[Electrophysiological influences of gamma knife at different doses on the compressed cat optic nerve]

To investigate the electrophysiological influences of gamma knife at different doses on the compressed cat optic nerve.

Model of compressed optic nerve was established in 20 cats. Two months later, the 20 cats were randomly divided into 5 equal groups. Four groups accepted the irradiation of gamma knife at the dose of 10, 11, 12, and 13 Gy respectively. One group was used as controls. Pattern visual evoked potential examination was used 3 days, 1 week, half a month, and 1, 2, 3, 4, and 5 months after the beginning of irradiation.

Electrophysiological changes could be observed 1 week later began to recover half a month later and then gradually recovered to normal with the lapse of time. Irreversible electrophysiological changes were observed in the groups undergoing gamma knife at the doses of 11 Gy and over, and these changes aggravated with the lapse of time.

10 Gy is the minimum dose of gamma knife that cause beneficial electrophysiological changes in the compressed cat optic nerves. The minimum dose that causes irreversible damage is 11 Gy.