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

Purpose: To determine the prevalence and investigate predictors of open-angle glaucoma in Victoria, Australia. Design: Two-site, population-based cross-sectional study. Participants: Permanent residents aged 40 years and older at recruitment from 1992 through 1996. Methods: 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. Main Outcome Measure: Diagnosis of glaucoma (possible, probable, definite). Results: 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. Conclusions: 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.