Recent advances in the treatment of central retinal artery occlusion (CRAO) have resulted in a relatively good prognosis, but few studies have been reported. In the present study, electroretinography (ERG) was used to evaluate visual function recovery in 15 cases of CRAO. All patients were treated with ocular massage, intravenous urokinase and hyperbaric oxygenation. Of 15 cases, 8 had improved vision after treatment. A single flash ERG of 40 J from a xenon lamp was recorded before and during treatment. For ERG evaluation, the a- and b-wave amplitudes and the b/a wave amplitude ratio were analyzed. As control, the nonaffected eye of each patient was used. Before treatment, no significant difference was found in the a-wave amplitude between the two eyes, while a significant attenuation was found in the b-wave of the affected eye (p < 0.01). The b/a ratio was 0.73 +/- 0.04 (mean +/- SE) in the affected eye group and 1.08 +/- 0.03 in the nonaffected eye group. It was significantly higher (p < 0.01) in eyes with improved visual acuity (0.83 +/- 0.03) than in those with unimproved visual acuity (0.62 +/- 0.05). The b-wave amplitude increased in accordance with visual improvement. We could thus demonstrate the temporal changes of ERG before and after treatment and show their correlation with the visual prognosis in patients with CRAO.