Optic nerve/sheath enlargement. A differential approach based on high-resolution CT morphology.

A wide variety of neoplastic and non-neoplastic processes can cause the intraorbital optic nerve and sheath to be enlarged on CT. The authors reviewed a large number of high-resolution CT scans and divided enlargement into three groups: tubular, fusiform, and excrescent. Further subdivision was possible by determining whether distinct optic nerve lucency was present or absent.