This 61YO diabetic male has been followed yearly for routine retinopathy screenings. On 1/27/22, vision was 20/20 with a normal right fundus. Note that the superior periphery is also normal.
On 8/31/22, he returned complaining of a new inferotemporal peripheral scotoma with monocular vertical diplopia in this eye. Vision was 20/20 centrally and 20/20 inferiorly. A new optic nerve and macula had developed in the interim. These findings were confirmed on MRI scanning, which revealed a single nerve OS and two nerves OD in the retro-orbital space.
Learning Points:
Duplication of the optic nerve is a non-heritable developmental abnormality with an extremely low prevalence of about 1 per 23.5 million live births, and is a rare cause of monocular diplopia. To the best of our knowledge, ours is the first such known de novo case.
AND HAPPY APRIL FOOL’S DAY 2023!
