Types of Color Blindness: Causes, Symptoms, & How to Test for Them

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Co-authored by Luxme Hariharan, MD, MPH and Sophie Burkholder, BA

Last Updated: February 24, 2026 Fact Checked

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Types & Subtypes of Color Blindness

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What is color blindness?

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Causes

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Signs & Symptoms

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Testing & Diagnosis

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Facts & Statistics

Color blindness is a unique but fairly common condition that affects more than 300 million people worldwide. However, color blindness isn’t one-size-fits-all, as there are actually several versions of the condition that can affect how each individual person perceives colors, hues, and brightness. With the help of board-certified ophthalmologist Luxme Hariharan, MD, MPH, we’ll walk you through every type and subtype of color blindness, as well as the principal causes, symptoms, and diagnostic methods for these conditions.

What are the different variations of color blindness?

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Illustration of a color blindness test comparing normal vision to different types of color blindness.

Achromatopsia: Complete lack of color vision. Everything appears black, white, or gray.
Deuteranomaly: Difficulty seeing green (subtype of red-green color blindness).
Protanomaly: Difficulty seeing red (subtype of red-green color blindness).
Protanopia: Impossible to see red (subtype of red-green color blindness).
Deuteranopia: Impossible to see green (subtype of red-green color blindness).
Tritanomaly: Difficulty distinguishing yellow vs. red and blue vs. green (subtype of blue-yellow color blindness).
Tritanopia: Difficulty distinguishing blue vs. green, purple vs. red, and yellow vs. pink (subtype of blue-yellow color blindness).

Section 1 of 6:

The Types and Subtypes of Color Blindness

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Red-Green Color Blindness Red-green color blindness is “one of the most common” types of color blindness, says Dr. Hariharan, and it usually makes it more difficult for a person to see shades that contain red or green.^{[1]
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Luxme Hariharan, MD, MPH
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Expert Interview} There are four main subtypes of red-green color blindness: deuteranomaly, protanomaly, protanopia, and deuteranopia.^{[2]
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- Deuteranomaly: Makes it difficult for a person to see green, so they’ll see mostly blue and yellow. Most colors will look dull or muted. This is the most common subtype of color blindness.
- Protanomaly: Makes it difficult for a person to see red, so reddish hues will likely appear as dark gray, and any red-containing color may be dulled or muted.
- Protanopia: Makes it impossible for a person to see red, so most colors will look like shades of blue and gold. It may be difficult to distinguish between red and black, and other dark colors (e.g, brown) may appear as green or orange.
- Deuteranopia: Makes it impossible for a person to see green, so most colors will look like shades of blue and gold. It may be difficult to distinguish between green and red, as well as between green and yellow.
Meet the wikiHow Expert

Luxme Hariharan, MD, MPH, is a board-certified pediatric ophthalmologist who specializes in preventing childhood blindness and serves on several committees within the American Academy of Ophthalmology.
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Blue-Yellow Color Blindness Blue-yellow color blindness makes it difficult to distinguish between a variety of different color combinations, mostly within the blue/green/yellow color families. This often occurs because the blue cones in one’s eyes are missing or not functioning correctly.^{[3]
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Go to source} Blue-yellow color vision deficiency is much rarer than red-green color blindness, and it encompasses two different subtypes: tritanomaly and tritanopia.^{[4]
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- Tritanomaly: Makes it difficult to distinguish between blue and green, as well as yellow and red. An affected person will mostly see red, pink, and lavender.
- Tritanopia: Makes it difficult to distinguish between blue and green, purple and red, and yellow and pink. May also dull the appearance of colors.
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Also known as monochromacy and achromatopsia, complete color blindness means that a person can’t see color at all. People with complete color blindness essentially see the world in black, white, and gray, and they may also experience enhanced light sensitivity or difficulties seeing clearly. This type of color blindness is extremely rare, with estimates that one in every 30,000–40,000 people have it worldwide.^{[5]
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Section 2 of 6:

What is color blindness?

