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Bhuckory MB, 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. Biomaterials 2024; 311:122674. [PMID: 38897028 PMCID: PMC11298295 DOI: 10.1016/j.biomaterials.2024.122674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 06/12/2024] [Accepted: 06/15/2024] [Indexed: 06/21/2024]
Abstract
Clinical results with photovoltaic subretinal prosthesis (PRIMA) demonstrated restoration of sight via electrical stimulation of the interneurons in degenerated retina, with resolution matching the 100 μm pixel size. Since scaling the pixels below 75 μm in the current bipolar planar geometry will significantly limit the penetration depth of the electric field and increase stimulation threshold, 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 32-36 weeks post-implantation in aged rats. With both flat and 3D implants, signals elicited in the visual cortex decreased after the day of implantation by more than 3-fold, and gradually recovered over the next 12-16 weeks. 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 retina. 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 10 ms pulses. However, fewer cells from the inner nuclear layer migrated into the 20 μm-wide wells, and stimulation threshold increased over 12-16 weeks, before stabilizing at about 0.08 mW/mm2. Such threshold is still 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 B Bhuckory
- Department of Ophthalmology, Stanford University, Stanford, CA, USA; Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA.
| | - Bing-Yi Wang
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Zhijie C Chen
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Andrew Shin
- Department of Material Science, Stanford University, Stanford, CA, USA
| | - Davis Pham-Howard
- Department of Ophthalmology, Stanford University, Stanford, CA, USA; Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
| | - Sarthak Shah
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
| | - Nicharee Monkongpitukkul
- Department of Ophthalmology, Stanford University, Stanford, CA, USA; Hansen Experimental Physics Laboratory, 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
- Department of Ophthalmology, Stanford University, Stanford, CA, USA; Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
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Xu Z, Kunala K, Murphy P, Patak L, Puthussery T, McGregor J. Foveal Retinal Ganglion Cells Develop Altered Calcium Dynamics Weeks After Photoreceptor Ablation. OPHTHALMOLOGY SCIENCE 2024; 4:100520. [PMID: 38881601 PMCID: PMC11179405 DOI: 10.1016/j.xops.2024.100520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 02/28/2024] [Accepted: 03/14/2024] [Indexed: 06/18/2024]
Abstract
Purpose Physiological changes in retinal ganglion cells (RGCs) have been reported in rodent models of photoreceptor (PR) loss, but this has not been investigated in primates. By expressing both a calcium indicator (GCaMP6s) and an optogenetic actuator (ChrimsonR) in foveal RGCs of the macaque, we reactivated RGCs in vivo and assessed their response in the weeks and years after PR loss. Design We used an in vivo calcium imaging approach to record optogenetically evoked activity in deafferented RGCs in primate fovea. Cellular scale recordings were made longitudinally over a 10-week period after PR ablation and compared with responses from RGCs that had lost PR input >2 years prior. Participants Three eyes received PR ablation, the right eye of a male Macaca mulatta (M1), the left eye of a female Macaca fascicularis (M2), and the right eye of a male Macaca fascicularis (M3). Two animals were used for in vivo recording, 1 for histological assessment. Methods Cones were ablated with an ultrafast laser delivered through an adaptive optics scanning light ophthalmoscope (AOSLO). A 0.5 second pulse of 25 Hz 660 nm light optogenetically stimulated RGCs, and the resulting GCaMP fluorescence signal was recorded using an AOSLO. Measurements were repeated over 10 weeks immediately after PR ablation, at 2.3 years and in control RGCs. Main Outcome Measures The calcium rise time, decay constant, and sensitivity index of optogenetic-mediated RGC were derived from GCaMP fluorescence recordings from 221 RGCs (animal M1) and 218 RGCs (animal M2) in vivo. Results After PR ablation, the mean decay constant of the calcium response in RGCs decreased 1.5-fold (standard deviation 1.6 ± 0.5 seconds to 0.6 ± 0.3 seconds) over the 10-week observation period in subject 1 and 2.1-fold (standard deviation 2.5 ± 0.5 seconds to 1.2 ± 0.2 seconds) within 8 weeks in subject 2. Calcium rise time and sensitivity index were stable. Optogenetic reactivation remained possible 2.3 years after PR ablation. Conclusions Altered calcium dynamics developed in primate foveal RGCs in the weeks after PR ablation. The mean decay constant of optogenetic-mediated calcium responses decreased 1.5- to twofold. This is the first report of this phenomenon in primate retina and further work is required to understand the role these changes play in cell survival and activity. Financial Disclosures Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
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Affiliation(s)
- Zhengyang Xu
- Institute of Optics, University of Rochester, Rochester, New York
| | - Karteek Kunala
- Center for Visual Science, University of Rochester Medical Center, Rochester, New York
| | - Peter Murphy
- Institute of Optics, University of Rochester, Rochester, New York
| | - Laura Patak
- Herbert Wertheim School of Optometry & Vision Science, University of California Berkeley, Berkeley, California
- Vision Science Graduate Program, University of California Berkeley, Berkeley, California
| | - Teresa Puthussery
- Herbert Wertheim School of Optometry & Vision Science, University of California Berkeley, Berkeley, California
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, California
| | - Juliette McGregor
- Center for Visual Science, University of Rochester Medical Center, Rochester, New York
- Department of Ophthalmology, University of Rochester Medical Center, Rochester, New York
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He Y, Toft-Nielsen J, Legge G, Montezuma SR. Pattern-reversal visual evoked potentials in prosthetic vision and simulated visual reduction. BMJ Open Ophthalmol 2024; 9:e001705. [PMID: 39103235 PMCID: PMC11308878 DOI: 10.1136/bmjophth-2024-001705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Accepted: 07/12/2024] [Indexed: 08/07/2024] Open
Abstract
OBJECTIVE To quantitatively evaluate visual evoked potentials (VEPs) in prosthetic vision and simulated visual reduction. METHODS AND ANALYSIS Four blind patients implanted with the Argus II retinal prosthesis and seven sighted controls participated. VEPs were recorded with pattern-reversal stimuli (2 cycles of a horizontal square wave grating, 0.1 cycle/degree) at 1.07 reversals per second (rps) for Argus II subjects and 3.37 rps for controls. Argus II patients had both eyes patched, viewing the pattern solely through their implant. Controls viewed the pattern monocularly, either with their best-corrected vision or with simulated visual reduction (field restriction, added blur or reduced display contrast). RESULTS VEPs recorded in Argus II patients displayed a similar shape to normal VEPs when controls viewed the pattern without simulated visual reduction. In sighted controls, adding blur significantly delayed the P100 peak time by 8.7 ms, 95% CI (0.9, 16.6). Reducing stimulus contrast to 32% and 6% of full display contrast significantly decreased P100 amplitude to 55% (37%, 82%) and 20% (13%, 31%), respectively. Restriction on the field of view had no impact on either the amplitude or the peak latency of P100. CONCLUSION The early visual cortex in retinal prosthesis users remains responsive to retinal input, showing a similar response profile to that of sighted controls. Pattern-reversal VEP offers valuable insights for objectively evaluating artificial vision therapy systems (AVTSs) when selecting, fitting and training implant users, but the uncertainties in the exact timing and location of electrode stimulation must be considered when interpreting the results.
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Affiliation(s)
- Yingchen He
- Department of Psychology, North Carolina State University, Raleigh, North Carolina, USA
| | - Jonathon Toft-Nielsen
- Department of Biomedical Engineering, University of Miami, Coral Gables, Florida, USA
- Intelligent Hearing Systems, Miami, Florida, USA
| | - Gordon Legge
- Department of Psychology, University of Minnesota Twin Cities, Minneapolis, Minnesota, USA
| | - Sandra R Montezuma
- Ophthalmology and Visual Neurosciences, University of Minnesota Twin Cities, Minneapolis, Minnesota, USA
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Kalloniatis M, Wang H, Phu J, Tong J, Armitage J. Optical coherence tomography angiography in the diagnosis of ocular disease. Clin Exp Optom 2024; 107:482-498. [PMID: 38452795 DOI: 10.1080/08164622.2024.2323603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 02/21/2024] [Indexed: 03/09/2024] Open
Abstract
Clinical imaging provided by optical coherence tomography (OCT) and its variant, OCT-angiography (OCT-A), has revolutionised eyecare practice. The imaging techniques allow for the identification and quantification of ocular structures, supporting the diagnosis and prognosis of eye disease. In this review, an overview of the usefulness of OCT-A imaging in the diagnosis and management of a range of ocular conditions is provided when used in isolation or in combination with other imaging modalities and measures of visual function (visual field results). OCT-A imaging has the capacity to identify and quantify ocular vasculature non-invasively, thereby assisting the clinician in the diagnosis or to determine the efficacy of intervention in ocular conditions impacting retinal vasculature. Thus, additional clinically useful information can be obtained in eye diseases involving conditions such as those impacting retinal vessel occlusion, in diabetic retinopathy, inherited retinal dystrophy, age-related macular degeneration, choroidal neovascularisation and optic nerve disorders. Through a clinical case series, various ocular conditions are reviewed, and the impact of OCT-A imaging is discussed. Although OCT-A imaging has great promise and is already used in clinical management, there is a lack of set standards to characterise altered vascular features in disease and consequently for prognostication, primarily due to a lack of large-scale clinical trials and variability in OCT-A algorithms when generating quantitative parameters.
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Affiliation(s)
- Michael Kalloniatis
- School of Medicine (Optometry), Deakin University, Waurn Ponds, VIC, Australia
- School of Optometry and Vision Science, University of New South Wales, Kensington, NSW, Australia
| | - Henrietta Wang
- School of Optometry and Vision Science, University of New South Wales, Kensington, NSW, Australia
- Centre for Eye Health, University of New South Wales, Kensington, NSW, Australia
| | - Jack Phu
- School of Medicine (Optometry), Deakin University, Waurn Ponds, VIC, Australia
- School of Optometry and Vision Science, University of New South Wales, Kensington, NSW, Australia
| | - Janelle Tong
- School of Optometry and Vision Science, University of New South Wales, Kensington, NSW, Australia
- Centre for Eye Health, University of New South Wales, Kensington, NSW, Australia
| | - James Armitage
- School of Medicine (Optometry), Deakin University, Waurn Ponds, VIC, Australia
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Schulz A, Knoll T, Jaeger T, Le Harzic R, Stracke F, Wien SL, Olsommer Y, Meiser I, Wagner S, Rammensee M, Kurz O, Klesy S, Sermeus L, Julich-Haertel H, Schweitzer Y, Januschowski K, Velten T, Szurman P. Photovoltaic, wireless wide-field epiretinal prosthesis to treat retinitis pigmentosa. Acta Ophthalmol 2024. [PMID: 38923194 DOI: 10.1111/aos.16733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 06/11/2024] [Indexed: 06/28/2024]
Abstract
PURPOSE To develop and evaluate a photovoltaic, wireless wide-field epiretinal prosthesis for the treatment of retinitis pigmentosa. METHODS A mosaic array of thinned silicon-based photodiodes with integrated thin-film stimulation electrodes was fabricated with a flexible polyimide substrate film to form a film-based miniaturized electronic system with wireless optical power and signal transmission and integrated electrostimulation. Manufactured implants were characterized with respect to their optoelectronic performance and biocompatibility following DIN EN ISO 10993. RESULTS A 14 mm diameter prosthesis containing 1276 pixels with a maximum sensitivity at a near infrared wavelength of 905 nm and maximized stimulation current density 30-50 μm below the electrodes was developed for direct activation of retinal ganglion cells during epiretinal stimulation. Fabricated prostheses demonstrated mucosal tolerance and the preservation of both metabolic activity, proliferation and membrane integrity of human fibroblasts as well as the retinal functions of bovine retinas. Illumination of the prosthesis, which was placed epiretinally on an isolated perfused bovine retina, with infrared light resulted in electrophysiological recordings reminiscent of an a-wave (hyperpolarization) and b-wave (depolarization). CONCLUSIONS A photovoltaic, wireless wide-field epiretinal prosthesis for the treatment of retinitis pigmentosa using near infrared light for signal transmission was designed, manufactured and its biocompatibility and functionality demonstrated in vitro and ex vivo.
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Affiliation(s)
- André Schulz
- Eye Clinic Sulzbach, Knappschaft Hospital Saar, Sulzbach, Germany
- Klaus Heimann Eye Research Institute, Sulzbach, Germany
| | - Thorsten Knoll
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | | | - Ronan Le Harzic
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | - Frank Stracke
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | - Sascha L Wien
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | - Yves Olsommer
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | - Ina Meiser
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | - Sylvia Wagner
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | | | | | | | - Loic Sermeus
- Eye Clinic Sulzbach, Knappschaft Hospital Saar, Sulzbach, Germany
| | - Henrike Julich-Haertel
- Eye Clinic Sulzbach, Knappschaft Hospital Saar, Sulzbach, Germany
- Klaus Heimann Eye Research Institute, Sulzbach, Germany
| | | | - Kai Januschowski
- Eye Clinic Sulzbach, Knappschaft Hospital Saar, Sulzbach, Germany
- Klaus Heimann Eye Research Institute, Sulzbach, Germany
| | - Thomas Velten
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | - Peter Szurman
- Eye Clinic Sulzbach, Knappschaft Hospital Saar, Sulzbach, Germany
- Klaus Heimann Eye Research Institute, Sulzbach, Germany
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Xu Z, Kunala K, Murphy P, Patak L, Puthussery T, McGregor J. Foveal RGCs develop altered calcium dynamics weeks after photoreceptor ablation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.05.30.542908. [PMID: 37398439 PMCID: PMC10312553 DOI: 10.1101/2023.05.30.542908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Objective or purpose Physiological changes in retinal ganglion cells (RGCs) have been reported in rodent models of photoreceptor (PR) loss but this has not been investigated in primates. By expressing both a calcium indicator (GCaMP6s) and an optogenetic actuator (ChrimsonR) in foveal RGCs of the macaque, we reactivated RGCs in vivo and assessed their response in the weeks and years following PR loss. Design We used an in vivo calcium imaging approach to record optogenetically evoked activity in deafferented RGCs in primate fovea. Cellular scale recordings were made longitudinally over a 10 week period following photoreceptor ablation and compared to responses from RGCs that had lost photoreceptor input more than two years prior. Participants Three eyes received photoreceptor ablation, OD of a male Macaca mulatta (M1), OS of a female Macaca fascicularis (M2) and OD of a male Macaca fascicularis (M3). Two animals were used for in vivo recording, one for histological assessment. Methods Cones were ablated with an ultrafast laser delivered through an adaptive optics scanning light ophthalmoscope (AOSLO). A 0.5 s pulse of 25Hz 660nm light optogenetically stimulated RGCs, and the resulting GCaMP fluorescence signal was recorded using AOSLO. Measurements were repeated over 10 weeks immediately after PR ablation, at 2.3 years and in control RGCs. Main Outcome measures The calcium rise time, decay constant and sensitivity index of optogenetic mediated RGC were derived from GCaMP fluorescence recordings from 221 RGCs (Animal M1) and 218 RGCs (Animal M2) in vivo. Results Following photoreceptor ablation, the mean decay constant of the calcium response in RGCs decreased 1.5 fold (1.6±0.5 s to 0.6±0.3 s SD) over the 10 week observation period in subject 1 and 2.1 fold (2.5±0.5 s to 1.2±0.2 s SD) within 8 weeks in subject 2. Calcium rise time and sensitivity index were stable. Optogenetic reactivation remained possible 2.3 years after PR ablation. Conclusions Altered calcium dynamics developed in primate foveal RGCs in the weeks after photoreceptor ablation. The mean decay constant of optogenetic mediated calcium responses decreased 1.5 - 2-fold. This is the first report of this phenomenon in primate retina and further work is required to understand the role these changes play in cell survival and activity.
