U.S. patent application number 12/691176 was filed with the patent office on 2010-07-22 for flow regulating implant, method of manufacture, and delivery device.
This patent application is currently assigned to OPTONOL LTD.. Invention is credited to Orit YARDEN, Ira YARON.
Application Number | 20100185138 12/691176 |
Document ID | / |
Family ID | 25522977 |
Filed Date | 2010-07-22 |
United States Patent
Application |
20100185138 |
Kind Code |
A1 |
YARON; Ira ; et al. |
July 22, 2010 |
FLOW REGULATING IMPLANT, METHOD OF MANUFACTURE, AND DELIVERY
DEVICE
Abstract
An implant includes a tube for permitting fluid flow. A flow
controlling rod may be inserted within the tube passage. One or
more holes around the circumference of the tube may be selectively
permanently or temporarily occluded to give desired flow
characteristics. A delivery device for implanting the implant may
include a central bore in which a retractable wire is located. The
retractable wire penetrates a tube passage of the implant. After
the implant is in position in the eye, the retention wire is
retracted out of the implant. In a method for manufacturing an
implant, two tubes of different diameters are utilized. The smaller
tube fits inside the longitudinal bore of the larger tube. When the
tubes are cut, the smaller tube forms the tube of the implant and
the remaining portions of the larger tube form the retention
projection and/or disk of the implant.
Inventors: |
YARON; Ira; (Har Adar,
IL) ; YARDEN; Orit; (Givat Shmuel, IL) |
Correspondence
Address: |
KENYON & KENYON LLP
1500 K STREET N.W., SUITE 700
WASHINGTON
DC
20005
US
|
Assignee: |
OPTONOL LTD.
Neve Ilan
IL
|
Family ID: |
25522977 |
Appl. No.: |
12/691176 |
Filed: |
January 21, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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|
11952819 |
Dec 7, 2007 |
7670310 |
|
|
12691176 |
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|
|
|
10314324 |
Dec 9, 2002 |
|
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|
11952819 |
|
|
|
|
09729050 |
Dec 4, 2000 |
6510600 |
|
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10314324 |
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08975386 |
Nov 20, 1997 |
6203513 |
|
|
09729050 |
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Current U.S.
Class: |
604/9 ;
29/445 |
Current CPC
Class: |
Y10T 29/49826 20150115;
Y10T 29/49861 20150115; A61F 9/00781 20130101; A61M 27/002
20130101 |
Class at
Publication: |
604/9 ;
29/445 |
International
Class: |
A61M 5/00 20060101
A61M005/00; B23P 9/00 20060101 B23P009/00 |
Claims
1. A method for manufacturing an implant comprising the steps of:
selecting a first tube having a longitudinal bore and a second tube
having a longitudinal bore and dimensioned to fit inside the
longitudinal bore of the first tube; placing the second tube inside
the longitudinal bore of the outer tube; cutting the first tube and
the second tube to form the implant.
2. A method for manufacturing an implant as described in claim 1
wherein at least some of the cutting of the first tube is performed
before the second tube is placed inside the longitudinal bore of
the first tube.
3. A method for manufacturing an implant as described in claim 1
wherein at least some of the cutting of the first tube is performed
after the second tube is placed inside the longitudinal bore of the
first tube.
4. A method for manufacturing an implant as described in claim 3
wherein the cutting includes simultaneously cutting the outer tube
and inner tube along an angled plane at the outlet end of the
implant.
5. A method for manufacturing an implant as described in claim 1
further comprising the step of welding the second tube to the first
tube after it is placed in the longitudinal bore of the first
tube.
6. A method for manufacturing an implant as described in claim 1
wherein the portion of the inner tube that remains after completion
of the cutting forms an implant shaft and the portions of the outer
tube that remain after completion of the cutting form a retention
projection and a disk of the implant.
7. An implant for regulating fluid flow comprising: a tube
comprising an inlet end, an outlet end, and a tube passage
extending between the inlet end and the outlet end for permitting
fluid to flow through the tube passage; wherein the implant has a
flow controlling rod located in the tube passage.
8. An implant according to claim 7 wherein the flow controlling rod
has a circular cross-section.
9. An implant according to claim 7 wherein the flow controlling rod
has a noncircular cross-section.
10. An implant according to claim 7 wherein the flow controlling
rod has an external groove on its outer surface.
11. An implant according to claim 10 wherein the external groove is
helical.
12. An implant according to claim 7 wherein the flow controlling
rod is tapered.
13. An implant according to claim 7 wherein one of the location or
angular orientation of the flow controlling rod within the tube
passage is adjustable.
14. An implant according to claim 7 wherein the flow controlling
rod is bendable within the tube passage to regulate flow in
accordance with the fluid pressure.
15. An implant according to claim 7 wherein the flow controlling
rod is movable within the tube passage to regulate flow in
accordance with the fluid pressure.
16. An implant according to claim 15 wherein the flow controlling
rod is biased by a spring within the tube passage.
17.-22. (canceled)
23. A delivery device for implanting an implant, the delivery
device comprising: a handle; a rodlike instrument having a bore; a
retractable wire located in the bore of the rodlike instrument; and
a retention mechanism including an abutment surface for preventing
the implant from moving up the delivery device during implantation
and a hook for preventing the implant from moving down the wire
during implantation.
24. A delivery device according to claim 23 wherein the hook
prevents movement of the implant in a direction parallel to the
wire but permits movement in a direction transverse to the wire,
such that when the wire is retracted from a tube passage of the
implant, the implant is permitted to slide away from the hook to
separate the implant from the delivery device.
25. A delivery device according to claim 23 wherein the abutment
surface has an angle generally corresponding to that of a disk of
the implant.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of application Ser. No.
11/952,819, filed Dec. 7, 2007, U.S. Pat. No. 7,670,310, which is a
Continuation of application Ser. No. 10/314,324, filed Dec. 9,
2002, abandoned, which is a Divisional of application Ser. No.
