Glasses
Question: Why do I have to wear glasses? How do they help me see better?
Answer:
There are a lot of things our eyes have to do perfectly for us to have perfect sight.
If just one of those things is not quite right, we need glasses. But the glasses have to be made just for you and your unique eyes.
Eyeglasses work by bending light beams so that they meet right at the back of our eyeballs on the retina (RET-in-ah). The retina
changes light into signals that go to the brain.
A Look Inside Your Looker
Our eyeballs work a lot like little cameras. There is a lens that focuses the light. Light has to focus exactly at the retina for our sight to be clear.
The first thing that can go wrong is the length of the eyeball. It can be too short or too long. Or the cornea can have the wrong shape. The lenses in our eyeglasses help the lenses in our eyes. They make sure the light focuses right at the retina so we can see clearly.
When we look at faraway things, the lens is pulled flat by little muscles. In this drawing the blue arrows show you the direction the muscles are pulling. When we look at close-up things, the muscles pull in and the lens gets fat and round. The idea is to keep everything in focus.
Different Glasses Fix Different Problems
WHAT YOU NEED:
A few friends who wear glasses (perhaps your classmates at school).
WHAT TO DO:
Hold a pair of glasses out at the end of your arm. Look at the view. Look at the lenses, too. Look at several different pairs.
Be very careful not to hurt the glasses. People who wear glasses need them to see well. Respect that.
If you wear glasses, keep yours on when it's your turn.
Glasses for Nearsighted People
These lenses will make the view look smaller.
When people are nearsighted they can see near.
They cannot see clearly when things are far away. Their eyeballs may be too long.
Glasses for Farsighted People
These lenses will make the view look bigger or even upside down.
When people are farsighted they can see far.
They cannot see things clearly that are close up. One cause of it is eyeballs that are too short.
Glasses for People with Astigmatism
These will change the shape of the view, stretching it out and maybe twisting it.
People with astigmatism (ah-STIG-ma-tis-m) have a cornea that is out of shape.
The weird stretched-out lens fixes it.
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Copyright © 1999 - 2004 Jok R. Church - All Rights Reserved.