Several reports have suggested that nonarteritic anterior ischemic optic neuropathy (AION) may be related to increased intraocular pressure. We reviewed the records of 45 patients aged 48 through 86 years with nonarteritic AION (10 patients had bilateral AION) for intraocular pressure measurements and the diagnosis of glaucoma or suspected glaucoma. This group was compared with 45 age- and sex-matched patients with normal eye examination results. The mean +/- SD intraocular pressures were 16.3 +/- 3.3 mm Hg for 45 eyes of the 45 patients with AION and 16.1 +/- 2.8 mm Hg for 45 eyes of the 45 control patients (paired t test, P = .70). Among patients with unilateral AION, intraocular pressure was not greater in the involved eye than in the uninvolved eye. Three patients with AION had a previous diagnosis of glaucoma, while three of the control patients were being followed up with suspected glaucoma. We found no evidence in our series to support the hypothesis that AION is associated with increased intraocular pressure.