Background: The restoration of vision in blind patients suffering from degenerative retinal diseases like retinitis pigmentosa (RP) may be obtained by local electrical stimulation with retinal implants.a#13; In this study, a very large electrode array for retinal stimulation (VLARS) was introduced and tested regarding its safety in implantation and biocompatibility. Further, the array's stimulation capabilities were tested in an acute setting.a#13; Material and Method: The polyimide-based implants have a diameter of 12 mm, cover approximately 110 mm² of the retinal surface and carrying 250 iridium oxide coated gold electrodes. a#13; The implantation surgery was established in cadaveric porcine eyes. To analyze biocompatibility, ten rabbits were implanted with the VLARS device, and observed for 12 weeks using slit lamp examination, fundus photography, optical coherence tomography (OCT) as well as ultrasound imaging. After enucleation, histological examinations were performed.a#13; In acute stimulation experiments, electrodes recorded cortical field potentials upon retinal stimulation in the visual cortex in rabbits. a#13; Results: Implantation studies in rabbits showed that the implantation surgery is safe but difficult. Retinal detachment induced by retinal tears was observed in five animals in varying severity. In five cases, corneal edema reduced the quality of the follow-up examinations. Findings in OCT-imaging and funduscopy suggested that peripheral fixation was insufficient in various animals. Results of the acute stimulation demonstrated the array's ability to elicit cortical responses.a#13; Conclusion: Overall, it was possible to implant very large epiretinal arrays. The VLARS elicits cortical answers corresponding to the position of the retinal stimulation. The VLARS device offers the opportunity to restore a much larger field of visual perception when compared to current available retinal implants.a#13;
PURPOSE OF REVIEW: The purpose of this review is to provide an update on the efforts to restore vision through subretinal implants in patients with degenerative retinal diseases. In addition to the current technique and its latest improvements, it will focus on the surgical technique of implantation as well as explantation and reimplantation. RECENT FINDINGS: The durability of the current subretinal implant RETINA IMPLANT Alpha AMS has increased substantially compared with the predecessor model ...
Last. Diego Ghezzi(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 21
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Retinal prostheses have been developed to fight blindness in people affected by outer retinal layer dystrophies. To date, few hundred patients have received a retinal implant. Inspired by intraocular lenses, we have designed a foldable and photovoltaic wide-field epiretinal prosthesis (named POLYRETINA) capable of stimulating wireless retinal ganglion cells. Here we show that within a visual angle of 46.3 degrees, POLYRETINA embeds 2215 stimulating pixels, of which 967 are in the central area of...
Purpose: Following successful clinical outcomes of the prototype suprachoroidal retinal prosthesis, Bionic Vision Australia has developed an upgraded 44-channel suprachoroidal retinal prosthesis to provide a wider field of view and more phosphenes. The aim was to evaluate the preclinical passive safety characteristics of the upgraded electrode array. Methods: Ten normal-sighted felines were unilaterally implanted with an array containing platinum electrodes (44 stimulating and 2 returns) on a si...
#1Lan Yue(SC: University of Southern California)H-Index: 5
#2James D. Weiland(SC: University of Southern California)H-Index: 60
Last. Mark S. Humayun(SC: University of Southern California)H-Index: 85
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Retinal degeneration, a leading cause of blindness worldwide, is primarily characterized by the dysfunctional/degenerated photoreceptors that impair the ability of the retina to detect light. Our group and others have shown that bioelectronic retinal implants restore useful visual input to those who have been blind for decades. This unprecedented approach of restoring sight demonstrates that patients can adapt to new visual input, and thereby opens up opportunities to not only improve this techn...
Since the 1950s, vision researchers have been working towards the ambitious goal of restoring a functional level of vision to the blind via electrical stimulation of the visual pathways. Groups based in Australia, USA, Germany, France and Japan report progress in the translation of retinal visual prosthetics from the experimental to clinical domains, with two retinal visual prostheses having recently received regulatory approval for clinical use. Regulatory approval for cortical visual prosthese...
Purpose To investigate the safety and efficacy of a newly-developed wide-field dual-array suprachoroidal–transretinal stimulation (STS) prosthesis in middle-sized animals.
This review focuses on a description of the Argus II retinal prosthesis system (Argus II; Second Sight Medical Products, Sylmar, CA) that was approved for humanitarian use by the FDA in 2013 in patients with retinitis pigmentosa with bare or no light perception vision. The article describes the components of Argus II, the studies on the implant, and future directions.
