Amaurosis fugax is caused by a blockage of blood flow to the eye, usually by an embolus entering the opthalmic artery. It qualifies as a transient ischaemic event (TIA).
It is described as a curtain coming down across the field of vision in one eye. Blackness covers all or part of the visual field for a variable period of time, usually between 5 and 30 minutes.
The most common cause of amaurosis fugax is emboli (blood clots) coming off a stenosed carotid artery. Other causes include emboli from the heart or heart valves and arterial spasm.
Even though blindness is temporary, this is a serious symptom because it indicates the danger of further vascular events occurring, including stroke. Anyone with amaurosis fugax should be reviewed by a doctor with some urgency.