Osteoma is the most common benign tumour of the nose and paranasal sinuses. However, involvement of the sphenoid sinus by osteoma is rare. Most of the time, patients with paranasal sinus osteoma are asymptomatic. However, symptoms may present, depending on the location and extension of the tumour. We report a case of a patient with sphenoethmoidal osteoma found incidentally on imaging, with evidence of impingement onto the optic nerve at the optic canal. However, the patient was asymptomatic. He was surgically treated using the endoscopic transnasal approach.