AION is a disease in which the blood supply to the optic nerve becomes diminished. This causes tissue damage, swelling, and bleeding to a segment of the nerve. The portion of vision served by that nerve segment is decreased.
Vision loss is rapid and painless. Recovery of vision is partial and limited. The majority of patients maintain vision of 20/60 or better.
Risk factors include age, hypertension, hypotension, diabetes, and smoking. In addition, small and crowded optic nerves are more susceptible to AION.
Occasionally an inflammatory disorder of the blood vessels of the head may be the cause of AION. Patients with temporal arteritis usually have systemic symptoms such as headache, fever, malaise, weight loss, and scalp tenderness.
If temporal arteritis is suspected, a blood test measuring inflammation, and possibly a temporal artery biopsy may be recommended.
Polymyalgia Rheumatica (PMR)
PMR is an inflammatory disease involving the muscles and joints. Patients with PMR are at a greater risk of developing temporal arteritis.
A dilated examination of the eye is necessary to visualize the optic nerve and diagnose AION.
Fluorescein angiography is useful to confirm the diagnosis and determine the extent of nerve damage present.
Optical coherence tomography (OCT) is useful to detect thickening, swelling, or atrophy of the nerve.
Formal visual field testing may be performed to assess the damage to the field of vision.
In typical AION (not related to temporal arteritis or PMR) there is no known treatment. Aspirin or other antiplatelet medications may be recommended to decrease the likelihood of future bouts of AION, particularly in the other eye. Controlling the blood pressure, lipids, and diabetes, and smoking cessation are all useful in decreasing the risk of AION.
If Temporal Arteritis or PMR is suspected, high dose steroids may be prescribed.