The Effects of Negative Periocular Pressure on Biomechanics of the Optic Nerve Head and Cornea: A Computational Modeling Study

• Type of Material: Article
• Authors: Babak N Safa, Georgia Institute of Technology; Adam Bleeker, Dean A. McGee Eye Institute; John P Berdahl, Equinox Ophthalmic; C Ross Ethier, Georgia Institute of Technology
• Language: English
• Date: 2023-02-01
• Publisher: Association for Research in Vision and Ophthalmology.
• Publication Version: Final Published Version
• Copyright Statement: 2023 The Authors
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1167/tvst.12.2.5
• Title of Journal or Parent Work: Translational Vision Science and Technology
• Volume: 12
• Issue: 2
• Start Page: 5
• End Page: 5
• Keywords: Humans; Computer Simulation; Optic Disk; Biomechanical Phenomena; Finite Element Analysis; Cornea; Glaucoma
• Research Categories: Engineering, Biomedical; Health Sciences, Opthamology

Abstract

Purpose: The purpose of this study was to evaluate the effects of negative periocular pressure (NPP), and concomitant intraocular pressure (IOP) lowering, on the biomechan-ics of the optic nerve head (ONH) and cornea. Methods: We developed a validated finite element (FE) model of the eye to compute tissue biomechanical strains induced in response to NPP delivered using the Multi-Pressure Dial (MPD) system. The model was informed by clinical measurements of IOP lowering and was based on published tissue properties. We also conducted sensitivity analyses by changing pressure loads and tissue properties. Results: Application of −7.9 mmHg NPP decreased strain magnitudes in the ONH by c. 50% whereas increasing corneal strain magnitudes by c. 25%. Comparatively, a similar increase in corneal strain was predicted to occur due to an increase in IOP of 4 mmHg. Sensitivity studies indicated that NPP lowers strain in the ONH by reducing IOP and that these effects persisted over a range of tissue stiffnesses and spatial distributions of NPP. Conclusions: NPP is predicted to considerably decrease ONH strain magnitudes. It also increases corneal strain but to an extent expected to be clinically insignificant. Thus, using NPP to lower IOP and hence decrease ONH mechanical strain is likely biomechan-ically beneficial for patients with glaucoma. Translational Relevance: This study provides the first description of how NPP affects ONH biomechanics and explains the underlying mechanism of ONH strain reduction. It complements current empirical knowledge about the MPD system and guides future studies of NPP as a treatment for glaucoma.