Young boy looking through a concave lens. The shape of a concave lens makes things look smaller. The lens is thicker on the outside than it is in the middle and because the image is wider, things appear smaller and further away. Rays of light refract through the lens and are spread out. Concave lenses are used to correct short sightedness (myopia). They are also components in complex photographic camera lenses, telescopes and binoculars.