The Trichromatic Theory by Young-Hemholtz proposed that there are three different types of color receptors that each respond maximally to a different wavelength. The three different cone photoreceptors are the S-cones, M-cones, and L-cones. If one of these sets of cones is absent, it can lead to colorblindness in people. About 8% of the male population and about 0.5% of the female population have some form of color vision deficiency. There are several types of color blind-people. A deuteranope has an absence of M-cones, a protanope has an absence of L-cones, and a tritanope has an absence of S-cones. There are also three types of defects that a person can suffer from. A color-anomalous person has two types of cones that appear so similar they can’t discriminate between the two. A cone monochromat has only one cone type, so this person is truly colorblind. Lastly, a rod monochromat has no cones at all so they are colorblind and are visually impaired in bright light.

My dad suffers from red green color blindness. His parents first identified it when he was a child when the colors in his drawings were incorrect such as coloring an apple green instead of red. His parents first thought he was just doing it to be different, but they eventually figured out he would pink the wrong crayons by accident. He began to read the labels on the crayons instead of looking at the colors. My whole life my dad always got very badly sunburned and he eventually told me it was because he couldn’t tell when he was getting too red so he only ever figured it out before it was too late. Another problem my dad has is when he is barbecuing red meat or chicken on the grill and it is difficult for him to tell if it is cooked well done or raw. He has gotten used to it and now has other ways of figuring it out or he asks one of us for our opinion. Lastly, he sometimes has trouble distinguishing between a tomato that is still green and unripe and a tomato that is red and ready to eat.

Overall, my dad has difficult distinguishing between colors and it is sometimes hard for him to see red, but he is lucky he is not totally colorblind and can’t see color at all. He is color-anomalous and has similar M-cones and L-cones that are hard to distinguish. He has adjusted so well that it’s usually hard to tell he has a problem with it at all.

Normal color vision

Deuteranopia

Source for photo: http://www.colourblindawareness.org/colour-blindness/types-of-colour-blindness/