U.S. patent application number 10/918112 was filed with the patent office on 2006-05-25 for retinal prosthesis.
Invention is credited to Robert Greenberg, James Little, Brian V. Mech, Neil Talbot.
Application Number | 20060111757 10/918112 |
Document ID | / |
Family ID | 35800994 |
Filed Date | 2006-05-25 |
United States Patent
Application |
20060111757 |
Kind Code |
A9 |
Greenberg; Robert ; et
al. |
May 25, 2006 |
Retinal prosthesis
Abstract
The invention is a retinal prosthesis with an improved
configuration mounting necessary components within and surrounding
the eye. The present invention better allows for the implantation
of electronics within the delicate eye structure. The invention
further limits the necessary width of a thin film conductor passing
through the sclera by use of a multiplexer external to the sclera
and a demultiplexer internal to the sclera.
Inventors: |
Greenberg; Robert; (Los
Angeles, CA) ; Talbot; Neil; (Montrose, CA) ;
Mech; Brian V.; (Stevenson Ranch, CA) ; Little;
James; (Saugus, CA) |
Correspondence
Address: |
SECOND SIGHT MEDICAL PRODUCTS, INC.
12744 SAN FERNANDO ROAD
BUILDING 3
SYLMAR
CA
91342
US
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Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20060036295 A1 |
February 16, 2006 |
|
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Family ID: |
35800994 |
Appl. No.: |
10/918112 |
Filed: |
August 13, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60574130 |
May 25, 2004 |
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Current U.S.
Class: |
607/54 |
Current CPC
Class: |
A61N 1/36046 20130101;
A61N 1/0543 20130101 |
Class at
Publication: |
607/054 |
International
Class: |
A61N 1/05 20060101
A61N001/05 |
Goverment Interests
GOVERNMENT RIGHTS NOTICE
[0001] This invention was made with government support under grant
No. R24EY12893-01, awarded by the National Institutes of Health.
The government has certain rights in the invention.
Claims
1. A retinal prosthesis comprising: An electrode array suitable to
be mounted in close proximity to a retina; A demultiplexer
electrically coupled to said electrode array; and An implantable
electronics package, including a multiplexer, electrically coupled
to said demultiplexer.
2. The retinal prosthesis according to claim 1, wherein said
electronics package is in a hermetic package.
3. The retinal prosthesis according to claim 1, wherein said
demultiplexer is suitable to be mounted within the eye, but distant
from the retina.
4. The retinal prosthesis according to claim 1, wherein said
demultiplexer is on a silicon chip.
5. The retinal prosthesis according to claim 4, wherein said
silicon chip is attached to a thin film cable.
6. The retinal prosthesis according to claim 4, wherein said
silicon chip is enclosed within a hermetic package.
7. The retinal prosthesis according to claim 6, wherein said
hermetic package is a hermetic case.
8. The retinal prosthesis according to claim 6, wherein said
hermetic package is a thin film hermetic coating.
9. The retinal prosthesis according to claim 1, wherein said
electrode array and said demultiplexer are formed on a common
substrate.
10. The retinal prosthesis according to claim 9, wherein said
common substrate is a silicon chip.
11. The retinal prosthesis according to claim 10, wherein said
silicon chip includes electrodes on a first side and electrical
contacts for a cable on a side opposite said first side.
12. The retinal prosthesis according to claim 11, further
comprising conductive feedthroughs in said silicon chip.
13. The retinal prosthesis according to claim 1, wherein said
electronics package is suitable to be mounted external to the
sclera, but supported by the sclera.
14. The retinal prosthesis according to claim 13, wherein said
electronics package is mounted lateral to the sclera.
15. The retinal prosthesis according to claim 1, wherein said
multiplexer is said side opposite of said first side.
16. The retinal prosthesis according to claim 1, wherein said
electronics package is coupled to a implantable coil.
17. The retinal prosthesis according to claim 1, wherein said
multiplexer is deposited on a thin film substrate.
18. The retinal prosthesis according to claim 1, wherein said
electrode array and said multiplexer are deposited on a common thin
film substrate.
