- •Visual Prosthetics
- •Preface
- •Acknowledgments
- •Contents
- •Contributors
- •1.1 The Visual System as an Engineering Compromise
- •1.2 An Overview of Human Visual System Architecture
- •1.2.1 Architecture and Basic Function of the Eye
- •1.2.2 Layout of the Retino-Cortical Pathway
- •1.2.3 Layout of the Subcortical Pathways
- •1.3 An Overview of Human Visual Function
- •1.3.1 Roles of Central (Foveal) Vision
- •1.3.2 Roles of Peripheral Vision
- •1.3.3 Roles of Dark-Adapted Vision
- •1.3.4 A Few Remarks Regarding Visual Development
- •1.4 Prospects for Prosthetic Vision Restoration
- •References
- •2.1 Introduction
- •2.2 Retina
- •2.2.1 Anatomy
- •2.2.2 Physiology and Receptive Fields
- •2.4.1 Anatomy
- •2.4.2 Physiology and Receptive Fields
- •2.6 The Role of Spatiotemporal Edges in Early Vision
- •2.7 The Role of Corners in Early Vision
- •2.7.1 Overview
- •2.8 Effects of Fixational Eye Movements in Early Visual Physiology and Perception
- •2.8.1 Overview
- •2.8.2 Neural Adaptation and Visual Fading
- •2.8.3 Microsaccades in Visual Physiology and Perception
- •References
- •3.1 Introduction
- •3.2 Background
- •3.3 Retinal Disease and Its Diversity
- •3.4 Retinal Remodeling
- •3.5 Retinal Circuitry
- •3.6 Retinal Circuitry Revision
- •3.7 Implications for Bionic Rescue
- •3.8 Implications for Biological Rescue
- •3.9 Final Remarks
- •References
- •4.1 Introduction
- •4.4 What Are the Limits to This Cortical Plasticity?
- •4.5 Possible Mechanisms Behind Brain Plasticity
- •4.6 Modulation of Brain Plasticity: Recent Developments
- •4.7 Neuroplasticity and Other Neuroprostheses Efforts
- •4.8 A Look at What Is Ahead
- •References
- •5.1 Introduction
- •5.2 Vision Changes Experienced by RP Patients
- •5.2.1 Overview
- •5.2.2 Visual Field Loss in RP
- •5.2.3 Changes in Color Vision and Glare Sensitivity in RP
- •5.2.4 Vision Fluctuations in RP
- •5.3 Visual Changes in Patients with Advanced Macular Degeneration
- •5.3.1 Changes Due to Wet AMD or Choroidal Neovascularization
- •5.3.2 Changes Due to Dry AMD or Geographic Atrophy
- •5.4 Charles Bonnet Syndrome
- •5.4.1 Overview
- •5.4.2 Complexity of Visual Hallucinations in CBS
- •5.4.3 Predictors and Alleviating Factors for CBS
- •5.5 Filling-In Phenomena (Perceptual Completion)
- •5.6 Remapping of Primary Visual Cortex in Patients with Central Scotomas from Macular Disease
- •5.7 The Preferred Retinal Locus for Fixation
- •5.8 Photopsias
- •5.8.1 Photopsias in RP
- •5.8.2 Photopsias in AMD and Other Ocular Diseases
- •5.9 Concluding Remarks
- •References
- •6.1 Introduction
- •6.2 Electrode–Electrolyte Interface
- •6.3 Electrode Material
- •6.3.1 Electrode Characterization
- •6.4 Overview of Electrode Materials for Neural Stimulation
- •6.5 Overview of Extracellular Stimulation
- •6.6 Safe Stimulation of Tissue
- •6.6.1 Mechanisms of Neural Injury
- •6.6.2 Parameters for Safe Stimulation
- •6.6.3 Stimulation Induced Injury in the Retina
- •References
- •7.1 Introduction
- •7.2 Power and Data Transmission
- •7.2.1 Wireline Connection
- •7.2.2 Inductive Coils
- •7.2.3 Serial Optical Telemetry
- •7.2.4 Photodiode Array-Based Prostheses
