Incidence of open-angle glaucoma - The Barbados Eye Studies

Objective: To measure the 4-year risk of open-angle glaucoma (OAG) in a bla ck population. Design? Population-based cohort study with 4 years of follow-up. Setting: Simple random sample of residents of Barbados, West Indies, aged 4 0 years or older. Participants? A total of 3427 members of the cohort (85% of those eligible) . Main Outcome Measure: Development of glaucoma visual held defects and optic disc damage, confirmed by automated perimetry, independent fundus photogra phic gradings, and standardized ophthalmologic examinations. Results: The 4-year risk of OAG in black participants was 2.2% (95% confide nce interval, 1.7%-2.8%), based on 67 newly developed cases of GAG. Inciden ce rates increased from 1.2%, at ages 40 to 49 years to 4.2%, at ages of 70 years or more, tending to be higher in men than women (2.7% vs 1.9%). Abou t half of the incident cases were undiagnosed previously, and the rest were receiving OAG treatment. Of the 67 new cases of GAG, 32 had intraocular pr essure of 21 mm Hg or less at baseline (1.2% incidence) and 35 had higher p ressures (9% incidence). Risk was highest among persons classified as havin g suspect OAG at baseline (26.1%), followed by those with ocular hypertensi on (4.9%) and lowest in the remaining population (0.8%). Conclusions: This longitudinal study provides new information on OAG risk, as well as the first incidence measurement in a black population. Although intraocular pressure increased risk, about half of the new cases had baseli ne pressures of 21 mm Hg or less. Results substantiate the high OAG risk in the population of African origin, especially in older adults; the relative role of intraocular pressure; and the considerable underdetection of new d isease after 4 years of follow-up.