Optic Neuritis: Treatment and Follow-Up
The most important study of patients with optic neuritis is termed the Optic Neuritis Treatment Trial. This was a large trial carried out between 1988 and 1991 of 454 patients with acute optic neuritis. This study made important contributions to both the treatment of optic neuritis and the prognosis for MS in patients with MS. As a result of this study, optic neuritis is typically treated with a 3-day course of IV steroids, usually Solumedrol 1 gram, followed by an oral prednisone taper for 11 days. This treatment regimen was found to be superior to both placebo and oral steroids. Treatment of optic neuritis with steroids hastens the speed at which patients recover their vision. However it does not clearly have a long-term impact on overall visual acuity or the possible progression of optic neuritis to MS.
Many patients with optic neuritis go on to develop MS, though many do not. Of course, the longer patients with optic neuritis are tracked, the more go on to have a second episode of demyelination such that they can be diagnosed with MS. After 15 years, about half of the patients with optic neuritis had gone on to develop MS. Fortunately, we have some idea of who is at risk for developing MS and who is not. The probability of a patient developing MS is directly related to the number of white matter lesions on MRI. After 15 years of follow-up, only 25% of patients with a normal MRI developed MS. In contrast, 72% of patients with even one lesion went on to develop MS. Among patients without lesions on MRI, male patients, patients with swelling of the optic disc and those with certain atypical features of optic neuritis had the lowest risk of developing MS.
The decision about when a patient with optic neuritis should begin treatment for multiple sclerosis can be quite difficult. If a patient has numerous lesions on their brain typical for MS then most neurologists (though not all) would suggest that patients start treatment with one of the disease modifying drugs to try to prevent or delay conversion to MS. Patients with a normal brain MRI occupy somewhat of a gray zone. After all, is it worth it to start a costly, partially effective medication with potentially significant side effects in such patients? Remember that after 15 years, half of them will not convert to clinically-definite MS. There is no right answer to this question and it is up to doctors and patients together to figure out a treatment plan they are comfortable with. Certainly it is advisable to patients who elect not to start medications to have periodic MRIs to screen for the development of lesions that suggest they are at risk for developing MS.