Logistic Regression Model Using Scheimpflug-Placido Cornea Topographer Parameters to Diagnose Keratoconus
Table 2
The mean values of shape indices and aberrations in keratoconus and normal groups.
Parameter
Keratoconus mean ± SD (range)
Normal mean ± SD (range)
value
Shape indices
Anterior rf (D)
46.83 ± 6.24 (30.63, 81.45)
42.59 ± 1.36 (39.63, 46.20)
0.01>
Anterior rs (D)
51.15 ± 8.60 (40.86, 113.3)
43.95 ± 1.53 (41.03, 48.91)
0.01>
Anterior Q
0.01 ± 1.17 (−5.45, 3.14)
0.84 ± 0.36 (−0.22, 1.47)
0.01>
Anterior RMS/A (μm/mm2)
0.20 ± 0.14 (0.01, 1.17)
0.02 ± 0.02 (0.01, 0.24)
0.01>
Posterior rf (D)
−7.17 ± 1.46 (−12.76, −3.34)
−5.93 ± 0.22 (−6.38, −4.73)
0.01>
Posterior rs (D)
−7.69 ± 5.32 (−15.85, 48.20)
−6.06 ± 1.95 (−6.87, 11)
0.01>
Posterior (p)
−0.36 ± 1.60 (−3.47, 7.19)
0.80 ± 0.55 (−0.58, 4.33)
0.01>
Posterior RMS/A (μm/mm2)
0.63 ± 0.63 (0.06, 5.69)
0.10 ± 0.06 (0.03, 0.70)
0.01>
Aberrations
Total
OPD (µm)
2.94 ± 2.43 (0.32, 14.44)
0.95 ± 0.85 (0.25, 6.29)
0.01>
HOAs (µm)
1.57 ± 1.35 (0.19, 10.18)
0.37 ± 0.42 (0.15, 4.64)
0.01>
Astigmatism Z (2, ±2) (µm)
2.37 ± 2.15 (0.02, 13.37)
0.83 ± 0.78 (0.02, 4.25)
0.01>
Coma Z (3, ±1) (µm)
1.10 ± 0.80 (0.08, 5.51)
0.17 ± 0.17 (0.01, 1.82)
0.01>
Spheric Z (4, 0) (µm)
0.26 ± 0.34 (0.01, 2.97)
0.16 ± 0.18 (0.02, 1.74)
0.042
Residual HOAs (µm)
0.89 ± 0.95 (0.13, 6.50)
0.27 ± 0.38 (0.06, 4.03)
0.01>
Anterior
OPD (µm)
2.84 ± 1.68 (0.37, 9.97)
0.96 ± 0.72 (0.20, 3.73)
0.01>
HOAs (µm)
1.62 ± 1.09 (0.23, 8.59)
0.27 ± 0.11 (0.14, 1.05)
0.01>
Astigmatism Z (2, ±2) (µm)
2.21 ± 1.49 (0.05, 9.38)
0.89 ± 0.74 (0.01, 3.71)
0.01>
Coma Z (3, ±1) (µm)
1.36 ± 0.97 (0.10, 6.44)
0.15 ± 0.09 (0.02, 0.69)
0.01>
Spheric Z (4, 0) (µm)
0.30 ± 0.36 (0.01, 2.87)
0.13 ± 0.04 (0.03, 0.28)
0.01>
Residual HOAs (µm)
0.72 ± 0.63 (0.09, 4.96)
0.16 ± 0.10 (0.06, 0.79)
0.01>
Posterior
OPD (µm)
0.94 ± 0.82 (0.12, 5.71)
0.27 ± 0.40 (0.09, 4.42)
0.01>
HOAs (µm)
0.75 ± 0.69 (0.08, 5.32)
0.21 ± 0.39 (0.05, 4.12)
0.01>
Astigmatism Z (2, ±2) (µm)
0.49 ± 0.46 (0.01, 2.60)
0.15 ± 0.14 (0.04, 1.59)
0.01>
Coma Z (3, ±1) (µ)
0.35 ± 0.33 (0.02, 1.88)
0.04 ± 0.11 (0, 1.31)
0.01>
Spheric Z (4, 0) (µm)
0.12 ± 0.14 (0, 1.27)
0.03 ± 0.15 (0, 1.72)
0.01>
Residual HOAs (µm)
0.74 ± 1.53 (0.06, 16)
0.20 ± 0.35 (0.04, 3.64)
0.01>
Mann–Whitney U test. SD: standard deviation; rf = apical radius of the flattest meridian of the aspherotoric surface in 4.5 mm zone of the cornea; rs = apical radius of the steepest meridian of the aspherotoric surface in 4.5 mm zone of the cornea; Q = mean asphericity 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, OPD = total wavefront error; HOAs = higher-order aberrations.
