• Question: Why do people become coulred blind and when its passed down to you how dose it work

    Asked by to Andrew, Elaine, Emma, Michael, Nancy on 17 Jun 2014. This question was also asked by .
    • Photo: Nancy Carlisle

      Nancy Carlisle answered on 17 Jun 2014:

      People who are color blind don’t have all the normal receptors in their eyes that are normally required to see all colors. This is genetically linked- and the gene is carried on the X chromosome. Girls have 2 X chromosomes, while boys have XY. For girls, usually if they don’t have the right gene on one X chromosome for the receptors, it will be on the other one. This doesn’t happen for boys, which is why more boys are color blind than girls! So, if you are color blind and you are a boy- you know it came from your mom’s side of the family!

    • Photo: Michael Kelly

      Michael Kelly answered on 18 Jun 2014:

      People can be colour blind for several reasons, the commonest is that their genetic make up prevents them from having the full set of photo-receptors. There are two types of photoreceptor, rod and cones. The cones are responsible for colour vision and have three sub types, called L, M and S. these provide signals for red, green and blue light.

      If one sub type missing or defective then that element of colour vision will be weaker. SO for example if the L cones are missing then it will be difficult for that person to tell different reds apart and they may confuse some reds with some greens.

      As we get older the tissues in the eye become yellower and our blue vision is affected, also some medicines and illnesses can affect our colour vision.

Comments