The Primary Care of Chronic Open Angle Glaucoma Report to the Royal College Ophthalmologists Samya Riad – University College London Hospital Supervisor: Richard Wormald – Moorfields Eye Hospital Introduction This report is directed to the primary care ophthalmologist. It is written in a way so that s/he is knowledgeable about the clinical work that needs to be undertaken in relation to glaucoma, the decisions that will have to be taken, mostly in isolation, the latest in evidence based medicine and clinical guidelines pertaining to glaucoma, the equipment needed to run a satisfactory service, the population s/he will serve, models in glaucoma care running in other parts of the UK, the views of her/his colleagues, his/her public health role in relation to glaucoma and finally, research gaps to which s/he may wish to contribute. The report is in three major divisions. The first consists of the clinical aspect of the primary care of chronic open angle glaucoma and its evidence base. The second includes policy aspects, most official documents and government sponsored initiatives and the projected prevalence of chronic open angle glaucoma in the different administrative areas of the UK. The third division contains models of glaucoma delivery in the UK and the views of consultants and optometrists on current trends in glaucoma care and future direction. In this report, complete references are placed within the text and not at the end, as traditional. This will allow the reader to know the source immediately. Also, the major studies, the levels of evidence and the available clinical guidelines will be presented at the beginning of the report in order to inform the reader of these significant works from the start. Abbreviations The following abbreviations will be used in the text AGIS Advanced Glaucoma Intervention Study ALT Argon Laser Trabeculoplasty CCT Central Corneal Thickness CIGTS Collaborative Initial Glaucoma Treatment Study CNTGS Collaborative Normal Tension Glaucoma Study COAG Chronic Open Angle Glaucoma CSLTC Confocal Scanning Laser Tomography EMGTS Early Manifest Glaucoma Treatment Study FDT Frequency Doubling Technology GDX Generic Digital Crosspoint HFA Humphrey Field Analyser HRT Heidelberg Retina Tomograph HES Hospital Eye Service IOP Intraocular Pressure NFL Nerve Fibre Layer OAG Open Angle Glaucoma OH Ocular Hypertension OHTS Ocular Hypertension Treatment Study ON Optic Nerve PXE Pseudoexfoliation PDS Pigment Dispersion Syndrome POAG Primary Open Angle Glaucoma RCT Randomised Controlled Trial RNFL Retinal Nerve Fibre Layer VF Visual Fields Remit of the Primary Care Ophthalmologist Unlike his/her hospital colleagues, who usually work with other ophthalmologists, the primary care ophthalmologist will mostly work in isolation without the advantage of an immediate discussion, exchange of clinical views or a second opinion He or she therefore should be trained to 1. 2. 3. 4. 5. 6. Master instruments Master clinical signs Know of the conditions that he is expected to refer to HES Know of the conditions that he is expected to discharge Know of the conditions that is expected to follow up Know of the conditions that he is expected to initiate treatment then refer to HES 7. Know of the conditions that he is expected to initiate treatment then retain in primary care 8. Know the risk factors for the condition 9. Know how to identify the risk factors for the condition 10. Appreciate the strength of the risk factor 11. Know and appreciate the risk factors for progression from ocular hypertension to glaucoma 12. Know and appreciate the risk factors for progression of glaucoma in case he/she is involved in a shared care scheme. 13. Select the appropriate equipment for his/her practice 14. Know of the performance and reliability of new equipment in order to make wise decisions 15. Understand his/her local population 16. In the absence of a national screening programme for glaucoma, find ways to enhance case finding the community where s/he works 17. To be update with current research and be able to participate 18. Train and direct his/her non medical team 19. Know of national models and trends for delivery of care in ophthalmology and of nation The Major Glaucoma Trials The following is a list of the major glaucoma studies that will be referred to the in this work as adapted from the European Glaucoma Society guidelines. Several publications have been published under each study but only the name of the study will be referred to the in the report. I. The Ocular Hypertension Treatment Study (OHTS) This is a multicentre, prospective study on patients with a normal ocular examination, except for elevated IOP between 24 and 32 mmHg in one eye and between 21 and 32 mmHg in the other eye. The purpose was to study differences in conversion rates to POAG between the natural history (no treatment) and versus treatment (IOP lowering treatment) in patients with elevated IOP (OH). II. Collaborative Initial Glaucoma Treatment Study (CIGTS) This is a randomised clinical trial on 607 patients with newly diagnosed open angle glaucoma. Initial treatment was either medication or trabeculectomy ( with or without 5- fluorouracil). III. Collaborative Normal Tension Glaucoma Study (CNTGS) This is a multicentre prospective randomized trial comparing treatment versus no treatment in normal tension glaucoma. The primary outcome measure was disease progression. IV. The Advanced Glaucoma Intervention Study (AGIS) This is a multicentre prospective randomised study on advanced open angle glaucoma patients who suffer from glaucoma that cannot be controlled by maximum tolerated medical therapy alone. The 591 patients of 35 to 81 years of age (789 eyes) were randomised between two treatment sequences for further interventions: argon laser trabeculoplasty → trabeculectomy → trabeculectomy (ATT) and trabeculectomy → argon laser trabeculoplasty → trabeculectomy (TAT). The second and third interventions were offered only after failure of the first and second interventions, respectively. V. Early Manifest Glaucoma Treatment Study (EMGTS) This is prospective randomised trial of treatment vs no treatment to evaluate the effectiveness of IOP reduction in early, previously untreated open angle glaucoma. Secondary aims were to assess factors related to glaucoma progression and to determine the natural history of the disease. During a population based screening among 44,243 residents in Sweden, 316 eyes of 255 patients were recruited. The Major Epidemiological Surveys There are seven major ophthalmic epidemiological studies to which there is reference throughout the report. The following summary was adapted from the work of the Eye Disease Prevalence Research Group* Name of Study Baltimore Eye Survey Barbados Study Beaver Dam Eye Study Blue Mountains Eye Study Proyecto Vision Evaluation Research Rotterdam Eye Study Vision Impairment Project Location Baltimore, Maryland, USA Barbados, West Indies Beaver Dam, Wisconsin, USA Sydney, New South Wales, Australia Nogales and Tucson, Arizona, USA Year Conducted 1985 -1988 Number of Participants 5308 1988 -1992 4314 1988 - 1990 4585 1992 - 1994 3632 1999 - 2000 4773 Rotterdam, The Netherlands Melbourne, Victoria, Australia 1990 - 1993 6774 1991 - 1998 4652 *Friedman DS, Wolfs RC, O'Colmain BJ, Klein BE, Taylor HR, West S, Leske MC, Mitchell P, Congdon N, Kempen J; Eye Diseases Prevalence Research Group. Prevalence of open-angle glaucoma among adults in the United States. Arch Ophthalmol. 2004 Apr;122(4):532-8. The Clinical Guidelines The following is a list of all clinical guidelines that were identified worldwide and relating to chronic open angle glaucoma. They are all available on the website of the respective organisations except for one guideline* which was published in a peer reviewed journal. They are presented in descending order of their year of publication. 1 2 3 4 5 6 7 8 9 Title Organisation Year Primary Open Angle Glaucoma (Initial Evaluation) Primary Open Angle Glaucoma (Follow up Evaluation) Primary Open Angle Glaucoma Suspect (Initial and Follow up Evaluation) Primary Open Angle Chronic Glaucoma, Normal Tension Glaucoma, and Ocular Hypertension (In German) International Council of Ophthalmology 2007 Country/ Region Belgium International Council of Ophthalmology 2007 Belgium International Council of Ophthalmology Not Stated Belgium German Society of Ophthalmology 2006 Germany Primary Open Angle Glaucoma – Preferred Practice Pattern Primary Open Angle Glaucoma Suspect – Preferred Practice Pattern Glaucoma Guidelines for the Management of Open Angle Glaucoma and Ocular Hypertension Asia Pacific Glaucoma Guidelines American Academy of Ophthalmology 2005 USA American Academy of Ophthalmology 2005 USA Ministry of Health The Royal College of Ophthalmologists 2005 2004 Singapore UK SEAGIG (South East Asia Glaucoma Interest Group) with support of AOGS (Asia 2003 2004 Asia Pacific Region 10 Terminology and Guidelines for Glaucoma 11 The Finnish Evidence Based Guideline for Open Angle Glaucoma* 12 Care of the Patient with Open Angle Glaucoma Oceanic Glaucoma Society) European Glaucoma Society 2003 Europe Finnish Ophthalmologic Society & The Finnish Glaucoma Society 2003 Finland American Optometric Association 2002 USA * Tuulonen A, Airaksinen PJ, Erola E, Forsman E, Friberg K, Kaila M, Klemetti A, Mäkelä M, Oskala P, Puska P, Suoranta L, Teir H, Uusitalo H, Vainio-Jylhä E, Vuori ML. The Finnish evidence-based guideline for open-angle glaucoma. Acta Ophthalmol Scand. 2003 Feb;81(1):3-18. The following guidelines will be quoted repeatedly in the report and will be referred to as follows ICO – International Council of Ophthalmology (any of the three guidelines) AAO – American Academy of Ophthalmology; Primary Open Angle Glaucoma – Preferred Practice Pattern Singapore - Singapore Ministry of Health; Glaucoma RCOphth – The Royal College of Ophthalmologists; Guidelines for the Management of Open Angle Glaucoma and Ocular Hypertension Asia Pacific - South East Asia Glaucoma Interest Group; Asia Pacific Glaucoma Guidelines European Glaucoma Society – European Glaucoma Society; Terminology and Guidelines for Glaucoma Finland - Finnish Ophthalmologic Society & The Finnish Glaucoma Society; The Finnish Evidence Based Guideline for Open Angle Glaucoma AOA - American Optometric Association; Care of the Patient with Open Angle Glaucoma Levels of Evidence and Recommendations In this report, the general principles of SIGN’s (Scottish Intercollegiate Guidelines Network) levels of evidence and recommendations will be used. These have been adapted to suit the circumstances under which this report was prepared. For the level of evidence, every attempt was made to comply with the SIGN ratings but sometimes, especially when a general review was summarised, the quality of the studies it quoted and sometimes their design, was not known to the author. Also, on some occasions, there were too few studies for the author to be able to evaluate the evidence. This will be evident in the text. As for the recommendations, SIGN’s recommendations are based on the level of evidence and should be decided by a panel of experts. This was not available at this stage of the work, and therefore it should be stressed that the recommendation included is only approximate and based on discussions between the author and the supervisor and should not be taken as the final recommendation but only an approximate guideline. The following are the levels of evidence and recommendations that have been adapted from the SIGN ratings. SIGN Levels of Evidence Level 1 High quality or well conducted meta-analysis, systematic review of RCTs, or RCTs with a very low risk of bias Level 2 High quality systematic reviews of case control or cohort studies, or high quality or well conducted case control or cohort studies with a low risk of confounding, bias or chance and a high or moderate probability that the relationship is causal. Level 3 Non analytic studies example case reports or case series Level 4 Expert opinion SIGN Grades of Recommendation A At least one high quality meta-analysis, systematic review or directly applicable to the target population or a body of evidence consisting principally of level 1 studies, directly applicable to the target population and demonstrating overall consistency of results. B A body of evidence including high quality level 2 studies, directly applicable to the target population and showing overall consistency of results or extrapolated evidence from medium or poor quality level 1 studies C A body of evidence including medium quality level 2 studies, directly applicable to the target population and showing overall consistency of results or extrapolated evidence from high quality level 2 studies D Evidence level 3 or 4 or extrapolated evidence from medium quality level 2 studies Other Ratings Four of the clinical guidelines that were presented previously have given levels of evidence and recommendations to some of their statements. Each used different ratings and no attempt will be made to compare them to each other or to SIGN ratings. In the event of level of evidence or recommendation quoted from these guidelines, the reader is advised to refer to the definitions given below. It should be noted that whereas SIGN, Singapore and Finland base their recommendations on the level of evidence, ICO and AAO base it on its importance to the care process. ICO Ratings Levels of Evidence: I: Strong, II: Substantial but lacks some of I, III: consensus of expert opinion in absence of evidence for I & II Grades of recommendation: A: Most important, B: Moderately important, C: Relevant but not critical AAO Ratings Levels of Evidence Level I includes evidence obtained from at least one properly conducted, welldesigned, randomized, controlled trial. It could include meta-analyses of randomized controlled trials. Level II includes evidence obtained from the following: Well-designed controlled trials without randomization Well-designed cohort or case-control analytic studies, preferably from more than one center Multiple-time series with or without the intervention Level III includes evidence obtained from one of the following: Descriptive studies Case reports Reports of expert committees/organizations (e.g., PPP panel consensus with peer review) Grades of Recommendation These recommendations are based on “importance to the care process” and their ratings represent care that the panel thought would improve the quality of the patient’s care in a meaningful way. The recommendations of importance are divided into three levels. Level A, defined as most important Level B, defined as moderately important Level C, defined as relevant but not critical Singapore Ratings Levels of Evidence Ia Evidence obtained from meta-analysis of randomised controlled trials. Ib Evidence obtained from at least one randomised controlled trial. IIa Evidence obtained from at least one well-designed controlled study without randomisation. IIb Evidence obtained from at least one other type of well-designed quasi-experimental study. III Evidence obtained from well-designed non-experimental descriptive studies, such as comparative studies, correlation studies and case studies. IV Evidence obtained from expert committee reports or opinions and/or clinical experiences of respected authorities. Grades of Recommendation A (evidence levels Ia, Ib) Requires at least one randomised controlled trial as part of the body of literature of overall good quality and consistency addressing the specific recommendation. B (evidence levels IIa, IIb, III) Requires availability of well conducted clinical studies but no randomised clinical trials on the topic of recommendation C (evidence level IV) Requires evidence obtained from expert committee reports or opinions and/or clinical experiences of respected authorities. Indicates absence of directly applicable clinical studies of good quality GPP (good practice points) Recommended best practice based on the clinical experience of the guideline development group. Finland Ratings Depending on the quality and size of original studies, the strength of each statement is graded from A to D. Level A represents ‘strong research based evidence’, that is multiple, relevant, high-quality studies with homogenous results (e.g. two or more randomized, controlled trials), or a systematic review with clearly positive results. Level B represents ‘moderate evidence’ (e.g. one randomized, controlled trial, or multiple adequate studies). Level C represents ‘limited research-based evidence’ (e.g. open, controlled, prospective studies). Level D represents ‘no evidence’ (e.g. retrospective studies, or the consensus reached by the group in the absence of good quality evidence). Recommendations for action are then formulated based on the studies of highest quality. Division One The Evidence Based Content of the Primary Care of Chronic Open Angle Glaucoma Method Definition Health Education Screening Prevalence Risk Factors Detection Method 1. The elements and content of the primary care of chronic open angle glaucoma were compiled, based on the following definition and on current clinical practice “Ophthalmic primary care is the provision of first contact care for all ophthalmic conditions and the follow up, preventive, and rehabilitative care of selected ophthalmic conditions. It can be delivered in a variety of settings and by a diverse workforce, but in strict, efficient, and timely coordination, to attain the best clinical outcome possible for the patient. A service is designated as ophthalmic primary care, only if appropriately integrated with the patient’s main primary care provider, in order to ensure continuity, longitudinality, and comprehensiveness in the overall care of the patient. The primary care ophthalmic service itself should be accessible, equitable, knowledgeable, responsive, and efficient. In these aims, it is supported by the population sciences which identify the medical and service needs of the population served.”* 2. Each section starts by the reason why it is included in the report which is also an explanation of its relevance to primary care. 3. A key question is asked on each topic, which is then discussed using the following method a. If an evidence synthesis report of good quality is available, its results are summarised and the subject is not taken further. b. If there is no evidence synthesis report, and a general review is available, then it is summarised. c. If the evidence synthesis report or the general review are found to be lacking on certain points, then the relevant publications are added and summarised. d. If there are no reports or reviews, then the relevant significant literature is summarised. e. If relevant, the evidence level is given at the end of the summary of the publication and the grade of recommendation is given at the end. f. The reference of each of the clinical guidelines to the topic is included either if it adds to the discussion or to demonstrate the significance of the topic. The extent of the inclusion of the guidelines differs from one section to the other as necessary and as will be evident in the report. *Riad SF, Dart JKG, Cooling RJ. Primary care and ophthalmology in the UK. Br J Ophthalmol (2003); 87:493-499. Definitions Why is this section included in the report? A precise definition of chronic open angle glaucoma and its related conditions is needed for the ophthalmologist who will work in a primary care setting and whose remit will partly be to decide on which cases to refer to the hospital eye service and which to retain in primary care, based on a reliable definition. Ophthalmic primary care, as an embryonic ophthalmic subspecialty, will need to develop its own identity and its practitioners will need to see their duties based on a scientific definition rather than a set of guidelines. A precise definition will also define the boundaries of primary care thus precluding it from encroaching on patient care that needs to be delivered in the hospital eye service. Background The lack of consistency on how glaucoma is defined in clinical research has been long recognised1,2. Krause and Burton3 in 20033 argued that the absence of an agreed detailed case definition for POAG that can be applied in clinical practice results in considerable uncertainty about the diagnosis of this condition. Clinical definitions of chronic open angle glaucoma and its related conditions have been included in clinical guidelines compiled worldwide. As will be seen, there are no fundamental differences between these definitions, because unlike definitions utilised in clinical research, they do not go to operational detail. Some may include more parameters than others, e.g. the reference to outflow facility by the Royal College of Ophthalmologists and the inclusion of the rapidly progressive form in the Finnish guidelines, but in general, there is an overall consensus of definition. Definitions of Chronic Open Angle Glaucoma and Related Conditions in Clinical Guidelines AAO 2005 Primary Open Angle Glaucoma Primary open-angle glaucoma is a progressive, chronic optic neuropathy in adults where intraocular pressure (IOP) and other currently unknown factors contribute to damage and in which, in the absence of other identifiable causes, there is a characteristic acquired atrophy of the optic nerve and loss of retinal ganglion cells and their axons. This is associated with an anterior chamber angle that is open by gonioscopic appearance. The Glaucoma Suspect A glaucoma suspect is an individual with clinical findings and/or a constellation of risk factors that indicate an increased likelihood of developing POAG. The clinical findings that define a glaucoma suspect are characterized by one or more of the following in an individual with open anterior-chamber angles by gonioscopy: 1. appearance of the optic disc or retinal nerve fibre layer that is suspicious for glaucomatous damage, 2. a visual field suspicious for glaucomatous damage and 3. consistently elevated intraocular pressure (IOP) associated with normal appearance of the optic disc and retinal nerve fibre layer and with normal visual field test results. The following have been implicated as important risk factors in the development of glaucomatous optic nerve damage: 1. elevated IOP measurement, 2. Older age, 3. family history of glaucoma, 4. African or Hispanic/Latino descent and 5. thinner central corneal thickness. This definition excludes known secondary causes for potential open-angle glaucoma, such as pseudoexfoliation, pigment dispersion and traumatic angle recession Singapore 2005 Primary Open Angle Glaucoma Glaucoma is an optic neuropathy with characteristic changes in the optic nerve head and visual field. Raised intraocular pressure (IOP) is the main risk factor for the development and progression of this disease. Normal Tension Glaucoma Normal tension glaucoma (NTG) is an important subtype of POAG, in which the IOPs are consistently within the statistically normal population range. .RCOphth 2004 Ocular Hypertension Ocular hypertension (OHT) is a term reserved for eyes in which the intraocular pressure (IOP) lies above the normal population range, the optic nerve and visual field show no signs of glaucomatous damage, and there is no ocular co-morbidity. Excluded from this definition are eyes with raised IOP from demonstrable causes such as pseudoexfoliation and pigment dispersion syndrome. Primary Open Angle Glaucoma Primary open angle glaucoma (POAG) is a chronic progressive condition with characteristic changes at the optic disc (glaucomatous excavation), where it is usually possible to identify reduced visual function related to the disc changes. In most patients, the IOP is above the normal range (i.e. over 21 mmHg) at some time of the day, usually being highest in the morning. In addition, there is a gonioscopically open angle indistinguishable from normal and, in those eyes with elevated IOP, a reduced facility of outflow. Normal tension glaucoma Apart from the finding of an IOP that does not exceed 21 mmHg, this form of open angle glaucoma may be indistinguishable from its higher pressure variant. European Glaucoma Society 2003 Ocular Hypertension (Compiled Definition) A condition of unknown aetiology and unknown pathomechanism where the peak IOP is more than 21 mm Hg without treatment (diurnal curve), the visual fields are normal, the optic disc and retinal nerve fibre layer are normal and gonioscopy shows an open anterior chamber angle. There is no history or signs of other eye disease or steroid use and there are no other risk factors. Primary Open Angle Glaucomas The open angle glaucomas are chronic progressive optic neuropathies, that have in common characteristic morphological changes at the optic nerve head and retinal nerve fibre layer in the absence of other ocular disease or congenital anomalies. Progressive retinal ganglion cells death and visual field loss are associated with these changes. The relative risk for POAG rises continuously with the level of the intraocular pressure (IOP), and there is no evidence of a threshold IOP for the onset of the condition. It is presumed that risk factors other than IOP have a relatively greater importance if there is glaucomatous optic neuropathy at the lower (statistically ‘normal’) pressure levels. POAG had been arbitrarily divided into High Pressure and Normal Pressure disease to reflect this, even though they may represent a spectrum of optic neuropathies variably sensitive to the IOP. Asia Pacific 2003 -2004 Primary Open Angle Glaucoma Chronic progressive optic neuropathy with characteristic changes with characteristic changes in the optic nerve head and/or visual field in the absence of secondary causes Ocular Hypertension Intraocular pressure more than two standard deviations above the population mean with open angles and no evidence of glaucomatous optic neuropathy or visual field loss (with normal central corneal thickness). Normal Pressure Glaucoma Characteristic glaucomatous optic neuropathy in the presence of statistically normal intraocular pressure Finland 2003 Glaucoma is a progressive neuropathy of the optic nerve with typical structural and functional abnormalities in the optic disc, retinal nerve fibre layer and visual field. In the majority of patients, the glaucomatous abnormalities progress slowly over the years. In a minority of patients, the disease may, however, lead to serious optic nerve damage within just a few months. AOA 2002 Primary Open Angle Glaucoma, Ocular Hypertension and Normal Tension Glaucoma POAG is a chronic, progressive disease that most often presents with characteristic optic nerve (ON) damage, nerve fibre layer (NFL) defects, and subsequent visual field (VF) loss. OAG occurs primarily in adults and is generally bilateral, but not always symmetrical, in its presentation. The majority of persons with POAG have elevated intraocular pressure (IOP). Although 21 mm Hg is considered the upper limit of statistically normal IOP, at least one-sixth of patients with POAG have IOP levels below 21 mm Hg, which is considered statistically normal in the 95th percentile range. Moreover, some whose IOP levels are statistically abnormal (>21 mm Hg) have no evidence of ON damage or loss of vision function, a condition known as ocular hypertension (OH). OAG in which the IOP is typically below a certain level, typically 21 mm Hg, is known as low tension or normal tension glaucoma (NTG). The Primary Care Perspective The above definitions are more useful in a hospital setting where a clear cut designation of the patient under a classification scheme is not as important for decision making. However, for the primary care ophthalmologist, in a community or a referral refinement setting, who is looking for an operational definition, in order to make referral decisions, a precise definition is important. For example, the Royal College of Ophthalmologists specifies that for the diagnosis of ocular hypertension, there should be no associated ocular morbidity. This may give rise to a situation where the primary care ophthalmologist is faced with a patient who fulfils all the criteria for a diagnosis of ocular hypertension, but has early lens changes, senile macular degeneration or an old corneal scar. Definitions for ophthalmic primary care will require attention to details like levels of IOP, the evidence based significance of the different risk factors, the interpretation of the optic disc characteristics and visual field changes in the detection phase of the disease. As will be seen later, such evidence is not always available, which constitutes a challenge in the development of such guidelines. References 1. Bathija R, Gupta N, Zangwill L, et al. Changing definition of glaucoma. J Glaucoma 1998;7:165–9 2. Foster PJ, Buhrmann R, Quigley HA, et al. The definition and classification of glaucoma in prevalence surveys. Br J Ophthalmol 2002;86:238–42 3. Kroese M, Burton H. Primary open angle glaucoma. The need for a consensus case definition. J Epidemiol Community Health 2003;57:752–754 Health Education Why is this section included in this report? Health education is included in this report because, in the absence of a national screening programme for glaucoma, education of subjects at risk of developing glaucoma is a significant pathway for the identification of glaucoma cases and glaucoma suspects at the primary care level. If persons at risk are made aware of their position and advised to seek regular examination with the optometrist, then this will contribute to the identification of patients at an early stage of the disease. Health education targets the population hence its inclusion in primary care. Key Questions Question 1 – Is there evidence that the population in the UK or a comparable society is aware about glaucoma and its risk factors? Evidence Synthesis – There is no evidence synthesis report on this question. The Literature Michielutte R, Diseker RA, Stafford CL, Carr P. Knowledge of diabetes and glaucoma in a rural North Carolina community. J Community Health. 