Modelling floppy iris syndrome and the impact of pupil size and ring devices on iris displacement.

Autor: Lockington D; Tennent Institute of Ophthalmology, Gartnavel General Hospital, Glasgow, UK. davidlockington@hotmail.com., Wang Z; Department of Mechanical Engineering, Hong Kong Polytechnic University, Hong Kong, China., Qi N; Institute of Marine Science and Technology, Shandong University, Shandong, China., Malyugin B; S. Fyodorov Eye Microsurgery Federal State Institution, Moscow, Russia., Cai L; School of Mathematics and Statistics, Northwestern Polytechnical University, Xi'an, China., Wang C; Department of Mechanical Engineering, Hong Kong Polytechnic University, Hong Kong, China., Tang H; Department of Mechanical Engineering, Hong Kong Polytechnic University, Hong Kong, China., Ramaesh K; Tennent Institute of Ophthalmology, Gartnavel General Hospital, Glasgow, UK., Luo X; School of Mathematics and Statistics, University of Glasgow, Glasgow, UK.
Jazyk: angličtina
Zdroj: Eye (London, England) [Eye (Lond)] 2020 Dec; Vol. 34 (12), pp. 2227-2234. Date of Electronic Publication: 2020 Feb 04.
DOI: 10.1038/s41433-020-0782-7
Abstrakt: Introduction: The aim of this paper was to further develop a previously described finite element model which equates clinical iris billowing movements with mechanical buckling behaviour, simulating floppy iris syndrome. We wished to evaluate the impact of pupil dilation and mechanical devices on normal iris and floppy iris models.
Methods: Theoretical mathematical modelling and computer simulations were used to assess billowing/buckling patterns of the iris under loading pressures for the undilated and dilated normal iris, the undilated and dilated floppy iris, and additionally with a mechanical ring device.
Results: For the normal iris, billowing/buckling occurred at a critical pressure of 19.92 mmHg for 5 mm pupil size, which increased to 28.00 mmHg (40.56%) with a 7 mm pupil. The Malyugin ring device significantly increased critical initiating buckling pressures in the normal iris scenario, to 34.58 mmHg (73.59%) for 7 mm ring with boundary conditions I (BC I) and 34.51 mmHg (73.24%) with BC II. For the most floppy iris modelling (40% degradation), initiating buckling value was 18.04 mmHg (-9.44%), which increased to 28.39 mmHg (42.52%) with the 7 mm ring. These results were much greater than for normal undilated iris without restrictive mechanical expansion (19.92 mmHg).
Conclusion: This simulation demonstrates that pupil expansion devices inhibit iris billowing even in the setting of floppy iris syndrome. Our work also provides a model to further investigate the impact of pupil size or pharmacological interventions on anterior segment conditions affected by iris position.
Databáze: MEDLINE
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