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.

No abstract

PURPOSE. We evaluated the ability of baseline and longitudinal estimates of retinal ganglion cell (RGC) counts in predicting progression in eyes suspected of having glaucoma.METHODS. The study included 288 glaucoma suspect eyes of 288 patients followed for an average of 3.8 6 1.0 years. Participants had normal standard automated perimetry (SAP) at baseline. Retinal nerve fiber layer thickness assessment was performed with optical coherence tomography (OCT). Progression was defined as development of repeatable abnormal SAP or glaucomatous progressive optic disc changes. Estimates of RGC counts were obtained by combining data from SAP and OCT according to a previously described method. Joint longitudinal survival models were used to evaluate the ability of baseline and rates of change in estimated RGC counts for predicting progression over time, adjusting for confounding variables. RESULTS.A total of 48 eyes (17%) showed progression during follow-up. The mean rate of change in estimated RGC counts was À18,987 cells/y in progressors versus À8,808 cells/y for nonprogressors (P < 0.001). Baseline RGC counts and slopes of RGC loss were significantly predictive of progression, with HRs of 1.56 per 100,000 cells lower (95% confidence interval [CI], 1.18-2.08; P ¼ 0.002) and 2.68 per 10,000 cells/y faster loss (95% CI, 1.22-5.90; P ¼ 0.014), respectively. The longitudinal model including estimates of RGC counts performed significantly better than models including only structural or functional indexes separately.CONCLUSIONS. Baseline and longitudinal estimates of RGC counts may be helpful in predicting progression and performed significantly better than conventional approaches for risk stratification of glaucoma suspects.