An estimated 300 million people worldwide are color blind. This usually means that you cannot distinguish between certain shades of colors. They have a hard time telling how bright a bright colour is. However, color blindness does not equally affect men and women. According to the Cleveland Clinic, the condition affects about one in 12 men, compared to one in 200 women.
So why are more men color blind than women?
The answer comes down to genetics that govern the function of the human eye. People use special cells on the back of their eyeballs called cones to see the colour. There are three types of cone cells, each of which is tuned to be most sensitive to light at a particular wavelength.
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“There are three types of cones that see colors: red, green and blue,” Dr. Usiwoma Abugo, clinical spokesman for the American Academy of Obstetrics, told Live Science in an email. “If one or more of these color cone cells are not present or are not functioning properly, color blindness occurs.”
The most common form of color blindness is red-green color blindness. This happens when people are born without a cone-shaped variety that is tailored to red or green light, or when their cones are lacking or misaligned to light of the wrong wavelength.
If a person has problems with a blue-sensitive cone in their eyes, this form of color blindness is less common than red-green, but it becomes blue-yellow color blindness. Also, if any kind of cone is missing or substantially damaged, it can cause a complete color blindness, also known as “complete color vision deficiency.” However, this form of color blindness is extremely rare and affects less than 1 in 30,000 people.
Related: New cells discovered by the eyes can help restore vision, scientists say
Color blindness is usually caused by recessive genetic traits associated with the X chromosome, and thus affects men more frequently than women.
Recessive traits are not usually expressed unless they inherit two dysfunctional copies of the gene, namely one copy from each parent. Therefore, people who have one functional copy of the corn cell gene usually have normal chromoscopic vision.
Most men carry one X and one Y chromosome in each cell. They inherit a single X chromosome from their mother and Y from their father. The genes responsible for the photosensitive proteins that make up the corn cells are located only on the X chromosome, so men will get only one copy of each gene, with only one chance of each functioning properly.
So if there is a mutation in its only copy, they are probably color blind. On the other hand, women usually have two X chromosomes in each cell. One is from each parent. Therefore, even if one X chromosome has a failed version of the corn cell gene, the other often carries a working copy that can be compensated. As a result, women are much less likely to develop color blindness, but they can carry and pass on the false genes that support their condition.
“Women can experience color blindness, but it is very rare and usually caused by something other than genetics,” Abugo said. Conditions such as optic nerve, cataracts, and glaucoma inflammation can cause color blindness in later years, for example.
At the moment, there are no widely available treatments for color blindness, but some researchers are investigating experimental gene therapy that can give people with visual impairments linked to genetics the opportunity to see the world in full color.
In these animal experiments and early tests with humans, scientists use harmless viruses to supply functional cone genes to the eye. These treatments have so far been used to restore full-color vision of animal models with the same genetic mutations as color blind people, and are currently being investigated in humans.
This article is for informational purposes only and is not intended to provide medical advice.
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