Assessment of Corneal Pachymetry Distribution and Morphologic Changes in Subclinical Keratoconus with Normal Biomechanics

Table 1

Variables used to differentiate the two study populations.

Parameters	Normal	VAE-NTB	value	AUC	95% CI	Cutoff	Sensitivity (%)	Specificity (%)
fKm (D)	42.66 ± 1.32	42.93 ± 1.22	0.331^‡	0.52	0.419–0.619	41.4	90.91	21.43
F_astig (D)	1.00 ± 0.53	1.20 ± 0.68	0.138^‡	0.581	0.480–0.678	1.40	39.39	84.29
F_Ecc^†	0.54 (0.43, 0.59)	0.60 (0.46, 0.66)	0.075^§	0.609	0.508–0.704	0.59	51.50	77.10
bKm (D)^†	−6.25 (−6.40, −6.10)	−6.20 (−6.20, −6.10)	0.119^§	0.594	0.493–0.690	−6.30	78.79	50.00
B_astig (D)^†	3.00 (3.00, 4.00)	4.00 (2.00, 5.00)	0.145^§	0.587	0.486–0.683	0.40	33.33	90.00
B_Ecc^†	0.49 (0.43, 0.56)	0.61 (0.51, 0.67)	0.001^§	0.707	0.609–0.792	0.56	60.60	77.10
Kmax (D)^†	43.90 (43.00, 44.50)	44.2 (42.95, 45.25)	0.199^§	0.579	0.477–0.675	45.10	27.27	90.00
DTCP-Apex (mm)	0.63 ± 0.16	0.85 ± 0.24	<0.001^‡	0.771	0.677–0.848	0.79	63.64	87.14
DPTCP-Apex (μm)^†	3.00 (2.00, 4.00)	6.00 (3.50, 8.00)	<0.001^§	0.753	0.659–0.833	5.00	57.58	85.71
PPImin	0.73 ± 0.11	0.74 ± 0.16	0.660^‡	0.519	0.418–0.618	0.68	42.42	72.86
PPImean	1.00 ± 0.10	1.06 ± 0.15	0.039^‡	0.625	0.524–0.719	1.03	63.64	67.14
PPImax	1.23 ± 0.13	1.42 ± 0.23	<0.001^‡	0.756	0.662–0.835	1.34	63.64	88.57
ARTave	556.0 ± 73.6	504.0 ± 74.1	0.001^‡	0.698	0.584–0.813	485.0	48.48	88.57
ARTmax^†	440.5 (410.0, 479.8)	377.0 (330.0, 426.0)	<0.001^§	0.798	0.707–0.871	377	51.52	97.14
ISV	14.79 ± 4.26	18.03 ± 4.91	0.001^‡	0.696	0.598–0.783	18.00	51.52	84.29
IVA^†	0.10 (0.06, 0.13)	0.14 (0.09, 0.16)	0.003^§	0.682	0.583–0.771	0.11	66.67	67.14
IHA^†	4.35 (1.88, 8.40)	8.20 (4.00, 12.20)	0.003^§	0.681	0.582–0.769	6.40	63.64	70.00
IHD^†	0.009 (0.005, 0.013)	0.012 (0.008, 0.017)	0.032^§	0.631	0.530–0.724	0.013	42.42	85.71
KI^†	1.02 (1.00, 1.03)	1.03 (1.02, 1.05)	0.007^§	0.665	0.565–0.755	1.02	57.58	67.14
CKI^†	1.01 (1.00, 1.01)	1.01 (1.00, 1.01)	0.659^§	0.524	0.423–0.623	1.01	9.09	98.57
B_Elv-D^†	5.00 (3.00, 7.00)	7.00 (4.50, 9.00)	0.012^§	0.653	0.552–0.744	6.00	57.58	74.29
BAD-D	0.79 ± 0.4	1.5 ± 0.7	<0.001^‡	0.799	0.708–0.871	1.20	63.64	85.71
ARTh^†	468.8 (425.2, 510.7)	479 (422.4, 530.1)	0.398	0.552	0.451–0.650	512.1	39.39	78.57
CBI^†	0.01 (0.00, 0.04)	0.02 (0.00, 0.09)	0.074^§	0.606	0.505–0.701	0.04	42.42	80.00
TBI^†	0.07 (0.01, 0.18)	0.27 (0.09, 0.74)	<0.001^§	0.760	0.666–0.838	0.17	69.70	75.71

fKm, front mean keratometry; F_astig, front astigmatism; F_Ecc, front eccentricity; bKm, back mean keratometry; B_astig, back astigmatism; B_Ecc, back eccentricity; Kmax, maximum keratometry; DTCP-Apex, distance between the corneal thinnest point and the apex; DPTCP-Apex, pachymetry difference between the corneal thinnest point and the apex; PPImin, PPImean, and PPImax, minimum, mean, and maximum pachymetry progression index, respectively; ARTave and ARTmax, average and maximum Ambrósio’s relational thickness; ISV, index of surface variation; IVA, index of vertical asymmetry; IHA, index of height asymmetry; IHD, index height decentration; KI, keratoconus index; CKI, central keratoconus index; B_Elv-D, posterior corneal elevation difference; BAD-D, Belin-Ambrósio deviation; ARTh, Ambrósio’s relational thickness to the horizontal profile; CBI, Corvis Biomechanical Index; TBI, tomography and biomechanical index; Normal, normal eyes; VAE-NTB, forme fruste keratoconus with normal biomechanics; AUC, area under the curve; CI, confidence interval. Values are listed as the mean ± standard deviation. ^†Values are listed as median (M25, M75). ^‡Independent t-test. ^§Mann–Whitney U test.