Amaurosis fugax

Amaurosis fugax is the transient monocular loss of vision, normally lasting a few seconds to a few minutes, secondary to vascular ischemia or insufficiency.

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:

• 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)
• hemodynamic 
  • hypoperfusion secondary to increased metabolic demands on a background of severe atherosclerotic vessels or acute hypovolemia 
  • retinal arterial- or vaso-spasm (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:

• Duplex ultrasound of carotid arteries
  • identifying occlusion, stenosis, and ulcerations at the bifurcation 
• consider CTA or MRA 
• 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

• migraine
• multiple sclerosis
• anterior ischemic optic neuropathy (AION)
• central or branch retinal artery occlusion (CRAO/BRAO)
• central retinal vein occulsion (CRVO)
• acute angle-closure glaucoma

Practical points

• prevention of stroke is key from this presentation