Posters

Evaluation of the biomechanical compensation of the intraocular pressure measurement using the Corvis ST device in keratoconus eyes

Poster Details

First Author: S.Rodrigo Rey SPAIN

Co Author(s): R. Cañones-Zafra   G. Bolívar   J. Gros-Otero   M. Teus           

Abstract Details

Purpose:

To evaluate the correlation, in keratoconic corneas, of the anterior and posterior elevation and the maximum anterior curvature (Kmax) obtained using the Scheimpflug tomograph (Pentacam HR®, Oculus), and both the biomechanically corrected intraocular pressure (bIOP) and the uncorrected pressure (IOPnct), measured using the Corvis Scheimpflug technology (Corvis ST®, Oculus).

Setting:

Department of Ophthalmology, Príncipe de Asturias University Hospital, Alcalá de Henares, Madrid, Spain.

Methods:

This is an observational cross-sectional study, were 65 eyes from 37 patients with keratoconus diagnosis were studied. A tomography scan was taken with Pentacam HR® followed by a biomechanical measurement taken with the Corvis ST. For each eye we analyzed the anterior and posterior elevation, the anterior maximum curvature (Kmax), the biomechanically compensated IOP (bIOP) and the non-contact IOP (IOPnct). Linear regression analysis and Pearson’s correlation coefficient were obtained.

Results:

Mean anterior corneal elevation was 15.75±11.63 (range from -5 to +55 μm), mean posterior elevation was 38.96±23.07 (range from +5 to +105) and mean Kmax was 51.11±5.2 (range from 42.2±66.1). The bIOP and the IOPnct obtained were 14.13±1.67mmHg, 12.73±1.93mmHg respectively. A significant correlation was obtained between the IOPnct and the anterior elevation, the posterior elevation and the Kmax, r2 of 0.24, 0.1 and 0.2 respectively, p <0.05 for all comparisons; whereas no significant correlation was found between the bIOP and any of the analyzed Pentacam® parameters (p>0.1). The Anterior and posterior surfaces were highly and significantly correlated (p=0.0001, r2= 0.88).

Conclusions:

Our results show a statistically significant correlation between the anterior and posterior surface corneal parameters related with the degree of ectasia with the IOPnct, while no significant correlation was found with the bIOP. This suggests that the bIOP is not affected by the corneal weakening seen in keratoconus, and thus seems to accurately reflect the true IOP. In addition, the tight correlation found between the anterior and posterior corneal curvatures suggests that epithelial hypoplasia at the conus apex seems to have a limited effect.

Financial Disclosure:

None