Visual outcome in anterior ischemic optic neuropathy

The Ischemic Optic Neuropathy Decompression Trial (IONDT)¹ has shown that the visual acuity of untreated patients with acute non-arteritic anterior ischemic optic neuropathy (NAION) frequently improves by 3 or more lines on the NY Lighthouse chart. This aspect of the natural history of NAION was largely unrecognized and undocumented in the literature prior to this landmark study. PURPOSE: Our objective was to document the experience of our patients who developed NAION during the five years preceding the IONDT, so as to determine the extent and rate of recovery of visual acuity. METHOD: We reviewed retrospectively the spontaneous changes in the visual acuity as a function of time in all 28 patients with NAION, seen initially within four weeks of onset of visual symptoms. RESULTS: The visual acuity of 17 patients (61%) improved over the measurements obtained on their initial visit. Thirteen patients (46%) improved by one octave (ie, they doubled their angle of visual resolution). Six (21%) did not change and five (18%) worsened. Improvement usually occurred in the second month from onset of symptoms. If one considers patients whose visual acuity worsened and then recovered back to the initial acuity or better, improvement of at least one octave (from the worst visual acuity) was found to occur in 17 of 28 patients (61%) during this period. CONCLUSIONS: This retrospective study of untreated patients with non-arteritic AION seen over a five year period is in agreement with the results of the IONDT. Specifically, a large proportion of patients shows a spontaneous improvement in visual acuity. This study demonstrates that although this tendency towards spontaneous improvement was not generally appreciated, documentation of a high rate of improvement in AION was available from standard clinical series.