Assessment of Pattern and Shape Symmetry of Bilateral Normal Corneas by Scheimpflug Technology
Abstract
:1. Introduction
2. Materials and Methods
2.1. Study Participants and Examination Protocol
2.2. Data Acquisition
2.3. Methods
2.3.1. Morphogeometric Symmetry
2.3.2. Axial Symmetry at the Corneal Vertex
- Adjust the point cloud to a general quadric model (ellipsoid) and subsequently transform into a perfect ellipsoid. With the help of some algorithms programmed in Matlab software that use the equations defined in Navarro’s model [34], we adjust the finite and discrete set of spatial data representative of the spatial surfaces (raw data) to an ellipsoid. Then, we perform the algebraic transformation with the matrix equations of the obtained ellipsoid into a perfect ellipsoid at the vertex reference point (V0), whose main axes are the 3 main position and orientation orthogonal axes in 3D space (Figure 2).
2.3.3. Angular-Spatial Symmetry
- Export the raw data CSV files from Sirius. This procedure is the same as in point 1 of Section 2.3.2.
- Identify the singular points for each ring by the elevation coordinate (Zi) and its angular position (αi). The Cartesian coordinate matrix (raw data) size is 20 × 256, where the 20 rows correspond to the projection of the 20 Placido’s discs (radius: 0, 0.2, 0.4, 0.6, 1, … 4 mm) on the corneal surface area, so they cover the corneal region for those corneas with a radius equal to 4 mm. Each matrix point i has a Cartesian elevation coordinate (Zi) and an angular position (αi) in relation to the projection ring of the Placido’s disc (anticlockwise). By the algorithm programmed in Matlab, we obtained the uppermost (Zmax) points in relation to the corneal vertex, and their angular positions (αZmax) in relation to the projection ring. This algorithm also helped us to identify each singular point with respect to the 8 defined octants.
2.3.4. Direct Symmetry (Equal Octants) and Enantiomorphism (Mirror Octants)
- Export the raw data CSV files from Sirius. This procedure is the same as in point 1 of Section 2.3.3. Identify the intersection points (ZX′–OD/ZX″–OD) between the octant axes and the Placido’s discs. For the Cartesian coordinate matrix described in the previous patterns, the points placed on all 8 axes that divide the corneal region are identified. Using another algorithm programmed in Matlab, we identify the 8 points for each Placido’s disc by their angular position, which must coincide with the angles of the octant axes, and obtain the Cartesian elevation coordinates for the right eye (ZA′ … ZH′) and the left eye (ZA″ … ZH″) (Figure 4). Our study considered only the intersection points between the octant axes and the Placido’s discs for radius r = 1, 2, 3, and 4 mm.
- Apply enantiomorph (mirror octants). In this pattern, the octants of the right eye do not coincide with the octants of the left eye. Instead, each right eye (OD) octant has a corresponding octant in the left eye (OS) via its specular image; that is, by its specular image, octant I-OD corresponds to octant IV-OS (Figure 5). As in the previous point, by means of another algorithm programmed in Matlab, the differences between the elevation coordinates for each pair of points are calculated (Table 3).
