Intraocular pressure asymmetry and undiagnosed open-angle glaucoma in an older population

PURPOSE: To quantify prevalence of asymmetric intraocular pressure (IOP) and assess associations with undiagnosed open-angle glaucoma. DESIGN: Population-based cross-sectional study. METHODS: Participants underwent applanation tonometry. Intraocular pressure asymmetry was defined for differences > or = 3 mm Hg; open-angle glaucoma was diagnosed if glaucomatous optic disk and field changes were congruous. Analyses excluded subjects using glaucoma medication, known glaucoma, pseudoexfoliation, and cataract surgery. RESULTS: Intraocular pressure asymmetry was present in 5.1% of subjects and was greater for patients older than 70 years (6.2%). Of subjects with maximum IOP > 21 mm Hg, IOP asymmetry was present in 41.1%. Undiagnosed open-angle glaucoma was more frequent among subjects with (4.8%) than without (1.2%) IOP asymmetry. This relationship remained significant for maximum IOP < or = 21 mm Hg. CONCLUSIONS: Intraocular pressure asymmetry may be a useful sign of undiagnosed glaucoma in subjects without elevated IOP.