The condition of having both rods and cones, but only a single kind of cone. Affected individuals have good pattern vision in daylight, but cannot distinguish between colors.
Comment:
There are three differing forms of cone monochromacy, named according to the residual functioning cone class, (1) blue cone (S-cone) monochromacy, green cone (M-cone) monochromacy, and red cone (L-cone) monochromacy.