Dataset Information

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

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 biomechanics 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 biomechanically 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.

SUBMITTER: Safa BN

PROVIDER: S-EPMC9910383 | biostudies-literature | 2023 Feb

REPOSITORIES: biostudies-literature

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Publications

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

Safa Babak N BN Bleeker Adam A Berdahl John P JP Ethier C Ross CR

Translational vision science & technology 20230201 2

<h4>Purpose</h4>The purpose of this study was to evaluate the effects of negative periocular pressure (NPP), and concomitant intraocular pressure (IOP) lowering, on the biomechanics of the optic nerve head (ONH) and cornea.<h4>Methods</h4>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 ...[more]

PMID: 36745441

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Project description:Intraocular pressure (IOP) is an important risk factor for glaucoma, and the response of the ONH and surrounding tissues to elevated IOP are often investigated to better understand pathophysiology. In vivo structure including that of the optic nerve head (ONH) and surrounding tissue of the eye are often assessed using optical coherence tomography (OCT). With advances in OCT technology, both large vessels and capillaries can be imaged non-invasively (OCT Angiography). Because a significant portion of retinal thickness is comprised of vasculature, the purpose of the current study was to investigate OCT structural and vascular changes in healthy non-human primate eyes with systematic graded increases and decreases in IOP. Six healthy animals with no previous experimental intervention were used. The pressure in the anterior chamber was adjusted from 10?mmHg to 60?mmHg and back to 10?mmHg in 10?mmHg steps every 10?min. Using optical coherence tomography (OCT), retinal nerve fiber layer (RNFL) thickness, minimum rim width (MRW), Bruch's membrane opening (BMO) size and relative height, anterior lamina cribrosa surface (ALCS) depth, choroidal thickness, and angiography (OCTA) were quantified. With IOP challenge there were significant changes in all morphological measures quantified (p?<?0.01) other than BMO size (p?=?0.30) and RNFL thickness (p?=?0.29). Specifically, the position of the BMO was sensitive to both an increase and decease in IOP. The inner retinal capillary density gradually decreased with increasing IOP, reaching statistical significance when pressure exceeded 50?mmHg, but returned when IOP was reduced. The average choroidal thickness around the ONH decreased for elliptical annuli 500-1000??m and 1000-1500??m, from the BMO, with increasing IOP (p?<?0.01). For the 1000-1500??m annulus, choroid thickness did not return to baseline with IOP reduction. Similarly, the MRW decreased with increase in IOP, but with pressure reduction did not return, and at the final 10?mmHg time point was thinner than at baseline (p?<?0.01). The results from this experiment illustrate differences in ONH neural rim tissue, RNFL and vessel density changes with acute IOP challenge. Overall, vessel collapse could not completely account for changes in RNFL or ONH MRW thickness. The study supports the hypothesis neural rim compression may be an important part of IOP-induced damage.

Dataset Information

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

Purpose

Methods

Results

Conclusions

Translational relevance

Publications

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

Similar Datasets

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