Saturday, March 30, 2013

Eyes in macro and more rayleigh LOL

Oh, the colours of the eye. I read something quite interesting today... Eyes, namely, the irises, they can only be 2 colours. Clear, or brown. The other colours are... Well, they're not caused by the object actually being coloured. Brilliant, right?

As I was saying, the brownness in your eyes are pigments; Little splotches of colour, in essence. Organic colouring is called pigments. Or something along those lines. Were full of it. Basically all the colours of our bodies are created when hemoglobin, and melanin, our natural pigment, both skin and eye, combine to make colours together. Brilliant, right?

To give you some interesting perspective, the only difference between bright skinned people and dark skinned people the difference in concentrations of melanin in their respective skin cells!

Back to the topic, aye (THAT RHYMES WITH EYE HAHA). So what are the other colours? Obviously, some people have blue eyes. Or green. Can you guess? YES IT'S RAYLEIGH SCATTERING

Ive written about it a couple times already... Slight dejavu, here. Anyhow, it's the same kind of elastic scattering that makes the sky look blue! How? Structural colouring! The atoms and such, in your eyes, are structured in a very specific way, that bends light in the same way as individual particles in the sky do!

Lots of animals, especially feathered such, make use of structural colouring (What evolutionary purpose it serves, I do not know.). Take the feathers of a peacock, for example. Or the iridiscent feathery wings of a duck. They kinda shift colour when the angle of view changes, and this is a telltale, but not conclusive, sign that indicates structural colouring.

The results of the mingling of these pigments and this structure are the beautiful orbs of spectation that we get to carry in our heads. Fucking brilliant.


I made this little experiment. Mouse over the pictures, I implore you.


  1. That's quite interesting!

    Another fun fact is that the iris of albinos looks red. Since it lacks pigments, it is of course transparent, meaning you can see the blood inside of their eyes!

    The same thing goes for when people get photographed (with only one flash of light); normally the pupil contracts when light is directed towards it, but the time between the flash and the taking of the picture is short, and the iris cannot contract the hole that is the pupil that fast. Hence, the flash of light shines through the dark pupil and reveals the blood behind it! This is why people often appear to have red eyes in pictures (this naturally doesn't work if you use a camera that flashes twice).

    1. The part about albinos is actually partly untrue. Albinos can still posess the genes that cause structural colouring in the eyes, and blue eyed albinos aren't uncommon. Their eyes are, though, naturally lighter, because pigmental colouring is subtractive. Its good that you brought it up though!


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