The retina is the internal layer of the eye that receives and transmits focused images. The retina is normally red due to its rich blood supply. Update Date: 09/16/2008Daniel B. Hoch, PhD, MD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.