Types of Color Blindness Explained
Quick answer: The main types are red-green (protan and deutan), which is by far the most common, blue-yellow (tritan), which is rare, and total colour blindness, which is very rare. Most cases are inherited and affect men more than women.
Check your own colour vision: open the colour blindness test.
Red-green deficiency
This is the common one, split into protan types (reduced or absent red perception) and deutan types (green). It affects about 1 in 12 men and 1 in 200 women, because the genes involved sit on the X chromosome.
Blue-yellow deficiency
Tritan types affect blue and yellow perception. They are much rarer and affect men and women about equally.
Total colour blindness
Achromatopsia, seeing little or no colour at all, is very rare and often comes with other vision effects. Most people described as colour blind actually have a partial red-green deficiency.
How to check
An online plate test gives a quick indication, but only an optometrist can diagnose the exact type and severity. Take the colour blindness test to see how you do.
The Main Types of Colour Blindness
Colour vision deficiency isn't a single condition — there are several types, depending on which of the eye's colour-sensing cells (cones) are affected. The cones detect red, green and blue light, and a problem with one shifts how you perceive certain colours. The types fall into three broad groups: red-green deficiencies (by far the most common), blue-yellow deficiencies (rare), and total colour blindness (very rare). Within each, the deficiency can be partial (an anomaly, where a cone works but abnormally) or complete (where a cone type is missing entirely). Our colour blindness test can hint at which group you may fall into.
Red-Green Deficiencies
These are the most common by a wide margin and come in four related forms. Protanomaly is reduced sensitivity to red light, making reds look duller and darker. Protanopia is the absence of red cones, so reds are very hard to distinguish. Deuteranomaly — the single most common type of all — is reduced sensitivity to green, the mildest and most widespread form. Deuteranopia is the absence of green cones. In practice, all four make red and green (and colours containing them, like brown, orange and some purples) easy to confuse, which is why this whole group is called red-green colour blindness even though it involves the red and green cones specifically.
Blue-Yellow and Total Colour Blindness
Blue-yellow deficiency is far rarer and affects the blue cones. Tritanomaly is reduced blue sensitivity, and tritanopia is the absence of blue cones; both make blue and yellow, and blue and green, hard to tell apart. Unlike red-green deficiency, it affects men and women roughly equally. Total colour blindness, or monochromacy, is very rare and means seeing little or no colour at all, in shades of grey — often alongside other vision issues like light sensitivity. These complete forms are uncommon compared with the mild red-green types that most colour-deficient people have.
Causes and Daily Impact
Most colour blindness is inherited and present from birth. The genes for the red and green cones sit on the X chromosome, and because men have only one X, a single faulty copy causes the deficiency — which is why red-green colour blindness is far more common in men. Women, with two X chromosomes, usually need both affected to be colour blind, so it's much rarer in them but they can carry it. Colour vision can also change later in life through eye disease, certain medications, or ageing. For most people the daily impact is manageable: difficulty with colour-coded charts, traffic lights judged by position, ripeness of fruit, or matching clothes. It isn't curable, but special glasses help some people, and apps and good design make colour cues easier to navigate.
How Severe Is It? Anomaly vs Dichromacy
Colour blindness isn't all-or-nothing — it sits on a spectrum, and the type name tells you where. Anomalous trichromacy is the mild end: all three cone types are present, but one works abnormally, shifting colour perception rather than removing a colour entirely. The "-anomaly" types (protanomaly, deuteranomaly, tritanomaly) are these milder forms, and most colour-deficient people have one of them — often without much daily disruption. Dichromacy is stronger: one cone type is missing altogether, so a whole dimension of colour is lost. The "-anopia" types (protanopia, deuteranopia, tritanopia) are these. At the far end, monochromacy means little or no colour perception at all and is very rare. This is why two people who are both "colour blind" can have very different experiences — one might only slightly confuse similar shades, while another genuinely can't tell two colours apart. Knowing your specific type and severity, which a professional can establish, explains how it actually affects you.
Frequently Asked Questions
What are the main types of colour blindness?
Three groups: red-green (by far the most common), blue-yellow (rare), and total colour blindness or monochromacy (very rare). Each can be partial, where a cone works abnormally, or complete, where a cone type is missing entirely.
What is the most common type of colour blindness?
Deuteranomaly — reduced sensitivity to green light — is the most common, and it's usually mild. It's part of the red-green group, which together accounts for the vast majority of colour vision deficiency, especially in men.
What is the difference between protanopia and deuteranopia?
Both are red-green deficiencies. Protanopia is the absence of red cones, making reds hard to distinguish, while deuteranopia is the absence of green cones. Both make red and green, and colours containing them like brown and orange, easy to confuse.
Why is colour blindness more common in men?
The genes for red and green cones sit on the X chromosome. Men have one X, so a single faulty copy causes the deficiency. Women have two X chromosomes and usually need both affected, making it much rarer in women, though they can carry it.
Is colour blindness the same for everyone who has it?
No. It ranges from mild anomalous trichromacy, where colours are shifted but all cones work, to dichromacy, where a cone type is missing and a whole colour dimension is lost. Two colour-blind people can have very different experiences depending on type and severity.
Do colour blind glasses work?
They help some people, not all. Tinted glasses can boost the contrast between colours that are otherwise confused, making certain reds and greens easier to tell apart. They don't restore normal colour vision or cure the condition, and results vary by person and type.
Can you be partially colour blind?
Yes — most colour-blind people are. The common forms are anomalous trichromacy, where a cone works abnormally and colours are shifted rather than missing. This partial deficiency is much more common than the complete forms where a cone type is absent.
Which colours do colour blind people confuse most?
It depends on the type. Red-green deficiencies, the most common, cause confusion between reds, greens, browns and oranges. The rarer blue-yellow deficiencies make blues hard to tell from greens, and yellows from other shades.
Is total colour blindness common?
No, it is very rare. True total colour blindness, called monochromacy, means seeing in shades of grey and affects very few people. The vast majority of colour-deficient people have a mild red-green type and still see most colours.