U.S. patent application number 11/502603 was filed with the patent office on 2007-08-02 for surgical support structure.
Invention is credited to Arthur G. Erdman, Paul E. Loftness, Timothy W. Olsen.
Application Number | 20070179512 11/502603 |
Document ID | / |
Family ID | 37488086 |
Filed Date | 2007-08-02 |
United States Patent
Application |
20070179512 |
Kind Code |
A1 |
Olsen; Timothy W. ; et
al. |
August 2, 2007 |
Surgical support structure
Abstract
This document discusses, among other things, a system for
translocating a multilayer patch. The system includes a support
structure having a contact surface for bonding to the patch. The
support structure has a shape configured to support the patch
following separation of the patch from a surrounding tissue.
Inventors: |
Olsen; Timothy W.; (Eden
Prairie, MN) ; Loftness; Paul E.; (Gibbon, MN)
; Erdman; Arthur G.; (New Brighton, MN) |
Correspondence
Address: |
SCHWEGMAN, LUNDBERG, WOESSNER & KLUTH, P.A.
P.O. BOX 2938
MINNEAPOLIS
MN
55402
US
|
Family ID: |
37488086 |
Appl. No.: |
11/502603 |
Filed: |
August 9, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60763536 |
Jan 31, 2006 |
|
|
|
Current U.S.
Class: |
606/151 |
Current CPC
Class: |
A61F 2/14 20130101; A61B
18/04 20130101; A61F 9/00727 20130101; A61B 18/20 20130101; A61B
2017/00867 20130101; A61F 9/00821 20130101 |
Class at
Publication: |
606/151 |
International
Class: |
A61B 17/08 20060101
A61B017/08 |
Claims
1. A system for translocating a multilayer patch of choroid,
Bruch's membrane, and retinal pigment epithelium (RPE), the system
comprising: a support structure having a contact surface for
bonding to the patch, the support structure having a shape
configured to support the patch following separation of the patch
from a surrounding tissue.
2. The system of claim 1 further including a tool configured to
engage the support structure.
3. The system of claim 1 further including a cannula having at
least one lumen, wherein the lumen is configured to pass the
support structure.
4. The system of claim 1 wherein the support structure includes at
least one ring shaped member.
5. The system of claim 1 wherein the support structure is
configured to permanently bond to the patch.
6. The system of claim 1 wherein the support structure is
configured for removal following translocation of the patch.
7. A system comprising: a support structure having a tissue contact
surface configured to bond to a tissue and configured to maintain a
fixed shape of the tissue after separation of the tissue from a
membrane.
8. The system of claim 7 wherein the support structure has a
circular configuration.
9. The system of claim 7 wherein the support structure includes a
first member and a second member, each member of which is adapted
to engage with the other.
10. The system of claim 9 wherein the first member includes a
tongue and the second member includes a groove.
11. The system of claim 7 wherein the support structure includes at
least one ring.
12. The system of claim 11 wherein the at least one ring is
endless.
13. The system of claim 11 wherein the at least one ring contacts
two opposing surfaces of the membrane.
14. The system of claim 7 wherein the support structure includes at
least one of stainless steel, nitinol, a polymer, a shape memory
material, a superelastic material, and a bioerodable material.
15. The system of claim 7 wherein the support structure includes at
least one of a textured surface and a porous surface.
16. The system of claim 7 wherein the support structure includes a
coated surface.
17. The system of claim 16 wherein the coated surface includes a
drug eluting surface.
18. The system of claim 7 wherein a portion of the support
structure has a cross section corresponding to at least one of a
circle, a rectangle, and an oval.
19. The system of claim 7 wherein the support structure includes a
first member and a second member, and further wherein the tissue
contact surface includes a first surface on the first member and a
second surface on the second member.
20. The system of claim 19 wherein the first member is coupled to
the second member by a joint.
21. The system of claim 20 wherein the joint includes at least one
of a portion of a helix, a hinge, and a flexible linkage.
22. The system of claim 7 wherein a first element of the support
structure is configured for placement in at least one of a
suprachoroidal space of an eye and on a retinal pigment epithelium
(RPE) surface of the eye.
23. The system of claim 7 further including a manipulator
configured to couple with the support structure.
24. The system of claim 23 wherein the manipulator includes one or
more electrically conductive nodes and wherein the support
structure includes one or more corresponding nodes.
25. The system of claim 23 wherein the manipulator includes a pair
of forceps.
26. The system of claim 25 wherein the pair of forceps are adapted
for delivering radio frequency (RF) energy.
27. The system of claim 25 wherein the pair of forceps is
configured to provide bipolar energy.
28. The system of claim 25 wherein the pair of forceps includes
clamping faces configured to exert a position dependent clamping
force.
29. The system of claim 23 wherein the support structure includes
at least one feature configured to engage a portion of the
manipulator.
30. The system of claim 29 wherein the feature includes at least
one of a tab, a cavity, a graduated section, a ball-shaped element,
a t-slot element, a hole, a spring, and a deflectable portion.
31. The system of claim 29 wherein the feature allows exertion of a
torque on the support structure.
32. The system of claim 29 wherein the feature is configured to
couple with a radio frequency (RF) energy source.
33. The system of claim 7 further including a cannula configured to
pass the support structure.
34. The system of claim 33 wherein the cannula includes a curved
lumen.
35. The system of claim 33 wherein the cannula has at least two
lumens.
36. The system of claim 33 wherein the cannula includes at least
two pushrods in contact with the reinforcement structure.
37. The system of claim 7 wherein the support structure includes a
mesh.
38. The system of claim 37 wherein the support structure includes a
first portion and a second portion and wherein the mesh is disposed
on the first portion.
39. The system of claim 7 wherein the support structure is
configured for placement on a single side of the membrane.
40. The system of claim 7 wherein the support structure includes a
first portion configured for placement on a first surface of the
membrane and a second portion configured for placement on a second
surface of the membrane.
41. The system of claim 40 wherein a tissue contacting surface of
the first portion includes at least two conductors separated by an
insulator.
42. The system of claim 41 wherein the at least two conductors
includes concentric metal conductors.
43. A method comprising: affixing a first support structure on a
target of a membrane; and separating the target from the membrane
by manipulating the first support structure.
44. The method of claim 43 further comprising positioning the
target at a destination site of the membrane.
45. The method of claim 44 further comprising affixing the target
at the destination site.
46. The method of claim 43 further comprising placing a second
support structure on a second surface of the membrane.
47. The method of claim 46 wherein placing the second support
structure includes orienting the first support structure and the
second support structure in a predetermined alignment.
48. The method of claim 43 wherein separating includes at least one
of coagulating, ablating, and forming an incision.
49. The method of claim 43 wherein affixing the first support
structure includes transitioning a superelastic material from a
first configuration to a second configuration during introduction
into the eye.
50. The method of claim 43 wherein affixing the first support
structure includes transitioning a shape memory material from a
first configuration to a second configuration.
51. The method of claim 43 wherein affixing includes manipulating a
linear element within a guide.
52. The method of claim 43 wherein affixing includes bonding the
first support structure to the membrane.
53. The method of claim 52 wherein bonding includes applying
energy.
54. The method of claim 53 wherein applying energy includes
applying at least one of radio frequency energy, thermal energy,
optical energy, and electrical energy.
55. A system comprising: a guide having a central lumen; an
internal member disposed in the central lumen; and a pair of split
rings coupled to the internal member wherein each split ring is
held in parallel alignment.
56. The system of claim 55 wherein the pair of split rings includes
nitinol.
57. The system of claim 55 wherein the internal member includes a
first linear wire and a second linear wire and further wherein each
of the first linear wire and the second linear wire is coupled to
one each of the pair of split rings.
58. A method comprising: bonding tissue to a support structure, the
tissue supported by a membrane; separating the bonded tissue from
the membrane; and manipulating the support structure to reposition
the bonded tissue.
59. The method of claim 58 wherein bonding includes forming a
chemical bond.
60. The method of claim 59 wherein forming a chemical bond includes
using an adhesive.
61. The method of claim 58 further including selectively disbonding
the support structure.
62. The method of claim 61 wherein selectively disbonding includes
at least one of bioeroding and laser ablating.
63. The method of claims 58 wherein manipulating includes engaging
a feature of the support structure.
64. The method of claim 58 wherein manipulating includes exerting a
torque on the support structure.
65. The method of claim 58 wherein bonding includes applying radio
frequency (RF) energy.
66. The method of claim 58 wherein bonding includes coupling with a
surgical tool.
67. The method of claim 58 wherein bonding includes applying RF
energy at each of a plurality of features of the support
structure.
68. The method of claim 58 wherein separating includes at least one
of coagulating and forming an incision.
69. A system comprising: a cannula configured to pass through a
tissue wall, the cannula having at least one lumen; and a support
structure disposed for passage through the lumen, wherein the
support structure is configured to change shape upon ejection from
the lumen and is configured to bond to a membrane.
70. The system of claim 69 wherein the support structure is
configured to bond to two surfaces of the membrane.
71. The system of claim 69 wherein the at least one lumen is
curved.
72. The system of claim 69 wherein the support structure includes a
ring.
73. The system of claim 72 wherein the ring is separable from a
pushrod, and wherein a portion of the pushrod is configured for
passage through the lumen.
74. The system of claim 72 further comprising a pushrod configured
for passage through the lumen and wherein the ring is in contact
with the pushrod.
75. The system of claim 72 wherein a portion of the ring has a
cross section corresponding to at least one of a circle, a
rectangle, and an oval.
76. The system of claim 69 wherein the support structure includes
at least one of a shape memory material and a superelastic
material.
77. The system of claim 69 wherein the support structure includes a
split ring.
78. The system of claim 69 wherein the support structure includes
two ring members in parallel alignment.
79. The system of claim 69 wherein the support structure includes
an electrical conductor.
