In long-sightedness or hypermetropia, the eye can form the image of distant objects on the retina but the image of closer objects is formed behind the retina.

For the correction of this defect, convex lens spectacles or contact lenses of suitable focal length are used. The lenses converge the light rays passing from closer objects which are again converged by the lens on the retina.

In this way, convex lens are used to correct long-sightedness.