Shoening of 2 mm of axial length of eye ball causes-
Axial hypermetropia is by far the commonest form. In this condition the total refractive powerof eye is normal but there is an axial shoening of eyeball. About 1-mm shoening of the anteroposterior diameter of the eye results in 3 dioptres of hypermetropia. So shoening of eyeball about 2mm results in 6D hypermetropia Reference : A K KHURANA OPHTALMOLOGY,Edition 4, page-29
3D myopia
6D myopia
3D hypermetropia
6D hypermetropia
Optics and refraction