Original Research Articles
Vol. 31 No. 1 (2024)
https://doi.org/10.4081/ltj.2024.392

Biomechanical changes after keratorefractive lenticule extraction with CLEAR and after femtosecond LASIK, correlated with optical coherence tomography findings

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Received: 26 February 2024
Accepted: 15 April 2024
Published: 24 April 2024
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Keratorefractive lenticule extraction (KLEx), LASIK, myopia, biomechanics, optical coherence tomography (OCT)

Authors

Antonio Leccisotti
leccisotti@libero.it
https://orcid.org/0000-0001-9953-0535
Siena Eye Laser, Poggibonsi, Siena, Italy; School of Biomedical Sciences, Ulster University, Coleraine, UK; Centre for Research in Refractive Surgery, Siena, Italy.
Stefania V. Fields
Siena Eye Laser, Poggibonsi, Siena, Italy; Centre for Research in Refractive Surgery, Siena, Italy.
Giuseppe De Bartolo
Siena Eye Laser, Poggibonsi, Siena, Italy; Centre for Research in Refractive Surgery, Siena, Italy.
Christian Crudale
https://orcid.org/0009-0006-4002-1481
Siena Eye Laser, Poggibonsi, Siena, Italy; Centre for Research in Refractive Surgery, Siena, Italy.
Matteo Posarelli
Siena Eye Laser, Poggibonsi, Siena, Italy; Centre for Research in Refractive Surgery, Siena, Italy; Liverpool University, United Kingdom.
Alex Malandrini
Siena Eye Laser, Poggibonsi, Siena, Italy; Centre for Research in Refractive Surgery, Siena, Italy; Università di Siena, Italy.

The aim of this retrospective, comparative, single-eye study was to assess the biomechanical changes after laser correction of myopia by keratorefractive lenticule extraction (KLEx) and by femtosecond LASIK (FS-LASIK), correlating them with the stromal changes on anterior segment optical coherence tomography. Corneal biomechanical parameters, provided by the high-speed Scheimpflug camera CorVis-ST (Oculus Optikgeräte GmbH) and measured pre-operatively and 1 week post-operatively, were: stiffness parameter at first applanation (SP-A1), stress-strain index (SSI), inverse integrated radius (IIR), deformation amplitude ratio at 2 mm (DA ratio-2mm).

A total of 79 eyes undergone KLEx (CLEAR, Ziemer Group) and 93 eyes undergone FS-LASIK were included. The mean residual stromal bed (RSB) was 271.36±17.22 µm after KLEx and 304.21±21.82 µm after FS-LASIK (p=0.00). All parameters in both groups showed statistically significant post-operative changes (p=0.00), except for SSI after FS-LASIK (p=0.39). The percent changes in all parameters were significantly higher in the KLEx group. Even in the eyes with equal RSB (300±5 µm; 19 eyes post-KLEx, 26 eyes post-FS-LASIK), changes were significantly higher after KLEx (SP-A1: -35.9%; SSI: -6.7%) than after FS-LASIK (SP-A1: -29.6%; SSI: -3.8%) (respectively, p=0.02, and p=0.00). In KLEx, reduction in stromal thickness had a weak correlation with reduction in SP-A1 (r=0.39), and poor correlation with reduction in SSI (r=0.26).

In conclusion, stiffness parameters were significantly worse after KLEx than after FS-LASIK, even in eyes ending with similar RSB. These findings should be valued cautiously, as the CorVis-ST might not capture all the clinically significant alterations, especially in the post-KLEx bi-layered cornea.

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Citations

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Ethics Approval

The study has been granted an exemption from requiring ethics approval by the Institutional Review Board at Siena Eye Laser. Ethical approval is not required for this study in accordance with national guidelines. All patients provided informed consent to participate.

CRediT authorship contribution

Antonio Leccisotti, Stefania V. Fields: conceptualization, writing – original draft; Giuseppe De Bartolo, Matteo Posarelli: data analysis, writing – review & editing; Christian Crudale, Alex Malandrini: conceptualization, data analysis. All authors read and approved the final version of the manuscript and agreed to be accountable for all aspects of the work.

Data Availability Statement

All data generated or analyzed during the study are available upon request from the corresponding author.

How to Cite



Leccisotti, A., Fields, S. V., De Bartolo, G., Crudale, C., Posarelli, M., & Malandrini, A. (2024). Biomechanical changes after keratorefractive lenticule extraction with CLEAR and after femtosecond LASIK, correlated with optical coherence tomography findings. Laser Therapy, 31(1). https://doi.org/10.4081/ltj.2024.392
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