Amaurosis fugax from disease of the external carotid artery.

Three patients with proved internal carotid artery occlusion and diseased external carotid artery or common carotid artery had amaurosis fugax. Evidence for retinal embolization through external carotid collaterals is retinal emboli and infarction after carotid artery manipulation, amaurosis during external carotid angiography, and relief of amaurosis by endarterectomy of this vessel. The abundance of external carotid collaterals, their size, and natural incidence are discussed. Reports clinically support embolization to the central retinal artery and ophthalmic artery through these collaterals.