The iris is the colored portion of the eye, amembrane located between the cornea and lens that regulates the entrance of light into the eye by contracting and dilating.
Review Date 10/8/2017
Updated by: Linda J. Vorvick, MD, Clinical Associate Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.