Risk factors for the development of multiple sclerosis (MS) were determined by follow-up (mean 22 yrs) of 79 children who presented with a diagnosis of optic neuritis (ON) at the Mayo Clinic between 1950 and 1988. The incidence of MS was 13% by 10 yrs follow-up and 19% by 20 yrs. Of the patients who developed MS, 7 of 15 (47%) had symptoms within the first year after recovery from ON; one developed MS after 31 years interval. Four had clinical signs of Devic’s disease. Bilateral sequential or recurrent ON increased the risk of MS, whereas unilateral ON was associated with a low risk of MS. Of 37 children with unilateral ON, only 2 (5%) developed MS. The presence of recent infection within 2 weeks of onset of ON decreased the risk of MS. Childhood onset ON had a lower risk of progression to MS compared to ON in adults. 
COMMENT. The risk of developing multiple sclerosis after optic neuritis in childhood is lower than in adult-onset ON and increases with length of follow-up from 13% after 10 years to 22% by 30 years. Bilateral ON carries a greater risk of MS, whereas infection preceding the ON lessens the risk of MS.
In a previous report from Gottingen, Germany (Hanefeld FA, 1995), onset or relapse of MS was preceded by a nonspecific infection, usually an URI, in >50% cases. Of 8 presenting with ON, 4 developed MS within 2 years. (See Progress in Pediatric Neurology III, PNB Publ, 1997;551-554, for further articles on childhood MS).