What causes color blindness?
The most common types of color blindness are the red-green types which are also called protan ("pro-tan") color blindness and deutan (“do-tan”) color blindness (see Types of Color Blindness for more information about these). Red-green color blindness is an inherited condition caused by recessive genes on the X-chromosome. These genes cause a molecular substitution to be expressed in the retinal photopigment molecule, which in turn, causes its spectral absorption to be shifted in such a way that the available information is reduced (we also call this an “overlap”).
Color vision also declines with age. Studies have shown the Total Error Score on the FM-100 color vision test increases from about 100 at age 20 to over 200 by age 70.
Color blindness and color vision deficiency can also be caused by natural aging processes in the eye, and by low vision disorders such as glaucoma, cataracts, and macular degeneration, as well as metabolic and vascular diseases.
Color vision loss can also be a side effect of drugs, or a result from exposure to neuro-toxic chemicals such as styrene, perchloroethylene, toluene, carbon disulfide, n-hexane, and mercury.