The cornea allows light to enter the eye. As light passes through
the eye the iris changes shape by expanding and letting more light
through or constricting and letting less light through to change
pupil size. The lens then changes shape to allow the accurate
focusing of light on the retina. Light excites photoreceptors that
eventually, through a chemical process, transmit nerve signals
through the optic nerve to the brain. The brain processes these
nerve impulses into sight.
Review Date: 06/01/2011
Reviewed By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of
Physician Assistant Studies, University of Washington, School of
Medicine; and Franklin W. Lusby, MD, Ophthalmologist, Lusby Vision
Institute, La Jolla, California. Also reviewed by David Zieve, MD,
MHA, Medical Director, A.D.A.M., Inc.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)
