What is the workup for acute retinal arterial ischemia?

Acute Retinal Arterial Ischemia Workup

Patients with acute retinal arterial ischemia must be immediately referred to the nearest stroke center or emergency department for urgent evaluation, as this represents both an ocular and systemic emergency with high risk of subsequent stroke within the first 7 days after symptom onset. 1

Initial Evaluation by Eye Care Provider

1. Establish diagnosis and rule out giant cell arteritis:

   • Confirm diagnosis of retinal arterial ischemia (TMVL, BRAO, or CRAO)
   • Consider giant cell arteritis in patients >50 years (especially Caucasians)
   • Inquire about systemic symptoms of GCA (headache, jaw claudication, scalp tenderness)
   • If GCA is suspected, order immediate ESR and CRP 2, 1

2. Immediate referral:

   • Send patient immediately to nearest emergency department affiliated with a certified stroke center
   • Include referral note indicating "Ocular TIA" or "Ocular Stroke"
   • Call the center to alert them that "a stroke patient is on the way" 2
   • Inform patient about stroke risk and importance of immediate evaluation 2

Stroke Center Workup

1. Neuroimaging:

   • Brain MRI with diffusion-weighted imaging (DWI) - can detect silent brain infarcts present in approximately 20% of patients 1, 3
   • Vascular imaging to evaluate carotid and cerebral vessels:
     • Carotid ultrasound
     • CT angiography (CTA)
     • MR angiography (MRA) 1

2. Cardiac evaluation:

   • ECG
   • Cardiac monitoring
   • Echocardiography (to evaluate for cardioembolic sources) 1, 4

3. Laboratory tests:

   • Complete blood count
   • Coagulation profile
   • Lipid panel
   • ESR and CRP (especially if GCA suspected)
   • Blood glucose 1

4. Ophthalmic evaluation:

   • Fluorescein angiography may be considered 1
   • Monitor for development of iris or retinal neovascularization 1

Management Considerations

1. Acute interventions (limited evidence for efficacy):

   • Consider intravenous thrombolysis (tPA) if within appropriate time window
   • Hyperbaric oxygen therapy may be considered in select cases
   • Initial treatments such as digital massage, anterior chamber paracentesis, and breathing into a paper bag have limited evidence 1

2. Secondary prevention:

   • Antiplatelet therapy should be started without delay in patients seen days after the episode 2
   • Management of modifiable cardiovascular risk factors
   • Appropriate treatment based on identified etiology (e.g., carotid stenosis, cardiac source) 4

Important Caveats and Pitfalls

• Time sensitivity: Delay in referral decreases chance of good outcome by 8-14% for every 30-minute delay 1
• Retinal viability window: Experimental studies show progressive ischemic damage after 97 minutes, with irreversible damage by 4 hours 5
• High stroke risk: Up to 24% of patients with CRAO have concurrent cerebrovascular accident on MRI 1
• Systemic implications: Up to 70% of patients with CRAO have significant cardiovascular conditions 1
• Varied clinical entities: CRAO and BRAO comprise multiple distinct clinical entities with different prognoses and management approaches 5

Remember that acute retinal arterial ischemia is the ocular equivalent of acute cerebral ischemia and requires the same urgency in evaluation and management to prevent further vascular events such as stroke and myocardial infarction 4.