19. A retinal prosthesis comprising: An electrode array suitable to
be mounted in close proximity to a retina; A demultiplexer suitable
to be mounted internal to the sclera; An electronics package
suitable to be mounted within the eye and supported by the sclera;
A first cable electrically coupling said electrode array to said
demultiplexer; A second cable electrically coupling said
demultiplexer to said electronics package; and An implantable coil
electrically coupled to said electronics package.
20. The retinal prosthesis according to claim 19, wherein said
demultiplexer is suitable to be mounted within the eye, but distant
from the retina.
21. The retinal prosthesis according to claim 19, wherein said
demultiplexer is on a silicon chip.
22. The retinal prosthesis according to claim 19, wherein said
electrode array and said demultiplexer are formed on a common
substrate.
23. The retinal prosthesis according to claim 19, wherein said
common substrate is a silicon chip.
24. The retinal prosthesis according to claim 23, wherein said
silicon chip is attached to a thin film cable.
25. The retinal prosthesis according to claim 23, wherein said
silicon chip includes electrodes on a first side and electrical
contacts for a cable on a side opposite said first side.
26. The retinal prosthesis according to claim 25, further
comprising conductive feedthroughs in said silicon chip.
27. The retinal prosthesis according to claim 19, wherein said
multiplexer is deposited on a thin film substrate.
28. The retinal prosthesis according to claim 19, wherein said
electrode array and said multiplexer are deposited on a common thin
film substrate.
29. The retinal prosthesis according to claim 19, wherein said
electrode array, said multiplexer, said first cable and said second
cable are deposited on a common thin film substrate.
30. A retinal prosthesis comprising: A camera for collecting a
video image; A video processor coupled to said camera for
processing said video image; A primary coil coupled to said video
processor for transmitting said video image into a body; An
secondary coil suitable to be implanted within the body but
external to a sclera for receiving said video image; An electronics
package, electrically coupled to said secondary coil, suitable to
be mounted external to the sclera and supported by the sclera; A
demultiplexer suitable to be mounted internal to the sclera; An
electrode array suitable to be mounted in close proximity to a
retina; A first cable electrically coupling said electrode array to
said demultiplexer; A second cable electrically coupling said
demultiplexer to said electronics package; and A second cable
electrically coupling said demultiplexer to said electronics
package.
31. The retinal prosthesis according to claim 18, wherein said
demultiplexer is a silicon chip.
32. The retinal prosthesis according to claim 19, wherein said
silicon chip is within a hermetic package.
Description
FIELD OF THE INVENTION
[0002] The present invention is generally directed to a visual
prosthesis and more specifically to an improved mechanical and
electrical configurations for retinal prosthesis for artificial
vision.
CROSS REFERENCE TO RELATED APPLICATIONS
[0003] This application is related to, and claims priority of,
provisional patent application attorney docket S300-PRO Retinal
Prosthesis.
BACKGROUND OF THE INVENTION
[0004] In 1755 LeRoy passed the discharge of a Leyden jar through
the orbit of a man who was blind from cataract and the patient saw
"flames passing rapidly downwards." Ever since, there has been a
fascination with electrically elicited visual perception. The
general concept of electrical stimulation of retinal cells to
produce these flashes of light or phosphenes has been known for
quite some time. Based on these general principles, some early
attempts at devising a prosthesis for aiding the visually impaired
have included attaching electrodes to the head or eyelids of
patients. While some of these early attempts met with some limited
success, these early prosthetic devices were large, bulky and could
not produce adequate simulated vision to truly aid the visually
impaired.
[0005] In the early 1930's, Foerster investigated the effect of
electrically stimulating the exposed occipital pole of one cerebral
hemisphere. He found that, when a point at the extreme occipital
pole was stimulated, the patient perceived a small spot of light
directly in front and motionless (a phosphene). Subsequently,
Brindley and Lewin (1968) thoroughly studied electrical stimulation
of the human occipital (visual) cortex. By varying the stimulation
parameters, these investigators described in detail the location of
the phosphenes produced relative to the specific region of the
occipital cortex stimulated. These experiments demonstrated: (1)
the consistent shape and position of phosphenes; (2) that increased
stimulation pulse duration made phosphenes brighter; and (3) that
there was no detectable interaction between neighboring electrodes
which were as close as 2.4 mm apart.
