Changes in the 3D Corneal Structure and Morphogeometric Properties in Keratoconus after Corneal Collagen Crosslinking
Abstract
:1. Introduction
2. Materials and Methods
2.1. Study Population
2.2. Surgical Procedure
2.3. Examinations and Measurements
2.4. Morphogeometric Analysis
- Data Acquisition. A custom-made script programmed in the Matlab R2017b (Mathworks, Natick, USA) software was created to transform each point of the cloud provided by the tomographer in polar coordinates into the Cartesian format. This procedure has been meticulously described in several previous research works [8,9,10,11,12,13,14,15]. The program provides a. CSV file containing data of the points of clouds that describe both the anterior and posterior corneal surfaces for the area comprised between the geometric center of the cornea (r = 0 mm) and the mid-peripheral area (r = 4 mm). This zone usually contains most corneal anomalies for not only diseased, but also healthy eyes [8,9,10,11,12,13,14,15]. Afterward, both surfaces were imported to the Rhinoceros V 5.0 (MCNeel and Associates, Seattle, USA) software, and the “patch” function was used to find the surfaces that better fitted the clouds of points. The fixed configuration settings for the function were:
- •
- Sample point spacing: 256;
- •
- Surface span planes: 255 for both directions “u” and “v”;
- •
- Stiffness of the solution surface: 1.
- Solid modeling and morphogeometric analysis. Finally, a customized three-dimensional model of the patient’s cornea was created from the surfaces previously generated in Rhinoceros by importing them to the SolidWorks V2018 (Dassault Systèmes, Vélizy-Villacoublay, France) software [8,9,10,11,12,13,14,15]. This model was then analyzed, and several morphogeometrical parameters were established. These parameters herein studied, as well as their particularities, have been previously described in several other articles [8,9,10,11,12,13,14,15]. This was also the case of several volumetric parameters related directly to the volumes around the anterior/posterior apices and the minimum thickness points [12].
- Aant: area of the anterior corneal surface [9].
- Apost: area of the posterior corneal surface [9].
- Atot: total area of the corneal surface [9].
- CV: total cornea volume [9].
- AAD: anterior apex deviation, which is the minimum mean distance between the point of maximum curvature (apex) of the anterior corneal surface and the z-axis [11].
- PAD: posterior apex deviation, which is the minimum mean distance between the point of maximum curvature of the posterior corneal surface and the z-axis [11].
