U.S. patent application number 15/981843 was filed with the patent office on 2018-09-20 for corneal implants and methods and systems for placement.
The applicant listed for this patent is Yichieh Shiuey. Invention is credited to Yichieh Shiuey.
Application Number | 20180263756 15/981843 |
Document ID | / |
Family ID | 46332281 |
Filed Date | 2018-09-20 |
United States Patent
Application |
20180263756 |
Kind Code |
A1 |
Shiuey; Yichieh |
September 20, 2018 |
CORNEAL IMPLANTS AND METHODS AND SYSTEMS FOR PLACEMENT
Abstract
A system comprising a hollow member is used to deliver a
constrained corneal implant into a corneal pocket. The hollow
member may be tapered and the system may further include an implant
deformation chamber and an axial pusher to advance the implant
through the hollow member.
Inventors: |
Shiuey; Yichieh; (San Jose,
CA) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Shiuey; Yichieh |
San Jose |
CA |
US |
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Family ID: |
46332281 |
Appl. No.: |
15/981843 |
Filed: |
May 16, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12405900 |
Mar 17, 2009 |
9999497 |
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15981843 |
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PCT/US08/61656 |
Apr 25, 2008 |
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12405900 |
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11741496 |
Apr 27, 2007 |
8029515 |
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PCT/US08/61656 |
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11341320 |
Jan 26, 2006 |
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11741496 |
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60648949 |
Jan 31, 2005 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 2002/1699 20150401;
A61F 2/148 20130101; A61F 9/007 20130101; A61F 2/145 20130101; A61F
2/147 20130101; A61F 2/142 20130101 |
International
Class: |
A61F 2/14 20060101
A61F002/14; A61F 9/007 20060101 A61F009/007 |
Claims
1. A method for delivering a corneal implant to a cornea, said
method comprising: constraining the implant at an initial width;
advancing the implant through a tapered chamber to reduce the width
of the width wherein opposed edges of the implant are curved
radially inwardly as the implant is advanced; and releasing the
constrained implant into the cornea at the reduced width.
2. A method as in claim 1, wherein the implant comprises a polymer
having a tensile strength in the range from 0.1 MPa to 4 MPa and a
modulus in the range from 0.1 MPa to 5 MPa.
3. A method as in claim 1, further comprising placing the implant
on a thin, flexible carrier prior to constraining the implant and
the carrier.
4. A method as in claim 1, wherein constraining comprises closing
semi-circular halves of a deformation chamber on the implant.
5. A method as in claim 1, wherein advancing comprises pushing a
pusher member against the corneal implant.
6. A method as in claim 5, wherein a forward portion of the pusher
member conforms to the interior of the tapered chamber as the
pusher member is pushed.
7. A method as in claim 1, wherein the corneal implant is a
biological implant.
8. A method as in claim 7, wherein the biological implant comprises
a lamellar corneal stromal endothelial transplant or DMEK
graft.
9. A method as in claim 1, wherein the implant is a synthetic
implant.
10. A system for delivering corneal implants, said system
comprising: a hollow member having a proximal end and a distal end
configured for insertion into a pocket within a cornea and having
an axial hollow passage which tapers in the distal direction; and
an axial pusher disposed in the hollow axial passage of the hollow
member to engage and axially advance a constrained corneal implant
through the hollow passage, wherein the axial hollow passage
includes inwardly oriented arcuate surface which evert the edges of
the corneal implant radially inwardly as the insert is axially
advanced through the passage.
11. A system as in claim 10, wherein the axial pusher includes a
thin, flexible carrier for the implant and wherein the carrier has
edges which are everted together with the edges of the corneal
implant.
12. A system as in claim 11, further comprising a corneal implant
constrained within the hollow passage on a distal side of the axial
pusher.
13. A system as in claim 11, wherein the axial pusher is tapered in
a distal direction.
14. A system as in claim 13, wherein the axial pusher is deformable
so that it will reduce in diameter as it is distally advanced
through the tapered hollow passage.
15. A system as in claim 14, wherein the axial pusher has a
cross-sectional profile which is similar in shape to the
cross-sectional profile of the hollow passage.
16. A system as in claim 15, further comprising an implant
deformation chamber coupled to the hollow member.
17. A corneal implant comprising: a scaffold having a
three-dimensional structure including discrete elements defining a
shape with a mostly empty volume therein, wherein the shape is
selected to provide a vision correction when placed in a corneal
pocket.
18. A corneal implant as in claim 17, wherein the shape flattens
the cornea when placed in the pocket to correct myopia.
19. A corneal implant as in claim 17, wherein the shape steepens
the cornea when placed in the pocket to correct hyperopia.
20. A corneal implant as in claim 17, wherein the shape steepens
the central cornea and flattens the steep axis of the cornea when
placed in the pocket to lessen hyperopia and reduce
astigmatism.
21. A corneal implant as in claim 17, where the shape flattens the
central cornea and the steep axis of the cornea when placed in the
corneal pocket in order to lessen myopia and reduce
astigmatism.
22. A corneal implant as in claim 17, further comprising a lens
wherein the shape changes the shape of the cornea when placed in
the pocket and the lens provides additional refractive error
correction.
23. A corneal implant as in claim 17, composed of a material such
that the body has a tensile strength in the range from 2.5 MPa to
53 GPa and a Young's modulus in the range from 3 MPa to 5 TPa.
24. A corneal implant as in claim 23, wherein the material
comprises an acrylic copolymer.
25. A corneal implant as in claim 23, wherein the material
comprises a silicone or collagen copolymer.
26. A corneal implant as in claim 23, wherein the shape flattens
the cornea when placed in the pocket to correct myopia.
27. A corneal implant as in claim 23, wherein the shape steepens
the cornea when placed in the pocket to correct hyperopia.
28. A corneal implant as in claim 23, wherein the shape steepens
the central cornea and flattens the steep axis of the cornea when
placed in the pocket to lessen hyperopia and reduce
astigmatism.
29. A corneal implant as in claim 23, further comprising a lens
wherein the shape changes the shape of the cornea when placed in
the pocket and the lens provides additional refractive error
correction.
30. A corneal implant as in claim 23, wherein the material
comprises a metal.
31. A corneal implant as in claim 30, wherein the metal is selected
from the group consisting of gold, titanium, and nickel-titanium
alloy, copper-zinc-aluminum-nickel alloy, and
copper-aluminum-nickel alloy.
32. A corneal implant as in claim 23, wherein the material
comprises a fullerene.
33. A corneal implant as in claim 32, wherein the fullerene is
selected from the group consisting of carbon nanotubes, spheres,
ellipsoids, planes, and ribbons.
34. A method for delivering a corneal implant to a cornea, said
method comprising: forming a central anterior opening in the
cornea; introducing the implant to the opening, wherein the implant
includes a center optic and a peripheral rim and wherein said
peripheral rim is constrained while being introduced; and releasing
the peripheral rim from constraint so that the peripheral rim
radially expands to engage corneal tissue circumscribing the
central anterior opening.
35. A method as in claim 34, wherein forming comprises creating an
opening extending from an anterior corneal surface through the full
thickness of the cornea.
36. A method as in claim 34, wherein forming comprises creating a
partial opening which does not extend through the full thickness of
the cornea.
37. A method as in any one of claims 34 to 36, wherein the implant
is introduced in a posterior direction into the central anterior
opening.
38. A method as in any one of claims 34 to 36, further comprising
forming a pocket through a lateral opening in the cornea, wherein
the implant is introduced through the lateral opening into the
pocket and the central anterior opening.
39. A method as in claim 34, wherein the corneal implant has a
single rim about a mid-sectional region, wherein the rim extends
into corneal tissue circumscribing the central anterior
opening.
40. A method as in claim 34, wherein the corneal implant has an
anterior rim and a posterior rim, wherein the anterior rim radially
expands over an anterior corneal surface circumscribing the central
anterior opening and the posterior rim radially expands over a
posterior corneal surface circumscribing the central anterior
opening.
41. A method as in claim 34, wherein the center optic is less
compressible than the rim so that the center optic is not
substantially compressed as the implant is being introduced.
42. A method as in claim 34, wherein both the rim and the center
optic are compressed while the implant is being introduced.
43. A method as in claim 34, wherein introducing comprises
advancing the implant through a tube having a width which
compresses at least the rim and releasing comprises advancing the
implant out of the tube.
44. A method as in claim 43, wherein the implant is introduced
through a passage in the tube, wherein the passage is tapered in a
distal direction to progressively compress the rim before the
implant is released.
45. A reversibly deformable corneal implant comprising: a center
optic having an anterior surface, a posterior surface, and a
peripheral wall; and at least one rim circumscribing at least a
portion of the peripheral wall; wherein, at least the rim is
radially compressible to allow the implant to be radially
constrained for insertion into a corneal pocket or opening.
46. A corneal implant as in claim 45, wherein the center optic and
at least one rim comprise a monolithic structure.
47. A corneal implant as in claim 46, wherein the monolithic
structure was formed by molding.
48. A corneal implant as in claim 46, wherein the monolithic
structure was formed by machining a block of material.