09/729,050, filed Dec. 4, 2000, U.S. Pat. No. 6,510,600, which is a
Divisional of application Ser. No. 08/975,386, filed Nov. 20, 1997,
U.S. Pat. No. 6,203,513, the entire contents of which are
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention relates generally to medical implants used to
regulate the flow of fluids within the body. The invention may be
applied, for example, to ophthalmic implants for treatment of
glaucoma. The invention also relates to methods of manufacturing
such implants and to delivery devices for implanting such
implants.
BACKGROUND OF THE INVENTION
[0003] Medical implants used to regulate the flow of fluids within
the human body are known and used.
[0004] One application for the use of such implants is in the
treatment of glaucoma. Glaucoma is an eye condition characterized
by an increase in the intraocular pressure (IOP) of the eye to an
abnormal level. A normal eye maintains a proper IOP by the
circulation within the eye of aqueous humor--aqueous humor is
secreted from the ciliary body, passes through the pupil into the
anterior chamber of the eyeball, and is filtered out of the eyeball
via the trabeculum and the Canal of Schlemm. With glaucoma, the
aqueous humor excretory pathway is blocked, the aqueous humor
cannot pass out of the eyeball at an adequate rate, the IOP rises,
the eyeball becomes harder, and the optic nerve atrophies by the
pressure applied on its fibers leaving the retina. A characteristic
optic neuropathy develops, resulting in progressive death of the
ganglion cells in the retina, restriction of the visual field, and
eventual blindness. Advanced stages of the disease are
characterized also by significant pain.
[0005] Glaucoma treatment, if initiated early in the course of the
disease, can prevent further deterioration and preserve most of the
ocular functions. The goal of glaucoma treatment is to reduce the
IOP to a level which is considered safe for a particular eye, but
which is not so low as to cause ocular malfunction or retinal
complications.
[0006] One type of glaucoma treatment is filtration surgery, which
provides an alternate route for aqueous humor to exit the anterior
chamber of the eyeball and enter the sub-conjunctival space,
thereby lowering the IOP. In full thickness operations a fistula is
created through the limbal sclera, connecting directly the anterior
chamber of the eyeball and the sub-conjunctival space. Full
thickness operations provide long-lasting control of IOP; however,
excessive loss of aqueous humor from the eyeball during the early
postoperative period frequently leads to hypotony.
[0007] In guarded filtration surgery (trabeculectomy), a fistula
created through the limbal sclera is protected by an overlying
partial thickness sutured scleral flap. The scleral flap provides
additional resistance to excessive loss of aqueous humor from the
eyeball, thereby reducing the risk of early postoperative hypotony.
However, trabeculectomy may result in higher eventual IOP and
increased risk of late failure of filtration, compared with full
thickness operations.
[0008] In accordance with one recently introduced procedure, a full
thickness filtering fistula may be created by a holmium laser
probe, with minimal surgically induced trauma. After retrobulbar
anesthesia, a conjunctival incision (approximately 1 mm) is made
about 12-15 mm posterior to the intended sclerostomy site, and a
laser probe is advanced through the sub-conjunctival space to the
limbus. Then, multiple laser pulses are applied until a full
thickness fistula is created. This technique has sometimes resulted
in early hypotony on account of a difficulty in controlling the
sclerostomy size. In addition, early and late iris prolapse into
the sclerostomy has resulted in abrupt closure of the fistula and
eventual surgical failure. Further, despite its relative
simplicity, the technique still necessitates the use of retrobulbar
anesthesia to avoid pain caused by the laser applications. The
injection of anesthetic material close to the already damaged optic
nerve may sometimes lead to further visual damage. A further
disadvantage of this procedure, as well as other types of glaucoma
filtration surgery, is the propensity of the fistula to be sealed
by scarring.
[0009] Various attempts have been made to overcome the problems of
filtration surgery, for example, by using ophthalmic implant
devices. Typical ophthalmic implants utilize drainage tubes so as
to maintain the integrity of the openings formed in the eyeball for
the relief of the IOP.
[0010] Typical ophthalmic implants suffer from several
disadvantages. For example, the implants typically utilize a valve
mechanism for regulating the flow of aqueous humor from the
eyeball; defects in and/or failure of such valve mechanisms could
lead to excessive loss of aqueous humor from the eyeball and
possible hypotony. The implants also tend to clog over time, either
from the inside by tissue, such as the iris, being sucked into the
inlet, or from the outside by the proliferation of cells, for
example by scarring. Additionally, the typical implant insertion
operation is complicated, costly and takes a long time.
[0011] U.S. Pat. No. 3,788,327 to Donowitz et al. shows a prior art
implant utilizing a valve mechanism for regulating the flow of
aqueous humor from the eyeball. As stated above, defects in and/or
failure of such a valve mechanism could lead to excessive loss of
aqueous humor from the eyeball and possible hypotony. Additionally,
both the inlet opening and the outlet opening in the implant shown
in U.S. Pat. No. 3,788,327 may be susceptible to clogging--the
inlet opening by the iris and the outlet opening by scarring.
Finally, implantation of an implant according to U.S. Pat. No.
3,788,327 may involve the separate steps of first providing a tract
for receiving the implant and/or suturing the implant once it is in
place, which add time and possible complications to the
operation.
SUMMARY OF THE INVENTION
[0012] It is an object of the invention to provide an improved
implant to regulate the flow of fluids within the body. The
invention may be applied, for example, to an ophthalmic implant
which may be implanted into the eyeball for the treatment of
glaucoma. It is a further object of the invention to provide a
method of manufacturing such an implant and a delivery device for
implanting such an implant.
