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Lincolnshire Knowledge and Resource Service
This search summary contains the results of a literature search
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Literature Search Results
Search completion date:
Search completed by:
6th March 2012
Alison Price
Enquiry Details
Long term effects of laser treatment on dermatological conditions such as vitiligo/
birthmarks/ rosacea
Systematic Reviews
Cochrane Skin Group Systematic Reviews
The following Cochrane Reviews address the use of lasers in dermatogy. Relevant
extracts are included.
van Zuuren EJ, Kramer S, Carter B, Graber MA, Fedorowicz Z. Interventions for
rosacea. Cochrane Database of Systematic Reviews 2011, Issue 3.
Laser and light therapies
Lasers and light therapies would appear to have a major clinical role to play in the
treatment of erythematotelangiectatic rosacea but these treatment modalities are still
largely under researched. There was some evidence that pulsed dye laser and intense
pulsed light therapy are capable of reducing erythema and telangiectasia on the face
(Neuhaus 2009).The effects of laser therapy for rosacea on the nose were investigated
in only one study (Karsai 2008). Because clearance of the redness and telangiectasia
occurring on the rest of the face is highly desirable, can be a source of personal
embarrassment and may lead to low self esteem, further studies of laser and light-based
therapies should be considered a priority (Menezes 2009).
Whitton ME, Pinart M, Batchelor J, Lushey C, Leonardi-Bee J, González U.
Interventions for vitiligo. Cochrane Database of Systematic Reviews 2010, Issue 1.
3.7 Lasers
Excimer laser
The 308 nm excimer laser delivers a condensed beam of UVB light to the skin. The
beam can be targeted but its use is limited to small areas. It is most commonly used in
combination with topical therapies such as tacrolimus (Kawalek 2004), calcipotriol
(Goldinger 2007), or tacalcitol (Lu-Yan 2006).
Helium Neon Laser
HeliumNeon Laser, a gas laser which operates in the red spectrum at 632.8 nm, is a
recent intervention for treating vitiligo, used as monotherapy but also in combination with
tacrolimus, which looks promising, particularly as it is reported to be effective for
segmental vitiligo which can be difficult to treat by conventional methods (Wu 2008).
There are as yet no published RCTs of this intervention.
Jordan R, Cummins CCL, Burls A, Seukeran DDC. Laser resurfacing for facial acne
scars. Cochrane Database of Systematic Reviews 2000, Issue 3
Acne (acne vulgaris) is caused by a combination of excess skin oil, bacteria and other
tissue leading to blockage of the pores. Inflamed spots usually appear on the face,
chest, shoulders or upper arms. Permanent physical scarring may result. Treatment of
scars includes using steroids, chemical and mechanical resurfacing techniques (such as
dermabrasion), or surgery to fill the scarred area with fat, skin or collagen. Laser
resurfacing has the potential to be more precise than other techniques in the treatment
of some facial scars, but is expensive and may have adverse effects. The review found
no trials of laser resurfacing.
There is not enough evidence to show whether laser resurfacing is worthwhile for acne
scars.
Faurschou A, Olesen AB, Leonardi-Bee J, Haedersdal M. Lasers or light sources for
treating port-wine stains. Cochrane Database of Systematic Reviews 2011, Issue 11.
Port-wine stains are birthmarks caused by malformations of blood vessels in the skin.
They manifest themselves in infancy as flat, red marks on the skin and do not disappear
spontaneously but may, if untreated, become darker and thicker by middle age with a
’cobblestone appearance’. Different lasers and light sources are used to lighten the portwine stains by a reduction in redness. However, it is unclear which treatment gives the
best results. Our aim with this systematic review was to assess the benefits and harms
of the various lasers and light sources available. We found 5 randomised controlled
trials, involving 103 participants, which we included in our review. All of the included
trials assessed the effectiveness of the interventions using a within-participant design.
These trials assessed the pulsed dye laser, intense pulsed light, and Nd:YAG laser. Only
the pulsed dye laser was assessed in all five trials.
None of the studies focused on participant satisfaction which was our primary outcome.
Depending upon the setting of the pulsed dye laser, more than 25% lightening (i.e. by
reduction in redness) of port-wine stains occurred. This was after 1 to 3 treatments for
up to 4 to 6 months postoperatively in 50% to 100% of the participants of the trials.
Substantial evidence is lacking for other laser types and intense pulsed light.
Side-effects were rare in the included trials, but 3 trials reported pigmentary alterations in
3% to 24% of the participants, with the highest percentage occurring in Chinese
participants with darker skin types. In one study one participant experienced scarring of
the skin due to a too-high dose of the laser used. Short-term side-effects included pain,
crusting, and blistering in the first two weeks after treatment. Two trials reported no
occurrence of long-term adverse effects, i.e. six months after treatment.
Leonardi-Bee J, Batta K, O’Brien C, Bath-Hextall FJ. Interventions for infantile
haemangiomas (strawberry birthmarks) of the skin. Cochrane Database of
Systematic Reviews 2011, Issue 5.
Infantile haemangiomas are soft, raised swellings on the skin, often with a bright, red
surface. They are a non-cancerous overgrowth of blood vessels in the skin. They are
commonly known as ’strawberry birthmarks’, ’strawberry naevi’, or ’capillary
haemangiomas’. They occur in five per cent of babies, with the majority appearing within
the first few weeks of life, and reach their full size at about three to six months of age.
The vast majority are uncomplicated and will shrink on their own by five to seven years
of age and require no further treatment. However, some infantile haemangiomas may
occur in high-risk areas (such as near the eyes and nose which can result in impairment
to vision and airway obstruction, respectively) and some of them are disfiguring and
psychologically distressing to the children and their parents. Some may also develop
complications so early medical treatment may be necessary. Corticosteroids
are currently the standard treatment; however, it is not known which of a variety of
treatments is best.
Four trials (ranging from 20 to 121 participants) were included in this review. Two
assessed treatments which are no longer used (bleomycin and radiation), with neither
trial finding clinically important improvements. From the other two trials limited evidence
in relation to clinically important improvements were seen.
One trial assessed the use of photodynamic laser (PDL) therapy. Haemangiomas were
more likely to completely clear with PDL when compared to a ’wait and see’ approach at
one year. However, there were significant side-effects, and it was noted that most of the
birthmarks treated with PDL would have resolved naturally over time. One trial compared
an oral corticosteroid (prednisolone) with an intravenous corticosteroid. Haemangiomas
weremore likely to reduce in size using the oral corticosteroid as compared to the
intravenous corticosteroid at three months and one year. Similar numbers of
side-effects were being seen in both groups. We found eight ongoing trials, four of which
were designed to assess the effectiveness of oral propranolol either against placebo or
an oral corticosteroid. Propranolol has become the second-line treatment since the
publication of the protocol of this review in 2007; therefore, it is important that this review
is updated within the next three years so these studies can be assessed and added to
the evidence base to inform clinical practice.
There is limited evidence of the effectiveness of treatments for those birthmarks that
require treatment because the data has come from small trials. The treatments used for
haemangiomas need to be tested in large, well-designed trials.
Non-Cochrane Systematic Reviews
Title: Laser and other light therapies for the treatment of acne vulgaris: systematic
review.
