Note: Descriptions are shown in the official language in which they were submitted.
CA 02767318 2013-08-16
ACCOMMODATING INTRAOCULAR LENS SYSTEM WITH SEPARATION
MEMBER
Background of the Invention
Field of the Invention
This invention relates to intraocular lenses and, more particularly, to
intraocular
lenses that alter the refractive power of the eye in response to changes in
the tension of
the ciliary muscle of the eye.
Description of the Related Art
The vast majority of cataract operations involve the implantation of an
artificial
lens following cataract removal. Typically these lenses have a fixed focal
length or, in
the case of bifocal or multifocal lenses, have several different fixed focal
lengths. Such
fixed focal-length lenses lack the ability of the natural lens to dynamically
change the
refractive power of the eye. The various embodiments of the intraocular lens
disclosed
herein provide an accommodating lens system which alters the refractive power
of the
eye in response to changes in tension of the ciliary muscle, thereby allowing
the lens
system to bring into focus on the retina images of objects that are both near
and far from
the eye.
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Summary of the Invention
In accordance with one aspect of the invention there is provided an
accommodating intraocular lens. The lens includes an anterior portion having
an
anterior viewing element including an optic having refractive power, the optic
having a
refractive zone configured to refract light that is received by a retina of a
patient. The
lens also includes a posterior portion having a posterior viewing element, the
viewing
elements positioned to move relative to each other along an optical axis of
the lens in
response to action of the ciliary muscle of the eye, the anterior and
posterior portions
meeting at first and second apices of the lens, the apices located on a
transverse axis of
the lens. At least one of the anterior and posterior portions have at least
one separation
member with a contact surface, the at least one separation member configured
to
prevent contact between the anterior viewing element and the posterior viewing
element
by inhibiting relative movement of the anterior and posterior portions toward
each other
beyond a minimum separation distance. The at least one separation member is
located
significantly closer to the anterior viewing element or the posterior viewing
element
than to either of the apices. The at least one separation member defines a
cross-
sectional area in a plane orthogonal to the optical axis and the contact
surface contacts
an opposing surface of the intraocular lens over a contact area when the
portions are at
the minimum separation distance, the contact area being smaller than the cross-
sectional
area. The entirety of the separation member is located outside a projection of
a
periphery of the refractive zone along a direction parallel to the optical
axis and the
separation member is out of contact with one of the anterior portion and the
posterior
portion when the viewing elements are separated by a distance greater than the
minimum separation distance.
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In accordance with another aspect of the invention there is provided an
accommodating intraocular lens for implantation in an eye of a patient. The
lens
includes an anterior portion having an anterior viewing element including an
optic
having refractive power. The lens also includes a posterior portion having a
posterior
viewing element, the viewing elements positioned to move relative to each
other along
an optical axis of the lens in response to action of the ciliary muscle of the
eye, the
anterior and posterior portions meeting at first and second apices of the
lens, the apices
located on a transverse axis of the lens. At least one of the anterior and
posterior
portions has at least one separation member with a contact surface on a distal
end of the
separation member, the at least one separation member configured to prevent
contact
between the anterior viewing element and the posterior viewing element by
inhibiting
relative movement of the anterior and posterior portions toward each other
beyond a
minimum separation distance. The at least one separation member is located
significantly closer to the anterior viewing element or the posterior viewing
element
than to either of the apices. The at least one separation member defines a
first cross-
sectional area near the contact surface and in a plane orthogonal to the
optical axis. The
at least one separation member defines a second cross-sectional area proximal
of the
distal end of the separation member and in a plane orthogonal to the optical
axis, the
second cross-sectional area being larger than the first cross-sectional area.
The anterior
optic has a refractive region that is configured to refract light that forms
an image on the
retina of the eye and the separation member is positioned outside a projection
of a
periphery of the refractive region along a direction parallel to the optical
axis and the
separation member is out of contact with one of the anterior portion and the
posterior
portion when the viewing elements are separated by a distance greater than the
minimum separation distance.
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In accordance with another aspect of the invention there is provided an
accommodating intraocular lens implantable in an eye of a patient. The lens
includes an
anterior portion having an anterior viewing element including an optic having
refractive
power, the optic having a refractive zone configured to refract light that is
received by a
retina of a patient. The lens also includes a posterior portion having a
posterior viewing
element, the viewing elements interconnected by a biasing element and moveable
relative to each other along an optical axis of the lens between an
accommodated state
and an unaccommodated state in response to action of the ciliary muscle of the
eye. At
least one of the anterior and posterior portions have at least one separation
member with
a contact surface, the at least one separation member configured to prevent
contact
between the anterior viewing element and the posterior viewing element by
inhibiting
relative movement of the anterior and posterior portions toward each other
beyond a
minimum separation distance. The at least one separation member defines a
first cross-
sectional area in a plane orthogonal to the optical axis at a first location
of the member
and a second cross-sectional area less than the first cross-sectional area
between the first
location and the contact surface. The contact surface contacts an opposing
surface of
the intraocular lens over a contact area when the portions are at the minimum
separation
distance, the contact surface being spaced from the biasing element. The
entirety of the
separation member is positioned outside a projection of the refractive zone
along a
direction parallel to the optical axis and the separation member is out of
contact with
one of the anterior portion and the posterior portion when the viewing
elements are
separated by a distance greater than the minimum separation distance.
