Table 3: Cutoff values between normal and keratoconus population at each measuring point with the statistical measures obtained at these cutoff values.

ParameterCutoffSensitivitySpecificityPPVNPVAUC (95% CI)

BFS RMS-P18.70.9390.7630.5970.9710.900 (0.870, 0.940)
BFS AA3.500.5850.9410.7870.8580.760 (0.680, 0.840)
BFS PA7.500.7440.9450.8360.9080.840 (0.770, 0.910)
BFS AT5.500.9510.9730.9290.9820.990 (0.990, 1.000)
BFS PT17.50.9760.9910.9760.9911.000 (1.000, 1.000)
BFTEFE RMS-P7.990.9510.9820.9510.9820.990 (0.990, 1.000)
BFTEFE AA1.500.6590.9680.8850.8830.800 (0.730, 0.870)
BFTEFE PA4.500.7320.9730.9090.9060.860 (0.790, 0.920)
BFTEFE AT1.500.9630.9770.9400.9860.980 (0.950, 1.000)
BFTEFE PT8.001.0000.9950.9881.0001.000 (1.000, 1.000)
BFTE RMS-P5.870.9270.9450.8640.9720.980 (0.960, 1.000)
BFTE AA−1.500.4020.9770.8680.8140.590 (0.510, 0.680)
BFTE PA−1.500.5120.9000.6560.8310.620 (0.520, 0.710)
BFTE AT0.500.8410.9320.8210.9400.910 (0.860, 0.960)
BFTE PT3.500.8660.9680.9100.9510.950 (0.920, 0.990)

AA, anterior elevation at the apex; AT, anterior elevation at the thinnest point; AUC, area under the curve; BFS, best fit sphere; BFTE, best fit toric ellipsoid; BFTEFE, best fit toric ellipsoid with fixed eccentricity; CI, confidence interval; NPV, negative predictive value; RMS-P, root mean square of posterior elevations; PA, posterior elevation at the apex; PPV, positive predictive value; PT, posterior elevation at the thinnest point.