Prevalence and causes of blindness and visual impairment among school children in south-western Nigeria

The aim of the study was to assess the prevalence and identify the causes of blindness and visual impairment in school children of Ilesa-East Local Government Area of Osun State, Nigeria. A total of 1144 school children in primary and secondary schools were selected using a 2-stage random sampling method and examined to determine the prevalence and causes of blindness and visual impairment. A total of 17 (1.48%) children were blind or visually impaired. These comprised of 11 (0.96%) children who were visually impaired and 4 (0.3%) who were severely visually impaired. Only 2 (0.15%) school children were blind. The causes of visual impairment were refractive error 10 (0.87%) and immature cataract 1 (0.08%), causes of severe visual impairment included corneal opacities 2 (0.2%), amblyopia leading to squint 1 (0.08%) and 1 cataract 1 (0.08%). The causes of blindness in school children were corneal scars presumed to be due to vitamin A deficiency 1 (0.08%) and keratoconus 1 (0.08%). Causes of blindness and visual impairment in children attending regular schools in Nigeria were treatable. Prevention, early recognition and prompt treatment of these diseases by regular screening of school children would definitely reduce unnecessary visual handicap in Nigerian school children so that they can attain their full potential in the course of their education. Also, information from this study is relevant for the purpose of planning eye care programmes for the prevention of blindness in Nigerian school children. This will go a long way in the prevention of unnecessary blindness and visual impairment in school children.     

Prevalence and causes of blindness and low vision in leprosy villages of north eastern Nigeria

AIMS: To determine the prevalence and spectrum of ocular pathology, and the prevalence and causes of blindness and low vision in leprosy villages of north eastern Nigeria. METHODS: People affected by leprosy, aged 30 years and above, resident in eight leprosy villages were invited to participate. Ocular examination was undertaken of each consenting individual. RESULTS: 480 people were examined. 456 (48%) of 960 eyes had at least one ocular lesion, but only 37% of all lesions were leprosy related and potentially sight threatening. The prevalence of blindness (VA<3/60 with available correction) was 10.4%. An additional 7.5% of subjects were severely visually impaired (3/60< or =VA<6/60). Cataract was the commonest cause of blindness. Other major causes were non-trachomatous corneal opacity and trachoma. CONCLUSIONS: Blindness and low vision are highly prevalent among leprosy patients in this setting. Only a third of the burden of ocular pathology is related to the direct effects of leprosy. Efforts to reduce the backlog of cataract and trichiasis, to improve early detection and management of lagophthalmos, and to provide refractive services are urgently required.     

Prevalence and causes of blindness and low vision in Timor-Leste

AIM: To estimate the prevalence and causes of blindness and low vision in people aged > or = 40 years in Timor-Leste. METHOD: A population-based cross-sectional survey using multistage cluster random sampling to identify 50 clusters of 30 people. A cause of vision loss was determined for each eye presenting with visual acuity worse than 6/18. RESULTS: Of 1470 people enumerated, 1414 (96.2%) were examined. The age, gender and domicile-adjusted prevalence of functional blindness (presenting vision worse than 6/60 in the better eye) was 7.4% (95% CI 6.1 to 8.8), and for blindness at 3/60 was 4.1% (95% CI 3.1 to 5.1). The adjusted prevalence for low vision (better eye presenting vision of 6/60 or better, but worse than 6/18) was 17.7% (95% CI 15.7 to 19.7). Gender was not a risk factor for blindness or low vision, but increasing age, illiteracy, subsistence farming, unemployment and rural domicile were risk factors for both. Cataract was the commonest cause of blindness (72.9%) and an important cause of low vision (17.8%). Uncorrected refractive error caused 81.3% of low vision. CONCLUSION: Strategies that make good-quality cataract and refractive error services available, affordable and accessible, especially in rural areas, will have the greatest impact on vision impairment.     

Prevalence of Trachoma in Jigawa State,Northwestern Nigeria

ABSTRACT

Purpose: To determine the magnitude of trachoma and the prevalent forms of the disease, and to provide baseline data for the establishment of a trachoma control program in Jigawa State, northwestern Nigeria.

Methods: A population-based cross-sectional survey was conducted in Jigawa State in May 2007 using a 2-stage cluster random sampling technique to select 4598 persons from 40 villages based on probability proportional to size. All participants were examined using a penlight and a 2.5?×?binocular loupe for signs of trachoma, and graded using the World Health Organization (WHO) simplified grading system.

