Twelve-Year Incidence, Causes, and Determinants of Visual Impairment and Visual Improvement in a Multiethnic Asian Population: The Singapore Epidemiology of Eye Diseases Study.

PURPOSE: To determine the 12-year incidence of visual impairment (VI) and visual improvement, associated risk factors and primary causes of VI in a multiethnic Asian population.

DESIGN

Population-based study.

PARTICIPANTS

Of 10 033 adults aged 40-80 years recruited at baseline from the Singapore Epidemiology of Eye Diseases (SEED) study, 5841 eligible participants were contacted for 12-year re-examination. A total of 4495 (response rate 76.96%; 1302 Malays, 1555 Indians, 1638 Chinese) attended follow-up.

METHODS

Best-corrected visual acuity (BCVA) and presenting visual acuity (PVA) were assessed at baseline and 12-year follow-up. Incident VI (low vision and blindness) was defined using US criteria based on the better-seeing eye. Age-standardized incidence rates were calculated. Visual improvement was defined as transition to a less severe VI category. Poisson regression with robust variance estimated associations between baseline factors and incident VI. Population attributable fractions (PAFs) were computed for significant determinants.

MAIN OUTCOME MEASURES: Twelve-year incidence of VI and rate of visual improvement.

RESULTS

Over 12 years, age-standardized incidence of best-corrected VI was 3.5% (95% confidence interval [CI], 2.8%-4.4%) and presenting VI was 8.1% (95% CI, 7.0%-9.4%). Incidence increased with age and was higher among women and Malay participants. Cataract was the leading cause of incident best-corrected VI (62.7%), whereas under-corrected refractive error predominated for presenting VI (46.2%). Older age (per decade, RR = 2.06), Malay ethnicity (vs Chinese, RR=2.12), diabetes (RR = 1.90), chronic kidney disease (RR = 1.70), low income (Over 12 years, the age-standardized incidence of best-corrected VI was 3.5% (95% confidence interval [CI], 2.8%-4.4%), and presenting VI was 8.1% (95% CI, 7.0%-9.4%). Incidence increased with age and was higher among women and Malay participants. Cataract was the leading cause of incident best-corrected VI (62.7%), whereas under-corrected refractive error predominated for presenting VI (46.2%). Older age (per decade, relative risk [RR] = 2.06), Malay ethnicity (vs Chinese, RR = 2.12), diabetes (RR = 1.90), chronic kidney disease (RR = 1.70), low income (<SGD$2000, RR = 2.52), and no formal education (RR = 2.14) were independently associated with incident best-corrected VI (all P ≤ 0.02). Low income contributed the largest PAF for both best-corrected and presenting VI (60.9% and 40.9%, respectively). Among participants baseline VI, visual improvement occurred in 52.0% (BCVA) and 74.5% (PVA); cataract was the commonest baseline cause among improvers.

CONCLUSIONS

In this multiethnic Asian cohort, the 12-year burden of VI is largely driven by preventable or treatable causes, particularly cataract and refractive error. A significant proportion of individuals experienced visual improvement over 12 years, highlighting the substantial reversibility of vision loss. Socioeconomic disadvantage was a major determinant of incident VI, reinforcing the need for targeted, equitable eye-care interventions to reduce avoidable vision loss in ageing populations.

FINANCIAL DISCLOSURES: The authors have no proprietary or commercial interest in any materials discussed in this article.