Corneal endothelium is a layer of endothelial cells on the inner surface of the cornea. It faces the space that forms between the cornea and the iris. The corneal endothelium is specialized, flattened, mitochondria-rich cells that line the posterior surface of the cornea and face the anterior chamber of the eye. The corneal endothelium regulates the transport of fluids and solutes across the posterior surface of the cornea and maintains the cornea in a slightly dehydrated state required for optical transparency.