Book of the Ten Treatises of the Eye the sclera, a thick, hard membrane which protects the inner parts of the nerves from injury. The chorioid, a thin and soft structure filled with veins and arteries, follows next and provides nourishment to the overall structure. Finally, the retina transmits nutrients to the lenses themselves. Hunayn then presents the system responsible for protecting the eye. From the outermost level, these are the conjunctiva, cornea, and uvea. While both the conjuctiva and cornea provide protection with minimizing hindrance to the lenses, the uvea has an extra function of concentrating the pneuma exiting out of the eye to prevent it from
Ora serrata Ora serrata The ora serrata is the serrated junction between the retina and the ciliary body. This junction marks the transition from the simple, non-photosensitive area of the ciliary body to the complex, multi-layered, photosensitive region of the retina. The pigmented layer is continuous over choroid, ciliary body and iris while the nervous layer terminates just before the ciliary body. This point is the ora serrata. In this region the pigmented epithelium of the retina transitions into the outer pigmented epithelium of the ciliary body and the inner portion of the retina transitions into the non-pigmented epithelium of the cilia.