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All of these aspects are intended to be within the scope of the invention
herein
disclosed. These and other aspects of the invention will become readily
apparent to
those skilled in the art from the following detailed description of the
preferred
embodiments having reference to the attached figures, the invention not being
limited to
any particular preferred embodiment(s) disclosed.
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CA 02767318 2012-10-12
Brief Description of the Drawings
Having thus summarized the general nature of the invention, certain preferred
embodiments and modifications thereof will become apparent to those skilled in
the art
from the detailed description herein having reference to the figures that
follow, of
which:
Figure 1 is a sectional view of the human eye, with the lens in the
unaccommodated state.
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PREPARING AN ACCOMODATING INTRAOCULAR LENS HAVING AN
OPTICAL AXIS FOR SUBSEQUENT IMPLANTATION
Background of the Invention
Field of the Invention
This invention relates to intraocular lenses and, more particularly, to
intraocular lenses that alter the refractive power of the eye in response to
changes in
the tension of the ciliary muscle of the eye.
Description of the Related Art
The vast majority of cataract operations involve the implantation of an
artificial lens following cataract removal. Typically these lenses have a
fixed focal
length or, in the case of bifocal or multifocal lenses, have several different
fixed focal
lengths. Such fixed focal-length lenses lack the ability of the natural lens
to
dynamically change the refractive power of the eye. The various embodiments of
the
intraocular lens disclosed herein provide an accommodating lens system which
alters
the refractive power of the eye in response to changes in tension of the
ciliary muscle,
thereby allowing the lens system to bring into focus on the retina images of
objects
that are both near and far from the eye.
Summary of the Invention
In accordance with one aspect of the invention, there is provided a method of
preparing an accommodating intraocular lens having an optical axis for
subsequent
implantation. The method involves providing an intraocular lens having first
and
second viewing elements interconnected by plural members. At least a portion
of the
members are disposed from the optical axis by a distance greater than a
periphery of at
least one of the viewing elements. The distance is measured orthogonal to the
optical
axis. The method further involves drawing the members inwardly toward the
optical
axis by relatively rotating the first and second viewing elements, and
increasing the
separation between the viewing elements along the optical axis while drawing
the
members inwardly.
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In accordance with another aspect of the invention, there is provided a method
of preparing an intraocular lens having an optical axis for subsequent
implantation.
The method involves providing an intraocular lens having first and second
viewing
elements interconnected by plural members. At least a portion of the members
are
disposed from the optical axis by a distance greater than a periphery of at
least one of
the viewing elements. The distance is measured orthogonal to the optical axis.
The
method further involves providing a tool including a base and a rotor
rotatably
connected to the base. The method also involves fixing one of the first and
second
viewing elements with respect to the base, fixing the other of the first and
second
viewing elements with respect to the rotor, and drawing the members inwardly
toward
the optical axis by relatively rotating the first and second viewing elements.
Relatively
rotating the first and second viewing elements involves rotating the rotor
with respect
to the base.
In accordance with another aspect of the invention, there is provided a method
of making an accommodating intraocular lens. The method involves forming
around
a tool, as a single piece of material, anterior and posterior portions of the
lens which
have corresponding anterior and posterior viewing elements positioned to move
relative to each other in response to force on the anterior and posterior
portions. The
anterior viewing element is coupled with a first side of the tool and the
posterior
viewing element is coupled with a second side of the tool, such that the tool
is
between the anterior and posterior viewing elements. Forming further involves
providing an open space between the viewing elements, the open space has first
and
second side openings on opposing sides of the lens, and separating the tool
from the
lens through one of the side openings.
In accordance with another aspect of the invention, there is provided a method
of making an accommodating intraocular lens. The method involves forming first
and
second optics of the lens, such that at least one of the optics has refractive
power, and forming around a tool an articulated frame of the lens, as a single
piece of
material. The method further involves mounting, on the frame, the optics such
that the
optics can move relative to each other in response to force on the lens,
forming an
open space within the articulated frame, the open space having first and
second
openings on opposing sides thereof, and separating the tool from the space
within the
articulated frame.
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In accordance with another aspect of the invention, there is provided an
accommodating intraocular lens. The lens includes an anterior portion having
an
anterior viewing element including an optic having refractive power. The optic
has a
refractive zone configured to refract light that is received by a retina of a
patient. The
lens further includes a posterior portion having a posterior viewing element.
The
viewing elements are positioned to move relative to each other along an
optical axis of
the lens in response to action of the ciliary muscle of the eye. The anterior
and
posterior portions meet at first and second apices of the lens. The apices are
located on
a transverse axis of the lens. The lens also includes at least one of the
anterior and
posterior portions having at least one separation member with a contact
surface. The
at least one separation member is configured to prevent contact between the
anterior
viewing element and the posterior viewing element by inhibiting relative
movement of
the anterior and posterior portions toward each other beyond a minimum
separation
distance. The at least one separation member is located significantly closer
to the
anterior viewing element or the posterior viewing element than to either of
the
apices, the at least one separation member defines a cross-sectional area in a
plane
orthogonal to the optical axis, and the contact surface contacts an opposing
surface of
the intraocular lens over a contact area when the portions are at the minimum
separation distance. The contact area is smaller than the cross-sectional
area. The
entirety of the separation member is located outside a projection of a
periphery of the
refractive zone along a direction parallel to the optical axis, and the
separation
member is out of contact with one of the anterior portion and the posterior
portion
when the viewing elements are separated by a distance greater than the minimum
separation distance.
