Nonarteritic Anterior Ischemic Optic Neuropathy

Objective To investigate systematically the natural history of visual outcome in nonarteritic anterior ischemic optic neuropathy (NAION). Design Cohort study. Participants Three hundred forty consecutive untreated patients (386 eyes) with NAION, first seen in our clinic from 1973 to 2000. Methods At first visit, all patients gave a detailed ophthalmic and medical history and underwent a comprehensive ophthalmic evaluation. Visual evaluation was done by recording visual acuity, using the Snellen visual acuity chart, and visual fields with a Goldmann perimeter. The same ophthalmic evaluation was performed at each follow-up visit. Main Outcome Measures Natural history of visual acuity and visual field outcome in NAION. Results Of the 386 eyes, 332 had 8 weeks or more of follow-up from the initial visit. At the initial visit, in eyes seen ≤2 weeks from onset of symptoms, 49% had visual acuity of ≥20/30 and 23% had ≤20/200; in these eyes, 38% had minimal to mild visual field defect and 43% marked to severe defect. In those who were first seen ≤2 weeks after onset with visual acuity ≤20/70, there was improvement in 41% at 6 months and in 42% at 1 year after the initial visit. Two years after the initial visit, there was deterioration in 9% of eyes with initial visual acuity of ≥20/60, and in 18% of those with initial visual acuity of ≤20/70. In those who were first seen ≤2 weeks of onset with moderate to severe visual field defect, there was improvement in 26% at 6 months and 27% at 1 year after the initial visit. Two years after the initial visit, 27% of eyes with initial minimal to mild field defects showed worsening, as did 19% of those with moderate to severe defects. Conclusions About half of the eyes with NAION presented with almost normal visual acuity (20/15 to 20/30) at the initial visit. Thus, the presence of normal visual acuity does not rule out NAION. Visual acuity and visual fields showed improvement or further deterioration mainly up to 6 months, with no significant change after that.