[0006] As intraocular surgical techniques have advanced, it has
become possible to apply stimulation on small groups and even on
individual retinal cells to generate focused phosphenes through
devices implanted within the eye itself. This has sparked renewed
interest in developing methods and apparati to aid the visually
impaired. Specifically, great effort has been expended in the area
of intraocular retinal prosthesis devices in an effort to restore
vision in cases where blindness is caused by photoreceptor
degenerative retinal diseases such as retinitis pigmentosa and age
related macular degeneration which affect millions of people
worldwide.
[0007] Neural tissue can be artificially stimulated and activated
by prosthetic devices that pass pulses of electrical current
through electrodes on such a device. The passage of current causes
changes in electrical potentials across visual neuronal membranes,
which can initiate visual neuron action potentials, which are the
means of information transfer in the nervous system.
[0008] Based on this mechanism, it is possible to input information
into the nervous system by coding the information as a sequence of
electrical pulses which are relayed to the nervous system via the
prosthetic device. In this way, it is possible to provide
artificial sensations including vision.
[0009] One typical application of neural tissue stimulation is in
the rehabilitation of the blind. Some forms of blindness involve
selective loss of the light sensitive transducers of the retina.
Other retinal neurons remain viable, however, and may be activated
in the manner described above by placement of a prosthetic
electrode device on the inner (toward the vitreous) retinal surface
(epiretinal). This placement must be mechanically stable, minimize
the distance between the device electrodes and the visual neurons,
and avoid undue compression of the visual neurons.
[0010] In 1986, Bullara (U.S. Pat. No. 4,573,481) patented an
electrode assembly for surgical implantation on a nerve. The matrix
was silicone with embedded iridium electrodes. The assembly fit
around a nerve to stimulate it.
[0011] Dawson and Radtke stimulated cat's retina by direct
electrical stimulation of the retinal ganglion cell layer. These
experimenters placed nine and then fourteen electrodes upon the
inner retinal layer (i.e., primarily the ganglion cell layer) of
two cats. Their experiments suggested that electrical stimulation
of the retina with 30 to 100 uA current resulted in visual cortical
responses. These experiments were carried out with needle-shaped
electrodes that penetrated the surface of the retina (see also U.S.
Pat. No. 4,628,933 to Michelson).
[0012] The Michelson '933 apparatus includes an array of
photosensitive devices on its surface that are connected to a
plurality of electrodes positioned on the opposite surface of the
device to stimulate the retina. These electrodes are disposed to
form an array similar to a "bed of nails" having conductors which
impinge directly on the retina to stimulate the retinal cells. U.S.
Pat. No. 4,837,049 to Byers describes spike electrodes for neural
stimulation. Each spike electrode pierces neural tissue for better
electrical contact. U.S. Pat. No. 5,215,088 to Norman describes an
array of spike electrodes for cortical stimulation. Each spike
pierces cortical tissue for better electrical contact.
[0013] The art of implanting an intraocular prosthetic device to
electrically stimulate the retina was advanced with the
introduction of retinal tacks in retinal surgery. De Juan, et al.
at Duke University Eye Center inserted retinal tacks into retinas
in an effort to reattach retinas that had detached from the
underlying choroid, which is the source of blood supply for the
outer retina and thus the photoreceptors. See, e.g., E. de Juan, et
al., 99 Am. J. Ophthalmol. 272 (1985). These retinal tacks have
proved to be biocompatible and remain embedded in the retina, and
choroid/sclera, effectively pinning the retina against the choroid
and the posterior aspects of the globe. Humayun, U.S. Pat. No.
5,935,155 describes the use of retinal tacks to attach a retinal
array to the retina. Alternatively, an electrode array may be
attached by magnets or glue. U.S. Pat. No. 5,109,844 to de Juan
describes a flat electrode array placed against the retina for
visual stimulation.
[0014] Any device for stimulating percepts in the retina must
receive a signal describing a visual image along with power to
operate the device. The device can not be powered by wires as any
connection through the skin will create the risk of infection.
Battery power is not practical as batteries are bulky and surgery
is required to replace them. Such signal and power may be
transmitted into the eye inductively as shown in Humayun U.S. Pat.
