Introduction In order to provide the theoretical basis and practical guidance of eye protection during the prone spinal surgery under the general anesthesia, visual evoked potential (VEP) was monitored before and after surgery. Patients and Methods A total of 82 patients were involved in our study and grouped into three groups, S, M, and L groups, respectively, according to the operation time. The P100's latency and amplitude changes and the visual function of preoperative, postanesthetic, and postoperative spots were analyzed to understand their relationship. Results (1) The waveforms of VEP in 78 cases were monitored stably and repeatedly and the other four cases failed. (2) Difference of P100's latency and amplitude at preoperative, postanesthetic time was not statistically significant in all groups. (3) Postoperatively, difference of P100's latency was statistically significant in M and L groups, and no statistically significant difference was observed in S and M groups. Difference in P100's amplitude was statistically significant in all groups. (4) Recovery time of P100's latency has statistically significant differences in all three groups. (5) Two patients in the L group had conjunctival edema, pupillary light reflex obstacles, and visual acuity descending. After receiving positive symptomatic treatment, symptoms disappeared and vision recovered. Conclusion VEP can provide the stable and on-time electrophysiological conductive evidence needed to judge the optical pathway function. The operator should pay close attention to the change in VEP and visual performance if prone spinal surgery continues for more than 4 hours.