Prevalence of eye diseases in primary school children in a rural area of Tanzania

Screening for refractive error among primary school children in Bayelsa State, Nigeria

INTRODUCTION

BACKGROUND

Vision screening study in primary school children has not been done in Bayelsa State. This study aims to screen for refractive error among primary school children in Bayelsa State and use the data to plan for school Eye Health Program.

METHODS

A cross sectional study on screening for refractive error in school children was carried out in Yenagoa Local Government Area of Bayelsa State in June 2009. A multistage sampling technique was used to select the study population (pupils aged between 5-15 years). Visual acuity (VA) for each eye, was assessed outside the classroom at a distance of 6 meters. Those with VA ≤6/9 were presented with a pinhole and the test repeated. Funduscopy was done inside a poorly lit classroom. An improvement of the VA with pinhole was considered refractive error. Data was analyzed with EPI INFO version 6.

RESULTS

A total of 1,242 school children consisting of 658 females and 584 males were examined. About 97.7% of pupils had normal VA (VA of 6/6) while 56 eyes had VAs ≤ 6/9. Of these 56 eyes, the visual acuity in 49 eyes (87.5%) improved with pinhole. Twenty seven pupils had refractive error, giving a prevalence of 2.2%. Refractive error involved both eyes in 22 pupils (81.5%) and the 8-10 years age range had the highest proportion (40.7%) of cases of refractive error followed by the 9-13 year-old age range (37%).

CONCLUSION

The prevalence of refractive error was 2.2% and most eyes (97.7%) had normal vision.

Screening of primary school children for refractive error in South-South Nigeria

BACKGROUND

Vision screening study in primary school children has not been done in Bayelsa State, South-South Nigeria. This study was therefore conducted to screen primary school children for refractive error in Bayelsa State and use the data to plan for an effective school Eye Health Program.

METHODS

A cross sectional study on screening for refractive error in school children was carried out in Yenagoa Local Government Area of Bayelsa State in June 2009. A multistage sampling technique was used to select the study population (pupils aged 5-15 years). Visual acuity for each eye was assessed by an Ophthalmic nurse and Optometrist outside the classroom, at 6 meters distance. 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 refractive error. Funduscopy was done inside a poorly lit classroom. Data was analyzed with EPI INFO version 6.

RESULTS

A total of 1,242 (658 females and 584 males) Pupils were examined. About 97.7% of eyes had normal vision of 6/6 while 49 out of 56 eyes, with visual acuity of 6/9 or less, improved with pinhole. Twenty seven pupils had refractive error, giving a prevalence of 2.2%. Refractive error involved both eyes in 22 pupils (81.5%) with the 8-10 years age range having the highest proportion (40.7%) of cases followed by 11-13 years age range (37.0%).

CONCLUSION

The prevalence of refractive error in school children in Bayelsa State, South-South Nigeria was low.

School-based approaches to the correction of refractive error in children

The World Health Organization estimates that 13 million children aged 5-15 years worldwide are visually impaired from uncorrected refractive error. School vision screening programs can identify and treat or refer children with refractive error. We concentrate on the findings of various screening studies and attempt to identify key factors in the success and sustainability of such programs in the developing world. We reviewed original and review articles describing children's vision and refractive error screening programs published in English and listed in PubMed, Medline OVID, Google Scholar, and Oxford University Electronic Resources databases. Data were abstracted on study objective, design, setting, participants, and outcomes, including accuracy of screening, quality of refractive services, barriers to uptake, impact on quality of life, and cost-effectiveness of programs. Inadequately corrected refractive error is an important global cause of visual impairment in childhood. School-based vision screening carried out by teachers and other ancillary personnel may be an effective means of detecting affected children and improving their visual function with spectacles. The need for services and potential impact of school-based programs varies widely between areas, depending on prevalence of refractive error and competing conditions and rates of school attendance. Barriers to acceptance of services include the cost and quality of available refractive care and mistaken beliefs that glasses will harm children's eyes. Further research is needed in areas such as the cost-effectiveness of different screening approaches and impact of education to promote acceptance of spectacle-wear. School vision programs should be integrated into comprehensive efforts to promote healthy children and their families.

