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Zhang B, Zhang R, Zhao J, Yang J, Xu S. The mechanism of human color vision and potential implanted devices for artificial color vision. Front Neurosci 2024; 18:1408087. [PMID: 38962178 PMCID: PMC11221215 DOI: 10.3389/fnins.2024.1408087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 05/31/2024] [Indexed: 07/05/2024] Open
Abstract
Vision plays a major role in perceiving external stimuli and information in our daily lives. The neural mechanism of color vision is complicated, involving the co-ordinated functions of a variety of cells, such as retinal cells and lateral geniculate nucleus cells, as well as multiple levels of the visual cortex. In this work, we reviewed the history of experimental and theoretical studies on this issue, from the fundamental functions of the individual cells of the visual system to the coding in the transmission of neural signals and sophisticated brain processes at different levels. We discuss various hypotheses, models, and theories related to the color vision mechanism and present some suggestions for developing novel implanted devices that may help restore color vision in visually impaired people or introduce artificial color vision to those who need it.
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Affiliation(s)
- Bingao Zhang
- Key Laboratory for the Physics and Chemistry of Nanodevices, Institute of Physical Electronics, Department of Electronics, Peking University, Beijing, China
| | - Rong Zhang
- Key Laboratory for the Physics and Chemistry of Nanodevices, Institute of Physical Electronics, Department of Electronics, Peking University, Beijing, China
| | - Jingjin Zhao
- Key Laboratory for the Physics and Chemistry of Nanodevices, Institute of Physical Electronics, Department of Electronics, Peking University, Beijing, China
| | - Jiarui Yang
- Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Department of Ophthalmology, Peking University Third Hospital, Beijing, China
| | - Shengyong Xu
- Key Laboratory for the Physics and Chemistry of Nanodevices, Institute of Physical Electronics, Department of Electronics, Peking University, Beijing, China
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Lohler P, Albert A, Erbsloh A, Nruthyathi, Muller F, Seidl K. A Cell-Type Selective Stimulation and Recording System for Retinal Ganglion Cells. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2024; 18:498-510. [PMID: 38096095 DOI: 10.1109/tbcas.2023.3342465] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Future retinal implants will require a stimulation selectivity between different sub-types of Retinal Ganglion Cells (RGCs) to evoke natural perceptions rather than phosphenes in patients. To achieve this, a cell-type specific stimulation pipeline is required that identifies target RGC sub-types from recorded input images and extracts the specific stimulation parameters to activate this cell-type selectively. Promising biological experiments showed that ON-/OFF- sustained/transient RGCs could be selectively activated by modulating repetition rate and amplitude of an electrical stimulation current in the kilohertz range. This research presents a 42 channel current controlled stimulation and recording system on chip (SoC) with parameter input from a real time target RGC selection algorithm. The SoC is able to stimulate retinal tissue with sinusoidal frequencies higher than 1 kHz at amplitudes of up to 200 μA at a supply voltage of 1.8 V. It also includes tunable recording units with an integrated action potential detection pipeline that are able to amplify signals between 1 Hz and 50 kHz. The required area of one stimulator is 0.0071 mm2, while one recording unit consumes an area of 0.0092 mm2. The application of sinusoidal stimulation currents in the kilohertz range towards retinal tissue leads to a suppressive response of only certain RGC sub-types that has not been oberved before, using electrical stimulation. Because this response is very similar to the natural light response of RGCs, this stimulation approach can lead to a more genuine visual perception for patients using retinal implants.
