U.S. patent application number 12/620557 was filed with the patent office on 2010-05-13 for manufacture of an organ implant.
This patent application is currently assigned to AqueSys, Inc.. Invention is credited to Cory Anderson, Stephen Cringle, Surag Mantri, James McCrea, Daniel Mufson, Hoang Van Nguyen, Er-Ning Su, Colin Tan, Roelof Trip, Ying Yang, Dao-Yi Yu.
Application Number | 20100119696 12/620557 |
Document ID | / |
Family ID | 38596192 |
Filed Date | 2010-05-13 |
United States Patent
Application |
20100119696 |
Kind Code |
A1 |
Yu; Dao-Yi ; et al. |
May 13, 2010 |
MANUFACTURE OF AN ORGAN IMPLANT
Abstract
Methods, system and apparatus for relieving pressure in an organ
such as, but not limited to, the eye are disclosed. The method
includes implanting a bioabsorbable channel into the selected area
of the organ using a delivery apparatus.
Inventors: |
Yu; Dao-Yi; (City Beach,
AU) ; Anderson; Cory; (Alpharetta, GA) ; Trip;
Roelof; (Suwanee, GA) ; Yang; Ying; (Union
City, CA) ; Nguyen; Hoang Van; (San Jose, CA)
; Mantri; Surag; (Sunnyvale, CA) ; Su;
Er-Ning; (City Beach, AU) ; Cringle; Stephen;
(Shenton Park, AU) ; McCrea; James; (Burlingame,
CA) ; Mufson; Daniel; (Napa, CA) ; Tan;
Colin; (Sunnyvale, CA) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
18191 VON KARMAN AVE., SUITE 500
IRVINE
CA
92612-7108
US
|
Assignee: |
AqueSys, Inc.
Irvine
CA
|
Family ID: |
38596192 |
Appl. No.: |
12/620557 |
Filed: |
November 17, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11771805 |
Jun 29, 2007 |
|
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12620557 |
|
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60806402 |
Jun 30, 2006 |
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Current U.S.
Class: |
427/2.25 |
Current CPC
Class: |
A61F 9/00781 20130101;
A61M 27/008 20130101; A61L 31/045 20130101; A61F 9/0008
20130101 |
Class at
Publication: |
427/2.25 |
International
Class: |
B05D 3/02 20060101
B05D003/02 |
Claims
1. A method, of making an ocular implantable drainage channel,
comprising: providing a gelatin solution with a viscosity of from
approximately 200 cP to approximately 500 cP; coating an outer
surface of a support with gelatin from the gelatin solution, the
outer surface having an outer diameter of from approximately 50
microns to approximately 250 microns; curing the gelatin on the
support for at least one hour; treating the gelatin, after curing
the gelatin, with a cross-linking agent; curing the cross-linked
gelatin; and removing said cross-linked gelatin channel from the
support after curing the cross-linked gelatin.
2. The method of claim 1, wherein the gelatin solution is
maintained, during the coating, at a temperature of from
approximately 40.degree. to approximately 60.degree. C.
3. The method of claim 1, wherein said gelatin solution comprises
approximately 40%, by weight, of gelatin dissolved in water.
4. The method of claim 1, wherein said cylindrical support
comprises a stainless steel wire coated with a biocompatible
material.
5. The method of claim 1, wherein the coating comprises dipping
said support into a bath comprising the gelatin solution.
6. The method of claim 1, wherein the coating comprises spraying a
gelatin solution onto a rotating support.
7. The method of claim 1, wherein the gelatin solution viscosity is
from approximately 260 cP to approximately 410 cP.
8. The method of claim 1, wherein the gelatin is cured for from
approximately 10 hours to approximately 24 hours.
9. The method of claim 1, wherein the gelatin is cured at a
temperature of approximately 20.degree. C. to approximately
25.degree. C. and at a relative humidity of from approximately 30%
to approximately 40%.
10. The method of claim 1, wherein the cross-linking agent
comprises a solution of glutaraldehyde.
11. The method of claim 10, wherein the treating comprises dipping
the cured gelatin in a 25% glutaraldehyde solution.
12. The method of claim 11, wherein the glutaraldehyde solution has
a pH of approximately 7.35-7.44.
13. The method of claim 11, wherein the cured gelatin is dipped in
the glutaraldehyde solution for at least 4 hours.
14. The method of claim 11, wherein the cured gelatin is dipped in
the glutaraldehyde solution for between approximately 10 hours and
approximately 36 hours.
15. The method of claim 1, wherein the cross-linked gelatin is
cured for approximately 48 hours to approximately 96 hours.
16. The method of claim 1, wherein said cross-linking agent
comprises 1-ethyl-3-[e-(dimethylamino)propyl]carbodiimide.
17. A method, of making an ocular implantable drainage channel,
comprising: providing a gelatin solution with a viscosity of from
approximately 200 cP to approximately 500 cP; coating an outer
surface of a support with gelatin from the gelatin solution, the
outer surface having an outer diameter of from approximately 50
microns to approximately 250 microns; curing the gelatin on the
support for at least one hour; cross-linking the cured gelatin on
the support; curing the cross-linked gelatin; and removing said
cross-linked gelatin channel from the support after curing the
cross-linked gelatin.
18. The method of claim 17, wherein the gelatin solution is
maintained, during the coating, at a temperature of from
approximately 40.degree. to approximately 60.degree. C.
19. The method of claim 17, wherein said gelatin solution comprises
approximately 40%, by weight, of gelatin dissolved in water.
20. The method of claim 17, wherein the coating comprises dipping
said support into a bath comprising the gelatin solution.
21. The method of claim 17, wherein the coating comprises spraying
a gelatin solution onto a rotating support.
22. The method of claim 17, wherein the gelatin solution viscosity
is from approximately 260 cP to approximately 410 cP.
23. The method of claim 17, wherein the gelatin is cured at a
temperature of approximately 20.degree. C. to approximately
25.degree. C. and at a relative humidity of from approximately 30%
to approximately 40%.
24. The method of claim 17, wherein cross-linking the gelatin
comprises dipping the cured gelatin in a cross-linking agent.
25. The method of claim 17, wherein the treating comprises dipping
the cured gelatin in a 25% glutaraldehyde solution.
26. The method of claim 17, wherein cross-linking the gelatin
comprises exposing the gelatin to radiation.
27. The method of claim 26, wherein the radiation is selected from
the group consisting of gamma and electron beam radiation.
28. The method of claim 17, wherein the cross-linked gelatin is
cured for approximately 48 hours to approximately 96 hours.
29. A method, of making an implantable drainage channel,
comprising: providing a gelatin solution having a ratio of solid
gelatin to water of from approximately 10%-50% gelatin by weight to
50%-90% water by weight; coating an outer surface of a support with
gelatin from the gelatin solution, the outer surface having an
outer diameter of from approximately 50 microns to approximately
250 microns; curing the gelatin on the support for at least one
hour; and cross-linking the cured gelatin on the support.
30. The method of claim 29, wherein the gelatin solution comprises
a viscosity of from approximately 200 cP to approximately 500
cP.
31. The method of claim 29, wherein the gelatin solution is
maintained, during the coating, at a temperature of from
approximately 40.degree. to approximately 60.degree. C.
32. The method of claim 29, wherein said gelatin solution comprises
approximately 40%, by weight, of gelatin dissolved in water.
33. The method of claim 29, wherein the coating comprises dipping
said support into a bath comprising the gelatin solution.
34. The method of claim 29, wherein the coating comprises spraying
a gelatin solution onto a rotating support.
35. The method of claim 29, wherein the gelatin is cured at a
temperature of approximately 20.degree. C. to approximately
25.degree. C. and at a relative humidity of from approximately 30%
to approximately 40%.
36. The method of claim 29, wherein cross-linking the gelatin
comprises dipping the cured gelatin in a cross-linking agent.
37. The method of claim 29, wherein cross-linking the gelatin
comprises exposing the gelatin to radiation.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 11/771,805, filed on Jun. 29, 2007, which claims the benefit of
and priority to U.S. Provisional Patent Application No. 60/806,402,
filed Jun. 30, 2006, both of which are hereby incorporated by
reference in their entireties.
BACKGROUND
[0002] The present disclosure generally relates to methods, systems
and apparatus for relieving fluid pressure from an organ such as
(but not limited to) the eye. More particularly, the present
disclosure relates to methods and apparatus for treating glaucoma
by relieving the pressure within the eye.
[0003] Glaucoma is a disease of the eye that affects millions of
people. Glaucoma is associated with an increase in intraocular
pressure resulting either from a failure of the eye's drainage
system to adequately remove aqueous humor from the anterior chamber
of the eye or the overproduction of aqueous humor by the ciliary
body. The build-up of aqueous humor and resulting intraocular
pressure can cause irreversible damage to the optic nerve and the
retina, which may potentially lead to irreversible retinal damage
and blindness.
