What Are the Signs of Color Blindness?

Color blindness, also known as color vision deficiency, affects approximately 8 percent of males and .5 percent of females in the United States, according to Prevent Blindness America. Most people with color blindness can see some colors, and only a small number are unable to detect any type of color.

Identification

• Photoreceptors in the eye's retina are responsible for your ability to distinguish between colors. These photoreceptors, called cones, contain light-sensitive pigments that allow color recognition. When the cones lack some of these light-sensitive pigments, it affects your ability to see certain colors.

Types of Color Blindness

• Red-green color deficiency occurs when you have a hard time recognizing red and green colors or shades of those colors. People with this deficiency may be able to see red or green to some extent, but may have trouble identifying these colors depending on how light or dark the colors appear. In severe cases, these colors appear gray. Blue-yellow color deficiency is a more severe form of the disease that affects the ability to recognize blue and yellow. People who have this type of blue-yellow color deficiency may also have red-green color deficiency. In severe cases, an affected person may be truly color blind and unable to see any colors. If you have this rare condition, called achromatopsia, you will only be able to see shades of gray and black and white.

Symptoms

• Symptoms of color vision deficiency may become evident about the time you start preschool or school. Children with the deficiency have trouble correctly identifying particular colors. It isn't always easy for parents to spot color blindness, as children can often compensate for the condition. If your child knows that the sky is blue, he will be able to correctly identify the color of the sky without actually being able to see the color blue. If there is a history of color blindness in your family, you will want to mention your family history to your pediatrician, who can determine if testing is necessary.

Causes

• In most cases, color blindness is inherited. It often passes from mother to son via an X-linked recessive gene. Diseases or injuries of the optic nerve or retina can also cause color blindness, as can multiple sclerosis, glaucoma, diabetes, leukemia, macular degeneration, alcoholism, sickle cell anemia, leukemia and Alzheimer's and Parkinson's diseases. Medications used to treat heart disease, infections, high blood pressure and nervous disorders can also cause color vision deficiency. In some people, the lens of the eye turns yellow with age, affecting the way colors are seen.

Testing

• Testing for color blindness is performed by asking you to look at a series of images composed of dots. Numbers are placed in the middle of the images in red, blue and green. If you have a color vision deficiency you will not be able to see these numbers.

Coping with Color Blindness

• There is no way to treat color blindness, but you can learn to compensate for color loss in a number of ways. Tinted eyeglasses may make it easier to tell the difference between colors, and you may find that you can distinguish colors by how bright or dark they are. Memorization of certain color orders can be helpful. Remembering that the red light is always located at the top of a vertical traffic light and the green light is always at the bottom can help a person with color blindness compensate for the lack of ability to see colors.