The vorticose veins, referred to clinically as the vortex veins, drain the ocular choroid. The number of vortex veins is known to vary from 4 to 8 with about 65% of the normal population having 4 or 5. In most cases, there is at least one vortex vein in each quadrant. Typically, the entrances to the vortex veins in the outer layer of the choroid

Choroid

The choroid, also known as the choroidea or choroid coat, is the vascular layer of the eye, containing connective tissue, and lying between the retina and the sclera. The human choroid is thickest at the far extreme rear of the eye , while in the outlying areas it narrows to 0.1 mm...

(lamina vasculosa) can be observed funduscopically and provide an important clinical landmarks identifying the ocular equator. However, the veins run posteriorly in the sclera exiting the eye well posterior to the equator.

Some vortex veins drain into the superior orbital veins and thence to the cavernous sinus. Some vortex veins drain into the inferior orbital vein which drains into the pterygoid plexus. There is usually collateral circulation between the superior and inferior orbital veins.