2.4. Statistical Analysis
3. Results
3.1. Analysis of Morphogeometric Corneal Symmetry
3.2. Analysis of Axial Symmetry at the Corneal Vertex
3.3. Analysis of Angular-Spatial Symmetry
3.4. Analysis of Direct Symmetry (Equal Octants) and Enantiomorphism (Mirror Octants)
4. Discussion
5. Conclusions
Author Contributions
Funding
Conflicts of Interest
References
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Morphogeometric Variable | Acronym | Description |
---|---|---|
Corneal volume (mm3) | CV | Volume defined by the solid model generated |
Anterior/posterior corneal surface area (mm2) | Aant/Apost | Area of the exterior/interior surface |
Corneal surface area (mm2) | Atot | Area defined by the solid model generated |
Anterior/posterior apex deviation (mm) | Dapexant/Dapexpost | Distance from the optical axis to the apex of the anterior/posterior corneal surfaces |
Anterior/posterior minimum thickness point deviation (mm) | Dmctant/Dmctpost | Distance in the XY plane from the optical axis to the minimum thickness points of the anterior/posterior corneal surfaces |
Shape Parameters | Acronym | Description |
---|---|---|
Horizontal/vertical apical radius (mm) | RX/RY | Radius of curvature at apex with respect to x and y axes |
Horizontal/vertical asphericity | QX/QY | Average variation of instantaneous curvature at each point P along corneal meridian with respect to x and y axes |
Angular coordinates of rotational displacement (°) | α/β/γ | Rotation in angular coordinates (α, β, γ) of x, y, and z axes with respect to the vertex (V) of a normal cornea (projection in XOY plane of a normal ellipsoid) toward the vertex (V0) of a perfect cornea (projection in XOY plane of a perfect ellipsoid) |
Cartesian coordinates of translational displacement (mm) | X0/Y0/Z0 | Distance in Cartesian coordinates (x, y, z) of the vertex (V) of a normal cornea (projection in XOY plane of a normal ellipsoid) toward the vertex (V0) of a perfect cornea (projection in XOY plane of a perfect ellipsoid) |
Parameters of the ellipsoid (mm) | a/b/c | Main parameters of the canonical representation of ellipsoid of major adjustment |
Equal Octants | Mirror Octants |
---|---|
ZA′–ZA″ | ZA′–ZE″ |
ZB′–ZB″ | ZB′–ZD″ |
ZC′–ZC″ | ZC′–ZC″ |
ZD′–ZD″ | ZD′–ZB″ |
ZE′–ZE″ | ZE′–ZA″ |
ZF′–ZF″ | ZF′–ZH″ |
ZG′–Z G″ | ZG′–Z G″ |
ZH′–ZH″ | ZH′–ZF″ |
Measurement | Right Eye (OD) | Left Eye (OS) | p-Value |
---|---|---|---|
Mean (SD) Median (Range) | Mean (SD) Median (Range) | ||
Sphere (D) | −0.03 (3.52) 0.25 (−10.00 to 8.50) | −0.20 (3.78) 0.00 (−12.00 to 8.00) | 0.159 |
