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

>I know that squinting helps you see better because you flex your cornea which helps bend the light to get a better focal point.

This isn’t accurate. Squinting helps you focus because it reduces the size of the hole light has to get through to reach your retina. The same way a camera obscura works, or why reducing the aperture of a camera increases the depth of field.

This is also one reason you can focus better in bright light, your pupil is smaller.