Of 196 patients with anterior ischemic optic neuropathy, 169 had the nonarteritic form and 27 had the arteritic type. Visual acuities were 20/40 or better in 83 of 184 eyes with nonarteritic anterior ischemic optic neuropathy but only eight of 45 eyes with the arteritic type. We found systemic disease associations for hypertension and diabetes mellitus only for patients with nonarteritic anterior ischemic optic neuropathy who were between 45 and 64 years of age. After a mean follow-up period of five years, 92 nonarteritic patients showed no changes in the first affected eye; there was eventual involvement of the second eye in 20 patients.