A 32-year-old woman with no significant medical history presents to the clinic with visual
complaints. On a recent trip to Arizona, she suffered an acute episode of visual impairment. She
experienced blurred and double vision, which made it difficult for her to drive. On visual
examination, her vision is 20/20 in both eyes. When she is asked to look to the right, her left eye
only reaches midline while her right eye shows a beating nystagmus. Testing for visual
convergence is intact. Based on the clinical history and physical examination, what is the most
likely cause of her complaints?
A. Amaurosis fugax
B. Cataract
C. Multiple sclerosis
D. Optic neuritis
E. Panophthalmitis