A 64-year-old woman reports an episode of transient visual loss in her left eye. During the episode, when she covered her right eye, she was blind. When she covered her left eye, she could see normally. This phenomenon could have been caused by all of the following, EXCEPT?
Incorrect. Cervical carotid-source embolism would cause acute transient MONOCULAR visual loss, as this patient describes. What answer choice does not meet these criteria?
Correct. Vertebrobasilar-source embolism would cause acute transient BINOCULAR visual loss, a contralateral homonymous hemianopia. This patient is reporting MONOCULAR vision loss. However, be advised that many patients mistakenly report monocular temporal vision loss when they have actually suffered transient homonymous hemianopia! Think of the anterior arterial circulation for MONOCULAR visual loss and the posterior arterial circulation for BINOCULAR visual loss.
Incorrect. Impending occlusion of the optic nerve arterioles would cause acute transient MONOCULAR visual loss, as this patient describes. What answer choice does not meet these criteria?
Incorrect. Vasospasm of retinal arterioles would cause acute transient MONOCULAR visual loss, as this patient describes. What answer choice does not meet these criteria?