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Affiliation(s)
- Zhengyang Xu
- Institute of Optics, University of Rochester, Rochester, New York, UNITED STATES
| | - Karteek Kunala
- Center for Visual Science, University of Rochester Medical Center, Rochester, New York, UNITED STATES
| | - Peter Murphy
- Institute of Optics, University of Rochester, Rochester, New York, UNITED STATES
| | - Laura Patak
- Herbert Wertheim School of Optometry & Vision Science, University of California Berkeley, Berkeley, California, UNITED STATES
- Vision Science Graduate Program, University of California Berkeley, Berkeley, California, UNITED STATES
| | - Teresa Puthussery
- Herbert Wertheim School of Optometry & Vision Science, University of California Berkeley, Berkeley, California, UNITED STATES
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, California, UNITED STATES
| | - Juliette McGregor
- Center for Visual Science, University of Rochester Medical Center, Rochester, New York, UNITED STATES
- Department of Ophthalmology, University of Rochester Medical Center, Rochester, New York, UNITED STATES
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Hirami Y, Mandai M, Sugita S, Maeda A, Maeda T, Yamamoto M, Uyama H, Yokota S, Fujihara M, Igeta M, Daimon T, Fujita K, Ito T, Shibatani N, Morinaga C, Hayama T, Nakamura A, Ueyama K, Ono K, Ohara H, Fujiwara M, Yamasaki S, Watari K, Bando K, Kawabe K, Ikeda A, Kimura T, Kuwahara A, Takahashi M, Kurimoto Y. Safety and stable survival of stem-cell-derived retinal organoid for 2 years in patients with retinitis pigmentosa. Cell Stem Cell 2023; 30:1585-1596.e6. [PMID: 38065067 DOI: 10.1016/j.stem.2023.11.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 09/03/2023] [Accepted: 11/08/2023] [Indexed: 12/18/2023]
Abstract
Transplantation of induced pluripotent stem cell (iPSC)-derived retinal organoids into retinal disease animal models has yielded promising results, and several clinical trials on iPSC-derived retinal pigment epithelial cell transplantation have confirmed its safety. In this study, we performed allogeneic iPSC-derived retinal organoid sheet transplantation in two subjects with advanced retinitis pigmentosa (jRCTa050200027). The primary endpoint was the survival and safety of the transplanted retinal organoid sheets in the first year post-transplantation. The secondary endpoints were the safety of the transplantation procedure and visual function evaluation. The grafts survived in a stable condition for 2 years, and the retinal thickness increased at the transplant site without serious adverse events in both subjects. Changes in visual function were less progressive than those of the untreated eye during the follow-up. Allogeneic iPSC-derived retinal organoid sheet transplantation is a potential therapeutic approach, and the treatment's safety and efficacy for visual function should be investigated further.
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Affiliation(s)
- Yasuhiko Hirami
- Department of Ophthalmology, Kobe City Eye Hospital, Kobe 650-0047, Japan; Department of Ophthalmology, Kobe City Medical Center General Hospital, Kobe 650-0047, Japan; Laboratory for Retinal Regeneration, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan.
| | - Michiko Mandai
- Department of Ophthalmology, Kobe City Eye Hospital, Kobe 650-0047, Japan; Laboratory for Retinal Regeneration, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan; Research Center, Kobe City Eye Hospital, Kobe 650-0047, Japan; RIKEN Program for Drug Discovery and Medical Technology Platforms, Yokohama 230-0045, Japan
| | - Sunao Sugita
- Department of Ophthalmology, Kobe City Eye Hospital, Kobe 650-0047, Japan; Laboratory for Retinal Regeneration, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
| | - Akiko Maeda
- Department of Ophthalmology, Kobe City Eye Hospital, Kobe 650-0047, Japan; Laboratory for Retinal Regeneration, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan; Research Center, Kobe City Eye Hospital, Kobe 650-0047, Japan
| | - Tadao Maeda
- Department of Ophthalmology, Kobe City Eye Hospital, Kobe 650-0047, Japan; Research Center, Kobe City Eye Hospital, Kobe 650-0047, Japan
| | - Midori Yamamoto
- Department of Ophthalmology, Kobe City Eye Hospital, Kobe 650-0047, Japan; Research Center, Kobe City Eye Hospital, Kobe 650-0047, Japan
| | - Hirofumi Uyama
- Department of Ophthalmology, Kobe City Eye Hospital, Kobe 650-0047, Japan; Department of Ophthalmology, Kobe City Medical Center General Hospital, Kobe 650-0047, Japan
| | - Satoshi Yokota
- Department of Ophthalmology, Kobe City Eye Hospital, Kobe 650-0047, Japan; Department of Ophthalmology, Kobe City Medical Center General Hospital, Kobe 650-0047, Japan; Laboratory for Retinal Regeneration, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
| | - Masashi Fujihara
- Department of Ophthalmology, Kobe City Eye Hospital, Kobe 650-0047, Japan; Department of Ophthalmology, Kobe City Medical Center General Hospital, Kobe 650-0047, Japan; Laboratory for Retinal Regeneration, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
| | - Masataka Igeta
- Department of Biostatistics, Hyogo Medical University, Nishinomiya 663-8501, Japan
| | - Takashi Daimon
- Department of Biostatistics, Hyogo Medical University, Nishinomiya 663-8501, Japan
| | - Kanako Fujita
- Research Center, Kobe City Eye Hospital, Kobe 650-0047, Japan
| | - Tomoko Ito
- Research Center, Kobe City Eye Hospital, Kobe 650-0047, Japan
| | - Naoki Shibatani
- Research Center, Kobe City Eye Hospital, Kobe 650-0047, Japan
| | - Chikako Morinaga
- RIKEN Program for Drug Discovery and Medical Technology Platforms, Yokohama 230-0045, Japan
| | - Tetsuya Hayama
- Regenerative & Cellular Medicine Kobe Center, Sumitomo Pharma Co. Ltd., Kobe 650-0047, Japan
| | - Aya Nakamura
- Technology Research & Development Division, Sumitomo Pharma Co. Ltd., Kobe 650-0047, Japan
| | - Kazuki Ueyama
- Technology Research & Development Division, Sumitomo Pharma Co. Ltd., Kobe 650-0047, Japan
| | - Keiichi Ono
- Technology Research & Development Division, Sumitomo Pharma Co. Ltd., Kobe 650-0047, Japan
| | - Hidetaka Ohara
- Regenerative & Cellular Medicine Office, Sumitomo Pharma Co. Ltd., Tokyo 103-6012, Japan
| | - Masayo Fujiwara
- Regenerative & Cellular Medicine Kobe Center, Sumitomo Pharma Co. Ltd., Kobe 650-0047, Japan
| | - Suguru Yamasaki
- Regenerative & Cellular Medicine Kobe Center, Sumitomo Pharma Co. Ltd., Kobe 650-0047, Japan
| | - Kenji Watari
- Regenerative & Cellular Medicine Kobe Center, Sumitomo Pharma Co. Ltd., Kobe 650-0047, Japan
| | - Kiyoko Bando
- Regenerative & Cellular Medicine Office, Sumitomo Pharma Co. Ltd., Tokyo 103-6012, Japan
| | - Keigo Kawabe
- Regenerative & Cellular Medicine Office, Sumitomo Pharma Co. Ltd., Tokyo 103-6012, Japan
| | - Atsushi Ikeda
- Regenerative & Cellular Medicine Kobe Center, Sumitomo Pharma Co. Ltd., Kobe 650-0047, Japan
| | - Toru Kimura
- Regenerative & Cellular Medicine Kobe Center, Sumitomo Pharma Co. Ltd., Kobe 650-0047, Japan; Regenerative & Cellular Medicine Office, Sumitomo Pharma Co. Ltd., Tokyo 103-6012, Japan
| | - Atsushi Kuwahara
- Regenerative & Cellular Medicine Kobe Center, Sumitomo Pharma Co. Ltd., Kobe 650-0047, Japan
| | - Masayo Takahashi
- Department of Ophthalmology, Kobe City Eye Hospital, Kobe 650-0047, Japan
| | - Yasuo Kurimoto
- Department of Ophthalmology, Kobe City Eye Hospital, Kobe 650-0047, Japan; Department of Ophthalmology, Kobe City Medical Center General Hospital, Kobe 650-0047, Japan; Laboratory for Retinal Regeneration, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
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Paez-Escamilla M, Alabek ML, Beale O, Prensky CJ, Lejoyeux R, Friberg TR, Sahel JA, Rosin B. An Optical Coherence Tomography-Based Measure as an Independent Estimate of Retinal Function in Retinitis Pigmentosa. Diagnostics (Basel) 2023; 13:3521. [PMID: 38066762 PMCID: PMC10706660 DOI: 10.3390/diagnostics13233521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 11/20/2023] [Accepted: 11/20/2023] [Indexed: 02/12/2024] Open
Abstract
BACKGROUND With the clinical advances in the field of gene therapy, the development of objective measures of visual function of patients with inherited retinal dystrophies (IRDs) is of utmost importance. Here, we propose one such measure. METHODS We retrospectively analyzed data from a cohort of 194 eyes of 97 genetically diagnosed patients with retinitis pigmentosa (RP), the most common IRD, followed at the UPMC Vision Institute. The analyzed data included the reflectivity ratio (RR) of the retinal nerve fiber layer (RNFL) to that of the entire retina, visual acuity (VA) and the thickness of the retinal outer nuclear layer (ONL) and the RNFL. RESULTS There was a strong positive correlation between the RR and VA. Both VA and the RR were negatively correlated with disease duration; VA, but not the RR, was negatively correlated with age. The RR correlated with the ONL but not with the RNFL thickness or the intraocular pressure. Age, RR, disease duration and ONL thickness were found to be independent predictors of VA by multivariate analysis. CONCLUSION The OCT RR could serve as an independent predictor of visual acuity, and by extension of retinal function, in genetically diagnosed RP patients. Such objective measures can be of great value in patient selection for therapeutic trials.
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Affiliation(s)
- Manuel Paez-Escamilla
- Department of Ophthalmology/UPMC Vision Institute, University of Pittsburgh Medical Center (UPMC), 1622 Locust Street, Pittsburgh, PA 15219, USA; (M.P.-E.); (M.L.A.); (O.B.); (C.J.P.); (R.L.); (T.R.F.); (J.-A.S.)
- Department of Ophthalmology, McGill University Health Centre, Montreal, QC H4A 3J1, Canada
| | - Michelle L. Alabek
- Department of Ophthalmology/UPMC Vision Institute, University of Pittsburgh Medical Center (UPMC), 1622 Locust Street, Pittsburgh, PA 15219, USA; (M.P.-E.); (M.L.A.); (O.B.); (C.J.P.); (R.L.); (T.R.F.); (J.-A.S.)
| | - Oliver Beale
- Department of Ophthalmology/UPMC Vision Institute, University of Pittsburgh Medical Center (UPMC), 1622 Locust Street, Pittsburgh, PA 15219, USA; (M.P.-E.); (M.L.A.); (O.B.); (C.J.P.); (R.L.); (T.R.F.); (J.-A.S.)
| | - Colin J. Prensky
- Department of Ophthalmology/UPMC Vision Institute, University of Pittsburgh Medical Center (UPMC), 1622 Locust Street, Pittsburgh, PA 15219, USA; (M.P.-E.); (M.L.A.); (O.B.); (C.J.P.); (R.L.); (T.R.F.); (J.-A.S.)
| | - Raphael Lejoyeux
- Department of Ophthalmology/UPMC Vision Institute, University of Pittsburgh Medical Center (UPMC), 1622 Locust Street, Pittsburgh, PA 15219, USA; (M.P.-E.); (M.L.A.); (O.B.); (C.J.P.); (R.L.); (T.R.F.); (J.-A.S.)
- Rothschild Foundation Hospital, 75019 Paris, France
- Institut Oeil Paupiere, Viry-Chatillon, 91170 Paris, France
| | - Thomas R. Friberg
- Department of Ophthalmology/UPMC Vision Institute, University of Pittsburgh Medical Center (UPMC), 1622 Locust Street, Pittsburgh, PA 15219, USA; (M.P.-E.); (M.L.A.); (O.B.); (C.J.P.); (R.L.); (T.R.F.); (J.-A.S.)
| | - Jose-Alain Sahel
- Department of Ophthalmology/UPMC Vision Institute, University of Pittsburgh Medical Center (UPMC), 1622 Locust Street, Pittsburgh, PA 15219, USA; (M.P.-E.); (M.L.A.); (O.B.); (C.J.P.); (R.L.); (T.R.F.); (J.-A.S.)
| | - Boris Rosin
- Department of Ophthalmology/UPMC Vision Institute, University of Pittsburgh Medical Center (UPMC), 1622 Locust Street, Pittsburgh, PA 15219, USA; (M.P.-E.); (M.L.A.); (O.B.); (C.J.P.); (R.L.); (T.R.F.); (J.-A.S.)
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9
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Haraguchi Y, Chiang TK, Yu M. Application of Electrophysiology in Non-Macular Inherited Retinal Dystrophies. J Clin Med 2023; 12:6953. [PMID: 37959417 PMCID: PMC10649281 DOI: 10.3390/jcm12216953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 11/02/2023] [Accepted: 11/03/2023] [Indexed: 11/15/2023] Open
Abstract
Inherited retinal dystrophies encompass a diverse group of disorders affecting the structure and function of the retina, leading to progressive visual impairment and, in severe cases, blindness. Electrophysiology testing has emerged as a valuable tool in assessing and diagnosing those conditions, offering insights into the function of different parts of the visual pathway from retina to visual cortex and aiding in disease classification. This review provides an overview of the application of electrophysiology testing in the non-macular inherited retinal dystrophies focusing on both common and rare variants, including retinitis pigmentosa, progressive cone and cone-rod dystrophy, bradyopsia, Bietti crystalline dystrophy, late-onset retinal degeneration, and fundus albipunctatus. The different applications and limitations of electrophysiology techniques, including multifocal electroretinogram (mfERG), full-field ERG (ffERG), electrooculogram (EOG), pattern electroretinogram (PERG), and visual evoked potential (VEP), in the diagnosis and management of these distinctive phenotypes are discussed. The potential for electrophysiology testing to allow for further understanding of these diseases and the possibility of using these tests for early detection, prognosis prediction, and therapeutic monitoring in the future is reviewed.
