What is Color Blindness?

What is Color Blindness?

Color is a concept that emerges when light waves reflected from objects are perceived by the optic nerves and transmitted to the brain. When naming colors, the wavelengths of the reflected lights are taken into account. If an object directly reflects or scatters all the light collected on it, the human eye sees that object in white, while the objects that absorb all the light waves that come upon it by directly absorbing it are perceived as black by the brain. As a result of the loss of function of some nerve cells in the eye, the different wavelengths of light reflected by the objects cannot be transmitted to the brain correctly and color vision does not occur. These disorders in the perception of colors are called color blindness.

What is Color Blindness?

As soon as a sufficient amount of light wave reflected from an object touches the eye, it first comes into contact with the retina and is processed here by two different photoreceptors. These photoreceptors, also known as rod and cone cells, are extremely important structures that support vision with their different properties. Rod cells, which are extremely sensitive to light, allow to see even in very dark environments, but they do not have any sensitivity to colors. Cone cells, on the other hand, are less sensitive to light, but have nerve cells that are extremely sensitive to colors reflected from objects, especially in daylight. According to the type of pigment it contains, three different cone cells can be mentioned as sensitive to red, green and blue, respectively. Light waves absorbed by photoreceptors in these cell groups,

In order for color vision to occur correctly, all three different types of photoreceptors in cone cells must function properly. Defects in the functioning of one or more of these three types of cone cells cause a disorder in the perception of colors and a disease called color blindness in medicine. Color blindness, known to affect 180 million people worldwide, is classified in 3 different ways, usually according to the photoreceptor cell that is defective:


In this type of color blindness, there is a functional disorder in all 3 different cone cells that perceive light waves and convert them into neural messages. People with monochromatic color blindness can only classify colors as dark and light, and they are not able to distinguish other colors in any way. The monochromatic color blindness picture, which is the least encountered among all color blindness cases, is also called the “colorless type” in some sources.


The type of color blindness in which one of the cone cells is completely defective while the other two perform their normal function is called dichromatic color blindness. Whichever cone cell has a defect, the person cannot distinguish the light waves absorbed by those cone cells and perceives that color differently than other people who are not colorblind. This type of dichromatic color blindness is called protanopia if the present defect is in photoreceptor cells that affect red color. While the person has difficulty in distinguishing colors close to red, he sees completely red colored objects in different colors. In the presence of any defects in the photoreceptors that absorb the green color, dichromatic color blindness is called deuteranopia. Persons with this defect sees green in different tones and has difficulty distinguishing color waves that are close to green. In dichromatic color blindness, a defect in the photoreceptor cells that absorb blue is called tritanopia, and in the same way, the person perceives the color blue in different tones and has difficulty in distinguishing the color tones close to blue.


In this type of color blindness, one of three different types of photoreceptors has a loss of sensitivity to that color and the corresponding cone cells malfunction. People with abnormal trichromatic color blindness have difficulty distinguishing a small area in the broad spectrum of colors. This causes that color to be perceived in different tones than a person who is not colorblind. This type of color blindness is also named in 3 different ways, depending on the type of photoreceptor cell that works in an imperfect manner. If the abnormal functioning and loss of sensitivity are in red-sensing photoreceptors, this condition is called protanopia abnormal color blindness. The person perceives red color waves as red, but has difficulty distinguishing some tones of this color. If there is loss of sensitivity in the photoreceptors that perceive green color, deuteranopia abnormal color blindness picture develops. While the person sees the color green as green, he has difficulty in distinguishing the different shades of this color. Abnormal trichromatic color blindness, which is characterized by loss of sensitivity in photoreceptors that perceive blue color waves, is called tritanopia color blindness. While seeing the color blue as blue, it causes the person to mix other tones of this color to a large extent.

What Causes Color Blindness?

Color blindness is a genetic disease that is passed down from generation to generation with recessive genes. This disease, which is one of the most common inherited disorders, is seen approximately 20 times more in men than in women, since it is transmitted through the X chromosome. However, it is not correct to say that color vision defects will only arise from genetic factors. Although it is extremely rare, various visual defects such as color blindness may occur as a result of injuries that cause trauma and damage to the retina, some diseases related to the structure of the eye, intense contact with serious toxic substances and some systemic diseases.

How Is Color Blindness Diagnosed?

The diagnosis of color blindness is usually made with some screening tests performed in line with various problems that occur in adulthood. It is extremely important to make the diagnosis as early as possible so that the person does not face serious problems both in professional life and in risky environments such as traffic. Commonly used tests in the diagnosis of color blindness are:

Ishihara color vision palettes

Ishihara palettes, which are created by the combination of many circles of different sizes and different colors, are also called pseudoisochromatic palettes. A complete test consists of a total of 38 different pallets. There are various numbers and lines in these pallets, each of which is designed differently. These numbers and figures, hidden with correct colors, can only be seen by people who do not have any color vision-related disorder. Some palettes are designed so that only people with color blindness can see them. Although the most widely known colorblind test, Ishihara palettes are currently considered inadequate as they can only result in a positive or negative result, without giving a detailed result for color blindness.

Farnsworth color dot procedure

While applying this test, the patient is asked to separate 85 different colored stones according to their tones and arrange them correctly. This colorblind test, which is generally used to diagnose blue color-related visual disorders, is difficult in terms of application, but it is not one of the frequently preferred tests because it takes too long.

Anomaloscope test

Thanks to the anomaloscope device, all congenital or subsequent color blindness problems can be fully diagnosed together with the degree of the disease. This test method, which gives the most accurate results for color vision impairment, is now considered the reference test.

Color Blindness Treatment

Since color blindness is a hereditary visual disorder, there is no treatment option that definitively eliminates the disease. However, with haploscopic filters with chromogenic properties, intraocular lenses and glasses that are specially colored for light waves in which the person has visual impairment can be preferred. Chromogen filter glasses and lenses, which were developed to facilitate the adaptation of people diagnosed with color blindness to daily life activities and areas such as traffic, are one of the most important inventions with a high success rate of 97%.