Prevalence of eye diseases and causes of visual impairment in school-aged children in Western China

Background

The present study investigated the prevalence of refractive error, visual impairment, and eye diseases in school-aged children in western China.

Methods

The survey was done in a representative county (Yongchuan District, Chongqing Municipality) of western China. Cluster random sampling was used to select children aged 6 to 15 years. We conducted door-to-door surveys and eye examinations including optometry, stereoscopic vision test, eye position and eye movement, slit lamp examination of the anterior segment, retinoscopy, and fundus examination after cycloplegia with 1% cyclopentolate.

Results

Among 3469 children, data were available for 3079 (88.76%). The prevalences of eye diseases were, in descending order, refractive error (20.69%; 637/3079), conjunctivitis (11.76%; 362/3079), amblyopia (1.88%; 58/3079), color vision defect (0.52%; 16/3079), keratitis (0.36%; 11/3079), strabismus (0.29%; 9/3079), cataract (0.23%; 7/3079), pathologic myopia (0.19%; 6/3079), and ocular trauma (0.13%; 4/3079). The prevalence of corneal leucoma, corneal staphyloma, optic neuropathy, macular degeneration, and myelinated nerve fibers was 0.03% (1/3079) for each. The prevalence of visual impairment was 7.70% (237/3079), and the major causes of visual impairment were uncorrected refractive error (86.08%; 204/237), amblyopia (9.70%; 23/237), pathologic myopia (1.27%; 3/237), congenital cataract (0.42%; 1/237), and others (2.11%; 5/237).

Conclusions

Among school-aged children in a less developed area of western China, refractive error was the most prevalent eye disorder, and uncorrected refractive error was the main cause of visual impairment.

Missing X and Y: a review of participant ages in population-based eye studies

Ophthalmic population-based studies have been used to establish the frequency of eye disease and the associated environmental and genetic factors that cause vision impairment and blindness. Most of these studies have concentrated on the diseases of ageing: cataract, age-related macular degeneration, glaucoma and diabetic retinopathy. Other studies have identified eye diseases in children but few studies of young adult eye disease exist. We conducted a systematic review of the ophthalmic literature to identify potential population-based eye studies and then note the age of participants in the studies. We then summarized the disease specific to young adults to show there is a need for further research to identify eye disease in this important and often-neglected group in the community. Eighty-four large population-based studies have been conducted worldwide: 9 in North America, 2 in South America, 17 in Africa, 35 in Asia, 11 in Australia and the Pacific, 6 in Europe, 4 in the Middle East and 1 that covered 3 continents. No studies specifically examined young adults. Twenty-six per cent of studies included young adults as part of all ages examined but none of these examined a large number of young adults.

The child self-refraction study results from urban Chinese children in Guangzhou

OBJECTIVE

To compare visual and refractive outcomes between self-refracting spectacles (Adaptive Eyecare, Ltd, Oxford, UK), noncycloplegic autorefraction, and cycloplegic subjective refraction.

DESIGN

Cross-sectional study.

PARTICIPANTS

Chinese school-children aged 12 to 17 years.

METHODS

Children with uncorrected visual acuity ≤ 6/12 in either eye underwent measurement of the logarithm of the minimum angle of resolution visual acuity, habitual correction, self-refraction without cycloplegia, autorefraction with and without cycloplegia, and subjective refraction with cycloplegia.

MAIN OUTCOME MEASURES

Proportion of children achieving corrected visual acuity ≥ 6/7.5 with each modality; difference in spherical equivalent refractive error between each of the modalities and cycloplegic subjective refractive error.

