Optical illusions occur when what the eyes see conflicts with what the brain expects.
75
The human eye blinks an average of 4,200,000 times a year.
233
Only about 2% of the world population has green eyes.
36
Shark corneas are used in eye transplants and shark bone marrow can be used to graft human bones.
132
Sheep, goats, octopuses, and toads have rectangular pupils.
7
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
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