U.S. patent application number 15/012544 was filed with the patent office on 2017-12-21 for methods and devices for increasing aqueous humor outflow.
This patent application is currently assigned to IVANTIS, INC.. The applicant listed for this patent is IVANTIS, INC.. Invention is credited to Charles L. EUTENEUER, Andrew T. SCHIEBER.
Application Number | 20170360609 15/012544 |
Document ID | / |
Family ID | 56552713 |
Filed Date | 2017-12-21 |
United States Patent
Application |
20170360609 |
Kind Code |
A9 |
SCHIEBER; Andrew T. ; et
al. |
December 21, 2017 |
METHODS AND DEVICES FOR INCREASING AQUEOUS HUMOR OUTFLOW
Abstract
An ocular implant having an inlet portion and a Schlemm's canal
portion distal to the inlet portion, the inlet portion being
disposed at a proximal end of the implant and sized and configured
to be placed within an anterior chamber of a human eye, the
Schlemm's canal portion being arranged and configured to be
disposed within Schlemm's canal of the eye when the inlet portion
is disposed in the anterior chamber.
Inventors: |
SCHIEBER; Andrew T.;
(Irvine, CA) ; EUTENEUER; Charles L.; (St.
Michael, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IVANTIS, INC. |
Irvine |
CA |
US |
|
|
Assignee: |
IVANTIS, INC.
Irvine
CA
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20160220417 A1 |
August 4, 2016 |
|
|
Family ID: |
56552713 |
Appl. No.: |
15/012544 |
Filed: |
February 1, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14691267 |
Apr 20, 2015 |
9610196 |
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15012544 |
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14246363 |
Apr 7, 2014 |
9039650 |
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14691267 |
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12236225 |
Sep 23, 2008 |
8734377 |
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14246363 |
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11860318 |
Sep 24, 2007 |
7740604 |
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12236225 |
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14932658 |
Nov 4, 2015 |
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11860318 |
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13865770 |
Apr 18, 2013 |
9211213 |
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14932658 |
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12833863 |
Jul 9, 2010 |
8425449 |
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13865770 |
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62110293 |
Jan 30, 2015 |
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61224158 |
Jul 9, 2009 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 9/00781
20130101 |
International
Class: |
A61F 9/007 20060101
A61F009/007 |
Claims
1. An ocular implant comprising: a longitudinally extending body
having an inlet portion and a Schlemm's canal portion distal to the
inlet portion, the inlet portion being configured to extend into
and be in fluid communication with an anterior chamber of a human
eye and the Schlemm's canal portion being configured to be inserted
into Schlemm's canal adjacent to collector channels of the eye; a
plurality of alternating spines and frames positioned
longitudinally along at least a portion of the Schlemm's canal
portion wherein the plurality of alternating spines and frames
define a central channel extending therethrough, with the central
channel being in fluid communication with the inlet portion; each
of the spines having edges partially defining an opening across
from the central channel and in fluid communication with the
central channel; and each of the frames including first and second
struts, the first and second struts each having an edge contiguous
with an edge of an adjacent spine, the edges defining the opening
in fluid communication with the central channel; wherein the ocular
implant is configured to provide at least a 121% increase in
average outflow facility of aqueous humor from the anterior chamber
through the collector channels of the eye.
2. The ocular implant of claim 1, wherein the implant comprises at
least three openings across from the central channel.
3. The ocular implant of claim 2, wherein the average outflow
facility comprises 0.438 .mu.l/min/mmHg.
4. The ocular implant of claim 2, wherein a peak circumferential
flow rate through the ocular implant comprises 3.2 .mu.l/min.
5. The ocular implant of claim 1, wherein the implant comprises at
least six openings across from the central channel.
6. The ocular implant of claim 5, wherein the average outflow
facility comprises 0.638 .mu.l/min/mmHg.
7. The ocular implant of claim 5, wherein a peak circumferential
flow rate through the ocular implant comprises 5.7 .mu.l/min.
8. The ocular implant of claim 1, wherein the average outflow
facility of the eye prior to implantation of the ocular implant
comprises 0.138 .mu.l/min/mmHg.
9. An ocular implant adapted to reside at least partially in a
portion of Schlemm's canal of an eye adjacent to collector channels
of the eye, the implant comprising: a longitudinally extending
curved body including a proximal portion and a distal portion; the
distal portion of the curved body defining a longitudinal channel
including a channel opening; and the curved body being adapted and
configured such that the distal portion of the curved body resides
in Schlemm's canal and the proximal portion extends into the
anterior space of the eye while the ocular implant assumes an
orientation in which the channel opening is adjacent a major side
of Schlemm's canal when the ocular implant is implanted; wherein
the ocular implant is configured to provide a 121%-222% increase in
average outflow facility of aqueous humor from the anterior chamber
through the collector channels of the eye.
10. The ocular implant of claim 9, wherein the implant comprises at
least three openings across from the central channel.
11. The ocular implant of claim 10, wherein the average outflow
facility comprises 0.438 .mu.l/min/mmHg.
12. The ocular implant of claim 10, wherein a peak circumferential
flow rate through the ocular implant comprises 3.2 .mu.l/min.
13. The ocular implant of claim 9, wherein the implant comprises at
least six openings across from the central channel.
14. The ocular implant of claim 13, wherein the average outflow
facility comprises 0.638 .mu.l/min/mmHg.
15. The ocular implant of claim 13, wherein a peak circumferential
flow rate through the ocular implant comprises 5.70 min.
16. The ocular implant of claim 9, wherein the average outflow
facility of the eye prior to implantation of the ocular implant
comprises 0.138 .mu.l/min/mmHg.
17. The ocular implant of claim 10, wherein the distal portion of
the curved body occupies up to 20% of Schlemm's canal but accounts
for up to 54.5% of total outflow in the eye.
18. The ocular implant of claim 13, wherein the distal portion of
the curved body occupies up to 40% of Schlemm's canal but accounts
for up to 74.6% of total outflow in the eye.
19. An ocular implant comprising an inlet portion and a Schlemm's
canal portion distal to the inlet portion, the inlet portion being
disposed at a proximal end of the implant and sized and configured
to be placed within an anterior chamber of a human eye, the inlet
portion having an inlet adapted to be in fluid communication with
the anterior chamber, the Schlemm's canal portion comprising: a
central channel in fluid communication with the inlet, the central
channel extending longitudinally in the Schlemm's canal portion; a
first element disposed along the central channel; a second element
disposed along the central channel distal to the first element; a
third element disposed along the central channel distal to the
first element and proximal to the second; a fourth element disposed
along the central channel distal to the second element; the first,
second, third and fourth elements each comprising two edges
partially defining an elongate opening in fluid communication with
the central channel, each of the first, second, third and fourth
elements having circumferential extents less than 360 degrees so
that the elongate opening extends continuously along the first,
second, third and fourth elements, the circumferential extents of
the first and second elements being less than the circumferential
extents of the third and fourth elements; the Schlemm's canal
portion being arranged and configured to be disposed within
Schlemm's canal of the eye when the inlet portion is disposed in
the anterior chamber, wherein the ocular implant is configured to
provide a 121%-222% increase in average outflow facility of aqueous
humor from the anterior chamber through the collector channels of
the eye.
20. The ocular implant of claim 19, wherein the implant comprises
at least three openings across from the central channel.
21. The ocular implant of claim 20, wherein the average outflow
facility comprises 0.438 .mu.l/min/mmHg.
22. The ocular implant of claim 20, wherein a peak circumferential
flow rate through the ocular implant comprises 3.2 .mu.l/min.
23. The ocular implant of claim 19, wherein the implant comprises
at least six openings across from the central channel.
24. The ocular implant of claim 23, wherein the average outflow
facility comprises 0.638 .mu.l/min/mmHg.
25. The ocular implant of claim 23, wherein a peak circumferential
flow rate through the ocular implant comprises 5.7 .mu.l/min.
26. The ocular implant of claim 19, wherein the average outflow
facility of the eye prior to implantation of the ocular implant
comprises 0.138 .mu.l/min/mmHg.
27. The ocular implant of claim 20, wherein the Schlemm's canal
portion occupies up to 20% of Schlemm's canal but accounts for up
to 54.5% of total outflow in the eye.
28. The ocular implant of claim 23, wherein the Schlemm's canal
portion occupies up to 40% of Schlemm's canal but accounts for up
to 74.6% of total outflow in the eye.
29. A method of treating glaucoma comprising: supporting tissue
forming Schlemm's canal in an eye with an implant extending at
least partially in the canal along an axial length within the
canal; contacting with the implant less than 50% of the tissue
forming the canal along the axial length disposing an inlet portion
of the implant in an anterior chamber of the eye; and providing
fluid communication between the anterior chamber and the canal
axially through the inlet into a channel of the implant such that
an average outflow facility between the anterior chamber and the
canal is increased by 121%-222%; and wherein the implant comprises
open areas separated by spine areas along a first longitudinal
section, the spine areas partially defining the channel, the
supporting step comprising orienting the first longitudinal section
openings towards a trabecular mesh portion of the canal.
30. An ocular implant adapted to reside at least partially in a
portion of Schlemm's canal of a human eye, the implant comprising:
a body configured to extend within Schlemm's canal in a curved
volume having a large radius side and a short radius side, the body
having a circumferential extent within the curved volume that
varies along the length of the body between sections having a
lesser circumferential extent and sections having a greater
circumferential extent, wherein the body defines a channel
extending longitudinally through the body, the channel having a
substantially open side disposed on the large radius side at one of
the sections of lesser circumferential extent and an adjacent
section of greater circumferential extent and a plurality of
openings along the length of the body on the short radius side, the
openings being in fluid communication with the channel; and, an
inlet portion configured to be disposed in an anterior chamber of
the eye when the body is in Schlemm's canal, the inlet portion
disposed on a proximal end of the body in fluid communication with
the channel, the inlet portion defining one or more openings in
fluid communication with the anterior chamber of the eye; wherein
the ocular implant is configured to provide a 121%-222% increase in
average outflow facility of aqueous humor from the anterior chamber
through the collector channels of the eye.
31. An ocular implant adapted to reside at least partially in a
portion of Schlemm's canal of an eye, the eye having an iris
defining a pupil, the implant comprising: a longitudinally
extending curved body including a proximal portion and a distal
portion, the distal portion of the curved body having a central
longitudinal axis defined by a radius of curvature and a lateral
cross section having a first lateral extent and a second lateral
extent, an aspect ratio of the first lateral extent to the second
lateral extent being greater than or equal to about two; the distal
portion of the curved body defining a longitudinal channel
including a channel opening, the channel opening included in
defining the first lateral extent; the curved body being adapted
and configured such that the distal portion of the curved body
resides in Schlemm's canal and the proximal portion extends into
the anterior space of the eye while the ocular implant assumes an
orientation in which the channel opening is adjacent a major side
of Schlemm's canal when the ocular implant is implanted; and
wherein the ocular implant is configured to provide a 121%-222%
increase in average outflow facility of aqueous humor from the
anterior chamber through the collector channels of the eye.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit under 35 U.S.C.
.sctn.119 of U.S. Application No. 62/110,293, titled "Methods and
Devices for Increasing Aqueous Humor Outflow", filed Jan. 30, 2015.
This application is a continuation-in-part of U.S. application Ser.
No. 14/691,267, filed Apr. 20, 2015, and is a continuation-in-part
of U.S. application Ser. No. 14/932,658, filed Nov. 4, 2015, the
disclosures of which are incorporated by reference as if fully set
forth herein.
INCORPORATION BY REFERENCE
[0002] All publications and patent applications mentioned in this
specification are herein incorporated by reference to the same
extent as if each individual publication or patent application was
specifically and individually indicated to be incorporated by
reference.
FIELD OF THE INVENTION
[0003] The present invention relates generally to devices that are
implanted within the eye. More particularly, the present invention
relates to devices that facilitate the transfer of fluid from
within one area of the eye to another area of the eye.
BACKGROUND
[0004] According to a draft report by The National Eye Institute
(NEI) at The United States National Institutes of Health (NIH),
glaucoma is now the leading cause of irreversible blindness
worldwide and the second leading cause of blindness, behind
cataract, in the world. Thus, the NEI draft report concludes, "it
is critical that significant emphasis and resources continue to be
devoted to determining the pathophysiology and management of this
disease." Glaucoma researchers have found a strong correlation
between high intraocular pressure and glaucoma. For this reason,
eye care professionals routinely screen patients for glaucoma by
measuring intraocular pressure using a device known as a tonometer.
Many modern tonometers make this measurement by blowing a sudden
puff of air against the outer surface of the eye.
[0005] The eye can be conceptualized as a ball filled with fluid.
There are two types of fluid inside the eye. The cavity behind the
lens is filled with a viscous fluid known as vitreous humor. The
cavities in front of the lens are filled with a fluid know as
aqueous humor. Whenever a person views an object, he or she is
viewing that object through both the vitreous humor and the aqueous
humor.
[0006] Whenever a person views an object, he or she is also viewing
that object through the cornea and the lens of the eye. In order to
be transparent, the cornea and the lens can include no blood
vessels. Accordingly, no blood flows through the cornea and the
lens to provide nutrition to these tissues and to remove wastes
from these tissues. Instead, these functions are performed by the
aqueous humor. A continuous flow of aqueous humor through the eye
provides nutrition to portions of the eye (e.g., the cornea and the
lens) that have no blood vessels. This flow of aqueous humor also
removes waste from these tissues.
[0007] Aqueous humor is produced by an organ known as the ciliary
body. The ciliary body includes epithelial cells that continuously
secrete aqueous humor. In a healthy eye, a stream of aqueous humor
flows out of the anterior chamber of the eye through the trabecular
meshwork and into Schlemm's canal as new aqueous humor is secreted
by the epithelial cells of the ciliary body. This excess aqueous
humor enters the venous blood stream from Schlemm's canal and is
carried along with the venous blood leaving the eye.
[0008] When the natural drainage mechanisms of the eye stop
functioning properly, the pressure inside the eye begins to rise.
Researchers have theorized prolonged exposure to high intraocular
pressure causes damage to the optic nerve that transmits sensory
information from the eye to the brain. This damage to the optic
nerve results in loss of peripheral vision. As glaucoma progresses,
more and more of the visual field is lost until the patient is
completely blind.
[0009] In addition to drug treatments, a variety of surgical
treatments for glaucoma have been performed. For example, shunts
were implanted to direct aqueous humor from the anterior chamber to
the extraocular vein (Lee and Scheppens, "Aqueous-venous shunt and
intraocular pressure," Investigative Ophthalmology (February
1966)). Other early glaucoma treatment implants led from the
anterior chamber to a sub-conjunctival bleb (e.g., U.S. Pat. No.
