Micro-scale Stiffness Change of Cornea Tissues Suffered from Elevated Intraocular Pressure Investigated by Nanoindentation

Abstract

Elevated intraocular pressure (IOP) is the main risk factor of glaucoma. In this study, an elevated IOP was introduced into the right eye balls of Sprague-Dawley rats, while their left eye balls were kept at a normal state. Nanoindentation showed that the elastic modulus of normal corneas was 2.75-3.33 MPa, whereas that of elevated IOP group was higher at 4.89-5.58 MPa. Scanning electron microscopy imaging suggested that the collagen fibrils subjected to the elevated IOP became thinner and with random directionality. It is believed the observed increase in elastic modulus should due to the strain-stiffening effects of collagen fibrils.

Keywords:

• Cornea
• Glaucoma
• Nanoindentation

Acknowledgments

The work described in this paper was supported by grants from the Research Grants Council (Project No. HKU 716908E), as well as from the University Grants Committee (Project No. SEG-HKU06) of the Hong Kong Special Administration Region, P.R. China. AHW Ngan would like to acknowledge support in the form of a Senior Research Fellowship from the Croucher Foundation.