The Value of Intraocular Pressure Asymmetry in Diagnosing Glaucoma

PURPOSE:To investigate the amount of intraocular pressure (IOP) asymmetry in a large group of ethnically diverse patients with and without glaucoma, and to delineate the risk for glaucoma which increasing amounts of IOP asymmetry confer upon the patient. PATIENTS AND METHODS:Collaborative retrospective study of 326 glaucoma patients and 326 controls. Former Wills Eye Institute fellows collected single pre-treatment measurements of IOP on patients diagnosed as having definite glaucoma based on characteristic optic nerve damage and confirmatory visual field damage. Patients with a normal eye examination who had normal-appearing optic discs and no apparent glaucoma, or who had a normal eye examination in association with refractive error or cataract, were used as controls. RESULTS:Intraocular pressure asymmetry is a significant risk factor for having glaucoma (odds ratio, 2.14; 95% confidence interval, 1.86-2.47; P6 mm Hg with a 57% probability of having glaucoma. The association between IOP asymmetry and glaucoma status is significant for subjects with both elevated IOP (P=0.014) and statistically normal IOP (maximum IOP≤21 mm Hg; P