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Abdelkawi Ahmed S, Mohi Eldin Taher I, Fouad Ghoneim D, Ahmed Elnaggar M, Ahmed Hassan A. Histopathology of Corneal Lenticules Obtained from Small Incision Lenticule Extraction (SMILE) versus Microkeratome Excision. JOVR [Internet]. 2023Feb.13 [cited 2024May2];18(1):24–33. Available from: https://knepublishing.com/index.php/JOVR/article/view/12722

https://doi.org/10.18502/jovr.v18i1.12722

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authors

  • Salwa Abdelkawi Ahmed

    Salwa Abdelkawi Ahmed

    PhD. Department of Vision Science, Biophysics and Laser Science Unit, Research Institute of Ophthalmology, Giza 12511, Egypt.
  • Ibrahim Mohi Eldin Taher

    Ibrahim Mohi Eldin Taher

    Ophthalmic Unit, National Institute of Laser Enhanced Science, Cairo University, Egypt
  • Dina Fouad Ghoneim

    Dina Fouad Ghoneim

    Ophthalmic Unit, National Institute of Laser Enhanced Science, Cairo University, Egypt
  • Mohammed Ahmed Elnaggar

    Mohammed Ahmed Elnaggar

    Ophthalmic Unit, National Institute of Laser Enhanced Science, Cairo University, Egypt
  • Aziza Ahmed Hassan

    Aziza Ahmed Hassan

    Ophthalmic Unit, National Institute of Laser Enhanced Science, Cairo University, Egypt

Published Date

  • Feb 13, 2023
This journal is publishing all the articles under Creative Commons Attribution License CC BY 4.0.

Histopathology of Corneal Lenticules Obtained from Small Incision Lenticule Extraction (SMILE) versus Microkeratome Excision

Journal of Ophthalmic and Vision Research (JOVR) / Jan–Mar 2023, Volume 18, Issue 1 / Pages 24–33

Abstract

Purpose: To study the alterations on the lenticules extracted after femtosecond (Femto) small incision lenticule extraction (SMILE) versus the corneal free cap removed using a microkeratome.
Methods: The visuMax (500 kHz; laser energy: 180 nJ) was used for small-incision lenticule extraction. Free caps from human cadaveric corneas were excised by microkeratome. The collected lenticules were examined with the light and transmission electron microscope (TEM) for histological analysis, DNA fragmentation was assessed by agarose gel electrophoresis, DNA damage was evaluated using comet assay, and corneal proteins secondary structure was assessed by Fourier transform infrared spectroscopy (FTIR).
Results: Light microscopic examination showed the presence of more edematous stroma under Femto SMILE than under free cap with a percentage change of 101.6%. In the Femto SMILE group, TEM examination showed pyknotic keratocytes, disruption, and cavitation of the collagen arrays stromal area under Femto SMILE. The DNA fragmentation for the Femto SMILE group revealed one undefined band with a size of 1.1 Kbp. The comet assay analysis indicated the presence of 3% and 8.0% tailed cells for the free cap and Femto SMILE groups, respectively. The tail lengths were 1.33 ± 0.16 and 1.67 ± 0.13 μm (P < 0.01), the percentage of tail DNA was 1.41 ± 0.18% (P < 0.01) and 1.72 ± 0.15%, and the tail moments were 1.88 ± 0.12 AU and 2.87 ± 0.14 AU (P < 0.001) for the free cap and Femto SMILE groups, respectively. FTIR spectroscopy of the Femto smile group revealed disorders in the secondary and tertiary structure of the proteins.
Conclusion: Femto SMILE technique induced more structural changes, DNA fragmentation, DNA damage, and corneal proteins secondary structure alteration than those induced by a microkeratome cutting. These changes may be attributed to the deep penetration of high energy levels to the corneal layer. These findings may highlight the potential impact of the Femto SMILE on the cornea and the necessity for managing the laser parameters used.

Keywords:

Comet Assay, DNA Fragmentation, Femto SMILE, Fourier Transform Infrared Spectroscopy, Histological Analysis

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