A Comparison of the Corrected Intraocular Pressure Obtained by the Corvis ST and Reichert 7CR Tonometers in Glaucoma Patients.

Satoshi Okimoto,Yoshitaka Nakao,Sanjoy Bhattacharya,Yoshiaki Kiuchi

doi:10.1371/journal.pone.0170206

Satoshi Okimoto, Yoshitaka Nakao + Show 2 more

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https://doi.org/10.1371/journal.pone.0170206

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Journal: PloS one	Publication Date: Jan 17, 2017
Citations: 15	License type: CC BY 4.0

Affiliation: Hiroshima University

Abstract

The purpose of the study was to investigate the accuracy of two corrected intraocular pressure (IOP) measurements by Corvis Scheimpflug Technology (CST)-IOPpachy and by corneal-compensated IOP (IOPcc) using the Reichert 7CR (7CR) tonometers. We also investigated the effects of corneal anatomical and structural parameters on the IOP measurements. The participants included 90 primary open-angle glaucoma patients. We assessed the IOP measurements, obtained by the CST, 7CR, and Goldmann applanation tonometer (GAT), using a paired t-test with Bonferroni correction, Bland-Altman plots, and multiple regression analyses. The 7CR-IOPcc gave the highest value (15.5 ± 2.7 mmHg), followed by the 7CR-IOPg (13.7 ± 3.1 mmHg), GAT-IOP (13.6 ± 2.2 mmHg), CST-IOP (10.3 ± 2.6 mmHg), and CST-IOPpachy (9.7 ± 2.5 mmHg). The values of CST-IOPpachy were significantly lower than those obtained by the other IOP measurement methods (all, p < 0.01). The values of 7CR-IOPcc were significantly higher than those obtained by the other IOP measurement methods (all, p < 0.01). Bland-Altman plots showed a mean difference between the GAT-IOP and the other IOP measurements (CST-IOP, CST-IOPpachy, 7CR-IOPg, and 7CR-IOPcc), which were −3.20, −3.82, 0.14, and 2.00 mmHg, respectively. The widths of the 95% limits of agreement between all pairs of IOP measurements were greater than 3 mmHg. With the exception of the 7CR-IOPcc, all of the IOP variations were explained by regression coefficients involving gender, average corneal curvature, and central corneal thickness. The IOP values obtained by the GAT, CST, and 7CR were not interchangeable. Each new IOP measurement device that was corrected for ocular structure had its own limitations.

Highlights

Intraocular pressure (IOP) is a fundamental parameter in every ophthalmic examination, and it is of critical importance in the management of patients with glaucoma
The 7CR-IOPcc measurements resulted in the highest values [15.5 ± 2.7 mmHg], followed by 7CR-IOPg (13.7 ± 3.1 mmHg), Goldmann applanation tonometer (GAT)-IOP (13.6 ± 2.2 mmHg), CSTIOP (10.3 ± 2.6 mmHg), and Corvis Scheimpflug Technology (CST)-IOPpachy (9.7 ± 2.5 mmHg)
Using the paired t-test with Bonferroni correction, CST-IOPpachy showed significantly lower values than CST-IOP (p < 0.001), and both the CST-IOPpachy and CST-IOP values were significantly lower than the values from GAT-IOP, 7CR-IOPg, and 7CR-IOPcc

Summary

Introduction

Intraocular pressure (IOP) is a fundamental parameter in every ophthalmic examination, and it is of critical importance in the management of patients with glaucoma. The ideal tonometer should be accurate, and yield reproducible results that are minimally influenced by corneal properties. Corvis Scheimpflug Technology (CST) Air impulse 4,330 Scheimpflug images per second Inward applanation points CST-IOP CST-IOPpachy Central corneal thickness and age Ocular Response Analyzer (ORA)Reichert 7CR (7CR) Air impulse The signal intensity of the reflected infrared light Inward and outward applanation points Goldmann-correlated IOP (IOPg) Corneal corrected IOP (IOPcc) Corneal viscoelastic properties and thickness. Goldmann applanation tonometer (GAT) has several excellent characteristics, including high accuracy and high reproducibility [1, 2], and it is presently the clinical standard for IOP measurements. Corneal biomechanical properties, including the central corneal thickness (CCT), influence IOP measurements when using this device [3,4,5]

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