Optic neuropathy produced by a compressed mucocele in an Onodi cell.

Objective: To describe a patient with compressive optic neuropathy caused by a mucocele in an Onodi cell.

Methods: Interventional case report. Methods: A 73-year-old man complained of sudden visual loss in the left eye 10 days after cataract surgery. Coronal computed tomography showed a homogeneous mass in an Onodi cell. Magnetic resonance imaging revealed an oval-shaped lesion that compressed the left optic nerve.

Results: After endoscopic microsurgery of the paranasal sinus, visual acuity in the left eye improved. Histopathological examination of the excised specimen showed a mucocele.

Conclusions: Ophthalmologists should be aware that the mucocele in the Onodi cell, an anatomical variation of the paranasal sinus, may compress the optic nerve.