The patient was a 51 year old woman who presented with a complaint of a central blind spot in the left eye for two months. Her past medical history was remarkable for diabetes, COPD, hypertension, coronary artery disease, hypothyroidism, and bipolar disorder and anxiety. She had ringing in her ears for about ten years, progressive left ear hearing loss, and vertigo. An MRI showed white matter changes, and demyelinating disease was in the differential diagnosis. There was left hand weakness and numbness. Her most recent hemoglobin A1c was 5.1.
Her blood pressure was 118/88. The visual acuity was 20/20 J1+ OD and 20/25 J1+ OS. There was no afferent pupillary defect. On brightness testing, light seemed twice as bright in the right eye as the left. There was mild red desaturation in the left eye, but color vision testing was normal in both eyes. Anterior segment examination was remarkable for a mild nuclear sclerotic cataract in each eye. The posterior segment examination was remarkable for focal sheathing of an arteriole inferotemporal to the disc in the left eye. What is the most likely diagnosis? What treatment, if any, would you recommend?