Fig. 3. Linear regression analysis of the relationship between posterior corneal cylinder power and cylinder power difference between the simulated keratometry (K) and total cornea. The solid line represents a linear regression line (Y = 0.928X − 0.868, R² = 0.240, p = 0.004) for the keratoconus group (filled triangles), and the dashed line represents a linear regression line (Y = 0.786X − 0.172, R² = 0.592, p < 0.001) for the normal controls (open circles). CD = cylinder diopters.