Ultrasonic elastography to assess biomechanical properties of the optic nerve head and peripapillary sclera of the eye

Xuejun Qian; Runze Li; Gengxi Lu; Laiming Jiang; Haochen Kang; K Kirk Shung; Mark S Humayun; Qifa Zhou

doi:10.1016/j.ultras.2020.106263

Ultrasonic elastography to assess biomechanical properties of the optic nerve head and peripapillary sclera of the eye

Ultrasonics. 2021 Feb:110:106263. doi: 10.1016/j.ultras.2020.106263. Epub 2020 Oct 10.

Authors

Xuejun Qian¹, Runze Li¹, Gengxi Lu¹, Laiming Jiang², Haochen Kang³, K Kirk Shung³, Mark S Humayun¹, Qifa Zhou⁴

Affiliations

¹ Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA; USC Roski Eye Institute, University of Southern California, Los Angeles, CA 90033, USA.
² USC Roski Eye Institute, University of Southern California, Los Angeles, CA 90033, USA.
³ Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
⁴ Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA; USC Roski Eye Institute, University of Southern California, Los Angeles, CA 90033, USA. Electronic address: qifazhou@usc.edu.

Abstract

Purpose: To quantitatively investigate both optic nerve head (ONH) and peripapillary sclera (PPS) biomechanical properties of porcine eyes through an ultrasonic elastography imaging system in response to both increasing and decreasing intraocular pressure (IOP).

Methods: The Young's modulus of the ONH and PPS were assessed using our high resolution ultrasonic imaging system which utilized a mechanical shaker to induce shear waves and an off-axis aligned 40 MHz needle transducer to track micron-level displacement along the direction of wave propagation. In this study, imaging on a total of 8 ex vivo porcine eyes preloaded with IOPs from 6 mmHg to 30 mmHg was performed. To have a better understanding of the effect of varying IOP on biomechanics, both increasing and decreasing IOPs were investigated.

Results: The increase of the Young's modulus of ONH (92.4 ± 13.9 kPa at 6 mmHg to 224.7 ± 71.1 kPa at 30 mmHg) and PPS (176.8 ± 14.3 kPa at 6 mmHg to 573.5 ± 64.4 kPa at 30 mmHg) following IOP elevation could be observed in the reconstructed Young's modulus of the shear wave elasticity (SWE) imaging while the B-mode structural images remained almost unchanged. In addition, for the same IOP level, both ONH and PPS have a tendency to be stiffer with decreasing IOP as compared to increasing IOP.

Conclusions: Our results demonstrate the feasibility of using our ultrasonic elastography system to investigate the stiffness mapping of posterior eye with high resolution in both increasing and decreasing IOPs, making this technique potentially useful for glaucoma.

Keywords: Glaucoma; High frequency ultrasound elastography; Optic nerve head; Peripapillary sclera; Shear wave propagation.

MeSH terms

Animals
Biomechanical Phenomena
Elastic Modulus
Elasticity Imaging Techniques / methods*
Equipment Design
Glaucoma / diagnostic imaging
In Vitro Techniques
Optic Disk / physiology*
Phantoms, Imaging
Sclera / physiology*
Swine

Abstract

MeSH terms

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