Kids . . . How do your eyes work? Let’s take a look!
Think of the eye as a camera. The front part of the eye has the magnification and the back part has the film.
Your eye works very much like a camera. Light enters the eye, first passing through the outer clear layer of the eye, called the cornea.
Through the cornea, the light next passes through the pupil that is a passage way to the back of the eye. The pupil gets bigger to allow more light in (when there’s very little light) and smaller to allow less light in (when there’s a lot of light).
How does the pupil know to get bigger or smaller? That’s the job of the iris. The iris is the colored part of your eye, and it controls the pupil’s size.
Once the light passes through the iris, it next hits the lens. The lens puts the light rays into focus and sends it to the retina. But before it hits the retina, it has to pass through the vitreous humor—a colorless mass of jelly-like material behind the lens. The light passes through this material, traveling to the retina.
The retina is the innermost layer of the eye. Think of the eye as a camera. The retina, then, is the film in the camera which captures the image. The funny thing is that the image on the retina appears upside-down, backwards, and 2-dimensional. But when we think about how we see things, they’re always right-side-up and 3-dimensional. Something else has to happen before this journey is over…this light-information has to be sent to the brain.
The retina contains light-sensitive cells called rods and cones. These cells connect to the brain through a very important nerve at the back of the eye called the optic nerve.
The optic nerve
This nerve is the brain’s messenger, sending the image to a place in the back of the brain called the occipital lobe. It’s at this point that the brain is able to switch that backwards, upside down, 2-dimensional image into its correct form.
How is your brain able to turn a 2-dimensional image into a 3-dimensional image? You need to remember that you have two eyes, each carrying this light information to the brain from 2 slightly different angles (your eyes are several inches apart, and that gives each eye a slightly different view on the world). When the brain receives both of these 2-dimensional images, it combines them together into one 3-dimensional image, allowing you to see the world in 3D!
Crying — what makes tears?
Your eyes have their own special bathing system to wash away things that can hurt or irritate your eyes. Above the outer corner of each eye are the lacrimal glands, which make tears. Every time you blink your eye, a tiny bit of tear fluid comes out of your upper eyelid. It helps wash away germs, dust, or other particles that don’t belong in your eye. It also keeps your eye from drying out. Then the fluid drains out of your eye by going into the lacrimal duct (this is also called the tear duct).
You can see the opening of your tear duct if you very gently pull down the inside corner of your eye. When you see a tiny little hole, you’ve found the tear duct. Sometimes your eyes will make more tear fluid than normal to protect themselves. This may have happened to you if you’ve been poked in the eye, if you’ve been in a dusty or smoking area, or if you’ve been near someone who’s cutting onions. And how about the last time you felt sad, scared, or upset? Your eyes got a message from your brain to make you cry, and the lacrimal glands made many, many tears.
Protecting Your Eyes
Did you know that 9 out of 10 eye injuries can be prevented with proper care? Eye injuries usually happen at home and school and often during sports and hobby activities. Make sure you practice prevention!
How Are Your Eyes Protected?
- Your eyes lie in bony sockets that protect them from getting hit.
- Eyebrows help keep light from getting in your eyes.
- Eyelids close to keep things from getting in your eyes.
- Eyelashes grow along the outside of the eyelids; they also keep things from getting in your eyes.
Protecting the eyes of your friends and family
Injuries can easily happen so you have to really think what you are doing. Wouldn’t it be awful if someone’s eyes were hurt and it was your fault? Here are some ways to help make sure you don’t hurt anyone else’s eyes.
- Never throw sand, dirt or small things at others
- Never run with pointy things like pencils or scissors in your hands
- Never fire anything at others —Darts, a gun, peashooters, paper planes etc.
- Never spray insect repellant or use any other kind of spray without warning others.
- Can you think of other things that might hurt someone’s eyes?
How Can You Protect Your Eyes?
Because your eyes are so precious you really need to take special care of them.
- Take care to protect your eyes when you are playing, especially in sports e.g. wear goggles for snow skiing, helmets and guards for cricket and baseball.
- Turn on lights when it’s going dark (especially if you’re reading).
- Wear sunglasses and hats on bright days.
- Tell your parent if your eyes are sore.
- Tell your teacher if you can’t see the blackboard or your book clearly.
- Tell your teacher if the text is not clear.
- Keep sunscreen or face lotion away from your eyes; it really stings if it runs into your eyes.
- Wear glasses if you need them.
- Don’t wear other people’s glasses.
- Looking directly at the sun (or any really bright light including lightning) can damage your eyes.
- Rubbing your eye if you get something in it can hurt your eye so ask an adult to help you.
- Use correct drops/medication for your eyes if you need to and do not use ones that that someone else has used.
What to do if your eyes don’t work properly or don’t see as well as they should?
Lots of people have problems with their eyes. You can miss a lot of things if you can’t see well. Sometimes you don’t even know you have a problem at first because you don’t know that everyone else can see things differently.
If you are worried or not sure if you have a problem with your eyes, tell your mom or dad or a teacher. 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, 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 colors.
- 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.
First Aid Tips
- If something gets into your eye, such as sand or dust, do not rub your eye. Wash your eye with water to get the object out.
- If your eye gets hit by a ball or a fist, put cold cloths on your eye for 15 minutes. This will make the swelling go down and reduce pain. You should also go to the doctor.
- If an object, such as a stick or a pencil, gets stuck on your eye, do not pull it out. Put a loose bandage on your eye. This is very serious. You need to go to the doctor right away.
- If a chemical, such as cleaning fluid or battery acid, splashes in your eyes, wash out your eyes with water for at least 10 minutes. You need to go to the doctor right away.
The eyes you’ve got will be yours forever – treat them right and they’ll never be out of sight!
The word Optical means “related to the science of vision.” An illusion is something that tricks the senses.
Optical illusions teach us about how the eye and brain work together to create vision. In our everyday three-dimensional (3-D) world, our brain gets clues about depth, shading, lighting, and position to help us interpret what our eyes see. But when we look at two-dimensional (2-D) images that lack some of these clues, the brain can be fooled.