Central retinal artery occlusion

Background

• Acute interruption of blood flow to the retinal artery causing retinal ischemia
• A stroke equivalent — 15-25% of patients will have an acute stroke or TIA within 1 week
• Ophthalmologic emergency — retinal tolerance for ischemia is approximately 90-100 minutes
• Permanent vision loss occurs in most patients despite treatment
• Average age: 60-65 years
• Most common cause: thromboembolism from carotid artery atherosclerosis or cardiac source

Etiology

• Carotid artery atherosclerosis (most common)
• Cardiac embolism (atrial fibrillation, valvular disease, endocarditis)
• Giant cell arteritis (GCA) — must be excluded in patients >50
• Hypercoagulable states
• Vasculitis
• Dissection of carotid or ophthalmic artery

Clinical Features

• Sudden, painless, monocular vision loss — often described as "lights went out"
• Typically develops over seconds
• Severe visual acuity loss (often counting fingers or light perception only)
• Relative afferent pupillary defect (APD / Marcus Gunn pupil)
• Fundoscopy:
  • Pale/white retina with cherry-red spot at fovea (pathognomonic)
  • Box-car segmentation of retinal vessels (intermittent blood flow)
  • Retinal edema
• Branch RAO: visual field defect corresponding to affected branch

Differential Diagnosis

• Central retinal vein occlusion (hemorrhages on fundoscopy, less acute)
• Retinal detachment
• Optic neuritis (painful with eye movement)
• Vitreous hemorrhage
• Giant cell arteritis (GCA) with anterior ischemic optic neuropathy
• Stroke affecting visual cortex

Evaluation

• ESR and CRP — stat to evaluate for giant cell arteritis (ESR >50 in GCA)
  • If GCA suspected: start treatment immediately (see below)
• Fundoscopic exam — cherry-red spot diagnostic
• Intraocular pressure (IOP) — rule out acute glaucoma
• CT/CTA head and neck — evaluate for stroke, carotid stenosis
  • May also obtain CTA to look for embolic source
• ECG — evaluate for atrial fibrillation
• Echocardiogram — evaluate for cardiac embolic source
• Labs: CBC, BMP, coagulation studies, lipid panel, HbA1c
• MRI with DWI — assess for concurrent acute stroke

Management

• No proven treatment reliably restores vision; most interventions have limited evidence
• Traditional temporizing measures (limited evidence):
  • Ocular massage — intermittent digital pressure over closed eyelid (10-15 seconds on, 5 seconds off)
  • Attempt to dislodge embolus distally
• Emergent ophthalmology consultation
• If GCA suspected (age >50, elevated ESR, headache, jaw claudication):
  • Methylprednisolone 1 g IV daily x 3 days or Prednisone 1 mg/kg PO
  • Do NOT wait for temporal artery biopsy to start treatment
• Stroke workup: same as TIA / stroke
  • Dual antiplatelet therapy, statin, carotid imaging
• Consider emergent catheter-directed intra-arterial thrombolysis (tPA) at specialized centers if <6 hours (experimental)

Disposition

• Admit for stroke workup (telemetry, vascular imaging, echocardiography)
• Emergent ophthalmology consultation
• If GCA suspected: admit for IV steroids and temporal artery biopsy within 1-2 weeks
• Treat as stroke equivalent with aggressive risk factor modification

See Also

• Central retinal vein occlusion
• Retinal detachment
• Stroke (main)
• Giant cell arteritis
• Acute angle-closure glaucoma