[0013] In one embodiment of an improved implant in accordance with
the invention, an intraocular implant is provided to be implanted
in the eyeball. The implant includes a tube having an inlet end, an
outlet end, and a tube passage therebetween for permitting aqueous
humor to flow out of the eyeball, and a disk connected to the tube
at the outlet end of the tube. The tube passage may have a
cross-sectional area sufficiently small to inhibit the flow of
aqueous humor through the tube passage. A flow controlling wire or
rod may be inserted within the tube passage to provide further
control over the flow. The configuration of the flow controlling
rod may be selected in accordance with the desired flow
characteristics. The configuration may be chosen to prevent flow
when the IOP is below a threshold amount.
[0014] The disk, which is designed to be located underneath the
conjunctiva, may have an outer rim for forming a reservoir having
an enlarged cross-sectional area relative to the cross-sectional
area of the tube passage. When aqueous humor flows through the tube
passage, a bleb of aqueous humor forms under the conjunctiva so
that the bleb and the elasticity of the conjunctiva assist in
regulating the flow of aqueous humor through the tube as a function
of the IOP.
[0015] To prevent clogging of the implant, the tube at its inlet
end may be provided with a beveled surface which faces away from
the iris when the implant is inserted. Additionally, one or more
circumferential holes may be provided along the tube for allowing
aqueous humor to flow into the tube passage even if the axial inlet
opening is blocked. The hole or holes may be selectively
permanently or temporarily occluded to give desired flow
characteristics.
[0016] To prevent clogging at the outlet end, the disk may have an
outer rim as described above which raises the conjunctiva away from
the axial outlet of the tube passage to allow outflow. One or more
inner uprights (which may be in the form of an inner rim) may also
be provided on the disk for this purpose. Clogging is further
avoided by implanting the implant under the conjunctiva at a
distance away from an insertion slit in the conjunctiva, such that
healing of the slit does not cause scar tissue to form in the area
of the axial outlet opening of the implant.
[0017] Implantation may be facilitated by further features of the
implant. For example, the implant may have one or more retention
projections (for example, in the form of a spur, flange, or plate).
The retention projection may be rigid, or it may be made of an
elastic material such that it is able to be flexed inward against
the tube during penetration through the sclera. Alternatively, the
retention projection may be designed to lie initially relatively
flat against the tube for easier penetration through the sclera and
to prevent tearing of the sclera, with a mechanism for extending
the retention projection outwardly when the implant is implanted in
the eyeball. For example, the retention projection may be extended
outwardly by a separate expansion tool or may be constructed of a
shape memory material, such as PMMA or nitinol, so that it is
extended outwardly when subjected to the heat of the eyeball. One
or more such retention projections are sufficient to reliably
anchor the implant in the eyeball without the need for sutures,
saving time and costs.
[0018] Implantation may also be facilitated by the provision of one
or more markers on the implant visible through the cornea upon
passing through the sclera. For example, a circumferential hole as
described above may serve as a marker; alternatively, the marker
may be some other suitable visible mechanism, such as a scratch or
colored mark on the tube. The visibility of the marker lets the
doctor know that the marker has passed through the sclera,
indicating that the implant is in place.
[0019] Implantation of an implant may be performed by use of a
delivery device comprising a handle and a rodlike instrument, for
example a needle or probe, for carrying the implant for insertion.
The delivery device has a tip for insertion into the tube passage
of the implant and a suitable retention mechanism for preventing
the implant from moving up the delivery device during implantation.
The retention mechanism may also be constructed to prevent the
implant from rotating during implantation to insure proper
orientation of the implant. The delivery device may additionally
have a suitable expansion tool for extending one or more retention
projections of the implant outwardly once the projection or
projections have penetrated through the desired tissue.
[0020] In an embodiment of a delivery device according to the
invention, the rodlike instrument has a central bore in which is
located a retractable wire. The retractable wire penetrates a tube
passage of the implant when the implant is attached to the delivery
device. A hook on the delivery device prevents the implant from
moving down the wire. After the implant is in position in the
desired implantation site, the retention wire is retracted out of
the implant. With the retention wire retracted, the implant is then
free to slide away from the hook, allowing the delivery device to
be withdrawn, leaving the implant in place.
[0021] In one method of implanting an implant according to the
invention, a small slit is cut in a portion of the conjunctiva
which normally lies at a distance away from the intended
implantation site. As the implant itself is very small, the slit
also may be very small, for example about 2 mm in length or less.
The small size of the slit as well as its positioning at a distance
away from the implantation site, for example about 10 mm, helps
prevent contamination of the sclerostomy site and reduces the risk
of infection.
[0022] The implant is placed through the slit, directed to the
implantation site, and inserted into the sclera at the implantation
site. The sclera may be pierced either by a needle-like tip of the
tube of the implant formed by a beveled surface at the inlet end of
the tube as described above or by the tip of a needle of the
delivery device which carries the implant. Thus, the implant may be
inserted directly into the eyeball without the need for any
separate piercing step, resulting in cost and time savings.
[0023] In a method for manufacturing an intraocular implant
according to the invention, two tubes of different diameters are
utilized. The smaller tube is able to fit inside the longitudinal
bore of the larger tube. When the tubes are cut, the smaller tube
forms the tube of the implant and the remaining portions of the
larger tube form the retention projection and disk of the
implant.
[0024] An intraocular implant according to the invention provide
the advantages of a full thickness fistula, while avoiding the
limitations of the standard trabeculectomy. An implant according to
the invention may be very small and implantable without surgery. No
surgery room or hospitalization is necessary, thereby reducing
costs. Implantation is minimally invasive, simple and quick,
requiring only local anesthesia. Retrobulbar anaesthesia is not
necessary, and thus iatrogenic damage to the optic nerve is
avoided. There is no need to perform an iridectomy, and thus
aqueous flow is maintained, lens nourishment is unaffected, and the
likelihood of cataracts developing as a result of the procedure is
reduced.
