Elsevier

Survey of Ophthalmology

Volume 47, Issue 4, July–August 2002, Pages 335-356
Survey of Ophthalmology

Major review
Retinal Prosthesis for the Blind

https://doi.org/10.1016/S0039-6257(02)00311-9Get rights and content

Abstract

Most of current concepts for a visual prosthesis are based on neuronal electrical stimulation at different locations along the visual pathways within the central nervous system. The different designs of visual prostheses are named according to their locations (i.e., cortical, optic nerve, subretinal, and epiretinal). Visual loss caused by outer retinal degeneration in diseases such as retinitis pigmentosa or age-related macular degeneration can be reversed by electrical stimulation of the retina or the optic nerve (retinal or optic nerve prostheses, respectively). On the other hand, visual loss caused by inner or whole thickness retinal diseases, eye loss, optic nerve diseases (tumors, ischemia, inflammatory processes etc.), or diseases of the central nervous system (not including diseases of the primary and secondary visual cortices) can be reversed by a cortical visual prosthesis. The intent of this article is to provide an overview of current and future concepts of retinal and optic nerve prostheses. This article will begin with general considerations that are related to all or most of visual prostheses and then concentrate on the retinal and optic nerve designs. The authors believe that the field has grown beyond the scope of a single article so cortical prostheses will be described only because of their direct effect on the concept and technical development of the other prostheses, and this will be done in a more general and historic perspective..

Section snippets

Psychophysical Experiments

There is a general consensus that electrical stimulation of the visual pathways via a small number of electrodes cannot be expected to provide unaided understanding of visual information. In an effort to define the minimum acceptable resolution for useful vision, several psychophysical experiments were performed. As early as 1965, it was suggested that 600 points of stimulation (pixels) would be sufficient for reading ordinary print.14 Others suggested that 80–120 points are sufficient for

Surface cortical electrodes

One of the earliest experiments included three blind patients, two of whom were able to locate a light source by scanning the visual field with a photocell. The photocell output electrically stimulated the cortex via electrodes in a wire passing through the scalp and skull and penetrating the visual cortex.25

Brindley and Lewin performed key experiments in this field by implanting devices consisting of 80 electrodes on the visual cortex of blind patients (Fig. 1). Wires through a burr hole

Retinal Prostheses

During the early seventies it became clear that blind humans can also perceive electrically elicited phosphenes in response to ocular stimulation, with a contact lens as a stimulating electrode.107, 108, 109 When obtainable, these electrically elicited responses indicated the presence of at least some functioning inner retinal cells. Because a number of blinding retinal diseases are due predominantly to outer retinal (in particular photoreceptor) degeneration,72, 127, 142 the idea of

Optic Nerve Prostheses

Investigators have also stimulated the optic nerve.133, 134, 153 The optic nerve is a compact compartment of ganglion cell axons running from the retina and synapse on the lateral geniculate body. This condensed cable can be reached surgically, and theoretically has a good location for implanting a surface or penetrating stimulation electrode array. However, the high density of the axons (1.2 million within a 2 mm-diameter cylindrical structure) could make it difficult to achieve focal

Sensory Substitution Devices

As an alternative to direct stimulation of the visual system neurons, several other approaches have attempted to convert visual information into vibro-tactile or auditory signals (i.e., sensory substitution devices12, 115). The distinct advantage of these approaches is that the device is wearable and not implantable. However, these devices have never reached widespread acceptance because they do not restore the sensation of vision, have low resolution, occupy another sensory modality, can evoke

Summary

The three levels of hierarchy in the sensory systems (i.e., receptor organ, sensory pathways, and perception) suggest a similar architecture for artificial and prosthetic sensory systems. Accordingly, artificial systems should include a transducer corresponding to the receptor organ, an encoder corresponding to the sensory processing system, and finally an interpreter corresponding to perceptual functions. In other words, the visual environment will be captured and processed by a photosensing

Method of Literature Search

A literature search of the PubMed data was performed (1966–present). The following key words were used: artificial vision, blindness, cortical prosthesis, electrical stimulation electronic implants, macular degeneration, optic nerve, optic nerve prosthesis, retina, retinal prosthesis, retinitis pigmentosa, visual cortex and visual prosthesis. In addtion, some abstracts from relevant recent conferences and annual meetings were reviewed. The search was not limited to English language, but only

Outline

I. General considerations

A. Efficacy of a visual prosthesis

1. Psychophysical experiments

2. Neuronal electrical excitation

a. Threshold parameters for electrical stimulation

3. Electrodes

4. Power supply

B. Safety of electrical stimulation

1. Damage caused by electrical current

2. Infection and inflammation

3. Heat damage

4. Hermetic sealing of the electronics

II. Cortical prosthesis

A. Surface cortical electrodes

B. Intracortical microstimulation

III. Retinal prostheses

A. Epiretinal prostheses

1. In vitro

Acknowledgements

The manuscript was supported in part by grants from the National Science Foundation #BES9810914, National Eye Institute #R209EY11888, Second Sight/NIH-NEI #R24EY12893-01, Foundation Fighting Blindness, Defense Advanced Research Projects Agency, Office of Naval Research: Tissue Based Biosensors Program, The Whitaker Foundation, and The Alfred E. Mann Fund at the Applied Physics Laboratory. The authors wish to thank Rhonda Grebe, Terry Shelley, Salvatore A. D'Anna, and Devon C. Ginther, for their

References (171)

  • E Guenther et al.

    Long-term survival of retinal cell cultures on retinal implant materials

    Vision Res

    (1999)
  • M.S Humayun et al.

    Pattern electrical stimulation of the human retina

    Vision Res

    (1999)
  • B Jansen et al.

