Blindness and eye disease in Cambodia

PURPOSE: To assess the prevalence and etiology of blindness and low vision and to assess the prevalence of common eye diseases in central Cambodia. METHODS: In this cross-sectional, population-based study, 6,558 residents of Kandal Province, Cambodia were registered, and 5,803 (88.5%) were interviewed and examined. This house-to-house survey was conducted by a team consisting of a senior ophthalmologist, a Cambodian eye doctor, and eight Cambodian eyecare workers. RESULTS: The prevalence of bilateral blindness (visual acuity <3/60) is 1.1% (95% confidence interval [CI], 0.9-1.4), and an additional 4.4% (95% CI, 3.9-5.0) have low vision (visual acuity < 6/18, > or =3/60 in the better eye). The major causes of bilateral blindness are cataract (67.4%), phthisis (6.1%), uncorrected refractive error (6.1%), corneal scar (5.3%), uncorrected aphakia (3.0%), trachoma corneal scar (3.0%), optic atrophy (3.0%), and others (6.1%). The major causes of low vision are uncorrected refractive error (49.8%) and cataract (42.7%). The prevalence of unilateral blindness is 1.2% (95% CI, 0.9-1.4), often caused by cataract, corneal scar, or phthisis. Trauma due to landmine explosions and war-related injuries was frequently the underlying etiology in subjects with phthisis, corneal scarring, or other pathology.CONCLUSIONS: The prevalence of blindness and low vision in Cambodia is relatively high compared to other developing countries. Most of the causes of blindness and low vision are treatable or preventable. Landmines and other war-related injuries are an important cause of ocular injury. These results will assist in developing a national plan for the prevention of blindness in Cambodia.     

Blindness and Eye Disease in Cambodia

Purpose: To assess the prevalence and etiology of blindness and low vision and to assess the prevalence of common eye diseases in central Cambodia. Methods: In this cross-sectional, population-based study, 6,558 residents of Kandal Province, Cambodia were registered, and 5,803 (88.5%) were interviewed and examined. This house-to-house survey was conducted by a team consisting of a senior ophthalmologist, a Cambodian eye doctor, and eight Cambodian eyecare workers. Results: The prevalence of bilateral blindness (visual acuity <3/60) is 1.1% (95% confidence interval [CI], 0.9–1.4), and an additional 4.4% (95% CI, 3.9–5.0) have low vision (visual acuity < 6/18, ≥3/60 in the better eye). The major causes of bilateral blindness are cataract (67.4%), phthisis (6.1%), uncorrected refractive error (6.1%), corneal scar (5.3%), uncorrected aphakia (3.0%), trachoma corneal scar (3.0%), optic atrophy (3.0%), and others (6.1%). The major causes of low vision are uncorrected refractive error (49.8%) and cataract (42.7%). The prevalence of unilateral blindness is 1.2% (95% CI, 0.9–1.4), often caused by cataract, corneal scar, or phthisis. Trauma due to landmine explosions and war-related injuries was frequently the underlying etiology in subjects with phthisis, corneal scarring, or other pathology.Conclusions: The prevalence of blindness and low vision in Cambodia is relatively high compared to other developing countries. Most of the causes of blindness and low vision are treatable or preventable. Landmines and other war-related injuries are an important cause of ocular injury. These results will assist in developing a national plan for the prevention of blindness in Cambodia.     

上海市宝山区5000名学生视力监测与干预情况

目的:通过监测获得宝山区中小学生视力、屈光不良情况,研究行为干预对近视发展有无影响。方法:采用整群随机抽样的方法,在上海市宝山区抽取中小学校5所,参照《眼科全书》近视诊断标准对所有学生进行视力普查,对视力低常学生使用拓普康RA800型验光仪进行电脑验光,选择基础条件相似的两所学校部分班级进行分组,加以行为干预,0.5a后对所测学生进行复查。结果:宝山区学生视力不良率高于上海市平均水平,且随年级升高呈现出阶梯性增长态势。小学生视力不良率已经达到将近50%,初中生达到了70%以上。随着年级增高,轻度屈光不良所占比例越来越低,重度屈光不良所占比例也越来越高,从一年级的10%左右增长到初二年级的30%左右。每个年级监测人群前后两次视力不良对比无统计学差异,每个年级屈光不良分级构成比前后无统计学差异。不能认为采取的干预措施对学生视力不良率的发展产生作用,但是干预对学生护眼知识方面水平的提高比较明显。结论:学生视力不良率随年级升高而逐渐升高,重度屈光不良所占比例也逐渐升高,强化行为干预对限制学生近视发展无明显作用。     

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.     

