Onodi cell

Axial CT nose and paranasal sinuses showing Onodi air cell marked "O" close to the optic nerve.

Onodi cell is also known as spheno ethmoidal air cell.  This air cell lies posterior and superior to the sphenoid sinus.

This air cell lies close to the optic nerve sheath.  Infections involving this air cell can lead to blindness.  Surgery in this

area can cause blindness if care is not exercised.