A 40-year-old man noticed blurred vision in his right eye which lasted 2 days and then improved. Four days later, he had central blurring of vision in his left eye which was noticed upon awakening. This progressed throughout the day until only a small temporal island of vision remained. He had a previous episode of left-sided numbness, weakness and headache 3 months prior, all of which resolved spontaneously. He was referred to the Neuro-Ophthalmology Clinic.

Past medical and surgical history was unremarkable. …