The human eye truly is an incredible feat. Here are 25 fun and fascinating facts that will certainly make you appreciate the marvel of these two little organs.
1. Every human in the world is born colourblind
2. Every human in the world is also born without the ability to produce tears. Even though we are making crying sounds our tear ducts only start working when we are 4-13 weeks old.
3. Not everything is going to get bigger as you age. Your eyeballs stay the same size throughout your entire life. From the day you are born till the day you die your eyes do not grow.
4. In the blink of an eye. 1/10th of a second is the average length of a blink.
5. Ever wondered why reading helps you feel tired? You actually blink less when you are reading. This can cause the eyes to feel a bit more dry and exhausted than usual.
6. Each year on average you blink 5.2 million times. A 14- hour day will see you blinking 14,820 times and that means 17 blinks a minute.
7. Why do we blink? Each time we blink our eyelids clean and moisten the eyeball keeping it healthy and stopping it from drying up. Blinking is also an automatic ‘survival’ instinct – if something were heading in the direction of your eye it will start blinking straight away.
8. Our 28-gram eyeballs each contain 107 million cells that are sensitive to light. This means every cell receives visual messages from what it is exposed to. 7 million of these cells are called cones; these help us see sharp details and colours. The other 100 million cells are called rods and help us to see in the dark.
9. The human eye can see the difference between around 10 million shades of colour.
10. Every hour our eyes can process 36,000 bits of information to our brain.
11. The most active muscles in our body are those controlling our eyeballs.
12. The eyes never sleep. The human eye is the only part of our bodies that can function at 100% of it’s abilities day or night, whenever we need them. They don’t actually get tired!
13. What determines whether or not you have brown or blue eyes is the level of Melanin in your iris. Melanin is a dark brown pigment. The more Melanin the darker the eyes. The less melanin the more the collagen in the eye can come through which is blue.
14. It is believed that all blue-eyed humans have common ancestory. The first pair of blue eyes date back 6000-10,000 years ago. Prior to blue eyes everyone had brown eyes.
15. The choroid, which is located behind the retina in our eyes, is jam packed full of blood vessels. This is why we get red eyes in photos. When the light flashes it reflects the light from the back of the eye giving the eyes a red colour in the printed photo.
16. The only living tissue in our bodies that does not contain any blood vessels is the cornea.
17. The brain actually creates the colour red for us. Our retinas can’t detect a plain red colour. The yellow and green receptors pick up a blue green and then the brain mixes the colours to create red.
18. Men are 10 times more likely to be colour blind than woman.
19. Our peripheral vision is very low-resolution and picks up visuals in nearly complete black and white.
20. Just like our brains create a variation of colours for us, it also puts things straight. When our retina receives a visual message it is actually upside down and when it hits the brain it rotates the image to its actual position. Even more than this, our eyes and brain work together to create whole visuals. Not are the images just upside down when they get to the retina they are split in half!
21. Some say that up to 80% of our memories are developed by what we see.
22. Humans and dogs have a very special ability. They are the only 2 species on the planet that actively seek visual cues from other individuals. Dogs only look for visual cues when they are interacting with humans.
23. Eyelashes and Eyebrows. Not just there to accentuate our facial structure. The eyelashes act as dust and dirt catchers. Whilst our eyebrows are sponge for any sweat that might drop down our forehead into our eyes (it actually does sting)
24. Why does our nose also have to get runny and overwhelmed when we cry? The tears run down the back of our eyeballs into our nasal passage.
25. People with longer eyeballs than normal are called shortsighted. Those with shorter eyeballs are called farsighted