Abstract
Purpose: :
To evaluate the relative influences of age, diabetes, intraocular pressure (IOP), and several ocular structural parameters on corneal hysteresis (CH) measurement.
Methods: :
Subjects were recruited from consecutive Albuquerque VA Medical Center eye clinic patients. Eligible subjects were categorized into one of four diagnostic groups: primary open-angle glaucoma (POAG), ocular hypertension (OH), glaucoma suspect (GS), or normal (NML). The Ocular Response Analyzer, Pascal dynamic contour tonometer, and Goldmann applanation tonometer were used to obtain IOP, CH, corneal resistance factor (CRF), and ocular pulse amplitude (OPA) values. Keratometry, pachymetry, axial length biometry, standard automated perimetry, cup/disc ratio (c/d) estimates, and Stratus OCT-derived retinal nerve fiber layer (RNFL) measurements were also obtained. Diabetes diagnostic status and glycosylated hemoglobin (HbA1c) levels were determined through chart review. One eye was randomly selected for analysis, unless only one eye met the criteria for glaucoma diagnosis in which case that eye was used. ANOVA and regression analyses were used to evaluate relationships between the studied parameters.
Results: :
Two hundred forty-three eyes in 243 subjects were studied. In univariate regression analyses, CH varied directly with CCT, CRF, HbA1c, mean visual field defect, and mean RNFL measurement, while CH varied inversely with age, IOP, c/d, and visual field pattern standard deviation. Additionally, CH was associated with diagnosis (lowest in POAG group, highest in NML group.) In multivariate regression analyses, independent associations remained between CH and the following: age, CCT, IOP, HbA1c, and diagnosis. Notably, while CH was significantly correlated with level of IOP in the POAG and OH groups, no significant CH:IOP correlation was evident in the GS and NML groups.
Conclusions: :
Although CH measurements have been shown to be associated with presence and severity of POAG, clinical use of this metric is challenging due to the numerous factors that influence CH measurement. For optimal clinical application of CH information, the confounding aspects of age, CCT, IOP, diagnostic status, and possibly DM status should be addressed.
Keywords: cornea: clinical science • diabetes • intraocular pressure