Bilateral Compressive Optic Neuropathy Secondary to Sphenoid Sinus Mucocele Mimicking Bilateral Retrobulbar Neuritis.

Sphenoid sinus mucoceles (SSMs) can rarely cause acute bilateral vision loss. We, hereby, report such a rare case of SSM in a 20-year-old female who presented with sudden onset bilateral diminution of vision. The best-corrected visual acuity was 20/400 in the right eye (RE) and hand movements in the left eye (LE). Both eyes had sluggish pupillary reactions. Both eyes had normal fundus. Initial treatment was started with a provisional diagnosis of bilateral retrobulbar neuritis, but imaging revealed a large SSM compressing bilateral optic nerves. The patient underwent urgent surgical decompression. Vision in RE improved to 20/20 and LE to 20/400. A high index of clinical suspicion for compressive lesions is needed in all cases of atypical optic neuritis.