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Madison was always the first to volunteer to read aloud, however today she sits frowning at the page in her book and glances tentatively at her teacher. The story in the reader is printed in purple with a blue background, and she doesn’t see any words at all.
Ethan understands the instructions to draw lines to the red balls. Unfortunately, all the balls look green to him. He guesses and gets many of them wrong. In later grades, the youngsters’ frustrations compound when asked to color maps in specific colors or interpret a litmus paper reaction.
Colorblindness or color deficiencies affect 1 in 12 boys and 1 in 200 girls. Because colorblindness can affect social interaction and educational performance, parents and teachers should be especially aware of kids with the deficiency. “Colors are used as tools of communication to teach reading and math,” says Scott Steidl, M.D., director of the vitreoretinal service at the University of Maryland School of Medicine. “Books and worksheets come in a rainbow of colors. Counting beads, chalk, maps and other activities all include color. There’s no way that kids who can’t see the material will be able to learn it. Children who are colorblind are easily misdiagnosed with learning disabilities, inattentiveness or laziness in school.”
To understand what causes colorblindness, first we must address how color is perceived. “The dazzling experience of color begins when light strikes a canvas of tightly-packed nerve cells in the back of the eye,” explains Alan Greene, MD FAAP. “These rods and cones, as they are commonly called, fire a storm of nerve impulses in response to the light, which then travel down the optic nerve to the visual centers of the brain.” These cones are cells on the retina, an area the size of a postage stamp.
The retina has red, blue, and green cones, which are sensitive to those colors and combinations of them. We need all three types to see colors properly. When our cones don’t work properly, or we don’t have the right combination, the brain doesn’t get the right message about which colors we’re seeing. To someone who’s colorblind, green grass may look tan or gray.
Those who see every color of the rainbow can distinguish between more than 100 hues (“hue” is just another word for “color”). Dr. Greene points out, “we humans are all born colorblind! The cones don’t begin functioning until a baby is about four months old. At that time, the baby undergoes a gradual transformation that is as remarkable as the scene in the Wizard of Oz when Dorothy leaves the black-and-white world of Kansas for the brilliant colors of Oz.” However, colorblind kids see only a handful of colors, and some see less than that.
Red Light, Green Light?
Many people think anyone diagnosed as “colorblind” sees only black and white, like Dorothy’s Kansas. This is a big misconception. Monochromasy, the complete absence of any color sensation, is extremely rare. There are many different types and degrees of colorblindness (more correctly called color deficiencies). By far the most common is red-green colorblindness.
Red-green blindness: Trouble distinguishing between shades of red and green. These children either do not have red cones (protanopia) or green cones (deuteranopia). They are unable to distinguish between green and red, but with their remaining two types of cones are able to see all the other colors.
Blue-yellow blindness: Difficulty telling the difference between shades of blue and green. The absence of blue cones is extremely rare.
Let’s go deeper. Protanomaly is known as “red-weakness”, meaning red, orange, yellow and yellow-green appear more or less like green. The redness component that a normal observer sees in a violet or lavender color is so weakened for the protanomalous observer that he or she may fail to detect it. Therefore, a purple flower simply looks blue.
Deuteranomaly is known as “green weakness”, which causes difficulty discriminating small differences in hues in the red, orange, yellow and green region of the spectrum.
Recognizing Colorblindness in Your Child
Diane Griffith of HealthAtoZ.com, reports that a child with a color vision problem may do any of the following:
- Refer to colors, especially primary shades, by the wrong name.
- Draw pictures differently than others (e.g., a tree trunk may be black or the grass brown.)
- Refer to a light pink or light green object as white.
- See reddish and greenish colors as similar (e.g., confusing peach and light green, or dark green and cranberry.)
Typically, an assessment for colorblindness occurs at your child’s four-year physical. The doctor will ask your child to identify a red and a green line on the eye chart. If any question remains, more precise visual testing can determine the exact nature of the problem.
In the Journal American Academy of Optometry, Dr. Terrace L. Waggoner’s new color vision theory–Color Vision Testing Made Easy–was found to be much more effective at assessing colorblindness in children than standard Ishihara and Dvorine plate tests. Waggoner’s test consists of displays made up of different colored dots with numbers or simple objects that young kids recognize like circles, stars and squares, hidden in the dots. A colorblind child will not be able to see the numbers or objects hidden inside the dots. If your child is aged 3-6 years, this color vision test has good validity, is inexpensive, allows rapid assessment and is commercially available.
Helping Young Children with Colorblindness
Remember, most color-deficient children can identify pure primary colors. In general, just different shades or tints present a problem. If your child is struggling to learn certain colors, let him or her know you understand some colors look the same to them, offering plenty of reassurance.
You can help your child by:
- Telling your child’s teacher about the condition.
- Labeling coloring utensils (crayons, colored pencils and pens) with the name of the color.
- Describing an object without mentioning color. Ask for the fuzzy pillow or the striped shirt.
- Gently suggesting clothing choices when something doesn’t match. Or, smiling and sending them out the door.
- Talking about the future and explaining that certain professions (e.g.: pilot, police officer, firefighter) require good color vision.
- Teaching the color of common objects, such as green for grass, blue for sky, etc.
- Accepting that some foods look downright unappealing to those who can’t distinguish certain colors. For instance, to your colorblind child, spinach may look like a brownish cow patty.
Dr. Greene suggests that while “there is no known way to restore color vision in those who have hereditary colorblindness, by being aware of their condition, we can help our children learn other ways to distinguish between red and green–the position of traffic lights, for instance.” And we can decorate their rooms and dress them in clothes in the millions of nuances of color that are still available to them.
The Genetic Link
According to Dr. Alan Greene, MD FAAP, colorblindness is almost always a hereditary condition. Red-green colorblindness is a recessive condition passed on the X chromosome. Only one healthy color vision gene is necessary to provide color vision. Since boys have only one X chromosome, it is much easier for them to be colorblind. If their mothers are carriers (having one normal X chromosome and one colorblind X chromosome), the sons have a 50% chance of having the condition.
Approximately 10 million American men are colorblind. All girls whose fathers are colorblind will at least carry the gene for colorblindness. In order for a girl to actually be red-green colorblind, she must have a mother who is a carrier and a father who is colorblind. This happens in only about 0.64 percent of American girls.