Color blindness is a surprisingly rare condition. It is generally inherited and is more common in males; 5-8 percent of men and only 0.5 percent of women in the world are born with color blindness. The cause is attached to the X chromosome, so males have a higher risk of inheriting color blindness than females, because they have only one X chromosome. Color blindness can also result from diseases or conditions of the retina, optic nerve damage, or exposure to toxins and certain drugs.
People with color blindness are not aware of differences among colors that are obvious to most people. The cones in the eye each contain a light sensitive pigment that is sensitive over a range of wavelengths. Each person’s genes contain coding instructions for these pigments. If the coding instructions are wrong, the wrong pigments will be produced, and the cones will be sensitive to different wavelengths of light, which results in color deficiency. The colors each person sees are dependent on the sensitivity ranges of those pigments.
People with normal cones in their eyes and light sensitive pigments are able to differentiate between all colors by using cones sensitive to red, green or blue wavelengths of light. A mild color deficiency results when the sensitivity of one or more of the three light sensitive pigments is shifted.
Many people with color blindness experience very few symptoms and may not even notice that they are color blind. Symptoms include:
- Difficulty distinguishing between colors
- The inability to see shades or tones of the same color
- Trouble seeing colors and the brightness of colors in the usual way
- Inability to tell the difference between shades of the same or similar colors, particularly red and green, or blue and yellow
- Rapid eye movement (in rare cases)
Most people with color blindness are able to see a wide spectrum of colors. Total color blindness, where one sees nothing but black and white, is very rare. The three main kinds of color blindness are based on defects in the cones that respond to blue, green or red light. Red-green color blindness is most common, followed by blue-green.
Although inherited color blindness is usually diagnosed in early childhood, many people are unaware that they are color blind. Unless it affects daily life, color blindness may fly under the radar for a while. A simple color blind test administered by an optometrist can tell you if you are color deficient in any way.
To schedule an appointment, call Illinois Eye Center at (309) 243-2400.