#1Tai-Chi Lin(NYMU: National Yang-Ming University)H-Index: 10
#2Hua-Ming Chang(NCU: National Central University)H-Index: 3
Last. Shih-Jen Chen(Taipei Veterans General Hospital)H-Index: 25
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Abstract Degenerative retinal diseases may lead to significant loss of vision. Age-related macular degeneration (AMD) and retinitis pigmentosa (RP), which eventually affect the photoreceptors, are the two most common retinal degenerative diseases. Once the photoreceptorcells are lost, there are no known effective therapies for AMD or RP. The concept of retinal prosthesis is to elicit neural activity in the remaining retinal neurons by detecting light and converting it into electrical stimuli usi...
#1Diego Ghezzi(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 21
In the last decade, various clinical trials proved the capability of visual prostheses, in particular retinal implants, to restore a useful form of vision. These encouraging results promoted the emerging of several strategies for neuronal stimulation aiming at the restoration of sight. Besides the traditional approach based on electrical stimulation through metal electrodes in the different areas of the visual path (e.g., the visual cortex, the lateral geniculate nucleus, the optic nerve, and th...
#1Vivien Gaillet(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 1
#2Eleonora Borda(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 1
Last. Diego Ghezzi(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 21
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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 pe...
ObjectiveOptic nerves 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. ApproachWe perfo...
Last. Diego Ghezzi(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 21
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Retinal prostheses hold the promise of restoring vision in totally blind people. However, a decade of clinical trials highlighted quantitative limitations hampering the possibility of reaching this goal. A key challenge in retinal stimulation is to independently activate retinal neurons over a large portion of the subject’s visual field. Reaching such a goal would significantly improve the perception accuracy in retinal implants’ users, along with their spatial cognition, attention, ambient mapp...
Objective.To restore central vision in patients with atrophic age-related macular degeneration, we replace the lost photoreceptors with photovoltaic pixels, which convert light into current and stimulate the secondary retinal neurons. Clinical trials demonstrated prosthetic acuity closely matching the sampling limit of the 100 μm pixels, and hence smaller pixels are required for improving visual acuity. However, with smaller flat bipolar pixels, the electric field penetration depth and the photo...
Last. Diego Ghezzi(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 21
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Objective Retinal stimulation in blind patients evokes the sensation of discrete points of light called phosphenes, which allows them to perform visually guided tasks, such as orientation, navigation, object recognition, object manipulation and reading. However, the clinical benefit of artificial vision in profoundly blind patients is still tenuous, as several engineering and biophysical obstacles keep it far away from natural perception. The relative preservation of the inner retinal neurons in...
Objective. Retinal stimulation in blind patients evokes the sensation of discrete points of light called phosphenes, which allows them performing visual guided tasks, such as orientation, navigation, object recognition, object manipulation and reading. However, the clinical benefit of artificial vision in profoundly blind patients is still tenuous, as several engineering and biophysical obstacles keep it away from natural perception. The relative preservation of the inner retinal neurons in here...
OBJECTIVE Retinal prostheses hold the potential for artificial vision in blind patients suffering from outer retinal dystrophies. The optimal number, density and coverage of the electrodes that a retinal prosthesis should have to provide adequate artificial vision in daily activities is still an open question and an important design parameter needed to develop better implants. APPROACH To address this question, we investigated the interaction between the visual angle, the pixel number and the pi...
#2Tianruo Guo(UNSW: University of New South Wales)H-Index: 10
Last. Liming Li(SJTU: Shanghai Jiao Tong University)H-Index: 11
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OBJECTIVE Implantable retinal prostheses aim to provide artificial vision to those suffering from retinal degenerative diseases by electrically stimulating the remaining retinal neurons using a multi-electrode array. The spatial resolution of these devices can be improved by creation of so-called virtual channels (VCs) that are commonly achieved through synchronized stimulation of multiple electrodes. It is largely unclear though if VCs can be created using asynchronous stimulation, which was th...
Visual prostheses are designed to restore partial functional vision in patients withtotal vision loss. Retinal visual prostheses provide limited capabilities as a result of low resolution, limited field of view and poor dynamic range. Understanding the influence of these parameters in the perception results can guide prostheses researchand design. In this work, we evaluate the influence of field of view with respect to spatial resolution in visual prostheses, measuring the accuracy and response ...