U.S. patent application number 11/440541 was filed with the patent office on 2006-11-09 for surgical tool for electrode implantation.
Invention is credited to Da-Yu Chang, Robert Greenberg.
Application Number | 20060253124 11/440541 |
Document ID | / |
Family ID | 37395002 |
Filed Date | 2006-11-09 |
United States Patent
Application |
20060253124 |
Kind Code |
A1 |
Greenberg; Robert ; et
al. |
November 9, 2006 |
Surgical tool for electrode implantation
Abstract
The present invention is a surgical tool for implanting an
electrode array and its connected cable within an orbital socket.
The insertion tool is used to aid the surgeon in pulling the
electrode wire and array through the scull, four-rectus muscles of
the eye, and the sclera. The insertion tool consists of a medical
grade ABS material that is commonly used in various medical
products.
Inventors: |
Greenberg; Robert; (Los
Angeles, CA) ; Chang; Da-Yu; (Rowland Heights,
CA) |
Correspondence
Address: |
Second Sight Medical Products, Inc.;Building 3
12744 San Fernando Road
Sylmar
CA
91342
US
|
Family ID: |
37395002 |
Appl. No.: |
11/440541 |
Filed: |
May 24, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10627260 |
Jul 24, 2003 |
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11440541 |
May 24, 2006 |
|
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60399012 |
Jul 26, 2002 |
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Current U.S.
Class: |
606/129 |
Current CPC
Class: |
A61F 9/08 20130101 |
Class at
Publication: |
606/129 |
International
Class: |
A61B 19/00 20060101
A61B019/00 |
Claims
1. A surgical tool for implantation of an electrode array
comprising: an end portion having a rounded point; a base portion
coupled to said end portion opposite said rounded point; and a top
portion coupled to said end portion opposite said rounded point,
the end portion forming a radius between said base portion and said
top portion, forming a space between said base portion and said top
portion whereby said base portion is parallel to said top
portion.
2. The surgical tool according to claim 1, further comprising a
hinge connecting said top portion to said rounded point.
3. The surgical tool according to claim 1, wherein said top portion
and based portion are curved to radii wherein the top portion and
base portion remain equally spaced from each other.
4. The surgical tool according to claim 3, wherein said radii
approximate the radius of an eye.
5. The surgical tool according to claim 1, wherein said top portion
and said base portion are curved on surfaces facing outward and
flat on surfaces facing each other.
6. The surgical tool according to claim 1, further comprising a
keeper connected to said base portion and limiting travel of said
top portion.
7. The surgical tool according to claim 1, further comprising
notches in said base adapted to meet guides in said top and latch
said base and said top together.
8. The surgical tool according to claim 1, fashioned from a
biocompatible elastic material.
9. The surgical tool according to claim 8, wherein said
biocompatible elastic material is ABS.
10. The surgical tool according to claim 8, wherein said
biocompatible elastic material is stainless steel.
11. The surgical tool according to claim 1, wherein said radius is
adapted to fit said electrode array when placed between said top
portion and said bottom portion.
12. A method of implanting an electrode array comprising: providing
a tool having a an end portion having a rounded point, a base
portion coupled to said end section opposite said rounded point, a
top portion coupled to said end section opposite said rounded
point, the end portion forming a radius between said base portion
and said top portion forming a space between said base portion and
said top portion whereby said base portion is parallel to said top
portion; placing an electrode between said top portion and said
base portion with a cable coupled to said electrode extending in a
direction opposite from said rounded point; passing said tool and
said electrode array into a body, said rounded point first.
13. The method according to claim 12, further comprising the step
of using said rounded point to separate extra ocular muscle.
14. The method according to claim 12, further comprising the step
of inserting said surgical tool into an orbital socket.
15. The method according to claim 12, further comprising the step
of releasing said electrode array from said tool once it is within
the orbital socket.
16. The method according to claim 15, further comprising the step
of inserting said tool into the orbital socket through a hole in a
skull.
17. The method according to claim 12, further comprising the step
of providing a hinge between said top portion and said bottom
portion.
18. The method according to claim 17, further comprising the step
of applying pressure to said top portion and said bottom portion to
retain said electrode array within said top portion and said bottom
portion.
19. The method according to claim 12, further comprising the step
of curving said top portion and said bottom portion such that they
remain equally spaced.
20. A surgical tool for implantation of an electrode array
comprising: an end portion having a rounded point; a base portion
coupled to said end portion opposite said rounded point, said base
portion having an outer surface which is concave in one dimension
and convex in another dimension, and having an inner surface which
is convex in one dimension and flat in another dimension; a top
portion coupled to said end section opposite said rounded point,
said top portion having an outer surface which is convex in two
dimensions and having an inner surface which is concave in one
dimension and flat in another dimension; and wherein said end
portion forms a radius between said base portion and said top
portion, forming a space between said base portion and said top
portion whereby said base portion is equally spaced from said top
portion along both of their inner surfaces.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of application Ser. No.
