The clinical manifestations are highly suggestive of typical optic neuritis. MRI is the strongest predictor of the chance of developing clinically-definite MS. With no white matter signal abnormalities, the untreated 15-year risk is 25%. When there is at least one signal abnormality typical of demyelination, the risk rises to 75%. The chance of recovering normal or near-normal visual function in the affected eye after a first bout of typical optic neuritis is 85% to 90%. The chance of a recurrence of optic neuritis in either eye over the next 15 years is 30%, evenly split between the previously affected and unaffected eyes. The chance of having long term neurologic disability—including visual disability—is only 10%. Whether treatment of any kind reduces the risks of developing MS in patients with isolated optic neuritis is unsettled; treatment is not currently recommended. Once MS is diagnosed, treatment with immune-modulating drugs probably reduces the pace of the illness.