郑州市金水区小学生视力状况调查

目的　调查郑州市金水区７～１２岁小学生视力状况及屈光不正的患病情况,为小学生视力保健工作提供科学依据。方法　横断面调查研究,分层整群抽样方法,以学校为单位,随机抽取郑州市金水区３所小学,对抽样学校内的１～６年级在校学生进行普查,共调查７８４５名学生。眼部检查包括裸眼视力、矫正视力、眼前节、眼底、眼压及眼位检查,并对任意一眼或双眼裸眼视力＜１．０且眼压正常的儿童进行睫状肌麻痹验光。结果　实际受检学生７６８１名,应答率为９７．９１％。裸眼视力在７～８岁呈现逐年增加趋势,两两比较差异有显著统计学意义（Ｐ＜０．０１）;９～１２岁时裸眼视力视力呈现逐年下降趋势,两两比较差异有显著统计学意义（Ｐ＜０．０１）。任一眼裸眼视力≤０．５者占总人数３７．３９％,并且随着年龄增长,视力低下人群所占比例逐渐加大（７岁１５．２５％、８岁１８．３５％、９岁３１．６７％、１０岁４２．９６％、１１岁５１．７３％、１２岁６０．０３％）。接受睫状肌麻痹后验光的小学生中,近视的总患病率为３８．５８％,远视的总患病率为４．８４％。Ｌｏｇｉｓｔｉｃ回归分析显示,近视眼的等效球镜度与年龄呈显著正相关（ｒ＝１．７６９,Ｐ＜０．０１）;远视眼的等效球镜度与年龄呈显著负相关（ｒ＝－０．９２３,Ｐ＜０．０１）。受检的视力损伤者中屈光不正占８６．４０％,弱视占１２．４０％,沙眼导致的角膜混浊占０．０３％,其他原因导致的角膜混浊占０．３１％,白内障占０．４４％,视网膜疾病占０．１９％,其他致病原因占０．２５％。结论　郑州市金水区７～１２岁小学生视力损害的主要原因是近视,９岁是正视向近视转变的高敏年龄。     

山东滕州市农村小学生弱视斜视及立体视锐度调查

目的 调查滕州市农村小学生的视力、立体视锐度及弱视和斜视的患病情况,并对Titmus立体视图检查法、视力检查法、Titmus立体视图联合视力检查法三种弱视筛选试验进行评价.方法 应用随机整群抽样调查方法,共抽取滕州市8所农村小学,共有小学生2742人,年龄5～14岁,平均(9.3±2.3)岁.进行Titmus立体视图、裸眼视力、眼位及眼球运动检查,对任一眼裸眼视力<1.0者进行视网膜检影验光.结果 (1)小学生视力低常率为13.83%,从7岁至13岁视力低常率呈逐渐上升趋势;视力低常的首位原因为屈光不正,弱视,其中近视占79.67%(486眼/610眼);(2)弱视患病率为1.50%.97.5%(39/40)的弱视患儿为首次被筛查出来;斜视患病率为1.72%;(3)非弱视/斜视儿童的立体视锐度5岁年龄组为60″,6岁年龄组为50″,7岁及以上年龄组均为40″;弱视患者中立体视锐度异常者占77.5%(31140),斜视患者中立体视锐度异常者占28.3%(13/46);(4)Titmus立体视图联合视力检查法筛选弱视的特异度(99.47%)及粗一致性(99.06%)最高,误诊率(0.53%)最低;其次为Titmus立体视图检查法(特异度为97.98%;粗一致性为97.59%;误诊率为2.02%);视力检查法的特异度(87.47%)及粗一致性(87.66%)最低,误诊率(12.53%)最高.结论 滕州市农村小学生视力低下的首位原因为近视;弱视和斜视是影响立体视觉发育的主要因素;Titmus立体视图联合视力检查法可提高学龄儿童弱视筛选的效率.     

