After reading the article earlier about color blindness, you may want to know what is the cause.
Color blindness occurs when there is a problem with the color-sensing materials (pigments) in certain nerve cells of the eye. These cells are called cones. They are found in the retina, the light-sensitive layer of tissue at the back of the inner eye. If you are missing just one pigment, you might have trouble telling the difference between red and green. This is the most common type of color blindness.
Other times, people have trouble seeing blue-yellow colors. People with blue-yellow color blindness almost always have problems identify reds and greens too.
Color blindness can be inherited. It is most commonly inherited from mutations on the X chromosome but the mapping of the human genome has shown there are many causative mutations – mutations capable of causing color blindness originate from at least 19 different chromosomes and 56 different genes.
Inherited color blindness can be congenital (since birth), or it can commence in childhood or adulthood. Depending on the mutation, it can be stationary, that is, remain the same throughout a person’s lifetime, or progressive.
The most severe form of color blindness is achromatopsia. A person with this rare condition cannot see any color. Achromatopsia is often associated with lazy eye, nystagmus (small, jerky eye movements), severe light sensitivity, and extremely poor vision. Most color blindness is due to a genetic problem. About 1 in 10 men have some form of color blindness. Very few women are color blind.
The drug hydroxychloroquine (Plaquenil) can also cause color blindness. It is used to treat rheumatoid arthritis, among other conditions.