The Four Types of Color Blindness
Worth knowing: Deuteranomaly, the most common form of red-green color blindness, affects an estimated 6% of men and less than 0.5% of women.
Color vision depends on three types of light-sensing cone cells in the retina, tuned to red, green, and blue wavelengths. Color blindness happens when one or more of these cone types works differently than expected, or is missing altogether. Which cones are affected determines which type of color blindness a person has.
Red-Green Color Blindness
Red-green types are by far the most common, accounting for the vast majority of color vision differences. They come in two forms: protanomaly (weak red cones) and deuteranomaly (weak green cones), plus rarer total absences called protanopia and deuteranopia. People with these types often struggle to tell red, orange, brown, and green apart, especially in dim lighting or on small color swatches.
Wondering which type of color vision difference matches what you're experiencing? Our free test separates results by category.
Take the Color Blind Test →Blue-Yellow Color Blindness
Tritanomaly is much rarer than red-green types and affects the blue-sensing cones. It makes blue look more green, and yellow can be hard to distinguish from light gray or violet. Because it is uncommon, tritanomaly is sometimes misread as a red-green deficiency by people who haven't been tested with tools designed to separate the categories.
Total Color Blindness (Achromatopsia)
Achromatopsia is the rarest and most severe type, affecting a very small fraction of the population. People with this condition see the world only in shades of gray, black, and white, and often experience light sensitivity and reduced visual sharpness as well, since it usually involves all three cone types rather than just one.
How the Types Differ in Everyday Life
The practical effect of each type depends on which colors it involves. Someone with deuteranomaly might mix up green and brown packaging on a shelf, while someone with tritanomaly might struggle more with blue-and-yellow warning signage. This is why medical overviews that treat "color blindness" as one single condition can be misleading — the experience is genuinely different depending on the type.
What Causes These Differences?
Most color vision differences are inherited genetically and present from birth, which is why they are far more common in men than women — the relevant genes sit on the X chromosome. A smaller number of cases are acquired later in life through eye disease, certain medications, or aging, and these can affect any of the cone types.
Your results suggest possible color vision differences? Check which type is the closest match with our free interactive test — it separates results into categories that most standard checks skip.
Check Your Color Vision Type →For more background, see National Eye Institute (www.nei.nih.gov).
Frequently Asked Questions
What are the main types of color blindness?
The main types are red-green color blindness (deuteranomaly and protanomaly), blue-yellow color blindness (tritanomaly), and total color blindness (achromatopsia). Red-green types are the most common by far.
What is the most common type of color blindness?
Deuteranomaly, a form of red-green color blindness, is the most common type. It affects a large share of men of Northern European descent and makes green shades look more red.
Can you have more than one type of color blindness?
It's uncommon but possible to have overlapping deficiencies. Most people with color vision differences have one dominant type, most often within the red-green category.
How do I know which type I might have?
An online color vision test that separates results by category can suggest which type is most likely. A clinical diagnosis requires a comprehensive eye exam with an optometrist or ophthalmologist.
Is color blindness the same severity for everyone?
No. Severity ranges from mild, where some colors are harder to distinguish in low light, to severe, where certain hues cannot be told apart at all. Achromatopsia, true total color blindness, is rare.