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Also called color vision deficiency, this common condition leads to a reduced ability to distinguish between certain colors (e.g., red vs. green) compared to people with normal vision. This happens due to missing or non-functional cone cells in the retina of the eye. These cones are used to detect colors, so when they’re not working properly, a person will struggle to see certain colors, distinguish between shades, or perceive hues as bright or vivid.^{[6]
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Section 3 of 6:

Causes of Color Blindness

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Most types of color blindness are caused by genetics. More specifically, color blindness is caused by inherited genetic mutations that affect the cone cells in the retina of one’s eyes (this is most common with red-green vision deficiency).^{[7]
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Go to source} For example, says Dr. Hariharan, “male colorblindness is often [passed down] from fathers,” so it’s more likely for a man to have it if their father or grandfather had it.^{[8]
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- However, color blindness can also occur later in life due to conditions that damage the retina or optic nerve, including glaucoma, diabetic retinopathy, and optic neuritis.
- Other chronic illnesses like multiple sclerosis, Alzheimer’s disease, and leukemia can increase the chances of developing color blindness.
- Aging can also cause a natural degeneration of the eye’s lens, as can certain medications and long-term exposure to industrial solvents or toxic chemicals.

Section 4 of 6:

Signs & Symptoms of Color Blindness

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The most common sign of color blindness is difficulty distinguishing distinct colors. “Differentiating between red and green would be the [main] thing to look out for,” says Dr. Hariharan, which may present as “difficulty in [perceiving] contrast, like looking at screens or looking at other things.”^{[9]
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Luxme Hariharan, MD, MPH
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Expert Interview} While red-green colorblindness is the most common, another sign of color blindness would be difficulty distinguishing between shades of blue and yellow, or perceiving colors as being duller or more muted than they actually are.^{[10]
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- Additionally, look out for “children who are having difficulty with speech,” instructs Dr. Hariharan. “80% of learning is visual,” so color blindness may be at fault for a child having speech difficulties.^{[11]
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- Otherwise, concludes Dr. Hariharan, take note of whether someone has a family history of color blindness, and be sure to visit a professional for diagnosis if you suspect any vision challenges.^{[12]
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Section 5 of 6:

How to Test for & Diagnose Color Blindness

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You can test for color blindness online, but visit a doctor for a final diagnosis. Many websites offer color blindness tests based on authentic medical exams, such as the Ishihara Color Test and the Farnsworth-Munsell 100 Hue Test. While you can certainly take these unofficial tests to see if you might have color blindness, the best thing to do is to go “to a visual professional, because there are different tests based on different ages, and how you administer the test is important,” says Dr. Hariharan.^{[13]
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- “So, if there’s a question of colorblindness or any doubt,” continues Dr. Hariharan, “it’s important to just see an ophthalmologist or an optometrist that can do a test for that.”^{[14]
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- If you don’t already have an ophthalmologist or other eye doctor, search online for “optometrist near me.” Request a consultation or appointment, and ask the physician to perform a comprehensive color vision test and color blindness screening.
- Is color blindness treatable? As of now, most types of color blindness are not curable, but they can be managed with special color blindness glasses that can help to enhance color contrast. However, if your color blindness stems from an underlying health condition, medication, or non-genetic cause, it may be possible to reverse or improve the vision deficiency by treating that root issue.^{[15]
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Section 6 of 6:

Facts & Statistics About Color Blindness

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Color blindness is more common in men than in women. It’s estimated that, worldwide, 1 in 12 men has some level of color blindness, while only 1 in every 200 women has color blindness.^{[16]
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All babies are born (partially) color blind. When babies are born, they’re not totally color blind, but they have muted color vision. As a result, they can see very little color and may have trouble distinguishing between similar hues. As babies grow, however, their color vision improves and is thought to be fully developed by the time they’re six months old. If their color vision doesn’t improve by around this time, they may have color vision deficiency.^{[17]
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There’s a remote island where 10% of people are completely color blind. Pingelap is a remote atoll in the Federated States of Micronesia. Allegedly, after a typhoon in 1775, the island’s (already small) population was heavily reduced. One of the typhoon’s survivors, however, carried a rare gene for total color blindness, which was then passed on to later populations. Today, the island only has a population of 250 people, and roughly 10% of them are believed to have the gene for complete color blindness.^{[18]
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People with red-green color blindness see peanut butter as green. Because people with this type of color blindness often have trouble distinguishing between red and green, the tan or orangey color of peanut butter may appear as green, olive, or beige. And this isn’t even the only food-related challenge for color blind people!^{[19]
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- Some people with color blindness can struggle to tell when a banana is ripe based on color, and they may also have a hard time cooking meat to a proper temperature (without the help of a meat thermometer, that is).
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Some countries have legal barriers for people with color blindness. In Romania, for instance, people with color blindness aren’t allowed to obtain a driver’s license.^{[20]
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Research source} In England, color blindness can make it difficult to become a doctor, while the United States has a similar rule about color blind people being restricted from becoming pilots.^{[21]
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