The Prevalence and Causes of Visual Impairment and Blindness in a Multi-Ethnic Asian Population: The Singapore Epidemiology of Eye Disease (SEED) Study

Abstract

Purpose: : There are few precise population-based data on racial/ethnic variations in visual impairment (VI) and the major eye diseases, particularly in Asia. We describe the prevalence and causes of blindness/VI in a multi-ethnic Asian population of Chinese, Malays and Indians in Singapore.

Methods: : The Singapore Epidemiology of Eye Disease (SEED) study comprises 3 population-based studies of Singapore-resident ethnic Malays, Indians and Chinese aged ≥40 years, examined between 2004 and 2011 using the same study protocol. An age-stratified random sample of residents residing in south-western Singapore was selected from a national database and invited to a centralized clinic for a standardized comprehensive eye assessment, including measurement of best-corrected visual acuity (VA) to determine blindness/VI rates, and the primary causes of blindness/VI. Presenting VA was also measured. Prevalence estimates were standardized to the 2010 Singapore Census.

Results: : A total of 10,016 persons (75.7% response rate), comprising 3,280 Malays, 3,400 Indians and 3,336 Chinese participated. The age-standardized prevalence of bilateral blindness (US definition, ≤20/200, better eye) was 0.3%, 0.3% and 0.4%, respectively for Malays, Indians and Chinese, and of bilateral VI (<20/40 to >20/200, better eye) was 3.9% 3.8%, and 4.6%, respectively. Across all ethnic groups, cataract was the leading cause of bilateral blindness (63.6%) and bilateral VI (77.9%). Other major causes of blindness/VI included diabetic retinopathy, age-related macular degeneration, glaucoma, corneal opacity, and myopic maculopathy. Undercorrected refractive error doubled the prevalence of VI, if presenting VA was used instead of best-corrected VA (i.e. 50% of VI cases overall).

Conclusions: : The prevalence of visual impairment was similar amongst Chinese, Indians, and Malays residents in Singapore and substantially lower than those reported in China, India and Indonesia. These data may have implications for the US and many countries where a key objective of public health system reform is to redress racial/ethnic inequality.

Keywords: clinical (human) or epidemiologic studies: prevalence/incidence