U.S. patent application number 10/217836 was filed with the patent office on 2003-01-02 for intraocular lenses.
Invention is credited to Hoffmann, Laurent, Ross, Mark Wesley, Stenger, Donald Carrol.
Application Number | 20030004570 10/217836 |
Document ID | / |
Family ID | 23311673 |
Filed Date | 2003-01-02 |
United States Patent
Application |
20030004570 |
Kind Code |
A1 |
Hoffmann, Laurent ; et
al. |
January 2, 2003 |
Intraocular lenses
Abstract
An intraocular lens including an optic portion having an outer
peripheral edge and two, three or four balanced looped haptic
elements for use to achieve refractive correction. Each looped
haptic is formed to have greater resistance to bending in a plane
generally parallel to an eye's optical axis than in a plane
generally perpendicular to the eye's optical axis. The intraocular
lens is designed with specific flexibility characteristics so as to
exhibit less than approximately 1.0 mm axial displacement of the
optic portion along the eye's optical axis under a compression
force suitable to effect a 1.0 mm in diameter compression of the
intraocular lens.
Inventors: |
Hoffmann, Laurent; (Foothill
Ranch, CA) ; Ross, Mark Wesley; (Costa Mesa, CA)
; Stenger, Donald Carrol; (Anaheim Hills, CA) |
Correspondence
Address: |
BAUSCH & LOMB INCORPORATED
ONE BAUSCH & LOMB PLACE
ROCHESTER
NY
14604-2701
US
|
Family ID: |
23311673 |
Appl. No.: |
10/217836 |
Filed: |
August 13, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10217836 |
Aug 13, 2002 |
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09335413 |
Jun 17, 1999 |
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6461384 |
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Current U.S.
Class: |
623/6.49 ;
623/6.51 |
Current CPC
Class: |
A61F 2/1616 20130101;
A61F 2250/0004 20130101; A61F 2250/0073 20130101; A61F 2002/1681
20130101 |
Class at
Publication: |
623/6.49 ;
623/6.51 |
International
Class: |
A61F 002/16 |
Claims
We claim:
1. An intraocular lens to be implanted within an eye generally
perpendicular to the eye's optical axis comprising: an outer
peripheral edge defining an optic portion, and two, three or four
looped haptic elements permanently connected to the outer
peripheral edge, whereby a compressive force sufficient to effect a
1.0 mm in diameter compression of said lens results in less than
approximately 1.0 mm of axial displacement of said optic portion
along the eye's optical axis.
2. An intraocular lens to be implanted within an eye generally
perpendicular to the eye's optical axis comprising: an outer
peripheral edge defining an optic portion, and two, three or four
looped haptic elements permanently connected to the outer
peripheral edge, whereby a compressive force sufficient to effect a
1.0 mm in diameter compression of said lens results in less than
approximately 0.5 mm of axial displacement of said optic portion
along the eye's optical axis.
3. An intraocular lens to be implanted within an eye generally
perpendicular to the eye's optical axis comprising: an outer
peripheral edge defining an optic portion, and two, three or four
looped haptic elements permanently connected to the outer
peripheral edge, whereby a compressive force sufficient to effect a
1.0 mm in diameter compression of said lens results in less than
approximately 0.3 mm of axial displacement of said optic portion
along the eye's optical axis.
4. The intraocular lens of claim 1, 2 or 3 wherein the looped
haptic elements and the optic portion are both formed of a foldable
or compressible material.
5. The intraocular lens of claim 1, 2 or 3 wherein said lens is
formed from a material selected from the group consisting of
silicone polymers, hydrocarbon and fluorocarbon polymers,
hydrogels, soft acrylic polymers, polyester, polyamides,
polyurethane, silicone polymers with hydrophilic monomer units,
fluorine-containing polysiloxane elastomers and combinations
thereof.
6. The intraocular lens of claim 1, 2 or 3 wherein said lens is
formed from a hydrogel material.
7. The intraocular lens of claim 1, 2 or 3 wherein said lens is
formed from a hydrogel material which is 18 percent by weight
water.
8. The intraocular lens of claim 1, 2 or 3 wherein said lens is
formed from poly(HEMA-co-HOHEXMA).
9. The intraocular lens of claim 1, 2 or 3 wherein said lens is
formed from a material having a refractive index above 1.33.
10. The intraocular lens of claim 1, 2 or 3 wherein said lens is
formed from an acrylic material.
