A 36-year-old woman presents with a complaint of rapid decrease of vision in the left eye and pain associated with movement of the left eye. She states that it is “very hard to read or see the computer screen”. She reports no prior medical history and she takes no medications. She denies any recent fevers, chills, nausea, vomiting, diarrhea, numbness, tingling, shortness of breath, cough, chest pain, rashes or arthralgias. Her best-corrected visual acuity is 20/20 in the right eye and 20/70 in the left eye. She has an APD in the left eye with a positive red desaturation test. Anterior and posterior segment examinations are unremarkable in both eyes. Her visual fields are shown above.