10/627,260, filed Jul. 24, 2003, which claimed the benefit of U.S.
Provisional Application No. 60/399,012, filed Jul. 26, 2002, the
disclosures of which are incorporated fully herein by
reference.
FIELD OF THE INVENTION
[0002] The present invention is generally directed to implantable
medical devices, in particular to a tool for implanting electrodes
and their association wires.
BACKGROUND OF THE INVENTION
[0003] 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 concepts 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 prosthesis devices were large, bulky and could
not produce adequate simulated vision to truly aid the visually
impaired.
[0004] 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 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.
[0005] 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.
[0006] 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 neuronal membranes, which
can initiate neuron action potentials, which are the means of
information transfer in the nervous system.
[0007] 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.
[0008] 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. This placement must be mechanically stable, minimize the
distance between the device electrodes and the neurons, and avoid
undue compression of the neurons.
[0009] 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.
[0010] 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).
[0011] 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. Such
a device increases the possibility of retinal trauma by the use of
its "bed of nails" type electrodes that impinge directly on the
retinal tissue.
[0012] 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. Retinal tacks are one way
to attach a retinal array to the retina.
[0013] The retina is extraordinarily fragile. In particular,
retinal neurons are extremely sensitive to pressure; they will die
if even a modest intraocular pressure is maintained for a prolonged
period of time. Glaucoma, which is one of the leading causes of
blindness in the world, can result from a chronic increase of
intraocular pressure of only 10 mm Hg. Furthermore, the retina, if
it is perforated or pulled, will tend to separate from the
underlying epithelium, which will eventually render it
functionless. Thus attachment of a conventional prosthetic retinal
electrode device carries with it the risk of damage to the retina,
because of the pressure that such a device could exert on the
retina.
[0014] Byers, et al. received U.S. Pat. No. 4,969,468 in 1990 which
disclosed a "bed of nails" electrode array which in combination
with processing circuitry amplifies and analyzes the signal
received from the tissue and/or which generates signals which are
sent to the target tissue. The penetrating electrodes are damaging
to the delicate retinal tissue of a human eye and therefore are not
applicable to enabling sight in the blind.
[0015] In 1992 U.S. Pat. No. 5,109,844 issued to de Juan et al. on
a method of stimulating the retina to enable sight in the blind
wherein a voltage stimulates electrodes that are in close proximity
to the retinal ganglion cells. A planar ganglion cell-stimulating
electrode is positioned on or above the retinal basement membrane
to enable transmission of sight-creating stimuli to the retina. The
electrode is a flat array containing 64-electrodes.
[0016] Norman, et al. received U.S. Pat. No. 5,215,088 in 1993 on a
three-dimensional electrode device as a cortical implant for vision
prosthesis. The device contains perhaps a hundred small pillars
each of which penetrates the visual cortex in order to interface
with neurons more effectively. The array is strong and rigid and
may be made of glass and a semiconductor material.
[0017] U.S. Pat. No. 5,476,494, issued to Edell, et al. in 1995,
describes a retinal array held gently against the retina by a
cantilever, where the cantilever is anchored some distance from the
array. Thus the anchor point is removed from the area served by the
array. This cantilever configuration introduces complexity and it
is very difficult to control the restoring force of the cantilever
due to varying eye sizes.
[0018] Sugihara, et al. received U.S. Pat. No. 5,810,725 in 1998 on
a planar electrode to enable stimulation and recording of nerve
cells. The electrode is made of a rigid glass substrate. The lead
wires which contact the electrodes are indium tin oxide covered
with a conducting metal and coated with platinum containing metal.
The electrodes are indium tin oxide or a highly electrically
conductive metal. Several lead-wire insulating materials are
disclosed including resins.
[0019] U.S. Pat. No. 5,935,155, issued to Humayun, et al. in 1999,
describes a visual prosthesis and method of using it. The Humayun
patent includes a camera, signal processing electronics and a
retinal electrode array. The retinal array is mounted inside the
eye using tacks, magnets, or adhesives. Portions of the remaining
parts may be mounted outside the eye. The Humayun patent describes
attaching the array to the retina using retinal tacks and/or
magnets. This patent does not address reduction of damage to the
retina and surrounding tissue or problems caused by excessive
pressure between the retinal electrode array and the retina.