[0004] Presently, glaucoma can be treated in a number of different
ways, The most widely practiced treatment of glaucoma involves
delivery of drugs such as beta-blockers or prostaglandins to the
eye (typically in the form of eye drops) to either reduce the
production of aqueous humor or increase the flow of aqueous humor
from the anterior chamber of the eye. Glaucoma may also be treated
by surgical intervention such as trabeculectomy. Trabeculectomy or
similar surgical procedures involve creating conduits between the
anterior chamber and the various structures involved in aqueous
humor drainage such as Schlemm's canal, the sclera, and the
subconjunctival space in order to provide a pathway for the aqueous
humor to exit the anterior chamber.
[0005] While these methods of treating glaucoma have been generally
effective, they are not without their drawbacks. In the case of
medicinal treatments of the eye, patient compliance is an issue
because such treatments require regular (i.e., daily) intervention.
With respect to surgical procedures such as a trabeculectomy, such
procedures are very invasive and can cause irreversible changes to
the eye. For example, trabeculectomy results in the permanent
removal of a segment of the trabecular meshwork, inflammation and
scarring in the quadrant of the eye where the surgery was
performed, and the formation of a filtering bleb. Implantation of
shunts such as the Molteno, Barveldt, or Ahmed shunts induce
chronic foreign body reactions and the formation of a chronic
subconjunctival bleb. In addition, such surgical treatment of
glaucoma often requires long healing times and can result in
certain complications such as infection, scarring, hypotony or
cataracts.
[0006] More recently, less invasive surgical treatments have been
developed. These treatments do not require incision into the
conjunctiva of the eye. One example of a less invasive surgical
procedure is described in U.S. Pat. No. 6,544,249, the entire
disclosure of which is hereby incorporated by reference. U.S. Pat.
No. 6,544,249 discloses methods and apparatus for introducing a
small bioabsorbable and biocompatible drainage canal, referred to
therein as a microfistula tube into the portion of the eye that
extends from the anterior chamber to the sub-conjunctival space.
The procedure described in U.S. Pat. No. 6,544,249 does not require
incision of the conjunctiva. Instead, introduction of the
bioabsorbable microfistula tube is accomplished by an ab interno
approach--through the cornea of the eye to the desired location
(between the anterior chamber and the sub-conjunctival space.) U.S.
Pat. No. 6,544,249 also generally describes a delivery apparatus
for introducing and implanting the bioabsorbable microfistula
tube.
[0007] U.S. Pat. No. 6,007,511, the entire disclosure of which is
incorporated herein by reference, likewise discloses less invasive
methods and apparatus for treating glaucoma. As in the
above-referenced U.S. Pat. No. 6,544,249, a bioabsorbable drainage
tube is introduced into the area between the anterior chamber and
the sub-conjunctival space to allow drainage of the aqueous humor
from the anterior chamber of the eye. As in U.S. Pat. No.
6,544,249, incision of the conjunctiva is not required.
[0008] These new procedures for treating glaucoma offer the promise
of a long term cure of glaucoma without the shortcomings of
medicinal treatments and without the risks associated with the
known and presently practiced surgical procedures described above.
Accordingly, it would be desirable to provide improved methods,
systems, channels and delivery apparatus for treating glaucoma
specifically and for treating other conditions where drainage of
accumulated liquid is desired or required.
SUMMARY OF THE INVENTION
[0009] The present disclosure sets forth improved methods and
apparatus for carrying out channel implantation into an organ of
the body such as the eye. It will be appreciated that the methods
and apparatus described below may also find application in any
treatment of a body organ requiring controlled drainage of a fluid
from the organ. Nonetheless, the methods and apparatus for
performing such treatment will be described relative to the eye
and, more particularly, in the context of treating glaucoma.
[0010] The present disclosure relates to an implantable,
microfistula channel. The channel has a bioabsorbable body defining
an interior flow path. The channel body is made of cross-linked
bioabsorbable material such as gelatin and has an expandable outer
diameter. The flow path has a diameter of between approximately 50
and 250 microns (.mu.m).
[0011] The present disclosure also relates to a method of making an
implantable channel. The method includes providing a source of a
bio-compatible gelatin solution and providing a generally
cylindrical solid support. The support has a diameter of
approximately 50 to 250 microns. The method includes contacting the
outer surface of the support with the gelatin for a period of time
sufficient to coat the support outer surface. A hollow gelatin tube
is thus formed on the support. The formed hollow gelatin channel
may be dried (cured) for a selected period of time and the formed
gelatin tube may be subjected to a cross-linking treatment. The
formed and cross-linked gelatin tube is removed from the
support.
[0012] The present disclosure also relates to an implantation
apparatus for implanting a channel into an organ of a subject. The
apparatus includes a reusuable portion that includes an apparatus
housing. The housing has an open distal end, a proximal end and an
interior chamber. The apparatus includes an arm subassembly within
the housing that includes one or more movable arms adapted to
engage a disposable needle assembly. The apparatus further includes
one or more drivers coupled to said one or more moveable arms of
the arm sub-assembly.
[0013] The present disclosure further relates to systems for
implanting a channel into an organ of a subject. The system
includes a reusable portion adapted to receive a needle assembly
and a disposable portion that includes a needle assembly. The
needle assembly has a hollow needle terminating in a sharpened tip
and a guidewire and a plunger disposed within the needle. The
system includes a microprocessor-based controller including
pre-programmed instructions for selective movement of at least the
guidewire and the plunger.
[0014] The present disclosure further relates to methods of
implanting a bioabsorbable channel into an organ of a subject. In
the methods described herein, an implantation apparatus including a
hollow needle having a pointed distal end, a bioabsorbable channel
within the needle assembly and a plunger proximally located
relative to the channel is provided. The method includes the steps
of introducing the pointed tip of the needle end assembly into the
organ of a subject, advancing the needle to the desired area of
implantation and actuating the plunger to advance the channel to
the desired area of implantation. The method further includes
removing the needle from the organ.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1, depicts, in general, a method for implanting a
channel, showing in cross section, the distal end of an
implantation apparatus;
[0016] FIG. 2 is an enlarged, schematic view of the distal end of
one embodiment of an implantation apparatus described herein;
[0017] FIG. 3 is a perspective view of one embodiment of a handheld
implantation apparatus with the door opened and a needle assembly
installed therein;
[0018] FIG. 4 is a top view of the apparatus of FIG. 3 with front
door removed;
[0019] FIG. 5 is an exploded view of the system for implanting a
channel including the apparatus FIG. 3;
[0020] FIG. 6 is a perspective view of the distal end of the
apparatus of FIG. 3 with the needle assembly separated
therefrom;
[0021] FIG. 7 is an enlarged perspective view of the needle
assembly of FIG. 6;
[0022] FIG. 8 is an exploded view of the needle assembly of FIG.
7;
[0023] FIG. 9(a)-(f) are schematic views of the implantation
apparatus of FIG. 3 showing the plunger, guidewire and needle arms
in different positions during the positioning and/or implantation
steps as they correspond to the positions of the plunger,
guidewire, needle and channel within the eye;
[0024] FIG. 10 is a perspective view of another embodiment of an
implantation apparatus with the needle assembly installed
therein;
[0025] FIG. 11 is a perspective view of the implantation apparatus
of FIG. 10 and the disposable needle assembly in its extended state
and separated therefrom;
[0026] FIG. 12 is a side view of another embodiment of a handheld
and manually operated implantation apparatus;
[0027] FIG. 13 is a side view of still another embodiment of a
handheld and manually operated implantation apparatus;
[0028] FIG. 14 is an enlarged side view of the needle assembly of
the apparatus of FIG. 13;
[0029] FIG. 15 is a perspective view of a syringe type, manually
operated, handheld implantation apparatus;
[0030] FIG. 16 is a schematic illustration of a method and
apparatus for making a gelatin microfistula channel in the form of
a tube;
[0031] FIG. 17 is a schematic illustration an alternative
embodiment of an apparatus for making a gelatin microfistula
tube;
[0032] FIG. 18 is a perspective view of an apparatus for making a
plurality of microfistula gelatin tubes.
[0033] FIG. 19 is a front view of a graduated needle inserted into
the eye of a patient;
[0034] FIG. 20 is a front view showing a transpupil channel
insertion and placement;
[0035] FIG. 21 is a schematic view showing an ipsilateral
tangential channel insertion and placement;
[0036] FIG. 22(a)-(d) depicts a series of steps showing an
ipsilateral normal channel insertion and placement using a U-shaped
or otherwise arcuate needle;
[0037] FIG. 23 is a perspective view of a U-shaped needle of the
type shown in the method of insertion and placement shown in FIGS.
22(a)-(d);
[0038] FIG. 24 is a front view of the U-shaped needle of FIG.
