Prevalence and Causes of Visual Impairment and Blindness in an Urban Indian Population: The Singapore Indian Eye Study

Purpose: To describe the prevalence and causes of visual impairment and blindness in an urban Indian population. Design: Population-based study. Participants: Ethnic Indians aged more than 40 years living in Singapore. Methods: Participants underwent standardized ophthalmic assessments for visual impairment and blindness, defined using best-corrected visual acuity (BCVA) and presenting visual acuity (PVA), according to US and modified World Health Organization (WHO) definitions. Main Outcome Measures: Unilateral visual impairment or blindness was defined on the basis of the worse eye, and bilateral visual impairment or blindness was defined on the basis of the better eye. Primary causes of visual impairment were determined. Results: A total of 3400 eligible individuals (75.6% response rate) participated. On the basis of US definitions, the age-standardized prevalence was 0.4% for bilateral blindness (<= 20/200, better eye) and 3.4% for bilateral visual impairment (<20/40 to >20/200, better eye). Another 0.3% of bilateral blindness and 13.4% of bilateral visual impairment were correctable with refraction. Cataract was the principal cause of best-corrected bilateral blindness (60.0%) and bilateral visual impairment (65.7%). Other major causes of blindness and visual impairment included diabetic retinopathy, age-related macular degeneration, glaucoma, corneal opacity, and myopic maculopathy. Conclusions: The prevalence of bilateral blindness and visual impairment in Indians living in Singapore is lower than estimates from populations living in India, but similar to estimates obtained from Singapore Malay and Chinese populations. Cataract is the leading cause of blindness and visual impairment. One in 20 cases of bilateral blindness and 1 in 10 cases of bilateral visual impairment are attributable to diabetic retinopathy. These data may have relevance to many ethnic Indian persons living outside India.