Corneal biomechanical properties

SIGNIFICANT advances are being made in unlocking the secrets of the cornea’s biomechanical properties and the underlying processes at work after collagen cross-linking (CXL) in keratoconic eyes, according to Cynthia Roberts PhD. Speaking at the joint ESCRS/EuCornea symposium on Corneal Cross-Linking: Current Status and Future Perspectives, Dr Roberts said that the future will lead to the ability to predict curvature changes that result in visual improvements for patients based on initial biomechanical measurements. “We are not quite there yet because we are currently just measuring some of the early changes in CXL. We also need to bear in mind as well that intraocular pressure (IOP) is an important factor in the assessment of corneal biomechanics,” she said. Dr Roberts said that her hypothesis is that the curvature, thickness and elevation changes, which are measured tomographically in keratoconus, are secondary symptoms of pre-clinical keratoconus, and that the primary corneal alteration is focally biomechanical. “If there is a focal reduction in elasticity, that area is going to stretch more than the areas around it, which leads to strain, redistribution of stress and increased curvature, triggering the cycle of biomechanical decompensation with keratoconus. The goal is really to try to figure out how to interrupt that cycle,” she said. While mechanical testing has shown for some time that keratoconic corneas are weaker, no effort was ever made to look for asymmetry of properties in those corneas, said Dr Roberts. A new non-contact technique pioneered at Harvard University using Brillouin microscopy based on light scattering from inherent acoustic waves in tissues seeks to rectify that, and has already enabled the mapping of the elastic modulus of normal and keratoconus patients in vivo.

Tags: cornea