23;
[0039] FIG. 25 is a side view of a needle having a bend at its
distal end portion including the guidewire and channel inserted
therein;
[0040] FIG. 26 is a cross-sectional view of the needle, guidewire,
plunger and channel of the needle distal end portion of FIG.
25;
[0041] FIG. 27 is a side view of the needle, the plunger or
guidewire of FIG. 25, wherein a portion of the plunger or guidewire
facilitates bending of the same;
[0042] FIG. 28 is a perspective view of a cylindrical channel
including a tapered end;
[0043] FIG. 29 is a perspective view of a cylindrical channel
including retaining tabs for limiting migration of the channel;
[0044] FIG. 30 is an end view of the tabbed channel of FIG. 29;
[0045] FIG. 31 is a perspective view of a cylindrical channel
including centrally located barbs to limit migration of the
implanted channel;
[0046] FIG. 32 is a perspective view of a cylindrical channel
including barbs located at one of the implanted channel to limit
migration thereof;
[0047] FIG. 33 shows the tabbed channel of FIGS. 29-30 inserted
within the eye of the patient.
DETAILED DESCRIPTION OF THE INVENTION
[0048] Methods and apparatus for delivering and implanting
bioabsorbable tubes or shunts are generally disclosed in U.S. Pat.
Nos. 6,544,249 and 6,007,511, both of which have been previously
incorporated by reference in their entireties. As set forth
therein, and also with reference to FIG. 1, an implantation
apparatus 10 is used to deliver and implant a small micro-sized
bioabsorbable tube i.e., the microfistula tube 26, to an area
between the anterior chamber 16 and the sub-conjunctival space 18
of the eye 12. The implanted microfistula tube 26 provides a
channel that continuously drains aqueous humor from anterior
chamber 16 at a desired rate. Microfistula tube 26 remains
implanted in the eye, and eventually dissolves.
[0049] FIG. 1 illustrates the distal (i.e., "working end") end of
the apparatus 10 (including the microfistula tube 26) as it
approaches the eye 12 as described in U.S. Pat. No. 6,544,249.
Unlike current trabeculectomy procedures, in accordance with the
method shown in FIG. 1, needle 22 housing microfistula tube 26
approaches and enters the eye through cornea 19 (ab interno) and
not through the conjunctiva 14 (ab externo). This prevents damage
to the conjunctiva, improves healing time and reduces the risk of
complications that may result from other surgical techniques of the
prior art (e.g., trabeculectomy). As further shown and described in
U.S. Pat. No. 6,544,249 and in FIG. 1, hollow needle 20 is
introduced through the cornea 19 and is advanced across the
anterior chamber 16 (as depicted by the broken line) in what is
sometimes referred to as a transpupil implant insertion. Channel 26
is eventually implanted in the area spanning the sclera 21,
anterior chamber 16 and the sub-conjunctival space 18 (see also
FIG. 8 of U.S. Pat. No. 6,544,249).
[0050] The methods, systems, apparatus and channels described
herein likewise utilize a hollow needle and a bioabsorbable channel
delivered by the needle ab interno through the cornea 19 or the
surgical limbus 17. As used herein, the term "channel" includes
hollow microfistula tubes similar to the type generally described
in U.S. Pat. No. 6,544,249 as well as other structures that include
one or more flow paths therethrough.
[0051] Turning now to a discussion of the methods, systems,
apparatus and channels that embody the present invention, as
generally shown in FIG. 2, the working end of implantation
apparatus is provided as a needle assembly 20 that includes a
hollow needle 22 defining an inner chamber 23 and terminating in a
sharpened tip. Placed within inner chamber 23 of the hollow needle
22 is a cylindrical inner tube or plunger 32 that is coaxial with
needle 22. In the loaded and ready to use condition, channel 26 is
also placed or otherwise disposed within the hollow chamber 23 of
needle 22 and is distally located relative to plunger 32. Both
channel 26 and plunger 32 may be placed over and supported by
optional guidewire 28. As described in U.S. Pat. No. 6,544,249 and
in this disclosure, through relative movement of needle 22, plunger
32, guidewire 28, and channel 26 can be implanted into eye 12. As
noted above, guidewire 28 is optional and may be omitted where
placement and advancement of channel 26 does not require one.
[0052] As will be described in greater detail below, channel 26 may
be delivered to and implanted within the desired location of the
eye in any one of several different ways. The method of
implantation (and system) may be fully automated, partially
automated (and, thus, partially manual) or completely manual. For
example, in a fully automated procedure, channel 26 may be
delivered by robotic implantation whereby a surgeon controls the
advancement of needle 22, plunger 32, optional guidewire 28 and, as
a result, channel 26 by remotely controlling a robot. In such fully
automated, remotely controlled procedures, the surgeon's hands
typically do not contact implantation apparatus 10 during the
surgical procedure.
[0053] Alternatively, channel 26 may be delivered to the desired
area of the eye with a "handheld" implantation apparatus,
embodiments of which are shown in FIGS. 2-15 and described below.
In one example of a handheld implantation apparatus, discussed in
more detail below, movement of the channel 26, needle 22, and
plunger 32 and optional guidewire 28 may be controlled remotely by
an operator using a microprocessor-based device i.e., "controller,"
while implantation apparatus 10 is physically held by the surgeon.
Insertion of the needle into the eye as well as certain
repositioning or adjusting steps may be performed manually by the
surgeon.
[0054] In the case of fully manual apparatus and methods, which are
also discussed below and shown in FIGS. 12-15, all of the
positioning, repositioning, adjusting and implantation steps are
performed manually by the surgeon.
[0055] One example of an implantation apparatus 10 and system
embodying the present invention is shown in FIGS. 3-9. Although
apparatus 10 shown in FIGS. 3-9 is preferably a handheld type
implantation apparatus where relative movement of the needle,
optional guidewire and plunger is accomplished automatically by
pre-programmed instructions in a microprocessor-based controller
and at least some of the steps may be manually performed by the
surgeon, apparatus 10 can also be used in a fully automated
environment. In any event, implantation apparatus 10 shown in FIG.
3 includes a reusable portion 30 and a disposable portion embodied
in needle assembly 20. As will be discussed in greater detail
below, needle assembly 20 is separately provided and is received by
arm sub-assembly 55 of implantation apparatus 30.
[0056] As shown in FIG. 3, implantation apparatus 10 includes a
generally cylindrical body or housing 34, although as will be
appreciated from other embodiments disclosed herein, the body shape
of housing 34 is not critical. However, if apparatus 10 is to be
held by the surgeon (i.e., a handheld apparatus) the shape of
housing 34 should be such that is ergonomical, allowing for
comfortable grasping by the surgeon. Housing 34 is closed at its
proximal end by end cap 38 and has an opening 39 at its distal end
through which at least a portion of needle assembly 20 extends.
Door 36 provides access to the interior of housing 34 allowing for
easy insertion and removal of needle assembly 20. Locking means
such as slide lock 37 may be provided to secure door 36 to (and
release door 36 from) housing 34. Door 36 may be secured to housing
34 by a hinge 41 allowing the door to swing open when it is
unlocked. In an alternative embodiment, door 36 may be slidably
attached to housing 34 and access to the interior of housing 34 may
be achieved by sliding door 36 toward the proximal end of the
housing 34. Of course, it will be appreciated that other ways of
providing access to the interior of the implantation apparatus 10
are also possible.
[0057] Housing 34 and door 36 may be made of any material that is
suitable for use in medical devices. For example, housing 34 may be
made of a lightweight aluminum or, more preferably, a biocompatible
plastic material. Examples of such suitable plastic materials
include polycarbonate and other polymeric resins such as
Delrin.RTM. and Ultem.RTM.. Similarly, door 36 may be made of a
plastic material such as the above-described materials including
polymers and polymer resins such as polycarbonate, Delrin.RTM. and
Ultem.RTM.. In a preferred embodiment, door may be substantially
translucent or transparent.
[0058] Re-usable portion 30 of implantation apparatus 10 houses the
components required to effect movement of the needle assembly 20
components during the implantation procedure. As shown in FIGS.
3-6, implantation apparatus 10 houses a plurality of moveable arms,
collectively referred to herein as the arm sub-assembly 55, which
is adapted to receive needle assembly 20. Arms 54, 58 and 62 are
axially moveable between the proximal and distal ends of apparatus
10 and are coupled to lead screws 52(a)-(c) at their distal ends
which, in turn, are coupled to one or more drivers 44, 46, 48. In
the embodiment shown in FIGS. 3-6, drivers are preferably a
plurality of gear or stepper motors 44, 46 and 48. Alternatively,
arms may be driven pneumatically or otherwise.
[0059] With respect to the embodiments of FIGS. 3-6, motors 44, 46
and 48 are housed near the proximal end of implantation apparatus
10. Motors 44, 46 and 48 may be stacked or bundled in parallel in
the manner shown in FIG. 5 and held in place by front motor mount
50 and rear motor mount 40.