温州市区小学生弱视的筛选及屈光状态分析

目的 研究弱视在小学生中的发病率、屈光状态分布和主要影响因素。方法 在全市视力 小学生中,用列镜筛选,再用扩瞳检影验光进行屈光测定,选择矫正视力≤４．９;眼科检查无器质性病变的弱视患者,分别检查注视性质,眼位、单视功能及询问填写调查表。并分别作统计学处理。结果 在受检６３６００眼中,确诊弱视１２０５人,２２６６只眼,患病为３．７８％;以屈光不正弱视为主,其中远视性弱视最高。弱视程度与屈光度、注视性     

National survey of blindness and low vision in The Gambia: results.

A population based survey of blindness and eye disease has been conducted throughout the whole country of The Gambia, and 8174 people were examined. The prevalence of blindness (best acuity less than 3/60) was 0.7% and low vision (6/24-3/60) 1.4%. The causes of blindness were cataract (55%), non-trachomatous corneal opacity/phthisis (20%), and trachoma (17%). An estimated 5500 people in The Gambia require cataract surgery, 4600 eyelid surgery for entropion, and 4600 people spectacles to correct a refractive error which causes a visual acuity of less than 6/18. More than half the current burden of blindness in The Gambia is potentially remediable through the provision of cataract surgery and aphakic spectacles.     

Prevalence and causes of vision loss in central Tanzania

A population-based survey of the prevalence of major blinding disorders was conducted in three villages in central Tanzania. Overall, 1827 people overthe age of seven years old were examined. In those age seven and older, the prevalence of bilateral blindness (visual acuity in the better eye of <3/60) was 1.26% and monocular blindness (visual acuity of <3/60 in one eye) was 4.32% and the prevalence of visual impairment (visual acuity <6/18 but 3/60 in both eyes was 1.04% and in one eye was 1.75%. Corneal opacities were responsible for 44% of bilateral and 39% of monocular blindness and resulted from trachoma, measles often in association with Vitamin A deficiency, keratoconjunctivitis, and the use of traditional eye medicines. Cataracts accounted for 22% of bilateral and 6% of monocular blindness. Readily preventable or reversible causes of blindness were responsible for 65% of cases of bilateral and 46% of monocular blindness.Abbreviations TEM traditional eye medicines     

Prevalence of high astigmatism, eyeglass wear, and poor visual acuity among Native American grade school children.

PURPOSE: The purpose of this study was to examine the prevalence of astigmatism and poor visual acuity and rate of eyeglass wear in grade school children who are members of a Native American tribe reported to have a high prevalence of large amounts of astigmatism. METHODS: Vision screening was conducted on 1,327 first through eighth grade children attending school on the Tohono O'odham Reservation. Noncycloplegic autorefraction was conducted on the right and left eye of each child using the Nikon Retinomax K+ autorefractor, and monocular recognition acuity was tested using ETDRS logarithm of the minimum angle of resolution (logMAR) letter charts. RESULTS: Tohono O'odham children had a high prevalence of high astigmatism (42% had > or = 1.00 D in the right or left eye) and the axis of astigmatism was uniformly with-the-rule. However, only a small percentage of children arrived at the vision screening wearing glasses, and the prevalence of poor visual acuity (20/40 or worse in either eye) was high (35%). There was a significant relation between amount of astigmatism and uncorrected visual acuity with each additional diopter of astigmatism resulting in an additional 1 logMAR line reduction in visual acuity. CONCLUSIONS: Uncorrected astigmatism and poor visual acuity are prevalent among Tohono O'odham children. The results highlight the importance of improving glasses-wearing compliance, determining barriers to receiving eye care, and initiating public education programs regarding the importance of early identification and correction of astigmatism in Tohono O'odham children.     

