Abstract 116: Reversal of Acute Ocular Ischemic Syndrome Following Rescue Carotid Revascularization: A Case Report
Authors: Pillai Abhiram Parameswaran 
Published: March 2024

Introduction
Ocular ischemic syndrome (OIS) is a rare, vision‐threatening condition resulting from severe carotid artery disease secondary to severe atherosclerosis or arteritis. Common clinical features include acute/subacute to gradual vision loss, ocular pain, amaurosis fugax, photophobia and diplopia. We are presenting a case of acute ocular ischemic syndrome secondary to acute re‐occlusion of the right internal carotid artery (RICA) post Carotid Endarterectomy (CEA), that reversed with carotid revascularization.

Methods
Case Summary: 59‐year‐old male with history of T2DM, hyperlipidemia, tobacco use presented to an outside hospital with complaints of dizziness, blurry vision, left upper extremity weakness and multiple falls with head trauma. Exam revealed left lower quadrantanopia, mild left arm weakness and left hemineglect. Computed Tomography (CT) Head showed scattered right middle cerebral artery (MCA) territory infarcts. CT Angiography (CTA) revealed ulcerated plaque with a small focus of thrombus intraluminally in the RICA. Subsequently, the patient was initiated on heparin infusion and underwent CEA. On postoperative day (POD) 2, the patient experienced severe stabbing right eye pain with reduced visual acuity and worsening of left arm weakness. Imaging revealed complete occlusion of the right common carotid artery (RCCA). Perfusion imaging did not reveal a core or a penumbra. Given acute loss of vision likely secondary to ocular ischemic syndrome, decision was taken to proceed with rescue stenting. Using a transfemoral approach, an 8‐French balloon guide catheter was advanced into the proximal RCCA. A primary suction thrombectomy was performed under proximal flow arrest. After achieving a complete recanalization in one pass, we started the patient on cangrelor 30 mcg/kg intravenous bolus followed by 4 mcg/kg/min infusion. Post bolus, we placed a tandem closed‐cell carotid stent measuring 8x36mm & 10x37mm. The patient reported immediate relief of ocular pain, vision and weakness following the procedure. He transitioned from cangrelor infusion to ticagrelor 90 mg twice daily and aspirin 81 mg daily. On post‐stenting day 7, the patient experienced acute onset headache, and imaging revealed re‐occlusion of the entire carotid artery sparing only the ophthalmic segment of the RICA which now filled retrograde via anterior communicating artery (AcoA) from the contralateral carotid artery. However, his visual acuity remained unchanged and reported no ocular pain. At one month follow‐up the patient remains symptom‐free.

Results
Discussion: Incidence of OIS is estimated to be 7.5 cases per million every year. Carotid artery atherosclerosis is the most common etiology. Majority of OIS (∼90%) present with gradual vision loss and approximately 40% present with ocular pain. Gradual vision loss is predominantly related to chronic ocular hypoperfusion and resultant iris neovascularization and glaucoma. In this case, patient suffered acute vision loss secondary to acute ICA occlusion following CEA. Emergent carotid revascularization resulted in restoration of vision and resolution of ocular pain.

Conclusion
Our main goal is to emphasize the importance of rescue stenting to address symptoms of aOIS. Immediately post‐stenting, there was remarkable improvement in ocular pain and visual acuity. Although, the carotid re‐occluded within seven days post‐stenting, we hypothesize that gradual re‐occlusion while on DAPT provided enough time recruit and preserve collaterals into the right ophthalmic artery via retrograde flow into the ophthalmic segment of RICA from the contralateral carotid artery via the AcoA which was subsequently confirmed on imaging.