Corneal Hysteresis and Progressive Retinal Nerve Fiber Layer Loss in Glaucoma

Abstract

Purpose: To investigate the relationship between corneal hysteresis (CH) and progressive retinal nerve fiber layer (RNFL) loss in a cohort of patients with glaucoma followed prospectively over time.

Design: Prospective observational cohort study.

Methods: One hundred and eighty-six eyes of 133 patients with glaucoma were followed for an average of 3.8 ± 0.8 years, with a median of 9 visits during follow-up. The CH measurements were acquired using the Ocular Response Analyzer (Reichert Instruments, Depew, New York, USA) and RNFL measurements were obtained at each follow up visit using spectral-domain optical coherence tomography (SDOCT). Random-coefficient models were used to investigate the relationship between baseline CH, central corneal thickness (CCT), average intraocular pressure (IOP), and rates of RNFL loss during follow-up, while adjusting for potentially confounding factors.

Results: Average baseline RNFL thickness was 76.4 ± 18.1 μm and average baseline CH was 9.2 ± 1.8 mm Hg. CH had a significant effect on rates of RNFL progression. In the univariable model, including only CH as a predictive factor along with time and their interaction, each 1 mm Hg lower CH was associated with a 0.13 μm/year faster rate of RNFL decline (P = .011). A similar relationship between low CH and faster rates of RNFL loss was found using a multivariable model accounting for age, race, average IOP, and CCT (P = .015).

Conclusions: Lower CH was significantly associated with faster rates of RNFL loss over time. The prospective longitudinal design of this study provides further evidence that CH is an important factor to be considered in the assessment of the risk of progression in patients with glaucoma.

Copyright © 2016 Elsevier Inc. All rights reserved.

Figures

Figure 1

Distribution of corneal hysteresis values at baseline for all 186 eyes included in the study of the relationship between corneal hysteresis and retinal nerve fiber layer loss during follow-up.

Figure 2

Scatterplot showing the relationship between rate of change in retinal nerve fiber layer (RNFL) thickness and baseline corneal hysteresis (Top) and average intraocular pressure (IOP) (Bottom) during follow up.

Figure 3

Example of a patient included in the study with low corneal hysteresis (7.9 mmHg) and thick central corneal thickness (575 μm) who experienced significant loss of retinal nerve fiber layer (RNFL) thickness over time (Top). Average intraocular pressure was 17 mmHg. Serial standard automated perimetry (Bottom left row) and SD-OCT RNFL thickness measurements (Bottom right row) are shown.