80. The system of claim 79 wherein an electric current in the
support structure causes the support structure to bond to the
membrane.
81. The system of claim 69 wherein a first portion of the support
structure is configured to bond to a first surface of the membrane
and a second portion of the support structure is configured to bond
to an opposing surface of the membrane.
82. A system for translocating a multilayer patch of choroid,
Bruch's membrane, and retinal pigment epithelium (RPE) the system
comprising: support means having a contact surface for bonding to
the patch, the support means having a shape configured to support
the patch following separation of the patch from a surrounding
tissue.
83. The system of claim 82 further including an engaging means to
couple with the support means.
84. The system of claim 82 further including a passing means having
a lumen, wherein the lumen is configured to pass the support
means.
85. The system of claim 82 wherein the support means includes at
least one ring shaped member.
86. The system of claim 82 wherein the support means is configured
to permanently bond to the patch.
87. The system of claim 82 wherein the support means is configured
for removal following translocation of the patch.
Description
CROSS-REFERENCE TO RELATED PATENT DOCUMENTS
[0001] This document claims the benefit of priority, under 35
U.S.C. Section 119(e), to Timothy W. Olsen et al., U.S. Provisional
Patent Application Ser. No. 60/763,536, entitled "SURGICAL
SCAFFOLD," filed on Jan. 31, 2006, Attorney Docket No. 600.675PRV,
and is incorporated herein by reference.
TECHNICAL FIELD
[0002] This document pertains generally to ophthalmology, and more
particularly, but not by way of limitation, to ophthalmic
surgery.
BACKGROUND
[0003] Age-related macular degeneration (AMD) is a form of
degeneration that results when the delicate photoreceptors
deteriorate in a highly specialized region of the central retina
called the macula. AMD is the leading cause of visual impairment
and blindness for many people over age 50. The cause of AMD is not
fully understood, and at present, there is no cure.
[0004] AMD is an eye disease of the macula: a tiny area in the
retina that helps produce sharp, central vision required for
central visual activities such as reading, sewing, and driving. A
person with AMD loses this clear, central vision and in some cases,
vision loss is rapid and profound. AMD is a leading cause of severe
visual impairment and blindness in the United States. According to
current statistics, approximately 1.5 million citizens in the
United States are affected by advanced age-related macular
degeneration. This number is expected to increase to 2.95 million
Americans by the year 2020, according to current government
statistics.
[0005] There are two forms of AMD: an atrophic form, called dry
AMD, and an exudative form (eAMD), also called wet AMD. Dry AMD is
the early stage of the disease; about 90% of the diagnosed cases of
AMD are the dry form, but it is the wet form that results in most
of the vision loss associated with the disease. The term AMD is
sometimes used to refer only to the advanced form of the disease
and the term Age-related Maculopathy (ARM) is used to describe the
early clinical findings associated with AMD.
[0006] Dry AMD is associated with extracellular deposits called
drusen (druse is the singular form of the word but is not commonly
used) that form between the retinal pigment epithelium (RPE) and
Bruch's membrane. Drusen are believed to result from impaired
metabolism in the RPE. In a normal eye, the RPE serves a number of
roles critical to healthy vision: renewal of the photoreceptor
outer segments through phagocytosis, providing a blood-retinal
barrier through the tight junctions between RPE cells, and the
selective transport of nutrients across Bruch's membrane to the
outer retina. Dry AMD usually results in a gradual loss of central
vision in the macular regions associated with the drusen and loss
of the RPE.
[0007] Wet AMD is also associated with the drusen deposits plus new
blood vessel growth or neovascularization. Wet AMD results when
fragile blood vessels grow from the choroid into the subretinal
space, leaking blood and fluid, and leading to rapid loss of
central vision. The growth of new vessels under the retina is
called choroidal neovascularization, or CNV. Exudative AMD is a
major cause of severe vision loss. Wet AMD is a major cause of
severe vision loss and accounts for approximately 80% of such
cases. Wet AMD often causes rapid decline in visual acuity.
[0008] The eye includes three tissue layers, or tunics as shown in
the partial sagittal section of the human eye in FIG. 1. The
outermost layer of the eye is fibrous tunic 10 and includes the
transparent cornea (near lens 12) and the opaque white sclera.
[0009] The middle, highly vascularized layer of tissue within the
eye is called uveal tract 15. The innermost tunic, or layer, of the
eye is retina 20, which is an extension of the central neural
tissue of the brain. Retina 20 is comprised of the multi-layered
neurosensory retina 22 and a tightly spaced monolayer of
hexagonal-shaped cells called the RPE 25 as shown in FIG. 2.
Bruch's membrane 35 is a thin, collagenous membrane separating RPE
25 from choroid 30 as shown in FIG. 2. Although RPE 25 must be in
close apposition to neurosensory retina 22 for normal visual
function, there is only a weak attachment between these two tissue
layers. In both pathologic and surgical retinal detachments,
neurosensory retina 22 is separated from RPE 25, with RPE 25
adhering to Bruch's membrane 35. In the present subject matter, it
is understood that a graft to be harvested following retinal
detachment typically includes RPE 25 lying on Bruch's membrane 35
and underlying choroid 30. As one looks directly into the eye, the
central region responsible for the greatest visual acuity is called
the macula (40), a circular region approximately 5.5 mm in
diameter, as shown in FIG. 1. Macula 40 contains the highest
concentration of cone photoreceptor cells that are largely
responsible for central, sharp vision and color vision. In the
figure, macula 40 is shown in the middle of two temporal arcing
vessels (trajectories). Macula 40 is responsible for the central 15
to 20 degrees of visual angle. At the center of macula 40 is the
fovea, a 1.5 mm diameter region that contains primarily cone
cells.
[0010] The human eye can be described as a space-variant optical
system because the detector elements within retina 20
(photoreceptors 21) vary as a function of position. Photoreceptors
21 convert light energy entering the eye into electrochemical
impulses and are often referred to as rods and cones.
[0011] Improved systems and methods for addressing AMD as well as
other forms of macular disease such as hereditary macular
disorders, post-inflammatory diseases, post-traumatic maculopathy,
and toxic maculopathy.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] In the drawings, which are not necessarily drawn to scale,
like numerals describe substantially similar components throughout
the several views. Like numerals having different letter suffixes
represent different instances of substantially similar components.
The drawings illustrate generally, by way of example, but not by
way of limitation, various embodiments discussed in the present
document.
[0013] FIG. 1 illustrates a partial sagittal view of an eye.
[0014] FIG. 2 illustrates a cross-sectional block of the retina,
choroid and sclera.
[0015] FIG. 3 illustrates a sectional view of a support
structure.
[0016] FIGS. 4A-4E illustrate exemplary support structures.
[0017] FIG. 5 illustrates a support structure with an insertion
guide.
[0018] FIGS. 6A and 6B illustrate helical support structures.
[0019] FIG. 7 illustrates a support structure with a particular
surface finish.
[0020] FIGS. 8A, 8B and 8C illustrate sectional views of exemplary
support structures.
[0021] FIG. 9 illustrates a perspective view of a support
structure.
[0022] FIG. 10 illustrates a tool.
[0023] FIG. 11 illustrates a view of a support structure.
[0024] FIGS. 12A, 12B and 12C illustrate support structures in
various configurations.
[0025] FIG. 12D illustrates a cut-away view of a support structure
partially disposed in a cannula.
[0026] FIG. 13 illustrates a tool.
[0027] FIGS. 14A, 14B and 14C illustrate exemplary support
structures and corresponding coagulated regions.
[0028] FIGS. 15A and 15B illustrate perspective views of exemplary
support structures and a portion of tissue.
[0029] FIGS. 16 and 17 illustrate exemplary methods of the present
subject matter.
[0030] FIG. 18 illustrates a perspective view of a graft supported
by an exemplary support structure.
[0031] FIGS. 19A and 19B illustrate sectional views of a support
structure.
[0032] FIGS. 20A, 20B, and 20C illustrate sectional views of a
support structure.
[0033] FIGS. 21A and 21B illustrate portions of a manipulator for
controlling a support structure.
[0034] FIGS. 22A and 22B illustrate views of tissue repair
structures.
[0035] FIG. 23 illustrates a support structure having deployable
features.
[0036] FIG. 24 illustrates a multi-element support structure.
[0037] FIGS. 25A and 25B each illustrate segmented insulation of a
portion of a support structure.
[0038] FIG. 26 illustrates a partial sectional view of a feature
affixed to a support structure.
DETAILED DESCRIPTION
[0039] The following detailed description includes references to
the accompanying drawings, which form a part of the detailed
description. The drawings show, by way of illustration, specific
embodiments in which the invention may be practiced. These
embodiments, which are also referred to herein as "examples," are
described in enough detail to enable those skilled in the art to
practice the invention. The embodiments may be combined, other
embodiments may be utilized, or structural, logical and electrical
changes may be made without departing from the scope of the present
invention. The following detailed description is, therefore, not to
be taken in a limiting sense, and the scope of the present
invention is defined by the appended claims and their
equivalents.
[0040] In this document, the terms "a" or "an" are used, as is
common in patent documents, to include one or more than one. In
this document, the term "or" is used to refer to a nonexclusive or,
unless otherwise indicated. Furthermore, all publications, patents,
and patent documents referred to in this document are incorporated
by reference herein in their entirety, as though individually
incorporated by reference. In the event of inconsistent usages
between this document and those documents so incorporated by
reference, the usage in the incorporated reference(s) should be
considered supplementary to that of this document; for
irreconcilable inconsistencies, the usage in this document
controls.
[0041] The present subject matter includes methods and systems for
establishing a new connection between the macula and healthy
underlying tissue. Accordingly, following the procedure as
described herein, the macula remains nearly in its original
location, and a region of damaged, underlying RPE and choroid is
replaced by surgically translocating healthy autologous tissue to
support the macula. The present subject matter establishes a new
connection between the macula and the choroid, Bruch's membrane,
and RPE complex. In one example, the macula or other layer of
unhealthy tissue is removed followed by translocation of a
graft.
