Investigation of Overall Corneal Stiffness Based on Whole Corneal Stroma Constitutive Model and Corvis ST Test

Abstract

To investigate the impact factors on the overall corneal stiffness, a modified whole corneal stroma constitutive model with explicit physical meaning was utilized to describe the microstructural characteristics and biomechanical properties of the stroma. By constructing a detailed three-dimensional finite element model of the cornea, precise finite element simulations of Corvis ST tests can be realized. The rationality of the constitutive model and simulation results were validated by statistical data from clinical Corvis ST tests on 70 young myopic specimens. Subsequently, the factors and patterns affecting the overall corneal stiffness were analyzed by varying stiffness parameters and collagen fibril crimping morphology parameters within the model. The results indicate that, under physiological intraocular pressure of 16mmHg and during Corvis ST test, the overall corneal stiffness in young myopic individuals is predominantly provided by the non-collagenous matrix, with collagen fibrils mostly remaining in a crimping state and making a minor contribution to the overall load-bearing capacity of the cornea. Conversely, the crimping morphology of collagen fibrils significantly impacts the overall corneal stiffness. Which further elucidates the crucial relationship between corneal microstructure and its biomechanical properties. These results possess instructive significance for understanding the physical meaning of dynamic corneal response parameters and hold driving value for further exploration of the microstructural characteristics of the whole cornea.

Note:
Funding Declaration: This work is supported by the National Natural Science Foundation of China (Grants Nos. 82271118, 81670884, and 10972155)

Conflicts of Interest: None.

Ethical Approval: The research was approved by the Ethics Committee of Tianjin Eye Hospital (2022027) and adhered to the tenets of the Declaration of Helsinki.

Keywords: overall corneal stiffness, hyperelastic property, Corvis ST test, whole corneal stroma constitutive model, finite elements method