Rapid Assessment of Avoidable Blindness

Abstract

and to evaluate the Rapid Assessment for Avoidable Blindness (RAAB), a new methodology to measure the magnitude and causes of blindness. Design: Cross-sectional population-based survey. Participants: Seventy-six clusters of 50 people 50 years or older were selected by probability proportionate to size sampling of clusters. Households within clusters were selected through compact segment sampling. Three thousand seven hundred eighty-four eligible subjects were selected, of whom 3503 (92.6%) were examined. Methods: Participants underwent a comprehensive ophthalmic examination in their homes by an ophthalmologist, including measurement of visual acuity (VA) with a tumbling-E chart and the diagnosis of the principal cause of visual impairment. Those who had undergone cataract surgery were questioned about the details of the operation and their satisfaction with surgery. Those who were visually impaired from cataract were asked why they had not gone for surgery. Main Outcome Measures: Visual acuity and principal cause of VA�6/18. Results: The prevalence of bilateral blindness (presenting VA � 3/60) was 2.0 % (95 % confidence interval [CI], 1.5%–2.4%), and prevalence of bilateral visual impairment (VA of �6/18–�6/60) was 5.8 % (95 % CI