Cylinder (D) | −0.60 (0.54) −0.50 (−2.00 to 0.00) | −0.76 (1.07) −0.50 (−5.75 to 0.00) | 0.316 |
SE (D) | −0.33 (3.46) 0.00 (−10.00 to 8.12) | −0.58 (3.72) 0.00 (−12.00 to 7.75) | 0.126 |
Decimal CDVA | 1.00 (0.09) 1.00 (0.60 to 1.20) | 1.00 (0.10) 1.00 (0.60 to 1.20) | 0.892 |
Q4.5 | −0.11 (0.26) −0.07 (−0.65 to 0.31) | −0.16 (0.24) −0.18 (−0.65 to 0.19) | 0.169 |
Q8 | −0.27 (0.21) −0.29 (−0.78 to 0.10) | −0.27 (0.18) −0.26 (−0.65 to 0.05) | 0.990 |
HOA RMS (μm) 6 mm pupil | 0.43 (0.12) 0.42 (0.25 to 0.76) | 0.41 (0.11) 0.39 (0.4 to 0.70) | 0.182 |
Coma RMS (μm) 6 mm pupil | 0.29 (0.11) 0.30 (0.08 to 0.49) | 0.27 (0.11) 0.27 (0.02 to 0.54) | 0.102 |
SA (μm) 6 mm pupil | 0.22 (0.05) 0.22 (0.13 to 0.35) | 0.22 (0.06) 0.23 (0.08 to 0.32) | 0.737 |
MCT (μm) | 539.2 (31.5) 541.9 (479.6 to 610.9) | 540.3 (29.0) 540.5 (485.4 to 609.0) | 0.448 |
CCT (μm) | 542.8 (31.8) 544.0 (482.0 to 615.0) | 543.9 (29.4) 546.0 (489.0 to 614.0) | 0.458 |
CV (mm3) | 25.8 (1.6) 26.2 (23.2 to 29.1) | 25.9 (1.5) 26.1 (23.3 to 28.9) | 0.565 |
Measurement | Right Eye (OD) | Left Eye (OS) | p-Value |
---|---|---|---|
Mean (SD) Median (Range) | Mean (SD) Median (Range) | ||
Aant (mm2) | 43.09 (0.12) 43.08 (42.84 to 43.34) | 43.10 (0.12) 43.13 (42.83 to 43.32) | 0.055 |
Apost (mm2) | 44.27 (0.26) 44.29 (43.53 to 44.72) | 44.28 (0.27) 44.28 (43.52 to 44.75) | 0.572 |
Atot (mm2) | 104.04 (1.24) 104.07 (100.72 to 106.15) | 104.08 (1.23) 104.14 (100.80 to 106.09) | 0.580 |
Dapexant (mm) | 0.00 (0.00) 0.00 (0.00 to 0.00 | 0.00 (0.00) 0.00 (0.00 to 0.00 | 0.999 |
Dapexpost (mm) | 0.07 (0.02) 0.08 (0.03 to 0.13) | 0.07 (0.02 to 0.65) 0.87 (0.22) | 0.488 |
Dmctant (mm) | 0.89 (0.27) 0.89 (0.45 to 1.66) | 0.87 (0.22) 0.88 (0.48 to 1.31) | 0.659 |
Dmctpost (mm) | 0.81 (0.23) 0.84 (0.40 to 1.53) | 0.79 (0.22) 0.77 (0.40 to 1.24) | 0.606 |
Measurement | Right Eye (OD) | Left Eye (OS) | p-Value |
---|---|---|---|
Mean (SD) Median (Range) | Mean (SD) Median (Range) | ||
Rx (mm) | 7.62 (0.21) 7.58 (7.28 to 8.09) | 7.61 (0.23) 7.55 (7.10 to 8.07) | 0.549 |
Ry (mm) | 7.79 (0.19) 7.79 (7.52 to 8.24) | 7.79 (0.19) 7.76 (7.49 to 8.19) | 0.851 |
Qx | −0.27 (0.11) −0.27 (−0.51 to −0.05) | −0.27 (0.12) −0.24 (−0.56 to −0.02) | 0.981 |
Qy | −0.25 (0.11) −0.26 (−0.51 to −0.02) | −0.25 (0.12) −0.23 (−0.49 to 0.00) | 0.999 |
Alpha (°) | −4.17 (28.62) 1.24 (−161.10 to 13.31) | −3.87 (25.53) −0.39 (−143.08 to 13.49) | 0.814 |
Beta (°) | −0.05 (11.16) 1.10 (−52.67 to 27.55) | −2.05 (9.59) −1.70 (−49.32 to 18.71) | 0.012 |
