Magnitude and causes of blindness in the developing world

Summary Table 5 summarises the available data on blindness prevalence for different areas of the world with estimates of the number of blind by continent.     

Causes of blindness among adult Jordanians: a hospital-based study

PURPOSE: To assess the causes of blindness among adults aged 20 years and over who attended two big general ophthalmic clinics in Jordan. PATIENTS AND METHODS: This hospital-based study was undertaken at Jordan University Hospital in Amman (the capital of Jordan) and Princess Basma Teaching Hospital which is affiliated with Jordan University of Science and Technology in Irbid, the third largest city in the country. A total of 2732 patients seen consecutively over 26 months were examined and the ophthalmic findings were recorded. Using standard Snellen charts, subjects were placed in one of three categories according to their best corrected visual acuity: (1) unilateral blindness: less than 6/60 in the worst eye, 6/60 or more in the better eye; (2) moderate bilateral blindness: less than 6/60 in the worst eye, less than 6/60 to 3/60 or more the better eye; and (3) severe bilateral blindness: less than 3/60 in both eyes. RESULTS: Of the totalpatients seen, 373 were blind according to the selection criteria. Among 248 patients with unilateral blindness, diabetic retinopathy, cataract and trauma were the leading causes. Among the 81 patients with moderate bilateral blindness, diabetic retinopathy and cataract were the leading causes. Diabetic retinopathy and glaucoma were the leading causes in patients with severe bilateral blindness. CONCLUSIONS: These data could be used in planning blindness prevention and treatment programs while awaiting a national survey on the prevalence and causes of blindness in Jordan.     

The prevalence and causes of blindness in the Sultanate of Oman: the Oman Eye Study (OES)

AIMS: To estimate the magnitude and the causes of blindness through a community based nationwide survey in Oman. This was conducted in 1996-7. METHODS: A stratified cluster random sampling procedure was used to select 12 400 people. The WHO/PBD standardised survey methodology was used, with suitable adaptation. The major causes of blindness were identified among those found blind. RESULTS: A total of 11 417 people were examined (response rate 91.8%) The prevalence of blindness in the Omani population was estimated to be 1.1% (95% CI 0.9 to 1.3), blindness being defined according to the WHO Tenth Revision of the International Classification of Diseases. Prevalence of blindness was clearly related to increasing age, with estimates of 0.08% for the 0-14 age group, 0.1% for the 15-39 age group, 2.3% for the 40-59 age group, and 16.8% for the group aged 60 +. There was a statistically significant difference between the prevalence in females (1.4%) and males (0.8%). The northern and central regions had a higher prevalence of blindness (1.3% to 3%). The major causes of blindness were unoperated cataract (30.5%), trachomatous corneal opacities (23.7%), and glaucoma (11.5%) CONCLUSIONS: Despite an active eye healthcare programme, blindness due to cataract and trachoma remains a public health problem of great concern in several regions of the sultanate. These results highlight the need, when planning effective intervention strategies, to target the eye healthcare programme to the ageing population, with special emphasis on women.     

Perceptions of blindness related to smoking: a hospital-based cross-sectional study

AIMS: Smoking is associated with several serious eye diseases. Awareness of smoking and blindness, and its potential to act, as a stimulus to assist stopping smoking has not been investigated. METHODS: A cross-sectional survey using a structured interview of adult patients attending district general hospital ophthalmology, general surgery, and orthopaedic clinics. The interview investigated the awareness and fear of blindness for three established smoking-related diseases, and a distractor condition (deafness), and the likelihood that smokers would quit on developing early signs of each condition. RESULTS: Response was 89.1% (358/402). In all, 183 (51.1%) of responders were male and 175 (48.9%) female. Only 9.5% of patients believed that smoking was definitely or probably a cause of blindness, compared with 92.2% for lung cancer, 87.6% for heart disease, and 70.6% for stroke. Patients ranked their fear of each of the five conditions, scoring five for the most feared and one for the least feared. Patients were significantly (P<0.01) less fearful of blindness (mean score 2.80) than lung cancer (3.89), heart disease (3.58), and stroke (3.35). About one-half of smokers stated that they would definitely or probably quit smoking if they developed early signs of blindness or the three established smoking-related conditions, with no significant differences in proportions for these four conditions. CONCLUSION: The findings suggest that awareness of the risk of blindness from smoking is low, but that the fear of blindness is as compelling a motivation to quit as fear of lung cancer, heart disease, and stroke. The link between smoking and eye disease should be publicised to help reduce smoking prevalence.     