[0042] The present subject matter includes translocating a patch,
or tissue complex, including an underlying layer of full (or
partial) thickness choroid, Bruch's membrane, and RPE. The
translocation procedure can be used in eyes having the wet or dry
forms of AMD. Prior to translocation of the patch, the periphery of
the patch is coagulated using a micropulsed diode laser or other
method to minimize shrinkage.
[0043] The term tissue refers to any portion of the structure
illustrated in FIGS. 1 and 2. The term patch refers to the portion
of tissue selected to support the native macular tissue.
Accordingly, the patch can be an autograft (including the fellow
eye), an allograft (a donor eye), a xenograft (an animal source) or
a synthetic graft (generated and grown outside the eye) and
describes that portion of tissue selected for translocation. The
term patch has meaning at a time before, during and after
translocation. According to one example of the present subject
matter, the patch is translocated from a first position to a second
position. The patch can remain partially attached to the
surrounding tissue or can be entirely separated from the
surrounding tissue. Portions of this document refer to an autograft
however it is understood that other sources of tissue to support
the macula are also contemplated, depending upon tissue
compatibility and availability.
[0044] For example, the tissue, and therefore the patch, can
include one or more layers. In one example, the patch includes
tissue identified as choroid, Bruch's membrane, and RPE.
[0045] In one example, laser energy is used to coagulate the tissue
and gain access to the suprachoroidal space for placement of a
support structure. The support structure can be viewed as a support
frame or support structure for tissue, and in one example, is in
the shape of a ring, however other configurations are also
contemplated. In some examples, the support structure includes one
ring or two rings. In some examples, the support structure includes
one or more members each having various shapes and configurations
that serve to provide support to the tissue. In one example, the
support structure is placed on top of the RPE, and activated by
applying energy in order to coagulate and bond to the tissue. In
one example, pulsed laser energy from a diode laser is used to
create an ablation with minimal shrinkage of surrounding tissue.
The donor tissue (patch) can be excised using a knife or other
cutting means. The laser method is effective to obtain hemostasis
in the vascular choroidal tissues in order to minimize potential
bleeding complications from this vascular tissue during excision.
Activation of the support structure with electric or radio
frequency energy creates coagulation and bonding between individual
segments or portions of the support structure and nearby tissue,
and with little or no damage to the tissue complex supported by the
support structure. In an example where the support structure
includes a ring structure, the tissue complex (donor graft) is
disposed in the center of the ring. This tissue complex is
considered an autograft since it is both harvested from and
translocated to the same patient thereby avoiding immune rejection
problems.
[0046] In various examples, the laser energy is selected to either
avoid ablation of the tissue or cause tissue ablation while
avoiding excessive tissue shrinkage. In one example, the
intraocular laser has a maximum power level that is insufficient to
ablate tissue. Coagulation, in one example, can be performed using
a particular laser having a maximum power of 2 W (2,000 milliwatts)
and at a distance of 3 mm from probe tip to tissue, the laser can
form a region of coagulated tissue of approximately 200 microns
wide as the laser probe traces a path at a relatively fixed
distance from the support structure. In in vitro testing, a probe
tip distance of approximately 2 mm produced good results. Larger or
smaller lasers and other parameters are also contemplated.
[0047] In one example, a coagulated zone of tissue around the
support structure is formed using an 810 nm diode laser in
micropulse mode with the endoprobe held 2-3 mm from surface of
tissue, a power setting of 750-2,000 milliwatts, a pulse duration
of 100 microseconds, and pulse interval ranging from 500
microseconds to 1 millisecond. The coagulated zone is later cut,
for example with a diamond knife, to excise the graft.
[0048] The coagulated line can be re-traced as needed until a
desired burn is achieved. In one example, the laser burn line is
repeatedly traced to separate the graft. The surgeon is able to
control the burn by altering the rate of travel (distance/time) of
the laser probe over the tissue. This control allows for direct
surgeon feedback-control of the burn intensity, and allows for
variation in choroidal pigmentation. In one example of the present
subject matter, the support structure serves as a guide to simplify
retracing of the same path.
[0049] The present subject matter relates to a support structure
that bonds to a surface of tissue. The tissue, according to one
procedure, includes choroid and RPE however other tissue is also
contemplated. One example of the present subject matter is
configured to increase the strength or reinforce the patch to
withstand the forces associated with manipulating the patch. In one
example, the present subject matter provides support for the
patch.
[0050] One example of the present subject matter is configured to
resist shrinkage and distortion of the excised tissue. The RPE is
susceptible to damage if folds are allowed to rub or abrade against
each other. In addition, the present subject matter facilitates
maintenance of the orientation of the patch. In particular, the
patch can be viewed as having a polarity. Maintaining the polarity
of the patch can be a factor in the success of the translocation of
the patch. The present subject matter can be effective both during
and after the separation process.
[0051] The support structure includes a contact surface that bonds
to the tissue at a target site and counters shrinkage or other
distortion after the tissue is separated from the surrounding
membrane. The tissue at the target site, after having been excised,
is sometimes referred to as a graft. The support structure can have
a variety of configurations.
[0052] FIG. 3 illustrates a sectional view of an exemplary
configuration for the support structure. Support structure 100,
which can be considered a reinforcement structure, is shown
disposed on opposing surfaces of tissue 125. Support structure 100,
in the example illustrated, includes ring 100A and ring 100B. Rings
100A and 100B have a circular configuration and can be endless (or
contiguous), or split as illustrated in FIGS. 4A and 4B. In one
example, the rings of the support structure have a diameter of 5.5
mm (approximately that of the macula), however, diameters larger or
smaller than that of the macula are also contemplated, including,
for instance, between 1 and 8 mm. In the figure, rings 100A and
100B have different overall diameters, however, both diameters can
be the same. The wire gauge of the rings, in one example, is 175
microns, however, sizes larger or smaller are also contemplated,
including, for example a wire diameter of 0.004 inch (approximately
100 microns). In one example, a split ring configuration allows
insertion of a portion of support structure 100 through a guide
having a length sufficient to preclude unintended penetration of an
end of the support structure into the tissue. In one example, a
contiguous ring is formed by welding or by cutting from sheet
goods. In one example, the guide includes a cannula.
[0053] As illustrated in FIG. 4A, ring 100C includes a circular
support structure formed of round material. Ring 100C has two ends
101 that are aligned at split 99. In the example illustrated in
FIG. 4A, ends 101 lie in the same plane as ring 100C. FIG. 4B
illustrates exemplary ring 100D having ends that overlap. Extension
102 protrudes beyond the circular configuration of ring 100D and,
in one example, provides a handle or tab by which the support
structure can be manipulated, positioned or contacted for purposes
of coupling an electrical current or other energy.
[0054] In one example, ring 100C includes a shape memory material
that returns to a circular configuration as illustrated in the
figure, upon warming in response to body temperature. Some shape
memory materials have a transition temperature somewhat lower than
normal body temperature and are chilled well below body temperature
before placement in the body. Ring 100C is shown in a configuration
where the temperature is approximately that of the body and, when
at a cooler temperature, ring 100C is in the form of a straight
wire segment (not shown). As such, ring 100C assumes a circular
configuration upon ejection from a cannula using, for example, a
pushrod. In one example, ring 100C is formed at the end of a long
wire section and is clipped or cut upon ejection from a cannula. In
one example, ring 100C separates from the long wire at a notched or
weakened segment.
[0055] FIGS. 4C, 4D and 4E illustrate alternative embodiments of a
support structure with each structure having a feature to
facilitate manipulation. In FIG. 4C, the support structure is in
the form of a split ring and tab 41 extends from one end of the
ring and in a direction towards the interior. A force can be
applied to tab 41, for example, to urge the support structure in a
direction that increases the contact force on the membrane. In FIG.
4D, the support structure is in the form of an endless ring having
a graduated cross section. In particular, portion 42 has a narrower
cross section relative to that of portion 43. As with the structure
of FIG. 4C, the gradient (or non-uniform section) shown in FIG. 4D
allows an operator to control the contact force between the support
structure and the membrane. In FIG. 4E, the support structure is in
the form of a split ring having tab 45 extending towards the
interior of the ring and at a point opposite that of split 44. Tab
45 allows an operator to manipulate the support structure and
adjust the contact force on the membrane. In one example, the tab
extends outward from the diameter of the ring.
[0056] FIG. 5 illustrates support structure 100E coupled to wire
103 disposed in a lumen of guide 110A. Support structure 100E
includes a circular configured ring having overlapping ends.
Support structure 100E is formed at one end of wire 103. The second
end of wire 103 extends beyond guide 110A and allows manipulation
of support structure 100E. In addition, electrical energy or other
energy can be applied to support structure 100E by coupling with
wire 103. In one example, support structure 100E is separated or
detached from wire 103 by cutting, breaking or other forms of
device disengagement.
[0057] FIG. 6A illustrates a partial sectional view of exemplary
support structure 100F in contact with tissue 125. In the figure, a
portion of support structure 100F is shown in section using a cut
plane that lies parallel to the cut plane of tissue 125. Support
structure 100F includes a helical structure and the figure
illustrates one portion of a first winding in contact with a first
surface of tissue 125 and one portion of a second winding in
contact with a second surface of tissue 125. FIG. 6B illustrates a
perspective view of support structure 100F without the tissue.
Support structure 100F includes circular configured windings with
one winding (ring) larger than another winding, however both rings
can be of similar or the same size. In one example, the ends of
support structure 100F overlap. In one example, the ends of support
structure 110F butt together as in the form of a split ring.
