The natural history of optic neuritis.

Optic neuritis is a common cause of visual loss in young patients, typically presenting with painful monocular visual loss and decreased color vision. Visual function generally spontaneously improves over weeks, and 95% of patients return to visual acuity of at least 20/40 within 12 months. The initial magnetic resonance imaging (MRI) helps stratify the risk of multiple sclerosis (MS) in patients with acute isolated optic neuritis. In the Optic Neuritis Treatment Trial, the 10-year risk of MS in the group of patients with at least one MRI T2 lesion was 56%, whereas the 10-year risk with a normal baseline MRI was 22%. A normal MRI in concert with painless optic neuritis, severe optic nerve head edema, peripapillary hemorrhages, or a macular star defines a very low MS risk subgroup. High-dose steroids hasten the rate, but not the final extent, of visual recovery in optic neuritis, and the decision to use this therapy is individualized. Interferon beta-1a therapy should be considered in selected high-risk patients.