Prevalence of Refractive Errors in Primary
School Children in a Rural Community in
Ebonyi State of Nigeria
Year : 2013 | Volume : 18 | No : 3 | Page : 017-034
Date of Web Publication
09-June-2015
Abstract
Background: Globally, refractive error is a common cause of visual impairment in the paediatric
age group. However, no previous vision screening study among primary schools children has been
reported in Ebonyi State, South-Eastern Nigeria. This study aimed to screen primary school children
in two rural primary schools in Nchokko Community of Igbeagu Izzi, Ebonyi State for refractive
errors
Subjects and Methods
This was point prevalence, cross- sectional study of all primary school children in the two primary
schools at Nchokko community of Igbeagu village of Izzi local government area of Ebonyi State. The
study population consists of all pupils present during the school eye health visit to this community on
the 6th of March 2012.
Results
There was a total of 213 pupils comprising of 107 males and 106 females (Ratio, 1:1) ages ranged
from 5-15 years with a mean age of 9.6 ± 2.7 years. Refractive error was found in 2 patients (0.9%).
Conclussion
The Prevalence of Refractive Error in the two rural primary schools at Nchokko community of
Igbeagu village of Izzi Local Government Area of EbonyiState.was 0.9%.
Key words: Nigeria, Refractive error, Rural, school children
Introduction
Globally, visual impairment due to uncorrected refractive error is a significant cause of poor vision
in children.1-2 It is estimated that 12.8 million children aged 5 – 15 years are visually impaired due to
uncorrected refractive error. 3 Uncorrected refractive error (RE) remains a public health problem
among different population groups, thereby warranting its recognition as a priority area for
intervention by the Vision 2020- The Right to Sight4. Uncorrected RE is one of the leading cause of
low vision and the second cause of blindness.3 In children, the uncorrected refractive error can
hinder education, as optimal vision is needed for proficiency in learning.5 Refractive Error Study in
Children (RESC) from Chile, 6 China 7 and Nepal 8 documented that refractive error (RE) was
responsible for 56.3%, 89.5% and 56% of reduced vision respectively.
Along with cataract, trachoma, onchocerciasis and vitamin A deficiency, refractive errors have been
listed, among eye problems whose prevention and cure should provide enormous savings and
facilitate socio-economic developments. 9Children who are visually impaired must overcome a
lifetime of emotional, social and economic difficulties, which also affect the family and society.10 Loss
of vision in children influences their education, employment and social activities.10 Vision has an
essential role in a child’s development, and a visual deficit is a risk factor not only for altered visiosensory development, but also for overall socioeconomic status throughout life11. In most instances,
children do not complain of their visual difficulties by themselves. Timely screening for the early
detection of eye and vision problems in children is vital to avoid lifelong visual impairment. Early
detection provides the best opportunity for effective treatment10.
The benefit of regular eye screening in children that includes a comprehensive eye examination has
been recognized worldwide, including in developed economies12. Early corrective measures for
deficits detected would greatly assist in reducing childhood blindness and related morbidity.
School-age children (6-15 years) represent 20–30% of the total population in most low and medium
income countries(LMICs)13. For Nigeria, this translates to 20–30 million children. In some states in
Southern Nigeria, 80% of children attend school and can, therefore, be reached by healthcare
programs14. Therefore, school children are an important, large target group for early detection of
eye diseases and prevention of blindness.15
Vision screening involves searching for unrecognized eye disease or defect using rapidly applied
tests, examinations or other procedures for apparently healthy individuals. 13,16 A screening test is
not intended to be a diagnostic test; it is only an initial examination. Those who are found to have
ocular problems are referred to an ophthalmologist for further diagnostic work-up and treatment.
In this study, vision screening was carried out in all the pupils in the only two rural primary schools,
with a view to determining the burden of refractive errors among this rural paediatric population.
This study will provide data to government educational and health policy makers for planning and
implementing an effective school Eye Health Programme for the state.
Methods
This was a point prevalence, cross- sectional study of all school children present in the two primary
schools at Nchokko community of Igbeagu village of Izzi local government area of Ebonyi State at
the time of study.
Context
Izzi Local Government Area has its headquarters at Iboko. It has a total population of 261, 410[9].