In accordance with another aspect of the invention, there is provided an
accommodating intraocular lens for implantation in an eye of a patient. The
lens
includes an anterior portion having an anterior viewing element including an
optic
having refractive power, and a posterior portion having a posterior viewing
element.
The viewing elements are positioned to move relative to each other along an
optical
axis of the lens in response to action of the ciliary muscle of the eye, the
anterior and
posterior portions meet at first and second apices of the lens, and the apices
are
located on a transverse axis of the lens. The lens also includes at least one
of the
anterior and posterior portions having at least one separation member with a
contact
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surface on a distal end of the separation member. The at least one separation
member
is configured to prevent contact between the anterior viewing element and the
posterior viewing element by inhibiting relative movement of the anterior and
posterior portions toward each other beyond a minimum separation distance. The
at
least one separation member is located significantly closer to the anterior
viewing
element or the posterior viewing element than to either of the apices, the at
least one
separation member defines a first cross-sectional area near the contact
surface and in a
plane orthogonal to the optical axis, and the at least one separation member
defines a
second cross-sectional area proximal of the distal end of the separation
member and in
a plane orthogonal to the optical axis. The second cross-sectional area is
larger than
the first cross-sectional area. The anterior optic has a refractive region
that is
configured to refract light that forms an image on the retina of the eye and
the
separation member is positioned outside a projection of a periphery of the
refractive
region along a direction parallel to the optical axis, and the separation
member is out
of contact with one of the anterior portion and the posterior portion when the
viewing
elements are separated by a distance greater than the minimum separation
distance.
In accordance with another aspect of the invention, there is provided an
accommodating intraocular lens implantable in an eye of a patient. The lens
includes an anterior portion having an anterior viewing element including an
optic
having refractive power. The optic has a refractive zone configured to refract
light that
is received by a retina of a patient. The lens further includes a posterior
portion having
a posterior viewing element. The viewing elements are interconnected by a
biasing
element and moveable relative to each other along an optical axis of the lens
between
an accommodated state and an unaccommodated state in response to action of the
ciliary muscle of the eye. At least one of the anterior and posterior portions
have at
least one separation member with a contact surface. The at least one
separation
member is configured to prevent contact between the anterior viewing element
and the
posterior viewing element by inhibiting relative movement of the anterior and
posterior portions toward each other beyond a minimum separation distance. The
at
least one separation member defines a first cross-sectional area in a plane
orthogonal
to the optical axis at a first location of the member and a second cross-
sectional area
less than the first cross-sectional area between the first location and the
contact
surface. The contact surface contacts an opposing surface of the intraocular
lens over a
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contact area when the portions are at the minimum separation distance. The
contact
surface is spaced from the biasing element, the entirety of the separation
member is
positioned outside a projection of the refractive zone along a direction
parallel to the
optical axis, and the separation member is out of contact with one of the
anterior
portion and the posterior portion when the viewing elements are separated by a
distance greater than the minimum separation distance.
In accordance with another aspect of the invention, there is provided a method
of making an intraocular lens having first and second viewing elements
interconnected
by a plurality of translation members extending from a periphery of the first
viewing
element. At least one of the translation members includes a plurality of arms,
and at
least one of the viewing elements includes an optic having refractive power.
The
method involves providing a first outer mold and a second outer mold, and an
inner
mold therebetween. The first outer mold and the inner mold define a first mold
space,
and the second outer mold and the inner mold define a second mold space. The
method further involves molding the viewing elements, the plurality of arms,
and the
optic as a single piece by filling the first and second mold spaces with a
material, such
that the first viewing element and the plurality of arms are formed in the
first mold
space and the second viewing element is formed in the second mold space. The
method also involves removing the first and second outer molds from the lens
while
the inner mold remains between the viewing elements, and removing the inner
mold
from between the viewing elements while the viewing elements remain
interconnected.
In accordance with another aspect of the invention, there is provided an
accommodating intraocular lens including an anterior viewing element, a
posterior
viewing element, and a biasing structure. The anterior and posterior viewing
elements
have refractive power. The biasing structure defines a side opening in the
accommodating intraocular lens, the opening extends by a distance greater than
a
diameter of at least one of the anterior and posterior viewing elements, and
the biasing
structure is configured to move the viewing elements relative to each other
along an
optical axis between an accommodated state and an unaccommodated state in
response to action of a ciliary muscle. The viewing elements are spaced
farther apart
in the accommodated state than in the unaccommodated state, the biasing
structure is
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formed of silicone, at least one of the optics is formed of acrylic, and the
diameter
extends transverse to and intersecting the optical axis of the lens.
In accordance with another aspect of the invention, there is provided an
accommodating intraocular lens including a first optic, a second optic, and a
biasing
structure. The lens inlcudes silicone, the optics are formed of an optic
material having
an index of refraction higher than that of the silicone, the biasing structure
defines a
side opening in the accommodating intraocular lens, and the side opening
extends by a
distance greater than a diameter of at least one of the first and second
optics. The
intraocular lens is biased toward the accommodated state, and the diameter
extends
transverse to and intersecting an optical axis of the lens.
In accordance with another aspect of the invention, there is provided an
accommodating intraocular lens having an optical axis. The lens includes an
anterior
optic having positive refractive power and a posterior optic having negative
refractive
power. The lens further includes an anterior biasing element and a posterior
biasing
element. The anterior biasing element and the posterior biasing element are
joined at
first and second apices which are spaced radially from the optical axis. At
least
respective portions of the anterior and posterior optics are disposed on
opposite sides
of a line passing through the first and second apices, the optics include an
optic
material having an index of refraction of about 1.49, and the lens includes
silicone.
