Modelling floppy iris syndrome and the impact of phenylephrine on iris buckling

Qi, N., Lockington, D., Wang, H., Hill, N. A. , Ramaesh, K. and Luo, X. (2018) Modelling floppy iris syndrome and the impact of phenylephrine on iris buckling. International Journal of Applied Mechanics, 10(5), 1850048. (doi:10.1142/S1758825118500485)

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Abstract

Abnormal iris movement (floppy iris syndrome) during intraocular surgery is associated with an increased risk of intraoperative complications. We have previously investigated this scenario with respect to intracameral air in corneal endothelial transplantation, and described the concept of iris buckling. As a number of clinical interventions are recommended for addressing floppy iris syndrome, we wished to evaluate the impact of intracameral phenylephrine on iris buckling and so refine our mathematical model. We considered the stability of an iris structure under a uniform pressure loading. We performed mathematical and computational simulations to demonstrate iris buckling, and then altered the parameters to assess the impact of phenylephrine on the model. We elucidated a number of buckled iris configurations which become unstable as the intraocular pressure increased, for transversely isotropic iris material properties, and identified a positive correlation between the critical pressure and the iris stiffness. A mechanical analysis with a dilated pupil (mimicking phenylephrine use) was also conducted, and demonstrated a significant increase in the critical pressure required to induce iris buckling. We have shown that iris buckling can arise at lower pressures when the iris stiffness is reduced, as in floppy iris syndrome. The use of phenylephrine was shown to prevent iris movement (buckling) by increasing the required critical pressures. This refined model demonstrates the positive effectiveness of phenylephrine in the management of floppy iris syndrome and gives evidence to the clinical practice of using this as a preventative measure.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Luo, Professor Xiaoyu and Qi, Dr Nan and Hill, Professor Nicholas and Wang, Mr HuiMing and Ramaesh, Dr Kanna
Authors: Qi, N., Lockington, D., Wang, H., Hill, N. A., Ramaesh, K., and Luo, X.
College/School:College of Medical Veterinary and Life Sciences
College of Science and Engineering > School of Mathematics and Statistics > Mathematics
Journal Name:International Journal of Applied Mechanics
Publisher:World Scientific Publishing
ISSN:1758-8251
ISSN (Online):1758-826X
Published Online:11 July 2018
Copyright Holders:Copyright © 2018 The Authors
First Published:First published in International Journal of Applied Mechanics 10(5):1850048
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
560111Finite element-immersed boundary method and its application to mitral valvesXiaoyu LuoEngineering and Physical Sciences Research Council (EPSRC)EP/I029990/1M&S - MATHEMATICS