An update on retinal prostheses

Retinal prostheses are designed to restore a basic sense of sight to people with profound vision loss. They require a relatively intact posterior visual pathway (optic nerve, lateral geniculate nucleus and visual cortex). Retinal implants are options for people with severe stages of retinal degenerative disease such as retinitis pigmentosa and age-related macular degeneration. There have now been three regulatory-approved retinal prostheses. Over five hundred patients have been implanted globally over the past 15 years. Devices generally provide an improved ability to localize high-contrast objects, navigate, and perform basic orientation tasks. Adverse events have included conjunctival erosion, retinal detachment, loss of light perception, and the need for revision surgery, but are rare. There are also specific device risks, including overstimulation (which could cause damage to the retina) or delamination of implanted components, but these are very unlikely. Current challenges include how to improve visual acuity, enlarge the field-of-view, and reduce a complex visual scene to its most salient components through image processing. This review encompasses the work of over 40 individual research groups who have built devices, developed stimulation strategies, or investigated the basic physiology underpinning retinal prostheses. Current technologies are summarized, along with future challenges that face the field

Worldwide Argus II implantation: recommendations to optimize patient outcomes

Abstract Background A position paper based on the collective experiences of Argus II Retinal Prosthesis System investigators to review strategies to optimize outcomes in patients with retinitis pigmentosa undergoing retinal prosthesis implantation. Methods Retinal surgeons, device programmers, and rehabilitation specialists from Europe, Canada, Middle East, and the United States were convened to the first international Argus II Investigator Meeting held in Ann Arbor, MI in March 2015. The recommendations from the collective experiences were collected. Factors associated with successful outcomes were determined. Results Factors leading to successful outcomes begin with appropriate patient selection, expectation counseling, and preoperative retinal assessment. Challenges to surgical implantation include presence of staphyloma and inadequate Tenon’s capsule or conjunctiva. Modified surgical technique may reduce risks of complications such as hypotony and conjunctival erosion. Rehabilitation efforts and correlation with validated outcome measures following implantation are critical. Conclusions Bringing together Argus II investigators allowed the identification of strategies to optimize patient outcomes. Establishing an on-line collaborative network will foster coordinated research efforts to advance outcome assessment and rehabilitation strategies.http://deepblue.lib.umich.edu/bitstream/2027.42/134581/1/12886_2016_Article_225.pd

Human Embryonic Stem Cell-Derived Retinal Pigment Epithelium Transplantation in Advanced Neovascular Age-Related Macular Degeneration

Age-related macular degeneration (AMD) remains one of the leading causes of permanent vision impairment worldwide. It is a disorder of the central retina that manifests with irreversible cell loss, primarily affecting the retinal pigment epithelium (RPE) and subsequently the retina and choroid, leading to blindness through atrophy or neovascularization and exudation. Current treatments are only able to suppress the progression of the early and moderate neovascular AMD, mainly by controlling leakage and haemorrhage, while there is no established therapy for the atrophic type or the advanced neovascular type. RPE transplantation strategies have been attempted with promising outcomes; however, their operational complexity combined with the large patients’ volume has underlined the need for more accessible cell sources and a more feasible surgical paradigm. This thesis aims to examine the feasibility, safety and efficacy of transplantation of a human Embryonic Stem Cell (hESC)-derived RPE sheet in patients with severe neovascular (n) AMD. A fully differentiated hESC-RPE monolayer on a coated synthetic basement membrane (BM) has been bioengineered ex vivo and, using a purpose-designed surgical tool, has been implanted in the subretinal space of two patients with nAMD and acute vision decline. Systemic immunosuppression was administered during the peri- operative periods, while only local, intra-ocular steroids were given for the longer term. The patients were followed-up in a prospective study to assess the safety, and the structural and functional outcomes of this strategy for two years post-operatively. Both subjects demonstrated good safety outcome with no signs of local or distal tumorigenicity or uncontrolled proliferation from the implanted cells. Both showed reconstruction of the RPE-BM complex sufficient to support the retinal structure and the rescue and preservation of the photoreceptors, during the study period. Furthermore, both patients showed significant gain in their visual function, in terms of fixation, retinal light sensitivity, visual acuity and reading speed, maintained for two years. Most importantly, in both cases there was a clear co-localisation of the structural support, provided by the transplant, with the areas of functional improvement. The work in this thesis provides proof that the reconstruction of the RPE using hESC on synthetic BM can rescue and preserve the retinal structure and function over the long term, in severe neovascular AMD

