Defects in color vision are actually not associated with visual perception at all and are generally due to a genetic condition. The most common form of color vision defects, which is about 99% prevalent in partial color blindness, is red/green color vision deficiency. Another color vision defect, blue/yellow, also presents, but is exceptional and there is no normally accessible test for it.
The color vision defect is hereditary and exists all through one’s life. It is very rare that such a defect develops as a secondary defect to another medical condition, or that a negligible degree of damage may become evident as the eye ages. Several tests for color defects have been produced, but the most common among them is the Ishihara plate test, which is applied as an initial screening test for marine engineers.
Color blindness may be limited in that is affects only some colors, or inclusive, meaning it affects all colors. Total color blindness is very uncommon. Bear in mind that those who suffer complete color blindness regularly have other grave eye troubles as well.
Photoreceptors known as cones let us understand color. These are situated in the very middle of the retina and hold three photosensitive pigments that are red, green, and blue. Thus people who are color vision defective lack or miss one or more of these colors. Those with regular color vision are denoted as trichromats. Anomalous trichromats are the ones who have a deficiency in one of the pigments, and this is the most common kind of color vision issue. A dichromat person is one who has a total absence in one cone pigment.