Color blindness, an anomaly of color perception

Color blindness, an anomaly in color perception, was discovered in the 18th century by English chemist John Dalton. Carried by the X chromosome, the disease mainly affects men. There are several forms of color blindness. The retina is covered with three types of cones. Each type perceives one color: blue, green or red. If one or more types of cone malfunction, the sufferer will not perceive certain hues.