The 3 Types of Color Blindness - Step To Health

The 3 Types of Color Blindness

Not all colour blind people perceive colours in the same way, as the condition has several manifestations. We'll show you what they are and their characteristics.
The 3 Types of Color Blindness

Last update: 03 January, 2022

Color blindness is an eye condition that’s characterized by a difficulty in perceiving color wavelengths. Most cases develop due to genetic causes, although it’s also possible to manifest color blindness due to environmental interactions. As there are several types of color blindness, it’s useful to be aware of them and their differences.

Indeed, this condition manifests in several different ways. The National Eye Institute distinguishes three types of color blindness, and these, in turn, have several subtypes. Not every patient diagnosed with the condition perceives colors in the same way, and this is something that must be taken into account in order to avoid prejudices and clichés. In the following lines, we’ll distinguish their variants and characteristics.

Main types of color blindness

In general, there are three types of color blindness: red-green, blue-yellow, and complete or total color blindness. These categories are not specific, and have subcategories that describe the possibilities of manifestation within them.

Color blindness is caused by a defect of the retinal cones (specialized cells) in picking up or interpreting color wavelengths. This is either because they don’t work or because there’s an absence of any of them. We’ll now go into detail about the types of color blindness to distinguish the differences between them.

Red-green color blindness

A woman with sore eyes.
Color blindness can affect a person’s ability to perform daily activities in many different ways.

Red-green color blindness is the most common manifestation of the condition worldwide. According to studies, it affects up to 8% of men of European descent, a percentage that drops to 0.4% in the case of women.

Those who suffer from this variant have difficulty distinguishing red and green tones due to the absence or malfunction of photoreceptors. These genes are encoded on the X chromosome, so this explains why it’s more common in males. The following subtypes are distinguished:

  • Deuteranomaly: This is the most common type of red-green color blindness and affects people by making the color green take on a weaker tone, although they can still discriminate some shades. This causes green to be perceived as very close to red when there’s a lot of light, and close to black or brown (the dark shades of green) when there’s little light. It is also known as deutan color blindness.
  • Deuteranopia: People with this variant have trouble distinguishing the red, yellow, and green wavelengths of the spectrum. This is because they lack photoreceptors for the color green, or they don’t work at all. Therefore, they can’t discriminate this color in relation to those mentioned above. The color spectrum is assimilated almost entirely in shades of yellow and blue.
  • Protanomaly: People with this variant have a mutation in the photoreceptor for the red wavelength, which means that the red wavelength is interpreted more weakly. In bright light, red will be closer to shades of green, deep pink to grey, and deep violet to blue, among others.
  • Protanopia: In this case, patients lack the photoreceptors for the color red, which results in red being confused with green, yellow, or grey depending on its tone and the absence or presence of light. For example, shades of violet, lavender, and purple are indistinguishable from blue, and the red of the traffic light is perceived as dull.

In general, we can say that deuteranomaly and protanomaly are the mildest forms of red-green color blindness. Most people have no complications in their day-to-day lives, and many of them are even unaware that they’re color blind. Deuteranopia and protanopia are the most severe variants and can create moderate complications in the perception of reality.

Blue-yellow color blindness

Blue-yellow color blindness is the second of the most common types of color blindness. It’s also known as tritan color blindness, as the former name can be misleading. Indeed, those who suffer from this variant have difficulty appreciating blue and bluish-green tones.

People with this deficiency also have trouble distinguishing between yellow and reddish tones. Although it can be inherited, many people develop this type due to eye conditions or natural age-related degeneration. There are two subtypes:

  • Tritanomaly: People with this type have a defect in the photoreceptors of the blue pigment, which causes it to be seen in pale or faint shades. It’s a rare form of color blindness that affects men and women equally. People with this variant have trouble differentiating between blue and green, and red and violet.
  • Tritanopia: Patients with this type lack photoreceptors of the blue wavelength, so they can’t distinguish this color at all. The subject won’t be able to differentiate between blue-green, purple-red, and yellow-pink, among other combinations.

As with the previous types of color blindness, the difference lies in an abnormality of the cone in receiving the wavelength (it perceives it less brightly, or as a duller or less intense tone). It may also be totally absent or be deficient in its functioning, and this prevents a person from appreciating color regardless of its hue.

Complete or total color blindness

An eye specialist.
For the exact determination of the type of color blindness, it is important to consult an ophthalmologist.

Complete or total color blindness is the inability to distinguish the colors of the wavelength spectrum. It isn’t related to color agnosia, a condition in which the patient can’t perceive or interpret colors, although his or her eye is able to distinguish them physiologically.

It’s the least frequent type of color blindness, as, according to experts, only 1 in 30,000 people suffer from it. Like the previous case, it can develop with different degrees (mild, moderate, or severe), but, generally, two subtypes are differentiated:

  • Rod monochromacy: This is often called achromatopsia and is distinguished by the absence of cones in the retina. In addition to not being able to distinguish colors, people have trouble seeing in moderate and high light intensity settings (their vision is better when there’s less light).
  • Cone monochromacy: People with this variant have rods and cones. They also show sensitivity to light and reduced visual acuity, but this is less than in the previous case. According to the severity, they can distinguish differences in brightness, but not in shades.

In general, a person with total color blindness perceives reality in different shades of gray. This is the most severe form of the condition, although, fortunately, the least common. It’s often accompanied by vision problems that make it even more difficult to perceive objects and things.

This concludes our explanation of the different types of color blindness. In its milder forms, especially the first two variants, many of the patients will be unaware that they have this condition. Often it’s a condition that’s stable for life and affects both eyes equally. If you think you have either variant, don’t hesitate to consult a specialist.

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  • Kohl, S., Jägle, H., Wissinger, B. y Zobor, D. Acromatopsia. GeneReviews® [Internet] . 2018.
  • Wong, B. Color blindness. Nature Methods. 2011; 8(6): 441-442.