4,968,296 and U.S. Pat. No. 5,180,362). Still others were shunts
leading from the anterior chamber to a point just inside Schlemm's
canal (Spiegel et al., "Schlemm's canal implant: a new method to
lower intraocular pressure in patients with POAG?" Ophthalmic
Surgery and Lasers (June 1999); U.S. Pat. No. 6,450,984; U.S. Pat.
No. 6,450,984). In addition to drug treatments, a variety of
surgical treatments for glaucoma have been performed. For example,
shunts were implanted to direct aqueous humor from the anterior
chamber to the extraocular vein (Lee and Scheppens, "Aqueous-venous
shunt and intraocular pressure," Investigative Ophthalmology
(February 1966)). Other early glaucoma treatment implants led from
the anterior chamber to a sub-conjunctival bleb (e.g., U.S. Pat.
No. 4,968,296 and U.S. Pat. No. 5,180,362). Still others were
shunts leading from the anterior chamber to a point just inside
Schlemm's canal (Spiegel et al., "Schlemm's canal implant: a new
method to lower intraocular pressure in patients with POAG?"
Ophthalmic Surgery and Lasers (June 1999); U.S. Pat. No. 6,450,984;
U.S. Pat. No. 6,450,984).
SUMMARY OF THE DISCLOSURE
[0010] This disclosure pertains to an ocular implant comprising a
longitudinally extending body having an inlet portion and a
Schlemm's canal portion distal to the inlet portion, the inlet
portion being configured to extend into and be in fluid
communication with an anterior chamber of a human eye and the
Schlemm's canal portion being configured to be inserted into
Schlemm's canal adjacent to collector channels of the eye, a
plurality of alternating spines and frames positioned
longitudinally along at least a portion of the Schlemm's canal
portion wherein the plurality of alternating spines and frames
define a central channel extending therethrough, with the central
channel being in fluid communication with the inlet portion, each
of the spines having edges partially defining an opening across
from the central channel and in fluid communication with the
central channel, and each of the frames including first and second
struts, the first and second struts each having an edge contiguous
with an edge of an adjacent spine, the edges defining the opening
in fluid communication with the central channel, wherein the ocular
implant is configured to provide at least a 121% increase in
average outflow facility of aqueous humor from the anterior chamber
through the collector channels of the eye.
[0011] In some embodiments, the implant comprises at least three
openings across from the central channel.
[0012] In other embodiments, the average outflow facility comprises
0.438 .mu.l/min/mmHg.
[0013] In one embodiment, a peak circumferential flow rate through
the ocular implant comprises 3.2 .mu.l/min.
[0014] In some embodiments, the implant comprises at least six
openings across from the central channel.
[0015] In one embodiment, the average outflow facility comprises
0.638 .mu.l/min/mmHg.
[0016] In some embodiments, a peak circumferential flow rate
through the ocular implant comprises 5.7 .mu.l/min.
[0017] In one embodiment, the average outflow facility of the eye
prior to implantation of the ocular implant comprises 0.138
.mu.l/min/mmHg.
[0018] An ocular implant adapted to reside at least partially in a
portion of Schlemm's canal of an eye adjacent to collector channels
of the eye is provided, the implant comprising a longitudinally
extending curved body including a proximal portion and a distal
portion, the distal portion of the curved body defining a
longitudinal channel including a channel opening, and the curved
body being adapted and configured such that the distal portion of
the curved body resides in Schlemm's canal and the proximal portion
extends into the anterior space of the eye while the ocular implant
assumes an orientation in which the channel opening is adjacent a
major side of Schlemm's canal when the ocular implant is implanted,
wherein the ocular implant is configured to provide a 121%-222%
increase in average outflow facility of aqueous humor from the
anterior chamber through the collector channels of the eye.
[0019] In some embodiments, the implant comprises at least three
openings across from the central channel.
[0020] In other embodiments, the average outflow facility comprises
0.438 .mu.l/min/mmHg.
[0021] In one embodiment, a peak circumferential flow rate through
the ocular implant comprises 3.2 .mu.l/min.
[0022] In some embodiments, the implant comprises at least six
openings across from the central channel.
[0023] In one embodiment, the average outflow facility comprises
0.638 .mu.l/min/mmHg.
[0024] In some embodiments, a peak circumferential flow rate
through the ocular implant comprises 5.7 .mu.l/min.
[0025] In one embodiment, the average outflow facility of the eye
prior to implantation of the ocular implant comprises 0.138
.mu.l/min/mmHg.
[0026] In one embodiment, the distal portion of the curved body
occupies up to 20% of Schlemm's canal but accounts for up to 54.5%
of total outflow in the eye.
[0027] In another embodiment, the distal portion of the curved body
occupies up to 40% of Schlemm's canal but accounts for up to 74.6%
of total outflow in the eye.
[0028] An ocular implant is provided comprising an inlet portion
and a Schlemm's canal portion distal to the inlet portion, the
inlet portion being disposed at a proximal end of the implant and
sized and configured to be placed within an anterior chamber of a
human eye, the inlet portion having an inlet adapted to be in fluid
communication with the anterior chamber, the Schlemm's canal
portion comprising a central channel in fluid communication with
the inlet, the central channel extending longitudinally in the
Schlemm's canal portion, a first element disposed along the central
channel, a second element disposed along the central channel distal
to the first element, a third element disposed along the central
channel distal to the first element and proximal to the second, a
fourth element disposed along the central channel distal to the
second element, the first, second, third and fourth elements each
comprising two edges partially defining an elongate opening in
fluid communication with the central channel, each of the first,
second, third and fourth elements having circumferential extents
less than 360 degrees so that the elongate opening extends
continuously along the first, second, third and fourth elements,
the circumferential extents of the first and second elements being
less than the circumferential extents of the third and fourth
elements, the Schlemm's canal portion being arranged and configured
to be disposed within Schlemm's canal of the eye when the inlet
portion is disposed in the anterior chamber, wherein the ocular
implant is configured to provide a 121%-222% increase in average
outflow facility of aqueous humor from the anterior chamber through
the collector channels of the eye.
[0029] In some embodiments, the implant comprises at least three
openings across from the central channel.
[0030] In other embodiments, the average outflow facility comprises
0.438 .mu.l/min/mmHg.
[0031] In one embodiment, a peak circumferential flow rate through
the ocular implant comprises 3.2 .mu.l/min.
[0032] In some embodiments, the implant comprises at least six
openings across from the central channel.
[0033] In one embodiment, the average outflow facility comprises
0.638 .mu.l/min/mmHg.
[0034] In some embodiments, a peak circumferential flow rate
through the ocular implant comprises 5.7 .mu.l/min.
[0035] In one embodiment, the average outflow facility of the eye
prior to implantation of the ocular implant comprises 0.138
.mu.l/min/mmHg.
[0036] In one embodiment, the distal portion of the curved body
occupies up to 20% of Schlemm's canal but accounts for up to 54.5%
of total outflow in the eye.
[0037] In another embodiment, the distal portion of the curved body
occupies up to 40% of Schlemm's canal but accounts for up to 74.6%
of total outflow in the eye.
[0038] A method of treating glaucoma is provided, comprising
supporting tissue forming Schlemm's canal in an eye with an implant
extending at least partially in the canal along an axial length
within the canal, contacting with the implant less than 50% of the
tissue forming the canal along the axial length, disposing an inlet
portion of the implant in an anterior chamber of the eye, and
providing fluid communication between the anterior chamber and the
canal axially through the inlet into a channel of the implant such
that an average outflow facility between the anterior chamber and
the canal is increased by 121%-222%, and wherein the implant
comprises open areas separated by spine areas along a first
longitudinal section, the spine areas partially defining the
channel, the supporting step comprising orienting the first
longitudinal section openings towards a trabecular mesh portion of
the canal.
[0039] An ocular implant adapted to reside at least partially in a
portion of Schlemm's canal of a human eye is provided, the implant
comprising a body configured to extend within Schlemm's canal in a
curved volume having a large radius side and a short radius side,
the body having a circumferential extent within the curved volume
that varies along the length of the body between sections having a
lesser circumferential extent and sections having a greater
circumferential extent, wherein the body defines a channel
extending longitudinally through the body, the channel having a
substantially open side disposed on the large radius side at one of
the sections of lesser circumferential extent and an adjacent
section of greater circumferential extent and a plurality of
openings along the length of the body on the short radius side, the
openings being in fluid communication with the channel, and an
inlet portion configured to be disposed in an anterior chamber of
the eye when the body is in Schlemm's canal, the inlet portion
disposed on a proximal end of the body in fluid communication with
the channel, the inlet portion defining one or more openings in
fluid communication with the anterior chamber of the eye, wherein
the ocular implant is configured to provide a 121%-222% increase in
average outflow facility of aqueous humor from the anterior chamber
through the collector channels of the eye.
[0040] An ocular implant adapted to reside at least partially in a
portion of Schlemm's canal of an eye, the eye having an iris
defining a pupil is provided, the implant comprising a
longitudinally extending curved body including a proximal portion
and a distal portion, the distal portion of the curved body having
a central longitudinal axis defined by a radius of curvature and a
lateral cross section having a first lateral extent and a second
lateral extent, an aspect ratio of the first lateral extent to the
second lateral extent being greater than or equal to about two, the
distal portion of the curved body defining a longitudinal channel
including a channel opening, the channel opening included in
defining the first lateral extent, the curved body being adapted
and configured such that the distal portion of the curved body
resides in Schlemm's canal and the proximal portion extends into
the anterior space of the eye while the ocular implant assumes an
orientation in which the channel opening is adjacent a major side
of Schlemm's canal when the ocular implant is implanted, and
wherein the ocular implant is configured to provide a 121%-222%
increase in average outflow facility of aqueous humor from the
anterior chamber through the collector channels of the eye.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] The novel features of the invention are set forth with
particularity in the claims that follow. A better understanding of
the features and advantages of the present invention will be
obtained by reference to the following detailed description that
sets forth illustrative embodiments, in which the principles of the
invention are utilized, and the accompanying drawings of which:
[0042] FIG. 1 is a stylized perspective view depicting a portion of
a human eye and a portion of an ocular implant disposed in
Schlemm's canal.
[0043] FIG. 2 is an enlarged perspective view showing a portion of
the implant of FIG. 1.
[0044] FIG. 3 is a perspective view showing a volume defined by the
body of the ocular implant of FIGS. 1 and 2.
[0045] FIG. 4 is a perspective view showing a first plane
intersecting the body of an ocular implant.
[0046] FIG. 5 is a perspective view showing a bending moment being
applied to an ocular implant.
[0047] FIG. 6 is a plan view of the implant shown in FIG. 5 but in
the absence of any bending moment.
[0048] FIG. 7A is a lateral cross-sectional view of the ocular
implant of FIG. 6 taken along section line A-A of FIG. 6.
[0049] FIG. 7B is a lateral cross-sectional view of the ocular
implant of FIG. 6 taken along section line B-B of FIG. 6.
[0050] FIG. 8 is an enlarged cross-sectional view of the ocular
implant of FIG. 6 taken along section line B-B of FIG. 6.
[0051] FIG. 9 is an enlarged cross-sectional view of the ocular
implant of FIG. 6 taken along section line A-A of FIG. 6.
[0052] FIG. 10 is a plan view showing an ocular implant according
to another embodiment of the invention having a longitudinal radius
of curvature that varies along its length.
[0053] FIG. 11 is a perspective view showing an ocular implant
according to yet another embodiment of the invention that has
substantially no radius of curvature.
[0054] FIG. 12 is a stylized representation of a medical procedure
in accordance with this detailed description.
[0055] FIG. 13A is a perspective view further illustrating a
delivery system 100 used in the medical procedure shown in the
previous Figure. FIG. 13B is an enlarged detail view further
illustrating a cannula of the delivery system shown in the previous
Figure.
[0056] FIG. 14 is a stylized perspective view illustrating the
anatomy of an eye.
[0057] FIG. 15 is a stylized perspective view showing Schlemm's
canal and an iris of the eye shown in the previous Figure.
[0058] FIG. 16 is an enlarged cross-sectional view further
illustrating Schlemm's canal SC shown in the previous Figure.
[0059] FIG. 17 is a perspective view showing an ocular implant in
accordance with this detailed description.
[0060] FIG. 18A and FIG. 18B are section views showing an ocular
implant disposed in Schlemm's canal of an eye.
[0061] FIG. 19A, FIG. 19B and FIG. 19C are multiple plan views
illustrating an implant in accordance with the present detailed
description.
[0062] FIG. 20 is a lateral cross-sectional view of an ocular
implant taken along section line A-A shown in the previous
Figure.
[0063] FIG. 21A is a perspective view of an ocular implant and FIG.
21B is a stylized perspective view showing Schlemm's canal SC
encircling an iris.
[0064] FIG. 22A is a perspective view showing a delivery system
12100 that may be used to advance an ocular implant into Schlemm's
canal of an eye. FIG. 22B is an enlarged detail view illustrating a
cannula portion of the delivery system.
[0065] FIG. 23 is an enlarged perspective view of an assembly
including a cannula, an ocular implant, and a sheath.
[0066] FIG. 24 is an additional perspective view of the assembly
shown in the previous Figure.
[0067] FIG. 25 is another perspective view of an assembly including
a cannula, an ocular implant, and a sheath.
[0068] FIG. 26 is an additional perspective view of the assembly
shown in the previous Figure.
[0069] FIG. 27A and FIG. 27B are perspective views showing a sheath
in accordance with the present detailed description.
[0070] FIG. 28 is a perspective view of an assembly including the
sheath shown in the previous Figure.
[0071] FIG. 29A and FIG. 29B are simplified plan views showing a
sheath in accordance with the present detailed description.
[0072] FIG. 30A, FIG. 30B and FIG. 30C are plan views showing an
implant in accordance with the present detailed description.
[0073] FIG. 31 is a lateral cross-sectional view of an ocular
implant taken along section line A-A shown in the previous
Figure.
[0074] FIG. 32 is a plan view showing an implant in accordance with
the present detailed description.
[0075] FIG. 33A, FIG. 33B and FIG. 33C are plan views showing an
additional implant in accordance with the present detailed
description.
[0076] FIG. 34 is a lateral cross-sectional view of an ocular
implant taken along section line B-B shown in the previous
Figure.
[0077] FIG. 35 is a plan view showing an implant in accordance with
the present detailed description.
[0078] FIG. 36A through FIG. 36D are a series of plan views
illustrating a method in accordance with the present detailed
description.
