Our eyes are one of the most fascinating and complex parts of the body. Almost every animal in the animal kingdom relies on them everyday, but how much do we really know about eyes, and how they work?
Eyes are thought to have first developed in animals, in a very basic form, around 550 million years ago.
The world’s most common eye colour is brown
Your eye is the fastest muscle in your body – hence why when something happens quickly, we say ‘in the blink of an eye!’
You see with your brain, not your eyes. Our eyes function like a camera, capturing light and sending data back to the brain.
Dogs can’t distinguish between red and green.
We have two eyeballs in order to give us depth perception – comparing two images allows us to determine how far away an object is from us.
Eye colour is determined by the amount of melanin in your iris.
20/20 vision simply means that you have normal vision.
Your eyes become tired when you read or stare at a computer, this is because you blink less often.
Although our nose and ears keep growing throughout our lives, our eyes remain the same size from birth.
You blink more when you talk.
Diabetes is the number one cause of blindness in adults in the UK.
People generally read 25 times slower on screen than on paper.
All babies are colour blind at birth.
The first blue-eyed person is said to have lived 6,000-10,000 years ago.
It’s impossible to sneeze with your eyes open.
An ostrich’s eye is bigger than its brain.
The human eye can see 500 shades of grey.
You blink on average 4,200,000 times a year.
The cornea is the only tissue in the human body which doesn’t contain blood vessels.
The human eye can function at 100% at any given moment, without needing to rest.
Smoking reduces your night vision.
Eyelashes have an average lifespan of five months.
A newborn baby will cry, but not produce any tears. Babies do not produce tears until they are around six weeks old.
Our eyes are made up of over 200 million working parts.
In the right conditions and lighting, humans can see the light of a candle from 14 miles away.
The shark cornea is used in human eye surgery as it is the most similar to the human cornea.
80% of vision impairment worldwide is curable.
The human eye only sees three colours, red, blue and green. All other colours are combination of these.
A camel’s eyelashes can measure up to 10cm long, to protect its eyelashes from blowing sand and debris in the desert.
One of the most common cosmetic injuries is poking the eyeball with a mascara wand.
The eye muscles are the most active muscles in the human body.
The eyes of a chameleon are independent from each other, allowing it to look in two different directions at once.
It’s possible to blink five times in a single second.
Your eyes contain around 107 million light sensitive cells.
Your eyes contain 7 million cones which help you see colour and detail, as well as 100 million cells called rods which help you to see better in the dark.
Geckos can see colours around 350 times better than a human, even in dim lighting.
A blink typically lasts 100-150 milliseconds.
Blue-eyed people share a common ancestor with every other blue-eyed person in the world.
Our eyes close automatically to protect us from perceived dangers.
We have all have unseen, and harmless, microscopic creatures living in our eyelashes.
The muscles in the eye are 100 times stronger than they need to be to perform their function.
When your eyes are watering it may be a sign of dry-eye, and your eyes are producing more moisture to compensate.
Your eyes start to develop just two weeks after conception.
Owls cannot move their eyeballs – which has led to the distinctive way they turn their heads almost all the way around.
The older we get, the less tears we produce.
Eyes are able to process 36,000 pieces of information in a single hour.
Colour blindness is more common in males.
Reading in dim lighting does not damage your eyes but it may tire them out.
Sitting too close to a TV won’t give you square eyes.
The four-eyed fish can see both above and below water at the same time.
Oily fish, vitamin A and vitamin C all help to preserve good eyesight.
When working at a computer, you should follow the 20-20-20 rule – look at something twenty feet away from your computer every twenty minutes for twenty seconds.
Snakes have no eyelids, just a thin membrane covering the eye.
Eye transplants are currently impossible due to the sensitivity of the optic nerve.
Only one sixth of the human eyeball is exposed.
Pirates believed that wearing gold earrings improved their eyesight.
Snakes have two sets of eyes – one set used to see, and the other to detect heat and movement.
If you lined up all the eyelashes shed during one human life, they would measure 98 feet long.
A scallop has around 100 eyes around the edge of its shell to detect predators.
You see things upside down - it is your brain which turns the image the right way up.
The space between your eyebrows is called the Glabella.
Contrary to urban myth, contact lenses cannot become ‘lost’ behind your eye due to the structure of your eyeball.
Goats have rectangular pupils to give them a wide field of vision.
Everyone has one eye that is slightly stronger than the other.
The eyeball weighs around 28 grams.
Although the function of tears is to keep eyes clean, scientists don’t understand why we cry when we are upset.
Owls are the only bird which can see the colour blue.
Your nose gets runny when you cry as the tears drain into your nasal passages.
About half of the human brain is dedicated to vision and seeing.
Most hamsters only blink one eye at a time.
The phrase ‘it’s all fun and games until someone loses an eye’ comes from Ancient Rome, as the only rule for their bloody wrestling matches was ‘no eye gouging’.
80% of our memories are determined by what we see.
Our eyes have small blind spots where the optic nerve passes through the retina, and our brains use the information from the other eye to fill this gap.
Camels have three eyelids! This is to protect their eyes from sand blowing in the desert.
You should always wear sunglasses and a hat in bright light to protect your eyes from UV rays.
While a fingerprint has 40 unique characteristics, an iris has 256. This is why retina scans are increasingly being used for security purposes.
Red-eye in photos is caused by light from the flash bouncing off the capillaries in people’s eyes.
In an average life, your eyes will see 24 million different images.
It is reported that men can read fine print better than women can.
Scorpions can have as many as 12 eyes.
...and the box jellyfish has 24!
Just behind our pupil is the lens - which is round, flat and thicker toward the middle.
Albinism affects melanin production, perhaps resulting in extra sensitivity to light and a red-eyed appearance.
The cornea is the transparent covering of the iris and pupil.
Guinea pigs are born with their eyes open!
Astigmatism refers to a curvature of the cornea or lens and toric lenses are prescribed to aid the individual’s vision.
A worm has no eyes at all.
An owl can see a moving mouse more than 150 feet away.
Research has found that a tie tied too tightly can increase the risk of glaucoma in men.
The perfect length of eye contact when you first meet someone is to acknowledge what colour eyes they have – about 4 seconds.