2.5. Statistical Analysis
3. Results
4. Discussion
Author Contributions
Funding
Conflicts of Interest
References
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Mean (SD) Median (Range) | Preoperative | 3 Months Postop | 6 Months Postop | p-Value |
---|---|---|---|---|
LogMAR UDVA | 0.66 (0.58) 0.52 (0.01 to 2.00) | 0.56 (0.51) 0.40 (0.10 to 2.00) | 0.66 (0.68) 0.38 (0.00 to 2.00) | 0.449 |
Manifest sphere (D) | −0.75 (2.48) 0.00 (−6.25 to 3.75) | −0.40 (2.57) 0.00 (−6.50 to 3.25) | −1.41 (2.80) −0.75 (−6.50 to 1.25) | 0.949 |
Manifest cylinder (D) | −2.97 (2.00) −2.25 (−9.00 to −0.50) | −2.63 (1.35) −2.50 (−4.75 to 0.00) | −2.59 (1.06) −3.00 (−4.75 to −1.00) | 0.465 |
Manifest SE (D) | −2.24 (2.47) −2.25 (−7.00 to 2.88) | −1.72 (2.48) −1.38 (−7.50 to 2.50) | −2.70 (2.61) −2.13 (−7.50 to 0.75) | 0.538 |
LogMAR CDVA | 0.09 (0.09) 0.09 (−0.04 to 0.30) | 0.12 (0.11) 0.10 (0.00 to 0.32) | 0.10 (0.11) 0.02 (0.00 to 0.28) | 0.438 |
CCT (µm) | 496.42 (34.99) 495.00 (444 to 564) | 461.92 (36.82) 463.00 (414 to 520) | 468.73 (46.69) 484.00 (377 to 531) | 0.006 Preop—3 months 0.006 3–6 months 0.084 Preop—6 months 0.024 |
KM (D) | 45.44 (2.00) 44.88 (42.16 to 48.82) | 44.36 (3.01) 43.51 (39.49 to 49.26) | 45.47 (2.80) 45.62 (41.40 to 50.27) | 0.311 |
Q45 | −0.58 (0.79) −0.39 (−2.00 to 0.51) | −0.96 (0.84) −1.08 (−2.17 to 0.36) | −0.81 (1.17) −0.40 (−2.91 to 1.12) | 0.846 |
Q8 | −0.67 (0.32) −0.68 (−1.35 to −0.16) | −0.69 (0.47) −0.81 (−1.13 to 0.51) | −0.63 (0.38) −0.51 (−1.37 to −0.17) | 0.115 |
Total RMS (µm) | 4.92 (3.73) 4.13 (1.07 to 14.39) | 3.65 (1.48) 4.09 (1.25 to 6.20) | 4.45 (3.27) 4.33 (1.04 to 13.65) | 0.115 |
Astigmatism RMS (µm) | 2.74 (1.14) 2.91 (0.78 to 4.53) | 2.69 (1.17) 2.47 (0.73 to 4.14) | 2.68 (1.34) 3.04 (0.78 to 4.88) | 0.135 |
Primary spherical aberration (µm) | 0.02 (0.36) 0.04 (−0.53 to 0.56) | −0.10 (0.30) −0.06 (−0.61 to 0.36) | 0.15 (0.37) 0.12 (−0.52 to 0.78) | 0.311 |
Primary coma RMS (µm) | 1.64 (0.97) 1.49 (0.26 to 3.71) | 1.21 (0.95) 0.98 (0.04 to 3.05) | 1.53 (1.04) 1.45 (0.12 to 3.33) | 0.223 |
Spherical-like RMS (µm) | 0.75 (0.36) 0.64 (0.23 to 1.51) | 0.67 (0.36) 0.57 (0.27 to 1.36) | 0.84 (0.47) 0.77 (0.18 to 1.65) | 0.030 Preop—3 months 0.015 3–6 months 0.084 Preop—6 months 0.722 |
Coma-like RMS (µm) | 1.85 (1.00) 1.60 (0.38 to 3.98) | 1.65 (0.86) 1.41 (0.43 to 3.19) | 1.86 (0.88) 1.87 (0.59 to 3.05) | 0.057 |
Mean (SD) Median (Range) | Preoperative | 3 Months Postop | 6 Months Postop | p-Value |
---|---|---|---|---|
Aant (mm2) | 43.27 (0.26) 43.22 (42.93 to 43.81) | 43.16 (0.27) 43.08 (42.85 to 43.79) | 43.24 (0.32) 43.15 (42.83 to 43.75) | 0.205 |