Citation: British Journal of Dermatology, June 2009, vol./is. 160/6(1273-85), 0007Author(s): Hamilton FL, Car J, Lyons C, Car M, Layton A, Majeed A
Abstract: BACKGROUND: Acne is common and can lead to scarring of the skin, as well
as to psychological distress and reduced self-esteem. Most topical or oral treatments for
acne are inconvenient and have side-effects. Laser and other light therapies have been
reported to be convenient, safe and effective in treating acne.OBJECTIVES: To carry out
a systematic review of randomized controlled trials of light and laser therapies for acne
vulgaris.METHODS: We searched the Cochrane Central Register of Controlled Trials,
MEDLINE, EMBASE, CINAHL, PsycInfo, LILACS, ISI Science Citation Index and
Dissertation Abstracts International for relevant published trials.RESULTS: We identified
25 trials (694 patients), 13 of light therapy and 12 of light therapy plus light-activated
topical cream (photodynamic therapy, PDT). Overall, the results from trials of light alone
were disappointing, but the trials of blue light, blue-red light and infrared radiation were
more successful, particularly those using multiple treatments. Red-blue light was more
effective than topical 5% benzoyl peroxide cream in the short term. Most trials of PDT
showed some benefit, which was greater with multiple treatments, and better for
noninflammatory acne lesions. However, the improvements in inflammatory acne lesions
were not better than with topical 1% adapalene gel, and the side-effects of therapy were
unacceptable to many participants.CONCLUSIONS: Some forms of light therapy were of
short-term benefit. Patients may find it easier to comply with these treatments, despite
the initial discomfort, because of their short duration. However, very few trials compared
light therapy with conventional acne treatments, were conducted in patients with severe
acne or examined long-term benefits of treatment.
Title: Evidence-based review of lasers, light sources and photodynamic therapy in
the treatment of acne vulgaris.
Citation: Journal of the European Academy of Dermatology & Venereology, March 2008,
vol./is. 22/3(267-78), 0926-9959;1468-3083 (2008 Mar)
Author(s): Haedersdal M, Togsverd-Bo K, Wulf HC
Abstract: Background There is a considerable need for effective and safe treatment for
acne vulgaris. Objective In a systematic review with an evidence-based approach to
assess the effects of optical treatments for acne vulgaris. Methods Original publications
of controlled clinical trials were identified through searches in PubMed and the Cochrane
Library.
Results A total of 16 randomized controlled trials (RCT) and 3 controlled trials (CT) were
identified, involving a total of 587 patients. Interventions included photodynamic therapy
(PDT; 5 RCTs), infrared lasers (4 RCTs), broad-spectrum light sources (3 RCTs, 1 CT),
pulsed dye lasers (PDL; 2 RCTs, 1 CT), intense pulsed light (IPL; 1 RCTs, 2 CTs), and
potassium titanyl phosphate laser (1 RCT). The randomization method was mentioned in
6 of 16 RCTs, and one trial described adequate allocation concealment. Most trials were
intraindividual trials (12 of 19), which applied blinded response evaluations (12 of 19)
and assessed a short-term efficacy up to 12 weeks after treatment (17 of 19). Based on
the present best available evidence, we conclude that optical treatments possess the
potential to improve inflammatory acne on a short-term basis with the most consistent
outcomes for PDT [up to 68% improvement, aminolevulinic acid (ALA), methylaminolevulinic acid (MAL) and red light]. IPL-assisted PDT seems to be superior to IPL
alone. Only two trials compare optical vs. conventional treatments, and further studies
are needed. Side-effects from optical treatments included pain, erythema, oedema,
crusting, hyperpigmentation, pustular eruptions and were more intense for treatments
combined with ALA or MAL.
Conclusion Evidence from controlled clinical trials indicates a short-term efficacy from
optical treatments for acne vulgaris with the most consistent outcomes for PDT. We
recommend that patients are preoperatively informed of the existing evidence, which
indicates that optical treatments today are not included among first line treatments.
Title: Laser resurfacing of the skin for the improvement of facial acne scarring: a
systematic review of the evidence.
Citation: British Journal of Dermatology, March 2000, vol./is. 142/3(413-23), 0007Author(s): Jordan R, Cummins C, Burls A
Abstract: This review presents and evaluates the evidence of the effectiveness of laser
resurfacing for facial acne scars. Primary studies of all types of design in any language
were identified from MEDLINE, EMBASE, the Cochrane database, Science Citation
Index and various internet sites. Studies were accepted if they included patients treated
by any laser for atrophic or ice-pick acne scars. The quality of the studies was assessed
and data extracted by two independent researchers. There were no controlled trials but
14 case series were found which reported the effects of either the carbon dioxide or
erbium:YAG laser. All of the studies were of poor quality. The types and severity of
scarring were poorly described and there was no standard scale used to measure scar
improvement. There was no reliable or validated measure of patient satisfaction; most
improvement was based on visual clinical judgement, in many cases without blinded
assessment. The inaccurate use of ordinal scales meant that any improvement was
impossible to quantify with any validity, although the evidence suggested that laser
treatment had some efficacy (a range in individual patients of 25-90% for both the
carbon dioxide laser and the erbium:YAG laser). Changes in pigmentation as a sideeffect were common (in up to 44% of patients), although lasting only a few weeks. Laser
resurfacing technology is increasingly used in clinical practice to treat acne scars.
Despite the poor quality evidence, it is plausible that there is some improvement of acne
scarring; there is insufficient information, however, for patients to make informed
decisions on whether to opt for treatment and there is not enough evidence to compare
the two types of laser. There is a particular lack of information about the psychological
effects of acne scar improvement. Good quality randomized controlled trials are needed
with standardized scarring scales and validated patient outcome measures in order to
assess the effectiveness of laser resurfacing in this group of patients.
Literature Reviews
Title: Update dermatologic laser therapy
Journal of the German Society of Dermatology, February 2011, vol./is. 9/2(146-160),
Author(s): Grunewald S., Bodendorf M.O., Simon J.C., Paasch U.
Abstract: New trends in dermatological laser therapy during the last years are based on
new wavelengths, concepts and treatment combinations resulting in a variety of new
dermatologic indications. Fractional laser therapy of chronic actinic damage of the skin
has been introduced and already represents a standard technique. The concept of
fractional non-ablative and ablative laser treatment has been shown to be safe and
effective. Also pigmented and vascular skin changes can be treated by this method.
New, very promising concepts for laser epilation include linear scanned as well as low
fluence laser systems. The first enable very short treatment times for large areas; the
latter are the basis for the growing market of laser epilation devices for home use.
Nevertheless, the potential of low fluence laser devices for long-term hair reduction has
not been tested so far. Furthermore, no data exist on side effects resulting from
repetitive application of laser light to melanocytic lesions. Laser lipolysis has been
introduced as the latest, minimally invasive way of removing small localised fat deposits.
The new procedure may have a great potential for liposculpture; its further development
should be thoughtfully observed. The latest innovations for precise ablation are ultrashort pulsed laser systems. Femtosecond lasers avoid thermal damage at the border
areas of ablation zones. Blackwell Verlag GmbH, Berlin.
Title: Lasers in the treatment of acne scars
Citation: Expert Review of Dermatology, February 2011, vol./is. 6/1(45-60), 1746-9872
Author(s): Choudhary S., McLeod M., Meshkov L., Nouri K.
Abstract: Acne scars occur as one of the complications of acne vulgaris. A number of
therapeutic options are available. Lasers are most useful for grades 2 and 3 acne scars
according to the scale put forth by Goodman and colleagues. Nonablative lasers are
most appropriate for grade 2 scars, while ablative lasers should be used to treat grade 3
acne scars. Fractional lasers have been developed in an effort to improve the efficacy
observed with nonablative lasers, yet reduce the side effects of ablative lasers. Ablative
fractional lasers ablate through the epidermis, while nonablative fractional lasers leave
the epidermis largely untouched, instead targeting the dermo-epidermal junction. More
studies are required to determine the exact placement of fractional lasers in the
clinician's armamentarium. 2011 Expert Reviews Ltd.