11. The intraocular lens of claim 1, 2 or 3 wherein said lens is
formed from a silicone material.
12. The intraocular lens of claim 1, 2 or 3 wherein said looped
haptic elements are dimensioned to be equal to or less in a plane
generally perpendicular to the eye's optical axis than in a plane
generally parallel to the eye's optical axis.
13. The intraocular lens of claim 1, 2 or 3 wherein a glare
reduction zone is formed adjacent to the outer peripheral edge of
the optic portion.
14. The intraocular lens of claim 1, 2 or 3 wherein one or more of
said looped haptic elements includes a stiffening element having a
greater resistance to bending in a plane generally parallel to an
eye's optical axis than in a plane generally perpendicular to the
eye's optical axis.
15. The intraocular lens of claim 1, 2 or 3 wherein the haptic
element includes a stiffening element formed from a material
selected from the group consisting of polyimide, polyolefin,
high-density polyester, nylon and metal.
16. A method of manufacturing the intraocular lens of claim 1, 2 or
3 comprising: forming a disk of a suitable material, and machining
said lens from said disk.
17. A method of manufacturing the intraocular lens of claim 1, 2 or
3 comprising: molding said lens of a suitable material.
18. A method of using the intraocular lens of claim 1, 2 or 3
comprising: creating an incision in a cornea of an eye, and
inserting said intraocular lens in an anterior chamber of said
eye.
19. A method of using the intraocular lens of claim 1, 2 or 3
comprising: creating an incision in a cornea of an eye, and
inserting said intraocular lens in a posterior chamber of said
eye.
20. A method of using the intraocular lens of claim 1, 2 or 3
comprising: creating an incision in a cornea and lens capsule of an
eye, removing a natural lens of said eye, and inserting said
intraocular lens in said lens capsule of said eye.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to intraocular lenses (IOLs)
and a method for making and using the same. More particularly, the
present invention relates to IOLs designed primarily for refractive
correction in phakic eyes where the eye's natural lens remains
intact. IOLs made in accordance with the present invention may also
be used in aphakic eyes where a diseased natural lens is surgically
removed, such as in the case of cataracts.
BACKGROUND OF THE INVENTION
[0002] Visual acuity deficiencies such as myopia (nearsightedness),
hyperopia (farsightedness) and presbyopia (age-related
farsightedness) are typically corrected with use of refractive
lenses such as spectacles or contact lenses. Although these types
of lenses are effective in correcting a wearer's eyesight, many
wearers consider the lenses inconvenient. The lenses must be
located, worn at certain times, removed periodically and may be
lost or misplaced. The lenses may also be dangerous or cumbersome
if the wearer participates in athletic activities or suffers an
impact in an area near the eyes.
[0003] The use of surgically implanted IOLs as a permanent form of
refractive correction in phakic eyes has been gaining in
popularity. IOL implants have been used for many years in aphakic
eyes as replacements for diseased natural crystalline lenses that
have been surgically removed from the eyes. Many different IOL
designs have been developed over past years and proven successful
for use in aphakic eyes. Successful IOL designs to date primarily
include an optic portion with supports therefor, called haptics,
connected to and surrounding at least part of the optic portion.
The haptic portions of an IOL are designed to support the optic
portion of the IOL in the lens capsule, anterior chamber or
posterior chamber of an eye.
[0004] Commercially successful IOLs have been made from a variety
of biocompatible materials, ranging from more rigid materials such
as polymethylmethacrylate (PMMA) to softer, more flexible materials
capable of being folded or compressed such as silicones, certain
acrylics, and hydrogels. Haptic portions of the IOLs have been
formed separately from the optic portion and later connected
thereto through processes such as heat, physical staking and/or
chemical bonding. Haptics have also been formed as an integral part
of the optic portion in what is commonly referred to as
"single-piece" IOLs.
[0005] Softer, more flexible IOLs have gained in popularity in more
recent years due to their ability to be compressed, folded, rolled
or otherwise deformed. Such softer IOLs may be deformed prior to
insertion thereof through an incision in the cornea of an eye.
Following insertion of the IOL in an eye, the IOL returns to its
original pre-deformed shape due to the memory characteristics of
the soft material. Softer, more flexible IOLs as just described may
be implanted into an eye through an incision that is much smaller,
i.e., 2.8 to 3.2 mm, than that necessary for more rigid IOLs, i.e.,
4.8 to 6.0 mm. A larger incision is necessary for more rigid IOLs
because the lens must be inserted through an incision in the cornea
slightly larger than the diameter of the inflexible IOL optic
portion. Accordingly, more rigid IOLs have become less popular in
the market since larger incisions have been found to be associated
with an increased incidence of postoperative complications, such as
induced astigmatism.
