Light is truly a magical phenomenon of our universe. It is a form of electromagnetic radiation, and interestingly, we are only able to experience a tiny fragment of this spectrum, which is known as visible light. We are only able to experience the visible light because of our eyes. Not only does this organ enable us to interact with the world uniquely, but it also has been a subject of poems, songs, and even mysticism for centuries. What makes our eyes magnificent is that we can see colors. Unfortunately, sometimes because of genetics, our eyes can lose the ability to recognize colors, and it is known as color blindness. Here are some interesting facts about it:
1. What is colorblindness?
It can be easily stated that the inability to perceive colors is called colorblindness; however, there is more to this condition. For instance, colorblindness doesn’t always mean a complete grey world because depending on the intensity of the condition, a person may be able to see all colors except one or they may be unable to differentiate between any color.
2. Color Vision Deficiency
Interestingly, in medical journals and papers, medical professionals never address this condition as colorblindness. Instead, they refer to it as color vision deficiency. No one is sure about the origins of the term ‘colorblindness’, despite it being used to such a large extent.
Although color blindness has been around for centuries, it was first medically addressed in 1803 by an English chemist and scientist, John Dalton. Interestingly, both John Dalton and his brother were colorblind, which made him curious to understand the cause of this condition. After thorough research, he discovered that colorblindness occurs because of the discoloration of aqueous humor, a liquid medium of the eyeball. He published his article in a medical journal.
4. Why does it happen?
While John Dalton’s theory behind the aqueous humor discoloration is accurate to some extent, modern science has found true factors that contribute to colorblindness. The retina in our eyes comprises two types of cells, known as rods and cones. While the former cell is designed to be extremely sensitive to light because it is used to differentiate between light and dark, cones are programmed to perceive colors. If cones are absent in the eyes or are damaged, it can also lead to colorblindness.
5. The Cones
Cones within our eyes are photoreceptor cells. It is present in all vertebrates, and they respond to different wavelengths, resulting in us perceiving colors. There are three types of cones within our eyes that respond to three distinct colors, depending on the wavelength of light. These colors are red, green, and blue.
Males are more vulnerable to colorblindness than women, as it is estimated that 1 in 12 men are colorblind compared to 1 in 200 women. Presently, there are approximately 300 million people in the world that have colorblindness to some extent. Nearly 98% of the people with this condition are red or green colorblind.
7. Types of Colorblindness
There are four types of color blindness.
Protanopia- When the eyes are unable to detect red color because of the absence of red cones, it is known as protanopia.
Deuteranopia- The most common type of color blindness is deuteranopia. It is blindness to both red and green colors, and it is caused because of abnormalities in one or more cones.
Tritanopia- In this type of color blindness, the eyes are unable to perceive the color blue, while also unable to differentiate between yellow and blue colors. This condition occurs due to abnormalities in the blue cones.
Achromatopsia- This condition can be considered true color blindness because of the total absence of color vision. The only visible colors in this condition are black, white, and some shades of grey.
Genetics play a huge role when it comes to colorblindness. Depending on both the intensity of colorblindness in parents and variations of the colorblind gene, color blindness can surface differently in the baby. For instance, if the father is colorblind and the mother has normal vision, their daughter has a 50 percent chance of being colorblind, whereas their son has an extremely rare chance of developing colorblindness. All the combinations that lead to colorblindness can be discussed with an ophthalmologist. The colorblindness gene is passed by the mother via the X-chromosome. Additionally, mutation on OPN1LW or OPN1MW genes that are present on the X-chromosome is linked to red and green colorblindness.
9. Babies are colorblind
It may be surprising to some but each baby is born colorblind. Fortunately, color vision begins to improve with age, and the ability to perceive colors is fully developed six months after birth.
10. Colorblindness in dogs
The consensus is that dogs are colorblind; however, in reality, dogs are not able to see green, yellow, orange, and red. Instead, they can recognize and differentiate between blue, violet, shades of gray, and interestingly, yellow. This is because, unlike humans, dogs only possess two cones in their retinas.
11. The Ishihara Test
One of the most widely used tests to determine red and green color blindness is the Ishihara test. It was developed by a professor from the University of Tokyo, Shinobu Ishihara, in 1963. This test typically consists of 38 plates, and each plate consists of different colored dots with different numbers or shapes. Depending on the intensity of color blindness, people have trouble identifying numbers or the shapes, difficulty distinguishing them from the background, or them unable to tell any difference, i.e., invisibility. Here, invisibility means complete color blindness.
12. Anomaloscope Test
While the Ishihara test is the widely used red-green color blindness test, the anomaloscope test is the most accurate test to date. In this, people are asked to match the colors by manually adjusting the intensity of the pallet to a reference color while peeking into an anomaloscope. The results are then calculated by an ophthalmologist to determine the intensity of color blindness.
13. Restrictive Rules
In addition to color blindness causing annoyances, regulations in some countries regarding this condition can limit one’s rights and opportunities. For instance, a driver’s license is not granted to the colorblind in Romania. Additionally, becoming an electrician is off the table for color-blind in many countries. Moreover, colorblind people cannot have a medical career in the United Kingdom.
14. Color Correction
If a person has protanopia, deuteranopia, or tritanopia, then depending on the intensity of the condition, they can be prescribed color corrective lenses or glasses, which are of different tints depending on the type of color blindness. Interestingly, only one lens is used at any given time, usually in the non-dominant eye. It enables the brain to extract more information from its surroundings.