Objective: To evaluate risk factors for the 4-year incidence of cortical and posterior subcapsular (PSC) lens opacities.
Design: Population-based cohort study with 85% participation at 4-year follow-up.
Participants: Three thousand one hundred ninety-three black participants of the Barbados Eye Studies, Barbados, West Indies, of whom 2040 and 2954 were free of cortical and PSC lens opacities, respectively, at baseline.
Methods: The standardized protocol at baseline and follow-up included an interview, anthropometric and blood pressure measurements, and ophthalmic measurements including slitlamp lens grading, fundus photography, and an ophthalmologic examination. Factors associated with incident cortical and PSC opacities (Lens Opacities Classification System II, > or =2) were evaluated by logistic regression. Main Outcome Measure Relative risks (RRs) with 95% confidence intervals.
Results: The 4-year incidence of cortical lens opacities was 22.2% (452/2040); the factors increasing risk were older age, female gender (RR = 1.3), low socioeconomic status (RR = 1.4), and a history of diabetes mellitus (RR = 2.4), while aspirin use was associated with a lower RR (RR = 0.2; 95% confidence interval, 0.1-0.8), a result based on small numbers. The 4-year incidence of PSC opacities was lower at 3.3% (97/2954), and risk also increased with age and a history of diabetes mellitus (RR = 2.9). A dose-response relationship was evident between incident opacities and increased levels of glycosylated hemoglobin at baseline, with the highest risk of cortical (RR = 3.60; 95% confidence interval, 2.23-5.81) and PSC (RR = 4.93; 95% confidence interval, 2.69-9.05) opacities at more than an 11.5% glycosylated hemoglobin level.
Conclusions: Diabetes mellitus and hyperglycemia are major modifiable risk factors for the development of cortical and PSC lens opacities in this African-descent population with a high rate of diabetes mellitus. Prevention and improved control of diabetes mellitus are likely to reduce the burden of cataract. The finding of a reduced incidence of cortical lens opacities in aspirin users merits further investigation, given its potential for cataract prevention.