Apost (mm2) | 44.60 (0.51) 44.41 (43.94 to 45.64) | 44.56 (0.57) 44.30 (44.00 to 45.83) | 44.72 (0.48) 44.49 (44.24 to 45.71) | 0.338 |
Atot (mm2) | 104.07 (2.00) 103.50 (100.97 to 107.68) | 102.98 (2.26) 102.59 (100.30 to 106.79) | 103.87 (1.81) 102.95 (101.37 to 106.77) | 0.001 Preop—3 months 0.006 3–6 months 0.999 Preop—6 months 0.003 |
CV (mm3) | 24.61 (1.95) 24.16 (21.38 to 27.97) | 22.65 (1.91) 22.81 (20.37 to 26.32) | 23.62 (1.89) 23.28 (19.70 to 26.87) | <0.001 Preop—3 months <0.001 3–6 months 0.816 Preop—6 months 0.003 |
AAD (mm) | 0.0098 (0.0091) 0.0080 (0.0000 to 0.0400) | 0.0084 (0.0066) 0.0068 (0.0000 to 0.0200) | 0.0113 (0.0139) 0.0061 (0.000 to 0.0500) | 0.779 |
PAD (mm) | 0.21 (0.09) 0.17 (0.10 to 0.39) | 0.23 (0.11) 0.20 (0.10 to 0.51) | 0.26 (0.13) 0.28 (0.09 to 0.45) | 0.076 |
AMTPD (mm) | 1.04 (0.30) 1.03 (0.60 to 1.75) | 1.14 (0.39) 1.22 (0.30 to 1.93) | 1.28 (0.41) 1.29 (0.66 to 2.18) | 0.717 |
PMTPD (mm) | 0.97 (0.27) 0.94 (0.58 to 1.62) | 1.08 (0.37) 1.16 (0.26 to 1.86) | 1.19 (0.41) 1.20 (0.60 to 2.08) | 0.717 |
Mean (SD) Median (Range) | Preoperative | 3 Months Postop | 6 Months Postop | p-Value |
---|---|---|---|---|
VOLmct (mm3) | ||||
Radius | ||||
0.1 mm | 0.015 (0.001) 0.015 (0.014–0.017) | 0.013 (0.001) 0.013 (0.011–0.015) | 0.014 (0.002) 0.014 (0.010–0.016) | 0.002 |
0.2 mm | 0.060 (0.004) 0.060 (0.054–0.069) | 0.054 (0.005) 0.053 (0.043–0.060) | 0.054 (0.007) 0.056 (0.042–0.063) | 0.002 |
0.3 mm | 0.134 (0.087) 0.134 (0.122–0.156) | 0.121 (0.012) 0.120 (0.098–0.136) | 0.122 (0.015) 0.126 (0.095–0.142) | 0.002 |
0.4 mm | 0.241 (0.016) 0.239 (0.217–0.279) | 0.216 (0.021) 0.214 (0.176–0.243) | 0.219 (0.026) 0.225 (0.170–0.253) | 0.002 |
0.5 mm | 0.377 (0.024) 0.374 (0.340–0.437) | 0.335 (0.034) 0.323 (0.277–0.381) | 0.344 (0.040) 0.353 (0.268–0.397) | 0.002 |
0.6 mm | 0.545 (0.035) 0.541 (0.491–0.631) | 0.490 (0.047) 0.485 (0.403–0.551) | 0.497 (0.057) 0.510 (0.391–0.574) | 0.002 |
0.7 mm | 0.745 (0.049) 0.738 (0.670–0.862) | 0.670 (0.064) 0.664 (0.555–0.753) | 0.680 (0.078) 0.697 (0.539–0.784) | 0.002 |
0.8 mm | 0.977 (0.064) 0.968 (0.877–1.130) | 0.880 (0.083) 0.871 (0.734–0.988) | 0.894 (0.100) 0.914 (0.709–1.030) | 0.002 |
0.9 mm | 1.243 (0.082) 1.230 (1.112–1.435) | 1.121 (0.104) 1.109 (0.941–1.256) | 1.139 (0.126) 1.162 (0.905–1.310) | 0.002 |
1.0 mm | 1.542 (0.103) 1.526 (1.378–1.779) | 1.392 (0.126) 1.376 (1.179–1.557) | 1.416 (0.154) 1.441 (1.128–1.626) | 0.002 |
1.1 mm | 1.877 (0.127) 1.855 (1.675–2.163) | 1.694 (0.151) 1.675 (1.449–1.891) | 1.725 (0.185) 1.753 (1.378–1.979) | 0.002 |
