Due to their complexity, our eyes are being used more and more in place of fingerprint scanners for identification. Although fingerprints have 40 unique elements, the iris of our eyes has 256.
Here are some interesting facts about eyes:
1. The human eye can detect approximately 10 million different colours
The human eye can detect around 10 million colours! Although not everyone can differentiate between these many colours. Some may be colour blind, which means they find it difficult to detect some or many colours (typically red-green).
2. We see things upside down
We actually see the world upside down, yes really! It’s our brains that convert the image before us the right way up. When people are born, they are colour blind and for the first week or two, we see the world upside down. This is because we haven’t yet developed the ability to flip the image in front of us.
Bojana Danilovic from Serbia was born with spatial orientation, a phenomenon that stops her brain from converting the image in front of her the right way up. Literally seeing the world upside down isn’t as annoying as you might think. The screen on her computer is permanently flipped and she has a separate television to her family which rests permanently upside down.
3. Can you sneeze with your eyes open?
We're busting two myths here. Not only can you sneeze with your eyes open, your eyes won't pop out if you do. Although trying to sneeze with your eyes open may be tricky (the impulse to close them is very strong), doing so won’t harm you. Closing your eyes when you sneeze is a natural reflex, although nobody really knows why. It could be to stop whatever comes out of our noses from going into our eyes, or there could be no reason at all.
4. Your eyes can get sunburned
It’s not just your skin you should worry about burning in the sun. When your eyes are exposed to too much UV light, you can develop a condition called photokeratitis. This can happen from too much natural sunlight as well as artificial. It’s particularly likely in snowy conditions on mountain tops because snow is highly reflective.
Photokeratitis is a painful condition that can be avoided by always wearing sunglasses or snow goggles in bright conditions. Even on cloudy days, you should wear sunglasses as UV light can penetrate cloud.
5. Pupils dilate when we’re excited
Have you ever noticed how cats’ eyes get bigger when they look at prey, or right before they’re about to jump on your lap? Just like cats, our pupils expand when we’re excited, interested, or scared. Equally, when we’re less engaged, our pupils also decrease in size. In bright conditions, the pupil will also decrease to allow less light in, and the pupil increases in size to help you see in darker conditions.
6. Can you see mental illness in the eyes?
Researchers from the University of Aberdeen discovered that eye tests can detect Schizophrenia with 100% accuracy. In a group of Schizophrenia patients and a control group, the patients that had Schizophrenia performed worse overall. Scientists have been aware of people with Schizophrenia having abnormal eye patterns of for some time, but only now is this being used to help diagnose the mental illness.
7. What causes red eyes in photos?
When someone takes a picture of you using flash, some of that light is reflected back at the camera. Light bounces off the cornea and brightens the blood supply at the back of your eyes, producing the red eye effect in photos.
Of course, your eyes could be red for a different reason. If you find your eyes are dry, red or uncomfortable, consider using some eye drops, and if the problem still persists, visit your optician for further advice.
8. Contact lenses can’t get stuck behind your eye
Good news, it’s physically impossible for your contact lenses to get stuck behind your eyes. The eye is very clever at stopping foreign objects from getting that far back. The thin membrane that covers the eye is called the conjunctiva; this forms a blockade to any unwanted objects. If your contact lens has moved and you can no longer see it, that only means the lens is stuck on the inner, upper eyelid.
If your eyes are especially dry, sometimes a contact lens can get stuck to the front of your eye. This can also happen if you accidentally sleep in your lenses, as the lens forms a barrier between your tears and the cornea, starving it of essential moisture and oxygen. If this happens to you, apply a few eye drops, wait 15 minutes for your eyes and lenses to rehydrate, wash your hands (dry them with a lint-free towel) and then attempt to remove the lenses.
