Question: How do glasses make our sight better

Stephen Moss answered on 14 Mar 2011:

When light enters the eye it passes through the lens, before hitting the light-sensitive cells at the back of the eye. The lens is just like a magnifying glass, in that it has two curved surfaces, and it focuses the light on the back of the eye. But the lens is even better than a magnifying glass because it changes shape depending on whether we’re looking at things near to us or far away. But in many people (like me), the ability of the lens to change shape decreases as we get older, which means the light doesn’t get properly focused and things start to look fuzzy.

Humans discovered centuries ago that a glass lens held in front of the eye can make that essential adjustment to the incoming light, so that things appear in focus again. The thickness and curve on the glass lens can be varied to meet our individual need. Put two of those lenses into a frame, make use of the nose and ears for support, and hey presto you have a pair of glasses.