A fistula of the lesser sphenoid wing sinus is a rare dural arteriovenous fistula resulting from a connection between the middle meningeal artery and recipient vein in the sinus of the lesser sphenoid wing. In this report, MRI/magnetic resonance angiography of a 54-year-old man who presented with sudden-onset glaucoma and proptosis revealed a fistula in this anatomic location. Drainage patterns here may account for the absence of serious complications and optimistic prognosis following embolization. Care in diagnosis is required to avoid superfluous procedures, because classic signs of the more common carotid-cavernous fistula are absent.