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Histopathology of Corneal Lenticules Obtained from Small Incision Lenticule Extraction (SMILE) versus Microkeratome
Salwa Abdelkawi Ahmed1, Ibrahim Mohi Eldin Taher2, Dina Fouad Ghoneim2
1Department of Vision Science, Biophysics and Laser Science Unit, Research Institute of Ophthalmology, Giza, Egypt.
Journal of Ophthalmic & Vision Research
|March 20, 2023
Summary
Femtosecond small incision lenticule extraction (SMILE) causes more corneal structural and DNA damage than microkeratome cutting. Careful management of laser parameters is crucial for femtosecond SMILE to minimize corneal alterations.
Area of Science:
- Ophthalmology
- Biomedical Engineering
- Corneal Surgery
Background:
- Small Incision Lenticule Extraction (SMILE) is a refractive surgery technique.
- Understanding the cellular and molecular impact of SMILE is crucial for patient safety.
- Comparing SMILE with traditional microkeratome techniques provides insights into tissue alteration.
Purpose of the Study:
- To compare the histological and molecular alterations in lenticules extracted via femtosecond (Femto) SMILE versus corneal caps created by a microkeratome.
- To evaluate the extent of DNA damage and protein structure changes induced by each method.
Main Methods:
- Human cadaveric corneas were used.
- Lenticules from Femto SMILE and microkeratome caps were analyzed using light and transmission electron microscopy (TEM).
- DNA fragmentation (agarose gel electrophoresis), DNA damage (comet assay), and protein secondary structure (FTIR spectroscopy) were assessed.
Main Results:
- Femto SMILE resulted in more stromal edema (101.6% increase) compared to microkeratome.
- TEM revealed pyknotic keratocytes, disrupted collagen, and cavitation in Femto SMILE lenticules.
- Femto SMILE showed increased DNA fragmentation, a higher percentage of tailed cells (8.0% vs 3%), and greater DNA damage indicators (tail length, % tail DNA, tail moment) compared to microkeratome.
Conclusions:
- Femto SMILE induces more significant structural, DNA, and protein alterations in corneal tissue than microkeratome cutting.
- These changes may be due to the high energy levels and deep penetration of the laser in Femto SMILE.
- Findings underscore the importance of optimizing laser parameters in Femto SMILE to mitigate corneal impact.
