The iris is a thin diaphragm composed mostly of connective tissue and smooth muscle fibers. It is seen from the outside as the colored portion of the eye. It extends forward from the periphery of the ciliary body and lies between the cornea and the lens. The iris divides the space separating these parts, which is called the anterior cavity, into an anterior chamber (between the cornea and the iris)mycontentbreak and a posterior chamber (between the iris and the lens).