Mechanism of delayed conduction of fellow eyes in patients with optic neuritis.

To test the hypothesis that latency delay in the fellow eyes of optic neuritis (ON) patients and to compensate for delayed transmission of visual information, latency change of multi-focal visual evoked potential (mfVEP) traces in fellow eyes of 15 ON patients were analyzed. Patients with low risk (LR) for developing multiple sclerosis (MS) were examined separately from MS patients to isolate effect of cortical plasticity from potential pathological changes in disseminated disease. The small increase in latency in fellow eyes of LR group was statistically not significant. In MS patients, the latency was significantly delayed ( P <0.02). The magnitude of the latency change in the fellow eyes did not correlate with the severity of latency delay in the affected eyes ( R ² <0.02, P =0.3). The differences between ON patients with and without MS, reported here, suggest that the presence of disseminated disease plays critical role in latency delay of the fellow eye.