Optic neuritis is inflammation of the optic nerve.
Optic neuritis is most common among adults aged 20 to 40 years. Optic neuritis is most often caused by multiple sclerosis (see Multiple Sclerosis (MS)). However, some people who have optic neuritis are found only later to have multiple sclerosis. Optic neuritis may also be caused by the following:
Rare causes include diabetes, pernicious anemia, certain autoimmune diseases, Graves disease that affects the orbit (called Graves orbitopathy), bee stings, and injuries. However, the cause of optic neuritis is often unknown.
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 but not always completely. Some people have repeat episodes of optic neuritis.
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. MRI may show evidence of multiple sclerosis or, rarely, a tumor pressing on the optic nerve.
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. After a few days, corticosteroids are given by mouth.
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 (low-vision aids) may help people with loss of vision.
Last full review/revision October 2014 by James Garrity, MD