Ischemic Optic Neuropathy
What is ischemic optic neuropathy?
Ischemic optic neuropathy (ION) causes a sudden loss of vision because of poor blood flow to the optic nerve. The optic nerve carries the message of sight from the eye to the brain. Central vision or peripheral vision or both may be affected.
What are the symptoms of ION?
Sudden loss of central or side vision is the most common symptom. You may notice loss of side vision in the lower half of reading vision. Vision loss is usually at its worst when first noticed and in most eyes permanently remains at this level. In a few eyes, vision either progressively worsen or improve over days to weeks. ION may be considered a stroke of the optic nerve. It generally does not cause any other symptoms, such as pain or double vision. The risk of brain stroke is no greater for people with ION. People who may have temporal arteritis, one cause of ION, notice headaches and tenderness in the temple. Joint aches and pains commonly affect the shoulders and hips of people with this blood vessel disorder. They may also feel tired, run a fever, experience weight loss, have poor appetite and have pain associated with chewing food.
How is ION diagnosed?
Your ophthalmologist will perform a complete eye examination, including pupil dilation. Decreased blood flow usually results in swelling of the optic nerve, which your ophthalmologist can see when examining your eye. A test of side vision (visual field) may also be performed. Your doctor may recommend a check of blood pressure or a blood test for diabetes. In addition, a blood test and/or biopsy of an artery in the temple to diagnose temporal arteritis may be required.
What causes ION?
The most common type of ION occurs in individuals over 40 years of age and is usually not related to other illness. It is caused by poor blood supply to the optic nerve, usually associated with a “crowded” or small optic nerve. ION may be more common in people with diabetes or high blood pressure. A less common type of ION occurring in people over 60 years of age is temporal arteritis. This disease is an inflammation of certain arteries, including those in the eye. Rarely, ION can occur after loss of large amounts of blood.
Can ION be treated?
ION has no proven treatment. There is about a 50% risk that the other eye will develop ION. There is no treatment to improve vision. However, many patients will spontaneously experience some improvement of their vision over time. Patients with ION caused by temporal arteritis (inflammation and damage to the blood vessels that supply blood to the head) have a very high chance of the other eye being affected unless treated with steroids (cortisone). The purpose of steroids is to “prevent” ION in the other eye but this treatment rarely improves vision which is lost in the first eye.
What will happen to my vision?
Unfortunately, with either type of ION, vision loss is usually permanent. For those with severe vision loss in both eyes, often some side vision is preserved. This side vision generally allows you enough sight to function at home independently. Special visual devices are available which can help you to continue many daily activities.