Corneal biomechanical properties associated with glaucoma damage.

Abstract

Abstract Purpose We measured the impact of corneal hysteresis (CH), a measure of viscous damping in the cornea, and corneal resistance factor (CRF), highly correlated with central corneal thickness (CCT), to determine the effect of the glaucoma damage on these two parameters. Methods 130 eyes of 65 adult patients were classified into two groups (control group and glaucoma group). Measurements of CH and CRF on the Reichert Ocular Response Analyzer, and measurements of CCT by ultrasonic pachymetry were made. In the glaucoma group we reviewed the chart to determine highest known intraocular pressure (IOP), target IOP, diagnosis, years with glaucoma, cup‐to‐disk ratio (CDR), mean defect (MD), and presence or absence of visual field progression. Statistical analysis was performed using SPSS 15.0 for Windows. Results Control group (56 eyes): The mean age was 43.29 years (SD 15.35), 26 were male. Glaucoma group (74 eyes): All eyes had a diagnosis of primary open angle glaucoma. The mean age was 56.38 years (SD 13.49), 40 were male. The mean hysteresis in normal eyes was 11.15 (SD 1.37) while in glaucomatous population was 9.71 (SD 1.89). A lower corneal hysteresis value (P<0.05) was associated with glaucomatous eyes with visual field progression, which causes a change in the measured compensated intraocular pressure. No effect on CRF was observed. Conclusion The biomechanical properties of the cornea are modified according to the pathology. CH is significantly higher in the normal group than in the glaucoma group. In glaucoma group lower CH was associated with progressive field worsening. We found no effect of progressive field worsening on the CRF.