[0025] An implant according to the invention has other applications
aside from the field of intraocular implants. For example, the
implant may be used for drainage of a hydrocele sac, regulating
flow between the hydrocele sac and the subcutaneous scrotum. As
will be appreciated by persons of ordinary skill in the art, other
applications of an implant in accordance with the invention are
possible.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a schematic cross-sectional view of a first
embodiment of an intraocular implant shown inserted in an
eyeball;
[0027] FIG. 2 is an enlarged perspective view of the intraocular
implant of FIG. 1;
[0028] FIG. 3 is a view similar to FIG. 2, with part of the
intraocular implant cut away to show a sectional view thereof;
[0029] FIG. 4 is an enlarged perspective view of a disk portion of
the intraocular implant of FIG. 1;
[0030] FIGS. 5 through 7 illustrate the action of the conjunctiva
during operation of the intraocular implant of FIG. 1, with FIG. 5
showing a stage of operation without a bleb formed, FIG. 6 showing
a formation of the bleb, and FIG. 7 showing further formation of
the bleb;
[0031] FIGS. 8 through 10 illustrate a delivery device and
insertion of the intraocular implant of FIG. 1 into an eyeball,
with FIG. 8 showing the delivery device and implant before
insertion, FIG. 9 showing the delivery device and implant being
placed through a slit in the conjunctiva, and FIG. 10 showing the
implant after insertion with the delivery device withdrawn;
[0032] FIG. 11 is an enlarged perspective view of a second
embodiment of an intraocular implant with part of the intraocular
implant cut away to show a sectional view thereof;
[0033] FIG. 12 is a top view of the intraocular implant of FIG. 11,
showing a disk portion of the implant;
[0034] FIG. 13 illustrates a delivery device and insertion of the
intraocular implant of FIG. 11 into an eyeball;
[0035] FIG. 14 is a schematic cross-sectional view of the
intraocular implant of FIG. 11, shown inserted in an eyeball;
[0036] FIGS. 15 and 16 illustrate a third embodiment of an
intraocular implant with FIG. 15 showing the implant prior to
attachment of a retention plate and FIG. 16 showing the implant
after attachment of the retention plate;
[0037] FIGS. 17 through 19 illustrate successive steps in a method
of manufacturing an intraocular implant according to an embodiment
of the invention, with FIG. 17 showing an outer tube cut in an
initial phase of the manufacturing process, FIG. 18 showing the
outer tube joined to an inner tube, and FIG. 19 showing the
finished intraocular implant;
[0038] FIG. 20 illustrates an intraocular implant according to the
invention with a flow controlling wire or rod in the tube
passage;
[0039] FIGS. 21A through 21D illustrate four variations of
cross-sections for a flow controlling rod;
[0040] FIG. 22 illustrates an intraocular implant with a threaded
flow controlling rod;
[0041] FIG. 23 illustrates an intraocular implant with a tapered
flow controlling rod;
[0042] FIG. 24 illustrates an intraocular implant with an
adjustable flow controlling rod;
[0043] FIG. 25 illustrates an intraocular implant with selectively
occluded side holes;
[0044] FIG. 26 illustrates an intraocular implant with a flexible
flow controlling rod;
[0045] FIG. 27 illustrates an intraocular implant with a flow
controlling rod biased against a spring;
[0046] FIG. 28 illustrates the end of an embodiment of a delivery
device according to the invention and an implant attached to the
delivery device; and
[0047] FIG. 29 illustrates a view similar to that of FIG. 28, with
a retention wire of the delivery device retracted from the
implant.
DETAILED DESCRIPTION OF THE DRAWINGS
[0048] FIG. 1 illustrates an intraocular implant 30, implanted in
an eyeball 10. The implant 30 comprises a needle-like tube 32 and a
disk 34. The plane of the disk 34 forms an angle with the tube 32
that corresponds to the angle between the surface of the sclera 12
and the axis of insertion of the implant 30. The implant 30 is
inserted in the sclera 12 of the eyeball 10, in the limbal area 14
adjacent to the cornea 16, and protrudes into the anterior chamber
20 adjacent the iris 22. The implant 30 is inserted so that the
disk 34 is placed on a surface of the sclera 12 underneath the
conjunctiva 18. The implant 30 may be placed above or below the
Tenon's capsule (not shown). It will be appreciated by persons of
ordinary skill in the art that the exact location for inserting the
implant 30 is not restricted to that shown, and may be any other
suitable position, such as behind the iris 22.
[0049] FIG. 2 shows an enlarged perspective view of the implant 30
of FIG. 1, and FIG. 3 shows a similar view, with part of the
implant 30 cut away. The tube 32, which may take the form of a
modified standard retrobulbar tip, has an inlet end 40, an outlet
end 50, and a tube passage 38 extending therebetween, with the tube
passage 38 having an axial inlet 41 and an axial outlet 51. The
disk 34 is connected to the tube 32 at its outlet end 50. The
entire implant is very small; for example the tube 32 may have a
length of about 2 mm and a width of about 0.5 mm, and the disk 34
may have a diameter of about 1 mm and a thickness of less than 0.1
mm.
[0050] The tube passage 38 has a cross-sectional area sufficiently
small to inhibit the flow of aqueous humor through the tube
passage. In one embodiment, for example, the cylindrical tube
passage 38 has a diameter of about 300 micrometers. By using a
specified internal cross-sectional area for the tube passage,
excessive loss of aqueous humor from the eyeball is prevented.
[0051] When the IOP is above a threshold amount, for example about
5 mm Hg, aqueous humor drains from the anterior chamber 20 of the
eyeball 10 through the axial inlet 41 and one or more
circumferential holes 42, through the tube passage 38, and into the
space under the conjunctiva 18. The circumferential holes 42 may
take any suitable form; for example, they may be in the form of
circular openings whose combined cross-sectional area is equal to
the cross-sectional area of the tube passage 38. The
circumferential holes 42 prevent the tube passage 38 from becoming
clogged at its inlet end because, even if the iris 22 obstructs the
axial inlet 41, aqueous humor can still pass through the
circumferential holes 42. In the event the axial inlet 41 is
obstructed, the circumferential holes 42 also serve to cause a back
pressure in the tube passage 38 to unclog the axial inlet 41. The
circumferential holes 42 serve the additional purpose of insuring a
proper insertion depth of the implant 30, as the upper hole is
visible during implantation after penetration through the sclera
and thus can be used as a marker. To serve this function, any other
suitable marker (such as a scratch or colored mark) may be
used.
