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Thread: Eumelanin and Pheomelanin

  1. #1 Eumelanin and Pheomelanin 
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    Today in a biology class, my teacher got onto the discussion of melanin, particularly in the eyes. I am wondering about the amounts in each eye colour. I know brown has lots of melanin, green has moderate amounts and blue has low amounts, but is this actually right? And if so how do they absorb the same amount of light required for normal vision.

    I was thinking that brown has high amounts of eumelanin, but low amounts of pheomelanin, green has moderate amounts for both, and blue has low amounts of eumelanin but high amounts pheomelanin.

    Is this correct? I can't seem to find anything on it.


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  3. #2 Im not sure 
    Forum Professor leohopkins's Avatar
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    Im not sure about the chemical composition that gives the eyes colour. However colour has got nothing to do with sight. The colour of the eyes is just the colour of the iris which is used for focus. The light that we see passes through the cornea and pupil and hits the photo-sensitive cells of the retina. My knowledge of how the eye works, unfortunately ends there.


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  4. #3  
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    Joel - I'm not into biology - but I found this, it may not be what you want but is may give you some terms you can look up and get closer -

    Another tip - I think you have misunderstood the question - read up on how the eye works - And you'll see where the mis-understanding is -
    try 'rods and cones' when you know where they are you'll spot your mistake.



    http://en.wikipedia.org/wiki/Eye_color

    Quote Originally Posted by leohopkins
    Im not sure about the chemical composition that gives the eyes colour. However colour has got nothing to do with sight.
    You do of course mean the 'colour' of the eye has nothing to do with sight, I would not make such a bland statement - it may have a less obvious effect - you an I (the non-bio's) are unaware of...
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  5. #4  
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    Thanks for the replies guy... but i thought the iris restricted/controlled how much light was let into the eye, then the cones and rods focus it onto the retina.
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  6. #5  
    Forum Professor leohopkins's Avatar
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    possibly.
    The hand of time rested on the half-hour mark, and all along that old front line of the English there came a whistling and a crying. The men of the first wave climbed up the parapets, in tumult, darkness, and the presence of death, and having done with all pleasant things, advanced across No Man's Land to begin the Battle of the Somme. - Poet John Masefield.

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  7. #6  
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    Quote Originally Posted by Joel
    Thanks for the replies guy... but i thought the iris restricted/controlled how much light was let into the eye, then the cones and rods focus it onto the retina.
    Behind the iris sits a lens which focus's the light onto the retina, the pupil is where most of the light enters the eye, The iris controls the light levels in the eye mutch like the aperture on a camera.

    The retina contains the rods and cones which convert the light they detect into nerve impulces which are sent to the brain via the optic nerve
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