Color Blindness? – All You Need To Know

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Some people ask: What is the name of the disease that confuses colors?

Do we really know what ‘color blindness‘ or ‘Daltonism‘ is?

Do we really know what ‘color blindness’ or ‘Daltonism’ is?

  • Do we know what colors a colorblind or Daltonic person sees?
  • Are different types of color blindness?
  • This article teaches us a little more about this color vision disorder, its symptoms, diagnosis, and… Is there a treatment for color blindness?

What Is Color Blindness?

Color blindness or Daltonism is an anomaly, not a disease; it is an alteration in chromatic (color) vision.

In our retina, we have sensory cells called photoreceptors, which react in response to light, and there are two types: rods and cones.

The rods allow us to appreciate black, white, and shades of gray and are activated in the dark.

In contrast, cones are the light-sensitive photoreceptors of the retina, which are activated during the day or in brightly lit environments, and allow us to see colors.

We have three types of cones:

  1. One type of cone: is sensitive to red light,
  2. Another type cone to green light
  3. And another to blue light.

The combination of these three colors allows us to see the world in a wide range of colors.

Depending on the incorrect functioning of the cones, we will have one type of color blindness or another. Color blindness can be: monochromatic, dichromatic, or anomalous trichromatic.

Color blindness is an alteration of genetic origin, and the degree of affectation varies greatly. It ranges from the inability to appreciate any color (known as achromatopsia or color blindness) to a slight difficulty in distinguishing shades of red, green, and sometimes blue.

The arrangement of normal color vision is known as trichromatism (three primary colors can be perceived).

Abnormal trichromatism refers to a person with all three types of cones but has functional defects that cause them to confuse colors and perceive altered color shades. This is the most common case among color-blind people.

‘Redolar’tells us in their manual ‘Cognitive Neuroscience (2014)’ that “Each of the three types of cones has a different sensitivity according to the wavelength to which they are tuned” (p:275), following the experiments conducted by Young and von Helmholtz of the trichromatic theory:

  • C cones (encode the color blue), make up 5-10% of all cones and have maximum sensitivity to short waves.
  • M cones (green color coding) make up about 40% of the total cones and have a maximum sensitivity to medium waves.
  • L cones (encoding the color red) make up 50% of the cones and are sensitive to long waves.

What Is The Difference Between Color Blindness And Dyschromatopsia?

Dyschromatopsia refers to the difficulty of perceiving colors, but its meaning is broader since it can be of genetic origin, known as congenital dyschromatopsia or color blindness. Dyschromatopsia of non-genetic origin is due to some diseases affecting the optic nerve or retina.

Based on his experiments at the end of the 19th century, Ewald Hering demonstrated the theory of opposing colors. He indicated that there are three pairs of opposite colors (red and green, blue and yellow, and black and white).

And since the middle of the 20th century, both theories are unified, where we have the three types of photoreceptors of the retina with different degrees of activation, which are encoded according to the processes of the opponents.

The three main types of visual color deficiency are:

  1. Protan defect (red color blindness).
  2. Deutan defect (green color blindness)
  3. And Tritan defect (blue color blindness).

These terms are translated as first, second, and third and come from Greek.

What Colors Do Color Blind People See? What Types of Color Blindness Are There?

As we indicated at the beginning, there are different types of color blindness depending on the deficit in the cones (achromatic, monochromatic, dichromatic, or anomalous trichromatic).

Let’s see how a color-blind person sees colors at the same time that we get to know each of the different types of color blindness:

Veamos cómo ve los colores, un daltónico, al mismo tiempo que conocemos cada uno de los distintos tipos de daltonismo:

Anomalous Trichromatism

In anomalous trichromatism, the retina has all three types of cones, just like a person who can see colors normally. Still, one of these is out of focus, which causes the person to confuse colors and perceive the shades of colors altered.

It is the most common form of color blindness. Depending on the functional alteration, it can be a protanomaly, deuteranomaly, or tritanomaly.

Red-green color blindness combines Protan (red) and Deudan (green) defects and is the most common form of color deficiency. It can be a protanomaly or deuteranomaly.