[0058] In one example, a helical structure includes an electrical
resistance element or other structure that allows use of electric
resistance heating to bond the support structure to the tissue. In
one example, the rings of the support structure can be attached
together at a hinge rather than a winding, where both rings can be
deployed simultaneously.
[0059] In one example, two rings of a support structure can be
deployed simultaneously through a delivery system. The rings can be
hinged together or otherwise connected. For example, two rings can
be coupled together at a pivot point thus allowing them to swing
open or clamp closed around tissue. In one example, the two rings
are deployed together through a common sheath or insertion element,
for example as shown in FIG. 12.
[0060] FIG. 7 illustrates a perspective view of a segment of
support structure 100. In various examples, surface 105 of support
structure 100 is textured or roughened to enhance bonding to tissue
125 (not shown). Surface 105 can include raised or indented details
that increase the surface area of support structure 100. In one
example, surface 105 includes a coating or conformal layer having
properties that enhance bonding, administer a drug, peptide, growth
factor, chemical or other bioactive compound, provide insulation,
increase electrical conductivity, or achieve another desirable
result. In one example, surface 105 includes a drug eluting
coating.
[0061] FIGS. 8A, 8B and 8C illustrate sectional views of a segment
of support structures 100G, 100H and 100J, respectively. In FIG.
8A, support structure 100G has a circular or round section and
bears on tissue 125 at contact surface 80A. In FIG. 8B, support
structure 100H has a rectangular section and bears on tissue 125 at
contact surface 80B. In FIG. 8C, support structure 100J has a
semi-circular section and bears on tissue 125 at contact surface
80C. The shape and size of contact surfaces 80A, 80B and 80C are
selected to provide a desired surface area of contact with tissue
125. In various examples, support structure 100 is formed of wire
or sheet stock. In other examples, support structure 100 is formed
by rolling, etching, stamping, machining, casting, or by other
fabrication means. In one example, the support structure is placed
in position using a cannula having an interior profile that matches
that of a section of the support structure.
[0062] Support structure 100 can be formed of solid, hollow (or
tubular), laminated or built-up structures including any of a
variety of metals or non-metals. Exemplary materials for support
structure 100 include stainless steel, nitinol or other shape
memory or superelastic material, and a polymer or biodegradable
polymer. Support structure 100 can include elastic or non-elastic
materials. In one example, support structure 100 is
non-magnetic.
[0063] In one example, the present subject matter includes a ring
fabricated of a shape memory material and the ring is inserted
through a tube through the pars plana region of the eye. Following
insertion, body heat raises the temperature of the ring and causes
the ring to transition from a first configuration or shape to a
second configuration or shape. In one example, the superelastic
properties of the support structure allow it to be deformed
significantly as it is introduced into the eye and return to its
original shape once inside the eye.
[0064] FIG. 9 illustrates an exemplary support structure formed of
separate semi-circular rings denoted as rings 100K and 100L. In the
figure, rings 100K and 100L have approximately matching overall
diameters and are fabricated of wire. The wire can be wound or
rolled. Features located at the ends of ring 100K and ring 100L
include holes 106. Holes 106 can be blind holes, divots, dimples or
through holes. In the example illustrated, holes 106 provide
electrical contact with rings 100K and 100L. In one example, holes
106 are configured to receive a surgical tool that may help
manipulate rings 100K and 100L.
[0065] In one example, ring 100K serves as an electrical supply
electrode and ring 100L serves as an electrical drain electrode. A
current passing between the supply and drain electrodes serves to
activate the support structure and thus bond to the tissue.
[0066] As illustrated, rings 100K and 100L present a relatively
small footprint. The surface area in contact with the tissue is
small relative to the surface area of the tissue supported by the
support structure.
[0067] FIGS. 10 and 13 illustrate tools 201A and 201B,
respectively, with tool 201B particularly suited for manipulating,
placing and activating the structure illustrated in FIG. 9. In one
example, the tool is used for capturing the graft and for insertion
of the graft into the destination.
[0068] In FIG. 10, tool 201A includes formed linear members 200A
and 200B having ends 205A and 205B, respectively. Linear members
200A and 200B are disposed in a lumen of cannulas 202A and 202B,
respectively. Cannulas 202A and 202B are disposed within a lumen of
guide 210A and an opposite end (not shown) provides access for
manipulating, placing and activating a structure coupled to ends
205A and 205B. In one example, ends 205A and 205B of tool 201A are
shaped in a manner that presents opposing convergent faces to
facilitate coupling with a structure, such as that illustrated in
FIG. 9. In one example, ends 205A and 205B are shaped in a manner
that forms opposing divergent faces. Other configurations for ends
205A and 205B are contemplated. Linear members 200A and 200B are
formed of electrically conductive or non-conductive materials and
can be laminated, coated, solid or hollow. Linear members 200A and
200B can be manipulated together or independent of each other.
[0069] In various examples, tool 201A is used to insert, place or
position exemplary support structure 100 shown partially in the
figure. In one example, tool 201A is used to deliver energy to bond
support structure 100 to tissue. In the figure, ends 205A and 205B
are shaped to enter holes of support structure 100 from opposite
sides, however, in other examples, the ends enter holes or other
features of support structure 100 from a single side. Ends 205A and
205B are urged apart by a resilient force operating in the
direction shown at arrows 20. Ends 205A and 205B can be drawn
together by relative movement of guide 210A in the direction shown
by arrows 21, or movement of cannulas 202A and 202B relative to
guide 210A. In one example, cannulas 202A and 202B are configured
for independent movement relative to each other as well as
independent movement relative to guide 210A.
[0070] FIG. 13 illustrates tool 201B having curved linear members
200C and 200D in the positions shown. These members may be
retracted into a straight configuration for insertion through a
small incision. A portion of the length of linear members 200C and
200D is coated with a dielectric (such as polyimide). Bare ends
205C and 205D provide electrical connection to support structure
100. For example, ends 205C and 205D can be manipulated to connect
with features of a structure, including, for example, selected
holes 106 of rings 100K and 100L. Guide 210A provides an insulative
sheath by which linear members 200C and 200D can be manipulated. In
one example, the support structure is manipulated based on relative
motion between the guide 210A and the linear members.
[0071] Ends 205C and 205D are shaped to engage a support structure
for purposes of manipulating and activating the support structure.
In the example illustrated, ends 205C and 205D include elbow
portions that allow insertion into receiving holes of a support
structure from one side of the support structure. Other
configurations for the ends are also contemplated. Ends 205C and
205D, as illustrated, facilitate delivery of electrical energy to
an exemplary support structure.
[0072] FIG. 11 illustrates support structure 100M having a circular
configuration with loop feature 107 disposed at end 108. In one
example, loop feature 107 includes a formed wire loop configured to
engage with a device such as tool 201A or tool 201B.
[0073] FIG. 12A illustrates an embodiment of a support structure in
a retracted position and FIGS. 12B and 12C illustrate alternative
examples of the structure in a deployed configuration. In FIG. 12A,
insulative sheath 210D (also referred to as a cannula) and guides
210B and 210C (also referred to as a cannula) constrain the
deflection of ring 100N and ring 100P where ring 100N and ring 100P
are illustrated in an uncoiled configuration. In one example,
guides 210B and 210C have a common sheath with a rotational
component for manipulation of ring 100N and ring 100P either
simultaneously or independently. In various examples, rings 100N
and 100P are fabricated of elastic or shape memory material. For
example, rings 100N and 100P can be distorted to a substantially
linear configuration, as shown in FIG. 12A and later return to a
formed configuration when external constraints or forces are
removed (as with an elastic material) or upon transition from a
first temperature to a second temperature (as with a shape memory
material). In one example, an intraocular infusion fluid (cooling
or heating) can be used to trigger a transition of a shape memory
material from a first configuration to a second configuration, in
addition to controlling an intraocular temperature.
[0074] The cannula can have two lumens (as shown in the figures) or
more than two lumens. In addition, the multiple lumens of the
cannula can each carry a pushrod for deployment, manipulation, or
activation of a support structure.
[0075] In one example as illustrated in FIG. 12A, each of
insulative sheath 210D, guide 210B, guide 210C, ring 100N, and ring
100P are configured for independent movement relative to each
other. For instance, guide 210B can be manipulated independently
relative to sheath 210D as well as ring 100N, ring 100P and guide
210C.
[0076] In FIG. 12B, linear members 210B and 210C are configured in
a curved or swept formation with each linear member deflecting a
similar amount from a center line upon relaxation. FIG. 12B
illustrates a sectional view of insulative sheath 210D penetrating
a tissue wall 5. In FIG. 12C, linear member 210E is configured in
an angular formation and linear member 210C is configured in an
unbent formation with linear member 210E deflecting away from
linear member 210C. For the example illustrated, linear member 210E
has a length that exceeds linear member 210C when in a retracted
position. Linear member 210E is configured with two hinge points or
knees, however, in other examples, one or more of the linear
members are shaped with more or less curvature.
[0077] FIG. 12D illustrates a portion of a support structure having
ring 100N disposed partially within a lumen of cannula 210B. Ring
100N is shown in an uncoiled configuration. In one example, ring
100N includes a shape memory material. Ring 100N is ejected by a
force applied to pushrod 80, also disposed within a lumen of
cannula 210B. In the figure, both of ring 100N and cannula 210B
have a curvature that facilitates placement (and extraction) of the
support structure. In other examples, either one or the other of
ring 100N and cannula 210B has a curvature. In one example, the
structure is naturally coiled and when restrained by the confines
of the lumen, maintains a substantially linear configuration but
when ejected from within the lumen, it assumes a ring shape or
other configuration. Break 26 depicts the separate nature of
pushrod 80 and ring 100N. In one example, break 26 includes a keyed
joint, such as a tongue and groove, screw, or a spline, to allow
rotational control of the support structure from the distal end of
the pushrod. Break 26, in one example, includes a weakened portion
where pushrod 80 can be physically separated from ring 100N by
applying a force. The curved cannula, when disposed through the
sclera, may reduce strain on the tissue wall of the eye and support
structure during introduction into the eye.
