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.
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!
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.
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!
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.
Because your eyes are so precious you really need to take special care of them.
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:
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.