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14 Unbelievable Facts About The Human Eye

My EYES. H/t this fascinating Quora thread.

1. Your retinas actually perceive the outside world as upside-down – your brain flips the image for you.

2. In addition to being upside-down, images arrive at your retina split in half and distorted.

3. Your retinas cannot detect the colour red.

4. Your peripheral vision is very low-resolution and is almost in black-and-white.

5. Got blue eyes? You share an ancestor with all other blue-eyed people across the world.

6. And if you have brown eyes, you're old school.

7. If you're blind, but were born with sight, you probably still see images in your dreams.

8. On average, you blink 17 times a minute.

9. "20/20 vision" doesn't equal perfect vision. It just means you can see 20 feet in front of you as well as the average person can.

10. If you're shortsighted, your eyeball is longer than normal. If you're farsighted, it's shorter than average.

11. Your eyes are almost the same size as they were when you were born. And newborn babies can see clearly up to 15 inches away.

12. Your tears have different compositions based on whether something's irritating your eye, or you're crying, or yawning.

13. Your eye is constantly making tiny jerking movements called "microsaccades" to stop objects from fading from your vision.

14. And finally, your eye can distinguish between 50,000 shades of grey.