A Treatise of the Physical Aspects of Phosphenes and Single-Cell Selectivity in Retinal Stimulation

DL, Villarreal; Wh, Krautschneider

doi:10.19070/2572-7389-170008

Cited by 1 publication

(2 citation statements)

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“…Previous retinal stimulation models have been developed using cell physiology data, but with highly idealized FEMs of the implant and surrounding tissue. These models report activation thresholds orders of magnitude lower than clinical research studies [ 14 ]–[ 16 ], [ 31 ], [ 32 ]. By implementing an existing biophysical model into an anatomically realistic FEM, we predict absolute RGC activation thresholds in an amplitude range similar to perceptual thresholds.…”

Section: Resultsmentioning

confidence: 99%

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A Patient-Specific Computational Framework for the Argus II Implant

Finn

Zander

Graham

et al. 2020

IEEE Open J. Eng. Med. Biol.

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Retinal prosthesis performance is limited by the variability of elicited phosphenes. The stimulating electrode's position with respect to retinal ganglion cells (RGCs) affects both perceptual threshold and phosphene shape. We created a modeling framework incorporating patient-specific anatomy and electrode location to investigate RGC activation and predict inter-electrode differences for one Argus II user. Methods: We used ocular imaging to build a three-dimensional finite element model characterizing retinal morphology and implant placement. To predict the neural response to stimulation, we coupled electric fields with multi-compartment cable models of RGCs. We evaluated our model predictions by comparing them to patientreported perceptual threshold measurements. Results: Our model was validated by the ability to replicate clinical impedance and threshold values, along with known neurophysiological trends. Inter-electrode threshold differences in silico correlated with in vivo results. Conclusions: We developed a patient-specific retinal stimulation framework to quantitatively predict RGC activation and better explain phosphene variations.

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Section: Resultsmentioning

confidence: 99%

“…Unfortunately, it is not currently possible to measure retinal tissue anisotropy in patients. Secondly, several studies have reported effects of foveal eccentricity on perceptual threshold, as a result of varying RGC density [ 8 ], [ 31 ], [ 35 ]. Future models should incorporate RGC density.…”

Section: Discussionmentioning

confidence: 99%