7 Amazing Facts About Your Eyes
#1 Did you know that your eye colour is controlled by the level of melanin in your iris?
Brown eyes have for melanin (a dark brown pigment) in their iris.
Blue eyes have less melanin, which allows collagen (which is blue), to show through.
#2 If you have blue eyes, then you share a common ancestor with every other blue-eyed person in the world.
The first person ever to have blue eyes lived sometime between 6,000 and 10,000 years ago. Before then, all people had brown eyes.
#3 Your eye contains 107 million cells which are sensitive to light.
7 million "clones" help you to see colour and details.
100 million cells called "rods" help you to see better in the dark.
#4 Did you know that 20/20 vision just means that your vision is "normal"?
Eye doctors have determined what people should "normally" be able to read on a chart from 20 feet away.
#5 If you wore glasses which flipped images upside down, your brain would correct your vision.
Although you'd see things upside down for a few days, your brain would eventually adapt, and make sure that you see everything the right way up.
#6 On average, you blink 17 times per minute, 14,280 times in a 14 hour day and 5.2 million times a year.
You blink less when you're reading, which is why your eyes get tired quickly.
You blink more when you're talking.
#7 They say "in the blink of an eye" because it's the fastest muscle in your body.
A blink typically lasts 100 - 150 milliseconds.
It's possible to blink 5 times in a single second.
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