Comparative evaluation of tomographic and biometric characteristics in bilateral keratoconus patients with unilateral corneal Vogt’s striae: a contralateral eye study

Figures & data

Table 1 Contralateral comparison of basic parameters between keratoconus eyes with and without Vogt’s striae

Parameter	With Vogt’s striae		Without Vogt’s striae		Mean difference	P-value
	Mean ± SD	Range	Mean ± SD	Range
Sph (D)	−3.28±2.67	−8.75 to +1.75	−0.98±1.90	−7.25–1.50	−2.29±2.68	<0.001a
Cyl (D)	−5.03±2.10	−8.75 to −1.75	−2.52±1.90	−8.25–0.00	−2.51±2.28	<0.001a
SE (D)	−5.97±3.50	−16.62 to −0.12	−2.24±2.43	−10.12–0.88	−3.73±3.37	<0.001a
J0 (D)	1.30±1.94	−4.00–7.93	0.30±0.10	−2.07–2.62	0.10±1.62	<0.001b
J45 (D)	0.32±1.83	−3.71–3.13	−0.19±1.12	−3.25–2.62	0.55±2.62	<0.131a
UDVA (Log MAR)	0.68±0.45	0.00–1.60	0.41±0.46	0.00–1.60	0.26±0.36	<0.001a
CDVA (Log MAR)	0.31±0.30	0.00–1.00	0.09±0.11	0.00–0.40	0.23±0.26	<0.001a

Notes:

a Wilcoxon signed ranks test.

b Paired-samples t-test. Bold values are significant.

Abbreviations: Sph, sphere; Cyl, cylinder; SE, spherical equivalent; J0, Jackson cross cylinder; axes at 0° and 90°; J45, Jackson cross cylinder; axes at 45° and 135°; UDVA, uncorrected distance visual acuity; CDVA, corrected distance visual acuity; D, diopter; Log MAR, logarithm of the minimum angle of resolution.

Table 2 Contralateral comparison of biometric characteristics between keratoconus eyes with and without Vogt’s striae

Parameter	With Vogt’s striae		Without Vogt’s striae		Mean difference	P-valuea
	Mean ± SD	Range	Mean ± SD	Range
AL (mm)	23.49±0.87	21.28–25.29	23.44±0.89	20.77–25.14	0.05±0.30	0.307
ACD (mm)	3.70±0.39	2.84–4.66	3.60±0.36	2.98–4.57	0.10±0.20	0.001
VL (mm)	16.14±0.83	13.94–18.26	16.15±0.84	13.90–17.92	−0.01±0.25	0.756
LT (mm)	3.65±0.26	3.20–4.18	3.69±0.26	3.18–4.18	−0.04±0.10	0.010

Notes:

a Paired-samples t-test. Bold values are significant.

Abbreviations: AL, axial length; ACD, anterior chamber depth; VL, vitreous length; LT, lens thickness.

Table 3 Contralateral comparison of tomographic characteristics between keratoconus eyes with and without Vogt’s striae

Parameter	With Vogt’s striae		Without Vogt’s striae		Mean difference	P-value
	Mean ± SD	Range	Mean ± SD	Range
K1 front (D)	48.58±4.75	42.20–65.70	44.83±2.40	39.30–51.10	3.74±4.50	<0.001a
K2 front (D)	53.14±5.23	43.80–71.20	47.45±3.34	40.80–56.30	5.70±5.52	<0.001b
K1 back (D)	−7.23±0.90	−10.20 to −5.70	−6.31±1.02	−7.60 to −0.40	−0.92±1.20	<0.001b
K2 back (D)	−7.63±3.06	−10.60–11.80	−7.03±0.65	−8.80 to −5.70	−0.60±3.14	<0.001b
Kmax (D)	59.21±6.07	48.10–77.00	51.40±5.42	44.10–67.40	7.81±5.74	<0.001a
CCT (μm)	457.20±3.25	369.00–537.00	487.13±35.80	409.00–553.00	−29.94±25.57	<0.001a
ACD (mm)	3.56±0.36	2.79–4.47	3.41±0.40	2.28–4.24	0.15±0.25	<0.001a

Notes: All parameters were measured by Pentacam.

a Paired-samples t-test.

b Wilcoxon signed ranks test. Bold values are significant.