1984 Summer;9(4):269-84. This is a telephone survey of residents in one rural community to determine knowledge, attitudes, and practices concerning diabetes and glaucoma. Results of the survey indicated that the level of knowledge for both diabetes and glaucoma is particularly low with respect to identification of high-risk groups and symptoms; the lowest levels of knowledge were observed in the youngest and oldest respondents, males, the unmarried, and those with low levels of educational attainment. Level of Evidence - 3 Livingston PM, Lee SE, De Paola C, Carson CA, Guest CS, Taylor HR. Knowledge of glaucoma, and its relationship to self-care practices, in a population sample. Aust N Z J Ophthalmol. 1995 Feb;23(1):37-41. A cluster sample of 1711 persons of Melbourne population 40 years and older was interviewed. Seventy per cent of the sample had heard of glaucoma. However, only 22% provided a description that demonstrated a reasonable understanding of the disease. A lack of awareness and knowledge of glaucoma appeared to be negatively related to self-care practices. Level of Evidence - 3 Attebo K, Mitchell P, Cumming R, Smith W. Knowledge and beliefs about common eye diseases. Aust N Z J Ophthalmol. 1997 Nov;25(4):283-7. A population based survey of an urban Australian population aged 49 years or older to ascertain knowledge of common causes of blindness. Awareness of glaucoma was 93%, however among those who were aware of glaucoma only 29% showed some knowledge of glaucoma. Those who were aware and had some knowledge of eye disease accessed eye care services more frequently. Level of Evidence - 3 Pfeiffer N, Krieglstein GK, Wellek S. Knowledge about glaucoma in the unselected population: a German survey. J Glaucoma. 2002 Oct;11(5):458-63. A total of 2,742 persons aged 14 to 93 years, representative of the German populations, were interviewed face to face to determine their knowledge about nature, occurrence and possible risk factors of glaucoma. Fifty one percent had knowledge of the term glaucoma when asked about eye disease. Seventy five percent had heard about glaucoma when asked specifically about it. Twenty-five percent of respondents assumed that all people are equally at risk, and 21% thought that relatives of glaucoma patients carry a higher risk. Age was recognized as a risk factor by 12% (over 40 years), 32% (over 60 years) and 4% (over 80 years) Level of Evidence - 3 Mansouri K, Orgul S, Meier-Gibbons F, Mermoud A. Awareness about glaucoma and related eye health attitudes in Switzerland: a survey of the general public. Ophthalmologica. 2006;220(2):101-8. A cluster random sample of 502 individuals between the age of 35 and 70, representing urban and rural populations was interviewed by telephone to assess their level of awareness about glaucoma. In total, 76% of respondents did not have any (or any correct) association with the term 'glaucoma'. Only 24.7% of the interviewees could describe glaucoma as an eye condition. Awareness of glaucoma was independent of age, gender, educational status, and household income. Level of Evidence - 3 Noertjojo K, Maberley D, Bassett K, Courtright P. Awareness of eye diseases and risk factors: identifying needs for health education and promotion in Canada. Can J Ophthalmol. 2006 Oct ;41(5):617-23. This is a cross-sectional survey of 882 adult patients presenting to using selfadministered questionnaires of patients presenting to 33 family practitioners' offices in British Columbia. Overall, 41.2% reported familiarity with glaucoma. Women were 1.6 times more likely than men to report familiarity with glaucoma. Respondents with university education were 1.8 times more likely to report familiarity with glaucoma than were those with no family education. Canadians with European descent were 2.9 times more likely to report familiarity with glaucoma than were non-European descent Canadians. Family history was recognized by only 23% of respondents. Women, those of European ancestry and those with university education were more likely to recognise family history as a risk factor for glaucoma. Medications were recognised as a risk factor by 4.4% of respondents. Level of Evidence - 3 Question 2 - Is there evidence that subjects at risk of developing glaucoma in the UK or a comparable society are aware of the need for regular eye examination? Evidence Synthesis – There is no evidence synthesis report on this question. The Literature Eke T, Reddy MA, Karwatowski WS. Glaucoma awareness and screening uptake in relatives of people with glaucoma. Eye. 1999 Oct;13 ( Pt 5):647-9 Seventy first degree relatives of glaucoma patients in Leicester, aged over 40 years, were identified and returned a questionnaire on glaucoma awareness and screening uptake. Only 53% thought they were at increased lifetime risk of developing glaucoma. Level of Evidence - 3 Landers JA, Goldberg I, Graham SL. Factors affecting awareness and knowledge of glaucoma among patients presenting to an urban emergency department. Clin Experiment Ophthalmol. 2002 Apr;30(2):104-9. A total of 240 patients, with no previous history of glaucoma or ocular hypertension, presenting to an urban hospital emergency department in Sydney, Australia were surveyed with a brief questionnaire to assess their knowledge of glaucoma. Data was collected about their gender, age, family history of glaucoma and presence of systemic hypertension, diabetes, Raynaud's phenomenon, migraines and myopia. Women (Odds ratio 2.3), people who were 40 years or older (Odds ratio 2.2) and those who were aware of a family history of glaucoma (Odds ratio 15.7) knew significantly more about the disease than others, while people with other risk factors did not demonstrate significantly greater knowledge. Level of Evidence - 2 Question 3 – Is there evidence that subjects who are aware of being at risk of developing glaucoma in the UK or a comparable society are attending for screening? Evidence synthesis – There is no evidence synthesis report on this question. The Literature In the study by Eke et al, 1999, above, uptake of regular, free glaucoma screening at least every 2 years was 57% among offspring and 30% among siblings. The responses of patients' siblings and patients' offspring were compared and revealed that perceived lifetime glaucoma risk was similar in the two groups, but the (older) siblings had a significantly lower awareness of the free screening service and attended for screening less frequently. Uptake of regular, free glaucoma screening at least every 2 years was 57% among offspring and 30% among siblings. Level of Evidence - 3 Question 4 – Is there evidence of an intervention in the UK or a comparable society which has been successful in increasing awareness of glaucoma risk or the need for seeking regular eye examination by those at risk? Evidence synthesis – There is no evidence synthesis report on this question. The Literature Baker H, Murdoch IE. Can a public health package on glaucoma reach its target population? Eye. 2004 May;18(5):478-82. A pilot study was conducted to assess how successful an advertisement in a local newspaper and an interview on local radio about glaucoma are at reaching their target population. The target population were residents aged 45 years and above in Southall in the West of London and the Isle of Wight. In Southall, a convenience sample was taken from local temples and the high street, the majority of which was of Indian ethnicity. In the Isle of White, the sample was taken from the main town centre and it was 100% Caucasian. Using a pre and post intervention questionnaire, it was found that the proportion who had heard of glaucoma increased from 27 % before the intervention to 40% after the intervention in Southall and from 71% to 79% in the Isle of White. On the Isle of White, females were more knowledgeable and responded more positively to the intervention. This differed in Southall where males tended to be the positive responders. The increase in the proportion of those who had heard of the disease was attributed to both the advert and interview in Southall but to the newspaper advertisement alone on the Isle of White, as only 3% of respondents reported hearing the radio interview. In a complete logistic regression model with ‘heard of glaucoma’ as the outcome, adjusting for age, gender and intervention, the only important factor was the intervention. Level of Evidence - 2 Screening Why is this section included in the report? Screening tests are population based hence the inclusion of screening in the primary care of chronic open angle glaucoma. The term ‘glaucoma screening’ is sometimes used in the hospital setting to refer to the examination of patients referred from the community in order to categorise them into normal individuals, glaucoma suspects or glaucoma patients. Obviously, these are the patients who were suspected to have glaucoma in the community via opportunistic case finding or suggestive symptoms. True screening will examine all individuals in the community who are at risk of developing glaucoma and not only those who have been referred to the hospital eye service. As screening is a major primary care subject, it will be presented in a different format. It will inform the reader of the definition, measures, criteria and basics of screening, the situation in the United Kingdom, the international scenario and finally opinions of authors who have written on the subject. The Definition of Screening The UK National Screening Committee defines screening as a public health service in which members of a defined population, who do not necessarily perceive that they are at risk of, or are already affected by a disease or its complications, are asked a question or offered a test, to identify those individuals who are more likely to be helped than harmed by further tests or treatment to reduce the risk of a disease or its complications1. The Measures of Screening Wormald2 explained the measures of the process of screening as follows. The validity of a test is its ability to differentiate correctly between those who have the disease and those who do not. Two kinds of error, false-positive and false negative, may occur, both of which are important in a screening programme.. Sensitivity (detection rate) is the proportion of persons with the disease that the test correctly identifies. Thus the sensitivity of a test is a measure of its ability to detect disease in those who are affected. Specificity (true-negative rate) is the proportion of persons who are disease-free that the test identifies as normal. Thus the specificity of a test is a measure of its ability to identify correctly those who are disease-free. The relation between sensitivity and specificity is important. Increasing the sensitivity of a test will usually be at the expense of specificity, and vice versa. The computation of these test parameters depends upon the existence of a gold standard that can determine the truth with regard to the disease status of the participants. This can be problematic in some situations, for example when it is hard to categorise individuals clearly as diseased and nondiseased, or when the case definition is imprecise. This is particularly true for glaucoma. In nature, few diseases demonstrate a clear step from being diseasefree to being affected. Usually there is a continuum between health and disease, particularly for chronic or degenerative disease. Thus, an arbitrary judgment based on practical considerations must be made in order to decide when the transition from health to disease has occurred. Positive predictive value (PPV) is the probability of being disease-positive if the test is positive. This is an important parameter because it reveals the amount of work the screening test will generate at the referral centres and the number of persons who will be unnecessarily referred for further examination. It is determined by the falsepositive rate but also influenced by the prevalence of the disease. It can also be described as the conditional probability of being disease-positive if the test is positive. This can be expressed as: PPV = (sensitivity x prevalence) divided by the probability of a positive test. It is the combined probability of the test detecting a case when among known cases (i,e. the sensitivity) and the probability of the individual being a case in the target population (the prevalence) divided by the overall probability of a test being positive in the population. Thus even when the test sensitivity is high, if the prevalence is low so also will be the PPV. Negative predictive value (NPV) is the probability of being diseasenegative if the test is negative. This is relevant to the concerns of screened individuals, and influences the degree of assurance that the screened negative person can assume when the test is negative. Like PPV, it is prevalencedependent. When the prevalence is low, the NPV will tend to be high, even though the test may be quite insensitive. Yield is the number of persons screened to detect one case and is also dependent on prevalence of the disease in the population. Yield can be extended to include cost per yield and, further, cost per yield that are then successfully treated. Prevalence is the proportion of true cases in the population and is an important consideration in any screening programme because of its effect on PPV; but it is also a measure of the public health importance of the disease. A reasonably precise estimate of the prevalence of a disease is required before screening can be implemented. The reliability of a test is a product of the variation in the test results, whereas validity deals with the ability of the test to distinguish normal from abnormal. A reliable test gives consistent results when repeated on the same individual. It depends on the variation inherent in the test itself (sometimes termed reproducibility), which may be random or biological, and that introduced by the observer who conducts the test, which may be both random or systematic (intra- (within) and inter (between) observer variation).The sources of variation can be the subject or the instrument. Coverage is the proportion of the population at risk who are screened during anyone trawl. Acceptability of the screening test is of importance. An unpleasant, painful or invasive test will deter response. The target population must be properly informed about the nature and purpose of the screening test so that they can clearly understand that there is a real benefit to be derived from attending the screening examination. Access to the screening site must be optimal. Long and costly travel to the site will deter attendance. Ideally, screening should be available within the community of the target population, outside the hospital setting (which is associated with fear and disease), and preferably in the primary care setting where individuals are used to having contact with healthcare services. Feedback, explanation and reassurance about the outcome of the examination are essential for all individuals so that the word spreads in the community that attending the screen is a positive experience. The Basics of Screening for Glaucoma Quigley3reviewed the subject and highlighted the following screening elements that need to be taken into account in a glaucoma screening programme Parameters used for screening differ in different populations The instruments used must be reliable The personnel who will perform the tests must be experienced New perimetry tests for screening that were found promising when evaluated on experienced patients in the clinic where found to have lower specificity and sensitivity when used on populations with no past experience New perimetry tests for screening may be ignored because they were tested against a gold standard that is less effective in detecting new cases. The true cases identified by the new perimeter may be classified as false positives. Glaucoma for screening purposes needs to defined with rigour Some persons will be screened positive because they have other eye disease These usually represent an increased yield because major eye disease has been detected Cost should refer to the cost of the finished test including purchase price, servicing, training cost, useful life, number of units needed for the programme and associated costs e.g. printer and paper. The test should be fast The test should be acceptable to the individuals being screened in terms of not being painful, frightening, frustrating or embarrassing. The predictive power of the test used in screening should be high The test should not be affected by the different types of populations being screened Tests that include pupil dilatation are time consuming, costly and carry the risk of precipitating acute closed angle glaucoma Tests that include dark adaptation are time consuming The instruments should be preferably portable The test should have well characterised output measures, which are easy to interpret and are not subjective Simple judgement should be required for the person being tested if the test includes a subjective element Training of the examiner is substantially simpler for tests with automated sequences than for those that are manually operated. The test should be appropriate for the stage of glaucoma that needs to be detected Immediate results are more useful Screening Tests for Glaucoma These have been discussed by Wormald2. The three tests necessary for the diagnosis of glaucoma, namely an lOP measurement, an optic disk examination and a visual field assessment, all perform poorly as single tests, with both low sensitivity and PPV. The combination of lOP and disk assessment only marginally improves the validity: and the current view of the American Academy of Ophthalmology is that all three tests should be performed routinely in the comprehensive eye examination. Despite it being clearly shown in 1966 by Hollows and Graham that the IOP is inadequate as a screening index, opportunistic testing for glaucoma in many circumstances relies on pressure measurement. Despite this inadequacy, it remains true that after age, a raised IOP is the single most significant risk factor for glaucoma. When found, a high IOP needs treating and the risk of developing glaucoma (if not already present) should be carefully assessed. Disk changes in glaucoma can be extremely subtle and are the domain of experienced glaucoma specialists who can detect potentially pathognomonic change. These changes are too subtle for use in screening, and agreement between specialists in recognizing them changes has been shown to be poor. The presence of a definite groove or defect in the nerve fibre layer, which can be sometimes seen with direct or indirect ophthalmoscopy (and better with a red-free filter), is a strong indicator of glaucoma and is very unlikely to be a falsepositive finding, even though it may precede the appearance of a definite abnormality of visual function. But the absence of a visible defect does not exclude glaucoma. Detection of an NFL defect requires good clarity of the optical media and usually a dilated pupil. To visualise an NFL groove easily may also require that the nerve fibre damage is focal and that the rest of the NFL is thick, young and healthy. None of these conditions make this technique likely to be suitable for screening in the community, although technological developments in this area may change this. The reliable demonstration of an abnormal visual function in screening for glaucoma is probably the best hope for the development of a screening tool. Visual function is traditionally assessed in glaucoma by plotting the visual field, and numerous methods now exist for the execution of this test. A major problem arises from the fluctuation in retinal sensitivity which is a normal feature of visual function. This variation is accentuated in glaucoma patients. The process of identifying the threshold of perception is an arduous task which requires many repetitions. These and other reasons are enough to exclude threshold testing as a possible screening tool, but suprathreshold techniques have been widely tested and show promise. The principle of this strategy is to reduce the false positive rate by looking only for marked focal reductions in retinal sensitivity. The price is some loss of sensitivity to the detection of early defects. Screening for Glaucoma in the United Kingdom and Worldwide Population screening for glaucoma has been rejected in the UK, USA, Quebec, Finland and Singapore. These are the countries that have recorded their experience or views, but it is also not known of any countries worldwide that have a national screening programme for glaucoma4. Screening for Glaucoma in the United Kingdom In the United Kingdom, the body responsible for screening is the UK National Screening Committee (NSC) which advises Ministers, the devolved national Assemblies and the Scottish Parliament on all aspects of screening policy5. The NSC assesses proposed new screening programmes against a set of internationally recognised criteria covering the condition, the test, the treatment options and effectiveness and acceptability of the screening programme6. In 2001, Spry and Sparrow evaluated open angle glaucoma against these criteria and found that some but not all criteria were met7. As a result, screening for open angle glaucoma was not offered by NSC. Currently another review commissioned by the Health Technology Assessment Programme of the Department of Health is being carried out by Dr Jennifer Burr, a clinical epidemiologist at the University of Aberdeen8. This review will include 1) a systematic review of screening and diagnostic strategies to determine the accuracy, reliability and acceptability of alternative strategies in different population groups in a UK setting, 2) an update of Cochrane reviews to assess short-term effects of alternative management strategies for glaucoma 3) a statistical modelling to extrapolate the effects of IOP changes on later visual impairment and 4) a systematic review of economic evaluations, followed by economic modelling of cost-effectiveness and cost-utility, if possible, of alternative approaches to screening. The forecast publication date is October 2007 Screening for Glaucoma in the United States of America In 2005, the US Preventive Services Task Force (USPSTF) found insufficient evidence to recommend for or against screening adults for glaucoma9. In 2007, the American Academy of Ophthalmology wrote to AHRQ (Agency for Healthcare Research and Quality), which sponsors the development of systematic evidence reviews, requesting a re-evaluation of the recommendations because of new evidence regarding screening for and treatment of glaucoma not available at the time of the USPSTF report and because of significant concerns regarding the scope and applicability of the USPSTF recommendation10. AHRQ responded that they would not re-evaluate glaucoma screening on a more rapid schedule and that they would clarify in the future that the scope of the report is not glaucoma screening by primary care clinicians, which is implied by the current title of the report. The Academy had proposed a screening benefit under Medicare where the ophthalmologist would be performing the screening in their office with appropriate staffing and supervision11. Screening for Glaucoma in Quebec, Canada In 1995, the Quebec Agency for Health Services and Technology Assessment (AETMIS) stated that a formal screening program for primary open angle glaucoma (POAG) could not be recommended for the province of Quebec, owing to “a high degree of uncertainty and because of the high cost such a program would entail.”12 An article in response to this decision was published in 2005 in the Canadian Journal of Ophthalmology to evaluate the possibility of instituting a POAG screening programme in light of recent advances in the diagnosis and treatment of glaucoma. Currently in Canada, screening for POAG (detecting glaucoma and ocular hypertension) generally occurs during routine clinical patient visits, without being part of a formal POAG screening protocol.12 Screening for Glaucoma in Finland The Finnish evidence based guideline for open angle glaucoma does not recommend mass screening in the public sector due to insufficient evidence for its cost effectiveness. Instead, it recommends that the Finnish people, at their own initiative, have an ocular examination performed by an ophthalmologist, from the age of 40-45 to 60 every 5 years and every 3 years for those above 6013. Screening for Glaucoma in Singapore The glaucoma guidelines by the Ministry of Health and the National Committee on Ophthalmology do not recommend routine population screening for glaucoma. However, high risk individuals may be considered as target populations for case detection programmes14. The Evidence Synthesis I The Agency of Healthcare Research and Quality15 The following eight key questions were assessed for evidence by the Agency for Healthcare Research and Quality. They include screening for ocular hypertension and primary open angle glaucoma. Key Question 1. Is there new evidence that screening for open angle glaucoma reduces severe visual impairment? Results: There are no studies assessing the screening and treatment of open-angle glaucoma in a population setting. Key Question 2 Is there new evidence that feasible screening tests are accurate and reliable in detecting increased intraocular pressure or open-angle glaucoma? Results: 1. Using current methods, optic nerve assessment is neither a practical nor reliable tool for population screening. 2. At the present time, perimetry has a limited role in population screening programmes because of the expense of equipment, the amount of time necessary for testing (up to 10-20 minutes per eye), and the relative lack of portability of most instruments. 