High resolution optical coherence elastography of retina under prosthetic electrode

Runze Li; Zhaodong Du; Xuejun Qian; Yan Li; Juan-Carlos Martinez-Camarillo; Laiming Jiang; Mark S Humayun; Zhongping Chen; Qifa Zhou

doi:10.21037/qims-20-1137

High resolution optical coherence elastography of retina under prosthetic electrode

Quant Imaging Med Surg. 2021 Mar;11(3):918-927. doi: 10.21037/qims-20-1137.

Authors

Runze Li^{1

2}, Zhaodong Du², Xuejun Qian^{1

2}, Yan Li^{3

4}, Juan-Carlos Martinez-Camarillo², Laiming Jiang², Mark S Humayun^{1

2}, Zhongping Chen^{3

4}, Qifa Zhou^{1

2}

Affiliations

¹ Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA.
² USC Roski Eye Institute, University of Southern California, Los Angeles, CA, USA.
³ Beckman Laser Institute, University of California, Irvine, CA, USA.
⁴ Department of Biomedical Engineering, University of California, Irvine, CA, USA.

Abstract

Background: Quantitatively investigating the biomechanics of retina with a retinal prosthetic electrode, we explored the effects of the prosthetic electrode on the retina, and further supplemented data for a potential clinical trial.

Methods: Biomechanical properties were assessed with a high resolution optical coherence tomography (OCT) based elastography (OCE) system. A shaker was used to initiate elastic waves and an OCT system was used to track axial displacement along with wave propagation. Rabbits received surgery to implant the retinal prosthetic electrode, and elastic wave speed was measured before and after implantation; anatomical B-mode images were also acquired.

Results: Spatial-temporal maps of each layer in retina with and without prosthetic electrodes were acquired. Elastic wave speed of nerve fiber to inner plexiform layer, inner nuclear to outer nuclear layer, retinal pigmented epithelium layer and choroid to sclera layer without prosthetic electrode were found to be 3.66±0.36, 5.33±0.07, 6.85±0.37, and 9.69±0.24 m/s, respectively. With prosthetic electrode, the elastic wave speed was found to be 4.09±0.26, 5.14±0.11, 6.88±0.70, and 9.99±0.73 m/s, respectively in each layer.

Conclusions: Our results show that the elastic wave speed in each layer of retina is slightly faster with the retinal electrode, and further demonstrate that the retinal prosthetic electrode does not affect biomechanical properties significantly. In the future, we expect OCE technology to be used by clinicians where it could become part of routine testing and evaluation of the biomechanical properties of the retina in response to long term use of prosthetic electrodes in patients.

Keywords: Optical coherence elastography; elastic wave propagation; mechanical shaker; retinal prosthetic electrode.