Decrease Corneal Hysteresis in Early Glaucoma Patients Measured with Ocular Response Analyzer (Ora) Helps in Early Diagnosis of Glaucoma

Abstract

The aim of the research was to compare the intraocular pressure value (IOP) measured with a GAT (Goldmann tonometer) with the cornea compensated IOP obtained with an ORA tonometer, and to establish whether there is a correlation between the IOP, corneal hysteresis and OCT RNFL results. Patients were divided into two groups: healthy individuals, with no ophthalmic history, and patients with early primary open angle glaucoma, treated pharmacologically with no history of either laser nor surgical eye treatment. The inclusion criteria were assessed based on the ophthalmic assessment of the optic nerve disc and perimetry (MD>-6dB). The control group included 25 subjects and the patient group 46. All measurements were performed in the Glaucoma Outpatient Clinic of the Wroclaw University Hospital: intraocular pressure with GAT and ORA, central corneal thickness, OCT RNFL. A significant positive correlation between ORA IOP and GAT IOP was found in the glaucoma group. There was significant negative correlation between ORA IOP and CH. There was a strong positive correlation between ORA IOP and GAT IOP results in the control group. Corneal hysteresis (CH) in patients with early stage glaucoma, confirmed by incorrect OCT RNFL values, is lower compared with the control group. CH is an important parameter useful for glaucoma diagnosis and evaluation of risk groups. IOP values measured with the ORA tonometer correlated with results obtained with the GAT. ORA tonometry is a novel, noninvasive method of intraocular pressure and corneal hysteresis measurement, that can be used alternatively for GAT.