49. A corneal implant as in any one of claims 45 to 48, consisting
of a hydrogel.
50. A corneal implant as in any one of claims 45 to 48, consisting
essentially of a material selected from the group consisting of
collagen, polyurethanes, poly(2-hydroxyethylmethacrylate),
polyvinylpyrolidone, polyglycerolmethacrylate, polyvinyl alcohol,
polyethylene glycol, polymethacrylic acid, silicones,
polyfluorocarbons, and polymers with phosphocholine.
51. A corneal implant as in any one of claims 45 to 48, consisting
essentially of a material selected from the group consisting of a
copolymer of hydroxyethyl methacrylate (HEMA) and methyl
methacrylate (MMA).
52. A corneal implant as in any one of claims 45 to 48, consisting
essentially of a co-polymer of hydroxyethyl methacrylate (HEMA),
methyl methacrylate (MMA), and methacrylic acid.
53. A corneal implant as in any one of claims 45 to 48, comprising:
(a) a multi-network hydrogel with a first network interpenetrated
with at least one other network, wherein said first network and
said other networks are based on biocompatible polymers and at
least one of said network polymers is based on a hydrophilic
polymer; (b) epithelization promoting biomolecules covalently
linked to the surface of said multi-network hydrogel; and (c)
corneal epithelial cells or cornea-derived cells adhered to said
biomolecules.
54. A corneal implant as in any one of claims 45 to 48, composed at
least partially from a material selected from the group consisting
of collagen and N-isopropylacrylamide, collagen and
1-ethyl-3.3'(dimethyl-aminopropyl)-carbodiimide, and collagen and
N-hydroxysuccinimide (EDC/NHS).
55. A corneal implant as in claim 42, comprising a single rim
circumscribing the center optic location intermediate the anterior
and posterior surfaces.
56. A corneal implant as in claim 51, wherein the peripheral wall
anterior to the rim is oriented at an angle in the range from
1.degree. to 144.degree. relative to the plane that passes through
the junction of the peripheral wall and the rim.
57. A corneal implant as in claim 50, wherein the center optic has
a cylindrical peripheral wall with a diameter in the range from 3
mm to 9 mm and a thickness in the anterior-posterior direction in
the range from 0.1 mm to 3 mm.
58. A corneal implant as in claim 57, wherein the rim has a width
in the range from 3.5 mm to 12 mm.
59. A corneal implant as in claim 52, wherein the rim has a
generally circular periphery with a concave profile in the
posterior direction.
60. A corneal implant as in claim 45, comprising at least an
anterior rim circumscribing at least a portion of the peripheral
wall at or near the anterior surface and a posterior rim
circumscribing at least a portion of the peripheral wall at or near
the posterior surface.
61. A corneal implant as in claim 55, wherein the center optic has
a cylindrical peripheral wall with a diameter in the range from 3
mm to 9 mm and a thickness in the anterior-posterior direction in
the range from 0.1 mm to 3 mm.
62. A corneal implant as in claim 56, wherein the anterior and
posterior rims have widths in the range from 3.5 mm to 12 mm.
63. A corneal implant as in claim 57, wherein the anterior and
posterior rims have circular peripheries and convex or tapered
anterior surfaces.
64. A corneal implant as in claim 23, where the shape flattens the
central cornea and the steep axis of the cornea when placed in the
corneal pocket in order to lessen myopia and reduce astigmatism.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent Ser. No.
12/405,900 filed on Mar. 17, 2009 (pending) which is a
continuation-in-part of PCT/US08/61656 (attorney docket no.
022253-000230PC), filed on Apr. 25, 2008, which was a
continuation-in-part of application Ser. No. 11/741,496 (Attorney
Docket No. 022253-000220US), filed on Apr. 27, 2007, which was a
continuation-in-part of application Ser. No. 11/341,320 (Attorney
Docket No. 022253-0002 lOUS), filed on Jan. 26, 2006, which claimed
the benefit of provisional application No. 60/648,949 (Attorney
Docket No. 022253-000200US), filed on Jan. 31, 2005, the full
disclosures of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] There are many different types of corneal implants that have
been developed for the treatment of refractive error and disease.
Because of limitations in the methods of creating corneal pockets,
these implants have all been designed for placement in the cornea
by creation of a corneal incision which is either similar in size
to the smallest dimension of the implant or larger. Recently, two
methods of corneal pocket creation have been devised which can
create a pocket with an external opening width that is less than
the maximum internal width of the pocket. These two methods are
pocket creation by the femtosecond laser and, of particular
interest, cornea cutting, as described in US 2004/0243159 and
0243160, invented by the inventor herein, the full disclosure of
which is incorporated herein by reference.
[0003] It is advantageous to have a biocompatible corneal implant
that can be placed through an external incision that is less than
the width of the implant, especially an external incision that is
less than half of the width of the implant. It is particularly
advantageous if the corneal implant can be placed through an
incision that does not require suturing for closure, typically
being 3 mm or less. Such a small external incision also decreases
induced surgical astigmatism and speeds up the recovery time for
the patient. Moreover, it is useful to have a relatively large
implant that can be placed through a relatively small incision. For
example, a lens implant that is larger is more likely to give good
quality vision, especially in a patient with large pupils. It is
also advantageous to have a simple and reliable delivery system for
the corneal implant.
[0004] Intraocular lenses (IOL's) for cataract surgery have been
designed to be placed through a small incision. These small
incision cataract surgery lenses cannot practically be used within
a corneal pocket. Most small incision cataract surgery lens
implants are usually too thick to be placed within a corneal
pocket. For example, the typical thickness of a cataract surgery
lens implant is 1 mm or more which is substantially thicker than
the human cornea, which is usually between 0.5 to 0.6 mm. Some
corneal implants that have been designed only have a thickness of
about 0.05 mm. Moreover, the cataract surgery lens implants have
haptics, which are extensions from the lens implant designed to
keep the lens implant fixated within the capsular bag. Haptics are
not present and not necessary for corneal implants. Finally, the
cataract surgery lens implants are not designed to be biocompatible
with the cornea and would not be tolerated as corneal implants.
[0005] The delivery systems designed for small incision cataract
surgery lens implants are not well adapted for use as a delivery
system for small incision corneal implants. These delivery systems
have been designed for cataract surgery lens implants that are much
thicker than the usual corneal implant. The delivery systems for
small incision cataract surgery lens implants are designed to
accommodate haptics, which would not be present on a corneal lens
implant. It has been found that at least some commercially
available corneal implants are destroyed when placed through a
standard IOL injector. Similarly, biological corneal implants
placed through a standard IOL injector will often show severe
histological damage, such as endothelial damage.
[0006] Corneal implants can be made of either synthetic materials
(e.g., prostheses) or can be biological in origin (e.g., transplant
grafts). Recently, two new surgical techniques for placement of a
lamellar corneal stromal endothelial transplant grafts have been
devised. These surgical techniques are useful in the treatment of
endothelial diseases of the cornea such as Fuchs' endothelial
dystrophy and pseudophakic bullous keratopathy. One of these
techniques is referred to as deep lamellar endothelial keratoplasty
(DLEK). In this technique, a pocket is made within the cornea and
diseased corneal endothelium is excised along with a layer of
corneal stroma. Healthy lamellar corneal stromal endothelial tissue
is then transplanted into the space left by the excised diseased
tissue. Another technique is called Descemet's stripping automated
endothelial keratoplasty (DSAEK or DSEK). In this technique, a
lamellar corneal stromal endothelial transplant graft is
automatically created using either a microkeratome or a laser. The
diseased corneal endothelium is stripped away with surgical
instruments and then the lamellar corneal stromal endothelial
transplant graft is inserted into the anterior chamber through a
full thickness corneal incision. The graft is then held in place
against the stripped posterior corneal stromal surface by an air
bubble until the graft is able to heal in position.
[0007] In both DLEK and DSAEK it is advantageous to be able to
insert a relatively large transplant atraumatically through a small
corneal or scleral incision. A larger transplant has more corneal
endothelial cells and should produce better results in the
treatment of corneal endothelial diseases. However, a significant
problem with prior art methods of inserting corneal transplants
into the anterior chamber through a small incision is that they all
involve folding of the transplant and grasping of the transplant
with forceps. Moreover, the transplant is typically severely
compressed as it passes through the corneal incision. It has been
demonstrated through the use of vital staining techniques that many
of the delicate corneal endothelial cells of a transplant are
killed during the prior art insertion process. Like corneal
transplant grafts for DSAEK or DLEK, synthetic corneal implants
(e.g., corneal inlay prostheses) are also very delicate. In many
cases, these corneal inlays may be as thin as 30 to 40 microns,
which make them very easily torn by forceps. Therefore, there is
also a need for an improved method to place these corneal inlays
atraumatically through a small incision.
