Eye Know

March 26, 2012

Torah Kachur

On a recent girls road trip we got onto the topic of the size of the human eye.... because that is what my friends do... don't judge.  It got me thinking about the size of a human eye at birth and the ultimate adult size, and all the other things I don't know about the adult eye.


At birth the human eye is about 16-17 mm in vertical diameter while the adult eye is pretty constant between individuals at 24mm in diameter.  In other words, the human eye increases its size by about 50% over a lifetime with most of that growth occuring in the first 3 years of life and stopping at about puberty.  The eye increases its mass by 50% while the rest of the body increases by about 2000% (not including the super fat people that weigh like 3425lbs). 



This account for the innocent little peepers that babies have that seem to fill their whole face.  Only to get smaller and more cynical as life goes on.


All babies are born with less pigment deposition than their final eye color and that color, called melanin, gets slowly deposited over the first six months.  This is why caucasian babies have blue eyes at birth.  The pigment is to protect our precious windows to the world from the world itself, UV light in particular.   The amount of melanin and it's deposition pattern is determined by our genetics but eye color is considerably more complex than just blue eyed man meets blue eyed woman and have blue-eyed children.  In fact, brown eyed children have come from blue eyed parents - without any involvement from the milkman.


We, at Science in Seconds, seem to be particularly fascinated with our most complex and backwards organ - Eva wrote a book of a blog about the eye not too long ago, while Rheanna has an all-consuming fear of having an umbrella stick her in the eye and I have also explained how we can have Super Sight - a la Superman.  But for some reason we have never sat around with our girlfriends and talked about eyeball size over a glass of wine....strange....



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