Title: Light-based treatments for acne
Citation: Hong Kong Journal of Dermatology and Venereology, December 2009, vol./is.
17/4(190-198), 1814-7453 (Winter 2009)
Author(s): Yeung C.K., Chan H.H.L.
Abstract: Acne is a common skin condition that can lead to significant scarring and
psychological disturbance. The existing oral and topical anti-acne medications are
limited by efficacy, adverse effects and patients' compliance. Lasers or light sources are
explored as therapeutic options for acne. Light treatment targets the function of the
pilosebaceous glands and reduction of Propionibacterium acnes that are pathogenic
factors of acne. Patients whose acne is resistant to conventional treatments or who are
intolerant to their side effects may be candidates for light treatment. Blue light, red light,
pulsed dye laser, mid-infrared laser, intense pulsed light, photodynamic therapy have
been studied in this regard. Long-term efficacy of light-based therapy is still lacking and
careful selection of patients is necessary given its cost and discomfort.
Title: Role of lasers in the treatment of benign pigmented lesions
Citation: Expert Review of Dermatology, October 2007, vol./is. 2/5(663-670), 1746-9872
Author(s): Madan V., August P.J.
Abstract: Benign pigmented lesions are often treated for cosmetic reasons. Several
modalities exist for the treatment of such lesions, with the aim being clearance of the
lesion with acceptable cosmetic results. Cryotherapy and surgical excision of benign
pigmented lesions result in inevitable scarring and the cosmetic end points may not be
achieved. Such therapies may be declined by patients. The availability of lasers has
made it possible to achieve clearance of these lesions with excellent cosmetic results.
Although interest in such lasers has arisen in the past few decades, few studies
comparing the efficacy of lasers and traditional treatment modalities exist.
Randomised Controlled Trial
Title: Ablative fractional laser therapy as treatment for Becker nevus: A
randomized controlled pilot study
Journal of the American Academy of Dermatology, 2011, vol./is. 65/6(1173-1179), 0190Author(s): Meesters A.A., Wind B.S., Kroon M.W., Wolkerstorfer A., Van Der Veen
Abstract: Background: Becker nevus (BN) is an uncommon pigment disorder
characterized by hyperpigmentation and sometimes hypertrichosis. To date, no effective
treatment has been available. Objectives: We sought to assess efficacy and safety of
ablative 10,600-nm fractional laser therapy (FLT) in the treatment of BN. Methods:
Eleven patients with BN, older than 18 years, were included in a prospective randomized
controlled, observer-blinded split-lesion trial. In each patient two similar square test
regions were randomized to either ablative FLT at 10 mJ/microbeam, coverage 35% to
45%, and topical bleaching (to prevent laser-induced postinflammatory
hyperpigmentation), or topical bleaching alone (to allow comparison of the regions). At 3and 6-month follow-up, clearance of hyperpigmentation was assessed by physician
global assessment, reflectance spectroscopy, melanin index, patient global assessment,
patient satisfaction, and histology. Results: At 6-month follow-up, physician global
assessment improved in the FLT region (P <.05). Reflectance spectroscopy, melanin
index, number of melanocytes, and amount of dermal melanin did not significantly differ
between the regions. Patient global assessment and patient satisfaction were 5.0 and
5.9 (visual analog scale score, 0-10), respectively. Side effects were postinflammatory
hyperpigmentation (n = 3), erythema (n = 3), burning sensation (n = 3), crusting (n = 3),
edema (n = 2), and blistering (n = 2). Limitations: Limitations include the small number of
patients, treatment in spring, possibly suboptimal laser settings, and the combined
usage of FLT and a bleaching agent. Conclusion: Ablative FLT was moderately effective
in some patients with BN. However, postinflammatory hyperpigmentation and relatively
negative patient-reported outcomes still preclude ablative FLT from being a standard
therapy. Larger studies with different laser settings will be required to optimize this
treatment modality. 2010 by the American Academy of Dermatology, Inc.
Adverse Events & Complications
Title: Risk management in dermatology: An analysis of data available from several
British-based reporting systems
Citation: British Journal of Dermatology, March 2011, vol./is. 164/3(537-543)
Author(s): Gawkrodger D.J.
Abstract: Background The elimination or reduction of risk is a prime requirement of all
healthcare workers. The matter has come to the fore in dermatological practice recently
with the widespread use of effective drugs that have significant side-effects (e.g.
retinoids, cytotoxic drugs, biologics), the increase in skin surgery, especially for skin
cancer, and the extensive use of phototherapies. Objectives To examine the available
database from different agencies to which adverse events may be reported over at least
a 5-year time frame, categorize the risks, look forward to where as yet unidentified risks
might exist, and draw conclusions to improve the safety of dermatological practice. This
work came about through a request from the National Patient Safety Agency [to the Joint
Specialty Committee of the British Association of Dermatologists (BAD) and Royal
College of Physicians] for information on risks to patients receiving treatment or
investigation for skin disease. Methods Organizations in the U.K. that receive information
about adverse events, whether caused by drugs or procedures in dermatological
treatments, were approached for information about reported events over a 5-year (or, in
one case, 10-year) time frame up to 2009. Data were received from the National Patient
Safety Agency, the Medicines and Healthcare Products Regulatory Agency, the National
Health Service Litigation Authority, the Medical Protection Society and the Medical
Defence Union. In addition, the results of a survey conducted in 2010 by the BAD of its
members concerning potential critical incident reporting were included. The received
information was analysed according to category of event and conclusions drawn about
how best to manage the risks that were identified. Results Adverse events were divided
into the following categories, listed in order of the number of reports received: drug sideeffects (biologics and retinoids), phototherapy dosage, drug monitoring (including initial
screening), pregnancy prevention programmes, skin cancer follow-up (including acting
on reports), dermatopathological reporting and conduct of dermatological surgery
(including management of complications, equipment problems, use of lasers, cosmetic
procedures and cryotherapy). Critical incidents reported by BAD members often
concerned follow-up failures, e.g. of patients receiving systemic drugs or of those with
skin cancer. Conclusions Several of the reported adverse events concern systemic
failures. Recommendations for risk reduction include the following points: better systems
for drug monitoring (including regularity of attendance, provision of sufficient follow-up
appointments, acting on results and adequacy of pregnancy prevention programmes);
staff training and record keeping for phototherapy; acting on skin cancer multidisciplinary
team meeting outcomes (including provision of sufficient follow-up appointments); and
adequate training of staff in dermatological surgery including cryotherapy. Regular
monitoring of the occurrence of such reports is needed to ensure safe practice and to
identify early areas of new risk. 2011
Title: Reported adverse incidents from laser & intense pulsed light use: A laser
protection adviser's view
Citation: Lasers in Medical Science, September 2009, vol./is. 24/5(832), 0268-8921
Author(s): Town G.