[0006] After IOL implantation, both softer and more rigid IOLs are
subject to compressive forces exerted on the outer edges thereof,
which typically occur when an individual squints or rubs the eye.
These compressive forces may result in decentration of the IOL and
distortion of the visual image. Compressive forces exerted on an
IOL also tend to cause axial displacement of the IOL along the
optical axis of an eye. Movement of an IOL along the optical axis
of an eye has the potential in anterior chamber applications to
cause the IOL to contact and damage the delicate corneal
endothelial cell layer of the eye. Such potential damage to the
delicate corneal endothelial cell layer is due in part to the
design of anterior chamber IOLs that are vaulted to prevent
interference or damage to the iris of an eye. Also, IOLs of current
designs, whether vaulted or unvaulted, or formed of either softer
or more rigid materials, tend to deflect along the optical axis of
an eye when the haptics are compressed. IOL manufacturers provide a
wide range of IOL sizes to more precisely fit IOLs to each
particular patient's eye size. Providing a wide range of IOL sizes
is an attempt to minimize the potential for axial displacement of
the IOL along the optical axis of an eye.
[0007] Because of the noted shortcomings of current IOL designs,
there is a need for IOLs designed to minimize axial displacement of
the IOL optic portion along the optical axis of the eye when
compressive forces are exerted against the outer edges thereof. By
lessening an IOLs movement along the optical axis of an eye, more
certain refractive correction may be achieved and the risk of
corneal endothelial cell layer damage may be reduced.
SUMMARY OF THE INVENTION
[0008] An intraocular lens (IOL) made in accordance with the
present invention has an optic portion with an outer peripheral
edge and two, three or four looped haptic elements for supporting
the optic portion in a patient's eye. A lens having two looped
haptic elements is balanced by having a looped haptic element
formed or attached on two opposed edges of the optic portion. A
lens having three looped haptic elements is balanced by having a
set of two looped haptic elements formed or attached on one edge of
the optic and the third looped haptic element formed or attached on
an opposite edge of the optic. A lens having four looped haptic
elements is balanced by having a set of two looped haptic elements
formed or attached on one edge of the optic and a set of two looped
haptic elements formed or attached on an opposite edge of the
optic. Each looped haptic element has an inner edge portion, an
outer edge portion and generally two attachment portions that
permanently connect the looped haptic elements to the outer
peripheral edge of the optic portion. In the case of lenses having
three or four looped-haptic elements, a set of two looped haptic
elements may have three attachment portions rather than four. In
such a case, one of the three attachment portions is common to each
of the two looped haptic elements in the set. Each looped haptic
element also includes a flexible central portion located adjacent
to each of the two attachment portions and a contact plate located
between the two flexible central portions. The contact plate is
designed to engage an inner surface of a patient's eye. The two
flexible central portions that extend between the contact plate and
the attachment portions allow the lens to adjust to pressures
exerted on the lens within the eye. Additionally, within these
flexible central portions, each looped haptic element is designed
to have greater resistance to bending in a plane generally parallel
to the optical axis of an eye than in a plane generally
perpendicular to the optical axis of an eye. By providing looped
haptic elements with this type of flexibility characteristic, the
present IOL fits eyes of varying sizes. The flexibility
characteristic of the subject looped haptic elements relative to
the optic portion also eliminates unacceptable axial displacement
of the optic portion along the optical axis when compressive forces
are exerted against the looped haptic elements of the IOL.
[0009] Accordingly, it is an object of the present invention to
provide intraocular lenses for use in phakic eyes.
[0010] Another object of the present invention is to provide
intraocular lenses for use in phakic eyes, which fit a variety of
eye sizes.
[0011] Another object of the present invention is to provide
intraocular lenses for use in phakic eyes, which minimize axial
displacement of the optic portions of-the lenses along the optical
axis of the eyes.
[0012] Another object of the present invention is to provide
intraocular lenses for use in phakic eyes, which minimize damage to
tissues in the interior of the eyes.
[0013] Still another object of the present invention is to provide
intraocular lenses, which are resistant to decentration within the
eyes.