3. Henson Visual Field Analyse is currently used in population screening and FDT is a promising instrument due to its portability, ease of administration and short time required for testing. Population studies are needed on these to instruments to determine their true performance as population tools. Key Question 3 Is there new evidence that treating increased intraocular pressure reduces the incidence of primary open angle glaucoma? The Ocular Hypertension Treatment Study (OHTS) has shown that over the duration of the study, the hazard ratio for progression of ocular hypertension to POAG in all treated vs. untreated participants was 0.40 and was 0.54 in treated vs. untreated blacks. Key Question 4 Is there new evidence that treating increased intraocular pressure reduces severe visual impairments? There were no studies that assessed the treatment of ocular hypertension using delay of progression to severe visual impairment as an endpoint. Key Question 5 Is there new evidence that treating open angle glaucoma with drugs, laser, and/or surgery reduces severe visual impairment? The Early Manifest Glaucoma Trial (EMGT) was a randomized clinical trial comparing treatment with no treatment in 255 individuals with early POAG. One hundred and twenty-nine participants were randomized to treatment with argon laser trabeculoplasty (ALT) and topical beta-blocker eye drops. The remaining 126 control participants received no treatment. At 48 months, the minimum planned follow up, 30% of treated subjects reached a progression endpoint vs. 49% of control subjects. In the Collaborative Normal-Tension Glaucoma Study (CNTGS), 145 eyes of 145 individuals with manifestations of POAG, but without recorded IOP elevation (>24 mm Hg) on repeated testing, were randomized to receive treatment with medications or surgery to lower IOP by 30%, or to receive no treatment. A total of 35 progression endpoints were observed. Seven of 61 eyes (12%) in the treated group reached progression endpoints compared with 28 of 79 (35%) in the untreated group. In the CNTGS study, 23 of 66 treated eyes (35%) developed loss of visual acuity due to cataracts, compared with 11 of 79 eyes in the control group (14%) The highest incidence of cataracts (16 of 33) occurred in the surgically treated eyes. The rate of cataract formation in untreated eyes was lower than surgically treated eyes, but was not significantly different from medically treated eyes. The first CNTGS paper indicates that IOP does play a pathogenic role in normaltension glaucoma. However, the results of the second paper31 do not indicate whether treating IOP would effectively reduce glaucoma progression in patients with NTG. In the EMGT study, secondary analyses show that increased IOP is a significant risk factor for progression. This indicates that treatment directed at lowering IOP is definitely beneficial for eyes with increased IOP, but of uncertain benefit in eyes with normal IOP. The Collaborative Initial Glaucoma Treatment Study (CIGTS), in which participants were randomized to treatment with surgical trabeculectomy or to a stepwise medication regimen, concluded that both medical and surgical treatment result in similar VF outcomes. They caution, however, that 4 to 5 years of followup in a chronic disease is not adequate to draw treatment conclusions. The Glaucoma Laser Treatment (GLT) study compared initial treatment with ALT to a stepwise regimen of topical and systemic ocular hypotensive medications. There were no observed differences between treatment groups in either visual acuity or visual field changes over 24 months. Key Question 6 Is there new evidence that screening results in adverse effects? Is screening acceptable to patients? There were no studies addressing the harms or acceptability of screening for ocular hypertension or POAG. Key Question 7 Is there new evidence that treatment of increased intraocular pressure and/or open-angle glaucoma results in adverse effects? In the OHTS, ocular symptoms occurred in 57% of treated patients and 47% of control subjects. Other symptoms, such as darkening of the eyelids or eyelash growth, were reported in 23% of treated patients vs.18% of control subjects. The CIGTS trial reported intraoperative and postoperative complication for surgical trabeculectomy in 525 participants. II The Cochrane Collaboration A Cochrane review16 was undertaken in 2006 to determine the impact of screening for OAG compared with opportunistic case findings or current referral practices on the prevalence of and the degree of optic nerve damage due to OAG in screened and unscreened populations. The authors pointed out that the challenge of screening for OAG is to detect the disease at a stage where it is sufficiently present to be accurately identified in those individuals who are at risk of going blind in their lifetime if left untreated. Detecting very early disease may not necessarily be the most effective and efficient way to screen if resources are to be focused on those at risk of blindness. Attempting to detect the condition in its very early stages is likely to generate more false positive errors and identify numerous people whose sight is not threatened. Ultimately, the effectiveness of screening as a means of preventing the adverse effects of a disease in a population can be demonstrated only by randomised trials of screening where individuals or clusters of individuals are randomised to be screened, or not, thereby testing the hypothesis that screened individuals will have a lower risk of suffering the effects of the disease than the unscreened individuals. The authors concluded that on the basis of current evidence, population-based screening for chronic OAG cannot be recommended, although much can be done to improve awareness and encourage at risk individuals to seek testing. III Centre for Reviews and Dissemination Two records on the cost effectiveness of screening were compiled by CRD commissioned reviewers according to a set of guidelines developed in collaboration with a group of leading health economists. The first record is for a study17 to determine the cost-effectiveness of glaucoma screening under 12 different scenarios. In scenario 1, screening is done every 3 years using both funduscopy and tonometry for people aged 40-79 years, the participation rate and compliance rate is 75% and treatment efficacy is 50%. In scenarios 2 and 3, all assumptions are the same as scenario 1, except that screening is carried out at 1 and 5 year intervals, respectively. Scenarios 4 to 9 vary the participation rate (60%, 75% and 90%), compliance rate (60%, 75% and 90%), and efficacy of treatment (30%, 50% and 70%). In scenario 10, the screening age is restricted to 65-79 years. Scenarios 11 and 12 assume that tonometry is the only screen used, and vary the ages from 40-79 years, and 65-79 years, respectively. The authors concluded that there is no proof that treatment of glaucoma would prevent blindness. Even when treatment efficacy is assumed to be as high as 50%, glaucoma screening programmes were not shown to be competitive with regard to cost-effectiveness. The second record is for a study18 to assess the cost-effectiveness of different modes of screening/case-finding for glaucoma defined in terms of various combinations of three main tests (ophthalmoscopy, tonometry and perimetry) with associated referral criteria (relatively lax or relatively severe). No specific mode of screening was regarded as a comparator. The authors concluded that "glaucoma screening of people over age 40 years could be justifiable, provided that it is worth more than about $850 (£548 at 1995 values) to detect a new case. The modes of glaucoma testing which can provide the best balance between sensitivity and cost are those which use ophthalmoscopy and tonometry routinely on patients over the age of about 40 years, together with perimetry either routinely or on glaucoma high risk groups. Screening is most likely to be economic when conducted (as systematised "case-finding") in conjunction with overall eye examinations, thus minimising the costs of ophthalmoscopy and overheads. The cost per glaucoma detected can be as low as $850 at 1995 prices, with sensitivity for those tested of >/= 80%. If the real worth of detecting a new case is considered likely to exceed this, there is reason to promote and improve potentially economic systems of detection. References 1. http://www.nsc.nhs.uk/whatscreening/whatscreen_ind.htm 2. Wormald P. Screening in Ophthalmology. In, The Epidemiology of Eye Diseases. GJ Johnson, DC Minassian, RA Weale, SK West (Eds). Arnold, London, 2003. pp 88-101. 3. Quigley HA. Current and future approaches to glaucoma screening. J Glaucoma. 1998 Jun;7(3):210-20. 4. Wormald RP, Rauf A. Glaucoma screening. J Med Screen. 1995;2(2):109-14.. 5. http://www.nsc.nhs.uk/uk_nsc/uk_nsc_ind.htm 6. http://www.nsc.nhs.uk/pdfs/criteria.pdf 7. Spry PGD; Sparrow JM. An Evaluation of Open Angle Glaucoma against the NSC Criteria for Screening Viability, Effectiveness and Appropriateness NSC, September 2001 8. http://www.hta.ac.uk/ProjectData/1_project_record_notpublished.asp?PjtId=1446 9. http://www.ahrq.gov/clinic/uspstf05/glaucoma/glaucrs.htm 10.http://www.aao.org/education/statements/loader.cfm?url=/commonspot/security/ge tfile.cfm&PageID=37601 11. (Personal Communication with AAO on June 12, 2007). 12. Harasymowycz P, Kamdeu Fansi A, Papamatheakis D. Screening for primary open-angle glaucoma in the developed world: are we there yet? Can J Ophthalmol. 2005 Aug;40(4):477-86. 13. Tuulonen A, Airaksinen PJ, Erola E, Forsman E, Friberg K, Kaila M, Klemetti A, Mäkelä M, Oskala P, Puska P, Suoranta L, Teir H, Uusitalo H, Vainio-Jylhä E, Vuori ML. The Finnish evidence-based guideline for open-angle glaucoma. Acta Ophthalmol Scand. 2003 Feb;81(1):3-18. 14. Ministry of Health. Glaucoma. MOH Clinical Practice Guidelines 3/2005. Singapore 2005. 15. Fleming C, Whitlock E, Beil T, Smit B. Primary Care Screening for Ocular Hypertension and Primary Open-Angle Glaucoma: Evidence Synthesis. Agency for Healthcare Research and Quality. Evidence Synthesis no.34. 16. Hatt S, Wormald R, Burr J. Screening for prevention of optic nerve damage due to chronic open angle glaucoma. Cochrane Database Syst Rev. 2006 Oct 18;(4):CD006129 17. Boivin J F, McGregor M, Archer C. Cost effectiveness of screening for primary open angle glaucoma. Journal of Medical Screening, 1996; 3(3): 15463.16. 18. Tuck M W, Crick R P. The cost-effectiveness of various modes of screening for primary open angle glaucoma. Ophthalmic Epidemiology, 1997; 4(1): 3-17 , , Prevalence Why is Prevalence included in the report? The primary care ophthalmologist should be aware of the prevalence of glaucoma in the community that he serves for the following reasons: 1) for planning, 2) for research, 3) for making informed decisions about capacity, and 4) for making a case for his services and his needed workforce. Background There is sufficient evidence in the literature that the prevalence of glaucoma differs according to race and according to age. Therefore, in order to estimate the prevalence of chronic open angle glaucoma with optimum accuracy in a defined population, the prevalence rates within the different subgroups and the distribution of these subgroups within the population need to be known. In another part of this report, these calculations for the populations of the different primary care trusts will be presented. In this section, the results of prevalence surveys will be reviewed. There are prevalence surveys from many parts of the world. For the purpose of this work, we will only include results from prevalence surveys of races that are present in significant numbers in the United Kingdom namely 1. 2. 3. 4. 5. 6. 7. Whites Blacks Mixed Races Indians Pakistani Bangladeshi Chinese Key Question What is the prevalence of glaucoma in white, black, mixed black, Indians, Pakistanis, Bangladeshis and Chinese races in age groups above 40 years old? Evidence Synthesis There are two meta-analyses on the prevalence of glaucoma in the different races. Friedman DS, Wolfs RC, O'Colmain BJ, Klein BE, Taylor HR, West S, Leske MC, Mitchell P, Congdon N, Kempen J; Eye Diseases Prevalence Research Group. Prevalence of open-angle glaucoma among adults in the United States. Arch Ophthalmol. 2004 Apr;122(4):532-8. Rudnicka AR, Mt-Isa S, Owen CG, Cook DG, Ashby D Variations in primary open-angle glaucoma prevalence by age, gender, and race: a Bayesian meta-analysis. Invest Ophthalmol Vis Sci. 2006 Oct; 47(10):4254-61 The first study was conducted by an international research group and calculated prevalence for the purpose of estimating the prevalence and distribution of open angle glaucoma in the United States. They therefore concentrated on eight studies that were found useful for this purpose. The second study is more recent and was conducted in the UK (St George’s and Queen Mary’s, University of London). Forty-six published observational studies of OAG prevalence (103,567 participants with 2509 cases of OAG) were included. The results of the two studied were close and the results of the second study will be presented in this work. Age Range in Years Predicted Prevalence of OAG (95% Credible Interval) White Black Asian 30 - 39 1.8 (1.2 – 2.7) 0.4 (0.3 – 0.6) 40 - 49 0.4 (0.3 – 0.6) 2.9 (1.9 – 4.4) 0.6 (0.4 – 1.0) 50 - 59 0.8 (0.5 – 1.2) 4.6 (3.1 – 6.8) 1.0 (0.6 – 1.6) 60 - 69 1.6 (1.1 – 2.5.) 7.2 (4.9 – 10.6) 1.6 (1.0 – 2.4) 70 - 79 3.3 (2.2 – 4.9) 11.2 (7.6 – 16.1) 2.5 (1.6 – 3.8) 80 - 89 6.6 (4.4 – 9.7) 16.9 (11.7 – 23.8) 3.8 (2.3 – 5.9) 90 - 95 10.8 (7.2 – 15.8) 22.5 (15.7 – 31.2) The pooled random effects prevalence estimates of OAG for those above 40 years of age is 1.4% (95% CI, 1.0% – 2.0%) in Asian populations, 4.2% in black populations (95% CI, 3.1% - 5.8%) and 2.1% (95%CI, 1.6% - 2.7%) in white populations. It will be noticed that the authors have placed all Asians in one category. No reason was given for this, but the following tables, compiled by the author of this report, show that overall, the prevalence rates and their confidence intervals are comparable between the different populations of the Indian subcontinent and between these populations and Chinese populations. Prevalence of Glaucoma in Chinese Populations Country Number of Sample Participants Type Thailand 701 Cross sectional over 50 Monglia 942 All over 40 Singapore 1232 Prevalence of POAG% 2.3% (95 CI, 1.3 3.7) 0.5 Disproportionate stratified 2.4% (95 clustered random sample 40 CI, 1.6 to 79 3.2) Reference Bourne et al 1 Foster et al 2 Foster et al 3 Prevalence of Glaucoma in Indian Populations Country Number of Sample Participants Type Reference Southern India 934 Dandona et al4 South India 972 Bangladesh 2347 Southern India 5150 South India 3934 Prevalence of POAG% Cross 2.56% sectional (95% CI, over 40 1.22 -3.91) Cluster 0.41% sample 30 (95% CI, to 60 0.008 – 0.81) . Multistage 2.1%(95% stratified CI, 1.5-2.9) cluster sample over 40 Cross 1.7% (95% sectional CI, 1.3 – clustered 2.1) over 40 Non 1.62% random (95% CI, sample 1.42 – over 40 1.82) Jacob et al 5 Rahman et al 6 Ramakrishnan et al 7 Vijaya et al 8 References 1. Bourne RR, Sukudom P, Foster PJ, Tantisevi V, Jitapunkul S, Lee PS, Johnson GJ, Rojanapongpun P. Prevalence of glaucoma in Thailand: a population based survey in Rom Klao District, Bangkok. Br J Ophthalmol. 2003 Sep;87(9):106974. 2. Foster PJ, Baasanhu J, Alsbirk PH, Munkhbayar D, Uranchimeg D, Johnson GJ. Foster et al Glaucoma in Mongolia. A population-based survey in Hovsgol province, northern Mongolia. Arch Ophthalmol. 1996 Oct;114(10):1235-41. 3. Foster PJ, Oen FT, Machin D, Ng TP, Devereux JG, Johnson GJ, Khaw PT, Seah SK. The prevalence of glaucoma in Chinese residents of Singapore: a crosssectional population survey of the Tanjong Pagar district. Arch Ophthalmol. 2000 Aug;118(8):1105-11. 4. Dandona L, Dandona R, Srinivas M, Mandal P, John RK, McCarty CA, Rao GN. Open-angle glaucoma in an urban population in southern India: the Andhra Pradesh eye disease study. Ophthalmology. 2000 Sep;107(9):1702-9. 5. Jacob A, Thomas R, Koshi SP, Braganza A, Muliyil J. Prevalence of primary glaucoma in an urban south Indian population. Indian J Ophthalmol. 1998 Jun;46(2):81-6. 6. Rahman MM, Rahman N, Foster PJ, Haque Z, Zaman AU, Dineen B, Johnson GJ. The prevalence of glaucoma in Bangladesh: a population based survey in Dhaka division. Br J Ophthalmol. 2004 Dec;88(12):1493-7. 7. Ramakrishnan R, Nirmalan PK, Krishnadas R, Thulasiraj RD, Tielsch JM, Katz J, Friedman DS, Robin AL. Glaucoma in a rural population of southern India: the Aravind comprehensive eye survey. Ophthalmology. 2003 Aug;110(8):1484-90. Erratum in: Ophthalmology. 2004 Feb;111(2):331. 8. Vijaya L, George R, Baskaran M, Arvind H, Raju P, Ramesh SV, Kumaramanickavel G, McCarty C. Prevalence of Primary Open-angle Glaucoma in an Urban South Indian Population and Comparison with a Rural Population The Chennai Glaucoma Study. Ophthalmology. 2007 Jul 28 Risk Factors Why is this section included in the report? Risk factors are important in suspecting and diagnosing glaucoma in primary care. The primary care ophthalmologist will need to know these factors in order to recognise patients who may have glaucoma. The primary care ophthalmologist, who will follow up ocular hypertension, needs to know which patients are more at risk of developing glaucoma. Finally, the risk factors for the progression of glaucoma are important for determining which patients could be followed up safely in primary care. A note on the clinical guidelines and risk factors for glaucoma Available clinical guidelines have varied in their approach to the subject of risk factors for glaucoma. The AAO, for example, explicitly states that risk factors are discussed as part of the background section, which does not include recommendations, but is designed to provide the rationale for the recommendations that are presented in the care process section. The Finland guidelines provide recommendations, whilst the AAO guidelines give comprehensive reviews on many factors. In this section therefore, reference will be made only to guidelines with a distinct contribution to the discussion. In this section, the following categories of risk factors will be examined 1. Risk factors for the development of chronic open angle glaucoma 2. Risk factors for the progression of ocular hypertension to chronic open angle glaucoma 3. Risk factors for the progression of chronic open angle glaucoma I. Risk factors for the development of chronic open angle glaucoma Key Question – Is there evidence that any of the following characteristics or conditions is a risk factor for the development of glaucoma? This will be presented according to the classification by Boland and Quigley Boland MV, Quigley HA. Risk factors and open-angle glaucoma: classification and application. J Glaucoma. 2007 Jun-Jul;16(4):406-18 An evidence level is given for each publication. At the end of each risk factor, a conclusion of knowledge up to date is given. This is followed by a level of recommendation which denotes the strength of the conclusion in terms of available evidence. A summary table based on the level of recommendation is given at the end of the discussion. 1 Age Evidence Synthesis Rudnicka AR, Mt-Isa S, Owen CG, Cook DG, Ashby D Variations in primary open-angle glaucoma prevalence by age, gender, and race: a Bayesian meta-analysis. Invest Ophthalmol Vis Sci. 2006 Oct; 47(10):4254-61 Results of the above meta-analysis showed that in white populations, the odds ratio of OAG per decade is 2.05, whereas in black populations, the odds ratio is 1.6 per decade and in Asian populations, it is 1.57 per decade. These findings indicate that proportional increase in prevalence of OAG with age was highest in white populations. In 40 to 49 year olds, the prevalence of OAG in black populations was approximately 7 times higher than the prevalence in white populations, whereas by age 80 to 89 years, the prevalence was approximately 2.5 times higher. The prevalence in Asian populations was similar to the prevalence in white populations at ages 40 to 69; thereafter, it was relatively higher in white populations. OR per decade; whites 2.05, blacks 1.6, Asians 1.57 Level of Evidence – 1 Conclusion – Increased age is a risk factor for the development of POAG especially among white populations. Recommendation – A State of the Individual 2. Gender Evidence Synthesis Rudnicka et al above stated that the controversy around whether a gender difference exists in the prevalence of POAG may be explained by lack of power with insufficient numbers of OAG cases within individual studies. In their metaanalysis, published estimates by gender were available for 25 studies with 61267 participants and 1355 case of OAG. Overall, the prevalence of OAG in men was 1.37 times that in women after adjusting for age, racial group, publication year and survey methods. On stratification by racial group, the odds ratio for OAG in men compared with women was 1.46 in white populations, 1.27 in black populations and 1.36 in Asian populations. OR men to women; white 1.46, black, 1.27, 1.36 Level of Evidence – 1 Conclusion – Male gender is a risk factor for the development of POAG in white, black and Asian populations Recommendation - A 3. Ethnicity Evidence Synthesis As discussed in the section on prevalence and age, the meta-analysis by Rudnicka et al has shown that at all ages, black populations have the highest prevalence estimates of OAG. The pooled random effects prevalence estimates of OAG is 1.4% (95% CI, 1.0% – 2.0%) in Asian populations, 4.2% in black populations (95% CI, 3.1% - 5.8%) and 2.1% (95%CI, 1.6% - 2.7%) in white populations. Prevalence; white 2.1, black 4.2, Asian 1.4 Level of Evidence – 1 The Literature on Blacks Wormald RP, Basauri E, Wright LA, Evans JR. The African Caribbean Eye Survey: risk factors for glaucoma in a sample of African Caribbean people living in London. Eye. 1994;8 ( Pt 3):315-20. This is a study of a cross sectional voluntary sample of Afro Caribbean people living in the London Borough of Haringey to estimate the prevalence and risk factors of chronic glaucoma. Skin colour was graded as light, medium or dark. The prevalence of glaucoma in the light skin was 1.7%, in the medium skin 3.5% and 4.5% in the dark skin (p=0.38). Dark skin colour was significant as a risk factor only when the outcome was definite glaucoma plus glaucoma suspects plus ocular hypertension. African origin as a risk factor had the strongest odds ratio (OR) after age for the development of definite glaucoma. Africans accounted for only 16% of the sample and were younger than the West Indians. They came mainly from Nigeria and Ghana. The authors concluded that data from this study is insufficient to throw more light on this observation and should probably be interpreted with caution. Level of Evidence - 3 Murdoch IE, Cousens SN, Babalola OE, Yang YF, Abiose A, Jones BR. Glaucoma prevalence may not be uniformly high in all 'black' populations. Afr J Med Med Sci. 2001 Dec;30(4):337-9. The authors examined a population of Hausa/Fulani individuals in rural Northen Nigeria. The overall prevalence of open angle glaucoma in this population was 1.02% (0.12 to 3.64, 95% confidence interval) in individuals 45 years of age and older which is lower than the prevalence rates reported for other "black" populations. The authors mentioned that the low prevalence of glaucoma detected in this African population may be, to some extent, a reflection of the age structure of the population studied or methodological differences in ophthalmic examinations performed. It is also possible that the prevalence of glaucoma varies considerably between "black" populations due to genetic heterogeneity or the effect of some unidentified environmental exposure. The authors concluded that the use of the simple description of populations as 'black' (or 'white'), which focuses on a commonality, tends to obscure the potential heterogeneity within and between populations and thus may be unhelpful in some circumstances. Level of Evidence - 2 Racette L, Wilson MR, Zangwill LM, Weinreb RN, Sample PA. Primary open-angle glaucoma in blacks: a review. Surv Ophthalmol. 2003 May-Jun;48(3):295-313. In this review, the authors compared the prevalence of glaucoma in five different studies on blacks. There was variation in the prevalence estimates of the different studies but the authors pointed out that this variability may be due to differences in the definitions, criteria and/or testing methods used to define, diagnose and classify POAG. Level of Evidence - 3 Conclusion – At all ages, black populations have the highest prevalence estimates of OAG, compared to other races. There may be a significant variation in prevalence between different black populations but this is not definite. Recommendation - B 4. Family History Key Questions Evidence Synthesis – There is no evidence synthesis report on this question The Guidelines - AOA Studies have suggested that 13 -25 percent of patients with glaucoma may have family histories positive for the disease. In close relatives of persons with POAG, the prevalence is 3-6 times that of the general public, and the incidence of the disease in first-degree relatives is 3−5 times that found in the general population. The 22 percent lifetime risk for glaucoma found in relatives of patients with glaucoma is almost 10 times that of controls. The risk may be greater in siblings than in parents or children. A family history of glaucoma puts a person with OH at greater risk of developing the disease. Ocular characteristics associated with glaucoma, including IOP and the cup-to-disc ratio, have been associated with moderate familial risk. The Literature Tielsch JM, Katz J, Sommer A, Quigley HA, Javitt JC. Family history and risk of primary open angle glaucoma. The Baltimore Eye Survey Arch Ophthalmol. 1994 Jan;112(1):69-73 This study is based on a population prevalence survey of 5308 black and white residents of east Baltimore, USA, which identified 161 cases of primary open angle glaucoma among subjects who were 40 years of age or older. Family history was ascertained by interview and included all first-degree relatives (parents, siblings, and children). Results showed a higher risk of glaucoma in siblings than in parents or children (odd ratios: 3.69, 2.17, and 1.12, respectively) of known glaucoma patients. OR; siblings 3.69, parents 2.17, children 1.12 Level of Evidence – 2 Wolfs RC, Klaver CC, Ramrattan RS, van Duijn CM, Hofman A, de Jong PT Genetic risk of primary open-angle glaucoma. Population-based familial aggregation study Arch Ophthalmol. 1998 Dec;116(12):1640-5 In this population based Rotterdam study, Wolfs et al, found that the prevalence of primary open angle glaucoma was 10.4% in siblings of patients, 1.1% in offspring of patients, 0.7% in siblings of controls, and 0% in offspring of controls. Life-time risk of primary open angle glaucoma was 22.0% in relatives of patients vs. 2.3% in relatives of controls. Enlarged cup-disc ratio, not intraocular pressure, was the earliest and most prominent feature of familial aggregation. Prevalence; siblings patients 10.4%, offspring patients 1.1%, 0.7% siblings controls, offspring controls 0% Level of Evidence – 2 Leske MC, Nemesure B, He Q, Wu SY, Fielding Hejtmancik J, Hennis A Patterns of open-angle glaucoma in the Barbados Family Study. Ophthalmology. 2001 Jun;108(6):1015-22 This is a case control study in a black population. Leske et al examined 207 families of probands which included 1056 family members. They found that 10% of the probands had two or more relatives affected with OAG and 29% had one relative with OAG. They also compared sibling with and without OAG and found that the affected siblings were significantly older than those without the disease and more often were male. Siblings with OAG had higher IOP, lower diastolic blood pressure–IOP differences, and more myopia than unaffected siblings. Level of Evidence - 2 Sung VC, Koppens JM, Vernon SA, Pawson P, Rubinstein M, King AJ, Tattersall CL Longitudinal glaucoma screening for siblings of patients with primary open angle glaucoma: the Nottingham Family Glaucoma Screening Study. Br J Ophthalmol. 2006 Jan;90(1):59-63 In this study, a group of siblings of OAG probands underwent initial and follow up standardised ophthalmic examinations with a mean interval of 7 years between both examinations. In the first examination, 271 siblings from 156 probands were examined. Of these, 32 (11.8%) were classified as definite glaucoma and 15 (5.5%) as suspects. In the second examination, 157 of the 224 "normal" siblings from the initial examination were examined and 11 (7%) were classified as definite glaucoma and 30 (19.1%) as suspects. The authors compared these results to those of a Bedford Survey conducted in the 1980s on 101 individuals with a positive family history of glaucoma. The study reported only a 3% incidence of definite glaucoma after 10–12 years of follow up. The authors of the Nottingham study attributed this lower incidence, compared to their findings, to the fact that only 17 of the Bedford survey subjects were siblings and the others were mostly children of probands and by necessity of much younger age. Level of Evidence – 3 Wiggs JL Genetic Etiologies of Glaucoma Arch Ophthalmol. 