Blue-yellow color blindness is rare, and the sufferer has a reduced sensitivity to the color blue (Tritan), so it can confuse blue from green and red from purple. It is known as tritanomaly.


In dichromatism, the retina has two types of cones instead of the three needed for normal color vision:

  • Protanopia: people can see colors from the combination of green and blue, as they have no L (red) photoreceptors.

  • Deuteranopia: people can see colors from the combination of blue and red. They do not have M (green) photoreceptors.

  • Tritanopia: is one of the least common disabilities and involves people who do not have C (blue) photoreceptors.

Tipos de daltonismo


In monochromatism, the retina has only one of the three pigments of the cones, and the person will perceive the vision of light and color in one dimension.


Tricromatismo y acromatismo -

Achromatopsia occurs when the person does not have any of the three types of cones, so they will not be able to appreciate any color and will see the world in different shades of gray.

Depending on the type of color blindness and color deficiency:

  • Protanopia, red blindness
  • Protanomaly, red weakness
  • Deuteranopia, green blindness
  • Deuteranomaly, green weakness
  • Tritanopia, blue blindness
  • Tritanomaly, blue weakness

How Do You Know If You Are Color Blind?

Color blindness affects 8% of the population (8% male and 0.5% female), so it is necessary to perform a specific visual test to detect it. The best known is the Ishihara color blindness test.

Read: Ishihara test

This visual deficiency to distinguish colors is transmitted genetically through the X chromosome, usually from mother to son.

Although more women than men carry the color blindness gene, it is their sons who suffer from this disability, even if they have normal color vision.

For a female to be color blind, both X chromosomes must carry this gene

What Are The Symptoms Of Color Blindness?

The main symptoms of color blindness are difficulty seeing brightness in colors normally and differences that are impossible to observe between shades of the same color, especially between red and green or blue and yellow.

How to Detect Color Blindness in Children?

When a child suffers from color blindness, usually, they will not know that they suffer from it since the way they see colors is the way they have always perceived them. They do not know any other way to see color, and it is completely normal to them. Remember that color blindness is genetic, and you are born with this alteration in color vision.

But some signs, such as confusing the colors of green, red, and blue objects or paints when drawing, may indicate that we should do a visual color test to determine if our child has color blindness.

It is important to be able to detect color blindness in the child as soon as possible to reduce the inconveniences that they may have during the school stage, teaching them some ‘tricks’ so that they can continue learning without significant consequences.

How to Diagnose Color Blindness?

The Ishihara chart test is the most widespread procedure, although there are others.

This color vision deficiency test consists of the Ishihara charts. It refers to a test with 38 slides with a circle printed on each, formed by dots of different colors, wavy lines, or a number in the center.

The Farnsworth Test, on the other hand, is composed of colored cards which are differentiated by hue. To perform the test, the person has to order these cards according to the color graduation.

And the anomaloscope is a very precise device used to distinguish the color vision deficit and its severity. However, it is not very widespread due to its high cost.

Nevertheless, and even though we can find many color blindness tests online, it is essential to remember that in order to properly evaluate our case or that of our children, it is necessary to visit a vision specialist to perform a complete examination and to be able to tell us if we suffer from any visual deficiency and what its degree is.

Is there any treatment for color blindness?

Although not given that much importance, color-blind people go unnoticed in our society. This color alteration can cause problems for people who suffer from it because they cannot recognize them correctly.

For example, by not being able to identify the degree of freshness of certain foods or
Not being able to perform certain professions where you are required to correctly identify colors, as in the case of referees, police, and pilots.

Currently, there is no treatment to treat color blindness. However, there are contact lenses or special glasses that can help. At the same time, although it is a visual tool that can help, it does not solve the problem.

However, a few years ago, research was being done with monkeys at the University of Washington by the Neitz couple to treat color blindness by genetically modifying the cones for red and green color.

Where does the name color blindness come from?

It is named after John Dalton (1766-1844), an English chemist, mathematician, naturalist, and meteorologist, who wrote the first scientific paper on color vision deficiency, ‘Extraordinary facts relating to color vision.’ Dalton also suffered from this condition.