[0014] These and other objectives and advantages of the present
invention, some of which are specifically described and others that
are not, will become apparent from the detailed description,
drawings and claims that follow, wherein like features are
designated by like numerals.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a schematic representation of the interior of a
human eye including a natural lens and a refractive IOL implanted
in the anterior chamber of the eye;
[0016] FIG. 2 is a plan view of an IOL with three looped haptics
made in accordance with the present invention;
[0017] FIG. 3 is a side view of the IOL of FIG. 2;
[0018] FIG. 4 is a cross sectional view of the IOL of FIG. 2 taken
along line 4-4;
[0019] FIG. 5 is a perspective view of the IOL of FIG. 2;
[0020] FIG. 6 is a side view of the looped haptic element of FIG. 3
with sharper edges;
[0021] FIG. 7 is a side view of the looped haptic element of FIG. 3
with rounded edges;
[0022] FIG. 8 is a side cross sectional view of the looped haptic
element of FIG. 6 with a stiffening element;
[0023] FIG. 9 is a plan view of an IOL with four looped haptics
made in accordance with the present invention;
[0024] FIG. 10 is a side view of the IOL of FIG. 9;
[0025] FIG. 11 is a plan view of an IOL with four looped haptics
made in accordance with the present invention;
[0026] FIG. 12 is a side view of the IOL of FIG. 11;
[0027] FIG. 13 is a plan view of an IOL with two looped haptics
made in accordance with the present invention; and
[0028] FIG. 14 is a side view of the IOL of FIG. 13.
DETAILED DESCRIPTION OF THE INVENTION
[0029] FIG. 1 illustrates a simplified diagram of an eye 10 showing
landmark structures relevant to the implantation of an intraocular
lens of the present invention. Eye 10 includes an optically dear
cornea 12 and an iris 14. A natural crystalline lens 16 and a
retina 18 are located behind the iris 14 of eye 10. Eye 10 also
includes anterior chamber 6 located in front of iris 14 and a
posterior chamber 8 located between iris 14 and natural lens 16.
IOLs of the present invention are preferably implanted in anterior
chamber 6 to correct refractive errors while healthy natural lens
16 remains in place (phakic application). IOLs of the present
invention may also be implanted in posterior chamber 8 or lens
capsule 7 for use in aphakic eyes. When used in aphakic eyes, IOLs
serve as replacements for surgically removed diseased natural
lenses 16, such as for example following cataract surgeries. Eye 10
also includes an optical axis OA-OA that is an imaginary line that
passes through the optical center 20 of anterior surface 22 and
posterior surface 24 of lens 16. Optical axis OA-OA in the human
eye 10 is generally perpendicular to a portion of cornea 12,
natural lens 16 and retina 18.
[0030] The IOL of the present invention, as illustrated in FIGS. 2
through 14 but best illustrated in FIGS. 2, 9, 11 and 13, is
identified generally by reference numeral 26. IOL 26 has an optic
portion 28 with an outer peripheral edge 30. IOL 26 is designed for
implantation preferably in anterior chamber 6 of a patient's eye 10
and is preferably vaulted. For anterior chamber 6 applications, a
vault of approximately 1.0 to 2.0 mm but preferably 1.6 to 1.7 mm
measuring from the plane of outer peripheral edge 30 of optic
portion 28 to the plane of contact plates 38, described in detail
below, is generally suitable. However as mentioned above, IOL 26
may likewise be implanted in posterior chamber 8 or in the case of
an aphakic eye, in lens capsule 7 in which case IOL 26 need not be
vaulted. Preferably integrally formed on peripheral edge 30 of
optic portion 28 are two, three or four looped haptic elements 32,
each having an inner edge portion 34 and an outer edge portion 36.
Looped haptic elements 32 are preferably integrally formed with and
permanently connected to outer peripheral edge 30 of optic portion
28 by attachment portions 33. Alternatively however, haptic
elements 32 may be attached to optic portion 28 by staking,
chemical polymerization or other methods known to those skilled in
the art. Each looped haptic element 32 also includes a broadened
contact plate 38 designed to preferably engage inner surfaces 40 in
anterior chamber 6. However, contact plate 38 is also suitable to
engage inner surfaces 42 in posterior chamber 8 or inner surfaces
43 in lens capsule 7 of eye 10.