RESULTS

Among 556 eligible children of consenting parents, 554 (99.6%) completed self-refraction (mean age, 13.8 years; 59.7% girls; 54.0% currently wearing glasses). The proportion of children with visual acuity ≥ 6/7.5 in the better eye with habitual correction, self-refraction, noncycloplegic autorefraction, and cycloplegic subjective refraction were 34.8%, 92.4%, 99.5% and 99.8%, respectively (self-refraction versus cycloplegic subjective refraction, P<0.001). The mean difference between cycloplegic subjective refraction and noncycloplegic autorefraction (which was more myopic) was significant (-0.328 diopter [D]; Wilcoxon signed-rank test P<0.001), whereas cycloplegic subjective refraction and self-refraction did not differ significantly (-0.009 D; Wilcoxon signed-rank test P = 0.33). Spherical equivalent differed by ≥ 1.0 D in either direction from cycloplegic subjective refraction more frequently among right eyes for self-refraction (11.2%) than noncycloplegic autorefraction (6.0%; P = 0.002). Self-refraction power that differed by ≥ 1.0 D from cycloplegic subjective refractive error (11.2%) was significantly associated with presenting without spectacles (P = 0.011) and with greater absolute power of both spherical (P = 0.025) and cylindrical (P = 0.022) refractive error.

CONCLUSIONS

Self-refraction seems to be less prone to accommodative inaccuracy than noncycloplegic autorefraction, another modality appropriate for use in areas where access to eye care providers is limited. Visual results seem to be comparable. Greater cylindrical power is associated with less accurate results; the adjustable glasses used in this study cannot correct astigmatism. Further studies of the practical applications of this modality are warranted.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Ocular morbidity prevalence among school children in Shimla, Himachal, North India

Background

Data on eye diseases among school children is not readily available. Considering the fact that one-third of India's blind lose their eyesight before the age of 20 years and many of them are under five when they become blind, early detection and treatment of ocular morbidity among children is important.

Aim

To estimate the prevalence of ocular morbidity among school children of age 6-16 years.

Settings

Government and private coeducational schools in urban area of Shimla.

Design

Cross-sectional

Materials and Methods

Government and private coeducational schools selected by stratified random sampling. About 1561 school children, studying in elementary through secondary class in these schools were examined from August 2001 to January 2002 in Shimla. A doctor did visual acuity and detailed ophthalmic examination.

Statistical analysis

The Chi-square test was used to test differences in proportions. Differences were considered to be statistically significant at the 5% level.

Results

Prevalence of ocular morbidity was 31.6% (CI=29.9-32.1%), refractive errors 22% (CI=21.1-22.8%), squint 2.5% (CI=2.4-2.6%), color blindness 2.3% (CI=2.2-2.4%), vitamin A deficiency 1.8 % (CI=1.7-1.9%), conjunctivitis 0.8% (CI=0.79-0.81%). Overall prevalence of ocular morbidity in government and private schools did not show any statistical significant difference. Prevalence of conjunctivitis was significantly (P<0.5) more in government schools.

Conclusion

A high prevalence of ocular morbidity among high-school children was observed. Refractive errors were the most common ocular disorders.

Prevalence of Refractive Error in Malay Primary School Children in Suburban Area of Kota Bharu, Kelantan, Malaysia

Introduction: Refractive error remains one of the primary causes of visual impairment in children worldwide, and the prevalence of refractive error varies widely. The objective of this study was to determine the prevalence of refractive error and study the possible associated factors inducing refractive error among primary school children of Malay ethnicity in the suburban area of Kota Bharu, Kelantan, Malaysia. Materials and Methods: A school-based cross-sectional study was performed from January to July 2006 by random selection on Standard 1 to Standard 6 students of 10 primary schools in the Kota Bharu district. Visual acuity assessment was measured using logMAR ETDRS chart. Positive predictive value of uncorrected visual acuity equal or worse than 20/40, was used as a cut-off point for further evaluation by automated refraction and retinoscopic refraction. Results: A total of 840 students were enumerated but only 705 were examined. The prevalence of uncorrected visual impairment was seen in 54 (7.7%) children. The main cause of the uncorrected visual impairment was refractive error which contributed to 90.7% of the total, and with 7.0% prevalence for the studied population. Myopia is the most common type of refractive error among children aged 6 to 12 years with prevalence of 5.4%, followed by hyperopia at 1.0% and astigmatism at 0.6%. A significant positive correlation was noted between myopia development with increasing age (P <0.005), more hours spent on reading books (P <0.005) and background history of siblings with glasses (P <0.005) and whose parents are of higher educational level (P <0.005). Malays in suburban Kelantan (5.4%) have the lowest prevalence of myopia compared with Malays in the metropolitan cities of Kuala Lumpur (9.2%) and Singapore (22.1%). Conclusion: The ethnicity-specific prevalence rate of myopia was the lowest among Malays in Kota Bharu, followed by Kuala Lumpur, and is the highest among Singaporean Malays. Better socio-economic factors could have contributed to higher myopia rates in the cities, since the genetic background of these ethnic Malays are similar. Key words: Children, Myopia, Refractive error

