Optic neuritis is inflammation of the optic nerve. It may cause sudden, reduced vision in the affected eye.
The cause of optic neuritis is unknown.
Sudden inflammation of the nerve connecting the eye and the brain (optic nerve) can cause the nerve to swell and destroy its outer shell (myelin sheath). The inflammation may occasionally be due to a viral infection, or it may be caused by autoimmune diseases such as multiple sclerosis.
Risk factors are related to the possible causes.
Germann CA, Baumann MR, Hamzavi S. Ophthalmic diagnoses in the ED: optic neuritis. Am J Emerg Med. 2007;25:834-837.