[0079] FIG. 37A through FIG. 37D are a series of section views
illustrating a method in accordance with the present detailed
description.
[0080] FIG. 38A and FIG. 38B are simplified plan views showing a
sheath in accordance with the present detailed description.
[0081] FIG. 39 is a diagram showing the results of mathematical
simulations of 8 mm and 16 mm ocular implants.
[0082] FIG. 40 is a diagram showing circumferential flow rates for
8 mm and 16 mm ocular implants.
DETAILED DESCRIPTION
[0083] FIG. 1 is a stylized perspective view depicting a portion of
a human eye 20. Eye 20 can be conceptualized as a fluid filled ball
having two chambers. Sclera 22 of eye 20 surrounds a posterior
chamber 24 filled with a viscous fluid known as vitreous humor.
Cornea 26 of eye 20 encloses an anterior chamber 30 that is filled
with a fluid know as aqueous humor. The cornea 26 meets the sclera
22 at a limbus 28 of eye 20. A lens 32 of eye 20 is located between
anterior chamber 30 and posterior chamber 24. Lens 32 is held in
place by a number of ciliary zonules 34.
[0084] Whenever a person views an object, he or she is viewing that
object through the cornea, the aqueous humor, and the lens of the
eye. In order to be transparent, the cornea and the lens can
include no blood vessels. Accordingly, no blood flows through the
cornea and the lens to provide nutrition to these tissues and to
remove wastes from these tissues. Instead, these functions are
performed by the aqueous humor. A continuous flow of aqueous humor
through the eye provides nutrition to portions of the eye (e.g.,
the cornea and the lens) that have no blood vessels. This flow of
aqueous humor also removes waste from these tissues.
[0085] Aqueous humor is produced by an organ known as the ciliary
body. The ciliary body includes epithelial cells that continuously
secrete aqueous humor. In a healthy eye, a stream of aqueous humor
flows out of the eye as new aqueous humor is secreted by the
epithelial cells of the ciliary body. This excess aqueous humor
enters the blood stream and is carried away by venous blood leaving
the eye.
[0086] In a healthy eye, aqueous humor flows out of the anterior
chamber 30 through the trabecular meshwork 36 and into Schlemm's
canal 38, located at the outer edge of the iris 42. Aqueous humor
exits Schlemm's canal 38 by flowing through a number of outlets 40.
After leaving Schlemm's canal 38, aqueous humor is absorbed into
the venous blood stream.
[0087] In FIG. 1, an ocular implant 100 is disposed in Schlemm's
canal 38 of eye 20. Ocular implant 100 has a body 102 including a
plurality of tissue supporting frames 104 and a plurality of spines
106. Body 102 also includes a first edge 120 and a second edge 122
that define a first opening 124. First opening 124 is formed as a
slot and fluidly communicates with an elongate channel 126 defined
by an inner surface 128 of body 102. With reference to FIG. 1, it
will be appreciated that first opening 124 is disposed on an outer
side 130 of body 102. Accordingly, channel 126 opens in a radially
outward direction 132 via first opening 124.
[0088] Ocular implant 100 may be inserted into Schlemm's canal of a
human eye to facilitate the flow of aqueous humor out of the
anterior chamber. This flow may include axial flow along Schlemm's
canal, flow from the anterior chamber into Schlemm's canal, and
flow leaving Schlemm's canal via outlets communicating with
Schlemm's canal. When in place within the eye, ocular implant 100
will support trabecular mesh tissue and Schlemm's canal tissue and
will provide for improved communication between the anterior
chamber and Schlemm's canal (via the trabecular meshwork) and
between pockets or compartments along Schlemm's canal. As shown in
FIG. 1, the implant is preferably oriented so that the first
opening 124 is disposed radially outwardly within Schlemm's
canal.
[0089] FIG. 2 is an enlarged perspective view showing a portion of
ocular implant 100 shown in the previous figure. Ocular implant 100
has a body 102 that extends along a generally curved longitudinal
axis 134. Body 102 has a plurality of tissue supporting frames 104
and a plurality of spines 106. As shown in FIG. 2, these spines 106
and frames 104 are arranged in a repeating AB pattern in which each
A is a tissue supporting frame and each B is a spine. In the
embodiment of FIG. 2, one spine extends between each adjacent pair
of frames 104
[0090] The frames 104 of body 102 include a first frame 136 of
ocular implant 100 that is disposed between a first spine 140 and a
second spine 142. In the embodiment of FIG. 2, first frame 136 is
formed as a first strut 144 that extends between first spine 140
and second spine 142. First frame 136 also includes a second strut
146 extending between first spine 140 and second spine 142. In the
exemplary embodiment of FIG. 2, each strut undulates in a
circumferential direction as it extends longitudinally between
first spine 140 and second spine 142.
[0091] In the embodiment of FIG. 2, body 102 has a longitudinal
radius 150 and a lateral radius 148. Body 102 of ocular implant 100
includes a first edge 120 and a second edge 122 that define a first
opening 124. First opening 124 fluidly communicates with an
elongate channel 126 defined by an inner surface 128 of body 102. A
second opening 138 is defined by a second edge 122A of a first
strut 144 and a second edge 122B of a second strut 146. First
opening 124, second opening 138 and additional openings defined by
ocular implant 100 allow aqueous humor to flow laterally across
and/or laterally through ocular implant 100. The outer surfaces of
body 102 define a volume 152.
[0092] FIG. 3 is an additional perspective view showing volume 152
defined by the body of the ocular implant shown in the previous
figure. With reference to FIG. 3, it will be appreciated that
volume 152 extends along a generally curved longitudinal axis 134.
Volume 152 has a longitudinal radius 150, a lateral radius 148, and
a generally circular lateral cross section 153.
[0093] FIG. 4 is a perspective view showing a first plane 154 and a
second plane 155 that both intersect ocular implant 100. In FIG. 4,
first plane 154 is delineated with hatch marks. With reference to
FIG. 4, it will be appreciated that spines 106 of body 102 are
generally aligned with one another and that first plane 154
intersects all spines 106 shown in FIG. 4. In the embodiment of
FIG. 4, body 102 of ocular implant 100 is generally symmetric about
first plane 154.
[0094] In the embodiment of FIG. 4, the flexibility of body 102 is
at a maximum when body 102 is bending along first plane 154, and
body 102 has less flexibility when bending along a plane other than
first plane 154 (e.g., a plane that intersects first plane 154).
For example, in the embodiment shown in FIG. 4, body 102 has a
second flexibility when bending along second plane 155 that is less
than the first flexibility that body 102 has when bending along
first plane 154.
[0095] Stated another way, in the embodiment of FIG. 4, the bending
modulus of body 102 is at a minimum when body 102 is bent along
first plane 154. Body 102 has a first bending modulus when bent
along first plane 154 and a greater bending modulus when bent along
a plane other than first plane 154 (e.g., a plane that intersects
first plane 154). For example, in the embodiment shown in FIG. 4,
body 102 has a second bending modulus when bent along second plane
155 that is greater than the first bending modulus that body 102
has when bent along first plane 154.
[0096] FIG. 5 is an enlarged perspective view showing a portion of
ocular implant 100 shown in the previous figure. In the exemplary
embodiment of FIG. 5, a bending moment M is being applied to body
102 of ocular implant 100. Bending moment M acts about a first axis
156 that is generally orthogonal to first plane 154. A second axis
158 and a third axis 160 are also shown in FIG. 5. Second axis 158
is generally perpendicular to first axis 156. Third axis 160 is
skewed relative to first axis 156.
[0097] An inner surface 128 of body 102 defines a channel 126. Body
102 of ocular implant 100 includes a first edge 120 and a second
edge 123 that define a first opening 124. Channel 126 of ocular
implant 100 fluidly communicates with first opening 124. A second
opening 138 is defined by a second edge 122A of a first strut 144
and a second edge 122B of a second strut 146. First opening 124,
second opening 138 and additional openings defined by ocular
implant 100 allow aqueous humor to flow laterally across and/or
laterally through ocular implant 100.
[0098] As shown in FIG. 5, ocular implant 100 has a first spine 140
and a second spine 142. First strut 144 and a second strut 146 form
a first frame 136 of ocular implant 100 that extends between first
spine 140 and second spine 142. In the exemplary embodiment of FIG.
5, each strut undulates in a circumferential direction as it
extends longitudinally between first spine 140 and second spine
142.
[0099] In the embodiment of FIG. 5, the flexibility of body 102 is
at a maximum when body 102 is bent by a moment acting about first
axis 156, and body 102 has less flexibility when bent by a moment
acting about an axis other than first axis 156 (e.g., second axis
158 and third axis 160). Stated another way, the bending modulus of
body 102 is at a minimum when body 102 is bent by a moment acting
about first axis 156, and body 102 has a greater bending modulus
when bent by a moment acting about an axis other than first axis
156 (e.g., second axis 158 and third axis 160).
[0100] FIG. 6 is a plan view showing ocular implant 100 shown in
the previous figure. In the embodiment of FIG. 6, no external
forces are acting on body 102 of ocular implant 100, and body 102
is free to assume the generally curved resting shape depicted in
FIG. 6. Body 102 defines a first opening 124 that is disposed on an
outer side 130 of body 102. A channel 126 is defined by the inner
surface of body 102 and opens in a radially outward direction 132
via first opening 124.
[0101] Section lines A-A and B-B are visible in FIG. 6. Section
line A-A intersects a first frame 136 of ocular implant 100.
Section line B-B intersects a first spine 140 of ocular implant
100.
[0102] FIG. 7A is a lateral cross-sectional view of ocular implant
100 taken along section line A-A shown in the previous figure.
Section line A-A intersects a first strut 144 and a second strut
146 of first frame 136 at the point where the circumferential
undulation of these struts is at its maximum. Body 102 of ocular
implant 100 has a longitudinal radius 150 and a lateral radius 148.
An inner surface 128 of body 102 defines a channel 126. A first
opening 124 fluidly communicates with channel 126.
[0103] In FIG. 7A, first opening 124 in body 102 can be seen
extending between first edge 120A of first strut 144 and a first
edge 120B of second strut 146. With reference to FIG. 7A, it will
be appreciated that second strut 146 has a shape that is a mirror
image of the shape of first strut 144.
[0104] FIG. 7B is a lateral cross-sectional view of ocular implant
100 taken along section line B-B shown in the previous figure.
Section line B-B intersects first spine 140 of ocular implant 100.
Body 102 has a longitudinal radius 150 and a lateral radius 148. In
the embodiment of FIG. 7B, the center 159 of lateral radius 148 and
the center 163 of longitudinal radius 150 are disposed on opposite
sides of first spine 140. The center 159 of lateral radius 148 is
disposed on a first side of first spine 140. The center 163 of
longitudinal radius 150 is disposed on a second side of second
spine 142.
[0105] FIG. 8 is an enlarged cross-sectional view of ocular implant
100 taken along section line B-B of FIG. 6. First spine 140
includes a first major side 160, a second major side 162, a first
minor side 164, and second minor side 166. With reference to FIG.
8, it will be appreciated that first major side 160 comprises a
concave surface 168. Second major side 162 is opposite first major
side 160. In the embodiment of FIG. 8, second major side 162
comprises a convex surface 170.
[0106] The geometry of the spine provides the ocular implant with
flexibility characteristics that may aid in advancing the ocular
implant into Schlemm's canal. In the embodiment of FIG. 8, first
spine 140 has a thickness T1 extending between first major side 160
and second major side 162. Also in the embodiment of FIG. 8, first
spine 140 has a width W1 extending between first minor side 164 and
second minor side 166.
[0107] In some useful embodiments, the spine of an ocular implant
in accordance with this detailed description has an aspect ratio of
width W1 to thickness T1 greater than about 2. In some particularly
useful embodiments, the spine of an ocular implant in accordance
with this detailed description has an aspect ratio of width W1 to
thickness T1 greater than about 4. In one useful embodiment, the
ocular implant has a spine with an aspect ratio of width W1 to
thickness T1 of about 5.2.
[0108] A first axis 156, a second axis 158 and a third axis 160 are
shown in FIG. 8. Second axis 158 is generally perpendicular to
first axis 156. Third axis 160 is skewed relative to first axis
156.
[0109] In the embodiment of FIG. 8, the flexibility of first spine
140 is at a maximum when first spine 140 is bent by a moment acting
about first axis 156. First spine 140 has a first flexibility when
bent by a moment acting about first axis 156 and less flexibility
when bent by a moment acting about an axis other than first axis
156 (e.g., second axis 158 and third axis 160). For example, first
spine 140 has a second flexibility when bent by a moment acting
about second axis 158 shown in FIG. 8. This second flexibility is
less than the first flexibility that first spine 140 has when bent
by a moment acting about first axis 156.
[0110] In the embodiment of FIG. 8, the bending modulus of first
spine 140 is at a minimum when first spine 140 is bent by a moment
acting about first axis 156. First spine 140 has a first bending
modulus when bent by a moment acting about first axis 156 and a
greater bending modulus when bent by a moment acting about an axis
other than first axis 156 (e.g., second axis 158 and third axis
160). For example, first spine 140 has a second bending modulus
when bent by a moment acting about second axis 158 shown in FIG. 8.
This second bending modulus is greater than the first bending
modulus that first spine 140 has when bent by a moment acting about
first axis 156.
[0111] FIG. 9 is an enlarged cross-sectional view of ocular implant
100 taken along section line A-A of FIG. 6. Section line A-A
intersects first strut 144 and second strut 146 at the point where
the circumferential undulation of these struts is at its
maximum.
[0112] Each strut shown in FIG. 9 includes a first major side 160,
a second major side 162, a first minor side 164, and second minor
side 166. With reference to FIG. 9, it will be appreciated that
each first major side 160 comprises a concave surface 168 and each
second major side 162 comprises a convex surface 170.
[0113] In the embodiment of FIG. 9, each strut has a thickness T2
extending between first major side 160 and second major side 162.
Also in the embodiment of FIG. 9, each strut has a width W2
extending between first minor side 164 and second minor side 166.
In some useful embodiments, an ocular implant in accordance with
this detailed description includes spines having a width W1 that is
greater than the width W2 of the struts of the ocular implant.
[0114] In some useful embodiments, the struts of an ocular implant
in accordance with this detailed description have an aspect ratio
of width W2 to thickness T2 greater than about 2. In some
particularly useful embodiments, the struts of an ocular implant in
accordance with this detailed description have an aspect ratio of
width W2 to thickness T2 greater than about 4. One exemplary ocular
implant has struts with an aspect ratio of width W2 to thickness T2
of about 4.4.
