Our patient is a 67-year-old woman with a PMH of anxiety, depression, GERD, and mitral valve repair. She was in a usual state of health on the night prior going to bed at 3 am. The next morning she awoke at 9 am with left eye vision loss except for a small crescent of vision in her central vision. She denied eye pain, headache, trauma. She denied temporal artery tenderness, headaches, or jaw claudication. No prior history of glaucoma. Emergent ophthalmologic and stroke neurology consultation confirmed a diagnosis of left Central Retinal Artery Occlusion (CRAO) with macular sparing (Figure 1A-Fundoscopic OS Pre-tPA). Emergent consultation for interventional therapy was requested. 

NEURO-INTERVENTIONAL THERAPY AND HYPERBARIC OXYGEN THERAPY
Dr. Sundeep Mangla performed emergent angiography of the left internal carotid artery and left ophthalmic artery, demonstrating normal origin of the ophthalmic artery with a poor choroidal blush confirming the diagnosis of retinal ischemia (Figure 2, A+B). Superselective angiography of the ophthalmic artery was performed followed by intra-arterial infusion of tPA at a concentration of 0.4 mg/cc for a total dose of 4 mg over 5-7 minutes. The patient reported significantly improved vision immediately after IA tPA therapy, with persistent lateral field cut. The patient then received post interventional hyperbaric oxygen therapy (2.0 – 2.6 atmospheres, 90-120 mins duration) for 4 sessions starting within 12 hours of diagnosis and treatment. A follow-up fundoscopic examination demonstrates improved perfusion of the retinal branches (Figure 1A and 1B, immediate and 2 days post fundoscopic). MRI of the brain confirmed an embolic source of the CRAO, with additional small diffusion positive strokes within the left hemisphere. She was discharged home with significantly improved vision in the left eye for continued outpatient therapy and management.
Figure 1A: OS A. CRAO pre tPA 
Figure 1B: OS B. 30 mins post IA tPA demonstrates improved perfusion and branching vessels of retina
SUMMARY AND DISCUSSION
Central Retinal Artery Occlusion (CRAO) represents on neuro-ophthalmologic emergency, which can lead to irreversible retinal damage secondary to ischemia of a terminal vessel (without collaterals). It is characterized by a sudden, unilateral and painless loss of vision. Embolism is the most common cause of CRAO, the major source of which is carotid artery disease. The natural history for spontaneous recovery or improvement with conservative measures (including paracentesis, acetazolamide, anticoagulation and/or antiplatelets) remains poor, ranging from 20-30% for some measures of functional visional improvement. In studies comparing selective thrombolysis with conservative therapy, Schmidt et al. reported 58% of the interventional therapy group compared with 29% of the control group demonstrated partial improvement in visual acuity, with 77% vs. 26% if treated within 6 hours.1 Additional studies delivering lower doses of tPA within 4 hours of onset published by Aldrich and colleagues demonstrated significant improvement in visual acuity (at least 1 line on the Snellen chart) in 76% of patients receiving intra-arterial therapy versus 33% of patients in the control group. The Interventional group was 13 times more likely to have improvement in visual acuity of 3 lines or more and 4.9 times more likely to have a visual acuity of 20/200 or better.2 Although limited due to the heterogeneity of the presentations and therapeutic regimens applied, early experiences suggest opportunities for improved outcomes.
Figure 2. A. Left ICA Angiogram CRaO; B. Selective infusion 4 mg tPA; C. Post IA tPA
(OA-Ophthalmic Artery, CRA-Central Retinal Artery, CB-Choroidal Blush, PCA-Posterior Ciliary Artery)
Hyperbaric oxygen therapy (HBOT) has been associated with visual improvement in retrospective studies.3 HBOT can maintain oxygenation of the retina through the choroidal blood supply, decrease edema and preserve compromised tissue adjacent to ischemic area. Important key factors for improvement include early therapy (<4-12 hours), degree of vessel occlusion, type of vessel occluded and presence of an adequate PaO2 of oxygen.4

Our patient experienced the most severe form of CRAO with complete vision loss with only light perception. Despite this critical presentation, with a combination of early Neurointerventional therapy with intra-arterial thrombolysis directed to provide primary revascularization and Hyperbaric oxygen therapy to improve collateral and retinal perfusion, she was able to achieve early functional visual improvement of movement, objects, and color in his lateral fields. CRAO represents an ocular emergency with devastating outcomes. Poor outcomes are more commonly observed with delayed presentation, complete vision loss, and conservative management. Early recognition and potential multi-disciplinary treatment plans may offer patients an opportunity for improved functional outcomes and restoration of vision for these ophthalmologic emergencies and impending strokes of the eyes.
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