[0008] Delivery systems for placement of IOLs into the posterior
chamber through a small incision have been described. However,
these delivery systems designed for small incision cataract surgery
IOLs are not well adapted for use as a delivery system for corneal
implants through a small incision. For example, a typical IOL
implant may be 1 mm or more in thickness, whereas the typical
corneal transplant for DLEK or DSAEK is between 0.1 to 0.15 mm in
thickness. Moreover, as has been noted before, the thickness of a
corneal inlay prosthesis may be as little as 30 to 40 microns. In
addition, the size and shape of an IOL is different from that of a
corneal transplant. An IOL is typically 12 to 13 mm in length, 5 to
6 mm wide, and 1 mm or more in thickness, whereas a corneal
transplant DSEK graft would typically be circular in shape and
would have a diameter of 8 to 9 mm and a thickness from 0.1 mm to
0.2 mm. In the case of a corneal prosthesis implant, the diameter
may range from 1 mm to 10 mm and the thickness from 0.01 mm to 0.6
mm. Finally, IOL delivery systems are designed to greatly compress
the IOL during the insertion process, whereas this type of
compression would be likely to either damage or destroy a living
corneal transplant. The amount of compression used for IOL delivery
systems could also damage the much thinner corneal implants.
2. Description of the Background Art
[0009] Corneal implants and methods for their implantation are
described in U.S. Pat. Nos. 4,842,599; 5,112,350; 5,698,192;
5,755,785; 5,843,185; 6,106,552; 6,592,621; 6,814,755; and
7,364,674; and in U.S. Patent Application Publications
2002/0065555; 2003/0014106; 2003/0093066; 2003/0229303;
2005/0080485; 2005/0119737; 2006/0083773; 2006/0134050;
2006/0235428; and 2007/0129797.
BRIEF SUMMARY OF THE INVENTION
[0010] Improved systems and methods for implanting corneal implants
are provided by the present invention. The phrase "corneal implant"
refers to any natural (biological) or synthetic implant or graft
that may be implanted into a human cornea. These systems and
methods can place a corneal implant through a corneal incision that
is substantially less than the width of the implant. The placement
of the implant may be within or between any of the layers of the
cornea including epithelium, Bowman's membrane, stroma, Descemet's
membrane, and endothelium. In preferred aspects, the corneal
incision is equal or less than half of the width of the implant. In
additional preferred aspects, the system allows the placement of a
corneal implant through an incision that is less than or equal to 3
mm, which advantageously avoids the need for suturing of the
incision in most cases and greatly decreases the chance of unwanted
induced astigmatism.
[0011] In accordance with a first aspect of the present invention,
the corneal implant is reversibly deformable in shape to allow its
passage through a corneal incision that is equal or less than half
of the width of the implant. The corneal implant is bio-compatible
with the cornea, the eye, and the body. In certain embodiments,
synthetic material which can meet these criteria may potentially be
used for the implant. Suitable synthetic materials include one or
more compounds selected from the group consisting of collagen,
polyurethanes, poly(2-hydroxyethylmethacrylate),
polyvinylpyrolidone, polyglycerolmethacrylate, polyvinyl alcohol,
polyethylene glycol, polymethacrylic acid, silicones, acrylics,
polyfluorocarbons, and polymers with phosphocholine. In other
embodiments, the grafts may comprise human corneas harvested for
use in transplants such as grafts or DSEK or a graft which consists
only of Descemet's membrane and endothelium. Transplantation of
only Descemet's membrane and endothelium is referred to as
Descemet's Membrane Endothelial Keratoplasty (DMEK). In the future,
biological cornea implants may be obtained from other sources such
as animals, genetically modified animals, in vitro cell culture, or
the like.
[0012] In a preferred embodiment, the material comprises a
hydrogel. The hydrogel may comprise or consist essentially of
collagen, polyurethanes, poly(2-hydroxyethylmethacrylate),
polyvinylpyrolidone, polyglycerolmethacrylate, polyvinyl alcohol,
polyethylene glycol, polymethacrylic acid, silicones,
polyfluorocarbons, and polymers with phosphocholine. Alternatively,
the hydrogel may comprise or consist essentially of a material
selected from the group consisting of a copolymer of hydroxyethyl
methacrylate (HEMA) and methyl methacrylate (MMA). Still further
alternatively, the hydrogel may comprise or consist essentially of
a co-polymer of HEMA, MMA, and methacrylic acid. As a still further
alternative, the hydrogel may comprise or consist essentially of
(a) a multi-network hydrogel with a first network interpenetrated
with at least one other network, wherein said first network, said
other networks are based on biocompatible polymers and at least one
of said network polymers is based on a hydrophilic polymer; (b)
epithelization promoting biomolecules covalently linked to the
surface of said double network hydrogel; and (c) corneal epithelial
cells or cornea-derived cells adhered to said biomolecules.
[0013] In an alternative preferred embodiment, the corneal implant
is formed from a material comprising of a reversibly deformable
acrylic copolymer, such as those used for intraocular lenses. These
materials have excellent tensile strength and can be elongated as
much as 250% before breaking. Such characteristics allow injection
to be performed according to the present invention without damage
to the implant. Examples of suitable materials include copolymers
of hydroxyethyl methacrylate and methyl methacrylate (e.g.,
materials available under the tradenames Contamac C126, C118, C121
materials, Benz IOL 25UV, and Benzflex 26UV). In additional
preferred aspects, the deformable polymer is hydrophilic in nature
to allow smooth wetting of the optical surface of the implant.
Wetability is an important characteristic of a corneal implant
which allows the tear film to act as a good optical interface. In
yet other preferred aspects, the material contains between 1% and
20% methacrylic acid. More preferably, 5 to 10% methacrylic acid,
which advantageously allows the linkage of tethering molecules such
as polyethylene glycol to the surface of the implant. Tethering
molecules will allow reactive moieties to be linked to the surface
of the implant to create useful implant characteristics such as
promotion of epithelialization or the ability to create chemical
bonds with the cornea. Other preferred physical characteristics of
the corneal implant material would be a tensile strength in the
range of 0.1 to 4 MPa, more preferably a tensile strength in the
range of 0.6 to 2.6 MPa. In addition, a modulus of 0.1 to 5 MPa,
more preferably a modulus in the range of 0.2 to 3.1 MPa would also
be desirable. Although we have described specific types of acrylic
copolymers as suitable for corneal implants, other types of
materials (e.g., silicone or collagen polymers) which have similar
physical and chemical characteristics as those described above,
could also be used and are all considered part of the present
invention.
[0014] In other preferred embodiments, holes or pores may be
provided in the implant to increase biocompatibility of the implant
by allowing nutritive substances and gasses (e.g., water, glucose,
and oxygen) to pass easily through the implant in order to maintain
healthy metabolism in the cornea. In still other preferred
embodiments, the polymer material may have thermoplastic properties
such that the implant will have one desired shape at one
temperature and then deform into another desired shape at a second
temperature. In yet other preferred aspects, the corneal implant
may comprise one or more separate, smaller components that can be
assembled in situ placed inside the corneal pocket. Such in situ
assembly advantageously minimizes the incision size needed to
insert a corneal implant.
[0015] The corneal implant may be of any shape that allows it to be
placed within a corneal pocket. In preferred embodiments, the
corneal implant is substantially round. In alternate preferred
embodiments, the corneal implant is not round. A corneal implant
which is not round has the advantage that it is less likely to
rotate within a corneal pocket. This property is useful in the
implants which correct for astigmatism.
[0016] In preferred other embodiments, the corneal implant is a
lens. The lens can be a monofocal, multifocal, Fresnel,
diffractive, prismatic, or other type of lens that can be used to
treat refractive error such as myopia, hyperopia, astigmatism,
presbyopia, or ocular disease (e.g., macular degeneration). The
lens may also be made of a polymer that can have its refractive
properties adjusted permanently or reversibly by electromagnetic
energy as described in U.S. Patent Application 2003/0173691 to
Jethmalani.
[0017] The corneal implant may comprise a prosthesis that is used
to replace or augment a portion of the cornea. Such implants are
useful in restoring optical clarity or structural integrity to the
cornea in lieu of corneal transplantation. The corneal prosthesis
may be used to replace only a partial thickness portion of the
cornea or a full thickness portion of the cornea. In preferred
aspects, the corneal implant may be coated with extracellular
matrix proteins such as collagen, fibronectin, laminin, substance
P, insulin-like growth factor-1, or peptide sequences such as
fibronectin adhesion-promoting peptide (FAP). In additional
preferred aspects, these extracellular matrix proteins and peptides
are tethered or otherwise bound to the epithelial side of the
corneal implant by the methods described in U.S. Pat. No.
6,689,165, to Jacob et al. Such surface treatments are intended to
promote epithelialization on the surface of a corneal implant.
[0018] In alternate preferred embodiments, the surface of the
corneal implant may have a texture that promotes epithelialization
on the surface of the corneal implant. Textures, such as surface
indentations, may be applied to the surface of the corneal implant
to promote epithelialization, as described in U.S. Pat. No.
6,454,800 to Dalton et al.
