The English-born naturalist, chemist and mathematician John Dalton (1766–1844) was one of the main responsible for the study of achromatopsia, a disease of a genetic character and congenital profile that, according to experts, is not progressive. This is an anomaly that affects the view. For the valuable contributions of this specialist, over time partial achromatosy began to be described as color blindness.
Color blindness is framed in discromatopsia, a term that refers to an inconvenience based on the inability to differentiate colors. Although not all color blinds confuse the same tones, they most often have difficulty distinguishing between green and red. Instead, a colorblind can appreciate more shades of violet than a subject with normal vision.
When we talk about this genetic problem we have to state that there are several types of it. Specifically at the general level we can determine that there are three:
- Monochromatic. The person who suffers from this kind of color blindness is characterized because in the retina he has only one sensitive cone so he only sees one color.
- Dichromatic. Two of the above cones are those of the citizen suffering from this problem. This fact brings with it that we find in turn three types of colorblind: protanopes that are absolutely insensitive to red; deuteranopes that confuse the red, green and yellow shadows; and tritanops that are insensitive to blue while confusing blue and green shadows.
- Anomalous tricromatric. One of the most common cases is this in which people who have it find the fact that they are unable to distinguish colors, they confuse each other.
In addition to these three kinds of color blindness, we cannot ignore the fact that there is also another one that is called Achromatic. This is a visual defect that occurs very infrequently but is characterized by the fact that the sufferer sees everything in black and white and in the corresponding range of grays.
Several are the methods that exist to be able to determine that someone suffers from color blindness. However, the most common procedure is to make use of so-called Ishihara letters in which numbers are represented in different colors.
Color blindness disorder is linked to a recessive allele associated with the X chromosome. In the case of men, inheriting a single X chromosome with the deficiency already becomes colorblind. Women, on the other hand, need a pair of X chromosomes with the deficiency to be diagnosed as colorblind; otherwise, they will only carry carriers (so they can pass on color blindness to their children). This difference translates into a broad prevalence of the male sex among those who suffer from color blindness.
Color blindness implies a lack of sensory cells in the retina that react to colors and are known as cones. They process the light that objects reflect and that determine colors. There is one type of red light-sensitive cone, another type of green light-sensitive cone, and a third type of blue light-sensitive cone. The problem of colorblinds arises from the failure of the genes that must produce the pigments of these cones.