Figure 5: There was a curve fitting relationship between A.C.D and x-coma for anterior corneal surface, linear regression showed statistic differences between x-coma of posterior corneal surface (y=0.329x-0.185 r2 =0.083, p<0.000) and age, that of total corneal surface (y=0.982-0.317x, r2 =0.176, p<0.000) and A.C.D.