Abstract: Introduction: During the past six years, an average of 10 adverse incidents per
annum were reported in writing to me by clients. My current LPA database of 300
organisations uses approximately 350 lasers and/or intense pulsed light devices, mainly
for aesthetic skin treatments. Materials and Methods: Data presented here was
extracted from client LPA records, letters and documents provided by clients reporting
incidents. In the period 2003-2007, the number of LPA establishments registered with
me increased from 60 in the calendar year 2003 to 180 in 2006, 230 in 2007 and 300 in
2008. Results & Discussion: The increase in the number of recorded adverse incident
cases in 2008/9 is explained by a) an exponential growth in affordable cosmetic lasers
and IPL devices, b) a real increase in the number of reported events and c) an
improvement in my own efforts at recording adverse incidents. Analysis of these
reported adverse incidents indicates that operator error is most likely the main reason for
the occurrence of adverse incidents. In my experience, there are five types of adverse
incidents: Unintentional eye exposure to laser beam or IPL leading to retinal or corneal
injury to the eye of the operator or patient; incidents of tissue injury caused by a device
component failure; incidents of tissue injury caused by professional operator error;
incidents of tissue injury resulting from poor client compliance before or after laser/IPL
treatments; Incidents of a technical nature including component failure or incorrect
device calibration or use of incorrect safety equipment, etc. Conclusions: The statutory
obligation to report only serious untoward incidents (death or serious injury) dramatically
reduces the number of incidents that take place. If my recorded data is representative of
the minimum number of actual cases of untoward incidents, then the incidence of skin
injury across England and Wales without the safeguards to patient safety implicit in the
Regulations and National Minimum Standards, would be very much higher.
Title: Complications of laser dermatologic surgery
Citation: Lasers in Surgery and Medicine, January 2006, vol./is. 38/1(1-15), 01968092;1096-9101 (Jan 2006)
Author(s): Willey A., Anderson R.R., Azpiazu J.L., Bakus A.D., Barlow R.J., Dover J.S.,
Abstract: Background and Objective: Innovations in lasers, light and radiofrequency
devices have allowed for improved therapeutic efficacy and safety and the ability to treat
patients with an ever-increasing number of medical and aesthetic indications. Safety
remains a primary concern and the timely communication of complications and their
management is vital to insure that treatments be as safe as possible. The purpose of this
report on the Proceedings of the First International Laser Surgery Morbidity Meeting is to
provide laser experts the opportunity to present and discuss complications that their
patients have experienced and how they were successfully managed. Methods: Laser
experts were invited to present complications of laser, light, and radiofrequency
treatments that their patients have experienced and to discuss the potential mechanisms
leading to the complications their management and final outcomes. Results: Nineteen
unique cases are presented and the clinical management of each case discussed.
Eighteen sets of pre- and post-operative photos are presented. Conclusion: This report
shows that even experts, with extensive experience using light-based therapies, can and
do have patients who develop complications. Sound clinical judgment, and knowing how
to avoid complications and their timely post-operative management, is essential to insure
optimal therapeutic outcome. 2006 Wiley-Liss, Inc.
http://digitalartsph.com/sinpelo/wp-content/uploads/2011/05/Lasers-in-Surgery-and-Medicine-381-15-2006-Complicaciones-Laser.pdf
Guidelines
Vascular lasers and IPLS: guidelines for care from the European Society for Laser
Dermatology (ESLD). J Cosmet Laser Ther. 2007 Jun;9(2):113-24.
Adamic M, Troilius A, Adatto M, Drosner M, Dahmane R.
Dermatology and dermatologic surgery have rapidly evolved during the last two decades
thanks to the numerous technological and scientific acquisitions focused on improved
precision in the diagnosis and treatment of skin alterations. Given the proliferation of
new devices for the treatment of vascular lesions, we have considerably changed our
treatment approach. Lasers and non-coherent intense pulse light sources (IPLS) are
based on the principle of selective photothermolysis and can be used for the treatment
of many vascular skin lesions.
A variety of lasers has recently been developed for the treatment of congenital and
acquired vascular lesions which incorporate these concepts into their design. The list is
a long one and includes pulsed dye (FPDL, APDL) lasers (577 nm, 585 nm and 595
nm), KTP lasers (532 nm), long pulsed alexandrite lasers (755 nm), pulsed diode lasers
(in the range of 800 to 900 nm), long pulsed 1064 Nd:YAG lasers and intense pulsed
light sources (IPLS, also called flash-lights or pulsed light sources). Several vascular
lasers (such as argon, tunable dye, copper vapour, krypton lasers) which were used in
the past are no longer useful as they pose a higher risk of complications such as
dyschromia (hypopigmentation or hyperpigmentation) and scarring. By properly selecting
the wavelength which is maximally absorbed by the target--also called the chromophore
(haemoglobin in the red blood cells within the vessels)--and a corresponding pulse
duration which is shorter than the thermal relaxation time of that target, the target can
be preferentially injured without transferring significant amounts of energy to surrounding
tissues (epidermis and surrounding dermal tissue). Larger structures require more time
for sufficient heat absorption. Therefore, a longer laser-pulse duration has to be used. In
addition, more deeply situated vessels require the use of longer laser wavelengths (in
the infrared range) which can penetrate deeper into the skin.
Although laser and light sources are very popular due to their non-invading nature,
caution should be considered by practitioners and patients to avoid permanent side
effects. These guidelines focus on patient selection and treatment protocol in order to
provide safe and effective treatment. Physicians should always make the indication for
the treatment and are responsible for setting the machine for each individual patient and
each individual treatment. The type of laser or IPLS and their specific parameters must
be adapted to the indication (such as the vessel's characteristics, e.g. diameter, colour
and depth, the Fitzpatrick skin type). Treatments should start on a test patch and a
treatment grid can improve accuracy. Cooling as well as a reduction of the fluence will
prevent adverse effects such as pigment alteration and scar formation. A different
number of repeated treatments should be done to achieve complete results of different
vascular conditions. Sunscreen use before and after treatment will produce and maintain
untanned skin. Individuals with dark skin, and especially tanned patients, are at higher
risk for pigmentary changes and scars after the laser or IPLS treatment.
Example of external IFR policy - NHS North of Tyne IFR Policy, 2011
21 – Resurfacing procedures: Dermabrasion, chemical peels and laser
treatment (OPCS Codes: S60.1, S60.2, S09.-, S10.3, S11.3)
Advice: Evidence (grade D) indicates that resurfacing procedures including
dermabrasion, chemical peels and laser may only be funded in accordance with the
guidance specified below.
Guidance: One course of treatment will be funded for those with post-traumatic scarring
(including post surgical) and severe acne scarring once the active disease is controlled.
21A – Capillary Haemangiomas (Port Wine Stains): Laser treatment of capillary
haemangiomas on the face and neck will be supported. Applications for treatment of
capillary haemangiomas on other parts of the body, will be considered, but will be
considered on a case by case basis by an Individual Funding Request Panel.
Laser is not an appropriate treatment option for cavernous haemangiomas (Strawberry
Naevi) and will not be considered.
21B – Acne Scarring: Consideration will be given to severe facial or neck scarring which
has resulted in significant withdrawal from social, educational or work environments.
One course of treatment only will be funded. Laser is not an effective treatment for
milder forms of post acne scarring or generalised poor skin texture following burnt out
acne.
21C – Telangiectasia: Treatment of benign, acquired lesions such as spider naevi is not
authorised. Treatment of other lesions on the face is considered, if there is evidence of
significant withdrawal from social, educational or work environments. Treatment of facial
telangiectasia following rosacea will be supported, but only after confirmation of the
diagnosis by an experienced dermatologist. Treatment for facial telangiectasia and
vascular complications following other conditions will not be supported.