- •7.2.5 Thermal Safety Considerations
- •7.2.6 Conclusions: Comparing the Different Approaches
- •7.3 Tissue Response to a Subretinal Implant
- •7.3.1 Flat Implants
- •7.3.2 Chamber Implants
- •7.3.3 Pillar Arrays
- •7.4 Damage to Retinal Tissue from Electrical Stimulation
- •7.4.1 Effect of Pulse Duration
- •7.4.2 Electrode Size
- •7.5 Concluding Remarks
- •References
- •8.1 Introduction
- •8.2 Quasistatic Numerical Methods: The Admittance Method
- •8.2.1 Layered Retinal Model
- •8.2.2 Equivalent Electric Circuit
- •8.3 Three-Dimensional Activation Function Calculation
- •8.4 Safety of Implant
- •8.5 Conclusion
- •References
- •9.1 Pathophysiology of Retinal Degeneration
- •9.2.1 Outer Plexiform Layer
- •9.2.2 Inner Plexiform Layer
- •9.2.2.1 Bipolar Cell Excitation of Retinal Ganglion Cells
- •9.2.2.2 Amacrine Cell Modulation of Signal Processing
- •9.2.2.3 Inhibitory Transmitters
- •9.2.2.4 Acetylcholine and Dopamine
- •9.2.2.5 Neuropeptides
- •9.2.2.6 Putative neurotransmitters for retinal prosthesis
- •9.3 Neurophysiological Changes in Retinal Degeneration
- •9.4 Rationale for a Neurotransmitter-Based Retinal Prosthesis
- •9.4.1 Limitations of Electrical Stimulation
- •9.5 Technical Considerations and Design Approaches
- •9.5.1 Operating Principles for a Neurotransmitter-Based Retinal Prosthesis
- •9.5.2 Establishing a Retinal Prosthesis/Synaptic Interface
- •9.5.2.1 The Proximity Requirement
- •9.5.2.2 Convective Delivery of Neurotransmitters Via Microfluidics
- •9.5.2.3 Functionalized Surfaces for Neurotransmitter Stimulation
- •9.5.2.4 Synaptic Requirements for l-Glutamate Mediated Neuronal Stimulation
- •9.6 Summary
- •References
- •10.1 Introduction
- •10.2 Pioneering Experiments
- •10.2.1 Stimulation with No Chromophores
- •10.2.2 Azo Chromophores
- •10.3 Current Research
- •10.3.1 Caged Neurotransmitters
- •10.3.2 Pore Blocker and Photoisomerization
- •10.3.3 The Channelrhodopsins
- •10.3.4 Melanopsin
- •10.4 Synthetic Chromophores and Artificial Sight
- •References
- •11.1 Background
- •11.2 Physical Structure of Intracortical Electrodes
- •11.3 Charge Injection Using Intracortical Electrodes
- •11.3.1 The Intracortical Electrode as a Transducer
- •11.3.2 Charge Injection Limits
- •11.4 Intracortical Electrode Coatings
- •11.5 Characterization of Intracortical Electrodes
- •11.5.1 Cyclic Voltammetry
- •11.5.2 Electrode Stimulation Voltage Waveforms
- •11.5.3 Non-ideal Access Resistance Behavior
- •11.5.4 Non-linear Electrode Polarization
- •11.5.5 Determining Electrode Safety
- •11.6 Contrasts of In Vitro and In Vivo Behavior
- •11.7 Alternative Coatings for Improving Intracortical Electrodes
- •11.7.1 SIROF
- •11.7.2 PEDOT
- •11.7.3 Carbon Nanotube Coatings
- •11.8 Conclusion
- •References
- •12.1 Introduction
- •12.2 Responses of RGCs to Electrical Stimulation in Normal Retina
- •12.2.1 Epiretinal Stimulation
- •12.2.1.1 Target of Stimulation
- •12.2.1.2 The Site of Spike Initiation in RGCs
- •12.2.1.3 Threshold vs. Stimulating Electrode Diameter
- •12.2.1.4 Spatial Extent of Activation
- •12.2.1.5 Selective Activation
- •12.2.1.6 Temporal Response Properties
