Amaurosis fugax

What's going on?

This is transient ischaemic attack (TIA) of the retinal circulation. An embolus has lodged in the central retinal circulation and caused ischaemia of the retina. The embolus either dislodges or is lysed, and blood flow is restored. Classically, patients describe the sudden, painless onset of complete visual loss in one eye. Often they describe a black or grey curtain falling or rising over their vision.

If I examine the patient, what will I find?

By definition after the resolution of the episode there should be no residual visual defect. There may be a carotid bruit on auscultation (although some clinicians believe this is a completely worthless sign) or the patient may have atrial fibrillation.

What if I've diagnosed it?

If the diagnosis is clear-cut and the vision is completely restored with no evidence of any visual field defect, then referral to the eye service is not required.

If the diagnosis is in doubt the patient should be referred soon via letter.

If there are multiple episodes, the possibility of GCA should be considered and an ESR/CRP obtained, even in the absence of GCA symptoms. If GCA symptoms are present, urgent assessment of inflammatory indices and urgent referral if the results are positive is required.

Any predisposing factors should be addressed as described above.

If you have access to a TIA fast-track clinic, then refer according to local criteria.

What will the hospital do?

Carotid Dopplers and/or a cardiac echo will be organised. If carotid Dopplers indicate a significant stenosis, referral may be made directly to a vascular surgeon. Inflammatory indices should be checked in case the patient has occult asymptomatic GCA.

What do I need to do?

These patients are at risk of further embolic phenomena, which could result in a permanent occlusion (central retinal artery occlusion) or even a CVA. Cardiovascular risk factors should be addressed and carotid Dopplers or cardiac echo should be arranged to ensure there is no carotid or cardiac source of embolus. Antiplatelet medication should be considered as a prophylactic measure.

What to tell the patient

They have had a mini-stroke and are at risk of further ocular or cerebral embolic events.