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Affiliation(s)
| | | | - Minzhong Yu
- Department of Ophthalmology, University Hospitals, Case Western Reserve University, Cleveland, OH 44106, USA
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10
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Ahn J, Yoo Y, Goo YS. Multiple consecutive-biphasic pulse stimulation improves spatially localized firing of retinal ganglion cells in the degenerate retina. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2023; 27:541-553. [PMID: 37884286 PMCID: PMC10613570 DOI: 10.4196/kjpp.2023.27.6.541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 08/08/2023] [Accepted: 08/22/2023] [Indexed: 10/28/2023]
Abstract
Retinal prostheses have shown some clinical success in restoring vision in patients with retinitis pigmentosa. However, the post-implantation visual acuity does not exceed that of legal blindness. The reason for the poor visual acuity might be that (1) degenerate retinal ganglion cells (RGCs) are less responsive to electrical stimulation than normal RGCs, and (2) electrically-evoked RGC spikes show a more widespread not focal response. The single-biphasic pulse electrical stimulation, commonly used in artificial vision, has limitations in addressing these issues. In this study, we propose the benefit of multiple consecutive-biphasic pulse stimulation. We used C57BL/6J mice and C3H/HeJ (rd1) mice for the normal retina and retinal degeneration model. An 8 × 8 multi-electrode array was used to record electrically-evoked RGC spikes. We compared RGC responses when increasing the amplitude of a single biphasic pulse versus increasing the number of consecutive biphasic pulses at the same stimulus charge. Increasing the amplitude of a single biphasic pulse induced more RGC spike firing while the spatial resolution of RGC populations decreased. For multiple consecutive-biphasic pulse stimulation, RGC firing increased as the number of pulses increased, and the spatial resolution of RGC populations was well preserved even up to 5 pulses. Multiple consecutive-biphasic pulse stimulation using two or three pulses in degenerate retinas induced as much RGC spike firing as in normal retinas. These findings suggest that the newly proposed multiple consecutive-biphasic pulse stimulation can improve the visual acuity in prosthesis-implanted patients.
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Affiliation(s)
- Jungryul Ahn
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju 28644, Korea
| | - Yongseok Yoo
- School of Computer Science and Engineering, Soongsil University, Seoul 06978, Korea
| | - Yong Sook Goo
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju 28644, Korea
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11
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Zhou Y, Sheng Y, Pan M, Tu J, Zhao X, Ge Q, Lu Z. Spatial Transcriptomic Analysis Reveals Regional Transcript Changes in Early and Late Stages of rd1 Model Mice with Retinitis Pigmentosa. Int J Mol Sci 2023; 24:14869. [PMID: 37834317 PMCID: PMC10573885 DOI: 10.3390/ijms241914869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 09/27/2023] [Accepted: 10/02/2023] [Indexed: 10/15/2023] Open
Abstract
Retinitis pigmentosa (RP) is the leading cause of inherited blindness with a genetically heterogeneous disorder. Currently, there is no effective treatment that can protect vision for those with RP. In recent decades, the rd1 mouse has been used to study the pathological mechanisms of RP. Molecular biological studies using rd1 mice have clarified the mechanism of the apoptosis of photoreceptor cells in the early stage of RP. However, the pathological changes in RP over time remain unclear. The unknown pathology mechanism of RP over time and the difficulty of clinical treatment make it urgent to perform more refined and spatially informed molecular biology studies of RP. In this study, spatial transcriptomic analysis is used to study the changes in different retinal layers of rd1 mice at different ages. The results demonstrate the pattern of photoreceptor apoptosis between rd1 mice and the control group. Not only was oxidative stress enhanced in the late stage of RP, but it was accompanied by an up-regulation of the VEGF pathway. Analysis of temporal kinetic trends has further identified patterns of changes in the key pathways of the early and late stages, to help understand the important pathogenesis of RP. Overall, the application of spatial transcriptomics to rd1 mice can help to elucidate the important pathogenesis of RP involving photoreceptor apoptosis and retinal remodeling.
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Affiliation(s)
- Ying Zhou
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China; (Y.Z.); (Y.S.); (J.T.); (X.Z.); (Z.L.)
| | - Yuqi Sheng
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China; (Y.Z.); (Y.S.); (J.T.); (X.Z.); (Z.L.)
| | - Min Pan
- School of Medicine, Southeast University, Nanjing 210097, China;
| | - Jing Tu
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China; (Y.Z.); (Y.S.); (J.T.); (X.Z.); (Z.L.)
| | - Xiangwei Zhao
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China; (Y.Z.); (Y.S.); (J.T.); (X.Z.); (Z.L.)
| | - Qinyu Ge
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China; (Y.Z.); (Y.S.); (J.T.); (X.Z.); (Z.L.)
| | - Zuhong Lu
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China; (Y.Z.); (Y.S.); (J.T.); (X.Z.); (Z.L.)
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12
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Beaver D, Limnios IJ. A treatment within sight: challenges in the development of stem cell-derived photoreceptor therapies for retinal degenerative diseases. FRONTIERS IN TRANSPLANTATION 2023; 2:1130086. [PMID: 38993872 PMCID: PMC11235385 DOI: 10.3389/frtra.2023.1130086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 09/07/2023] [Indexed: 07/13/2024]
Abstract
Stem cell therapies can potentially treat various retinal degenerative diseases, including age-related macular degeneration (AMD) and inherited retinal diseases like retinitis pigmentosa. For these diseases, transplanted cells may include stem cell-derived retinal pigmented epithelial (RPE) cells, photoreceptors, or a combination of both. Although stem cell-derived RPE cells have progressed to human clinical trials, therapies using photoreceptors and other retinal cell types are lagging. In this review, we discuss the potential use of human pluripotent stem cell (hPSC)-derived photoreceptors for the treatment of retinal degeneration and highlight the progress and challenges for their efficient production and clinical application in regenerative medicine.
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Affiliation(s)
- Davinia Beaver
- Clem Jones Centre for Regenerative Medicine, Bond University, Gold Coast, QL, Australia
| | - Ioannis Jason Limnios
- Clem Jones Centre for Regenerative Medicine, Bond University, Gold Coast, QL, Australia
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13
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Kramer RH. Suppressing Retinal Remodeling to Mitigate Vision Loss in Photoreceptor Degenerative Disorders. Annu Rev Vis Sci 2023; 9:131-153. [PMID: 37713276 DOI: 10.1146/annurev-vision-112122-020957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/17/2023]
Abstract
Rod and cone photoreceptors degenerate in retinitis pigmentosa and age-related macular degeneration, robbing the visual system of light-triggered signals necessary for sight. However, changes in the retina do not stop with the photoreceptors. A stereotypical set of morphological and physiological changes, known as remodeling, occur in downstream retinal neurons. Some aspects of remodeling are homeostatic, with structural or functional changes compensating for partial loss of visual inputs. However, other aspects are nonhomeostatic, corrupting retinal information processing to obscure vision mediated naturally by surviving photoreceptors or artificially by vision-restoration technologies. In this review, I consider the mechanism of remodeling and its consequences for residual and restored visual function; discuss the role of retinoic acid, a critical molecular trigger of detrimental remodeling; and discuss strategies for suppressing retinoic acid biosynthesis or signaling as therapeutic possibilities for mitigating vision loss.
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Affiliation(s)
- Richard H Kramer
- Department of Molecular and Cell Biology, University of California, Berkeley, USA;
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14
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Ulhaq ZS, Okamoto K, Ogino Y, Tse WKF. Dysregulation of Spliceosomes Complex Induces Retinitis Pigmentosa-Like Characteristics in sf3b4-Depleted Zebrafish. THE AMERICAN JOURNAL OF PATHOLOGY 2023; 193:1223-1233. [PMID: 37263342 DOI: 10.1016/j.ajpath.2023.05.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 05/15/2023] [Accepted: 05/19/2023] [Indexed: 06/03/2023]
Abstract
The SF3B4 gene encodes a highly conserved protein that plays a critical role in mRNA splicing. Mutations in this gene are known to cause Nager syndrome, a rare craniofacial disorder. Although SF3B4 expression is detected in the optic vesicle before it is detected in the limb and somite, the role of SF3B4 in the eye is not well understood. This study investigated the function of sf3b4 in the retina by performing transcriptome profiles, immunostaining, and behavioral analysis of sf3b4-/- mutant zebrafish. Results from this study suggest that dysregulation of the spliceosome complex affects not only craniofacial development but also retinogenesis. Zebrafish lacking functional sf3b4 displayed characteristics similar to retinitis pigmentosa (RP), marked by severe retinal pigment epithelium defects and rod degeneration. Pathway analysis revealed altered retinol metabolism and retinoic acid signaling in the sf3b4-/- mutants. Supplementation of retinoic acid rescued key cellular phenotypes observed in the sf3b4-/- mutants, offering potential therapeutic strategies for RP in the future. In conclusion, this study sheds light on the previously unknown role of SF3B4 in retinogenesis and provides insights into the underlying mechanisms of RP.
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Affiliation(s)
- Zulvikar Syambani Ulhaq
- Laboratory of Developmental Disorders and Toxicology, Center for Promotion of International Education and Research, Faculty of Agriculture, Kyushu University, Fukuoka, Japan; Research Center for Pre-clinical and Clinical Medicine, National Research and Innovation Agency, Republic of Indonesia, Cibinong, Indonesia.
| | - Keigo Okamoto
- Laboratory of Aquatic Molecular Developmental Biology, Center for Promotion of International Education and Research, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
| | - Yukiko Ogino
- Laboratory of Aquatic Molecular Developmental Biology, Center for Promotion of International Education and Research, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
| | - William Ka Fai Tse
- Laboratory of Developmental Disorders and Toxicology, Center for Promotion of International Education and Research, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
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15
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Antropoli A, Arrigo A, Bianco L, Cavallari E, Berni A, Casoni F, Consalez G, Bandello F, Cremona O, Battaglia Parodi M. HYPERREFLECTIVE BAND IN THE GANGLION CELL LAYER IN RETINITIS PIGMENTOSA. Retina 2023; 43:1348-1355. [PMID: 36996465 DOI: 10.1097/iae.0000000000003801] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/01/2023]
Abstract
PURPOSE To describe a sign that takes the form of a continuous hyperreflective band within the thickness of the ganglion cell layer (GCL), thus dubbed the "hyperreflective ganglion cell layer band" (HGB), which the authors detected in a fraction of patients affected by retinitis pigmentosa (RP). METHODS Retrospective, cross-sectional, observational study. Optical coherence tomography (OCT) images of patients with RP examined between May 2015 and June 2021 were retrospectively reviewed for the presence of HGB, epiretinal membrane (ERM), macular hole, and cystoid macular edema (CME). The ellipsoid zone (EZ) width was also measured. A subgroup of patients underwent microperimetry in the central 2°, 4°, and 10°. RESULTS One hundred and fifty-four eyes from 77 subjects were included in the study. The HGB was present in 39 (25.3%) eyes with RP. Mean best-corrected visual acuity (BCVA) was 0.39 ± 0.05 logMAR (approximately 20/50 Snellen equivalent) and 0.18 ± 0.03 logMAR (approximately 20/32 Snellen equivalent) in eyes with and without HGB, respectively ( P < 0.001). The two groups did not differ regarding EZ width; mean 2°, 4°, and 10° retinal sensitivity; and prevalence of CME, ERM, and macular hole. The multivariable analysis showed the presence of HGB to be a predictor of poorer BCVA ( P < 0.001). CONCLUSION HGB is an OCT finding detectable in approximately a quarter of eyes with RP and is associated with a poorer visual function. In the discussion, the authors speculate about possible morphogenetic scenarios to explain this observation.
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Affiliation(s)
- Alessio Antropoli
- Department of Ophthalmology, Vita-Salute San Raffaele University, IRCCS San Raffaele Scientific Institute, Milan, Italy; and
| | - Alessandro Arrigo
- Department of Ophthalmology, Vita-Salute San Raffaele University, IRCCS San Raffaele Scientific Institute, Milan, Italy; and
| | - Lorenzo Bianco
- Department of Ophthalmology, Vita-Salute San Raffaele University, IRCCS San Raffaele Scientific Institute, Milan, Italy; and
| | - Elena Cavallari
- Department of Ophthalmology, Vita-Salute San Raffaele University, IRCCS San Raffaele Scientific Institute, Milan, Italy; and
| | - Alessandro Berni
- Department of Ophthalmology, Vita-Salute San Raffaele University, IRCCS San Raffaele Scientific Institute, Milan, Italy; and
| | | | | | - Francesco Bandello
- Department of Ophthalmology, Vita-Salute San Raffaele University, IRCCS San Raffaele Scientific Institute, Milan, Italy; and
| | | | - Maurizio Battaglia Parodi
- Department of Ophthalmology, Vita-Salute San Raffaele University, IRCCS San Raffaele Scientific Institute, Milan, Italy; and
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16
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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 : THE PREPRINT SERVER FOR BIOLOGY 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] [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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17
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Zhao H, Wang H, Zhang M, Weng C, Liu Y, Yin Z. Chromatic pupillometry isolation and evaluation of intrinsically photosensitive retinal ganglion cell-driven pupillary light response in patients with retinitis pigmentosa. Front Hum Neurosci 2023; 17:1212398. [PMID: 37533585 PMCID: PMC10390747 DOI: 10.3389/fnhum.2023.1212398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 07/05/2023] [Indexed: 08/04/2023] Open
Abstract
Purpose The pupil light response (PLR) is driven by rods, cones, and intrinsically photosensitive retinal ganglion cells (ipRGCs). We aimed to isolate ipRGC-driven pupil responses using chromatic pupillometry and to determine the effect of advanced retinitis pigmentosa (RP) on ipRGC function. Methods A total of 100 eyes from 67 patients with advanced RP and 18 healthy controls (HCs) were included. Patients were divided into groups according to severity of visual impairment: no light perception (NLP, 9 eyes), light perception (LP, 19 eyes), faint form perception (FFP, 34 eyes), or form perception (FP, 38 eyes). Pupil responses to rod-weighted (487 nm, -1 log cd/m2, 1 s), cone-weighted (630 nm, 2 log cd/m2, 1 s), and ipRGC-weighted (487 nm, 2 log cd/m2, 1 s) stimuli were recorded. ipRGC function was evaluated by the postillumination pupil response (PIPR) and three metrics of pupil kinetics: maximal contraction velocity (MCV), contraction duration, and maximum dilation velocity (MDV). Results We found a slow, sustained PLR response to the ipRGC-weighted stimulus in most patients with NLP (8/9), but these patients had no detectable rod- or cone-driven PLR. The ipRGC-driven PLR had an MCV of 0.269 ± 0.150%/s and contraction duration of 2.562 ± 0.902 s, both of which were significantly lower than those of the rod and cone responses. The PIPRs of the RP groups did not decrease compared with those of the HCs group and were even enhanced in the LP group. At advanced stages, ipRGC responses gradually became the main component of the PLR. Conclusion Chromatic pupillometry successfully isolated an ipRGC-driven PLR in patients with advanced RP. This PLR remained stable and gradually became the main driver of pupil contraction in more advanced cases of RP. Here, we present baseline data on ipRGC function; we expect these findings to contribute to evaluating and screening candidates for novel therapies.