[0031] In accordance with the present invention, looped haptic
elements 32 are designed so that when IOL 26 is implanted in a
patient's eye 10 and held in place through compressive forces
exerted by inner surfaces 40, 42 or 43 on contact plates 38 of
looped haptic elements 32, looped haptic elements 32 flex so that
contact plates 38 do not slide along surfaces 40, 42 or 43 in the
eye 10. Accordingly, looped haptic elements 32 are designed to flex
in a plane generally parallel to that of optic portion 28 of IOL 26
and generally perpendicular to that of optical axis OA-OA of eye
10. By designing this type of flexibility characteristic into
looped haptic elements 32, IOL 26 may be manufactured in one or a
few standard sizes and be a suitable fit for most sizes of
patients' eyes 10. The flexibility characteristic of looped haptic
elements 32 also minimizes axial displacement of optic portion 28
in a direction along optical axis OA-OA of eye 10. Compressive
forces of differing magnitudes within the range of approximately
0.1 to 5 mN exerted against contact plates 38 of looped haptic
elements 32 to effect approximately an overall 1.0 mm in diameter
compression of IOL 26, such as that caused by differing eye sizes,
results in less than approximately 1.0 mm, but more preferably less
than approximately 0.5 mm and most preferably less than
approximately 0.3 mm axial displacement of optic portion 28 along
optical axis OA-OA in an eye 10. Under like compressive forces,
IOLs known in the art result in greater than 1.0 mm axial
displacement of the optic portion along the optical axis in the
eye, which may damage delicate tissues therein. The unique design
of IOL 26 achieves significantly minimized axial displacement of
optic portion 28. The IOL 26 of the present invention with its
minimized axial displacement of optic portion 28 protects the
corneal endothelium cell layer 4 of eye 10 from damage when a wide
range of compressive forces, potentially even greater than those
described above, are applied to eye 10.
[0032] The flexibility characteristic of looped haptic elements 32
of IOL 26 as described above is achieved through the unique design
thereof. As best illustrated in FIGS. 2, 9, 11 and 13, and most
particularly in FIG. 11, IOL 26 has looped haptic elements 32
formed with angled, arched or bowed flexible central portions 44
adjacent to attachment portions 33 permanently connected to outer
peripheral edge 30 of optic portion 28. The angled, arched or bowed
flexible central portions 44 are essential in imparting the
necessary flexibility to the IOLs of the present invention. As best
illustrated in FIGS. 3, 10, 12 and 14, flexible central portions 44
have a dimension in plane 46-46, generally parallel to optical axis
OA-OA, equal to or greater than the same in plane 48-48 generally
perpendicular to optical axis OA-OA as depicted in FIG. 2.
Transition portions 50, of significantly decreasing size in
dimension in plane 46-46 extend from flexible central portions 44
to broadened contact plate 38. Contact plate 38 is relatively flat
with either rounded edges 52 as depicted in FIG. 7 to provide a
smoother fit with inner surfaces 40, 42 or 43, or more defined,
sharper edges 54 as depicted in FIG. 6 to provide a barrier to
prevent cellular migration and growth upon implantation in lens
capsule 7. The relatively thin or flat contact plate 38 also
minimizes iris 14 contact by virtue of its overall angled, arched
or bowed cross section as illustrated in FIGS. 6 through 8.
[0033] The subject IOL 26 is preferably manufactured to have an
optic portion 28 approximately 4.5 to 9.0 mm, but preferably
approximately 5.0 to 6.0 mm and most preferably 5.5 mm in diameter
and approximately 0.15 mm to 1.0 mm, but preferably approximately
0.6 to 0.8 mm and most preferably 0.7 mm in thickness at peripheral
edge 30. Looped haptic elements 32 extend from the optic portion 28
of IOL 26 in a generally rounded or oval configuration and will
increase or decrease in overall length depending upon the size of
lens desired and the diameter of optic portion 28. As the diameter
of optic portion 28 increases, the overall length of looped haptic
elements 32 may be decreased. Likewise, as the diameter of optic
portion 28 decreases, the overall length of looped haptic elements
32 may be increased. However, as customary, the overall length of
the looped haptic elements 32 are varied to achieve desired IOL 26
sizes rather than varying the sizes of optic portions 28. In
general, looped haptic elements 32 are formed to be approximately
2.6 to 6.0 mm, but preferably approximately 3.4 to 5.0 mm and most
preferably approximately 4.2 mm in length measuring from a point of
equal distance between common attachment portions 33 on peripheral
edge 30, to the center of contact plate 38. Looped haptic elements
32 are preferred to have a generally rounded or oval configuration
as illustrated in FIGS. 2, 9, 11 and 13 to allow radial deflection
under compressive forces. For purposes of the present invention,
the generally rounded or oval shape of looped haptic element 32,
i.e., the beam curve shape, relative to the width to thickness
ratio, i.e., the aspect ratio, of looped haptic element 32 as
described herein is critical to achieve suitable function. Flexible
central portion 44 of looped haptic element 32 is approximately 0.5
to 2.5 mm, but preferably approximately 1.0 to 2.0 mm and most
preferably 1.6 mm in length; approximately 0.2 to 1.0 mm, but
preferably approximately 0.3 to 0.7 mm and most preferably
approximately 0.46 mm in thickness in plane 46-46 and approximately
0.2 to 0.7 mm, but preferably approximately 0.3 to 0.6 and most
preferably approximately 0.43 mm in width in plane 48-48.