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Zueva MV, Neroeva NV, Zhuravleva AN, Bogolepova AN, Kotelin VV, Fadeev DV, Tsapenko IV. Fractal Phototherapy in Maximizing Retina and Brain Plasticity. ADVANCES IN NEUROBIOLOGY 2024; 36:585-637. [PMID: 38468055 DOI: 10.1007/978-3-031-47606-8_31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
The neuroplasticity potential is reduced with aging and impairs during neurodegenerative diseases and brain and visual system injuries. This limits the brain's capacity to repair the structure and dynamics of its activity after lesions. Maximization of neuroplasticity is necessary to provide the maximal CNS response to therapeutic intervention and adaptive reorganization of neuronal networks in patients with degenerative pathology and traumatic injury to restore the functional activity of the brain and retina.Considering the fractal geometry and dynamics of the healthy brain and the loss of fractality in neurodegenerative pathology, we suggest that the application of self-similar visual signals with a fractal temporal structure in the stimulation therapy can reactivate the adaptive neuroplasticity and enhance the effectiveness of neurorehabilitation. This proposition was tested in the recent studies. Patients with glaucoma had a statistically significant positive effect of fractal photic therapy on light sensitivity and the perimetric MD index, which shows that methods of fractal stimulation can be a novel nonpharmacological approach to neuroprotective therapy and neurorehabilitation. In healthy rabbits, it was demonstrated that a long-term course of photostimulation with fractal signals does not harm the electroretinogram (ERG) and retina structure. Rabbits with modeled retinal atrophy showed better dynamics of the ERG restoration during daily stimulation therapy for a week in comparison with the controls. Positive changes in the retinal function can indirectly suggest the activation of its adaptive plasticity and the high potential of stimulation therapy with fractal visual stimuli in a nonpharmacological neurorehabilitation, which requires further study.
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Affiliation(s)
- Marina V Zueva
- Department of Clinical Physiology of Vision, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Natalia V Neroeva
- Department of Pathology of the Retina and Optic Nerve, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Anastasia N Zhuravleva
- Department of Glaucoma, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Anna N Bogolepova
- Department of neurology, neurosurgery and medical genetics, Pirogov Russian National Research Medical University, Moscow, Russia
| | - Vladislav V Kotelin
- Department of Clinical Physiology of Vision, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Denis V Fadeev
- Scientific Experimental Center Department, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Irina V Tsapenko
- Department of Clinical Physiology of Vision, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
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Ramirez KA, Drew-Bear LE, Vega-Garces M, Betancourt-Belandria H, Arevalo JF. An update on visual prosthesis. Int J Retina Vitreous 2023; 9:73. [PMID: 37996905 PMCID: PMC10668475 DOI: 10.1186/s40942-023-00498-1] [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: 06/26/2023] [Accepted: 09/17/2023] [Indexed: 11/25/2023] Open
Abstract
PURPOSE To review the available evidence on the different retinal and visual prostheses for patients with retinitis pigmentosa and new implants for other indications including dry age-related macular degeneration. METHODS The PubMed, GoogleScholar, ScienceDirect, and ClinicalTrials databases were the main resources used to conduct the medical literature search. An extensive search was performed to identify relevant articles concerning the worldwide advances in retinal prosthesis, clinical trials, status of devices and potential future directions up to December 2022. RESULTS Thirteen devices were found to be current and were ordered by stimulation location. Six have active clinical trials. Four have been discontinued, including the Alpha IMS, Alpha AMS, IRIS II, and ARGUS II which had FDA and CE mark approval. Future directions will be presented in the review. CONCLUSION This review provides an update of retinal prosthetic devices, both current and discontinued. While some devices have achieved visual perception in animals and/or humans, the main issues impeding the commercialization of these devices include: increased length of time to observe outcomes, difficulties in finding validated meaures for use in studies, unknown long-term effects, lack of funding, and a low amount of patients simultaneously diagnosed with RP lacking other comorbid conditions. The ARGUS II did get FDA and CE mark approval so it was deemed safe and also effective. However, the company became more focused on a visual cortical implant. Future efforts are headed towards more biocompatible, safe, and efficacious devices.
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Affiliation(s)
- Kailyn A Ramirez
- Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, 08901, USA
| | - Laura E Drew-Bear
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Maumenee 713, Baltimore, MD, 21287, USA
| | | | | | - J Fernando Arevalo
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Maumenee 713, Baltimore, MD, 21287, USA.
