Visual-evoked response differentiation of ischemic optic neuritis from the optic neuritis of multiple sclerosis.

Fifteen patients with ischemic optic neuritis studied electrophysiologically had a characteristic change of marked reduction in the amplitude of the visual-evoked response even when loss of vision was moderate. The optic neuritis of multiple sclerosis rarely produced this change. Occasionally, small increases in the latent period of the visual-evoked response were recorded from the patients with ischemic optic neuritis. The optic neuritis of multiple sclerosis usually produced significant increases in the latent period. When the normal nerve was tested in patients with ischemic optic neuritis, the visual evoked response was normal. In patients with optic neuritis of multiple sclerosis, stimulation of the "normal" nerve usually produced an increase in the latent period similar to that seen when the involved nerve was stimulated.