Objective To observe the results of multifocal visual evoked potential (mfVEP) examination in patients with anterior ischemic optic neuropathy (AION) before and ater treatment, and to probe its clinical significance. Methods A total of 90 patients (90 eyes) with AION were examined by mfVEP; the secondorder reaction of mfVEP was analyzed.The reaction was divided into upper and lower hemi field of visual field, or 1/4 quadrant visual field (superior nasal, inferior nasal, superior temporal, and inferior temporal). The sum of waves of each response was analyzed and the results in various regions were compared.The features of wave configuration was compared between the AION eyes and the contralateral eye, and between the AION eyes before and after treatment.Results The amplitude and latency of P-wave of mfVEP was 0.198plusmn;0.033 and 100.197plusmn;7.354 respectively in AION eyes before treatment, and was 0.271plusmn;0.024 and 98.567plusmn;6.794 in the contralateral eyes; the difference was significant (t=16.556,18.330; Plt;0.01). The amplitude and latency of P-wave of mfVEP was 0.229plusmn;0.016 and 100.104plusmn;10.603 respectively in AION eyes after treatment, which differed much from that before the treatment (t=13.649, 8.858; Plt;0.01) and also from that of the contralateral eyes (t=13.649，8.858；P＜0.01). ConclusionsThe amplitude and latency of P-wave of mfVEP may accurately reflect the recovery of local optic nerve damage in AION eyes before and after treatment with good repeatability. AION can be used as a new method for AION diagnosis and detection of the prognosis.