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

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.

Factors Associated With Corneal Deformation Responses Measured With a Dynamic Scheimpflug Analyzer

“…The current study also confirmed the significant negative associations among axial length and A2T, A2V, and radius, reported by Asaoka et al 35 Lee et al 36 reported significantly larger A2V and PD values in myopic subjects, which agrees with those from the current study. 36 Together, the current study confirmed more comprehensively the results of the previous investigations that myopic eyes have less corneal deformation.…”

“…The significant association between age and A2T reported in another previous study 35 was confirmed by the current study, but the current study did not confirm the associations of age with other parameters (A1T, A2V, radius, and HCDA) reported in the same paper. The inconsistencies among studies might be due to differences in statistical analyses and study populations.…”

“…These results basically agreed with the results of previous studies. 13,25,30,32,35 In the current study, the IOP was significantly negatively correlated with the WEMA, meaning that, with higher IOP values, there was less WEM. This could be because the supporting tissues such as the sclera become stiffer with increasing IOP, as reported in an experimental study.…”

Peripapillary Nerve Fiber Elevation in Young Healthy Eyes

“…To determine the independent factors of the pNFE, the optimal linear models were selected among all possible combinations of the predictors based on the second order bias corrected Akaike Information Criterion index. 26,27 …”

Applanation optical coherence elastography: noncontact measurement of intraocular pressure, corneal biomechanical properties, and corneal geometry with a single instrument

“…4 Moreover, biomechanical measurements of the cornea are confounded by other parameters, such as IOP 5,6 and central corneal thickness (CCT). 5,7 Thus, providing an accurate measurement of corneal mechanical parameters (e.g., Young's modulus) is not straightforward, let alone based on applanation measurements. Nevertheless, commercially available noncontact tonometers (e.g., the ocular response analyzer and CorVis ST) can distinguish between healthy and keratoconic corneas, 8 but there have been conflicting results on their ability to detect corneal biomechanical changes due to therapeutic interventions such as corneal collagen crosslinking.…”