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Laspro M, Chaya BF, Brydges HT, Dave N, Thys E, Onuh OC, Tran D, Kimberly LL, Ceradini DJ, Rodriguez ED. Technical Feasibility of Whole-eye Vascular Composite Allotransplantation: A Systematic Review. PLASTIC AND RECONSTRUCTIVE SURGERY-GLOBAL OPEN 2023; 11:e4946. [PMID: 37113307 PMCID: PMC10129168 DOI: 10.1097/gox.0000000000004946] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 02/22/2023] [Indexed: 04/29/2023]
Abstract
There are over 43 million individuals in the world who are blind. As retinal ganglion cells are incapable of regeneration, treatment modalities for this condition are limited. Since first incepted in 1885, whole-eye transplantation (WET) has been proposed as the ultimate cure for blindness. As the field evolves, different aspects of the surgery have been individually explored, including allograft viability, retinal survival, and optic nerve regeneration. Due to the paucity in the WET literature, we aimed to systematically review proposed WET surgical techniques to assess surgical feasibility. Additionally, we hope to identify barriers to future clinical application and potential ethical concerns that could be raised with surgery. Methods We conducted a systematic review of PubMed, Embase, Cochrane Library, and Scopus from inception to June 10, 2022, to identify articles pertaining to WET. Data collection included model organisms studied, surgical techniques utilized, and postoperative functional outcomes. Results Our results yielded 33 articles, including 14 mammalian and 19 cold-blooded models. In studies performing microvascular anastomosis in mammals, 96% of allografts survived after surgery. With nervous coaptation, 82.9% of retinas had positive electroretinogram signals after surgery, indicating functional retinal cells after transplantation. Results on optic nerve function were inconclusive. Ocular-motor functionality was rarely addressed. Conclusions Regarding allograft survival, WET appears feasible with no complications to the recipient recorded in previous literature. Functional restoration is potentially achievable with a demonstrated positive retinal survival in live models. Nevertheless, the potential of optic nerve regeneration remains undetermined.
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Affiliation(s)
- Matteo Laspro
- From the Hansjörg Wyss Department of Plastic Surgery, NYU Grossman School of Medicine, New York, N.Y
| | - Bachar F. Chaya
- From the Hansjörg Wyss Department of Plastic Surgery, NYU Grossman School of Medicine, New York, N.Y
| | - Hilliard T. Brydges
- From the Hansjörg Wyss Department of Plastic Surgery, NYU Grossman School of Medicine, New York, N.Y
| | - Nikhil Dave
- From the Hansjörg Wyss Department of Plastic Surgery, NYU Grossman School of Medicine, New York, N.Y
| | - Erika Thys
- From the Hansjörg Wyss Department of Plastic Surgery, NYU Grossman School of Medicine, New York, N.Y
| | - Ogechukwu C. Onuh
- From the Hansjörg Wyss Department of Plastic Surgery, NYU Grossman School of Medicine, New York, N.Y
| | - David Tran
- From the Hansjörg Wyss Department of Plastic Surgery, NYU Grossman School of Medicine, New York, N.Y
| | - Laura L. Kimberly
- From the Hansjörg Wyss Department of Plastic Surgery, NYU Grossman School of Medicine, New York, N.Y
- Department of Population Health, NYU Grossman School of Medicine, New York, N.Y
| | - Daniel J. Ceradini
- From the Hansjörg Wyss Department of Plastic Surgery, NYU Grossman School of Medicine, New York, N.Y
| | - Eduardo D. Rodriguez
- From the Hansjörg Wyss Department of Plastic Surgery, NYU Grossman School of Medicine, New York, N.Y
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Daich Varela M, Cabral de Guimaraes TA, Georgiou M, Michaelides M. Leber congenital amaurosis/early-onset severe retinal dystrophy: current management and clinical trials. Br J Ophthalmol 2021; 106:445-451. [PMID: 33712480 PMCID: PMC8961750 DOI: 10.1136/bjophthalmol-2020-318483] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 01/18/2021] [Accepted: 02/23/2021] [Indexed: 12/26/2022]
Abstract
Leber congenital amaurosis (LCA) is a severe congenital/early-onset retinal dystrophy. Given its monogenic nature and the immunological and anatomical privileges of the eye, LCA has been particularly targeted by cutting-edge research. In this review, we describe the current management of LCA, and highlight the clinical trials that are on-going and planned. RPE65-related LCA pivotal trials, which culminated in the first Food and Drug Administration-approved and European Medicines Agency-approved ocular gene therapy, have paved the way for a new era of genetic treatments in ophthalmology. At present, multiple clinical trials are available worldwide applying different techniques, aiming to achieve better outcomes and include more genes and variants. Genetic therapy is not only implementing gene supplementation by the use of adeno-associated viral vectors, but also clustered regularly interspaced short palindromic repeats (CRISPR)-mediated gene editing and post-transcriptional regulation through antisense oligonucleotides. Pharmacological approaches intending to decrease photoreceptor degeneration by supplementing 11-cis-retinal and cell therapy’s aim to replace the retinal pigment epithelium, providing a trophic and metabolic retinal structure, are also under investigation. Furthermore, optoelectric devices and optogenetics are also an option for patients with residual visual pathway. After more than 10 years since the first patient with LCA received gene therapy, we also discuss future challenges, such as the overlap between different techniques and the long-term durability of efficacy. The next 5 years are likely to be key to whether genetic therapies will achieve their full promise, and whether stem cell/cellular therapies will break through into clinical trial evaluation.
