Optic neuritis is inflammation of the optic nerve, which lies at the back of the eye and carries visual information from the eye to the brain. Optic neuritis may cause partial or total loss of vision, usually in one eye, and is often associated with pain when the eye moves.

When optic neuritis causes partial vision loss, effects may include:

• Loss of vision in the center of the visual field (central scotoma).
• Changes in color perception, with bright colors appearing dull.

Symptoms of optic neuritis usually develop over a period of a few days to a week and stabilize for several weeks or months. In many cases vision then improves on its own. If not, steroid treatment usually is effective at relieving the inflammation.

Optic neuritis can be associated with other neurological and inflammatory conditions, such as multiple sclerosis.