2007;125:30-37 Glaucoma may be inherited as mendelian-dominant or mendelian recessive traits (usually early-onset forms of the disease), or may exhibit a heritable susceptibility consistent with complex trait inheritance (typically adult-onset forms of the disease). Genetic approaches have helped define the underlying molecular events responsible for some mendelian forms of the disease and have identified the chromosome locations of genes that are likely to contribute to common complex forms. Adult-onset glaucoma often occurs in multiple family members (familial aggregation) but does not usually follow a clear mendelian inheritance pattern, suggesting that inherited risk factors can result in a susceptibility to the disease but alone are not necessarily causative. Multiple risk factors and/or environmental factors may be responsible for this disease in older individuals. Defects in MYOC coding for myocilin are found in 3% to 5% of patients with adult-onset POAG. Certain MYOC mutations are more commonly found in older-onset patients than in early-onset patients. In particular, the nonsense mutation Q368X, which results in a truncated polypeptide, is more frequently found in patients with adult onset POAG than in patients with early-onset POAG. Conclusion – There is level 2 evidence that siblings of patients with POAG have a higher risk of developing the disease than parents or children. Affected siblings are significantly older than those without the disease and more often male. Siblings with OAG have higher IOP, lower diastolic blood pressure–IOP differences, and more myopia than unaffected siblings. Recommendation - C Ocular Anatomy and Physiology 5. Increased Intraocular Pressure Evidence Synthesis – There is no evidence synthesis report on this question The Guidelines - AOA Intraocular pressure has a strong, direct relationship with the prevalence and longterm risk for glaucoma. For persons with IOP above 21 mm Hg, the risk of developing glaucoma is 16 times the risk for persons with IOP below 16 mm Hg. Moreover, the percentage of eyes developing visual field defects after 5 years is percent for those with IOP over 20 mm Hg, compared with 1.5 percent of eyes with IOP below 20 mm Hg. Even in NTG, it was found that the higher the pressure, the greater the risk. Asymmetric levels of IOP in individual pairs of eyes correlate risk for optic nerve damage. Long-term studies have consistently shown that a large percentage of persons with statistically elevated IOP (>21 mm Hg) do not develop glaucoma, while many persons with glaucoma have IOP well within the statistically normal range. Population-based studies have demonstrated that one-tenth or fewer of those with elevated IOP suffer visual field loss when monitored over several years. The incidence of glaucoma among persons with ocular hypertension is at most 1 percent per year. One-third to one-half of persons with glaucoma have IOP at or below 20 mm Hg at initial diagnosis. The Literature Boland and Quigley mentioned that nearly every study has shown that the level of IOP is a risk factor for OAG incidence, prevalence and progression. Both the three clinical trials that followed the natural history of a recruited population and the three population based incidence studies from Melbourne, Barbados and South India identified higher IOP as a risk factor for the development of glaucoma. In the South India study, the diurnal fluctuation in IOP was found to be an independent risk factor as well. Level of Evidence – 2 Le A, Mukesh BN, McCarty CA, Taylor HR Risk factors associated with the incidence of open-angle glaucoma: the visual impairment project Invest Ophthalmol Vis Sci. 2003 Sep;44(9):3783-9 This is a population based study which included 3271 participants recruited from nine urban areas through cluster random sampling and examined at baseline and five years follow up. For increased intraocular pressure, the authors calculated, by multivariate analysis, a relative risk (RR) for the development of at least possible and at least probable glaucoma (grading based on the judgment of the examiner and not clinical criteria), of RR 1.1 (95% CI, 1.03–1.2) and RR 1.1(95% CI, 1.04– 1.2) respectively. RR; at least possible glaucoma 1.1, at least probable glaucoma 1.1 Level of Evidence – 2 Conclusion – There is level 2 evidence that there is an increased risk for the development of POAG with increased levels of intraocular pressure. Recommendation - C 6. Exfoliation Syndrome Evidence Synthesis – There is no evidence synthesis report on this question. The Guidelines – AOA The prevalence of pseudoexfoliation syndrome varies widely throughout the world ranging from about 1.6 to 2.3 percent in persons over age 50 in the United States. The prevalence of PEX with subsequent pseudoexfoliation glaucoma increases with age, and these conditions most commonly occur between the ages of 60 and PEX is 2−3 times more common in women than in men and its prevalence in African Americans is much lower than in Caucasians. Through family studies, several putative sites on chromosome 2 are being investigated for genetic mutations related to PEX. PEX is a definite risk factor for OH and OAG. On initial screening, OH is found in 22−30 percent of individuals with PEX.OH develops in about 10 percent of persons who had PEX and normal IOP at initial diagnosis. The cumulative probability of developing OH is 5.3 percent in 5 years and 15.4 percent in 10 years. The prevalence of PEX in a glaucoma population ranges from 1.6 to 28 percent in the United States. Thirty to sixty percent of individuals with PEX have been reported to develop OAG. The Literature Mitchell P, Wang JJ, Hourihan F. The relationship between glaucoma and pseudoexfoliation: the Blue Mountains Eye Study. Arch Ophthalmol. 1999 Oct; 117(10):1319-24. This is a cross-sectional study of 3654 people aged 49 to 97 years identified subjects with PEX during slitlamp examination. Glaucomatous damage was present in 14.2% of eyes with PEX compared with 1.7% of eyes without PEX (age- and sex-adjusted odds ratio (OR), 5.0; 95% CI, 2.6-9.6). This was almost unchanged (OR, 4.8) after adjustment for glaucoma risk factors and was also relatively unaffected by IOP adjustment (OR, 3.7; 95% CI, 1.8-7.6). For subjects with PEX, the relationship with glaucoma persisted, but was weaker (OR, 2.3; 95% CI, 1.0-5.0) in the multivariate model. However, the population attributable risk from PEX was only 2.7%. OR glaucomatous damage in eyes with PEX to eyes without PEX after adjustment is 4.8 Level of Evidence - 2 Jeng SM, Karger RA, Hodge DO, Burke JP, Johnson DH, Good MS. The risk of glaucoma in pseudoexfoliation syndrome. J Glaucoma. 2007 Jan;16(1):117-21. This is a retrospective community-based study of newly diagnosed cases of PEX syndrome in all residents of Olmsted County, Minnesota between 1976 and 1991. The end point was considered the initiation of therapy, which included patients with glaucoma (optic disc damage or visual field defects), or with elevated intraocular pressure (IOP) >21 mm Hg in the presence of risk factors. Two hundred fifty-five patients (318 eyes) had newly diagnosed PEX over the 15-year interval. Of all PEX patients, 16% were placed on therapy at the time of initial diagnosis of PEX. In the remaining PEX patients, the probability of being placed on therapy was 44% at 15 years. The strongest risk factors for converting to therapy were raised IOP at initial diagnosis of PEX and bilateral involvement. Level of Evidence – 2 Conclusion – There is level 2 evidence that there is a strong association between glaucoma and eyes with PEX. The strongest risk factors for converting to glaucoma are initial raised IOP and bilateral involvement. Recommendation – D Systemic Associations of Pseudoexfoliation Schlotzer-Schrehardt U, Naumann GO. Ocular and systemic pseudoexfoliation syndrome. Am J Ophthalmol. 2006 May;141(5):921-937. An association of PEX syndrome with cardiovascular and cerebrovascular disease has so far only been established by rather small-scale retrospective studies in single centres. As inherent to retrospective studies, the accuracy of (early) diagnoses may vary or may have been established only without the use of modern diagnostic techniques. Therefore, a carefully planned prospective, randomized multicenter study is warranted to finally assess a cause and effect relation of cardiovascular/ cerebrovascular morbidity status and PEX. 7. Pigment Dispersion Syndrome Evidence Synthesis – There is no evidence synthesis report on this question. The Guidelines – AOA Pigment dispersion syndrome occurs in about 2.5 percent of adult Caucasians in the United States. It rarely occurs in African Americans and Asians. About 20−60% of persons with PDS develop ocular hypertension and 25−50% will develop pigmentary glaucoma. PDS is usually bilateral and affects persons at younger ages than POAG (30−50 years). Its occurrence is most common in Caucasian males with myopia. In fact, about 90 percent of individuals with PDS are myopic. PDS may have an autosomal-dominant, multifactorial basis, suggesting the importance of family history. At least one genetic locus has been identified for PDS. The Literature Farrar SM, Shields MB, Miller KN, Stoup CM Risk factors for the development and severity of glaucoma in the pigment dispersion syndrome. Am J Ophthalmol. 1989 Sep 15;108(3):223-9 The authors studied the medical records of patients with pigmentary glaucoma and pigment dispersion syndrome to identify factors associated with the presence of secondary glaucoma. Male gender, black race, severe myopia, and Krükenberg spindles were identified as possible risk factors. Level of Evidence – 3 Siddiqui Y, Ten Hulzen RD, Cameron JD, Hodge DO, Johnson DH. What is the risk of developing pigmentary glaucoma from pigment dispersion syndrome? Am J Ophthalmol. 2003 Jun;135(6):794-9. Erratum in: Am J Ophthalmol. 2003 Sep;136(3):592. This is a retrospective community-based study of all newly diagnosed cases of pigment dispersion syndrome or pigmentary glaucoma over a period of 24 years. The majority of patients were myopic and mean myopic refractive error was –3.9 ± 2.7 dioptres (range, 0.1 to – 12.0 dioptres). The condition was most commonly diagnosed between the ages of 30 to 49 years. The risk of developing pigmentary glaucoma from pigment dispersion syndrome was 10% at 5 years and 15% at 15 years. Young, myopic men were most likely to have pigmentary glaucoma. An IOP greater than 21 mm Hg at initial examination was associated with an increased risk of conversion. Level of Evidence – 2 Conclusion – there is a level 2 evidence that male gender, severe myopia and Krukenberg spindle are risk factor for the development of pigmentary glaucoma in pigment dispersion syndrome. There is level 3 evidence that a raised IOP at initial examination is associated with an increased risk of conversion from pigment dispersion syndrome to pigmentary glaucoma. Recommendation - D 8. Myopia Evidence Synthesis – there is not evidence synthesis report on this question The guidelines AAO – The association between POAG and myopia has not demonstrated consistently Finland – There is a two to four fold risk for development of AOG among myopes AOA – Though potentially subject to selection bias, several studies have demonstrated, after adjustment for age, a two to five fold higher prevalence of POAG in patients with myopia The Literature Mitchell P, Hourihan F, Sandbach J, Wang JJ. The relationship between glaucoma and myopia: the Blue Mountains Eye Study. Ophthalmology. 1999 Oct;106(10):2010-5. In this cross-sectional population-based study of 3654 Australians 49 to 97 years of age, subjects with myopia were categorized into low myopia (> or =-1.0 D to <3.0 D) or moderate-to-high myopia (> or =-3.0 D). Glaucoma was diagnosed from characteristic visual field loss, combined with optic disc cupping and rim thinning, without reference to IOP. Glaucoma was present in 4.2% of eyes with low myopia and 4.4% of eyes with moderate-to-high myopia compared to 1.5% of eyes without myopia. After adjusting for known glaucoma risk factors, an association between myopia and glaucoma remained with odds ratio (OR) 2.3 (95% CI, 1.3 4.1) for low myopia and OR, 3.3(95% CI, 1.7-6.4) for eyes with moderate-to-high myopia Only a borderline relationship was found with ocular hypertension, OR of 1.8 (95% CI, 1.2-2.9) for low myopia, and OR of 0.9 (CI, 0.4-2.0) for moderate-tohigh myopia. Myopia and glaucoma OR 2.3 for low myopia and OR 3.3 for eyes with moderate-to-high myopia Myopia and ocular hypertension OR 1.8 for low myopia, and OR of 0.9 for moderate-to-high myopia. Level of Evidence - 2 Ramakrishnan R, Nirmalan PK, Krishnadas R, Thulasiraj RD, Tielsch JM, Katz J, Friedman DS, Robin AL. Glaucoma in a rural population of southern India: the Aravind comprehensive eye survey Ophthalmology. 2003 Aug; 110(8):1484-90 This is a population based cross sectional study of 5150 subjects aged 40 years and older from 50 clusters representative of three southern districts of Tamil Nadu in southern India. Myopia was present in 59.3% of POAG patients. This association was statistically significant on univariate analysis (OR, 1.9; 95% CI, 1.2- 2.9). Multivariate analysis showed a statistically significant association between POAG and mild myopia (OR, 2.9, 95% CI, 1.3- 6.9), moderate myopia (OR, 2.1, 95% CI,1.0- 4.6), severe myopia (OR, 3.9, 95% CI,1.6- 9.5). Myopia and POAG OR, 2.9, moderate myopia OR, 2.1, severe myopia OR, 3.9 Level of Evidence - 2 Xu L, Wang Y, Wang S, Wang Y, Jonas JB. High myopia and glaucoma susceptibility the Beijing Eye Study. Ophthalmology. 2007 Feb;114(2):216-20. This is a study of 4319 subjects, 40 years or older, who agreed to participate when invited (response rate, 83.4%). The group was stratified according to refractive error into high myopia (myopia > -8 D), marked myopia (<-6 to -8 D), moderate myopia (<-3 to -6 D), low myopia (<-0.5 to -3 D), emmetropia (-0.5 to + <2 D), and hyperopia (>+ 2 D) subgroups. They were evaluated by morphologic assessment of optic disc monoscopic photographs and measurement of intraocular pressure. Prevalence of glaucomatous optic nerve atrophy as defined by the glaucomatous optic nerve head appearance did not vary significantly (p = 0.77; odds ratio [OR] 1.2( 95% CI, 0.38-3.81) between the highly myopic group and the group with marked myopia. In both refractive groups combined, glaucoma frequency was (p = 0.075; OR, 2.28; 95% CI, 0.99-5.25) higher than in the group with moderate myopia; it was significantly (p = 0.001; OR, 3.5; 95% CI, 1.717.25) higher than in the group with low myopia; significantly (p<0.001; OR, 7.56; 95% CI, 3.98-14.35) higher than in the group with emmetropia; and significantly (p = 0.005; OR, 4.23; 95% CI, 1.57-11.45) higher than in the group with hypermetropia. Glaucoma frequency did not vary significantly between the hyperopic group and the emmetropic group (p = 0.17), the group with low myopia (p = 0.83) and the group with moderate myopia (P = 0.32). Intraocular pressure did not vary significantly (P>0.10) between any of the subgroups. Similar results were obtained for the frequency of glaucoma defined as glaucomatous optic disc appearance and visual field defects. Risk of glaucoma high myopia to marked myopia OR 2.28 Risk of glaucoma high myopia to low myopia OR 3.5 Risk of glaucoma high myopia emmetropia OR 7.56 Risk of glaucoma high mypia hypermetropia OR 4.23 Level of Evidence – 2 Conclusion – There is level 2 evidence that increasing levels of myopia are a risk factor for the development of POAG. Recommendation - C 9. Central Corneal Thickness Evidence Synthesis – there is no evidence synthesis report on this question The Literature To our knowledge, there are no population studies that have examined central corneal thickness as a risk factor for the development of glaucoma. Boland and Quigley pointed out that central corneal thickness has two interactions with OAG risk. First, it is known that thinner corneas give lower applanation IOP readings, hence persons with thin corneas would be missed with IOP screening alone and are more likely to develop optic nerve damage before being detected. On the other hand, there is recent evidence that those with thinner corneas respond better to topical medication to lower IOP. Level of Evidence – 4 Conclusion – There is level 4 evidence that central corneal thickness may be an indirect risk factor for the development of glaucoma. Recommendation - D 10. Optic Disc Diameter Evidence Synthesis – There is no evidence synthesis report on this question The Literature Quigley HA, Varma R, Tielsch JM, Katz J, Sommer A, Gilbert DL The relationship between optic disc area and open-angle glaucoma: the Baltimore Eye Survey. J Glaucoma. 1999 Dec;8(6):347-52 Data were collected from a population-based sample of adults residing in East Baltimore. One eye from each of 75 patients with glaucoma was compared to those of 3,518 subjects without glaucoma. Although optic disc area was somewhat larger among patients with glaucoma than control subjects, in a regression model adjusting for age, gender, and race, the significance of this difference had a probability of 0.06. It was therefore concluded that disc area is a weak risk factor for open-angle glaucoma. Level of Evidence – 2 Conclusion – There is level 2 evidence that the optic disc diameter is a weak risk factor for the development of open angle glaucoma. Recommendation - D 11. Ocular Trauma Strictly, open angle glaucoma due to ocular trauma is classified as secondary glaucoma. In addition, Boland Quigley did not include it in their review of risk factors. However, it is included in this report due to its significance in suspecting glaucoma especially that the eye may look normal or contain a residual sign which may be overlooked by the examiner. Evidence Synthesis – There is no evidence base synthesis report on this question The Literature Two publications analysed the United States Eye Injury Registry for risk factors for the development of glaucoma following contusion and penetrating injuries. These are the only. Other literature attempting to identify risk factors associated with glaucoma after ocular trauma consists of only a few small case series. Girkin CA, McGwin G Jr, Long C, Morris R, Kuhn F. Glaucoma after ocular contusion: a cohort study of the United States Eye Injury Registry. J Glaucoma. 2005 Dec;14(6):470-3. Data from the United States Eye Injury Registry were obtained from a total of 6021 patients who experienced blunt ocular contusion. Cases were defined as having developed posttraumatic glaucoma within the 6-month follow-up period based upon the 6-month report form, as determined by the physician submitting the form. The physician’s opinion was based upon the presence of elevated IOP, optic disc, and/or visual field abnormality consistent with glaucoma. Specific information on intraocular pressure, number of medications, need for glaucoma. The development of glaucoma was independently associated with: advancing age (OR = 1.02; 95% CI = 1.02, 1.03), visual acuity worse than 20/200 (OR = 1.92; 95% CI = 1.19, 3.10), iris injury (OR = 1.60; 95% CI = 1.05, 2.44), lens injury (OR = 1.86; 95% CI = 1.11, 3.11), hyphema (OR = 2.23; 95% CI = 1.40, 3.54), or angle recession (OR = 1.71; 95% CI = 1.00, 2.90). Level of Evidence – 2 Muallem, MS, Wilensky, J Glaucoma after Ocular Contusion J Glaucoma. 2006 Jun;15(3):274 Muallem and Wilensky subsequently wrote to the editor of the Journal of Glaucoma, commenting on the above study, and expressing concern about the definition of glaucoma, the inherent wide variability in interpreting visual field defects and reporting optic disc changes among the large numbers of participating physicians and the criteria for elevated IOP in terms of level and consistency. Tumbocon JA, Latina MA. Angle recession glaucoma. Int Ophthalmol Clin. 2002 Summer;42(3):69-78. The authors reviewed the literature and found five studies reporting that more than 60% of eyes with non-penetrating injuries will have some degree of angle recession. In hyphema patients, based on six studies, some degree of angle recession occurred in 56% to 100% of cases with a total of 81%. Two studies have shown that only 6% to 7% of angle recession cases will eventually develop glaucoma. There appears to be two peak incidences of glaucoma after angle recession. The first peak occurs within the first few weeks to years after the trauma and the second peak occurs ten or more years after the injury. Some investigators have even reported cases of recession glaucoma developing more than fifty years after the initial injury. There is also an association between the extent of angle recession and the development of glaucoma. Most investigators agree that patients with 180 to 360 degrees of angle recession will have a greater risk of developing late occurring glaucoma. It appears that those eyes with less than 180 degrees of recession are unlikely to develop glaucoma. In eyes that do develop angle recession glaucoma, the contralateral non-traumatised eye has been reported to have a 50% chance of developing open-angle glaucoma, sometimes years after the pressure rise was noted in the traumatized eye. This may indicate that the angle recession itself is probably not the cause of elevated intraocular pressure but, rather, that it may accelerate the appearance of glaucoma in patients who are already predisposed to develop primary open-angle glaucoma. Level of Evidence - 3 Girkin CA, McGwin G Jr, Morris R, Kuhn F. Glaucoma following penetrating ocular trauma: a cohort study of the United States Eye Injury Registry. Am J Ophthalmol. 2005 Jan;139(1):100-5. This is prospective cohort study in which data from the United States Eye Injury Registry was obtained from a total of 3,627 patients who experienced penetrating ocular injury between 1988 and January 2003. Data are collected from hospitals, emergency rooms, and physicians’ offices on all types of trauma determined as serious eye trauma, defined as trauma that may potentially result in permanent structural or functional damage. A standardized reporting form is filled out on the initial examination of a patient with ocular trauma. Information regarding demographics, the nature and location of injury, the extent of ocular injury assessed both structurally and functionally, and any initial surgical interventions are recorded on the initial visit after the traumatic injury. At 6 months, an additional form is filled out encompassing information regarding the structural and functional ocular outcomes resulting from the initial trauma and any additional procedures that have occurred. The risk of developing posttraumatic glaucoma was 2.67%. The development of glaucoma was independently associated with several baseline characteristics including advancing age (relative risk 1.02/yr 95% confidence interval [1.00, 1.03]), lens injury (1.56 [1.03, 2.35]), poor baseline visual acuity (2.59 [1.62, 4.14]), and inflammation (3.02 [1.52, 6.02]). Level of Evidence – 2 Conclusion – There is level 2 evidence that advancing age, lens injury and poor baseline visual acuity are risk factors for the development of glaucoma following both contusion and penetrating injuries. In addition, angle recession, hyphema and iris injury are risk factors in contusion injuries and inflammation is a risk factor in penetrating injuries. Recommendation - D Systemic Diseases 12. Hypertension Evidence Synthesis – there is no evidence synthesis report on this question The Guidelines AAO – There appears to be a subset of patients with low diastolic perfusion pressure (diastolic blood pressure – IOP) who are at a higher risk for POA Finland – Decreased perfusion pressure together with age give a threefold risk of developing open angle glaucoma AOA - The literature is equivocal on whether there is an association between systemic hypertension and POAG. The Baltimore Eye Survey suggested the complexity of the relationship between POAG and systemic blood pressure. Patient age and the duration of systemic hypertension modify its effect on POAG. Lower perfusion pressure (BP-IOP) was significantly associated with an increased prevalence of POAG. Low systemic blood pressure, including the nocturnal dip, also may pose a risk for NTG. The Literature Wong TY, Mitchell P. The eye in hypertension. Lancet. 2007 Feb 3;369(9559):425-35. Review. Erratum in: Lancet. 2007 Jun 23;369(9579):2078. Wong, Tien Systemic hypertension is suspected to increase the risk of the development and progression of glaucoma. Epidemiological studies have not, however, shown a consistent association between hypertension and glaucoma. Three populationbased studies reported a cross-sectional association. In one, people with hypertension were 50% more likely to have glaucoma, after adjustment for glaucoma risk factors such as intraocular pressure, than those without. Hypertension also accounted for the greatest population-attributable risk for glaucoma compared with other risk factors, suggesting that from a public-health perspective, hypertension might be more important than less common risk factors carrying a two-fold to three-fold higher risk of glaucoma. Nonetheless, prospective studies have not proven an association between both systolic or diastolic blood pressure and incidence of glaucoma. Perfusion pressure is the difference between the diastolic blood pressure and intraocular pressure. One study noted that low perfusion pressure was a stronger risk factor for glaucoma than was systemic hypertension alone and that hypertension was a risk factor for glaucoma in older participants, but not in those who were younger. Level of Evidence – Level 2 Conclusion – It is not yet confirmed that hypertension is a risk factor for the development of POAG. Recommendation for Hypertension - D Recommendation for Perfusion Pressure - C 13. Diabetes Evidence Synthesis Bonovas S, Peponis V, Filioussi K Diabetes mellitus as a risk factor for primary open-angle glaucoma: a metaanalysis. Diabet Med. 2004 Jun;21(6):609-14 This meta-analysis included twelve studies published between 1987 and 2001 (five case–control studies and seven cross-sectional studies). Eleven studies reported positive association (OR > 1) and one study reported negative association (OR < 1). However, only five of the positive studies had estimated ORs that were statistically significant. The one study reporting negative association was not statistically significant. The association of diabetes mellitus with primary openangle glaucoma was found to be statistically significant using either a random effects model, OR =1.50, (95% CI, 1.16-1.93), or a fixed-effects model, OR = 1.27 (95% CI, 1.10-1.45). The Guidelines – AOA The association of diabetes mellitus with both elevated IOP and POAG has been controversial. Several studies lend support to a higher prevalence of ocular hypertension and POAG in persons with diabetes, for whom the relative risk of POAG ranges from 1.6 to 4.7. Others have found no relationship between the presence of diabetes and the development of ocular hypertension or POAG. The Literature In relation to the above meta-analysis, Boland and Quigley pointed out that the report did not standardise the definition of OAG and two of the included studies used IOP as a defining feature of OAG. Level of Evidence – 1 Conclusion – It is not yet definite that diabetes is a risk factor for the development of POAG. Recommendation – B (guarded due to problems affecting quality of metaanalysis) 14. Thyroid Disease Evidence Synthesis – There is no evidence synthesis report on this question The Literature Lee AJ, Rochtchina E, Wang JJ, Healey PR, Mitchell P Open-angle glaucoma and systemic thyroid disease in an older population: The Blue Mountains Eye Study. Eye. 2004 Jun;18(6):600-8. In this population based study of 3654 persons, aged 49-97 years, AOG was more frequent in those reporting past thyroid disease but the relationship was not statistically significant. OAG was significantly more frequent in subjects reporting current thyroxine use, multivariate OR 2.1; 95% CI 1.0-4.4, or history of thyroid surgery multivariate OR 2.5; 95% CI 1.0-6.2. Level of Evidence – Level 2 Girkin CA, McGwin G, McNeal SF, Lee PP, Owsley C. Hypothyroidism and the development of open-angle glaucoma in a male population. Ophthalmology. 2004 Sep;111(9):1649-52. This is a case control study in which 590 patients newly diagnosed with OAG were age matched with controls. After adjustment for the other potential risk factors, patients were significantly more likely to have prior hypothyroidism than controls (OR, 1.40; 95% CI, 1.01-1.97). The authors mentioned that there were previously published five small case control studies with some showing a significant positive association and others finding no greater risk of glaucoma in patients with hypothyroidism. However, these previous studies utilized a small number of subjects, with varying study designs and different definitions for both glaucoma and hypothyroidism, resulting in an unclear impression of the true relationship between hypothyroidism and the development of open-angle glaucoma (OAG). Level of Evidence – Level 2 Conclusion – An association between POAG and hypothyroidism has been found but the role of hypothyroidism as a risk factor for the development of POAG is not known. Recommendation - D 15. Cardiovascular Disease Evidence Synthesis – There is no evidence synthesis report on this question The Literature Boland and Quigley pointed out that despite the presence of several articles examining the risk of OAG in cardiovascular disease, diagnostic definitions have varied and are difficult to standardise. With one exception, major population studies and clinical trials have generally failed to find any association of cardiovascular disease with OAG, nor is there evidence of premature mortality in OAG patients as might occur if they had predispositions to cardiovascular disease. Evidence – Level 2 Orzalesi N, Rossetti L, Omboni S; on behalf of the OPTIME Study Group (Osservatorio sulla Patologia glaucomatosa, Indagine Medico Epidemiologica), CONPROSO (Collegio Nazionale dei Professori Ordinari di Scienze Oftalmologiche). Vascular risk factors in glaucoma: the results of a national survey. Graefes Arch Clin Exp Ophthalmol. 