No. 5,935,155. Humayun uses a primary (external) coil in front of
the eye, possibly encased within the rim of a pair of glasses, and
a secondary (internal) coil within the lens capsule or around the
sclera just under the conjunctiva. Implanting within the lens
capsule is difficult surgery and only allows for a small diameter
coil. Larger coils are more efficient, can receive more power with
less resulting temperature rise per unit of power received.
Implanting around the sclera under the conjunctiva and near the
surgical limbus (that is at the front of the eye) allows for a
larger coil but may cause irritation or damage to the conjunctiva
if the coil is placed in front near the cornea.
[0015] U.S. patent application Ser. No. 09/761,270, Ok, discloses
several coil configurations including a configuration where the
coil is offset about 45 degrees from the front of the eye. The
offset configuration allows the primary and secondary coils to be
placed closer together allowing for better inductive coupling. The
bridge of nose partially blocks placement of a primary coil when
placed directly in front of the eye.
[0016] Vision simulations show that approximately 1000 pixels are
needed to achieve basic visual functions such a face recognition
and reading. It would be difficult or impossible to mount the
electronics need for 1000 pixels within the eye. Even if the
electronics could be fit within the eye, heat dissipation would be
a major issue. It would be equally difficult to pass a cable
capable of caring 1000 signal wires through the sclera. New
mechanical and electrical configurations are needed to supply such
a high density electrode array.
SUMMARY OF THE INVENTION
[0017] The invention is a retinal prosthesis with an improved
configuration mounting necessary components within and surrounding
the eye. The present invention better allows for the implantation
of electronics, capable of high resolution display, within the
delicate eye structure. The invention further limits the necessary
width of a thin film conductor passing through the sclera by use of
a multiplexer external to the sclera and a demultiplexer internal
to the sclera.
[0018] Applicants have discovered that a coil and electronics
package around the sclera at or near 90 degrees rotation toward the
lateral side of the eye has several advantages over previous
designs. The secondary coil will not irritate the conjunctiva as it
is placed against the sclera under the lateral rectus muscle, well
behind the region where the conjunctiva attaches to the surgical
limbus which is most susceptible to irritation. There is also more
room between the conjunctiva and sclera on the side of the eye
compared to the front of the eye. The primary coil can be placed on
the temples of a pair of glasses and/or hidden by the user's hair.
The spacing between primary and secondary coil can be as close, or
closer, than that allowed for a coil pair located in the front of
the eye or at a 45 degree angle because there are no eyelids or
eyelashes to interfere with the coil.
[0019] Such a side coil design, coil and electronics outside the
eye and demultiplexer inside the eye, facilitates the necessary
space and heat dissipation needed for a high resolution video
prosthesis.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a perspective view of the implanted portion of the
preferred retinal prosthesis.
[0021] FIG. 2 depicts a retinal prosthesis with a secondary
processing chip, including a demultiplexer, in the retina.
[0022] FIG. 3 depicts a retinal prosthesis with a secondary
processing chip, including a demultiplexer, within the sclera but
not on the retina.
[0023] FIG. 4 depicts a retinal prosthesis with a polymer thin film
based secondary processor, including a demultiplexer, on the
retina.
[0024] FIG. 5 depicts a retinal prosthesis with a polymer thin film
based secondary processor, including a demultiplexer, within the
sclera, but not on the retina.
[0025] FIG. 6 is an external profile view of a user wearing the
external portion of the retinal prosthesis.
[0026] FIG. 7 is a description of the preferred demultiplexer and
electrode chip.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] The following description is of the best mode presently
contemplated for carrying out the invention. This description is
not to be taken in a limiting sense, but is made merely for the
purpose of describing the general principles of the invention. The
scope of the invention should be determined with reference to the
claims.
[0028] FIG. 1 shows a perspective view of the implanted portion of
the preferred retinal prosthesis. An electrode array 10 is mounted
by a retinal tack or similar means to the epiretinal surface. The
electrode array 10 is electrically coupled by a cable 12 which
pierces the sclera and is electrically coupled to an electronics
package 14, external to the sclera. It is advantageous to encase
the electronics within a hermetic package. This can be accomplished
by use of a metal, ceramic polymer or a combination of these
materials case, or by applying a thin film hermetic coating such as
described in U.S. patent application 20020038134 Package for an
Implantable Medical Device and 20020120296, Implantable Device
Using Ultra-Nanocrystalline Diamond. An electronics package with a
coil mounted on the lateral surface of the retina is described in
US patent application attorney docket S293-USA. All of the above
applications are incorporated herein by reference.
