An Optoelectronic Retinal Prosthesis
Author: Alexander Forrest Albert Butterwick
Publisher:
Published: 2008
Total Pages: 320
ISBN-13:
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Author: Alexander Forrest Albert Butterwick
Publisher:
Published: 2008
Total Pages: 320
ISBN-13:
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Publisher:
Published: 2009
Total Pages:
ISBN-13:
DOWNLOAD EBOOKAuthor: Mark S. Humayun
Publisher: Springer
Published: 2018-01-17
Total Pages: 137
ISBN-13: 3319672606
DOWNLOAD EBOOKIntended as a useful and practical guide primarily oriented toward ophthalmic practitioners involved in retinal prosthesis implantation and post-operative visual rehabilitation, this book focuses on the Argus II Retinal Prosthesis and its revolutionary incorporation into the practice. The reader will get an update on patient selection, expected visual outcomes, surgical implantation techniques, and post-operative visual rehabilitation. Retinal Prosthesis - A Clinical Guide to Successful Implementation is written in a clear and concise manner and includes diagrams and high quality photographs to demonstrate best practices in surgical techniques and desired outcomes. Covering topics such as history of retinal prostheses, bioengineering considerations, clinical therapies, and other therapies and future directions, this book is written for practicing ophthalmologists, residents, and medical students interested in retinal implants.
Author: Samir Sudhir Damle
Publisher:
Published: 2020
Total Pages: 108
ISBN-13:
DOWNLOAD EBOOKDegenerative retinal diseases such as Age-Related Macular Degeneration (AMD) are among the leading causes of irreversible blindness today for which there are no effective treatments to recover lost vision. Retinal prostheses have been developed to replace the lost photo-sensing with implanted optoelectronic pixels that transduce light into electrical current to stimulate patterns of retinal activity. A fundamental goal of retinal prosthesis design is the realization of a densely packed stimulating array that can restore high visual acuity. However, the efficacy of optoelectronic subretinal stimulation for high visual acuity retinal prosthesis is not as well understood, particularly because passive photodiodes used in clinical implants today lack sufficient photoresponsivity ( 1 A/W) to produce sufficient photocurrent to stimulate retinal neurons at size scales suitable for high density retinal interfaces. Here, we evaluated an optoelectronic approach to retinal prosthesis that offers a unique solution to the problem of minimizing the photosensor, current source, and stimulating electrode size for high density retinal interfaces. First, we characterized the feasibility of retinal stimulation with a fully implantable nanowire based subretinal prosthesis on the basis of electrically evoked potentials measured in the visual cortex of an in vivo rabbit model. We then established criteria for stimulation at a single pixel level using an ex vivo model of photoreceptor cell degeneration. We determined stimulation thresholds and dynamic range of current required to evoke spiking responses in retinal ganglion cells within the charge injection limits of 10-30[mu]m iridium oxide electrodes. We showed that the minimum size for effective stimulation approaches 20[mu]m diameter. Next, to meet these established current requirements we developed a novel optoelectronic pixel architecture consisting of a vertically integrated photo junction-field-effect transistor (Photo-JFET) and neural stimulating electrode. We demonstrated that optically addressed Photo-JFET pixels can utilize phototransistive gain (100 A/W) to produce a broad range of neural stimulation current. At 13[mu]m pixel size, a single Photo-JFET pixel can effectively stimulate retinal neurons ex vivo. The compact nature of the Photo-JFET pixel can enable high resolution retinal prostheses with the smallest reported optoelectronic pixel size to help restore high visual acuity in patients with degenerative retinal disease.
Author: Mark S. Humayun
Publisher: Springer Science & Business Media
Published: 2007-09-30
Total Pages: 407
ISBN-13: 038749331X
DOWNLOAD EBOOKThis book describes advances in implantable neural stimulation technology to restore partial sight to people who are blind from retinal degnerative diseases such as age-related macular degeneration and retintis pigmentosa. Many scientific, engineering, and surgical challenges must be surmounted before widespread practical applications can be realized. The book summarizes the state of research and clinical practice in the field and reviews the current ideas and approaches of its leading researchers and practitioners.
