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Retinal Occlusion, Ischemic Stroke, and the Brain-Eye Connection

  • Eric R. Eggenberger
    Correspondence
    Correspondence: Address to Eric R. Eggenberger, DO, Departments of Ophthalmology, Neurology, and Neurosurgery, Mayo Clinic, 4500 San Pablo Rd, Jacksonville, FL 32224.
    Affiliations
    Departments of Ophthalmology, Neurology, and Neurosurgery, Mayo Clinic, Jacksonville, FL
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      The risk of cerebral infarction associated with retinal ischemia has been the subject of an evolving debate. Several factors complicate this association, including varied types of ischemic visual events ranging from transient monocular visual loss to anterior ischemic optic neuropathy and retinal artery occlusion (branch or central); additionally, diagnostic and therapeutic options for cerebral ischemia continue to advance.
      Earlier reports highlighted a more benign prognosis after transient monocular visual loss, perhaps most clearly vocalized by the North American Symptomatic Carotid Endarterectomy Trial study in which patients with transient monocular visual loss had a stroke risk approximately half the rate after a hemispheric transient ischemic attack.
      • Benavente G.J.
      • Eliasziw M.
      • Strefler J.Y.
      • Fox A.J.
      • Barnett H.J.M.
      • Meldrum H.
      for the North American Symptomatic Carotid Endarterectomy Trial Collaborators
      Prognosis after transient monocular blindness associated with carotid artery stenosis.
      This result may seem counterintuitive to the school of thought that regards ocular structures as a component of cerebral tissue. However, there are several potential reasons for this apparent paradox, including the possibility of misclassification of nonischemic transient visual loss as an ischemic event or a more benign local mechanism accounting for transient visual symptoms such as retinal vasospasm.
      Retinal artery occlusion represents a more precisely defined diagnosis, thereby affording less diagnostic uncertainty and, accordingly, reducing the risks of misdiagnosis and misclassification. Such diagnostic precision regarding central retinal artery occlusion is a substantial strength when central retinal artery occlusion is used to study the relationship between retinal and subsequent brain ischemia because this investigative approach improves the reliability and accuracy of the resulting data. Previous studies document a gradient of increased risk concerning concomitant magnetic resonance imaging–demonstrable diffusion-weighted imaging abnormalities from transient monocular visual loss to branch retinal artery occlusion to central retinal artery occlusion.
      • Biousse V.
      • Nahab F.
      • Newman N.J.
      Management of acute retinal ischemia: follow the guidelines!.
      Reports using insurance-generated data suggest approximately a 3% and 5% stroke risk at 2 and 4 weeks, respectively, after central retinal artery occlusion.
      • Park S.J.
      • Choi N.K.
      • Yang B.R.
      • et al.
      Risk and risk periods for stroke and acute myocardial infarction in patients with central retinal artery occlusion.
      • Chang Y.S.
      • Jan R.L.
      • Weng S.F.
      • et al.
      Retinal artery occlusion and the 3-year risk of stroke in Taiwan: a nationwide population-based study.
      It is on this evolving background that Chodnicki et al
      • Chodnicki K.D.
      • Pulido J.S.
      • Hodge D.O.
      • Klaas J.P.
      • Chen J.J.
      Stroke risk before and after central retinal artery occlusion in a US cohort.
      review the recent Mayo Clinic experience with central retinal artery occlusion and the risk of associated cerebral ischemia. Although subject to limitations inherent to the retrospective methodology, including nonuniform patient evaluations, this excellent study has numerous strengths including sample size and case ascertainment. Overall, these authors noted a 5% risk of symptomatic ischemic stroke in 15 days before and after a central retinal artery occlusion. An embolic source for retinal ischemia was associated with a higher risk of cerebral ischemia. It should be noted, however, that the subpopulation with an embolic source for retinal ischemia was enriched primarily by participants with ipsilateral carotid stenosis, and such subjects are at a relatively increased risk of cerebral ischemia.
      Chodnicki et al have undertaken an important study that significantly contributes to the field in at least 2 major ways. First, this study provides firm and timely evidence attesting to the close connection between retinal and cerebral ischemia. Second, this study underscores the need for an emergent management strategy for patients presenting with retinal ischemia. Current guidelines emphasize an emergent management approach akin to a “stroke alert,” including the performance of appropriate laboratory and other diagnostic tests to identify vasculitis, thrombotic factors, and relevant cardiac disease, along with pertinent neuro-imaging (preferably magnetic resonance imaging with diffusion-weighted imaging) and vascular imaging studies. This is often most expeditiously actualized under the direction of an experienced stroke service.
      • Powers W.J.
      • Rabinstein A.A.
      • Ackerson T.
      • et al.
      American Heart Association Stroke Council. 2018 guidelines for early management of patients with acute ischemic stroke: a guideline for healthcare professionals from the American Heart Association/American Stroke Association.
      This important and timely report highlights the brain-eye connection concerning vascular disease and underscores, in particular, the clinical and therapeutic ramifications of this connection.

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        • Fox A.J.
        • Barnett H.J.M.
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        Prognosis after transient monocular blindness associated with carotid artery stenosis.
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        Management of acute retinal ischemia: follow the guidelines!.
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