Color Blindness: Causes, Symptoms, Types And Characteristics
Of all the senses, sight is the most developed in human beings. Being able to see allows us to perceive the stimuli and events that are present around us, and this allows us to analyze and evaluate the situation immediately and be able to react to it, even instinctively.
However, we do not all see the same way. Through our eyes we see many things: shapes, depth… even color. But there are people who are not able to detect any of these properties. This is the case of color blindness of which we are going to explain what it is and what its causes are.
The human being is able to see thanks to a complex association between light-sensitive cells and neurons that transmit and process this information: the visual system. This system It is responsible for capturing images through the refraction of light thanks to which we can capture the elements of the environment in an efficient and effective way. The images are captured by the main organ of vision, the eye, to later be processed at the brain level.
At the time of capturing an image, the light entering the eye passes through the cornea and crosses the eye until it reaches the retina, on which the image in question is projected inverted.
In the retina there are a series of receptors that allow us to capture different aspects of the image, cones and rods. While the rods focus on capturing the level of luminosity thanks to their extreme sensitivity to light energy, the cones are mainly responsible for providing information regarding color.
Located in the fovea, the cones allow us to capture color thanks to the existence of three pigments inside which can capture different wavelengths (specifically they contain erythropsin, chloropsin and cyanopsin, which allow us to see red, green and blue respectively).
From the retina, the information will be sent to the brain through the optic nerve, to later be processed. Thanks to this we can be able to recognize a large number of different colors, possessing trichromatic vision. But What happens in the case of a color blind person?
A person who shows severe difficulty or a total absence of the ability to perceive one or more colors is considered colorblind. Also called color blindness color blindness means that the eye is not able to capture the wavelength corresponding to a certain color, either because it does not have the pigments to do so or because they have stopped working correctly.
This means that, when faced with stimuli that people who have three pigments in their cones see as a certain color, the colorblind subject will perceive a different color and will even be unable to perceive the differences between said color and the one with which it is confused (for example, will see green something that others see the same color, but also what another non-colorblind person would see red).
It is an ailment that until now has been chronic. although research in gene therapy may offer some type of solution to this problem in the future. As a general rule, color blindness does not usually pose an adaptation problem and does not usually have major repercussions.
However, this condition disqualifies you from carrying out certain professions and activities. For example, although they may have a driving license, professions such as piloting are prohibited due to the risk of not being able to distinguish certain colors or signs.
Why does this disorder occur?
The causes of this deficiency in color perception are found in the absence of certain pigments in the cones of the retina. In most cases, this absence has a genetic origin, being caused specifically by X-linked disorders.
The fact that the alteration is found in this sex chromosome explains why color blindness is a condition that appears much more frequently in men. Since they only have one
In addition to its genetic origin, there are some substances that can also induce it as a side effect there are some cases of medications that produce it, such as hydroxychloroquine.
Finally, some strokes or diseases such as macular degeneration, dementia or diabetes can cause damage that prevents color perception, either due to damage to the retina, the optic nerve or the brain regions in which information is processed. of the color.
Types of color blindness
As we have seen, color blindness is defined as the absence or difficulty of perceiving the color of objects. However, people with this problem may have different degrees of difficulty in detecting it, as well as The tones that they will be able to perceive may differ. Below we present the most well-known types of color blindness.
Dichromatisms
The most common type of color blindness It is produced by the absence of one of the three pigments. Given the impossibility of the pigment in question capturing the color, it will be captured through a different wavelength, perceiving another color.
Sometimes this causes two colors to be confused, as in the example of the confusion between red and green. It must be taken into account that it is not that a single color is not seen, but that all those colors that result from the combination of this one with others are not correctly perceived.
Likewise, it is possible that dichromatism only occurs in one of the eyes, with the other having trichromatic color vision. Depending on the type of receiver that is not working correctly, we can distinguish three subtypes of dichromatism :
Deuteranopia
The missing pigment is the one that corresponds to green. Short wavelengths will be perceived as blue, while from a neutral point where you perceive the color gray you will begin to perceive different shades of yellow.
Protanopia
The color that is not perceived is this time the red. The subject perceives short wavelengths as blue, until reaching a neutral point where he perceives the color gray. From this neutral point, as the wavelength increases, he perceives different shades of yellow.
Tritanopia
The blue pigment is the one that works incorrectly in this type of color blindness. This is the least common subtype and usually causes greater perceptual loss compared to the previous types. These people perceive the color green at short wavelengths, and from a neutral point they begin to see red.
In this case, the individual has all three types of pigments, but at least one works abnormally and cannot perceive color in the same way as a trichromatic.
In this case, they require that the intensity of the color be much greater than usual to be able to capture it. It is also common for them to confuse colors. As with dichromatisms, we can find three types:
Tritanomaly : on this occasion the color that is not captured correctly is blue.
Monochromatism or achromatism
People with this strange condition do not have functional cones, being unable to perceive color. They can only experience reality in different shades of white, black and gray basing all of their vision on the light detection capacity of the canes.
Diagnosis
One of the most used tools to diagnose color blindness is the Ishihara color test. This tool consists of a series of images created with several points very close together that, based on their different coloring patterns, form an image. People with some type of color blindness have difficulty seeing the image that is formed, since beyond the color of the dots there is nothing that gives clues about the shape of that figure.
However, it must be remembered that the diagnosis can only be made by specialists who examine each case in particular.
Bibliographic references:
Adams, A.J.; Verdon, WA & Spivey, BE (2013) Color vision. In: Tasman, W. & Jaeger EA, eds. Duane’s Foundations of Clinical Ophthalmology. vol. 2. Philadelphia, PA: Lippincott Williams & Wilkins.
Goldstein, E. B. (2006). Sensation and perception, 6th edition. Debate: Madrid.
Wiggs, J.L. (2014). Molecular genetics of selected ocular disorders. In: Yanoff M, Duker JS, eds. Ophthalmology. 4th ed. St. Louis, MO: Elsevier Saunders.