[0078] In one example, ring 100N is naturally coiled and when
restrained by the confines of the lumen, maintains a substantially
linear configuration but when ejected from within the lumen, it
assumes a ring configuration. Break 26 depicts the separate nature
of pushrod 80 and ring 100N.
[0079] Rings 100N and 100P, for example can be separate from a
pushrod or can be contiguous segments that are clipped or
configured to break at a predetermined location, thus separating
from the pushrod or other member that remains in the lumen.
[0080] A suitable shape memory material is selected to have a
transition temperature based on the body temperatures encountered
in the eye. For example, the support structure material is selected
to retain a first shape or configuration at a first temperature
(which can be greater than or less than that of the eye) and then
resort to a second shape or configuration upon exposure to a second
temperature different from the first temperature. In one example,
the material has elastic or superelastic properties.
[0081] Shape memory materials (or metals) have a thermal memory.
Nitinol is an example of a shape-memory alloy and its shape-memory
effect is due to a reversible austenite-martensite transformation.
In the low-temperature regime, the alloy exists as a complex
arrangement of atoms called martensite. As the alloy is heated
through a transition temperature range, the alloy undergoes a
solid-to-solid phase change to the highly ordered parent phase,
called austenite. It is possible to control the transition
temperature range by changing the nickel-titanium ratio, or by
alloying with other metals. In one example, the nitinol structure
that is introduced into the body has a transition temperature near
body temperature. A nitinol structure can be cooled and compressed
for delivery, and when deployed, it warms to body temperature, and
returns to the parent shape.
[0082] To impart a parent shape to a nitinol structure, it must be
constrained in the desired, final shape and heated in a furnace to
between approximately 450 and 550 degrees C. This produces an
austenitic structure. The part can then be cooled and compressed or
deformed to produce a martensitic structure. Subsequent heating
beyond the transition temperature allows the structure to return to
its memory position.
[0083] Ni--Ti is an example of a shape memory material with
superelastic properties used in biomedical applications. Other
alloys that exhibit shape memory properties include Cu--Al--Ni
(copper-aluminum-nickel), Cu--Zn--Al (copper-zinc-aluminum), Au--Cd
(gold-cadmium), and Ni--Al (nickel-aluminum). Some shape memory
alloys also exhibit superelastic behavior. Examples of superelastic
alloys include Cu--Al--Ni (copper-aluminum-nickel), Cu--Al--Mn
(copper-aluminum-manganese), In--Pb (indium-lead), and Cu--Al--Be
(copper-aluminum-beryllium). Non-metallic materials are also
contemplated for shape memory materials and superelastic
materials.
[0084] A structure having a first shape (first configuration) can
be deformed to allow passage through an opening or cannula through
the sclera. Accordingly, to pass through the eye, the structure is
deformed or partially uncoiled into a second configuration. After
passing into the eye, the constraining force exerted by, for
example, the cannula, is removed and the structure returns to the
first configuration. Nitinol can sustain a strain below
approximately 8% and exhibit the superelasticity property as
described herein.
[0085] FIGS. 14A, 14B and 14C illustrate exemplary support
structures having a variety of configurations. Support structures
100Q, 100R, and 100S are shown having a hemi-circular (half),
semi-circular (partial), and unbent configuration, respectively. In
each figure, a region of tissue 125 is illustrated underlying each
support structure. Each support structure 100Q, 100R and 100S is
disposed in guide 110A. In various examples, a corresponding
portion of a support structure (not illustrated) is disposed
underneath tissue 125. The corresponding portion can have a similar
or different size or configuration as the upper portion.
[0086] The tissue is cauterized in the regions illustrated by the
radial lines underlying the support structures. In one example, the
support structure is illustrated as a straight segment. In one
example, the support structure includes a split or forked element
that deploys to a "V" shaped segment in which case the perimeter of
the "V" is cauterized and cut. Other geometric configurations and
sizes for support structures are also contemplated.
[0087] FIG. 15A illustrates a perspective view of a support
structure having ring 100T and ring 100U positioned on opposite
surfaces of a section of tissue 125. In the figure, both ring 100T
and ring 100U are illustrated in the form of split circular rings
of a similar size. Coagulated region 126 encircles a periphery of
the support structure and penetrates through the entire depth of
tissue 125. Cut 128 is disposed within coagulated region 126 and
encircles a portion of the periphery of ring 100T. The subject
matter of FIG. 15A is configured to form a free graft for
translocation.
[0088] The split portions in rings 100T and 100U are illustrated
near an edge of the tissue. Other locations or alignments of the
splits are also contemplated. The figure also illustrates holes
disposed at the ends on either side of the splits. In one example,
the holes facilitate manipulation and activation of the support
structure.
[0089] A method according to the present subject matter includes
placing the support structure about a target location on at least
one surface of the tissue. In FIG. 15A, target 150 is encircled by
both ring 100T and ring 100U. After placement of the support
structure and activation to bond the structure to the tissue
(including ring 100T and ring 100U for the example illustrated),
coagulated region 126 is formed on a surface of tissue 125 around
the periphery of the support structure. Cut 128 is formed within
the coagulated region followed by removal or separation of target
150 from tissue 125. Target 150 is then translocated to a
destination location and affixed in position. In various examples,
ring 100T and ring 100U provide a support structure by which target
150 is manipulated and positioned. In the example illustrated in
FIG. 15A, target 150 is completely separated from tissue 125 by
coagulating and cutting around the entire periphery.
[0090] In one example, the target tissue is partially separated
from tissue 125 and a portion of the tissue and target remain
contiguous. FIG. 15B illustrates such an example with support
structure 100V disposed on an upper surface of tissue 125. In one
example, a second portion of the support structure (not
illustrated) is provided on a lower surface of tissue 125.
Coagulated region 126 is formed around a portion of support
structure 100V and cut 128 is formed therein. Target 150 is located
proximate a portion of support structure 100V and remains attached
to tissue 125 at region 130. Region 130 is distorted when target
150 is rotated, or relocated, to a destination location by
manipulating support structure 100V and guide 110A. The subject
matter illustrated in FIG. 15B allows formation and translocation
of a pedicle graft where the target remains attached to the tissue
and blood perfusion to the graft continues. In one example, the
cauterized region, and the incision are located very close to the
perimeter of the support structure.
[0091] FIG. 16 illustrates a flow chart of method 300 according to
the present subject matter. At 305, a standard 3-port pars plana
vitrectomy is performed, removing the core vitreous, lifting the
posterior vitreous from the retinal surface, and removing the
majority of the posterior vitreous gel. At 310, the retina is
detached. At 315, the graft is harvested. At 320, the graft is
placed in position at the destination. At 325, the retina is
replaced.
[0092] FIG. 17 illustrates a flow chart of method 400 according to
the present subject matter. At 405, tissue is coagulated in order
to reduce bleeding. At 410, an incision is made to gain access to
the suprachoroidal space. At 415, support structure 100 is
positioned proximate target 150 on tissue 125. At 420, support
structure 100 is bonded to tissue 125 or other membrane. At 425,
tissue 125 around support structure 100 is coagulated. At 430,
graft or target 150 is detached from the surrounding tissue 125. At
435, graft 150 is relocated to the macular region, thereby
supporting the neurosensory retina with a translocated autograft of
healthy choroid, Bruch's membrane, and RPE.
[0093] In one example, the retina is left intact. The
full-thickness retina, RPE, Bruch's membrane, and choroid are
coagulated using a thermal modality, such as pulsed laser. Next, an
incision is made along the nerve fiber layers of the retina. The
posterior ring of a support structure is placed in the
suprachoroidal space between the choroid and the sclera. The
anterior ring, aligned with the posterior ring, is placed upon the
innermost layer of the neurosensory retina. The rings are
activated, and the graft, (including choroid, Bruch's membrane,
RPE, and neurosensory retina), is removed. The neurosensory retina
is then gently peeled away from the graft, leaving a layer of
choroid, Bruch's membrane, and RPE supported by the structure. The
graft is then inserted as described.
[0094] In one example, the support structure is placed and
positioned without detaching the superior retina at a localized
position. In such a procedure, a small blister, or induction of a
serous retinal detachment, is made and an incision is made in the
nerve fiber layers in a direction parallel to the grain of the
fibers. In one example, the support structure is inserted under the
separated nerve fiber layer.
[0095] In one example, the translocation procedure includes
removing the damaged tissue underlying the retina. In one example,
the damaged tissue remains in place and the translocated patch of
choroid, Bruch's membrane, and RPE is placed beneath the retina in
a position on top of the original damaged tissue. Over time, new
vessels grow through the original tissue to perfuse the new graft.
The removal of the damaged tissue underlying the macula is
optional.
[0096] FIG. 18 illustrates a view of an excised autologous graft of
choroid, Bruch's membrane, and RPE supported by a support structure
including two nitinol rings. Tissue 125 is held in a position that
reveals the RPE with underlying layers not visible. Anterior ring
100A is largely visible and portions of posterior ring 100B are
visible only where the cauterized tissue is cut closer to the
rings. Prior to harvest of the graft, posterior ring 100B is
positioned between the sclera and the choroid. Forceps 32 is shown
gripping ring 100A and 100B.
ALTERNATE EXAMPLES
[0097] In one example, tissue other than choroid, Bruch's membrane,
and RPE is manipulated and translocated using the present subject
matter. For example, other vascular tissue includes the choroid
plexus in the central nervous system, vascular complexes in the
gastrointestinal system including the small bowel, colon and
stomach tissue, vascular plexus of the bladder or urinary tract
system, pericardium with its inherent microvasculature, meninges
surrounding the central nervous system, vascular plexus surrounding
nerve tissue, subcutaneous vascular tissue (subdermal), vascular
complexes in the sinuses or oral mucosa, nasal pharynx or
esophagus.
