Optic Neuritis: pathophysiology, clinical features, and management

Optic Neuritis (ON) is an inflammatory disease of the optic nerve. The inflammation can be due to primary demyelination as part of disease spectrum that includes multiple sclerosis (MS) (typical ON) or inflammation and demyelination secondary to other causes (atypical ON). In cases of both typical MS-associated and isolated ON, the cause is presumed to be an inflammatory autoimmune reaction, resulting in demyelination of the optic nerve. The trigger for these autoimmune mechanisms is uncertain; however, attention is focused on an external factor (such as a virus) initiating events in susceptible individuals. Optic perineuritis is an uncommon variety of orbital inflammatory disease that involves the optic nerve sheath; most cases are isolated or idiopathic. If an inflammatory lesion affects the optic chiasm, the terms "optic chiasmal neuritis" or "chiasmitis" are used. This is distinguishable from bilateral simultaneous ON by a preferential involvement of the bitemporal visual fields. Treatment with corticosteroids in the setting of ON reportedly results in a more rapid recovery of visual function; however, it has also been reported that there was no difference in visual outcome by 6-12 months.