Rapid assessment of cataract blindness in an urban district of Gujarat

Purpose: To estimate the prevalence of bilateral cataract blindness in persons ≥50 years of age in Ahmedabad district, Gujarat. Methods: A total of 1,962 persons ≥50 years of age were examined in clusters of 45 people or less. The survey design used a systematic random cluster sampling. The sample size was calculated assuming a prevalence of bilateral cataract blindness (visual acuity <3/60) of at least 3% and design effect of 1.6, to estimate the actual prevalence of cataract blindness with a sampling error of ≤20 at 80% confidence level. Visual acuity was assessed with glasses, where available, and pinhole was used for visual acuity <6/18. Distant direct ophthalmoscopy in semidark condition with undilated pupil was used to assess the lens status. Results: The age-gender-adjusted prevalence of all blindness was 2.9% in persons ≥50 years of age (6.7% for visual acuity<6/60). The age-gender-adjusted prevalence of bilateral cataract blindness ( visual acuity <3/60) was 1.2% in persons ≥50 years of age. For visual acuity <6/60, the prevalence was 3.1%. The prevalence in females was slightly higher than in males. The prevalence of bilateral and unilateral aphakia and pseudophakia was high. The cataract surgical coverage, an indicator for coverage and service utilization, was 92.9% for persons and 83.1% for eyes. Conclusion: Rapid assessment of cataract blindness in persons ≥50 years of age can be conducted in urban settings with existing resources and at affodable costs, to provide district level data for assessment and monitoring of cataract intervention programs