- •12.2.2 Subretinal Stimulation
- •12.2.2.1 Target of Stimulation
- •12.2.2.2 Threshold vs. Polarity of Stimulation Pulse
- •12.2.2.3 Spatial Extent of Activation
- •12.2.2.4 Temporal Response Properties
- •12.2.2.5 Dynamics of the Retinal Response
- •12.4 Responses of RGCs to Electrical Stimulation in Degenerate Retina
- •12.4.1 Epiretinal Stimulation
- •12.4.2 Subretinal Stimulation
- •12.4.2.1 Response Properties of RGCs
- •12.4.2.2 Activation Thresholds of RGCs
- •12.5 Cortical Responses to Retinal Stimulation
- •12.5.1 Spatial Properties Revealed by Cortical Measurements
- •12.5.2 Local Field Potentials
- •12.5.3 Elicited Responses Are Focal
- •12.5.4 Cortical Measurements Reveal Electrode Interactions
- •12.5.5 Temporal Responsiveness in Cortex
- •12.6 Suggestions for Future Studies
- •References
- •13.1 Introduction
- •13.2 General Considerations for Acute Retinal Stimulation Experiments
- •13.3 Surgical Technique
- •13.4 Threshold Measurements
- •13.5 Spatial Resolution and Pattern Perception
- •13.6 Temporal Resolution
- •13.7 Subretinal Versus Epiretinal Stimulation
- •13.8 Less Invasive Stimulation Procedures
- •13.9 Conclusions and Outlook
- •References
- •14.1 Introduction
- •14.2 Overview of Chronic Retinal Implant Technologies
- •14.2.1 The Retinal Implant AG Microphotodiode Prosthesis
- •14.2.2 The Intelligent Retinal Implant System
- •14.2.3 Second Sight Medical Products, Inc. A16 System
- •14.3 Thresholds on Individual Electrodes
- •14.3.1 Single Pulse Thresholds Using the SSMP System
- •14.3.2 Pulse Train Integration and Temporal Sensitivity
- •14.4 Suprathreshold Brightness
- •14.4.1 Brightness Using the Retinal Implant AG System
- •14.4.2 Brightness Using the Intelligent Medical Implant System
- •14.4.3 Brightness Using the SSMP A16 System
- •14.5 Spatial Vision
- •14.5.1 Spatial Vision with the Retinal Implant AG System
- •14.5.2 Spatial Vision with the Intelligent Medical Implant System
- •14.5.3 Spatial Vision with the SSMP A16 System
- •14.6 Models to Guide Electrical Stimulation Protocols
- •14.7 Conclusions
- •References
- •15.1 Background
- •15.2 Cortical Surface Stimulation
- •15.3 Intracortical Microstimulation
- •15.4 Optic Nerve Stimulation
- •15.5 What Is Known and What Needs to Be Done
- •15.6 Current Research Efforts
- •15.6.1 Optic Nerve Stimulation
- •15.6.2 Cortical Surface Stimulation
- •15.6.3 Intracortical Stimulation of Visual Cortex
- •15.6.4 CORTIVIS Program
- •15.6.5 Lateral Geniculate Stimulation
- •15.7 Microelectrode Arrays and Stimulation Hardware
- •15.7.1 Miniature Cameras
- •15.7.2 Animal Models
- •15.7.3 Image Processing and Phosphene Mapping
- •15.8 Conclusion
- •References
- •16.1 Introduction
- •16.2 Simulation Techniques and Basic Parameters
- •16.2.1 Gaze Tracking and Image Stabilization
- •16.2.2 Filter Engine Parameters
- •16.2.2.1 Raster Spatial Properties
- •16.2.2.2 Dot Spatial Properties
- •16.2.2.3 Temporal Properties
- •16.2.2.4 Dynamic Background Noise
- •16.2.2.5 Input Filtering/Windowing, Image Enhancement
- •16.3 Optotype Resolution and Reading
- •16.3.1 Visual Acuity
- •16.3.2 Reading
