Role of Aspirin Loading in the Treatment of Central Retinal Artery Occlusion
For patients with Central Retinal Artery Occlusion (CRAO), an initial course of dual antiplatelet therapy for 21 days followed by long-term single antiplatelet therapy is reasonable as part of secondary prevention when the cause is cryptogenic or attributed to atherosclerosis. 1
Pathophysiology and Classification
- CRAO is defined as an interruption of blood flow through the central retinal artery by thromboembolism or vasospasm resulting in retinal ischemia, and is classified as part of the central nervous system infarction spectrum, making it a true stroke equivalent 2
- In 95% of cases, CRAO occurs as a result of thromboembolic disease, while in 5% of cases, it occurs as arteritic CRAO, usually as a component of giant cell arteritis 1
- CRAO presents as sudden, painless monocular visual loss with poor natural history - only 17% of patients achieve functional visual acuity in the affected eye without intervention 1
Acute Management
- CRAO should be treated as an ophthalmic and neurological emergency requiring rapid triage to emergency medical care 3, 2
- Immediate ophthalmological examination is necessary to confirm diagnosis and rule out other causes of visual loss 1
- While intravenous tissue plasminogen activator (tPA) may be considered in patients presenting within 4.5 hours of symptom onset, there is no widely accepted therapy for acute CRAO 1
- Conservative treatments such as ocular massage, anterior chamber paracentesis, and hemodilution lack compelling evidence and may be harmful 1
Secondary Prevention with Antiplatelet Therapy
- For patients with CRAO without an indication for anticoagulation or surgery, an antithrombotic therapy regimen similar to that used in cryptogenic ischemic stroke is reasonable 1
- The American Heart Association recommends an initial course of 21 days of dual antiplatelet therapy followed by long-term treatment with a single antiplatelet agent for patients with a presenting National Institutes of Health Stroke Scale score of ≤3 1
- Typical long-term antiplatelet options include aspirin 81 mg daily or clopidogrel 75 mg daily as recommended by current guidelines 1
- The THALES and SOCRATES trials suggest that ticagrelor (either alone or in combination with aspirin) may reasonably form part of pharmacological secondary prevention in patients with transient ischemic attack or minor stroke and thus might be reasonable after CRAO 1
Comprehensive Management Approach
- Secondary prevention should be a collaborative effort between neurology, ophthalmology, and primary care medicine 1
- Risk factor modification should include pharmacological and lifestyle interventions 1
- Treatment of hypertension, dyslipidemia, diabetes, obesity, and obstructive sleep apnea; smoking cessation; implementation of a plant-based diet; and regular physical activity are critical for secondary prevention after CRAO 1
- Urgent etiological workup is essential as it frequently uncovers concurrent disease requiring prompt intervention 1
- High-grade stenosis of the ipsilateral carotid artery should be identified rapidly and treated as symptomatic carotid stenosis 1
- If atrial fibrillation or another cardioembolic source is detected during the diagnostic workup, anticoagulation may be appropriate for secondary prevention instead of antiplatelet therapy 1
Key Pitfalls to Avoid
- Failing to recognize CRAO as a stroke equivalent requiring emergency evaluation 2, 4
- Delaying emergency referral to perform additional testing in the outpatient setting 2
- Missing giant cell arteritis as a potential cause of CRAO 2
- Not conducting a thorough vascular risk factor screening, which is more likely to occur when patients are not routinely referred to an emergency department 4
- Inconsistent approaches to treatment - a national survey found significant variability in treatment practices for acute CRAO in the US, with only 20% of institutions having a formal policy or guideline 4