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Affiliation(s)
- He Zhao
- Southwest Hospital/Southwest Eye Hospital, Army Medical University, Chongqing, China
- Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Hao Wang
- Southwest Hospital/Southwest Eye Hospital, Army Medical University, Chongqing, China
- Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Minfang Zhang
- Southwest Hospital/Southwest Eye Hospital, Army Medical University, Chongqing, China
- Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Chuanhuang Weng
- Southwest Hospital/Southwest Eye Hospital, Army Medical University, Chongqing, China
- Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Yong Liu
- Southwest Hospital/Southwest Eye Hospital, Army Medical University, Chongqing, China
- Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Zhengqin Yin
- Southwest Hospital/Southwest Eye Hospital, Army Medical University, Chongqing, China
- Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
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18
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Asghar SA, Mahadevappa M. Integrating Finite Element Method for Multiscale Modeling and Simulation of Retinal Ganglion Cell Stimulation Strategies. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023; 2023:1-4. [PMID: 38082879 DOI: 10.1109/embc40787.2023.10340593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
The finite element method (FEM) has become an increasingly popular tool for the computational modeling of multiscale biological systems, including the electrode-tissue interface and the behavior of individual neural cells. However, a significant challenge in these studies is integrating multiple levels of complexity, each with its biophysical properties. This paper presents a single platform solution for modeling these multiscale systems using the finite element method. The proposed method combines different finite element formulations tailored to the specific biophysical properties of each scale into a single unified simulation platform. The results of this method are compared to experimental data to demonstrate the accuracy and efficacy of the proposed approach. With the goal of eliciting the most significant possible response from the retinal ganglion cell's (RGC) multiple components, we devised an electrical stimulation strategy and electrode placement setup that took into account both the RGC's horizontal and vertical location. We found that the activity in a single RGC model could be elicited by a cathodic pulse of amplitude 34 µA. We observed that the optimum electrode placement for a neural response is around the initial axon segment, 30 μm from the soma, and 10 μm above the RGC. Our results show that the proposed method can accurately capture the complex behavior of these multiscale systems and provide a valuable tool for further research in retinal prostheses.Clinical Relevance- To develop efficient electrical stimulation schemes for retinal prosthesis applications, this research can shed light on the behavior of the electrode-tissue interface and individual neural cells. Electrical stimulation of RGCs has shown promise in the application of retinal prostheses. Still, a thorough understanding of the electrode-induced electric field is essential for the design of effective and safe stimulation protocols. Electrical stimulation's side effects may require knowledge of multiple physics disciplines (such as thermal or structural deformation owing to implant placement inside the eye). Finding a solution to diseases that cause vision impairment could be aided by a finite element method (FEM) framework that simulates the neuronal response to extracellular electrical stimulation for realistic 3D cell and electrode geometries.
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19
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Ahn J, Jeong Y, Cha S, Lee JY, Yoo Y, Goo YS. High amplitude pulses on the same charge condition efficiently elicit bipolar cell-mediated retinal ganglion cell responses in the degenerate retina. Biomed Eng Lett 2023; 13:129-140. [PMID: 37124107 PMCID: PMC10130300 DOI: 10.1007/s13534-023-00260-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 12/19/2022] [Accepted: 01/09/2023] [Indexed: 02/01/2023] Open
Abstract
Retinal pigmentosa (RP) patients lose vision due to the loss of photoreceptors. Retinal prostheses bypass the dead photoreceptors by electrically stimulating surviving retinal neurons, such as bipolar cells or retinal ganglion cells (RGCs). In previous studies, stimulus charge has been mainly optimized to maximize the RGC response to electrical stimulation. This study aimed to investigate the effect of amplitude and duration even under the same charge condition on eliciting RGC spikes in the wild-type and degenerate retinas. Wild-type (WT) Sprague-Dawley rats were used as the normal retinal model, and Pde6b knockout rats were used as a retinal degeneration (RD) model. Electrically-evoked RGC spikes were recorded from isolated rat retinas using an 8 × 8 multielectrode array. The same charge was maintained (10 or 20 nC), and electrical stimulation was applied to WT and RD retinas, adjusting the amplitude and duration of the 1st phase of biphasic pulses. In the pulse modulation of the 1st phase, high amplitude (short duration) pulses induced more RGC spikes than low amplitude (long duration) pulses. Both WT and RD retinas showed a significant reduction in the number of RGC spikes upon stimulation with lower amplitude (longer duration) pulses. In clinical trials where stimulus charges are delivered to the degenerate retina of blind patients, high amplitude (short duration) pulses would help elicit more RGC spikes.
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Affiliation(s)
- Jungryul Ahn
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju, South Korea
| | - Yurim Jeong
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju, South Korea
| | - Seongkwang Cha
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju, South Korea
| | - Joo Yong Lee
- Department of Ophthalmology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - Yongseok Yoo
- School of Computer Science and Engineering, Soongsil University, Seoul, South Korea
| | - Yong Sook Goo
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju, South Korea
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20
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Nishida K, Morimoto T, Terasawa Y, Sakaguchi H, Kamei M, Miyoshi T, Fujikado T, Nishida K. The influence of stimulating electrode conditions on electrically evoked potentials and resistance in suprachoroidal transretinal stimulation. Jpn J Ophthalmol 2023; 67:182-188. [PMID: 36626079 DOI: 10.1007/s10384-022-00972-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 11/17/2022] [Indexed: 01/11/2023]
Abstract
PURPOSE To determine the influence of stimulating electrode conditions on the amplitudes and latencies of electrically evoked potentials (EEPs) and the resistance at the electrode-tissue interface in the suprachoroidal transretinal stimulation (STS) system. STUDY DESIGN Experimental study. METHODS A scleral pocket (3 × 5 mm) was created just over the visual streak in anesthetized pigmented rabbits (weight, 1.9-2.7 kg), and STS stimulating electrodes were implanted into the pocket. Measurements were obtained with stimulating electrodes of different lengths (0.3 or 0.5 mm) and different surface characteristics (smooth or porous). EEPs elicited with a fixed current under each set of electrode conditions were recorded; three measurement sessions were performed for each rabbit. The resistance at each electrode-tissue interface was measured. RESULTS The latencies and amplitudes of the EEPs did not differ significantly with changes in the height and surface characteristics of the stimulating electrodes, but the resistances at the electrode-tissue interface differed significantly (P = 0.001; the resistance values for the 0.3-mm-long electrode with a porous surface was 5.24 ± 0.67 kΩ and with the 0.3- and 0.5-mm-long electrodes with smooth surfaces were 7.63 ± 0.12 kΩ and 6.77 ± 0.20 kΩ). CONCLUSION Being shorter did not affect the EEPs of the stimulating electrodes with a porous surface while decreasing the resistance at the electrode-tissue interface.
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Affiliation(s)
- Kentaro Nishida
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, #E7, Suita, 565-0871, Japan.
| | - Takeshi Morimoto
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, #E7, Suita, 565-0871, Japan
| | - Yasuo Terasawa
- R&D Division, Artificial Vision Institute, NIDEK Co., Ltd., Gamagori, Japan
| | - Hirokazu Sakaguchi
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, #E7, Suita, 565-0871, Japan.,Department of Ophthalmology, Gifu University Graduate School of Medicine, Yanagido, Gifu, Japan
| | - Motohiro Kamei
- Department of Ophthalmology, Aichi Medical University, Nagakute, Japan
| | - Tomomitsu Miyoshi
- Department of Integrative Physiology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Takashi Fujikado
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, #E7, Suita, 565-0871, Japan
| | - Kohji Nishida
- Department of Ophthalmology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, #E7, Suita, 565-0871, Japan.,Integrated Frontier Research for Medical Science Division, Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, 2-2 Yamadaoka, Suita, Osaka, Japan
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21
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Choi KE, Cha S, Yun C, Ahn J, Hwang S, Kim YJ, Jung H, Eom H, Shin D, Oh J, Goo YS, Kim SW. Outer retinal degeneration in a non-human primate model using temporary intravitreal tamponade with N-methyl-N-nitrosourea in cynomolgus monkeys. J Neural Eng 2023; 20. [PMID: 36603218 DOI: 10.1088/1741-2552/acb085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 01/05/2023] [Indexed: 01/06/2023]
Abstract
Objective:The main objective of this study was to induce and evaluate drug-dose-dependent outer retinal degeneration in cynomolgus monkeys by application of N-methyl-N-nitrosourea (MNU).Approach:Intravitreal temporary tamponade induced outer retinal degeneration with MNU solutions (2-3 mg ml-1) after vitrectomy in five cynomolgus monkeys. Optical coherence tomography (OCT), fundus autofluorescence (FAF), full-field electroretinography (ffERG), and visual evoked potentials (VEP) were performed at baseline and weeks 2, 6, and 12 postoperatively. At week 12, OCT angiography, histology, and immunohistochemistry were performed.Main results:Outer retinal degeneration was observed in four monkeys, especially in the peripheral retina. Anatomical and functional changes occurred at week 2 and persisted until week 12. FAF images showed hypoautofluorescence dots, similar to AF patterns seen in human retinitis pigmentosa. Hyperautofluorescent lesions in the pericentral area were also observed, which corresponded to the loss of the ellipsoid zone on OCT images. OCT revealed thinning of the outer retinal layer adding to the loss of the ellipsoid zone outside the vascular arcade. Histological findings confirmed that the abovementioned changes resulted from a gradual loss of photoreceptors from the perifovea to the peripheral retina. In contrast, the inner retina, including ganglion cell layers, was preserved. Functionally, a decrease or extinction of scotopic ffERGs was observed, which indicated rod-dominant loss. Nevertheless, VEPs were relatively preserved.Significance:Therefore, we can conclude that temporary exposure to intravitreal MNU tamponade after vitrectomy induces rod-dominant outer retinal degeneration in cynomolgus monkeys, especially in the peripheral retina.
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Affiliation(s)
- Kwang-Eon Choi
- Department of Ophthalmology, Korea University College of Medicine, Seoul 08373, Republic of Korea
| | - Seongkwang Cha
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju 28644, Republic of Korea
| | - Cheolmin Yun
- Department of Ophthalmology, Korea University College of Medicine, Seoul 08373, Republic of Korea
| | - Jungryul Ahn
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju 28644, Republic of Korea
| | - Seil Hwang
- Department of Ophthalmology, Korea University College of Medicine, Seoul 08373, Republic of Korea
| | - Young-Jin Kim
- Medical Device Development Center, Osong Medical Innovation Foundation, Cheongju 28160, Chungbuk, Republic of Korea
| | - Hachul Jung
- Medical Device Development Center, Osong Medical Innovation Foundation, Cheongju 28160, Chungbuk, Republic of Korea
| | - Heejong Eom
- Laboratory Animal Center, Osong Medical Innovation Foundation, Cheongju 28160, Chungbuk, Republic of Korea
| | - Dongkwan Shin
- Laboratory Animal Center, Osong Medical Innovation Foundation, Cheongju 28160, Chungbuk, Republic of Korea
| | - Jaeryung Oh
- Department of Ophthalmology, Korea University College of Medicine, Seoul 08373, Republic of Korea
| | - Yong Sook Goo
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju 28644, Republic of Korea
| | - Seong-Woo Kim
- Department of Ophthalmology, Korea University College of Medicine, Seoul 08373, Republic of Korea
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22
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Kim KE, Kim YH, Kim J, Ahn SJ. Macular Ganglion Cell Complex and Peripapillary Retinal Nerve Fiber Layer Thicknesses in Hydroxychloroquine Retinopathy. Am J Ophthalmol 2023; 245:70-80. [PMID: 35963445 DOI: 10.1016/j.ajo.2022.07.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 07/19/2022] [Accepted: 07/21/2022] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To investigate macular ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (RNFL) thicknesses in patients with hydroxychloroquine retinopathy of differing severity. DESIGN Cross-sectional, case-control comparison study. PARTICIPANTS From patients screened for hydroxychloroquine retinopathy between January 2016 and October 2021 using swept-source optical coherence tomography (SS-OCT), fundus autofluorescence (FAF), and standard automated perimetry, 66 patients with retinopathy and 66 without retinopathy were included by 1:1 propensity score matching based on age, sex, systemic diseases, history of tamoxifen and pentosan use, and kidney disease. METHODS Eyes with hydroxychloroquine retinopathy were divided into early, moderate, and severe stages. Inner-retinal thickness parameters, including macular GCC (RNFL + ganglion cell layer + inner plexiform layer) and peripapillary RNFL thicknesses, were automatically obtained using SS-OCT (DRI-OCT Triton, Topcon Inc., Japan) and compared between patients with and without retinopathy and between severity subgroups. The structure-function relationships between GCC or peripapillary RNFL thicknesses and perimetric parameters including mean deviation (MD) and visual field index (VFI) of Humphrey 30-2 test were evaluated. MAIN OUTCOME MEASURES Macular GCC and peripapillary RNFL thickness parameters. RESULTS The average macular GCC and peripapillary RNFL thicknesses were significantly decreased in patients with hydroxychloroquine retinopathy relative to those without retinopathy. Macular GCC thicknesses in 4 of 6 macular sectors and peripapillary RNFL thicknesses in 9 of 12 clock-hour sectors were significantly different between the groups. The differences in the average and sectoral macular GCC parameters were statistically significant among the severity subgroups, particularly between severe and earlier stages. Average macular GCC and peripapillary RNFL thicknesses significantly correlated with MD and VFI in all patients (all P < .001). CONCLUSIONS Macular GCC and peripapillary RNFL thinning was more prominent in eyes with severe hydroxychloroquine retinopathy, as indicative of inner-retinal thinning in eyes with advanced-stage disease. Further, as inner-retinal thinning showed a significant correlation with worse perimetric function, cautious evaluation of the inner retina may be required for eyes with advanced hydroxychloroquine retinopathy.
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Affiliation(s)
- Ko Eun Kim
- From Department of Ophthalmology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea (K.E.K)
| | - Young Hwan Kim
- Department of Ophthalmology, Hanyang University Hospital, Hanyang University College of Medicine, Seoul, Republic of Korea (Y.H.K, S.J.A)
| | - Jiyeong Kim
- Laboratory of Biostatistical Consulting and Research, Medical Research Collaborating Center, Industry-University Cooperation Foundation, Hanyang University, Seoul, Republic of Korea (J.K)
| | - Seong Joon Ahn
- Department of Ophthalmology, Hanyang University Hospital, Hanyang University College of Medicine, Seoul, Republic of Korea (Y.H.K, S.J.A);.
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23
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Kim HM, Oh JK, Tsang SH. The Use of Optical Coherence Tomography in Evaluation of Retinitis Pigmentosa. Methods Mol Biol 2022; 2560:91-100. [PMID: 36481886 DOI: 10.1007/978-1-0716-2651-1_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Optical coherence tomography (OCT) is a noninvasive imaging technology that has gained widespread use in the evaluation of multiple retinal pathologies, including retinitis pigmentosa (RP). OCT allows for visualization of distinct retinal layers and the choroid and facilitates study of morphological features associated with RP. OCT can be used to detect and to track progression of RP, as well as to correlate structural findings with functional manifestations of the disease. This chapter provides a basic overview of OCT technology and details elements of importance in the use of OCT for diagnosis and assessment of progression of RP.
