PEER-REVIEWED PUBLICATION

2023

Patient-Specific Finite Element Analysis of Human Corneal Lenticules: An Experimental and Numerical Study

Nambiar MH, Liechti L, et al.

Journal of the Mechanical Behavior of Biomedical Materials

University of Bern, Optimo Medical, Narayana Nethralaya Eye Clinic, IROC AG, Inselspital Bern, University Hospital Düsseldorf

Germany, India, Switzerland

RESEARCH SUMMARY

This study combines experimental uniaxial testing and finite element modeling to characterize the mechanical properties of human corneal lenticules extracted from patients undergoing refractive surgery (CLEAR procedure). Samples from five patients (ages 27–30) were analyzed to derive anisotropic hyperelastic parameters describing the anterior stroma. Using patient-specific geometries reconstructed from Pentacam corneal topography, the researchers developed a numerical model accounting for realistic collagen fiber dispersion and non-uniform thickness. The model successfully reproduced experimental force–displacement behavior, providing accurate constitutive parameters (C10 = 24.05 kPa, k1 = 4.98 MPa, k2 = 40.34) that reflect the mechanical response of young human corneas and improve predictive accuracy in refractive surgery simulations.

Mechanical testing was conducted using the CellScale UStretch equipped with BioRake attachments (three tines, 0.25 mm diameter) for uniaxial tensile tests on freshly excised corneal lenticules. Samples were submerged in MEM + 5% Dextran medium at room temperature to maintain hydration and preloaded to 10 mN before testing. Five preconditioning cycles of 10% strain at 0.007 mm/s were applied, and the fifth cycle was used for material parameter fitting (Fig. 4, p. 4). The UStretch recorded force–displacement data with high precision, enabling derivation of strain-dependent moduli and validation of the anisotropic Holzapfel–Gasser–Ogden model for corneal tissue.

AUTHORS

Malavika H. Nambiar, Layko Liechti, Harald Studer, Abhijit S. Roy, Theo G. Seiler, Philippe Büchler.

PUBLICATION DETAILS

JOURNAL

Journal of the Mechanical Behavior of Biomedical Materials

YEAR

2023

INSTITUTIONS

University of Bern, Optimo Medical, Narayana Nethralaya Eye Clinic, IROC AG, Inselspital Bern, University Hospital Düsseldorf

COUNTRIES

Germany, India, Switzerland

INSTRUMENT USED

UStretch

TESTING METHODS

Hydrated and Temperature Controlled TestingTensile Testing

RESEARCH APPLICATIONS

ECM & Decellularized Matrix MechanicsMechanotransductionOphthalmic Biomechanics & Corneal Tissue Engineering

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