[0115] Body 102 of ocular implant 100 has a longitudinal radius 150
and a lateral radius 148. In some useful embodiments, an ocular
implant in accordance with this detailed description is
sufficiently flexible to assume a shape matching the longitudinal
curvature of Schlemm's canal when the ocular implant advanced into
the eye. Also in some useful embodiments, a length of the ocular
implant is selected so that the implant will extend across a
pre-selected angular span when the implant is positioned in
Schlemm's canal. Examples of pre-selected angular spans that may be
suitable in some applications include 60.degree., 90.degree.,
150.degree. and 180.degree.. The diameter of an ocular implant in
accordance with this detailed description may be selected so that
the ocular implant is dimensioned to lie within and support
Schlemm's canal. In some useful embodiments, the diameter of the
ocular implant ranges between about 0.005 inches and about 0.04
inches. In some particularly useful embodiments, the diameter of
the ocular implant ranges between about 0.005 inches and about 0.02
inches.
[0116] It is to be appreciated that an ocular implant in accordance
with the present detailed description may be straight or curved. If
the ocular implant is curved, it may have a substantially uniform
longitudinal radius throughout its length, or the longitudinal
radius of the ocular implant may vary along its length. FIG. 6
shows one example of an ocular implant having a substantially
uniform radius of curvature. FIG. 10 shows one example of an ocular
implant having a longitudinal radius of curvature that varies along
the length of the ocular implant. An example of a substantially
straight ocular implant is shown in FIG. 11.
[0117] FIG. 10 is a plan view showing an ocular implant 200 having
a radius of curvature that varies along its length. In the
embodiment of FIG. 10, ocular implant 200 has an at rest shape that
is generally curved. This at rest shape can be established, for
example, using a heat-setting process. The ocular implant shape
shown in FIG. 10 includes a distal radius RA, a proximal radius RC,
and an intermediate radius RB. In the embodiment of FIG. 10, distal
radius RA is larger than both intermediate radius RB and proximal
radius RC. Also in the embodiment of FIG. 10, intermediate radius
RB is larger than proximal radius RC and smaller than distal radius
RA. In one useful embodiment, distal radius RA is about 0.320
inches, intermediate radius RB is about 0.225 inches and proximal
radius RC is about 0.205 inches.
[0118] In the embodiment of FIG. 10, a distal portion of the ocular
implant follows an arc extending across an angle AA. A proximal
portion of the ocular implant follows an arc extending across an
angle AC. An intermediate portion of the ocular implant is disposed
between the proximal portion and the distal portion. The
intermediate portion extends across an angle AB. In one useful
embodiment, angle AA is about 55 degrees, angle AB is about 79
degrees and angle AC is about 60 degrees.
[0119] Ocular implant 200 may be used in conjunction with a method
of treating the eye of a human patient for a disease and/or
disorder (e.g., glaucoma). Some such methods may include the step
of inserting a core member into a lumen defined by ocular implant
200. The core member may comprise, for example, a wire or tube. The
distal end of the ocular implant may be inserted into Schlemm's
canal. The ocular implant and the core member may then be advanced
into Schlemm's canal until the ocular implant has reached a desired
position. In some embodiments, an inlet portion of the implant may
be disposed in the anterior chamber of eye while the remainder of
the implant extends through the trabecular mesh into Schlemm's
canal. The core member may then be withdrawn from the ocular
implant, leaving the implant in place to support tissue forming
Schlemm's canal. Further details of ocular implant delivery systems
may be found in U.S. application Ser. No. 11/943,289, filed Nov.
20, 2007, now U.S. Pat. No. 8,512,404, the disclosure of which is
incorporated herein by reference.
[0120] The flexibility and bending modulus features of the ocular
implant of this invention help ensure proper orientation of the
implant within Schlemm's canal. FIG. 1 shows the desired
orientation of opening 124 when the implant 100 is disposed in
Schlemm's canal. As shown, opening 124 faces radially outward. The
implant 100 is therefore designed so that it is maximally flexible
when bent along a plane defined by the longitudinal axis of implant
100 as shown in FIG. 1, and less flexible when bent in other
planes, thereby enabling the curved shape of Schlemm's canal to
help place the implant in this orientation automatically if the
implant is initially placed in Schlemm's canal in a different
orientation.
[0121] FIG. 11 is a perspective view showing an ocular implant 300
in accordance with an additional embodiment in accordance with the
present detailed description. With reference to FIG. 11, it will be
appreciated that ocular implant 300 has a resting (i.e.,
unstressed) shape that is generally straight. Ocular implant 300
extends along a longitudinal axis 334 that is generally straight.
In some useful embodiments, ocular implant 300 is sufficiently
flexible to assume a curved shape when advanced into Schlemm's
canal of an eye.
[0122] Ocular implant 300 comprises a body 302. With reference to
FIG. 11, it will be appreciated that body 302 comprises a plurality
of tissue supporting frames 304 and a plurality of spines 306. As
shown in FIG. 11, these spines 306 and frames 304 are arranged in
an alternating pattern in which one spine extends between each
adjacent pair of frames 304. The frames 304 of body 302 include a
first frame 336 of ocular implant 300 is disposed between a first
spine 340 and a second spine 342. In the embodiment of FIG. 11,
first frame 336 comprises a first strut 344 that extends between
first spine 340 and second spine 342. A second strut 346 of first
frame also extends between first spine 340 and second spine 342.
Each strut undulates in a circumferential direction as it extends
longitudinally between first spine 340 and second spine 342.
[0123] An inner surface 328 of body 302 defines a channel 326. Body
302 of ocular implant 300 includes a first edge 320 and a second
edge 322 that define a first opening 324. Channel 326 of ocular
implant 300 fluidly communicates with first opening 324. First
strut 344 of first frame 336 comprises a first edge 325A. Second
strut 346 has a first edge 325B. In FIG. 11, first opening 324 in
body 302 can be seen extending between first edge 325A of first
strut 344 and a first edge 325B of second strut 346.
[0124] A first axis 356, a second axis 358 and a third axis 360 are
shown in FIG. 11. Second axis 358 is generally perpendicular to
first axis 356. Third axis 360 is generally skewed relative to
first axis 356. The flexibility of body 302 is at a maximum when
body 302 is bent by a moment acting about first axis 356, and body
302 has less flexibility when bent by a moment acting about an axis
other than first axis 356 (e.g., second axis 358 and third axis
360). Stated another way, in the embodiment of FIG. 11, the bending
modulus of body 302 is at a minimum when body 302 is bent by a
moment acting about first axis 356, and body 302 has a greater
bending modulus when bent by a moment acting about an axis other
than first axis 356 (e.g., second axis 358 and third axis 360).
[0125] Many of the figures illustrating embodiments of the
invention show only portions of the ocular implant. It should be
understood that many embodiments of the invention include an inlet
portion (such as inlet 101 in FIG. 6 and inlet 201 in FIG. 10) that
can be placed within the anterior chamber to provide communication
of aqueous humor from the anterior chamber through the trabecular
mesh into Schlemm's canal via the ocular implant. Further details
of the inlet feature may be found in U.S. application Ser. No.
11/860,318.
[0126] FIG. 12 is a stylized representation of a medical procedure
in accordance with this detailed description. In the procedure of
FIG. 12, a physician is treating an eye 1220 of a patient P. In the
procedure of FIG. 12, the physician is holding a delivery system
12100 in his or her right hand RH. The physician's left hand (not
shown) may be used to hold the handle H of a gonio lens 1223. It
will be appreciated that some physician's may prefer holding the
delivery system handle in the left hand and the gonio lens handle H
in the right hand RH.
[0127] During the procedure illustrated in FIG. 12, the physician
may view the interior of the anterior chamber using gonio lens 1223
and a microscope 1225. Detail A of FIG. 12 is a stylized simulation
of the image viewed by the physician. A distal portion of a cannula
12102 is visible in Detail A. A shadow-like line indicates the
location of Schlemm's canal SC which is lying under various tissue
(e.g., the trabecular meshwork) that surround the anterior chamber.
A distal opening 12104 of cannula 12102 is positioned near
Schlemm's canal SC of eye 1220. In some methods in accordance with
this detailed description, distal opening 12104 of cannula 12102 is
placed in fluid communication with Schlemm's canal SC. When this is
the case, an ocular implant may be advanced through distal opening
12104 and into Schlemm's canal SC.
[0128] FIG. 13A is a perspective view further illustrating delivery
system 12100 and eye 1220 shown in the previous Figure. In FIG.
13A, cannula 12102 of delivery system 12100 is shown extending
through a cornea 1240 of eye 1220. A distal portion of cannula
12102 is disposed inside the anterior chamber defined by cornea
1240 of eye 1220. In the embodiment of FIG. 13A, cannula 12102 is
configured so that a distal opening 12104 of cannula 12102 can be
placed in fluid communication with Schlemm's canal.
[0129] In the embodiment of FIG. 13A, an ocular implant is disposed
in a lumen defined by cannula 12102. Delivery system 12100 includes
a mechanism that is capable of advancing and retracting the ocular
implant along the length of cannula 12102. The ocular implant may
be placed in Schlemm's canal of eye 1220 by advancing the ocular
implant through distal opening 12104 of cannula 12102 while distal
opening 12104 is in fluid communication with Schlemm's canal.
[0130] FIG. 13B is an enlarged detail view further illustrating
cannula 12102 of delivery system 12100. In the illustrative
embodiment of FIG. 13B, an ocular implant 12126 has been advanced
through distal opening 12104 of cannula 12102. Cannula 12102 of
FIG. 13B defines a passageway 12124 that fluidly communicates with
distal opening 12104. Ocular implant 12126 may be moved along
passageway 12124 and through distal opening by delivery system
12100. Delivery system 12100 includes a mechanism capable of
performing this function.
[0131] FIG. 14 is a stylized perspective view illustrating a
portion of eye 1220 discussed above. Eye 1220 includes an iris 1230
defining a pupil 1232. In FIG. 14, eye 1220 is shown as a
cross-sectional view created by a cutting plane passing through the
center of pupil 1232. Eye 1220 can be conceptualized as a fluid
filled ball having two chambers. Sclera 1234 of eye 1220 surrounds
a posterior chamber PC filled with a viscous fluid known as
vitreous humor. Cornea 1236 of eye 1220 encloses an anterior
chamber AC that is filled with a fluid known as aqueous humor. The
cornea 1236 meets the sclera 1234 at a limbus 1238 of eye 1220. A
lens 1240 of eye 1220 is located between anterior chamber AC and
posterior chamber PC. Lens 1240 is held in place by a number of
ciliary zonules 1242.
[0132] Whenever a person views an object, he or she is viewing that
object through the cornea, the aqueous humor, and the lens of the
eye. In order to be transparent, the cornea and the lens can
include no blood vessels. Accordingly, no blood flows through the
cornea and the lens to provide nutrition to these tissues and to
remove wastes from these tissues. Instead, these functions are
performed by the aqueous humor. A continuous flow of aqueous humor
through the eye provides nutrition to portions of the eye (e.g.,
the cornea and the lens) that have no blood vessels. This flow of
aqueous humor also removes waste from these tissues.
[0133] Aqueous humor is produced by an organ known as the ciliary
body. The ciliary body includes epithelial cells that continuously
secrete aqueous humor. In a healthy eye, a stream of aqueous humor
flows out of the eye as new aqueous humor is secreted by the
epithelial cells of the ciliary body. This excess aqueous humor
enters the blood stream and is carried away by venous blood leaving
the eye.
[0134] Schlemm's canal SC is a tube-like structure that encircles
iris 1230. Two laterally cut ends of Schlemm's canal SC are visible
in the cross-sectional view of FIG. 14. In a healthy eye, aqueous
humor flows out of anterior chamber AC and into Schlemm's canal SC.
Aqueous humor exits Schlemm's canal SC and flows into a number of
collector channels. After leaving Schlemm's canal SC, aqueous humor
is absorbed into the venous blood stream and carried out of the
eye.
[0135] FIG. 15 is a stylized perspective view showing Schlemm's
canal SC and iris 1230 of eye 1220 shown in the previous Figure. In
FIG. 15, Schlemm's canal SC is shown encircling iris 1230. With
reference to FIG. 15, it will be appreciated that Schlemm's canal
SC may overhang iris 1230 slightly. Iris 1230 defines a pupil 1232.
In the embodiment of FIG. 15, Schlemm's canal SC and iris 1230 are
shown in cross-section, with a cutting plane passing through the
center of pupil 1232.
[0136] The shape of Schlemm's canal SC is somewhat irregular, and
can vary from patient to patient. The shape of Schlemm's canal SC
may be conceptualized as a cylindrical-tube that has been partially
flattened. With reference to FIG. 15, it will be appreciated that
Schlemm's canal SC has a first major side 1250, a second major side
1252, a first minor side 1254, and a second minor side 1256.
[0137] Schlemm's canal SC forms a ring around iris 1230 with pupil
1232 disposed in the center of that ring. With reference to FIG.
15, it will be appreciated that first major side 1250 is on the
outside of the ring formed by Schlemm's canal SC and second major
side 1252 is on the inside of the ring formed by Schlemm's canal
SC. Accordingly, first major side 1250 may be referred to as an
outer major side of Schlemm's canal SC and second major side 1252
may be referred to as an inner major side of Schlemm's canal SC.
With reference to FIG. 15, it will be appreciated that first major
side 1250 is further from pupil 1232 than second major side
1252.
[0138] FIG. 16 is an enlarged cross-sectional view further
illustrating Schlemm's canal SC shown in the previous Figure. With
reference to FIG. 16, it will be appreciated that Schlemm's canal
SC comprises a wall W defining a lumen 1258. The shape of Schlemm's
canal SC is somewhat irregular, and can vary from patient to
patient. The shape of Schlemm's canal SC may be conceptualized as a
cylindrical-tube that has been partially flattened. The
cross-sectional shape of lumen 1258 may be compared to the shape of
an ellipse. A major axis 1260 and a minor axis 1262 of lumen 1258
are illustrated with dashed lines in FIG. 16.
[0139] The length of major axis 1260 and minor axis 1262 can vary
from patient to patient. The length of minor axis 1262 is between
one and thirty micrometers in most patients. The length of major
axis 1260 is between one hundred and fifty micrometers and three
hundred and fifty micrometers in most patients.
[0140] With reference to FIG. 16, it will be appreciated that
Schlemm's canal SC comprises a first major side 1250, a second
major side 1252, a first minor side 1254, and a second minor side
1256. In the embodiment of FIG. 16, first major side 1250 is longer
than both first minor side 1254 and second minor side 1256. Also in
the embodiment of FIG. 16, second major side 1252 is longer than
both first minor side 1254 and second minor side 1256.
