Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION)

What is non-arteritic anterior ischemic optic neuropathy (NAION)?

NAION is a form of anterior ischemic optic neuropathy (AION), which is an eye disease that causes a sudden loss of vision by interrupting blood flow to the front of the optic nerve. The optic nerve sends visual information from the eye to the brain, which turns that information into images. The more the optic nerve is damaged, the greater the vision loss will be. This disease is classified as NAION if it is “non-arteritic,” meaning it is not caused by inflammation in the arteries. NAION mostly affects people over the age of 50, but it is possible for anyone to develop the condition. It affects men and women equally.

What are the symptoms of NAION?

The major symptom is rapid, painless loss of vision in one eye, usually after waking up. It can occur over the span of a few hours to a few days. Vision loss is usually permanent, but some recovery may occur within the first few weeks or months. Most patients with NAION do not have any other symptoms, but some report pain and headaches.

What causes NAION?

Since NAION is non-arteritic, meaning it is not caused by inflammation in the arteries, it is instead caused by a variety of other things, including the following:

• A high drop in blood pressure that leads to decreased blood supply to the optic nerve
• Increased pressure inside the eyeball
• Narrowed arteries
• Increased blood thickness
• Decreased blood flow to the optic nerve at the back of the eye

The exact mechanism causing NAION is not yet known, but it does have several risk factors, including: high blood pressure, diabetes, sleep apnea, smoking, high cholesterol, heart disease, blocked arteries, anemia, sudden drops in blood pressure, and inflammation of blood vessels (vasculitis).

How is NAION diagnosed?

NAION is diagnosed using the following procedures:

• Thorough recording of patient history
• Eye and vision exams
• Measurement of blood pressure
• Blood work

In most diagnoses, doctors will notice a swelling of the optic nerve in the back of the eye.

What are the treatments for NAION?

There are currently no major treatments for NAION. The main focus of treatment is on the various risk factors that help trigger NAION. This may help prevent additional vision loss and help control the condition.

Where can I find out more about NAION?

• Cleveland Clinic
• Brigham and Women’s Hospital
• NIH