[0052] The inlet end 40 of the tube 32 has a needle-like tip formed
by a beveled surface 36, angled sharply for easy insertion into the
eyeball. The beveled surface 36 increases the area of the axial
inlet 41 to enlarge the entrance to the tube passage 38. The
beveled surface 36 is designed to face away from the iris 22 to
reduce the possibility of obstruction of the axial inlet 41.
Because the disk 34 is designed to rest against the sclera 12 and
the beveled surface 36 is designed to face away from the iris 22,
the beveled surface 36 lies in a plane which is angled opposite to
the plane in which the disk 34 lies.
[0053] The tube 32 may have one or more retention projections in
the form of one or more spurs 52 provided integrally with it for
retaining the implant 30 in the eyeball 10 after insertion.
Alternatively, the retention spur 52 may be made as a separate part
connected to the tube 32 by, for example, welding or brazing. The
retention spur 52 may be rigid, or it may be flexible such that it
bends toward the tube 32 during penetration of the sclera and
springs outward to its original shape after passing through the
sclera. Alternatively, the retention spur 52 may be designed for
plastic deformation by a separate expansion tool (for example, a
balloon) once it is in the eyeball 10, or the retention spur 52 may
be constructed of a shape memory material, such as PMMA or nitinol,
such that the spur is flat against the tube when cool but expands
to its final shape when subjected to the heat of the eyeball
10.
[0054] The disk 34, shown enlarged in FIG. 4, comprises a base 44,
an outer rim 46, and a plurality of inner uprights 48. The areas
between the uprights 48 constitute passageways 56 for the
transverse flow of aqueous humor. The base 44 and outer rim 46
define a reservoir 54 such that, in operation, the aqueous humor
flows out of the axial outlet 51 of the tube passage 38, between
the uprights 48, and into the reservoir 54. The passageways 56 may
be considered as part of the reservoir 54. The enlarged
cross-sectional area of the reservoir 54 as compared to the
cross-sectional area of the tube passage 38 provides a larger area
for absorption of the aqueous humor by the conjunctiva 18 and also
acts in conjunction with the elasticity of the conjunctiva 18 to
assist in regulating the flow of aqueous humor through the implant
30 as a function of the IOP.
[0055] FIGS. 5 through 7 illustrate the action of the conjunctiva
18 during operation of the implant 30, in which it can be seen that
the aqueous humor which flows out of the tube passage forms a
"bleb" 24 below the conjunctiva 18. It will be appreciated by
persons having ordinary skill in the art that a higher IOP results
in a higher flow rate through the implant 30, and a greater force
of the aqueous humor on the conjunctiva 18.
[0056] In addition to defining the reservoir 54, the outer rim 46
of the disk 34 serves the additional purpose of raising the
conjunctiva 18 away from the axial outlet 51 to prevent clogging of
the tube passage 38. The inner uprights 48 also serve this
purpose.
[0057] The shape of the disk 34 may be, but is not limited to, an
ellipse, and it will be appreciated by persons having ordinary
skill in the art that it may conform to any shape which allows the
implant to fit under the conjunctiva 18 and which regulates the
IOP. The size and/or shape of the disk 34 and/or the angle between
the disk 34 and the tube 32 can also be changed in order to use
different implants for different persons' eyes.
[0058] FIGS. 8 through 10 illustrate a delivery device 60 and a
method of inserting the intraocular implant 30 into an eyeball. The
implant 30 is first attached to the delivery device 60, having a
handle 62 and a suitable rodlike instrument 64 such as a needle or
probe. The rodlike instrument 64 has a tip 70 for penetrating a
tube passage of the implant 30 and a retention mechanism for
preventing the implant from moving up the delivery device during
implantation, for example in the form of an abutment surface 68
having an angle generally corresponding to that of the disk 34.
This configuration also prevents rotation of the implant 30 on the
delivery device 60, thereby insuring proper orientation of the
implant in the eyeball. The retention mechanism may also include
one or more projections for extending inside the outer rim and/or
between the inner uprights on the disk 34. In an alternative
embodiment, the retention mechanism may be the tip of the rodlike
instrument, constructed to engage the inside of the tube passage of
the implant with a friction fit, thereby preventing the implant
from moving up the delivery device during implantation.
[0059] A delivery device 60 in which the rodlike instrument is a
needle 65 is illustrated in FIG. 9. In that illustrated embodiment,
the delivery device 60 is similar to a standard medical syringe
having a housing and a needle 65 with a bore 67. The front tip 69
of the needle 65 is configured as an abutment surface having an
angle generally corresponding to that of the disk 34. The bore 67
of the needle 65 has a tip in the form of a plug 71 which is
configured to have a cross-sectional shape corresponding to that of
the tube passage 38. The implant 30 is placed over the plug 71,
with the end of the plug 71 projecting into the tube passage 38,
and with the front tip 69 of the needle 65 abutting against the
disk 34. The plug 71 blocks the tube passage 38 during
implantation.
[0060] To insert the implant 30 into the eyeball 10, a small slit
26 is cut in a portion of the conjunctiva 18 which normally lies at
a distance away from a portion 28 of the conjunctiva 18 which
normally covers the intended implantation site. A small slit
distanced away from the implantation site, for example a 1-2 mm
slit about 5-15 mm away from the implantation site, reduces the
possibility of aqueous humor flowing out of the conjunctiva through
the slit, reduces the possibility of infection, reduces the
possibility of scarring over the axial outlet of the implant, and
facilitates closing and healing.
