Convex lens

A convex lens, which is thicker in the middle, corrects long-sightedness. It begins to converge the light before it enters the eye. The combined effect of the corrective lens and the eye's own lens brings the focus forwards, exactly onto the retina.

A convex lens, which is thicker in the middle, starts bringing the rays together before they enter the eye. The eye can then focus them sooner, on the retina. Glasses and contact lenses can provide either type of corrective lens.