Amaurosis fugax, one type of TIA, is a manifestation of carotid bifurcation atherosclerotic disease. It is manifested by unilateral blindness, being described by the patient as a window shade across the eye, lasting for minutes or hours. It is caused by micro emboli from a carotid lesion lodging in the retinal artery, the first intracerebral branch of the internal carotid artery.