[0060] As indicated above, each of the motors 44, 46 and 48 (or
other drivers) is coupled to one of the lead screws 52(a)-(c),
which, in turn, are coupled to movable arms 54, 58 and 62 of arm
sub-assembly 55. For example, with specific reference to the
embodiment of FIGS. 3-6, lead screw 50(a) is coupled to guidewire
arm 54; lead screw 50(b) is coupled to plunger arm 58; and lead
screw 50(c) is coupled to needle arm 62. Motors 44, 46 and 48 may
be selectively and independently activated by switches on the
apparatus 10 itself or as schematically shown in FIG. 5 as
described, may be coupled to a remote controller 8 of the system.
In one embodiment, apparatus 10 includes printed circuit board 7
which establishes an electrical connection between motors 44, 46
and 48 and controller 8. Controller 8 may include a control box
that supplies power and pre-programmed positioning instructions to
the implantation apparatus 30 generally and motors 44, 46 and 48,
specifically. Movements of the various arms 54, 58 and 62 can be
initiated by the surgeon via a foot switch or other type of remote
control 6.
[0061] As shown in the Figures, arms 54, 58 and 62 are preferably
of varying axial lengths. Each of the arms 54, 58 and 62 includes a
slot for receiving a portion of the needle assembly 20 (described
below.) Thus, guidewire arm 54 includes a guidewire hub slot 57;
plunger arm 58 includes a plunger hub slot 59 and needle arm 62
includes a needle hub slot 63.
[0062] In a preferred embodiment, each of the arms 54, 58 and 62
includes at its distal and/or proximal ends a portion having an
enlarged cross-section. The distal "blocks" 54(a), 58(a) and 62(a)
provide abutment surfaces which limit axial movement of the
respective arms. As will be seen from the discussion of the
implantation method, the distal blocks which also define slots 59,
62 and 63 limit movement of the particular arms, thereby ensuring
that the guidewire, plunger and channel 26 do not move beyond a
pre-determined distance. Similarly, wall 65 of housing 34 limits
movement of needle arm 62, likewise ensuring that the needle does
not penetrate the eye beyond a desired distance. Proximal blocks
58(a), 58(b) and 58(c) (not shown) likewise provide an abutment
surfaces for contacting fixed collars 53 on lead screws 52(a)-(c).
Contact between the surfaces of blocks 58(a), 58(b) and 58(c) and
respective collars 53 provides an indication that arms of arm
subassembly 55 are in their rearmost or "hard stop" position,
discussed below. Blocks 58(a)-(c) also include internal threaded
nuts through which lead screws 50(a)-(c) travel.
[0063] As further seen in FIGS. 3-6, implantation apparatus 10
includes a guide block 66 attached to needle arm 62. Guide block 66
defines two partially enclosed apertures for slidably retaining
guidewire arm 54 and plunger arm 58. Guide block 66 prevents
rotation or other undesired dislocation of guidewire arm 54 and
plunger arm 58 and maintains these components in an axially aligned
orientation. Guide block 66 also serves as a stop that limits
movement of arms 54 and 58.
[0064] As noted above, arm sub-assembly 55 is adapted to receive
needle assembly 20. Needle assembly, shown in FIGS. 7 and 8 is
itself made of a plurality of separate, and co-axially assembled
parts. Co-axial assembly of these constituent parts allows for
relative axial movement of optional guidewire 28, needle 20 and
plunger 32. As shown in FIGS. 7 and 8, in one embodiment, needle
assembly includes a guidewire hub 72. In the embodiment shown,
guidewire hub 72 includes a distal cylinder 82 and a proximal block
84. Guidewire 28 extends from the cylinder 82 and is received
within plunger hub 68 which likewise includes a distal hollow
cylinder and proximal block 90. Plunger tube 32 extends from
plunger cylinder 88 and when brought together with guidewire hub 72
surrounds guidewire 86 along most of its length. Both guidewire 28
and plunger tube 92 are then received by needle hub 96. A hollow
needle 22 attached to needle mount 23 is mounted on needle hub 96.
Hollow needle 22 has an inner diameter sufficient to receive the
assembled co-axial guidewire 86 and plunger 92. Of course, it will
be appreciated that in certain embodiments, a guidewire may not be
required and that needle assembly 20 may include a plunger and
needle only.
[0065] As best shown in FIG. 6, needle assembly 20 is adapted for
placement within arm assembly 55. More specifically, guidewire
block 84, plunger block 90 and needle block 94 of needle assembly
20 are received by the slots 57, 59 and 63, respectively, of arm
sub-assembly 55. Each of blocks 84, 90 and 94 may include an
upstanding pin 85, 91 and 95 (respectively). Pins 85, 91 and 95 are
of a height sufficient so as to almost contact the inner surface of
door 36 (when closed). Providing pins of sufficient height keeps
needle assembly from becoming dislodged from sub-assembly 55 in the
event that apparatus 10 is rotated by the surgeon. As shown in
FIGS. 7 and 8, hollow needle 22 is preferably protected prior to
use by removable needle cap 80.
[0066] Another embodiment of a handheld implantation apparatus is
shown in FIGS. 10-11. As in the embodiment described above,
hand-held implantation apparatus 10 of FIG. 10 includes a reusable
portion 30 that includes handle 180, movable block 182 and slider
assembly 214. As with the embodiment of FIGS. 3-9 above, needle
assembly 20, itself includes several different components that can
be preassembled (as shown in FIG. 10) and are axially movable
relative to one another. For example, in the embodiment shown in
FIG. 10, needle assembly 20 includes plunger 32, needle adapter 184
and guidewire holder 24. Plunger 32 has a hollow cylindrical body
which has an open distal end and an open proximal end. Open
proximal end of plunger 32 receives guidewire 28 and guidewire
holder 24.
[0067] As further shown in FIG. 10, distal end of plunger 32 is
received by hollow needle adapter 184 and needle adapter 184
receives disposable needle 22. Needle 22 includes a distal piercing
end and a hub 188 which is fitted over needle adapter 184. Once
assembled, guidewire extends from guidewire holder 24 through
plunger 32, through needle adapter 184 and needle 22. In the
embodiments of FIG. 10, channel 26 is typically placed on guidewire
28 near the distal end thereof within hollow needle 22.
[0068] Needle assembly 20 is mounted onto reusable handheld portion
30. More particularly, as shown in FIG. 3, needle assembly is
fitted into slots 192, 194 and 196 of implantation apparatus 30.
For example, collar 198 of guidewire holder 24 is received within
slot 192, collar 200 of intermediate tube 32 is positioned within
slot 194, and collar 202 of needle adapter 34 is received within
slot 196.
[0069] Implantation apparatus 10 includes a handle 180. Handle 180
preferably includes groove 206 along the side wall for easy
gripping by the surgeon. As shown in FIGS. 10 and 11, handle 204
supports movable slider block 182. Block 182 includes a slide 210
that fits within a central slot of handle 180. During use of
implantation apparatus 10, block 182 may move axially within the
slot of handle 180. Movable slider block 182 may also include a
slot 212 (see FIG. 10) which receives plunger block assembly 214.
As shown in the figures, plunger block 214 may be slidable within
block 182. Plunger block assembly 214 includes forwardly extending
arms 216 which defines at its distal end a slot 192 (in which
collar 25 of guidewire holder 24 is received). Plunger block
assembly also includes guidewire slider block 218 that is movable
within slot 219 defined by arms 216. Guidewire slider block 218 is
coupled to motor 230 (discussed below) by screw 220.
[0070] Reusable portion 30 of handheld implantation apparatus 10
generally depicted in FIGS. 10 and 11 may further include drivers
for selectively actuating movement of the component parts of needle
assembly 20, such as needle 22, guidewire 28, plunger 32, and
channel 26. As in the embodiment of FIGS. 3-9, in the embodiment of
FIGS. 10 and 11, the drivers for selectively moving these and other
components may be one or more motors, such as gear or stepper
motors. Motors 230 may be selectively activated to move the desired
component of apparatus 10. In one non-limiting example shown in
FIGS. 10 and 11, a plurality of stepper motors 230(a), (b) and (c)
are carried by handheld implantation apparatus. Motors 230(a)-(c)
may be selectively activated by switches on the apparatus itself,
remote hand-operated switches, a foot-operated controller and/or an
automatically controlled via a preprogrammed controller (i.e.,
computer) 8.
[0071] Regardless of the means of control, in the example shown in
FIGS. 10 and 11, motor 230(a) causes movement of guidewire slider
block 218. Movement of guidewire slider block 218 which holds
collar 25 of guidewire holder 24 results in selective back and
forth movement of guidewire 28. Motor 230(b) moves arm 216 within
slot 212 which holds collar 200 of plunger 32, allowing for back
and forth movement of plunger 32. Finally, motor 230(c) drives
block 182 including the entire needle assembly 20 further including
block 214 and its associated components.
