We analyzed data from 4 orthokeratology studies of refractive error change (ARE) and keratometer-reading change (ΔK). Instead of the reported ΔRE/ΔK ratio of 2:1, we calculated from linear-regression analysis a ratio (slope) of 2:3. The ordinate intercept of the straight line fitted to the data (N = 181 eyes) indicates that when ΔK = 0, ΔRE = 0.72. The correlation between ΔK and ΔRE is poor (+0.63). Causes and interpretations of these results are discussed.