[0141] FIG. 17 is a perspective view showing an ocular implant in
accordance with this detailed description. Ocular implant 12126 of
FIG. 17 comprises a body 12128 that extends along a generally
curved longitudinal central axis 12148. In the embodiment of FIG.
17, body 12128 has a radius of curvature R that is represented with
an arrow extending between a lateral central axis 12176 and body
12128.
[0142] Body 12128 of ocular implant 12126 has a first major surface
12130 and a second major surface 12132. With reference to FIG. 17,
it will be appreciated that body 12128 is curved about longitudinal
central axis 12148 so that first major surface 12130 comprises a
concave surface 12136 and second major surface 12132 comprises a
convex surface 12134. The curvature of body 12128 can be pre-sized
and configured to align with the curvature of Schlemm's canal in a
patient's eye.
[0143] A distal portion of body 12128 defines a longitudinal
channel 12138 including a channel opening 12139. Channel opening
12139 is disposed diametrically opposite a central portion 12135 of
concave surface 12136. Because of the curvature of the body 12128,
an outer diameter of the implant defined by the channel opening
12139 will be greater than an inner diameter of the implant defined
by surface 12132. In some embodiments, the body is pre-biased to
assume a configuration in which the channel opening 12139 is
disposed along an outer diameter of the body, ensuring that the
channel opening can be positioned adjacent to the first major side
1250 of Schlemm's canal.
[0144] In the embodiment of FIG. 17, central portion 12135 of
concave surface 12136 defines a plurality of apertures 12137. Each
aperture 12137 fluidly communicates with channel 12138. In some
useful embodiments, body 12128 is adapted and configured such that
ocular implant 12126 assumes an orientation in which channel
opening 12139 is adjacent a major side of Schlemm's canal when
ocular implant 12126 is disposed in Schlemm's canal. Ocular implant
12126 can be made, for example, by laser cutting body 12128 from a
length of metal or a shape memory material (e.g., nitinol or
stainless steel) tubing.
[0145] FIG. 18A and FIG. 18B are section views showing an ocular
implant 12126 disposed in Schlemm's canal SC of an eye. FIG. 18A
and FIG. 18B may be collectively referred to as FIG. 18. The eye of
FIG. 18 includes an iris 1230. A central portion of iris 1230
defines a pupil 1232. Schlemm's canal SC is disposed near an outer
edge of iris 1230. The trabecular meshwork TM extends up from the
iris of overlays Schlemm's canal SC. The picture plane of FIG. 18
extends laterally across Schlemm's canal SC and the trabecular
meshwork TM.
[0146] Schlemm's canal SC forms a ring around iris 1230 with pupil
1232 disposed in the center of that ring. Schlemm's canal SC has a
first major side 1250, a second major side 1252, a first minor side
1254, and a second minor side 1256. With reference to FIG. 18, it
will be appreciated that first major side 1250 is further from
pupil 1232 than second major side 1252. In the embodiment of FIG.
18, first major side 1250 is an outer major side of Schlemm's canal
SC and second major side 1252 is an inner major side of Schlemm's
canal SC.
[0147] In the embodiment of FIG. 18A, a distal portion of ocular
implant 12126 is shown resting in Schlemm's canal SC. A proximal
portion of ocular implant 12126 is shown extending out of Schlemm's
canal SC, through trebecular meshwork TM and into anterior chamber
AC. Ocular implant 12126 of FIG. 18 comprises a body having a first
major surface 12130 and a second major surface 12132. With
reference to FIG. 17, it will be appreciated that the body of
ocular implant 126 is curved about a longitudinal central axis so
that first major surface 12130 comprises a concave surface and
second major surface 12132 comprises a convex surface.
[0148] A distal portion of ocular implant 12126 defines a
longitudinal channel 12138 including a channel opening 12139.
Channel opening 12139 is disposed diametrically opposite a central
portion 12135 of first major surface 12130. In the embodiment of
FIG. 18A, ocular implant 12126 is assuming an orientation in which
channel opening 12139 is adjacent and open to first major side 50
of Schlemm's canal. In the embodiment of FIG. 18B, ocular implant
12126 is assuming an orientation in which channel opening 12139 is
adjacent and open to second major side 1252 of Schlemm's canal.
[0149] FIG. 19A, FIG. 19B and FIG. 19C illustrate multiple plan
views of an implant 12126 in accordance with the present detailed
description. FIG. 19A, FIG. 19B and FIG. 19C may be referred to
collectively as FIG. 19. It is customary to refer to multi-view
projections using terms such as front view, top view, and side
view. In accordance with this convention, FIG. 19A may be referred
to as a top view of implant 12126, FIG. 19B may be referred to as a
side view of implant 12126, and FIG. 19C may be referred to as a
bottom view of implant 12126. The terms top view, side view, and
bottom view are used herein as a convenient method for
differentiating between the views shown in FIG. 19. It will be
appreciated that the implant shown in FIG. 8 may assume various
orientations without deviating from the spirit and scope of this
detailed description. Accordingly, the terms top view, side view,
and bottom view should not be interpreted to limit the scope of the
invention recited in the attached claims.
[0150] Ocular implant 12126 of FIG. 19 comprises a body 12128 that
extends along a longitudinal central axis 12148. Body 12128 of
ocular implant 12126 has a first major surface 12130 and a second
major surface 12132. In the embodiment of FIG. 19, body 12128 is
curved about longitudinal central axis 12148 so that first major
surface 12130 comprises a concave surface 12136 and second major
surface 12132 comprises a convex surface 12134.
[0151] A distal portion of body 12128 defines a longitudinal
channel 12138 including a channel opening 12139. Channel opening
12139 is disposed diametrically opposite a central portion 12135 of
concave surface 12136. In the embodiment of FIG. 19, central
portion 12135 of concave surface 12136 defines a plurality of
apertures 12137. Each aperture 12137 fluidly communicates with
channel 12138. In some useful embodiments, body 12128 is adapted
and configured such that ocular implant 12126 assumes an
orientation in which channel opening 12139 is adjacent a major side
of Schlemm's canal when ocular implant 12126 is disposed in
Schlemm's canal.
[0152] FIG. 20 is a lateral cross-sectional view of ocular implant
12126 taken along section line A-A shown in the previous Figure.
Ocular implant 12126 comprises a body 12128 having a first major
surface 12130 and a second major surface 12132. With reference to
FIG. 20, it will be appreciated that body 12128 curves around a
longitudinal central axis 12148 so that first major surface 12130
comprises a concave surface 12136 and second major surface 12132
comprises a convex surface 12134. The concave surface 12136 of body
12128 defines a longitudinal channel 12138 having a channel opening
12139.
[0153] As shown in FIG. 20, channel 12138 has a width WD and a
depth DP. Body 12128 of ocular implant 12126 has a first lateral
extent EF and a second lateral extent ES. In some cases, body 12128
is adapted and configured such that ocular implant 12126
automatically assumes an orientation in which the channel opening
is adjacent a major side of Schlemm's canal when ocular implant
12126 is disposed in Schlemm's canal. In some useful embodiments,
an aspect ratio of first lateral extent EF to second lateral extent
ES is greater than about one. In some particularly useful
embodiments, the aspect ratio of first lateral extent EF to second
lateral extent ES is about two. In some useful embodiments, the
aspect ratio of first lateral extent EF to second lateral extent ES
is greater than about two. In some useful embodiments, an aspect
ratio of channel width WD to channel depth DP is greater than about
one. In some particularly useful embodiments, the aspect ratio of
channel width WD to channel depth DP is about two. In some useful
embodiments, the aspect ratio of channel width WD to channel depth
DP is greater than about two.
[0154] FIG. 21A is a perspective view of an ocular implant 12126
and FIG. 21B is a stylized perspective view showing Schlemm's canal
SC encircling an iris 1230. FIG. 21A and FIG. 21B may be
collectively referred to as FIG. 21. With reference to FIG. 21B, it
will be appreciated that Schlemm's canal SC may overhang iris 1230
slightly. Iris 1230 defines a pupil 1232. Schlemm's canal SC forms
a ring around iris 1230 with pupil 1232 disposed in the center of
that ring. With reference to FIG. 21B, it will be appreciated that
Schlemm's canal SC has a first major side 1250, a second major side
1252, a first minor side 1254, and a second minor side 1256. With
reference to FIG. 21B, it will be appreciated that first major side
1250 is further from pupil 1232 than second major side 1252. In the
embodiment of FIG. 21B, first major side 1250 is an outer major
side of Schlemm's canal SC and second major side 1252 is an inner
major side of Schlemm's canal SC.
[0155] For purposes of illustration, a window 1270 is cut through
first major side 1250 of Schlemm's canal SC in FIG. 21B. Through
window 1270, an ocular implant 12126 can be seen residing in a
lumen defined by Schlemm's canal. Ocular implant 12126 of FIG. 21
comprises a body 12128 having a first major surface 12130. First
major surface 12130 of body 12128 comprises a concave surface
12136. Body 12128 defines a longitudinal channel 12138 including a
channel opening 12139. Channel opening 12139 is disposed
diametrically opposite a central portion 12135 of concave surface
12136. In the embodiment of FIG. 21B, ocular implant 12126 is
assuming an orientation in which channel opening 12139 is adjacent
first major side 1250 of Schlemm's canal.
[0156] FIG. 22A is a perspective view showing a delivery system
12100 that may be used to advance an ocular implant 12126 into
Schlemm's canal of an eye. Delivery system 12100 includes a cannula
12102 that is coupled to a handle H. Cannula 12102 defines a distal
opening 21104. The distal portion of cannula 21102 of delivery
system 12100 is configured and adapted to be inserted into the
anterior chamber of a human subject's eye so that distal opening
12104 is positioned near Schlemm's canal of the eye. Cannula 12102
is sized and configured so that the distal end of cannula 21102 can
be advanced through the trabecular meshwork of the eye and into
Schlemm's canal. Positioning cannula 12102 in this way places
distal opening 12104 in fluid communication with Schlemm's
canal.
[0157] In the embodiment of FIG. 22A, an ocular implant is disposed
in a passageway defined by cannula 12102. Delivery system 12100
includes a mechanism that is capable of advancing and retracting
the ocular implant along the length of cannula 12102. The ocular
implant may be placed in Schlemm's canal of eye 1220 by advancing
the ocular implant through distal opening 12104 of cannula 12102
while distal opening 12104 is in fluid communication with Schlemm's
canal.
[0158] FIG. 22B is an enlarged detail view further illustrating
cannula 12102 of delivery system 12100. With reference to FIG. 22B,
it will be appreciated that cannula 12102 comprises a tubular
member defining a distal opening 12104, a proximal opening 12105,
and a passageway 12124 extending between proximal opening 12105 and
distal opening 12104. With reference to FIG. 22B, it will be
appreciated that cannula 12102 includes a curved portion 12107
disposed between distal opening 12104 and proximal opening
12105.
[0159] In the embodiment of FIG. 22B, an ocular implant 12126 is
disposed in passageway 12124 defined by cannula 12102. Ocular
implant 12126 of FIG. 22B comprises a body 12128 that extends along
a generally curved longitudinal central axis 12148. Body 12128 of
ocular implant 12126 has a first major surface 12130 and a second
major surface 12132. With reference to FIG. 22B, it will be
appreciated that body 12128 is curved about longitudinal central
axis 12148 so that first major surface 12130 defines a longitudinal
channel 12138 and second major surface 12132 comprises a convex
surface 12134. Longitudinal channel 12138 includes a channel
opening 12139. Ocular implant 12126 is orient relative to delivery
cannula 12102 such that longitudinal channel 12138 of ocular
implant 12126 opens in a radially outward direction RD when ocular
implant 12126 is disposed in curved portion 12107. Radially outward
direction RD is illustrated using an arrow in FIG. 22B. Distal
opening 12104 of cannula 12102 may be placed in fluid communication
with Schlemm's canal of an eye. Implant 12126 may be advanced
through distal opening 12104 and into Schlemm's canal while
assuming the orientation shown in FIG. 22B. When this is the case,
ocular implant 12126 may be oriented such that channel opening
12139 is adjacent an outer major side of Schlemm's canal when
ocular implant 12126 is disposed in Schlemm's canal.
[0160] FIG. 23 is an enlarged perspective view of an assembly 12106
including an ocular implant 12126, a sheath 12120, and a cannula
12102. For purposes of illustration, cannula 12102 is
cross-sectionally illustrated in FIG. 23. In the embodiment of FIG.
23, a sheath 12120 is shown extending into a passageway 12124
defined by cannula 12102. In FIG. 23, sheath 12120 is illustrated
in a transparent manner with a pattern of dots indicating the
presence of sheath 12120.
[0161] With reference to FIG. 23, it will be appreciated that an
implant 12126 is disposed in a lumen 12122 defined by sheath 12120.
Implant 12126 comprises a body 12128 having a first major surface
12130 and a second major surface 12132. In the embodiment of FIG.
23, body 12128 curves around a longitudinal central axis so that
first major surface 12130 comprises a concave surface and second
major surface 12132 comprises a convex surface 12134. The concave
surface of body 12128 defines a longitudinal channel 12138. In FIG.
23, a core 12166 is shown extending through longitudinal channel
12138.
[0162] Body 12128 of ocular implant 12126 defines a plurality of
openings 12140. In the embodiment of FIG. 23, sheath 12120 is
covering openings 12140. With reference to FIG. 23, it will be
appreciated that sheath 12120 comprises a proximal portion 12150
defining a lumen 12122 and a distal portion 12152 defining a distal
aperture 12154. Core 12166 is shown extending through distal
aperture 12154 in FIG. 23. In the embodiment of FIG. 23, distal
portion 12152 of sheath 12120 has a generally tapered shape.
[0163] FIG. 24 is an additional perspective view of assembly 12106
shown in the previous Figure. In FIG. 24, core 12166, sheath 12120,
and implant 12126 are shown extending through a distal port 12104
of cannula 12102. Core 12166, sheath 12120, and implant 12126 have
been moved in a distal direction relative to the position of those
elements shown in the previous Figure.
[0164] A push tube 12180 is visible in FIG. 24. In FIG. 24, a
distal end of push tube 12180 is shown contacting a proximal end of
implant 12126. In the embodiment of FIG. 24, push tube 12180 is
disposed in a lumen 12122 defined by sheath 12120. Sheath 12120
comprises a proximal portion 12150 defining a passageway 12124 and
a distal portion 12152 defining a distal aperture 12154. Implant
12126 is disposed in lumen 12122 defined by sheath 12120. In FIG.