1.2 mm | 2.248 (0.153) 2.221 (2.000–2.588) | 2.030 (0.178) 2.004 (1.750–2.265) | 2.070 (0.218) 2.097 (1.653–2.371) | 0.002 |
1.3 mm | 2.655 (0.183) 2.623 (2.357–3.052) | 2.400 (0.206) 2.371 (2.085–2.685) | 2.449 (0.254) 2.477 (1.961–2.802) | 0.001 |
1.4 mm | 3.100 (0.215) 3.063 (2.747–3.558) | 2.803 (0.237) 2.769 (2.458–3.145) | 2.863 (0.292) 2.900 (2.297–3.267) | <0.001 |
1.5 mm | 3.585 (0.251) 3.542 (3.168–4.109) | 3.241 (0.269) 3.204 (2.873–3.647) | 3.317 (0.331) 3.369 (2.668–3.778) | <0.001 |
VOLaap (mm3) | ||||
Radius | ||||
0.1 mm | 0.016 (0.001) 0.016 (0.014–0.018) | 0.014 (0.001) 0.014 (0.012–0.016) | 0.014 (0.004) 0.015 (0.000–0.017) | <0.001 |
0.2 mm | 0.062 (0.004) 0.062 (0.056–0.071) | 0.057 (0.005) 0.057 (0.047–0.064) | 0.059 (0.006) 0.060 (0.047–0.067) | <0.001 |
0.3 mm | 0.140 (0.010) 0.140 (0.125–0.160) | 0.128 (0.011) 0.129 (0.107–0.144) | 0.132 (0.014) 0.135 (0.105–0.150) | <0.001 |
0.4 mm | 0.250 (0.017) 0.249 (0.223–0.284) | 0.228 (0.019) 0.229 (0.191–0.256) | 0.234 (0.024) 0.240 (0.188–0.268) | <0.001 |
0.5 mm | 0.391 (0.027) 0.390 (0.349–0.445) | 0.356 (0.030) 0.358 (0.300–0.401) | 0.367 (0.037) 0.375 (0.296–0.419) | <0.001 |
0.6 mm | 0.565 (0.039) 0.562 (0.503–0.643) | 0.514 (0.042) 0.515 (0.435–0.578) | 0.530 (0.053) 0.541 (0.430–0.604) | <0.001 |
0.7 mm | 0.770 (0.053) 0.767 (0.685–0.877) | 0.701 (0.057) 0.700 (0.597–0.789) | 0.722 (0.073) 0.737 (0.589–0.825) | <0.001 |
0.8 mm | 1.008 (0.069) 1.004 (0.897–1.149) | 0.917 (0.074) 0.914 (0.786–1.033) | 0.946 (0.094) 0.965 (0.774–1.080) | <0.001 |
0.9 mm | 1.280 (0.088) 1.274 (1.137–1.459) | 1.164 (0.093) 1.157 (1.005–1.312) | 1.201 (0.119) 1.222 (0.982–1.371) | <0.001 |
1.0 mm | 1.585 (0.109) 1.578 (1.406–1.807) | 1.441 (0.114) 1.430 (1.253–1.624) | 1.488 (0.147) 1.512 (1.215–1.699) | <0.001 |
1.1 mm | 1.925 (0.133) 1.916 (1.705–2.195) | 1.750 (0.137) 1.732 (1.533–1.974) | 1.807 (0.177) 1.834 (1.476–2.066) | <0.001 |
1.2 mm | 2.300 (0.159) 2.288 (2.034–2.624) | 2.089 (0.163) 2.062 (1.842–2.362) | 2.158 (0.211) 2.187 (1.759–2.466) | <0.001 |
1.3 mm | 2.710 (0.188) 2.695 (2.394–3.094) | 2.461 (0.190) 2.424 (2.184–2.784) | 2.544 (0.247) 2.574 (2.071–2.906) | <0.001 |
1.4 mm | 3.156 (0.220) 3.140 (2.784–3.604) | 2.867 (0.218) 2.821 (2.562–3.242) | 2.965 (0.286) 2.996 (2.407–3.392) | <0.001 |
1.5 mm | 3.642 (0.255) 3.621 (3.206–4.158) | 3.308 (0.248) 3.251 (2.984–3.743) | 3.422 (0.328) 3.453 (2.779–3.922) | 0.001 |
VOLpap (mm3) | ||||
Radius | ||||
0.1 mm | 0.015 (0.001) 0.015 (0.014–0.018) | 0.014 (0.001) 0.014 (0.011–0.016) | 0.014 (0.015) 0.014 (0.011–0.016) | <0.001 |