All of these aspects are intended to be within the scope of the invention
herein
disclosed. These and other aspects of the invention will become readily
apparent to
those skilled in the art from the following detailed description of the
preferred
embodiments having reference to the attached figures, the invention not being
limited to
any particular preferred embodiment(s) disclosed.
Brief Description of the Drawings
Having thus summarized the general nature of the invention, certain preferred
embodiments and modifications thereof will become apparent to those skilled in
the
art from the detailed description herein having reference to the figures that
follow, of
which:
Figure 1 is a sectional view of the human eye, with the lens in the
unaccommodated state.
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CA 02767318 2012-01-31
Figure 2 is a sectional view of the human eye, with the lens in the
accommodated state.
Figure 3 is a perspective view of one embodiment of an intraocular lens
system.
Figure 4 is a side view of the lens system.
Figure 5 is a rear perspective view of the lens system.
Figure 6 is a front view of the lens system.
Figure 7 is a rear view of the lens system.
Figure 8 is a top view of the lens system.
Figure 9 is a side sectional view of the lens system.
Figure 10 is a top sectional view of the lens system.
Figure 11 is a second perspective view of the lens system.
Figure 12 is a third perspective view of the lens system.
Figure 13 is a side view of the lens system in the unaccommodated state.
Figure 14 is a side sectional view of the lens system in the unaccommodated
state.
Figure 15 is a top sectional view of the lens system in the unaccommodated
state.
Figure 16 is a sectional view of the human eye with the lens system implanted
in the capsular bag and the lens system in the accommodated state.
Figure 17 is a sectional view of the human eye with the lens system implanted
in the capsular bag and the lens system in the unaccommodated state.
Figure 17A is a sectional view of an arm of the lens system.
Figure 17B is a sectional view of another embodiment of the arm of the lens
system.
Figures 17C-17L are sectional views of other embodiments of the arm of the
lens system.
Figure 17M is a side sectional view of another embodiment of the lens system.
Figure 17N is a side sectional view of another embodiment of the lens system.
Figure 18 is a side view of another embodiment of the lens system.
Figure 19 is a side sectional view of another embodiment of the lens system.
Figure 20 is a rear perspective view of another embodiment of the lens system.
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CA 02767318 2012-01-31
Figure 21 is a partial top sectional view of another embodiment of the lens
system, implanted in the capsular bag.
Figure 21A is a front view of another embodiment of the lens system.
Figure 21B is a front view of another embodiment of the lens system.
Figure 21C is a front view of another embodiment of the lens system.
Figure 22 is a partial side sectional view of another embodiment of the lens
system, implanted in the capsular bag.
Figure 22A is a side view of a stop member system employed in one
embodiment of the lens system.
Figure 23 is a side view of a mold system for forming the lens system.
Figure 24 is a side sectional view of the mold system.
Figure 25 is a perspective view of a first mold portion.
Figure 26 is a perspective view of a second mold portion.
Figure 27 is a top view of the second mold portion.
Figure 28 is a side sectional view of the second mold portion.
Figure 29 is another side sectional view of the second mold portion.
Figure 30 is a bottom view of a center mold portion.
Figure 31 is a top view of the center mold portion.
Figure 32 is a sectional view of the center mold portion.
Figure 33 is another sectional view of the center mold portion.
Figure 34 is a perspective view of the center mold portion.
Figure 34A is a partial cross sectional view of an apex of the lens system,
showing a set of expansion grooves formed therein.
Figure 35 is a schematic view of another embodiment of the lens system.
Figure 36 is a schematic view of another embodiment of the lens system.
Figure 37 is a perspective view of another embodiment of the lens system.
Figure 38 is a top view of another embodiment of the lens system.
Figure 38A is a schematic view of another embodiment of the lens system, as
implanted in the capsular bag.
Figure 38B is a schematic view of the embodiment of Figure 38A, in the
accommodated state.
Figure 38C is a schematic view of biasers installed in the lens system.
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Figure 38D is a schematic view of another type of biasers installed in the
lens
system.
Figure 38E is a perspective view of another embodiment of the lens system.
Figures 39A-39B are a series of schematic views of an insertion technique for
use in connection with the lens system
Figure 40 is a schematic view of fluid-flow openings formed in the anterior
aspect of the capsular bag.
Figure 40A is a front view of the lens system, illustrating one stage of a
folding technique for use with the lens system.
Figure 40B is a front view of the lens system, illustrating another stage of
the
folding technique.
Figure 40C illustrates another stage of the folding technique.
Figure 40D illustrates another stage of the folding technique.
Figure 40E illustrates another stage of the folding technique.
Figure 4OF illustrates another stage of the folding technique.
Figure 40G is a perspective view of a folding tool for use with the lens
system.
Figure 41 is a sectional view of an aspheric optic for use with the lens
system.
Figure 42 is a sectional view of an optic having a diffractive surface for use
with the lens system.
Figure 43 is a sectional view of a low-index optic for use with the lens
system.
Figure 44 is a side elevation view of another embodiment of the lens system
with a number of separation members.
Figure 45 is a front elevation view of the lens system of Figure 44.
Figure 46 is an overhead sectional view of the lens system of Figure 44.
