Development and validation of a correction equation for Corvis tonometry.

Joda, Akram Abdelazim ORCID: 0000-0001-8930-7954, Shervin, Mir Mohi Sefat, Kook, Daniel and Elsheikh, Ahmed ORCID: 0000-0001-7456-1749 (2016) Development and validation of a correction equation for Corvis tonometry. Computer methods in biomechanics and biomedical engineering, 19 (9). pp. 943-953.

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Abstract

<h4>Primary objective</h4>This study uses numerical analysis and validation against clinical data to develop a method to correct intraocular pressure (IOP) measurements obtained using the Corvis Tonometer for the effects of central corneal thickness (CCT), and age.<h4>Materials and methods</h4>Finite element analysis was conducted to simulate the effect of tonometric air pressure on the intact eye globe. The analyses considered eyes with wide variations in IOP (10-30 mm Hg), CCT (445-645 microns), R (7.2-8.4 mm), shape factor, P (0.6-1) and age (30-90 years). In each case, corneal deformation was predicted and used to estimate the IOP measurement by Corvis (CVS-IOP). Analysis of the results led to an algorithm relating estimates of true IOP as a function of CVS-IOP, CCT and age. All other parameters had negligible effect on CVS-IOP and have therefore been omitted from the algorithm. Predictions of corrected CVS-IOP, as obtained by applying the algorithm to a clinical data-set involving 634 eyes, were assessed for their association with the cornea stiffness parameters; CCT and age.<h4>Results</h4>Analysis of CVS-IOP measurements within the 634-large clinical data-set showed strong correlation with CCT (3.06 mm Hg/100 microns, r(2) = 0.204) and weaker correlation with age (0.24 mm Hg/decade, r(2) = 0.009). Applying the algorithm to IOP measurements resulted in IOP estimations that became less correlated with both CCT (0.04 mm Hg/100 microns, r(2) = 0.005) and age (0.09 mm Hg/decade, r(2) = 0.002).<h4>Conclusions</h4>The IOP correction process developed in this study was successful in reducing reliance of IOP measurements on both corneal thickness and age in a healthy European population.

Item Type:	Article
Uncontrolled Keywords:	Cornea, Humans, Tonometry, Ocular, Reproducibility of Results, Intraocular Pressure, Algorithms, Pressure, Models, Theoretical, Time Factors, Numerical Analysis, Computer-Assisted, Adult, Aged, Aged, 80 and over, Middle Aged, Young Adult, Corneal Pachymetry
Depositing User:	Symplectic Admin
Date Deposited:	11 Apr 2016 08:17
Last Modified:	17 Dec 2022 02:28
DOI:	10.1080/10255842.2015.1077515
Related URLs:	Author
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3000421