Prevalence of glaucoma types and legal blindness from glaucoma in the western region of Saudi Arabia: a hospital-based study

To determine prevalence of glaucoma subtypes and legal blindness in patients on their first visit to an ophthalmic center in the western region of Saudi Arabia a chart review analysis was carried out of new patients in 2006 with glaucoma diagnosis in our Glaucoma Unit. Diagnosis was confirmed clinically and by glaucoma workup. The main outcome was prevalence of glaucoma types and legal blindness from glaucoma. Of 2,354 new patients in 2006, 417 were glaucomatous. Mean age was 56.4 years and mean intraocular pressure (IOP) was 26.5 mmHg; 54.4% had prior glaucoma diagnosis. Prevalence of primary open-angle glaucoma was 30.5%, primary angle-closure 24.7%, neovascular 7.6%, surgically induced 6.5%, and exfoliative 5.2%. One-third of patients were unilaterally legally blind, whereas 11.3% were bilateral. Primary glaucoma represents two-thirds of glaucoma cases in Saudi Arabia. Approximately one-half of patients were legally blind in at least one eye at time of presentation.     

Prevalence and causes of blindness & low vision; before and five years after 'VISION 2020' initiatives in Oman: a review

BACKGROUND: A prevalence survey of blindness and low vision was conducted in Oman in 2005. Here, we present the prevalence and determinants of blindness and low vision among the population >or= 40 years of age. The results are then compared with those of the survey in 1997 and the changes following the 'VISION 2020' initiatives are assessed. METHODS: The survey covered 24 randomly selected clusters (75 houses in each). Teams assessed the distance vision of subjects while wearing glasses. The ophthalmologists examined the anterior segment and fundus to determine the causes of disability. The visual field was tested in those suspected of glaucoma. The prevalence rates of blindness (< 3/60 on presentation), legal blindness (< 6/60) and low vision (< 6/18) were calculated. The data from the 1997 survey was then analyzed to obtain similar rates in the population >or= 40 years of age. RESULTS: The prevalence of blindness was 8.25% (95% CI 7.14-9.36) in the >or= 40 year-old population in 2005. The rate would be 6.95% (95% CI 5.92-7.98) if blindness were defined as vision with best possible correction. The prevalence of legal blindness and low vision were 12% and 45.12%, respectively. In the 1997 survey, the prevalence of blindness in same age group was 7.23% (95% CI 5.91-8.55). Between the two surveys, the prevalence of blindness due to corneal pathology declined from 1.9% to 1.1% but that of blindness due to unoperated cataract increased from 1.8% to 2.3%. CONCLUSIONS: The rate of disability has declined but the number of blind people has increased in Oman. The causes of blindness have changed from communicable/avoidable eye diseases to non-curable/chronic eye diseases, and the number with visual disabilities has increased. An increasing number of operations for cataract and improvements in the care for glaucoma and diabetic retinopathy are recommended.     

Prevalence and causes of visual impairment and blindness in the South Western region of Saudi Arabia

A population-based survey of the prevalence of major causes of blindness and visual impairment was conducted in Bisha region, Saudi Arabia. Overall, 2882 people were examined. The prevalence of blindness (visual acuity of < 3/60 in the better eye with best available correction) was 0.7% and the prevalence of visual impairment (visual acuity < 6/12 but 3/60 in the better eye with best available correction) was 10.9%. Cataracts were responsible for 52.6% of blindness and 20.6% of visual impairment. Refractive errors accounted for 67.9% of visual impairment. Proper management of cataracts and correction of refractive errors will cure 73.6% of blind subjects and 88.5% of visually handicap people in this part of the world.     

Coverage of cataract surgery per person and per eye: review of a community-based blindness survey in Oman

BACKGROUND AND OBJECTIVE: The data from a national survey of blindness and common eye diseases in Oman in 1996 were reviewed. The objective was to compare the calculation of cataract surgery services coverage on a per eye and per person basis. The advantages and limitations of both methods of program management are evaluated. METHODS AND MATERIALS: The information on cataract status, visual status and past history/evidence of cataract surgery was collected for 11,415 Omani subjects. The coverage of existing cataract services was calculated per eye and per person. The rates by gender, age groups, regional groups and type of cataract were also compared. RESULTS: The cataract surgery services could address more than 60% of the reported persons with blinding cataract (vision less than 3/60) and more than half of the eyes with blinding cataract. The services could cover more than one-fourth of the persons with cataract (with any grade of vision defect) and less than one-fourth of the eyes with cataract. If the coverage of cataract services for blinding cataract is calculated using persons as the denominator, it is nearly 10% higher than that calculated using eyes as the denominator. CONCLUSIONS: The two methods of calculating the coverage of cataract services give different results and both are useful for monitoring ophthalmic services. A national program should implement a system for reporting the visual and cataract status of the fellow eye so that coverage rates could be calculated by person and by eye and the impact of the cataract services in relation to time, place, gender and resources could be reviewed.     