Figure 47 is an overhead sectional view of the lens system of Figure 44, with
the viewing elements at a minimum separation distance.
Figure 48 is a closeup view of the contact between a separation member and
an opposing surface.
Figure 49 is a side sectional view of an apparatus and method for
manufacturing a center mold.
Figure 50 is another side sectional view of the apparatus and method of Figure
49.
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Figure 51 is another side sectional view of the apparatus and method of Figure
49.
Figure 52 is another side sectional view of the apparatus and method of Figure
49.
Figure 53 is another side sectional view of the apparatus and method of Figure
49.
Figure 54 is a side sectional view of the lens system in position on the
center
mold.
Detailed Description of the Preferred Embodiment
I. THE HUMAN EYE AND ACCOMMODATION
Figures 1 and 2 show the human eye 50 in section. Of particular relevance to
the present disclosure are the cornea 52, the iris 54 and the lens 56, which
is situated
within the elastic, membranous capsular bag or lens capsule 58. The capsular
bag 58
is surrounded by and suspended within the ciliary muscle 60 by ligament-like
structures called zonules 62.
As light enters the eye 50, the cornea 52 and the lens 56 cooperate to focus
the
incoming light and form an image on the retina 64 at the rear of the eye, thus
facilitating vision. In the process known as accommodation, the shape of the
lens 56
is altered (and its refractive properties thereby adjusted) to allow the eye
50 to focus
on objects at varying distances. A typical healthy eye has sufficient
accommodation
to enable focused vision of objects ranging in distance from infinity
(generally defined
as over 20 feet from the eye) to very near (closer than 10 inches).
The lens 56 has a natural elasticity, and in its relaxed state assumes a shape
that in cross-section resembles a football. Accommodation occurs when the
ciliary
muscle 60 moves the lens from its relaxed or "unaccommodated" state (shown in
Figure 1) to a contracted or "accommodated" state (shown in Figure 2).
Movement of
the ciliary muscle 60 to the relaxed/unaccommodated state increases tension in
the
zonules 62 and capsular bag 58, which in turn causes the lens 56 to take on a
thinner
(as measured along the optical axis) or taller shape as shown in Figure 1. In
contrast,
when the ciliary muscle 60 is in the contracted/accommodated state, tension in
the
zonules 62 and capsular bag 58 is decreased and the lens 56 takes on the
fatter or
shorter shape shown in Figure 2. When the ciliary muscles 60 contract and the
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CA 02767318 2012-01-31
capsular bag 58 and zonules 62 slacken, some degree of tension is maintained
in the
capsular bag 58 and zonules 62.
II. THE LENS SYSTEM: STRUCTURE
Figures 3-17 depict one embodiment of an intraocular lens system 100 which
is configured for implantation into the capsular bag 58 in place of the
natural lens 56,
and is further configured to change the refractive properties of the eye in
response to
the eye's natural process of accommodation. With reference to Figure 3, a set
of axes
is included to illustrate the sense of directional terminology which will be
used herein
to describe various features of the lens system 100. The terms "anterior" and
"posterior" refer to the depicted directions on the optical axis of the lens
100 shown in
Figure 3. When the lens 100 is implanted in an eye, the anterior direction
extends
toward the cornea and the posterior direction extends toward the retina, with
the
optical axis of the lens substantially coincident with the optical axis of the
eye shown
in Figures 1 and 2. The terms "left" and "right" refer to the directions shown
on the
lateral axis, which is orthogonal to the optical axis. In addition, the terms
"upper" and
"lower" refer to the directions depicted on the transverse axis which is
orthogonal to
both of the optical axis and the lateral axis.
This system of axes is depicted purely to facilitate description herein; thus,
it is
not intended to limit the possible orientations which the lens system 100 may
assume
during use. For example, the lens system 100 may rotate about, or may be
displaced
along, the optical axis during use without detracting from the performance of
the lens.
It is clear that, should the lens system 100 be so rotated about the optical
axis, the
transverse axis may no longer have an upper-lower orientation and the lateral
axis may
no longer have a left-right orientation, but the lens system 100 will continue
to
function as it would when oriented as depicted in Figure 3. Accordingly, when
the
terms "upper," "lower," "left" or "right" are used in describing features of
the lens
system 100, such use should not be understood to require the described feature
to
occupy the indicated position at any or all times during use of the lens
system 100.
Similarly, such use should not be understood to require the lens system 100 to
maintain the indicated orientation at any or all times during use.
As best seen in Figure 4, the lens system 100 has an anterior portion 102
which is anterior or forward of the line A-A (which represents a plane
substantially
orthogonal to the optical axis and intersecting first and second apices 112,
116) and a
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CA 02767318 2012-01-31
posterior portion 104 which is posterior or rearward of the line A-A. The
anterior
portion 102 comprises an anterior viewing element 106 and an anterior biasing
element 108. The anterior biasing element 108 in turn comprises a first
anterior
translation member 110 which extends from the anterior viewing element 106 to
the
first apex 112 and a second anterior translation member 114 which extends from
the
anterior viewing element 106 to the second apex 116. In the illustrated
embodiment
the first anterior translation member 110 comprises a right arm 110a and a
left arm
110b (see Figure 3). In addition, the depicted second anterior translation
member 114
comprises a right arm 114a and a left arm 114b. However, in other embodiments
either or both of the first and second anterior translation members 110, 114
may
comprise a single arm or member, or more than two arms or members.
