Population-Based Assessment of Unilateral Visual Impairment in the South Indian State of Andhra Pradesh: Rapid Assessment of Visual Impairment (RAVI) Project

Abstract

Purpose: To assess the prevalence and causes of unilateral visual impairment (VI) in the South Indian state of Andhra Pradesh.

Methods: A population-based cross-sectional study was conducted among individuals aged ≥40 years in one urban and two rural locations, using rapid assessment methodology. A 2-stage cluster random sampling method was used to select 7800 individuals from 156 clusters. Distance visual acuity (VA) was assessed using a standard Snellen chart at a distance of 6 m. Eye examinations were conducted using a torchlight and distance direct ophthalmoscopy. Unilateral VI was defined as presenting VA <6/18 in one eye and presenting VA ≥6/18 in the other, and included moderate unilateral VI (<6/18 to 6/60) and unilateral blindness (<6/60).

Results: In total, 7378 individuals (94.6%) were examined. After excluding 918 individuals with VI in the better eye, data were analyzed for the remaining 6460 individuals. Among those included in the analysis, mean age was 50 years (standard deviation 9.6 years), 46.7% were male, 58.9% had no education, and 34.1% were urban residents. The prevalence of unilateral VI was 11.3% (95% confidence interval 10.5-12.1%; n = 730). Uncorrected refractive error was found to be the leading cause (44%; n = 321) of unilateral VI followed by cataract (39.7%; n = 290).

Conclusions: Unilateral VI is common in the South Indian state of Andhra Pradesh. As most of this VI can be addressed with interventions such as cataract surgery and spectacles, service models need to be streamlined to address this need.

Keywords: Andhra Pradesh; cataract; rapid assessment; refractive errors; visual impairment.