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

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.