Results: A total of 4598 people were seen with 99.96% coverage. Of these, 2460 (53.5%) were female and 2138 (46.5%) were male. Mean age was 21.6 years (?±?19.8 years). The prevalence of follicular trachoma in children aged ≤9 years was 20.5% (95% confidence interval, CI, 18.7–22.4%) with no difference between the sexes. The prevalence of trichiasis in adults aged ≥15 years was 5%, and the prevalence was higher in females than males (odds ratio 2.60, 95% CI 2.06–3.28; p?<?0.001).

Conclusion: Trachoma is a major problem in Jigawa State; there is a need to train trichiasis surgeons and empower them to carry out community-based surgery. District-level prevalence of trachoma needs to be determined to know which aspects of the WHO SAFE strategy (surgery, antibiotics, facial cleanliness and environmental improvements) need to be emphasized in each district.     

Prevalence and causes of blindness in the northern Transvaal.

During November 1985 a survey was carried out to determine the prevalence and causes of blindness in the Elim Hospital district of Gazankulu in the Northern Transvaal, South Africa, and to assess the Eye Department's effectiveness in preventing blindness. Using a random cluster sample technique, we screened 18,962 of the estimated 71,200 inhabitants of the district (26.6%). We found 109 blind people. The prevalence of blindness was 0.57% (95% confidence interval 0.46%-0.68%). The main causes of blindness were senile cataract (55%), corneal scarring due to trachoma (10%), uncorrected aphakia (9%), and open-angle glaucoma (6%). There were 14 aphakic blind persons who did not have aphakia glasses (43% of all persons operated on for cataract). Women had a significantly higher prevalence of blindness than men. After the age of 60 years the prevalence of blindness increased sharply. Women were 1.6 times less likely to have undergone cataract surgery than men. The two most effective steps to reduce the prevalence of blindness in the Elim district further are to provide aphakia glasses to all aphakic patients and to improve the accessibility of the Eye Department's surgical services.     

Prevalence and causes of blindness and low vision among adults in Fiji

Background: To estimate the prevalence and causes of blindness and low vision among adults aged ≥40 years in Fiji. Design: Population‐based cross‐sectional study. Participants: Adults aged ≥40 years in Viti Levu, Fiji. Method: A population‐based cross‐sectional survey used multistage cluster random sampling to identify 34 clusters of 40 people. A cause of vision loss was determined for each eye with presenting vision worse than 6/18. Main Outcome Measures: Blindness (better eye presenting vision worse than 6/60), low vision (better eye presenting vision worse than 6/18, but 6/60 or better). Results: Of 1892 people enumerated, 1381 participated (73.0%). Adjusting sample data for ethnicity, gender, age and domicile, the prevalence of blindness was 2.6% (95% confidence interval 1.7, 3.4) and low vision was 7.2% (95% confidence interval 5.9, 8.6) among adults aged ≥40 years. On multivariate analysis, being ≥70 years was a risk factor for blindness, but ethnicity, gender and urban/rural domicile were not. Being Indo‐Fijian, female and older were risk factors for vision impairment (better eye presenting vision worse than 6/18). Cataract was the most common cause of bilateral blindness (71.1%). Among participants with low vision, uncorrected refractive error caused 63.3% and cataract was responsible for 25.0%. Conclusion: Strategies that provide accessible cataract and refractive error services producing good quality outcomes will likely have the greatest impact on reducing vision impairment.     

中国四川省视力损伤及盲的原因和发病率

目的:了解四川省低视力及盲的原因和发病率。方法:分层多阶段及随机抽样调查38个县市40351户125641人,进行全面眼部检查,包括标准对数视力表检测视力,发病率以年龄和性别为标准根据2000年中国人口普查结果进行分析。结果:盲率0.77%(95%可信区间:0.72～0.82,n=966),低视力率1.22%(95%可信区间1.14～1.27,n=1513)。视力残疾率城市1.40%,农村2.22%(P<0.01),白内障无论城市还是农村均是首位致残原因(55.7%,n=1381),视网膜疾病居第二(9.7%,n=236),但是城市明显高于农村(34.3%vs2.7%,P<0.01)。角膜病居第三(6.5%,n=161),农村明显多于城市(7.2%vs3.9%,P=0.006)。结论:四川省估计有约172万视力残疾患者,其中52.5万盲人,防盲重心在农村。     

Prevalence and causes of visual impairment and blindness in Sichuan province of China

