Color blindness is also sometimes known as a color vision problem, color vision deficiency, or simply color deficiency. People who are color-blind do not perceive colors in the same way as other people do. They often have trouble telling certain colors apart.
To understand why some people are color blind, it is helpful to know a little about how the eye words. The retina, a thin layer of tissue at the back of the eye, has special cells called cones. There are cones that help the eye process red light, cones for blue light, and cones for green light. Color blindness is due to missing pigments in the cones of the eye.
Three Types of Color Vision Impairment
There are three main types of color blindness. In the first, the person has trouble telling the difference between red and green. In the second, the person has difficulty telling yellow and blue apart. The third type is called achromatopsia. A person with this form cannot perceive any colors at all; everything appears gray. Achromatopsia is much more rare than the first two types.
Inherited vs. Acquired Color Blindness
Color blindness can also be classified as either inherited or acquired. Inherited color blindness is more common. It is caused by a genetic defect. This means that the condition is passed on through family—someone who has close family members who are color-blind is more likely to have the condition as well.
Acquired color blindness develops later in life and can affect men and women equally. Diseases that damage the optic nerve or the retina of the eye can cause acquired color blindness. For that reason, you should alert your doctor if your color vision changes—it might indicate a more serious underlying issue.
In glaucoma the internal pressure of the eye (the intraocular pressure) is too high. The pressure damages the optic nerve, which carries signals from the eye to the brain so that you can see. According to the British Journal of Ophthalmology, the inability of people with glaucoma to distinguish blue and yellow has been noted since the 18th century (M. Pacheco-Cutillas, 1999).
Macular degeneration and diabetic retinopathy cause damage to the retina, which is where the cones are. This causes color blindness and in some cases, blindness.
If you have a cataract, the lens of your eye gradually changes from transparent to opaque. Your color vision may be dimmed as a result.
Medication and Color Blindness
Certain medications can cause changes in color vision. These include the antipsychotic medications chlorpromazine (Thorazine) and thioridazine (Mellaril).
The antibiotic ethambutol (Myambutol), which is used to treat tuberculosis, may cause optic nerve problems and difficulty seeing some colors.
Some heart and blood pressure medications, as well as medications prescribed for nervous disorders, can put individuals at an increased risk of developing acquired color blindness (Stresing, 2011).
In cases of inherited color blindness, it is often parents who first notice there is a problem with their child’s ability to recognize or tell certain colors apart. In other cases, though, the problem may be so subtle that the person does not realize there is an issue until later in life.
If you suspect color blindness in either yourself or your child, you should consult a doctor. A physician will be able to confirm the diagnosis and rule out other, more serious, health issues.
A family physician may choose to refer you to an ophthalmologist, a specialist who focuses on conditions related to the eye.
The following may be part of the process of diagnosing color blindness:
- an eye exam
- a basic vision test
- questions about the nature of your symptoms
- questions about your (or your child’s) medical history
- tests that involve asking you or your child to look at pictures composed of groups of different-colored dots to identify the object or number in the picture (for example, a number 7 made of red dots might be placed against a background of green dots)
- tests that involve asking you or your child to look at small objects such as chips and place them in groups according to their color
The inherited form of color blindness is not curable. In mild cases, the doctor may decide not to take any measures at all. In more severe cases, there are special contact lenses and glasses that can help you see colors more clearly.
If your acquired color blindness is due to underlying issues such as cataracts or another health disorder, treating them may help improve your color vision deficiency.
Color blindness can prevent a person from pursuing certain career paths where the ability to accurately identify and distinguish among colors is an essential skill.
From an overall health standpoint, color blindness is usually not a serious condition. In the majority of cases, color blindness does not significantly hinder a person’s ability to live on his or her own and carry out the tasks of day-to-day life.