Distribution of intraocular pressure: the Barbados Eye Study

ABSTRACT

OBJECTIVE: To provide data on the distribution of intraocular pressure (IDP) in a predominantly black population, which has a high prevalence of open-angle glaucoma. DESIGN: Population-based prevalence study. SETTING AND PARTICIPANTS: Participants (N = 4601) (age range, 40-84 years) who had undergone applanation tonometry measurements in the Barbados Eye Study. Self-reported race was 93 percent black, 4 percent mixed (black and white), and 3 percent white or other. DATA COLLECTION A standardized protocol included applanation tonometry and other ocular measurements, fundus photography, demographic data, and an interview. MAIN OUTCOME MEASURES: The average of 3 IDP measurements at the Barbados Eye Study visit was used to compare IDP by self-reported race. Descriptive data on IDP by age, sex, glaucoma status, and cup-disc ratio were examined in the black population. RESULTS: The IDP was highest in the population of African origin. The mean (+/-SD) IDP values for black, mixed, and white participants were 18.7 +/- 5.2, 18.2 +/-3.8, and 16.5 +/- 3.0 mm Hg, respectively. An IDP greater than 21 mm Hg was present in 18.4 percent, 13.6 percent and 4.6 percent of the black, mixed and white participants, respectively. In analyses that were adjusted for age, sex, and glaucoma status, such values were 5 times as likely in black than white participants and 3.5 times as likely in mixed race participants (p < .01). Among the black participants, the mean IDP increased approximately 1 mm Hg for every increase in 10 years of age. After excluding persons with any type of glaucoma, suspected glaucoma, or a history of glaucoma treatment, women had significantly (P < .01) higher IDP values; however, no significant IDP trends by sex were evident in the group with glaucoma. The IDP was also positively associated (P < .05) with vertical cup-disc ratios. After 2 visits, the IDP remained 21 mm Hg or less in 21 percent of the persons with glaucoma vs 64 percent of those without glaucoma. CONCLUSIONS: In the black participants, the IDP was higher than in the white participants. The IDP was also associated with age and cup-disc ratios. The results showed that open-angle glaucoma and a high IDP alone have a different distribution by sex; although open-angle glaucoma was more frequent in men, ocular hypertension was more frequent in women. These data have implications for the detection and causation of open-angle glaucoma in this high-risk population.(AU)