Tetrachromatism is a condition that arouses scientific curiosity. It is a term that refers to a visual quality. People or animals with tetrachromatism have a high visual index. What is and what are the causes of tetrachromatism?
People with tetrachromatism can see up to 100 million colors. Tetrachromatism exists in certain animals, such as some birds, fish, insects or amphibians. Apparently, some people may also have tetrachromatism.
How is chromatic vision produced?
Before explaining what tetrachromatism is, it is important to present some basic notions about how the chromatic process takes place. The retina is a light-sensitive tissue located in the back of the eyeball. It is made up of different cells, including sticks and cones. They are light-sensitive cells. The cones allow the view of colors, ie the chromatic view.
There are different types of cones depending on how they react to light. The majority of the human population has three types. Each of them reacts to light with a different bandwidth. The information is transmitted through the optic nerve to the cerebral cortex.
Therefore, most people have so-called trichromatic vision. One type of cone detects red light, another type blue light and a third type green light. In this way, we can see almost 1 million colors.
Something different happens to some animal species. For example, in certain fish. There is a fourth type of cone, which allows them to perceive variations for each of the colors.
What is tetrachromatism?
Tetrachromatism is an eye abnormality that allows us to see about a hundred times more colors than normal. It is estimated that almost 12% of women in the world have this characteristic.
What happens is that they have a fourth type of cone. These people are called tetrachromates. The fourth type of cones allows them to obtain a four-dimensional sensory color space. They have a much higher visible spectrum because they can combine several primary colors. The rest of the people can make combinations of only three colors (red, green and blue). They are called trichromates. This means that I do not see all the possible variants.
How does it differ from the other categories?
Currently, there are different types of vision, depending on the cones in the retina. The first is trichromatism. It is the most common form of human vision. But sight can also be dichromatic. It is the most characteristic type in animals, such as dogs. There are only two types of cones sensitive to blue and green.
It is difficult to tell if a person has trichromatic or tetrachromatic vision. Sometimes this can only be verified by retinal tissue biopsy.
What are the causes of tetrachromatism?
Apparently, this condition occurs almost exclusively in women. The reason is a variation of the X chromosome, where the dichromatic gene is found. In this chromosome are the genes responsible for the expression of red and green cones. The reason there are more women than men is that they have two X chromosomes, while men have only one.
Women are more likely to have two different versions of these genes. This is how the four types of cones appear. However, this does not mean that there can be no men with tetrachromatism.
How can it be identified?
Now that we have established the causes of tetrachromatism, let’s see how it can be diagnosed.
To date, there is no test that can diagnose tetrachromatism with certainty. Online tests that try to verify this condition have no scientific support. Because they are made on digital screens, they are based on RGB technologies, ie they are made with a trichromatic color representation system. However, researchers are looking for ways to get an accurate diagnosis.
There is a way to diagnose tetrachromatism with certainty, but it is a complex option. The main idea is to get a retinal sample. These types of biopsies are very difficult to perform because they pose many risks to the patient’s vision.
Tetrachromatism is more common than you think
Tetrachromatism is a condition that women have more often than men. In the eye, there is another type of cone, which are the retinal cells responsible for color vision. Normally, there are three different types, but these people have four. They can see almost a hundred times more colors than normal. However, to date, there are no established methods to diagnose the condition.