[0019] In yet other alternate preferred embodiments, the corneal
implant may be manufactured from a material that promotes
epithelialization on the surface of the corneal implant. Examples
of such materials include polymers selected from the group
consisting of collagen and N-isopropylacrylamide, collagen and
1-ethyl-3.3'(dimethyl-aminopropyl)-carbodiimide as well as collagen
and N-hydroxysuccinimide (EDC/NHS). In further preferred aspects,
the polymer may additionally contain extracellular matrix proteins
such as fibronectin, laminin, substance P, insulin-like growth
factor-1, or peptide sequences such as fibronectin
adhesion-promoting or peptide (FAP).
[0020] Optionally, at least a portion of the device may contain
holes or be porous in nature so as to promote growth of corneal
tissue into and through the implant in order to promote retention
and biocompatibility. Such porous implants may be fabricated as
described in U.S. Pat. No. 6,976,997 to Noolandi et al. and U.S.
Pat. No. 5,300,116 to Chirila et al.
[0021] Optionally, at least a portion of the lens or other corneal
implant may be colored. Coloration can be useful for cosmetic
purposes or for therapeutic purposes (e.g., treatment of aniridia).
For example, methods of applying biocompatible inks, which are well
known in colored contact lens manufacturing, may be used to color
the corneal implant. Particular coloring methods are described in
U.S. Patent Applications 2003/0054109 and 2003/0025873, the
disclosures of which are incorporated herein by reference. In
alternate preferred aspects, the corneal implant may be colored
with photosensitive inks that change color with exposure to
electromagnetic waves. This allows the color of the corneal implant
to be adjusted permanently or reversibly by exposure to
electromagnetic waves in vivo.
[0022] Optionally, the corneal implant may also contain an
ultraviolet filter compound of the benzophenone type such as 3-(2
Benzyotriazolyl)-2-Hydroxy-5-Tert-Octyl-Benzyl Methacryl Amide.
[0023] In alternate preferred embodiments, the corneal implant may
comprise a scaffold having a three-dimensional structure including
discrete elements defining a peripheral shape with a mostly empty
interior volume therein. The predetermined shape is selected to
provide a vision correction when placed in a corneal pocket. The
scaffold can be inserted into a corneal pocket for the purpose of
reshaping or supporting the cornea.
[0024] Reshaping of the cornea is useful for correction of various
vision problems including refractive errors as well as for the
treatment of ectactic corneal disorders such as keratoconus or
pellucid marginal degeneration. In preferred aspects the corneal
implant scaffold consists of a three-dimensional structure where it
is not possible for a single plane to pass through all of the
elements of the structure. In other preferred aspects, the corneal
implant scaffold is reversibly deformable so that it may be
introduced to a corneal packet by the devices and methods of the
present invention. Also, the corneal implant scaffold should have a
rigidity that is greater than a mammalian cornea, so that insertion
of the scaffold into a corneal pocket will result in either a
change in shape of the cornea or be able to provide increased
structural strength to the cornea.
[0025] In preferred aspects of the present invention, the tensile
strength of the material used to make the corneal scaffold implant
should be in the range between 2.5 MPa and 53 GPa and the Young's
modulus between 3 MPa to 5 TPa. More preferably, the present
invention should have a tensile strength in the range between 800
to 2000 MPa and a Young's modulus between 25 to 100 GPa. In other
preferred aspects, the corneal implant scaffold is made of a
biocompatible and reversibly deformable polymer or a biocompatible
and reversibly deformable metal or alloy (e.g., gold, titanium,
nickel-titanium alloy, copper-zinc-aluminum-nickel alloy, and
copper-aluminum-nickel alloy).
In yet other preferred aspects, the corneal scaffold is made from a
fullerene including, but not limited to carbon nanotubes, spheres,
ellipsoids, planes, or ribbons. In additional preferred aspects,
the width of the structural elements in the corneal implant
scaffold is 0.001 mm to 1 mm, more preferably 0.3 to 0.6 mm. In
preferred aspects, the thickness of the structural elements in the
scaffold is 0.001 mm to 0.5 mm, more preferably 0.01 mm to 0.06 mm.
In alternate preferred aspects, the cornea scaffold implant may
also include a lens within the structure, which advantageously
combines correction of refractive error by both changing of the
shape of the cornea and the addition of another lens. The cornea
scaffold may be shaped in ways to correct for myopia, hyperopia,
astigmatism, and presbyopia. For example, a shape which flattens
the central cornea will correct for myopia. A shape which steepens
the central cornea will correct for hyperopia. A shape which
flattens the central cornea and flattens the steep axis of the
cornea will correct for myopia and astigmatism. A shape that
steepens the central cornea and flattens the steep axis of the
cornea will correct for hyperopia and astigmatism. A shape that
produces multifocality of the cornea will correct for presbyopia.
Examples of shapes which can correct for presbyopia include a shape
which steepens the central cornea while keeping the peripheral
corneal shape the same or a shape which steepens the peripheral
cornea while keeping the central corneal shape the same.
[0026] A scaffold corneal implant has a number of advantages
compared to a corneal implant which is mostly solid. For example,
if a high degree of refractive correction is desired, a centrally
located solid corneal implant will need to be fairly thick. A
relatively thick solid corneal implant will decrease the
permeability of essential nutrients and gases to the anterior and
posterior to the implant. Lack of normal nutrient and gas transport
could result in undesirable consequences such as melting or
necrosis of the corneal tissue. In contrast, a thin scaffold
implant can correct large amounts of refractive error without
significantly interfering with corneal physiology because most of
the implant is empty space. Moreover, because the scaffold corneal
implant is mostly empty space, the scaffold corneal implant can be
made to be highly compressible which can allow for insertion
through a smaller incision and thereby decrease recovery time for
the patient.
[0027] In yet other alternate preferred embodiments, the corneal
implant may be a device. Examples of potential implant devices
include miniature cameras and aqueous glucose monitors.
[0028] The improved corneal implants of the present invention are
reversibly deformable into a reduced width shape that allows
passage through a corneal incision that is substantially less than
the width of the implant when not deformed or unconstrained. In
preferred aspects, the implant will be insertable through an
incision that is less than or equal to one-half of the width of the
implant, preferably being 3 mm or less.
[0029] A specific reversibly deformable corneal implant, according
to the present invention, comprises a center optic having an
anterior surface, a posterior surface, and a peripheral wall. The
implant further includes at least one rim circumscribing at least a
portion of the peripheral wall. In contrast to the rigid implants
and lenses of the prior art, at least the rim of the corneal
implant of the present invention will be radially compressible to
allow the implant to be radially constrained for insertion into a
corneal pocket or opening. Usually, the center optic and the rim
will comprise a monolithic structure (i.e., a structure which is
substantially continuous and free from discontinuities throughout).
Such monolithic structures may be formed by molding, machining a
block of material, or other conventional corneal implant
fabrication techniques. The preferred materials will be the
hydrogel materials listed hereinbefore.
[0030] In a first specific embodiment of this corneal implant, the
implant will comprise or consist essentially of a single rim
circumscribing the center optic at a location intermediate the
anterior and posterior surfaces. Usually, but not necessarily, the
peripheral wall will be oriented at an angle in the range from
1.degree. to 144.degree. relative to plane which intersects the
junction of the rim and the peripheral wall anterior to the rim
(i.e., toward the external end of the implant when it is implanted
in a cornea). The center optic will usually have a peripheral wall
diameter in the range from 3 mm to 8 mm and a thickness in the
anterior-posterior direction in the range from 0.1 mm to 3 mm. The
rim will have a width, typically a diameter, greater than the
diameter of the peripheral wall, usually being in the range from
3.5 mm to 12 mm. The geometry of the rim will usually be circular,
but could also be oval, polygonal, or irregular, usually having a
concave profile in the posterior direction.
[0031] In an alternative embodiment, the corneal implant will
comprise at least an anterior rim circumscribing at least a portion
of the peripheral wall at or near the anterior surface of the
center optic and a posterior rim circumscribing at least a portion
of the peripheral wall at or near the posterior surface of the
center optic. The rims will both be sufficiently resilient and
collapsible so that they may be compressed against the center optic
to permit and facilitate implantation of the implant within the
cornea. With the two-rimmed implant, implantation will usually be
in an anterior-posterior direction through a hole or aperture
formed entirely through the center of the cornea, where the
anterior rim acts as a flange or retaining element, engaging the
upper surface of the cornea, and the posterior rim also acts as an
anchor or retaining element engaging the interior surface of the
cornea.
[0032] The implant embodiments having both anterior and posterior
rims, the center optic will typically be cylindrical with a
peripheral wall diameter in the range from 3 mm to 9 mm and a
thickness in the anterior-posterior direction in the range from 0.1
mm to 1.2 mm. The anterior and posterior rim diameters may be the
same or different, always being larger than the adjacent
cylindrical wall diameter, typically being in the range from 3.5 mm
to 9 mm. The anterior and posterior rims will usually have circular
peripheries and convex, conical, or otherwise tapered anterior
surfaces, but it will be appreciated that other peripheral
geometries could be employed as well.
