Corneal Hysteresis as a Risk Factor for Glaucoma Progression: A Prospective Longitudinal Study

Abstract

Purpose To evaluate the role of corneal hysteresis (CH) as a risk factor for the rate of visual field progression in a cohort of glaucoma patients followed prospectively over time. Design Prospective observational cohort study. Participants The study group included 114 eyes of 68 glaucoma patients followed for an average of 4.0 ± 1.1 years. Visual fields were obtained with standard automated perimetry. Included eyes had a median number of 7 (range: 5 to 12) tests during follow-up. Methods CH measurements were acquired at baseline using the Ocular Response Analyzer (Reichert Instruments, Depew, NY, USA). Evaluation of rates of visual field change during follow-up was performed using the Visual Field Index (VFI). Linear mixed models were used to investigate the relationship between rates of visual field loss and baseline CH, baseline intraocular pressure (IOP) and central corneal thickness (CCT), while adjusting for potentially confounding factors. An interaction term between IOP and CH was included in the model to investigate whether the effect of IOP on rates of progression depended on the level of CH. Main Outcome Measures Effects of CH, IOP and CCT on rates of VFI loss over time. Results CH had a significant effect on rates of visual field progression over time. In the univariable model including only CH as a predictive factor along with time and their interaction, each 1mmHg lower CH was associated with 0.25%/year faster rate of VFI decline over time (P<0.001). The multivariable model showed that the effect of IOP on rates of progression depended on CH. Eyes with high IOP and low CH were at increased risk for having fast rates of disease progression. CH explained a larger proportion of the variation in slopes of VFI change than CCT (17.4% versus 5.2%, respectively). Conclusion CH measurements were significantly associated with risk of glaucoma progression. Eyes with lower CH had faster rates of visual field loss than those with higher CH. The prospective longitudinal design of this study supports the role of CH as an important factor to be considered in the assessment of the risk of progression in glaucoma patients.

Lack of Association Between Corneal Hysteresis and Corneal Resistance Factor With Glaucoma Severity in Primary Angle Closure Glaucoma

“…[15][16][17] We noted only modest Pearson correlations (À0.15 to À0.20) between CRF and VCDR (clinical and HRT) in our subjects. Although Vu et al 18 showed similar weak associations (r ¼ À0.11 to À0.15) of VCDR with CH, they did not report on the association with CRF.…”

Analyzing biomechanical parameters of the cornea with glaucoma severity in open-angle glaucoma

“…Lower CH has been reported to be associated with glaucomatous visual field progression in retrospective studies [11,13,28] and in one prospective study [12]. Anand et al found that lower CH was associated with worse eyes in asymmetric POAG [29].…”

“…In addition to the impact of these parameters on the accuracy of Goldmann applanation tonometry (GAT) [5][6][7][8][9][10], it has been shown that these parameters are significantly reduced in glaucoma patients and appear to be a risk factor for glaucoma progression [11][12][13].…”

The contribution of the sclera and lamina cribrosa to the pathogenesis of glaucoma

“…Second, people with axial myopia are more susceptible to OAG (Boland and Quigley, 2007) and their eyes have mechanical disadvantages in responding to the stress of IOP because of their larger globe diameter and thinner sclera. Third, hysteresis measured by an ocular response analyzer is a risk factor for OAG progression (Congdon et al, 2006;Medeiros et al, 2013). Fourth, in human glaucoma eyes, scleral rigidity is estimated to be increased by indirect measurements in vivo (Ebneter et al, 2009;Hommer et al, 2008) and by in vitro inflation studies .…”