[0098] In one example, fluid is introduced under the retina into
the subretinal space to aid in detachment of the retina.
[0099] The present subject matter is configured to facilitate
transplantation of healthy RPE with a full-thickness patch of
underlying Bruch's membrane and choroid. The present subject matter
can be used to harvest and translocate a patch of tissue while
maintaining the shape, size, and polarity of the patch or graft. In
one example, an autologous graft of choroid, Bruch's membrane, and
RPE is moved to the subfoveal area and placed beneath the
macula.
[0100] It is expected that new blood vessels may form to provide
choroidal blood flow to support the RPE.
[0101] The present subject matter may eliminate the problem of
torsional diplopia, a tilted horizon in the surgical eye that
sometimes results from macular translocation surgery. A temporary,
surgical retinal detachment provides access for the surgery. The
retina is reattached in its original position and maintains normal
orientation.
[0102] In one example, a flap (shaped like a peninsula) of healthy
choroid, Bruch's membrane, and RPE is repositioned by rotation of
the flap under the retina to replace a region of damaged choroid,
Bruch's membrane, and RPE that is no longer capable of supporting
the photoreceptors in the retina. The flap, or pedicle, remains
connected to the choroidal blood supply to nourish the flap
tissue.
[0103] In one example, a free, autologous graft of healthy choroid,
Bruch's membrane, and RPE is harvested from the patient's eye and
repositioned under the macula. The neovascularization from the
choroid will vascularize the graft.
[0104] In one example, an allograft (tissue transplanted from a
donor to a recipient) is performed using the present subject
matter. As such, the host is subjected to immunosuppression since
the graft would be treated as foreign tissue by the recipient's
immune system. In one example, the graft can be obtained from a
cadaveric source such as an eye bank. In one example, tissue from
the fellow eye is used as an autograft, thereby avoiding immune
barriers. As such, tissue (including choroid, Bruch's membrane, and
RPE) from one eye is translocated to the macular region of the
fellow eye of the donor.
[0105] In one example, a patch includes a synthetic graft. A
synthetic graft can be grown in vitro, from, for example, donor
stem cells, iris cells, or other sources.
[0106] In one example, a layer of photoreceptor cells is implanted
on a support structure as described herein and used to replace
cellular elements lost in other retinal degenerative conditions
such as retinitis pigmentosa.
[0107] Coagulation around the patch can damage the RPE.
Additionally, Bruch's membrane has a tendency to shrink when
exposed to energy that is capable of coagulating choroidal blood
vessels. In one example, the shape and orientation of the graft is
maintained by the support structure while repositioning the graft,
thus reducing the amount of tissue damaged during the process. An
index mark or a feature position can be used as a reference to
maintain alignment of the graft orientation. The index mark or
feature can be disposed on one or more portions of the support
structure.
[0108] In one example, a micro-pulsed diode laser is used to
coagulate the periphery of the patch. The laser is operated with
particular parameters as to maximum power, length of pulse and
length of interval between pulses.
[0109] Typical radio frequency (RF) generators for intraocular
devices have a maximum power in the range of 12-15 W. In one
example, the support structure is bonded to the tissue using a
power level ranging from about 1 W to 10 W. Parameters for bonding
the tissue to the support structure, including power level, pulse
duration, and frequency can be established experimentally.
[0110] In one example, a foot pedal is used to apply power to the
electrodes momentarily. In one example, the device is operated
briefly to tack the support structure into position at one or more
locations around the periphery. Typically, during the bonding
process, some regions of tissue stick to the electrodes, thus
forming a thin layer of insulation. To overcome the thin layer of
insulation, the power is slightly increased in order to maintain
the same activation or bonding effect. If excessive tissue sticks
to the electrodes, increased power levels have little effect and
the electrodes can be cleaned to restore bonding effectiveness.
[0111] In one example, the support structure includes an
implantable structure of biocompatible metal to support the graft
during harvest and facilitates repositioning of the graft. In
various examples, the support structure is in the form of a ring or
other structure having an approximately circular shape.
[0112] In one example, the support structure is fabricated of a
shape memory material such as nitinol (a nickel titanium alloy
originally developed at the Naval Ordnance Laboratory). Nitinol has
shape-memory characteristics that allow it to be folded into a
compact shape for insertion through a small tube (for example, a 20
gauge blunt needle) inserted into the eye, and then deployed (by
exposure to body temperature) to return to its memory position for
use as a support structure.
[0113] In one example, the support structure is inserted or
retracted using a guide of 18 gauge (approximately 1.02 mm
diameter); however, larger or smaller diameters are also
contemplated. Entry sites through the sclera (sclerotomy) may range
from 25 gauge to 18 gauge or larger.
[0114] In one example, the support structure is bonded to the graft
and provides a structure with which to manipulate and position the
graft, or patch. In one example, the orientation and polarity of
the RPE cells remain aligned with that of the surrounding
tissue.
[0115] In one example, the support structure includes two rings,
one on top of the RPE and one beneath the choroid and each serves
as an electrode for applying pulsed radio frequency (RF) energy.
The two rings bond to the tissue and provide support for the
graft.
[0116] Various bipolar devices can be used to activate the support
structure. In one example, a bipolar device and a signal generator
are used for delivering RF energy to the support structure. For
example, a bipolar scissors can be used for cutting and
coagulation. In one example, an intraocular (bipolar) forceps is
adapted to activate the support structure. In various examples, the
support structure includes members disposed on one or two surfaces
of the graft. In addition to bipolar devices, the support structure
can also be bonded using a monopolar device. In a monopolar device,
RF current flows in the tissue between a small active electrode and
a passive, neutral or dispersive electrode which has a much larger
surface area. In a bipolar device, RF current flows in the tissue
between two closely spaced electrodes.
[0117] In one example, laser ablation and cutting (for example,
with a diamond knife) are used around the outer periphery of the
support structure of the choroid, Bruch's membrane, and RPE tissue.
In one example, the upper and lower (or first and second) rings of
a support structure are clamped in concentric alignment to elevate
and separate tissue, protect the RPE cellular layer or other
delicate monocellular layers that are being translocated, and to
separate tissue on either side of the choroid, Bruch's membrane,
and RPE.
[0118] In one example, air (in the form of bubbles), or fluid (such
as balanced salt solution, perfluorocarbon liquid, hyaluronate, or
other viscoelastic agent) is introduced to elevate and separate
tissue to allow placement of the graft in the subretinal space or
other destination for target 150. The bubbles, fluids, or liquids
can also be used in the insertion site to protect delicate cellular
layers, and prevent injury. Accordingly, the graft is positioned
between the existing RPE and the neurosensory retina
(photoreceptors) in the macular region. The graft is centered to
support the fovea. In one example, the fovea of the neurosensory
retina is positioned to lie at the center of target 150.
[0119] In one example, a laser is used to cauterize tissue around
the graft.
[0120] In one example, the support structure is fabricated of
biodegradable material and thus, breaks down after a predetermined
period following translocation of the graft.
[0121] In one example, the support structure is encased in a
naturally occurring fibrous capsule and remains in position
following translocation of the graft.
[0122] In various examples, the support structure includes a
feature, such as a tab, that facilitates manipulation and
positioning of the graft.
[0123] In various examples, the support structure is used to
cauterize the tissue around the graft. For example, electrically
conductive rings can serve as cauterizing electrodes and the rings
are placed and positioned using forceps or another tool having
electrically charged contacts. In one example, the tool includes a
vertically acting forceps. In one example, the tool is manipulated
through a guide having a diameter of approximately 2 mm. In various
examples, the forceps are used to insert the support structure
through a guide as well as to grasp, position, and activate the
support structure.
[0124] In one example, access to the graft is provided (for either
retrieval or insertion) through the sclera by creating a larger
scleral opening externally with standard blades and addressing the
choroid with laser, diathermy, or cautery.
[0125] In one example, the support structure includes two members
that are positioned with one on either surface of the tissue. In
various examples, the two members are aligned by manual alignment,
a hinge, a pivoting bracket or aligned by a placement structure as
illustrated herein. In one example, the members of the support
structure are aligned by visually noting deflection telegraphed
through from an opposite side of the tissue.
[0126] In one example, a layer of oxide is removed from a metal
support structure to facilitate bonding to the tissue.
[0127] In various examples, the surface of the support structure is
modified to enhance bonding. Exemplary modifications include
roughening, scoring, serrations, or ridges on the surface of the
support structure.
[0128] In various examples, the support structure is positioned by
means of a linear incision or a pierced hole. The support structure
can be distorted or collapsed into a first configuration and
inserted into position and thereafter deployed or allowed to revert
to a second configuration.
[0129] In various examples, the support structure is affixed in
position by an activation process that produces a change in
collagen as energy is delivered, thus causing the tissue to adhere
to the support structure. Activation can include application of
thermal energy (freezing or heating current), RF energy, electric
current or optical energy. In one example, a radio frequency (RF)
bipolar generator is used to activate the support structure and
form a bond with the tissue. In one example, a biocompatible
adhesive is used to bond the support structure to the tissue.
[0130] In various examples, a laser light source is directed around
the periphery of the support structure to coagulate the blood
around the graft. In one example, low level pulsed energy is
applied to avoid shriveling, shrinkage and tissue damage. In one
example, the power level is approximately 750 milliwatts and the
pulse interval is reduced to deliver sufficient energy per unit
time in order to coagulate. At low energy levels, the line can be
traced repeatedly in order to produce an acceptable burn.
[0131] The absorption rate also depends on the level of
pigmentation in the eye. For example, in micropulse mode with an
810 nm diode laser, a power of approximately 850 mW, a pulse
duration of 100 microseconds, and a pulse interval of 500
microseconds can produce effective results. Other power levels,
durations and intervals are also contemplated. In one example, the
power level may be in the range of 500 mW to 2000 mW depending on
the level of pigmentation and other factors.
