Assessment of Corneal Biomechanics in Cases of Glaucoma before and after Control: A Prospective Study

Purpose: To compare corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated KW (IOPcc), and Goldmann-correlated KW (IOPg) in normal eyes and open angle glaucoma before and after treatment. Study Design: Prospective, hospital based, observational study. Methods: 282 consecutive subjects were divided into two main groups; normal control group (group 1, 141 cases and glaucoma group II, comprised of 141 cases). Group II was subdivided into controlled glaucoma group A under medical treatment (119 cases); and controlled glaucoma group after trabeculectomy (group B, 22 cases). Full ophthalmological examination and assessment of corneal biomechanical properties using the Ocular Response Analyzer were done. All results were expressed as mean±SD. Analysis of variance (ANOVA) with post hoc comparisons and students t-test with Bonferroni correction were used to assess differences in groups and between groups. Pearson correlation was done to detect correlation between tested variables. Results: Mean IOPcc did not differ significantly from the mean IOPg in all groups. In group IIA, IOPg was significantly higher than IOPg in control group (p=0.001). After medical treatment, the IOPg was significantly reduced (p=0.001). Corneal hysteresis increased significantly from 8.73±2.40mm Hg before treatment to 9.52±1.68mm Hg. (p=0.037). CRF was significantly higher in group IIA than group I (p=0.001) and it was significantly reduced after medical treatment. In group IIB, IOPg and IOPcc were significantly reduced but the CH and CRF did not show significant difference from the control group I. In all groups, CH showed significant negative correlation with IOPg and IOPcc (p=0.0001). Meanwhile, CRF showed strong positive correlation with IOPg and IOPcc (p=0.0001). Conclusion: The corneal biomechanical factors (CH and CRF) showed association with the IOP After treatment whether medical or surgical, the recovery of CH and CRF values suggested that these factors could be used as a measuring for the accuracy of treatment.