Four-year incidence and progression of visual impairment in a South Indian population with diabetes

PURPOSE The aim of this study is to investigate the 4-year incidence and progression of visual impairment (VI) and the associated risk factors for incident VI in a South Indian population with type 2 diabetes. METHODS A total of 634 participants with type 2 diabetes were found eligible after 4 years. Visual acuity (VA) was estimated using the modified Early Treatment Diabetic Retinopathy Study protocol. VA in the better eye was considered for the assessment of VI based on the World Health Organization criteria. Mild VI was defined as VA <20/40 but up to 20/60, moderate VI as VA <20/60 but up to 20/200, severe VI as VA <20/200 but up to 10/200, and blindness as VA worse than 10/200. RESULTS The 4-year incidence of any VI, mild VI, moderate VI, severe VI, and blindness was 21.7%, 18.3%, 3.4%, 0.0%, and 0.0%, respectively; of the 13 participants with VI at baseline, 12 (92%) showed worsening/progression of VI on follow-up. Multiple logistic regression showed that nuclear cataract of grades >4.0 (odds ratio [OR]: 2.612 [1.148-5.942], P = 0.022) and lower socioeconomic score (OR: 0.965 [95% confidence interval, (0.933-0.998)], P = 0.040) were associated with the risk of future incident VI. Refractive error (47%) and cataract (30%) were identified as the leading causes of incident VI at follow-up. CONCLUSIONS VI seems to be a significant problem among diabetic participants in the South Indian population. Refractive error and cataract are the leading but treatable causes of incident VI in this population and would benefit from intervention.