Currently there’s little scientific information on appropriate management of central retinal artery occlusion (CRAO), a topic of interest not just to eye doctors but cardiologists and neurologists as well because it may presage future cerebrovascular or cardiovascular events. Observational studies and expert opinion comprise the bulk of knowledge on treatment strategies. The American Heart Association (AHA) conducted a literature review of the condition to form a new framework for considering acute treatment and secondary prevention of this condition. They stated that the literature suggests intravenous administration of a clot-busting agent may be effective.
The review study included randomized controlled clinical trials, prospective and retrospective cohort studies, case-control studies, case reports, clinical guidelines, review articles, basic science articles and editorials on the management of CRAO. The AHA put together a panel of experts in vascular neurology, neuro-ophthalmology, vitreoretinal surgery, immunology, endovascular neurosurgery and cardiology to assess the findings. Each member performed a literature review of their assigned studies to synthesize the data and offer considerations for practice. The panel reviewed multiple drafts until the group had achieved consensus.
Their findings showed that acute CRAO is a true medical emergency and prioritizing early recognition and triage is vital. They noted that there’s “considerable variability in management patterns among practitioners, institutions and subspecialty groups.”
Experts identified tissue plasminogen activator as an effective treatment when circumstances are conducive to administration, as the treatment is highly time-sensitive. “Intravenous tissue plasminogen activator (tPA) is an evidence-based therapy for acute ischemic stroke,” the researchers noted. It’s been known to improve long-term functional outcomes in patients with acute CRAO treated within 4.5 hours of onset, with no evidence of intracranial or systemic hemorrhage.
“The most commonly used agent is alteplase, delivered via an intravenous infusion” at 0.9mg/kg with 10% given over one minute and the remainder over 59 minutes, they explained. Intravenous thrombolytic agents have been used empirically since the 1960s to treat CRAO. The researchers noted that currently only 5.8% of CRAO patients are administered tPA in the United States.
Another possible approach the researchers identified was intra-arterial tPA. “Introducing tPA directly into the ophthalmic circulation via superselective microcatheterization of the ostium of the ophthalmic artery (intra-arterial thrombolysis) has the advantage of directly administering thrombolytic therapy to the thrombus while reducing the risk of intracranial and systemic hemorrhage,” they wrote. “Thus, the dose of tPA reaching the systemic circulation is much lower, so it may be considered in patients with systemic contraindications to intravenous thrombolysis such as recent surgery, gastrointestinal hemorrhage or coagulopathy.” They noted, however, that the reduction in systemic complications may be accompanied by risks of arterial dissection, catheter-induced spasm and dislodgement of atheromatous plaque in the ophthalmic circulation, with the possibility of distal embolization.”
A more conservative approach involves using hyperbaric oxygenation therapy to salvage retinal tissue in acute CRAO. They explained, “In normal physiology, >50% of the retinal oxygen supply is derived from passive diffusion from the choroidal circulation, whereas with hyperbaric oxygenation, it’s as high as 97%. Several case series suggest that hyperbaric oxygenation therapy improves visual outcome in CRAO.” This approach may provide a temporizing measure while definitive reperfusion is pursued; however, it’s not believed to promote reperfusion itself. This method has a low risk of systemic complications and hasn’t been shown to increase intracranial or systemic hemorrhage.
Secondary prevention should be guided by multidisciplinary collaboration, the researchers suggested. This team might include a neurologist, an ophthalmologist and a primary care physician or internist. They also recommend seeking treatment for 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 and should follow established professional guidelines for cerebral ischemic stroke,” the researchers wrote. Ischemic stroke guidelines don’t currently mention CRAO, but it is formalized in the AHA’s definition.
The AHA panel concluded that there is no widely accepted therapy, but patients are advised to undergo urgent screening and treatment of any vascular risk factors they may have. They also propose more high-quality, randomized clinical trials for emerging treatments for the condition.
Mac Grory B, Schrag M, Biousse V, et al. Management of central retinal artery occlusion: A scientific statement from the American Heart Association. Stroke. March 8, 2021. [Epub ahead of print].