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31. Kongress der Deutschsprachigen Gesellschaft für Intraokularlinsen-Implantation, Interventionelle und Refraktive Chirurgie (DGII)

Deutschsprachige Gesellschaft für Intraokularlinsen-Implantation, Interventionelle und Refraktive Chirurgie (DGII) (DGII)

16.02. - 18.02.2017, Dortmund

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Biomechanical analysis of different retreatment options after SMILE refractive surgery

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  • Bogdan Spiru - Marburg
  • S. Kling - Laboratory of Ocular Cell Biology, Center for Applied Biotechnology and Molecular Medicine, Universität Zürich, Switzerland
  • F. Hafezi - Dietikon-Zurich, Switzerland; University of Southern California, Los Angeles, USA
  • W. Sekundo - Marburg

Deutschsprachige Gesellschaft für Intraokularlinsen-Implantation, Interventionelle und Refraktive Chirurgie. 31. Kongress der Deutschsprachigen Gesellschaft für Intraokularlinsen-Implantation, Interventionelle und Refraktive Chirurgie (DGII). Dortmund, 16.-18.02.2017. Düsseldorf: German Medical Science GMS Publishing House; 2017. Doc17dgii046

doi: 10.3205/17dgii046, urn:nbn:de:0183-17dgii0466

Published: February 15, 2017

© 2017 Spiru et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. See license information at http://creativecommons.org/licenses/by/4.0/.

Outline

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Purpose: To determine the corneal weakening induced by different re-treatment options after SmILE, and to investigate the potential of corneal cross-linking (CXL) to re-establish the original corneal stress resistance.

Methods: A total of 96 freshly enucleated porcine corneas were used. The initial refractive correction was defined to be -11D and the required enhancement to be -3D. Three different retreatment options were analyzed: (i) -3D Re-SmILE, (ii) -3D PRK on top of the SmILE cap and (iii) cap-to-flap conversion and -3D excimer ablation on the stromal bed (“LASIK”). The (iv) control condition did not receive any treatment. Subsequently, accelerated CXL (9mW/cm2, 10min) was performed in two groups with currently common enhancement techniques: (v) following cap-to-flap conversion (-3D “LASIK” enhancement) and (vi) in controls. Biomechanical properties were measured with stress-strain extensometry in the range from 1.27 to 12.5N.

Results: The Re-SmILE and PRK enhancement did not significantly reduce the overall elastic modulus of the cornea compared to controls (24.7 Mpa and 22.7 Mpa versus 23.8 Mpa, p=0.176), while LASIK enhancement did (22.2 Mpa, p=0.048). CXL treatment significantly increased the elastic modulus compared to all non-cross-linked conditions (p 0.001). Refractive surgery decreased the overall elastic modulus by 7%, while CXL increased it by 20%.

Conclusions: In enhancement, the corneal biomechanical integrity is less affected with both, Re-SMILE and PRK enhancement. Corneal weakening through laser refractive surgery is small compared to the stiffening effect after CXL.