40 incredible facts about your eyes that you never imagined were true

We think nothing of tiring our eyes out everyday by staring intently at the computer screen from morning to night. We forget that our eyes are an extremely delicate, and totally unique, organ, which scientists have yet to fully understand the complexity of.

Take a look at some of these incredible facts about the eye — and don’t forget to let yours rest once in a while!

• The pupil of your eye expands as much as 45% when you look at someone you love.
• Human corneas are so similar to shark corneas that they have been used as a replacement in human eye surgery.
• Each eye contains 107 million cells, and all of them are light sensitive.
• One in every 12 males is colour blind.
• The human eye only sees three colours: red, blue and green. All other colours are combinations of these.
• Your eyes are about 2.5 cm across and weight about 8 grammes.
• Only one sixth of the human eyeball is exposed.
• In an average lifetime, eyes see 24 million different images.
• While a fingerprint has 40 unique characteristics, an iris has 256. This is why retina scans are increasingly being used for security purposes.
• People say ’in the blink of an eye’ because it’s the fastest muscle in the body. A blink usually lasts 100 to 150 milliseconds, and it’s possible to blink five times in a second.
• The eyes on average blink 17 times per minute, 14,280 times per day, and 5.2 million times per year.
• Eyes can process about 36,000 bits of information each hour.
• Brown eyes are actually blue underneath the brown pigment, and as a result there exists a laser procedure to turn brown eyes blue permanently.
• Your eye will focus on about 50 things per second.
• The images which our eyes send to our brains are actually sent backwards and upside down.
• Out of all the muscles in your body, the muscles that control your eyes are the most active.
• Each eyelash has a lifespan of approximately 5 months.
• The Mayans believed that cross-eyes were attractive, and would make efforts to ensure their children became cross-eyed.
• Ten thousand years ago, everyone’s eyes were brown until someone developed a genetic mutation that made their eyes blue. This means that if your eyes are blue, you share a common ancestor with every blue-eyed individual in the world!
• If in a flash photograph you have only one eye that shows up red, it is likely that you have eye cancer (if you are looking directly into the lens). Fortunately, in 95% of cases it’s possible to survive.
• A diagnosis of schizophrenia can be made with 98.3% accuracy by doing a simple eye test.
• Humans and dogs are the only species known to see visual cues from another individual’s eyes, and dogs only do this when interacting with humans.
• About 2% of women have a rare genetic mutation that provides them with an extra retinal cone in their eyes. This allows them to see 100 million colours!
• The human eye can only make smooth motions if it’s actually tracking a moving object.
• Pirates used eye patches to quickly adjust their eyes from above to below deck, having one eye trained for the bright light and the other for dim light, respectively.
• There are colours that are too complex for the human eye to perceive, called ’Impossible colours’.
• All babies are colour blind when they are born.
• Eyes began to develop 550 million years ago. The simplest eyes were patches of photoreceptor protein in single-celled animals.
• While it takes some time for most parts of your body to warm up to their full potential, your eyes are always active, 24/7.
• Eyes heal quickly. With proper care, it only takes about 48 hours for the eye to repair a corneal scratch.
• The eye’s lens is quicker than any camera’s.
• You see with your brain, not with your eyes. In many cases, blurry or poor vision isn’t caused by the eye at all. It stems from something going wrong in the visual cortex of the brain.
• Your eyes started to develop only two weeks after you were conceived.
• Blind people, as long as they weren’t born blind, can see their dreams.
• Eyes use about 65% of your brainpower, more than any other part of the body.