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

Vol. 31 No. 1 (2024)
Submitted: 26 February 2024
Accepted: 15 April 2024
Published: 24 April 2024
Keratorefractive lenticule extraction (KLEx), LASIK, myopia, biomechanics, optical coherence tomography (OCT)
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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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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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