Ophthalmic and facial veins are not valveless.

Background: The ophthalmic and facial veins are frequently stated to be devoid of valves, facilitating the spread of infection from the mid-face to the cavernous sinus.
Methods: Twelve superior and eight inferior ophthalmic veins together with 13 angular and facial veins were harvested from adult cadavers. Each vein was opened longitudinally and examined by stereomicroscopy; the number, location and geometry of valve cusps were recorded.
Results: Ten valves were identified in nine (75%) superior ophthalmic vein specimens: four valves were in the superior ophthalmic vein and the remainder were located near its origin from angular and supra-orbital tributaries. No valves were seen in the inferior ophthalmic vein. Seventeen bicuspid valves were identified in tributaries of the angular vein or in the facial vein, but none were in the angular vein itself. Four of seven facial vein segments extending to the lower border of the mandible had valves. The orientation of valve cusps predicted the following blood flow: in the facial vein, inferiorly; in the superior ophthalmic vein, towards the cavernous sinus; and in the angular vein, to the facial or superior ophthalmic vein.
Conclusions: This study demonstrates, for the first time, the existence of valves in the superior ophthalmic vein and its two main tributaries. Valves were also seen in the facial vein. It is not the absence of venous valves but the existence of communications between the facial vein and cavernous sinus and the direction of blood flow that is important in the spread of infection from the face.