Gamma (°) | −43.08 (91.21) −80.75 (−151.45 to 152.23) | −29.53 (10.50) −80.55 (−176.10 to 173.43) | 0.596 |
X0 (mm) | 0.20 (0.19) 0.14 (−0.13 to 0.88) | −0.18 (0.26) −0.15 (−1.37 to 0.08) | <0.001 |
Y0 (mm) | −0.003 (0.219) −0.016 (−0.630 to 0.560) | 0.036 (0.204) −0.001 (−0.470 to 0.690) | <0.001 |
Z0 (mm) | 10.61 (1.70) 10.43 (8.12 to 15.25) | 10.65 (1.86) 10.00 (8.19 to 15.99) | 0.325 |
a (mm) | 8.98 (0.68) 9.00 (8.00 to 10.64) | 8.98 (0.72) 8.80 (8.16 to 10.69) | 0.994 |
b (mm) | 9.07 (0.68) 9.08 (8.17 to 10.84) | 9.08 (0.77) 8.86 (8.22 to 11.46) | 0.345 |
c (mm) | 10.63 (1.69) 10.43 (8.27 to 15.26) | 10.67 (1.87) 10.01 (8.25 to 16.11) | 0.845 |
Measurement | Right Eye (OD) | Left Eye (OS) | p-Value |
---|---|---|---|
Mean (SD) Median (Range) | Mean (SD) Median (Range) | ||
Rx (mm) | 6.21 (0.29) 6.25 (5.74 to 6.90) | 6.22 (0.30) 6.27 (5.75 to 6.94) | 0.466 |
Ry (mm) | 6.49 (0.29) 6.49 (6.00 to 7.06) | 6.50 (0.27) 6.48 (6.00 to 7.13) | 0.535 |
Qx | −0.35 (0.21) −0.33 (−0.99 to −0.08) | −0.34 (0.19) −0.30 (−0.79 to−0.07) | 0.606 |
Qy | −0.32 (0.22) −0.30 (−0.98 to −0.05) | −0.31 (0.19) −0.28 (−0.75 to −0.04) | 0.685 |
Alpha (°) | 6.15 (30.07) −1.59 (−14.15 to 132.15) | 4.70 (23.66) −3.46 (−9.19 to 86.79) | 0.562 |
Beta (°) | −8.80 (19.68) −3.87 (−73.89 to 7.58) | −6.30 (15.42) −5.24 (−59.11 to 40.24) | 0.506 |
Gamma (°) | −22.62 (87.81) −75.31 (−98.32 to 120.09) | −78.51 (45.54) −90.51 (−108.98 to 86.76) | 0.004 |
X0 (mm) | 1.49 (7.81) 0.06 (−0.62 to 44.91) | −0.23 (0.54) −0.09 (−2.37 to 0.26) | 0.229 |
Y0 (mm) | 1.09 (4.64) 0.17 (−0.10 to 26.81) | 0.31 (0.42) 0.19 (−0.16 to 2.14) | 0.335 |
Z0 (mm) | 22.39 (67.41) 9.97 (6.59 to 397.35) | 10.99 (4.28) 9.34 (6.63 to 26.71) | 0.331 |
a (mm) | 9.08 (7.14) 7.63 (6.04 to 48.19) | 7.95 (1.42) 7.57 (6.10 to 12.24) | 0.342 |
b (mm) | 9.28 (7.35) 7.73 (6.16 to 49.58) | 8.13 (1.52) 7.71 (6.21 to 13.32) | 0.345 |
c (mm) | 22.00 (67.99) 9.48 (6.32 to 400.21) | 10.51 (4.29) 8.83 (6.34 to 26.39) | 0.330 |
Right Eye (OD) | Left Eye (OS) | p-Value | |
---|---|---|---|
Measurement | Mean (SD) Median (Range) Most Common Position | Mean (SD) Median (Range) Most Common Position | |
Radius 1 mm Anterior Zmax (mm) | 0.07 (0.02) 0.07 (0.06 to 0.13) Octants 7 (27.3%) and 3 (18.2%) | 0.07 (0.01) 0.07 (0.06 to 0.13) Octants 7 (33.3%) and 6 (18.2%) | 0.984 |
Posterior Zmax (mm) | 0.63 (0.03) 0.64 (0.57 to 0.71) Octants 2 (60.6%) and 1 (27.3%) | 0.63 (0.03) 0.64 (0.58 to 0.70) Octants 3 (69.7%) and 4 (21.2%) | 0.247 |
