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Bhuckory MB, Monkongpitukkul N, Shin A, Goldstein AK, Jensen N, Shah SV, Pham-Howard D, Butt E, Dalal R, Galambos L, Mathieson K, Kamins T, Palanker D. Enhancing Prosthetic Vision by Upgrade of a Subretinal Photovoltaic Implant in situ. bioRxiv 2024:2024.04.15.589465. [PMID: 38659843 PMCID: PMC11042236 DOI: 10.1101/2024.04.15.589465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
In patients with atrophic age-related macular degeneration, subretinal photovoltaic implant (PRIMA) provided visual acuity up to 20/440, matching its 100μm pixels size. Next-generation implants with smaller pixels should significantly improve the acuity. This study in rats evaluates removal of a subretinal implant, replacement with a newer device, and the resulting grating acuity in-vivo. Six weeks after the initial implantation with planar and 3-dimensional devices, the retina was re-detached, and the devices were successfully removed. Histology demonstrated a preserved inner nuclear layer. Re-implantation of new devices into the same location demonstrated retinal re-attachment to a new implant. New devices with 22μm pixels increased the grating acuity from the 100μm capability of PRIMA implants to 28μm, reaching the limit of natural resolution in rats. Reimplanted devices exhibited the same stimulation threshold as for the first implantation of the same implants in a control group. This study demonstrates the feasibility of safely upgrading the subretinal photovoltaic implants to improve prosthetic visual acuity.
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Affiliation(s)
- Mohajeet B Bhuckory
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94303, USA
- Department of Ophthalmology, Stanford University, Stanford, CA, USA
| | - Nicharee Monkongpitukkul
- Department of Ophthalmology, Stanford University, Stanford, CA, USA
- Department of Ophthalmology, Faculty of Medicine, Prince of Songkla University, Thailand
| | - Andrew Shin
- Department of Material Science, Stanford University, Stanford, CA, USA
| | | | - Nathan Jensen
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Sarthak V Shah
- Department of Ophthalmology, Stanford University, Stanford, CA, USA
| | - Davis Pham-Howard
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94303, USA
- Department of Ophthalmology, Stanford University, Stanford, CA, USA
| | - Emma Butt
- Department of Physics, University of Strathclyde, Glasgow, Scotland, UK
| | - Roopa Dalal
- Department of Ophthalmology, Stanford University, Stanford, CA, USA
| | - Ludwig Galambos
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94303, USA
| | - Keith Mathieson
- Department of Physics, University of Strathclyde, Glasgow, Scotland, UK
| | - Theodore Kamins
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Daniel Palanker
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94303, USA
- Department of Ophthalmology, Stanford University, Stanford, CA, USA
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Bhuckory M, Wang BY, Chen ZC, Shin A, Pham-Howard D, Shah S, Monkongpitukkul N, Galambos L, Kamins T, Mathieson K, Palanker D. 3D electronic implants in subretinal space: long-term follow-up in rodents. bioRxiv 2023:2023.07.25.550561. [PMID: 37546971 PMCID: PMC10402070 DOI: 10.1101/2023.07.25.550561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Photovoltaic subretinal prosthesis (PRIMA) enables restoration of sight via electrical stimulation of the interneurons in degenerated retina, with resolution limited by the 100 μm pixel size. Since decreasing the pixel size below 75 μm in the current bipolar geometry is impossible, we explore the possibility of using smaller pixels based on a novel 3-dimensional honeycomb-shaped design. We assessed the long-term biocompatibility and stability of these arrays in rats by investigating the anatomical integration of the retina with flat and 3D implants and response to electrical stimulation over lifetime - up to 9 months post-implantation in aged rats. With both flat and 3D implants, VEP amplitude decreased after the day of implantation by more than 3-fold, and gradually recovered over about 3 months. With 25 µm high honeycomb walls, the majority of bipolar cells migrate into the wells, while amacrine and ganglion cells remain above the cavities, which is essential for selective network-mediated stimulation of the second-order neurons. Retinal thickness and full-field stimulation threshold with 40 µm-wide honeycomb pixels were comparable to those with planar devices - 0.05 mW/mm2 with 10ms pulses. However, fewer cells from the inner nuclear layer migrated into the 20 µm-wide wells, and stimulation threshold increased over 5 months, before stabilizing at about 0.08 mW/mm2. Such threshold is significantly lower than 1.8 mW/mm2 with a previous design of flat bipolar pixels, confirming the promise of the 3D honeycomb-based approach to high resolution subretinal prosthesis.
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Affiliation(s)
- Mohajeet Bhuckory
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
- Department of Ophthalmology, Stanford University, Stanford, CA, USA
| | - Bing-Yi Wang
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Zhijie Charles Chen
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Andrew Shin
- Department of Material Science, Stanford University, Stanford, CA, USA
| | - Davis Pham-Howard
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
- Department of Ophthalmology, Stanford University, Stanford, CA, USA
| | - Sarthak Shah
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
| | - Nicharee Monkongpitukkul
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
- Department of Ophthalmology, Stanford University, Stanford, CA, USA
| | - Ludwig Galambos
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
| | - Theodore Kamins
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Keith Mathieson
- Department of Physics, Institute of Photonics, University of Strathclyde, Glasgow, Scotland, UK
| | - Daniel Palanker
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
- Department of Ophthalmology, Stanford University, Stanford, CA, USA
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