PURPOSE: To estimate the prevalence of open-angle glaucoma (OAG) in a population-based sample of subjects 60 years of age or older in Thessaloniki, Greece.DESIGN: Cross-sectional population-based study.METHODS: Subjects randomly identified from municipality registers in Thessaloniki underwent a complete ophthalmologic examination. Glaucoma was defined in two ways. Definition 1 was based on the presence of both glaucomatous optic disk and confirmed glaucomatous visual field defect. Subjects also were classified as having glaucoma when the clinical judgment was strongly in favor of the presence of glaucoma even though the strict criteria were not fulfilled (definition 2).RESULTS: Of the 3,617 eligible subjects, 2,554 (71%) participated. The prevalence of OAG was 3.8% and 5.5% by definitions 1 and 2, respectively. The prevalence of primary OAG was 2.7% and 3.8% by definitions 1 and 2, respectively, and the prevalence of pseudoexfoliation glaucoma (PEXG) was 1.1% and 1.7% by definitions 1 and 2, respectively. Pseudoexfoliation was present in 11.9% of participants, whereas 15.2% among those with pseudoexfoliation had PEXG.CONCLUSIONS: The prevalence of OAG in the Thessaloniki Eye Study (TES) is similar or slightly higher compared with other population-based studies in White persons. The overall slightly higher prevalence of OAG in the TES compared with other studies may be attributed to the high prevalence of PEXG in the TES.