Safeguarding public health
Device Bulletin
Guidance on the safe use of
lasers, intense light source
systems and LEDs in medical,
surgical, dental and aesthetic
practices
DB2008(03)
April 2008
Contents
1
Introduction........................................................................................................3
1.1
1.2
1.3
2
Nature of hazards ..............................................................................................4
2.1
2.2
2.3
3
Local rules .........................................................................................17
Risk assessment ...............................................................................18
Ophthalmic surveillance ....................................................................20
Reporting adverse incidents ..............................................................20
Safety mechanisms and controlling hazards................................................21
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
5.10
5.11
5.12
5.13
6
Employer responsibilities.....................................................................8
Optical radiation safety policy..............................................................8
Laser Protection Adviser .....................................................................9
Laser Safety Officer...........................................................................11
Laser Protection Supervisor ..............................................................12
Authorised user .................................................................................14
Assisting staff ....................................................................................15
Training..............................................................................................15
Safety administration ......................................................................................17
4.1
4.2
4.3
4.4
5
Effects of exposure..............................................................................4
Dangers to patients and clients ...........................................................5
Dangers to staff ...................................................................................6
Safety management...........................................................................................8
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
4
Document aim .....................................................................................3
Document audience.............................................................................3
New formatting ....................................................................................4
Hierarchy for controlling safety ..........................................................21
Controlled area ..................................................................................22
Maximum permissible exposure ........................................................22
Nominal ocular hazard distance ........................................................23
Blinds and barriers.............................................................................23
Door interlocks...................................................................................24
Warning signs....................................................................................24
Beam hazards and reflections ...........................................................25
Eye protection....................................................................................26
Hand and clothing protection.............................................................29
Surgical fires – causes and prevention..............................................29
Other thermal and operational issues................................................32
Smoke plume issues .........................................................................33
Equipment management .................................................................................36
6.1
6.2
6.3
Equipment management ...................................................................36
Equipment purchasing, loan and demonstration ...............................36
Pre-use equipment checks ................................................................37
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6.4
6.5
6.6
6.7
6.8
7
Optical radiation devices ................................................................................41
7.1
7.2
7.3
7.4
7.5
7.6
7.7
8
Lasers................................................................................................41
Laser delivery systems ......................................................................43
Laser applications..............................................................................45
Intense pulsed light systems .............................................................47
IPL applications .................................................................................48
Light emitting diodes..........................................................................48
LED applications................................................................................49
Optical radiation effects on tissue .................................................................49
8.1
8.2
8.3
8.4
8.5
9
Entry of equipment into service .........................................................37
Quality assurance..............................................................................38
Equipment fault log............................................................................39
Equipment modifications ...................................................................40
Equipment accessories .....................................................................40
Optical radiation.................................................................................49
Photo-thermal effect ..........................................................................50
Photo-mechanical effect ....................................................................50
Photo-chemical effect ........................................................................51
Photo-ablative effect..........................................................................51
Classification of lasers and IPLs....................................................................52
9.1
9.2
Laser classification scheme...............................................................52
IPL classification scheme ..................................................................54
10 Legislation........................................................................................................54
11 Equipment standards ......................................................................................57
11.1
11.2
Overview............................................................................................57
Standards ..........................................................................................57
12 References and bibliography .........................................................................59
References ......................................................................................................59
Further reading................................................................................................62
Appendix A – Example of local rules for the safe use of lasers,
IPL equipment and LEDs ...............................................................64
Appendix B – Example of register of Authorised Users .....................................69
Appendix C – Core of Knowledge syllabus..........................................................70
Appendix D – Reporting adverse incidents .........................................................72
Appendix E – Laser equipment features and terminology .................................76
Appendix F – IPL equipment features and terminology .....................................80
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Accessory purchase issues
• Verify that the accessory is suitable for the specific manufacturer’s make and
model of laser or IPL
• Verify that the product, including accessory is CE marked as a medical device
• Verify that the accessory is suitable for the required procedure
• Ensure that the device has not passed its expiry date.
7
Optical radiation devices
7.1
Lasers
The word ‘laser’ is an acronym for ‘light amplification by stimulated emission of
radiation’. The first working laser, using ruby as the lasing material, was demonstrated
in the early 1960s, when a laser was used for the treatment of retinal detachment.
Lasers concentrate their output over an extremely narrow portion of the spectrum,
which for practical purposes is considered as a single wavelength. The type of active
material determines the wavelength.
7.1.1
Lasing materials
The lasing medium may be solid, semiconductor, liquid or gas. Solid materials may be
crystals, such as ruby or neodymium yttrium aluminium garnet (Nd:YAG); or in the form
of a semiconductor diode, such as gallium arsenide (GaAs). Liquid mediums are
generally organic dyes in a suitable solvent (e.g. rhodamine 6G in methanol). Gases
such as argon, carbon dioxide, rare gas-halide mixtures and also metal vapours may
be employed.
7.1.2 Laser properties
Laser optical radiation has some unique features in addition to that ordinarily
possessed by optical radiation, which enables the beam to be focused to a very small
spot size.
Laser optical radiation is:
Collimated
Most lasers (an exception being semiconductors) emit optical radiation from the
laser aperture as a nearly parallel beam. This low divergence means that the
inherently high irradiance (power per unit area irradiated) of the laser is maintained
over large distances.
Monochromatic
A laser spectrum comprises one or more very narrow lines at characteristic
wavelengths, in contrast to the broad spectrum produced by conventional light
sources; this enables a particular laser wavelength to be chosen to affect certain
body tissues selectively or activate specific types of chemical.
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Spatially coherent
All components of the laser wavefront are exactly in step. This property may be
reduced when laser light is transmitted down an optical fibre and is rapidly lost with
penetration through tissue.
7.1.3 Laser output mechanisms
Continuous wave
The continuous wave (emission) of laser optical radiation is generally produced
when the shutter is opened for as long as the operator depresses the footswitch or
hand-switch, which is typically for a few seconds.
The output from a continuous wave laser is quantified in watts (joules per second).
Pulsed laser
The pulsed laser output is intermittent and generally relates to lasers whose
individual pulses do not exceed 0.25 seconds. They can emit a single pulse, or the
pulses may be grouped together to appear as a single long pulse (pulse train). The
output pulses may range typically from microseconds to milliseconds.
The total energy of each pulse is usually given in joules, or for repeated pulses as
the average power in watts.
Q-switched
Q-switched outputs are very short laser pulses of low energy, but very high peak
power. Q-switching also increases spatial coherence and therefore the quality and
usefulness of the laser emission.
7.1.4
Laser types
Table 1 gives examples of the type of laser generally used in a particular medical
application.
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Table 1: Examples of medical application for a variety of lasers
Laser type
Wavelength
µm
Emission
mode
He-Ne
0.63
0.54
CW
Nd:YAG
1.06
CW
Pulsed
Q switched
Free-running
pulse (FRP)
Ho:YAG
2.1
Er:YAG
2.94
CW
Pulsed
Pulsed
FRP
Associated
beam
transport
Optical fibre
Mirror
Optical fibre
Mirrors
Optical fibre
Mirrors
Waveguide
Mirrors
0.81-0.98
CW
Gated CW
Pulsed
Optical fibre
CO2
10.6
CW
Q switched
Mirrors
Waveguide
Dye
0.4-0.7
Pulsed
Optical fibre
Ruby
0.69
Pulsed
Q switched
Excimer
0.16-0.35
Pulsed
Alexandrite
0.755
Q switched
Optical fibre
Mirror
Optical fibre
Direct
Articulated arm
Optical fibre
KTP
0.532
Q switched
Gated CW
Diode
Optical fibre
Medical application
examples
Aiming beam
Dentistry
Ophthalmology
Dermatology
Gynaecology
Urology
Respiratory
Ophthalmology
Urology
Dermatology
Plastic Surgery
Dentistry
General Surgery
Physiotherapy
Ophthalmology
Dentistry
Gastroenterology
General Surgery
Neurosurgery
Head & Neck
Dentistry
Gynaecology
Dermatology
Urology
Dermatology
Plastic Surgery
Cardiac
Ophthalmology
Dermatology
Gynaecology
Dentistry
Dermatology
Obstectrics
Plastic Surgery
7.2
Laser delivery systems
A laser delivery system comprises a number of components: entrance optics, a beam
guide and target optics.