[0061] The implant 30, by delivery device 60, is passed through the
slit 26, under the conjunctiva 18, to the implantation site in the
sclera 12. FIG. 9 shows the advancement of the implant only
schematically; it will be appreciated that in practice the implant
is directed from the slit to the implantation site generally along
the surface of the sclera, such that the longitudinal axis of the
implant is generally parallel to the surface of the sclera. Upon
reaching the implantation site, the implant is tilted for
penetration into the sclera. The acute angle of the needle-like tip
formed by the beveled surface 36 of the implant 30 ensures that the
implant 30 enters the sclera 12 easily. The needle-like tip
penetrates through the sclera 12 into the anterior chamber 20 of
the eyeball 10, while the disk 34 is pushed up against the sclera
12.
[0062] When the implant 30 is in place, as shown in FIG. 10, the
retention spur (or spurs) 52 anchors the implant 30 in the eyeball
10 and prevents the implant 30 from sliding out as the delivery
device 60 is withdrawn. The retention spur 52 also prevents the
implant 30 from slipping out once in place.
[0063] It will be appreciated by persons having ordinary skill in
the art that the insertion of the implant is not restricted to the
method described above, and it may be inserted by any of several
methods known in the art. The delivery device may comprise an
`internal` or `external` needle. A straight or twisted guide wire,
known in the art, may also be used to guide the delivery device to
its precise position. To ease insertion, the delivery device may be
vibrated, or a lubricant, such as medical paste or gel, can be
spread onto the delivery device. Additionally, after implantation
of the implant a suitable fibrosis inhibiting compound (e.g. 5 FU,
mitomycin) may be applied to the implantation site.
[0064] FIG. 11 shows an alternative embodiment of an intraocular
implant 130. The implant 130 comprises a tube 132 attached to an
elliptical disk 134. The tube 132 has an inlet end 140, an outlet
end 150, and a tube passage 138, with the tube passage 138 having
an axial inlet 141, an axial outlet 151, and circumferential holes
142 to drain the aqueous humor from the anterior chamber 20 of the
eyeball 10 into the space under the conjunctiva 18.
[0065] The distal end 152 of the tube 132 has a partially conical
shape. A plurality of retention projections in the form of
retention flanges 158 are formed on the outer circumference of the
tube 132, approximately parallel to the disk 134, to act as anchors
to retain the implant 130 in the eyeball.
[0066] As shown in the enlarged view in FIG. 12, the disk 134
comprises an elliptical base 144, an outer rim 146, and an inner
upright curved to form an inner rim 148, defining therebetween a
reservoir 154. A plurality of "U"-shaped passageways 156 are formed
in the inner rim 148 for allowing aqueous humor to flow from the
axial outlet 151 into the reservoir 154. The outer rim 146 and the
inner rim 148 prevent the conjunctiva 18 from clogging the axial
outlet 151.
[0067] As shown in FIG. 12, the disk 134 is elliptical in shape.
The longer axis of the disk 134 is approximately twice the diameter
of the tube 132, and the disk 134 is eccentrically displaced
relative to the tube 132. The elliptical shape and placement of the
disk 134 allows a wide anchoring area for the implant 130 and
maximizes the outlet drainage area on the longer axis of the
ellipse. The shorter axis of the ellipse enables the implant 130 to
fit within the narrow space under the conjunctiva 18.
[0068] FIG. 13 illustrates a delivery device 160 and a method of
inserting the intraocular implant 130 into an eyeball. The implant
130 is slidably fixed over a needle 164 of the delivery device 160,
which, similar to a standard medical syringe, has needle 164
attached to a housing 162. The tip 174 of needle 164, which passes
through the implant 130, is acutely angled so that the tip 174 is
generally in line with the angle of the lower part of the implant
130.
[0069] A front surface of the delivery device 160 is formed as an
abutment surface angled to match the angle of the disk 134 and
further comprises an indent 172 to hold the implant 130 in place
during implantation. The shape of the delivery device 160 and the
angled surface of the disk 134 prevent the implant 130 from
rotating during implantation.
[0070] The delivery device 160 shown in FIG. 13 is used in a manner
similar to that described above with reference to FIGS. 8 through
10. In this embodiment, however, the acute angle of the needle tip
174 pierces the sclera. The angled inlet end of the implant device
130 follows the needle tip 174 through the sclera 12, into the
anterior chamber 20 of the eyeball. As shown in FIG. 14, the
retention flanges 158 anchor the implant 130 in position and
prevent the implant 130 from sliding out as the delivery device 160
is withdrawn. The anchorage of the retention flanges 158 also
prevents the implant 130 from slipping out once in place.
[0071] FIGS. 15 and 16 illustrate a third embodiment of an
intraocular implant. This embodiment is similar to that shown in
FIGS. 1 through 10, with the exception that a separately attached
retention projection in the form of a retention plate 252 is used
for anchoring instead of the retention spur 52. The retention plate
is inserted into a groove 253 in the tube of the implant 230 and
may be fastened by any suitable means, for example by welding in
the case of an implant 230 constructed of stainless steel.
[0072] An implant constructed in accordance with the invention may
be manufactured entirely from or covered with any suitable material
such as stainless steel, silicon, gold, nitinol, Teflon, tantalum,
PMMA, or any other suitable plastic or other material. The implant
may also be coated with heparin or any other suitable biologically
active compound.
[0073] Manufacture of an implant in accordance with the invention
may be carried out according to the following process. The tube may
be formed from the tip of a standard stainless steel hypodermic
needle. Using an EDM machine, small holes are drilled proximate the
tip of the needle to form the circumferential holes. At a distance
from the tip corresponding to the desired length of the tube, the
needle is cut at the appropriate angle to correspond to the desired
angle of the disk. The side of the needle is then undercut to form
a projection which can be later bent outwardly to form the
spur.