[0033] A system, according to the present invention, comprises a
hollow member and implant mover or other axial pusher used to
deliver a corneal implant that has been constrained to fit inside
an axial hollow passage of the hollow member. The implant may be
deformed or constrained in any shape or configuration having a
"reduced width" that allows it to be fit inside of the hollow
member (e.g., rolled or folded). By "reduced width," it is meant
that a maximum width of the implant, such as a diameter of a
circular lens, is reduced by some threshold amount; typically, by
at least one-half (50%), often by at least 60%, and sometimes by
65% or more.
[0034] A system, according to the present invention, comprises a
hollow member and implant mover used to deliver a corneal implant
that has been restrained to fit inside of the hollow member. Once
the corneal implant is inside the hollow member, the implant mover
is used to move the implant into a corneal pocket or the anterior
chamber.
[0035] Optionally, the system may further comprise a deformation
chamber where the implant is deformed into a shape and size that
will fit inside the hollow member. In preferred aspects, the
deformation chamber may contain ridges, protrusions, indentations,
or recesses which help to maintain and guide the orientation of the
corneal implant within the deformation chamber during the
deformation process. In further preferred aspects, the deformation
chamber will be a size that is appropriate for the type of corneal
implant which is being used. For example, in the case of a corneal
transplant, the minimum internal dimensions of an open deformation
chamber should be between 6 and 10 mm, more preferably between 8
and 9 mm. In the case of a corneal implant prosthesis, the minimum
internal dimensions of an open deformation chamber dimensions
should be between 1 mm and 10 mm, more preferably between 2.0 mm
and 7 mm. In additional preferred aspects, the deformation area may
be tapered or funnel shaped (i.e., narrower one end than on the
other end). The tapered or funnel shape advantageously facilitates
the corneal implant to be restrained to a smaller diameter
configuration.
[0036] In other preferred aspects, the interior of the hollow
member may contain ridges, protrusions, indentations, or recesses
which help to maintain and guide the orientation of the corneal
implant as it travels inside of the hollow member. Such surface
features will be arranged to prevent rotation of the corneal
implant during insertion which might otherwise disorient the
implant within the pocket. In additional preferred aspects, the
interior of the hollow member may contain ridges, protrusions,
indentations, or recesses which guides a lamellar corneal stromal
endothelial transplant to deform in a way which allows it to travel
through a small incision without the need for folding or being
grasped by forceps. The system is designed to allow a corneal
transplant to be placed through an incision equal or less than 3
mm. However, the system can also be used to place an implant
through an incision that is greater than 3 mm.
[0037] Optionally, the system may be designed to be sterile and
disposable for single use. This advantageously decreases the chance
for contamination and infection. It also obviates the need for the
surgeon to autoclave or to provide other methods of sterilization
such as ethylene oxide. To ensure that the system will be both
sterile and single use only, we can add one or more of the
following features. In preferred aspects, one or more components of
the system may be made of a polymer which will melt or deform into
an unusable shape upon autoclaving. In additional preferred
aspects, the system may have a one way locking mechanism, such that
once the tip of the implant mover travels to a certain distance,
the implant mover is locked in position inside of the hollow
member, thus preventing reloading of another corneal implant. In
alternative preferred aspects, the system may be assembled through
the use of breakable tabs or snaps, which allows the secure
assembly of the disposable component, but which are easily
destroyed if there is an attempt to disassemble the system for
reuse.
[0038] Optionally, the system may be designed so that the corneal
implant is pre-loaded inside of the hollow member prior to use by
the surgeon. This advantageously minimizes the need for
manipulation of the delicate corneal implant by the surgeon, which
could result in damage to the corneal implant.
[0039] Once the corneal implant is inside the hollow member, the
implant mover or other axial pusher is used to engage and push the
implant into the corneal pocket. Optionally, the system may further
comprise a deformation chamber where the implant is deformed into a
shape and size that will fit inside the hollow member. In other
preferred aspects, the deformation chamber may contain ridges,
protrusions, indentations, or recesses which help to maintain
orientation of the corneal implant within the deformation chamber
during the deformation process. Optionally, the hollow member is
tapered (i.e., narrower at a distal end than at a proximal end).
Such tapering allows additional deformation (size or width
reduction) of the implant as it is advanced through the hollow
member and passes out through a smaller distal opening. The
interior of the hollow member may contain ridges, protrusions,
indentations, or recesses which help to maintain orientation of the
corneal implant as it travels inside of the hollow member. The
system for implant placement is designed to allow an implant to be
placed into a corneal pocket with an entry incision that is equal
or less than one-half of the width of the implant; however, the
system can also be used to place an implant through a corneal
incision that is greater than one-half of the width of the
implant.
[0040] The present invention further provides methods for
delivering a corneal implant to a cornea. A first exemplary method
comprises forming a central anterior opening in the cornea. The
implant is introduced through the opening, where the implant
includes a center optic and a peripheral rim, wherein the
peripheral rim is constrained while being introduced. After
introduction, the peripheral rim is released from constraint so
that the peripheral rim radially expands to engage corneal tissue
circumscribing the central anterior opening, where the rim helps
anchor the implant in place.
[0041] Forming the central anterior opening may comprise creating
an opening extending from an anterior corneal surface through the
full thickness of the cornea. Alternatively, the opening may be
only partial, extending from the anterior surface only part way
through the thickness of the cornea.
[0042] In a first exemplary embodiment of the method of the present
invention, the implant is introduced in a posterior direction into
the central anterior opening, where the peripheral wall of the
central anterior opening remains intact (i.e., there are no lateral
openings formed into the central anterior opening). Alternatively,
introducing the implant may comprise forming a pocket through a
lateral opening in the cornea, wherein the implant is introduced
through the lateral opening into the pocket and from the pocket
into the central anterior opening.
[0043] Using either introductory protocol, the corneal implant may
have a single rim about a mid-sectional region of the center optic,
where the rim extends into corneal tissue circumscribing the
central anterior opening after it is released from constraint. In
other alternative embodiments, the corneal implant may have an
anterior rim and a posterior rim, as described generally above,
where the anterior rim radially expands over an anterior corneal
surface circumscribing the central anterior opening and the
posterior rim radially expands over a posterior corneal surface
circumscribing the central anterior opening.
[0044] In further preferred aspects of the method of the present
invention, the center optic will be less compressible than the rim
so that the center optic is not substantially compressed as the
implant is being introduced. In other embodiments, both the rim and
the center optic may be compressible and compressed while the
implant is being introduced.
[0045] In preferred aspects of the methods of the present
invention, the corneal implant will be introduced by advancing the
implant through a tube having a width which compresses at least the
rim of the implant, where the implant is released as it is advanced
out of the tube, in turn releasing the rim to expand and engage the
corneal tissue. The tube is preferably tapered in a distal
direction so that it progressively compresses the rim before the
implant is released from the tube.
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] FIGS. 1A, 1B, 1C, and 1D illustrate prior art corneal
implants.
[0047] FIGS. 2A through 2C illustrates a first embodiment of
apparatus of the present invention.
[0048] FIGS. 3A through 3C illustrate side views of a corneal
implant as it is advanced and constrained by the apparatus of FIGS.
2A-2C.
[0049] FIGS. 4A through 4D illustrate a second embodiment of the
apparatus of the present invention.
[0050] FIGS. 5A through 5D illustrate side views of a corneal
implant as it is advanced and constrained by the apparatus of FIGS.
4A-4D.
[0051] FIGS. 6A through 6C illustrate a third embodiment of the
apparatus of the present invention.
[0052] FIGS. 7A and 7B illustrate use of the apparatus of FIGS.
6A-6C in implanting an implant in a cornea.
[0053] FIGS. 8A through 8F illustrate preferred corneal implants in
accordance with the present invention.
[0054] FIGS. 9A through 9F illustrate a further implantation
protocol in accordance with the present invention.
[0055] FIGS. 10A through 10F illustrate a further implantation
protocol in accordance with the present inventions.
[0056] FIGS. 11A through 11F illustrate a further implantation
protocol in accordance with the present inventions.
[0057] FIGS. 12A and 12B illustrate a tool in accordance with the
principles of the present invention for collapsing and advancing a
corneal implant.
[0058] FIGS. 13A and 13B illustrate an alternative tool in
accordance with the principles of the present invention for
collapsing and advancing a corneal implant.
[0059] FIGS. 14A and 14C are cross-sectional views of the tool of
13A and 13B showing the implant as it is advanced as shown in FIGS.
15A through 15D.
[0060] FIGS. 15A through 15D illustrate use of the tool of FIGS.
13A and 13B for advancing and reducing the cross-section of an
implant in accordance with the principles of the present
invention.
[0061] FIGS. 16 A-F illustrate an alternative tool in accordance
with the principles of the present invention for collapsing and
advancing a corneal implant.
[0062] FIGS. 17 A-C illustrate a corneal scaffold embodiment of the
corneal implant for the treatment of myopia.
[0063] FIGS. 18A-B illustrate a corneal scaffold embodiment of the
corneal implant for the treatment of hyperopia.
[0064] FIGS. 19 A-B illustrate a corneal scaffold embodiment of the
corneal implant for the treatment of hyperopic astigmatism.
