Presumed optic nerve sheath meningioma diagnosed after complicated retrobulbar anesthesia.

We present a patient who developed acute visual loss and light flashes at retrobulbar anesthesia for cataract extraction. Vision improved only slightly after cataract surgery. Although traumatic optic neuropathy was suspected, the patient was diagnosed one year later with an optic nerve sheath meningioma (ONSM). ONSM is a rare, slow growing, benign tumour with highly variable clinical features. Diagnosis is often delayed. This case report demonstrates the diagnostic difficulty of this tumour.