Visual acuity and quantitative perimetry (Octopus Program 32) testing was performed in the acute (< 30 days after onset) and convalescent (> 3 months after onset) phases of disease in 27 patients with untreated NAION. Initial group mean acuity and sensitivity loss were compared to final values using the t test. Proportions of patients demonstrating a change of > 2 lines acuity or > 2 dB mean sensitivity were calculated. Patients were classified as either "progressive" (n = 6) or "stable" (n = 21) for purposes of additional subgroup analysis. There was no significant change in group mean visual acuity or field over time. Overall, significant worsening occurred in 11.1% for visual acuity and 22.2% for visual field; improvement occurred in 23.8% for acuity and 24.0% for field. Of 21 "stable" patients, none worsened for acuity and 4.7% showed late worsening of field; 31.3% showed significant improvement for acuity and 31.6% for field. No "progressive" patients demonstrated worsening or improvement after the initial progressive phase.