[0020] Mortimer's U.S. Pat No. 5,987,361 of 1999 disclosed a
flexible metal foil structure containing a series of precisely
positioned holes that in turn define electrodes for neural
stimulation of nerves with cuff electrodes. Silicone rubber may be
used as the polymeric base layer. This electrode is for going
around nerve bundles and not for planar stimulation.
[0021] The retina is also very sensitive to heat. Implanting a
retinal prosthesis fully within the eye may cause excessive heat
buildup damaging the retina. It is, therefore, advantageous to
implant an electrode array on the retina attached by a cable to
heat producing electronics which are implanted somewhere outside
the eye. If no electronics are implanted in the eye, it is
necessary to run one wire for each electrode from the electronics
package to the electrode array. These wires must be extremely thin.
While grouping them together in a cable with a protective sheath
provides some protection, the array and cable must be handled
carefully to prevent damage to the electrode array or cable.
[0022] Published U.S. patent application 2002/0099420, Chow et al.
describes a surgical tool for implantation of a retinal electrode
array. The Chow device is a tube which is placed into the eye and
to the implant location. Then fluid flows though the tube pushing
the electrode array into place.
SUMMARY OF THE INVENTION
[0023] The present invention is a surgical tool for implanting an
electrode array and its connected cable within an eye. The
insertion tool is used to aid the surgeon in pulling the electrode
wire and array through the scull, four-rectus muscles of the eye,
and the sclera. The insertion tool consists of a medical grade ABS
material that is commonly used in various medical products.
[0024] The novel features of the invention are set forth with
particularity in the appended claims. The invention will be best
understood from the following description when read in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a perspective view of the retinal electrode array
assembly showing the electrodes and signal conductors as well as
mounting aperture for tacking the assembly inside the eye, wherein
both the array and its associated electronics are located inside
the eye.
[0026] FIG. 2 is a perspective view of the retinal electrode array
assembly showing the electrodes and signal conductors as well as
mounting aperture for tacking the assembly inside the eye, wherein
the associated electronics are located outside the eye.
[0027] FIG. 3 is a perspective view of the retinal electrode array
assembly wherein the array is installed inside the eye and the
associated electronics are installed outside the eye at some
distance from the sclera wherein the feeder cable contains both a
coiled cable leading between the electronics and the sclera and a
series of fixation tabs along the feeder cable for securing the
feeder cable by suture.
[0028] FIG. 4 is a cross-sectional view of the retinal electrode
array, the sclera, the retina and the retinal electrode array
showing the electrodes in contact with the retina.
[0029] FIG. 5 depicts a cross-sectional view of the retinal
electrode array showing a strain relief slot, strain relief
internal tab and a mounting aperture through a reinforcing ring for
a mounting tack to hold the array in position.
[0030] FIG. 6 illustrates a cross-sectional view of the retinal
electrode array showing a strain relief slot and a ferromagnetic
keeper to hold the array in position.
[0031] FIG. 7 illustrates a cross-sectional view of the retinal
electrode array showing a strain relief slot and a mounting
aperture through a reinforcing ring for a mounting tack to hold the
array in position, wherein the strain relief internal tab
containing the mounting aperture is thinner than the rest of the
array.
[0032] FIG. 8 is a perspective view of the preferred insertion
tool, for inserting the array of FIGS. 1-7, having an curved tongs
and a spring base.
[0033] FIG. 9 is a mechanical drawing of an alternate embodiment of
the insertion tool illustrated in FIG. 8 having straight tongs and
a.
[0034] FIG. 10 is a perspective view of an alternate embodiment
using a hinged base.
[0035] FIG. 11 is a perspective view of an alternate embodiment
using curved tongs and a hinged base.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] 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.
[0037] FIG. 1 provides a perspective view of a preferred embodiment
of the retinal electrode array (implanted by the surgical too of
the resent invention), generally designated 2, comprising
oval-shaped electrode array body 4, a plurality of electrodes 6
made of a conductive material, such as platinum or one of its
alloys, but that can be made of any conductive biocompatible
material such as iridium, iridium oxide or titanium nitride, and
single reference electrode 6A made of the same material as
electrode 6, wherein the electrodes are individually attached to
separate conductors 8 made of a conductive material, such as
platinum or one of its alloys, but which could be made of any
biocompatible conductive material, that is enveloped within an
insulating sheath 10, that is preferably silicone, that carries an
electrical signal to each of the electrodes 6. "Oval-shaped"
electrode array body means that the body may approximate either a
square or a rectangle shape, but where the corners are rounded. The
reference electrode 6A is not necessarily stimulated, but is
attached to a conductor, as are electrodes 6. The electrodes could
be used in another application as sensors to transmit electrical
signals from a nerve. The electrodes 6 transmit an electrical
signal to the eye while reference electrode 6A may be used as a
ground, reference, or control voltage.