[0074] The disk may be chemically etched from a stainless steel
sheet according to the following process. A pattern of the disk is
drawn on a computer aided design (CAD) system and plotted on a
transparent film using a laser plotter. Plottings are made of both
the upper side and the lower side of the disk. The plotting for the
upper side, for example, includes the outer rim and the inner
uprights; the plotting for the lower side, for example, includes
the base of the disk.
[0075] A layer of photoresist is adhered to both surfaces of the
stainless steel sheet. The photoresist is then exposed to UV light
through the film on which the plottings are made. The areas of the
sheet which are blocked by the plottings are not exposed. The
photoresist which has been exposed to UV light is then chemically
removed.
[0076] Using an etching chemical, the stainless steel sheet is then
etched, so that the chemical eats away the areas of the sheet from
which the photoresist has been removed. The etching is
time-controlled such that the chemical takes away material only to
a predetermined depth.
[0077] By use of a plotting for the upper side which includes the
outer rim and the uprights, the chemical on the upper surface of
the sheet takes away material on the outside of the disk, in the
reservoir including between the uprights, and in the center of the
disk which is to receive the tube. Because the etching is
time-controlled, the chemical acting on the top of the sheet takes
away material only part way through the thickness of the sheet. By
use of a plotting for the lower side which includes the base of the
disk, the chemical on the lower surface of the sheet takes away
material on the outside of the disk and in the center of the disk
which is to receive the tube. The chemical acting on the bottom of
the sheet takes away material part way through the thickness of the
sheet. Because of action from both the top and the bottom, the
material on the outside of the disk and in the center of the disk
which is to receive the tube is completely taken away by the
etching process through the entire thickness of the sheet. A small
projection may be left on the outside of the disk during the
etching process to prevent the disk from being dislodged from the
sheet.
[0078] An alternative method for manufacturing an implant according
to the invention is illustrated in FIGS. 17 through 19. FIG. 17
shows an initial step of the process in which an outer tube 74
having a longitudinal bore is cut into the illustrated pattern. The
outer tube 74 may have, for example, an outer diameter of about 1
mm and an inner diameter (i.e., a diameter for its longitudinal
bore) of about 400 micrometers. In the illustration, the outer tube
74 has been cut into two pieces 76 and 78; however, it should be
recognized by persons skilled in the art that the two pieces 76 and
78 need not be completely separated. For example, the bottom half
of the tube 74 could be left intact between the two pieces, leaving
a connection piece in the form of a half-cylinder between the piece
76 and the piece 78.
[0079] In a next step of the process, illustrated in FIG. 18, a
smaller inner tube 90 is placed inside the longitudinal bore of the
remaining portion or portions of the outer tube 74. The inner tube
90 has an outer diameter that generally corresponds to the inner
diameter of the outer tube 74. For example, the inner tube may have
an outer diameter of about 400 micrometers. The inner tube also has
a longitudinal bore, which may have a diameter, for example, of
about 200 micrometers. When the inner tube 90 is placed inside the
outer tube 74, the two tubes may be secured together, for example
by welding the tubes together at the areas identified by reference
numerals 86 and 88.
[0080] After the two tubes are joined together, further cuts are
made to form the implant as shown in FIG. 19. This step includes
simultaneously cutting the outer tube and inner tube along an
angled plane at the outlet end of the implant to form the upper
surface of the disk 84 and to cut away the unwanted portion of the
inner tube 90 that would otherwise have projected beyond that upper
surface of the disk 84. The portion of the inner tube 90 that
remains after these final cuts forms the implant shaft. The
portions of the outer tube 74 that remain after these final cuts
form the retention projection 82 and the disk 84.
[0081] It will be appreciated by persons having ordinary skill in
the art that variations on this manufacturing process and other
manufacturing processes are possible. For example, an implant made
of plastic may be manufactured by a suitable molding operation.
[0082] Various mechanisms may be used, if desired, for giving
different flow characteristics to the implant. It may be desirable
to use implants with different flow characteristics for different
patients and/or to have an implant in which the flow
characteristics may be changed after implantation in a particular
patient.
[0083] FIGS. 20 through 25 illustrate various mechanisms for
assisting in controlling the flow of fluid, e.g. aqueous humor,
through an implant 100 according to the invention. In FIG. 20, the
implant 100 has a flow controlling wire or rod 92A in the tube
passage 102. The flow controlling rod 92A may be spot welded on one
side to the inside of the tube passage 102.
[0084] The effect of the flow controlling rod 92A is to reduce the
cross-sectional area through which the fluid flows for a particular
length inside the tube passage 102 of the implant 100. Because the
flow is a function of the cross-section and length of the lumen
through which it passes, the interposition of the flow controlling
rod 92A serves to increase the resistance to flow. In an
intraocular implant, for example, this assists in reducing the risk
of hypotony.
[0085] The diameter of the flow controlling rod 92A may be selected
in accordance with the flow characteristics that are desired. For
example, an internal tube passage of the implant having a diameter
of 200 micrometers may be fitted with a flow controlling rod 92A
having a diameter that is, for example, between 175 micrometers and
195 micrometers. A larger diameter for the flow controlling rod 92A
provides more resistance to flow.
[0086] The length and cross-sectional shape of the flow controlling
rod may similarly be selected to achieve the flow characteristics
that are desired. FIGS. 21A through 21D show four possible
cross-sectional shapes for the flow controlling rod. Flow
controlling rod 92A has a circular cross-section. Flow controlling
rod 92B is similar to flow controlling rod 92A with the addition of
grooves 94B. Flow controlling rod 92C has a flat surface 96C. Flow
controlling rod 92D has a longitudinal bore 98D.
