Safe Tv Viewing distance calculator
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Your eyes are like a wonderful kind of camera.
They take pictures of the world around you and send the pictures to your brain. Your brain works out what your eyes are seeing. This happens from the moment that you open your eyes in the morning to when you close your eyes at night.
How a camera works
The light rays from an object pass through the lens of the camera and get recorded on a film or a computer chip.
Do you notice something about this drawing? Yes, the picture that is recorded by the camera is upside down (of course, when you look at the picture as a printed photo or on a computer screen, it is not upside down.)
How your eyes work
Your eye works in a similar way to a camera - light passes through the lens of your eye and is 'recorded' on the back of your eye (the retina).
Do you notice something about this drawing? Yes, the picture that your eye takes is upside down too!
Why don't you see things upside down?
Well, your eye sends the picture to your brain, and your brain turns the picture the right way up and tells you what you are looking at. So you see things the right way up.
Inside your eye
What are the parts of your eye and what do they do?
Cornea (Cor-nee-a)
This is the see-through skin that covers the front of your eye. It is clear like glass and it has no blood vessels in it.
Sclera (Sk-ler-a)
This is the tough skin which covers the outside of the eyeball (except for the see-through cornea). We call it the 'white' of the eye.
Iris (eye-ris)
The iris controls the amount of light that enters the eye. The iris is the coloured part of your eye.
Pupil (pew-pil)
This is the hole in the coloured iris. It lets light into your eye. It gets very small in bright light, and bigger in dull light.
The lens
The lens focuses light onto the retina. It changes shape to make sure that the 'picture' on the retina is as clear as possible.
Retina (Ret-in-a)
This is like a movie screen which shows the picture you are seeing - upside down, remember? The retina has two lots of cells called 'rods' and 'cones' (because that is what they look like.) Rods can 'see' black and white. Cones can 'see' colours. They turn the picture into an electrical message for the brain. Sometimes people don't see all the colours - look at our topic 'Colour blindness' to find out more.
Blind spot
This is a bit of your retina which is not sensitive to light because there are no rods or cones there. It is the spot where the optic nerve is joined on to the retina.
Optic nerve (op-tic)
The electrical messages from the retina travel along the optic nerve to your brain. It's a bit like the cable that carries all the TV pictures from your aerial to your TV so that you can see the programs. The great thing is that our eyes take these 'movies' all the time and we don't need any film or camera.
Eyelids and Eyelashes
These protect your eyes. The eyelids can shut out light so that you can sleep. They will shut very fast if they feel something that is trying to get into your eye.
Eyelashes
Eyelashes are very sensitive, and if they feel dust coming they trap it as your eyelids close.
Eyebrows
Eyebrows also help to keep dust and sweat out of your eyes.
Tear glands
These are small glands inside your upper eye lid. Their job is to make tears to keep the surface of your eyeball clean and moist, and help protect your eye from damage.
When you blink, your eyelids spread the tears over the surface of the eye. Small things that are on your eye (like specks of dust) wash into the corner of your eye next to your nose. Sometimes tears flow over your lower eyelid (when you cry, or you have hay fever), but mostly the tears flow down a tiny tube at the edge of your lower eyelid, next to your nose. (If you look very carefully you can see a tiny dot that is the beginning of that tube). This tube carries the tears to the back of your nose (and this is why your nose 'runs' when you cry!)
Conjunctiva (con-junk-ty-va)
This is the lining on the inside of your eyelid and the outside of the front of your eye (except for the special skin of the cornea). You can see some tiny blood vessels on the conjunctiva over your eye. If your eyes get sore, these blood vessels get bigger and your eye looks red.
There are two lots of fluid in the eye.
Aqueous humour (ak-we-us)
Aqueous means water, and humour means fluid. This watery stuff fills the front of the eyeball around the lens.
Vitreous humour (vit-re-us)
This is a thicker jelly-like liquid which fills the larger part of the eyeball and keeps it in shape. (Vitreous means glassy, because the vitreous humour is very clear, so that light can pass through it).
Protecting your eyes
Some ways to look after your eyes
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Take care to protect your eyes when you are playing, especially in sports, eg. wear goggles for snow skiing, helmets and guards for cricket and baseball.
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Turn on lights when it's getting dark (especially if you're reading).
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Wear sunglasses and hats on bright days.
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Tell your parent if your eyes are sore.
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Tell your teacher if you can't see the blackboard/whiteboard or your book clearly.
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|  Tell your teacher if the text is not clear. |
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Keep sunscreen away from your eyes - it really stings if it runs into your eyes.
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Wear glasses if you need them.
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Don't wear other people's glasses.
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Your eyes get sore if you watch a computer or TV screen for too long, so do lots of different things in your spare time (you need exercise, and so do your eyes).
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Looking directly at the sun (or any really bright light, including lightning) can damage your eyes.
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Rubbing your eye if you get something in it can hurt your eye, so ask an adult to help you.
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Use the correct drops/medication for your eyes if you need them, and do not use ones that someone else has used.
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Sunglasses and hats
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All children (and adults) should wear sunglasses if they are going to be in bright sun light (babies usually don't wear sunglasses - they might poke the sunglasses in their eyes!)
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Babies should be sheltered from the sun by a hat, shade umbrella or the shade of a tree or roof.
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It is important that everyone's eyes are protected from sun damage. Sunglasses should be up to Australian standards to protect eyes from the sun. There will be a sticker telling you this on the glasses. Wearing non-approved glasses could cause problems with your eyes.
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Hats that shade the eyes are important.
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Could you have a problem?
What if your eyes don't work properly or don't see as well as they should?
Lots of people have problems with their eyes. Sometimes you don't even know you have a problem at first because you don't know that everyone else can see things differently.
Some people who have problems with their eyes say "I can see what they are doing, but I can't see who is doing it". You can miss a lot of things if you can't see well.
| Here are some things that might tell you that you are not seeing as well as you could: | |
 | You can't see the board. |
| Writing looks blurry. |
| Your eyes hurt or feel tired. |
| Your eyes feel hot, or they sting or twitch. |
| You get headaches when you've been reading or writing for a while. |
| It's hard to copy from the board. |
| You can't tell the difference between some colours. |
| You keep losing your place when reading or copying. |
| You need your book close up to your eyes to be able to read it. |
| When you look up from your work everything looks blurred or misty. |
What to do
If you are worried or not sure if you have a problem with your eyes, tell your mum or your dad or a teacher.