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Amaurosis Fugax / Transient Visual Loss

URGENT — Neuro

Symptoms

  • Monocular visual loss lasting seconds to minutes (occasionally up to 1–2 hours).
  • Complete return to normal vision between episodes.

Clinical Findings

Ocular findings

  • Often normal between episodes.
  • Visible embolus within a retinal arteriole (Hollenhorst, calcific, or platelet-fibrin).
  • Signs of ocular ischemic syndrome (OIS).

Neurologic findings

  • Associated TIA features: Contralateral arm or leg weakness, dysarthria, or aphasia.

Etiology

Embolic (most common)

  • Carotid artery atherosclerosis: The most common source.
  • Cardiac: Valvular disease, atrial fibrillation, or endocarditis.
  • Aortic arch atherosclerosis.

Hypoperfusion

  • Arteriosclerotic disease anywhere along the aorta-to-globe path.
  • Often precipitated by postural changes or cardiac arrhythmias.

Other causes

  • Giant cell arteritis (GCA): Must consider in patients age ≥55.
  • Hypercoagulable or hyperviscosity states.
  • Rare: Vasospasm or gaze-evoked loss (intraorbital mass compressing the nerve or vessel).

Red Flags

  • Treat as a TIA: Up to 10% stroke risk within 90 days; 2–5% risk within 48 hours.
  • Visible Hollenhorst plaque: Strong indicator of a carotid source.
  • Age ≥55 with new monocular loss: Rule out GCA immediately with ESR and CRP.
  • Symptomatic carotid stenosis >70%: High risk for stroke; mandates urgent intervention.

Investigations

Emergent TIA workup

  • Emergent stroke-center or ER referral (AHA classifies amaurosis fugax as a TIA).
  • Neurology consultation and MRI brain with diffusion-weighted imaging.

Ocular examination

  • Confrontation visual fields and dilated fundus exam to identify emboli or OIS signs.

Cardiovascular & imaging

  • Carotid duplex Doppler ultrasound (or MRA/CTA).
  • ECG and echocardiogram.
  • Orbital color Doppler ultrasound (if retrolaminar stenosis is suspected).

Laboratory testing

  • CBC with differential (rule out polycythemia/thrombocytosis), fasting glucose, HbA1c, and lipid profile.
  • If age ≥55: Stat ESR, CRP, and platelet count (rule out GCA).

Treatment

Antiplatelet therapy

  • Aspirin 81–325 mg daily or Clopidogrel 75 mg daily (start while workup is ongoing).

Vascular & cardiac management

  • Carotid disease: Carotid endarterectomy (CEA) or stenting for high-grade stenosis; medical therapy for low-grade.
  • Cardiac disease: Anticoagulation (heparin/warfarin/DOAC) for atrial fibrillation or thrombus.

Systemic & lifestyle

  • High-dose corticosteroids if GCA is confirmed.
  • Risk-factor modification: Statin therapy, smoking cessation, and BP/DM control.
  • Calcium channel blockers only if vasospasm is confirmed after excluding embolic sources.

Clinical Pearl

Amaurosis fugax is an ocular TIA. The risk of a permanent stroke within 48 hours is 2–5%. The ABCD2 score applies. Carotid endarterectomy is indicated if stenosis is >70%. Never dismiss a transient visual episode.

Differential Diagnosis

  • Papilledema (transient obscurations)
  • Impending central retinal vein occlusion
  • Basilar artery migraine
  • Vertebral artery dissection
  • Drop attacks

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