As best seen in Figures 4, 5 and 7, the posterior portion 104 includes a
posterior viewing element 118 and a posterior biasing element 120. The
posterior
biasing element 120 includes a first posterior translation member 122
extending from
the posterior viewing element 118 to the first apex 112 and a second posterior
translation member 124 extending from the posterior viewing element 118 to the
second apex 116. In the illustrated embodiment, the first posterior
translation member
comprises a right arm 122a and a left arm 122b. Likewise, the depicted second
posterior translation member 124 comprises a right arm 124a and a left arm
124b.
However, in other embodiments either or both of the first and second posterior
translation members 122, 124 may comprise a single arm or member, or more than
two arms or members.
In the embodiment shown in Figure 4, the anterior biasing element 108 and the
posterior biasing element are configured symmetrically with respect to the
plane A-A
as the lens system 100 is viewed from the side. As used herein to describe the
biasing
elements 108, 120, "symmetric" or "symmetrically" means that, as the lens
system
100 is viewed from the side, the first anterior translation member 110 and the
first
posterior translation member 122 extend from the first apex 112 at
substantially equal
first anterior and posterior biasing angles 01, 02 with respect to the line A-
A (which,
again, represents the edge of a plane which is substantially orthogonal to the
optical
axis and intersects the first and second apices 112, 116) and/or that the
second anterior
translation member 114 and the second posterior translation member 124 extend
from
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CA 02767318 2012-01-31
the second apex 116 at substantially equal second anterior and posterior
biasing angles
03, 04 with respect to the line A-A. Alternative or asymmetric configurations
of the
biasing elements are possible, as will be discussed in further detail below.
It should
be further noted that a symmetric configuration of the biasing elements 108,
120 does
not dictate symmetric positioning of the viewing elements with respect to the
line A-
A; in the embodiment shown in Figure 4 the anterior viewing element 106 is
closer to
the line A-A than is the posterior viewing element.
Preferably, both the anterior viewing element 106 and the posterior viewing
element 118 comprise an optic or lens having refractive power. (As used
herein, the
term "refractive" or "refractive power" shall include "diffractive" or
"diffractive
power") The preferred power ranges for the optics are discussed in detail
below. In
alternative embodiments one or both of the anterior and posterior viewing
elements
106, 118 may comprise an optic with a surrounding or partially surrounding
perimeter
frame member or members, with some or all of the biasing elements/translation
members attached to the frame member(s). As a further alternative, one of the
viewing elements 106, 118 may comprise a perimeter frame with an open/empty
central portion or void located on the optical axis (see Figure 20 and
discussion
below), or a perimeter frame member or members with a zero-power lens or
transparent member therein. In still further variations, one of the viewing
elements
106, 118 may comprise only a zero-power lens or transparent member.
In a presently preferred embodiment, a retention portion 126 is coupled to the
anterior portion 102, preferably at the anterior viewing element 106. The
retention
portion 126 preferably includes a first retention member 128 and a second
retention
member 130, although in alternative embodiments the retention portion 126 may
be
omitted altogether, or may comprise only one retention member or more than two
retention members. The first retention member 128 is coupled to the anterior
viewing
element 106 at a fixed end 128a and also includes a free end 128b opposite the
fixed
end 128a. Likewise, the second retention member 130 includes a fixed end 130a
and
a free end 130b. The retention members 128, 130 are illustrated as being
coupled to
the anterior viewing element 106 at the upper and lower edges thereof;
however, the
retention members 128, 130 may alternatively be attached to the anterior
viewing
element 106 at other suitable edge locations.
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In the preferred embodiment, the posterior portion 104 includes a distending
portion 132, preferably attached to the posterior viewing element 118. The
preferred
distending portion 132 includes a first distending member 134 which in turn
includes
a fixed end 134a, a free end 134b opposite the fixed end 134a and preferably
also
includes an opening 134c formed therein. The preferred distending portion 132
also
comprises a second distending member 136 with a fixed end 136a, a free end
136b
and preferably an opening 136c formed therein. In alternative embodiments, the
distending portion 132 may be omitted altogether, or may comprise a single
distending member or more than two distending members. To optimize their
effectiveness, the preferred location for the distending members 134, 136 is
90
degrees away (about the optical axis) from the apices 112, 116 on the
posterior portion
104. Where the biasing elements form more than two apices (or where two apices
are
not spaced 180 degrees apart about the optical axis), one or more distending
members
may be positioned angularly midway between the apices about the optical axis.
Alternatively, the distending member(s) may occupy other suitable positions
relative
to the apices (besides the "angularly midway" positions disclosed above); as
further
alternatives, the distending member(s) may be located on the anterior portion
102 of
the lens system 100, or even on the apices themselves. The functions of the
retention
portion 126 and the distending portion 132 will be described in greater detail
below.
III. THE LENS SYSTEM: FUNCTION/OPTICS
The anterior and posterior biasing elements 108, 120 function in a springlike
manner to permit the anterior viewing element 106 and posterior viewing
element 118
to move relative to each other generally along the optical axis. The biasing
elements
108, 120 bias the viewing elements 106, 118 apart so that the elements 106,
108
separate to the accommodated position or accommodated state shown in Figure 4.
Thus, in the absence of any external forces, the viewing elements are at their
maximum separation along the optical axis. The viewing elements 106, 118 of
the
lens system 100 may be moved toward each other, in response to a ciliary
muscle
force of up to 2 grams, to provide an unaccommodated position by applying
appropriate forces upon the anterior and posterior portions 102, 104 and/or
the apices
112, 116.
