Why Do People Wear Glasses?
We’ve all experienced scenarios where someone broke their glasses: “I have another pair at home, we need to go back to get them! Okay, now we can go, I can see clearly now.” Why do some people need glasses and others don’t? To understand why some people wear glasses, we first need to know more about the eyes. So, on the front of the eye, we have two major parts which are the cornea and the lens. On the back of the eye there is another part called the retina.
The lens and the cornea work together so that the light rays from outside objects enter the eye and focus on the retina. The retina is the place where we have cells that can detect light, so happens if the light is not focused on the retina correctly? When light rays get focused in front of the retina, it causes myopia, which means that nearby objects are clear, but distant objects are out of focus and appear blurry. They are also called short-sighted. They may be able to read books very easily, but always need to sit in the front of the classroom in order to read the blackboard. If you’re experiencing this, it’s important to go to an optician to get your eyes tested.
Now, let’s see what happens when outside light is focused behind the retina. This is called hyperopia, which means that nearby objects are blurry, and distant objects are clear. This is also called being long-sighted. People who only need to wear glasses in order to read are long-sighted.
These problems occur because of the shape of the eyeball. If it is misshapen, it causes the light to focus at the wrong point. Some of us have shorter eyeballs and others have longer eyeballs. If your eyeballs are too elongated, light rays get focused in front of your retina you can see things up close but struggle with things in the distance. If your eyeball is too short, light rays get focused at the back of the retina and you can see things at a distance but struggle with close details.
Glasses help people to see things clearly. These corrective lenses help focus the light to the right place on your retina, so even if your eyeballs are shorter or longer, you can still see clearly. There are two main types of lenses: concave and convex. Concave and convex lenses have different shapes, and the curvature of the lens bends the light rays as they approach your eye. This helps the rays to focus on your retina instead of behind or in front of it. The lens you require if you are short-sighted is concave, that is, curving inward. Convex lenses are used to correct long-sightedness.
When someone visits an optometrist, they will have their vision measured and a prescription written for the exact shape of lens that will focus light correctly for their eyes. Another type of eye problem is called astigmatism. This is when the cornea is misshapen. This can also be corrected with specifically-shaped lenses.