Optic neuritis is an acute inflammatory optic neuropathy. It is the most common type of optic neuropathy which causes acute visual loss in young to middle-aged adults. Usual symptoms are acute reduction of visual acuity, pain (especially with eye movements), and papilledema. (1)

In a ten-year study of 388 patients who experienced acute optic neuritis, it was noted that the ten-year risk of developing multiple sclerosis was 38%. Patients who had one or more typical lesions for MS on the MRI of the brain had 56% risk, and those without such lesions had 22% risk. Among the patients with no typical MS lesions on the MRI of the brain, male gender, optic disc swelling, perpapillary hemorrhages, and retinal exudates were associated with a lower risk of developing MS. (2)

Another major cause of optic neuritis is acute disseminated encephalomyelitis (ADEM). ADEM is a post-infectious inflammatory process, mediated by auto-reactive immune cells or antibodies. It has been noted that bilateral optic neuritis and transverse myelitis are particularly suggestive of ADEM. (3)