aviation medical examiner

Color vision testing and color blindness.

Types of Color Vision Tests – AOPA.

Color blindness is a mostly inherited vision abnormality where there is deficiency in perception of red, green, and blue due to abnormality of cone cells located in the eye. Red-green color blindness is passed from mother to son on the 23rd chromosome (sex chromosome). The 23rd chromosome is made up of two parts (XX for female or XY for male).

For a male to be color blind he needs to receive one abnormal X chromosome from mom. For a female to be color blind both X chromosomes need to be abnormal. Therefore she will need to receive an abnormal X chromosome from a color blind father and an abnormal chromosome from a carrier mom. As a result a color blind woman (2 abnormal X chromosomes) will have all color blind sons. Fortunately, red-green color blindness is much rarer in females.

On the other hand, since blue color blindness is not carried on the sex chromosome, it affects men and women equally.

See colorblindawareness.org for informative pedigree charts and explanations on the risk for color blindness. How does color blindness affect you if you are a pilot, or a merchant mariner and what kind of tests can be used to diagnose color blindness? See link above from AOPA (Aircraft Owners and Pilots Association) for more information. For the commercial truck driver, currently only gross color vision with the ability to distinguish among traffic signals and devices showing standard red, green, and amber is required.