[0029] It is advantageous to mount electronics external to the
sclera, as the fatty tissue there is less heat sensitive, and blood
flow rapidly dissipates excess heat. The vitreous within the eye is
does not change often and the retina is very heat sensitive.
[0030] The electronics package 14 is electrically coupled to a
secondary inductive coil 16. Preferably the secondary inductive
coil 16 is made from wound wire. Alternatively, the secondary
inductive coil may be made from a thin film polymer sandwich with
wire traces deposited between layers of thin film polymer. The
electronics package 14 and secondary inductive coil 16 are held
together by a molded body 18. The molded body 18 may also include
suture tabs 20. The molded body narrows to form a strap 22 which
surrounds the sclera and holds the molded body 18, secondary
inductive coil 16, and electronics package 14 in place. The molded
body 18, suture tabs 20 and strap 22 are preferably an integrated
unit made of silicone elastomer. Silicone elastomer can be formed
in a pre-curved shape to match the curvature of a typical sclera.
However, silicone remains flexible enough to accommodate
implantation and to adapt to variations in the curvature of an
individual sclera. The secondary inductive coil 16 and molded body
18 are preferably oval shaped. A strap can better support an oval
shaped coil.
[0031] It should be noted that the entire implant is attached to
and supported by the sclera. An eye moves constantly. The eye moves
to scan a scene and also has a jitter motion to improve acuity.
Even though such motion is useless in the blind, it often continues
long after a person has lost their sight. It is an advantage of the
present design, that the entire implanted portion of the prosthesis
is attached to and supported by the sclera. By placing the device
under the rectus muscles with the electronics package in an area of
fatty issue between the rectus muscles, eye motion does not cause
any flexing which might fatigue, and eventually damage, the
device.
[0032] As we improve the resolution of retinal prostheses, the
number of electrodes increases. As the number of electrodes
increases the number of wires between the electronics package and
the electrode array must increase. This increase requires a wider
thin film cable piercing the sclera. If the thin film cable is too
wide, the sclerotomy may not heal properly. FIG. 2-5 present
embodiments to provide for a narrower thin film cable between the
electronics, external to the sclera, and the electrode array within
the sclera.
[0033] A common method of reducing the conductor count in cables,
is the use of a multiplexer and demultiplexer. However,
multiplexers, like any electronic circuit, present unique problems
when implanted within the human body. All electronics must be
sealed to prevent the saline body fluids from harming the
electronics and to prevent the electronics from harming the body.
Each electrical wire entering and exiting the electronics package
must also be sealed. Therefore it is advantageous the limit the
number of such wire electronics package interconnects. While it is
easy to include a multiplexer within the electronics package, it is
more difficult to house a demultiplexer within the sclera.
[0034] FIG. 2, depicts the preferred embodiment where a computer
chip 110, including a demultiplexer is placed directly on the
retina. The demultiplexer interconnects with the thin film cable
112 on one side and includes electrode openings, for contacting the
retina on the other side. This is best accomplished by create
feedthroughs in the silicon chip to allows electrodes on one side
of the chip and connection to the flexible cable on the other side
of the chip (described in more detail in FIG. 7. Cable 112 pierces
the sclera and attaches to an electronics package 114. The
electronics package connects to a coil 116. The chip 110 must be
coated with a thin film hermetic coating as described above. This
is the simplest most cost effective method of providing a
demultiplexer within the sclera.
[0035] Silicon chips such as chip 110 are necessarily flat. It is
possible through polishing to slightly curve one side, but the
curvature is limited as the electrical circuit on the chip must be
flat. It is possible that chip 110 may be a series of silicon chips
bonded to a flexible membrane to approximate the curvature of the
retina. This allows for a larger electrode array than would be
possible with a single chip 110.
[0036] However, the retina is extremely delicate and can be damaged
by either the weight of such a demultiplexer chip or chips, or by
the heat generated by the demultiplexer chip. If the chip can not
be made light enough or cool enough to attach to the sclera, other
solutions are needed.
