What is the posterior five-sixths of middle vascular layer in the eye?

The posterior five-sixths of the middle vascular layer of the eye is known as the choroid. It is a highly vascularized layer located between the retina and the sclera, providing essential nutrients and oxygen to the outer layers of the retina. The choroid contains numerous blood vessels and pigmented cells that help absorb excess light, preventing scattering and enhancing visual clarity.