Diabetic retinopathy in Oman: a hospital based study

The magnitude of diabetic retinopathy, its determinants, and coverage of laser treatment for diabetic retinopathy among registered people with diabetes in Oman are presented. 2249 randomly selected subjects representing 5564 registered diabetics were examined. WHO recommended definitions of diabetes, retinopathy, and other related conditions were used. Physicians reported the profile of the diabetes while ophthalmologists reported ocular profile and the eye care provided to them. The prevalence of diabetic retinopathy was 14.39% (95% CI 13.46 to 15.31). Men had significantly higher rate of retinopathy than women. The retinopathy rate was higher in age groups 50-59 years and 60-69 years. The rates of background retinopathy, proliferative retinopathy, and diabetic maculopathy were 8.65%, 2.66%, and 5.12%, respectively. The rate was higher among subjects with longer duration of diabetes than those with a shorter duration. Those with an HbA(1c) level more than 9% had significantly higher rates of diabetic retinopathy than those with an HbA(1c) level less than 9%. The retinopathy rate was higher in cases with hypertension, nephropathy, and neuropathy. Of those with diabetic retinopathy who were advised to have treatment at the time of registration, only 20% were treated with laser therapy.     

Common causes of blindness: a pilot survey in Brooklyn, New York

The causes of blindness in 105 consecutive legally blind patients were analyzed in a large urban multidisciplinary medical center. It was found that the leading causes of blindness, in order of frequency of incidence, were glaucoma, diabetic retinopathy, senile macular degeneration, and cataract. The periodic collection of statistics on the relative frequency of the causes of blindness is strongly suggested so that possible changes and improvements in health care may be determined.     

Common causes of blindness: a pilot survey in Jaipur, Rajasthan.

The cause of blindness in 1006 consecutive legally blind patients were analyzed in a large urban multidisciplinary medical center. It was found that the leading causes of blindness, in order of frequency of incidence, were cataract, corneal blindness, glaucoma and ocular trauma. The periodic collection of statistics on the relative frequency of the causes of blindness under Indian conditions is strongly suggested so that priorities can be redefined and improvements in health care may be suggested.     

Cortical blindness in infancy: a follow-up study

Clinical data of 6 cases of cortical blindness in infancy were analyzed. The underlying brain damage was a result of hypoxic events occurring in the pre- or perinatal period, or shortly after birth. The long-term follow-up of the children showed that some visual recovery occurred but capacity of recognition remained impaired. Early diagnosis of this entity and adequate education will help the visual and psychomotor development of the child.     

The prevalence and causes of bilateral and unilateral blindness in an elderly urban Danish population. The Copenhagen City Eye Study

PURPOSE: To study the prevalence and causes of bilateral and unilateral blindness in an elderly urban Danish population. METHODS: Data originated from a Danish epidemiologic cross-sectional random sample population eye survey conducted during the years 1986-1988. The population consisted of 1,000 inhabitants aged 60 to 80 years in Copenhagen. The participants underwent an extensive ophthalmologic examination. A participation rate of 96.9% was achieved. Any blindness was defined as best-corrected visual acuity (VA) worse than 0.05 (the WHO criteria) and VA of 0.1 or worse (the National criteria (NC) of blindness). RESULTS: The prevalence rates of bilateral and unilateral blindness were, respectively, 0.53% and 3.38% according to WHO, but 1.06% and 4.44% using NC. Bilateral blindness rose significantly with age (p=0.02). According to NC, age-related macular degeneration (AMD) was the leading cause of bilateral blindness, accounting for 60% of all blind persons. Glaucoma, myopic macular degeneration, cataract and retinitis pigmentosa were jointly the second most common cause, each accounting for 10% of all bilaterally blind persons. Diabetic retinopathy was not a cause of bilateral blindness. Amblyopia was the most frequent, AMD the second most frequent, and diabetic retinopathy was among the third most common cause of unilateral blindness accounting for, respectively, 28.60%, 16.66% and 9.52% of all unilateral blindness. CONCLUSIONS: Blindness was associated with increasing age. A calculation indicates that among Danes aged 60 to 80 years 7,736 are bilaterally blind and 35,503 suffer from unilateral blindness. This study highlights AMD as the most important cause.