As light enters the eye, it strikes the receptor cells of the retina called the rods and cones. A chemical reaction results in the formation of electric impulses, which then travel to the brain through the optic nerve.
Review Date 5/14/2017
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.