There are 25 communities in Izzi LGA. Igbagu Development Centre is one of the newly created
development centres in Izzi LGA. It is about 20 kilometers from Abakaliki, the state capital. Four out
of the 25 communities in Izzi LGA make up the development centre. All the four communities serve
as the catchment area for the Primary Health Care Centre of Ebonyi State University Teaching
Hospital, now known as Federal Teaching Hospital Abakaliki (FETHA). Nchokko community, which
is the location of this study, is one of the communities in Igbeagu Development Centre of Izzi Local
Government Area of Ebonyi State.
The Department of Community Medicine of the Ebonyi State University/Federal Teaching Hospital,
has the development centre as its Primary Health Care (PHC) Practice Area.This is used for the
training of medical students and resident doctors in primary health care and also provision of
preventive and curative clinical services.
The Department of Ophthalmology also uses that primary health care centre for its community
ophthalmology programmes.
Study Population
The study population consists of all pupils present during the school eye health visit to the only two
primary schools of the community on the 6th of March 2012.
Permission to carry out the study
This school eye health visit was arranged by the Department of Community Medicine of Ebonyi State
University (EBSU) as part of their Rural Health Exposure for Medical Students. The department of
ophthalmology of EBSU was invited to conduct the eye screening part of the program. Permission to
carry out the study was sought for and obtained from, the Faculty of Clinical Medicine and the
University management, who also provided some of the logistics such as transport.
Each participating community /school was visited two weeks before the screening day, and
permission to do the study sought and obtained from the community leaders and Head teachers.
Procedure
Outdoor visual acuity assessment for each eye was done by an ophthalmic assistant for all the school
children who were present during the screening. This was done using the standard Snellen eye-test
chart placed at 6 metres. Visual acuity level is taken at the line of complete identification of the line
alphabets. Those with visual acuity of 6/9 or less were presented with a pinhole and the test
repeated. Improvement of visual acuity with pinhole was considered as a refractive error. External
eye examination was performed using a pen torch and a simple magnifying head loupe. Posterior
segment studies were also done for each pupil using a direct ophthalmoscope in required cases.
Those who needed further evaluation and/or treatment were referred to the teaching hospital of the
University.
Data Analysis
Data were entered into, cleaned and analyzed using the Statistical Package for Social Sciences
(SPSS), version 18 (SPSS Inc, Chicago, Illinois, USA), and reported as frequency distributions,
percentages and means ± standard deviation.
Ethics Approval
Ethical approval consistent with the tenets of 1964 Helsinki Declaration on research involving
human subjects was obtained from Ebonyi State University’s Medical and Health Research Ethics
Committee (Institutional Review Board). The study was adequately explained, and the refusal of
participation by parents, teachers or children was respected.
Results
There was a total of 213 pupils; ages ranged from 5-15 years with a mean age of 9.6 ± 2.7 years.
There were 107 males and 106 females (Male to female ratio of 1:1). Refractive error was found in 2
pupils (0.9%). See tables 1 and 2.
Discussion
Vision screening and refractive services for school children have been recommended by WHO as a
useful strategy for prevention of avoidable childhood blindness. 17 Since most children with
uncorrected refractive error are asymptomatic, screening helps in early diagnosis and timely
interventions.Thereforethis strategy has been found to be a very useful measure
18
The prevalence of refractive error varies widely in children from 50% in Singapore, 36.7% in Hong
Kon,19 14.8% in Malaysia,20 12.8% in China,21 11.6% in Uganda22to less than 1% in Tanzania.23In
Malaysia20 the study population comprised 70.3% Malay, 16.5% Chinese, 8.9% Indian and 4.3% other
ethnicity. The prevalence of uncorrected, presenting and best corrected visual acuity (BCVA) of
20/40 or worse in at least one eye was 17.1%, 10.1% and 1.4% respectively. Among the eyes with
reduced vision, refractive error was the cause in 87.0%, amblyopia in 2.0%, other causes in 0.6%
and unexplained causes in 10.4%. Over half of the children that needed corrective spectacles did not
have them.
