Purpose: To establish new contact lens (CL) design method to reduce corneal aberrations.

Method: The subjects were astigmatism eye with initial stage tendency of Stage 1 keratoconus and keratoconus eyes of Stage 1 and Stage 4 which were classified by the Amsler-Krumeich classification. We designed the anterior surface of HCL from two-dimensional ray tracing in the optimal position by using the corneal anterior and posterior shape data by OCT measurement under the condition that the optical path length is constant and the shape of the CL posterior surface and the anterior surface of the cornea are the same. And then we evaluated the aberrations and Modulation Transfer Function (MTF) before and after wearing the designed CL.

Result: In all subjects, the aberrations were improved after wearing the designed CL. In addition, as a result of calculating the estimated Visual Acuity (VA) from MTF, VA 1.0 or more was obtained in the astigmatism eye and Stage 1 keratoconus eye after wearing the designed CL under the condition that there are no aberrations in the crystalline lens. Also, even in the Stage 4 keratocouns eye, which has a large change in the corneal shape, although MTF in the tangential direction was 0.010 and the sagittal direction was 0.003 before wearing CL, they were improved to 0.075 and 0.038, respectively. And the RMS value of the 2^nd to 4^th order aberrations decreased from 5.483 µm to 1.273 µm, too.

Conclusion: The new CL design by two-dimensional ray tracing improved the aberrations and MTF of all the subjects. This design is effective for the astigmatism and keratoconus eyes.