THANK YOU VERY MUCH FOR YOUR PARTICIPATION. I apologize for the mistakes it could have into the text, English is not my mother tongue.
 
Color vision is due to photoreceptors in the retina of the eye known as cones. These cones have light sensitive pigments that enable us to recognize color. Each cone is more sensitive to either red, green or blue light, which the cones recognize based upon light wavelengths.


Normally, the pigments inside the cones register differing colors and send that information through the optic nerve to the brain enabling you to distinguish countless shades of color. If the cones in the retina lack one or more light sensitive pigments or one of the three are defective, people would have a colour deficiency.

Colloquially, the defects in color vision are called "colour blindness" but, actually, the anomalies are called "protan", "deuter" or "tritan" depending on the type of cone affected (red, green or blue one).