Optic Neuritis
Optic neuritis occurs when inflammation and demyelination affect the optic nerve. The optic nerve works to communicate sensory information from the eye to the brain.
Optic neuritis may affect one or both of the eyes. Its symptoms include changes in vision and eye pain.
It is unclear what causes optic neuritis. Experts often link the condition with MS, with the condition according to one 2016 paper — occurring in about 50% of people with MS. The same paper states that it may also be an initial MS symptom in about 20% of individuals.
Optic neuritis is also more likely to occur in people with viral infections, such as mumps, measles, and the flu.