Another vision screening program that is mandated is for color vision. This screening is only conducted once, usually in the 1st or 2nd grade, and only on males. This screening is conducted using The Ishihara Plates . The Ishihara test for children is intended for those who are 4 to 6 years old. Consult the Ishihara test on line and learn about the test.
Color blindness is an inaccurate term for a lack of perceptual sensitivity to certain colors.
Absolute color blindness is almost unknow. There are three types of color receptors in our eyes, red, green and blue. We also have black and white receptors. They are more sensitive than the color receptors, that is why we have poor color perception in the dark. Color deficiency comes as a result of a lack of one or more of the types of color receptors.