Why does squinting help you see better when you don’t have your glasses on, but doesn’t overcorrect when you do?

Question

From a previous ELI5, I know that squinting helps you see better because you flex your cornea which helps bend the light to get a better focal point, but shouldn’t squinting when you have your glasses on/contacts in cause an overcorrection as if you are wearing an overprescribed pair of glasses/contacts?

In: 42

Answer 1

It won’t make a difference, when you squint without correction, you are only allowing tiny amounts of light which are travelling almost perpendicular to the lens of your eye so correction isn’t needed . When you are wearing glasses it is already corrected and when you do squint the you will allow the same amount of rays to pass through but they are already perpendicular which means they don’t need to be corrected because perpendicular rays to the lens don’t change direction.