Can left carotid artery stenosis cause vision problems?

Can Left Carotid Artery Stenosis Cause Vision Problems?

Yes, left carotid artery stenosis can absolutely cause vision problems in the left eye through two primary mechanisms: embolic events causing transient or permanent monocular vision loss (amaurosis fugax or central retinal artery occlusion), and chronic hypoperfusion leading to reduced retinal blood flow. 1

Mechanisms of Vision Loss

Embolic Ocular Events

• Transient monocular blindness (amaurosis fugax) is caused by temporary reduction of blood flow to the ipsilateral eye, typically described as a shade drawn upward or downward over the visual field. 1
• The most common cause is atherosclerosis of the ipsilateral internal carotid artery, with embolic material including fibrin, cholesterol crystals (Hollenhorst plaques), or atherosclerotic debris traveling through the ophthalmic artery to the retinal circulation. 1
• Central retinal artery occlusion (CRAO) represents complete embolic or thrombotic occlusion of the central retinal artery, resulting in sudden, severe, permanent vision loss with characteristic funduscopic findings including diffuse retinal whitening and a cherry red spot. 1

Chronic Hypoperfusion

• In severe internal carotid artery stenosis, collateral circulation may divert blood flow from the eye to the brain via the circle of Willis to maintain cerebral perfusion, resulting in recurrent episodes of transient monocular vision loss without cerebral infarction because the brain is perfused at the expense of the eye. 1
• Patients with high-grade stenosis (≥80%) or carotid artery occlusion with retrograde ophthalmic artery flow demonstrate significantly reduced central retinal artery peak systolic velocity (0.098 ± 0.028 m/s versus 0.130 ± 0.035 m/s on the unaffected side). 2

Clinical Presentations

Transient Symptoms

• Amaurosis fugax presents as brief episodes of monocular vision loss, typically lasting minutes, affecting the eye ipsilateral to the stenotic carotid artery. 1
• Patients may describe dimming of vision, altitudinal visual field defects, or complete temporary blindness in one eye. 3

Permanent Vision Loss

• CRAO results in severe, irreversible vision loss, with nearly 80% of patients having visual acuity of "count fingers" or worse at follow-up, and only 17.7% achieving functional visual recovery (improvement from 20/200 or worse to 20/100 or better). 1
• Retinal tissue may remain viable if CRAO is present for <97 minutes, with severe irreversible damage occurring after 240 minutes. 4

Stroke Risk Stratification

The risk of subsequent stroke in patients with transient monocular blindness is directly related to the number of cardiovascular risk factors present. 1

• 3-year stroke risk with medical treatment alone:

  • 0-1 risk factors: 1.8%
  • 2 risk factors: 12.3%
  • 3-4 risk factors (hypertension, hypercholesterolemia, diabetes, smoking): 24.2% 1

• While the risk of stroke after retinal TIA may be lower than after cerebral TIA, the overall risk for cardiovascular events and death remains equivalent, reflecting shared major vascular risk factors. 1

Diagnostic Evaluation

Immediate Assessment

• Funduscopic examination is essential to confirm retinal ischemia, identify emboli (Hollenhorst plaques), and differentiate from other causes of vision loss such as vitreous or retinal hemorrhage. 1
• Duplex ultrasound is the first-line imaging modality to detect and quantify carotid artery stenosis severity. 1

Comprehensive Vascular Workup

• Carotid imaging with ultrasound, CT angiography, or MR angiography to identify ipsilateral stenosis severity. 4
• Echocardiography to evaluate for structural heart disease and cardiac embolic sources. 4
• Extended cardiac monitoring to detect atrial fibrillation. 4
• Screening for giant cell arteritis with ESR, CRP, and clinical assessment of temporal arteries, particularly in patients over 50 years old. 4

Management Implications

Acute Vision Loss (CRAO)

• Treat as an ophthalmic and neurological emergency requiring rapid triage to emergency medical care. 4
• Consider intravenous tissue plasminogen activator (tPA) if presenting within 4.5 hours of symptom onset, though evidence is limited. 4

Carotid Revascularization

• Carotid endarterectomy (CEA) performed within 2 weeks of symptomatic events (including amaurosis fugax) significantly reduces stroke risk, but benefit diminishes rapidly after this window. 1
• CEA improves both subjective and objective visual function in patients with carotid stenosis, including visual acuity, visual fields, intraocular pressure, and retinal blood flow. 5
• Recent evidence shows CEA provides superior visual recovery compared to carotid artery stenting, likely due to fewer postoperative microembolisms that can impair visual outcomes. 6

Critical Pitfalls

• Do not dismiss monocular vision loss as benign—it represents a warning sign of significant cerebrovascular disease requiring urgent evaluation. 1
• Patients presenting with retinal arterial emboli visible on funduscopy are at increased risk for stroke and vascular death, regardless of symptom duration. 3
• The intraluminal streaming phenomenon means recurrent vascular emboli tend to travel to the same arterial branch, so patients with retinal TIAs are more likely to have subsequent retinal rather than cerebral infarctions. 1