Eyes questions

Mona Lisa is famous for an optical illusion aka 'the mysterious smile'. The illusion is caused due to peripheral vision as the focus of the viewer shifts from the eyes of the portrait to the lips of the portrait.

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.

Most newborn babies who have European ancestry lack pigments in the iris - so they have blue eyes. Over time, melanocytes slowly begin to produce melanin. Until the end of the first year of life, the child will have a permanent colour.

Louis Braille was a French educator and inventor of a system of reading and writing for use by the blind or visually impaired. His system remains virtually unchanged to this day, and is known worldwide simply as braille. Blinded in both eyes as a result of an early childhood accident, Braille mastered his disability while still a boy.

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.

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.

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.

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

Dilated pupils typically occur as an effect of taking stimulant drugs such as cocaine and amphetamine, while opiates such as heroin, morphine and codeine constrict the pupils.