10 most difficult eyes riddles

The number on the bottom eyelid is significantly lower - about 50-150.

The Richat Structure in Mauritania, also known as the Eye of the Sahara, was interpreted as an asteroid impact structure, but no evidence of shock metamorphism has been found. Today, scientists believe that it is a huge (40 km in diameter) and deeply eroded geologic dome.

Owl's eye colour depends on the time of day in which they hunt. The ones that hunt during daylight have yellow eyes. The ones that hunt at night but also at the evenings and mornings have orange eyes. Black eyes are typical to owls that hunt only at night.

Emmetropia is the state of vision where a faraway object at infinity is in sharp focus with the eye lens in a neutral or relaxed state. Protanopia, Deuteranopia, Monochromacy - color blindness, also known as color vision deficiency, is the decreased ability to see color or differences in color.

The Scriptures tell us that Jesus didn’t look different from an ordinary Jewish man of His time. (No, they do not. Jesus was descended from the Galilean Mary.) Any other color of eyes than brown would have been surely noted down. In the 2004 movie, The Passion of the Christ, Jesus was portrayed by Jim Caviezel who had his blue eyes digitally changed to brown.

Man is usually sensitive to about 500,000 colors. Tetrachromacy is the condition of possessing four independent channels for conveying color information, or possessing four types of cone cells in the eye. Organisms with tetrachromacy are called tetrachromats which can see up to 99 million shades.

Many vertebrates, especially nocturnal ones, have the reflecting layer called the tapetum lucidum. It reflects the light back through the retina, increasing the amount of light available to the photoreceptors.

Giant squids have the largest eyes of any living creature except perhaps colossal squid – over 30 centimeters (1 ft) in diameter. Large eyes can better detect light (including bioluminescent light), which is scarce in deep water.

Wearing sunglasses without UV filter causes the pupils to dilate and eyes to absorb more UV rays than they normally would without the sunglasses. Hence, it's much better not to wear sunglasses at all, than to wear ones without UV filter.

Tarsiers are small animals with enormous eyes; each eyeball is approximately 16 millimetres (0.63 in) in diameter and is as large as, or in some cases larger than, its entire brain. The unique cranial anatomy of the tarsier results from the need to balance their large eyes and heavy head so they are able to wait silently for nutritious prey.