The choice of delivery system will depend upon the characteristics of the laser and the
medical, surgical, dental or aesthetic application.
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7.2.1
Beam guides
Waveguide
Waveguides fall into two groups – leaky and guide-mode propagating. Both types of
waveguide transmit the laser energy along the bore.
In general waveguides have limited flexibility. They are most often used in handpieces and connected to the articulated arm.
Articulated arm
When the wavelength or peak power does not permit transportation through a
waveguide, the laser beam can be transported using reflecting surfaces of an
articulated arm.
An articulated arm consists of between six and eight mirrors, which are mounted on
rotating holders to provide steering in any direction. The holders are connected to
each other by a set of rigid tubes. If the system is properly aligned, the laser beam
will exit the arm at the same position and angle, independent from the position of the
freely movable tubes; the alignment is very critical.
The articulated arm is the transportation system of choice for Q-switched laser
systems which deliver high peak power pulses.
7.2.2
Beam delivery systems
Focusing and collimated hand-pieces
Focusing hand-pieces are coupled to the laser and are used for precise vaporisation
of skin lesions, such as warts.
Microscope manipulators
A microscope may be connected to the distal end of the articulated arm. A joystick is
used to guide the laser beam along the optical path of the microscope and through
the field of view. The beam is then focused onto the target tissue using optics that
have a focal length that is compatible with the microscope optics. The spot size will
determine the resulting tissue effect. Microscope manipulators may be used in
certain ear, nose and throat surgery, as well as some gynaecological procedures.
Endoscopic applicators
A rigid endoscope may be coupled to an articulated arm. This apparatus is used
when laser tissue vaporisation is needed within body cavities.
Scanning heads
Scanners allow large areas of tissue to be treated from a distance. The tissue is
irradiated more evenly and accurately than can be achieved manually. Treatment
patterns may either be preset or tailored for specialised treatments.
Various scanners have been developed for selective vascular lesion treatments
(e.g. port wine stains).
Diffusers
A diffuser may be attached to the probe. The diffuser is used to spread the laser
light over a large treatment area. The shape of the diffuser will also control the
energy spread to the treatment area.
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7.2.3
Fibre delivery systems
Optical fibres
With some laser applications, the lasing output is not used directly, but is instead
coupled to an optical fibre, which conveys the laser radiation. Optical fibres of
different materials are available; each material will transmit light over different
ranges of wavelength. The scattering and absorption properties will be different for
each different type of optical fibre.
The side firing fibre directs the laser energy at an angle, typically 70º and may be
used in a fluid environment. The side-firing fibre may be used in endoscopic urology
and is compatible with rigid, semi-rigid and flexible endoscopes. The side-firing fibre
is generally compatible with holmium and Nd:YAG wavelength systems.
For some applications, the fibre delivery system may be used in conjunction with a
distal assembly which aids the delivery of laser energy to the target tissue.
Examples may be a simple conduit hand-piece, or more complex flexible, or rigid
endoscopes.
The delivery system may use a particular type of sheath with the fibre, which
delivers irrigation fluids or gas to cool the tip, while simultaneously removing tissue
debris.
Fibre (contact) tips
Optical fibres are often used in conjunction with various shaped contact tips. The
tips have been developed to provide a more controlled application of the light beam
to the target. Commonly, they are made of sapphire glass (or other similar material)
and may be of varying size (e.g. 200-1500 µm diameter). The tips improve the
cutting characteristics of the laser by shaping the beam, delineating a controlled
spot size and minimising beam scatter. The purpose of the fibre tip is to improve
cutting and coagulation processes, control more easily the depth of the cut and
allow tissue contact.
The tips can be damaged if the maximum output through the device is greater than
20 watts. The tips are also susceptible to breakage, especially if too much pressure
is applied to its end.
Contact tips, such as sapphire are commonly used in soft tissue procedures with
Nd:YAG lasers and with Er:YAG lasers in hard tissue procedures.
7.3
Laser applications
Table 2 provides a few examples of typical applications and the type of laser that may
be used.
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Table 2 Examples of clinical applications of lasers
Speciality
Laser type
Application
Nd: YAG
Soft tissue and periodontal surgery, root canal treatment,
desensitisation, analgesia
CO2
Major & minor oral soft tissue and periodontal surgery
Diode
Diagnostics, PAD, tooth bleaching, periodontal surgery,
endodontics
KTP
Tooth bleaching [26], soft tissue, endodontics
Er,Cr:YSGG
Er:YAG
Soft tissue surgery, tooth cavity preparation, bone
surgery
Dye
Port wine stain [27]
Alexandrite
Hair reduction
Ruby
Tattoo removal
Diode
Hair reduction
Nd:YAG
Leg veins, vascular lesions
CO2
Ablation of skin / mucosa lesions, skin resurfacing, plastic
surgical procedures
CO2
Laryngeal papillomata, laryngology, webs, dysplasia,
carcinoma-in-situ, vocal cord nodules, pharyngeal
diverticula
Ho:YAG
Endo-nasal surgery, tonsillectomy
Nd:YAG
Tumour ablation.
Bleeding from GI tract
CO2
Soft surgery
GaAs
Laparoscopic surgery
Ho/ Nd:YAG
Endoscopic surgery, laparoscopic surgery
Nd:YAG
Endometrial ablation for menorrhagia
CO2
Cervical, vaginal and vulvar pre-cancer
KTP
Laparoscopic, hysteroscopic surgery
Interstitial
Nd:YAG
Liver and breast cancer
Neurosurgery
(see also PDT)
CO2
Neuraxis neoplasia
Argon
Diabetic retinopathy, other retinal vascular abnormalities
Nd:YAG
Posterior lens capsulotomy
Excimer
Photorefractive keratectomy [28, 29]
Orthopaedics
Ho:YAG
Lateral retinacula release, osteoarthritic lesion removal,
contouring and sculpting of articular surfaces
PDT (photodynamic
therapy)
Dye
Bladder, GI tract, respiratory tract and other body site
cancers
Physiotherapy
GaA/As
Wound healing, pain control [30] small joint inflammation
[31, 32, 33], adhesive capsulitis [34], arthritis [35, 36]
Respiratory
Nd:YAG
Intraluminal lesions
CO2
Ablative re-surfacing
Dye
Lithotripsy
Ho:YAG
Urinary stones, prostatic hyperplasia, bladder tumours
Ho / Nd:YAG
Bladder, urethral and kidney stones
Dentistry
Dermatology
ENT
Otorhinolaryngolog
y
Gastroenterology
(see also PDT)
General surgery
(see also PDT,
interstitial)
Gynaecology
Ophthalmology
Urology
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7.4
Intense pulsed light systems
Intense pulsed light (IPL) systems have been in use since the late 1990s. These
systems are also marketed by some manufacturers as intense light source (ILS), or
intense continuous light system (ICL system). Manufacturers may also describe the
device as a light based or heat based system. All these types of devices are used
similarly and have the same hazards associated with them.
