Pattern VEP in two immunochemical subtypes of optic neuritis.

Visual functions and visual evoked potentials (VEP) were compared in 2 groups of patients with optic neuritis (ON). The subdivision was based on the occurrence of oligoclonal IgG in the cerebrospinal fluid in some patients [the ON (+) group] but not in others [the ON (-) group]. At the onset of ON there were no other signs of neurological disease in these patients. Later the majority of those in the ON (+) group had developed multiple sclerosis but only one patient in the ON (-) group. Recovery after the acute optic inflammation was the same in both groups with respect to visual acuity and fields, but better in the ON (-) than in the ON (+) group with respect to colour vision and pattern VEP. A closer correlation between colour vision defects and VEP latency changes was found for the ON (+) than the ON (-) group, suggesting demyelinating disease as a more probable cause of the optic nerve inflammation in the former than in the latter group.