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Symptoms ⬇

Monocular visual loss that usually lasts seconds to minutes, but may last up to 1 to 2 hours. Vision returns to normal.

Signs ⬆ ⬇

Critical

May see an embolus within an arteriole or the ocular examination may be normal.

Other

Signs of ocular ischemic syndrome (see 11.11, OCULAR ISCHEMIC SYNDROME/CAROTID OCCLUSIVE DISEASE), an old branch retinal artery occlusion (sheathed arteriole), or neurologic signs and symptoms caused by cerebral ischemia (e.g., transient ischemic attacks [TIAs] with contralateral arm or leg weakness).

Differential Diagnosis ⬆ ⬇

Differential Diagnosis of Transient Visual Loss

Etiology ⬆ ⬇

  1. Embolus from the carotid artery (most common), heart, or aorta.
  2. Vascular insufficiency as a result of arteriosclerotic disease of vessels anywhere along the path from the aorta to the globe causing hypoperfusion often precipitated by a postural change or cardiac arrhythmia.
  3. Hypercoagulable/hyperviscosity state.
  4. Rarely, an intraorbital mass may compress the optic nerve or a nourishing vessel in certain gaze positions, causing gaze-evoked transient visual loss.
  5. Vasospasm.

Work Up ⬆ ⬇

Workup
  1. Amaurosis fugax is considered by the American Heart Association to be a form of TIA. Current guidelines recommend MRI with diffusion weighted imaging, urgent carotid and cardiac studies, and neurology consultation. If patient is seen within days of the event, emergent referral to a stroke center or emergency room is required.
  2. Immediate ESR, CRP, and platelet count when GCA is suspected.
  3. History: Monocular visual loss or homonymous hemianopsia (verified by covering each eye)? Duration of visual loss? Previous episodes of transient visual loss or TIA? Cardiovascular disease risk factors? Oral contraceptive use? Smoker? Vascular surgeries?
  4. Ocular examination, including a confrontation visual field examination and a dilated retinal evaluation. Look for an embolus or signs of other aforementioned disorders.
  5. Medical examination: Cardiac and carotid auscultation.
  6. Noninvasive carotid artery evaluation (e.g., duplex Doppler US). Consider orbital color Doppler US, if available, which may reveal a retrolaminar central retinal artery stenosis or embolus proximal to the lamina cribrosa. MRA or CTA may also be considered, but cannot evaluate flow like a duplex Doppler US.
  7. CBC with differential, fasting blood sugar, hemoglobin A1c, and lipid profile (to rule out polycythemia, thrombocytosis, diabetes, and hyperlipidemia).
  8. Cardiac evaluation including an echocardiogram.

Treatment ⬆

  1. Carotid disease.
    • Consider aspirin 81 mg or 325 mg p.o. daily.
    • Consult vascular surgery in select patients if a surgically accessible, high-grade carotid stenosis is present for consideration of carotid endarterectomy or endovascular stent.
    • Control hypertension, diabetes, and dyslipidemia (follow up with a medical internist).
    • Lifestyle modification (e.g., smoking cessation).
  2. Cardiac disease.
    • Consider aspirin 325 mg p.o. daily.
    • In presence of a thrombus, coordinate care with internal medicine and/or cardiology with likely hospitalization and anticoagulation (e.g., heparin therapy).
    • Consider referral to cardiac surgery as needed.
    • Control arteriosclerotic risk factors (follow up with medical internist).
  3. If carotid and cardiac diseases are ruled out, a vasospastic etiology can be considered (extremely rare). Treatment with a calcium channel blocker may be beneficial.