Amaurosis fugax is the transient monocular loss of vision, normally lasting a few seconds to a few minutes, secondary to vascular ischemia or insufficiency.
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Epidemiology
It has an incidence of 50,000 per year in the United States.
Clinical presentation
Patients present with transient monocular, painless, loss of vision lasting seconds to minutes, with full resolution.
Pathology
Etiology
Common etiologies include:
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thromboembolic
atherosclerotic emboli traveling to and disrupting ophthalmic circulation, especially from ipsilateral carotid artery
cardiac emboli from valvular disease (e.g. rheumatic heart disease, infective endocarditis)
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hemodynamic
hypoperfusion secondary to increased metabolic demands on a background of severe atherosclerotic vessels or acute hypovolemia
retinal arterial vasospasm (e.g. giant cell arteritis)
ocular vascular disease
neurological (e.g. optic neuritis)
Radiographic features
Although different etiologies will have different radiographic features, a work-up of a patient presenting with amaurosis fugax may include:
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duplex ultrasound of carotid arteries
identifying occlusion, stenosis, and ulcerations at the bifurcation
consider CT or MRI angiography
echocardiogram to identify cardio-embolic causes
Treatment and prognosis
Management depends on the underlying cause. During the work-up, modifiable risk factors should be addressed (e.g. smoking cessation, control of diabetes mellitus, control of hyperlipidemia) and patients may be commenced on aspirin for stroke prevention (the annual incidence of stroke in patients with amaurosis fugax is 2%).
Differential diagnosis
acute angle-closure glaucoma
Practical points
prevention of stroke is key from this presentation