[0132] In one example, a tab or other feature is provided on a
support structure and energy is coupled to the support structure by
the feature.
[0133] In one example, the laser energy is directed at the tissue
and measures are taken to avoid absorption by the support
structure. For example, a coating or sacrificial structure (such as
an additional wire ring) is provided to reduce losses at the
support structure.
[0134] The laser energy is directed around the support structure by
manual manipulation of a tool or by indexing off the support
structure. In one example, the support structure includes a
side-emitting optical fiber element and optical energy pulsed in
the fiber serves to ablate or coagulate the tissue around the
graft.
[0135] In various examples, the support structure is treated with a
pro-vascular or an anti-vascular drug to modulate perfusion of the
graft following translocation. In one example, the drug is
incorporated as a drug eluting coating on the support structure. In
one example, a scleral depressor is used to place the support
structure in position. For example, an external thrust device can
be used to apply a pressure to a portion of the sclera to
facilitate identification of the target site. The blood vessels
will appear blanched and thus provide a guide as to
cauterizing.
[0136] In one example, choroidal blood vessels are blanched to
facilitate coagulation. Blanching can reduce the thermal spread of
vascular blood flow to surrounding tissues (radiator effect) and
thus also allow closure of vessels without actively flowing
blood.
[0137] In addition, blanching before coagulating may allow the
laser energy level to be lower. The tissue may coagulate with
reduced thermal damage if tamponade is provided by, for example, an
external scleral depression device, sufficient to blanch the
choroidal tissue. Application of visible light (illumination) in
conjunction with scleral depression can facilitate identification
of the blanched tissue.
[0138] In one example, selected drugs or factors are used with the
support structure to enhance engraftment. Exemplary
anti-angiogenesis drugs include Lucentis.TM. (ranibizumab, a
humanized anti-VEGF antibody fragment that inhibits activity) or
MACUGEN.RTM. (pegaptanib sodium injection) and exemplary
pro-angiogenic peptides such as VEGF. In various examples, a first
drug or surface treatment is used on a first member of a support
structure and a different or second drug or surface treatment is
used on a second member of the support structure.
[0139] In one example, a balloon depressor or other structure to
depress the sclera is used to compress a target area. After
depressing the target area, a laser is used to coagulate the
surrounding tissue. After removing the depressor (or deflating the
balloon), the support structure is introduced and placed in
position on one or both sides of the tissue. The graft is then
excised by cutting followed by translocation and re-implantation.
In one example, a scleral depressor is used to tamponade the
choroidal blood flow to improve coagulation.
[0140] The depressor can facilitate blanching of the blood vessels.
The tissue blanches, or turns a pale color when pressure is
applied.
[0141] In one example, pre-existing tissue is removed from the
destination site prior to translocation and re-implantation. In one
example, the graft is translocated and re-implanted without removal
of pre-existing tissue.
[0142] In one example, the support structure members (or portions)
are disposed on the first and second surface of the tissue and are
spaced apart by a distance of approximately 400-500 microns. In
various examples, the support structure members are spaced apart by
a dimension less than 400 microns and in other examples, by a
dimension greater than 500 microns. The support structure members
are separated to reduce or eliminate damage to the tissue,
particularly the RPE, by scraping. In one example, a portion of the
support structure is coated with a material selected to protect the
RPE, such as a viscoelastic substance, and thereby reduce loss of
RPE.
[0143] In various examples, the tissue is coagulated on either one
or both surfaces. In one example, an incision is formed on either
one or both surfaces. In one example, the support structure is
affixed to one surface of the tissue and an opposite surface of the
tissue is coagulated. In one example, the support structure is
affixed to one surface of the tissue and an opposite surface of the
tissue is cut. The tissue is cut with a scissors, a laser, a
diamond blade, or other cutting tool.
[0144] FIGS. 19A and 19B illustrate sectional views of portions of
a support structure. In FIG. 19A, support structure 190A includes
ring 192A and ring 194A. Ring 192A has a substantially rectangular
cross section with groove 191 disposed on the tissue contact
surface. Ring 194A has a substantially rectangular cross section
with tongue 193 disposed on the tissue contact surface. Tongue 193
and groove 191 are configured to match and facilitate alignment of
ring 192A and ring 194A disposed on opposite sides of the membrane
(not shown).
[0145] In one example, the two rings of a support structure are
aligned by a series of raised dimples or spikes on one ring and a
corresponding series of depressions or holes on the second ring.
The combination of protruding portions and receiving portions may
facilitate holding the support structure in position relative to
the tissue.
[0146] In FIG. 19B, support structure 190B includes ring 192B and
ring 194B. Ring 192B and ring 194B have sections corresponding to
partially flattened round stock. The round stock can be flattened
by rolling. Ring 192B and ring 194B are held in alignment by hinge
195. Hinge 195, in various examples, includes a flexible element or
mechanical structure that allows limited movement of ring 192B
relative to ring 194B. In one example, hinge 195 includes a shape
memory material.
[0147] FIGS. 20A, 20B and 20C illustrate exemplary features for
manipulating the support structure. In FIG. 20A, for example,
support structure 250A is affixed to feature 260. Feature 260
includes a ball-like structure that is configured for grasping by a
manipulator having a corresponding cup-shaped element. In FIG. 20B,
for example, support structure 250B includes feature 262 disposed
on a surface. Feature 262, in the figure, includes a hole or cavity
that receives a manipulator having a corresponding element. In one
example, the hole includes a "t-slot" or other shaped element that
allows an operator to manipulate, control and engage the support
structure. In FIG. 20C, for example, a resilient portion of
manipulator 276 engages a corresponding feature of support
structure 250C. In the figure, manipulator 276 includes ramped
portions 272 that engage hole 261 in the support structure 250C.
Notch 274 of manipulator 276 engages the surfaces of hole 261 of
support structure 250C following deflection of ramped portions 272
and insertion of the manipulator into hole 261. Other
configurations of features are also contemplated for engaging the
support structure for purposes of manipulating during placement and
activation.
[0148] A feature affixed to, or integral with, the support
structure can be used to selectively apply a torque or other force
to generate compressive pressure on a selected portion of a ring or
rings. In one example, a feature can be used for delivering energy
(RF) such as for purposes of activating (bonding) or disbonding the
support structure and the membrane. Features distributed about the
support structure can be used for selective activation. For
example, one support structure illustrated herein includes four
features.
[0149] FIGS. 21A and 21B illustrate portions of exemplary
manipulators suitable for use with a particular support structure.
In FIG. 21A, manipulator 270A includes parallel clamping surfaces
275. In one example, the clamping surfaces travel in a linear
manner and remain parallel when operated by legs 272. Legs 272 are
at an angle of approximately 60-70 degrees with respect to the
clamping surfaces, however other angles are also contemplated. In
FIG. 21B, clamping surfaces 277 are set at an angle that causes a
work piece to be clamped at a corresponding angle. For example, a
support structure can be manipulated or clamped so that one portion
makes contact with the membrane before another portion of the
support structure. In one example, the manipulator includes a pair
of forceps, a micro-manipulator or a remotely operable actuator.
Forceps are a hand-held instrument used for grasping and holding an
object.
[0150] FIGS. 22A and 22B illustrate structures for keeping the
membrane from being torn or for treating a torn membrane. Support
structure 280 shown in FIG. 22A includes ring 282 bonded to mesh
284. Mesh 284 is affixed to a tissue contact surface of ring 282
and provides a structure that supports torn tissue disposed within
the circumference of ring 282. Mesh 284 includes a biocompatible
material and can include a bioerodable material, a biodegradable
material, an elastic material or other substance. For tears or
other damage external to the support structure, a structure as
illustrated in FIG. 22B can be used. FIG. 22B illustrates ring 286
having hole 287 disposed in a surface. In the example illustrated,
hole 287 is a blind hole, however, through holes can also be used.
In other examples, hole 287 includes internal splines, threads,
clamps or other features that engage a corresponding structure of
support 290. Support 290 includes leg 288 and hook 292. Hook 292
engages a portion of tissue and exerts a force that stabilizes a
torn tissue based on the fixed alignment between support 290 and
ring 286. Support 290, in various examples, includes a metal or
polymer structure.
[0151] FIG. 23 illustrates a view of support structure 350A having
a generally circular shape. As used herein, shape refers to a
two-dimensional configuration when viewed from above. Support
structure 350A includes a plurality of features 352A, 352B, 352C,
and 352D. The features illustrated include four tabs uniformly
distributed about the circumference, however, more or fewer
features and different placement are also contemplated. In various
examples, the features allow manipulation or activation of the
support structure. In one example, the features are held in a
closed or retracted position by material properties selected for
the feature. For example, a shape memory material can be selected
to provide a retracted position as shown by features 352A, 352B,
and 352C and when activated by temperature or other energy source,
the features are deployed as shown by feature 352D. Thermal energy
can be provided by an external source or by natural body
temperature. Radio frequency energy can be provided by a suitably
configured manipulator or forceps. In one example, the features are
electrically isolated from the ring of support structure 350A. An
electrically isolated feature allows the surgeon to selectively
bond the feature to the membrane.
[0152] In one example, a shape memory material provides a retracted
position as shown by feature 352A or a partially or fully retracted
position in which the feature is flush with a surface of support
structure 350A. In a flush position, the feature is disposed in a
cavity or channel in a manner similar to a folding blade of a
pocket knife.
[0153] FIG. 24 illustrates a cross section of a portion of a
support structure. In the figure, the support structure includes a
first ring 240A disposed on a first surface of membrane 125. A
second ring 242 is disposed on a second surface of membrane 125,
and in one example, the second surface includes the RPE layer.
