Artery occlusion

• Central retinal artery occlusion (CRAO) is the sudden occlusion of the artery supplying the inner retina leading to hypoperfusion of the retina, hypoxic damage, retinal cell death and visual loss.
• Causes:

  • most commonly an embolism - carotid artery disease or AF
  • Can be from an in-situ thrombosis - atherosclerotic disease, vasculitis, inflammatory disorders
• Risk factors:

  • Hypertension
  • Smoking
  • Hyperlipidaemia
  • Diabetes
  • Hypercoagulable states
  • Male gender
  • Carotid artery stenosis
• Symptoms:

  • Sudden painless unilateral visual loss - occurs over seconds
  • Amaurosis fugax
• important areas to cover in the history include:

  • Past medical history: atherosclerotic disease or vasculitis
  • Symptoms of temporal/giant cell arteritis: headaches, temporal tenderness, jaw claudication
• Typical clinical findings in CRAO include:

  • Profound unilateral reduction in visual acuity (usually reduced to counting fingers or less)
  • Relative afferent pupillary defect (RAPD)
  • Pale retina with a central cherry-red spot on fundoscopy
• A physical examination should also be undertaken to identify an underlying cause, paying particular attention to:

  • Pulse rate and rhythm
  • Blood pressure
  • Carotid bruits
  • Signs of temporal arteritis (scalp tenderness, nodular temporal arteries)
  • Signs of connective tissue diseases that could predispose to vasculitis in younger patients
• Relevant laboratory investigations include:

  • ESR and CRP: to exclude temporal/giant cell arteritis
  • Full blood count: to check for myeloproliferative disorders or anaemia
  • Coagulation studies (PT and APTT): to screen for coagulation disorders
• If an embolic cause is suspected, other investigations to consider may include:

  • Carotid duplex ultrasound (doppler): to look for carotid artery stenosis
  • ECG: to look for atrial fibrillation
  • Echocardiogram: to look for mural thrombus
  • Ambulatory ECG monitoring: to look for paroxysmal atrial fibrillation
• If inflammatory markers are elevated and/or the history and examination are consistent with temporal/giant cell arteritis, then high dose steroids should be initiated immediately.
• Immediate management options include:

  • Ocular massage: repeatedly massaging the globe over the closed lid for ten seconds with five-second interludes may occasionally dislodge the obstructing thrombus.
  • Increase blood oxygen content and dilate retinal arteries: administration of sublingual isosorbide dinitrate or oral pentoxifylline. Inhalation of a carbogen or hyperbaric oxygen.
  • Reduce intraocular pressure: to increase retinal artery perfusion pressure with intravenous acetazolamide and mannitol, plus anterior chamber paracentesis.