Pop quiz: What's the diagnosis for this 64-year-old man?

A 64-year-old man with hypertension developed sudden onset of right eye blindness while shaving this morning. He describes a "curtain falling over my right eye," which cleared spontaneously after 8 minutes. He had no other concurrent neurologic symptoms and no prior episodes of similar description. His general examination reveals a blood pressure of 140/87 mmHg but is otherwise unremarkable. Neurologic exam is grossly normal.

What is the most likely diagnosis? (Hint: think about what route the tiny embolus will take to give these symptoms!)

A Right internal carotid artery transient ischemic attack (TIA)
B Basilar artery TIA
C Left Posterior cerebral TIA
D Left Internal carotid artery TIA

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Answer:  A. Here's why: The Right Retinal artery runs off the Right Internal Carotid!