2007 Jun; 245(6):795-802. This is an observational survey in 35 Italian academic centres examining 2,879 POAG patients and 973 controls. The ESH-ESC (European Society of Hypertension-European Society of Cardiology) guidelines were used to calculate the level of cardiovascular risk. POAG patients tended to have a higher cardiovascular risk than controls: 63% of glaucoma cases vs 55% of controls (OR:1.38, p=0.005) had a “high” or “very high” cardiovascular risk. Level of Evidence – Level 2 Conclusion – POAG patients may have a higher cardiovascular risk than controls but there is no evidence that cardiovascular disease is a risk factor for the development of POAG. Recommendation - D 16. Sleep Apnea Evidence Synthesis – There is no evidence synthesis report on this question The Literature McNab AA. The eye and sleep apnea. Sleep Med Rev. 2007 Aug;11(4):269-76. The author reviewed the literature and found a report that has identified increased prevalence of primary open angle glaucoma in patients with obstructive sleep apnea (OSA) and also a report of high prevalence of sleep-disordered breathing in patients with primary open angle glaucoma. One study showed a correlation between the severity of the sleep disturbance and severity of the visual field loss. Others have reported an association between normal-tension glaucoma and OSA, particularly in older patients. A variety of visual field defects in OSA patients was also reported in nine patients, and in two patients who were treated for OSA, the field defects stabilised. Another patient has also been reported with normaltension glaucoma and progressive field loss despite pressure lowering by drops and surgery, whose field loss stabilised after diagnosis of OSA and its treatment. Against this background of reports, one conflicting study has shown the prevalence of glaucoma in a group of OSA patients to be the same as the general population. The author concluded that this may be an optic neuropathy that mimics glaucoma and that it would seem prudent to ask for symptoms of OSA in patients with an optic neuropathy especially those in whom there is no other identifiable risk factor of glaucoma. Level of Evidence – Level 2 Conclusion – Sleep apnea as a risk factor for the development of POAG has not been confirmed but sleep apnea may be associated with an optic neuropathy. Recommendation – D Migraine and Vasospasm 17. Migraine Evidence Synthesis – There is no evidence synthesis report on this question The Literature Phelps CD, Corbett JJ. Migraine and low-tension glaucoma. A case-control study. Invest Ophthalmol Vis Sci. 1985;26:1105–1108. In this study, headaches were present in 86% of elderly low-tension glaucoma patients (70 yr of age or older) but in only 64% of elderly normal subjects (P = 0.04) and only 59% of elderly ocular hypertensive patients (P = 0.02). Level of Evidence – Level 2 Klein BE, Klein R, Meuer SM, Goetz LA. Migraine headache and its association with open-angle glaucoma: the Beaver Dam Eye Study. Invest Ophthalmol Vis Sci. 1993 Sep;34(10):3024-7 In this population based study, there was no difference in the frequency of openangle glaucoma between those with and those without migraine headache (P = 0.87). Multivariate analyses did not alter the conclusion. Level of Evidence – Level 2 Wang JJ, Mitchell P, Smith W. Is there an association between migraine headache and open-angle glaucoma? Findings from the Blue Mountains Eye Study. Ophthalmology. 1997;104:1714–1719. In this population based cross sectional study of subjects 49 years old and older. For all age groups combined, there was no significant association between typical migraine headache and OAG. However, after stratifying into 10-year age groups, increased odds for OAG were found for people giving a history of typical migraine headache and aged 70-79 years (OR, 2.5; 95% CI 1.2-5.2), after adjusting for variables found associated with glaucoma. Level of Evidence – Level 2 Cursiefen C, Wisse M, Cursiefen S, Jünemann A, Martus P, Korth M. Migraine and tension headache in high-pressure and normal-pressure glaucoma. Am J Ophthalmol. 2000 Jan;129(1):102-4. This is a prospective study in which 154 patients with glaucoma (56 normalpressure subgroup and 98 high-pressure glaucoma subgroup), 55 patients with ocular hypertension and 75 control subjects were analyzed by means of a standardized questionnaire based on International Headache Society criteria. The prevalence of headache, migraine, and tension headache did not vary significantly among control subjects, patients with ocular hypertension and patients with glaucoma, but migraine was significantly more common in patients with normalpressure glaucoma (28%) compared with control subjects (12%; P<.05) and patients with high-pressure glaucoma (10%; P<.01). Level of evidence – 2 Conclusion – There is level 2 evidence that headaches are more common in elderly patients with low tension glaucoma and that there is increased odds of OAG in elderly people with migraine headache that those without. For all age groups, there is no difference in the occurrence of glaucoma between those with and without migraine headaches, but migraine is significantly more common in patients with normal tension glaucoma than controls or patients with high tension glaucoma. Recommendation – C 18. Raynaud’s Phenomenon Evidence Synthesis – There is no evidence synthesis report on this question The Literature Boland and Quigley explained that on the basis of the vascular theory of glaucoma, systemic manifestations of vasospasm have been studied as a possible risk factor. They found that an earlier report suggested a link between vasospastic phenomena and certain types of optic nerve damage (see below), but that the Early Manifest Glaucoma Trial did not confirm an association. Broadway DC, Drance SM. Glaucoma and vasospasm. Br J Ophthalmol. 1998 Aug;82(8):862-70. Patients with pure examples of four glaucomatous optic disc types--focal ischaemic, myopic glaucomatous, senile sclerotic, and those with generalised cup enlargement, were selected. A detailed ophthalmic, systemic, drug and smoking history was taken from the patients who, in addition, underwent assessment of peripheral vasospasm with a laser Doppler flowmeter. The group of patients with focal ischaemic discs contained more women (66% versus 32%-50% in the other three groups; p = 0.01) and had a higher prevalence of vasospasm (63% versus 25%-49%; p = 0.01), migraine (32% versus 8%-19%; p = 0.02), and cold extremities (66% versus 17%-30%; p = 0.00003). The authors also noted that the simple assessment as to whether a glaucoma patient suffers from colder extremities than average appeared to be better at distinguishing the focal ischaemic type of glaucoma than using the laser Doppler flowmeter. Evidence Level – 3 Conclusion – Vasospasm, migraine and cold extremities may be associated with focal ischaemic discs. Recommendation - D Non-Glaucoma Medications 19. Corticosteroids Evidence Synthesis – There is no evidence synthesis report on this question The Literature Jones R 3rd, Rhee DJ Corticosteroid-induced ocular hypertension and glaucoma: a brief review and update of the literature. Curr Opin Ophthalmol. 2006 Apr;17(2):163-7. The authors reviewed the literature of corticosteroid induced ocular hypertension and glaucoma and its risk factors. They found that increased intraocular pressure can occur as a consequence of oral, intravenous, inhaled, topical, periocular, or intravitreal corticosteroid therapy. If the ocular hypertension is of a significant magnitude, not recognized and not treated, subsequent glaucomatous optic neuropathy can develop. The rise of raised IOP usually occurs over a period of weeks if used topically and years if used systemically. There have been some reports of an elevation of IOP within hours of initiating intensive topical steroid use. Corticosteroids have been shown to exert an ocular hypertensive response relative to the intraocular potency of the steroid. Acetates are more lipophilic and penetrate through the cornea better than phosphates, which are relatively hydrophilic. Medrysone 1.0% caused a 1.0 mmHg rise in IOP, while more potent steroids such as prednisolone acetate 1.0% and dexamethasone acetate 0.1% caused a 10 and 22 mmHg rise in IOP, respectively. As regards predisposing risk factors for corticosteroid induced glaucoma , they found the following. Primary open-angle glaucoma patients and glaucoma suspects were shown to be at an increased risk for elevated IOP after treatment with topical dexamethasone 0.1% for four weeks or betamethosone 0.1% for two to four weeks. In the dexamethasone study, the effect was noted to be more prominent in the eyes of older adult patients compared with the eyes of younger adult patients. Two other studies showed that simply having a first-degree relative with POAG could make one susceptible to being a steroid-responder, one of which was a double blind study performed in Whipps Cross Hospital, London by TG Davies*. In this study, disodium phosphate betamethasone 0.1% was instilled four times daily into one eye, and normal saline into the fellow eye of close relatives of patients with chronic simple glaucoma. (Addition by author of report) Although older patients are at increased risk, the frequency of steroid responsiveness with age may occur in a bimodal distribution. Children as a group have been shown to be greater steroid-responders as compared with adults. Patients with connective tissue disease tend to be steroid-responders. Men with connective-tissue disease tended to be greater responders, although gender is not typically considered a risk factor in people without connective-tissue disease. Additionally, patients with type-1 diabetes mellitus and high myopia have also been shown to be at increased risk to be steroid-responders. * Davies TG. Tonographic survey of the close relatives of patients with chronic simple glaucoma. Br J Ophthalmol. 1968 Jan;52(1):32-9. Conclusion - Increased intraocular pressure can occur as a consequence of oral, intravenous, inhaled, topical, periocular, or intravitreal corticosteroid therapy. Children, older adult patients, close relatives of glaucoma patients, men with connective tissue disease and patients with diabetes mellitus or high myopia are at high risk of being steroid responders. No evidence level or recommendation due to the narrative nature of the review. 20. Cholesterol Lowering Agents Evidence Synthesis – There is no evidence synthesis report on this question The Literature McGwin G Jr, McNeal S, Owsley C, Girkin C, Epstein D, Lee PP. Statins and other cholesterol-lowering medications and the presence of glaucoma. Arch Ophthalmol. 2004;122:822–826. This study is based on the records of an administrative clinical database. Cases were all male patients aged 50 years and older with a new diagnosis of glaucoma on an outpatient or inpatient visit between January 1, 1997, and December 31, 2001. Each case was age matched to 10 control subjects. Longer duration of statin use was associated with a lower risk of open-angle glaucoma primarily among subjects with 24 months or more of use (OR, 0.60; 95% CI, 0.39-0.92). Nonstatin cholesterol-lowering agents were also associated with a reduced risk of having open-angle glaucoma. Level of Evidence – 2 Conclusion – Statin and non-statin cholesterol lowering agents may be associated with a reduced risk of developing open angle glaucoma. Recommendation - D 21. Calcium Channel Blockers Evidence Synthesis – There is no evidence synthesis report on this question The Literature Boland and Quigley reviewed the literature and found that calcium channel blockers have been used in some clinical trials of small subgroups of OAG patients and ‘shown to lower IOP when used topically’ (Report author addition). They also mentioned that no data from population studies have indicated either beneficial or detrimental effects of these agents. Evidence Level – 1 to 2 Conclusion – The role of calcium channel blockers as a risk factor for developing OAG is not known. Recommendations - C Personal Behaviours 22. Exercise Evidence Synthesis – There is no evidence synthesis report on this question The Literature Boland and Quigley reviewed the literature and concluded that although exercise has shown the ability to lower IOP in adults with ocular hypertension, no direct association with OAG risk has been made. Evidence Level – 2 Conclusion – There is not direct association between exercise and glaucoma risk. Recommendation - D 23. Smoking Evidence Synthesis Bonovas S, Filioussi K, Tsantes A, Peponis V Epidemiological association between cigarette smoking and primary open-angle glaucoma: a meta-analysis Public Health. 2004 Jun;118(4):256-61 This meta-analysis included seven studies. Results suggest that current smokers are at significantly increased risk of developing POAG, odds ratio (OR) 1.37 (95% CI, 1.00 –1.87). In contrast, past smokers are not elevated risk of developing POAG, OR 1.03 (95% CI, 0.77–1.38). It should be noted that this meta-analysis did not include a definition for POAG. Also Boland and Quigley pointed out that this meta-analysis includes clinic based data from Africa and that one small clinic based case control series found that Chinese OAG exhibit more cigarette smoking than controls; suggesting that some OAG risk factors might be dependant on interaction with ethnicity. Evidence Level – 1 Conclusion – Smokers may be at a significantly increased risk of developing POAG Recommendation - B 24. Obesity Evidence Synthesis – There is no evidence synthesis report on this question The Literature Cheung N, Wong TY Obesity and eye diseases. Surv Ophthalmol. 2007 Mar-Apr;52(2):180-95. In this study, the authors reviewed 11 studies on the relation between body mass index and ocular hypertension or glaucomatous optic neuropathy. They found as strong evidence that obesity is associated with elevated intraocular pressure, but there was no convincing data to support a more direct association between obesity and glaucomatous optic neuropathy. One study suggested some protective effect of higher BMI with risk of open-angle glaucoma. The reviewers mentioned that the analysis, however, only controlled for age and not other factors, and the possibility of incomplete adjustment for confounders could not be excluded. Evidence Level for obesity and OHT – 2 Evidence Level for protective effect – 2 Conclusion - Inconsistent Findings – no recommendation 25. Alcohol Evidence Synthesis – There is no evidence synthesis report on this question The Literature Klein BE, Klein R, Ritter LL Relationship of drinking alcohol and smoking to prevalence of open-angle glaucoma. The Beaver Dam Eye Study Ophthalmology. 1993 Nov;100(11):1609-13 This is a population-based survey of 4926 persons 43 to 84 years of age in Beaver Dam, Wisconsin. Heavy drinking behaviour was not related to the prevalence of open angle glaucoma. Level of Evidence - 2 Kang JH, Willett WC, Rosner BA, Hankinson SE, Pasquale LR Prospective study of alcohol consumption and the risk of primary open-angle glaucoma Ophthalmic Epidemiol. 2007 May-Jun;14(3):141-7 The authors followed female nurses from 1980 and male health professionals from 1986 to 2002, who were 40 years or older, did not have POAG, and reported receiving eye examinations during follow-up. Alcohol consumption of less than 30 g/day did not influence POAG risk. Although there were suggestive inverse associations with drinking more than 30 g/day (RR=0.71), this was not significant (95% CI, 0.49-1.04), and no significant linear associations were detected between alcohol consumption and AOG. Level of Evidence – 2 Conclusion – There is no significant association between alcohol consumption and POAG. Recommendation - C 26. Caffeine Evidence Synthesis – There is no evidence synthesis report on this question The Literature Boland and Quigley reviewed the literature and found that caffeine intake has not been related to OAG, although acute intake of a large volume of caffeine containing beverage does cause a slight rise in IOP. Level of Evidence – 2 Conclusion – There is no evidence of an association between caffeine intake and POAG. Recommendation - D 27. Fat Intake Evidence Synthesis – There is no evidence synthesis report on this question The Literature Kang JH, Pasquale LR, Willett WC, Rosner BA, Egan KM, Faberowski N, Hankinson SE. Dietary fat consumption and primary open-angle glaucoma. Am J Clin Nutr. 2004 May;79(5):755-64 In this study, the authors studied dietary fat consumption because dietary fatty acids affect endogenous prostaglandin F(2alpha) concentrations and may thus influence intraocular pressure. They prospectively followed up 76199 women nurses for 16 years and 40306 men health professionals for 10 years who were 40 years or older and free of POAG at the time of enrolment. Major fats and fat subtypes were not independently associated with POAG risk. A high ratio of n-3 to n-6 polyunsaturated fat appeared to increase the risk of POAG, particularly high-tension POAG. Level of Evidence – 2 Conclusion – Major fats and fat subtypes are not associated with POAG risk. Recommendation - D 28. Increased Venous Pressure Evidence Synthesis – There is no evidence synthesis report on this question The Literature Boland and Quigley reviewed the literature on elevated venous pressure and OAG and concluded that there is some epidemiologic evidence that this may play a role in OAG, but clinic-based studies have not confirmed a general tendency. Level of Evidence – 2 to 3 Conclusion – A role of increased venous pressure in the development of POAG has not been confirmed. Recommendation – D Summary Table of Risk Factors for Glaucoma Level of Recommendation A B C D Condition Age Gender Ethnicity Diabetes Smoking Family History Raised IOP Myopia Perfusion Pressure Migraine Calcium Channel Blockers Alcohol Exfoliation Syndrome Pigment Dispersion Syndrome Central Corneal Thickness Optic Disc Diameter Ocular Trauma Hypertension Thyroid Disease Cardiovascular Disease Raynaud’s Phenomenon Cholesterol Lowering Agents Exercise Caffeine Fat Intake Increased Venous Pressure Number in Text 1 2 3 13 23 4 5 8 12 17 21 25 6 7 9 10 11 12 14 15 16 20 22 26 27 28 No Recommendation Corticosteroids Obesity 19 24 II Risk of progression of ocular hypertension to glaucoma Friedman DS, Wilson MR, Liebmann JM, Fechtner RD, Weinreb RN. An evidence-based assessment of risk factors for the progression of ocular hypertension and glaucoma. Am J Ophthalmol. 2004 Sep;138(3 Suppl):S19-31. In this review, the authors examined 34 studies, including the Ocular Hypertension Treatment Study critically for strength of evidence to ascertain risk factors for progression of OHT to glaucoma and the progression of glaucoma to blindness. The latter will be discussed in the next section. For the progression of ocular hypertension to glaucoma the authors analysed 8 studies. Mean intraocular pressure was found to be a significant risk factor for progression. In the OHTS, univariate and multivariate analyses found that every 1 mmHg increase in mean IOP level was associated with a 10% increased risk of progression from OHT to glaucoma. One study reported that a large difference in IOP levels between the two eyes was associated with progression from OHT to glaucoma. In an unrelated study, such large disparities between the two eyes were reported to be more common in patients with OHT (33%) and POAG (36%), than in normal subjects (6%). The significance of diurnal or nocturnal fluctuation of IOP is still questionable. Greater cup to disc ratio is an independent risk factor for progression from OHT to glaucoma. Evidence was strong and consistent. Greater cup to disc ratio has been identified as a baseline risk factor in two studies, with values > 0.4 and = or >0.5 being associated with an increased risk of progression. The OHTS univariate hazard ratios were increased by a significant 25% per 0.1 larger horizontal cup to disc ratio and by 32% per 0.1 larger vertical cup to disc ration. Statistical significance was confirmed in multivariate analysis. One edit orial however warned that large cup to disc ratios in OHT patients in general and in OHTS specifically may be an indication of early structural damage and not a risk factor, particularly that after selecting the OHT patients, 20% of them were found to have defects on short wave length automated perimetry. Entry into the study was based on a normal and reliable Humphrey 30-2 visual fields. Nerve fibre layer atrophy was associated with increasing risk of development of visual field loss among persons with ocular hypertension. The grade of atrophy was strongly predictive with OR around 8 for more severe nerve fibre defects. Central corneal thickness was identified in the OHTS as a strong independent risk factor for progression from OHT to POAG in both univariate and multivariate analysis, Hazard Ratio 1.88 (95% CI, 1.55 – 2.29) and 1.71 ( 95% CI, 1.40 – 2.09) respectively. Age is an independent risk factor for progression of OHT, as evidenced by multiple progression studies. Black race, although associated with increased risk for AOG; there is little evidence that it is an independent risk factor for progression from OHT to glaucoma. In OHTS, black race was associated with an increased risk of progressing from OHT to glaucoma in the univariate analysis but not in the multivariate analysis. Family history, although associated with increased risk of AOG; evidence is lacking regarding progression from OHT to glaucoma. In OHTS, family history was not identified as a risk factor, however, family history was ascertained by patient report and not by direct examination of relatives. One large cohort study of Greek subjects with OHT did find family history to be associated with progression to visual field loss. Diabetes had a weak evidence of being a risk factor in progression from OHT to glaucoma. Analysis of the OHTS results suggested that diabetes protects against progression to glaucoma. However, these unexpected findings may in part be explained by the fact that patients with diabetic retinopathy were excluded from this study, yielding an unrepresentative group of patients with diabetes. Also, the diagnosis of diabetes was by self-report and not clinically verified, which could result in inaccuracies in reporting. Decreased outflow facility, migraine, myopia, hypermetropia, pseudoexfoliation and male sex, have been mentioned in the literature as risk factor for the progression of OHT. In general, the limited number of studies in which these additional suspected risk factors were evaluated does not support firm conclusions concerning their relative importance. III Risk factors for the progression of chronic open glaucoma to blindness For the progression of glaucoma to blindness, the authors analysed 4 studies namely, the Early Manifest Glaucoma Trial (EMGT), The Advanced Glaucoma Intervention Study (AGIS), the Collaborative Normal Tension Glaucoma Study (CNTGS) and the Collaborative Initial Glaucoma Treatment Study (CIGTS). Older age was found to be a risk factor for the progression of glaucoma in three of the studies. The fourth, CNTGS, did not find an association. Diabetes was found to be a risk factor by AGIS and CIGTS. The other two studies did not examine diabetes for risk. Disc haemorrhage was found to be a risk factor by EMGT and CNTGS. The other two studies did not examine disc haemorrhage for risk Female sex was found to be a risk factor in the CNTGS. Male sex was found to be a risk factor in the AGIS. EMGT and CIGTS did not examine gender for risk. Intraocular pressure was found in the EMGT to be a risk factor for progression at 21 mmHg or higher. Greater IOP reduction at the first follow up visit after three months for both treated and untreated patients was associated with a lower risk of progression. In CNTGS and AGIS, the level at intraocular pressure at baseline was not a risk factor. The CIGTS did not examine IOP as a risk factor. Pseudoexfoliation was found to be a risk factor in EMGT. The other three studies did not examine pseudoexfoliation as a risk factor. Race was found to be a significant risk factor in the CNTGS with Asians having a significantly longer survival time before blindness compared to Caucasions. Black race appeared to show more rapid deterioration than Caucasians; however this difference did not reach statistical significance due to the small number of black patients enrolled. In the CIGTS, being non white was a risk. The EGIS did not find an association. Greater visual field loss was found to be a risk factor for progression of glaucoma the EMGT. The AGIS found that better visual field is the risk factor which is the opposite of the findings of EMGT. The other two studies did not examine the degree of visual field loss as a risk factor. Lower formal education was found to be a risk factor for the progression of glaucoma by AGIS. Migraine was an independent risk factor for the progression of glaucoma in CNTGS. The EMGT did not find it significantly related. Raynauld’s syndrome was not a significant risk factor for the progression of glaucoma in EMGT. Systemic hypertension was not a significant risk factor for the progression of glaucoma in AGIS. Systemic diseases were not a significant risk factor for the progression of glaucoma in AGIS. Refractive errors were not a significant risk factor for the progression of glaucoma in AGIS. Central corneal thickness was not a significant risk factor for the progression of glaucoma in the EMGT. Behki R,. Damji KF, Crichton A for the CCT workshop participants Canadian perspectives in glaucoma management: the role of central corneal thickness Can J Ophthalmol. 2007; 42 (1): 66-74. Other studies have shown relatively lower CCTs among ocular hypertensives with abnormal perimetry results in SWAP or FDT, compared with subjects with normal results. There are seven studies, besides EMGT, which are related to CCT and POAG. In one study, increased CCT correlated significantly (p>0.001) and positively with the area of the neuroretinal rim and negatively with the presenting loss of visual field. Some of the other studies showed a weak association between thinner corneas and glaucoma progression Detection Why is the detection of glaucoma included in this report? The detection of chronic open angle glaucoma, ocular hypertension and glaucoma suspects is first contact care. In the UK, this type of first contact, where glaucoma is definitively diagnosed, suspected or excluded, is usually in the hospital eye service. Traditionally, the optometrists suspected glaucoma by a raised IOP finding or a suspiciously cupped optic disc and referred the patient to the hospital eye service for glaucoma detection. But now there are changes. Firstly, some optometrists have acquired advanced technologies. Secondly, Primary Care Trusts are increasingly establishing ophthalmic primary care units where they would expect glaucoma detection to take place. Thirdly, there may be private providers who are offering a glaucoma detection service in the community. Background The detection of glaucoma in primary care is different to that in the hospital eye service because it is the first level of capturing the disease. Whereas the hospital doctor will have glaucoma at the forefront of his differential diagnosis because the patient has already been suspected of having glaucoma in primary care, the primary care ophthalmologist will not have this advantage. S/He may not proceed with tests like visual field testing or close examination of the optic disc and nerve fibre layer unless he has a strong reason to suspect glaucoma. In this report therefore, all the steps leading to detection will be analysed fully for evidence, even if these steps have not traditionally be included with rigour in the examination of the possible glaucoma patient. For each step, elaboration in any of the clinical guidelines will be mentioned, followed by a presentation of evidence to date. The level of evidence and degree of recommendation will be included in the end. The following steps will be presented 1. History Taking 2. Visual Acuity 3. Colour Vision 4. Contrast Sensitivity 5. Visual Disabitily 6. Relative Afferent Pupillary Defect 7. Water Drinking Test 8. Central Corneal Thickness 9. Measurement of intraocular pressure 10. Gonioscopy 11. Pupil Dilatation 12. Optic Disc Examination 13. Examination of the Nerve Fibre Layer 14. Visual Field Testing 1. History Taking Key Question Is there evidence of specific questions in history taking that would help in the diagnosis of ocular hypertension, glaucoma suspect or chronic open angle glaucoma? Evidence Synthesis – There is no evidence synthesis report on this question The Guidelines ICO – recommends including the following in history taking Ocular history (A:III) Systemic history (A:III) Family history (A:II) Assessment of impact of visual function on daily living and activities (A:III) Review of pertinent records (A:III) AAO – Recommends including the following in history taking Ocular history (A:III) Family history (A:II) Systemic history (A:III) Assessment of the impact of visual function on daily living and activities (A:III) Review of pertinent records with particular reference to the status of the optic nerve, visual field, and IOP (A:III) History of ocular surgery (A:III) The use of ocular or systemic medications (A:III) Known local or systemic intolerance to glaucoma medications (A:III) Outcome of glaucoma in family members including history of visual loss from glaucoma (B:III) Singapore – No mention RCOphth – No mention Asia Pacific – recommends including the following in history taking Past ophthalmic history of steroids, surgery and laser Visual symptoms of blurring and discomfort (Posner-Schlossman and pigment dispersion syndromes), glare and coloured rings around lights from corneal oedema, poor light dark adaptation and difficulty tracing fast moving objects (tennis or golf ball) Past medical history o Respiratory - asthma and chronic obstructive pulmonary diseases associated with hyperresponsive airways and/or reduced lung capacity. o Cardiovascular – to exclude past haemodynamic crisis (post partum haemorrhage, ruptured abdominal aneurysm, severe trauma that may cause optic disc colour cupping that mimics glaucoma but is not progressive o Cardiovascular – cardiac arrythmias e.g. heart block which may preclude the use of β blockers or α agonists o Cardiovascular – hypertension overtreatment may worsen glaucoma risk and progression. Systemic β blockers may mask elevated IOP o Cardiovascular - vasospastic tendency (migraine and Raynaud’s syndrome) may be associated with increased incidence and severity of glaucoma, especially normal pressure. o Endocrine – diabetes associated with open angle and neovascular glaucoma o Endocrine - thyroid eye disease o Endocrine – pituitary tumours o CNS – previous CVA/head injury/pituitary lesions may cause field loss o CNS – early dementia - affects compliance, understanding and insight into the disease o Musculoskeletal – arthritis ( osteo and musculoskeletal) may affect severely the ability to administer eye drops o Urogenital – urinary stones may limit carbonic anhydrase inhibitors o Ocular trauma – angle recession, lens dislocation, choroidal/retinal damage o Pregnancy and lactation – if present or possible renders all interventions potentially hazardous o Medication – steroids – any route of administration is associated with ocular hypertension or open angle glaucoma. It is sometimes found in traditional medicines o Medication – Vigabatrin (anti convulsant)- linked to nasal peripheral loss without disc changes o Medication – systemic β blocker/calcium channel blockers – may interact with topical β blockers Family History of the glaucoma, its type and its course in the family European Glaucoma Society – Recommends including the following in the history History of migraine History of cold hands and Raynaud’s disease, History of neurological disease, thyroid disease, kidney disease or blood loss, Smoking and drinking habits Family history of visual loss and glaucoma Finland – No mention AOA - The patient history should include a thorough analysis of all general familial, ocular, and nonocular risk factors for the various types of glaucoma. A complete medical history, including current medication and known medicine intolerance and allergies, is essential. The Literature There are no publications on history taking in chronic open angle glaucoma. 