Recovery of Corneal Hysteresis After Reduction of Intraocular Pressure in Chronic Primary Angle-Closure Glaucoma

Purpose: To measure corneal hysteresis (CH) in unilateral chronic primary angle-closure glaucoma (CPACG) patients to determine if it was affected by high intraocular pressure (IOP). Design: Prospective interventional case series. Methods: CH and Goldmann-correlated IOP (IOPg) were obtained with the Ocular Response Analyzer (Reichert Ophthalmic Instruments, Dephew, New York, USA) and central corneal thickness (CCT) was measured by optical coherence tomography. Baseline CH, IOPg, and CCT were measured in 40 CPACG eyes and compared to the fellow eyes and 40 normal controls. Reduction of IOPg in CPACG eyes was achieved medically, followed by trabeculectomy and peripheral iridectomy. Measurements were repeated at 2 and 4 weeks posttherapy. Results: IOPg decreased significantly from 31.55 ± 10.48 mm Hg (mean ± standard deviation) before therapy to 11.47 ± 4.71 mm Hg, and CH increased significantly from 6.83 ± 2.08 mm Hg to 9.22 ± 1.80 mm Hg at 2 weeks, with no further changes after that. However, the CH in the treated eyes remained significantly lower compared with that of fellow and normal eyes. Before treatment, CH was negatively correlated with IOPg; however, there was no correlation after treatment. CCT was not affected by the reduced IOPg in the CPACG eyes. Conclusions: CH was significantly lower in CPACG patients, and partial recovery occurred after successful IOP-lowering therapy. Alternations affecting corneal biomechanical properties appear to occur during glaucoma development.