choroid

Definition of choroid
National Cancer Institute

choroid

(KOR-oyd)
A thin layer of tissue that is part of the middle layer of the wall of the eye, between the sclera (white outer layer of the eye) and the retina (the inner layer of nerve tissue at the back of the eye). The choriod is filled with blood vessels that bring oxygen and nutrients to the eye.

Source: NCI Dictionary of Cancer Terms