Focus errors and glasses

Long-sighted
Short-sighted
Astigmatism
Diagrams showing focus error

Lots of us get confused about the names “short-sighted” and “longsighted”. These diagrams try to show how light is brought to a focal point by your eye.

The lens in the eye, which sits just behind the pupil, is able to adjust it’s curve to move the point of focus of your eye. A longsighted eye can be made clear by the lens focusing, increasing the focus power of the eye. A shortsighted eye can’t have its power reversed – things far away will always be blurred when no glasses are worn. But that person can read without glasses.