MSFinals-3768

MSFinals-3768

A 70-year-old man, with a history of atrial fibrillation, hypertension and type 2 diabetes mellitus, presents to the Emergency Department with a sudden painless loss of vision in his left eye that lasted for a few minutes. He describes the loss of vision as a curtain coming into his vision, and he could not see anything out of it for a few minutes before his vision returned to normal.
Upon examination, his acuity is 6/9 in both eyes. On dilated fundoscopy, there is a small embolus in one of the vessels in the left eye. The rest of the fundus is normal in both eyes.
What is the most likely diagnosis?