0.2 mm | 0.062 (0.004) 0.062 (0.056–0.070) | 0.056 (0.005) 0.056 (0.045–0.062) | 0.057 (0.006) 0.058 (0.044–0.065) | <0.001 |
0.3 mm | 0.139 (0.009) 0.140 (0.125–0.159) | 0.125 (0.011) 0.125 (0.102–0.140) | 0.129 (0.014) 0.131 (0.099–1.467) | <0.001 |
0.4 mm | 0.247 (0.016) 0.248 (0.222–0.282) | 0.223 (0.020) 0.221 (0.182–0.249) | 0.229 (0.024) 0.233 (0.178–0.261) | <0.001 |
0.5 mm | 0.386 (0.025) 0.389 (0.348–0.442) | 0.350 (0.031) 0.346 (0.286–0.389) | 0.359 (0.037) 0.365 (0.280–0.409) | 0.002 |
0.6 mm | 0.557 (0.037) 0.561 (0.501–0.638) | 0.505 (0.045) 0.499 (0.416–0.561) | 0.518 (0.053) 0.527 (0.407–0.591) | 0.002 |
0.7 mm | 0.761 (0.050) 0.765 (0.682–0.870) | 0.690 (0.061) 0.681 (0.572–0.767) | 0.707 (0.073) 0.722 (0.560–0.807) | 0.002 |
0.8 mm | 0.997 (0.066) 1.001 (0.893–1.141) | 0.904 (0.078) 0.892 (0.755–1.006) | 0.927 (0.094) 0.949 (0.740–1.057) | 0.002 |
0.9 mm | 1.267 (0.084) 1.271 (1.133–1.449) | 1.148 (0.098) 1.132 (0.966–1.280) | 1.178 (0.120) 1.209 (0.949–1.344) | 0.001 |
1.0 mm | 1.570 (0.105) 1.574 (1.401–1.795) | 1.423 (0.120) 1.403 (1.207–1.588) | 1.461 (0.147) 1.504 (1.186–1.667) | 0.001 |
1.1 mm | 1.908 (0.128) 1.911 (1.670–2.181) | 1.729 (0.143) 1.704 (1.479–1.933) | 1.776 (0.178) 1.828 (1.454–2.027) | 0.001 |
1.2 mm | 2.281 (0.154) 2.283 (2.027–2.608) | 2.067 (0.169) 2.037 (1.785–2.315) | 2.124 (0.211) 2.180 (1.749–2.424) | 0.001 |
1.3 mm | 2.690 (0.182) 2.690 (2.385–3.075) | 2.438 (0.196) 2.401 (2.121–2.733) | 2.507 (0.246) 2.567 (2.062–2.862) | 0.001 |
1.4 mm | 3.136 (0.214) 3.133 (2.774–3.586) | 2.842 (0.225) 2.797 (2.492–3.186) | 2.926 (0.283) 2.989 (2.402–3.334) | 0.001 |
1.5 mm | 3.620 (0.250) 3.614 (3.196–4.138) | 3.280 (0.256) 3.228 (2.911–3.683) | 3.379 (0.328) 3.445 (2.765–3.854) | 0.001 |
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Alifa, R.; Piñero, D.; Velázquez, J.; Alió del Barrio, J.L.; Cavas, F.; Alió, J.L. Changes in the 3D Corneal Structure and Morphogeometric Properties in Keratoconus after Corneal Collagen Crosslinking. Diagnostics 2020, 10, 397. https://doi.org/10.3390/diagnostics10060397
Alifa R, Piñero D, Velázquez J, Alió del Barrio JL, Cavas F, Alió JL. Changes in the 3D Corneal Structure and Morphogeometric Properties in Keratoconus after Corneal Collagen Crosslinking. Diagnostics. 2020; 10(6):397. https://doi.org/10.3390/diagnostics10060397
Chicago/Turabian StyleAlifa, Ramón, David Piñero, José Velázquez, Jorge L. Alió del Barrio, Francisco Cavas, and Jorge L. Alió. 2020. "Changes in the 3D Corneal Structure and Morphogeometric Properties in Keratoconus after Corneal Collagen Crosslinking" Diagnostics 10, no. 6: 397. https://doi.org/10.3390/diagnostics10060397