Some antibiotics, malaria preventing drugs, diuretics and barbiturates may also alter color vision. Because the gene for color vision is found on the X chromosome, color deficiencies are more frequently found in men than in women. Color vision deficiencies are a genetically recessive trait, meaning that if at least one gene for color vision is normal, the individual will have normal color vision. Because men have a single X chromosome and women have two X chromosomes, men are much more likely to be color deficient that women. Individuals with normal vision may simulate these altered color perceptions by looking through colored glasses, which is why sunglasses should be a neutral color.
Monochromats view colors similar to the perception from a black and white television.
Certain diseases are associated with color vision deficiencies. These include inflammation of the optic nerve, glaucoma, cataracts, multiple sclerosis, central serous retinopathy, cataracts and toxicity from drugs or poisons. Yellowing of the lens of the eye with age may also alter color perception. There are two basis types of color deficiency. Trichromats simply have a relatively fewer number of cones for one type of color.