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August 1997

Distribution of Intraocular Pressure: The Barbados Eye Study

Author Affiliations

From the Department of Preventive Medicine, University Medical Center at Stony Brook, Stony Brook, NY (Drs Leske and Hyman and Ms Wu), the Ministry of Health, Barbados, West Indies (Dr Connell), and the Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, Md (Dr Schachat).

Arch Ophthalmol. 1997;115(8):1051-1057. doi:10.1001/archopht.1997.01100160221012

Objective:  To provide data on the distribution of intraocular pressure (IOP) 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% black, 4% mixed (black and white), and 3% 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 IOP measurements at the Barbados Eye Study visit was used to compare IOP by self-reported race. Descriptive data on IOP by age, sex, glaucoma status, and cup-disc ratio were examined in the black population.

Results:  The IOP was highest in the population of African origin. The mean (±SD) IOP 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 IOP greater than 21 mm Hg was present in 18.4%, 13.6%, and 4.6% 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 IOP 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 IOP values; however, no significant IOP trends by sex were evident in the group with glaucoma. The IOP was also positively associated (P<.05) with vertical cup-disc ratios. After 2 visits, the IOP remained 21 mm Hg or less in 21% of the persons with glaucoma vs 64% of those without glaucoma.

Conclusions:  In the black participants, the IOP was higher than in the white participants. The IOP was also associated with age and cup-disc ratios. The results showed that open-angle glaucoma and a high IOP 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.