Color blindness affects roughly 1 in 12 men and 1 in 200 women, making it one of the most common inherited conditions in humans. Worldwide, about 8% of males and 0.5% of females have some form of red-green color vision deficiency. That means in a room of 50 men, four of them likely perceive colors differently than the rest.
Red-Green vs. Blue-Yellow Deficiency
Not all color blindness is the same, and the vast majority falls into the red-green category. People with this type have trouble distinguishing between reds, greens, browns, and oranges. Within red-green deficiency, some people have difficulty with green shades specifically, while others struggle more with reds. Both types are extremely common compared to other forms.
Blue-yellow color blindness is far rarer, affecting roughly 1 in 30,000 to 50,000 people. This type makes it hard to tell the difference between blue and green or between yellow and red. Total color blindness, where a person sees only shades of gray, is rarer still, occurring in about 1 in 30,000 people worldwide. One striking exception: among Pingelapese islanders in Micronesia, 4 to 10 percent of the population has complete color blindness, likely due to a genetic bottleneck centuries ago.
Why Men Are Affected Far More Often
The lopsided ratio between men and women comes down to how red-green color blindness is inherited. The genes responsible for detecting red and green light sit on the X chromosome. Men have only one X chromosome, so a single altered copy of either gene is enough to cause color vision deficiency. Women have two X chromosomes, which means the working copy on one chromosome can compensate for a faulty copy on the other. For a woman to have red-green color blindness, both of her X chromosomes need to carry the altered gene, which is statistically much less likely.
Blue-yellow deficiency works differently. It’s carried on a non-sex chromosome, so it affects men and women at equal rates. The same is true for total color blindness.
Rates Vary by Ancestry
Color blindness isn’t evenly distributed across populations. A large review of studies spanning 1932 to 2022 found that people of European descent had the highest prevalence among children and adolescents at about 2.77%, closely followed by those of African descent at 2.69%. These numbers reflect combined rates for boys and girls, which is why they appear lower than the commonly cited 8% figure for men alone.
Color Blindness You Weren’t Born With
Most color vision deficiency is genetic and present from birth, but it can also develop later in life. Several diseases increase the risk, including diabetes, macular degeneration, glaucoma, multiple sclerosis, Parkinson’s disease, Alzheimer’s disease, sickle cell anemia, and chronic alcoholism. Certain medications can also affect color perception, particularly hydroxychloroquine, which is used for rheumatoid arthritis. Physical trauma to the eye from injury, surgery, or radiation therapy is another cause.
Acquired color blindness tends to behave differently from the inherited kind. It may affect only one eye, worsen over time, or involve blue-yellow confusion rather than the more common red-green pattern. If your color perception changes noticeably as an adult, that’s worth bringing up with an eye doctor, since it can signal an underlying condition.
How It’s Diagnosed
The most widely used screening tool is the Ishihara test, a series of cards covered in colored dots that form numbers or symbols. People with normal color vision can read the numbers easily, while those with a deficiency see a different number or nothing at all. It’s quick, simple, and effective for catching red-green deficiency.
For a more detailed picture, eye specialists use the Farnsworth-Munsell 100 hue test, which asks you to arrange 100 colored tiles in order as the hue gradually shifts. This test can pinpoint the exact type and severity of deficiency, distinguishing between the different subtypes of red-green, blue-yellow, and complete color blindness.
Living and Working With Color Blindness
Most people with color vision deficiency adapt without major difficulty. You learn to rely on context, brightness, and position rather than color alone (traffic lights, for instance, are read by position: top, middle, bottom). But certain tasks remain genuinely challenging. Jobs that require precise color discrimination, like electrical wiring, graphic design, or quality control in manufacturing, can pose problems. Pilots, train operators, and maritime workers typically face color vision requirements for safety reasons.
Color-correcting glasses have gained attention through viral videos showing emotional reactions, but the science is more measured. These glasses don’t restore missing color receptors. They work as specialized filters that block some wavelengths of light, which can increase the contrast between colors that normally look similar. Studies have not supported the claim that these glasses correct red-green deficiency in a meaningful clinical sense. The American Academy of Ophthalmology cautions against wearing them at night or while driving, since they reduce the amount of light reaching your eye and can slow reaction time.
For most people, color blindness is a manageable quirk of perception rather than a disability. The biggest practical hurdle is often that it goes undiagnosed for years. Many children don’t realize they see colors differently until they’re tested in school or run into confusion over something others find obvious, like whether a crayon is green or brown. Routine vision screening that includes a color test can catch it early, which helps kids (and their teachers) understand why certain tasks feel harder than they should.