- •16.4 Face and Object Recognition
- •16.5 Visually Guided Behavior
- •16.5.1 Hand–Eye Coordination
- •16.5.2 Wayfinding
- •16.6 Visual Tracking
- •16.7 Computational Simulations
- •16.8 Conclusion
- •References
- •17.1 Introduction
- •17.2 Situating Image Analysis
- •17.3 The Experimental Framework
- •17.4 Tracking a Low-Resolution Target
- •17.5 Discussion
- •17.6 Conclusion
- •References
- •18.1 Introduction
- •18.2 Representation of Visual Space on the Visual Cortex
- •18.3 Cortical Stimulation Studies
- •18.4 Variability in Occipital Cortex
- •18.5 Phosphene Map Estimation
- •18.6 Psychophysical Studies with the Estimated Maps
- •References
- •19.1 Importance of Mapping
- •19.3 The Computer Era: Refining the Pointing Method of Phosphene Mapping
- •19.4 Verbal Mapping
- •19.5 Mapping Studies Using Subject Drawings
- •19.6 Recent Simulation Studies Using Phosphene Mapping
- •19.6.1 Tactile Simulations at Shanghai Jiao Tong University
- •19.6.2 Simulations in Our Laboratory
- •19.7 Concluding Remarks on Phosphene Mapping Techniques
- •References
- •20.1 Introduction
- •20.2 Principles for Assessment of Prosthetic Vision
- •20.2.1 Experimental Design
- •20.2.2 The Importance of Pre-operative Testing
- •20.2.3 Post-operative Assessment
- •20.2.4.1 Potential Approaches
- •20.2.4.2 Avoidance of Bias
- •20.2.4.3 Criteria for Sound Testing
- •20.2.4.4 Forced Choice Procedures
- •20.2.4.5 Response Time
- •20.2.4.6 Task (Perceptual) Learning
- •20.2.4.7 Establishing Criteria for Meaningful Change
- •20.2.4.8 Light Level
- •20.3 Vision Assessment in Prosthesis Recipients: Overview
- •20.3.1 Visual Function Assessment: Overview
- •20.3.2 Visual Performance Assessment: Overview
- •20.3.2.1 Measured Visual Performance
- •20.3.2.2 Self-Reported Visual Performance
- •20.4 Visual Function Assessment
- •20.4.1 Candidate Measures
- •20.4.1.1 Contrast Sensitivity (Contrast Detection)
- •20.4.1.2 Contrast Discrimination
- •20.4.1.3 Motion Perception
- •20.4.1.4 Depth Perception
- •20.4.2 Tests Used in Prosthesis Trials
- •20.4.3 Tests that Have Been Designed for Use with Prostheses
- •20.4.4 Vision Tests for Very Low Vision
- •20.5 Visual Performance Assessment
- •20.5.1 Measured Performance
- •20.5.2 Self-Reported Performance (Questionnaires)
- •20.6 Summary
- •References
- •21.1 Concepts of Functional Vision and Rehabilitation
- •21.1.1 Application to Orientation and Mobility
- •21.1.2 Application for Activities of Daily Living
- •21.1.3 Patient Lifestyle and Expectations
- •21.1.4 Congenital and Adventitious Vision Loss
- •21.2 Evaluation and Intervention with Prosthetic Vision
- •21.2.1 Evaluation
- •21.2.2 Intervention
- •21.3 Measuring Functional Outcomes
- •21.4 The Future
- •References
- •Author Index
- •Subject Index
Contributors
Michael P. Barry
Lions Vision Research & Rehabilitation Center,
Johns Hopkins University School of Medicine, Baltimore, MD 21205-2020, USA mbarry11@jhu.edu
Ava K. Bittner
Lions Vision Research & Rehabilitation Center, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA abittne1@jhmi.edu
Alex Butterwick
Department of Applied Physics, Stanford University, Stanford, CA, USA abutterwick@gmail.com
