Figure 4: Zernike coefficient decomposition: The software fits a Zernike function to the measured topography. It enables a coefficient analysis of the resulting Zernike fit. The values for each coefficient are listed as numbers or, in case of the above image, displayed by a bar graph. The coefficients for tilt in and directions are marked by arrows. They guide the operator in centering the sample. Measuring a decentered sample will lead to higher tilt values. By lateral adjustment of the sample holder, the operators can find the position where they are minimal. The measured IOL is then centered.