Glasses and contacts help you to see better they don't make your sight better. As a matter of fact they make your sight worse. Why do you think you have to increase your prescription every few years?
Wearing glasses or contacts makes your eyes lazy and they become weak because you're not using the muscles in your eyes. There's a whole thing about how the muscles in your eyes work and how they constantly change the shape of the eyes to focus in on things, yada yada yada. But you didn't come here for all that.