Fig. 6. Wavefront technology evaluates the entire optical system. The eye is illuminated by a plane wave. In an ideal eye, the wave traveling inside this organ is a spherical wave that provides a bright point on the fovea. In reality, the wavefront is not spherical. If the fovea acts as a point source, it provides a divergent spherical wave that exits the eye as a plane wave, which in reality is a deformed wave. (Haman H: A Quick Method for Analyzing Hartmann-Shack Patterns: Application to Refractive Surgery. J Refract Surg 16:S636-S642, 2000.).