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Ocular Ischemic Syndrome/Carotid Occlusive Disease

URGENT — Neuro

Symptoms

  • subacute vision loss (weeks to months)
  • "ocular angina": dull periorbital pain that worsens when lying flat (recumbency)
  • light-induced amaurosis: vision loss when moving from dark to bright light
  • prolonged visual recovery after bright light (e.g., camera flash)
  • history of amaurosis fugax (transient monocular vision loss)

Clinical Findings

Posterior segment

  • mid-peripheral "blotty" hemorrhages (watershed ischemia)
  • dilated but straight (non-tortuous) retinal veins ("beaded" appearance)
  • narrowed retinal arteries

Anterior segment

  • rubeosis iridis (nvi): occurs in ~66% of symptomatic cases
  • paradoxically normal or low iop initially (ischemic ciliary body under-produces aqueous)
  • mild "pseudo-iritis" (flare > cell)
  • asymmetric cataract or iris atrophy

Diagnostic imaging

  • ivfa: prolonged arm-to-retina time (>15s), patchy choroidal filling, and late vessel staining
  • orbital doppler: reversed flow in ophthalmic artery (eca filling ica via collaterals)
  • carotid imaging: duplex ultrasound (first-line) or cta/mra of neck

Etiology

Primary cause

  • severe (≥90%) ipsilateral internal carotid artery (ica) stenosis or occlusion

Other causes

  • ophthalmic artery disease, giant cell arteritis (gca), or takayasu arteritis
  • carotid dissection or fibromuscular dysplasia

Red Flags

  • iop spike after carotid surgery: revascularized ciliary body resumes aqueous production against a closed angle
  • cardiovascular risk: 5-year mortality is ~40% (mostly cardiac events)
  • ois vs crvo: ois has straight veins and pain on recumbency; crvo has tortuous veins and is usually painless

Investigations

Ocular workup

  • gonioscopy: screen for angle neovascularization (nva)
  • fluorescein angiography (ivfa): look for delayed filling and peripheral non-perfusion

Mandatory systemic workup

  • carotid duplex ultrasound, followed by cta or mra of the neck
  • cardiology referral: high association with coronary artery disease (cad)
  • vasculopathic screen: bp, hba1c, lipids, and peripheral pulses

Treatment

Vascular intervention

  • carotid endarterectomy (cea) or stenting for symptomatic stenosis ≥70%

Ocular management

  • panretinal photocoagulation (prp) for iris/angle/retinal neovascularization
  • intravitreal anti-vegf for nvi/nvg or macular edema
  • topical aqueous suppressants (avoid prostaglandins if inflamed)

Systemic management

  • antiplatelet therapy (aspirin/clopidogrel) and statins
  • aggressive management of bp, glucose, and smoking cessation

Clinical Pearl

slow-to-dilate pupils with mid-peripheral hemorrhages and new iris neovascularization in an older patient is ocular ischemic syndrome — get a carotid doppler before treating it as a vein occlusion.

Differential Diagnosis

  • ## Central retinal vein occlusion (CRVO)
  • • dilated AND tortuous veins; hemorrhages in all 4 quadrants; usually painless
  • ## Diabetic retinopathy
  • • usually bilateral; typically includes microaneurysms and hard exudates
  • ## Takayasu arteritis
  • • large-vessel vasculitis; check for absent pulses in the neck/arms

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