Logistic Regression Model Using Scheimpflug-Placido Cornea Topographer Parameters to Diagnose Keratoconus
Table 4
Receiver operating characteristic (ROC) analysis of the parameters where AUROC values are greater than 0.9 95% confidence interval.
Parameter
AUROC
SE
Lower
Upper
Cut-off value
Sensitivity (%)
Specificity (%)
Corneal indices
TCT (μm)
0.956
0.012
0.933
0.979
500.5
90.4
90.8
Kmax (D)
0.927
0.016
0.895
0.959
47.85
84
88.3
CCT (μm)
0.934
0.015
0.904
0.963
511.5
87.2
88.3
Specially calculated indices
Kmax/TCT (D/μm)
0.974
0.009
0.957
0.991
0.097
89.6
97.5
Kmax2/TCT (D2/μm)
0, 975
0.008
0.959
0.991
0.0001
89.6
97.5
Keratometry readings
Anterior Ø = 3 mm K2 (D)
0.901
0.020
0.862
0.940
45.60
81.6
86.7
Posterior Ø = 3 mm K2 (D)
0.919
0.02
0.877
0.961
−6.73
85.6
95
Shape indices
Anterior rs (D)
0.909
0.019
0.871
0.947
46.36
79.2
94.2
Anterior RMS/A (μm/mm2)
0.965
0.013
0.940
0.990
0.065
90.4
95.8
Posterior rs (D)
0.906
0.023
0.861
0.951
−6.70
84
95.8
Posterior RMS/A (μm/mm2)
0.974
0.011
0.953
0.995
0.165
92.8
96.7
Keratoconus indices
SIf (D)
0.950
0.017
0.917
0.983
0.89
88.8
98.3
KVf (μm)
0.974
0.009
0.956
0.992
9.5
92
94.2
BCVf (D)
0.976
0.01
0.956
0.996
0.51
92.8
96.7
SIb (D)
0.936
0.082
0.897
0.974
0.225
88.8
98.3
KVb (μm)
0.965
0.013
0.939
0.990
20.5
92
95.8
BCVb (D)
0.965
0.013
0.940
0.990
0.555
88.8
97.5
Aberrations
Total
HOAs (µm)
0.940
0.016
0.909
0.972
0.60
85.6
93.3
Coma Z (3, ±1) (µm)
0.933
0.017
0.899
0.966
0.39
81.6
96.7
Residual (µm)
0.907
0.020
0.868
0.945
0.295
90.4
79.2
Anterior
HOAs (µm)
0.975
0.009
0.958
0.992
0.575
88.8
97.5
Coma Z (3, ±1) (µm)
0.963
0.011
0.941
0.986
0.375
87.2
97.5
Residual (µm)
0.950
0.014
0.923
0.977
0.270
89.6
89.2
Posterior
OPD (µm)
0.911
0.020
0.870
0.951
0.375
85.6
90
HOAs (µm)
0.913
0.019
0.876
0.951
0.305
84
89.2
Coma Z (3, ±1) (µm)
0.959
0.014
0.933
0.986
0.075
91.2
97.5
AUROC: area under the ROC curve; SE: standard error; TCT = minimum corneal thickness; Kmax = keratometry of the steepest point recorded from the anterior tangential map; CCT = central corneal thickness; K2 = steep keratometry; rs = apical radius of the steepest meridian of the aspherotoric surface in 4.5 mm zone of the cornea; RMS/A: root mean square values per unit area in 4.5 mm zone of the cornea; SIf = symmetry index front; KVf = keratoconus vertex front index; BCVf = Baiocchi Calossi Versaci front index; SIb = symmetry index back; KVb = keratoconus vertex back index; BCVb = Baiocchi Calossi Versaci back index; OPD = total wavefront error; HOAs = higher-order aberrations OPD = total wavefront error; HOAs = higher-order aberrations.