When the lens system 100 is implanted in the capsular bag 58 (Figures 16-17)
the above described biasing forces cause the lens system 100 to expand along
the
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CA 02767318 2012-01-31
optical axis so as to interact with both the posterior and anterior aspects of
the
capsular bag. Such interaction occurs throughout the entire range of motion of
the
ciliary muscle 60. At one extreme the ciliary muscle is relaxed and the
zonules 62
pull the capsular bag 58 radially so as to cause the bag to become more disk
shaped.
The anterior and posterior sides of the bag, in turn, apply force to the
anterior and
posterior portions 102, 104 of the lens system 100, thereby forcing the
viewing
elements 106, 118 toward each other into the accommodated position. At the
other
extreme, the ciliary muscle contracts and the zonules 62 move inwardly to
provide
slack in the capsular bag 58 and allow the bag to become more football-shaped.
The
slack in the bag is taken up by the lens system due to the biasing-apart of
the anterior
and posterior viewing elements 106, 118. As the radial tension in the bag is
reduced,
the viewing elements 106, 118 move away from each other into an accommodated
position. Thus, the distance between the viewing elements 106, 118 depends on
the
degree of contraction or relaxation of the ciliary muscle 60. As the distance
between
the anterior and posterior viewing elements 106, 118 is varied, the focal
length of the
lens system 100 changes accordingly. Thus, when the lens system 100 is
implanted
into the capsular bag (see Figures 16-17) the lens system 100 operates in
conjunction
with the natural accommodation processes of the eye to move between the
accommodated (Figure 16) and unaccommodated (Figure 17) states in the same
manner as would a healthy "natural" lens. Preferably, the lens system 100 can
move
between the accommodated and unaccommodated states in less than about one
second.
The entire lens system 100, other than the optic(s), thus comprises an
articulated frame whose functions include holding the optic(s) in position
within the
capsular bag and guiding and causing movement of the optic(s) between the
accommodated and unaccommodated positions.
Advantageously, the entire lens system 100 may comprise a single piece of
material, i.e. one that is formed without need to assemble two or more
components by
gluing, heat bonding, the use of fasteners or interlocking elements, etc. This
characteristic increases the reliability of the lens system 100 by improving
its
resistance to material fatigue effects which can arise as the lens system
experiences
millions of accommodation cycles throughout its service life. It will be
readily
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CA 02767318 2012-01-31
appreciated that the molding process and mold tooling discussed herein, lend
themselves to the molding of lens systems 100 that comprise a single piece of
material. However, any other suitable technique may be employed to manufacture
single-piece lens systems.
In those embodiments where the optic(s) are installed into annular or other
perimeter frame member(s) (see discussion below), the articulated frame may
comprise a single piece of material, to obtain the performance advantages
discussed
above. It is believed that the assembly of the optic(s) to the articulated
frame will not
substantially detract from the achievement of these advantages.
The lens system 100 has sufficient dynamic range that the anterior and
posterior viewing elements 106, 118 move about 0.5-4 mm, preferably about 1-3
mm,
more preferably about 1-2 mm, and most preferably about 1.5 mm closer together
when the lens system 100 moves from the accommodated state to the
unaccommodated state. In other words the separation distance X (see Figures 9-
10,
14-15) between the anterior and posterior viewing elements 106, 118, which
distance
may for present purposes be defined as the distance along the optical axis (or
a
parallel axis) between a point of axial intersection with the posterior face
of the
anterior viewing element 106 and a point of axial intersection with the
anterior face of
the posterior viewing element 118, decreases by the amount(s) disclosed above
upon
movement of the lens system 100 to the unaccommodated state. Simultaneously,
in
the preferred mode the total system thickness Y decreases from about 3.0 - 4.0
mm in
the accommodated state to about 1.5 - 2.5 mm in the unaccommodated state.
As may be best seen in Figure 6, the first anterior translation member 110
connects to the anterior viewing element 106 via connection of the left and
right arms
110a, 110b to first and second transition members 138, 140 at attachment
locations
142, 144. The second anterior translation member 114 connects to the anterior
viewing element 106 via connection of left and right arms 114a, 114b to the
first and
second transition members 138, 140 at attachment locations 146, 148. This is a
presently preferred arrangement for the first and second anterior translation
members
110, 114; alternatively, the first and second anterior translation members
110, 114
could be connected directly to the anterior viewing element 106, as is the
case with the
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CA 02767318 2012-01-31
connection of the first and second posterior translation members 122, 124 to
the
posterior viewing element 118.
However the connection is established between the first and second anterior
translation members 110, 114 and the anterior viewing element 106, it is
preferred
that the attachment locations 142, 144 corresponding to the first anterior
translation
member 110 be farther away from the first apex 112 than is the closest edge or
the
periphery of the anterior viewing element 106. This configuration increases
the
effective length of the first anterior translation member 110/arms 110a, 110b,
in
comparison to a direct or straight attachment between the apex 112 and the
nearest/top
edge of the anterior viewing element 106. For the same reasons, it is
preferred that the
attachment locations 146, 148 associated with the second anterior translation
member
114 be farther away from the second apex 116 than is the closest/bottom edge
of the
anterior viewing element 106.
As best seen in Figure 7, the first posterior translation member 122 is
preferably connected directly to the posterior viewing element 118 via
attachment of
the left and right arms 122a, 122b to the element 118 at attachment points
150, 152.
