[Evaluation of corneal biomechanical properties in glaucoma and control patients by dynamic Scheimpflug corneal imaging technology].

PURPOSE

To compare corneal biomechanical properties measured with Corvis Scheimpflug technology (Corvis ST) between a group of patients with chronic open-angle glaucoma and a group of control patients.

DESIGN

Prospective observational case-control study.

METHODS

This study enrolled 56 right eyes of 56 patients (G1 [chronic open-angle glaucoma] n=37/G2 [control] n=19). Each patient underwent measurement of corneal biomechanical properties by dynamic Scheimpflug (Corvis ST) camera and the Ocular Response Analyser (ORA), then a measurement of intraocular pressure (IOP) by Goldmann applanation tonometry (GAT) and measurement of central corneal thickness (CCT) by optical coherence tomography during the same visit, by a single clinician. The parameters determined by Corvis ST are: Corvis IOP (IOP Corvis ST), the corneal deformation amplitude (CDA), corneal velocity, the time at highest concavity (TIME CONCAV), the lengths of applanation and their corresponding applanation time. Those studied by ORA are: compensated IOP (IOPcc), non-compensated IOL (IOPg), corneal hysteresis (CH) and corneal resistance factor (CRF).

RESULTS

IOP measured on all patients by Corvis ST was positively correlated to GAT (Spearman r=0.569, P<0.001) and PIOcc (Spearman r=0.531, P<0.001). After adjusting for age effect, CCT and GAT, the CDA was significantly lower in G1 than in G2, respectively 1.10 ± 0.12 mm and 1.15 ± 0.10mm (P<0.001). The TIME CONCAV is significantly shorter in G1 than in G2, respectively 16.88 ± 0.63 ms and 17.11 ± 0.29 ms, P=0.029. CH was significantly lower in G1 (G1: 9.58 ± 1.94 than G2: 10.89 ± 2.16, P=0.026).

CONCLUSIONS

This study showed differences in corneal biomechanical properties between glaucoma and control patients. The cornea of glaucoma patients appears less deformable.