The outer layer of the choroid (lamina vasculosa) consists, in part, of the larger branches of the short ciliary arteries which run forward between the veins, before they bend inward to end in the capillaries, but is formed principally of veins, named, from their arrangement, the vorticose veins. They converge to four or five equidistant trunks, which pierce the sclera about midway between the sclero-corneal junction and the entrance of the optic nerve. They drain uveal tract. [ http://en.wikipedia.org/wiki/Vorticose_veins ]