By Diane Griffith, HealthAtoZ writer
If your child draws pictures of people with green skin and houses with brown grass, you may think he's being creative. The truth is, he may be color blind.
About 10 million men in America are color blind. That's about 8 percent of the country's male population. Color blindness (also called color vision deficiency) affects less than 1 percent of women. Most color blindness is inherited. Other causes include aging, glaucoma, cataracts and certain medications.
Types of color blindness
Red-green blindness. Trouble distinguishing between shades of red and green. This is the most common type.
Blue-yellow blindness. Difficulty telling the difference between shades of blue and green.
Green blindness. Inability to distinguish the green part of the color spectrum.
Absence of color vision. Seeing only black, white and shades of gray. This condition is very rare.
What causes color blindness?
In the retina of each of our eyes are three cones. Each cone reacts to a different color of light - red, blue or green. A defect in a cone causes mild color blindness. If a cone is missing completely, the color blindness is more severe.
A boy with color blindness inherits it from his mother, who inherited it from her father. This gene (involving the X chromosome) affects the cones.
A woman who carries the gene usually has normal color vision. If she has a son, the chances are 50-50 that he will be color blind. If a woman is color blind, her sons will be, too. The condition is rare in girls. If a girl is color blind, she has inherited one affected X chromosome from each parent.
Recognizing color blindness in your child
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.)
Color blindness can't be cured. Your child may feel frustrated, but can adjust. He or she may have problems with:
Selecting the right crayon or marker
Choosing clothes that match
Reading color-coded maps or charts
Knowing when meat is completely cooked
Understanding traffic signals
Having a career that requires normal color vision (e.g., pilot, police officer, firefighter, printer, etc.)
The most common test for color blindness is the Ishihara. The child is shown a set of plates, each with a number, letter or symbol hidden in a circle of dots. The symbol is easy to see with normal vision, but invisible to someone who is color blind. Using this test, the doctor can determine what type of color blindness the child has.
Teach your child that color blindness is a unique trait, not a limitation.
Help your child by:
Accepting the color names your child uses
Describing an object without mentioning color - ask for the fuzzy pillow or the striped shirt
Gently suggesting clothing choices when something doesn't match
Telling your child's teacher about the condition
Talking about the future and explaining that certain professions require good color vision
Howard Hughes Medical Institute. Color blindness: more prevalent among males. Accessed October 27, 2006.
National Institutes of Health. Color vision deficiency. Accessed October 27, 2006.
Nemours Foundation. What's color blindness? Accessed October 27, 2006.
Optometric Physicians of Washington. Color vision deficiency. Accessed October 27, 2006.
Prevent Blindness America. Color blindness. Accessed October 27, 2006.