[0072] Of course, as described in relation to the embodiment of
FIGS. 10-11, means for advancing or moving the operative components
of handheld implantation apparatus 30 of FIGS. 11-12 need not be
electrical and/or motor driven. Other embodiments of a handheld
apparatus 10 that include other ways for actuating movement of the
individual components may also be employed. For example, as shown
in FIGS. 12-15, in alternative embodiments of a handheld
implantation apparatus, the apparatus 10 may include mechanical
means for selectively advancing the component parts of the needle
assembly and the handheld implantation apparatus.
[0073] Turning to FIG. 12, implantation apparatus 110 includes a
reusable handheld portion 112 that receives a disposable needle
assembly 114. Implantation apparatus 110 includes a thumbwheel 116
placed on and movable along threaded screw 118. Attached to
thumbwheel 116 is a syringe body 120. Distal end of syringe 120
receives needle assembly 122. Implantation apparatus 110 includes a
conduit that extends through the handle 113 and is adapted for
receiving guidewire 28.
[0074] Placement of channel 26 onto guidewire 28 may be achieved by
turning thumbwheel 116 in a first direction to retract needle
assembly 122 and hollow needle 124, thereby revealing the distal
end of guidewire 28 and plunger tube 32. At that point, channel 26
is placed (typically manually) on guidewire 28 so that the proximal
end thereof (the end opposite the leading end of channel 26) of
channel comes into contact with the distal end of plunger 32.
Thumbwheel 116 is then turned in an opposite direction to the first
direction to slide needle 124 over plunger tube 32 and channel
26.
[0075] Channel 26 is now ready for implantation. During the
implantation process, needle 124 is inserted into the eye and, more
specifically, the cornea 19 or surgical limbus 17 of the eye in the
manner described above and in U.S. Pat. No. 6,544,249. Needle 124
is advanced across anterior chamber 16 and into the
sub-conjunctival space 18, stopping short of the conjunctiva 14.
Thumbwheel 116 is then rotated again in the first direction to
retract needle 124 and thereby expose channel 26. Once in place,
guidewire is retracted, releasing microfistula 26 from guidewire
28. Retraction of guidewire may be achieved manually by a simple
pulling of guidewire 28 at the proximal end of apparatus 110. Once
channel 26 is in its final position, needle 124 is removed.
[0076] FIGS. 13 and 14 illustrate another embodiment of a handheld
implantation apparatus 130 that likewise utilizes mechanical means
for advancing and/or selectively moving the component parts of the
needle assembly and/or apparatus 130. As in the embodiment of FIG.
12, handheld implantation apparatus relies on mechanically driving
the component parts. As shown in FIG. 13, implantation apparatus
130 includes handle portion 132 with a needle assembly 134 attached
to the distal end of body 132. A thumbwheel 136 is rotatable and
coupled to an internal screw (not shown). Internal screw is
attached to arms 138 which grasp flange 140 of needle assembly 134,
such that turning of thumbscrew 136 effects axial movement of
needle assembly 134.
[0077] In contrast to the embodiment of FIG. 12, implantation
apparatus 130 may further include additional means for controlling
movement of other components of the implantation apparatus. For
example, in the embodiment of FIG. 13, a second thumbwheel 142 is
mechanically coupled to guidewire 28. A rotation of thumbwheel 142
allows for retraction of guidewire 28 after implantation of channel
28.
[0078] FIG. 14 provides an enlarged view of needle assembly 134
shown in FIG. 13. As seen in FIG. 14, an assembly retainer 146 is
provided. Assembly retainer 146 is affixed to the needle assembly
134 during shipment to prevent movement of guidewire 28 and control
tube. Retainer is removed prior to insertion of the needle assembly
134 onto the handle 132 of apparatus 130.
[0079] FIG. 15 shows another embodiment of an implantation
apparatus. The implantation apparatus 150 of FIG. 8 includes a
handle 152, a movable or slidable syringe portion 154 and a trigger
156 for actuating movement of slidable syringe 124. Implantation
apparatus 150 further includes an attachable needle assembly 158
(with needle 22) at the distal end of syringe 154. As shown in FIG.
15, guidewire 28 extends through implantation apparatus 150 in
similar fashion to the apparatus of FIG. 12. Guidewire 28 extends
through barrel 154 and carries a tube 32 near its distal end.
Barrel 154 is preferably filled with gas (e.g., air, CO.sub.2,
nitrogen or liquid (e.g., water, trypan blue, saline or a
viscoelastic solution).
[0080] For placement of channel 26 onto guidewire 28, trigger 156
is pulled, resulting in rearward movement of syringe 154 and needle
22. Rearward movement of needle 22 exposes guidewire 28 and allows
for placement of channel 26 onto guidewire. Release of the trigger
158 advances needle 22 to cover guidewire 28 and channel 26. As in
the previous embodiments, needle 22 pierces cornea 19 or surgical
limbus 17, and is advanced through anterior chamber 16 to the
desired location of the eye (i.e. the area between the
sub-conjunctival space 18 and the anterior chamber). Trigger 156 is
once again pulled to move needle assembly 158 in a rearward
direction thereby exposing channel 26 carried by guidewire 28. Once
the surgeon has determined that the channel 26 is in the desired
location, guidewire 28 is retracted, thereby releasing channel 26.
As shown in FIG. 15, retraction of guidewire 28 may be performed
manually, as in the embodiment of FIG. 12, by simply pulling
guidewire 28. Alternatively, mechanical means for moving guidewire,
as in the examples of FIGS. 12 and 13, may also be provided.
[0081] Although selective movement of guidewire 28, needle
assembly, plunger 32 or guidewire holder 24 with the channel 26
using electrical, mechanical or even some manual means have been
described, other means for actuating movement of these components
may also be used instead of or in addition to such means. For
example, movement of the various component parts may be achieved by
pneumatic control or fluidic control.
[0082] The method of implanting channel 26 using implantation
apparatus will now be described. The method will be described with
particular reference to the embodiment of FIGS. 3-9, although many
of the steps described may also be employed using other embodiments
of the implantation apparatus. In addition, depending on the type
of apparatus and type of channel used, there may be variations to
some of the method steps. For example, in some embodiments, a
guidewire may be omitted. In addition, the advancement and
retraction steps of the parts of needle assembly may be continuous
or incremental. Regardless of the apparatus used, the sequence of
steps, distances traveled and continuous or incremental movement,
the ultimate location of channel 26 is substantially the same using
any of the methods, systems and apparatus described herein.
[0083] At the outset, it will be appreciated that the implantation
of channel 26 requires precise placement of the channel 26 in the
correct location within the eye. Moreover, it will also be
appreciated that the distances traveled by the channel 26, plunger
32, guidewire 28 and needle 22 are typically measured in
millimeters. Such precision may be difficult for even the most
skilled surgeon to achieve by manual manipulation (due to natural
hand tremors in humans). Accordingly, in embodiments other than the
manual hand-held implanters in FIGS. 12-15, many of the actual
implantation steps are preferably carried out under the automatic
control of an external, preprogrammed controller 8. While the
initial eye entry steps and some repositioning steps may be
performed manually by the surgeon, steps related to the release and
location of channel 26 may be automatically controlled.
[0084] In a first step, preferably performed during factory
assembly, channel 26 is loaded into needle assembly 20. During
loading, the distal tip of guidewire preferably extends slightly
beyond the beveled tip of hollow needle 22. Channel 26 may be
manually placed on guidewire 28 until proximal end of channel 26
contacts the distal end of plunger 32. Guidewire 28, with channel
26 placed thereon is then retracted into hollow needle 22.
[0085] Prior to loading needle assembly 20 into apparatus 30,
pre-positioning of arm-subassembly may be desired or required.
Thus, in a first step, all motors are activated to retract
guidewire arm 54, plunger arm 58 and needle arm 62 to a proximal
most position such that the proximal end surfaces of the arms abut
against collars 53. This "hard stop" position is shown
schematically in FIG. 9a. The operator may then prepare
implantation apparatus 30 for loading of needle assembly by
activating each motor and advancing each arm assembly 55 to a
"home" position and shown in FIG. 9(b). As will be seen in FIG.
9(b) movement of needle arm 62 is restricted by wall 70 of
apparatus 30. With the motors properly aligned in the "home"
position, needle assembly is installed by inserting guidewire hub
block 86 into guidewire hub slot 57; plunger hub block 90 into
plunger hub slot 59 and needle hub block into slot 63. With needle
assembly 20 properly installed, the surgeon may begin the procedure
by inserting the end distal tip of hollow needle 22 into the eye.
As shown in FIG. 1 and as previously described, the surgeon inserts
the hollow needle 22 into the anterior chamber via the cornea or
surgical limbus of the eye and advances it either manually (or
under automatic control) to a location short of the final
implantation site. Alternatively, the surgeon may first make an
incision in the eye and insert needle 22 through the incision. Once
the needle 22 has been properly inserted and placed, the program
may be activated to commence automatic implantation of channel 26.