Transition portions 50 are approximately 0.4 to 1.1 mm, but
preferably approximately 0.5 to 1.0 mm and most preferably
approximately 0.8 mm in length. Contact plate 38 is approximately
0.8 to 2.5 mm, but preferably approximately 1.0 to 2.2 mm and most
preferably approximately 1.8 mm in length, approximately 0.05 to
0.5 mm, but preferably approximately 0.1 to 0.4 mm and most
preferably approximately 0.3 mm in thickness and approximately 0.6
to 1.5 mm, but preferably approximately 0.8 to 1.2 mm and most
preferably approximately 1.0 mm in width.
[0034] As provided through the dimensions of IOL 26 above, looped
haptic elements 32 gradually change from being relatively thin in
plane 46-46 at outer edge portion 36 to being relatively thick at
attachment portions 33 and optic portion 28, with flexible central
portions 44 preferably exhibiting a thicker dimension in plane
46-46 than that of the width in plane 48-48. Looped haptic elements
32 of the subject design tend to deflect into closer proximity with
outer peripheral edge 30 when a compression force is exerted
against contact plates 38 with minimal axial displacement along
optical axis OA-OA. When IOL 26 is used as a refractive lens, a
stable, reliable refractive correction is provided.
[0035] The desired flexibility characteristic of looped haptic
elements 32 of IOL 26 may likewise be achieved or enhanced by
incorporating a stiffening element 60, in the shape of a ribbon, in
one or more looped haptic elements 32, as illustrated in FIG. 8.
Stiffening element 60 may be positioned in looped haptic element 32
so that flat face 62 is oriented parallel to the dimension 46-46.
Stiffening element 60 functions in a manner similar to that of an
I-beam in construction to prevent axial displacement along optical
axis OA-OA when compressive force is applied to contact plates
38.
[0036] Stiffening element 60 is formed of a less flexible material
than that of IOL 26. Suitable materials for stiffening element 60
include but are not limited to polyimides, polyolefins,
high-density polyethylenes, polyesters, nylons, metals or any
biocompatible material with suitable stiffening characteristics.
Stiffening element 60 may be used in conjunction with looped haptic
elements 32 described above or in cases where a thinner haptic
design is desired while still achieving the desired flexibility
characteristics.
[0037] Suitable materials for the production of the subject IOL 26
include but are not limited to foldable or compressible materials,
such as silicone polymers, hydrocarbon and fluorocarbon polymers,
hydrogels, soft acrylic polymers, polyesters, polyamides,
polyurethane, silicone polymers with hydrophilic monomer units,
fluorine-containing polysiloxane elastomers and combinations
thereof. The preferred material for the production of IOL 26 of the
present invention is a hydrogel made from 2-hydroxyethyl
methacrylate (HEMA) and 6-hydroxyhexyl methacrylate (HOHEXMA),
i.e., poly(HEMA-co-HOHEXMA). Poly(HEMA-co-HOHEXMA) is the preferred
material for the manufacture of IOL 26 due to its equilibrium water
content of approximately 18 percent by weight, and high refractive
index of approximately 1.474, which is greater than that of the
aqueous humor of the eye, i.e., 1.33. A high refractive index is a
desirable feature in the production of IOLs to impart high optical
power with a minimum of optic thickness. By using a material with a
high refractive index, visual acuity deficiencies may be corrected
using a thinner IOL. A thin IOL, such as that of IOL 26, is
particularly desirable in phakic applications to minimize
potentially harmful contact between IOL 26 and iris 14 and corneal
endothelium 4. Poly(HEMA-co-HOHEXMA) is also a desirable material
in the production of IOLs 26 due to its mechanical strength, which
is suitable to withstand considerable physical manipulation.
