The effect of spherical aberration of contact lens to the wearer.

To determine the influence of the spherical aberration of a contact lens on the total spherical aberration of the eye-contact lens system, appropriate formulas are derived. By comparing the total spherical aberration of the eye without a contact lens with that found when a contact lens is in place, it is shown that the spherical aberration of the eye is determined, almost entirely, by the first refracting surface (either cornea or contact lens). The amount of aberration when converted to a dioptric value shows the relative effects clearly.