[0065] FIGS. 20 A-B illustrate a corneal scaffold embodiment of the
corneal implant which also includes a lens.
[0066] FIGS. 21A-C illustrate an implantation protocol useful for
implanting the corneal implant illustrated in FIG. 8F.
DETAILED DESCRIPTION
[0067] FIG. 1A shows a top view of a cataract surgery lens implant
2. A round optic 5 of the implant 2 has haptics 10 which extend
from the periphery of the optic. The haptics 10 are used to help
the optic center and fixate within the capsular bag. FIG. 1B shows
a side view of a cataract surgery lens implant optic 5. Note that
the thickness t.sub.1 of the optic 5 is typically 1 mm or more and
is substantially greater than the 0.5 to 0.6 mm thickness of the
human cornea. The thickness of the optic 5 makes it inappropriate
for use as a corneal lens implant. FIG. 1C shows a top view of a
corneal implant 15. Note there are no haptics on the corneal
implant. FIG. 1D shows a side view of corneal implant 15. Note that
the thickness t.sub.2 is substantially less than cataract surgery
lens implant 5. The thickness t.sub.2 of corneal implant 15 would
in general be less than the thickness of the human cornea.
[0068] FIG. 2A shows a corneal implant delivery system 18 in
partial section. A hollow member 20 having a distal tip 21 (which
is preferably beveled or chamfered) defines hollow axial passage 25
(e.g., an axial lumen). Axial pusher 30 has a tip 35 that engages a
corneal implant 15 that has been deformed in shape and constrained
to fit inside the hollow axial passage 25 of the hollow member 20,
as shown in FIG. 2B. The cross-section of hollow passage 25 may be
circular, polygonal, or any other shape that is conducive to
constraining the corneal implant 15. The hollow axial passage 25 of
the hollow member 20 may contain ridges, protrusions, indentations,
or recesses (now shown) which help to maintain orientation of the
corneal implant as it advances distally of the hollow member (not
shown). Axial pusher 30 engages one end of the constrained corneal
implant 15 to advance the constrained implant through hollow
passage 25. FIG. 2C shows the constrained corneal implant 15
emerging from a distal end of the hollow passage 25 still in its
deformed and constrained configuration. By placing the tip of the
hollow member 20 through an incision in the cornea, the corneal
implant 15 may be advanced into the corneal pocket (not shown)
through even a very small incision. In preferred aspects, the
corneal implant is able to pass through an entry incision that is
less than one-half the width of the corneal implant. In those
cases, the hollow member will have an external width from 0.5 mm to
5 mm, preferably from 1 mm to 3 mm and an internal width from 0.3
mm to 4.8 mm, preferably from 0.8 mm to 2.8 mm.
[0069] FIG. 3A shows a side view of corneal implant 15 in its
non-deformed, non-constrained shape. FIGS. 3B and 3C shows an end
on view of the corneal implant 15 as it is moved within the hollow
member 20. Note that the corneal implant 15 has been deformed and
constrained into a rolled configuration. The rolled configuration
will preferably have a diameter in the range from 0.3 mm to 4.8 mm,
more preferably from 0.6 mm to 2.6 mm, to fit into the hollow
passage 25 of the hollow member 20.
[0070] FIG. 4A-4D shows a corneal implant delivery system with a
deformation chamber 27 and a deforming member 28. In this
embodiment of the invention, the corneal implant 15 is placed into
the chamber 27 in an unconstrained and non-deformed configuration
and is then deformed into a folded or rolled corneal implant 17
within deformation chamber 27 by deforming member 28. Deforming
member 28 is moved within deformation chamber 27 to deform and fold
corneal implant 15 into a folded or rolled corneal implant 17. FIG.
4C shows axial pusher 30 engaging deformed corneal implant 17 by
implant mover tip 35. FIG. 4D shows deformed and folded corneal
implant 17. Axial pusher 30 engages corneal implant 17 to push the
deformed constrained implant inside hollow passage 25. FIG. 4D
shows that corneal implant 17 has been advanced by axial pusher 30
out of the hollow passage 25 while retaining a constrained shape.
The constrained configuration of corneal implant 17 allows passage
into the corneal pocket (not shown) through a small incision. The
presence of the optional deformation chamber 27 and deforming
member 28 advantageously allows the corneal implant 15 to be easily
deformed into a configuration that will allow it to be placed
through a small corneal incision into a corneal pocket.
[0071] FIGS. 5A-5D show side views of the corneal implant 15 being
deformed into an exemplary deformed and folded or pleated corneal
implant 17.
[0072] FIGS. 6A-6C show a top view of an alternative corneal
implant delivery system 100. In this embodiment, a corneal implant
115 is placed into a deformation area 122. When the "wings" 123 of
the deformation area are closed, a deformation chamber 124 (FIG.
6B) is formed which deforms the corneal implant 115. In this
embodiment, the corneal implant 115 is folded in half. A tip 132 of
an axial pusher 130 engages corneal implant 115. The hollow member
120 is tapered so that hollow passage 126 is narrower at a distal
end 121 that inserts into the corneal pocket. This allows the
corneal implant 115 to be deformed into an even smaller
cross-section as the implant is advanced distally and through the
distal end 121. Advantageously in this embodiment, the implant
mover tip 132 may also be deformable to fit within the narrowing
hollow passage 126.
[0073] FIG. 7A shows a side cross-sectional view of corneal implant
115 being inserted into corneal pocket 140. FIG. 7B shows the final
shape of corneal implant 115 after it has been inserted into
corneal pocket 140 and unfurled or otherwise expanded back to its
unconstrained size within cornea 145.
[0074] FIG. 8A illustrates a cross-sectional view of a corneal
implant prosthesis 50. Corneal implant 50 is meant to replace a
portion of the anterior layers of the cornea. In this embodiment,
there is a central optic 52 that protrudes anteriorly from a rim
54. In preferred aspects, the central optic would protrude
anteriorly from the rim by 1 to 600 microns. More preferably, the
central optic would protrude anteriorly from the rim by 50 to 400
microns. The central optic 52 will replace diseased anterior
corneal tissue that has been removed. The rim 54 is designed to
partly or fully surround the center of the optic and to fit within
the peripheral recesses of a corneal pocket in order to anchor the
corneal implant prosthesis to the cornea. The rim may be a
continuous skirt as illustrated or may be crenellated or otherwise
distributed in sections about the periphery of the center optic.
FIG. 8B shows a top view of corneal implant prosthesis 50 which
shows the central optic 52 and the rim 54. The rim 54 may
optionally contain holes or be porous in nature so as to promote
growth of corneal tissue into and through the implant in order to
promote retention and biocompatibility.
[0075] FIG. 8C shows a cross-sectional view of corneal implant
prosthesis 60 which is meant to replace a full-thickness area of
the cornea. FIG. 8D shows a top view of the same implant prosthesis
60. In this embodiment, there is an anterior portion of central
optic 62 which protrudes anteriorly from a rim 64. The anterior
portion of central optic 62 will replace diseased anterior corneal
tissue that has been removed. In preferred aspects, the central
optic would protrude anteriorly from the rim by 1 to 600 microns.
More preferably, the central optic would protrude anteriorly from
the rim by 50 to 400 microns. In addition, corneal implant
prosthesis 60 has a posterior portion of central optic 66 which
protrudes posteriorly from rim 64. In preferred aspects, the
central optic would protrude posteriorly from the rim by 1 to 900
microns. More preferably, the central optic would protrude
posteriorly from the rim by 50 to 800 microns. The posterior
portion of central optic 63 will replace diseased posterior corneal
tissue that has been removed. The rim 64 will anchor corneal
implant prosthesis 60 within the peripheral recesses of the corneal
pocket and provide a water-tight seal. The rim 64 may optionally
contain holes or be porous in nature so as to promote growth of
corneal tissue into and through the implant in order to promote
retention and biocompatibility. The rim may be formed from any of
the lens materials described above.
[0076] FIG. 8E is an enlarged view of the reversibly deformable
implant prosthesis 60 shown in FIGS. 8C and 8D. The center optic 62
includes a protruding anterior optic 62a and optionally a
protruding posterior optic 62b. The rim 64 surrounds the center
optic 62 and defines said anterior and posterior protruding optics
62a and 62b. Preferably, the implant prosthesis 60 is formed as an
integrated or monolithic structure and is free from
discontinuities, joints, adhesions, connections, and other
fabrication artifacts. In a specific aspect, the sidewall of the
anterior protruding optic 62a is disposed at an angle .alpha.
relative to the plane which intersects the junction of the rim in
the anterior optic between 1.degree. and 144.degree.. The diameter
d.sub.1 of the anterior optic is preferably between 3 mm and 9 mm,
while the diameter d.sub.2 of the posterior optic is also between 3
mm and 9 mm, although the two diameters are not necessarily equal.
The diameter d.sub.3 of the rim will usually be substantially
greater than that of either of the optics, typically being in the
range from 3.5 mm to 12 mm.