Radius 2 mm Anterior Zmax (mm) | 0.27 (0.03) 0.27 (0.25 to 0.39) Octants 3 (24.2%) and 7 (21.2%) | 0.27 (0.03) 0.27 (0.25 to 0.38) Octants 7 (30.3%) and 3 (15.2%) | 0.950 |
Posterior Zmax (mm) | 0.88 (0.04) 0.89 (0.81 to 0.97) Octants 2 (72.7%) and 3 (24.2%) | 0.89 (0.04) 0.90 (0.81 to 0.97) Octants 3 (84.8%) and 2 (9.1%) | 0.171 |
Radius 3 mm Anterior Zmax (mm) | 0.62 (0.05) 0.61 (0.57 to 0.79) Octants 3 (36.4%) and 7 (18.2%) | 0.62 (0.04) 0.62 (0.57 to 0.78) Octants 2 (24.2%) and 7 (18.2%) | 0.900 |
Posterior Zmax (mm) | 1.31 (0.05) 1.32 (1.18 to 1.42) Octants 2 (57.6%) and 3 (27.3%) | 1.32 (0.05) 1.33 (1.18 to 1.40) Octants 3 (72.7%) and 2 (15.2%) | 0.560 |
Radius 4 mm Anterior Zmax (mm) | 1.05 (0.27) 1.12 (0.00 to 1.18) Octants 3 (27.3%) and 2 (21.2%) | 1.05 (0.27) 1.12 (0.00 to 1.18) Octants 2 (24.2%) and 8 (24.2%) | 0.936 |
Posterior Zmax (mm) | 1.93 (0.07) 1.94 (1.71 to 2.05) Octants 7 (30.3%) and 3 (24.2%) | 1.93 (0.07) 1.94 (1.73 to 2.05) Octants 3 (36.4%) and 6 (27.3%) | 0.745 |
Radius 1 mm | Radius 2 mm | Radius 3 mm | Radius 4 mm | ||
---|---|---|---|---|---|
ZX′ (OD) – ZX″ (OS) (Equal Octants) | Mean (SD) Median (Range) | Mean (SD) Median (Range) | Mean (SD) Median (Range) | Mean (SD) Median (Range) | p-Value (1 mm vs. 4 mm) |
Anterior Corneal Surface | |||||
A′–A″ (µm) | −0.09 (10.56) −0.25 (−29.70 to 30.83) | −1.16 (21.56) −1.39 (−63.46 to 63.42) | −5.48 (35.12) -4.39 (-111.02 to 99.96) | −16.90 (384.25) −10.15 (−1128.54 to 1061.36) | 0.80 |
B′–B″ (µm) | −0.07 (10.29) −0.05 (−30.10 to 29.59) | −0.33 (20.53) −0.02 (−63.00 to 58.30) | −0.58 (31.59) 0.33 (−95.62 to 91.05) | −2.92 (386.91) 2.90 (−1110.24 to 1088.41) | 0.97 |
C′–C″ (µm) | 0.09 (9.76) 0.17 (−28.74 to 28.38) | 0.98 (18.94) 1.34 (−54.76 to 55.54) | 4.75 (28.78) 4.73 (−75.78 to 86.28) | 11.19 (387.67) 6.41 (−1109.13 to 1098.68) | 0.87 |
D′–D″ (µm) | 0.17 (10.06) 0.07 (−27.72 to 30.11) | 0.79 (20.04) 0.30 (−54.64 to 60.80) | 3.83 (31.91) 3.25 (−83.97 to 97.74) | 12.57 (384.88) 15.39 (−1108.79 to 1085.62) | 0.86 |
E′–E″ (µm) | −0.01 (10.53) −0.01 (−29.09 to 30.68) | −0.27 (21.47) −0.09 −58.18 to 62.89) | 0.25 (34.58) 1.54 (−92.19 to 100.23) | 1.41 (387.93) 5.13 (−1128.11 to 1092.12) | 0.98 |
F′–F″ (µm) | −0.22 (10.34) −0.22 (−29.25 to 29.88) | −1.14 (20.42) −1.22 (−58.06 to 57.71) | −3.08 (31.37) −2.92 (−89.28 to 85.70) | −10.02 (394.50) −4.20 (−1164.97 to 1094.93) | 0.89 |
G′–G″ (µm) | −0.01 (10.02) −0.16 (−28.37 to 28.96) | −0.75 (19.56) −0.93 (−57.28 to 56.69) | −3.68 (30.24) −2.25 (−91.96 to 85.11) | −15.21 (388.90) −14.95 (−1147.93 to 1072.35) | 0.83 |