In a first implantation step, simultaneously motors) 44 and 46 are
activated to advance guidewire arm 54 and plunger are 58 as shown
in FIG. 9(c) which thereby advances channel 26 forward into the
subconjunctival space of the eye, as generally depicted in FIG.
9(c). For example, in one embodiment, plunger 32 and guidewire 28
are advanced approximately a total of 2 millimeters. Preferably,
the rate of placement of channel is carefully controlled because it
allows the channel to absorb fluid from the surrounding tissue
thereby causing it to swell and to provide better anchoring in the
tissue. Rapid advancement or placement of microfistula channel 26
may not allow tube 26 to adequately swell which can possibly result
in unwanted migration of channel 26 after implantation. In one
embodiment, the rate of placement may be between approximately
0.25-0.65 mm/sec.
[0086] After the advancement of the plunger and guidewire described
above, motor 48 is activated and needle arm 62 is moved in a
rearward direction such that needle 22 is withdrawn from its
position shown in FIG. 9(c) to the position shown in FIG. 9(d).
Withdrawal of needle 22 should preferably expose the entire length
of channel 26, and, in addition, the distal end of the plunger,
thereby allowing the surgeon to visualize the final position of the
proximal edge of the channel. In one embodiment, the distance that
hollow needle 22 is withdrawn is approximately 4.2 millimeters. At
this point, the program prompts (e.g., audibly) the surgeon to
visually view the location of channel 26 and determine if it is
correctly placed. The surgeon can manually make any adjustments to
a desired position by moving the implanter forward or backward. The
automatic system may be programmed to allow the surgeon sufficient
time to make any further manual adjustments and may require the
surgeon to press the foot or other switch or otherwise effect
movement to continue delivery of the channel. After a selected
period of time, the automated program preferably resumes control of
implantation procedure by activating motor guidewire motor 44, to
retract guidewire arm 54 and thus withdraw guidewire 28 as shown in
FIG. 9(e). Removal of the guidewire preferably occurs in one single
step as shown in FIG. 9(e). Finally, the system will then
preferably alert the surgeon that the procedure is now complete and
the needle 22 may be withdrawn (manually or automatically) from the
eye as shown in FIG. 9(f).
[0087] From the preceding discussion, it will be appreciated that
bioabsorbable microfistula channel is implanted by directing the
needle across the anterior chamber, entering the trabecular
meshwork (preferably between Schwalbe's Line and the Scleral spur),
and directing the needle through the sclera until the distal tip of
the needle is visible in the subconjunctival space. The length of
the channel through the sclera should be approximately 2-4 mm. Once
the surgeon has placed the needle in this location, he may actuate
the implanter to begin the release steps. The channel is released
and the needle is withdrawn such that approximately 1-2 mm of the
channel resides in the sub conjunctival space, approximately 2-4 mm
resides in the scleral channel, and approximately 1-2 mm resides in
the anterior chamber. Once the channel is released, the surgeon
removes apparatus needle 20.
[0088] Proper positioning of the bioabsorbable channel 26 should be
carefully controlled for at least the following reasons. If the
surgical procedure results in the formation of a bleb, the more
posterior the bleb is located, the fewer complications can be
expected. Additionally, the bleb interferes less with eyelid motion
and is generally more comfortable for the patient. Second, a longer
scleral channel provides more surface contact between the channel
and the tissue providing better anchoring. Third, the location of
the channel may play a role in stimulating the formation of active
drainage structures such as veins or lymph vessels. Finally, the
location of the channel should be such so as to avoid other
anatomical structures such as the ciliary body, iris, and cornea.
Trauma to these structures could cause bleeding and other
complications for the patient. Additionally, if the bleb is shallow
in height and diffuse in surface area, it provides better drainage
and less mechanical interference with the patient's eye. Tall,
anteriorly located blebs are more susceptible to complications such
as conjunctival erosions or blebitis which require further
intervention by the surgeon.
[0089] The ab interno approach provides better placement than the
ab externo approach because it provides the surgeon better
visibility for entering the eye. If directing the needle from an ab
externo approach, it is often very difficult for the surgeon to
direct the needle to the trabecular meshwork (between Schwalbe's
line and the scleral spur) without damaging the cornea, iris, or
ciliary body.
[0090] In an alternative method of implantation, it is possible to
direct the needle from the trabecular meshwork into the
suprachoroidal space (instead of the subconjunctival space) and
provide pressure relief by connecting these two spaces. The
suprachoroidal space also called supracilliary space has been shown
to be at a pressure of a few mmHg below the pressure in the
anterior chamber.
[0091] Common to all of the embodiments of handheld implantation
apparatus are a needle assembly including a hollow needle. In a
preferred embodiment, hollow needle 22 may be any needle suitable
for use in medical procedures. As such, needle 22 is made of a hard
and rigid material such as stainless steel with a beveled sharpened
distal tip. Needle 22 is bonded, welded, overmolded, or otherwise
attached to the needle mount 23 and/or hub that is adapted for
placement onto the distal end of a needle assembly. The needle 22
is disposable and intended for one time use.
[0092] Hollow needle 22 and indeed, the entire needle assembly may
be sterilized by known sterilization techniques such as
autoclaving, ethelyne oxide, plasma, electron beam, or gamma
radiation sterilization. In a preferred embodiment, needle 22 is a
25 gauge thin walled needle that is commercially available from
Terumo Medical Corp., Elkton, Md. 21921. The inside diameter of
hollow needle 22 must be sufficient to accommodate optional
guidewire 28, channel 26 and plunger tube 32, with an inner
diameter of 200-400 .mu.M being preferred. The usable length of
needle 22 may be anywhere between 20-30 mm, although a length of
approximately 22 mm is typical and preferred. Preferably, needle 22
may include markings or graduations 27 near the distal tip as shown
in FIG. 19. A graduated needle may be particularly useful to a
surgeon inasmuch as much of the needle within the eye is not
visible to the surgeon. Typically, the only visible portion of
needle 22 is the portion within the anterior chamber. Accordingly,
graduations 27 uniformly spaced along the needle shaft assist the
surgeon in determining how far to advance the needle in order to
place channel 26 in the desired location. In one embodiment, the
graduations may be applied using laser marks, ink, paint or
engraving and are typically spaced 0.1 to 1.0 mm apart.
[0093] While a straight hollow needle of the type typically used in
medial procedures is generally preferred, in an alternative to the
needle shown in the FIGS. 3-15 and described above, needle 22 may
be rigid and have a distal portion that is arcute as shown in FIGS.
22-24. As shown in FIGS. 22(a)-(d) and FIGS. 23-24 arcuate needle
may be preferably U-shaped or substantially U-shaped. With an
"arcuate" needle, instead of pushing the needle into the patient's
eye, the surgeon may orient the needle to "pull" the needle into
the patient's eye. As shown in FIGS. 23-24, the distal portion of
the needle 22 terminating in the beveled tip, identified by
reference number 96 is preferably disposed obliquely relative to
the longitudinal axis of needle shaft 98 as seen in FIG. 24.
[0094] Providing a piercing end 96 that is bent away from the plane
of needle shaft 98 can facilitate manipulation and rotation of
needle 22 during implantation of tube 26. It may also provide the
surgeon with greater flexibility in terms of selecting the corneal
entry site and the ultimate final position of channel 26. This is
perhaps best seen with reference to FIGS. 20, 21 and 22(a)-(d).
[0095] For example, FIG. 20 depicts a transpupil implantation
delivery generally described in U.S. Pat. No. 6,544,249 as shown in
FIG. 1. While the approach is satisfactory, it does require the
needle to cross the visual axis. In the event of a surgical error
that causes damage to the cornea or lens, corrective surgery may be
required.
[0096] FIG. 21 depicts an alternative method of delivery referred
to as an ipsilateral tangential delivery of channel 26. In the
ipsilateral tangential delivery method, the straight needle is
directed tangentially to the pupil 100 border and the surgical
limbus. This type of implant delivery allows the channel to be
delivered to a greater circumference of the eye and has the
advantage of avoiding the visual axis. Avoiding the visual axis
reduces the risk of complications to the cornea 19 and lens through
contact during surgery. Ipsilateral tangential delivery is a
modification of the transpupil implant location generally described
in U.S. Pat. No. 6,544,249, previously incorporated by
reference.
[0097] Although the transpupil implant delivery and/or the
ipsilateral tangential delivery, if performed correctly, are
acceptable methods of delivering channel 26, they do somewhat limit
the location of the corneal entry site due to interference with the
nose and eye orbit bones. In that regard, an arcuate needle of the
type described above and shown in FIGS. 22(a)-(d) and FIGS. 23-24
may provide greater flexibility to the surgeon. With an arcuate
needle, channel 26 may be placed anywhere around the 360.degree.
circumference of the eye, including the temporal quadrants which
would not be otherwise accessible for the reasons discussed
above.
