Optic neuritis is inflammation of the optic nerve. It may cause sudden, reduced vision in the affected eye.

Causes

The cause of optic neuritis is unknown.

Sudden inflammation of the nerve connecting the eye and the brain (optic nerve) can injure the insulation (myelin sheath) surrounding each nerve fiber, causing the nerve to swell.

Causes of the inflammation can include:

• Autoimmune diseases (systemic lupus erythematosus, sarcoidosis, Behcet disease, autoimmune optic neuritis)
• Infections (tuberculosis, syphilis, Lyme disease, meningitis, viral encephalitis, and post-infectious measles, rubella, chickenpox, herpes zoster, mumps, and Mycoplasma pneumonia or other common upper respiratory tract infections)
• Multiple sclerosis (most often in adults, but also in children)
• Toxicity from drugs such as methanol or ethambutol
• Vitamin B-12 deficiency

Risk factors are related to the particular cause.

Symptoms

• Loss of vision in one eye, over the course of an hour or a few hours
• Changes in the way the pupil reacts to bright light
• Loss of color vision
• Pain when you move the eye

Exams and Tests

A complete medical examination can help rule out related diseases. Tests may include the following:

• Color vision testing
• MRI of the brain including special images of the optic nerve
• Visual acuity testing
• Visualization of the optic disc by indirect ophthalmoscopy

Treatment

Vision often returns to normal within 2 - 3 weeks with no treatment.

Corticosteroids given through a vein (IV) may speed up recovery. Higher doses should be used cautiously, as they can have serious side effects.

Further tests may be needed to determine the cause of the neuritis. The condition causing the problem can then be treated.

Outlook (Prognosis)

People who have optic neuritis without a disease such as multiple sclerosis have a good chance of recovery.

Optic neuritis caused by multiple sclerosis or other autoimmune diseases such as systemic lupus erythematosus has a poorer outlook, although vision in the affected eye may still return to normal.

Possible Complications

• Body-wide side effects from corticosteroids
• Vision loss

About 20% of patients with a first episode of optic neuritis will develop myelin sheath inflammation at other sites or will develop multiple sclerosis.

When to Contact a Medical Professional

Call your health care provider immediately if you have a sudden loss of vision in one eye.

If you have optic neuritis, call your health care provider if:

• Your vision decreases
• You develop pain in the eye
• Your symptoms do not improve with treatment

Alternative Names