Optic neuritis is inflammation of the optic nerve.

• Multiple sclerosis is the most common cause.
• Loss of vision may develop, and there may be pain with eye movement.
• Magnetic resonance imaging is done.
• If multiple sclerosis seems possible, corticosteroids may be given.

Causes

Optic neuritis is most common among adults aged 20 to 40 years. Optic neuritis is most often caused by multiple sclerosis. However, some people who have optic neuritis are found only later to have multiple sclerosis. Optic neuritis may also be caused by the following:

• Infections such as viral encephalitis (especially in children), meningitis, syphilis, sinusitis, tuberculosis, and human immunodeficiency virus (HIV)
• Tumors
• Chemicals or drugs such as lead, methyl alcohol, quinineSome Trade Names
  QUALAQUIN
  , arsenic, and certain antibiotics

Rare causes include diabetes, pernicious anemia, certain autoimmune diseases, Graves disease, bee stings, 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 increase over 1 or 2 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 it. There may be pain with eye movement. Depending on the cause, vision usually returns within 2 to 3 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 light with magnifying lenses (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. Magnetic resonance imaging (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. Magnifiers, large-print devices, and talking watches may help people with loss of vision.

Last full review/revision November 2012 by James Garrity, MD