Performance measures of the illiterate E-chart vision-screening test used in Northern District Israeli school children

Objectives

To evaluate the screening performance of 6/6 and 6/12 vision cut-offs with an illiterate E-chart implemented by a public health nurse to test children for ocular abnormalities and uncorrected refractive error. The gold standard diagnosis is an eye examination performed by an ophthalmologist.

Setting

A cross-sectional population-based study was conducted among 2113 students' ages 6–7 and 13–14 years old in 70 Northern District Israeli schools.

Methods

Students were tested by nurses and ophthalmologists. A nurse examination was carried out using the illiterate E-chart for vision measurement. The medical examination included vision history, clinical eye examination, vision and retinoscopy testing. The Physician's evaluation of whether students needed a referral for diagnostic procedures, treatment and/or follow-up was recorded. Screening test's performance was determined using ophthalmologist's decision regarding referral as the gold standard. Detection rate (DR), false-positive rate (FPR), odds affected positive result (OAPR), positive predictive value (PPV) and negative predictive value (NPV) were estimated overall and by students' demographic characteristics.

Results

For vision >6/6 cut-off in at least one eye (eyes tested separately): DR – 71.9% (95% CI 65.8–78.7%), FPR – 22.8% (95% CI 17.9–28.9%), OAPR – 0.98:1 (95% CI 0.84:1–1.15:1), PPV – 52.7% (95% CI 45.4–61.2%), NPV – 90.9% (95% CI 88.7–93.1%). For 6/12 vision cut-off, namely vision 6/12 or worse in both eyes (tested separately): DR – 58.6 (95% CI 51.8–66.4%), FPR – 15.2% (95% CI 10.9–21.1%), OAPR – 1.13:1 (95% CI 0.94:1–1.35:1), PPV – 61.1% (95% CI 52.9–70.6%), NPV – 87.6% (95% CI 84.9–90.4%).

Conclusions

Vision-screening test performance measures are mild. It is suggested to change vision cut-off level that denotes vision abnormality from current policy of vision not equal 6/6 in both eyes (tested separately) to vision 6/12 or worse in both eyes (tested separately). This change will result in reduction of FPR from 22% to 15%, concomitant with an increase in false-negative rate from 28% to 41%. Students may be equally screened by either a senior or a less experienced nurse.

Prevalence of ocular disease in Tibetan primary school children

BACKGROUND

There is very little information on the prevalence of ocular diseases in Tibetan children who live in the remote areas of the Qinghai-Tibetan Plateau. The purpose of this study was to investigate the prevalence of ocular diseases in primary school children between 6 and 14 years of age in the rural Tibetan area of Maqin County, China.

METHODS

All the children from 8 Tibetan township primary schools in Maqin County underwent a full eye examination by a team of 6 senior ophthalmologists.

RESULTS

A total of 1084 children were included in this investigation, of which 199 (18.36%, 95% confidence interval [CI] 16.05-20.66) had ocular morbidity. Of these, 98 were male and 101 were female. Refractive errors were found in 11.07% (95% CI 9.20-12.94), strabismus in 2.49% (95% CI 1.56-3.42), corneal leukoma in 1.20% (95% CI 0.55-1.85), amblyopia in 1.02% (95% CI 0.42-1.61), and vernal conjunctivitis in 0.65% (95% CI 0.17-1.12). Monocular blindness was seen in 16 cases (1.48%, 95% CI 0.76-2.19). Trauma was the most common cause of blindness.

