What is color blindness?
Color blindness is a predominantly genetic defect, which consists of the inability - total or partial - to distinguish colors mainly due to an alteration of the photosensitive structures at the level of the retina.
The term "color blindness" derives from the chemist John Dalton who first wrote an article in which he exposed the problem derived from his color blindness.
Common color blindness
The most common form of color blindness is red-green blindness: the affected subjects are not able to distinguish the two colors because the wavelengths of red and green, respectively medium (700 nm) and long (540 nm), they are perceived as identical. Any green image on a red background (as in the figure), in fact, is not distinct from colorblind subjects: strictly speaking, for colorblinds a particular combination of colors is indispensable, which excludes the red-green combination.
Color blindness is considered a sex-related disease, which means that genes placed at the level of sex chromosomes X are responsible for color blindness: the disease, in fact, affects mainly males (XY) and less females (XX).
Genetic causes
We have seen that the gene involved in color blindness, a recessive disease, is placed in the sex chromosome X: this means that the color blindness is not transmitted directly from the affected father to the child, but a carrier daughter could transmit the disease to her nephew. To better understand: being a disease linked to the X gene, from a healthy mother and a colorblind father, all the daughters will have a healthy X chromosome (from the mother) and another defective X chromosome (from the father). For this reason, color blindness is usually transmitted to every other generation (from grandfather to grandson). It is rare, but not impossible, that the disease affects females; if the mother and father are color-blind, the offspring will also be color-blind regardless of gender.
Despite what has been said, it is possible that color blindness can occur even after birth: pathologies that affect the eyes, retina, brain, optic nerve and some chemical components, could cause more or less serious forms of color blindness. It should be noted, however, that in cases of extra-genetic color blindness the perceived chromatic alteration can be reversible and / or affect only a part of the visual field.
Are there treatments?
There are no pharmacological treatments to correct congenital color blindness; the only treatment is of a technological-IT nature. A software has been programmed that is suitable for people suffering from color blindness to be able to distinguish colors (albeit not in a completely natural way): moving the cursor over a colored element, the software will indicate the name of the color.