Author: Jeffrey N. Weiss
Publisher: Springer Nature
Published: 2022-08-22
Total Pages: 125
ISBN-13: 3031066200
DOWNLOAD EBOOKFor the millions of people with untreatable blindness the thought of a visual prosthesis that would allow them to live a normal life has always been a distant hope. There have been intermittent bright spots that periodically fan that hope such as when Dr. Dobelle’s visual prosthesis patient drove a car in an empty parking lot. This book will serve as an update of the work in developing a visual prosthesis. Chapters discuss the physiologic and engineering issues, alternative strategies, and patents, as well as recent research studies. Visual Prosthesis - A Concise Guide is a must-have resource for ophthalmologists, neurologists, engineers and physicists.
Author: Joyce Tombran-Tink
Publisher: Springer Science & Business Media
Published: 2007-12-08
Total Pages: 277
ISBN-13: 1597454494
DOWNLOAD EBOOKThis volume details the latest technology in treating eye injuries and infections. It provides insight into the most up-to-date and established treatment options. The volume focuses on what can currently be achieved with a variety of ocular prostheses as well as what the future holds. Coverage reviews issues such as intraocular lens implants, biocompatibility of materials, retinal implants, testing models, and software designs.
Author: Marta Jole Ildelfonsa Airaghi Leccardi
Publisher:
Published: 2020
Total Pages: 147
ISBN-13:
DOWNLOAD EBOOKMots-clés de l'auteur: POLYRETINA ; artificial vision ; retinal prosthesis ; photovoltaic stimulation ; curved injectable implant ; organic optoelectronic materials ; OSTEmer ; retinal ganglion cells ; miniature pigs.
Author: Veit Peter Gabel
Publisher: Springer
Published: 2016-11-24
Total Pages: 233
ISBN-13: 3319418769
DOWNLOAD EBOOKThis book presents and analyses the most recent research dedicated to restoring vision in individuals who are severely impaired or blind from retinal disease or injury. It is written by the leading groups worldwide who are at the forefront of developing artificial vision. The book begins by discussing the difficulties in comparing and interpreting functional results in the area of very low vision and the principal prospects and limitations of spatial resolution with artificial tools. Further on, chapters are included by researchers who stimulate the surface or the pigment epithelial side of the retina and by experts who work on stimulating the optic nerve, the lateral geniculate body and the superficial layers of the visual cortex. Artificial Vision: A Clinical Guide collates the most recent work of key artificial vision research groups to explain in a comparable and stringent order their varying approaches, the clinical or preclinical outcomes and their achievements during the last years. Senior ophthalmic fellows and academic practitioners will find this guide to be an indispensable resource for understanding the current status of artificial vision.
Author: Yi Jing
Publisher:
Published: 2013
Total Pages: 143
ISBN-13: 9781303619779
DOWNLOAD EBOOKThis dissertation presents works on two significant application areas of semiconductor nanowire. The first is nanowire photodetectors and their applications for image sensing and retinal prosthesis. The second is nanowire solar cells for renewable energy application and both Si and III-V nanowire devices are extensively discussed. Three structures of Si nanowire photodetectors are presented, including nanowire photoconductor, axial and radial junction nanowire photodiodes. Using the design of a crossbar structure, an individually addressable vertical Si nanowire photoconductor array was presented, followed by discussion on integration to CMOS for image sensing applications. In addition, the Si axial junction nanowire photodiodes were also demonstrated, which showed excellent detectivities in visible spectrum at zero bias, with a peak value of 2.14×1013 Jones at wavelength of 636 nm. Furthermore, the radial junction nanowire photodiodes were discussed as well, which exhibited enhanced photo responsivity due to shorter carrier separation and collection paths. These nanowire photodiode arrays promises potential application for retinal prosthesis by replacing the dysfunctional photo receptors in human retina In addition to photodetectors, I also demonstrated Si nanowire solar cells including both planar Si solar cells with nanowire absorber and Si radial junction nanowire solar cells. A low-cost chemical etching method was introduced to fabricate large-scale Si nanowire array as light absorber to improve the light absorption of planar Si solar cells. The efficiency of this device is over one order of magnitude higher than the one without nanowires. In addition, the Si radial junction nanowire solar cells were studied. A systematic study on design parameters, including nanowire core and shell doping concentrations, band structures and surface passivation methods, were discussed to achieve optimal device performance. With optimal design, a power conversion efficiency of 8%was demonstrated InAs based nanowire core/multi-shell heterojunction solar cells were investigated as well. A systematic study of catalyst-free MOCVD growth of InAs nanowires on Si substrates was performed. Various growth parameters and surface treatment methods were studies to achieve optimal nanowire growth and reveal the growth mechanism. Based on the InAs nanowire growth, the III-V core/multi-shell nanowires were successfully fabricated and solar cells have been demonstrated.