Anterior Ischaemic Optic Neuropathy

What's going on?

The blood supply to optic nerve has been compromised, resulting in loss of vision. The cause is either a microinfarct (non-arteritic anterior ischaemic optic neuropathy (NAION) or an inflammatory process, usually secondary to giant cell arteritis (arteritic anterior ischaemic neuropathy). The patient may lose their whole field of vision or develop a pattern of visual loss, such as an altitudinal defect when only the upper or lower portion of the visual field is lost.

If I examine the patient what will I find?

The vision will be reduced. They may have an upper or lower altitudinal visual field defect. The disc will be swollen. There will be a relative afferent papillary defect.

What if I've diagnosed it?

Giant cell arteritis needs excluding. Refer urgently.

What will the hospital do?

If there is a suspicion of GCA, the patient will undergo a temporal artery biopsy to exclude or confirm the diagnosis. Inflammatory indices will be assessed. If it is a non-arteritic process, there is no possible intervention and a conservative approach is taken in the hope of spontaneous recovery.

What do I need to do?

If the process is arteritic, the patient will be on long-term steroids. Consider osteoporosis prophylaxis and gastric acid protection.

If the process is non-arteritic, then assessment of cardiovascular and cerebrovascular risk factors is prudent. Consider antiplatelet treatment as a prophylactic measure if not contraindicated.

What to tell the patient

The prognosis is much better for the non-arteritic process. Visual recovery is extremely unlikely in the arteritic process.

Problems that may arise, and how to deal with them

Despite steroid treatment, the vision may deteriorate further due to the on-going inflammatory process. If vision deteriorates or the patient has a recurrence of GCA symptoms, their inflammatory indices should be measured urgently and the steroid dose increased.