Mystery #3Tier 2physics / light

Why do some people need glasses?

For some people the far-off world is a blur until they pop on their glasses, and suddenly everything snaps sharp. For others it's the close-up page that won't focus. The glasses are just curved bits of clear plastic. So what are they actually fixing?

A cheerful child wearing glasses and smiling, lenses that bend light so the picture lands sharply on the retina. — Photo: Kimberly Vardeman, Wikimedia Commons · CC BY 2.0 · via Wikimedia Commons

Your guess

What's your hunch about what goes a little wrong in the eye, and how a lens in front of it could help?

There's no single magic word to type, have a go in your own words, then reveal the answer to see how close you got.

Make a guess to unlock the hints and the answer.