Carlos J. Cela
Department of Electrical and Computer Engineering, University of Utah,
50 S. Central Campus Drive, Room 3280, Salt Lake City, UT 84112-9206, USA carlos.cela@utah.edu
Gislin Dagnelie
Lions Vision Research & Rehabilitation Center,
Johns Hopkins University School of Medicine, Baltimore, MD, 21205-2020 USA gdagnelie@jhmi.edu
James Deremeik
Johns Hopkins University, Baltimore, MD, USA jderemeik@jhmi.edu
Barbara R. Evans
Oak Ridge National Laboratory, Oak Ridge, TN, USA evansb@ornl.gov
Eduardo Fernández
Instituto de Bioingeniería, Universidad Miguel Hernández, Avda de la Universidad s/n, 03202 Elche (Alicante), Spain e.fernandez@umh.es
xvi |
Contributors |
Ione Fine
University of Washington, Seattle, WA, USA ionefine@u.washington.edu
Paul G. Finlayson
Departments of Otolaryngology and Ophthalmology, Wayne State University, 550 E. Canfield pfinlays@med.wayne.edu
Shelley I. Fried
VA Boston Healthcare System, 150 South Huntington Avenue, Boston, MA 02130, USA
and
Massachusetts General Hospital & Harvard Medical School, 429 Their, 50 Blossom Street, Boston, MA 02114, USA fried.shelley@mgh.harvard.edu
Duane R. Geruschat
Lions Vision Research & Rehabilitation Center, Wilmer Eye Institute, Johns Hopkins University School of Medicine, 550 N, Baltimore, MD 21205, USA dgeruschat@jhmi.edu
Elias Greenbaum
Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA greenbaum@ornl.gov
Luke E. Hallum
Graduate School of Biomedical Engineering, University of New South Wales, ANZAC Parade, Sydney 2052, Australia
and
Center for Neural Science, New York University, New York, NY 10003, USA hallum@cns.nyu.edu
Alan Horsager
Eos Neuroscience, Inc., 2100 3rd Street, 3rd floor, Los Angeles, CA 90057, USA
and
Department of Ophthalmology, University of Southern California, Los Angeles, CA 90089, USA
horsager@usc.edu
Philip Huie
Department of Ophthalmology, Stanford University, 450 Serra Mall, Stanford, CA, 94305, USA
philhuie@stanford.edu
Raymond Iezzi
Department of Ophthalmology, Mayo Clinic, 200 First Street, SW, Rochester, MN 55905, USA
iezzi.raymond@mayo.edu
Contributors |
xvii |
Ralph J. Jensen
VA Boston Healthcare System, Boston, MA, USA
Ralph.Jensen@va.gov
Bryan W. Jones
Moran Eye Center, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT 84132, USA
bryan.jones@m.cc.utah.edu
Gianluca Lazzi
Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT, USA lazzi@utah.edu
James Loudin
Department of Applied Physics, Stanford University, 450 Serra Mall, Stanford, CA 94305, USA
loudin@stanford.edu
Nigel H. Lovell
University of New South Wales, Sydney, Australia
N.Lovell@unsw.edu.au
Stephen L. Macknik
Barrow Neurological Institute, Phoenix, AZ, USA macknik@neuralcorrelate.com
Susana Martinez-Conde
Barrow Neurological Institute, 350 W. Thomas Road, Phoenix, AZ 85013, USA smart@neuralcorrelate.com
Robert E. Marc
Moran Eye Center, University of Utah, Salt Lake City, UT, USA robert.marc@hsc.utah.edu
Lotfi B. Merabet
Harvard Medical School, Boston, MA, USA
Lotfi_Merabet@meei.harvard.edu
Daniel Palanker
Department of Applied Physics, Stanford University, Stanford, CA, USA palanker@stanford.edu
