Color blindness: causes, symptoms, types and features

This disorder causes some people to see everything without color, on a scale of black and white.

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.

Humans are 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 is in charge of capturing images through the refraction of light, thanks to which we are able toThanks to this, 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 be subsequently processed at the cerebral level.

When an image is captured, light enters the eye through the cornea and crosses the eye until it reaches the retina, where the image in question is projected in an inverted form.

In the retina there are a number of receptors that allow different aspects of the image to be captured, the cones and rods. While the rods focus on capturing the level of brightness thanks to their extreme sensitivity to light energy, the cones are primarily responsible for providing color information.

Located in the fovea, the cones allow us to capture the color thanks to the existence of three pigments inside the cones.They can capture different wavelengths (specifically, they contain erythropsin, chloropsin and cyanopsin, which allow us to see red, green and blue respectively).

A person is considered color blind if he/she shows a severe difficulty or a total absence of the ability to perceive one or more colors. Also called color blindnesscolor blindness means that the eye is not able to capture the wavelength corresponding to a particular color, either because it does not have the pigments to do so or because they no longer function properly.

This causes that, when faced with stimuli that people who have three pigments in their cones see in a certain color, the colorblind subject will perceive a different color and will even be unable to perceive the differences between that color and the one he/she confuses it with (for example, he/she will see green something that others see as the same color, but also something that another person who is not colorblind would see as red).

This is an ailment that until now has been chronic.However, gene therapy research may offer some kind of solution to this problem in the future. As a general rule, color blindness does not usually pose a problem of adaptation and does not usually entail major repercussions.

However, this condition does disqualify people from certain professions and activities. For example, although they may be able to obtain a driving license, professions such as piloting are forbidden due to the risk involved in not being able to distinguish certain colors or signals.

Why does this disorder occur?

The causes of this deficiency in color perception are to be found in the absence of certain pigments in the retinal cones. This absence has in most cases a genetic origin, being caused in particular by X-linked alterations in the X chromosome.

The fact that the alteration is found in this sex chromosome explains why color blindness is a condition that appears much more frequently in males. Since males have only one X chromosome, if they inherit a chromosome with the mutation that causes color blindness, they will end up developing it, while in the case of females this only happens if both sex chromosomes have the mutation that causes color blindness.

In addition to its genetic origin, there are some substances that can also induce color blindness. substances that can also induce color blindness as a side effect, there are some cases of medications that induce it.There are some cases of drugs that produce it, such as hydroxychloroquine.

As we have seen, color blindness is defined as the absence or difficulty in perceiving the color of objects. However, people with this problem may have different degrees of difficulty in detecting it, as well as differing in the shades of color they see. may differ in the shades that they will be able to perceive.. The following are the most common types of color blindness.

Dichromatism

The most common type of color blindness is produced by the absence of one of the three pigments. Since it is impossible for the pigment in question to capture 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 a matter of not seeing a single color, but rather that all those colors resulting from the combination of this one with others are not perceived correctly.

It is also possible that dichromatism is only present in one eye, the other eye having a trichromatic color vision. Depending on the type of malfunctioning receptor, three subtypes of dichromatism can be distinguished three subtypes of dichromatism:

Deuteranopia

The missing pigment is the pigment corresponding to green.. Short wavelengths will be perceived as blue, while from a neutral point where it perceives gray it will begin to perceive different shades of yellow.

Protanopia

The color that is not perceived is on this occasion 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, the subject perceives different shades of yellow.

Tritanopia

The blue pigment is the one that functions incorrectly in this type of color blindness. in this type of color blindness. This is the least common subtype and usually causes a greater perceptual loss compared to the previous types. These people perceive the color green at short wavelengths, and from a neutral point begin to see red.

Anomalous trichromatism

In this case, the individual possesses all three types of pigments, but at least one functions abnormally and cannot perceive color in the same way as a trichromatic. and cannot perceive color in the same way as a trichromatic.

In this case they need the intensity of the color to be much higher than usual in order to be able to perceive it. It is also common for them to confuse colors. As with dichromatism, there are three types:

• DeuteranomalyDeuteranomaly: the green pigment does not work properly.

• Protanomalyred is not perceived in its entirety by the eye.

• Tritanomaly: in this case, the color that is not correctly captured is blue.

Monochromatism or achromatism

People with this strange condition do not have functional cones and cannot perceive color. They can only experience reality in different shades of white, black and gray, basing their entire vision on theTheir entire vision is based on the light detection ability of the rods.

Diagnosis

One of the most widely used tools for diagnosing color blindness is the Ishihara color test. the Ishihara color test.. This tool consists of a series of images created with several closely spaced dots that, from the different patterns of their coloring, form an image. People with some form of color blindness have difficulty seeing the image that is formed, since beyond the color of the dots there is nothing to give clues about the shape of that figure.

However, it should be remembered that the diagnosis can only be made by specialists who examine each individual case.

Bibliographical references:

• Adams, A.J.; Verdon, W.A. & Spivey, B.E. (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.