INTERPRETATION

The prevalence of eye disorder is high among school-aged Tibetan children in Maqin County, representing an important health problem. More effort should be devoted to the study, prevention, and treatment of these diseases. Effective strategies are needed to reduce the incidence of visual impairment in this population of children.

Vision First, a program to detect and treat eye diseases in young children: the first four years

PURPOSE

The Vision First program began in the fall of 2002 as a community outreach initiative by the Cleveland Clinic Cole Eye Institute in partnership with the Cleveland Metropolitan School District. It was designed to provide free eye examinations to all prekindergarten, kindergarten, and first grade students enrolled in Cleveland City public schools in order to diagnose refractive errors, amblyopia, and strabismus, so that treatment is instituted and the best possible visual outcome attained.

METHODS

Examinations are performed in 2 lanes of a specially outfitted recreational vehicle. All children undergo monocular visual acuity testing at distance and near, stereopsis testing, cover testing at distance and near, testing of versions, and external ocular inspection. If a child fails any part of this examination according to the guidelines set by the American Academy of Pediatrics, cycloplegic drops are instilled and an optometrist refracts the child on location and performs indirect ophthalmoscopy. Glasses are prescribed and follow-up with a pediatric ophthamologist is arranged.

RESULTS

During the first 4 years of the program, 22,988 examinations were performed. Seven percent of children had errors of refraction that necessitated optical correction, about 2.1% had strabismus, and 1.7% had amblyopia. The cost per student per year was around $23 excluding glasses.

CONCLUSIONS

About 10% of 5- and 6-year-old schoolchildren have eye problems that require either glasses or treatment for strabismus or amblyopia. The Vision First model brings eye care professionals to the schools and provides effective comprehensive screening of all children, as well as detailed examination and referral of those with significant eye problems.

Trachoma surveys 2000-2005: results, recent advances in methodology, and factors affecting the determination of prevalence

With the advent of VISION 2020 and GET 2020 inaugurated by the World Health Organization, it is timely to provide an update of the methodology employed in trachoma surveys, given that a significant number of individuals in many undeveloped and developing countries still suffer from this ophthalmic disease. The advent of Trachoma Rapid Assessment and Asymmetrical Sampling Rapid Trachoma Assessment has enabled faster identification of trachoma-endemic areas, though population-based surveys are still required prior to intervention. Research into factors affecting prevalence determination has shown that mobility, clustering, and seasonality should all be taken into account regarding survey design. In addition, recent advances in laboratory testing have given us new insight into trachoma infection patterns and a better understanding of the disease course. In this review, we examine advances in survey methodology and the results of trachoma surveys since 1999, and other issues relevant to the determination of trachoma prevalence. Based on recent findings, we recommend that pooled nucleic acid amplification testing be used to augment clinical assessment in areas where trachoma prevalence is greater than 20%. Further, we suggest that trachoma follicular and trachoma follicular or trachoma intense, as markers of the disease, be reported separately.

Prevalence of refractive error and other eye diseases in schoolchildren in the Greater Accra region of Ghana

PURPOSE

To determine the prevalence of refractive error and other eye diseases in schoolchildren in the Greater Accra region of Ghana.

METHODS

Research assistants tested visual acuity (VA) using a Snellen chart in students randomly selected from 24 schools (i.e., 8 metropolitan, 8 urban, and 8 rural). An ophthalmologist examined students with VA of 6/12 or worse in either eye and students with other eye problems.

RESULTS

Nine hundred fifty-seven students aged 6 to 22 years were screened: 67 had myopia with VA of 6/12 or worse in the better eye, 3 were unilaterally blind (2 from squint or amblyopia, 1 from a hypoplastic disk), and 4 had unilateral low vision from macular scars. Other eye diseases observed were congenital glaucoma (1), vernal conjunctivitis (2), and infective conjunctivitis (6). The prevalence of refractive error reducing vision to at least 6/12 was 7.0%. The prevalence of squint and amblyopia was 0.2%.

CONCLUSION

The most common eye defect in the students was refractive error. Squint and amblyopia were rare.

