Your eyes and your brain work together to see. The eye is made upof many different parts, including the cornea, iris, lens, and retina.These parts all work together to focus on light and images. Youreyes then use special nerves to send what you see to your brain, soyour brain can process and recognize what you're seeing. In eyesthat work correctly, this process happens almost instantly.

When this doesn't work the way it should, a person may be visuallyimpaired, or blind. The problem may affect one eye or both eyes.

When you think of being blind, you might imagine total darkness.But most people who are blind can still see a little light or shadows.They just can't see things clearly. People who have some sight, butstill need a lot of help, are sometimes called "legally blind."

A baby who is blind can still learn and develop normally. But the baby's parents will need the help of specialists who know how to help blind children. It's often a great idea for the child to attend special learning programs designed just for little kids who have trouble seeing. These programs would make the most of the senses that the kid does have, such as touch, hearing, smell, and taste.

Touch comes in handy when a child is older and wants to read books. Kids who are visually impaired can learn to read by using a special system called braille. Braille is a way of expressing letters, words, and thoughts. To read braille, a person feels a series of little bumps that are associated with letters in the alphabet. For instance, "A" is represented as one bump. Computer programs and other devices that can "see" turn the words on a page into braille.

Hearing is another important sense if a kid has vision problems. Some devices can read out loud what's written on a page. With special equipment, a visually impaired kid can read almost anything. These kinds of technologies can be helpful in learning. Kids who are blind might attend a special school, or they might attend regular classes, aided by special devices and specialists.

Similar to the eyes of other mammals, the human eye's non-image-forming photosensitive ganglion cells in the retina receive light signals which affect adjustment of the size of the pupil, regulation and suppression of the hormone melatonin and entrainment of the body clock.[3]

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Home  >  Your brain  >  What are your senses?  >  How do you see?  >  How do your eyes work?

When you look at an object, the light from it enters your eye through the pupil. The iris changes the size of the pupil, depending on how bright the light is. The lens focuses the light onto the back of the eye: the retina. The retina is a mass of light-sensitive neurons, called photoreceptors, which change light signals into electrical ones.

Your eye is only the starting point of how you see.

How do photoreceptors work?

Photoreceptors contain chemicals that change when they are hit by light. This causes an electrical signal, which is then sent to the brain along the optic nerve. Different types of photoreceptor allow us to see an enormous range of light: from starlight to full sunshine, and all the colours of the rainbow.Back to top

Photoreceptors in the eye.

What is colour blindness?

The most common form of 'colour blindness' is red-green colour deficiency, which affects 7-10% of people. This is not actually blindness, but a difficulty in distinguishing shades between red and green. It is caused by a change to or loss of the light responsive chemical in certain photoreceptors. Total absence of colour vision, where everything is seen in shades of black and grey, is very rare, and is usually caused by brain damage.

An Ishihara colour-blindness test.

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Incidentally, this could also result in blurry or double vision, which sounds really fun, so don’t see a doctor if it persists.

Read more at http://www.stuff.tv/sg/features/5-ways-ruin-your-eyesight#ocAyjfhkSJfzbAQy.99

You could always wear inaccurately-prescribed glasses to ensure your myopia worsens and achieve thicker and cooler lenses.

Read more at http://www.stuff.tv/sg/features/5-ways-ruin-your-eyesight#ocAyjfhkSJfzbAQy.99

You could always wear inaccurately-prescribed glasses to ensure your myopia worsens and achieve thicker and cooler lenses.

Read more at http://www.stuff.tv/sg/features/5-ways-ruin-your-eyesight#ocAyjfhkSJfzbAQy.99

1. Eyes began to develop 550 million years ago. The simplest eyes were patches of photoreceptor protein in single-celled animals.

2. Your eyes start to develop two weeks after you are conceived.

3. The entire length of all the eyelashes shed by a human in their life is over 98 feet with each eye lash having a life span of about 5 months.

4. To protect our eyes they are positioned in a hollowed eye socket, while eyebrows prevent sweat dripping into your eyes and eyelashes keep dirt out of your eyes.

5. Your eyeballs stay the same size from birth to death, while your nose and ears continue to grow.

6. An eye is composed of more than 2 million working parts.

7. Only 1/6 of the human eyeball is exposed.

8. Corneas are the only tissues that don’t have blood.

9. The human eye weights approximately just under an ounce and is about an inch across.

10. An eye cannot be transplanted. More than 1 million nerve fibers connect each eye to the brain and currently we’re not able to reconstruct those connections.

11. 80% of our memories are determined by what we see.

12. Eyes heal quickly. With proper care, it takes only about 48 hours to repair a minor corneal scratch.

13. There are about 39 million people that are blind around the world.

14. 80% of vision problems worldwide are avoidable or even curable.

15. Humans and dogs are the only species known to seek visual cues from another individual’s eyes, and dogs only do this when interacting with humans.

16. A fingerprint has 40 unique characteristics, but an iris has 256, a reason retina scans are increasingly being used for security purposes.

17. People who are blind can see their dreams if they weren’t born blind.

18. “Red eye” occurs in photos because light from the flash bounces off the back of the eye. The choroid is located behind the retina and is rich in blood vessels, which make it appear red on film.

19. 80% of what we learn is through our eyes.

20. Eyes are the second most complex organ after the brain.