AIM: To describe the prevalence and causes of low vision and blindness in a population within Sichuan province in southwestern China. · METHODS: A stratified, multi-phased and cluster probability sampling design was employed to enumerate 125641 participants from 40351 households within 38 counties/cities. Participants underwent a comprehensive eye examination, including standardized visual acuity (VA) tests using logarithm of the minimum angle resolution charts. Prevalence was age- and gender-standardized to the 2000 China Census. · RESULTS: Population-weighted prevalence of blindness was 0.77% (95%CI: 0.72-0.82, n=966) and low vision was 1.22% (95%CI: 1.14-1.27, n=1513). Overall, the prevalence of visual disability was 1.40% in the urban population, and 2.22% in the rural population (P<0.01). Cataract was the leading cause of visual disability (55.7%, n =1381), and was of similar frequency in both urban and rural populations. Retinal disease was the second leading cause(9.7%, n =236), but was more common in urban than in rural participants (34.3% vs 2.7%, P <0.01). Corneal disease accounted for 6.5% (n=161) of cases of visual disability, and was more common in the rural population (7.2% vs 3.9%, P =0.006). · CONCLUSION: We estimate that 1.72 million people suffer from visual disability within Sichuan province, of which 525000 are blind, the focus of blindness prevention should be in rural area.     

Prevalence and causes of blindness and low vision in the Casteldaccia Eye Study

In a population-based survey performed on the middleaged and elderly population of Casteldaccia, Sicily, we found that the prevalence of blindness was 0.47% and the prevalence of low vision 1.22%. Unilateral blindness affected 2.81% of the population and unilateral low vision 4.12%. Visual impairment was much more frequently seen in subjects aged 70 years or more than in younger persons. The main cause of visual impairment was cataract, followed by amblyopia, which was responsible for many cases of unilateral low vision.     

Prevalence and causes of blindness and low vision in a rural setting in Pakistan

PURPOSE: To determine the prevalence and causes of blindness and visual impairment in people 40 years of age and older in Budni, Peshawar, Pakistan. METHODS: A population-based cross-sectional study was carried out involving 1,106 men and women 40 years of age and older in a rural area in Pakistan's North West Frontier Province (NWFP). All subjects with a presenting visual acuity < 6/18 in either eye were referred to a centralized clinic for a standardized eye examination that included refraction and dilated fundal examination. The main outcome was blindness (presenting visual acuity < 3/60 in the better eye) and low vision (presenting VA < 6/18-3/60 in the better eye). RESULTS: Of 1,106 people examined, 21 (1.9%; 95% CI: 1.1-2.7%) were blind, while another 27 (2.4%) and 62 (5.5%) subjects had severe visual impairment (< 6/60-3/60) and visual impairment (< 6/18-6/60), respectively. Women, as compared to men, had a higher prevalence of visual impairment and severe visual impairment; but they had a lower prevalence of blindness (1.6 vs. 2.2%); however, the difference was not statistically significant (0.6%; 95% CI: -0.9-2.1%). Similarly farmers had the highest prevalence of blindness. The leading cause of blindness and low vision was cataract, which accounted for 14 of 21 (66.6%) cases of blindness and 49 of 89 (55.5%) cases of low vision. The second leading cause of blindness was uncorrected aphakia. CONCLUSION: Much of the blindness was due to unoperated cataract and uncorrected aphakia. Thus, there is an urgent need to develop ways in which cataract surgical output could be increased, and glasses provided to those who need them.     

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.     

Prevalence and causes of visual impairment and blindness in Sistan-va-Baluchestan Province, Iran: Zahedan Eye Study

AIM: To determine the prevalence and causes of visual impairment and blindness in the Sistan-va-Baluchestan Province of Iran. METHODS: A population-based cross-sectional study with a multistage cluster sampling technique was used to identify the study subjects. Visual acuity (VA) was defined for all participants aged >or=10 years. Participants with a VA of <20/60 were examined by an ophthalmologist to determine the causes of low vision or blindness. RESULTS: 5446 (84.0%) of the invited people were examined. The prevalence of visual impairment (VA <20/60) was 6.81% (95% CI 5.91% to 7.71%) and of bilateral blindness (VA <3/60) was 0.79% (95% CI 0.50% to 1.08%). Visual impairment increased with age and illiteracy. Bilateral blindness doubled in women aged >40 years. The causes of visual impairment and blindness were cataract (37.7%), corneal opacity (15.0%), amblyopia (15.0%), glaucoma (5.7%) and hyperopia (5.0%). 39.5% of the visual impairment cases were potentially curable. CONCLUSION: The estimated magnitude of visual impairment and blindness was much higher than our expectations. Further investigation of the pattern of vision loss in women and children, particularly as a result of trachoma and amblyopia, is warranted. Implementation of measures to treat curable cases of the study population can improve the situation in the region dramatically.