[0038] Electrode array body 4 is made of a soft material that is
compatible with the body. In a preferred embodiment array body 4 is
made of silicone having a hardness of about 50 or less on the Shore
A scale as measured with a durometer. In an alternate embodiment
the hardness is about 25 or less on the Shore A scale as measured
with a durometer. It is a substantial goal to have electrode array
body 4 in intimate contact with the retina of the eye.
[0039] Strain relief internal tab 12, defined by a strain relief
slot 13 that passes through the array body 4, contains a mounting
aperture 16 for fixation of the electrode array body 4 to the
retina of the eye by use of a surgical tack, although alternate
means of attachment such as glue or magnets may be used.
Reinforcing ring 14 is colored and opaque to facilitate locating
mounting aperture 16 during surgery and may be made of tougher
material, such as high toughness silicone, than the body of the
electrode array body to guard against tearing.
[0040] Signal conductors 8 are located in an insulated flexible
feeder cable 18 carrying electrical impulses from the electronics
20 to the electrodes 6, although the electrodes can be sensors that
carry a signal back to the electronics. Signal conductors 8 can be
wires, as shown, or in an alternative embodiment, a thin
electrically conductive film, such as platinum, deposited by
sputtering or an alternative thin film deposition method. In a
preferred embodiment, the entire retinal electrode array 2
including the feeder cable 18 and electronics 6 are all implanted
inside the eye. Electronics 20 may be fixated inside the eye to the
sclera by sutures or staples that pass through fixation tabs 24.
The conductors are covered with silicone insulation.
[0041] Grasping handle 46 is located on the surface of electrode
array body 4 to enable its placement by a surgeon using forceps or
by placing a surgical tool into the hole formed by grasping handle
46. Grasping handle 46 avoids damage to the electrode body that
might be caused by the surgeon grasping the electrode body
directly. Grasping handle 46 also minimizes trauma and
stress-related damage to the eye during surgical implantation by
providing the surgeon a convenient method of manipulating electrode
array body 4. Grasping handle 46 is made of silicone having a
hardness of about 50 on the Shore A scale as measured with a
durometer. A preferred embodiment of the electrode array body 4 is
made of a very soft silicone having hardness of 50 or less on the
Shore A scale as measured with a durometer. The reinforcing ring 14
is made of opaque silicone having a hardness of 50 on the Shore A
scale as measured with a durometer.
[0042] FIG. 2 provides a perspective view of the retinal electrode
array assembly 2 wherein the electrode array body 4 is implanted
inside the eye and the electronics 20 are placed outside the eye
with the feeder cable 18 passing through sclera 30. In this
embodiment, electronics 38 are attached by fixation tabs 24 outside
the eye to sclera 30.
[0043] FIG. 3 provides a perspective view of retinal electrode
array 2 wherein electrode array body 4 is implanted on the retina
inside the eye and electronics 38 are placed outside the eye some
distance from sclera 30 wherein feeder cable 18 contains sheathed
conductors 10 as silicone-filled coiled cable 22 for stress relief
and flexibility between electronics 38 and electrode array body 4.
Feeder cable 18 passes through sclera 30 and contains a series of
fixation tabs 24 outside the eye and along feeder cable 18 for
fixating cable 18 to sclera 30 or elsewhere on the recipient
subject.
[0044] FIG. 4 provides a cross-sectional view of electrode array
body 4 in intimate contact with retina 32. The surface of electrode
array body 4 in contact with retina 32 is a curved surface 28
substantially conforming to the spherical curvature of retina 32 to
minimize stress concentrations therein. Further, the decreasing
radius of spherical curvature of electrode array body 4 near its
edge forms edge relief 36 that causes the edges of array body 4 to
lift off the surface of retina 32 eliminating stress
concentrations. The edge of electrode array body 4 has a rounded
edge 34 eliminating stress and cutting of retina 32. The axis of
feeder cable 18 is at right angles to the plane of this
cross-sectional view. Feeder cable 18 is covered with silicone.
[0045] FIG. 5 provides a cross-sectional view of electrode array
body 4 showing spherically curved surface 28, strain relief slot 13
and mounting aperture 16 through which a tack passes to hold array
body 4 in intimate contact with the eye. Mounting aperture 16 is
located in the center of reinforcing ring 14 that is opaque and
colored differently from the remainder of array body 4, making
mounting aperture 16 visible to the surgeon. Reinforcing ring 14 is
made of a strong material such as tough silicone, which also
resists tearing during and after surgery. Strain relief slot 13
forms strain relief internal tab 12 in which reinforcing ring 14 is
located. Stresses that would otherwise arise in the eye from
tacking array body 4 to the eye through mounting aperture 16 are
relieved by virtue of the tack being located on strain relief
internal tab 12.
