Color blindness ranges from the inability to distinguish similar shades of a color, to the complete inability to see color. Dyschromatopsia refers to the ability to see some colors, but not others. Achromatopsia, which is rare, refers to the inability to see colors at all.

What is going on in the body?

Most of the time, color blindness is a genetic defect that is present when the individual is born. Less commonly, color blindness occurs as part of aging or is caused by a medication or disease.

What are the causes and risks of the condition?

Color blindness is usually caused by an inherited trait. Dyschromatopsia, or the inability to see some colors, occurs in about 8% of men and less than 1% of women. Color blindness may also be caused by some medications or by normal aging of the lens of the eye. Disorders of the retina of the eye, or of the optic nerve from the eye to the brain, may also interfere with color perception.