Most people recover well from ON. In approximately 80 percent of individuals, vision tends to recover by itself starting within 2–3 weeks from the onset of symptoms, usually stabilizing over months and continuing to improve for up to 1 year. According to a large clinical trial (the Optic Neuritis Treatment Trial), 1 year after the initial ON attack, 93 percent those diagnosed with ON had a visual acuity of 20/40 and 69 percent had visual acuity of 20/20. Additionally, the severity of initial visual loss does seem to affect final visual outcome and the best predictor of visual recovery is the baseline acuity at the time of the attack. On average, visual function is worse when ON is an early presentation of MS.
Even though recurrences of ON can occur, the long-term outcome remains good. ON can recur either in the same or the contralateral eye. After ten years of follow-up in the previously mentioned Optic Neuritis Treatment Trial, 35 percent of participants experienced at least one documented recurrence. Long-term follow-up studies have shown that only two percent are left with significant visual impairment in both eyes. Not surprisingly, recurrence is more common in those who are later diagnosed with MS.
In some cases, where there is no response to steroids (either intravenous or oral), plasma exchange is considered as a therapy. Long term immunomodulation and MS therapies (interferon beta-1a and interferon beta-1b) can be used to delay the progression or onset of MS in individuals who are likely to be diagnosed as MS.