University of Edinburgh

BSL Physics Glossary - short sight - definition

A short-sighted person can see a book clearly to read, but distant objects look blurred. The reason is that the eye lens is too thick. The parallel rays of light will enter the lens and refract strongly and the focus will in the middle of the eye, not on the retina at the back. So the image at the retina is blurred. To correct short sight, the person has a diverging lens in their glasses. This means that the light is focused further back in the eye, on the retina. That's the perfect place for a clear image.

short sight

Short sight: the point of focus is in front of the retina.