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Finite element modeling of circular keratotomy in the normal, astigmatic, and keratoconic cornea

Purpose: The purpose is to evaluate the effect of a circular relaxing incision (circular keratotomy [CK]) on corneal biomechanics using finite element analysis (FEA) of in silico models of a spherical comea, comea with astigmatism, and cornea with keratoconus. Methods: Computer-aided design software...

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Published in:CLEVER Clinical and Experimental Vision and Eye Research 2023-01, Vol.6 (1), p.3-7
Main Authors: Nahum, Yoav, Madhian, Stav, Bondarenko, Alexander, Ron, Amit, Goldenberg, Yair, Brand, Moshe
Format: Article
Language:English
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Summary:Purpose: The purpose is to evaluate the effect of a circular relaxing incision (circular keratotomy [CK]) on corneal biomechanics using finite element analysis (FEA) of in silico models of a spherical comea, comea with astigmatism, and cornea with keratoconus. Methods: Computer-aided design software and published biomechanical models were used to create a theoretical 3D model of a normal and a keratoconic human cornea. Abaqus FEA software was used to evaluate changes caused by circular incisions performed at different depths and diameters, radial and perpendicular to the corneal surface. To evaluate changes in refractive power, the radii of curvature at the central 3 mm of the cornea were calculated using a Python-based code (Supplemental File 1). Results: Circular incisions caused flattening of the cornea, which increased when the incisions were deeper and closer to the center. Maximal flattening of 2.75D was demonstrated with an incision of 450 µm depth and 6 mm diameter. A similar incision applied to a keratoconic corneal model with normal elastic properties caused flattening of 7.7D, which increased to 12.25D (from 50.25D to 38D) when Young's modulus was decreased to 30% of baseline, changing the elastic properties. In both models, flattening increased when incisions were made radial rather than perpendicular to the corneal surface. In a cornea with regular astigmatism of 7.89D, a similar incision caused flattening of both flat and steep meridians, with a decrease in astigmatism of 1.1D and 1.6D at diameters of 3 mm and 6 mm, respectively. Conclusion: FEA demonstrated that CK could flatten both regular and ectatic comeas.
ISSN:2581-656X
DOI:10.15713/ins.clever.96