Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION)

Patient Experience

  • Reference Number: HEY1424-2023
  • Departments: Ophthalmology Department
  • Last Updated: 1 November 2023


This leaflet has been produced to give you general information. Most of your questions should be answered by this leaflet. It is not intended to replace the discussion between you and the healthcare team, but may act as a starting point for discussion. If after reading it you have any concerns or require further explanation, please discuss this with a member of the healthcare team.

What is Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION)?

Non-arteritic anterior ischemic optic neuropathy (NAION) is a condition that causes sudden vision loss in one eye. It is caused by a lack of blood flow to the front of the optic nerve, the cable that connects the eye to the brain. NAION is the most common cause of sudden vision loss in people over the age of 50.

What causes NAION?

The exact cause of NAION is not fully understood. We do know that it happens more often in patients born with small optic discs (the front part of the optic nerve that can be seen within the eye). This crowded optic disc structure (often referred to as a small cup-to-disc ratio or a “disc at risk”) makes the nerve more vulnerable to blood supply problems. Some researchers have suggested that transient fluctuations in blood pressure may play a role in the onset of NAION, but this is controversial. Other risk factors may include the chronic vascular effects of:

  • High blood pressure
  • Diabetes
  • High cholesterol
  • Sleep apnoea
  • Smoking
  • A recent drop in blood pressure, this can be related to night time drop of blood pressure while asleep, or the use of erectile dysfunction medicines like Viagra.

What are the symptoms of NAION?

The most common symptom of NAION is sudden vision loss in one eye. The vision loss is usually painless and can range from mild to severe. Some people may also experience blurred vision, colour distortion, or a loss of peripheral vision.

How is NAION diagnosed?

NAION is diagnosed by an eye doctor. The eye doctor will ask about your medical history and perform a physical exam of your eyes. They may also order tests, such as a visual field test and an optical coherence tomography (OCT) scan, to confirm the diagnosis.

How is NAION treated?

There is no cure for NAION, but there are measures that can help to prevent similar attacks in the future. These measures may include:

  • Controlling blood pressure, blood pressure recording during sleep (ambulatory blood pressure recording) could be useful in detecting night time dips in blood pressure. To arrange this, you can discuss it with your GP.
  • Managing diabetes
  • Treating sleep apnoea
  • Quitting smoking
  • Exercising and optimising body weight
  • Cautious use of erectile dysfunction drugs when indicated.
  • Avoiding too much lowering of blood pressure during general anaesthesia (hypotensive techniques), inform you anaesthetist that you have suffered from a previous NAION episode.

What is the prognosis for NAION?

The prognosis for NAION is variable. Some people may experience some improvement in their vision in the initial period, but many others may not experience significant improvement. People with NAION in one eye are at increased risk of developing NAION in the other eye (there is about a 15% risk of second eye involvement within 5 years).

Should you require further advice on the issues contained in this leaflet, please do not hesitate to contact the ophthalmology department on tel: 01482 608788.

General Advice and Consent

Most of your questions should have been answered by this leaflet, but remember that this is only a starting point for discussion with the healthcare team.

Consent to treatment

Before any doctor, nurse or therapist examines or treats you, they must seek your consent or permission. In order to make a decision, you need to have information from health professionals about the treatment or investigation which is being offered to you. You should always ask them more questions if you do not understand or if you want more information.

The information you receive should be about your condition, the alternatives available to you, and whether it carries risks as well as the benefits. What is important is that your consent is genuine or valid. That means:

  • you must be able to give your consent
  • you must be given enough information to enable you to make a decision
  • you must be acting under your own free will and not under the strong influence of another person

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