Protanopia is caused by missing L cones. Deuteranomaly is caused by dysfunctional M cones. M cones have a spectral sensitivity similar to L cones. Deuteranopia is caused by missing M cones. Individuals with protanomaly and protanopia also have a reduced sensitivity to long wavelengths.
Reds appear darker than normal.
The spectrum as perceived by individuals with normal color vision, protanopia, deuteranopia and tritanopia Deuteranomaly is by far the most common form of color vision defect. The incidence of color vision defects, particular among males, varies greatly between populations. For designers the problem is to select color combinations that can be discriminated by individuals with different types of color vision deficiency. One approach is to try to simulate the colors that are perceived by such individuals. These models are generally limited to dichromatic defects.