The ophthalmic veins (latin: venae opthalmicae) are venous blood vessels that drain the orbital cavity. The ophthalmic veins include the superior ophthalmic vein and the inferior ophthalmic vein, and occasionally, the medial ophthalmic vein and the middle ophthalmic vein may be present. The ophthalmic veins connect the facial veins and intracranial veins.
The superior ophthalmic vein is the largest of the ophthalmic veins that arises as the continuation of the nasofrontal vein at the medial corner of the eye. The superior ophthalmic vein 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, the two superior vortex veins of the eyeball, the anterior ethmoidal vein, the lacrimal vein, the medial ophthalmic vein, some muscular veins and occasionally the inferior ophthalmic vein. The superior ophthalmic vein forms an anastomosis with the angular vein - a branch of the facial vein.
The inferior ophthalmic vein arises from a venous network near the anteromedial region of the orbital floor, between the globe and the inferior rectus muscle. The inferior ophthalmic vein passes posteriorly along the superior surface of the inferior rectus, and upon reaching the posterior orbit it gives off small branches that pass through the Mullers orbital 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 and the inferior medial and lateral vortex veins of the eyeball.
The medial ophthalmic vein is occasionally found in the human orbit (30 - 40%). The medial ophthalmic vein 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 in 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 the superior rectus.
The middle ophthalmic vein is a variable vein, presented only in around 20% of individuals. The middle ophthalmic vein begins as a muscular branch 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.