Pattern of eye diseases and visual impairment among students in southwestern Nigeria

PURPOSE

The aim of the study was to determine the prevalence and causes of eye diseases and visual impairment in students in the Ilesa East local government area of Osun state, Nigeria.

METHODS

A cross-sectional survey that utilised a multistage random sampling method to select 1,144 primary and secondary school students.

RESULTS

A total of 1,144 students (504 males and 640 females) were involved in the study. Their ages ranged from 4 to 24 years. The majority (97.8%) of them were below 18 years of age. A total of 177 (15.5%) of the school children were found to have eye diseases. The major ocular disorders were in the following order: conjunctiva 91 (51.4%), refractive error 66 (37.3%), lid 7 (4.0%), corneal, including staphyloma and keratoconus 5 (2.8%) and then others. These included conjunctival diseases 91 (8%) constituted mainly by allergic/vernal conjunctivitis 85 (7.4%), refractive error 66 (5.8%), lid disorders 6 (0.6%), squint 3 (0.3%), corneal scarring 3 (0.3%) and cataract 2 (0.2%). A total of 15 students were visually impaired, with a prevalence of 1.26%. Only two students were blind, with a prevalence of 0.17%. Causes of visual impairment were refractive error 10 (0.87%), bilateral immature cataract 1 (0.08%), corneal opacities 2 (0.2%), amblyopia leading to squint 1 (0.08%) and cataract 1 (0.08%). The causes of blindness in students were bilateral corneal scars presumed to be due to vitamin A deficiency in one (0.08%) student and complicated bilateral keratoconus with complicated vernal ulcers in another (0.08%).

CONCLUSIONS

Eye diseases are common amongst Nigerian students. Eye examination for all new intakes and regular screening in both public and private primary and secondary schools is advocated. Wearing of corrective glasses should be emphasised for children with refractive error. Causes of blindness and visual impairment in children attending regular schools in Nigeria were avoidable.

Inferring myopia over the lifecourse from uncorrected distance visual acuity in childhood

AIM

To report the usefulness of uncorrected distance visual acuity (DVA) at 16 years to "screen" for myopia status and to assess the lifetime risk of myopia, based on a national birth cohort.

METHODS

1867 members of the 1958 British birth cohort for whom there were data on acuity at 16 years had autorefraction, as part of a biomedical survey, at 45 years. Reduced uncorrected DVA at age 16 years (6/12 or worse in both eyes) was compared with adult refraction (spherical equivalent).

RESULTS

Only a quarter of individuals in the population studied who had developed myopia by 45 years of age had reduced acuity at 16 years of age. Notably, half of all adults with moderate myopia (-2.99 to -5.99) and 31% (11/35) with severe myopia (> or =-6) had good uncorrected DVA in both eyes at 16 years of age. Thus, sensitivities were low, ranging from 16% for all myopia (cut-off point spherical equivalent -0.5) to 69% for severe myopia (cut-off point spherical equivalent -6). However, a high (91%) lifetime probability of primary myopia (spherical equivalent > or =-0.5) given a reduced uncorrected DVA at 16 years was found.

CONCLUSION

In this population, reduced uncorrected DVA in childhood is an inaccurate and inappropriate intermediate "phenotype" for capturing adult myopia status. However, our findings support assessment of DVA in secondary school children as an effective method of identifying refractive error (both myopia and hypermetropia).

Clinical disorders affecting mesopic vision

Vision in the mesopic range is affected by a number of inherited and acquired clinical disorders. We review these conditions and summarize the historical background, describing the clinical characteristics alongside the genetic basis and molecular biological mechanisms giving rise to rod and cone dysfunction relevant to twilight vision. The current diagnostic gold standards for each disease are discussed and curative and symptomatic treatment strategies are summarized.

The value of corneal transplantation in reducing blindness

PURPOSE

To analyse the role of keratoplasty in reducing world blindness due to corneal diseases.

METHODS

Review of published literature. We collected and analysed articles published in the English language literature related to the prevalence and causes of blindness in different parts of the world, causes of corneal blindness, and outcome of corneal transplantation for various corneal diseases.