A comparative clinical survey of the prevalence of refractive errors and eye diseases in urban and rural school children

Objective: To assess the prevalence of refractive error and common ocular diseases in school-aged children in urban and rural populations in and around Hyderabad, India.Design: Population-based, cross-sectional study. Participants: A total of 3314 school children, 1789 from urban areas and 1525 from rural areas.Methods: The examination included visual acuity measurements, retinoscopy and autorefraction under cycloplegia, examination of the anterior segment and external eye, and ocular motility evaluation.Results: In the urban group the prevalence of uncorrected presenting and best-corrected visual impairment (≤20/40 in the better eye) was 9.8%, which dropped to 7.1% with presenting vision and was further reduced to 1.1% with best-corrected visual acuity. Uncorrected visual acuity in the rural group was 6.6%, which dropped to 3.3% with presenting vision and was further reduced to 2.5% with best-corrected visual acuity. The prevalence of refractive error was greater (25.2%) in the urban than the rural group (8%). Myopia measured with autorefraction was observed in 51.4% of urban children and 16.7% in rural children. Increased literacy rate, duration of study hours, and older age of the child were found to have contributed more to the prevalence of myopia in the urban group. Hyperopia with autorefraction was found to be 3.3% in the urban and 3.1% in the rural group. Hyperopia was associated with younger age in the study group. Trachoma was the leading cause of ocular morbidity in the rural group (3.5%) compared with the urban group (0.16%). Night blindness was reported in 3.2% of children in the rural group and 0.33% in the urban group. Vitamin A deficiency, low socio-economic status, and poor personal and environmental hygienic practice were found to have a positive correlation with ocular morbidity among rural group children.Conclusions: Provision of health education, periodic visual screening programs, and primary eye care by trained health care personnel in the elementary schools will prevent the prevalence of refractive errors and common ocular diseases in school children.     

Unilateral visual impairment in an urban population in southern India

This study assessed the prevalence and causes of unilateral visual impairment in the urban population of Hyderabad city as part of the Andhra Pradesh Eye Disease Study. Stratified, random, cluster, systematic sampling was used to select 2,954 subjects from 24 clusters representative of the population of Hyderabad. Eligible subjects underwent detailed eye examination including logMAR visual acuity, refraction, slitlamp biomicroscopy, applanation tonometry, gonioscopy, dilatation, cataract grading, and stereoscopic evaluation of fundus. Automated threshold visual fields and slitlamp and fundus photography were done when indicated by standardised criteria. Unilateral visual impairment was defined as presenting distance visual acuity < 6/18 in the worse eye and > or = 6/12 in the better eye, which was further divided into unilateral blindness (visual acuity < 6/60 in the worse eye) and unilateral moderate visual impairment (visual acuity < 6/18-6/60 in the worse eye). A total of 2,522 subjects (85.4% of eligible), including 1,399 > or = 30 years old, participated in the study. In addition to the 1% blindness and 7.2% moderate visual impairment (based on bilateral visual impairment criteria) reported earlier in this sample, 139 subjects had unilateral visual impairment, an age-gender-adjusted prevalence of 3.8% (95% confidence interval 2.7-4.9%). The major causes of this visual impairment 39.9% were refractive error (42.9%), cataract (14.4%), corneal disease (11.5%), and retinal disease (11.2%). Of this unilateral visual impairment was blindness. The major causes of unilateral blindness were corneal disease (23.2%), cataract (22.5%), retinal disease (18%), and optic atrophy (12.9%). On the other hand, the predominant cause of unilateral moderate visual impairment was refractive error (67%) followed by cataract (9%). Of the total unilateral visual impairment, 34.3% was present in those < 30 years old and 36.2% in those 30-49 years old. Unilateral visual impairment afflicts approximately 1 in 25 persons in this urban population. A large proportion of this unilateral visual impairment is present in younger age groups. The causes of unilateral visual impairment, like those of bilateral visual impairment in this population, are varied, suggesting therefore, that in addition to the current focus of eye care in India predominantly on cataract, other causes of visual impairment need to be addressed as well.     

Screening compliance and visual outcome in diabetes

PURPOSE: To study the relationship between screening compliance and visual outcome in a screening programme for diabetic eye disease. METHODS: A retrospective case control study. The screening compliance of all the diabetes patients (n = 22) listed at the Icelandic National Registry for the Blind (visual acuity <0.3) was compared to a matched group of 44 non-blind diabetes patients (visual acuity > or =0.3) who participated in the same screening programme for diabetic retinopathy. Glycaemic control (HbA1c), office blood pressure and cholesterol levels were assessed. RESULTS: The study group had a significantly lower level of compliance with the screening programme (27% +/- 38% [mean +/- SD] versus 77% +/- 26% [mean +/- SD]; p < 0.0001). Macular oedema or proliferative diabetic retinopathy was found in 60% (13/22) of the study group when entering the screening programme, compared to 7% (3/44) in the control group. Blood pressure (except diastolic BP among type 1 diabetes mellitus), blood glucose and cholesterol levels were identical. The prevalence of blindness and low vision amongst diabetes patients in Iceland is about 0.5%. CONCLUSIONS: There was a significant relationship between screening compliance and visual outcome in diabetes patients in our screening programme.     