    Evidence for degradation of synthetic polyurethanes by Staphylococcus epidermidis

    Zentralbl Bakteriol

    (1991)
  • H Karny

    Clinical and physiological aspects of the cortical visual prosthesis

    Surv Ophthalmol

    (1975)
  • E.M Maynard et al.

    The Utah intracortical electrode arraya recording structure for potential brain-computer interfaces

    Electroencephal Clin Neurophysiol

    (1997)
  • D.B McCreery et al.

    Neuronal activity evoked by chronically implanted intracortical microelectrodes

    Exp Neurol

    (1986)
  • J McHardy et al.

    Electrical stimulation with pt electrodes. IV. Factors influencing Pt dissolution in inorganic saline

    Biomaterials

    (1980)
  • G Meachim et al.

    The tissue response to acrylic particles implanted in animal muscle

    Biomaterials

    (1982)
  • H.R.F Motz

    A study of the application of the Hodgkin-Huxley and the Frankenhaeuser–Huxley model for electrostimulation of the acoustic nerve

    Neuroscience

    (1986)
  • G.M Acland et al.

    Gene therapy restores vision in a canine model of childhood blindness

    Nat Genet

    (2001)
  • D.J Anderson et al.

    Batch-fabricated thin-film electrodes for stimulation of the central auditory system

    IEEE Trans Biomed Eng

    (1989)
  • E App et al.

    Saccadic velocity and activationdevelopment of a diagnostic tool for assessing energy regulation

    Ergonomics

    (1998)
  • M Bak et al.

    Visual sensations produced by intracortical microstimulation of the human occipital cortex

    Med Biol Eng Comput

    (1990)
  • A.J Bard et al.
  • X Beebe et al.

    Charge injection limits of activated iridium oxide electrodes with 0.2 ms pulses in bicarbonate buffered saline

    IEEE Trans Biomed Eng

    (1988)
  • S.L BeMent et al.

    Solid-state electrodes for multi-channel multiplexed intracortical neuronal recording

    IEEE Trans Biomed Eng

    (1986)
  • E.L Berson et al.

    A randomized trial of vitamin A and vitamin E supplementation for retinitis pigmentosa

    Arch Ophthalmol

    (1993)
  • H Bostock

    The strength-duration relationship for excitation of myelinated nervecomputed dependence on membrane parameters

    J Physiol

    (1983)
  • J.A Brabyn

    New developments in mobility and orientation aids for the blind

    IEEE Trans Biomed Eng

    (1982)
  • N.M Bressler

    Photodynamic therapy of subfoveal choroidal neovascularization in age-related macular degeneration with verteporfintwo-year results of 2 randomized clinical trials—TAP report 2

    Arch Ophthalmol

    (2001)
  • G.S Brindley

    The number of information channels needed for efficient reading

    J Physiol

    (1965)
  • G.S Brindley et al.

    The sensations produced by electrical stimulation of the visual cortex

    J Physiol

    (1968)
  • G.S Brindley et al.

    The visual sensations produced by electrical stimulation of the medial occipital cortex

    J Physiol

    (1968)
  • G Brindley et al.

    Implanted stimulators of the visual cortex as visual prosthetic devices

    Trans Am Acad Ophthalmol Otolaryngol

    (1974)
  • W.J Brown et al.

    Tissue reactions to long-term electrical stimulation of the cerebellum in monkeys

    J Neurosurg

    (1977)
  • S.B Brummer et al.

    Electrochemical considerations for safe electrical stimulation of the nervous system with platinum electrodes

    IEEE Trans Biomed Eng

    (1977)
  • J.R Buckett et al.

    A flexible, portable system for neuromuscular stimulation in the paralyzed upper extremity

    IEEE Trans Biomed Eng

    (1988)
  • J Buffet

    Technological progress in pacemaker designhermetic sealing

    Med Prog Technol

    (1975)
  • J Button et al.

    Visual responses to cortical stimulation in the blind

    J Iowa St Med Soc

    (1962)
  • K Cha et al.

    Simulation of a phosphene-based visual fieldvisual acuity in a pixelized vision system

    Ann Biomed Eng

    (1992)
  • K Cha et al.

    Reading speed with a pixelized vision system

    J Opt Soc Am

    (1992)
  • Cheng Y, Lin L, Najafi K: Fabrication and hermeticity testing of a glass-silicon package formed using localized...
  • A.Y Chow et al.

    The subretinal microphotodiode array retinal prosthesis

    Ophthalmic Res

    (1998)
  • Chow AY: Silicon chips implanted into the eyes of three patients to treat blindness. Available at...
  • A.Y Chow et al.

    Development and application of subretinal semiconductor microphotodiode array

  • G.M Clark

    Electrical stimulation of the auditory nervethe coding of frequency, the perception of pitch and the development of cochlear implant speech processing strategies for profoundly

    Clin Exp Pharmacol Physiol

    (1996)
  • G.M Clark et al.

    Electrical stimulation of residual hearing in the implanted cochlea

    Ann Otol Rhinol Laryngol

    (1995)
  • C.A Curcio et al.

    Photoreceptor loss in age-related macular degeneration

    Invest Ophthalmol Vis Sci

    (1996)
  • Dagnelie G, Thompson J, Barnett D, Zhang W: Simulated prosthetic vision: Perceptual and performance measures, Vision...
  • W.W Dawson et al.

    The electrical stimulation of the retina by indwelling electrodes

    Invest Ophthalmol Vis Sci

    (1977)

    • Cited by (0)

    View full text
    Copyright © 2002 Elsevier Science Inc. All rights reserved.