24, core 12166 is shown extending through a channel 12138 defined
by implant 12126 and a distal aperture 12154 defined by distal
portion 12152 of sheath 12120.
[0165] FIG. 25 is an additional perspective view showing assembly
12106 shown in the previous Figure. With reference to FIG. 25, it
will be appreciated that implant 12126 is disposed outside of
cannula 12102. In the embodiment of FIG. 25, core 12166, sheath
12120, and push tube 12180 have been advanced further so that
implant 12126 is in a position outside of cannula 12102.
[0166] Methods in accordance with the present invention can be used
to deliver an implant into Schlemm's canal of an eye. In these
methods, a distal portion of core 12166 and sheath 12120 may be
advanced out of the distal port of cannula 12102 and into Schlemm's
canal. Ocular implant 12126 may be disposed inside sheath 12120
while the distal portion of the sheath 12120 is advanced into
Schlemm's canal. Sheath 12120 and core 12166 may then be retracted
while push tube 12180 prevents implant 12126 from being pulled
proximally.
[0167] FIG. 26 is an additional perspective view showing the
assembly 12106 shown in the previous Figure. In the embodiment of
FIG. 26, core 12166 and sheath 12120 have been moved in a proximal
direction relative to implant 12126. With reference to FIG. 26, it
will be appreciated that implant 12126 is now disposed outside of
sheath 12120. Some methods in accordance with the present detailed
description include the step of applying a proximally directed
force to sheath 12120 and core 12166 while providing a distally
directed reactionary force on implant 12126 to prevent implant
12126 from moving proximally. When this is the case, implant 12126
may pass through distal aperture 12154 of sheath 12120 as sheath
12120 is retracted over implant 12126.
[0168] In the embodiment of FIG. 26, distal portion 12152 of sheath
12120 comprises a first region 12156 and a second region 12158. The
frangible connection between first region 12156 and second region
12158 has been broken in the embodiment of FIG. 26. This frangible
connection may be selectively broken, for example, when sheath
12120 is moved in a proximal direction relative to implant 12126
due to the larger diameter of implant 12126 with respect to the
diameters of distal portion 12152 and opening 12154 of sheath
12120. With reference to FIG. 26, it will be appreciated that the
width of distal aperture 12154 becomes larger when the frangible
connection is broken.
[0169] With reference to the Figures described above, it will be
appreciated that methods in accordance with the present detailed
description may be used to position a distal portion of an implant
in Schlemm's canal of an eye. A method in accordance with the
present detailed description may include the step of advancing a
distal end of a cannula through a cornea of the eye so that a
distal portion of the cannula is disposed in the anterior chamber
of the eye. The cannula may be used to access Schlemm's canal, for
example, by piercing the wall of Schlemm's canal with a distal
portion of the cannula. A distal portion of a sheath may be
advanced out of a distal port of the cannula and into Schlemm's
canal. An ocular implant may be disposed inside the sheath while
the distal portion of the sheath is advanced into Schlemm's
canal.
[0170] In some useful methods, the ocular implant comprises a body
defining a plurality of apertures and the method includes the step
of covering the apertures with a sheath. When this is the case, the
distal portion of the implant may be advanced into Schlemm's canal
while the apertures are covered by the sheath. Covering the
apertures as the implant is advanced into Schlemm's canal may
reduce the trauma inflicted on Schlemm's canal by the procedure.
The apertures may be uncovered, for example, after the implant has
reached a desired location (e.g., inside Schlemm's canal).
[0171] The apertures of the implant may be uncovered, for example,
by moving the sheath in a proximal direction relative to the
implant. In some applications, this may be accomplished by applying
a proximal directed force to the sheath while holding the implant
stationary. The implant may be held stationary, for example, by
applying a distally directed reaction force on the implant. In one
embodiment, a distally directed reaction force is provided by
pushing on a proximal end of the implant with a push tube.
[0172] Some methods include the step of ceasing advancement of the
sheath into Schlemm's canal when a proximal portion of the implant
remains in an anterior chamber of the eye and a distal portion of
the implant lies in Schlemm's canal. When this is the case, only a
distal portion of the implant is advanced into Schlemm's canal. The
portion of the implant extending out of Schlemm's canal and into
the anterior chamber may provide a path for fluid flow between the
anterior chamber and Schlemm's canal.
[0173] An assembly may be created by placing a core in a channel
defined by the ocular implant. A sheath may be placed around the
implant and the core. For example, the core and the implant may
then be inserted into the lumen of a sheath. By way of another
example, the sheath may be slipped over the implant and the core.
The core may be withdrawn from the channel defined by the ocular
implant, for example, after the implant has been delivered to a
desired location.
[0174] The core may be withdrawn from the channel, for example, by
moving the core in a proximal direction relative to the implant. In
some applications, this may be accomplished by applying a proximal
directed force to the core while holding the implant stationary.
The implant may be held stationary, for example, by applying a
distally directed reaction force on the implant. In one embodiment,
a distally directed reaction force is provided by pushing on a
proximal end of the implant with a push tube.
[0175] The core, the implant, and the sheath may be advanced into
Schlemm's canal together. Once the implant is in a desired
location, the core and the sheath may be withdrawn from the
Schlemm's canal leaving the implant in the desired location. In
some methods, the core and the sheath are withdrawn from Schlemm's
canal simultaneously.
[0176] FIG. 27A and FIG. 27B are perspective views showing a sheath
12120 in accordance with the present detailed description. FIG. 27A
and FIG. 27B may be referred to collectively as FIG. 27. Sheath
12120 of FIG. 27 comprises a proximal portion 12150 defining a
lumen 12122 and a distal portion 12152 defining a distal aperture
12154. With reference to FIG. 27, it will be appreciated that lumen
12122 is generally larger than distal aperture 12154.
[0177] In the embodiment of FIG. 27A, distal portion 12152 of
sheath 12120 comprises a first region 12156, a second region 12158,
and a frangible connection 12160 between first region 12156 and
second region 12158. In FIG. 27A, a slit 12164 defined by distal
portion 12152 is shown disposed between first region 12156 and
second region 12158. In the embodiment of FIG. 27A, frangible
connection 12160 comprises a bridge 12162 extending across slit
12164.
[0178] In the embodiment of FIG. 27B, frangible connection 12160
has been broken. Frangible connection 12160 may be selectively
broken, for example, by moving sheath 12120 in a proximal direction
relative to an implant disposed in lumen 12122 having a diameter
larger than the diameters of distal opening 12154 and distal
portion 12152 of sheath 12120. With reference to FIG. 27, it will
be appreciated that distal aperture 12154 becomes larger when
frangible connection 12160 is broken.
[0179] In the embodiment of FIG. 27, the presence of slit 12164
creates a localized line of weakness in distal portion 12152 of
sheath 12120. This localized line of weakness causes distal portion
12152 to selectively tear in the manner shown in FIG. 27. It is to
be appreciated that distal portion 12152 may comprise various
elements that create a localized line of weakness without deviating
from the spirit and scope of the present detailed description.
Examples of possible elements include: a skive cut extending
partially through the wall of distal portion 12120, a series of
holes extending through the wall of distal portion 12120, a perf
cut, a crease, and a score cut.
[0180] FIG. 28 is a perspective view of an assembly including
sheath 12120 shown in the previous Figure. In the embodiment of
FIG. 28, an implant 12126 is shown extending through distal
aperture 12154 defined by distal portion 12152 of sheath 12120.
Implant 12126 defines a channel 12138. In FIG. 28, a core 12166 can
be seen resting in channel 12138. Implant 12126 and core 12166
extend proximally into lumen 12122 defined by sheath 12120. Distal
portion 12152 of sheath 12120 comprises a first region 12156 and a
second region 12158.
[0181] FIG. 29A and FIG. 29B are simplified plan views showing a
sheath 12120 in accordance with the present detailed description.
Sheath 12120 comprises a distal portion 12152 including a first
region 12156, a second region 12158 and a frangible connection
between first region 12156 and second region 12158. In the
embodiment of FIG. 19A, frangible connection 12160 is intact. In
the embodiment of FIG. 19B, frangible connection 12160 is broken.
FIG. 29A and FIG. 29B may be referred to collectively as FIG.
29.
[0182] Sheath 12120 of FIG. 29 comprises a proximal portion 12150
defining a lumen 12122. In the embodiment of FIG. 29, an implant
12126 is disposed in lumen 12122. Lumen 12122 fluidly communicates
with a distal aperture 12154 defined by distal portion 12152 of
sheath 12120. Distal portion 12152 includes a slit 12164 disposed
between first region 12156 and second region 12158. In FIG. 29A, a
bridge 12162 can be seen spanning slit 12164. In some useful
embodiments, distal portion 12152 of sheath 12120 has a first hoop
strength and proximal portion 12150 sheath 12120 has a second hoop
strength. The first hoop strength may be limited by the frangible
connection in the embodiment of FIG. 29A. When this is the case,
the second hoop strength is greater than the first hoop
strength.
[0183] Sheath 12120 of FIG. 29 comprises a proximal portion 12150
defining a lumen 12122 and a distal portion 12152 defining a distal
aperture 12154. Lumen 12122 has a lumen width LW. Distal aperture
has an aperture width AW when frangible connection 12160 is intact.
With reference to FIG. 29B, it will be appreciated that the distal
aperture 12154 is free to open further when frangible connection
12160 is broken.
[0184] In some useful embodiments, lumen width LW of lumen 12122 is
equal to or greater than the width of an implant 12126 disposed in
lumen 12122. In some of these useful embodiments, aperture width AW
is smaller than the width of the implant 12126. When this is the
case, frangible connection 12160 can be selectively broken by
moving sheath 12120 in a proximal direction relative to the implant
12126.
[0185] FIG. 30A, FIG. 30B and FIG. 30C are multiple plan views of
an implant 12326 in accordance with the present detailed
description. FIG. 30A, FIG. 30B and FIG. 30C may be referred to
collectively as FIG. 1309. FIG. 30A may be referred to as a top
view of implant 12326, FIG. 30B may be referred to as a side view
of implant 12326, and FIG. 30C may be referred to as a bottom view
of implant 12326. The terms top view, side view, and bottom view
are used herein as a convenient method for differentiating between
the views shown in FIG. 30. It will be appreciated that the implant
shown in FIG. 30 may assume various orientations without deviating
from the spirit and scope of this detailed description.
Accordingly, the terms top view, side view, and bottom view should
not be interpreted to limit the scope of the invention recited in
the attached claims.
[0186] Ocular implant 12326 of FIG. 30 comprises a body 12328 that
extends along a longitudinal central axis 12348. Body 12328 of
ocular implant 12326 has a first major surface 12330 and a second
major surface 12332. In the embodiment of FIG. 30, body 12328 is
curved about longitudinal central axis 12348 so that first major
surface 12330 comprises a concave surface 12336 and second major
surface 12332 comprises a convex surface 12334.
[0187] A distal portion of body 12328 defines a longitudinal
channel 12338 including a channel opening 12339. Channel opening
12339 is disposed diametrically opposite a central portion 12335 of
concave surface 12336. In the embodiment of FIG. 30, central
portion 12335 of concave surface 12336 defines a plurality of
apertures 12337. Each aperture 12337 fluidly communicates with
channel 12338.
[0188] FIG. 31 is a lateral cross-sectional view of ocular implant
12326 taken along section line B-B shown in the previous Figure.
Ocular implant 12326 comprises a body 12328 having a first major
surface 12330 and a second major surface 12332. With reference to
FIG. 31, it will be appreciated that body 12328 curves around a
longitudinal central axis 12348 so that first major surface 12330
comprises a concave surface 12336 and second major surface 12332
comprises a convex surface 12334. The concave surface 12336 of body
12328 defines a longitudinal channel 12338 having a channel opening
12339. As shown in FIG. 31, body 12328 has a circumferential extent
that spans an angle W. In the embodiment of FIG. 31, angle W has a
magnitude that is greater than one hundred eighty degrees.
[0189] FIG. 32 is a cross-sectional view showing an implant 12326
in accordance with the present detailed description. Ocular implant
12326 of FIG. 32 comprises a body 12328 that extends along a
generally curved longitudinal central axis 348. In the embodiment
of FIG. 32, body 12328 has a distal radius of curvature RD and a
proximal radius of curvature RP. Each radius of curvature is
represented with an arrow in FIG. 32. Distal radius of curvature RD
is represented by an arrow extending between a first lateral
central axis 12376 and a distal portion of longitudinal central
axis 12348. Proximal radius of curvature RP is represented by an
arrow extending between a second lateral central axis 12378 and a
proximal portion of longitudinal central axis 12348. In the
embodiment of FIG. 32, body 12328 of ocular implant 12326 has an at
rest shape that is generally curved. This at rest shape can be
established, for example, using a heat-setting process. The rest
shape of the implant can be generally aligned with the radius of
curvature of Schlemm's canal in a human eye.
[0190] FIG. 33A, FIG. 33B and FIG. 33C are multiple plan views of
an implant 12526 in accordance with the present detailed
description. FIG. 33A, FIG. 33B and FIG. 33C may be referred to
collectively as FIG. 33. FIG. 33A may be referred to as a top view
of implant 12526, FIG. 33B may be referred to as a side view of
implant 12526, and FIG. 33C may be referred to as a bottom view of
implant 12526. The terms top view, side view, and bottom view are
used herein as a convenient method for differentiating between the
views shown in FIG. 33. It will be appreciated that the implant
shown in FIG. 33 may assume various orientations without deviating
from the spirit and scope of this detailed description.
[0191] Accordingly, the terms top view, side view, and bottom view
should not be interpreted to limit the scope of the invention
recited in the attached claims.
[0192] Ocular implant 12526 of FIG. 33 comprises a body 12528 that
extends along a longitudinal central axis 12548. Body 12528 of
ocular implant 12526 has a first major surface 12530 and a second
major surface 12532. In the embodiment of FIG. 33, body 12528 is
curved about longitudinal central axis 12548 so that first major
surface 12530 comprises a concave surface 12536 and second major
surface 12532 comprises a convex surface 12534.
[0193] A distal portion of body 12528 defines a longitudinal
channel 12538 including a channel opening 12539. Channel opening
12539 is disposed diametrically opposite a central portion 12535 of
concave surface 12536. In the embodiment of FIG. 33, central
portion 12535 of concave surface 12536 defines a plurality of
apertures 12537. Each aperture 12537 fluidly communicates with
channel 12538.
[0194] FIG. 34 is a lateral cross-sectional view of ocular implant
12526 taken along section line C-C shown in the previous Figure.
