http://www.nkcf.org... How the Human Eye Works http://www.nkcf.org/how-the-human-eye-works/ National Keratoconus Foundation eyes evaluate objects http://www.nkcf.org/how-the-human-eye-works/ How the Human Eye Works http://www.nkcf.org/how-the-human-eye-works/ how the human eye works http://www.nkcf.org/how-the-human-eye-works/