From the Guidelines
Central retinal artery occlusion (CRAO) presents as sudden, painless, severe vision loss in one eye, typically described as a "curtain coming down," with a relative afferent pupillary defect and a cherry-red spot in the macula surrounded by retinal whitening on examination, requiring immediate emergency treatment within a narrow treatment window of 4-6 hours. The condition is an ocular stroke that necessitates prompt intervention to restore blood flow to the retina. Patients often have counting fingers vision or worse, and the condition is associated with a high risk of recurrent vascular events 1.
Clinical Presentation
The clinical presentation of CRAO includes:
- Sudden, painless, severe vision loss in one eye
- Relative afferent pupillary defect
- Cherry-red spot in the macula surrounded by retinal whitening on examination
- Counting fingers vision or worse
- Possible history of transient monocular vision loss or other vascular events
Treatment Options
The treatment options for CRAO include:
- Ocular massage
- Anterior chamber paracentesis
- Intraocular pressure lowering medications like acetazolamide 500mg IV or oral, timolol 0.5% drops, or brimonidine 0.2% drops to dislodge the embolus
- Breathing into a paper bag or carbogen therapy (95% oxygen, 5% carbon dioxide) to dilate the retinal artery
- Hyperbaric oxygen therapy within 24 hours
- Thrombolytic therapy with tissue plasminogen activator (tPA) in select cases within 4.5 hours of symptom onset, as recommended by the American Heart Association 1
- Long-term management includes antiplatelet therapy (aspirin 81-325mg daily), statins, and addressing modifiable cardiovascular risk factors to prevent further vascular events, as emphasized in the management guidelines for CRAO 1.
Importance of Prompt Treatment
Prompt treatment is crucial in CRAO, as the condition has a narrow treatment window of 4-6 hours, and delayed treatment can result in permanent vision loss 1. The American Heart Association recommends a thorough cardiovascular workup, including carotid ultrasound, echocardiogram, and blood tests for hypercoagulable states, to identify underlying systemic vascular disease and prevent further vascular events 1.
From the Research
Clinical Presentation of Central Retinal Artery Occlusion
- Patients with central retinal artery occlusion (CRAO) typically present with acute, painless loss of vision in one eye 2, 3.
- The condition can be classified into four distinct clinical entities: non-arteritic CRAO, transient non-arteritic CRAO, non-arteritic CRAO with cilioretinal artery sparing, and arteritic CRAO 4.
- Clinical characteristics, visual outcome, and management vary depending on the type of CRAO 4.
- Spontaneous improvement in visual acuity and visual fields can occur, mainly during the first 7 days, with significant differences in the incidence of improvement among the four types of CRAO 4.
Treatment Options for Central Retinal Artery Occlusion
- Timely diagnosis and treatment are crucial to prevent irreversible loss of vision, with a window of opportunity for treatment being within 6 hours from symptom onset 5.
- Thrombolysis within 6 hours from symptom onset has shown benefit in subset analyses from two large studies of patients with CRAO 5.
- However, recent studies have also shown that administration of local intra-arterial thrombolytic agent may have no beneficial effect and can be harmful 4.
- Point-of-care ultrasound (POCUS) can be used to rapidly diagnose CRAO, utilizing the retrobulbar 'spot sign' (RBSS) to reveal a hyperechoic density in the optic nerve sheath just proximal to the retinal surface 3.
Importance of Early Diagnosis and Treatment
- Early ophthalmologic involvement is essential for potential vision restoration, and a thorough history and physical are crucial for all patients with ocular complaints 2.
- Comprehensive stroke centers can serve as ideal triage centers for patients with CRAO, given the availability of multidisciplinary participation from vascular neurology, neuroendovascular surgery, and ophthalmology 5.
- The approach to acute ocular ischemia should mimic that used for acute brain ischemia, with the mantra "Time is Retina!" emphasizing the importance of prompt treatment 5.