Ocular implant 12526 comprises a body having a first major side
12530 and a second major side 12532. With reference to FIG. 34, it
will be appreciated that body 12528 curves around a longitudinal
central axis 1248 so that first major side 12530 comprises a
concave surface 12536 and second major side 12532 comprises a
convex surface 12534. The concave surface 12536 of body 12528
defines a longitudinal channel 12538 having a channel opening
12539. As shown in FIG. 34, body 12528 has a circumferential extent
that spans an angle C. In the embodiment of FIG. 34, angle C has a
magnitude that is about one hundred eighty degrees. Some useful
implants in accordance with the present detailed description
comprise a body having a circumferential extend that spans an angle
that is about one hundred eighty degrees. Some particularly useful
implants in accordance with the present detailed description
comprise a body having a circumferential extend that spans an angle
that is equal to or less than one hundred eighty degrees.
[0195] FIG. 35 is a plan view showing an implant 12526 in
accordance with the present detailed description. Ocular implant
12526 of FIG. 35 comprises a body 12528 that extends along a
generally curved longitudinal central axis 12548. In the embodiment
of FIG. 35, body 12528 has a distal radius of curvature RD and a
proximal radius of curvature RP. Each radius of curvature is
represented with an arrow in FIG. 35. Distal radius of curvature RD
is represented by an arrow extending between a first lateral
central axis 12576 and a distal portion of longitudinal central
axis 12548. Proximal radius of curvature RP is represented by an
arrow extending between a second lateral central axis 12578 and a
proximal portion of longitudinal central axis 12548. In the
embodiment of FIG. 35, body 12528 of ocular implant 12526 has an at
rest shape that is generally curved. This at rest shape can be
established, for example, using a heat-setting process.
[0196] FIG. 36A through FIG. 36D are a series of plan views
illustrating a method in accordance with the present detailed
description. FIG. 36A is a plan view showing an implant 12426.
Implant 12426 comprises a body 12428 defining a plurality of
openings 12440. Openings 12440 include a first opening 12442 and a
second opening 12444.
[0197] FIG. 36B is a plan view showing an assembly 12408 including
implant 12426. Assembly 12408 of FIG. 36B may be created by placing
a core 12406 in a channel 12438 defined by implant 12426. A sheath
12420 may be placed around implant 12426 and core 12406. For
example, core 12406 and implant 12426 may be inserted into a lumen
defined by sheath 12420. By way of another example, sheath 12420
may be slipped over implant 12426 and core 12406.
[0198] FIG. 36C is a plan view showing assembly 12408 disposed in
Schlemm's canal SC. The wall W of Schlemm's canal SC comprises a
plurality of cells 1290. With reference to FIG. 36C, it will be
appreciated that sheath 12420 is disposed between implant 12426 and
cells 1290. A method in accordance with the present detailed
description may include the step of advancing a distal end of a
cannula through a cornea of the eye so that a distal portion of the
cannula is disposed in the anterior chamber of the eye. The cannula
may be used to access Schlemm's canal, for example, by piercing the
wall of Schlemm's canal with a distal portion of the cannula. A
distal portion of sheath 12420 may be advanced out of a distal port
of the cannula and into Schlemm's canal SC. Ocular implant 12426
may be disposed inside sheath 12420 while the distal portion of
sheath 12420 is advance into Schlemm's canal SC.
[0199] In the embodiment of FIG. 36C, ocular implant 12426
comprises a body defining a plurality of openings 12440. With
reference to FIG. 36C, it will be appreciated that openings 12440
are covered by sheath 12420 and that a distal portion of implant
12426 may be advanced into Schlemm's canal while openings 12440 are
covered by sheath 12420. Covering openings 12440 as implant 12426
is advanced into Schlemm's canal SC may reduce the trauma inflicted
on cells 1290 by the procedure.
[0200] In some useful embodiments, sheath 12420 comprises a coating
disposed on an outer surface thereof. The properties of the coating
may be selected to further reduce the trauma inflicted on cells
1290 by the procedure. The coating may comprise, for example, a
hydrophilic material. The coating may also comprise, for example, a
lubricious polymer. Examples of hydrophilic materials that may be
suitable in some applications include: polyalkylene glycols, alkoxy
polyalkylene glycols, copolymers of methylvinyl ether and maleic
acid poly(vinylpyrrolidone), poly(N-alkylacrylamide), poly(acrylic
acid), poly(vinyl alcohol), poly(ethyleneimine), methyl cellulose,
carboxymethyl cellulose, polyvinyl sulfonic acid, heparin, dextran,
modified dextran and chondroitin sulphate.
[0201] In FIG. 36C, the distal portion of sheath 12420 is shown
extending between a smaller, distal diameter and a larger, proximal
diameter. In the embodiment of FIG. 36C, the distal portion of
sheath 12420 has a generally tapered shape. The tapered transition
of the distal portion of sheath 12420 may create a nontraumatic
transition that dilates Schlemm's canal SC as sheath 12420 is
advanced into Schlemm's canal SC. This arrangement may reduce the
likelihood that skiving of wall W occurs as sheath 12420 is
advanced into Schlemm's canal SC.
[0202] FIG. 36D is a plan view showing implant 12426 disposed in
Schlemm's canal SC. In the embodiment of FIG. 36D, openings 12440
defined by body 12428 have been uncovered. Openings 12440 may be
uncovered, for example, by moving sheath 12420 in a proximal
direction relative to implant 12426. In some applications, this may
be accomplished by applying a proximal directed force to sheath
12420 while holding implant 12426 stationary. Implant 12426 may be
held stationary, for example, by applying a distally directed
reaction force on implant 12426. In the embodiment of FIG. 36, a
distally directed reaction force may be provided by pushing on a
proximal end of implant 12426 with a push tube.
[0203] In the embodiment of FIG. 36D, core 12406 has been removed
channel 12438 defined by implant 12426. Core 12406 may be withdrawn
from channel 12438, for example, by moving core 12406 in a proximal
direction relative to implant 12426. In some applications, this may
be accomplished by applying a proximal directed force to core 12406
while holding implant 12426 stationary. Implant 12426 may be held
stationary, for example, by applying a distally directed reaction
force on implant 12426.
[0204] FIG. 37A through FIG. 37D are a series of section views
illustrating a method in accordance with the present detailed
description. The picture plane of FIG. 37A extends laterally across
Schlemm's canal SC and the trabecular meshwork 12596 overlaying
Schlemm's canal SC. In the embodiment of FIG. 37A, the distal end
of a cannula 12502 has been positioned proximate Schlemm's canal
SC. A method in accordance with the present detailed description
may include the step of advancing the distal end of cannula 12502
through the cornea of an eye so that a distal portion of cannula
12502 is disposed in the anterior chamber 12594 of the eye.
[0205] FIG. 37B is an additional section view showing Schlemm's
canal SC shown in the previous Figure. In FIG. 37B, a distal
portion of cannula 502 is shown extending through a wall W of
Schlemm's canal SC and trabecular meshwork 12596. A distal port
12504 of cannula 12502 fluidly communicates with Schlemm's canal in
the embodiment of FIG. 37B.
[0206] FIG. 37C is an additional section view showing Schlemm's
canal SC shown in the previous Figure. In the embodiment of FIG.
37C, a distal portion of a sheath 12520 is shown extending through
distal port 12504 of cannula 12502 and into Schlemm's canal SC.
Methods in accordance with the present invention can be used to
deliver an implant 12526 into Schlemm's canal SC. In these methods,
a distal portion of sheath 12520 and a core 12506 may be advanced
out of distal port 12504 of cannula 12502 and into Schlemm's canal
SC. Ocular implant 12526 may be disposed inside sheath 12520 while
the distal portion of sheath 12520 is advanced into Schlemm's canal
SC.
[0207] FIG. 37D is an additional section view showing implant 12526
shown in the previous Figure. In the embodiment of FIG. 37D, sheath
12520, core 12506, and cannula 12502 have all been withdrawn from
the eye. Implant 12526 is shown resting in Schlemm's canal SC in
FIG. 37D.
[0208] FIG. 38A and FIG. 38B are simplified plan views showing a
sheath 12720 in accordance with the present detailed description.
FIG. 38A and FIG. 38B may be referred to collectively as FIG. 38.
Sheath 12720 of FIG. 38 comprises a proximal portion 12750 defining
a lumen 12722 and a distal portion 12752 defining a distal aperture
12754. With reference to FIG. 38, it will be appreciated that lumen
12722 is generally larger than distal aperture 12754.
[0209] In the embodiment of FIG. 38A, distal portion 12752 of
sheath 12720 comprises a first region 12756, a second region 12758,
and a frangible connection 12760 between first region 12756 and
second region 12758. In FIG. 38A, a first slit 12764 defined by
distal portion 12752 is shown disposed between first region 12756
and second region 12758. In the embodiment of FIG. 38A, frangible
connection 12760 comprises a bridge 12762 extending across first
slit 12764. With reference to FIG. 38A, it will be appreciated that
distal portion 12752 defines a number of slits in addition to first
slit 12764.
[0210] In the embodiment of FIG. 38B, frangible connection 12760
has been broken. Frangible connection 12760 may be selectively
broken, for example, by moving sheath 12720 in a proximal direction
relative to an implant disposed in lumen 12722 having a diameter
larger than the diameters of distal opening 12754 and distal
portion 12752 of sheath 12720. With reference to FIG. 38, it will
be appreciated that distal aperture 12754 becomes larger when
frangible connection 12760 is broken.
[0211] In the embodiment of FIG. 38, the presence of slit 12764
creates a localized line of weakness in distal portion 12752 of
sheath 12720. This localized line of weakness causes distal portion
12752 to selectively tear in the manner shown in FIG. 38. It is to
be appreciated that distal portion 12752 may comprise various
elements that create a localized line of weakness without deviating
from the spirit and scope of the present detailed description.
Examples of possible elements include: a skive cut extending
partially through the wall of distal portion 12720, a series of
holes extending through the wall of distal portion 12720, a pert
cut, a crease, and a score cut.
[0212] In FIG. 38, distal portion 12752 of sheath 12720 is shown
extending between distal opening 12754 and lumen 12722. In the
embodiment of FIG. 38, distal portion 12752 of sheath 12720 has a
blunt shape. The blunt shape of distal portion 12752 of sheath
12720 may create a nontraumatic transition that dilates Schlemm's
canal as sheath 12720 is advanced into Schlemm's canal. This
arrangement may reduce the likelihood that skiving of the canal
wall occurs as sheath 12720 is advanced into Schlemm's canal.
[0213] Various fabrication techniques may be used to fabricate the
ocular implant. For example, the ocular implant can be fabricated
by providing a generally flat sheet of material, cutting the sheet
of material, and forming the material into a desired shape. By way
of a second example, the ocular implant may be fabricated by
providing a tube and laser cutting openings in the tube to form the
ocular implant.
[0214] The ocular implant of this invention can be fabricated from
various biocompatible materials possessing the necessary structural
and mechanical attributes. Both metallic and non-metallic materials
may be suitable. Examples of metallic materials include stainless
steel, tantalum, gold, titanium, and nickel-titanium alloys known
in the art as Nitinol. Nitinol is commercially available from Memry
Technologies (Brookfield, Conn.), TiNi Alloy Company (San Leandro,
Calif.), and Shape Memory Applications (Sunnyvale, Calif.).
[0215] The ocular implant may include one or more therapeutic
agents. One or more therapeutic agents may, for example, be
incorporated into a polymeric coating that is deposited onto the
outer surfaces of the struts and spines of the ocular implant. The
therapeutic agent may comprise, for example, an anti-glaucoma drug.
Examples of anti-glaucoma drugs include prostaglandin analogs.
Examples of prostaglandin analogs include latanprost.
[0216] The implants of the present disclosure provide a treatment
for glaucoma by combining the mechanism of trabecular meshwork (TM)
bypass and Schlemm's canal (SC) dilation. The trabecular meshwork
bypass is achieved through the openings, the longitudinal channel,
and channel opening of the implants above, and Schlemm's canal
dilation is achieved by supporting Schlemm's canal with the body of
the implant itself.
[0217] A comprehensive mathematical model was developed in this
disclosure to evaluate changes in fluid dynamics of aqueous humor
outflow induced by combinations of trabecular mesh bypass and/or
Schlemm's canal dilation, and to predict how the changes would
affect outflow facility. First, a control eye was modeled after an
ex vivo human anterior segment perfusion model using typical
dimensions for the eye and Schlemm's canal. This was done in order
to validate the model parameters with experimental data. Next, two
combinations of bypass and dilation were modeled using the
dimensional parameters of implants with 8 mm and 16 mm lengths. The
mathematical model was used to predict outflow facilities in
control and experimental simulations.
[0218] The mathematical model was developed to numerically simulate
aqueous humor outflow based on the assumptions and physical
principles that govern fluid flow. Schlemm's canal is modeled as a
rectangular channel with width (w) and height (h), where h varies
with the location (x) along the canal due to trabecular mesh
deformation. The trabecular mesh is treated as an elastic membrane
in the model. The ostia of collector channels (CC) are distributed
uniformly along the outer wall of Schlemm's canal with the first
collector channel located at x=0.6 mm or 0=6.degree.. Collector
channels are treated as individual sinks with flow rate, J.sub.CC
(see the governing equation below). Schlemm's canal in the
experimental simulations is modeled after either an 8 mm implant or
16 mm implant. The region of Schlemm's canal with an implant is
also modeled as a rectangular channel but with width (w.sub.d) and
height (h.sub.d) corresponding to the implant cross-sectional
area.
[0219] The height of Schlemm's canal (h) is intra-ocular pressure
(IOP) dependent. The dependence is assumed to be linear:
h=h.sub.0*(1-IOP-PSCE) (1)
[0220] Across the trabecular meshwork, the aqueous humor flux
(J.sub.TM) is dependent on the trabecular mesh resistance
(R.sub.TM) and is governed by:
J TM = IOP - P SC R TM ( 2 ) dP dx = 12 .mu. wh 3 Q ( 3 ) dQ dx = -
J CC ( x - x CC ) ( 4 ) J CC = P SC - P epi R CC ( x CC ) ( 5 )
##EQU00001##
[0221] In these equations, P.sub.sc is the fluid pressure in the
Schlemm's canal, E is the Young's modulus of the trabecular
meshwork, h.sub.0 is the value of h when intra-ocular
pressure=P.sub.sc, R.sub.TM is the trabecular meshwork's resistance
to fluid flow, Q is the flow rate along the SC, .mu. is the
viscosity of aqueous humor, x.sub.cc indicates locations of
collector channel ostia in the Schlemm's canal, J.sub.CC is the
flow rate in the collector channels, P.sub.epi is the pressure in
the episcleral veins, and R.sub.CC is the flow resistance of
collector channels that may depend on x.sub.cc. Since Schlemm's
canal is a ring-like channel, the boundary conditions at x=0 for
P.sub.sc and Q are the same as those at x=L, where L is the
circumferential length of Schlemm's canal.