2. Visual Acuity Key Question: Is there evidence that the testing of visual acuity alone or along with other tests, either using Snellen’s chart or any other clinically used vision chart, can contribute to the detection of chronic open angle glaucoma? Evidence Synthesis: There is no evidence synthesis report on this question. The Guidelines ICO –recommends the testing of VA but does not give a reason (A: III) AAO – Does not include VA in eight elements on which to focus in the examination of glaucoma patients and glaucoma suspects Singapore - The visual acuity and IOP are neither specific nor sensitive enough in themselves to be effective diagnostic or screening tools (B: IIa) RCOphth – no mention Asia Pacific – VA is not mentioned but gross visual function is included in history European Glaucoma Society – no mention Finland – refers to visual acuity as a basic examination AOA – 1.Corrected and uncorrected distance or near vision acuity, or both, should be measured as one indicator of the integrity of the central vision system. 2. Various forms of treatment for glaucoma as well as advanced stages of the disease can affect visual acuity. The Literature Stamper RL The effect of glaucoma on central visual function. Trans Am Ophthalmol Soc.1984;82:792-826. Stamper argued that there are enough clinical and experimental reports to suggest that central visual acuity is affected early in glaucoma but that these changes are not picked up by the Snellen’s Chart. His hypothesis was not taken further in the medical literature and at best it can be classified as Level 3 taking into account that he has reviewed the literature and some others were of his opinion. Level of Evidence – 3 Recommendation - D 3. Colour Vision Key Question Is there evidence that the examination of colour vision is useful in the detection of chronic open angle glaucoma? Evidence Synthesis – There is no evidence synthesis report on this question. The Guidelines Only AOA refers to the examination of colour vision and concludes that it is of no value The Literature Adams AJ, Rodic R, Husted R, Stamper R Spectral sensitivity and colour discrimination changes in glaucoma and glaucomasuspect patients. Invest Ophthalmol Vis Sci. 1982 Oct;23(4):516-24 Adams et al reviewed the literature and found studies suggesting that colour vision changes may occur early in the course of glaucoma and may precede visual field loss. Glaucoma suspects, having raised intraocular pressure and no diagnostic optic nerve head or visual field changes, may also have colour vision loss. They conducted their own case control study and concluded that minor modifications of the Farnsworth D-15 panel test produce highly significant differentiation of glaucoma and glaucoma-suspect patients from age-matched normal groups. Level of Evidence - 3 Heron G, Erskine NA, Farquharson E, Moore AT, White H. Colour vision screening in glaucoma: the Tritan Album and other simple tests. Ophthalmic Physiol Opt. 1994 Jul;14(3):233-8. (level IV evidence; case control study) The authors used simple colour vision tests for the detection of the Type III colour vision deficiency in glaucoma and ocular hypertension. Best results were obtained from a combination of City University Colour Vision Test and AO HRR plate test scores. No acquired tritan defects were identified by the Farnsworth F2 plate. Level of Evidence – 3 Recommendation - D 4. Contrast Sensitivity Key Question: Is there evidence that the examination of contrast sensitivity is useful in the detection of chronic open angle glaucoma? Evidence Synthesis: There is no evidence synthesis report on this question. The Guidelines Only AOA refers to the examination of contrast sensitivity and concludes that it is of no value. The Literature Stamper RL The effect of glaucoma on central visual function. Trans Am Ophthalmol Soc.1984;82:792-826. Stamper, and others quoted by him, have demonstrated the reduction of temporal contrast sensitivity in patients with glaucoma and some glaucoma suspects. He concluded that despite the useful information that they provide, tests for contrast sensitivity functions are not quite ready for routine clinical use. Level of Evidence – 3 Wilensky JT, Hawkins A Comparison of contrast sensitivity, visual acuity, and Humphrey visual field testing in patients with glaucoma. Trans Am Ophthalmol Soc. 2001;99:213-7; discussion 217-8. Patients with a diagnosis of glaucoma, glaucoma suspect, or ocular hypertension whose visual acuity was 20/40 (logMAR = 0.3) or better were included in the study. Visual acuity was measured using the Lighthouse visual acuity charts. Contrast sensitivity was measured using the Pell-Robson (PR) chart. The mean depression (MD) score from the most recent Humphrey visual field was used to quantify the visual field defect. The PR contrast sensitivity score correlated more strongly with the MD of the visual field (r = .589, P < .001) than did the logMAR visual acuity (r = .193, P = .035). When just the eyes with open-angle glaucoma were considered, the correlation was even greater for the PR score (r = .638). In ocular hypertensive eyes, the correlations to PR and logMAR were not that different (r = .394 for PR, r = .303 for logMAR). The authors speculated that this decrease in contrast sensitivity in glaucoma patients may account for their complaints of poor vision despite normal or near normal visual acuity. Level of Evidence - 3 Hawkins AS, Szlyk JP, Ardickas Z, Alexander KR, Wilensky JT Comparison of contrast sensitivity, visual acuity, and Humphrey visual field testing in patients with glaucoma. J Glaucoma. 2003 Apr;12(2):134-8. This prospective cross sectional case series was undertaken to investigate the phenomenon that despite their normal or near-normal Snellen visual acuity, patients with glaucoma often complain of "poor" vision. Using the methodology of the previous study, the authors evaluated 250 eyes, subjects with a diagnosis of glaucoma, suspected glaucoma, or ocular hypertension. The authors found that reduced contrast sensitivity is significantly correlated with visual field losses in patients with glaucoma and a visual acuity of 20/40 or better which supported the previous conclusion that, compared with visual acuity, the disease process preferentially affects contrast sensitivity. Level of Evidence – 3 Recommendation – C 5. Visual Performance This section refers to the overall visual performance of the glaucoma patient in daily life and not in clinical tests. There are several studies on the quality of life of the glaucoma patient but they will not be included, and only those that describe visual performance elements that may aid in detection will be presented. Evidence Synthesis – There is no evidence synthesis report on this question The Guidelines ICO – recommends ssessment of impact of visual function on daily living and activities (A:III) AAO – recommends assessment of impact of visual function on daily living and activities (A:III) Singapore – no mention RCOphth – no mention Asia Pacific – recommends including visual symptoms of blurring and discomfort (Posner-Schlossman and pigment dispersion syndromes), glare and coloured rings around lights from corneal oedema, poor light dark adaptation and difficulty tracing fast moving objects (tennis or golf ball) history taking. European Glaucoma Society – no mention Finland – no mention AOA – Recommends examination for relative afferent papillary defect Nelson P, Aspinall P, O’Brien C. Patients’ perception of visual impairment in glaucoma: a pilot study. Br J Ophthalmol 1999; 83:546–552 In this study, 63 glaucoma patients completed a questionnaire containing 62 questions covering 10 broad aspects of daily life activities using a five point answer scale. Patients were classified into three groups as having mild, moderate, and severe field loss on the basis of the perimetric results. The relation between a measure of the severity of visual field loss and subjective visual disability in the three groups was examined. The most frequently reported problems were grouped into the following four categories: outdoor mobility, glare and lighting conditions and activities demanding functional peripheral vision, household tasks, and personal care. With increasing severity of binocular visual field loss there was an increase in the number of self reported visual problems. A loss of confidence in performing some routine daily tasks tended to precede self reported specific visual disabilities. The factor “glare and lighting and activities demanding functional peripheral vision” was found to have a significant relation with a measure of visual field loss. Level of Evidence – 3 Jampel HD. Glaucoma patients' assessment of their visual function and quality of life. Trans Am Ophthalmol Soc. 2001;99:301-17 In this study, 237 glaucoma patients evaluated their vision using 2 utility tests, and 2 quality-of-life instruments. Their results were compared to clinical tests of their vision and to persons with normal vision and to blind persons. On a scale of 0 (blind) to 100 (ideal), subjects with normal vision rated their vision higher (90 +/8.0) than did glaucoma subjects and suspects (75.7 +/- 17.6) and "blind" subjects (15.6 +/- 15.3), P = .001. Level of Evidence - 3 Recommendation - D 6. Relative Afferent Pupillary Defect Key Question: Is there evidence that the examination of the relative afferent papillary defect is useful in the detection of chronic open angle glaucoma? Evidence Synthesis: There is no evidence synthesis report on this question. The Guidelines ICO – Recommends examination for relative afferent papillary defect (B-II) AAO – Recommends examination for relative afferent pupillary defect (B-II) Singapore – Informs that 1. there will be a relative afferent pupillary defect (RAPD) if asymmetrical involvement. 2. patients with chronic glaucoma may have no symptoms or signs, apart from abnormal pupil light reflexes and optic disc cupping RCOphth – no mention Asia Pacific – no mention European Glaucoma Society – no mention Finland – no mention AOA – Recommends examination for relative afferent papillary defect The Literature Brown et al studied 27 consecutive patients with glaucoma who had either a relative afferent pupillary defect (RAPD) or asymmetric optic nerve cupping without an RAPD. Every patient with a visual field asymmetry and a sensitivity difference of 13% or greater had an RAPD. The authors concluded that the presence of an RAPD indicates that a threshold of asymmetric optic nerve damage has been exceeded. Level of Evidence – 3 Recommendation – D 7. Water Drinking Test Key Question: Is there evidence that the water drinking test is useful in the detection of chronic open angle glaucoma? Evidence synthesis: There is not evidence synthesis report on this question The guidelines Water drinking is only described in the European Glaucoma Society guidelines. The literature Roth JA Inadequate diagnostic value of the water-drinking test. Br J Ophthalmol. 1974 Jan;58(1):55-61 The author reviewed the literature on the water drinking test and found that many investigators have evaluated it and considered it to be a reliable method of diagnosing chronic simple glaucoma. Some authors found it reliable with applanation rather than with indentation tonometry. Most authors have agreed that a rise in intraocular pressure (IOP) of 6 mm. Hg is suggestive of the presence of chronic simple glaucoma, but opinions have varied as to what is to be considered as a truly pathological rise. The author then did his own investigation by examining the notes of patients who have had the water drinking test and applanation tonometry in the Institute of Ophthalmology, London. Using the 6 mmHg criterion, he found that the highest proportion of positive tests was obtained in eyes with ocular hypertension (82%), the next in glaucoma suspects (74%), followed by glaucoma (52%), and then by normal individuals (22%). The author concluded that the water-drinking test cannot be used to separate the four categories described and is therefore of very limited value as a provocative test for chronic simple glaucoma. Level of Evidence – 3 Rasmussen KE, Jorgensen HA. Diagnostic value of the water-drinking test in early detection of simple glaucoma. Acta Ophthalmol (Copenh). 1976 Apr;54(2 p):160-6 A series of 64 patients (119 eyes) subjected 10 years previously to water provocative tests on a suspicion of simple glaucoma were followed up. At that time the intraocular tension exceeded 20 mmHg, but there were no optic disc changes and no visual field defects. Setting a rise of 8 mmHg as the lower limit, the water provocative test ten years previously had been positive in 31 eyes. Nine of these developed glaucomatous visual field defects despite treatment (29 per cent). The test had been negative in 88 eyes. Of these, 21 (24 per cent) developed glaucomatous visual field defects. The water-drinking test was negative in 70 per cent of the eyes which subsequently developed visual field defects and negative in 75 per cent of those in which no defects developed. Thus the test was neither of diagnostic nor of prognostic value. This indicated that a negative water-drinking test gave a false security. An alteration of the lower limit of a tension rise does not render the water provocative test any more useful. Level of Evidence – 2 Recommendation – C Susanna R Jr, Vessani RM, Sakata L, Zacarias LC, Hatanaka M. The relation between intraocular pressure peak in the water drinking test and visual field progression in glaucoma. Br J Ophthalmol. 2005 Oct;89(10):1298-301 This is a retrospective analysis of 76 eyes of 76 open angle glaucoma patients followed for a mean period of 26.0 (SD 13.8) months. Patients were submitted to the water drinking test at the beginning of the follow up period. The results of the water drinking test were compared between glaucomatous eyes with and without visual field progression. A significant difference of 1.9 (SD 0.6) mm Hg (p = 0.001, analysis of covariance; 95% CI 0.8 to 3.0) was observed between glaucomatous eyes that showed visual field deterioration and glaucomatous eyes that did not progress. A significant difference of 16.8% (SD 4.6%) in the mean percentage of IOP variation was also observed between the two groups (p<0.001, analysis of covariance; 95% CI 7.7 to 26.0). The authors suggested that the water drinking test is a low cost and feasible test and may reflect one of the important and common disturbances to steady state IOP during a common activity of daily living: drinking water. The also suggested that the emphasis on the value of the water drinking test should be changed. It may be useful as a complementary exam to check IOP control in the clinical practice. The concluded that the peak and percentage of IOP variation of this test should be considered when analysing risk factors for glaucoma progression and that future randomised controlled longitudinal studies may give a better evaluation of this possibility. Level of Evidence – 2 Recommendation – C 8. Central Corneal Thickness Key Questions Question 1: For which patients is pachymetry appropriate? Question 2: What is the optimal way to measure CCT and when? Question 3: What, if any, correction factor should be applied on measuring IOP? Evidence Synthesis Behki R,. Damji KF, Crichton A for the CCT workshop participants Canadian perspectives in glaucoma management: the role of central corneal thickness Can J Ophthalmol. 2007; 42 (1): 66-74. The above report is based on evidence from a review of glaucoma literature, a Canadian consensus development workshop and the personal clinical experience of the participating Canadian Ophthalmologists. Question 1 For which patients is pachymetry appropriate? CCT should be measured in glaucoma suspects and considered in those with definite glaucoma. Measuring CCT consistently provides additional knowledge regarding IOP accuracy as well as possible prognosis and future treatment effect. Published evidence regarding the value of CCT for prognostic information is strong in the case of patients with ocular hypertension but considerably weaker in patients with established glaucoma. It is important to educate patients regarding their CCT and its implications, although this will need to be tailored given a potentially short encounter time and the complexity of the discussion. Significant deviations of CCT from the appropriate population mean, may change our strategy in management of these patients (i.e., ocular hypertensive patients with very thick corneas, or very thin corneas in patients with borderline pressures). Question 2 What is the optimal way to measure CCT and when? 1. Ultrasonic pachymetry by a trained individual 2. At least 2 hours after patient awakening. 3. Record time of day. 4. Consider repeating at least once on a different visit 5. Beware of confounding factors (e.g., contact lenses, photorefractive keratectomy, Fuchs’ endothelial dystrophy) Question 3 What, if any, correction factor should be applied? 1. There was no universally agreed-upon nomogram that the group could recommend that could be applied as a correction factor. Nevertheless, currently available nomograms may be helpful in estimating the amount that the pressure reading is over or under the actual IOP. 2. Always communicate measured IOP rather than corrected IOP The Guidelines ICO – Recommends measurement (A:II) AAO – Measurement of central corneal thickness aids the interpretation of IOP measurement results and stratification of patient risk. (A:II) Singapore – pachymetry may be employed according to the clinical context RCOphth - Thinner than average central corneal thickness is a risk factor for the conversion of OHT to POAG Asia Pacific – Thicker corneas are associated with artificially elevated IOP measurements, thinner corneas with artificially depressed IOP measurements: apply correction 1-3 mm HG/40μ deviation from 525 μ on applanation tonometry. European Glaucoma Society – Central corneal thickness measurements are valuable 1) only to correct for Goldman applanation IOP measurement, 2) if interpreted within the general variability of tonometry readings, 3) especially when treatment of ocular hypertension is being considered, 4) when clinical findings do not match with IOP and 5) after corneal refractive surgery Finland – explanation to its relationship to IOP AOA - The general consensus seems to be that measuring CCT by pachymetry is only necessary in rare circumstances. The effect of CCT variation on applanation tonometry readings does not appear sufficient to influence treatment decisions. 9. Measurement of Intraocular Pressure Key Questions Question 1 - Is there evidence of any factors that need to be taken into account in a clinical situation for determining the final IOP reading? Question 2 - Is there evidence on the reliability of the different types of tonometer in the measurement of intraocular pressure? Question 1 - Is there evidence of any factors that need to be taken into account in a clinical situation for determining the final IOP reading? Evidence Synthesis: There is no evidence synthesis report on this question The Guidelines ICO – 1) IOP should be measured (A:I). 2) Time of day recorded because of diurnal variation (B:III) AAO – 1) Intraocular pressure is measured in each eye (A:I), preferably using a contact applanation method (typically a Goldmann tonometer) before gonioscopy or dilation of the pupil.(A:III). 2) Time of day should be recorded because of diurnal variation. (B:III), (C:III) in a glaucoma suspect. The assessment may benefit from determining diurnal IOP fluctuations, either on the same day or on different days, which may be indicated when disc damage exceeds the amount expected based on a single IOP measurement. Singpore - People suspected of glaucoma should undergo measurement by Goldmann applanation tonometer (Grade C, Level IV) RCOphth - IOPs recorded during the process of management should be considered to be measured samples of a true IOP that may be fluctuating. Before attributing too much significance to a single reading ("high" or "low"), the following factors should be considered:-i) measurement error which may be equipment and/or patient/operator related ii) diurnal variation Asia Pacific gives a detailed review of all the factors that need to be taken into account as follows Circadian Cycle: The IOP follows a circadian cycle, often with a peak in the morning and a trough in the evening. The normal diurnal variation is 3-6 mm Hg Central Corneal Thickness: Thicker corneas are associated with artificially elevated IOP measurements, thinner corneas with artificially depressed IOP measurements: apply correction 1-3 mm HG/40μ deviation from 525 μ. Blood Pressure: IOP is systemically associated with systemic blood pressure, particularly systolic blood pressure. Age: In Caucasians, each decade after 40 years of age is associated with an approximate increase of 1 mmHg in IOP. Systemic hypertension may confound this relationship. Exercise: Exercise may increase (e.g. yoga head-down positions) or reduce (by dehydration and/or acidosis) IOP by 3-6 mmHg Lifestyle: Large volume rapid fluid intake increases IOP, while alcohol and marijuana depress it. Posture: Horizontal or head down position increases IOP. European Glaucoma Society - Corneal characteristics that can affect IOP measurements are corneal thickness, curvature and hydration. A tight collar or tie, Valsalva manoeuvre, holding breath, a lid speculum or squeezing the lids can all falsely increase the IOP reading. Finland - A single value of IOP does not give a true picture of the diurnal variation of IOP. The least progression of the disease has been found in glaucoma patients whose diurnal pressure variation was modest. Intraocular pressure varies at different times of the day and the highest values are usually measured in the morning. Small central corneal thickness value may result in low IOP readings and large value in high IOP readings. A meta-analysis reported that a 10% difference in corneal thickness results in approximately 3.4mmHg difference in IOP. AOA – 1) Measurement of the IOP should precede papillary dilation and gonioscopy. 2) The time of day at examination should be recorded. 3) Multiple measurements in each eye (serial tonometry) at various times of the day may help to evaluate diurnal variability.4) Attention should be directed toward differences between the IOPs of the two eyes and changes in pressure over time. The Literature Most of the literature on this topic has been presented with the risk factors for glaucoma. There will therefore be no further discussion of the literature for this topic Question 2 - Is there evidence on the reliability of the different types of tonometer in the measurement of intraocular pressure? There are many types of tonometers and they are broadly differentiated by the physical principle by which they measure the IOP, portability and contact with the cornea. The Goldmann applanation tonometer is currently the gold standard. As for the rest, there is no evidence synthesis report on their reliability and the literature search did not return a general review. Publications comparing the different types of tonometers are rife, but results are inconsistent and there is no uniformity between the populations or the combination of tonometers compared. This section therefore will only review the different types of tonometers The Tonometers The Goldmann applanation tonometer (Haag Streit AG, Bern, Switzerland) is currently the most widely used tonometer by ophthalmologists in their consulting rooms, and is considered to be the gold standard for measuring intraocular pressure (IOP).The Goldmann tonometer, however, cannot be used for bedridden patients, for younger children, in the operating room, and in other situations outside the consulting room. Although there is a portable Goldmann applanation tonometer (Perkins; Clement-Clarke Inc., Columbus, OH, USA), it is not always suitable. Other portable tonometers have been developed, and the Tonopen (Mentor, Santa Barbara, CA, USA) is the oldest of these. It is a handheld device that uses the same physical principle as the Goldmann applanation tonometer. An earlier version of the Tonopen was the Oculab Tonopen and the latest version is the Tonopen XL.1 For half a century the Schiotz tonometer, an indentation tonometer, was the standard for measuring IOP and it is still useful for measurements at the bedside and in the operating room. Measurement errors can be introduced by the instrument and the observer. Variations in the curvature and thickness of the cornea and ocular rigidity affect the measurement. With indentation tonometry a relatively large amount of fluid is displaced, which increases the pressure by an amount that varies with the scleral rigidity. If the rigidity is high, the pressure may be overestimated; and if low, underestimated. Indentation of the eye by the plunger pushes fluid out of the eye, so repeat measurements over a short period of time lower the pressure, which also reduces measurement reliability.2 There are several models of the air puff non contact tonometer, which uses air to flatten the cornea. These include the Topcon CT-10, Reichert XPERT and NCT II and Keeler PULSAIR.3 The TGDc-01 (Ryazan State Instrument-making Enterprise, Ryazan, Russia), is a portable tonometer. It has been designed to measure the IOP through the eyelids, without anaesthesia or contact with the cornea. The movement pattern of a small rod falling freely onto the eyelid surface is measured. Individual measurements are displayed digitally. Three measurements are advised in the interest of reliability.1 The ICARE tonometer (TA01; Tiolat Oy, Helsinki, Finland) uses the impact rebound principle. A small probe is propelled against the cornea, impacts with it and rebounds from the eye. The movement of the probe induces a small induction current enabling the impact duration to be measured. It is a handheld tonometer with single-use probes that can be used without anaesthesia. Individual measurements are digitally displayed, and after six consecutive measurements the average result is given as well as a variability measure.1 The dynamic contour tonometer (DCT, Pascal tonometer, SwissMicrotechnology AG, Port, Switzerland) was recently introduced as a new method of intraocular pressure measurement, supposedly independent of corneal properties. It is a slit lamp-mounted device for contact tonometry that is based upon corneal contact without corneal applanation. Dynamic contour tonometry (DCT) claims independence of corneal properties by measuring IOP without causing considerable corneal deformation. A contour matched pressure-sensing tip is applied to the corneal surface with a small constant force and allows direct transcorneal IOP measurement. Diastolic IOP, ocular pulse amplitude, and the quality of data (Q1–5) are reported on a digital display.4 The Proview phosphene tonometer is based on the principle that pressure applied to the sclera generates a self perceptible visual phenomenon, known as a phosphene spot. The threshold pressure for creating a phosphene spot may provide an indication of IOP. The tip of the tonometer is pressed against the closed eyelid, and the pressure is read from the scale on the side of the device when the patient detects the phosphene. The Proview method has several theoretical advantages over the Goldmann method. It is relatively simple to use without extensive training, and it does not require anesthetic drops, fluorescein, or expensive equipment. As it does not require contact with the cornea, it may be useful for patients with corneal abnormalities that may interfere with accurate pressure measurements. By not applanating the cornea, the Proview may also circumvent inaccuracies related to corneal thickness.5 The ocular response analyser (ORA) determines corneal biomechanical properties using an applied force–- displacement relationship. An air jet similar to that used in traditional air-puff tonometers generates force/ pressure on the cornea. To distinguish between corneal biomechanical properties and IOP, the ORA uses a method that eliminates the potential interference between the two factors in a single measurement. Pairs of measurements are used because a measurement of a single parameter cannot determine the independent corneal properties and IOP. 5 The ocular blood flow (OBF) pneumotonometer (OBF Laboratories, Malmesbury, Wiltshire, England), now being marketed as the Ocular Blood Flow Analyser (Paradigm Medical Industries, Salt Lake City, UT), is a relatively new method of tonometry. The pneumotonometer also measures pulsatile ocular blood flow and hence can achieve two purposes in one measurement.6 1. Liane H. van der Jagt and Nomdo M. Jansonius. Three portable tonometers, the TGDc-01, the ICARE and the Tonopen XL, compared with each other and with Goldmann applanation tonometry Ophthal. Physiol. Opt. 2005 25: 429–435 2. Ravin JG, Higginbotham EJ. Are we there yet? Celebrating the centennial of the Schiotz tonometer. Arch Ophthalmol. 