CBL: Transient Monocular Vision Loss in a 71-Year-Old

A retired teacher with brief, recurrent greying of the left eye.

Topic: Amaurosis Fugax Level: Resident

Learning Objectives

  • Recognize amaurosis fugax as transient monocular vision loss (TMVL).
  • Understand that AFx is a medical emergency requiring urgent carotid/vascular evaluation.
  • Differentiate ocular, optic nerve, and central causes; consider GCA workup in the appropriate demographic.

Vignette

A 71-year-old retired kindergarten teacher reports 1–2 weeks of transient greying haze over the left eye, lasting minutes and resolving completely. No headache during episodes; denies jaw claudication, scalp tenderness, myalgias, or joint pain. Medications: lisinopril, aspirin, simvastatin, omeprazole, tolterodine. PMH: hypertension, hyperlipidemia, GERD, urinary incontinence, hysterectomy, tonsillectomy. Social: never smoker, ~2 glasses wine/week, lives alone. Family history: lupus (daughter), Alzheimer disease (mother), non-Hodgkin lymphoma (father). ROS otherwise unremarkable; vision currently normal.

Exam: Pulse 82, BP 131/83, afebrile. Cardiovascular exam normal; carotid auscultation without bruits. Cranial nerves intact; visual acuity corrected to baseline; pupils and fields normal; extraocular movements intact. Strength and tone normal; sensation intact; reflexes normal except absent Achilles bilaterally; plantar responses downgoing; coordination and gait normal; negative Romberg.

Localization and Neuroanatomy

The episodic, negative visual phenomenon ("greying out") affecting a single eye for minutes localizes anterior to the chiasm—retina, optic nerve, or ocular perfusion. Lack of positive visual phenomena argues against migraine aura. Transient monocular loss suggests retinal/optic nerve ischemia (retinal TIA) most commonly from ipsilateral internal carotid atherosclerotic disease with distal embolization.

Diagnosis

Treat as a medical emergency similar to TIA. Urgent vascular imaging of the head/neck (carotid duplex ultrasound, CTA, or MRA) is indicated to evaluate for carotid stenosis/plaques. Prompt ophthalmic evaluation helps exclude retinal pathology; check intraocular pressure. In patients >50 with concerning features for giant cell arteritis (GCA)—new headache, jaw claudication, scalp tenderness, polymyalgia—obtain ESR/CRP and CBC and consider temporal artery ultrasound/biopsy.

Key mimics: ocular migraine (positive visual aura), optic neuritis (painful vision loss, younger patients), retinal detachment/tear, acute angle closure glaucoma (pain, halos), occipital TIA (binocular).

Question 1

Amaurosis fugax most directly reflects transient ischemia of which structure?

  • A. Brainstem
  • B. Retina/optic nerve of the eye
  • C. Spinal cord
  • D. Myocardium

Question 2

Which is the most appropriate urgent diagnostic step?

  • A. MRI brain only
  • B. Carotid vascular imaging (duplex, CTA, or MRA)
  • C. Neck CT without contrast
  • D. Electrophysiologic testing

Question 3

When carotid imaging shows ipsilateral symptomatic stenosis, what is the preferred management?

  • A. Blood pressure support
  • B. Maximize medical therapy only regardless of stenosis
  • C. Carotid endarterectomy (CEA) or stenting for high-grade stenosis plus best medical therapy
  • D. Ophthalmologic surgery

Teaching Points

  • Amaurosis fugax = transient monocular negative visual loss (retinal TIA) and is a stroke warning.
  • Urgent carotid imaging (duplex/CTA/MRA) is recommended; evaluate the eye as well (retina, IOP).
  • Consider GCA in patients ≥50 with suggestive symptoms; obtain ESR/CRP and arrange imaging/biopsy if indicated.
  • For symptomatic carotid stenosis 70–99%, CEA (or CAS in appropriate patients) plus best medical therapy reduces stroke risk; optimize antiplatelet, statin, BP, and lifestyle.

References

  1. AHA/ASA. Prevention of Stroke in Patients With Stroke and TIA. Stroke. 2021.
  2. ESVS. 2023 Guidelines on Atherosclerotic Carotid & Vertebral Disease.
  3. StatPearls. Amaurosis Fugax (updated 2025).
  4. ACR/EULAR 2022 GCA Classification Criteria.
  5. AAO EyeNet. Retinal TIAs: A Medical Emergency.