The prevalence of refractive errors found in this study was low (0.9%). Similar studies have
confirmed low prevalence of refractive errors in rural schools. Chuka-Okosa in a study of refractive
errors in rural school children in Nkanu West LGA of Enugu State, South-Eastern Nigeria, reported
a prevalence of 1.97%.24 Ajaiyeoba et al in another rural community in South Western Nigeria
observed a refractive error prevalence of 0.87%.25 In Yenegoa local government Area of South-south
Nigeria, Opubiri et al. reported a prevalence rate of 2.2 %.26 In a study by Okoye et al. at a rural
primary school, Anambra state Nigeria, the prevalence of refractive error was found to be 0.7%.27
Relatively higher prevalence values have been reported from studies done in some cosmopolitan
cities of Nigeria. Nkanga13 in Enugu Nigeria reported a prevalence rate of 7.4% and Faderin28 in
Lagos reported a prevalence rate of 7.3%. These studies suggest that schools in urban centres have
a higher prevalence of refractive errors than schools in rural areas. This is corroborated by Padhye
et al29 in Maharastra, India, who did a comparative study of refractive error prevalence rates in
urban and rural schools. In that study the prevalence in urban schools was higher than that in rural
schools.
The higher prevalence in cosmopolitan cities may be related to the mixed socio-economic population
of a variable combination of low-, middle- and high income cadre population in such cities. An
Australian study30 had suggested the influence of environmental factors such apartment stylehousing and higher population density as a reason for the difference in prevalence of refractive error
between rural and urban children.
Vision screening in schools is a cost-effective preventive strategy for childhood blindness. This is
because the refractive error is a treatable cause of visual impairment, in most cases by mere
spectacles. 22 Moreover, it mostly sets in at a younger age than other major causes of visual
impairment and is responsible for a much larger number of blind years lived by a person than most
other causes if left uncorrected.
Although the burden of refractive errors may be lower in rural schools, the reduced availability of
access to eye care services in such schools makes it as important as in urban cities to have regular
vision screening programmes for these schools. This testing should involve visual acuity
measurement and an eye examination by trained eye care personnel, public eye health education
and training of teachers to carry out simple vision screening. The effectiveness of such a vision
screening project has been reported in Maharashtra, India.In this case,the staff of community
ophthalmology unit of an eye centre regularly embark on annual screening for school children both
in urban and rural areas in their catchment area.29During this programme, the children at remote
rural schools are examined in mobile eye units while the school teachers trained in vision screening
examine students of urban schools. The aim is to identify children with a refractive error as early as
possible and to offer them spectacles while those with other causes of reduced vision are referred to
secondary and tertiary eye care facilities for appropriate treatment.
It has been suggested that vision screening be routinely done at school entry, midway through
school and at the completion of primary education to enhance early detection and treatment of eye
diseases.26. This can be achieved if school eye health programmes become incorporated into primary
health care as done in immunization programmes. Government and Non-governmental organizations
can sponsor school eye health programmes much the same way that vaccination programmes are
sponsored.
Limitations
Its school-based nature limits the extrapolation of the conclusions drawn from this study since a
significant number of school aged children may not be in school due to poverty. Also, retinoscopy of
the children would have helped to characterize the refractive errors. A large sample size,
community-based design setting with retinoscopy is suggested.
Conclusion
This study found a prevalence of 0.9% of refractive error among the rural primary school children in
Nchokko community of Igbeagu village of Izzi local government area of Ebonyi State. Nigeria. It is
recommended that implementing regular vision screening of primary school children as part of
primary eye care should be given priority. Also eye screening (at least visual acuity testing) should
be done in schools routinely at school entry, midway through school and at the completion of
primary education. This will help to identify those with a refractive error with prompt refractive
correction offered to prevent life-long visual impairment from amblyopia and also to facilitate
optimal learning ability.
Acknowledgement
We acknowledge the assistance of the medical students who collected the data during their rural
posting experience in community medicine. We also recognize the support and cooperation of the
two schools in Nchokko village whose pupils were studied. We also recognize the help of the
Nchokko community development association as well as the village head for their cooperation during
this study. Finally, we thank the Vice Chancellor of Ebonyi State University, Prof Francis I. Idike for
creating the enabling environment that enabled the rural posting experience of the fifth year
medical students to take place without which this study may not have been possible.
Disclosure
The authors declare that we have no financial or personal relationships that may have
inappropriately influenced us in writing this article.
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Table 1: Age-Sex Distribution of the pupils (n=213)
Age Group
Sex
Total(%)
Male
Female
5-8
37
43
80(37.6)
9-12
57
46
103(48.3)
13-15
13
17
30(14.1)
Total
107
106
213(100)
Table 2: Demographic distribution of refractive errors among the pupils (n=213)
Age Group
5-8
Sex
Male
Female
1
9-12
Total(%)
1(0.47)
1
1(0.47)
1
2(0.94)
13-15
Total
1