H′–H″ (µm) | 0.13 (22.37) −0.13 (−62.49 to 65.21) | −0.58 (42.56) −1.48 (−119.22 to 126.11) | −4.16 (65.42) −5.10 (−189.76 to 193.95) | −20.20 (381.52) −19.01 (−1128.63 to 1048.49) | 0.77 |
Posterior Corneal Surface | |||||
A′–A″ (µm) | 6.47 (14.79) 7.17 (−34.30 to 34.07) | 16.40 (21.20) 17.39 (−37.99 to 54.74) | 24.59 (28.43) 27.42 (−46.15 to 79.81) | −0.80 (50.65) 2.81 (−153.69 to 97.13) | 0.43 |
B′–B″ (µm) | −1.96 (11.86) −3.13 (−36.25 to 18.43) | −1.81 (13.51) −2.61 (−37.95 to 26.85) | −0.78 (16.93) −0.79 (−46.78 to 35.16) | −5.75 (35.00) −3.18 (−97.58 to 94.60) | 0.54 |
C′–C″ (µm) | −9.43 (13.38) −8.70 (−48.50 to 12.81) | −16.81 (20.07) −17.29 (−68.24 to 30.00) | −21.44 (30.21) −27.50 (−86.19 to 40.59) | 0.40 (46.52) −2.52 (−90.91 to 103.92) | 0.22 |
D′–D″ (µm) | −16.97 (16.73) −18.04 (−60.09 to 18.51) | −30.09 (27.06) −33.49 (−92.33 to 41.95) | −43.19 (39.46) −49.00 (−130.73 to 62.94) | −45.62 (58.76) −54.94 (−185.60 to 81.02) | <0.01 |
E′–E″ (µm) | −12.02 (14.19) −11.53 (−53.86 to 16.79) | −23.78 (21.59) −27.86 (−79.60 to 30.69) | −37.76 (31.63) −44.22 (−113.25 to 43.88) | −47.13 (46.55) −52.98 (−148.28 to 74.72) | <0.01 |
F′–F″ (µm) | −4.03 (12.16) −3.13 (−39.68 to 12.03) | −5.85 (13.13) −4.84 (−49.54 to 12.84) | −7.74 (16.81) −4.66 (−68.22 to 16.58) | −9.24 (24.93) −3.74 (−88.05 to 33.27) | 0.20 |
G′–G″ (µm) | 5.45 (14.90) 5.75 (−32.47 to 30.66) | 14.99 (21.18) 15.17 (−33.76 to 49.16) | 26.09 (31.88) 26.32 (−35.20 to 91.49) | 34.39 (44.94) 36.42 (−58.31 to 135.05) | <0.01 |
H′–H″ (µm) | 11.15 (17.61) 10.94 (−29.37 to 43.27) | 24.40 (27.58) 23.86 (−50.35 to 73.36) | 39.14 (40.38) 41.86 (−63.25 to 115.43) | 44.10 (56.82) 53.20 (−84.18 to 136.37) | <0.01 |
Radius 1 mm | Radius 2 mm | Radius 3 mm | Radius 4 mm | ||
---|---|---|---|---|---|
ZX′ (OD)– ZX″ (OS) (Mirror Octants) | Mean (SD) Median (Range) | Mean (SD) Median (Range) | Mean (SD) Median (Range) | Mean (SD) Median (Range) | p-Value (1 mm vs 4 mm) |
Anterior Corneal Surface | |||||
A′–E″ (µm) | 0.58 (10.32) 0.40 (−27.33 to 30.89) | 1.77 (20.54) 0.74 (−53.01 to 62.89) | 3.14 (32.21) 0.87 (−84.19 to 99.34) | 5.72 (381.94) 8.53 (−1108.79 to 1061.36) | 0.94 |
B′–D″ (µm) | 0.50 (10.02) 0.27 (−28.03 to 29.46) | 2.58 (19.31) 2.03 (−52.23 to 58.00) | 7.84 (29.07) 8.44 (−73.10 to 91.29) | 13.75 (386.94) 15.69 (−1109.13 to 1088.41) | 0.84 |
D′–B″ (µm) | −0.33 (10.21) −0.29 (−30.15 to 30.03) | −2.42 (21.03) −2.21 (−65.08 to 61.32) | −5.73 (35.17) −5.30 (−110.80 to 98.36) | 10.23 (380.81) −8.30 (−1128.5 to 1085.6) | 0.88 |
