January 2012

Decoding Color Blindness

Color vision deficiency, often referred to as color blindness, is often a misunderstood condition. This is partially because there are several different causes of color blindness, as well as a variety of ways the condition develops. Is it true that only males are at risk? Are people born with color blindness? Read on to find out what is fact and what is fiction:
 
According to the U.S. National Library of Medicine (NLM) and the National Institutes of Health (NIH), color blindness occurs when there is a problem with the color-sensing pigments in certain nerve cells, or cones, within the eye. The cones are found in the retina, the light-sensitive layer of tissue that lines the back of the eye. Even if just one pigment is missing, you may have trouble telling the difference between certain colors or shades. Symptoms include not only an inability to identify colors, but also trouble seeing the difference between shades and brightness.
 
Red-green deficiency is the most common type of color blindness, followed by blue-yellow. People with blue-yellow color blindness usually have problems identifying reds and greens, too. The NLM and NIH also report that the most severe form of color blindness is achromatopsia. People with this rare condition cannot distinguish any color and see everything in shades of gray. Achromatopsia can be associated with a number of different conditions such as lazy eye and nystagmus (jerky eye movements).
The Mayo Clinic lists multiple causes of color blindness:
  • Genetics: Approximately one in 12 males of Northern European descent is born with some degree of red-green color deficiency. Most females possess genes that counteract the deficiency, so less than one percent of females of Northern European descent have this type of color deficiency. In other populations, the prevalence of red-green color deficiency is lower. Blue-yellow color deficiency is inherited by fewer than one in 10,000 people worldwide. Individuals can inherit a mild, moderate or severe degree of the disorder, and the severity doesn't change over a person’s lifetime if the cause is inherited.
  • Diseases: Diabetes, Alzheimer's disease, Parkinson's disease, leukemia and sickle cell anemia can all contribute to color vision deficiency. Other eye diseases, such as glaucoma and macular degeneration, can impact the ability to see color as well.
  • Medications: Certain drugs that are used to treat conditions like high blood pressure and psychological disorders can cause color blindness.
  • Chemicals: Exposure to chemicals like carbon disulfide and fertilizers can cause loss of color vision.
  • Aging: The ability to see colors can deteriorate slowly as a part of aging.
Although there is no direct treatment for color blindness, specially designed glasses and contact lenses can often help. Many people, especially those with mild color blindness, are able to adjust without much difficulty.
 
Whether or not you think you may be having problems with color, it’s always good to have regular eye exams with an optometrist or ophthalmologist. They can test color vision quickly and easily, as well as ask questions about your family history, current medical conditions and medications to help identify any possible issues.
 
For more information about color blindness from the National Library of Medicine, National Institutes of Health and the Mayo Clinic, visit www.nlm.nih.gov/medlineplus/ency/article/001002.htm and www.mayoclinic.com/print/poor-color-vision/DS00233/DSECTION=all&METHOD=print.