Ischemic Optic Neuropathy (AION)

A common cause of sudden vision loss where the optic nerve is deprived of oxygen

We do not see with our eyes. We see with part of our brain that is capable of interpreting visual signals sent back from the eyes. Loss of blood supply within the arteries deprives the optic nerve tissue of oxygen and results in damage to part or all of the optic nerve. This is a small “stroke” in the optic nerve but unlike other strokes is unassociated with pain, weakness, numbness, loss of speech, nor is there an increased risk of a classic stroke later.

We don’t completely understand the cause of the loss of blood supply to the optic nerve. These episodes may occur when there is a sudden drop in blood pressure (following an operation or associated with blood loss after an accident). Patients who smoke, or who have diabetes or high blood pressure, may be at higher risk for AION.

Symptoms include:

  • Decreased vision
  • Sudden vision disturbance
  • Difficulty seeing above or below the center of gaze.


Most patients with ischemic optic neuropathy will have relatively stable vision. Unfortunately, much of the visual field defect (difficulty seeing above or below) will not improve. It may, however, become less noticeable with time, especially if the other eye is normal.

Unfortunately, at this time there is no proven treatment for patients with AION. It has been suggested that aspirin (regular size or baby aspirin once a day) may decrease the chance of an episode in the opposite eye. It is important that the blood pressure be followed by your doctor.

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