[0037] FIG. 3, depicts an alternate embodiment where a
demultiplexer chip 224 is positioned within the eye, but not on the
retina. Electrode array 210 is connected to the demultiplexer 224
by a wide cable 226, and demultiplexer 224 is connected to the
electronics package 214 by a narrow cable 212. Narrow cable 212
pierces the sclera to attach to an electronics package 214. The
electronics package 214 also connects to a coil 216. This
embodiment requires two interconnects on the external electronics
package 214, one for the coil, and a low density interconnect to a
cable piercing the sclera. This cable piercing the sclera is
connected to another low density interconnect on the demultiplexer
chip within the sclera. Finally there must be a high density
interconnect on the demultiplexer connected to a thin film
electrode array. While this solution is more complex, it moves the
weight and heat of the demultiplexer off the retina.
[0038] FIG. 4, depicts yet another embodiment where the
demultiplexer is not a silicon based integrated circuit, but an
integrated circuit deposited directly on the thin film electrode
array 310. The demultiplexer interconnects with the thin film cable
312 on one side and includes electrode openings, for contacting the
retina on the other side. Cable 312 pierces the sclera and attaches
to an electronics package 314. The electronics package connects to
a coil 316. Several integrated circuit manufacturers are building
integrated circuits on Mylar thin films. The same technique can be
used to build integrated circuits on polyimide or other
biocompatible thin film polymers. By depositing the demultiplexer
circuitry directly on the thin film, one avoids the weight of a
silicon based integrated circuit and the possible damage to the
retina cause by the weight of a silicon based demultiplexer.
Further, building the demultiplexer circuit directly on the thin
films avoids the need for a hermetic interconnection to a
demultiplexer chip or a hermetic coating on the chip. If the heat
output of a thin film based demultiplexer is sufficiently small,
the demultiplexer can be built directly into the electrode array,
completely eliminating the need for a thin film wide enough to
include one connector for each electrode.
[0039] If the heat output of a thin film demultiplexer is likely to
cause damage to the retina, another embodiment, shown in FIG. 5,
provides a thin film demultiplexer between the electrode array and
electronics package, but sufficiently distant from the retina, to
avoid heat damage. FIG. 5, depicts an alternate embodiment where a
thin film demultiplexer 424 is positioned within the eye, but not
on the retina. Electrode array 410 is connected to the
demultiplexer 424 by a wide cable 426, and demultiplexer 424 is
connected to the electronics package 414 by a narrow cable 412.
Narrow cable 412 pierces the sclera to attach to an electronics
package 414. The electronics package 414 connects to a coil 416. It
is possible to form the electrode 410, wide cable, 426,
demultiplexer 424, and thin cable 412 on a single thin film
substrate. While this solution is more complex, it moves the heat
of the demultiplexer off the retina.
[0040] FIG. 6 depicts the profile of a user wearing the external
portion of the retinal prosthesis. The entire device may be built
into the temple of a pair of glasses. A camera 530 collects a video
image and transmits data to an external electronics package 532. A
battery 534 powers the camera 530, external electronics package
532, and provides power to a primary inductive coil 536. The
primary inductive coil 536 sends power and data through the skin
and skull to the secondary inductive coil 16. Maximum efficiency is
obtained when the primary inductive coil 536 and secondary
inductive coil 16 are the same size, shape and as close together as
possible.
[0041] FIG. 7, depicts the preferred demultiplexer chip 110. A
silicon substrate 610 has a demultiplexer 612 applied by
conventional means. Micromachining techniques are used to create
voids in the silicon substrate 610, which are filled with
conductive feedthroughs 616. Electrodes 614, for contact with the
retina, are applied to the conductive feedthroughs 616 by
electroplating or other means. A thin film hermetic coating 618 is
applied to the silicon substrate 610 allowing voids for electrodes
614 and contacts 620. Finally a thin film cable 622 is attached to
the contacts 620 to supply power and signal to the demultiplexer
chip.
[0042] Accordingly, what has been shown is an improved retinal
prosthesis. While the invention has been described by means of
specific embodiments and applications thereof, it is understood
that numerous modifications and variations could be made thereto by
those skilled in the art without departing from the spirit and
scope of the invention. It is therefore to be understood that
within the scope of the claims, the invention may be practiced
otherwise than as specifically described herein.
* * * * *