Purpose: To define the normal and variant venous anatomy in the human orbit.
Methods: Orbital dissections, focusing on the venous system, were performed on 17 formalin-preserved human cadavers (34 orbits) and two fresh orbits. Dissections were carefully documented photographically. Results were compared with those in previous reports on the venous anatomy of the orbit.
Results: The superior ophthalmic vein (SOV) is the most consistent vein within the superior orbit. The inferior ophthalmic vein (IOV) demonstrated more variation, but important variations were noted in both. Smaller veins demonstrated the largest variability. Several formerly published observations on the venous anatomy of the orbit could not be confirmed in this study. A previously unreported variation in the SOV was found in 9 of 36 orbits, with the SOV having a duplicated segment, which is likely to be a variant medial ophthalmic vein.
Conclusions: The venous anatomy of the orbit demonstrates considerable variability. Some of these variations may have implications in surgical management and natural history of ophthalmic conditions, such as carotid-cavernous sinus fistula (CCSF).