[0046] FIG. 6 provides a cross-sectional view of a preferred
embodiment of electrode array body 4 showing ferromagnetic keeper
40 that holds electrode array body 4 in position against the retina
by virtue of an attractive force between keeper 40 and a magnet
located on and attached to the eye.
[0047] FIG. 7 is a cross-sectional view of the electrode array body
4 wherein internal tab 12 is thinner than the rest of electrode
array body 4, making this section more flexible and less likely to
transmit attachment induced stresses to the retina. This embodiment
allows greater pressure between array body 4 and the retina at the
point of attachment, and a lesser pressure at other locations on
array body 4, thus reducing stress concentrations and irritation
and damage to the retina.
[0048] FIG. 8 is a perspective view of the preferred insertion tool
50. The electrode array body 4 and feeder cable 18 are extremely
delicate. They must pass through a hole in the scull, pass under
the four-rectus muscles of the eye, through the sclera and be
attached to the retina. The insertion tool 50 has a rounded point
52 for gently separating muscle and flesh as the tool is passed
through. The rounded point 52 is rigidly attached to a base 54 and
top 56. Both the base 54 and the top 58 are rounded on the outside
and square on the inside. The rounding helps the tool pass through
flesh without causing damage. The electrode body 4 is place between
the base 54 and top 58. Spring force traps the electrode array body
4 between the base 54 and top 58. The tool further includes a
radius 64 between the base 54 and the top 58, which provides a
space between the base 54 and the top 58 such that even pressure is
applied along the length of the base 54 and the top 58. The radius
64 reduces stress concentrations that could crack the tool at the
junction of the base and top with the base and top are deflected
while loading or unloading the electrode array. The even pressure
allows a surgeon to hold the electrode array body 4 and feeder
cable 18 firmly without causing unnecessary stress on the electrode
array body 4. The tool is fashioned from an inert biocompatible
material that includes resilient elastic properties such ABS,
stainless steel or titanium. ABS is suitable as a single use,
disposable surgical tool while stainless steel or titanium could be
steam sterilized and reused.
[0049] Once the electrode array body 4 and the feeder cable 18 are
safely held in the surgical tool 50, the surgeon can pass the tool
50, electrode array body 4 and the feeder cable 18 in the same
manner as a needle and thread. The preferred surgical tool 50 is
curved to promote easy movement around the eye. The curvature of
the tool generally conforms to the curvature of the outside of the
sclera. Alternatively the surgical tool may be strait as shown in
FIG. 9.
[0050] FIG. 9 shows an alternate embodiment of the surgical tool
150. The alternate surgical tool 150 has a strait base 54 and top
58, while retaining the radius 164 and rounded point 152 of the
preferred embodiment. There are advantages to strait and curved
surgical tools for much the same reasons there are advantages to
strait and curved needles. Different surgeons may prefer different
tools.
[0051] FIG. 10 shows another alternate embodiment. Rather than
relying on spring force to hold the electrode array body 4 and the
feeder cable 18 in the tool 250. The base 254 is rigidly attached
to the rounded point 252, but the top 258 is attached by a hinge
256 to the base 254 and rounded point 252. This allows the surgeon
more control of the force applied to the electrode array body 4 and
the feeder cable 18. The hinge 256 further provides for easier
loading and unloading of the electrode array. This embodiment
retains the radius 264 to provide even pressure along the lengths
of the base 254 and the top 258. This embodiment further includes
notches 260 in the base 254, which mate with guides 262 in the top
258 to hold the electrode array body 4 and the feeder cable 18 in
the tool 250, by holding the top 258 and base 254 together. The
radius 264 reduces stress concentrations that could crack the tool
at the junction of the base and top with the base and top are
deflected while loading or unloading the electrode array.
[0052] FIG. 11 shows another alternate embodiment, similar to that
shown in FIG. 12. The base 354 is rigidly attached to the rounded
point 352, but the top 358 is attached by a hinge 356 to the base
354 and rounded point 352. The hinge 356 further provides for
easier loading and unloading of the electrode array. This
embodiment retains the radius 264 to provide even pressure along
the lengths of the base 354 and the top 358. However, the base 354
and top 358 are curved to allow for easier insertion of the tool.
This embodiment further includes a keeper 360 attached to the base
354, which covers the top 358 to limit movement and prevents
opening the tool and possibly dropping the array body 4.
[0053] 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.
* * * * *