June 2023
Volume 64, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2023
Optical Coherence Elastography for the mechanical characterization of porcine lenses
Author Affiliations & Notes
  • iulen Cabeza
    Aragón Institute of Engineering Research (i3A), University of Zaragoza, Spain
  • Vahoura Tahsini
    ARTORG Center for Biomedical Engineering Research, University of Bern, Switzerland
  • Sabine Kling
    ARTORG Center for Biomedical Engineering Research, University of Bern, Switzerland
    Institute for Biomedical Engineering, Department of Information Technology and Electrical Engineering, ETH Zurich, Switzerland
  • Footnotes
    Commercial Relationships   iulen Cabeza None; Vahoura Tahsini None; Sabine Kling None
  • Footnotes
    Support  European Union’s HORIZON 2020 research and innovation programme under grant agreement No 956720, and from the AMBIZIONE career grant PZ00P2_174113 from the Swiss National Science Foundation. Iulen also acknowledges ESB mobility award and Universidad de Zaragoza, Fundación Bancaria Ibercaja y Fundación CAI IT 14/12.
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 4393. doi:
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    • Get Citation

      iulen Cabeza, Vahoura Tahsini, Sabine Kling; Optical Coherence Elastography for the mechanical characterization of porcine lenses. Invest. Ophthalmol. Vis. Sci. 2023;64(8):4393.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : To characterize the porovisco-hyperelastic properties of porcine lenses through compression tests using optical coherence elastography (OCE) and inverse finite element analysis (iFEA).

Methods : 13 porcine lenses obtained from a local slaughterhouse were used. The test initially consisted in axially compressing the lens’ thickness (LT) to 6.00 mm whilst the force required to achieve this deformation state was registered. Then, a sinusoidal micro-displacement (~34 um) with a period of 5 s controlled by a piezoelectric actuator was applied to the compressed lens whilst 2D strain maps of the lens (Fig. A) were computed using OCE. The overall test recording was 7.6 s, consisting of 256 subsequent B-scans, and the piezoelectric actuator began to displace at 0.8 s from the start of the acquisition (Fig. B). The strain maps and the force applied were used to determine the mechanical properties of the lens using iFEA. Different modeling approaches, including poroviscoelastic, viscoelastic, and stiffness gradient models, were considered.

Results : The accuracy of the OCE strains was confirmed by comparing them to the known LT strains, used as reference in this displacement-controlled test (Fig. C). We found that the averaged anterior strains were larger than those of the nucleus (7.32 10-3 compared to 6.11 10-3 ,respectively). The posterior cortex presented the lowest strains at 5.37 10-3. The results also demonstrated a pronounced viscoelastic behavior of the lens nucleus, as evidenced by the time delay between the LT strains and those of the nucleus at the midpoint of the sinusoidal displacement (t=2.50 s). The nucleus 'delay' ranged from 2.50 10-2 to 8.51 10-2 s and the LT ranged from 7.55 to 8.10 mm. The experimentally observed strain oscillation amplitudes could be reconstructed in the iFEA with a MAPE lower than 5% considering the lens stiffness gradient model.

Conclusions : The findings suggest that the anterior cortex is softer than the lens nucleus for most of the lenses (9/13) under investigation. The posterior cortex appears to be the stiffest part. The lens nucleus exhibits a rapid viscoelastic effect (τ~1s using Prony Series).

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

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