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Exp Eye Res. 2018 Oct;175:98-102. doi: 10.1016/j.exer.2018.06.013. Epub 2018 Jun 15.

Ex-vivo experimental validation of biomechanically-corrected intraocular pressure measurements on human eyes using the CorVis ST.

Author information

1
School of Engineering, University of Liverpool, Liverpool, L69 3GH, UK. Electronic address: eliasy.ashkan@gmail.com.
2
School of Engineering, University of Liverpool, Liverpool, L69 3GH, UK.
3
School of Engineering, University of Liverpool, Liverpool, L69 3GH, UK; St Paul's Eye Unit, Royal Liverpool and Broadgreen University Hospital, Liverpool, UK.
4
Department of Biomedical Science-Humanitas University, Via Manzoni 56, Rozzano, MI, Italy; Eye Center, Humanitas Clinical and Research Center, Via Manzoni 56, Rozzano, MI, Italy.
5
Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil; Department of Ophthalmology, Federal University of São Paulo (UNIFESP), São Paulo, Brazil; Department of Ophthalmology, Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil.
6
Department of Ophthalmology & Visual Science, Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA.
7
School of Engineering, University of Liverpool, Liverpool, L69 3GH, UK; NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, UK.

Abstract

The purpose of this study was to assess the validity of the Corvis ST (Oculus; Wetzlar, Germany) biomechanical correction algorithm (bIOP) in determining intraocular pressure (IOP) using experiments on ex-vivo human eyes. Five ex-vivo human ocular globes (age 69 ± 3 years) were obtained and tested within 3-5 days post mortem. Using a custom-built inflation rig, the internal pressure of the eyes was controlled mechanically and measured using the CorVis ST (CVS-IOP). The CVS-IOP measurements were then corrected to produce bIOP, which was developed for being less affected by variations in corneal biomechanical parameters, including tissue thickness and material properties. True IOP (IOPt) was defined as the pressure inside of the globe as monitored using a fixed pressure transducer. Statistical analyses were performed to assess the accuracy of both CVS-IOP and bIOP, and their correlation with corneal thickness. While no significant differences were found between bIOP and IOPt (0.3 ± 1.6 mmHg, P = 0.989) using ANOVA and Bonferroni Post-Hoc test, the differences between CVS-IOP and IOPt were significant (7.5 ± 3.2 mmHg, P < 0.001). Similarly, bIOP exhibited no significant correlation with central corneal thickness (p = 0.756), whereas CVS-IOP was significantly correlated with the thickness (p < 0.001). The bIOP correction has been successful in providing close estimates of true IOP in ex-vivo tests conducted on human donor eye globes, and in reducing association with the cornea's thickness.

KEYWORDS:

Corneal biomechanics; Intraocular pressure; Tonometry

PMID:
29908883
DOI:
10.1016/j.exer.2018.06.013

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