Daltonism owes its name to John Dalton, an English chemist who was the first to publish a scientific article on this alteration in 1798. This scientist was also color blind.
Color blindness is caused by a genetic mutation, which makes it a hereditary condition. The chromosome responsible for coding the colors red and blue is the X chromosome, so it affects more men than women. Thus, it is estimated that approximately 8% of men are color blind, compared to 0.5% of women. In contrast, the blue color is related to chromosome 7 and affects both sexes in the same way.
How are the colors perceived?
In the retina, that tissue sensitive to light in which the images are projected inside our eyes, are the photoreceptors. There are two types of photoreceptors: rods and cones.
The canes are the cells specialized in perceiving the contrast of the images, and therefore in the vision in black and white. The cones, the color experts. The color is received thanks to electromagnetic waves with different frequencies that take place by the reflection of light.
Thus, there are three types of cones:
- L wave cones or long wavelength: perceive the color red.
- M wave cones of medium wavelength: associated with the green color.
- S-wave cones or short wavelength: associated with the blue color.
These photoreceptors are concentrated in the central part of the retina, the fovea. This area is the one that receives more luminosity and the one that provides greater clarity. In the fovea there are no canes, which are located around it. In the intermediate zone is where we can find a mixture of cones and canes.
The accumulation of specialized cones in three colors is what makes it possible to perceive thousands of colors thanks to their combination.
As indicated above, the genetic mutation causes one or several types of cones not to be found or to present a malfunction. Depending on the type of cone affected, a different type of color blindness will occur.
- Acromatism: they do not appear, or they have anomalies in the three types of cones. People with this type, which are 1 in 100,000, perceive in grayscale.
- Monochromatic: only one of the three types of cones have or only works properly.
- Dicromatism: only one type of cone is affected. In turn, it is divided into:
- Protanopia: they do not perceive red well.
- Deuteranopia: affects the green color.
- Tritanopia: the blue color is the deficient one.
- Abnormal trichromatism: it is the most prevalent type. In this case, the person has all three types, but some of them are moderately affected. Thus, although he can perceive most colors, he has difficulties in differentiating some of them. Like dichromatism, it can be divided into protoanomal, deuteroanomal and tritanomal.
The world is colorful
That we live in a world of color is nothing new. However, with technological development, colors play a fundamental role in our day to day.
Although they grow up adapting to a colorful world and using other strategies, people with color blindness face a multitude of daily difficulties in which non-colorblind people do not even repair. At work or school, red and green are usually used to correct documents or mark errors. The metro lines are determined by colors. And what about traffic, where the traffic lights basically consist of red and green lights.
These limitations, in addition, sometimes are established by the administrations, preventing in some countries that they accede to the police. Or in Brazil, they are not allowed to obtain a driver’s license.
In spite of everything, devices and / or adaptations are being developed to mitigate these difficulties. For example, installing semaphores that, in addition to color, are differentiated by a shape or symbol (cross to stop, line to continue). Or, launching glasses or lenses that correct the chromatic deficiencies according to the needs.
In 2008, the Association Daltónicos No Anónimos was created in Spain, which launches both visualization campaigns and specific adaptation objectives. And in 2010, the Portuguese designer Ashoka Miguel Neiva, presented in Oporto a graphic color identification system called ColorADD. This system is based on 5 symbols that correspond to red, blue, green, black and white, and that can be combined with each other to designate a multitude of colors.
The objective of this system is to apply it to basic areas such as education, health, transportation, etc. For example, marking with these symbols the pencils, sections of textbooks, transport instructions, signs in hospitals … and even in games, clothes or makeup.