2006 Sep;124(9):1337-8. 3. Brencher HL, Kohl P, Reinke AR, Yolton RL. Clinical comparison of air-puff and Goldmann tonometers. J Am Optom Assoc. 1991 May;62(5):395-402 4. Schneider E, Grehn F Intraocular pressure measurement-comparison of dynamic contour tonometry and goldmann applanation tonometry. J Glaucoma. 2006 Feb;15(1):2-6. 5. Herndon LW. Measuring intraocular pressure-adjustments for corneal thickness and new technologies. Current Opinion in Ophthalmology 2006, 17:115–119 6. Bhan A, Bhargava J, Vernon SA, Armstrong S, Bhan K, Tong L, Sung V. Repeatability of ocular blood flow pneumotonometry. Ophthalmology. 2003 Aug;110(8):1551-4. The Guidelines Asia Pacific - Use Goldmann style applanation tonometer and Tonopen if not available. Pneumotonometer and Schiötz tonometer are less than ideal. The guidelines also describe in detail 1) how to perform Goldmann tonometry, 2) factors affecting measured IOP (as above), 3) measurement errors associated with Goldmann applanation tonometry, 4) how to test calibration of a Goldmann tonometer and 5) tonometry mires. European Glaucoma Society – Recommendations on methods of tonometry are as follows 1) air puff tonometry is not recommended for evaluation of patients with glaucoma. 2) pneumatonometry is useful in eyes with scarred, oedematous and irregular corneae and 3) the Tonopen is useful in patients with corneal oedema or irregularities. Finland - 1) the non contact tonometer may give different readings to the applanation tonometer. 2) the Schiötz tonometer is best suited to for the diagnosis of closed angle glaucoma. 10. Gonioscopy Key Question – Is there evidence that goniscopy is essential for the detection of chronic open angle glaucoma? Evidence Synthesis – there is no evidence synthesis report on this question. The Guidelines ICO – initial evaluation includes gonioscopy (A:III) AAO - The diagnosis of POAG requires careful evaluation of the anteriorchamber angle to exclude angle closure or secondary causes of IOP elevation, such as angle recession, pigment dispersion, peripheral anterior synechiae, angle neovascularization, and trabecular precipitates.(A:III). Singapore – gonioscopy demonstrates an open angle which is a sign of POAG. RCOphth - The starting point is a detailed baseline assessment which under normal circumstances would include an examination of the anterior segment with a slit-lamp, at least one IOP measurement, and gonioscopy. Asia Pacific – 1) a gonioscope that allows indentation gonioscopy is included in the minimal acceptable resources for examination. 2) gonioscopy is mandatory for every glaucoma suspect, irrespective of whether the suspicion is based on a raised IOP, optic disc or visual fields finding. European Glaucoma Society – gonioscopy is an essential part of the evaluation of all glaucoma patients. Finland - The diagnosis of glaucoma is based on the examination of the optic nerve head, nerve fibre layer, visual fields, IOP level and gonioscopy. AOA - Careful evaluation of the anterior chamber angle is essential for differentiating between open angle and closed angle glaucomas, and for distinguishing primary glaucoma from many secondary glaucomas. It may be valuable to evaluate the angle both before and after dilation of the pupil. Standard classification and drawing at initial visit are suggested. The Literature The literature on gonioscopy is old and was mostly written to describe the procedure and the different classification systems. Following this, there has been very little mention of gonioscopy in the literature. 11. Pupil Dilatation Key Questions Question 1 – is there evidence that pupil dilatation is essential in the assessment of the glaucoma patient? Question 2 – is there evidence that pupil dilatation in the glaucoma patient is safe? Question 1 – is there evidence that pupil dilatation is essential in the assessment of the glaucoma patient? Evidence Synthesis – there is no evidence synthesis report on this question The Guidelines ICO – the initial evaluation to include evaluation of the fundus (through a dilated pupil whenever feasible) (A:III) AAO – 1) the preferred technique for optic nerve head and retinal nerve fibre layer evaluation involves magnified stereoscopic visualization (as with the slitlamp biomicroscope) preferably through dilated pupil. (A:III) Inability to dilate (or the reason not to dilate) the pupil should be documented (B:III) and 2) examination of the fundus, through a dilated pupil whenever feasible, includes a search for other abnormalities that might account for visual field defects (e.g., optic nerve pallor, tilted disc, disc drusen, optic nerve pits, optic nerve hypoplasia, neurological disease, macular degeneration, and other retinal disease). (A:III) Singapore – no mention RCOphth - A careful stereoscopic disc assessment through the dilated pupil and drawing completes the pre-treatment picture. Asia Pacific – Stereoscopic view for optic disc examination is best when the pupil is dilated and this is recommended when safe. European Glaucoma Society – the pupil should be dilated whenever possible to facilitate the examination of the optic nerve head and the nerve fibre layer. Finland – no mention AOA – 1) optic nerve and nerve fibre layer assessment should be through a dilated pupil if clinically appropriate. 2) The ability to diagnose PEX can be increased by 10−20 percent when biomicroscopy is performed through a dilated pupil as pigment may be dispersed from the pigment epithelium of the iris near the pupil, and the peripheral granular zone on the anterior surface of the lens in PEX is best viewed through a dilated pupil. Evidence Level – 4 Recommendation - D Question 2 – Is there evidence that dilatation of the glaucoma patient is safe? Evidence Synthesis Pandit RJ, Taylor R. Mydriasis and glaucoma: exploding the myth. A systematic review. Diabet Med. 2000 Oct;17(10):693-9. In this systematic review, the authors investigated the risk of inducing acute glaucoma following mydriasis. They identified 28 studies published between 1933 and 1999 and categorised them into those on the general population, on people with chronic glaucoma, on eyes following iridectomy for acute glaucoma and on untreated ‘high risk’ fellow eyes. They found that the risk of inducing acute glaucoma following mydriasis with tropicamide alone is close to zero, no case being identified and the risk with long-acting (atropine or homatropine) or combined agents (tropicamide plus phenylephrine) is between 1 in 3380 and 1 in 20 000. The presence of chronic glaucoma constitutes no additional risk. They concluded that mydriasis with tropicamide alone is safe even in people with chronic glaucoma. Level of Evidence - 1 Hancox J, Murdoch I, Parmar D Changes in intraocular pressure following diagnostic mydriasis with cyclopentolate 1%. Eye. 2002 Sep;16(5):562-6. In this study the IOP of 83 cataract, 87 medical retinal and 100 glaucoma patients was measured with Goldmann applanation tonometry before and 45 minutes after dilatation with 1% cyclopentolate. An approximately normal distribution of change in IOP following dilatation was seen in all three groups (mean change 0.4 mmHg (95% CI 0.1–0.8)). Two glaucoma patients with open angles developed a clinically important (>10 mmHg) sustained rise in IOP requiring treatment. In medical retina and cataract patients, sustained clinically important rises in intraocular pressure following dilation seem rarer. The authors recommended that the IOP be rechecked after dilation in glaucoma patients with significantly damaged optic nerve heads. Level of Evidence – 3 Recommendation – B (In view of the findings of the Hancox et al study) 12. Optic Disc Examination Key Questions Question 1 - Is there evidence of optic nerve head changes that are pathognomonic of chronic open angle glaucoma? Question 2 – Is there evidence that the new technologies for analysis of the optic nerve head contribute to the detection of glaucoma? Question 1 - Is there evidence of optic nerve head changes that are pathognomonic of chronic open angle glaucoma? Evidence Synthesis – there is no evidence synthesis report on this question. The Guidelines ICO – no mention AAO – 1) diffuse thinning, focal narrowing, or notching of the optic disc rim, especially at the inferior or superior poles, 2) disc rim hemorrhages or 3) optic disc neural rim asymmetry of the two eyes consistent with loss of neural tissue. 4) visible structural alterations of the optic nerve head and development of peripapillary choroidal atrophy frequently occur before visual field defects can be detected. Careful study of the optic disc neural rim for small hemorrhages is important, since these hemorrhages can precede visual field loss and further optic nerve damage. Singapore - The hallmark of glaucoma is thinning and damage to the neuroretinal rim of the optic disc, resulting in the following appearances 1) increased cup-disc ratio (C/D), 2) focal thinning or notching of the neuro-retinal rim and 3) optic disc haemorrhage. RCOphth – Because the concept of that POAG only occurs with pressures over 21 mmHg is incorrect, increasing emphasis has been placed upon the morphological changes occurring at the optic nerve head and retinal nerve fibre layer. Asia Pacific - 1) Features of the neuroretinal rim that would raise suspicion that glaucomatous damage has already occurred including notching or the rim (especially to the disc margin), haemorrhage crossing the rim, undercutting of the rim, asymmetry of rim width between the eyes in the absence of asymmetry of disc size or an abnormally thin rim in one or two sectors. An approximate rule is that a vertical cup disc ratio of >0.7 is strongly or loss of rim to the disc margin anywhere outside the temporal sector is suggestive of glaucoma, 2) The ISNT rule is that normally the thickest to the thinnest parts of the neuroretinal rim of the optic disc are Inferior Superior Nasal Temporal. Any variation from this may help detect glaucomatous damage European Glaucoma Society – 1) Glaucoma is characterised by progressive thinning of the neuroretinal rim. The loss of rim may take the form of diffuse thinning, localised notching or both in combination. Thinning of the rim, while occurring in all disc sectors, is generally greatest at the inferior and superior poles leading to a loss of the physiological rim shape so that the inferotemporal rim is no longer the thickest. The optic cup often enlarges in all directions, but usually the enlargement occurs predominantly in the vertical direction as a result of rim loss at the poles. 2) Since the prevalence of disc haemorrhages is low in the normal population, their presence is very likely to be pathological. 3) Because some degree of parapapillary atrophy is present in many normal eyes, a large area of atrophy should be regarded as an extra clue to local vascular damage associated with glaucoma. 4) An early sign of acquired rim thinning is a circumlinear vessel becoming bared. A difference in cup/disc ratio between eyes with equal overall optic disc size is suggestive of tissue loss and therefore is highly suspicious of acquired damage. 5) The rim/disc ratio is the fractional decimal value obtained dividing the rim thickness by the disc diameter. The closer its value is to 1, the better the disc appearance. Finland – 1) Structural abnormalities in the optic nerve head precede visual field ones. 2) The preperimetric glaucoma is defined by normal visual field in spite of structural abnormalities in the optic disc and the nerve fibre layer. 3) A large cup in a large disc raises suspicions of glaucoma even if the IOP is not elevated. A small optic nerve head is more insidious because early disc abnormalities may go unnoticed. 4) A splinter haemorrhage in the nerve head may foretell and precede the glaucomatous damage and its progression both in the optic disc, nerve fibre layer and visual fields. 5) Peripapillary atrophy is more prevalent in glaucoma subjects than in the healthy population but its significance for the aetiology and progression of disease abnormalities is unclear and its presence cannot be used to distinguish between healthy and glaucomatous subjects. AOA 2) Features of the neuroretinal rim that would raise suspicion that glaucomatous damage has already occurred including notching or the rim (especially to the disc margin), haemorrhage crossing the rim, undercutting of the rim, asymmetry of rim width between the eyes in the absence of asymmetry of disc size or an abnormally thin rim in one or two sectors. An approximate rule is that a vertical cup disc ratio of >0.7 is strongly or loss of rim to the disc margin anywhere outside the temporal sector is suggestive of glaucoma, 3) The ISNT rule is that normally the thickest to the thinnest parts of the neuroretinal rim of the optic disc are Inferior Superior Nasal Temporal. Any variation from this may help detect glaucomatous damage The Literature – The fundamental optic disc changes in chronic open angle glaucoma were described in the seventies and eighties. Since that time, there has been isolated publications confirming or quantifying these changes and differentiating between glaucomatous and non glaucomatous optic disc cupping. No recent comprehensive review of this question was found in the peer reviewed literature although it has been reviewed in several textbooks. Question 2 – Is there evidence that the new technologies for analysis of the optic nerve head contribute to the detection of glaucoma? Evidence Synthesis Committee on Ophthalmic Procedures Assessment American Academy of Ophthalmology. Optic nerve head and retinal nerve fiber layer analysis. Ophthalmology. 1999 Jul;106(7):1414-24. This report reviewed the literature on the Rodenstock Optic Nerve Head Analyser (no longer manufactured), the Heidelberg Retina Tomograph (HRT), Scanning Laser Polarimetry (SLP; example of which is GDx) and Optical Coherence Tomography (OCT) for their advantages, disadvantages, sensitivity, specificity, accuracy, sources of error and reproducibility in the detection of glaucoma. Only the Rodenstoch Optic Nerve Head Analyser and the Heidelberg Retina Tomograph were evaluated in relation to the optic nerve head. HRT has been shown to have high reproducibility, but relatively poor correlation with an experienced observer’s assessment of optic disc parameters. It has the advantage of obtaining images through an undilated pupil and through cataracts, although one study showed reduced reproducibility in patients using pilocarpine. Several studies have also shown that the standard optic disc parameters, such as the cup to disc ratio, rim area, and cup area, are no longer adequate to distinguish subtle findings in the optic nerve head of glaucomatous eyes. First, there is overlap between what is considered normal optic nerve and early glaucomatous optic neuropathy when only looking at these parameters. Second, focal loss of rim area may well be missed when only these parameters are considered. This problem was addressed by incorporating other parameters into the HRT software. One of these parameters is the cup shape measure. In clinical studies it has shown some promise in correlating with automated perimetry parameters. However, this correlation was not adequate to detect early to moderate glaucoma damage as measured by achromatic automated perimetry. The Heidelberg Retina Tomograph sensitivity and specificity to detect glaucomatous optic neuropathy were variable, largely due to the study design of selecting patients with variable degrees of visual field loss as well as to the statistical methods employed in the study. Despite the seemingly high sensitivity and specificity, this should be in interpreted with caution given the low prevalence of glaucoma. However, HRT may be useful in monitoring patients with glaucoma because of its high reproducibility. Level of Evidence - 1 The Literature The following two reviews were published five years later and their conclusions did not differ much with those of the assessment report above. Stein DM, Wollstein G, Schuman JS Imaging in glaucoma. Ophthalmol Clin North Am. 2004 Mar;17(1):33-52 Burgoyne CF. Image analysis of optic nerve disease. Eye. 2004 Nov;18(11):1207-13. The following report was commissioned by the NHS R&D Health Technology Assessment Programme. The work was based at the Manchester Royal Eye Hospital. Kwartz AJ, Henson DB, Harper RA, Spencer AF, McLeod D The effectiveness of the Heidelberg Retina Tomograph and laser diagnostic glaucoma scanning system (GDx) in detecting and monitoring glaucoma Health Technology Assessment 2005; Vol. 9: No. 46 The objectives of this study were 1) to compare the diagnostic accuracy of optic nerve head tomography (HRT) and scanning laser polarimetry (GDx) for identifying patients with glaucomatous visual field loss, 2) to investigate the applicability of the instruments in an unselected population of hospital patients, 3) to measure the length of time required for a full examination and 4) to calculate between- and within-observer variability in HRT and GDx measurements. The study examined two groups of patients cross-sectionally (150 glaucoma patients and 100 normal individuals) and two groups longitudinally (240 high risk eyes and 75 glaucoma patients). Each examination session involved image capture with the HRT and GDx and assessment with the 24-2 full threshold program of the HFA. Patients within the cross sectional groups underwent a single examination, whereas patients in the longitudinal groups were examined 6 monthly for an average of 3.5 years. From the cross-sectional group, the maximum sensitivities of the HRT and GDx were 59% and 45%, respectively (at 95% specificity). From the two longitudinal cohorts, the level of agreement between the three instruments for identification of the development and deterioration of POAG was low. The applicability of the techniques was 80% (HRT), 88% (GDx) and 98% (HFA). The length of time to perform a full examination with each instrument was 12.3, 11.8 and 28.3 minutes, respectively. Agreement of HRT and GDx parameters between and within observers was largely good. The research concluded that there is little agreement between HFA, HRT and GDx. The techniques are amenable to use in the clinical environment but no single examination has sufficient diagnostic precision to be used in isolation. In order to provide a full investigation of the glaucoma patient or suspect, the clinician needs a stereoscopic examination of the ONH and RNFL with true colour representation. This examination is necessary in order to detect changes such as RNFL haemorrhages or pallor of the neuro-retinal rim, which are significant findings in glaucoma. Such alterations cannot easily be detected with the HRT or GDx. The findings of the glaucoma imaging study suggest that, although the HRT and GDx provide good-quality digital images, their data may contribute little to a patient’s clinical diagnosis but would add significantly to the cost of their assessment. The Guidelines ICO – Key elements of the initial examination are 1) evaluation of optic nerve head with magnified stereoscopic visualization (A:III) and 2) documentation of the optic disc morphology, best performed by colour stereophotography or computer-based image analysis (A:II) AAO – 1) There is evidence that glaucomatous changes detected by analysis of the optic nerve head may precede changes detected by standard automated perimetry. 2) The preferred technique for optic nerve head involves magnified stereoscopic visualization (as with the slit-lamp biomicroscope) preferably through a dilated pupil. (A:III}. 3) Direct ophthalmoscopy is useful in some cases to complement magnified stereoscopic visualization, providing more comprehensive information of optic nerve detail due to the greater magnification of the direct ophthalmoscope. 4) Color stereophotography or computer-based image analysis of the optic nerve head (A:II} are recommended for documentations. In the absence of these technologies, a nonstereoscopic photograph or a detailed drawing of the optic nerve head should be recorded but these are less desirable alternatives to stereophotography or computer-based imaging. (A:III) Singapore – Optic nerve head imaging is an ancillary test which may be employed. RCOphth - Baseline appearance of the optic disc may be obtained by various means including stereophotography or computerised digital imaging. Asia Pacific – 1) The disc size can be measured using a thin slit lamp beam, the small size spot of the direct ophthalmoscope, photography with an overlay grid or imaging. .2) Qualitative methods for assessment of optic disc are direct ophthalmoscopy, indirect slit lamp ophthalmoscopy, disc photograph and simultaneous stereophotography. Quantitative methods are disc photography with digitalisation, stereo disc photography with optic disc analysis, confocal laser scanning ophthalmoscopy, laser polarimetry and optical coherence tomography. European Glaucoma Society – Lists imaging technology but no evaluation Finland – 1) Description of the optic disc, estimation of cup/disc ratio or a drawing are not as accurate as optic disc photography or imaging. However, optimum usage of images requires profound experience. 2) High technology instruments (the Heidelberg retina tomograph, retinal nerve fibre analyser and optical coherence tomography), developed for nerve fibre layer and optic disc imaging and measurements, are not yet ready for routine glaucoma diagnostics, although due to their sensitivity and specificity, some may be used for the follow-up of glaucoma AOA – 1) Examination of the ON requires procedures that provide stereoscopic visualization with adequate magnification, through a dilated pupil if clinically appropriate. Use of a biomicroscope with an ancillary lens is the preferred procedure for . A 60 D lens, a 66 D lens, or a contact fundus lens will enable the best stereopsis. Evaluation of the ON includes ruling out other potential causes. 2) Despite the large ON cups in eyes that eventually develop glaucoma, the clinical finding of a 0.6 cup-to- disc ratio has only about a 60 percent (41%−77%) sensitivity for predicting which cases of OH will convert to the disease. There is no cutoff value for cup-to-disc ratio that changes this conclusion. Determining the cup-to-disc ratio by direct ophthalmoscopy is even less precise, due to intraobserver and interobserver variability. The evidence suggests even greater variability in assessment of the notching or width of the neuroretinal rim. Topography of the optic nerve and configuration of the neuroretinal rim may be more sensitive and specific than the cup-to-disc ratio in the detection of glaucoma. 3) Stereoscopic fundus photography is useful for evaluating the ON because it reduces observer variability in assessment of the cup-to-disc ratio. 3) Users of confocal scanning laser tomography (CSLT) have concentrated on the early detection of patients with glaucoma. The most beneficial application of this technology may be in the detection and monitoring of subtle changes in ON tissue over time. Because of significant physiological variation of the optic nerve head within the normal population, even with an ideal imaging system, it is very difficult to identify early glaucoma accurately in a single session. Although with CSLT there is a tendency to overestimate the neuroretinal rim and to underestimate the cup-to-disc ratio, several recent studies have shown that the parameters generated by this technology are adequate for discrimination between normal optic nerve heads and those of patients with ocular hypertension and early glaucoma. CSLT has a sensitivity of 89 % and a specificity of 84 % for differentiating between subjects with early glaucomatous VF defects and normal eyes. 13. Examination of the Nerve Fibre Layer Key Questions Question 1 - Is there evidence that examination of the nerve fibre layer contributes to the detection of glaucoma? Question 2 – Is there evidence that the new technologies for examination of the nerve fibre layer contribute to the detection of glaucoma? Question 1 - Is there evidence that examination of the nerve fibre layer contributes to the detection of glaucoma? Evidence Synthesis – there is no evidence synthesis report on this question. The Guidelines ICO – A key element in the initial evaluation is examination of the retinal nerve fibre layer with magnified stereoscopic visualization (A:III) AAO - 1) Retinal nerve fibre layer evaluation (A III), 2) There is evidence that glaucomatous changes detected with optic disc and retinal nerve fibre layer analysis may precede changes detected by standard automated perimetry. 3) Examination of the retinal nerve fibre layer provides valuable structural information about glaucomatous optic nerve damage. 4) The preferred technique for optic nerve head and retinal nerve fibre layer evaluation involves magnified stereoscopic visualization (as with the slit-lamp biomicroscope) preferably through a dilated pupil. (A III). 5) Red-free illumination may aid in evaluating the retinal nerve fibre layer. Inability to dilate (or the reason not to dilate) the pupil should be documented. (B III). Colour stereophotography or computer-based image analysis of the optic nerve head and retinal nerve fibre layer are the best currently available methods to document optic disc morphology and should be performed. In the absence of these technologies, a nonstereoscopic photograph or a detailed drawing of the optic nerve head should be recorded but these are less desirable alternatives to stereophotography or computer-based imaging. Singapore – Nerve fibre layer imaging is an ancillary test which may be employed RCOphth – 1) Because the concept of that POAG only occurs with pressures over 21 mmHg is incorrect, increasing emphasis has been placed upon the morphological changes occurring at the optic nerve head and retinal nerve fibre layer. 2) Retinal nerve fibre layer defect in the absence of morphometric optic nerve head changes is a risk factor for the conversion of ocular hypertension to POAG. Asia Pacific – 1) Record whether nerve fibre layer is visible and assess for wedge or slit defects European Glaucoma Society – 1) The thickness of the nerve fibre layer depends on the disc area, age and stage of the glaucomatous damge.2) It was shown that vertical polar sectors were thicker than polar and temporal ones.3) It was shown the retinal nerve fibre layer height in normal was thicker than in glaucomatous subjects. 