The Relationship between Corvis ST Tonometry Measured Corneal Parameters and Intraocular Pressure, Corneal Thickness and Corneal Curvature

Ryo Asaoka,Hitoshi Tabuchi,Ulfah Rimayanti,Noriko Ihara,Shunsuke Nakakura,Yoshitaka Nakao,Makoto Aihara,Hiroshi Murata,Yoshiaki Kiuchi,Pedro Gonzalez

doi:10.1371/journal.pone.0140385

Ryo Asaoka, Hitoshi Tabuchi + Show 8 more

Open Access

https://doi.org/10.1371/journal.pone.0140385

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Abstract

The purpose of the study was to investigate the correlation between Corneal Visualization Scheimpflug Technology (Corvis ST tonometry: CST) parameters and various other ocular parameters, including intraocular pressure (IOP) with Goldmann applanation tonometry. IOP with Goldmann applanation tonometry (IOP-G), central corneal thickness (CCT), axial length (AL), corneal curvature, and CST parameters were measured in 94 eyes of 94 normal subjects. The relationship between ten CST parameters against age, gender, IOP-G, AL, CST-determined CCT and average corneal curvature was investigated using linear modeling. In addition, the relationship between IOP-G versus CST-determined CCT, AL, and other CST parameters was also investigated using linear modeling. Linear modeling showed that the CST measurement ‘A time-1’ is dependent on IOP-G, age, AL, and average corneal curvature; ‘A length-1’ depends on age and average corneal curvature; ‘A velocity-1’ depends on IOP-G and AL; ‘A time-2’ depends on IOP-G, age, and AL; ‘A length-2’ depends on CCT; ‘A velocity-2’ depends on IOP-G, age, AL, CCT, and average corneal curvature; ‘peak distance’ depends on gender; ‘maximum deformation amplitude’ depends on IOP-G, age, and AL. In the optimal model for IOP-G, A time-1, A velocity-1, and highest concavity curvature, but not CCT, were selected as the most important explanatory variables. In conclusion, many CST parameters were not significantly related to CCT, but IOP usually was a significant predictor, suggesting that an adjustment should be made to improve their usefulness for clinical investigations. It was also suggested CST parameters were more influential for IOP-G than CCT and average corneal curvature.

Highlights

Glaucoma is the second leading cause of blindness in the world and approximately 60 million people are affected with the disease.[1]
Central corneal thickness (CCT) has been proposed as a factor related to the progression of glaucoma; one study suggested that a thin cornea is associated with an increased risk, [2] a more recent study purported that corneal hysteresis (CH) measured with the Ocular Response Analyzer (ORA, Reichert Ophthalmic Instruments, Depew, NY, USA) is a risk factor of glaucoma, but CCT is not,[3] and results from a randomized controlled study confirmed this finding.[4]
It was suggested that intraocular pressure (IOP) measured with Goldmann tonometer is influenced by CST determinedCCT and corneal curvature when other CST parameters were not considered, but importantly, these parameters were no longer selected when the other CST parameters were considered

Summary

Introduction

Glaucoma is the second leading cause of blindness in the world and approximately 60 million people are affected with the disease.[1]. There is a previous report which analyzed the relationship among CST parameters, but without GAT measured IOP and corneal curvature. It has been widely reported that IOP measurements from Goldmann applanation tonometer can be influenced by corneal biomechanics, such as CCT[9,10,11,12,13,14,15,16,17,18,19] and corneal curvature.[13,20,21] the second purpose of the study was to investigate the effect of CST-determined corneal biomechanical parameters on IOP readings by GAT

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