Ischemic optic neuropathy (ION) is when blood does not flow properly to your eye’s optic nerve. When the optic nerve does not get enough oxygen or nutrition, the nerve is damaged and you lose vision, usually permanently.

If blood flow to your optic nerve is reduced, your vision will darken for a few seconds or minutes then return to normal. This is called a transient ischemic attack (TIA). This kind of attack can happen before ION begins. If you have TIA symptoms, call your ophthalmologist or primary care doctor right away. Finding and treating the problem as soon as possible can help prevent further vision loss from ION.

ION is usually treated with medication. Low vision tools and tips are important ways to make the most of your remaining vision.

If you have any questions about your eyes or your vision, speak with your ophthalmologist. He or she is committed to protecting your sight.