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Central Retinal Artery Occlusion

CRITICAL — Retina

Symptoms

Unilateral, painless, acute vision loss (occurs over seconds).

Severe vision loss: counting fingers to light perception in 94% of cases.

May have a history of amaurosis fugax (transient visual loss).

Clinical Findings

Acute signs

  • Marked afferent pupillary defect (RAPD) on the affected side.
  • Superficial retinal whitening/opacification of the posterior pole.
  • Cherry-red spot at the fovea (transient; typically resolves over weeks).
  • Narrowed retinal arterioles with boxcarring or segmentation of the blood column.
  • Visible retinal arteriolar emboli.
  • Cilioretinal artery sparing (15–30%): foveolar perfusion is maintained.

Late signs (weeks later)

  • Optic disc pallor and arteriolar attenuation.
  • Inner-retinal atrophy.
  • Vision of light perception or worse suggests Ophthalmic Artery Occlusion (OAO).

Etiology

Embolic sources

  • Cholesterol (Hollenhorst plaque): refractile, yellow crystals at bifurcations (carotid origin).
  • Calcium: white plaques frequently causing distal infarction (cardiac valve origin).
  • Platelet-fibrin: dull white plugs (carotid origin).

Systemic vasculitis & inflammation

  • Giant cell arteritis (GCA): mandates immediate exclusion in patients ≥50.
  • Collagen vascular diseases: SLE, Polyarteritis nodosa.

Hematologic disorders

  • Hypercoagulable states: factor V Leiden, antiphospholipid syndrome, protein C/S deficiency.
  • Hyperviscosity: polycythemia, multiple myeloma, Waldenström macroglobulinemia.
  • Sickle cell disease and profound anemia.

Red Flags

Retinal stroke (code stroke)

  • CRAO is a retinal stroke; transfer immediately to an Emergency Department/stroke center for emergent MRI/DWI and vascular workup.

Giant cell arteritis (GCA)

  • In patients ≥50 years, rule out GCA immediately via stat ESR, CRP, and platelets.

Other concerns

  • Concurrent TIA or stroke symptoms require urgent neurology/vascular intervention.
  • Retinal whitening without a cherry-red spot and LP vision suggests OOA.

Investigations

Emergency workup

  • Immediate ED transfer for stroke protocol: MRI/DWI, carotid duplex, EKG, and echocardiogram.
  • GCA panel: stat ESR, CRP, and platelets (if age ≥55 or no embolus seen).

Systemic labs

  • Blood pressure, fasting glucose, HbA1c, CBC, and PT/PTT.
  • Younger patients (<50): hypercoagulable panel, syphilis testing, and protein electrophoresis.

Ocular imaging

  • OCT: shows inner retinal hyperreflectivity (acute) followed by thinning (late).
  • IVFA: demonstrates delayed or absent arterial filling.

Treatment

Acute interventions (within 4–6 hours)

  • Ocular massage and anterior chamber paracentesis to lower IOP.
  • Topical IOP-lowering drops (timolol, brimonidine).
  • Inhaled carbogen (5% CO2 + 95% O2) or hyperbaric oxygen (if available within 24h).

Systemic management

  • Antiplatelet or anticoagulation therapy as directed by neurology.
  • Carotid endarterectomy for significant stenosis; anticoagulation for atrial fibrillation.
  • Systemic steroids for confirmed GCA.

Clinical Pearl

CRAO is a retinal stroke. The priority is preventing a secondary cerebral stroke, as 25% of patients have concurrent silent brain infarcts. The cherry-red spot is not permanent and resolves as infarction progresses.

Differential Diagnosis

  • Acute ophthalmic artery occlusion
  • Commotio retinae
  • Giant cell arteritis

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