The Millstone Times April 2022

A World Without Colors By Pam Teel Color blindness is a usually a genetic (hereditary) condition (you are born with it). Red-green and blue color blindness is usually passed down from your parents. The gene, which is responsible for the condition, is carried on the X chromosome.

Many more men are affected than women. Eight percent of the male population are color-blind and there are estimated to be over 250 million color-blind people worldwide. The vast majority of people with a color vision deficiency have inherited their condition from their mother, who is normally a ‘carrier’ but not color-blind herself. Some people also acquire the condition as a result of long-stand- ing diseases such as diabetes, multiple sclerosis, some liver diseases and almost all eye diseases. The effects of color vision deficiency can be mild, moderate, or severe, depending upon the defect. If you have inherited colorblindness, your condition will stay the same throughout your life – it won’t get any better or worse. The retina of the eye has two types of light-sensitive cells called rods and cones. Both are found in the retina, which is the layer at the back of your eye which processes images. Rods work in low light conditions to help night vision, but cones work in daylight and are responsible for color discrimination. There are three types of cone cells and each type has a different sensitivity to light wavelengths. One type of cone perceives blue light, another perceives green and the third perceives red. When you look at an object, light enters your eye and stimulates the cone cells. Your brain then interprets the signals from the cones cells so that you can see the color of the object. The red, green and blue cones all work together allowing you to see the whole spectrum of colors. For example, when the red and blue cones are simulated in a certain way you will see the color purple. The exact physical causes of color blindness are still being researched but it is believed that color blindness is usually caused by faulty cones, but some- times by a fault in the pathway from the cone to the brain. People with normal color vision have all three types of cone pathways working correctly, but color blindness occurs when one or more of the cone types are faulty. For example, if the red cone is faulty, you won’t be able to see colors containing red clearly. Most people with color blindness can’t distinguish certain shades of red and green. Conditions like color blindness are passed from parents to their children on groups of genes called chromosomes. Some of these, called X and Y chromosomes, determine if you are male or female at birth. Males have 1 X chromosome and 1 Y chromosome, and fe- males have 2 X chromosomes. The genes that can give you red-green color blindness are passed down on the X chromosome. Since it’s passed down on the X chromosome, red-green color blindness is more common in men. This is because: Males have only 1 X chromosome, from their mother. If that X chromosome has the gene for red-green color blindness (instead of a normal X chromo- some), they will have red-green color blindness. Females have 2 X chromosomes, one from their mother and one from their father. To have red-green color blindness, both X chromosomes would need to have the gene for red-green color blindness. Blue-yellow color blindness and complete color blindness are passed down on other chromosomes, so they affect males and females equally. Color blindness can also happen if your eyes, or the part of your brain that helps you see color gets damaged. This can be caused by: eye diseases such as glaucoma or macular degeneration, nervous system diseases such as Alzheimer’s or Multiple Sclerosis, or some medicines like Plaquenil (a rheumatoid arthritis medicine). Your color vision may also get worse as you get older, especially if you get a cataract — a cloudy area on your eye. Since color blindness is considered to be a genetic disorder, regular prescription glasses are not effective. In the late 1990s, special color lenses were de- veloped to help individuals who suffered from a red and green color deficiency. These glasses are effective at bringing out shades of red and green. They also help bring a brightness to shades individuals with color blindness typically see as faded. Special enhancement lenses are effective glasses for color blindness. These lenses are most effective at correcting red and green color deficiencies. While glasses for color blindness are not as effective at correcting the inability to see blue and yellow, some patients see adequate improvement with their use. The glasses are not able to create any permanent improvements in color blindness, but are effective at changing the eyes' ability to sense different colors. It is important that patients realize that these corrective glasses for color blindness will not give them 100 percent normal eyesight. These lenses increase the differences between different shades. They make it more likely that those with color blindness will be able to see an enhanced version of the colors they find it difficult to distinguish. There are currently four main companies developing products to aid color blind people in reducing the effects of their condition: ColorMax, ColorView, ChomaGen, and ColorLite. All four companies base their efforts around utilizing tinted lenses to alter the light entering the eye. The way this works is actually quite simple. You use a lens in one or both of your eyes, the lens can either be a contact lens or in glasses frames. Because one eye has a modi- fied quality of light, the brain can use the difference in the feedback it receives from each eye to identify more information about the colors present than it would normally. You can also use tinted lenses for both eyes, but the tints must be different colors to maintain difference in what each eye is seeing. ChromaGen report that over 97% of patients in their study reported significant improvement in their color vision. Results do vary per each individual. There are many positive testimonies recorded on you tube where colorblind people, for the first time, in their lives, are able to see colors when they use the special corrective glasses. If you are color-blind, these glasses might be a solution, but not a cure, to your seeing color for the first time.

48 The Millstone Times

April 2022

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