Being color blind does not typically mean you don’t see color. It is rare to find someone who only sees in black and white. What color blindness usually means is that a person has difficulty seeing red, green and/or blue.
We see color from impulses sent by three different types of cone cells. Cone cells detect light and are located in the back of the eye. Each set of cone cells detects one of three colors: red, green or blue. The cone cells work together and a mixture of color signals are sent to your brain where they are interpreted as a wide range of image colors.
Color blindness occurs when a person does not inherit one or more types of cone cells so they are unable to see that color, or they see the color but it is altered in some way.
It is estimated that 1 in 12 men (8 percent) are color blind, but only 1 in 200 women (.5 percent) are, according to Colour Blind Awarness.org. The reason for this is genetics. Most cases of color blindness are passed on through the X chromosome, which comes from the person’s mother.
Men have both an X and Y chromosome and women have two X chromosomes.
If a man receives a color blind gene from his mother on his X chromosome, then he will be color blind. If a woman receives one X color blind gene she will be a carrier for color blindness, but will not be color blind herself.
She can however, pass color blindness on to her male children. For a woman to be color blind, both of her X genes must possess color blind coding.
There are also acquired causes of color blindness due to chronic illness such as Alzheimer’s disease, diabetes, multiple sclerosis or Parkinson’s disease. Accidents or strokes that cause damage to the retina or brain can also cause color blindness.
Certain medications such as antibiotics, anti-tuberculosis drugs, blood pressure medications or drugs that treat mental illness can cause color blindness to occur.
Environmental or industrial exposures to chemicals like carbon monoxide or lead can result in color blindness.
People over the age of 60 have been found to have some deterioration in their ability to perceive color as well.