The colossal squid has the largest eyes in the world.
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The focusing muscles of the eyes move around 100,000 times a day. To give your leg muscles the same workout, you would need to walk 80km (50 miles) every day.
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Only about 2% of the world population has green eyes.
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The human eye blinks an average of 4,200,000 times a year.
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Shark corneas are used in eye transplants and shark bone marrow can be used to graft human bones.
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Optical illusions occur when what the eyes see conflicts with what the brain expects.
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All humans have the ability to see ultraviolet light, but it is passively filtered out by the eye's lens. People who undergo surgery to remove the lens can detect ultraviolet light.
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There's a woman named Veronica Seider who had vision 20x better than average. She could identify people more than a mile (1.6km) away.
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