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

To quantify prevalence of asymmetric intraocular pressure (IOP) and assess associations with undiagnosed open-angle glaucoma.

Population-based cross-sectional study.

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.

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.

Intraocular pressure asymmetry may be a useful sign of undiagnosed glaucoma in subjects without elevated IOP.