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Close up of eye iris

101 amazing eye facts

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?

If you like eye facts, check out our 7 Amazing Facts About Your Eye Infographic! Here are 101 fun facts that you may not know about eyes.

  1. Eyes are thought to have first developed in animals, in a very basic form, around 550 million years ago. Tweet this.
  2. The world’s most common eye colour is brown. Tweet this. 
  3. Your eye is the fastest muscle in your body – hence why when something happens quickly, we say ‘in the blink of an eye!’ Tweet this. 
  4. You see with your brain, not your eyes. Our eyes function like a camera, capturing light and sending data back to the brain. Tweet this. 
  5. Dogs can’t distinguish between red and green. Tweet this. 
  6. 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. Tweet this. 
  7. Eye colour is determined by the amount of melanin in your iris. Tweet this. 
  8. 20/20 vision simply means that you have normal vision. Tweet this. 
  9. Your eyes become tired when you read or stare at a computer, this is because you blink less often. Tweet this. 
  10. Although our nose and ears keep growing throughout our lives, our eyes remain the same size from birth. Tweet this.
  11. You blink more when you talk. Tweet this.
  12. Diabetes is the number one cause of blindness in adults in the UK. Tweet this.
  13. People generally read 25% slower on screen than on paper. Tweet this.
  14. All babies are colour blind at birth. Tweet this.
  15. The first blue-eyed person is said to have lived 6,000-10,000 years ago. Tweet this.
  16. It’s impossible to sneeze with your eyes open. Tweet this.
  17. An ostrich’s eye is bigger than its brain. Tweet this.
  18. The human eye can see 500 shades of grey. Tweet this.
  19. You blink on average 4,200,000 times a year. Tweet this.
  20. The cornea is the only tissue in the human body which doesn’t contain blood vessels. Tweet this.
  21. The human eye can function at 100% at any given moment, without needing to rest. Tweet this.
  22. Smoking reduces your night vision. Tweet this.
  23. Eyelashes have an average lifespan of five months. Tweet this.
  24. A newborn baby will cry, but not produce any tears. Babies do not produce tears until they are around six weeks old. Tweet this.
  25. Our eyes are made up of over 2 million working parts. Tweet this.
  26. In the right conditions and lighting, humans can see the light of a candle from 14 miles away. Tweet this.
  27. The shark cornea is used in human eye surgery as it is the most similar to the human cornea. Tweet this.
  28. 80% of vision impairment worldwide is curable. Tweet this.
  29. The human eye only sees three colours, red, blue and green. All other colours are combination of these. Tweet this.
  30. A camel’s eyelashes can measure up to 10cm long, to protect its eyelashes from blowing sand and debris in the desert. Tweet this.
  31. One of the most common cosmetic injuries is poking the eyeball with a mascara wand. Tweet this.
  32. The eye muscles are the most active muscles in the human body. Tweet this.
  33. The eyes of a chameleon are independent from each other, allowing it to look in two different directions at once. Tweet this.
  34. It’s possible to blink five times in a single second. Tweet this.
  35. Your eyes contain around 107 million light sensitive cells. Tweet this. 
  36. 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. Tweet this.
  37. Geckos can see colours around 350 times better than a human, even in dim lighting. Tweet this.
  38. A blink typically lasts 100-150 milliseconds. Tweet this.
  39. Blue-eyed people share a common ancestor with every other blue-eyed person in the world. Tweet this. 
  40. Our eyes close automatically to protect us from perceived dangers. Tweet this. 
  41. Your eyelashes keep dirt out of your eyes. Tweet this. 
  42. The largest eye on the planet belongs to the Colossal Squid, and measures around 27cm across. Tweet this.
  43. Your eyebrows prevent sweat dripping into your eyes. Tweet this.
  44. Heterochromia refers to a condition where your eyes are two different colours. Tweet this.
  45. Our eyes are positioned in a hollowed eye socket, to protect the eye. Tweet this.
  46. Dolphins sleep with one eye open. Tweet this.
  47. Bees have 5 eyes. Tweet this
  48. Eyes are the second most complex organ after the brain. Tweet this.
  49. The Mayans believe that cross-eyes are attractive and would make efforts to ensure their children became cross-eyed. Tweet this.
  50. A dragonfly has 30,000 lenses in its eyes, assisting them with motion detection and making them very difficult for predators to kill. Tweet this. 