Intense pulsed light and other forms of intense light source devices are used in
conjunction with application based filters and will have similar effects on the skin as
lasers. The devices are generally used in the cosmetic sector for aesthetic purposes,
such as hair reduction. In recent years, the technology has been developed to include
other procedures, including skin treatments such as photo-rejuvenation.
A recent development is the combination IPL-laser system. The combination system is
a single device; it allows the user to ‘switch’ from the IPL system to the laser. The
output may be from a single hand-piece, or from a number of hand-pieces on the same
piece of equipment. These types of system are more commonly used in clinics that
offer cosmetic type procedures.
The effects of optical radiation on tissue are discussed in section 8.
7.4.1
IPL properties
The intense pulsed light system utilises technology that is different from that used in
lasers. Xenon or krypton gas may be used as the filling for the quartz tube which forms
the flash-lamp. IPL systems emit a broad spectrum of non-coherent light (400 nm to
1400 nm), which is filtered into wavelengths that are appropriate to the procedure being
undertaken.
Filtering is achieved by a number of mechanisms:
• Water path filtering. The flash-lamps may be water-cooled, or a water based gel
may be used, which will remove the majority of infra-red light.
• Dichroic filtering. Mirrors which are termed as being either ‘hot’ or ‘cold’ reflect
unwanted wavelengths to a heat sink.
• Longpass glass filtering. Coloured glass filters may be employed for
wavelength selection.
7.4.2
IPL delivery mechanisms
Typically the components of the IPL system will comprise a main unit and a handpiece. The main unit has a control computer, a pulse-generating network and an
ancillary cooling system. The hand-piece comprises a flash-lamp, filter and a lens or
waveguide. The filtered light is delivered to the skin via the hand-piece. Other beam
delivery systems may be used with IPL systems, including optical fibres,
micromanipulators and scanners.
Some method of skin cooling should be employed during IPL procedures to protect the
patient’s skin from heat damage and aid patient comfort during the procedure. A gel
may be applied to the skin creating a cold layer through which the light pulses pass.
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Cooling mechanisms are also integrated into some IPL systems. Some of the more
typical methods employed are:
• Forced air cooling uses high-flow, sub-zero (°C) air to the treatment area.
• Cryogen cooling utilises a refrigerated spray that is applied before, during, and
after each light pulse.
7.5
IPL applications
The following table provides a number of examples of IPL applications.
Table 3 Examples of clinical and aesthetic applications of IPL systems
7.6
Speciality
Application
Aesthetic
Spider veins, sunspots, broken capillaries
Dermatology
Hair reduction, wrinkles, inflammatory acne [37]
Physiotherapy
Acute and chronic musculoskeletal aches and pains
Light emitting diodes
Light emitting diodes (LEDs) are semiconductor devices that emit in general incoherent
light over a range of wavelengths, typically from 260 nm to 2100 nm. LEDs are often
used in conjunction with optical fibres.
Since the latter part of the 1990s LEDs have provided medicine with a useful tool.
Small LEDs can be placed anywhere in the body thus delivering light deep into tissues.
The wavelengths have been biologically optimised in photodynamic therapy (PDT) for
the treatment of cancer, wound healing and in a number of physiotherapy applications.
LEDs are also used as the light source in the treatment of seasonal affective disorder
(SAD).
LEDs have some advantages over lasers and IPL light sources:
• small in size
• low power consumption
• a negligible heat output.
Broad-band exposure limits for LEDs have been recommended by the International
Commission on Non-Ionising Radiation (ICNIRP) and device emission limits for
different risk groups have been published by the International Commission on
Illumination (CIE).
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7.7
LED applications
The following table provides a number of examples of LED applications.
Table 4 Examples of clinical applications for LEDs
Speciality
Application
Aesthetic
Spider veins, sunspots, broken capillaries
Dentistry
Dental composite curing [38]
PDT
Cancer treatment [39]
Physiotherapy
Wound healing [40]
8
Optical radiation effects on tissue
8.1
Optical radiation
Electromagnetic radiation may be defined as a form of energy that can propagate
(radiate) through space. It is characterised by wavelength and extends from X-rays
(short wavelengths) to radio (long wavelengths). Optical radiation has intermediate
wavelength ranges. The optical spectrum is defined as electromagnetic radiation in the
wavelength range 100nm to 1mm.
The optical radiation spectrum is divided into ultraviolet, visible and infra-red radiations.
The ultraviolet (UV) and infra-red (IR) regions are subdivided into A, B, C (i.e UV-A, IRA etc).
10-4nm
Gamma
rays
100nm
X-rays
1mm
Optical
Radiation
100nm 400nm
Ultraviolet
Microwave
700nm
Visible
1m
Radio
1mm
Infra-red
Figure 1: The electromagnetic radiation spectrum
The mechanisms by which optical radiation induces damage are similar for all
biological systems and may involve thermal, mechanical, chemical and ablative
processes.
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The location and absorption of laser optical radiation in tissue, especially in the eye is
strongly dependent on the wavelength.
8.2
Photo-thermal effect
The depth of penetration and absorption of optical radiation will depend primarily on its
wavelength. Tissue damage from thermal effects is also related to the duration of the
optical radiation exposure and the temperature reached in the tissue. If the optical
radiation exposure to the tissue is for a short duration (less than 1 second) the tissue
will suffer a lesser degree of damage, than if a longer exposure time is used.
For most surgical continuous wave (CW) lasers, damage is due to the heating of the
absorbing tissue. If the duration is short and the tissue temperature is below 42 ºC then
little or no permanent damage will occur. If this condition is exceeded, coagulation
occurs. The proteins start to denature, which is evidenced by a whitening of tissue.
Further heating above 100 ºC will cause evaporation of water and associated
vaporisation of tissue. Continued irradiation heats the debris until the tissue blackens
and carbonises at about 350 ºC. At temperatures above approximately 500 ºC
carbonised tissue will burn.
Photocoagulation employs continuous wave laser light applied to absorbing material
targets with effects mediated by primary and secondary effects of thermal damage.
This technique is most widely used in the eye to treat retinal diseases e.g. diabetic
retinopathy and macular degeneration.
Optical radiation exposure to the eye, especially focused on the retina, will cause local
heating and can cause damage to both the pigment epithelium and the adjacent lightsensitive rods and cones; such damage can result in temporary or permanent loss of
sight.
Intense pulsed light systems remove unwanted hair based on the principle of selective
photo-thermal effect. The filtered light causes thermal injury to the hair follicle. The light
penetrates the skin and is absorbed in the target pigment (melanin) found in the hair
shaft. The energy absorbed in the shaft causes the temperature to reach a sufficiently
high level in the hair follicle so that the targeted hair structures are destroyed and hair
re-growth is inhibited.
8.3
Photo-mechanical effect
Photo-mechanical effects may occur when the tissue is exposed to pulses of radiation
that last for a few nanoseconds. The tissue is heated up very quickly, which causes
thermal expansion of the tissue and thermo-acoustic shock waves, which propagate
through the tissue. This process is generally referred to as photo-disruption; it is used
for removing fibrous tissue growths which may form in the eye following cataract
surgery.