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Affiliation(s)
- Malena Daich Varela
- UCL Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital NHS Foundation Trust, London, London, UK
| | | | - Michalis Georgiou
- UCL Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital NHS Foundation Trust, London, London, UK
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital NHS Foundation Trust, London, London, UK
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Abbouda A, Avogaro F, Moosajee M, Vingolo EM. Update on Gene Therapy Clinical Trials for Choroideremia and Potential Experimental Therapies. MEDICINA (KAUNAS, LITHUANIA) 2021; 57:64. [PMID: 33445564 PMCID: PMC7826687 DOI: 10.3390/medicina57010064] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 12/26/2020] [Accepted: 01/07/2021] [Indexed: 12/27/2022]
Abstract
Background and objectives: Choroideremia (CHM) is an X-linked recessive chorioretinal dystrophy caused by mutations involving the CHM gene. Gene therapy has entered late-phase clinical trials, although there have been variable results. This review gives a summary on the outcomes of phase I/II CHM gene therapy trials and describes other potential experimental therapies. Materials and Methods: A Medline (National Library of Medicine, Bethesda, MD, USA) search was performed to identify all articles describing gene therapy treatments available for CHM. Results: Five phase I/II clinical trials that reported subretinal injection of adeno-associated virus Rab escort protein 1 (AAV2.REP1) vector in CHM patients were included. The Oxford study (NCT01461213) included 14 patients; a median gain of 5.5 ± 6.8 SD (-6 min, 18 max) early treatment diabetic retinopathy study (ETDRS) letters was reported. The Tubingen study (NCT02671539) included six patients; only one patient had an improvement of 17 ETDRS letters. The Alberta study (NCT02077361) enrolled six patients, and it reported a minimal vision change, except for one patient who gained 15 ETDRS letters. Six patients were enrolled in the Miami trial (NCT02553135), which reported a median gain of 2 ± 4 SD (-1 min, 10 max) ETDRS letters. The Philadelphia study (NCT02341807) included 10 patients; best corrected visual acuity (BCVA) returned to baseline in all by one-year follow-up, but one patient had -17 ETDRS letters from baseline. Overall, 40 patients were enrolled in trials, and 34 had 2 years of follow-up, with a median gain of 1.5 ± 7.2 SD (-14 min, 18 max) in ETDRS letters. Conclusions: The primary endpoint, BCVA following gene therapy in CHM, showed a marginal improvement with variability between trials. Optimizing surgical technique and pre-, peri-, and post-operative management with immunosuppressants to minimize any adverse ocular inflammatory events could lead to reduced incidence of complications. The ideal therapeutic window needs to be addressed to ensure that the necessary cell types are adequately transduced, minimizing viral toxicity, to prolong long-term transgenic potential. Long-term efficacy will be addressed by ongoing studies.
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Affiliation(s)
| | - Filippo Avogaro
- Department of Sense Organs, Faculty of Medicine and Odontology, Sapienza University of Rome, p.le A. Moro 5, 00185 Rome, Italy;
| | - Mariya Moosajee
- UCL Institute of Ophthalmology, London EC1V 9EL, UK;
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
- Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK
- The Francis Crick Institute, London NW1 1AT, UK
| | - Enzo Maria Vingolo
- Fiorini Hospital Terracina AUSL, 04019 Terracina, Latina, Italy;
- Department of Sense Organs, Faculty of Medicine and Odontology, Sapienza University of Rome, p.le A. Moro 5, 00185 Rome, Italy;
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