[0077] The anterior surface of the center optic will typically be
curved, or more typically, being generally spherical with a radius
in the range between about 3 mm and 4 mm. The anterior surface of
the rim 64 will usually be conical or generally spherical, with
spherical surfaces having a radius generally in the range between
1.5 mm and 9 mm and often being the same as that of the anterior
surface of the anterior optic 62a. The posterior surface of the rim
64 will also generally be conical or spherical, typically being
spherical with a radius in the range from about 1.5 mm to about 9
mm. The posterior face of the posterior optic 62b may be planar or
have a radius in the range from 1.5 to 9 mm. The total thickness t
of the center optic 60 will typically be in the range from 0.1 mm
to 3 mm, with t.sub.1 being in the range from 0.01 mm to 0.15 mm,
t.sub.2 being in the range from 0.05 mm to 1.1 mm, and t.sub.3
being in the range from 0.05 mm to 0.5 mm, and t.sub.4 being in the
range from 0 mm to 2 mm.
[0078] Referring now to FIG. 8F, a further corneal prosthesis 500
constructed in accordance with the principles of the present
invention, comprises a center optic 502 having an anterior rim 504
and a posterior rim 506. At least the anterior rim 504 and
posterior rim 506 are sufficiently flexible so that they may be
collapsed upon introduction into a corneal opening or pocket when
introduced in accordance with the methods of the present invention.
Often, the center optic 502 will also be compressible. The corneal
implant 500 will typically be molded, cast, or machined from a
single material and will be free from discontinuities and artifacts
of fabrication as discussed above with respect to the implant 60.
Corneal implant 500 will typically have a total thickness t, which
is sufficient for implantation in the cornea to span the full
thickness of the cornea, typically being in the range from 0.1 mm
to 3 mm. The thickness t.sub.1 of the anterior rim 504 between the
top of the center optic 502 and the top of the rim is in the range
from 0.001 mm to 0.3 mm, while the bottom of the anterior rim is
recessed by a distance t.sub.2 in the range from 0 mm to 0.3 mm.
The center optic between the anterior rim and the top of the
posterior rim 506 will typically have a length t.sub.3 in the range
from 0.1 mm to 1.2 mm, while the posterior rim 506 will have a
thickness t.sub.4 in the range from 0.01 mm to 2 mm.
[0079] The center optic 502 of the implant 500 will typically be
cylindrical and have a diameter selected to correspond to the
diameter of the opening formed in the cornea, although often the
diameter when the implant is fully hydrated will be slightly
greater than that of the opening. Usually, the diameter d.sub.2 of
the center optic 502 will be in the range from 3 mm to 9 mm. The
widths of the anterior rim 504 and the posterior rim 506 will be
greater than the diameter of the center optic 502 since the rims
will be holding the center optic in place. Typically, the rims 504
and 506 will have circular geometries, although a variety of other
shapes could be used, with the anterior rim having a diameter
d.sub.1 in the range from 3.5 mm to 12 mm and the posterior rim
having a diameter d.sub.3 in the range from 3.5 mm to 12 mm.
Methods for introducing the implant 500 into a corneal opening are
described in more detail below with reference to FIGS. 21A-21C.
[0080] FIGS. 9A-9F show a method of treating an anterior corneal
disease process using the methods and apparatus of the present
invention. In each FIG. 9A-F, a cross-sectional view of the cornea
is seen above and a top view is seen below. In FIG. 9A it is shown
that pocket 40 has been created posterior to anterior diseased
cornea 43. FIG. 9B shows that anterior diseased cornea 43 has been
excised with a circular trephine (not shown) to create an open top
having a peripheral pocket. The edge of the excision is shown as
45. FIG. 9B also shows corneal implant 50 resting in the
deformation area 122. In FIG. 9C the hollow member 120 has been
inserted into pocket 40 through external opening 42 and corneal
implant 50 has been folded in half within deformation chamber 124.
FIG. 9D shows that corneal implant 50 has been further deformed
into a more compact shape by its movement through narrowing hollow
passage 126 and is being extruded into pocket 40. FIG. 9E shows
that corneal implant 50 has been restored to its original shape
within corneal pocket 40. Central optic 52 fills the space left by
excised diseased anterior cornea 43 and restores optical clarity to
the cornea. Hollow member 120 and implant mover 30 have been
withdrawn from corneal pocket 40. FIG. 9F shows the final
appearance of corneal implant 50 fixated within corneal pocket
40.
[0081] FIGS. 10 A-10F show a method of treating a full-thickness
corneal disease (e.g., pseudophakic bullous keratopathy) through
the use of the present invention. In each FIG. 10-AF, a
cross-sectional view of the cornea is seen above and a top view is
seen below. In FIG. 10A it is shown that pocket 40 has been created
within the layers of the diseased cornea 41. The pocket divides the
cornea into diseased anterior cornea 43 and diseased posterior
cornea 44. FIG. 10B shows that anterior diseased cornea 43 has been
excised with a circular trephine (not shown). The edge of the
excision is shown in dashed lines as 45. The opening in the
anterior cornea within the edge of the excision 45 is shown at
reference number 46. FIG. 10B also shows corneal implant 60 resting
in the deformation charter or area 122. In FIG. 10C the hollow
member 120 has been inserted into pocket 40 through external
opening 42 and corneal implant 60 has been folded in half within
deformation chamber 122. FIG. 10D shows that corneal implant 60 has
been further deformed into a more compact shape by its movement
through narrowing hollow passage 126 and is being extruded into
pocket 40. FIG. 10E shows that corneal implant 60 has been restored
to its original shape within corneal pocket 40. Anterior optic 62
fills the space left by the excised diseased anterior cornea 43. In
preferred aspects, after corneal implant 60 has been positioned in
the pocket, the posterior diseased cornea 44 can be excised with
low profile curved corneal scissors or some other cutting tool
(e.g., plasma blade) inserted through external opening 42. FIG. 10F
shows the final appearance of corneal implant prosthesis 60. Note
that the rim 64 anchors corneal implant prosthesis 60 within the
peripheral recesses of the corneal pocket and provides a
water-tight seal. In this embodiment, posterior optic 63 protrudes
through the space left by excised diseased cornea 44. However,
posterior optic 63 is optional and is not necessarily required for
the corneal implant to properly function. It is to be understood
that the relative dimensions, shapes, and angles of the anterior
central optic 62, posterior central optic 63, and rim 64, may each
be modified to promote improved retention as well as optical
qualities all in keeping within the scope of the present
invention.
[0082] In alternative preferred aspects, the corneal implant 60 may
be introduced into the pocket 40 using the injector system as
described previously in FIGS. 9 and 10 through an opening 46. The
hollow member 120 may be inserted through the opening 46, and the
corneal implant 60 then injected into the pocket 40. In yet other
alternative preferred aspects, the corneal implant 60 may be placed
into the pocket 40 by constraining the corneal implant 60 into a
small diameter configuration (e.g., with forceps) and inserting it
through the opening 46 into the pocket 40 without the use of the
hollow member 120 (not shown).
[0083] FIG. 11A-11F show an embodiment of a corneal implant that
can be assembled within the corneal pocket. By assembling
individual smaller pieces of the corneal implant within the corneal
pocket, a relatively large corneal implant can be constructed while
using a relatively small external incision. The top portion of
FIGS. 11A and 11B show a cross-sectional view of a cornea with an
intra-stromal pocket. The bottom portion of FIG. 11A shows a top
down view of a cornea with an intra-stromal pocket. In both FIGS.
11A and 11B, it can be seen that the first half of the rim 70 has
already been inserted inside the pocket. A second half of the rim
74 is being inserted through the small external incision. Note that
because the corneal tissue is partially elastic, the rim may be
made of a relatively rigid material (e.g., polymethylmethacrylate
(PMMA)) and still be inserted through the external opening 42 that
is less than half of the diameter of the assembled corneal implant.
The vertical dashed lines in the top of the figure and the circular
dashed lines in the bottom figure represent an opening 76 left by a
circular disk of anterior stromal tissue that has been excised
(e.g., with a trephine). FIGS. 11C and 11D show that the optic 72
may fit into opening 76. FIGS. 11E and 11F show that the optic 72
has been attached to the two halves of the rim 70 and 74 to
complete assembly of the corneal implant. The individual pieces of
the corneal implant may be attached to each other by interlocking
fittings (not shown), by glue, or any other appropriate mechanical
or chemical method of fixation. In this embodiment of the
invention, the corneal implant is shown as a three piece prosthesis
that replaces part of the cornea. However, it is to be understood
that the invention includes any corneal implant that can be
assembled as two or more pieces within a corneal pocket.
[0084] FIGS. 12A-12B are end views of the back of a deformation
chamber 86 on a hollow member 80 which show how the presence of a
protrusion 82, within the deformation chamber, can help to maintain
the orientation of a corneal implant 90 as it is pushed in an axial
direction. Deformation chamber 86 includes three hinged sections
80a, 80b, and 80c which make up a hollow member which opens in
order to receive corneal implant 90. At the lateral aspects of
deformation area 80 are two protrusions 82, which help to hold the
rim 94 of corneal implant 90 in place. FIG. 12B shows how sections
80a, 80b, and 80c can be closed by putting together the wings 84,
which together form an axial pusher or implant mover, to create
hollow member 80 and deformation chamber 86. Corneal implant 90 is
now securely fixated within the hollow deformation chamber 86 by
the protrusions 82 and can be manipulated. The corneal implant 90
can then be moved axially along hollow member 80 by an axial pusher
or other implant mover (not shown) without inadvertent rotation of
the corneal implant.
