How do glasses work

You probably know someone how has to wear glasses or you even have to wear glasses yourself.
That is very much normal as around 60 percent of the worlds population has to wear glasses or contact-lenses. Most of the people having to wear glasses live on the Asian continent. There are many causes that can lead to you or someone else needing glasses but in most cases it is either because you are nearsighted or farsighted. But was does nearsighted / farsighted mean?:

Nearsighted means that you do see things that are close to you normally but everything further away seams to be blurry. As an example: for people with nearsightedness it is easy to read whats written in a book or on the phone, computer screen etc. but if the teacher writes something on the board or they have to read road signs its hard to see because it is blurry.

Farsighted on the other hand is the opposite. You can see everything that is far away but reading everything close by is quite hard. As example: For people with farsightedness reading a book is a struggle but seeing whats written on a board or a street sign is easy.

And there are many other causes that can lead to you having difficulty seeing clearly. Like astigmatism that can be corrected with glasses. But how do glasses help us see better?

In the back of your eye you have something called the retina. It is layer of cells whose job it is to react to the light. The reaction does then get sent to your brain whose work then is to put the reaction of the cells together to form a image. If you have a 20/20 vision the rays that come inside your eye will focus on that part of the retina where you then see a perfect image. The Job of the Pupil and the cornea is to shrink and focus the image so if they have an irregularity your vision will be blurry.

If you are nearsighted or farsighted the image does not focus on the right spot. In cases of nearsightedness it focuses before the retina and if you are farsighted it focuses behind the retina. If you have astigmatism your cornea is shaped irregularly so the light bends in different directions.

What glasses do is that they have curved frames that bend the light in the correct way so you get a perfect image. If you need glasses the optometrist has to do a lot of testing so they have an exact view of your eye and where the light needs to be bended.

There also are two different kinds of glasses convex(+) and Concave(-) if you look at your prescription you will either see an + or an – in front of the number of how much your glasses need to be curved. A minus stands for nearsightedness and a plus for farsightedness

Sources:

https://science.howstuffworks.com/innovation/everyday-innovations/lens.htm (01/11/22)

https://heffingtons.com/how-do-glasses-work/ (01/11/22)