transient monocular blindness


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transient monocular blindness

an episode of total or partial loss of vision in one eye, caused by ischemia of the eye and lasting several minutes or longer. The term is sometimes used synonymously with amaurosis fugax and sometimes to designate an episode of longer duration. Also called transient monocular visual loss.

transient monocular blindness

A temporary loss of vision affecting one eye. In older adults it is usually a form of transient ischemic attack, caused by carotid atherosclerosis, and is therefore a harbinger of stroke. In young adults it may be caused by migraine. Synonym: amaurosis fugax

Etiology

In older adults, causes of carotid atherosclerosis include smoking, diabetes mellitus, hypertension, obesity, and hypercholesterolemia. When atherosclerotic plaques form within the carotid artery, they may ulcerate. The exposed endothelium within the artery becomes a focus of inflammation and blood clotting. Blindness occurs when tiny clots from the carotid arteries embolize to the ophthalmic arteries.

Symptoms

Patients often describe a dark shade descending into the field of vision. At the same time they may have other stroke symptoms, e.g., difficulty with speech or weakness of the hand on the side opposite the affected eye.

Treatment

A patient who may have carotid atherosclerosis should begin taking aspirin or other antiplatelet drugs if these are tolerated. Blood pressure and lipid levels should be controlled. The patient should be referred for noninvasive evaluation of blood flow through the carotid arteries, e.g., ultrasonography. If the carotid arteries are significantly blocked, the patient and physician should consider the risks and benefits of carotid endarterectomy.

See also: blindness
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