Optic neuritis progressing to multiple sclerosis.

We report a partially retrospective and longitudinal study of patients with optic neuritis (ON) that developed multiple sclerosis (MS). We assessed clinical features or factors that might differentiate these patients from those with ON that did not develop MS. Of the cases followed, 110 (67%) were found to have an idiopathic origin of the disease; whereas 55 (33%) were found to develop it secondary to another disease. Of the 110 idiopathic cases, 13 (12%), developed MS over an average of 2 years. The results of these patients in the laboratory analyses of blood and CSF as well as the results of the MRI and evoked potential studies, were significantly different from the ON patients without MS. We conclude that the percentage of patients with ON in our sample that developed MS is similar to that found in Japan and is relatively low in comparison to other reports.