Corneal Biomechanical Assessment Using Corneal Visualization Scheimpflug Technology in Keratoconic and Normal Eyes
Table 1
Comparison of tomography and biomechanical parameters between the KC and control group, mean ± SD (range).
Control
KC
P value
Tomography
Flat keratometry (diopters)
43.27 ± 1.56 (38.5–48.8)
48.47 ± 5.94 (40.1–69.3)
0a
Steep keratometry (diopters)
44.39 ± 1.61 (39.2–49.5)
52.09 ± 6.82 (40.8–72.9)
0a
Mean keratometry (diopters)
43.82 ± 1.54 (38.9–48.8)
50.18 ± 6.19 (40.8–71)
0a
Astigmatism (diopters)
1.12 ± 0.68 (0–3.7)
3.63 ± 2.72 (0.1–9.3)
0a
Central corneal thickness (μm)
546.1 ± 30.09 (498–629)
456.37 ± 57.45 (302–557)
0a
Corneal volume at 3.0 mm (mm3)
3.94 ± 0.22 (3.6–4.6)
3.45 ± 0.33 (2.7–4.1)
0a
Corneal volume at 5.0 mm (mm3)
11.56 ± 0.64 (10.5–13.3)
10.57 ± 0.76 (9–12.4)
0b
Corneal volume at 7.0 mm (mm3)
24.89 ± 1.4 (22.7–28.7)
23.31 ± 1.54 (20.3–27)
0b
Corneal volume at 10 mm (mm3)
61.2 ± 3.67 (55.8–70.9)
58.18 ± 4.01 (50.6–68.3)
0b
Anterior chamber angle (degree)
39.14 ± 5.78 (28.4–63.6)
37.25 ± 5.71 (23.6–52.5)
0.074b
Anterior chamber depth (mm)
3.17 ± 0.32 (2.2–4.03)
3.43 ± 0.4 (2.16–4.39)
0b
Anterior chamber volume (mm3)
185.2 ± 36.73 (92–276)
203.18 ± 35.64 (124–263)
0.007b
Biomechanics
A-time1 (ms)c
7.52 ± 0.43 (6.81–8.58)
7.04 ± 0.36 (5.91–7.74)
0b
A-length1 (mm)d
1.78 ± 0.27 (1.34–2.28)
1.69 ± 0.33 (0.98–2.35)
0.108b
(m/s)e
0.15 ± 0.03 (0.08–0.24)
0.17 ± 0.04 (0.11–0.26)
0.026a
A-time2 (ms)c
22.18 ± 0.52 (21.27–23.3)
22.5 ± 0.55 (21.46–23.69)
0.001b
A-length2 (mm)d
1.9 ± 0.49 (1.01–2.86)
1.47 ± 0.46 (0.66–2.54)
0b
(m/s)e
–0.39 ± 0.08 (–0.6 to 0.23)
–0.53 ± 0.15 (–0.88 to 0.24)
0a
Highest concavity time (ms)f
16.72 ± 0.49 (15.25–18.25)
16.67 ± 0.94 (11.32–17.79)
0.419a
Highest concavity curvature (mm)g
7.52 ± 1.05 (4.1–10.75)
5.59 ± 2.32 (2.75–16.83)
0b
Peak distance (mm)h
4.50 ± 1.43 (2.21–5.99)
4.50 ± 1.43 (2.15–6.29)
0.585a
Deformation amplitude (mm)i
1.08 ± 0.11 (0.87–1.33)
1.32 ± 0.19 (0.92–1.96)
0b
IOP-GAT (mmHg)j
14.85 ± 2.79 (9.5–21)
12.09 ± 1.92 (7.5–15.5)
0b
aWilcoxon rank-sum test; bindependent two-sample t-test; cA-time1 and A-time2: time from the start until the first applanation and second applanation, respectively; dA-length1 and A-length2: length of the flattened cornea at the first applanation and second applanation; e and : corneal velocities during the first and second applanation moments; f time from the start until the highest concavity of the cornea was reached; gcurvature radius of the highest concavity; hdistance of the two “knees” at the highest concavity; imaximum deformation amplitude at the corneal apex, from start to the highest concavity; jintraocular pressure measured by Goldmann applanation tonometry.