What are the diagnosis and treatment for central retinal artery occlusion (CRAO)?

Central Retinal Artery Occlusion: Diagnosis and Treatment

Central retinal artery occlusion is diagnosed clinically by sudden, painless monocular vision loss with funduscopic findings of retinal whitening and a cherry red spot, and should be treated as a stroke equivalent with immediate emergency department triage for consideration of intravenous tPA within 4.5 hours if the patient meets systemic thrombolysis criteria. 1, 2

Diagnosis

Clinical Presentation

• Sudden, painless monocular vision loss occurring over seconds is the hallmark presentation, with over 80% of patients presenting with visual acuity of "count fingers" or worse 1, 2
• The diagnosis is made based on compelling clinical history supported by the presence of a relative afferent pupillary defect (Marcus Gunn pupil) and classic funduscopic findings 1

Funduscopic Examination Findings

An ophthalmological examination including funduscopy is necessary for diagnosis and reveals: 1, 2

• Retinal whitening (diffuse retinal edema)
• Cherry red spot at the fovea (where the thin retina allows visualization of the underlying choroidal circulation)
• Attenuated retinal arteries with "boxcar" segmentation of blood flow
• Possible visible emboli in retinal vessels

Critical Differential Diagnosis Exclusions

The funduscopic examination is essential to rule out: 1

• Intraocular hemorrhage (vitreous or retinal)
• Retinal detachment
• Ischemic optic neuropathy (most commonly anterior ischemic optic neuropathy)

Urgent Screening for Giant Cell Arteritis

• 5% of CRAO cases are arteritic, usually from giant cell arteritis (GCA), requiring immediate recognition 1
• Screen for GCA symptoms: jaw claudication, temporal headache, scalp tenderness, polymyalgia rheumatica symptoms 1
• If GCA is suspected, obtain ESR/CRP and initiate immediate high-dose corticosteroids before biopsy to prevent fellow eye involvement 2, 3

Acute Treatment

Immediate Triage

• Triage immediately to the nearest emergency department upon diagnosis—do not delay for outpatient evaluation or other treatments 1
• CRAO is formally recognized as an acute ischemic stroke by the American Heart Association 1, 2, 3
• The risk of concurrent or subsequent cerebral stroke is 3-6% within 1-4 weeks, with 20-24% having concurrent acute brain infarction on MRI 2

Thrombolytic Therapy Considerations

Intravenous tPA:

• May be considered in patients with disabling visual deficits presenting within 4.5 hours who otherwise meet criteria for systemic tPA after thorough benefit/risk discussion 1
• This recommendation comes despite limited evidence, given the devastating natural history (only 17% achieve functional visual recovery without intervention) 1, 3
• The standard stroke code protocol should be followed: immediate ophthalmological examination parallel to neurological assessment (NIH Stroke Scale), non-contrast head CT, and screening for contraindications 1

Intra-arterial tPA:

• In centers capable of endovascular therapy, intra-arterial tPA may be considered at early time points in patients with disabling visual deficits, especially if not candidates for IV tPA 1
• This comes with the strong caveat that intra-arterial therapy is currently unproven and should only be considered given the devastating visual outcome associated with CRAO 1
• Technical challenges include cannulation of the small ophthalmic artery and increased difficulty in the presence of atherosclerosis 1

Conservative Treatments to AVOID

There is no compelling evidence that conservative treatments are effective, and observational literature suggests the following may be harmful: 1, 3

• Ocular massage
• Anterior chamber paracentesis
• Hemodilution
• Topical intraocular pressure-lowering agents

Secondary Prevention

Etiological Workup

Since 95% of CRAO cases result from thromboembolic disease, perform: 1, 3

• Carotid imaging (ultrasound, CTA, or MRA) to identify ipsilateral carotid stenosis
• Cardiac evaluation including ECG, telemetry monitoring, and echocardiography to detect atrial fibrillation or other cardioembolic sources
• Vascular risk factor assessment

Antiplatelet Therapy

For patients without indication for anticoagulation or surgery: 3

• Initial 21 days of dual antiplatelet therapy (aspirin plus clopidogrel or ticagrelor) for patients with NIH Stroke Scale ≤3, following the approach used in cryptogenic ischemic stroke 3
• Long-term single antiplatelet agent: aspirin 81 mg daily OR clopidogrel 75 mg daily 3

Anticoagulation

• If atrial fibrillation or cardioembolic source is detected during workup, anticoagulation is appropriate for secondary prevention instead of antiplatelet therapy 1, 3

Carotid Intervention

• Severe stenosis of the ipsilateral carotid artery should be treated as symptomatic carotid stenosis and may require surgical intervention (carotid endarterectomy or stenting) 1, 3

Risk Factor Modification

Comprehensive management includes: 1, 3

• Treatment of hypertension, dyslipidemia, diabetes, obesity, and obstructive sleep apnea
• Smoking cessation
• Plant-based diet and regular physical activity
• These interventions should follow established stroke prevention guidelines

Multidisciplinary Follow-up

Secondary prevention requires collaborative effort between: 1, 3

• Neurology: determine etiology, initiate pharmacological secondary prevention
• Ophthalmology: optimize residual vision, monitor for neovascularization complications (occurs in up to 15% of cases), preserve contralateral eye health
• Primary care: control modifiable risk factors

Critical Pitfalls to Avoid

• Do not delay emergency department referral for outpatient ophthalmology evaluation—time is retina 1
• Do not use conservative treatments (ocular massage, paracentesis) as they may be harmful and delay definitive care 1, 3
• Do not miss giant cell arteritis—failure to recognize and treat arteritic CRAO can result in fellow eye involvement 1, 2
• Do not forget stroke workup—CRAO is a stroke equivalent requiring full neurovascular evaluation 1, 2, 3