Optical illusions occur when what the eyes see conflicts with what the brain expects.
75
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.
21
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
In ancient Egypt, priests plucked EVERY hair from their bodies, including their eyebrows and eyelashes.
130
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.
21
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.
22
Tigers can see 6 times better at night than humans.
305