Dichromat

A person with colour vision based on only two types of functional cone cells in the retina instead of the typical three, resulting in a reduced ability to distinguish certain colours. Dichromats perceive colour in a two-dimensional colour space rather than the three-dimensional space experienced by people with typical trichromatic vision. There are three types of dichromacy: protanopia (missing L-cones, affecting red perception), deuteranopia (missing M-cones, affecting green perception), and tritanopia (missing S-cones, affecting blue perception). Dichromacy affects approximately 2% of males and is much rarer in females.