The exact cause of optic neuritis is unknown.

The optic nerve carries visual information from your eye to the brain. The nerve can swell when it becomes inflamed. The swelling can damage nerve fibers. This can cause short or long-term loss of vision.

Conditions that have been linked with optic neuritis include:

• Autoimmune diseases, including lupus, sarcoidosis, and Behçet disease
• Cryptococcosis, a fungal infection
• Bacterial infections, including tuberculosis, syphilis, Lyme disease, and meningitis
• Viral infections, including viral encephalitis, measles, rubella, chickenpox, herpes zoster, mumps, and mononucleosis
• Respiratory infections, including mycoplasma pneumonia and other common upper respiratory tract infections
• Multiple sclerosis

Symptoms may include:

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

A complete medical exam can help rule out related diseases. Tests may include:

• Color vision testing
• MRI of the brain, including special images of the optic nerve
• Visual acuity testing
• Visual field testing
• Examination of the optic disc using indirect ophthalmoscopy

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

Corticosteroids given through a vein (IV) or taken by mouth (oral) may speed up recovery. However, the final vision is no better with steroids than without. Oral steroids may actually increase the chance of recurrence.

If tests suggest that there is also multiple sclerosis, other types of treatment may be helpful.

Further tests may be needed to try to find the cause of the neuritis. If there is a condition causing the problem, it may be able to be treated.

When optic neuritis occurs without other diseases, there is a better prognosis. An MRI is an important test because it can help predict if multiple sclerosis or other similar autoimmune diseases are present or may develop.

Optic neuritis caused by multiple sclerosis or other autoimmune diseases has a poorer outlook. However, vision in the affected eye may still return to normal.

Complications may include:

• Body-wide side effects from corticosteroids
• Vision loss

Some people who have an episode of optic neuritis will develop nerve problems in other places in the body or develop multiple sclerosis.

Contact your health care provider right away if you have a sudden loss of vision in one eye, especially if you have eye pain.

If you have been diagnosed with optic neuritis, contact your provider if:

• Your vision decreases.
• The pain in the eye gets worse.
• Your symptoms do not improve within 2 to 3 weeks.

Retro-bulbar neuritis; Multiple sclerosis - optic neuritis; Optic nerve - optic neuritis

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Updated by: Audrey Tai, DO, MS, Athena Eye Care, Mission Viejo, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.