RESULTS

A total of 80% of the world's blind live in developing countries. Retinal diseases are the most important causes of blindness (40-54%) in established economy nations while cataract (44-60%) and corneal diseases (8-25%) are the most common causes of blindness in countries with less developed economies. Keratitis during childhood, trauma, and keratitis during adulthood resulting in a vascularized corneal scar and adherent leucoma are the most frequent causes of corneal blindness in developing countries. Corneal diseases are responsible for 20% of childhood blindness. Nearly 80% of all corneal blindness is avoidable. The outcome of keratoplasty for vascularized corneal scar and adherent leucoma is unsatisfactory, necessitating repeat surgery in a high proportion of these cases. Other barriers for keratoplasty in these nations are suboptimal eye banking, lack of trained human resources, and infrastructure.

CONCLUSIONS

Since the developing world carries most of the load of corneal blindness and the major causes of corneal blindness are corneal scar and active keratitis, development of corneal transplantation services need a comprehensive approach encompassing medical standards in eye banking, training of cornea specialists and eye banking personnel and exposure of ophthalmologists to care of corneal transplants for better follow-up care. However, concerted efforts should be made to develop and implement prevention strategies since most corneal blindness is preventable.

Screening for correctable visual acuity deficits in school-age children and adolescents

BACKGROUND

Although the benefits of vision screening seem intuitive, the value of such programmes in junior and senior schools has been questioned. In addition to this there exists a lack of clarity regarding the optimum age, and frequency at which to carry out screening.

OBJECTIVES

The objective of this review is to evaluate the effectiveness of vision screening programmes carried out in schools in reducing the prevalence of undetected, correctable visual acuity deficits due to refractive error in school-age children.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials - CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) on The Cochrane Library (Issue 3 2004), MEDLINE (1966 to August 2004) and EMBASE (1980 to August 2004). No language or date restrictions were placed on these searches. To date it has not been possible to carry out any manual searches but it is hoped to include these in a future update.

SELECTION CRITERIA

We planned to include randomised controlled trials including randomised cluster controlled trials.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed study abstracts identified by the electronic searches. No trials were identified that met the inclusion criteria.

MAIN RESULTS

As no trials were identified, no formal analysis was performed. A narrative synthesis of other retrieved studies was undertaken in order to explain current practice.

AUTHORS' CONCLUSIONS

At present there are no robust trials available that allow the benefits of school vision screening to be measured. The disadvantage of attending school with a visual acuity deficit also needs to be quantified. The impact of a screening programme will depend on the geographical, and socio-economic setting in which it is conducted. There is therefore clearly a need for well planned randomised controlled trials, in various settings, to be undertaken so that the potential benefits and harms of vision screening can be measured.

Ill-health reported by schoolchildren during questionnaire surveys in Ghana, Mozambique and Tanzania

BACKGROUND

Insufficient attention has been paid to the health problems of school-age children in sub-Saharan Africa. A questionnaire administered to schoolchildren about their ill-health has been developed to identify schools in which urinary schistosomiasis occurs. The data collected during the interviews can also be used to assess other common health problems.

OBJECTIVES

To analyse data collected during health questionnaires in schools to assess how schoolchildren perceive their own health, and to compare the findings between three countries in sub-Saharan Africa.

METHODS

Questionnaires asking about recent health problems were administered by teachers to schoolchildren in 120 primary schools in Mozambique, 52 primary schools in Tanzania and 298 primary schools in Ghana. A total of 67 002 children aged 8-15 years took part.

RESULTS

Of the 10 health problems asked about in all questionnaires, the average number reported by each child was 3.9 in Ghana, 3.4 in Mozambique and 3.1 in Tanzania. The distributions of the prevalence of each condition among schools were similar and the prevalence of all conditions showed a similar ranking. For most conditions a greater percentage of girls than boys reported each health problem.

CONCLUSIONS

Schoolchildren in Ghana, Mozambique and Tanzania do not perceive themselves to be healthy. The pattern of reported health problems was similar in each country. School health questionnaires are worthy of further study and validation.