4) Localised loss of nerve fibre layer is more common in normal pressure glaucoma.5) A feature of the primary open angle glaucoma suspect is that the visual field and/or optic nerve and/or nerve fibre layer are normal or suspicious with at least one being suspicious. Finland – 1) The diagnosis of glaucoma is based on the examination of the optic nerve head. 2) Structural abnormalities in the optic disc and retinal nerve fibre layer precede visual field abnormalities. 3) Most cases of glaucoma – including the preperimetric glaucoma – may be diagnosed when the optic disc and the nerve fibre layer are examined in addition to visual field examination. 2) The preperimetric glaucoma is defined by normal visual field in spite of structural abnormalities in the optic disc and the nerve fibre layer. 4) Examination of the nerve fibre layer facilitates and supports the glaucoma diagnostics based on the optic disc and visual field evaluation, in particular with unusually small or large optic discs. It is possible to observe glaucomatous abnormalities in the nerve fibre layer before abnormalities can be detected in the optic disc and/or the visual field.5) A quality criteria for the self evaluation of glaucoma care is the proportion of patients who have had photography of the nerve fibre layer. AOA – 1) The procedure for evaluating the integrity of the NFL is similar to that described for the ON. The NFL is best visualized using stereo photographic techniques with red-free illumination and high-resolution black and white film. Serial NFL examination is more sensitive than colour ON evaluation in detecting the conversion of eyes from OH to POAG. In one study, a minority of the eyes (about 20%) with OH that converted to glaucoma over a 5-year period showed changes in the ON, while about 50 percent showed developing or worsening atrophy of the NFL. In another study, 60 percent of eyes with OH that converted to POAG had NFL defects at least 6 years before VF loss, and 88 percent had NFL defects at the time of the initial visual loss. Significant advances have occurred in techniques for assessing the NFL in the detection and progression of glaucoma. Studies have investigated the capabilities of scanning laser polarimetry, optical coherence tomography, and scanning laser ophthalmoscopy in distinguishing normal and OH eyes from those with POAG, as well as the reproducibility of results obtained with these instruments. Although the study results are encouraging with respect to accurate measurement of NFL thickness, whether these instruments have the sensitivity and specificity to detect the onset and the progression of glaucomatous damage remains to be determined. The correlations between VF indices and peripapillary NFL thickness have been weak, and the distribution of parameters measured by these techniques in normal eyes overlaps measurements made in eyes with OH or both OH and POAG, thereby reducing the sensitivity and the specificity of these tests. Question 2 – Is there evidence that the new technologies for examination of the nerve fibre layer contribute to the detection of glaucoma? Evidence Synthesis Committee on Ophthalmic Procedures Assessment American Academy of Ophthalmology. Optic nerve head and retinal nerve fiber layer analysis. Ophthalmology. 1999 Jul;106(7):1414-24. This report reviewed the literature on the Rodenstock Optic Nerve Head Analyser (no longer manufactured), the Heidelberg Retina Tomograph (HRT), Scanning Laser Polarimetry (SLP; example of which is GDx) and Optical Coherence Tomography (OCT) for their advantages, disadvantages, sensitivity, specificity, accuracy, sources of error and reproducibility in the detection of glaucoma. The HRT, SLP and OCT were evaluated in relation to the nerve fibre layer. Scanning laser polarimetry and optic coherence tomography were both shown to have good reproducibility and resolution as well as good correlation with histological measurements of the NFL thickness. Both have the advantage of obtaining measurements directly without a reference plane as well as of obtaining measurements independent of magnification and optical resolution of the human eye. However, the scanning laser polarimetry retardation measurements may be influenced by all of the polarizing structures of the eye, including the cornea, the lens, peripapillary atrophy, and chorioretinal scars. Optical coherence tomography requires pupillary dilation and may be influenced by certain types of cataract, such as posterior subcapsular and cortical opacities. The sensitivity and specificity are variable in clinical studies and are due largely to the use of different frequency distributions of what is normal, the definition of abnormal by visual field defects as measured by automated perimetry and statistical methods of analysis. Histopathologic studies and clinical studies have demonstrated tremendous variability of RNFL thickness in normal eyes. Obviously, this will limit the detection of early glaucoma using this measurement alone despite the reported high sensitivity and specificity. The Literature Bagga H, Greenfield DS. Retinal nerve fiber layer assessment using scanning laser polarimetry. Int Ophthalmol Clin. 2004 Spring;44(2):29-42. Review. This is a report which reviewed the historical development of GDx, its technological principles, reproducibility, sensitivity, specificity, capacity to detect glaucomatous progression, strengths and limitations. The authors found that numerous studies have reported high discriminating power for separating normal persons from those with glaucoma, and good agreement with other structural technologies and that recent advances in scanning laser polarimetry provide a means to obtain objective, quantitative, and reproducible structural measurements of peripapillary RNFL thickness. Using SLP with fixed corneal compensation, sensitivity and specificity values approximate 70% to 80% depending upon sample size, definition of glaucoma, and severity of glaucomatous damage. Methods for change detection exist but have not been prospectively validated in large populations. As with perimetry, it is not recommended that isolated clinical decisions be based solely upon ocular imaging results. Clinical correlation should be performed and treatment recommendations should be individualized. Stein DM, Wollstein G, Schuman JS Imaging in glaucoma. Ophthalmol Clin North Am. 2004 Mar;17(1):33-52 This review outlines confocal scanning laser ophthalmoscopy (CSLO), scanning laser polarimetry (SLP), optical coherence tomography (OCT), and the retinal thickness analyzer (RTA). It reviews their fundamentals, reproducibility, sources of error or variability, ability to distinguish normal from glaucomatous eyes, strengths and limitations. The authors concluded that although these measurements have been found to provide useful data for glaucoma detection in various regions of the posterior segment, further studies are needed to evaluate the utility of these technologies for preperimetric glaucoma detection and for monitoring glaucoma progression over an extended period. See also the health technology assessment above by Kwartz , Henson, Harper, Spencer and McLeod, 2005 The Guidelines ICO – no mention AAO – no mention Singapore – no mention RCOphth – no mention Asia Pacific – no mention European Glaucoma Society Imaging devices may aid clinical management. These include confocal scanning laser ophthalmosocopy (e.g. HRT), scanning laser polarimetry (e.g. GDx), optical coherence tomography (e.g. OCT) and retinal thickness analyser (e.g.RTA). It must be emphasised that the process of categorising patients by means of imaging device measurement is not the same as diagnosis. Diagnosis must integrate all the other available information including clinical assessment of the ONH and the RNFL, visual field and risk factors including IOP, age and family history. In the future, with greater clinical information being provided by optic disc measurement, and the cost of the instruments declining, the clinical use of these devices is likely to expand. Finland High technology instruments (the Heidelberg retina tomograph, retinalnerve fibre analyser and optical coherence tomography), developed for nerve fibre layer and optic disc imaging and measurements, are not yet ready for routine glaucoma diagnostics. Due to their sensitivity and specificity, some instruments may be used for the follow-up of glaucoma AOA Confocal scanning laser polarimetry, optical coherence tomography, confocal scanning laser ophthalmoscopy can be used in the assessment of the nerve fibre layer in the initial evaluation of glaucoma. 14. Visual Field Testing Key Question Is there evidence that examination of the visual field by any method of perimetry if useful in the diagnosis of glaucoma? Evidence Synthesis Delgado MF, Nguyen NT, Cox TA, Singh K, Lee DA, Dueker DK, Fechtner RD, Juzych MS, Lin SC, Netland PA, Pastor SA, Schuman JS, Samples JR; American Academy of Ophthalmology. Ophthalmic Technology Assessment Committee 2001-2002 Glaucoma Panel. Automated perimetry: a report by the American Academy of Ophthalmology. Ophthalmology. 2002 Dec;109(12):2362-74. Early detection of visual field defects is an important goal of current practice if glaucoma is to be diagnosed and treated in its earliest stages. Standard threshold automated perimetry involves determining the minimum luminance necessary for the patient to detect the presentation of a static white light stimulus of constant size in various locations of the visual field. Because standard threshold automated perimetry uses a static achromatic stimulus, it is thought to nonselectively invoke the two major groups of ganglion cells of the optic nerve, as they are now commonly classified. Since there is considerable overlap in the receptive fields of retinal ganglion cells, a test with a nonselective stimulus may not be highly sensitive for the earliest loss of retinal ganglion cells due to the considerable redundancy in the coverage of a given location in the retina. Therefore, unless the damage is very localised, standard threshold automated perimetry may not detect visual field loss until the optic nerve has already suffered considerable damage. One goal of current research is to develop quicker tests and evaluations that maintain or improve diagnostic accuracy and reproducibility to help detect glaucoma at an early stage and recognize slight disease progression. The ideal test would be rapid, inexpensive, applicable to the majority of the population, easy to use and highly sensitive and specific. This assessment describes four automated perimetry tests: blue-yellow perimetry, or short wavelength automated perimetry (SWAP); frequency doubling technology perimetry. (FDT); high-pass resolution perimetry (HPRP); and motion automated perimetry (MAP). The assessment also describes two static perimetry algorithms, the Swedish interactive threshold algorithm (SITA), and SITA fast. Short Wavelength Automated Perimetry (SWAP) Glaucomatous optic nerve damage may be associated with an acquired color vision deficit in the blue-yellow spectrum and/or red-green spectrum.7 It is proposed that blue-yellow perimetry, or SWAP, is more effective than whitewhite standard threshold automated perimetry in detecting early visual field loss. Frequency Doubling Technology Perimetry (FDT) The frequency doubling phenomenon, or “frequencydoubling illusion,” is a phenomenonwhere the alternating light and dark bars appear to have twice the actual number of bars when shown at low spatial frequency and high temporal frequency counterface flicker Frequency doubling technology perimetry is a contrast threshold test with a more complex target than standard threshold automated perimetry. High-Pass Resolution Perimetry (HPRP) High-pass resolution perimetry is thought to test the parvocellular system selectively. HPRP uses a photopic background on a cathode ray tube where ringshaped stimuli of various sizes are presented at different locations in the visual field. Instead of using differential light sensitivity, this test measures resolution threshold, the ability of the retina to resolve varying target sizes. Threshold is detected by 14 different ring-sized targets, which measure 50 locations within the central 30°. The central-most 5° and the vicinity of the blindspot cannot be quantified because of monitor limitations and because the targets subtend too large an angle (which is also why this test cannot measure a small isolated scotoma). Another substantial limitation is the inability to standardise between cathode ray tube monitors. Motion Automated Perimetry (MAP) Motion information travels through the magnocellular ganglion cells pathway, and the perception of motion is an essential visual function. Glaucoma patients have shown defects in motion perception as well as prolonged reaction times, and less precise localization of motion stimuli. Based on these findings, researchers have developed perimetric techniques to detect motion sensitivity defects. There are as many types of MAP protocols as there are different groups of researchers. Swedish Interactive Threshold Algorithm (SITA) Compared with newer strategies, conventional full threshold strategies use shorter stimulus steps and more reversals, producing longer testing staircase sequences, to establish threshold at each test locus. This results in longer tests, which are difficult to use in the clinical setting because they cause patient fatigue and compromise the reliability of the test. The Swedish interactive threshold algorithm (SITA) is a strategy designed to reduce testing time substantially without decreasing the quality of test results. Swedish Interactive Threshold Algorithm Fast (SITA fast) SITA fast reduces testing time with a test accuracy similar to FastPac This assessment addressed the following question: Can the automated perimetry tests and algorithms described detect glaucomatous damage or detect the progression of glaucoma? Blue-yellow perimetry, or SWAP, showed early detectionof glaucomatous loss (based on Level II evidence). This is a long and challenging test for patients to undergo. New developments on a SITA version of SWAP are being researched, and it is possible that further algorithm refinements similar to SITA may allow SWAP to be faster and thus more practical. Frequency doubling technology perimetry significantly reduces testing time and is not as affected by blur and pupil size as standard threshold automated perimetry. Studies also showed reduced intratest and intertest variability when compared to standard threshold automated perimetry. High sensitivity and specificity for FDT compared to standard threshold automated perimetry was demonstrated in one Level I study for detecting early, moderate, and advanced glaucomatous loss, although a Level II study found FDT less effective for advanced glaucoma. It may be that FDT perimetry is currently most useful as a screening tool, although further advances in this technology may allow it to become appropriate for long-term follow-up of patients. High-pass resolution perimetry can be sensitive to media opacities and blur. One Level I study demonstrated its ability to detect early glaucomatous loss and progression. It is associated with a shorter testing time and increased patient comfort relative to standard threshold automated perimetry, but prospective studies are needed to define its role in the clinical setting. Motion perception defects/deficits can be a strong predictor of visual field loss. Motion automated perimetry is useful for detecting early glaucomatous visual loss (Level I evidence), but its use has not yet been popularized. Studies on SITA show significant reduction in testing time (50%) without affecting diagnostic accuracy, making it a more patient-friendly test. It is associated with a greater sensitivity and reproducibility and less intertest variability when compared with standard full threshold testing (Level II evidence). It is important to establish a new baseline when patients are switched from the standard threshold automated perimetry algorithm to SITA. While this may be cumbersome in the short term, the switch to SITA is generally preferred by most patients. In principle, the different algorithms (SITA standard, SITA fast) can be applied on all different stimulus modalities. Not all combinations of algorithm and test are commercially available today. The Literature Henson Perimeter Henson DB, Bryson H Clinical results with the Henson-Hamblin CFS2000. Documenta Ophthalmologica Proceedings Series 49 Seventh International Visual Field Symposium, Amsterdam, September 1986 EL Greve and A Heijl (Eds) Henson-Hamblin CFS2000 is a computerised central visual field analyser which contains a screening programme that tests 26 retinal locations and a full programme which tests 132 stimulus locations. It also contains two quantification systems; the first gives an estimate of the likelihood that a given response is normal while the other gives a measure of the visual field survival (100-percent field loss). It uses a multiple stimulus suprathreshold static technique. The stimulus intensity is gradient adapted and increases by 0.8 log units from the centre of the visual field to an eccentricity of 25 degrees. In this study, 94 eyes from patients suspected of having glaucoma were examined. The screening programme was found to have a sensitivity of 90.5% and a specificity of 88.4%. The following studies have been published about alternative methods of visual field examination Confrontation Johnson LN, Baloh FG. The accuracy of confrontation visual field test in comparison with automated perimetry. J Natl Med Assoc. 1991 Oct;83(10):895-8. In this study, the accuracy of confrontation visual field testing was determined for 512 visual fields using automated static perimetry as the reference standard. The assessment was mainly for neurological field defects but confrontation testing was fairly insensitive (20%sensitivity) for detecting arcuate scotoma. The specificity of confrontation testing was high at 93.4%. The high positive predictive value (72.6%) and negative predictive value (75.7%) would indicate that visual field defects identified during confrontation testing are often true visual field defects. However, the many limitations of confrontation testing should be remembered, particularly its low sensitivity for detecting visual field loss associated with glaucoma. Shahinfar S, Johnson LN, Madsen RW. Confrontation visual field loss as a function of decibel sensitivity loss on automated static perimetry. Implications on the accuracy of confrontation visual field testing. Ophthalmology. 1995 Jun;102(6):872-7. This is a study to evaluate the accuracy of confrontation visual field testing with regard to the density of the visual field defect and its location in the peripheral visual field. Seventy-two patients with a variety of neurologic and ophthalmologic conditions underwent confrontation visual field testing full-threshold Humphrey automated static perimetry C24-2 or C30-2and. Confrontation visual field testing yielded an overall sensitivity for detecting an abnormal visual field of 63%, when sensitivity of confrontation testing rested on the detection of just one abnormal quadrant. The sensitivity of confrontation testing was 51% for arcuate scotomas. The sensitivity of confrontation testing was lower for superior quadrant defects and higher for inferior quadrant defects. Specificity was 97% and the positive predictive value was 96%. The authors concluded that confrontation visual field testing is relatively insensitive unless a moderate to dense defect is present, and as such is a poor screening test. However, when visual field defects are identified with confrontation visual field testing, the defects often are real with a high specificity and positive predictive values. Pandit RJ, Gales K, Griffiths PG. Effectiveness of testing visual fields by confrontation. Lancet. 2001 Oct 20;358(9290):1339-40. Erratum in: Lancet 2001 Nov 24;358(9295):1820. The authors prospectively compared seven confrontation field tests with fullthreshold automated static perimetry among 138 outpatients in an eye clinic. The primary outcome was detection of a defect in the visual field. Most confrontation field tests were insensitive in the identification of field loss. The most sensitive method was examination of the central 20 degrees visual field with a small red target (73% [95% CI 63-82]). Goldmann Perimetry The limitations of kinetic perimetry in early scotoma detection. Ophthalmology. 1978 Mar;85(3):287-93. When tested by Goldmann kinetic perimetry ten patients with glaucomatous optic disc cupping had no visual field defects, but visual field defects were detected when tested by threshold static perimetry on the Tubingen perimeter. Friedman Field Analyser Hicks BC, Anderson DR. Quantitation of glaucomatous visual field defects with the Mark II Friedmann analyzer. Am J Ophthalmol. 1983 May;95(5):692-700. In this study, the authors correlated the visual threshold determined kinetically (Goldmann perimeter) with the static threshold (Friedmann analyzer) in various parts of the central field. Friedmann working threshold correlated linearly with the height of the hill of vision represented by the position of the kinetic isopters of the Goldmann perimeter. The static visual threshold (Friedmann) at a particular location, whether normal or abnormal, was linearly related to the kinetic visual threshold (Goldmann) at that location. The depth of all visual field defects was essentially the same with both instruments. Thus, the Friedmann analyzer accurately quantitated the central visual field in both the normal and abnormal regions, and may be advantageous for following the progress of early glaucomatous defects. For other patients, however, its usefulness may be limited, because defects outside 25 degrees cannot be documented, the visual field examination may be lengthy and inefficient when quantitating large defects of irregular depth and the maximal quantitation of depth with the Friedmann analyzer is 2.0 log units less than with the Goldmann perimeter near fixation (but there is progressively less difference for defects further from fixation). The Guidelines ICO - Visual field evaluation, preferably by automated static threshold perimetry is a key element in the initial evaluation of the glaucoma patient (A:III) AAO - 1) The visual field abnormality considered a valid representation of the glaucoma patient’s functional status is a visual field damage consistent with retinal nerve fibre layer damage (nasal step, arcuate field defect, or paracentral depression in clusters of test sites) and visual field loss in the upper hemifield that is different compared with the lower hemifield, i.e., across the horizontal midline (in early/moderate cases). It should be reproducible and other known explanations for it should be absent. 2) Automated static threshold perimetry is the preferred technique for evaluating the visual field. (A:III) Careful manual combined kinetic and static threshold testing is an acceptable alternative when patients cannot perform automated perimetry reliably or if it is not available. (A:III)Causes of visual field loss other than glaucomatous optic neuropathy should be sought and assessed during the history review and physical examination. (A:III) Visual field testing based on short wavelength automated perimetry and frequency doubling technology may detect defects earlier than conventional white-on-white perimetry. It is important to use a consistent examination strategy when visual field testing is repeated. (A:III). Singapore – 1) If glaucomatous nerve damage has been sustained perimetry shows defects that are consistent with nerve fibre layer loss and these include: temporal island central island in advanced glaucoma, nasal step, paracentral or arcuate scotomas. 2) Psycho-physical tests (e.g. Short Wavelength Automated Perimetry, Frequency Doubling Threshold, etc may also be employed depending on the clinical context. RCOphth - The discovery that a significant number of the optic nerve fibres can be damaged before any change is detectable in visual function by standard automated perimetry (SAP) has lead to the concept of "glaucoma without field loss" or “pre-perimetric glaucoma”. However other psychophysical tests such as frequency doubled perimetry (FDP) and blue on yellow perimetry (SWAP) have consistently shown that defects in visual function are present before any defect can be detected by SAP. In this condition (usually with coexistent raised IOP) there is deemed to be unequivocal evidence of glaucomatous damage to the optic nerve head +/- the nerve fibre layer. Clearly, for some patients, there is a grey area between OHT and "glaucoma without field loss. Asia Pacific – 1) Users should read and be familiar with the perimeter manual. 2) The guidelines include an appendix on how to optimise patient performance in subjective perimetry. 3) Characteristics of glaucomatous visual field defects are that they are asymmetrical across the horizontal midline, located in the midperiphery in early and moderate cases, reproducible, not attributable to other pathology, clustered in neighbouring test points (localised) and the defect should correlate with the appearance of the optic disc and neighbourhood. European Glaucoma Society – 1) In the absence of retinal or neurological disease affecting the visual field, loss is considered significant when there is an abnormal Glaucoma Hemifield Test, confirmed on two consecutive tests, or 3 abnormal points confirmed on two consecutive tests, with p<5% probability of being normal, one of which should have p<1%, all being not contiguous with the blind spot, CPSD (corrected pattern standard deviation) <5% if the visual field is otherwise normal, confirmed on two consecutive tests. 2) Any defect or suspected defect must be confirmed by repeated testing.3) the guidelines discuss in detail the sources of error, the duties of the perimeter user, assessing the test results, including an explanation of the global indices, and the different grading systems for field defects. 4) Conventional techniques for visual field testing are Humphrey Perimeter 24-2 or 30-2, Octopus 32, Octopus program G1, SITA Standard and Fast for Humphrey and TOP for Octopus. Non conventional techniques are SWAP (Short Wavelength Automated Perimetry), FDT (frequency doubling technology) and HRP (High Pass Resolution Perimetry). Finland – 1) If the diagnosis of glaucoma is defined by visual field examination methods, the clinical significance of a single abnormal visual field is small. 2) In early glaucoma the visual field abnormalities are detected earlier with static automated perimetry than with kinetic visual field examination. 3) Blue-on-yellow perimetry may detect visual field abnormalities earlier and identify them as larger in size than traditional white-on-white perimetry. 4) Humphrey SITA standard and Octopus Dynamic are recommended are recommended for diagnosis and follow up. AOA – 1) Measurement of threshold levels in areas of the visual field likely to be affected by glaucomatous damage of the optic nerve should be made by perimetry through a pupil of adequate size. The results of perimetry should be compared with the reference values from an age-matched control population and evaluated with respect to the probability of abnormal (glaucomatous) findings. The clinician should consider factors that can influence interpretation of the findings, including the patient's learning curve. 2) FDT perimetry has demonstrated better patient reliability, less intratest and intertest variability, and results that are comparable to or better than standard automated perimetry for the detection of glaucoma. It appears that FDT can facilitate the diagnosis and grading of the extent of glaucoma. 3) Short-wavelength automated perimetry (SWAP) is useful in evaluating early or subtle diseases of the optic nerve and retina. A technique with which to isolate the blue colour (short-wavelength) vision mechanism, SWAP appears to uncover loss of visual function earlier in the disease process than traditional white-on-white automated perimetry. SWAP facilitates prediction of future defects that can eventually be found with white-on-white perimetry. The visual field defects found with SWAP are larger and progress more rapidly than those localized with white-on white automated perimetry. 4) An association between the prevalence of localized SWAP defects and other risk factors is predictive of the development of glaucoma in patients with OH. The longer duration of testing and the fluctuation of patient responses that may occur with SWAP are of clinical concern.
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