Eyes, Ears, Nose and Throatcommon
A 72-year-old woman with hypertension reports three episodes in the past week in which the vision in her right eye became obscured from the top down, each lasting about 5 minutes before returning completely. She has no headache, jaw discomfort or scalp tenderness; visual acuity and fundoscopy are normal between episodes. Which one of the following is the most likely diagnosis?