Colorblindness is the inability or decreased ability to perceive color differences. Dichromacy is a condition characterized by reduced dimension of color vision in which one of the three basic color mechanisms is absent or not functioning. Anomalous trichromacy is the milder form of color vision deficiency, with ability to discriminate between different colors in varying degrees but not normal. Dichromacy and anomalous trichromacy are subdivided into three types: protan, deutan, and tritan depending on the affected cone type. Protan and deutan types consist red-green defects. Inherited red-green color vision defects affect 8% of males. Tritan type defect leads to inherited blue-yellow defect that is fairly rare.
