The term color blindness is used to describe a condition in which shades of color are difficult to distinguish. A person who is truly color blind can see only in black and white or shades of gray, although this is a rare condition called achromatopsia. The inability to distinguish between shades of color is also called color vision deficiency. Most people with this condition can see color, but they have a general inability to distinguish between red and green or blue and yellow.
Color Perception
Light enters the eyes and strike photoreceptors in the retina that contain cones. These cones are sensitive to different colors because of the pigments they contain. The cones are sensitive to either blue, red or green light. This sensitivity is due to the different frequencies of the different color wavelengths. For people who have color vision deficiency, these cones are lacking in one or more of the pigments that are sensitive to the different colors.
Causes
Color blindness can be passed on genetically. There are other causes, however, including some diseases, the exposure of the eyes to chemicals, aging and some medications. Chemicals that can cause color vision deficiency include fertilizers, styrene and carbon disulfide. Aging causes a gradual decrease of the eyes' ability to distinguish colors. Medications that can cause color vision deficiency include drugs used to treat psychological conditions, nervous disorders, high blood pressure, infections and heart problems.
Diseases
Diseases that can cause color blindness include glaucoma, diabetes, Alzheimer's disease, leukemia, Parkinson's disease and multiple sclerosis. Other diseases that can lead to color blindness are sickle cell anemia, chronic alcoholism and macular degeneration.
Diagnosis
The condition of color blindness is diagnosed via an eye examination. The patient is asked to look at a picture composed of dots. Gradient shading is used to place letters, numbers or patterns within the picture to discern the ability of the eyes to distinguish colors. Patients who have color vision deficiency will not be able to see the letters, numbers or patterns because of the similarity in the shades of dot colors.
Treatments
There is no treatment for color blindness that is inherited genetically. If the color blindness results from a disease, treatment of the disease can slow or reverse the loss.
