Undiagnosed Primary Open-Angle Glaucoma in Korea: The Korean National Health and Nutrition Examination Survey 2008-2009

Purpose: To evaluate the characteristics of patients with previously undiagnosed primary open-angle glaucoma (POAG) in Korea. Methods: This study examined data from 391 subjects obtained from the 2008-2009 Korean National Health and Nutrition Examination Survey (KNHANES). The KNHANES is a population-based, cross-sectional epidemiological survey. Participants aged 19 years or older completed standardized interviews and dilated ocular examinations, including measurement of intraocular pressure, visual fields with frequency doubling perimetry, and fundus photography. Data from the 361 patients with previously undiagnosed POAG were analyzed and compared with data from the 30 patients with previously diagnosed glaucoma. Results: A total of 92.3% of POAG cases were undiagnosed before this study. Adjusted for age and sex, the strongest risk factor for undiagnosed glaucoma was longer elapsed time since last eye doctor visit. Glaucoma patients who had not visited an eye specialist in the last 3 years were 22 times (95% confidence interval, CI, 4.49-105.64, p < 0.001) more likely to have undiagnosed disease compared with patients who had visited an eye specialist in the last month. Another significant factor for previously undiagnosed glaucoma was smaller cup-to-disc ratio (odds ratio, OR, 0.60/0.1 units, 95% CI 0.43-0.85/0.1 units, p = 0.004). The higher vertical cup-to-disc ratio of a subject's two eyes was significantly different between those with previously undiagnosed (0.69) and diagnosed (0.78) POAG (p = 0.001). Conclusions: The undiagnosed POAG group had a longer interval from last eye doctor visit and smaller vertical cup-to-disc ratio compared to the diagnosed group.