How does the vision of people with glasses compare to that of people who don't need glasses?

It depends on how bad your myopia (nearsightedness) and/or astigmatism is. [For simplicity, we can ignore presbyopia for now.]

If your prescription is not at all that bad, vision with glasses is just a sharper version of what you see without them, usually with no optical side-effects. If you have a rather high degree prescription, your spectacle lenses may be quite thick. These can cause distortions, especially in side vision. They can also make the image you see either bigger or smaller than it would be with no need for glasses (or even compared to contact lenses). The 20/20 you may see is not necessarily the same 20/20 that the person with the low prescription will see.

_Written by J. Trevor Woodhams, M.D. - Chief of Surgery, Woodhams Eye Clinic