• Question: Why do we have colored eyes?

    Asked by weirdboblet to Carol, John, Philip, Rebecca on 4 Jul 2012.
    • Photo: Carol White

      Carol White answered on 4 Jul 2012:

      weirdboblet – awesome question!

      I did some reading, because I didn’t know that much!

      The pupil (black bit in the middle) is a hole that lets light into your eye and the bit around your eye (the iris) controls size of the pupil and how much light is allowed in.

      Your iris has at least one pigment in it to protect it from strong light. Most people (apart from those with medical conditions) will have a pigment at the back of the iris for protection, but not everyone has it at the front bit. This is what determines the type of colour!

      No pigment at the front means the iris is transparent (see through.. kind of!) and so it will absorb red and yellow light waves. The rest of the light (blue waves) bounces off the pigment at the back of your eye.. so your eyes look BLUE.

      If you have pigment at the front, the iris absorbs different kinds of light waves. So the result is a GREY or BROWN or MIX!

      It also explains why some people have blue eyes as a child and then brown as an adult – it takes time for the eyes to make the pigment for the front of the iris.

      Now that’ cool!

    • Photo: John Welford

      John Welford answered on 5 Jul 2012:

      I didn’t know this either!

      It seems that the answer is to do with the “Rayleigh scattering” of light. It is the same reason that the sky looks blue and the blood in your veins looks blue!

      Eyes that are darker than blue have more “melanin” pigment in, the same type of pigment that affects skin colour (although the two aren’t necessarily related).

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