Causes of blindness, low vision, and questionnaire-assessed poor visual function in Singaporean Chinese adults: The Tanjong Pagar Survey

Abstract

Objective To determine the prevalence rates and causes of low vision, blindness, and patient-assessed deficient visual function among Singaporean Chinese adults. Design Population-based cross-sectional survey. Participants Singaporean Chinese adults 40 to 79 years old (n = 1152). Methods From an initial sampling frame of 40- to 79-year-old Chinese in the Tanjong Pagar district in Singapore, 2000 subjects were selected using a disproportionate, stratified, clustered, random-sampling method. Of 1717 eligible subjects, 1232 were examined (participation rate = 71.8%), and 80 adults who did not have visual acuity (VA) data were excluded from the analysis. Main outcome measures Bilateral low vision was defined as best-corrected VA (BCVA) worse than 6/18 and 3/60 or better, and bilateral blindness as BCVA worse than 3/60 in the better eye or constriction of the visual field to within 10°of fixation, in accordance with the World Health Organization criteria. Patient-assessed visual function was measured using a modified VF-14 questionnaire. Results The age- and gender-adjusted prevalence rates were 1.1% (95% confidence interval [CI], 0.6-1.8) for bilateral low vision and 0.5% (95% CI, 0.2-1.1) for bilateral blindness, and the mean visual function score was 98.6. The rates of bilateral low vision and blindness increased with age, whereas visual function scores decreased with age, even after adjusting for gender and education. Cataract accounted for 58.8% of bilateral low vision, 20.0% of bilateral blindness, and 52.0% of poor visual function (score