Combining corneal hysteresis with central corneal thickness and intraocular pressure for glaucoma risk assessment

Abstract

Purpose To determine whether adjusting corneal hysteresis (CH) values for central corneal thickness (CCT) and intraocular pressure (IOP) improves its capability to differentiate primary open-angle glaucoma (POAG) from ocular hypertension (OH). Methods This prospective, observational, cross-sectional study included 169 eyes of 169 subjects with a diagnosis of POAG (n ¼ 81) or OH (n ¼ 88). We utilized the Ocular Response Analyzer (ORA), Pascal Dynamic Contour Tonometer (DCT), Goldmann applanation tonometer (GAT), and ORA ultrasound pachymeter to obtain CH, IOP, and CCT values. Correlational, regression, and t-test analyses were conducted before and after the sample was divided into low, intermediate, and thick CCT subgroups. Results In the full sample, CH and CCT were moderately correlated (r ¼ 0.44, Po0.001). Although both were related to diagnosis in univariate regression analysis, only CH was independently related to glaucoma diagnosis in multivariate analysis. After the sample was divided into CCT tertiles, CH was significantly lower in POAG vs OH eyes within all three CCT subgroups, and CH was the only multivariate variable that differentiated POAG from OH in each CCT subgroup. Moreover, the relationship between CH and diagnosis was more robust within the CCT subgroups compared with the full sample, suggesting that integrating CCT into CH interpretation is beneficial. Adjusting CH for IOP did not aid diagnostic precision in this study. ConclusionOur findings suggest that combining CH and CCT for glaucoma risk assessment improves diagnostic capability compared to using either factor alone. Conversely, adjusting CH for IOP provided no clear clinical benefit in this study.

Novel Parameter of Corneal Biomechanics That Differentiate Normals From Glaucoma

“…Prior studies using the ORA have demonstrated that glaucomatous eyes exhibit distinctly different biomechanical profiles as compared with nonglaucomatous eyes. [10][11][12][13][14][15][16][17][18][19][20][21][22] However, subsequent studies have shown that CH is moderately correlated with both IOPdependent and CCT-dependent variable with reported Pearson correlation coefficients ranging from 0.33 to 0.52. [34][35][36] Our work is the first, to the best of our knowledge, to describe a novel corneal biomechanical parameter-highest concavity time-which correlates with glaucomatous disease and is not associated with previously validated risk factors such as IOP, CCT, and age.…”

“…Prior studies have demonstrated statistically significant differences between CH and corneal resistance factor in patients with various categories of glaucomatous disease, including primary open-angle glaucoma, [10][11][12][13][14][15][16] primary angle closure glaucoma, 17,18 and normal tension glaucoma 12,[19][20][21][22] from normal eyes. Although there is conflicting evidence as to whether or not corneal biomechanical parameters are truly pressure-independent risk factors for glaucoma, 16,23 newer studies suggest that corneal biomechanical parameters may be able to predict the development and progression of this disease for individuals.…”

Ophthalmic Ultrasonography

“…A wide variety of other applications of ocular sonography, both as a clinical tool and a research tool, have been reported in the literature as well, including evaluation of patients with glaucoma, identification of ocular foreign bodies, diagnosis of a variety of acute and chronic problems, and even many veterinary applications. [27][28][29][30] …”

Comparison of Corneal Biomechanical Properties Betweeen Physiological Macrodiscs and Glaucomatous Macrodiscs

“…In this study, we defined macrodiscs as larger than 2.80 mm 2 . Normal disc size was defined as disc area between 1.4 and 2.80 mm 2 (11).…”

“…The Ocular Response Analyzer (ORA) (Reichert Inc., Depew, NY, USA) evaluates biomechanical properties of the cornea in situ. Corneal hysteresis (CH) measurement obtained using ORA demonstrates cornea's ability to dampen and buffer fluctuations in IOP (2).…”