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Affiliation(s)
- Ha Min Kim
- Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA. .,Department of Ophthalmology, Columbia University Irving Medical Center, New York, NY, USA.
| | - Jin Kyun Oh
- Department of Ophthalmology, Columbia University Irving Medical Center, New York, NY, USA
| | - Stephen H Tsang
- Departments of Opthalmology, Pathology & Cell Biology Graduate Programs in Nutritional & Metabolic Biology and Neurobiology & Behavior Columbia Stem Cell Initiative, New York, NY, USA
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24
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Nikonov S, Dolgova N, Sudharsan R, Tochitsky I, Iwabe S, Guzman JM, Van Gelder RN, Kramer RH, Aguirre GD, Beltran WA. Photochemical Restoration of Light Sensitivity in the Degenerated Canine Retina. Pharmaceutics 2022; 14:pharmaceutics14122711. [PMID: 36559205 PMCID: PMC9783220 DOI: 10.3390/pharmaceutics14122711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/23/2022] [Accepted: 11/28/2022] [Indexed: 12/11/2022] Open
Abstract
Photopharmacological compounds such as azobenzene-based photoswitches have been shown to control the conductivity of ionic channels in a light-dependent manner and are considered a potential strategy to restore vision in patients with end-stage photoreceptor degeneration. Here, we report the effects of DENAQ, a second-generation azobenzene-based photoswitch on retinal ganglion cells (RGC) in canine retinas using multi-electrode array (MEA) recordings (from nine degenerated and six WT retinas). DENAQ treatment conferred increased light sensitivity to RGCs in degenerated canine retinas. RGC light responses were observed in degenerated retinas following ex vivo application of 1 mM DENAQ (n = 6) or after in vivo DENAQ injection (n = 3, 150 μL, 3-10 mM) using 455 nm light at intensities as low as 0.2 mW/cm2. The number of light-sensitive cells and the per cell response amplitude increased with light intensity up to the maximum tested intensity of 85 mW/cm2. Application of DENAQ to degenerated retinas with partially preserved cone function caused appearance of DENAQ-driven responses both in cone-driven and previously non-responsive RGCs, and disappearance of cone-driven responses. Repeated stimulation slowed activation and accelerated recovery of the DENAQ-driven responses. The latter is likely responsible for the delayed appearance of a response to 4 Hz flicker stimulation. Limited aqueous solubility of DENAQ results in focal drug aggregates associated with ocular toxicity. While this limits the therapeutic potential of DENAQ, more potent third-generation photoswitches may be more promising, especially when delivered in a slow-release formulation that prevents drug aggregation.
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Affiliation(s)
- Sergei Nikonov
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Natalia Dolgova
- Division of Experimental Retinal Therapies, Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Raghavi Sudharsan
- Division of Experimental Retinal Therapies, Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ivan Tochitsky
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 90095, USA
| | - Simone Iwabe
- Division of Experimental Retinal Therapies, Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jose-Manuel Guzman
- Division of Experimental Retinal Therapies, Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Russell N. Van Gelder
- Department of Ophthalmology, Pathology, and Biological Structure, University of Washington, Seattle, WA 98195, USA
| | - Richard H. Kramer
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 90095, USA
| | - Gustavo D. Aguirre
- Division of Experimental Retinal Therapies, Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - William A. Beltran
- Division of Experimental Retinal Therapies, Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Correspondence:
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25
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Sakai D, Tomita H, Maeda A. Optogenetic Therapy for Visual Restoration. Int J Mol Sci 2022; 23:15041. [PMID: 36499371 PMCID: PMC9735806 DOI: 10.3390/ijms232315041] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 11/29/2022] [Accepted: 11/29/2022] [Indexed: 12/02/2022] Open
Abstract
Optogenetics is a recent breakthrough in neuroscience, and one of the most promising applications is the treatment of retinal degenerative diseases. Multiple clinical trials are currently ongoing, less than a decade after the first attempt at visual restoration using optogenetics. Optogenetic therapy has great value in providing hope for visual restoration in late-stage retinal degeneration, regardless of the genotype. This alternative gene therapy consists of multiple elements including the choice of target retinal cells, optogenetic tools, and gene delivery systems. Currently, there are various options for each element, all of which have been developed as a product of technological success. In particular, the performance of optogenetic tools in terms of light and wavelength sensitivity have been improved by engineering microbial opsins and applying human opsins. To provide better post-treatment vision, the optimal choice of optogenetic tools and effective gene delivery to retinal cells is necessary. In this review, we provide an overview of the advancements in optogenetic therapy for visual restoration, focusing on available options for optogenetic tools and gene delivery methods.
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Affiliation(s)
- Daiki Sakai
- Department of Ophthalmology, Kobe City Eye Hospital, Kobe 650-0047, Japan
- Department of Ophthalmology, Kobe City Medical Center General Hospital, Kobe 650-0047, Japan
- Department of Surgery, Division of Ophthalmology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Hiroshi Tomita
- Graduate Course in Biological Sciences, Division of Science and Engineering, Iwate University, Iwate 020-8550, Japan
| | - Akiko Maeda
- Department of Ophthalmology, Kobe City Eye Hospital, Kobe 650-0047, Japan
- Department of Ophthalmology, Kobe City Medical Center General Hospital, Kobe 650-0047, Japan
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26
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De Silva SR, Moore AT. Optogenetic approaches to therapy for inherited retinal degenerations. J Physiol 2022; 600:4623-4632. [PMID: 35908243 DOI: 10.1113/jp282076] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 07/18/2022] [Indexed: 01/07/2023] Open
Abstract
Inherited retinal degenerations such as retinitis pigmentosa (RP) affect around one in 4000 people and are the leading cause of blindness in working age adults in several countries. In these typically monogenic conditions, there is progressive degeneration of photoreceptors; however, inner retinal neurons such as bipolar cells and ganglion cells remain largely structurally intact, even in end-stage disease. Therapeutic approaches aiming to stimulate these residual cells, independent of the underlying genetic cause, could potentially restore visual function in patients with advanced vision loss, and benefit many more patients than therapies directed at the specific gene implicated in each disorder. One approach investigated for this purpose is that of optogenetics, a method of neuromodulation that utilises light to activate neurons engineered to ectopically express a light-sensitive protein. Using gene therapy via adeno-associated viral vectors, a range of photosensitive proteins have been expressed in remaining retinal cells in advanced retinal degeneration with in vivo studies demonstrating restoration of visual function. Developing an effective optogenetic strategy requires consideration of multiple factors, including the light-sensitive protein that is used, the vector and method for gene delivery, and the target cell for expression because these in turn may affect the quality of vision that can be restored. Currently, at least four clinical trials are ongoing to investigate optogenetic therapies in patients, with the ultimate aim of reversing visual loss in end-stage disease.
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Affiliation(s)
- Samantha R De Silva
- Oxford Eye Hospital, Oxford, UK.,UCL Institute of Ophthalmology, London, UK.,Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Anthony T Moore
- UCL Institute of Ophthalmology, London, UK.,Ophthalmology Department, University of California, San Francisco, CA, USA
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27
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Bipolar cell targeted optogenetic gene therapy restores parallel retinal signaling and high-level vision in the degenerated retina. Commun Biol 2022; 5:1116. [PMID: 36266533 PMCID: PMC9585040 DOI: 10.1038/s42003-022-04016-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Accepted: 09/21/2022] [Indexed: 11/09/2022] Open
Abstract
Optogenetic gene therapies to restore vision are in clinical trials. Whilst current clinical approaches target the ganglion cells, the output neurons of the retina, new molecular tools enable efficient targeting of the first order retinal interneurons, the bipolar cells, with the potential to restore a higher quality of vision. Here we investigate retinal signaling and behavioral vision in blind mice treated with bipolar cell targeted optogenetic gene therapies. All tested tools, including medium-wave opsin, Opto-mGluR6, and two new melanopsin based chimeras restored visual acuity and contrast sensitivity. The best performing opsin was a melanopsin-mGluR6 chimera, which in some cases restored visual acuities and contrast sensitivities that match wild-type animals. Light responses from the ganglion cells were robust with diverse receptive-field types, inferring elaborate inner retinal signaling. Our results highlight the potential of bipolar cell targeted optogenetics to recover high-level vision in human patients with end-stage retinal degenerations. A chimeric Mela(CTmGluR6) optogenetic tool has the potential to restore vision and signaling in a mouse model of degenerative retinal disease.
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28
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Caravaca-Rodriguez D, Gaytan SP, Suaning GJ, Barriga-Rivera A. Implications of Neural Plasticity in Retinal Prosthesis. Invest Ophthalmol Vis Sci 2022; 63:11. [PMID: 36251317 DOI: 10.1167/iovs.63.11.11] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Retinal degenerative diseases such as retinitis pigmentosa cause a progressive loss of photoreceptors that eventually prevents the affected person from perceiving visual sensations. The absence of a visual input produces a neural rewiring cascade that propagates along the visual system. This remodeling occurs first within the retina. Then, subsequent neuroplastic changes take place at higher visual centers in the brain, produced by either the abnormal neural encoding of the visual inputs delivered by the diseased retina or as the result of an adaptation to visual deprivation. While retinal implants can activate the surviving retinal neurons by delivering electric current, the unselective activation patterns of the different neural populations that exist in the retinal layers differ substantially from those in physiologic vision. Therefore, artificially induced neural patterns are being delivered to a brain that has already undergone important neural reconnections. Whether or not the modulation of this neural rewiring can improve the performance for retinal prostheses remains a critical question whose answer may be the enabler of improved functional artificial vision and more personalized neurorehabilitation strategies.
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Affiliation(s)
- Daniel Caravaca-Rodriguez
- Department of Applied Physics III, Technical School of Engineering, Universidad de Sevilla, Sevilla, Spain
| | - Susana P Gaytan
- Department of Physiology, Universidad de Sevilla, Sevilla, Spain
| | - Gregg J Suaning
- School of Biomedical Engineering, University of Sydney, Sydney, Australia
| | - Alejandro Barriga-Rivera
- Department of Applied Physics III, Technical School of Engineering, Universidad de Sevilla, Sevilla, Spain.,School of Biomedical Engineering, University of Sydney, Sydney, Australia
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29
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Wang BY, Chen ZC, Bhuckory M, Kochnev Goldstein A, Palanker D. Pixel size limit of the PRIMA implants: from humans to rodents and back. J Neural Eng 2022; 19:10.1088/1741-2552/ac8e31. [PMID: 36044878 PMCID: PMC9527086 DOI: 10.1088/1741-2552/ac8e31] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 08/31/2022] [Indexed: 11/11/2022]
Abstract
Objective.Retinal prostheses aim at restoring sight in patients with retinal degeneration by electrically stimulating the inner retinal neurons. Clinical trials with patients blinded by atrophic age-related macular degeneration using the PRIMA subretinal implant, a 2 × 2 mm array of 100µm-wide photovoltaic pixels, have demonstrated a prosthetic visual acuity closely matching the pixel size. Further improvement in resolution requires smaller pixels, which, with the current bipolar design, necessitates more intense stimulation.Approach.We examine the lower limit of the pixel size for PRIMA implants by modeling the electric field, leveraging the clinical benchmarks, and using animal data to assess the stimulation strength and contrast of various patterns. Visually evoked potentials measured in Royal College of Surgeons rats with photovoltaic implants composed of 100µm and 75µm pixels were compared to clinical thresholds with 100µm pixels. Electrical stimulation model calibrated by the clinical and rodent data was used to predict the performance of the implant with smaller pixels.Main results.PRIMA implants with 75µm bipolar pixels under the maximum safe near-infrared (880 nm) illumination of 8 mW mm-2with 30% duty cycle (10 ms pulses at 30 Hz) should provide a similar perceptual brightness as with 100µm pixels under 3 mW mm-2irradiance, used in the current clinical trials. Contrast of the Landolt C pattern scaled down to 75µm pixels is also similar under such illumination to that with 100µm pixels, increasing the maximum acuity from 20/420 to 20/315.Significance.Computational modeling defines the minimum pixel size of the PRIMA implants as 75µm. Increasing the implant width from 2 to 3 mm and reducing the pixel size from 100 to 75µm will nearly quadrupole the number of pixels, which should be very beneficial for patients. Smaller pixels of the same bipolar flat geometry would require excessively intense illumination, and therefore a different pixel design should be considered for further improvement in resolution.
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Affiliation(s)
- Bing-Yi Wang
- Department of Physics, Stanford University, Stanford, CA, United States of America
| | - Zhijie Charles Chen
- Department of Electrical Engineering, Stanford University, Stanford, CA, United States of America
| | - Mohajeet Bhuckory
- Department of Ophthalmology, Stanford University, Stanford, CA, United States of America
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, United States of America
| | - Anna Kochnev Goldstein
- Department of Electrical Engineering, Stanford University, Stanford, CA, United States of America
| | - Daniel Palanker
- Department of Ophthalmology, Stanford University, Stanford, CA, United States of America
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, United States of America
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30
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Duan F, Xiao Z, Wang Y, Sun X, Tang Z, Wang R, Guo L, Tang W, Liu T, Wang P, Zhan Y. Metabolic alterations in the visual pathway of retinitis pigmentosa rats: A longitudinal multimodal magnetic resonance imaging study with histopathological validation. NMR IN BIOMEDICINE 2022; 35:e4751. [PMID: 35478360 DOI: 10.1002/nbm.4751] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 04/12/2022] [Accepted: 04/25/2022] [Indexed: 06/14/2023]
Abstract
Because retinitis pigmentosa (RP) has been shown to cause degenerative changes in the entire visual pathway, there is an urgent need to perform longitudinal assessments of RP-induced degeneration and identify imaging protocols to detect this degeneration as early as possible. In this study, we assessed a transgenic rat model of RP by using complementary noninvasive magnetic resonance imaging techniques, namely, proton magnetic resonance spectroscopy (1 H-MRS), to investigate the metabolic changes in RP. Our study demonstrated decreased concentrations and ratios to creatine (Cr) of N-acetylaspartate (NAA), glutamate (Glu), γ-aminobutyric acid (GABA), and taurine (Tau), whereas myo-inositol (Ins) and choline (Cho) were increased in the visual cortex of Royal College of Surgeons (RCS) rats compared with control rats (p < 0.05). Furthermore, with the progression of RP, the concentrations of NAA, Glu, GABA, and Tau, and the ratios of GABA/Cr and Tau/Cr significantly decreased over time, whereas the concentrations of Ins and Cho and the ratio of Ins/Cr significantly increased over time (p < 0.05). In addition, in RCS rats, NAA/Cr decreased significantly from 3 to 4 months postnatal (p < 0.001), and Cho/Cr increased significantly from 4 to 5 months postnatal (p = 0.005). Meanwhile, the 1 H-MRS indicators in 5-month postnatal RCS rats could be confirmed by immunohistochemical staining. In conclusion, with the progression of RP, the metabolic alterations in the visual cortex indicated progressive reprogramming with the decrease of neurons and axons, accompanied by the proliferation of gliocytes.
