Biomechanically Corrected IOP Measurement

Elsheikh, Ahmed; Mohammadvali, Ashkan; Chen, Kai-Jung

doi:10.5005/highlights-44-4s-7

Cited by 1 publication

(1 citation statement)

References 36 publications

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“…The biomechanically corrected intraocular pressure bIOP is a characteristic parameter determined by this tonometer. The equation for the bIOP value was determined using numerical simulations with the finite element method, taking into account the influence of corneal stiffness, corneal thickness, curvature, and biomechanical properties [ 4 ]. It has been shown experimentally that it is in fact less dependent on corneal thickness and age than uncorrected IOP , measured with the same tonometer [ 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

Novel Method of Measuring Corneal Viscoelasticity Using the Corvis ST Tonometer

Boszczyk

Kasprzak

Przeździecka-Dołyk

2022

JCM

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Background: The process of rapid propagation of the corneal deformation in air puff tonometer depends not only on intraocular pressure, but also on the biomechanical properties of the cornea and anterior eye. One of the biomechanical properties of the cornea is viscoelasticity, which is the most visible in its high-speed deformations. It seems reasonable to link the corneal viscoelasticity parameter to two moments of the highest speed of corneal deformations, when the cornea buckles. The aim of this work is to present a method of determining the time and place of occurrence of corneal buckling, examine spatial and temporal dependencies between two corneal applanations and bucklings in the Corvis ST tonometer, and correlate these dependencies with corneal viscoelastic properties. Methods: Images of the horizontal cross section of the Corvis ST deformed cornea from the air puff tonometer Corvis ST were used. 14 volunteers participated in the study, each of them had one eye measured eight times. Mutual changes in the profile slopes of the deformed corneas were numerically determined. They describe pure corneal deformation, eliminating the influence of rotation, and displacement of the entire eyeball. For each point in the central area of the corneal profile, the maximum velocities of mutual slope changes accompanying the applanations were estimated. The times of their occurrence were adopted as buckling times. Results: The propagation of buckling along the corneal profile is presented, as well as the repeatability and mutual correlations between the buckling parameters and intraocular pressure. Based on the relationship between them, a new parameter describing corneal hysteresis: Corvis Viscoelasticity (CVE) is introduced. It is characterized by high repeatability: ICC = 0.82 (0.69–0.93 CI) and low and insignificant correlation with intraocular pressure: r = 0.25 (p-value = 0.38). Conclusion: The results show for the first time how to measure the corneal buckling and viscoelastic effects with Corvis ST. CVE is a new proposed biomechanical parameter related to the viscoelastic properties of the cornea, which has high repeatability for the examined subject. The distribution of its values is planned to be tested on different groups of patients in order to investigate its clinical applicability.

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Section: Introductionmentioning

confidence: 99%