The colour blindness is a genetic alteration which causes difficulty distinguish colors. It is common to believe that color blind people see in gray scale, but this is not true in most cases since color blindness usually affects specific colors.

In fact, achromatic color blindness, which is the type of color blindness in which no color is distinguished, is very rare (0.001-0.005% of the population).

types of color blindness

There are several types of color blindness and the spectrum of colors affected in each is different. Not all color blind people see the same way.

The colour blindnessalso know as color blindness, is generally due to a congenital dysfunction (it is of genetic origin, hereditary and is present at birth). It can also occur, although it is not very common, to acquired eye injuries.

In the retina there are two types of cells whose stimulation is responsible for eyesight: cones and rods. The cones are responsible for seeing and distinguishing colors and Canes black, white, and grayscale.

exist three types of cones and each of them reacts to a type of color: red, green and blue. The combination of these three colors, together with the black and white perceived by the rods, makes it possible to see and distinguish the entire range of colors and shades.

There are many types of color blindness depending on the type of cones affected and, therefore, the colors that can be seen and distinguished.

The most important types of color blindness are:

  • Achromatic: In this type of color blindness there is no type of cone. There are only photosensitive rod cells.
  • monochrome: Appears when there is only one type of cone. The ability to distinguish many colors and see in one dimension is lost, the ability to perceive spatial depth is also lost.
  • Dichromatic: Only two types of cones are present. According to the affected or absent cone, three types of dichromatic color blindness are distinguished:
    • Protanopia: affects the red cone.
    • deuteranopia: affects the green cone.
    • tritanopia: Affects the blue cone. Tritanopia is a very rare type of color blindness.
  • anomalous trichomatic: In this type of color blindness, the cones of the three types are present, but one or more do not work correctly and for this reason some colors can be confused with others. Vision may be similar to that of dichromatic colorblindness but with less severe color disturbance. Depending on the type of affected cone, one can speak of protanomaly (red), deuteranomaly (green) and of tritanomaly (green).

How does each type of colorblind person see?

The deuteranopia and deuteranomaly They are the most common types of color blindness. This people are unable to distinguish between red and greenwhich is why it is also known as red-green blindness.

Red and pink tones are seen as shades of green, but also greens are not seen as good but are seen as light grays or a dull and dark brownish green tone, similar to the browns and greens of military camouflage suits. Color blind people with deuteranopia also do not distinguish violet, a color that is seen as blue.

The protanopia and protanomaly, is another of the most frequent types of color blindness and also falls within red-green blindness. Difficulty distinguishing between green and red is more severe than in deuteranopia because red is not converted to green, but red is completely removed from the visual spectrum and is perceived as black or gray.

In addition, shades of pink become dark green, even human skin tones, often causing these people to see people as having gray-green skin tones.

The yellow-blue blindness (tritanopia or tritanomalia) It is one of the less common types of color blindness and has been observed with some frequency as damage resulting from severe alcoholism or exposure to some chemical agents. These colorblind people do not see green, a color that transforms into blue tones. Red and yellow are seen as pink. Pink skin tones are often seen brighter and blues are tinted gray looking darker.

Let’s see some examples of how colorblind people would see through a series of images: