A: Farsightedness occurs when light rays entering the eye are refracted   behind the retina, rather than precisely on the retina, which is needed to produce clear vision. This refractive error can occur with a flat cornea or because the eye is too short. Farsightedness is not intuitive because the natural focusing system in the eye can compensate for uncorrected farsightedness. Farsightedness affects near vision initially but aging can cause this error to affect distance as well. This shift occurs because aging individuals lose flexibility and thus focusing power in their natural lens.