The difference between the genetic makeup of men and women holds the answer to why color blindness – also known as color vision deficiency – is more common in males than females.
Per the U.S.’s National Institutes of Health (NIH), around one in 12 men suffer from the most common type of color blindness, which makes it difficult for them to tell the difference between red and green.
By contrast, this condition affects only about 0.5% of women, the NIH says.
How do humans become color blind?
Humans can develop color blindness through illness or injury affecting the eye or the brain, and from some medicines. However, it is chiefly a condition that people are born with, having inherited a genetic malfunction from their parents.
And the reason why men are so much more susceptible to color blindness comes down to the distribution of X and Y chromosomes in our cells.
What’s the role of X and Y chromosomes in color blindness?
These chromosomes determine a human’s sex: males typically have one X and one Y chromosome in each cell; females typically have two X chromosomes.
As Dr. Usiwoma Abugo, an eye expert with the American Academy of Ophthalmology, explains to the scientific publication Live Science, color blindness is normally caused by a faulty X chromosome in the cells of our eyeballs.
As women have two X chromosomes in each cell, they’re likely to have one properly functioning X chromosome that can make up for its partner if it’s deficient.
But men, with only the one X chromosome in each eyeball cell, do not possess this natural safety net against genetic color blindness.
“Women can experience color blindness, but it’s quite rare and is usually caused by something other than genetics,” Dr. Abugo tells Live Science.
Is there a cure for color blindness? How is it treated?
According to the U.S.’s National Eye Institute (NEI), there is currently no cure for genetic color blindness.
“If your color vision deficiency is happening because of another health problem,” the agency says, “your doctor will treat the condition that’s causing the problem.
“If you’re taking a medicine that causes color vision deficiency, your doctor may adjust how much you take or suggest you switch to a different medicine.”
The NEI notes that people with color vision deficiency can wear special glasses or contact lenses to help them differentiate between colors. There are also apps that help people to identify colors, by allowing them to take a photo and then tap on each area of the image.
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