Colour blindness is an X- linked recessive disorder that is caused by a difference in how one or more of the light-sensitive cells (called cones) found in the retina of the eye respond to certain colours. In a person suffering from colour blindness, the development of the cone cells may be faulty and the cone cells might be missing, or less sensitive to light or the pathway from the cone cells to the brain may not have developed correctly. This results in a difference in sensitivity in one or more cones due to which the person can become colour blind.