[0098] A further advantage of the arcuate needle and the delivery
implant method associated therewith is that microfistula channel 26
can be delivered without crossing the lens i.e., visual axis,
thereby reducing the risk of complications. An arcuate needle
design may also allow the surgery to be done in patients with
abnormal anatomy or who have previously undergone surgery.
[0099] In accordance with delivering a microfistula channel 26
using the U-shaped hollow needle 20 of FIGS. 23 and 24, as noted
above, instead of pushing the needle into the patient's eye, the
surgeon orients the needle to "pull" needle 22 into the patient's
eye. Thus, as shown in FIG. 22(a), the pointed tip of hollow needle
22 is inserted at the desired corneal entry point and pulled in the
direction of the arrow. Once the portion of needle 22 that contains
the channel 26 is in the patient's eye, the surgeon rotates the
needle and directs the needle 22 toward the target within the angle
of the anterior chamber. After adjusting needle 22 to the proper
position, the surgeon again pulls the needle 22 in the direction of
the arrow of FIG. 22(b) so that the needle is directed through the
trabecular mesh work and sclera. The particular advancement and
delivery steps described previously are then performed to place the
channel 26 in the desired location and withdraw the guidewire
plunger and needle from the eye. Of course, retraction and other
movements of the needle may be automatically controlled in the
manner described above and as shown in FIG. 9.
[0100] In a further embodiment, a hollow needle 22 that is bent
(but not necessarily in a U-shape as described above), may be
provided. A needle of this type is shown in FIGS. 25-27. As with
the "arcuate" or U-shaped needles discussed above, a simple bend in
the distal portion of needle 22 can likewise avoid interference
from the patient's facial features. A bend that creates an angle
.alpha. of between 900.degree.-180.degree. may be preferred.
Providing a needle 22 with a bend is also ergonomically desirable
in that it improves the position of the surgeon's hands during
surgery. For example, by providing a bend in the distal portion of
needle 22, a surgeon may rest and stabilize his hands on the
patient's forehead or other support while making the initial
corneal entry and carrying out the later implantation steps.
Providing a bend in the distal portion of needle 22 is not merely
an alternative to the U-shaped needle of FIGS. 23 and 24. In fact,
both features i.e., a needle with an arcuate distal portion and
further having a bend near the distal tip may be employed together
in the needle 22.
[0101] Whether the needle is U-shaped or bent at an angle .alpha.
shown in FIG. 25, the component parts of needle 22 must likewise be
susceptible to bending. Accordingly, instead of a rigid plunger 32
and guidewire 28, both the plunger and guidewire may be, in part,
bendable or be made of a material that is bendable, yet provides
adequate support and has adequate strength. In one example, the
plunger 32 may be made of a tightly wound coil such as but limited
to a spring or coil. Alternatively, at least a portion of guidewire
28 or plunger 32 may be made of a flexible plastic material
including a polymeric material, examples of which include
polyimide, PEEK, Pebax or Teflon. Other bendable, flexible
materials may also be used. Similarly, guidewire 28 may be made of
any of the above-described materials or a material such as nitinol
which has shape memory characteristics. The entire plunger or
guidewire 28 may be made of the flexible materials described above
or, as shown in FIG. 27 only a portion of the guidewire 28 or
plunger tube 32 may be made of the selected material or be
otherwise bendable.
[0102] Typically, however, guidewire 28 is preferably a narrow
gauge wire made of a suitable rigid material. A preferred material
is tungsten or stainless steel, although other non-metallic
materials may also be used. In a preferred embodiment, guidewire 28
is solid with an outside diameter of approximately 50-200 (ideally
125) microns. Where guidewire 28 is made of tungsten, it may be
coated with a Teflon, polymeric, or other plastic material to
reduce friction and assist in movement of channel 26 along
guidewire 28 during implantation.
[0103] Channels 26 useful in the present invention, are preferably
made of a biocompatible and preferably bioabsorbable material. The
materials preferably have a selected rigidity, a selected stiffness
and a selected ability to swell (during manufacture and/or after
implantation) in order to provide for secure implantation of the
channel in the desired section of the eye. Selecting a material
that is capable of a controlled swelling is also desirable. By
controlled swelling, it is meant that the swellable material is
such that the outer diameter of the channel expands (increases)
without decreasing the inner diameter. The inner diameter may
increase or remain substantially the same. The materials and
methods for making channels described below provide such controlled
swelling. By sufficient biocompatibility, it is meant that the
material selected should be one that avoids moderate to severe
inflammatory or immune reactions or scarring in the eye. The
bioabsorbability is such that the channel is capable of being
absorbed by the body after it has been implanted for a period of
anywhere between 30 days and 2 years and, more preferably, several
months such as 4-7 months.
[0104] In one embodiment, the material selected for the channels is
preferably a gelatin or other similar material. In a preferred
embodiment, the gelatin used for making the channel is known as
gelatin Type B from bovine skin. A preferred gelatin is PB Leiner
gelatin from bovine skin, Type B, 225 Bloom, USP. Another material
that may be used in the making of the channels is a gelatin Type A
from porcine skin also available from Sigma Chemical. Such gelatin
is available is available from Sigma Chemical Company of St. Louis,
Mo. under Code G-9382. Still other suitable gelatins include bovine
bone gelatin, porcine bone gelatin and human-derived gelatins. In
addition to gelatins, microfistula channel may be made of
hydroxypropyl methycellulose (HPMC), collagen, polylactic acid,
polylglycolic acid, hyaluronic acid and glycosaminoglycans.
[0105] In accordance with the present invention, gelatin channels
are preferably cross-linked. Cross-linking increases the inter- and
intramolecular binding of the gelatin substrate. Any means for
cross-linking the gelatin may be used. In a preferred embodiment,
the formed gelatin channels are treated with a solution of a
cross-linking agent such as, but not limited to, glutaraldehyde.
Other suitable compounds for cross-linking include
1-ethyl-3-[3-(dimethyamino)propyl]carbodiimide (EDC). Cross-linking
by radiation, such as gamma or electron beam (e-beam) may be
alternatively employed.
[0106] In one embodiment, the gelatin channels are contacted with a
solution of approximately 25% glutaraldehyde for a selected period
of time. One suitable form of glutaraldehyde is a grade 1G5882
glutaraldehyde available from Sigma Aldridge Company of Germany,
although other glutaraldehyde solutions may also be used. The pH of
the glutaraldehyde solution should preferably be in the range of 7
to 7.8 and, more preferably, 7.35-7.44 and typically approximately
7.4.+-0.0.01. If necessary, the pH may be adjusted by adding a
suitable amount of a base such as sodium hydroxide as needed.
[0107] Channels used in the present invention are generally
cylindrically shaped having an outside cylindrical wall and, in one
embodiment, a hollow interior. The channels preferably have an
inside diameter of approximately 50-250 microns and, more
preferably, an inside diameter and us, a flow path diameter of
approximately 150 to 230 microns. The outside diameter of the
channels may be approximately 190-300 with a minimum wall thickness
of 30-70 microns for stiffness.
[0108] As shown in FIG. 28, one end of tube 26 may be slightly
tapered to limit or prevent migration of tube 26 after it has been
implanted. Other means for limiting migration are also shown in
FIGS. 29-33. For example, channel 26 may include expandable tab 150
along outer surface 152 of tube 26. As shown in FIG. 29, prior to
deployment and introduction of tube into the patient's eye, tabs
150 are rolled or otherwise pressed against surface 152. Tabs 150
may also be features that are cut out of the outer surface of
channel 26 (i.e., not separately applied). Upon contact with an
aqueous environment, tabs 150 are deployed. Specifically, contact
with an aqueous environment causes tabs 150 to expand as shown in
FIG. 30 and, thereby, create an obstruction which limits or
prevents migration of tube 26. Tube 26 may include a plurality of
tabs, typically but not limited to 1-4, and may be located nearer
the subconjuctival side, the anterior chamber or both, as shown in
FIG. 33. Other means for limiting or preventing migration include
barbs 158 placed along the length of tube 26 as shown in FIGS.
31-32 and also disclosed in U.S. Pat. Nos. 6,544,249 and 6,007,511,
previously incorporated by reference.
[0109] The length of the channel may be any length sufficient to
provide a passageway or canal between the anterior chamber and the
subconjunctival space. Typically, the length of the channel is
between approximately 2 to 8 millimeters with a total length of
approximately 6 millimeters, in most cases being preferred. The
inner diameter and/or length of tube 26 can be varied in order to
regulate the flow rate through channel 26. A preferred flow rate is
approximately 1-3 microliters per minute, with a flow rate of
approximately 2 microliters being more preferred.