Low vision and blindness in adults in Gurage Zone,central Ethiopia

AIM: To determine the magnitude and causes of low vision and blindness in the Gurage zone, central Ethiopia. METHODS: A cross sectional study using a multistage cluster sampling technique was used to identify the study subjects. Visual acuity was recorded for all adults 40 years and older. Subjects who had a visual acuity of <6/18 were examined by an ophthalmologist to determine the cause of low vision or blindness. RESULTS: From the enumerated population, 2693 (90.8%) were examined. The prevalence of blindness (<3/60 better eye presenting vision) was 7.9% (95% CI 6.9 to 8.9) and of low vision (6/24-3/60 better eye presenting vision) was 12.1% (95% CI 10.9 to 13.3). Monocular blindness was recorded in 16.3% of the population. Blindness and low vision increased with age. The odds of low vision and blindness in women were 1.8 times that of the men. The leading causes of blindness were cataract (46.1%), trachoma (22.9%), and glaucoma (7.6%). While the prevalence of vision reducing cataract increased with age, the prevalence of trachoma related vision loss did not increase with age, suggesting that trichiasis related vision loss in this population might not be cumulative. CONCLUSION: The magnitude of low vision and blindness is high in this zone and requires urgent intervention, particularly for women. Further investigation of the pattern of vision loss, particularly as a result of trachomatous trichiasis, is warranted.     

Blindness and eye diseases in Tibet: findings from a randomised, population based survey

BACKGROUND: Public health officials of the Tibet Autonomous Region (TAR) of China requested a survey of blindness, eye diseases, and eye care service utilisation to assist the development of a 10 year blindness prevention and treatment plan. The objective of the survey was to determine the prevalence of blindness and visual impairment, as well as cataract surgical coverage and surgical outcome in the TAR. METHODS: The Tibet Eye Care Assessment was a cross sectional prevalence study of three of the seven prefectures (provinces) of the TAR (Lhoka, Nakchu, and Lingzhr) selected to represent its three main environmental regions. The survey sample was selected using a random multistage cluster method. Two teams conducted the survey in a standardised fashion in each prefecture, Lhoka during May and Nakchu during June 1999, and Lingzhr during May 2000. Visual acuity, cause of vision loss, trachoma, and vitamin A deficiency were included in the clinical examination. RESULTS: Among the 15,900 people enumerated, 12,644 were examined for an overall response rate of 79.6%. The crude prevalence of blindness (presenting better eye visual acuity of less than 6/60) was 2.3%; age and sex adjusted blindness prevalence was 1.4% (95% CI 1.3 to 1.5). Visual impairment (better eye presenting visual acuity of 6/24 to 6/60) was found in 10.9% (95% CI 10.5 to 11.2) of the population (age and sex adjusted). Cataract was the primary cause of blindness (50.7%), followed by macular degeneration (12.7%) and corneal opacity (9.7%). CONCLUSION: Blindness is a serious public health problem in Tibet, with prevalence higher than in similar studies in eastern China. As elsewhere in the world, women have an excess burden of blindness compared to men. About 75% of blindness in Tibet can be either prevented or treated. Eye care planning for Tibet must focus on cataract, particularly among women.     

Trachoma, cataracts and uncorrected refractive error are still important contributors to visual morbidity in two remote indigenous communities of the Northern Territory, Australia

