Circulus arteriosus major

Circulus arteriosus major, also called "major circulus arteriosus of iris" CIA or CIAM, is formed by anastomosis of the anterior ciliary arteries with the Long posterior ciliary arteries at the ciliary body. It supplies the iris, ciliary body and choroid.
The veinous drainage of CIA is : 4 vortex veins that drain into the ophthalmic vein.