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Affiliation(s)
- Fei Duan
- Department of Radiology, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Zebin Xiao
- Department of Radiology, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Yuzhe Wang
- Department of Radiology, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Xinghuai Sun
- Department of Ophthalmology & Visual Science, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Fudan University, Shanghai, China
- Key Laboratory of Myopia, NHFPC (Fudan University), Shanghai, China
- Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China
| | - Zuohua Tang
- Department of Radiology, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Rong Wang
- Department of Radiology, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
- Department of Radiology, Huashan Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Linying Guo
- Department of Radiology, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Weijun Tang
- Department of Radiology, Huashan Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Tingting Liu
- Department of Ophthalmology & Visual Science, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Peng Wang
- Department of Radiology, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
| | - Yang Zhan
- Department of Radiology, Eye & ENT Hospital of Fudan University, Shanghai Medical School, Fudan University, Shanghai, China
- Shanghai Institute of Medical Imaging, Shanghai, China
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Lindner M, Gilhooley MJ, Hughes S, Hankins MW. Optogenetics for visual restoration: From proof of principle to translational challenges. Prog Retin Eye Res 2022; 91:101089. [PMID: 35691861 DOI: 10.1016/j.preteyeres.2022.101089] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 05/17/2022] [Accepted: 05/19/2022] [Indexed: 01/04/2023]
Abstract
Degenerative retinal disorders are a diverse family of diseases commonly leading to irreversible photoreceptor death, while leaving the inner retina relatively intact. Over recent years, innovative gene replacement therapies aiming to halt the progression of certain inherited retinal disorders have made their way into clinics. By rendering surviving retinal neurons light sensitive optogenetic gene therapy now offers a feasible treatment option that can restore lost vision, even in late disease stages and widely independent of the underlying cause of degeneration. Since proof-of-concept almost fifteen years ago, this field has rapidly evolved and a detailed first report on a treated patient has recently been published. In this article, we provide a review of optogenetic approaches for vision restoration. We discuss the currently available optogenetic tools and their relative advantages and disadvantages. Possible cellular targets will be discussed and we will address the question how retinal remodelling may affect the choice of the target and to what extent it may limit the outcomes of optogenetic vision restoration. Finally, we will analyse the evidence for and against optogenetic tool mediated toxicity and will discuss the challenges associated with clinical translation of this promising therapeutic concept.
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Affiliation(s)
- Moritz Lindner
- The Nuffield Laboratory of Ophthalmology, Jules Thorn SCNi, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX1 3QU, United Kingdom; Institute of Physiology and Pathophysiology, Department of Neurophysiology, Philipps University, 35037, Marburg, Germany
| | - Michael J Gilhooley
- The Nuffield Laboratory of Ophthalmology, Jules Thorn SCNi, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX1 3QU, United Kingdom; The Institute of Ophthalmology, University College London, EC1V 9EL, United Kingdom; Moorfields Eye Hospital, London, EC1V 2PD, United Kingdom
| | - Steven Hughes
- The Nuffield Laboratory of Ophthalmology, Jules Thorn SCNi, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX1 3QU, United Kingdom
| | - Mark W Hankins
- The Nuffield Laboratory of Ophthalmology, Jules Thorn SCNi, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX1 3QU, United Kingdom.
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Italiano ML, Guo T, Lovell NH, Tsai D. Improving the spatial resolution of artificial vision using midget retinal ganglion cell populations modelled at the human fovea. J Neural Eng 2022; 19. [PMID: 35609556 DOI: 10.1088/1741-2552/ac72c2] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 05/24/2022] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Retinal prostheses seek to create artificial vision by stimulating surviving retinal neurons of patients with profound vision impairment. Notwithstanding tremendous research efforts, the performance of all implants tested to date has remained rudimentary, incapable of overcoming the threshold for legal blindness. To maximize the perceptual efficacy of retinal prostheses, a device must be capable of controlling retinal neurons with greater spatiotemporal precision. Most studies of retinal stimulation were derived from either non-primate species or the peripheral primate retina. We investigated if artificial stimulation could leverage the high spatial resolution afforded by the neural substrates at the primate fovea and surrounding regions to achieve improved percept qualities. APPROACH We began by developing a new computational model capable of generating anatomically accurate retinal ganglion cell (RGC) populations within the human central retina. Next, multiple RGC populations across the central retina were stimulated in-silico to compare clinical and recently proposed neurostimulation configurations based on their ability to improve perceptual efficacy and reduce activation thresholds. MAIN RESULTS Our model uniquely upholds eccentricity-dependent characteristics such as RGC density and dendritic field diameter, whilst incorporating anatomically accurate features such as axon projection and three-dimensional RGC layering, features often forgone in favor of reduced computational complexity. Following epiretinal stimulation, the RGCs in our model produced response patterns in shapes akin to the complex percepts reported in clinical trials. Our results also demonstrated that even within the neuron-dense central retina, epiretinal stimulation using a multi-return hexapolar electrode arrangement could reliably achieve spatially focused RGC activation and could achieve single-cell excitation in 74% of all tested locations. SIGNIFICANCE This study establishes an anatomically accurate three-dimensional model of the human central retina and demonstrates the potential for an epiretinal hexapolar configuration to achieve consistent, spatially confined retinal responses, even within the neuron-dense foveal region. Our results promote the prospect and optimization of higher spatial resolution in future epiretinal implants.
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Affiliation(s)
- Michael Lewis Italiano
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Sydney, New South Wales, 2052, AUSTRALIA
| | - Tianruo Guo
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Sydney, New South Wales, 2052, AUSTRALIA
| | - Nigel H Lovell
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Sydney, New South Wales, 2052, AUSTRALIA
| | - David Tsai
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Sydney, New South Wales, 2052, AUSTRALIA
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Yoon CK, Bae K, Yu HG. Longitudinal Microstructure Changes of the Retina and Choroid in Retinitis Pigmentosa. Am J Ophthalmol 2022; 241:149-159. [PMID: 35551907 DOI: 10.1016/j.ajo.2022.05.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 04/25/2022] [Accepted: 05/02/2022] [Indexed: 11/30/2022]
Abstract
PURPOSE To investigate longitudinal changes in the retinal and choroidal microstructure of the macula in patients with retinitis pigmentosa (RP). DESIGN Retrospective, observational cohort study. METHODS A total of 69 patients with RP and 69 age- and sex-matched controls who underwent optical coherence tomography (OCT) over a 4-year follow-up period were included. The severity of RP was classified into 3 stages according to the integrity of the inner segment ellipsoid zone. The retinal and choroidal layers were segmented manually from OCT images. The areas of retinal pigment epithelium (RPE) atrophy and choroidal vascular index (CVI) were also analyzed. Longitudinal changes in the OCT parameters were compared among the groups. RESULTS Significant decreases (median [interquartile range]) in the thickness of the ganglion cell inner plexiform layer (GCIPL; -1.04 [-2.41 to -0.17]), outer nuclear layer (ONL; -1.44 [-1.86 to -0.28]), and inner segment ellipsoid (ISE; -0.74 [-1.33 to -0.49]) at the moderate stage and retinal nerve fiber layer (RNFL; -1.49 [-2.08 to -0.66]) and GCIPL (0.58 [-1.79 to 0.06]) at the advanced stage were observed. Choroidal thickness decreased significantly from -7.62 to -9.40 μm per year at all stages. RPE atrophy and CVI reduction were observed at the advanced stage. There was no change in the control group. CONCLUSIONS ONL and GCIPL thicknesses decreased at the moderate and advanced stages of RP; RNFL thickness decreased only at the advanced stage; and choroidal thickness decreased continuously. In addition, RPE atrophy and CVI reduction were prominent at the advanced stage. These results indicate that there is a temporal variation in the damage of each retinal layer and the choroid in RP patients.
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Affiliation(s)
- Chang Ki Yoon
- from the Department of Ophthalmology (C.K.Y., K.H.B., H.G.Y.), Seoul National University College of Medicine, Seoul, Korea; Department of Ophthalmology (C.K.Y., K.H.B., H.G.Y.), Seoul National University Hospital, Seoul, Korea
| | - Kunho Bae
- from the Department of Ophthalmology (C.K.Y., K.H.B., H.G.Y.), Seoul National University College of Medicine, Seoul, Korea; Department of Ophthalmology (C.K.Y., K.H.B., H.G.Y.), Seoul National University Hospital, Seoul, Korea
| | - Hyeong Gon Yu
- from the Department of Ophthalmology (C.K.Y., K.H.B., H.G.Y.), Seoul National University College of Medicine, Seoul, Korea; Department of Ophthalmology (C.K.Y., K.H.B., H.G.Y.), Seoul National University Hospital, Seoul, Korea; Retina Center (H.G.Y.), Sky Eye Institute, Seoul, Korea.
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34
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Sharf T, Kalakuntla T, J Lee D, Gokoffski KK. Electrical devices for visual restoration. Surv Ophthalmol 2022; 67:793-800. [PMID: 34487742 PMCID: PMC9241872 DOI: 10.1016/j.survophthal.2021.08.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 08/24/2021] [Accepted: 08/30/2021] [Indexed: 11/21/2022]
Abstract
Given the rising number of patients with blindness from macular, optic nerve, and visual pathway disease, there is considerable interest in the potential of electrical stimulation devices to restore vision. Electrical devices for restoration of visual function can be grouped into three categories: (1) visual prostheses whose goal is to bypass damaged areas and directly activate downstream intact portions of the visual pathway; (2) electric field stimulation whose goal is to activate endogenous transcriptional and molecular signaling pathways to promote neuroprotection and neuro-regeneration; and (3) neuromodulation whose stimulation would resuscitate neural circuits vital to coordinating responses to visual input. In this review, we discuss these three approaches, describe advances made in the different fields, and comment on limitations and potential future directions.
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Affiliation(s)
- Tamara Sharf
- Keck School of Medicine, University of Southern California, CA, USA
| | - Tej Kalakuntla
- Keck School of Medicine, University of Southern California, CA, USA
| | - Darrin J Lee
- Department of Neurological Surgery, University of Southern California, CA, USA
| | - Kimberly K Gokoffski
- Department of Ophthalmology, Roski Eye Institute, University of Southern California, CA, USA.
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35
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McGregor JE, Kunala K, Xu Z, Murphy PJ, Godat T, Strazzeri JM, Bateman BA, Fischer WS, Parkins K, Chu CJ, Puthussery T, Williams DR, Merigan WH. Optogenetic therapy restores retinal activity in primate for at least a year following photoreceptor ablation. Mol Ther 2022; 30:1315-1328. [PMID: 34547460 PMCID: PMC8899524 DOI: 10.1016/j.ymthe.2021.09.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 08/10/2021] [Accepted: 09/14/2021] [Indexed: 10/20/2022] Open
Abstract
All retina-based vision restoration approaches rely on the assumption that photoreceptor loss does not preclude reactivation of the remaining retinal architecture. Whether extended periods of vision loss limit the efficacy of restorative therapies at the retinal level is unknown. We examined long-term changes in optogenetic responsivity of foveal retinal ganglion cells (RGCs) in non-human primates following localized photoreceptor ablation by high-intensity laser exposure. By performing fluorescence adaptive optics scanning light ophthalmoscopy (AOSLO) of RGCs expressing both the calcium indicator GCaMP6s and the optogenetic actuator ChrimsonR, it was possible to track optogenetic-mediated calcium responses in deafferented RGCs over time. Fluorescence fundus photography revealed a 40% reduction in ChrimsonR fluorescence from RGCs lacking photoreceptor input over the 3 weeks following photoreceptor ablation. Despite this, in vivo imaging revealed good cellular preservation of RGCs 3 months after the loss of photoreceptor input, and histology confirmed good structural preservation at 2 years. Optogenetic responses of RGCs in primate persisted for at least 1 year after the loss of photoreceptor input, with a sensitivity index similar to optogenetic responses recorded in intact retina. These results are promising for all potential therapeutic approaches to vision restoration that rely on preservation and reactivation of RGCs.
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Affiliation(s)
- Juliette E. McGregor
- Center for Visual Science, 601 Crittenden Blvd., University of Rochester Medical Center, Rochester, NY 14642, USA,Corresponding author: Juliette E. McGregor, Center for Visual Science, University of Rochester Medical Center, Rochester, NY 14642, USA.
| | - Karteek Kunala
- Center for Visual Science, 601 Crittenden Blvd., University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Zhengyang Xu
- Institute of Optics, University of Rochester, Rochester, NY 14627, USA
| | - Peter J. Murphy
- Center for Visual Science, 601 Crittenden Blvd., University of Rochester Medical Center, Rochester, NY 14642, USA,Institute of Optics, University of Rochester, Rochester, NY 14627, USA
| | - Tyler Godat
- Center for Visual Science, 601 Crittenden Blvd., University of Rochester Medical Center, Rochester, NY 14642, USA,Institute of Optics, University of Rochester, Rochester, NY 14627, USA
| | - Jennifer M. Strazzeri
- Center for Visual Science, 601 Crittenden Blvd., University of Rochester Medical Center, Rochester, NY 14642, USA,Flaum Eye Institute, University of Rochester, Rochester, NY 14642, USA
| | | | - William S. Fischer
- Center for Visual Science, 601 Crittenden Blvd., University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Keith Parkins
- Center for Visual Science, 601 Crittenden Blvd., University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Colin J. Chu
- Translational Health Sciences, University of Bristol, Bristol BS105NB, United Kingdom
| | - Teresa Puthussery
- School of Optometry & Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA
| | - David R. Williams
- Center for Visual Science, 601 Crittenden Blvd., University of Rochester Medical Center, Rochester, NY 14642, USA,Institute of Optics, University of Rochester, Rochester, NY 14627, USA
| | - William H. Merigan
- Center for Visual Science, 601 Crittenden Blvd., University of Rochester Medical Center, Rochester, NY 14642, USA,Flaum Eye Institute, University of Rochester, Rochester, NY 14642, USA,Corresponding author: William H. Merigan, Center for Visual Science, 601 Crittenden Blvd., University of Rochester Medical Center, Rochester, NY 14642, USA.
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36
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Reh M, Lee M, Zeck G. Expression of Channelrhodopsin‐2 in Rod Bipolar Cells Restores ON and OFF Responses at High Spatial Resolution in Blind Mouse Retina. ADVANCED THERAPEUTICS 2022. [DOI: 10.1002/adtp.202100164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Miriam Reh
- Neurophysics NMI Natural and Medical Sciences Institute at the University of Tübingen 72770 Reutlingen Germany
- Graduate School of Neural Information Processing/ International Max Planck Research School Tübingen Germany
| | - Meng‐Jung Lee
- Neurophysics NMI Natural and Medical Sciences Institute at the University of Tübingen 72770 Reutlingen Germany
- Graduate School of Neural Information Processing/ International Max Planck Research School Tübingen Germany
| | - Günther Zeck
- Neurophysics NMI Natural and Medical Sciences Institute at the University of Tübingen 72770 Reutlingen Germany
- Institute of Biomedical Electronics TU Wien 1040 Vienna Austria
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37
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Wright P, Rodgers J, Wynne J, Bishop PN, Lucas RJ, Milosavljevic N. Viral Transduction of Human Rod Opsin or Channelrhodopsin Variants to Mouse ON Bipolar Cells Does Not Impact Retinal Anatomy or Cause Measurable Death in the Targeted Cells. Int J Mol Sci 2021; 22:ijms222313111. [PMID: 34884916 PMCID: PMC8658283 DOI: 10.3390/ijms222313111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/26/2021] [Accepted: 12/01/2021] [Indexed: 11/16/2022] Open
Abstract
The viral gene delivery of optogenetic actuators to the surviving inner retina has been proposed as a strategy for restoring vision in advanced retinal degeneration. We investigated the safety of ectopic expression of human rod opsin (hRHO), and two channelrhodopsins (enhanced sensitivity CoChR-3M and red-shifted ReaChR) by viral gene delivery in ON bipolar cells of the mouse retina. Adult Grm6Cre mice were bred to be retinally degenerate or non-retinally degenerate (homozygous and heterozygous for the rd1Pde6b mutation, respectively) and intravitreally injected with recombinant adeno-associated virus AAV2/2(quad Y-F) serotype containing a double-floxed inverted transgene comprising one of the opsins of interest under a CMV promoter. None of the opsins investigated caused changes in retinal thickness; induced apoptosis in the retina or in transgene expressing cells; or reduced expression of PKCα (a specific bipolar cell marker). No increase in retinal inflammation at the level of gene expression (IBA1/AIF1) was found within the treated mice compared to controls. The expression of hRHO, CoChR or ReaChR under a strong constitutive promoter in retinal ON bipolar cells following intravitreal delivery via AAV2 does not cause either gross changes in retinal health, or have a measurable impact on the survival of targeted cells.