Poly(HEMA-co-HOHEXMA) also has desirable memory properties suitable
for IOL use. IOLs manufactured from a material possessing good
memory properties such as those of poly(HEMA-co-HOHEXMA) unfold in
a more controlled manner in an eye, rather than explosively, to its
predetermined shape. The unique design of the subject IOL 26 with
looped haptic elements 32 manufactured from a material having good
memory properties also provides improved control of haptic
unfolding upon insertion thereof in eye 10. Explosive unfolding of
IOLs is undesirable due to potential damage to delicate tissues
within the eye. Poly(HEMA-co-HOHEXMA) also has dimensional
stability in the eye, which is desirable.
[0038] Although the teachings of the present invention are
preferably applied to soft or foldable IOLs formed of a foldable or
compressible material, the same may also be applied to harder, less
flexible lenses formed of a relatively rigid material such as
polymethylmethacrylate (PMMA) having flexible haptics formed either
of the same or a different material.
[0039] Optic portion 28 of IOL 26 can be a positive powered lens
from 0 to approximately +40 diopters or a negative powered lens
from 0 to approximately -30 diopters. Optic portion 28 may be
biconvex, plano-convex, plano-concave, biconcave or concave-convex
(meniscus), depending upon the power required to achieve the
appropriate central and peripheral thickness for efficient
handling.
[0040] Optic portion 28 of the subject IOL 26 may optionally be
formed with a glare reduction zone 56 of approximately 0.25 to 2.00
mm but more preferably approximately 0.3 to 0.6 mm and most
preferably 0.5 mm in width adjacent outer peripheral edge 30 for
reducing glare when outer peripheral edge 30 of IOL 26 is struck by
light entering eye10 during high light or at other times when pupil
58 is dilated. Glare reduction zone 56 is typically fabricated of
the same material as optic portion 28, but may be opaque, colored
or patterned in a conventional manner to block or diffuse light in
plane with optical axis OA-OA.
[0041] Subject IOL 26 may be molded or preferably manufactured by
first producing discs from a material of choice as described in
U.S. Pat. Nos. 5,217,491 and 5,326,506 each incorporated herein in
its entirety by reference. If discs are produced, IOL 26 is then be
machined from the material discs in a conventional manner. Once
machined or molded, IOL 26 may be polished, cleaned, sterilized and
packaged by a conventional method known to those skilled in the
art.
[0042] Subject IOL 26 is used in eye 10 by creating an incision in
cornea 12, inserting IOL 26 in either anterior chamber 6 or
posterior chamber 8 and closing the incision. Alternatively, IOL 26
may be used in eye 10 by creating an incision in cornea 12 and
capsule 7, removing natural lens 16, inserting IOL 26 in capsule 7
and closing the incision.
[0043] IOL 26 of the present invention provides for a refractive
lens suitable for use in lens capsule 7 or posterior chamber 8, but
most preferably for use in anterior chamber 6 of eye 10. IOL 26 has
looped haptic elements 32 with flexibility characteristics that
minimize axial displacement along optical axis OA-OA of eye 10
thereby preventing decentration of IOL 26, distortion of vision and
damage to corneal endothelium 4. IOL 26, having the flexibility
characteristics described herein, is also commercially desirable
because one or a few lens sizes suitably fit eyes 10 of most sizes.
By providing a lens suitable for use as a "universal" lens, such as
that of the present invention, clinical risks to patients due to
improperly sized lenses are minimized. Such clinical risks
minimized include pupil ovalization, corneal endothelium damage and
poor fixation. Likewise, manufacturers' need to produce IOLs of
many sizes to fit eyes of many sizes is eliminated, thus reducing
production and inventory costs associated therewith.
Ophthalmologists also benefit from the subject IOL 26 in that time
is saved by eliminating the need to determine each patient's eye
size and costs associated with maintaining large inventories of
varying sized lenses.
[0044] While there is shown and described herein certain specific
embodiments of the present invention, it will be manifest to those
skilled in the art that various modifications may be made without
departing from the spirit and scope of the underlying inventive
concept and that the same is not limited to the particular forms
herein shown and described except insofar as indicated by the scope
of the appended claims.
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