Optic Neuritis: The Role of Disease-modifying Therapy in This Clinically Isolated Syndrome

Optic neuritis (ON) is an important clinical entity, which may herald the diagnosis of multiple sclerosis (MS). Patients with acute monosymptomatic ON generally have a good visual prognosis, and the speed of recovery may be hastened with intravenous methylprednisolone. The question of whether disease-modifying therapy should be initiated after ON as a clinically isolated syndrome is a controversial topic, and factors specific to the patient should be taken into consideration before weighing in favor or against this therapeutic option. A significant proportion of patients with ON will go on to develop MS, and early initiation of therapy may delay this diagnosis. In addition, disease-modifying therapies also may reduce the disabling effects of MS among patients, but this is unknown. There are approved therapies currently available for patients with ON and an abnormal baseline cranial MRI scan, which predict a greater risk of future MS. Patients with a higher baseline MRI burden of disease, multifocal symptomatology (including sensory complaints) at onset, a high relapse rate, and a rapid accumulation of disability within the first few years of diagnosis may benefit from early and aggressive therapy with the disease-modifying drugs that are currently available. ON patients with few or no lesions on their baseline MRI scans and those with low rates of clinical relapse may be selected for careful clinical follow-up and monitored for signs of disease activity before the role of disease-modifying therapy is determined. ON patients with no light perception vision at presentation, marked optic disc swelling, and other atypical clinical features (including peripapillary hemorrhages or retinal exudates) may have a reduced risk of future MS, and for these patients, disease-modifying therapy may be deferred until it is deemed necessary by the patient and the treating physician.