Thermo-acoustic shock waves are also produced by high power pulsed systems which
may not be of sufficient intensity to create a plasma but may nevertheless cause very
rapid heating. An example of this is seen with the use of erbium lasers in tooth cavity
preparation, where interstitial water is rapidly vaporised causing explosive dislocation
of enamel and dentine mineral components.
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8.4
Photo-chemical effect
The cornea and the lens can be injured through ultraviolet radiation photo-chemical
effects. The retina is particularly sensitive to damage from blue light. This sensitivity is
the result of a photo-chemical reaction within pigments contained in the eye.
The occurrence of a photo-chemically induced injury depends on the number of
absorbed photons per unit area on the tissue surface. It does not normally depend on
the time taken to deliver the photons. A short exposure time to a high level of optical
radiation will have the same effect as a long exposure period with a correspondingly
reduced level of optical radiation. Photo-chemical damage has a cumulative effect.
However, the use of photo-chemical effects with tissue is used for positive benefits in
medicine. An example of this in photodynamic therapy, where light therapy is used in
combination with a photoactive drug.
8.5
Photo-ablative effect
Photo-ablation takes place when short duration laser pulses are focused onto a small
area, rapid heating follows and results in the vaporisation of tissue and bone. Effective
photo-ablation and precise depth control can be achieved by selecting the appropriate
laser wavelength in a region where the absorbance of the tissue or bone to be treated
is very high.
In excimer photo-ablation, strongly absorbing ultraviolet optical radiation is used to
vaporize superficial tissues. It is primarily for surface etching, reshaping and refractive
surgical applications in the cornea.
Tissue may be ablated by the beam from an excimer laser, which emits short
wavelength ultraviolet optical radiation that breaks molecular bonds directly. The effect
is to remove a localised volume, precisely defined by the physical extent of the beam.
The mid-infrared wavelength of an erbium laser may be used for bone ablation. An
erbium laser coupled to a sapphire-tipped fibre may be used in photo-ablation
orthopaedic surgery applications and dental and oral surgical applications.
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9
Classification of lasers and IPLs
9.1
Laser classification scheme
In 2001, the Safety of Laser Products standard was revised.The revision to the laser
classification system has resulted in the introduction of three new laser classifications –
1M, 2M and 3R – and the abolition of Class 3A.
The 2001 revised standard included a letter appended to a number of the laser
classifications. The laser classification scheme only deals with the laser beam hazard.
The letter ‘M’ in Class 1M and Class 2M is derived from ‘magnifying’: optical viewing
instruments.
The letter ‘R’ in Class 3R, is derived from ‘reduced’ or ‘relaxed’ requirements. The ‘R’
requirement relates to certain equipment and user specifics e.g. manufacturer: no key
switch and interlock connector required; user: no eye protection is usually required.
The letter ‘B’ in Class 3B is historical.
It should be noted that in the previous laser classification scheme, lasers were grouped
into four main classes and two sub-classes (i.e. 1, 2, 3A, 3B and 4); these
classifications will still apply to older lasers that are currently in use.
The 2001 edition has been revised as BS EN 60825-1:2007 Safety of laser products.
Equipment classification and requirements [13].
The laser classification is determined by the equipment manufacturer. The
manufacturer follows the specification laid out in the standard BS EN 60825-1:2007
[13]; details of the laser safety classes are given in Table 5. Additional equipment
requirements are detailed in BS EN 60601-2-22 Medical electrical equipment.
Particular requirements for safety. Specification for diagnostic and therapeutic laser
equipment [41].
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Table 5 Laser safety classes
Laser safety
class
Laser type
Potential eye or skin hazard
Laser completely
enclosed
Generally safe during use. Hazards
according to power of enclosed laser when
interlocks are overridden.
Class 1
Very low power
level
Emitted power generally safe for long-term
intrabeam viewing, even with optical
instruments such as magnifying glasses.
Class 1M
Low power level.
Collimated large
beam diameter or
divergent
Safe for long-term intrabeam viewing, but
potentially hazardous with magnifyers
(divergent beams) or binoculars (large
diameter collimated beams).
Low power level
Safe for brief (accidental) direct exposure
with naked eye and optical instruments.
Prolonged staring may injure eye, especially
blue wavelengths.
Class 1
(embedded)
Class 2
Visible wavelengths
only
Low power visible
Class 2M
Class 3R
(visible)
Class 3R
(non-visible)
Class 3B
Class 4
Collimated large
beam diameter or
divergent
Low power
Typically alignment
lasers
Safe for brief exposure with the naked eye,
but potentially hazardous when exposure
occurs with magnifiers (divergent beams) or
binoculars (large diameter collimated
beams).
Accidental exposure usually not hazardous,
but eye injury possible for intentional
intrabeam viewing
Low power
Accidental exposure usually not hazardous,
but eye injury possible for intentional
intrabeam viewing.
Medium power
Exposure (including brief accidental
exposure) of the eye to the direct beam may
cause serious eye injuries. Very limited skin
hazard. Viewing of diffuse reflections are
normally safe.
High power
Exposure (including brief accidental
exposure) of the eye to the direct beam and
close viewing of diffuse reflections may lead
to serious eye injuries. May cause serious
skin hazard. Presents fire hazard.
The manufacturer is required to implement all appropriate safety and engineering
controls that are applicable to each class of laser; for example, with Class 3B and
Class 4 lasers, remote interlocks, a key switch, a beam stop and an emission warning
will be required.
Any laser equipment of a given class may contain an embedded laser, which is greater
than the class assigned to the device. In these cases safety and engineering controls
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are required to ensure that access to the optical radiation in excess of the device class
is not possible.
Labelling on laser equipment is required for all classifications of device.
9.2
IPL classification scheme
The standard IEC 62471 Photobiological safety of lamps and lamp systems [42]
provides details of lamp classification, which include IPL systems.
The lamp classification scheme indicates only the potential risk. Depending upon the
use factors, time of exposure and luminaire effects these potential hazards may or may
not become actual hazards.
The pulsed lamp criteria, including IPL, apply to a single pulse and to any group of
pulses within 0.25 seconds. The hazard values are at a distance of 200 mm.
The risk group determination of the lamp being tested is detailed in the standard.
10
Legislation
There is no single item of UK legislation that deals with the use of non-ionising
radiation devices in the work place. General health and safety legislation applies as
well as certain other regulations that cover non-ionising (optical) radiation equipment
use. There is specific legislation which controls aspects of Class 3B and 4 medical
lasers usage in private healthcare.
The legislation given below is not an exhaustive list of requirements. The employer
will have to consider their legal responsibilities in more detail before they proceed.
Artificial Optical Radiation Directive [11]
This directive is otherwise known as the Physical Agents Directive (Artificial Optical
Radiation). It has to be implemented by 27 April 2010. It will include all optical radiation
devices, including lasers and intense pulsed light systems, LEDs and other diagnostic
and therapeutic light sources used in medical, surgical, dental or aesthetic practices.
Care Standards Act 2000 [8]
This act, and equivalent devolved administration legislation, covers all aspects of
healthcare and social care, including the private and voluntary sectors. It includes
definitions of independent hospitals and clinics.
In England, the Healthcare Commission is responsible for the enforcement of the Care
Standards Act 2000. In Wales, the Healthcare Inspectorate Wales regulates under the
Care Standards Act 2000. In Scotland, the Care Commission regulates under the
Regulation of Care Scotland Act 2001. In Northern Ireland, regulation is encompassed
under The Health and Personal Social Services (Quality, Improvement and Regulation)
(Northern Ireland) Order 2003.
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