An aspheric IOL for use in an ocular system has no inherent spherical aberration. An aspheric IOL for use in an ocular system has a controlled amount of inherent negative spherical aberration such that the IOL induces no spherical aberration in a converging wavefront. The amount of negative spherical aberration is less than an amount necessary to counter balance the positive spherical aberration of the cornea. A family of aspheric IOLs made up of any two or more individual aspheric IOLs having different spherical aberration values and different lens shape factors. A lens constant, such as the A-constant, is kept constant throughout the family of lenses. In an aspect, the A-constant of a child-family of aspheric IOLs matches the A-constant of a parent-family of spherical IOLs. A method for designing a family of aspheric IOLs.
