In this study the pattern-reversal stimulation was used for analysing the clinical VEP in 27 cases (37 eyes) of ischemic optic neuropathy (ION), and combined uses of visual field (VF) and contrast sensitivity (CS) examinations were compared and observed with 3 kinds of spatial frequencies (60', 30', 15' check size), VEP in the eyes of ION displayed decrease in amplitude as a dominant manifestation accompanied by the slight increase of latency period. The abnormal latency and amplitude were 83.5% and 81.3% respectively. The decreased CS in the ION eyes was appeared mainly in the stimulation of middle and high frequencies or all frequency bands. There was a significant correlation between the VEP amplitude and CS in the patients with ION. The quadrant VF defect and bow-shaped scotoma were displayed in majority of the cases. Abnormal VEP was shown to be related to the central VF impaired. Among these patients, 7 cases (8 eyes) were followed up with VEP, however the VEP amplitude was shown decreasing somewhat compared with first exam. The results indicated that the ION was responsible for many visual function damages.