Anatomy, Head and Neck: Eye Ophthalmic Vein

The orbital cavity drains via a system of venous blood vessels referred to collectively as the ophthalmic veins. The primary ophthalmic veins are the superior ophthalmic vein (SOV) and inferior ophthalmic vein (IOV). Accessory veins include the medial ophthalmic vein and middle ophthalmic vein, which occur in approximately 40% and 1% to 20% of the population, respectively. The ophthalmic veins anastomose with the facial venous system and drain into the cavernous sinus and intracranial veins (Figure 1). Of the ophthalmic veins, the SOV is the largest caliber with the greatest diameter. It originates in the anterior medial orbit from the junction of the supraorbital, supratrochlear, and angular (a branch of the facial vein) veins medial to the superior rectus muscle insertion and posterior to the trochlea. The SOV then travels posteriorly in a diagonal manner (from medial to lateral) coursing inferior to the superior rectus muscle and superior to the optic nerve and ciliary nerves. Once it reaches the lateral edge of the superior rectus muscle posteriorly, the SOV traverses the superior orbital fissure outside of the annulus of Zinn and drains into the cavernous sinus. The IOV originates as a venous plexus between the globe and the inferior rectus muscle near the anteromedial portion of the orbital floor. The IOV often splits into two branches: one exits the orbit via the inferior orbital fissure to drain into the pterygoid venous plexus while the other exits via the superior orbital fissure to empty into either the SOV or the cavernous sinus directly. The cavernous sinus, a component of the dural venous sinus pathway, drains via the superior and inferior petrosal sinuses and the sigmoid sinus into the internal jugular vein.