Retrobulbar optic neuropathy associated with sphenoid sinus mucormycosis

Because fungi usually spread from the paranasal sinuses to the orbital apex in invasive fungal sinusitis (IFS), IFS often presents as an orbital apex syndrome (OAS) characterized by dysfunction of cranial nerves II, III, IV, V1, and VI. We report a case of sphenoid sinus mucormycosis that presented as isolated retrobulbar optic neuropathy. A 94-year-old woman presented with acute blindness in the right eye. Examination revealed the absence of light perception and pupillary reflex in the right eye. Head MRI showed a mass in the right sphenoid sinus, which was contiguous with the right optic nerve. She underwent endoscopic surgery, and a histopathological diagnosis of mucormycosis was established. Treatment with intravenous liposomal amphotericin B reduced the size of the mass. She has survived for more than 1 year without recurrence. Clinicians should consider that IFS can present as isolated retrobulbar optic neuropathy.