Color blindness is a vision defect wherein the eye perceives some colors differently than others. This condition may be hereditary or may be caused by a disease of the optic nerve or retina.
Color blindness can be classified as inherited, partial or complete. Inherited color blindness is most common in males, affecting both eyes but does not worsen over time - in other words, once you have it, you have it. Partial color blindness affects some colors while complete color blindness, which is a rare condition, affects all your color vision. Some color blinded people, for example, see red instead of green or blue instead of yellow.