Prevalence of blindness and its causes among those aged 50 years and above in rural Karnataka, South India

Prevalence and causes of avoidable blindness and severe visual impairment in a tribal district of Maharashtra, India

BACKGROUND

We present the outcomes of a survey conducted in Nandurbar, a tribal district of Maharashtra, India. It was based on "Rapid Assessment for Avoidable Blindness" methodology and conducted in 2009 in Nandurbar, a tribal district of Maharashtra, India.

MATERIALS AND METHODS

We examined persons of 50 years and older ages. Ophthalmic assistants noted the distant vision [best corrected vision (BCV) and as presented]. Ophthalmologist examined eyes of persons with vision less than 6/18. The principal cause of impairment in each eye and the most "preventable" or "treatable" cause were assigned. We calculated the prevalence rates of bilateral blindness, severe visual impairment (SVI), and moderate visual impairment (MVI).

RESULT

We examined 2,005/2,300 persons (response rate 87.2%). The prevalence of blindness, SVI, and MVI for the BCV was 1.63% (95% CI 1.11-2.15), 5.93% (95% CI 4.96-6.90), and 14.6% (95% CI 13.2-16.1), respectively. The prevalence of blindness, SVI, and MVI for the presented vision was 1.87% (1.32-2.42), 6.72% (95% CI 5.70-7.74), and 19% (95% CI 17.4-20.6), respectively. Unoperated cataract was responsible for 77% of different visual disabilities. The coverage of existing cataract surgery service was 9.4%. Lack of knowledge about cataract surgery was the main cause of unoperated cataract among 41% of interviewed participants with cataract and SVI.

CONCLUSION

Unoperated cataract was the main curable cause of visual disabilities in tribal population of India. Increasing awareness and offering cataract surgeries at affordable cost in the district would reduce visual disabilities.

Prevelence and causes of visual impairment and blindness in older adults in an area of India with a high cataract surgical rate

BACKGROUND

The cataract surgical rate (CSR) in Gujarat, India is reported to be above 10,000 per million population. This study was conducted to investigate the prevalence and causes of vision impairment/blindness among older adults in a high CSR area.

METHODS

Geographically defined cluster sampling was used in randomly selecting persons >or= 50 years of age in Navsari district. Subjects in 35 study clusters were enumerated and invited for measurement of presenting and best-corrected visual acuity and an ocular examination. The principal cause was identified for eyes with presenting visual acuity < 20/32.

RESULTS

A total of 5158 eligible persons were enumerated and 4738 (91.9%) examined. Prevalence of presenting visual impairment < 20/63 to 20/200 in the better eye was 29.3% (95% confidence interval [CI]: 27.5-31.2) and 13.5% (95% CI: 12.0-14.9) with best correction. The prevalence of presenting bilateral blindness (< 20/200) was 6.9% (95% CI: 5.7-8.1), and 3.1% (95% CI: 2.5-3.7) with best correction. Presenting and best-corrected blindness were both associated with older age and illiteracy; gender and rural/urban residence were not significant. Cataract in one or both eyes was the main cause of bilateral blindness (82.6%), followed by retinal disorders (8.9%). Cataract (50.3%) and refractive error (35.4%) were the main causes in eyes with vision acuity < 20/63 to 20/200, and refractive error (86.6%) in eyes with acuity < 20/32 to 20/63.

CONCLUSIONS

Visual impairment and blindness is a significant problem among the elderly in Gujarat. Despite a reportedly high CSR, cataract remains the predominant cause of blindness.

Rapid Assessment of Avoidable Blindness in India

BACKGROUND

Rapid assessment of avoidable blindness provides valid estimates in a short period of time to assess the magnitude and causes of avoidable blindness. The study determined magnitude and causes of avoidable blindness in India in 2007 among the 50+ population.

METHODS AND FINDINGS

Sixteen randomly selected districts where blindness surveys were undertaken 7 to 10 years earlier were identified for a follow up survey. Stratified cluster sampling was used and 25 clusters (20 rural and 5 urban) were randomly picked in each district.. After a random start, 100 individuals aged 50+ were enumerated and examined sequentially in each cluster. All those with presenting vision <6/18 were dilated and examined by an ophthalmologist. 42722 individuals aged > = 50 years were enumerated, and 94.7% examined. Based on presenting vision,, 4.4% (95% Confidence Interval[CI]: 4.1,4.8) were severely visually impaired (vision<6/60 to 3/60 in the better eye) and 3.6% (95% CI: 3.3,3.9) were blind (vision<3/60 in the better eye). Prevalence of low vision (<6/18 to 6/60 in the better eye) was 16.8% (95% CI: 16.0,17.5). Prevalence of blindness and severe visual impairment (<6/60 in the better eye) was higher among rural residents (8.2%; 95% CI: 7.9,8.6) compared to urban (7.1%; 95% CI: 5.0, 9.2), among females (9.2%; 95% CI: 8.6,9.8) compared to males (6.5%; 95% CI: 6.0,7.1) and people above 70 years (20.6%; 95% CI: 19.1,22.0) compared to people aged 50-54 years (1.3%; 95% CI: 1.1,1.6). Of all blindness, 88.2% was avoidable. of which 81.9% was due to cataract and 7.1% to uncorrected refractive errors/uncorrected aphakia.

CONCLUSIONS

Cataract and refractive errors are major causes of blindness and low vision and control strategies should prioritize them. Most blindness and low vision burden is avoidable.