Photovoltaic implant simulator reveals resolution limits in subretinal prosthesis

Zhijie Charles Chen, Bing-Yi Wang, Anna Kochnev Goldstein, Emma Butt, Keith Mathieson, Daniel Palanker

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)
29 Downloads (Pure)

Abstract

Objective.PRIMA, the photovoltaic subretinal prosthesis, restores central vision in patients blinded by atrophic age-related macular degeneration (AMD), with a resolution closely matching the 100µm pixel size of the implant. Improvement in resolution requires smaller pixels, but the resultant electric field may not provide sufficient stimulation strength in the inner nuclear layer (INL) or may lead to excessive crosstalk between neighboring electrodes, resulting in low contrast stimulation patterns. We study the approaches to electric field shaping in the retina for prosthetic vision with higher resolution and improved contrast.Approach.We present a new computational framework, Retinal Prosthesis Simulator (RPSim), that efficiently computes the electric field in the retina generated by a photovoltaic implant with thousands of electrodes. Leveraging the PRIMA clinical results as a benchmark, we use RPSim to predict the stimulus strength and contrast of the electric field in the retina with various pixel designs and stimulation patterns.Main results.We demonstrate that by utilizing monopolar pixels as both anodes and cathodes to suppress crosstalk, most patients may achieve resolution no worse than 48µm. Closer proximity between the electrodes and the INL, achieved with pillar electrodes, enhances the stimulus strength and contrast and may enable 24µm resolution with 20µm pixels, at least in some patients.Significance.A resolution of 24µm on the retina corresponds to a visual acuity of 20/100, which is over 4 times higher than the current best prosthetic acuity of 20/438, promising a significant improvement of central vision for many AMD patients.

Original languageEnglish
Article number055008
JournalJournal of Neural Engineering
Volume19
Issue number5
Early online date2 Sept 2022
DOIs
Publication statusPublished - 27 Sept 2022

Keywords

  • subretinal prosthesis
  • implant
  • prosthetic vision
  • inner nuclear layer
  • retina

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