Aditi Ray
Department of Biomedical Engineering, 1042 Downey Way,
Denney Research Building (DRB) 140, Los Angeles, CA 90089, USA Aditi.Ray@AlconLabs.com
Gernot Roessler
Department of Ophthalmology, RWTH Aachen University, Aachen, Germany groessler@ukaachen.de
xviii |
Contributors |
Edward M. Schmidt
National Institutes of Health (retired) emschmidt@atlanticbb.net
Marilyn E. Schneck
Rehabilitation Engineering and Research Center, The Smith-Kettlewell Eye Research Institute, 2318 Fillmore Street, San Francisco, CA 94115, USA and
Vision Sciences Program School of Optometry-2020, University of California at Berkeley, Berkeley, CA 94720-2020, USA
mes@ski.org
Nishant R. Srivastava
Department of Biomedical Engineering, Pritzker Institute of Biomedical Science and Engineering, Illinois Institute of Technology, 3255 S. Dearborn, WH 314, Chicago, IL 60616, USA
srivnis@gmail.com
H. Christiaan Stronks
Lions Vision Research and Rehabilitation Center, Wilmer Eye Institute, Johns Hopkins University School of Medicine, 550 N. Broadway, 6th floor, Baltimore, MD 21205, USA
hstronk1@jhmi.edu
Janet S. Sunness
Greater Baltimore Medical Center, Baltimore, MD, USA jsunness@gbmc.org
Xoana G. Troncoso
California Institute of Technology, Pasadena, CA, USA x.troncoso@neuralcorrelate.com
Philip R. Troyk
Department of Biomedical Engineering,
Pritzker Institute of Biomedical Science and Engineering, Illinois Institute of Technology, 3255 S. Dearborn, WH 314, Chicago, IL 60616, USA troyk@iit.edu
Peter Walter
Department of Ophthalmology, RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany
pwalter@ukaachen.de
Carl B. Watt
Moran Eye Center, University of Utah, Salt Lake City, UT, USA carl.watt@hsc.utah.edu
James D. Weiland
Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
jweiland@doheny.org
Part I
Structure and Function
of the Visual System
Chapter 1
The Human Visual System:
An Engineering Perspective
Gislin Dagnelie
Abstract This chapter provides a brief introduction to the architecture and function of the healthy visual system. Particular emphasis is placed on the diverse capabilities of the visual system that visual prosthesis researchers may want to emulate, to provide the reader with a realistic sense of the daunting challenges facing workers in this field.
Abbreviations
CCD |
Charge-coupled device |
COS |
Cone outer segment |
HL |
Henle fiber layer |
INL |
Inner nuclear layer |
LGN |
Lateral geniculate nucleus |
NOT |
Nucleus of the optic tract |
ONL |
Outer nuclear layer |
RPE |
Retinal pigment epithelium |
SC |
Superior colliculus |
TN |
Terminal nucleus |
V1 |
Primary visual cortex, striate cortex |
V2 |
Secondary visual cortex, peristriate/extrastriate cortex |
G. Dagnelie (*)
Lions Vision Research & Rehabilitation Center, Johns Hopkins University School of Medicine, 550 N. Broadway, 6th floor, Baltimore, MD 21205-2020, USA
e-mail: gdagnelie@jhmi.edu
G. Dagnelie (ed.), Visual Prosthetics: Physiology, Bioengineering, Rehabilitation, |
3 |
DOI 10.1007/978-1-4419-0754-7_1, © Springer Science+Business Media, LLC 2011 |
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