Piezoelectric and mechanical properties in bovine cornea

Abstract

The piezoelectric coefficient (d(31)) and Young's modulus (E) were investigated as a function of degree of hydration for bovine cornea. The piezoelectric and mechanical responses observed were anisotropic, and d(31) decreased, whereas E increased with decreasing the degree of hydration. The anisotropic mechanical and electromechanical properties observed seem to be caused by oriented crystalline collagen fibrils. In addition, the loss of water molecules appears to decrease crystallinity (of the collagen) in the cornea. With dehydration of the cornea, a reduction in crystallinity and changes in hydrogen bonding were observed by wide-angle X-ray diffraction and Fourier transform infrared measurements. The decrease of piezoelectricity in cornea during dehydration is most likely caused by the increase in modulus and the loss of order to a nonpiezoelectric phase in the collagen.

Collagen Cross-Linking Using Rose Bengal and Green Light to Increase Corneal Stiffness

“…37 Riboflavin/dextran application substantially decreases the stromal thickness 8,38 due to dehydration, which is also known to increase corneal stiffness. 39 The mechanism for protein-protein cross-linking by RGX is initiated by light absorption by RB molecules, which are promoted to excited singlet, then excited triplet states. When sufficient oxygen is present, the RB triplet state transfers energy to oxygen, generating singlet oxygen.…”

Corneal collagen—its role in maintaining corneal shape and transparency

“…Diameters also increase from central to peripheral cornea in most species, although in this case the volume fraction changes (Boote et al 2003). These differences probably relate to the biomechanical properties of the corneas (Parry et al 1978;Jayasuriya et al 2003;Meek 2008). The fibril volume fraction has a significant effect on the mechanical strength of a connective tissue (Boote et al 2003;Goh et al 2008).…”

Determining the effect of hydration upon the properties of ligaments using pseudo Gaussian stress stimuli

“…For example, dehydration of rat tail tendons resulted in an increase in stiffness and elimination of the toe region of the stress-strain curve (Betsch and Baer, 1980). Decreasing the hydration of the cornea resulted in an increase in stiffness (Jayasuriya et al, 2003). The effect of hydration upon the viscoelastic properties has also been demonstrated.…”