Optic neuritis is one of the most important causes of visual loss in young and middle aged adults. The prognosis in terms of functional outcome is good. The diagnosis of optic neuritis is a clinical one. Steroids can shorten the recovery time but do not change the long term functional outcome. The MRI is the most important investiga- tion to assess an associated risk of multiple sclerosis. Optic cohe- rence tomography (OCT) contribute additional details to course and functional outcome of optic neuritis. In the future the OCT may additionally contribute to the relationship between optic neuritis and possible associated multiple sclerosis.