Nine-year incidence of open-angle glaucoma in the Barbados Eye Studies

Purpose: To determine the 9-year incidence of open-angle glaucoma (OAG) in African-descent participants of the Barbados Eye Studies. Design: Nine-year cohort study with 81% to 85% participation. Participants: Three thousand two hundred twenty-two persons without definite OAG at baseline, at risk of developing OAG at follow-up. Methods: The standardized protocol included automated perimetry and various ophthalmic measurements, with a comprehensive ophthalmologic examination for those referred. Fundus photographs were evaluated independently by masked graders. Incidence was estimated by the product-limit approach. Relative risk (RR) ratios with 95% confidence intervals (Cls) were based on Cox regression models with discrete time. Main Outcome Measure: Nine-year incidence of definite OAG, based on the development of visual field defects and glaucomatous optic neuropathy, with ophthalmologic confirmation. Results: The 9-year incidence of definite OAG was 4.4% (95% CI, 3.7%-5.2%), or an average of 0.5%/year, based on 125 new cases. Incidence increased greatly with age, from 2.2% at ages 40 to 49 years to 7.9% at ages 70 years or older, and tended to be higher in men than women (4.9% vs. 4.1 %; RR, 1.3; 95% CI, 0.9-1.8). More than half (53%) of new cases were undetected, and of these, one third had intraocular pressure of 21 mmHg or less. When 141 persons developing suspected/probable OAG were considered, the total incidence was 9.4% (8.4%-10.6%), averaging approximately 1 %/year, also increasing with age, and significantly higher in men than women (10.7% vs. 8.6%; RR, 1.31; 95% CI, 1.02-1.67). Conclusions: These new data provide a measure of the long-term risk of OAG in an African-descent population, which is markedly higher than in persons of European ancestry. Results confirm the increased risk with age and in men. The incidence data fill a gap in our understanding of OAG risk and have implications for public health policy and planning; they also will allow the study of factors related to the risk of OAG development.