Young man presents with subacute binocular diplopia

A 22-year-old otherwise healthy man was referred to the New England Eye Center by his primary care physician for 1 to 2 months of intermittent binocular diplopia. He described that his vision had “not felt right” for the last few months. The doubling seemed to occur mostly at night and when he was tired. Subjectively he also felt the acuity was mildly worse in the right eye. His last eye exam was 10 years prior without any reported significant findings. He denied any headaches, flashes or floaters. He had no recent illness or trauma. His medical and family history was unremarkable.The patient’s best corrected visual acuity was 20/20-1 in the right eye and 20/20 in the left eye. Pupils were equal, round and briskly reactive with no afferent pupillary defect. Extraocular movements were significant only for a small left hypertropia that was comitant in all gazes. Ishihara color vision testing was full, and IOPs were within normal limits. On slit lamp biomicroscopy, anterior segment examination was normal with no evidence of inflammation. Fundus exam in the right eye revealed a large irregular elevated peripapillary white mass with fine visible internal vasculature and adjacent retinal striae. There was no visible vitritis, hemorrhage or exudate (Figure 1). Peripheral retinal exam was unremarkable, and left posterior segment was normal.