[0087] FIGS. 22 and 23 illustrate further possible modifications to
the flow controlling rod to modify the flow characteristics. As
shown in FIG. 22, the flow controlling rod 92E may have an external
helical groove 99E giving it a threaded appearance. If the diameter
of the flow controlling rod 92E is large such that most or all of
the flow occurs through the helical groove 99E, this embodiment
provides a longer path for the fluid to travel and thus a greater
resistance to flow. Additionally or alternatively, as shown in FIG.
23, the flow controlling rod 92F may be tapered or partially
conical in shape. This embodiment provides less resistance to flow
toward the outlet end of the implant. Persons skilled in the art
will appreciate that numerous other variations are possible for the
shape and size of the flow controlling rod.
[0088] With the use of a flow controlling rod that is adjustable,
the flow characteristics of the implant may similarly be
adjustable. Thus, for example, the flow controlling rod may be
mounted within the tube passage by only a friction fit, so that its
position within the tube passage may be adjusted. As illustrated
schematically in FIG. 24, the longitudinal position of the flow
controlling rod 92 may be adjusted to provide a longer or shorter
distance d for the fluid to travel from the inlet side hole(s) 104
to the end of the flow controlling rod 92. A longer distance d for
the fluid to travel provides a higher resistance to flow. Another
way to adjust the flow when using a flow controlling rod with a
non-circular cross-section, as in FIGS. 21B and 21C, is to rotate
the rod within the tube passage. This rotation changes the
orientation of the rod with respect to the side holes 104, giving
different flow characteristics to the implant.
[0089] The flow characteristics of the implant may be adjusted
before implantation in accordance with the patient's needs, or, if
desired, the implant may be constructed to allow for the flow
characteristics through the implant to be varied after the implant
has been implanted. After the implant has been implanted, the flow
controlling rod 92 may be pushed forward toward the inlet end of
the implant, for example by a tool with a wire. This reduces the
distance d that the fluid must travel from the inlet side hole(s)
104 to the end of the flow controlling rod 92, and thus reduces the
resistance to flow through the implant. Alternatively, a rod with a
non-circular cross-section may be rotated after implantation.
[0090] Another way to have different flow characteristics is to
have different locations or configurations of the side holes 104.
Thus, different models of the implant may have side holes in
different locations and/or with different configurations.
Alternatively, a single implant may have side holes which can be
changed, for example by temporary occlusion of one or more of the
side holes. FIG. 25 illustrates an implant with occluded side holes
104. The occlusion may be permanent or temporary. Temporary
occlusion may be with an absorbable material or with a material
that may be removed after implantation, for example by a tool or
laser probe. In this way, the resistance to flow can be reduced
after implantation.
[0091] The implant may additionally or alternatively be designed to
give different flow characteristics as a function of the fluid
pressure. The flow controlling rod or wire may itself be flexible
or movable and designed to flex or move in response to the fluid
pressure. For example, as shown in FIG. 26, the flow controlling
rod 92G may be fixed at one end 122 to a front end of the implant
100 with the other end 124 of the rod 92G unattached and free to
bend. Before implantation, the rod 92G extends essentially parallel
to the axis of the tube passage. When implanted, pressure from the
fluid through the side holes 104 causes the rod 92G to flex, as
indicated by the dashed lines. In this way, when the fluid pressure
rises at the inlet end of the implant, the rod 92G bends to allow
greater flow.
[0092] Another related example is shown in FIG. 27. In that
embodiment, the tube passage 102A is tapered and the flow
controlling rod 92H is biased within the tube passage 102A by a
spring 126. The flow controlling rod 92H is illustrated as tapered,
but it will be appreciated that other shapes are possible. The
spring 126 is shown as braced against a flange 128 near the outlet
end of the tube passage 102A, but it will be appreciated that it
also may be attached on the opposite side of the rod 92H near the
inlet end of the tube passage 102A. When the fluid pressure
increases at the inlet end, the force on the rod 92H causes the
spring 126 to compress (or, if the spring is positioned on the
opposite side of the rod, the force on the rod causes the spring to
extend). The rod 92H is thus displaced longitudinally toward the
outlet end of the implant, to a position at which the cross-section
of the tube passage 102A is greater. Thus, the area through which
fluid is allowed to flow is increased, allowing greater flow. As
persons skilled in the art will appreciate, other variations are
possible in which the rod moves or flexes to increase flow in
response to increased pressure at the inlet end of the implant.
[0093] FIG. 28 illustrates an end portion of an alternative
embodiment of a delivery device 110 according to the invention. The
delivery device 110 has a handle (not shown) and a rodlike
instrument 112. In this case, the rodlike instrument 112 has
central bore 114 in which is located a retractable wire 116. The
retractable wire 116 is positioned for penetrating a tube passage
102 of the implant 100 when the implant 100 is attached to the
delivery device 110. The delivery device 110 has a retention
mechanism including an abutment surface 118 having an angle
generally corresponding to that of the disk 106 of the implant 100
for preventing the implant 100 from moving up the delivery device
110 during implantation and a hook 120 for preventing the implant
100 from moving down the wire 116.
[0094] For implantation, the implant 100 is placed over the wire
116 with the wire 116 projecting into the tube passage 102 and with
the abutment surface 118 abutting against the disk 106 with the
hook 120 retaining the disk 106 around the opposite side. FIG. 28
illustrates the end of the delivery device 110 in this condition,
with the retention wire 116 in its forward position.
[0095] After the implant is in position, the retention wire 116 is
retracted out of the implant 100. FIG. 29 illustrates the end of
the delivery device 110 with the retention wire retracted. With the
retention wire retracted, the implant is free to slide away from
the hook 120, allowing the delivery device 110 to be withdrawn,
leaving the implant in place.
[0096] As will also be appreciated by persons having ordinary skill
in the art, the various embodiments of implants, methods of
manufacture, delivery devices, and methods for implantation
described hereinabove are given by way of example only. Various
changes, modifications and variations may be applied to the
described embodiments without departing from the scope of the
invention, defined by the appended claims.
* * * * *