Microsaccades in applied environments: Real-world applications of fixational eye movement measurements

Across a wide variety of research environments, the recording of microsaccades and other fixational eye movements has provided insight and solutions into practical problems. Here we review the literature on fixational eye movements—especially microsaccades—in applied and ecologically-valid scenarios. Recent technical advances allow noninvasive fixational eye movement recordings in real-world contexts, while observers perform a variety of tasks. Thus, fixational eye movement measures have been obtained in a host of real-world scenarios, such as in connection with driver fatigue, vestibular sensory deprivation in astronauts, and elite athletic training, among others. Here we present the state of the art in the practical applications of fixational eye movement research, examine its potential future uses, and discuss the benefits of including microsaccade measures in existing eye movement detection technologies. Current evidence supports the inclusion of fixational eye movement measures in real-world contexts, as part of the development of new or improved oculomotor assessment tools. The real-world applications of fixational eye movement measurements will only grow larger and wider as affordable high-speed and high-spatial resolution eye trackers become increasingly prevalent

Simulating and optimizing electrical current flow and neuronal activation in retinal implants

© 2018 Dr Timothy Bede Esler[Abstract Withheld

2019 IMSAloquium: Student Inquiry and Research Program and IMSA Internship Program

Welcome to IMSAloquium 2019! This is IMSA’s 32nd year of leading in educational innovation, the 31st year of the IMSA Student Inquiry and Research (SIR) Program, and the first year of the newly imagined IMSA Internship Program.https://digitalcommons.imsa.edu/archives_sir/1029/thumbnail.jp

Large scale retinal modeling for the design of new generation retinal prostheses

With the help of modern technology, blindness caused by retinal diseases such as age-related macular degeneration or retinitis pigmentosa is now considered reversible. Scientists from various fields such as Neuroscience, Electrical Engineering, Computer Science, and Bioscience have been collaborating to design and develop retinal prostheses, with the aim of replacing malfunctioning parts of the retina and restoring vision in the blind. Human trials conducted to test retinal prostheses have yielded encouraging results, showing the potential of this approach in vision recovery. However, a retinal prosthesis has several limitations with regard to its hardware and biological functions, and several attempts have been made to overcome these limitations. This thesis focuses on the biological aspects of retinal prostheses: the biological processes occurring inside the retina and the limitations of retinal prostheses corresponding to those processes have been analysed. Based on these analyses, three major findings regarding information processing inside the retina have been presented and these findings have been used to conceptualise retinal prostheses that have the characteristics of asymmetrical and separate pathway stimulations. In the future, when nanotechnology gains more popularity and is completely integrated inside the prosthesis, this concept can be utilized to restore useful visual information such as colour, depth, and contrast to achieve high-quality vision in the blind

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 183

This bibliography lists 273 reports, articles, and other documents introduced into the NASA scientific and technical information system in July 1978

Large scale retinal modeling for the design of new generation retinal prostheses

With the help of modern technology, blindness caused by retinal diseases such as age-related macular degeneration or retinitis pigmentosa is now considered reversible. Scientists from various fields such as Neuroscience, Electrical Engineering, Computer Science, and Bioscience have been collaborating to design and develop retinal prostheses, with the aim of replacing malfunctioning parts of the retina and restoring vision in the blind. Human trials conducted to test retinal prostheses have yielded encouraging results, showing the potential of this approach in vision recovery. However, a retinal prosthesis has several limitations with regard to its hardware and biological functions, and several attempts have been made to overcome these limitations. This thesis focuses on the biological aspects of retinal prostheses: the biological processes occurring inside the retina and the limitations of retinal prostheses corresponding to those processes have been analysed. Based on these analyses, three major findings regarding information processing inside the retina have been presented and these findings have been used to conceptualise retinal prostheses that have the characteristics of asymmetrical and separate pathway stimulations. In the future, when nanotechnology gains more popularity and is completely integrated inside the prosthesis, this concept can be utilized to restore useful visual information such as colour, depth, and contrast to achieve high-quality vision in the blind