Ischemic optic neuropathy is damage of the optic nerve caused by a blockage of its blood supply.

• Blockage can occur with or without inflammation of the arteries (typically in association with a disorder called temporal arteritis)
• Vision may suddenly deteriorate.
• People with temporal arteritis may have pain when combing their hair and when chewing, generalized muscle aches and pains, fatigue, or a combination.
• Blood tests and sometimes removal of a piece of the artery (biopsy) are done to diagnose temporal arteritis.
• Temporal arteritis is treated with corticosteroids.

Causes

Blockage of the blood supply to the part of the optic nerve within the eye can lead to impaired function of optic nerve cells. Two types can occur: nonarteritic and arteritic.

Nonarteritic ischemic optic neuropathy usually occurs in people older than 50. Risk factors include high blood pressure, diabetes, and atherosclerosis. Rarely, it occurs in younger people with severe migraines. Arteritic ischemic optic neuropathy usually occurs in people older than 70. The blood supply to the optic nerve is blocked due to inflammation of the arteries (arteritis), most notably temporal arteritis (giant cell arteritis—see Vasculitic Disorders: Giant Cell Arteritis).

Symptoms

Loss of vision may be rapid (over minutes, hours, or sometimes days). Depending on the cause, vision may be impaired in one or both eyes. Vision in the involved eye or eyes can range from almost normal to complete blindness. A small area of vision loss at the center of the visual field slowly enlarges and can progress to complete blindness. People with temporal arteritis tend to be older, and their loss of vision tends to be more severe. They may have pain when they chew, muscle aches and pains, and pain when they comb their hair.

About 40% of people with nonarteritic ischemic optic neuropathy spontaneously improve over time. In this condition, repeat episodes in the same eye are extremely rare. Involvement of the other eye is estimated to occur in about 20% of affected people over the next 5 years.

In people with arteritic ischemic optic neuropathy caused by temporal arteritis, loss of vision in the other eye occurs in 25 to 50% of people within days to weeks if treatment is not started.

Diagnosis

Diagnosis involves examination of the back of the eyes with a viewing instrument (ophthalmoscope). Determining the cause involves determining whether the person has any of the disorders known to be risk factors.

If temporal arteritis is suspected as a cause, blood tests and removal and examination of a temporal artery tissue sample under a microscope (biopsy) may be done to confirm the diagnosis. If a person has no symptoms of temporal arteritis, magnetic resonance imaging (MRI) or computed tomography (CT) of the brain may be done to make sure the optic nerve is not being compressed by a tumor.

Treatment

In people with nonarteritic ischemic optic neuropathy, treatment involves controlling blood pressure, diabetes, and other factors that affect the blood supply to the optic nerve. In people with arteritic ischemic optic neuropathy caused by temporal arteritis, high doses of corticosteroids are given to prevent loss of vision in the other eye. The role of aspirin in preventing involvement of the other eye is being investigated, although at this time there is no evidence to support its use.

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