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Sunday 11 January 2015

Eye

THE HUMAN EYE

The only part of the human body that has no blood supply is the cornea in the eye. It takes in oxygen directly from the air and that's why corneal transplant is one of most successful surgeries - no rejection from the body.

Only 2% of people on this planet have green eyes.


8% of the world’s population have blue eyes.

The majority of Caucasian newborns have blue eyes, but by adulthood, only one in five do so.

All blue-eyed people are mutants sharing a single, common ancestor. A mutation occurred between 6,000 and 10,000 years ago, up until which we all had brown eyes.


About half of Americans born at the turn of the 20th century had blue eyes. Today, only about one of every six Americans has them.

There is no blue pigmentation in blue eyes. They are instead blue for the same reason that water and the sky are blue: they scatter light so that only blue light reflects out.

Brown colored eyes are really blue, under a layer of melanin. As a result you can actually get surgery to turn brown eyes blue.


1% of people suffer from 'Heterochromia Iridum', A condition where one of your eyes is brown and the other is blue.

There are about 600 people worldwide with purple eyes.

Although most babies are born with blue eyes, a pigment in the iris matures over the first two years of their life, usually leaving them a different color.

Humans are the only primates with a very distinct and visible colored iris and black pupil in contrast with the rest of the eye (sclera) which is white. This is due to a lack of pigment in the sclera. Other primates have pigmented sclera that are brown or dark in color.

Our eyeballs are always the same size from birth, but our nose and ears never stop growing.

The pupil was referred to as “the apple of one’s eye” as it was originally thought to be a solid, spherical part of the eyeball.

The pupil in your eye expands up to 45% when looking at something pleasing.


Our eyes contain over four million cone cells that let us see up to one million different simultaneous visual impressions.

The human eye has a resolution of approximately 576 megapixels. For context a 4K screen has about 8.8 megapixels.

Our eyes see everything upside down, but our brain automatically makes us to see the right side up. This marvel is called Optical Inversion.

The human eye is so sensitive that, if the Earth were flat, you could spot a candle in the dark from 20 miles away.

The focusing muscles in your eyes move around 100,000 times per day.

The extra layer of skin over the eye of 90% Asiatic people is called the "epicanthic fold" and is theorized to have evolved as a protection against cold and snow blindness.

The Moken are a nomadic, Southeast Asian people that number between 1,000 and 3,000. The most unique thing about these people, though, is that they have learned to control their pupil dilation in low light and see clearly underwater.

EYES IN THE ANIMAL KINGDOM

The Giant Atlantic Squid have the largest eyes in the animal kingdom.  In 2008 one colossal squid eye was measured at 11 inches across.

The Philippine tarsier (see below) has the largest eye-to-body size ratio of all mammals. Its huge eyes provide excellent vision, especially during nights.

By mtoz - originally posted to Flickr as Tarsier, Wikipedia Commons

An ostrich's eye measures almost 5 cm across and is the largest of any land animal.

An owl’s eyes are bigger than its brain.


When reflected from bright lights (head lights) deer’s eyes are orange, whereas cats and dogs are green. Rabbit’s eyes remain black.

Honeybees have hair on their eyes.

If a goldfish's eyes are damaged it can regrow them.

Snakes are unable to close their eyes – they can't blink and they must sleep with their eyes open.

Shark eyes are so similar to ours that they've been used in human corneal transplants.

Some animals like frogs and lizards have a third eye, a very small grey oval between their two regular eyes, which functions as a photoreceptor connected directly to the pineal gland to tell their brain when it is day or night while the regular eyes are closed.

FUN EYE FACTS

Sammy Davis Jnr lost his left eye in a car crash when he was his way to record the theme song for the 1955 Tony Curtis film, Six Bridges to Cross . He wore an eyepatch for sometime after that, but Humphrey Bogart ultimately convinced him to unmask when he told him that he didn't want to be known as the kid with the eyepatch.

Comic actor Dan Aykroyd was born with heterochromia, meaning his eyes are different colors — his right eye is blue, his left brown

Theodore Maiman operated the first optical laser, at Hughes Research Laboratories in Malibu, California in 1960.

The phrase an eye for an eye referring to the principle that a person who has injured another is to be penalized to a similar level is biblical. It originates in the Old Testament book of Exodus "Eye for an eye, tooth for tooth, hand for hand, foot for foot."

Lisa "Left Eye" Lopes of TLC got her nickname from a man who told her that he was very attracted to her because of her left eye.

Optophobia is the fear of opening one's eyes.

Only about 35 percent of all adults have 20/20 vision without glasses, contact lenses or corrective surgery.

Here is a list of songs about eyes.

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