Corneal endothelium forms on the inner surface of the cornea. These cells play an important role in maintaining a stable hydration and the "transparency of the cornea ":/glossary/transparency.html. Regulates intraocular fluid penetration into the stroma, and actively draws it back. During life, the number of endothelial cells declines by half. The ability of endothelial recovery is minimal damage that leads to fluid penetration into the stroma and give corneal edema.