What is Color Blindness?

Color Vision Deficiency

A Color Vision Deficiency

Normal vision vs. colorblind vision. The term "color blindness" is misleading, because most "colorblind" people see colors, but their color perception is limited and inaccurate. The most common form of color vision deficiency causes inaccurate perception of the colors red and green, making it easy to confuse them.


Color Blindness, or more accurately, Color Vision Deficiency, is a deficiency in the way you see color and distinguishing certain colors, such as blue and yellow or red and green. It is typically an inherited condition that affects males more frequently than females. According to Prevent Blindness America, an estimated 8 percent of males and less than 1 percent of females have color vision problems.

Red-green color deficiency is the most common form of color blindness.  Much more rarely, a person may inherit a trait that reduces the ability to see blue and yellow hues. This blue-yellow color deficiency usually affects men and women equally.

Symptoms And Signs

Do you have difficulty telling if colors are blue and yellow, or red and green? Do other people sometimes inform you that the color you think you are seeing is wrong?

If so, these are primary signs that you have a color vision deficiency. Contrary to popular belief, it is rare for a color blind person to see only in shades of gray.  Most people who are considered "color blind" can see colors, but certain colors appear washed out and are easily confused with other colors, depending on the type of color vision deficiency they have.


If you develop color vision problems when normally you have been able to see a full range of color, then you definitely should visit your doctor. Sudden or gradual loss of color vision can indicate any number of underlying health problems, such as cataracts.

[View more simulations  of what a person with color deficiency might see.]

Causes of Color Blindness/Color Vision Deficiency

Color blindness occurs when light-sensitive cells in the retina fail to respond appropriately to variations in wavelengths of light that enable people to see an array of colors.  Causes for Color Vision loss or damage include:

  • Hereditary Genetic Makeup- Most common cause.

  • Parkinson's Disease (PD). Because Parkinson's disease is a neurological disorder, light-sensitive nerve cells in the retina where vision processing occurs may be damaged and cannot function properly.

  • Cataracts. Clouding of the eye's natural lens that occurs with cataracts can "wash out" color vision, making it much less bright. Fortunately, cataract surgery can restore bright color vision when the cloudy natural lens is removed and replaced with an artificial intraocular lens.

  • Tiagabine for Epilepsy. An antiepileptic drug known as tiagabine has been shown to reduce color vision in about 41 percent of those taking the drug, although effects do not appear to be permanent.

  • Leber's Hereditary Optic Neuropathy (LHON). Particularly prevalent among males, this type of inherited optic neuropathy can affect even carriers who don't have other symptoms but do have a degree of color blindness. Red-green color vision defects primarily are noted with this condition.

  • Kallman's Syndrome. This inherited condition involves failure of the pituitary gland, which can lead to incomplete or unusual gender-related development such as of sexual organs. Color blindness can be one symptom of this condition.

  • Aging Process Damage- Color blindness also can occur when aging processes damage retinal cells.

  • Brain Injuries- An injury or damage to areas of the brain where vision processing takes place can also cause color vision deficiencies.  

Treatment And Strategies

Gene therapy has cured color blindness in monkeys, according to study results announced in September 2009 by researchers at the University of Washington and University of Florida.  While early findings look promising, gene therapy would not be considered for humans until treatments are proven to be safe.

Meanwhile, there is no cure for color blindness. But some coping strategies may help you function better in a color-oriented world. Most people are able to adapt to color vision deficiencies without too much trouble. But some professions, such as graphic design and occupations that require handling various colors of electrical wiring, depend on accurate color perception.

If you become aware of a color deficiency early enough in life, you may be able to compensate by training for one of the many careers that are not as dependent on the ability to see in a full range of colors.

Diagnosing color vision deficiency early also may prevent learning problems during school years, particularly because many learning materials rely heavily on color perception. If your child has a color deficiency, be sure to speak with his or her teachers about it. Teachers and administrators can help by planning their lessons and presentations accordingly, and providing learning accommodations.

Lenses For Color Blindness

Some people use special lenses to enhance color perception, which are filters in either contact lens or eyeglass lens form.

You also can learn ways to work around your inability to pick out certain colors. For example, you might organize and label your clothing to avoid color clashes. (Ask friends or family to help!)

You might also remember items by their order rather than their color. An example would be to recognize that the red light is at the top of the traffic signal, and green is at the bottom.

New apps for Android and Apple devices may also help with color detection. 

Schedule an appointment with one of our eye care practitioners for screening, diagnosis, and additional 
advice if you have difficulty distinguishing colors, or if you have observed this difficulty in your child. 


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