E′–A″ (µm) | −1.62 (17.15) 0.12 (−62.01 to 31.01) | −2.29 (33.19) −0.04 (−116.23 to 64.37) | −2.45 (52.18) −0.19 (−180.32 to 105.19) | 2.16 (386.87) −0.66 (−1128.63 to 1092.12) | 0.96 |
F′–H″ (µm) | 0.30 (10.19) 0.14 (−27.81 to 30.23) | 0.48 (20.22) −0.39 (−54.80 to 59.90) | 0.02 (31.73) −2.51 (−83.85 to 94.17) | −5.74 (391.77) −6.42 (−1147.93 to 1094.93) | 0.93 |
H′–F″ (µm) | 1.74 (17.62) −0.26 (−29.22 to 65.39) | 1.44 (33.94) −2.50 (−61.17 to 124.64) | −1.46 (52.06) −5.17 (−101.63 to 188.99) | −20.95 (382.57) −17.90 (−1128.11 to 1048.49) | 0.75 |
Posterior Corneal Surface | |||||
A′–E″ (µm) | 1.30 (13.15) 3.53 (−35.48 to 30.05) | 9.27 (16.09) 10.75 (−39.66 to 47.90) | 19.23 (23.57) 21.42 (−60.39 to 61.40) | 3.03 (43.54) 1.46 (−122.71 to 88.32) | 0.80 |
B′–D″ (µm) | −2.07 (12.42) −0.41 (−39.52 to 19.39) | 2.50 (16.74) 2.37 (−46.78 to 40.59) | 11.73 (23.89) 8.10 (−54.86 to 61.41) | 19.70 (35.15) 23.77 (−83.97 to 75.25) | <0.01 |
D′–B″ (µm) | −1.18 (12.10) −9.28 (−47.86 to 9.28) | −2.29 (14.93) −19.59 (−59.99 to 2.77) | −3.78 (21.35) −38.66 (−85.13 to 3.66) | −4.94 (32.51) −51.41 (−134.6 to 35.74) | <0.01 |
E′–A″ (µm) | −3.15 (11.82) −1.86 (−38.47 to 16.47) | −2.04 (13.41) 1.18 (−36.67 to 21.08) | 1.98 (18.06) 4.25 (−47.29 to 45.80) | 11.07 (30.47) 11.78 (−69.37 to 95.99) | <0.01 |
F′–H″ (µm) | 1.44 (13.00) 1.84 (−35.00 to 18.67) | 10.58 (16.16) 8.61 (−25.13 to 45.23) | 22.22 (22.23) 22.50 (−29.92 to 77.71) | 29.84 (37.33) 34.44 (−56.98 to 115.93) | <0.01 |
H′–F″ (µm) | 2.29 (13.48) 2.30 (−35.86 to 24.85) | 2.67 (15.91) 2.29 (−44.93 to 36.23) | −0.60 (21.62) 1.71 (−69.32 to 44.15) | −14.09 (34.85) −7.11 (−126.26 to 43.76) | <0.01 |
© 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
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Cavas-Martínez, F.; Piñero, D.P.; Fernández-Pacheco, D.G.; Mira, J.; Cañavate, F.J.F.; Alió, J.L. Assessment of Pattern and Shape Symmetry of Bilateral Normal Corneas by Scheimpflug Technology. Symmetry 2018, 10, 453. https://doi.org/10.3390/sym10100453
Cavas-Martínez F, Piñero DP, Fernández-Pacheco DG, Mira J, Cañavate FJF, Alió JL. Assessment of Pattern and Shape Symmetry of Bilateral Normal Corneas by Scheimpflug Technology. Symmetry. 2018; 10(10):453. https://doi.org/10.3390/sym10100453
Chicago/Turabian StyleCavas-Martínez, Francisco, David P. Piñero, Daniel G. Fernández-Pacheco, Jorge Mira, Francisco J. F. Cañavate, and Jorge L. Alió. 2018. "Assessment of Pattern and Shape Symmetry of Bilateral Normal Corneas by Scheimpflug Technology" Symmetry 10, no. 10: 453. https://doi.org/10.3390/sym10100453