Corneal biomechanical characteristics measured by the CorVis Scheimpflug technology in eyes with primary open-angle glaucoma and normal eyes

Abstract

Purpose: To evaluate the biomechanical properties of the cornea using Corneal Visualization Scheimpflug Technology (CorVis ST, Oculus) in eyes with primary open-angle glaucoma (POAG) and normal control eyes.

Methods: A comparative cross-sectional study that included 42 patients with POAG and 60 normal control subjects matched for intraocular pressure (IOP) and central corneal thickness (CCT). IOP was measured with a Goldmann applanation tonometer (GAT). Corneal tomography and biomechanical parameters were measured with Pentacam (Oculus) and CorVis ST, respectively. Corneal biomechanical properties were compared between groups, and the associations between corneal biomechanical parameters and ocular characteristics were evaluated. Receiver operating characteristic (ROC) curves were used to establish a cut-off value for the biomechanical parameters.

Results: The following parameters of the CorVis ST showed a significant difference between eyes with POAG and normal eyes: first applanation velocity (Vin ), second applanation time (A-time2 ), peak distance (PD) and deformation amplitude (DA). In the univariate analysis, DA was negatively correlated with IOP in both groups. For all biomechanical parameters, the areas under the ROC curve were <0.80 and thus did not reach a good level of predictive accuracy for detecting POAG.

Conclusion: CorVis ST offers an alternative method for measuring corneal biomechanical properties. Eyes with POAG exhibit a faster Vin , longer A-time2 , lower DA and longer PD than do IOP- and CCT-matched normal control eyes. The biomechanical parameters of the CorVis ST cannot readily be used for diagnosis of POAG in the individual patient.

Keywords: corneal biomechanics; corneal visualization Scheimpflug technology; deformation amplitude; primary open-angle glaucoma.