Optic neuritis is inflammation of the optic nerve anywhere along its course.

• Multiples sclerosis is the most common cause.
• Loss of vision may develop, and moving the eye may hurt.
• Magnetic resonance imaging (MRI) is done.
• If multiple sclerosis seems possible, corticosteroids may be given.

Optic neuritis is most often caused by multiple sclerosis. Some people who have optic neuritis later develop multiple sclerosis. Optic neuritis may also be caused by the following:

• Infections such as viruses (especially in children), meningitis, syphilis, sinusitis, tuberculosis, and human immunodeficiency virus (HIV)
• Tumors
• Chemicals or drugs such as lead, methyl alcohol, quinine, arsenic, and certain antibiotics
• Certain autoimmune diseases such as multiple sclerosis
• Intraocular inflammation (uveitis—see Uveitis)

Rare causes include diabetes, pernicious anemia, Grave's disease, bee stings, vaccinations, and injuries. However, the cause of optic neuritis is often unknown.

Symptoms

Optic neuritis causes vision loss, which may be mild or severe and may occur in one or both eyes. Loss of vision may occur over days. Vision in the involved eye or eyes can range from almost normal to complete blindness. Color vision may be particularly affected, but the person may not realize this. There may be pain with eye movement. Depending on the cause, vision usually recovers within a few months. However, some people have repeat episodes of optic neuritis.

Diagnosis

Diagnosis involves examination of the reactions of the pupils and observing the back of the eyes with a viewing instrument (ophthalmoscope). The head of the optic nerve at the back of the eye (optic disk) may appear swollen. Testing the field of vision may reveal loss of a portion of the visual field. MRI may show evidence of multiple sclerosis or, rarely, a tumor pressing on the optic nerve.

Treatment

In some instances, such as when multiple sclerosis seems possible, corticosteroids may be given by vein. These drugs may hasten recovery and reduce the chance of a recurrence. If a tumor is pressing on the optic nerve, vision usually improves once the pressure caused by the tumor is relieved.

Last full review/revision July 2008 by James Garrity, MD