■ A convex lens is used for farsightedness. ■
 
 

In a case of farsightedness, the light which comes by covering a convex lens from a triangle is refracted inside.  By it, a triangular image will connect an image to the front retina.

角膜から網膜までの距離が短い場合:In the case the distance from cornea (black part of the eye) to retina is short.