However the cornea makes the greatest contribution to the overall power of the eye (~60%), there are few knowledge of its role in determining the aberration of the retinal images. Most Corneal Topographers or Keratometers can only measure corneal dioptric power and shape, but cannot estimate the corneal contribution to the quality of the retinal images. On the other hand, the aberrometer measures the aberration of the eye as a single optical system, and explain the function of it. In this study, we extracted the dioptric power from the corneal topography images, and used the Ray Tracing method to simulate the principle of the Hartmann sensor (that is used to measure the wavefront). Then reconstructed the shape of the wavefront exiting from the pupil with Zernike polynomials. Finally the Sphere, Cylinder, and Axis parameters of 4 subjects were calculated, these parameters can be used as index of the correcting glasses or refractive surgery.