Patient Portal: Non-Arteritic-Anterior Ischemic Optic Neuropathy (NAION)

Non-arteritic anterior ischemic optic neuropathy (NAION or NA-AION) is caused by decreased blood flow to the front part of the optic nerve (optic disc). It causes optic nerve swelling and sudden vision loss. NAION typically affects one eye, although the other eye sometimes suffers similar loss months or years later (there is about a 15% risk of second eye involvement within 5 years). Rarely, both eyes may be affected at the same time. The blood supply to the front of the optic nerve comes from small branches off the ophthalmic artery, which comes off of the carotid artery. Loss of the blood supply within those small branches damages the front part of the optic nerve, causing it to swell and resulting in vision loss. The swelling eventually goes away, but part of the optic nerve is permanently damaged.