Changing scenario of cataract blindness in Kolar District, Karnataka, South India. The utility of rapid assessment of avoidable blindness in reviewing programs

Abstract

Purpose: To estimate the prevalence and causes of blindness in persons aged 50 years and over in Kolar district, India, using rapid assessment of avoidable blindness (RAAB) methodology and compare results with a similar study done in 1995.

Methodology: A total of 61 clusters of 50 people aged 50 years and over were selected by probability proportional to size sampling. Households were selected by compact segment sampling. Participants were evaluated using standard RAAB methodology.

Results: Of 3050 people visited, 2907 were examined (95.3%). Prevalence of bilateral blindness (visual acuity, VA, <3/60 in the better eye with available correction) was 3.9%, and severe visual impairment (SVI; VA <6/60 - 3/60 in the better eye with available correction) was 3.5%. Untreated cataract was the leading cause of blindness (74.6%) and SVI (73.3%). Compared with the previous study, results showed a significant drop in prevalence of blindness from all causes from 8.0% to 3.9% (p < 0.001). Prevalence of cataract blindness (VA <3/60) had also decreased. Cataract surgical coverage (CSC) showed a significant increase from the previous survey (46.2% to 81.7%).

Conclusion: Rapid assessments conducted once in 8-10 years at a district level, give reliable estimates on the prevalence of blindness and help monitor planning and implementation of eye care programs. Despite a turnaround in Kolar district seen over the last 16 years, with a decrease in the prevalence of blindness and increased CSC, untreated cataract continues to be the leading cause of blindness, warranting sustained service delivery efforts and careful planning.