Abbreviations: K1, flat keratometry; K2, steep keratometry; Kmax, maximum keratometry; CCT, central corneal thickness; ACD, anterior chamber depth (internal).

Table 4 Correlation coefficients of refractive, tomographic, and biometric characteristics of keratoconus eyes with and without Vogt’s striae

Parameter	ALa (mm)		ACDa (mm)		VLa (mm)		LTa (mm)
	P-valuec	r	P-valuec	r	P-valuec	r	P-valuec	r
ALa (mm)
With Vogt’s striae	–	–	0.019	0.345	<0.001	0.928	0.333	−0.146
Without Vogt’s striae	–	–	0.002	0.436	<0.001	0.935	0.197	−0.194
ACDa (mm)
With Vogt’s striae	–	–	–	–	0.636	0.072	<0.001	−0.506
Without Vogt’s striae	–	–	–	–	0.081	−0.260	<0.001	−0.582
VLa (mm)
With Vogt’s striae	–	–	–	–	–	–	0.136	−0.224
Without Vogt’s striae	–	–	–	–	–	–	0.081	−0.260
CCTb (μm)
With Vogt’s striae	0.450	0.114	0.692	0.060	0.461	0.111	0.739	−0.050
Without Vogt’s striae	0.953	0.009	0.723	−0.054	0.643	0.070	0.718	−0.055
K1b (D)
With Vogt’s striae	0.062	−0.280	0.110	0.239	0.010	−0.376	0.944	−0.011
Without Vogt’s striae	0.051	−0.291	0.811	0.036	0.055	−0.285	0.821	0.034
K2b (D)
With Vogt’s striae	0.155	−0.213	0.368	0.136	0.053	−0.288	0.619	0.075
Without Vogt’s striae	0.250	−0.173	0.520	−0.097	0.342	−0.143	0.546	0.091
Kmaxb (D)
With Vogt’s striae	0.214	−0.187	0.083	0.259	0.116	−0.235	0.193	−0.195
Without Vogt’s striae	0.479	−0.107	0.873	−0.024	0.446	−0.115	0.552	0.090
SE (D)
With Vogt’s striae	0.302	−0.156	0.120	−0.232	0.497	−0.103	0.303	0.156
Without Vogt’s striae	0.941	0.011	0.497	0.103	0.497	−0.103	0.452	−0.114

Notes:

a Measured by ultrasound biometer.

b Measured by Pentacam.

c Pearson correlation coefficient analysis. Bold values are significant.

Abbreviations: AL, axial length; ACD, anterior chamber depth; VL, vitreous length; LT, lens thickness; CCT, central corneal thickness; K1, flat keratometry; K2, steep keratometry; Kmax, maximum keratometry; SE, spherical equivalent.

Table 5 Pentacam and ultrasound biometer measurements for anterior chamber depth of keratoconus eyes with and without Vogt’s striae

Parameter Device	Pentacam	Ultrasound	Difference		Correlation		95% LoA
	Mean ± SD	Mean ± SD	Δ	P-valuea	r	P-value	Lower	Upper
ACD (mm)
With Vogt’s striae	4.01±0.36	3.70±0.39	−0.31±0.53	0.0002	−0.005	0.974	−0.72	1.35
Without Vogt’s striae	3.90±0.39	3.60±0.36	−0.30±0.53	0.0004	0.006	0.968	−0.74	1.33

Notes:

a Paired-samples t-test. Bold values are significant.

Abbreviations: ACD, anterior chamber depth; Δ, mean difference; r, Pearson correlation coefficient; LoA, limit of agreement.

Figure 1 Bland–Altman plots of the ACD measured by the Pentacam against ultrasound biometer in KCN eyes with Vogt’s striae (top) and without Vogt’s striae (bottom). The middle line in each figure is the mean difference of the values and the lines on the sides represent the upper and lower 95% LoA (mean difference ±1.96 SD).

Abbreviations: ACD, anterior chamber depth; KCN, keratoconus; LoA, limits of agreement.