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38
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Vėbraitė I, David-Pur M, Rand D, Głowacki ED, Hanein Y. Electrophysiological investigation of intact retina with soft printed organic neural interface. J Neural Eng 2021; 18. [PMID: 34736225 DOI: 10.1088/1741-2552/ac36ab] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Accepted: 11/04/2021] [Indexed: 12/26/2022]
Abstract
Objective.Understanding how the retina converts a natural image or an electrically stimulated one into neural firing patterns is the focus of on-going research activities.Ex vivo, the retina can be readily investigated using multi electrode arrays (MEAs). However, MEA recording and stimulation from an intact retina (in the eye) has been so far insufficient.Approach.In the present study, we report new soft carbon electrode arrays suitable for recording and stimulating neural activity in an intact retina. Screen-printing of carbon ink on 20µm polyurethane (PU) film was used to realize electrode arrays with electrodes as small as 40µm in diameter. Passivation was achieved with a holey membrane, realized using laser drilling in a thin (50µm) PU film. Plasma polymerized 3.4-ethylenedioxythiophene was used to coat the electrode array to improve the electrode specific capacitance. Chick retinas, embryonic stage day 13, both explanted and intact inside an enucleated eye, were used.Main results.A novel fabrication process based on printed carbon electrodes was developed and yielded high capacitance electrodes on a soft substrate.Ex vivoelectrical recording of retina activity with carbon electrodes is demonstrated. With the addition of organic photo-capacitors, simultaneous photo-electrical stimulation and electrical recording was achieved. Finally, electrical activity recordings from an intact chick retina (inside enucleated eyes) were demonstrated. Both photosensitive retinal ganglion cell responses and spontaneous retina waves were recorded and their features analyzed.Significance.Results of this study demonstrated soft electrode arrays with unique properties, suitable for simultaneous recording and photo-electrical stimulation of the retina at high fidelity. This novel electrode technology opens up new frontiers in the study of neural tissuein vivo.
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Affiliation(s)
- Ieva Vėbraitė
- School of Electrical Engineering, Tel Aviv University, Tel Aviv, 699780, Israel
| | - Moshe David-Pur
- School of Electrical Engineering, Tel Aviv University, Tel Aviv, 699780, Israel
| | - David Rand
- School of Electrical Engineering, Tel Aviv University, Tel Aviv, 699780, Israel
| | - Eric Daniel Głowacki
- Central European Institute of Technology, Brno University of Technology, Brno, 61200, Czech Republic
| | - Yael Hanein
- School of Electrical Engineering, Tel Aviv University, Tel Aviv, 699780, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 699780, Israel
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39
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Eggenberger SC, James NL, Ho C, Eamegdool SS, Tatarinoff V, Craig NA, Gow BS, Wan S, Dodds CWD, La Hood D, Gilmour A, Donahoe SL, Krockenberger M, Tumuluri K, da Cruz MJ, Grigg JR, McCluskey P, Lovell NH, Madigan MC, Fung AT, Suaning GJ. Implantation and long-term assessment of the stability and biocompatibility of a novel 98 channel suprachoroidal visual prosthesis in sheep. Biomaterials 2021; 279:121191. [PMID: 34768150 DOI: 10.1016/j.biomaterials.2021.121191] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 09/28/2021] [Accepted: 10/18/2021] [Indexed: 11/25/2022]
Abstract
Severe visual impairment can result from retinal degenerative diseases such as retinitis pigmentosa, which lead to photoreceptor cell death. These pathologies result in extensive neural and glial remodelling, with survival of excitable retinal neurons that can be electrically stimulated to elicit visual percepts and restore a form of useful vision. The Phoenix99 Bionic Eye is a fully implantable visual prosthesis, designed to stimulate the retina from the suprachoroidal space. In the current study, nine passive devices were implanted in an ovine model from two days to three months. The impact of the intervention and implant stability were assessed using indirect ophthalmoscopy, infrared imaging, and optical coherence tomography to establish the safety profile of the surgery and the device. The biocompatibility of the device was evaluated using histopathological analysis of the tissue surrounding the electrode array, with a focus on the health of the retinal cells required to convey signals to the brain. Appropriate stability of the electrode array was demonstrated, and histological analysis shows that the fibrotic and inflammatory response to the array was mild. Promising evidence of the safety and potential of the Phoenix99 Bionic Eye to restore a sense of vision to the severely visually impaired was obtained.
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Affiliation(s)
- Samuel C Eggenberger
- School of Biomedical Engineering, Faculty of Engineering, University of Sydney, Sydney, Australia
| | - Natalie L James
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Cherry Ho
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Steven S Eamegdool
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia
| | - Veronika Tatarinoff
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Naomi A Craig
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Barry S Gow
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Susan Wan
- The Westmead Institute for Medical Research, Westmead, Australia
| | - Christopher W D Dodds
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Donna La Hood
- Brien Holden Vision Institute, Sydney, Australia; School of Optometry and Vision Science, University of New South Wales (UNSW), Sydney, Australia
| | - Aaron Gilmour
- School of Biomedical Engineering, Faculty of Engineering, University of Sydney, Sydney, Australia; Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Shannon L Donahoe
- Veterinary Pathology Diagnostic Services, Sydney School of Veterinary Science, University of Sydney, Sydney, Australia
| | - Mark Krockenberger
- Veterinary Pathology Diagnostic Services, Sydney School of Veterinary Science, University of Sydney, Sydney, Australia
| | - Krishna Tumuluri
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia; Westmead Clinical School, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, University of Sydney, Sydney, Australia; Department of Ophthalmology, Faculty of Medicine and Health Sciences, Macquarie University, New South Wales, Australia
| | - Melville J da Cruz
- Department of Otolaryngology, Westmead Hospital, University of Sydney, Sydney, Australia; Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - John R Grigg
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia; Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - Peter McCluskey
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia; Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - Nigel H Lovell
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Michele C Madigan
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia; School of Optometry and Vision Science, University of New South Wales (UNSW), Sydney, Australia
| | - Adrian T Fung
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia; Westmead Clinical School, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, University of Sydney, Sydney, Australia; Department of Ophthalmology, Faculty of Medicine and Health Sciences, Macquarie University, New South Wales, Australia
| | - Gregg J Suaning
- School of Biomedical Engineering, Faculty of Engineering, University of Sydney, Sydney, Australia; Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia.
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Xu Y, Pang S. Microelectrode Array With Integrated Pneumatic Channels for Dynamic Control of Electrode Position in Retinal Implants. IEEE Trans Neural Syst Rehabil Eng 2021; 29:2292-2298. [PMID: 34705653 DOI: 10.1109/tnsre.2021.3123754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Retinal prostheses are biomedical devices that directly utilize electrical stimulation to create an artificial vision to help patients with retinal diseases such as retinitis pigmentosa. A major challenge in the microelectrode array (MEA) design for retinal prosthesis is to have a close topographical fit on the retinal surface. The local retinal topography can cause the electrodes in certain areas to have gaps up to several hundred micrometers from the retinal surface, resulting in impaired, or totally lost electrode functions in specific areas of the MEA. In this manuscript, an MEA with dynamically controlled electrode positions was proposed to reduce the electrode-retina distance and eliminate areas with poor contact after implantation. The MEA prototype had a polydimethylsiloxane and polyimide hybrid flexible substrate with gold interconnect lines and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate electrodes. Ring shaped counter electrodes were placed around the main electrodes to measure the distance between the electrode and the model retinal surface in real time. The results showed that this MEA design could reduce electrode-retina distance up to [Formula: see text] with 200 kPa pressure. Meanwhile, the impedance between the main and counter electrodes increased with smaller electrode-model retinal surface distance. Thus, the change of electrode-counter electrode impedance could be used to measure the separation gap and to confirm successful electrode contact without the need of optical coherence tomography scan. The amplitude of the stimulation signal on the model retinal surface with originally poor contact could be significantly improved after pressure was applied to reduce the gap.
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EPIRETINAL FIBROSIS REMOVAL IN AN ARGUS II-IMPLANTED EYE: Histological Characteristics and Functional Results. Retina 2021; 40:2403-2409. [PMID: 32195788 DOI: 10.1097/iae.0000000000002780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE 1) To investigate morphologic and histochemical characteristics of an epiretinal fibrosis removed in an Argus II-implanted eye; 2) to evaluate the Argus II function before and after the fibrosis removal, and 3) to compare morphologic and functional data. METHODS Fibrosis, which developed between the Argus II prosthesis and the retina two years after implant, was surgically removed. Its morphologic and histochemical characteristics were evaluated both in light and transmission electron microscopy, with special stains and immunohistochemistry. The Argus II function was evaluated during the follow-up before surgical removal and 1 month later. RESULTS Fibrosis was successfully removed. It was composed of a fibrotic tissue with spindle cells arranged in nodular aggregates with a symmetric distribution, mixed with an inflammatory infiltrate. Extra- and intracellular, irregular, small iron particles were found and confirmed ultrastructural characterization with degenerative cellular changes. The repositioned Argus II restored, and its function was partially nearly to normal values 1 month after surgery. CONCLUSION Fibrosis can develop between the Argus II and the retina with increasing reduced function. Morphologic characteristics of the removed fibrosis suggested a pathogenesis based on an inflammatory process involved in a foreign body reaction with progressing connective tissue deposition leading to sclerosis. Adequate clinical follow-up is critical to successful removal of the fibrosis with reactivation of the Argus II function.
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Faber H, Ernemann U, Sachs H, Gekeler F, Danz S, Koitschev A, Besch D, Bartz-Schmidt KU, Zrenner E, Stingl K, Kernstock C. CT Assessment of Intraorbital Cable Movement of Electronic Subretinal Prosthesis in Three Different Surgical Approaches. Transl Vis Sci Technol 2021; 10:16. [PMID: 34264295 PMCID: PMC8299430 DOI: 10.1167/tvst.10.8.16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Purpose Electronic retinal implants restore some visual perception in patients blind from retinitis pigmentosa. Eye movements cause mechanical stress in intraorbital power supply cables leading to cable breaks. By using computer tomography (CT) scans at the extreme positions of the four cardinal gaze directions, this study determined in vivo, which of three surgical routing techniques results in minimal bending radius variation and favors durability. Methods Nine patients received the first-generation subretinal implant Alpha IMS (Retina Implant AG, Reutlingen, Germany) in one eye. Three techniques for intraorbital cable routing were used (straight cable route (A), parabulbar loop (B), and encircling band (C)), each in three patients. All patients underwent computer tomography of the orbital region. The bending radius of the intraorbital cable was measured with the DICOM viewer Osirix v4.1.2 (Pixmeo SARL, Bernex, Switzerland) and served as indicator for mechanical stress. Results Average bending radius variation was 87% for method A, 11% for method B, and 16% for method C. Methods A and B (P = 0.005) and methods A and C (P = 0.007) differed significantly, while method B and C showed no statistical difference (P = 0.07). Conclusions Compared to straight routes, arcuated cable routes significantly reduce cable movement and bending. Due to an easier surgical procedure, a parabulbar loop is the preferred method to minimize bending radius variation and prolong survival time of electronic subretinal implants. Translational Relevance CT analysis of cable bending of implanted medical devices allows to determine which surgical routing technique favors durability in vivo.
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Affiliation(s)
- Hanna Faber
- University Eye Hospital, Center for Ophthalmology, University of Tuebingen, Tuebingen, Germany
| | - Ulrike Ernemann
- Department of Diagnostic and Interventional Neuroradiology, Radiological Clinic, University of Tuebingen, Tuebingen, Germany
| | - Helmut Sachs
- Ophthalmology Clinic, Städtisches Klinikum Dresden Friedrichstadt, Dresden, Germany
| | - Florian Gekeler
- Ophthalmology Clinic, Klinikum Stuttgart, Stuttgart, Germany
| | - Søren Danz
- Radiologische Praxis Hofbauer Danz Fischer, Sindelfingen, Germany
| | - Assen Koitschev
- Clinic for Ear, Nose and Throat Disorders, Plastic Surgery, Klinikum Stuttgart, Stuttgart, Germany
| | - Dorothea Besch
- University Eye Hospital, Center for Ophthalmology, University of Tuebingen, Tuebingen, Germany
| | | | - Eberhart Zrenner
- University Eye Hospital, Center for Ophthalmology, University of Tuebingen, Tuebingen, Germany.,Institute for Ophthalmic Research, Center for Ophthalmology, University of Tuebingen, Tuebingen, Germany.,Werner Reichardt Centre for Integrative Neuroscience, University of Tuebingen, Tuebingen, Germany
| | - Katarina Stingl
- University Eye Hospital, Center for Ophthalmology, University of Tuebingen, Tuebingen, Germany.,Center of Rare Eye Diseases, University of Tuebingen, Tuebingen, Germany
| | - Christoph Kernstock
- University Eye Hospital, Center for Ophthalmology, University of Tuebingen, Tuebingen, Germany
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Masri RA, Weltzien F, Purushothuman S, Lee SCS, Martin PR, Grünert U. Composition of the Inner Nuclear Layer in Human Retina. Invest Ophthalmol Vis Sci 2021; 62:22. [PMID: 34259817 PMCID: PMC8288061 DOI: 10.1167/iovs.62.9.22] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The purpose of this study was to measure the composition of the inner nuclear layer (INL) in the central and peripheral human retina as foundation data for interpreting INL function and dysfunction. Methods Six postmortem human donor retinas (male and female, aged 31–56 years) were sectioned along the temporal horizontal meridian. Sections were processed with immunofluorescent markers and imaged using high-resolution, multichannel fluorescence microscopy. The density of horizontal, bipolar, amacrine, and Müller cells was quantified between 1 and 12 mm eccentricity with appropriate adjustments for postreceptoral spatial displacements near the fovea. Results Cone bipolar cells dominate the INL a with density near 50,000 cells/mm2 at 1 mm eccentricity and integrated total ∼10 million cells up to 10 mm eccentricity. Outside central retina the spatial density of all cell populations falls but the neuronal makeup of the INL remains relatively constant: a decrease in the proportion of cone bipolar cells (from 52% at 1 mm to 37% at 10 mm) is balanced by an increasing proportion of rod bipolar cells (from 9% to 15%). The proportion of Müller cells near the fovea (17%) is lower than in the peripheral retina (27%). Conclusions Despite large changes in the absolute density of INL cell populations across the retina, their proportions remain relatively constant. These data may have relevance for interpreting diagnostic signals such as the electroretinogram and optical coherence tomogram.
