Prevalence and predictors of open-angle glaucoma: results from the visual impairment project

To determine the prevalence and investigate predictors of open-angle glaucoma in Victoria, Australia.

Two-site, population-based cross-sectional study.

Permanent residents aged 40 years and older at recruitment from 1992 through 1996.

A cluster-stratified random sample of 4744 participants from two cohorts, urban and rural, participated. Participants completed a standardized interview regarding demographic, lifestyle, and medical characteristics and a dilated eye examination including measurement of intraocular pressure, visual fields, cup-to-disc ratios, and paired stereo photography of the optic discs. A consensus panel of six ophthalmologists determined glaucoma diagnosis.

Diagnosis of glaucoma (possible, probable, definite).

The prevalence of possible glaucoma cases was 1.2% (95% confidence interval [CI], 0.60, 1.7), of probable cases was 0.70% (95% CI, 0.39, 1.0), and of definite cases was 1.8% (95% CI, 1.4, 2.2). There was a significant increase in glaucoma prevalence with age across all definitions, but there was no difference in age-standardized rates between genders. A total of 60% of probable and definite glaucoma cases were undiagnosed before this study. Adjusted for age, the strongest risk factor for glaucoma was a positive family history of glaucoma (odds ratio, 3.1; 95% CI, 1.6, 5.3). Glaucoma patients who had not attended an eye care provider in the last 2 years were eight times (95% CI, 3.2, 20.4) more likely to have undiagnosed disease.

These results support the importance of the genetic or familial basis of many glaucoma cases and highlight the need to develop appropriate techniques to screen for undiagnosed disease.