[0222] In simulations with an implant such as those described
herein, a portion of Schlemm's canal is stretched open. The implant
inlet is assumed to be a uni-directional fluid source with zero
flow resistance P.sub.sc=IOP. The implant is modeled as a channel
with three side walls, leaving the side facing the outer wall of
Schlemm's canal open. For example, FIGS. 7A-7B show an implant
having three "walls" comprising first strut 144, second strut 146,
and spine 140 which leaves opening or channel 124 open and facing
Schlemm's canal when implanted. The wall of the implant facing the
inner wall of Schlemm's canal (spine 140) contains several windows
(or openings), which allow the aqueous humor to enter SC through
the TM.
[0223] Two scaffold designs are investigated in this disclosure.
One has a total length of 8 mm with 3 windows and 3 spines (shown
in FIGS. 2, 4, 11, 17, 19A-C, 30A-C, 32, 33A-C, 35); and another
has a total length of 16 mm with 5 windows and 6 spines (shown in
FIG. 6, 10, 21A). Individual dimensions of 8 mm and 16 mm implants
are shown in Table 2A and 2B, respectively. The governing equations
for the region of SC without the scaffold and R.sub.TM in window
regions are equal to control parameters listed in Section (a). In
the spine regions, Equations 1 and 2 are replaced by h=h.sub.s and
J.sub.TM=0, respectively. Equations 3 through 5 are unchanged,
excepted that w and h are replaced with h.sub.d and w.sub.d,
respectively. The boundary conditions are given as IOP=P.sub.sc at
x=0 and Q=0 at x=L. Additionally, P.sub.sc and Q are continuous at
the distal end of the scaffold.
[0224] The baseline values of the constants are given in Table
1.
TABLE-US-00001 TABLE 1 Universal Parameters Parameter Description
Value h.sub.0 Intrinsic Height of SC 20 .mu.m w Width of SC 230
.mu.m L Length of SC 36 mm E Young's modulus of TM 30 mmHg .DELTA.P
IOP - P.sub.epi 5 .ltoreq. .DELTA.P .ltoreq. 30 mmHg N.sub.CC
Number of CCs 30 R.sub.TM TM Resistance to Flow 9 cm
mmHg/(.mu.l/min) R.sub.CC Resistance to flow in CC 2.5*N.sub.CC
mmHg/(.mu.l/min) .beta. Ratio of RCC in control 3 SC vs. SC with TM
bypass .mu. Viscosity of AH 7.5 .times. 10.sup.-4 kg/(m sec) or
0.75 cP
[0225] Dimensions of the implants shown in Table 2A-2B are
estimated based on the actual sizes except width.
TABLE-US-00002 TABLE 2A Geometric Parameters of 8 mm implant
Parameter Description Value A.sub.w Area of window region 17553
.mu.m.sup.2 A.sub.s Area of spine region 22955 .mu.m.sup.2 A.sub.in
Area of inlet region 29841 .mu.m.sup.2 h.sub.w Height of window
region 76.3 .mu.m h.sub.s Height of spine region 99.8 .mu.m
h.sub.in Height of inlet region 129.7 .mu.m L.sub.w Length of
window region 1.1 mm N.sub.w Number of windows 3 w.sub.d Width of
device 230 .mu.m L.sub.in Length of inlet spine region 1.1 mm
L.sub.dev Length of device in SC 7.2 mm L.sub.s Length of spine
region 0.9 mm
TABLE-US-00003 TABLE 2B Geometric Parameters of 16 mm implant
Parameter Description Value A.sub.w Area of window region 20994
.mu.m.sup.2 A.sub.s Area of spine region 32092 .mu.m.sup.2 A.sub.in
Area of inlet region 29841 .mu.m.sup.2 h.sub.w Height of window
region 91.3 .mu.m h.sub.s Height of spine region 139.5 .mu.m
h.sub.in Height of inlet region 129.7 .mu.m L.sub.w Length of
window region 1 mm N.sub.w Number of windows 5 w.sub.d Width of
device 230 .mu.m L.sub.in Length of inlet spine region 1.1 mm
L.sub.dev Length of device in SC 15 mm L.sub.s Length of spine
region 1.5 mm
[0226] For simplicity, the width of all implants are assumed to be
the same as that of the intact Schlemm's canal; and the height of
each implant is calculated from the cross-sectional areas estimated
for that device divided by w.sub.d. In Table 1, the viscosity of
aqueous humor (.mu.) at 37.degree. C. is assumed to be the same as
that measured at 34.degree. C., because .mu. is close to the
viscosity of water which changes only slightly (.about.6%) when the
temperature is increased from 34.degree. C. to 37.degree. C. The
pressure in the episcleral vein (P.sub.epi) is close to zero in
experiments involving ex vivo perfusion of whole eye or anterior
segment, but approximately equal to 8 mmHg in live eyes. In order
to apply conclusions obtained from this mathematical model to both
types of studies, .DELTA.P was varied between 5 and 30 mmHg, where
.DELTA.P=IOP-P.sub.epi, instead of changing the absolute value of
IOP. Implantation of a bypass causes a significant increase in the
pressure in this region of Schlemm's canal and can lead to an
increase in the diameter of collector channel ostia in the region.
To account for diameter increase-induced decrease in outflow
resistance in collector channels, a parameter, .beta., can be
defined as the ratio of R.sub.CC with ostia in control Schlemm's
canal versus that in dilated Schlemm's canal. The value of .beta.,
which is >1, depends on how the three-dimensional shape of the
collector channel is changed due to Schlemm's canal dilation and
pressure increase, which is unknown at present. If the collector
channel is considered as a circular channel, and its diameter is
uniformly increased by a factor of two, then .beta. equals 16 for
Newtonian fluid. However, it is likely that only the portion of the
collector channel near its ostium is be dilated after device
implantation. Thus, a baseline value of .beta. is assumed to be
three.
[0227] In control simulations, with the frequent and uniform
distribution of collector channel ostia in Schlemm's canal, the
pressure difference between Schlemm's canal and episcleral venous
pressure (Psc-P.sub.epi) showed negligible variation. This resulted
in negligible circumferential flow along Schlemm's canal. When the
pressure drop between the anterior chamber and episcleral veins
(.DELTA.P) was fixed at different pressures, ranging from 5 to 30
mmHg, the shapes of these profiles varied only slightly although
their magnitudes were increased significantly. Therefore, only the
profiles at 10 mmHg are shown in this disclosure. The total sum of
the flow rates through the collector channels per unit .DELTA.P is
defined as the outflow facility (C). The average C of the control
eye was 0.198 .mu.l/min/mmHg (Table 3). When .DELTA.P is increased
from 5 to 30 mmHg, C decreased slightly in the control simulation
with TM intact, which falls within the range of experimental data
of human eyes reported in the literature.
TABLE-US-00004 TABLE 3 Simulated Outflow Facility Simulation
Average Outflow Facility Control 0.198 8 mm implant 0.438 16 mm
implant 0.638
[0228] FIG. 39 illustrates the results of mathematical simulations
of the 8 mm and 16 mm implants with frequent and uniform
circumferential distribution of collector channels and an IOP of 10
mmHg. In FIG. 39, solid line 390 represents the P.sub.sc in
Schlemm's canal of the eye with the 8 mm implant, and dashed-line
392 represents the P.sub.sc in Schlemm's canal of the eye with the
16 mm implant. Circles 394 illustrate the flow in the collector
channels of the eye with the 8 mm implant, and triangles 396 show
the flow in the collector channels of the eye with the 16 mm
implant. In the simulations, the pressure in the region of
Schlemm's canal (P.sub.sc) with the implants was similar to IOP.
Outside this region, P.sub.sc decreased exponentially, starting at
the distal end of the implants, with the smallest level of P.sub.sc
slightly greater than controls.
[0229] Consequently, the outflow rate through the collector
channels (J.sub.cc) was highest in the implant regions due to the
high P.sub.sc and Schlemm's canal dilation-induced reduction in
outflow resistance in these collector channels. Outside this
region, the profile of Jcc matched the Psc profile and was similar
for both implants. The collector channels in the scaffold regions
contributed to a majority of the overall difference in flow rate
through collector channels when compared to controls. The average C
value for the 8 mm implant was 121% greater than controls with a C
value of 0.438 .mu.l/min/mmHg and the 16 mm implant was 46% greater
than the 8 mm implant (222% greater than controls) with a C value
of 0.638 .mu.l/min/mmHg (Table 3 above). However, the 16 mm implant
reached twice as many collector channels as the 8 mm implant but
only gained 46% greater outflow despite the addition of 6 collector
channels. This indicates that as the distance from the collector
channels to the inlet increases, the benefit to outflow facility
diminishes.
[0230] Significant circumferential flow was observed adjacent to
the trabecular meshwork bypass not seen in control simulations. The
peak circumferential flow rate was 3.2 .mu.l/min with the 8 mm
implant and 5.7 .mu.l/min with the 16 mm implant. The magnitude of
the circumferential flow indicates a significant portion of the
total outflow passed through the trabecular mesh bypass inlet. The
circumferential flow rate peaked at the position of the bypass and
decreased with a linear step pattern in the implant region. At the
distal end of the scaffold, the circumferential flow rate decreased
exponentially until it reached zero, as shown in FIG. 40, in which
line 490 illustrates flow in Schlemm's canal in the 8 mm implant
and line 492 illustrates flow in Schlemm's canal in the 16 mm
implant. The circumferential flow region correlates to the regions
of increased P.sub.sc and J.sub.cc for both the 8 mm and 16 mm
implant. Throughout the first 90 degrees of Schlemm's canal, the 16
mm implant maintained a 2.415 .mu.l/min flow difference versus the
8 mm implant. But when 150 degrees of Schlemm's canal is reached,
the difference is reduced to only 0.526 .mu.l/min, indicating a
diminishing advantage with a longer length device.
[0231] Calculations of the percentage of total aqueous humor
outflow through collector channels within an implant region
indicate that the longer the implanted region the greater the
percentage of total outflow (Table 4).
TABLE-US-00005 TABLE 4 Percent of Total Outflow Through Collector
Channels in Schlemm's Canal regions with Implants Percent of
Schlemm's Average Percent of Total Type of Implant Canal Occupied
Outflow in Implant Region 8 mm implant 20% 54.5% 16 mm implant 40%
74.6%
[0232] The 8 mm implant occupied three clock-hours of Schlemm's
canal (20% of Schlemm's canal length), however the collector
channels in that region accounted for 54.5% of the total outflow in
the eye. The 16 mm implant occupied five clock-hours of Schlemm's
canal (42% of Schlemm's canal length) which accounted for 74.6% of
the total outflow. These results indicate that a significant
portion of total outflow is diverted into the implant area and
drains out collector channels adjacent to the implant. The more
collector channels adjacent to the implant the larger a percentage
of total outflow. Likewise, a segmental variation of the collector
channel patency would make the outflow facility results dependent
on implant location.
[0233] Theoretical in vivo glaucoma scenarios were designed to
simulate how different ocular implants could improve outflow in
eyes with increased trabecular meshwork resistance (RTM) and
reduced collector channel outflow capacity in the hemisphere of the
implant. Three scenarios were simulated in Table 5, with fixed
conventional outflow rate of 1.5 .mu.L/min 27, 28 and Pepi of 10
mmHg.
TABLE-US-00006 TABLE 5 Theoretical Glaucoma Scenarios R.sub.TM
Collector Channels in Theoretical Scenario (mmHg/.mu.l/min) Implant
Hemisphere Normal 2.12 Zero Blocked Glaucoma Case #1 6.34 50%
Blocked Glaucoma Case #2 8.78 75% Blocked
[0234] The first scenario was a normal eye, which assumed R.sub.TM
to be 2.12 mmHg/4/min and no blocked collector channels. The second
scenario assumed R.sub.TM to be 6.34 mmHg/4/min and 50% of the
collector channels in the implanted hemisphere to be uniformly
blocked including the collector channels at the trabecular mesh
bypass. The third scenario assumed R.sub.TM to be 8.78 mmHg/4/min
and 75% of the collector channels in the implanted hemisphere to be
uniformly blocked including the collector channel at the trabecular
meshwork bypass. Simulation results showed that in the control eye
without implant, the intra-ocular pressures under these scenarios
were 17, 25 and 30 mmHg, respectively, and based on the Goldmann
equation, the corresponding outflow facilities were 0.214, 0.100
and 0.075 .mu.L/min/mmHg, respectively. Implantation of the 8 mm
implant would improve the simulated outflow facility to 0.450,
0.240 and 0.171 .mu.L/min/mmHg, or reduce IOPs to 13.3, 16.3 and
18.8 mmHg, respectively. When compared to the control simulations,
the 8 mm implant resulted in IOP reductions of 22%, 35% and 37%,
respectively.
[0235] The model shows the effects of trabecular meshwork bypass
and Schlemm's canal dilation on outflow facility and subsequent IOP
reduction. In analysis of the dilation length, increasing the
dilated portion of Schlemm's canal from the bypass improved outflow
facility. But, at a certain distance from the bypass there was
diminished improvement. This indicates that dilation near the
bypass creates circumferential flow from the bypass which allows
more collector channels to be utilized.
[0236] Fluid dynamic mathematical modeling of scaffolding ocular
implants as described herein shows that bypassing the trabecular
meshwork increases the pressure within Schlemm's canal, and
increases circumferential flow rate, and the flow rate into
collector channels adjacent to the trabecular meshwork bypass. The
larger bypass size creates a larger increase in the circumferential
flow when compared with controls. Dilation of Schlemm's canal
adjacent to the trabecular meshwork bypass increases the pressure
in Schlemm's canal in the area of dilation which further increases
the circumferential flow. Increasing the length of dilation
increases the number of collector channels accessed by the implant,
however, there was diminishing improvement in circumferential flow
and flow rate into collector channels over a distance of
approximately one quadrant in the eye beyond the region with the
implant. When trabecular meshwork resistance was increased and
collector channels were closed segmentally to simulate glaucoma,
the dependence on the location of trabecular meshwork bypass to
collector channels and the dilation length of Schlemm's canal was
more pronounced.
[0237] While exemplary embodiments of the present invention have
been shown and described, modifications may be made, and it is
therefore intended in the appended claims to cover all such changes
and modifications which fall within the true spirit and scope of
the invention.
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