Ophthalmic veins

The ophthalmic veins (Latin: venae opthalmicae) are venous blood vessels that drain the orbits. The ophthalmic veins include the superior ophthalmic vein and the inferior ophthalmic vein. Occasionally, the medial ophthalmic vein and the middle ophthalmic vein may be present. The ophthalmic veins connect the facial veins with intracranial veins.

The superior ophthalmic vein is the largest ophthalmic vein and it arises as the continuation of the nasofrontal vein at the medial corner of the eye. This vessel passes posteriorly just medial and inferior to the superior oblique muscle, then runs through the superior orbital fissure, and ends in the cavernous sinus.

On its course, the superior ophthalmic vein receives the following tributaries: the central vein of the retina, two superior vortex veins of the eyeball, anterior ethmoidal vein, lacrimal vein, medial ophthalmic vein, some muscular veins, and, occasionally, the inferior ophthalmic vein. The superior ophthalmic vein forms an anastomosis with the angular vein, which continues as the facial vein.

The inferior ophthalmic vein arises from a venous network near the anteromedial region of the orbital floor, between the eyeball and the inferior rectus muscle. The vessel passes posteriorly along the superior surface of the inferior rectus. Upon reaching the posterior aspect of the orbit, it gives off small branches that pass through the Muller's orbital muscle (superior tarsal muscle) within the inferior orbital fissure and empty into the pterygoid venous plexus.

Further, the inferior ophthalmic vein runs superiorly around the lateral rectus to join the superior ophthalmic vein, and empties into the cavernous sinus. On its course, the inferior ophthalmic vein receives several tributaries: veins from the inferior rectus, inferior oblique, the nasolacrimal sac, eyelids, as well as the inferior medial and lateral vortex veins of the eyeball.

The medial ophthalmic vein is occasionally found in the human orbit (30 - 40%). It begins in the superomedial surface of the orbit from branches of the superior ophthalmic and angular veins. The medial ophthalmic vein passes along the superomedial orbital wall within the extraconal orbital compartment. Further, it rejoins with the superior ophthalmic vein or empties directly into the cavernous sinus. On its course, the medial ophthalmic vein receives tributaries from the medial rectus and superior rectus muscles.

The middle ophthalmic vein is a variable vein, presented only in around 20% of individuals. It begins as a muscular branch arising from the vein of the medial rectus. The middle ophthalmic vein passes posteriorly and drains into the inferior ophthalmic vein, or directly into the cavernous sinus. On its course, the middle ophthalmic vein receives tributaries from the collateral veins.