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Affiliation(s)
- Rania A Masri
- The University of Sydney, Faculty of Medicine and Health, Save Sight Institute and Discipline of Clinical Ophthalmology, Sydney, Australia.,Australian Research Council Centre of Excellence for Integrative Brain Function, The University of Sydney, Sydney, Australia
| | - Felix Weltzien
- The University of Sydney, Faculty of Medicine and Health, Save Sight Institute and Discipline of Clinical Ophthalmology, Sydney, Australia
| | - Sivaraman Purushothuman
- The University of Sydney, Faculty of Medicine and Health, Save Sight Institute and Discipline of Clinical Ophthalmology, Sydney, Australia
| | - Sammy C S Lee
- The University of Sydney, Faculty of Medicine and Health, Save Sight Institute and Discipline of Clinical Ophthalmology, Sydney, Australia.,Australian Research Council Centre of Excellence for Integrative Brain Function, The University of Sydney, Sydney, Australia
| | - Paul R Martin
- The University of Sydney, Faculty of Medicine and Health, Save Sight Institute and Discipline of Clinical Ophthalmology, Sydney, Australia.,Australian Research Council Centre of Excellence for Integrative Brain Function, The University of Sydney, Sydney, Australia
| | - Ulrike Grünert
- The University of Sydney, Faculty of Medicine and Health, Save Sight Institute and Discipline of Clinical Ophthalmology, Sydney, Australia.,Australian Research Council Centre of Excellence for Integrative Brain Function, The University of Sydney, Sydney, Australia
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Sadeghi R, Kartha A, Barry MP, Bradley C, Gibson P, Caspi A, Roy A, Dagnelie G. Glow in the dark: Using a heat-sensitive camera for blind individuals with prosthetic vision. Vision Res 2021; 184:23-29. [PMID: 33780753 PMCID: PMC8137663 DOI: 10.1016/j.visres.2021.02.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 02/12/2021] [Accepted: 02/28/2021] [Indexed: 11/29/2022]
Abstract
To date, retinal implants are the only available treatment for blind individuals with retinal degenerations such as retinitis pigmentosa. Argus II is the only visual implant with FDA approval, with more than 300 users worldwide. Argus II stimulation is based on a grayscale image coming from a head-mounted visible-light camera. Normally, the 11°×19° field of view of the Argus II user is full of objects that may elicit similar phosphenes. The prosthesis cannot meaningfully convey so much visual information, and the percept is reduced to an ambiguous impression of light. This study is aimed at investigating the efficacy of simplifying the video input in real-time using a heat-sensitive camera. Data were acquired from four Argus II users in 5 stationary tasks with either hot objects or human targets as stimuli. All tasks were of m-alternative forced choice design where precisely one of the m≥2 response alternatives was defined to be "correct" by the experimenter. To compare performance with heat-sensitive and normal cameras across all tasks, regardless of m, we used an extension of signal detection theory to latent variables, estimating person ability and item difficulty in d' units. Results demonstrate that subject performance was significantly better across all tasks with the thermal camera compared to the regular Argus II camera. The future addition of thermal imaging to devices with very poor spatial resolution may have significant real-life benefits for orientation, personal safety, and social interactions, thereby improving quality of life.
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Affiliation(s)
- Roksana Sadeghi
- Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Arathy Kartha
- Department of Ophthalmology, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | | | - Chris Bradley
- Department of Ophthalmology, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Paul Gibson
- Advanced Medical Electronics Corporation, Maple Grove, MN, USA
| | - Avi Caspi
- Second Sight Medical Products, Sylmar, CA, USA; Jerusalem College of Technology, Jerusalem, Israel
| | - Arup Roy
- Second Sight Medical Products, Sylmar, CA, USA
| | - Gislin Dagnelie
- Department of Ophthalmology, Johns Hopkins School of Medicine, Baltimore, MD, USA
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Phototoxicities Caused by Continuous Light Exposure Were Not Induced in Retinal Ganglion Cells Transduced by an Optogenetic Gene. Int J Mol Sci 2021; 22:ijms22136732. [PMID: 34201658 PMCID: PMC8269149 DOI: 10.3390/ijms22136732] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/16/2021] [Accepted: 06/22/2021] [Indexed: 11/16/2022] Open
Abstract
The death of photoreceptor cells is induced by continuous light exposure. However, it is unclear whether light damage was induced in retinal ganglion cells with photosensitivity by transduction of optogenetic genes. In this study, we evaluated the phototoxicities of continuous light exposure on retinal ganglion cells after transduction of the optogenetic gene mVChR1 using an adeno-associated virus vector. Rats were exposed to continuous light for a week, and visually evoked potentials (VEPs) were recorded. The intensities of continuous light (500, 1000, 3000, and 5000 lx) increased substantially after VEP recordings. After the final recording of VEPs, retinal ganglion cells (RGCs) were retrogradely labeled with a fluorescein tracer, FluoroGold, and the number of retinal ganglion cells was counted under a fluorescent microscope. There was no significant reduction in the amplitudes of VEPs and the number of RGCs after exposure to any light intensity. These results indicated that RGCs were photosensitive after the transduction of optogenetic genes and did not induce any phototoxicity by continuous light exposure.
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Allen PJ. Retinal prostheses: Where to from here? Clin Exp Ophthalmol 2021; 49:418-429. [PMID: 34021959 DOI: 10.1111/ceo.13950] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 05/05/2021] [Accepted: 05/09/2021] [Indexed: 11/29/2022]
Abstract
Researchers have been working towards the development of retinal prostheses, so called "bionic eyes" since the 1960s in an effort to restore functional vision to severely visually impaired patients. Groups from all around the world are involved in this research but in particular, groups from the United States, Germany, France, Japan and Australia have conducted clinical trials of these devices and three of these devices have achieved either FDA HDE (U.S. Food and Drug Administration Humanitarian Device Exception) or CE mark approval for commercial production. Despite this, all three of these devices are now not in commercial production. There are many challenges to overcome to develop devices suitable to implant in human patients and then reach commercial distribution. This is an exacting process and many hurdles need to be overcome to reach this point so that leaving the market after achieving this goal is a significant decision. Ongoing research is exploring the possibility of less complicated surgery with better visual processing algorithms to provide more useful visual information for our patients to provide a commercial alternative.
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Affiliation(s)
- Penelope J Allen
- The Centre for Eye Research Australia, East Melbourne, Australia.,Department of Surgery (Ophthalmology), University of Melbourne, Melbourne, Australia.,The Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
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Gaillet V, Borda E, Zollinger EG, Ghezzi D. A machine-learning algorithm correctly classifies cortical evoked potentials from both visual stimulation and electrical stimulation of the optic nerve. J Neural Eng 2021; 18. [PMID: 33823498 DOI: 10.1088/1741-2552/abf523] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 04/06/2021] [Indexed: 11/12/2022]
Abstract
Objective. Optic nerve's intraneural stimulation is an emerging neuroprosthetic approach to provide artificial vision to totally blind patients. An open question is the possibility to evoke individual non-overlapping phosphenes via selective intraneural optic nerve stimulation. To begin answering this question, first, we aim at showing in preclinical experiments with animals that each intraneural electrode could evoke a distinguishable activity pattern in the primary visual cortex.Approach. We performed both patterned visual stimulation and patterned electrical stimulation in healthy rabbits while recording evoked cortical activity with an electrocorticogram array in the primary visual cortex. Electrical stimulation was delivered to the optic nerve with the intraneural array OpticSELINE. We used a support vector machine algorithm paired to a linear regression model to classify cortical responses originating from visual stimuli located in different portions of the visual field and electrical stimuli from the different electrodes of the OpticSELINE.Main results. Cortical activity induced by visual and electrical stimulation could be classified with nearly 100% accuracy relative to the specific location in the visual field or electrode in the array from which it originated. For visual stimulation, the accuracy increased with the separation of the stimuli and reached 100% for separation higher than 7°. For electrical stimulation, at low current amplitudes, the accuracy increased with the distance between electrodes, while at higher current amplitudes, the accuracy was nearly 100% already for the shortest separation.Significance. Optic nerve's intraneural stimulation with the OpticSELINE induced discernible cortical activity patterns. These results represent a necessary condition for an optic nerve prosthesis to deliver vision with non-overlapping phosphene. However, clinical investigations will be required to assess the translation of these results into perceptual phenomena.
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Affiliation(s)
- Vivien Gaillet
- Medtronic Chair in Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Engineering, École Polytechnique fédérale de Lausanne, Geneva 1202, Switzerland
| | - Eleonora Borda
- Medtronic Chair in Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Engineering, École Polytechnique fédérale de Lausanne, Geneva 1202, Switzerland
| | - Elodie Geneviève Zollinger
- Medtronic Chair in Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Engineering, École Polytechnique fédérale de Lausanne, Geneva 1202, Switzerland
| | - Diego Ghezzi
- Medtronic Chair in Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, School of Engineering, École Polytechnique fédérale de Lausanne, Geneva 1202, Switzerland
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Hadjinicolaou AE, Meffin H, Maturana MI, Cloherty SL, Ibbotson MR. Prosthetic vision: devices, patient outcomes and retinal research. Clin Exp Optom 2021; 98:395-410. [DOI: 10.1111/cxo.12342] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 07/06/2015] [Accepted: 08/04/2015] [Indexed: 12/11/2022] Open
Affiliation(s)
- Alex E Hadjinicolaou
- National Vision Research Institute, Australian College of Optometry, Carlton, Victoria, Australia,
- ARC Centre of Excellence for Integrative Brain Function and Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia,
| | - Hamish Meffin
- National Vision Research Institute, Australian College of Optometry, Carlton, Victoria, Australia,
- ARC Centre of Excellence for Integrative Brain Function and Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia,
| | - Matias I Maturana
- National Vision Research Institute, Australian College of Optometry, Carlton, Victoria, Australia,
- Department of Electrical and Electronic Engineering, The University of Melbourne, Parkville, Victoria, Australia,
| | - Shaun L Cloherty
- National Vision Research Institute, Australian College of Optometry, Carlton, Victoria, Australia,
- ARC Centre of Excellence for Integrative Brain Function and Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia,
- Department of Electrical and Electronic Engineering, The University of Melbourne, Parkville, Victoria, Australia,
| | - Michael R Ibbotson
- National Vision Research Institute, Australian College of Optometry, Carlton, Victoria, Australia,
- ARC Centre of Excellence for Integrative Brain Function and Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia,
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Schick R, Farah N, Markus A, Korngreen A, Mandel Y. Electrophysiologic Characterization of Developing Human Embryonic Stem Cell-Derived Photoreceptor Precursors. Invest Ophthalmol Vis Sci 2021; 61:44. [PMID: 32991686 PMCID: PMC7533729 DOI: 10.1167/iovs.61.11.44] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Purpose Photoreceptor precursor cells (PRPs) differentiated from human embryonic stem cells can serve as a source for cell replacement therapy aimed at vision restoration in patients suffering from degenerative diseases of the outer retina, such as retinitis pigmentosa and AMD. In this work, we studied the electrophysiologic maturation of PRPs throughout the differentiation process. Methods Human embryonic stem cells were differentiated into PRPs and whole-cell recordings were performed for electrophysiologic characterization at days 0, 30, 60, and 90 along with quantitative PCR analysis to characterize the expression level of various ion channels, which shape the electrophysiologic response. Finally, to characterize the electrically induced calcium currents, we employed calcium imaging (rhod4) to visualize intracellular calcium dynamics in response to electrical activation. Results Our results revealed an early and steady presence (approximately 100% of responsive cells) of the delayed potassium rectifier current. In contrast, the percentage of cells exhibiting voltage-gated sodium currents increased with maturation (from 0% to almost 90% of responsive cells at 90 days). Moreover, calcium imaging revealed the presence of voltage-gated calcium currents, which play a major role in vision formation. These results were further supported by quantitative PCR analysis, which revealed a significant and continuous (3- to 50-fold) increase in the expression of various voltage-gated channels concomitantly with the increase in the expression of the photoreceptor marker CRX. Conclusions These results can shed light on the electrophysiologic maturation of neurons in general and PRP in particular and can form the basis for devising and optimizing cell replacement-based vision restoration strategies.
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Affiliation(s)
- Revital Schick
- School of Optometry and Visual Science, Faculty of Life Science and Bar-Ilan Institute for Nanotechnology and Advanced material (BINA), Bar-Ilan University, Ramat-Gan, Israel
| | - Nairouz Farah
- School of Optometry and Visual Science, Faculty of Life Science and Bar-Ilan Institute for Nanotechnology and Advanced material (BINA), Bar-Ilan University, Ramat-Gan, Israel
| | - Amos Markus
- School of Optometry and Visual Science, Faculty of Life Science and Bar-Ilan Institute for Nanotechnology and Advanced material (BINA), Bar-Ilan University, Ramat-Gan, Israel
| | - Alon Korngreen
- Faculty of Life Science and The Leslie and Susan Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan, Israel
| | - Yossi Mandel
- School of Optometry and Visual Science, Faculty of Life Science and Bar-Ilan Institute for Nanotechnology and Advanced material (BINA), Bar-Ilan University, Ramat-Gan, Israel
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Li W, Qin S, Lu Y, Wang H, Xu Z, Wu T. A facile and comprehensive algorithm for electrical response identification in mouse retinal ganglion cells. PLoS One 2021; 16:e0246547. [PMID: 33705406 PMCID: PMC7951861 DOI: 10.1371/journal.pone.0246547] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 01/20/2021] [Indexed: 12/01/2022] Open
Abstract
Retinal prostheses can restore the basic visual function of patients with retinal degeneration, which relies on effective electrical stimulation to evoke the physiological activities of retinal ganglion cells (RGCs). Current electrical stimulation strategies have defects such as unstable effects and insufficient stimulation positions, therefore, it is crucial to determine the optimal pulse parameters for precise and safe electrical stimulation. Biphasic voltages (cathode-first) with a pulse width of 25 ms and different amplitudes were used to ex vivo stimulate RGCs of three wild-type (WT) mice using a commercial microelectrode array (MEA) recording system. An algorithm is developed to automatically realize both spike-sorting and electrical response identification for the spike signals recorded. Measured from three WT mouse retinas, the total numbers of RGC units and responsive RGC units were 1193 and 151, respectively. In addition, the optimal pulse amplitude range for electrical stimulation was determined to be 0.43 V-1.3 V. The processing results of the automatic algorithm we proposed shows high consistency with those using traditional manual processing. We anticipate the new algorithm can not only speed up the elaborate electrophysiological data processing, but also optimize pulse parameters for the electrical stimulation strategy of neural prostheses.
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Affiliation(s)
- Wanying Li
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Shan Qin
- Shenzhen Shekou People’s Hospital, Shenzhen, China
| | - Yijie Lu
- Shenzhen Aier Eye Hospital, Shenzhen, China
| | - Hao Wang
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Zhen Xu
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
- * E-mail: (TZW); (ZX)
| | - Tianzhun Wu
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
- * E-mail: (TZW); (ZX)
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