<prompt> Shoening of 2 mm of axial length of eye ball causes-3D myopia6D myopia3D hypermetropia6D hypermetropia  <response>: 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 