What Is Optic Neuritis?

Optic neuritis is swelling of the eye’s optic nerve. The optic nerve carries light signals from the back of your eye to your brain so you can see. If the optic nerve is swollen, damaged or infected, you cannot see clearly.

Doctors do not know for sure what causes optic neuritis. This condition may be caused by the body’s immune system attacking optic nerve tissue by mistake. It seems more likely to happen in people who have had viral problems like mumps, measles, flu or multiple sclerosis, among others.