Ocular morbidity in schoolchildren in Kathmandu

BACKGROUND/AIMS

Any information on eye diseases in schoolchildren in Nepal is rare and sketchy. A programme to provide basic eye screening to schoolchildren with an aim to provide services as well as gather information on ocular morbidity has been started.

METHODS

All the children in the schools visited are included in the study. This programme is targeted at poor government schools, which are unable to afford this service. A complete eye examination is given to all the children including slit lamp examination, fundus evaluation and retinoscopy, and subjective refraction.

RESULTS

A total of 1100 children from three schools are included in this report. 11% of our schoolchildren have ocular morbidity, 97% (117 out of 121) of which is preventable or treatable. Refractive error is the commonest type of ocular morbidity (8.1%). Myopia is the commonest type of refractive error (4.3%) as opposed to hypermetropia (1.3%). 12.4% of children with refractive error have already developed amblyopia. Strabismus is the second commonest type of ocular disability (1.6%). Alternate divergent squint is the commonest type of strabismus (1.4%). Traumatic eye injuries (0.54%), xerophthalmia (0.36%), and congenital abnormalities (0.36%) are much less common.

CONCLUSION

A school eye screening cum intervention programme with periodic evaluation seems to be appropriate for countries like Nepal as most of the eye diseases found are preventable or treatable.

Myopia in secondary school students in Mwanza City, Tanzania: the need for a national screening programme

BACKGROUND/AIMS

The prevalence of significant refractive errors and other eye diseases was measured in 2511 secondary school students aged 11-27 years in Mwanza City, Tanzania. Risk factors for myopia were explored.

METHODS

A questionnaire assessed the students' socioeconomic background and exposure to near work followed by visual acuity assessment and a full eye examination. Non-cycloplegic objective and subjective refraction was done on all participants with visual acuity of worse than 6/12 in either eye without an obvious cause.

RESULTS

154 (6.1%) students had significant refractive errors. Myopia was the leading refractive error (5.6%). Amblyopia (0.4%), strabismus (0.2%), and other treatable eye disorders were uncommon. Only 30.3% of students with significant refractive errors wore spectacles before the survey. Age, sex, ethnicity, father's educational status, and a family history of siblings with spectacles were significant independent risk factors for myopia.

CONCLUSION

The prevalence of uncorrected significant refractive errors is high enough to justify a regular school eye screening programme in secondary schools in Tanzania. Risk factors for myopia are similar to those reported in European, North-American, and Asian populations.

Sensitivity and specificity of visual acuity screening for refractive errors in school children

PURPOSE

To examine the optimal cutoff point for the use of the visual acuity test to screen for refractive errors in schoolchildren.

METHODS

In a sample of schoolchildren between 7 and 9 years old, visual acuity testing was performed using modified ETDRS charts monocularly without optical aids by trained personnel. Cycloplegic autorefraction was performed in each eye. The screening efficacy of using various cutoff points for referring children for further optometric/ ophthalmic assessment was studied. Myopia was defined as a spherical equivalent of at least -0.5 D, hyperopia a spherical equivalent of at least +2.0 D, and astigmatism a cylinder of at least -1.0 D in at least one eye. The sensitivity, specificity, and predictive values were calculated using each patient as a case; a receiver operator curve was plotted.

RESULTS

A total of 1,028 children were tested. A satisfactory sensitivity/specificity profile was obtained using a referral criterion of visual acuity worse than or equal to 0.28 logarithm of the minimum angle of resolution in at least one eye. In this scenario, the sensitivity and specificity of this screening test were 72% (95% confidence interval [CI], 68 to 76) and 97% (95%CI, 95 to 98), respectively. The positive and negative predictive values were 96% (95%CI, 93 to 98) and 78% (95%CI, 75 to 82), respectively.

CONCLUSIONS

The modified ETDRS visual acuity chart can be used to predict refractive errors in schoolchildren in Singapore in a sensitive and specific manner using a referral criterion of worse than or equal to 0.28 logarithm of the minimum angle of resolution.