Incidence of open-angle glaucoma. The Barbados Eye studies

ABSTRACT

OBJECTIVE: To measure the 4-year risk of open-angle glaucoma (OAG) in a black population. DESIGN: Population-based cohort study with 4 years of follow up. SETTING: Simple random sample of residents of Barbados, West Indies, aged 40 years or older. PARTICIPANTS: A total of 3427 members of the cohort (85 percent of those eligible). MAIN OUTCOME MEASURE: Development of glaucoma visual field defects and optic disc damage, confirmed by automated perimetry, independent fundus photographic gradings, and standardized opthalmologic examinations. RESULTS: The 4-year risk of OAG in black participants was 2.2 percent (95 percent confidence interval, 1.7 percent-2.8 percent), based on 67 newly developed cases of OAG. Incidence rates increased from 1.2 percent at ages 40 to 49 years to 4.2 percent at ages of 70 years or more, tending to be higher in men than women (2.7 percent vs 1.9 percent). About half of the incident cases were undiagnosed previously, and the rest were receiving OAG treatment. Of the 67 new cases of OAG, 32 had intraocular pressure of 21 mm HG or less at baseline (1.2 percent incidence) and 35 had higher pressures (9 percent incidence). Risk was the highest among persons classified as having suspect OAG at baseline (26.1 percent), followed by those with ocular hypertension (4.9 percent and lowest in the remining population (0.8 percent). 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 baseline 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 underdetecion of new disease after 4 years of follow-up. (AU)