Second ring 242 includes two electrical conductors separated by an
insulator or dielectric 246. The dielectric can include an oxide
layer. In one example, ring 244 and ring 248 are concentric. Rings
240A, 244, and 248 are separately accessible by way of features
disposed about the support structure and when energized, bond to
the membrane. In particular, second ring 242 can be placed on the
RPE in a manner that avoids scraping or damage to the cells on the
surface of the membrane. Once placed in position, energy can be
applied to the two conductors of second ring 242, thus bonding the
second ring to the membrane. After placing second ring 242 in
position, first ring 240A can be positioned and bonded to the
membrane. First ring 240A can be activated by applying energy to
one or both of ring 244 and ring 248. In various examples, second
ring 242 (including ring 244, ring 248 and dielectric 246) are
separate elements or of a unitary construction.
[0154] In one example, the support structure includes a single ring
or other structure (configured for placement on a single side of
the tissue) where the ring or other structure has a portion
including two electrical conductors separated by an insulator or
dielectric. For example, graduated portion 43 of the ring
illustrated in FIG. 4D can include two electrically isolated
conductors that can be used to apply bonding energy. As another
example, tab 41 (of the ring illustrated in FIG. 4C) or tab 45 (of
the ring illustrated in FIG. 4E) can include two electrically
isolated conductors that can be used to apply bonding energy. This
structure allows a surgeon to both manipulate the rings (+ or -
pole) as well as activate the rings using an energy source such as
radio frequency.
[0155] FIGS. 25A and 25B illustrate portions of support structures
having segmented insulators. In FIG. 25A, electrically conductive
portions of the support structure are exposed at 266A. Insulators
264A shield selected portions of the support structure. At exposed
portions 266A, a bond is readily formed between the support
structure and the membrane by applying monopolar RF energy. In FIG.
25B, the support structure includes a pair of adjacent electrical
conductors, each having segmented insulators. In particular,
electrically conductive portions of the support structure are
exposed at 266A and 266B. Insulators 264A and 264B shield selected
portions of the support structure. At exposed portions 266A and
266B, a bond is readily formed with the tissue disposed between the
adjacent rings of the support structure by applying bipolar RF
energy.
[0156] FIGS. 23, 24, and 25 exemplify various means of attaching a
support structure to a tissue surface using RF energy. Other means
are also contemplated and can generally be described as having two
conductors, relatively closely spaced, and separated by a
dielectric or insulator. In one example, the two conductors are
disposed at intervals, thus forming regions where the conductors
are very close. The conductors can be positioned to contact the
tissue so that RF energy applied to the conductors passes through a
circuit including the two conductors as well as the tissue adjacent
the separating insulator. FIG. 26 illustrates a partial sectional
view of an example in which a feature includes two electrically
isolated conductors. Feature 352E is affixed to support structure
350B. Feature 352E includes a first electrical conductor 362A,
which is isolated from the support structure by insulator 364A, and
a second electrical conductor 362B, which is isolated from the
support structure by insulator 364B. Bipolar RF energy can be
applied to conductor 362A and conductor 362B, and when the device
is in contact with tissue, a bond is formed by the current in the
tissue.
[0157] Particular embodiments of the present subject matter can be
used to maintain a fixed shape of the excised graft and facilitate
translocation. A tissue contact surface of the support structure is
bonded to the membrane and resists the tendency of the excised
tissue to distort or shrink. The graft is supported by the support
structure and a feature of the support structure facilitates
translocating the graft along with the support structure.
[0158] In one example, the support structure remains permanently
bonded to the graft after placement of the graft in the new
position in the eye. In one example, the support structure is of a
temporary nature and can be selectively disbonded from the graft
after translocating the graft and before formation of a fibrous
capsule. The graft can be disbonded by various means including
application of an electric current, exposure to a chemical
releasing agent or by mechanical removal.
[0159] The support structure can be configured to harvest and
translocate a graft in the form of a pedicle or a circular (or
other closed) shape.
[0160] The support structure can be fabricated by electrical
discharge machining (EDM), by photolithography or other
semiconductor fabrication technology.
[0161] Manipulation of the support structure can endanger the RPE
or cause a tear or other damage. Such hazards can be mitigated by
an embodiment of the present subject matter including a mesh or
screen that encircles the support structure. The mesh or screen can
be disposed on one or both sides of the membrane. In one example, a
tool is engaged with a hole in the surface of the support structure
(a through hole or a blind hole) and an end of the tool stabilizes
the adjacent membrane. Retraction of the support structure would
also mitigate injury to the surrounding tissues.
[0162] In one example, the support structure is configured for use
on one side of the membrane. As such, the support structure is
bonded to the RPE side or the choroid side of the membrane. In one
example, the support structure is configured for use on two sides
of the membrane and the graft is sandwiched between.
[0163] In one example, the features are used to deliver RF energy
sufficient to tack the support structure to the membrane. As such,
the RF energy is delivered at multiple sites (or features)
distributed about the periphery. In one example, the features are
electrically isolated from a main electrode and energy is
selectively applied to activate particular portions. In one
example, the features include isolated electrodes that are
selectively deployable. In one example, the features maintain a
retracted position until energized (by body temperature or above,
or electrical energy) and are deployed to allow harvesting of the
graft. In one example, each feature includes a two-conductor
element that can be selectively bonded to underlying tissue using
bipolar RF energy or laser energy.
[0164] In one example, the support structure includes a ring having
a diameter of 3-5 mm.
[0165] In one example, a posterior ring of the support structure is
inserted into the suprachoroidal space and an anterior ring of the
support structure is placed on the RPE. The two rings are aligned
with each other over the donor site. A source of RF energy is
applied to the two rings which serve as electrodes. The RF energy
causes the tissue to bond to the rings.
[0166] In one example, the anterior ring includes at least two
separate conductors and is positioned on the RPE surface. The
separate conductors of the support structure are electrically
isolated and when coupled to a RF energy source, serve as
electrodes to bond the anterior ring to the tissue. After bonding
the anterior ring, the posterior ring is aligned and placed in
position in the suprachoroidal space. This procedure may reduce the
incidence of damage to the RPE surface.
[0167] The graft is carried to the translocation site by
maneuvering and manipulating the support structure after excising
the tissue from the membrane. In one example, the target (or
translocation) site underlies the macula. Reattachment of the
retina will likely hold the graft in position by the natural RPE
pumping mechanism that dehydrates the subretinal space. This
creates a "vacuum seal" of the graft and support ring in position.
Alternatively, the graft can be held in position by tacking the
support structure to the membrane at the new site. Features or
other small electrode elements of the support structure can be used
to fix the graft in position. The features or other small
electrodes may be the same or different from those features used
for affixing the support structure at the donor site. It is
expected that blood vessels from the native choroid will grow into
the graft, vascularize the donor tissue, and help secure the tissue
in position.
[0168] In one example, the support structure includes a double ring
structure. For example, an outer ring remains at the donor site,
and the inner ring, which is bonded to the graft tissue, disengages
from the outer ring, and is relocated to the target site. This
configuration allows a compressive ring at the recipient site (to
prevent shrinkage), and compression ring at the donor site (to
prevent bleeding).
[0169] In one example, a bioadhesive serves as the support
structure as well as a bonding agent for attachment to the graft.
The bioadhesive is compatible with the body environment and can be
applied to one or more tissue layers. The bioadhesive cures to a
rigid or semi-rigid state and provides support for the excised
graft.
[0170] In one example, the support structure is mechanically
coupled to the graft. For example, a graft is disposed between a
support structure having two clamping surfaces (as shown in FIGS.
19A and 19B). A mechanical clamping force sandwiches the tissue
between the two surfaces. In such a configuration, the surrounding
tissue is coagulated and the graft is excised without having
activated the support structure. A clamping force can be described
as a mechanical bond.
[0171] In one example, a manipulation tool is integrated as a unit
with the support structure. As such, the manipulation tool portion
is not readily separable from the support structure portion and the
unit is used for both harvesting and placing of the graft after
which the unit is wholly removed from the eye. For example, in
particular embodiments illustrated at FIGS. 12B and 12C, the guide
(tool) remains attached to the support structure.
[0172] This document discusses, among other things, a system of
translocating a graft for treatment of age-related macular
degeneration. Structural support devices, manipulation tools and
corresponding methods are described. In the case of an external
source of tissue, one method includes forming an incision to
accommodate insertion of the graft.
[0173] It is to be understood that the above description is
intended to be illustrative, and not restrictive. For example, the
above-described embodiments (and/or aspects thereof) may be used in
combination with each other. Many other embodiments will be
apparent to those of skill in the art upon reviewing the above
description. The scope of the invention should, therefore, be
determined with reference to the appended claims, along with the
full scope of equivalents to which such claims are entitled. In the
appended claims, the terms "including" and "in which" are used as
the plain-English equivalents of the respective terms "comprising"
and "wherein." Also, in the following claims, the terms "including"
and "comprising" are open-ended, that is, a system, device,
article, or process that includes elements in addition to those
listed after such a term in a claim are still deemed to fall within
the scope of that claim. Moreover, in the following claims, the
terms "first," "second," and "third," etc. are used merely as
labels, and are not intended to impose numerical requirements on
their objects.
[0174] The Abstract of the Disclosure is provided to comply with 37
C.F.R. .sctn. 1.72(b), requiring an abstract that will allow the
reader to quickly ascertain the nature of the technical disclosure.
It is submitted with the understanding that it will not be used to
interpret or limit the scope or meaning of the claims. In addition,
in the foregoing Detailed Description, various features may be
grouped together to streamline the disclosure. This method of
disclosure is not to be interpreted as reflecting an intention that
the claimed embodiments require more features than are expressly
recited in each claim. Rather, as the following claims reflect,
inventive subject matter may lie in less than all features of a
single disclosed embodiment. Thus the following claims are hereby
incorporated into the Detailed Description, with each claim
standing on its own as a separate embodiment.
* * * * *