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Purpose: To determine if corneal hysteresis (CH) was associated with increased central corneal thickness (CCT) induced by wearing soft contact lenses during eye closure. Design: A prospective laboratory investigation. Methods: CCT was measured with a modified optical coherence tomography (OCT), and CH was measured with a Reichert Ocular Response Analyzer (ORA) [Reichert Ophthalmic Instruments, Depew, New York, USA]. The ORA also determined values for intraocular pressure (IOP), corneal compensated IOP (IOPcc), and corneal resistance factor (CRF). One randomly selected eye of 20 non–contact lens wearers (four males and 16 females, age 19.7 ± 1.1 years) was patched during three hours of soft contact lens wear. Measurements were made before lens insertion, immediately upon removal, and every 20 minutes thereafter for 100 minutes. Results: Immediately after contact lens removal, CCT was increased by 13.1 ± 2.2% (mean ± SD) compared with baseline (post hoc, P = .001). After 100 minutes, it remained elevated by 2.4 ± 1.6% (post hoc, P = .001). However, there were no significant differences of CH at any time after lens wear (analysis of variance [ANOVA], P = .9). Immediately after lens removal, there were significant increases in IOP (post hoc, P = .003) and corneal resistance factor (CRF) (post-hoc, P = .015), but not in IOPcc (post hoc, P = .07). After lens wear, there were significant but weak correlations between the percentage change of CCT (CCT%) and IOP (r = 0.32, P = .001) and IOPcc (r = 0.29, P = .001). However, there was no significant correlation between CCT% and CH (r = 0.07, P = .458). Conclusion: CH as measured by ORA was not associated with corneal swelling induced by soft contact lens wear in this study group. [Copyright &y& Elsevier]

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. [Copyright &y& Elsevier]