[0085] Please note at least some portion of the corneal implant
could be colored in any of the embodiments of the invention to
enhance the aesthetic appearance of the eye or to decrease the
amount of light exposure to the eye (e.g., for treatment of
aniridia).
[0086] Referring now to FIGS. 13A and 13B, a corneal implant
insertion device 200 includes a deformation chamber 202 defined by
two-circular hinged sections 204. The hinged sections 204 are
attached to wings 206 which permit the hinged sections to be closed
in order to capture the corneal implant C, after the implant has
been introduced into the deformation chamber, as shown in FIG.
13B.
[0087] Protrusions 210 having interior arcuate surfaces 212 are
attached to the hinged sections 204 so that the surfaces 212 form
radially inwardly directed ramps, as illustrated in FIG. 14A. Thus,
after the corneal implant C is introduced into the deformation
chamber 202, as illustrated in FIG. 13B, closure of the chamber
using the wings 206 will curl the corneal implant C into a C-shaped
profile, as shown in FIG. 14A. This can be an advantage over the
corneal insertion tool embodiment of FIGS. 12A and 12B where the
edges of the implant are held in a generally open configuration by
the outwardly facing surfaces of protrusions 82.
[0088] In a specific embodiment of the corneal implant insertion
device of the present invention, the corneal implant C comprises a
lamellar corneal stromal endothelial transplant graft of
approximately 9 mm in diameter and 100 .mu.m to 200 .mu.m in
thickness. The deformation chamber 220 has a diameter or width D of
approximately 9 mm in order to receive the corneal implant C such
that its edges are disposed beneath the arcuate surfaces 212 of the
protrusions 210, as illustrated in FIG. 13B.
[0089] Referring now to FIGS. 15A through 15D, a pusher shaft 230
having a forward member 232 may be advanced into the deformation
chamber 202 of the corneal implant insertion device 200. The
forward element 232 will have a profile which is similar to the
shape of the hollow passage so that it can pass over the
protrusions 210 and will typically be compressible so that it can
pass into a tapered region 240 of the insertion device, as shown in
FIG. 15D. Thus, the forward member 232 will first be introduced
into the constant-diameter portion of the deformation chamber 202,
as shown in FIG. 15B, and used to advance the corneal implant C
forwardly. The shaft 30 and forward member 232 will continue to be
advanced so that the corneal implant C is pushed from the distal
tip of the tapered region 240, as shown in FIG. 15C.
[0090] As the corneal implant C is advanced, its edges will be
curved or everted inwardly, as illustrated in FIGS. 14A through
14C. In FIG. 14A, the corneal implant C is shown as it is in FIG.
15A. As it advances forwardly, as shown in FIG. 15B, the corneal
implant C is reduced in diameter with the edges being pushed
radially inwardly, as shown in FIG. 14B. Finally, as the corneal
implant C is released from the proximal tip of the tapered region
240, it has a significantly reduced diameter, as shown in FIG. 14C.
It is particularly desirable that the corneal implant C be reduced
in size to as great an extent as possible, but that the leading
tips of the implant not touch the interior surface, as shown in
FIG. 14C. This reduces the damage or trauma to the delicate corneal
endothelial cells during the implantation protocol.
[0091] In an embodiment illustrated in FIGS. 16A-F, a graft C, such
as a DSEK or DMEK graft, is placed stromal side down onto the
surface of implant mover 300. Implant mover 300 has a flexible
platform 310 which provides a loading area and which consists of a
thin flexible material, such as a plastic. FIG. 16A shows the DSEK
or DMEK graft C on the platform 310 from a top view. FIG. 16 B
shows the DSEK or DMEK graft C on the platform 310 in side profile.
FIG. 16E shows the DSEK or DMEK graft on the platform 310 from a
front view at the start of the loading process. FIG. 16E is shown
at the same time point of the loading process as FIGS. 16A and 16B.
FIG. 16 C is a top view which shows that when platform 310 is
pulled into a hollow member 320, by implant mover member 300, that
the flexible platform 310 will become constrained in size and
shape. Because the DSEK or DMEK graft C is flexible, it will also
become constrained in size and shape inside the flexible platform
310. FIG. 16 D shows a side view at the same time point as 16C.
FIG. 16F shows how DSEK or DMEK graft C is restrained inside
flexible platform 310 into a small diameter configuration. In FIGS.
16A-D and 16 F an internal arcuate protrusion 330 will force the
flexible platform 310 and DSEK graft C to curl in a way that
engages only the stromal surface, thereby protecting the delicate
corneal endothelium located on the inside of the DSEK or DMEK Graft
C. When DSEK or DMEK graft C is to be inserted into the anterior
chamber, hollow member 320 is advanced into the corneal or scleral
incision. The implant mover 300 is then advanced, allowing the
flexible platform 310 and DSEK Graft C so that DSEK Graft C can
unfurl and be released into the anterior chamber. FIGS. 16A-D show
an optional bevel to the end of hollow member 320 which
advantageously allows for easier insertion into the ocular
incision. The optional bevel has an angle between 1.degree. and
89.degree., preferably between 25.degree. and 65.degree..
[0092] FIG. 17A shows a top view of a corneal scaffold implant 400
which is designed for correcting myopia. The scaffold implant 400
is formed from discrete elements 402, providing a peripheral shape,
which is a truncate dome. An interior volume of the dome is empty
and free from structure. FIG. 17B is an oblique view which shows
the shape of the cornea C prior to insertion of the corneal
scaffold implant 400 for myopia into a corneal pocket through
incision I. FIG. 17C shows how the insertion of corneal scaffold
implant for myopia 400 flattens the cornea in the direction of the
arrow 404 and thereby reduces myopia.
[0093] FIG. 18A shows a top view of a corneal scaffold implant 410
which is designed for the purpose of correcting hyperopia. The
implant 410 comprises elements 412 which form a higher truncated
dome than implant 400. FIG. 18B shows how the insertion of this
corneal scaffold implant for hyperopia 410 steepens the cornea in
the direction of the arrow and thereby reduces hyperopia.
[0094] FIG. 19A shows a top view of a corneal scaffold implant 420
which is designed for the purpose of correcting hyperopic
astigmatism. The implant 420 comprises two lateral wings 422 joined
by a central ring 424. FIG. 19B shows how the insertion of this
corneal scaffold implant for hyperopic astigmatism 420 steepens the
central cornea in the direction of the arrow and thereby reduces
hyperopia and also flattens the steep axis of the cornea thereby
reducing astigmatism.
[0095] FIG. 20A shows a top view of a corneal scaffold implant 430
which also contains a lens L shown in hatched lines. FIG. 20B shows
how the insertion of this corneal scaffold implant with a lens 430
corrects refractive error by both changing the shape of the cornea
(flattening in this case) and by introducing an additional lens to
the optical system.
[0096] The scaffold may be formed from the same polymers as
described previously by common techniques, such as molding. Many
other shapes and structures for the corneal scaffold implant can be
devised for the treatment of myopia, hyperopia, astigmatism, higher
order aberrations, and ectactic corneal diseases. Our invention
includes all of the possible three dimensional shapes and
structures where it is not possible for a single plane to pass
through all of the elements of the structure.
[0097] The corneal implant 500 described previously with reference
to FIG. 8F can be reversibly deformed and inserted into a
full-thickness opening O in a cornea C, as illustrated in FIGS.
21A-21C. The opening O will typically be smaller than the corneal
implant 500 and in order to insert the implant into the opening, at
least the posterior rim will be constrained against the sidewall of
the center optic 502, as shown in FIG. 21B. Such constraint may be
achieved with the various insert apparatus, including the tapered
tubes as described hereinbefore. Alternatively, the deformation
could be achieved using conventional forceps or other surgical
tools. The implant 502 is inserted fully so that the anterior rim
504 engages the upper surface of the cornea C in the region
surrounding the opening O with the posterior rim 506 returning to
its unconstrained state and engaging the anterior surface of the
cornea, as illustrated in FIG. 21C. Thus, the rims 504 and 506
capture the anterior and posterior surfaces of the cornea to create
a watertight seal. Optionally, sutures could be placed through the
edges or peripheries of the rims 504 and 506 or further optionally,
through holes (not shown), to secure the implant. Alternatively,
the implant 500 could be introduced through a separate incision
into the cornea with the anterior plate being constrained as the
implant is pushed upwardly or in the anterior direction, with the
anterior rim 504 emerging from the top surface and resuming an
unconstrained geometry to capture the cornea.
[0098] While the above is a complete description of the preferred
embodiments of the invention, various alternatives, modifications,
and equivalents may be used. Therefore, the above description
should not be taken as limiting the scope of the invention which is
defined by the appended claims.
* * * * *