[0110] In one embodiment, channels 26 may be made by dipping a core
or substrate such as a wire of a suitable diameter in a solution of
gelatin. The gelatin solution is typically prepared by dissolving a
gelatin powder in de-ionized water or sterile water for injection
and placing the dissolved gelatin in a water bath at a temperature
of approximately 55.degree. C. with thorough mixing to ensure
complete dissolution of the gelatin. In one embodiment, the ratio
of solid gelatin to water is approximately 10% to 50% gelatin by
weight to 50% to 90% by weight of water. In an embodiment, the
gelatin solution includes approximately 40% by weight, gelatin
dissolved in water. The resulting gelatin solution preferably is
devoid of any air bubbles and has a viscosity that is between
approximately 200-500 cp and more preferably between approximately
260 and 410 cp (centipoise).
[0111] Once the gelatin solution has been prepared, in accordance
with the method described above, supporting structures such as
wires having a selected diameter are dipped into the solution to
form the gelatin channels. Stainless steel wires coated with a
biocompatible, lubricious material such as polytetrafluoroethylene
(Teflon) are preferred.
[0112] Typically, the wires are gently lowered into a container of
the gelatin solution and then slowly withdrawn. The rate of
movement is selected to control the thickness of the coat. In
addition, it is preferred that a the tube be removed at a constant
rate in order to provide the desired coating. To ensure that the
gelatin is spread evenly over the surface of the wire, in one
embodiment, the wires may be rotated in a stream of cool air which
helps to set the gelatin solution and affix film onto the wire.
Dipping and withdrawing the wire supports may be repeated several
times to further ensure even coating of the gelatin. Once the wires
have been sufficiently coated with gelatin, the resulting gelatin
films on the wire may be dried at room temperature for at least 1
hour, and more preferably, approximately 10 to 24 hours. Apparatus
for forming gelatin tubes are described below.
[0113] Once dried, the formed microfistula gelatin channels are
treated with a cross-linking agent. In one embodiment, the formed
microfistula gelatin films may be cross-linked by dipping the wire
(with film thereon) into the 25% glutaraldehyde solution, at pH of
approximately 7.0-7.8 and more preferably approximately 7.35-7.44
at room temperature for at least 4 hours and preferably between
approximately 10 to 36 hours, depending on the degree of
cross-linking desired. In one embodiment, formed channel is
contacted with a cross-linking agent such as gluteraldehyde for at
least approximately 16 hours. Cross-linking can also be accelerated
when it is performed a high temperatures. It is believed that the
degree of cross-linking is proportional to the bioabsorption time
of the channel once implanted. In general, the more cross-linking,
the longer the survival of the channel in the body.
[0114] The residual glutaraldehyde or other cross-linking agent is
removed from the formed channels by soaking the tubes in a volume
of sterile water for injection. The water may optionally be
replaced at regular intervals, circulated or re-circulated to
accelerate diffusion of the unbound glutaraldehyde from the tube.
The tubes are washed for a period of a few hours to a period of a
few months with the ideal time being 3-14 days. The now
cross-linked gelatin tubes may then be dried (cured) at ambient
temperature for a selected period of time. It has been observed
that a drying period of approximately 48-96 hours and more
typically 3 days (i.e., 72 hours) may be preferred for the
formation of the cross-linked gelatin tubes.
[0115] Where a cross-linking agent is used, it may be desirable to
include a quenching agent in the method of making channel 26.
Quenching agents remove unbound molecules of the cross-linking
agent from the formed channel 26. In certain cases, removing the
cross-linking agent may reduce the potential toxicity to a patient
if too much of the cross-linking agent is released from channel 26.
Formed channel 26 is preferably contacted with the quenching agent
after the cross-linking treatment and, preferably, may be included
with the washing/rinsing solution. Examples of quenching agents
include glycine or sodium borohydride.
[0116] The formed gelatin tubes may be further treated with
biologics, pharmaceuticals or other chemicals selected to regulate
the body's response to the implantation of channel 26 and the
subsequent healing process. Examples of suitable agents include
anti-mitolic pharmaceuticals such as Mitomycin-C or 5-Fluorouracil,
anti-VEGF (such as Lucintes, Macugen, Avastin, VEGF or
steroids).
[0117] After the requisite drying period, the formed and
cross-linked gelatin tubes are removed from the underlying supports
or wires. In one embodiment, wire tubes may be cut at two ends and
the formed gelatin tube slowly removed from the wire support. In
another embodiment, wires with gelatin film thereon, may be pushed
off using a plunger or tube to remove the formed gelatin
channel.
[0118] FIGS. 16 and 17 show two alternative methods and apparatus
for forming gelatin channels. In FIG. 16, apparatus 140 includes a
suspended wire 142 that may be introduced into a vacuum chamber 144
at a temperature of 20.degree. C. The gelatin solution 146
maintained at 55.degree. C. may be applied to the wire in vacuum
chamber 144 by spraying via air jet 148. Wire 142 is rotated by
rotating apparatus 150 to ensure that the sprayed gelatin is
applied evenly to the surface of wire 142.
[0119] In FIG. 17, a further alternative embodiment of forming
gelatin tubes is shown. In accordance with the embodiment of FIG.
17, a wire 142 attached to a rotating apparatus 150 is dipped into
the gelatin solution 163 at 55.degree. C. as generally described
above. Wire 142 is dipped into and removed, from the gelatin
solution repeatedly and sprayed with air to ensure an even coat of
the gelatin film onto the wire. In either embodiment of FIGS. 16
and 17, the gelatin tubes formed thereby may be further subjected
to a cross-linking step desired above.
[0120] The gelatin tube may also be formed by preparing the mixture
as described above and extruding the gelatin into a tubular shape
using standard plastics processing techniques. Preparing channel 26
by extrusion allows for providing channels of different cross
sections. For example, as shown in FIG. 34, channels 26 having two
or more passageways 260 may be provided, allowing for flow
regulation. In one embodiment, passageways 260 may be selectively
opened or obstructed, as shown in the shading on FIG. 34(d) to
selectively control flow therethrough. One of the passageways 260
may be adapted to receive guidewire 28 or, in the alternative,
channel 26 of FIG. 34 may be used (and implanted) without a
guidewire, as previously described. Channel 26 shown in FIG. 34 may
also provide greater structural integrity after implantation.
[0121] FIG. 18 shows an automated apparatus 160 for preparing a
plurality of microfistula gelatin tubes. Shown in FIG. 18 is an
apparatus 160 that includes a temperature controlled bath 162 of
the gelatin solution 163. The apparatus includes a frame 164 that
carries a vertically movable dipping arm 166. The dipping arm is
coupled to a gear box 168 which is actuated by a rotary motor. The
dipping arm includes a plurality of clamps (not shown) for holding
several mandrel wires 170 for dipping into the gelatin solution. As
further shown in FIG. 18, mandrel wires 170 may further include
weights 172 suspended at their distal ends to ensure that the wire
remains substantially straight (without kinking or curving) and to
dampen oscillations or vibrations when being dipped in the gelatin
solution 163. The operation of apparatus 160 may be controlled by a
controller such as a computer with commands for dipping and
withdrawal of the wires from the gelatin solution. A stirrer 176
may be provided to ensure the consistency of the gelatin solution.
After the gelatin tubes have been formed, the tubes are dried and
cross-linked as described above.
[0122] Channels 26 made in accordance with the methods described
above, allow for continuous and controlled drainage of aqueous
humor from the anterior chamber of the eye. The preferred drainage
flow rate is approximately 2 microliters per minute, although by
varying the inner diameter and length of channel 26, the flow rate
may be adjusted as needed. One or more channels 26 may be implanted
into the eye of the patient to further control the drainage.
[0123] In addition to providing a safe and efficient way to relieve
intraocular pressure in the eye, it has been observed that
implanted channels disclosed herein can also contribute to
regulating the flow rate (due to resistance of the lymphatic
outflow tract) and stimulate growth of functional drainage
structures between the eye and the lymphatic and/or venous systems.
These drainage structures evacuate fluid from the subconjunctival
which also result in a low diffuse bleb, a small bleb reservoir or
no bleb whatsoever.
[0124] The formation of drainage pathways formed by and to the
lymphatic system and/or veins may have applications beyond the
treatment of glaucoma. Thus, the methods of channel implantation
may be useful in the treatment of other tissues and organs where
drainage may be desired or required.
[0125] In addition, it has been observed that as the microfistula
channel absorbs, a "natural" microfistula channel or pathway lined
with cells is formed. This "natural" channel is stable. The
implanted channel stays in place (thereby keeping the opposing
sides of the formed channel separated) long enough to allow for a
confluent covering of cells to form. Once these cells form, they
are stable, thus eliminating the need for a foreign body to be
placed in the formed space.
[0126] While the methods, apparatus and systems of this disclosure
have been described with reference to certain embodiments, it will
be apparent to those skilled in the art that numerous modifications
and variations can be made within the scope and spirit of the
inventions as recited in the appended claims.
* * * * *