Purpose:  To assess the contribution of trachoma, cataract and refractive error to visual morbidity among Indigenous adults living in two remote communities of the Northern Territory.
Design, Setting and Participants:  Cross-sectional survey of all adults aged 40 and over within a desert and coastal community.
Main outcome measures:  Visual acuity, clinical signs of trachoma using the simplified WHO grading system and assessment of cataract through a non-dilated pupil.
Results:  Two hundred and sixty individuals over the age of 40 years participated in the study. The prevalence of visual impairment (<6/12) was 17%. The prevalence of blindness (<3/60) was 2%, 40-fold higher than seen in an urban Australian population when adjusted for age. In total, 78% of adults who grew up in a desert community had trachomatous scarring compared with 26% of those who grew up in a coastal community ( P  ≤ 0.001). In the desert community the prevalence of trachomatous trichiasis was 10% and corneal opacity was 6%. No trachomatous trichiasis or corneal opacity was seen in the coastal community.
Conclusions:  Trachoma, cataract and uncorrected refractive error remain significant contributors to visual morbidity in at least two remote indigenous communities. A wider survey is required to determine if these findings represent a more widespread pattern and existing eye care services may need to be re-assessed to determine the cause of this unmet need.     

Prevalence of blindness and visual impairment in Pakistan: the Pakistan National Blindness and Visual Impairment Survey

PURPOSE: To determine the prevalence of blindness and visual impairment in adults aged 30 years and older in Pakistan and to assess socio-demographic risk factors. METHODS: Multistage, stratified (rural/urban), cluster random sampling, with probability proportional-to-size procedures, was used to select a nationally representative, cross-sectional sample of adults 30 years of age or older. Each subject was interviewed; had visual acuity measured (logMAR; logarithm of the minimum angle of resolution); and underwent autorefraction, biometry, and fundus-optic disc examination. Those with less than 6/12 acuity in either eye underwent a detailed ophthalmic examination, including corrected distance visual acuity measurement and dilated ophthalmoscopy. RESULTS: A nationally representative sample of 16,507 adults (95.5% of those enumerated) was examined. The age- and gender-standardized prevalence of blindness was 2.7% (95% confidence interval [CI], 2.4%-2.9%). It has been estimated that there are 1,140,000 (962,000-1,330,000) blind adults in Pakistan (2003 statistics). Blindness prevalence varied throughout the country, being highest in the provinces of Punjab and Baluchistan and lowest in the North West Frontier Province. Rural areas had a higher prevalence of blindness than did urban areas (3.8% vs. 2.5%, P < 0.001). Increasing age and being female were significantly associated with presenting visual acuity of <6/60 (odds ratio [OR], 2.5; 95% CI, 2.3-2.7 and 1.3; 95% CI, 1.1-1.5, respectively). Educational status was also associated with presenting visual acuity of <6/60. Subjects who had attended primary school were 60% (P < 0.001) less likely to have acuity of <6/60 than were subjects who had never been to school. CONCLUSIONS: This comprehensive survey provides reliable estimates of the prevalence of visual impairment and blindness in Pakistan. A significant excess of visual impairment was found among the elderly and the uneducated. After adjustment for age differences, women were found to have a significant excess of severe visual impairment and blindness. Regional variations in the prevalence of blindness were also identified.     

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.     

Prevalence and causes of blindness and visual impairment in Limbe urban area, South West Province, Cameroon

AIM: To conduct a rapid assessment of cataract surgical services to estimate the prevalence and causes of blindness and visual impairment in members of the population aged >/=40 years in the Limbe urban area, Cameroon. METHODS: Clusters of 50 people aged >/=40 years were sampled with probability proportionate to size. Compact segment sampling was used to select households within clusters. All eligible people had their visual acuity (VA) measured by an ophthalmic nurse. An ophthalmologist examined people with VA<6/18. RESULTS: 2215 people were examined (response rate = 92.3%). The prevalence of bilateral blindness was 1.1% (95% CI: 0.7-1.5%), 0.3% (0.1-0.6%) for severe visual impairment and 3.0% (2.0-4.0%) for visual impairment. Posterior-segment disease was the leading cause of blindness (29%), followed by cataracts (21%) and optic atrophy (21%). Cataracts were the most common cause of severe visual impairment (43%) and visual impairment (48%). Most cases of blindness (50%), severe visual impairment (57%) and visual impairment (78%) were avoidable (that is, they were caused by cataracts, refractive error, corneal scar, onchocerciasis or phthisis/no globe). The cataract surgical coverage was relatively high, although 57% of eyes operated upon had a poor outcome (presenting VA<6/60). CONCLUSIONS: Although the prevalence of blindness was relatively low, most of the cases were avoidable. The implementation of an effective eye-care programme remains a priority in the Limbe urban area.