  51. We have all have unseen, and harmless, microscopic creatures living in our eyelashes. Tweet this. 
  52. The muscles in the eye are 100 times stronger than they need to be to perform their function. Tweet this. 
  53. When your eyes are watering it may be a sign of dry-eye, and your eyes are producing more moisture to compensate. Tweet this. 
  54. Your eyes start to develop just two weeks after conception. Tweet this. 
  55. Owls cannot move their eyeballs – which has led to the distinctive way they turn their heads almost all the way around. Tweet this. 
  56. The older we get, the less tears we produce. Tweet this.
  57. Eyes are able to process 36,000 pieces of information in a single hour. Tweet this.
  58. Colour blindness is more common in males. Tweet this.
  59. Reading in dim lighting does not damage your eyes but it may tire them out. Tweet this.
  60. Sitting too close to a TV won’t give you square eyes. Tweet this.
  61. The four-eyed fish can see both above and below water at the same time. Tweet this.
  62. Oily fish, vitamin A and vitamin C all help to preserve good eyesight. Tweet this.
  63. 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. Tweet this.
  64. Snakes have no eyelids, just a thin membrane covering the eye. Tweet this.
  65. Eye transplants are currently impossible due to the sensitivity of the optic nerve. Tweet this.
  66. Only one sixth of the human eyeball is exposed. Tweet this.
  67. Pirates believed that wearing gold earrings improved their eyesight. Tweet this.
  68. Snakes have two sets of eyes – one set used to see, and the other to detect heat and movement. Tweet this.
  69. If you lined up all the eyelashes shed during one human life, they would measure 98 feet long. Tweet this.
  70. A scallop has around 100 eyes around the edge of its shell to detect predators. Tweet this.
  71. You see things upside down - it is your brain which turns the image the right way up. Tweet this.
  72. The space between your eyebrows is called the Glabella. Tweet this.
  73. Contrary to urban myth, contact lenses cannot become ‘lost’ behind your eye due to the structure of your eyeball. Tweet this.
  74. Goats have rectangular pupils to give them a wide field of vision. Tweet this.
  75. Everyone has one eye that is slightly stronger than the other. Tweet this.
  76. The eyeball weighs around 28 grams. Tweet this.
  77. Although the function of tears is to keep eyes clean, scientists don’t understand why we cry when we are upset. Tweet this.
  78. Owls are the only bird which can see the colour blue. Tweet this.
  79. Your nose gets runny when you cry as the tears drain into your nasal passages. Tweet this.
  80. About half of the human brain is dedicated to vision and seeing. Tweet this.
  81. Most hamsters only blink one eye at a time. Tweet this.
  82. 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’. Tweet this.
  83. 80% of our memories are determined by what we see. Tweet this.
  84. 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. Tweet this.
  85. Camels have three eyelids! This is to protect their eyes from sand blowing in the desert. Tweet this.
  86. You should always wear sunglasses and a hat in bright light to protect your eyes from UV rays. Tweet this.
  87. While a fingerprint has 40 unique characteristics, an iris has 256. This is why retina scans are increasingly being used for security purposes. Tweet this. 
  88. Red-eye in photos is caused by light from the flash bouncing off the capillaries in people’s eyes. Tweet this. 
  89. In an average life, your eyes will see 24 million different images. Tweet this. 
  90. It is reported that men can read fine print better than women can. Tweet this. 
  91. Scorpions can have as many as 12 eyes. Tweet this. 
  92. ...and the box jellyfish has 24! Tweet this. 
  93. Just behind our pupil is the lens - which is round, flat and thicker toward the middle. Tweet this. 
  94. Albinism affects melanin production, perhaps resulting in extra sensitivity to light and a red-eyed appearance. Tweet this. 
  95. The cornea is the transparent covering of the iris and pupil. Tweet this. 
  96. Guinea pigs are born with their eyes open! Tweet this. 
  97. Astigmatism refers to a curvature of the cornea or lens and toric lenses are prescribed to aid the individual’s vision. Tweet this. 
  98. A worm has no eyes at all. Tweet this. 
  99. An owl can see a moving mouse more than 150 feet away. Tweet this. 
  100. Research has found that a tie tied too tightly can increase the risk of glaucoma in men. Tweet this. 
  101. The perfect length of eye contact when you first meet someone is to acknowledge what colour eyes they have – about 4 seconds. Tweet this. 

Like these eye facts? Check out our 7 amazing facts about your eyes infographic!