Likewise, the second posterior translation member 124 is preferably directly
connected to the posterior viewing element 118 via connection of the left and
right
arms 124a, 124b to the element 118 at attachment points 154, 156,
respectively. In
alternative embodiments, the first and second posterior translation members
124, 122
can be connected to the posterior viewing element via intervening members as
is done
with the anterior viewing element 106. No matter how these connections are
made, it
is preferred that the attachment locations 150, 152 be spaced further away
from the
first apex 112 than is the nearest edge or the periphery of the posterior
viewing
element 118. Similarly, it is preferred that the attachment locations 154, 156
be
spaced further away from the second apex 116 than is the closest edge of the
posterior
viewing element 118.
By increasing the effective length of some or all of the translation members
110, 114, 122, 124 (and that of the arms 110a, 110b, 114a, 114b, 122a, 122b,
124a,
124b where such structure is employed), the preferred configuration of the
attachment
locations 142, 144, 146, 148, 150, 152, 154, 156 relative to the first and
second apices
112, 116 enables the anterior and/or posterior viewing elements 106, 118 to
move
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CA 02767318 2012-01-31
with respect to one another a greater distance along the optical axis, for a
given
angular displacement of the anterior and/or posterior translation members.
This
arrangement thus facilitates a more responsive spring system for the lens
system 100
and minimizes material fatigue effects associated with prolonged exposure to
repeated
flexing.
In the illustrated embodiment, the attachment location 142 of the first
anterior
translation member 110 is spaced from the corresponding attachment location
146 of
the second anterior translation member 114 along the periphery of the anterior
viewing element, and the same relationship exists between the other pairs of
attachment locations 144, 148; 150, 154; and 152, 156. This arrangement
advantageously broadens the support base for the anterior and posterior
viewing
elements 106, 118 and prevents them from twisting about an axis parallel to
the lateral
axis, as the viewing elements move between the accommodated and unaccommodated
positions.
It is also preferred that the attachment locations 142, 144 of the first
anterior
translation member 110 be located equidistant from the first apex 112, and
that the
right and left arms 110a, 110b of the member 110 be equal in length.
Furthermore,
the arrangement of the attachment locations 146, 148, arms 114a, 114b and
second
apex preferably mirrors that recited above regarding the first anterior
translation
member 110, while the apices 112, 116 are preferably equidistant from the
optical axis
and are situated 180 degrees apart. This configuration maintains the anterior
viewing
element 106 orthogonal to the optical axis as the viewing element 106 moves
back
and forth and the anterior viewing element flexes.
For the same reasons, a like combination of equidistance and equal length is
preferred for the first and second posterior translation members 122, 124 and
their
constituent arms 122a, 122b, 124a, 124b and attachment points 150, 152, 154,
156,
with respect to the apices 112, 116. However, as shown the arms 122a, 122b,
124a,
124b need not be equal in length to their counterparts 110a, 110b, 114a, 114b
in the
first and second anterior translation members 110, 114.
Where any member or element connects to the periphery of the anterior or
posterior viewing elements 106, 118, the member defines a connection geometry
or
attachment area with a connection width W and a connection thickness T (see
Figure
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CA 02767318 2012-01-31
4 and the example illustrated therein, of the connection of the second
posterior
translation member 124 to the posterior viewing element 118). For purposes of
clarity, the connection width is defined as being measured along a direction
substantially parallel to the periphery of the viewing element in question,
and the
connection thickness is defined as measured along a direction substantially
perpendicular to the periphery of the viewing element. (The periphery itself
is
deemed to be oriented generally perpendicular to the optical axis as shown in
Figure
4.) Preferably, no attachment area employed in the lens system 100 has a ratio
of
width to thickness less than 3. It has been found that such a geometry reduces
distortion of the viewing element/optic due to localized forces. For the same
reasons,
it is also preferred that each of the translation members 110, 114, 122, 124
be
connected to the periphery of the respective viewing elements at least two
attachment
areas, each having the preferred geometry discussed above.
Figures 17A and 17B show two preferred cross-sectional configurations which
may be used along some or all of the length of the translation members and/or
arms
110a, 110b, 114a, 114b, 122a, 122b, 124a, 124b. The shape is defined by a
relatively
broad and flat or slightly curved outer surface 182. It is intended that when
in use the
outer surface faces away from the interior of the lens system and/or toward
the
capsular bag 58. The remaining surfaces, proportions and dimensions making up
the
cross-sectional shape can vary widely but may advantageously be selected to
facilitate
manufacture of the lens system 100 via molding or casting techniques while
minimizing stresses in the arms during use of the lens system.
Figures 17.C-17L depict a number of alternative cross-sectional configurations
which are suitable for the translation members and/or arms 110a, 110b, 114a,
114b,
122a, 122b, 124a, 124b. As shown, a wide variety of cross-sectional shapes may
be
used, but preferably any shape includes the relatively broad and flat or
slightly curved
outer surface 182.
It is further contemplated that the dimensions, shapes, and/or proportions of
the cross-sectional configuration of the translation members and/or arms 110a,
110b,
114a, 114b, 122a, 122b, 124a, 124b may vary along the length of the
members/arms.
This may be done in order to, for example, add strength to high-stress regions
of the
arms, fine-tune their spring characteristics, add rigidity or flexibility,
etc.
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CA 02767318 2012-01-31
As discussed above, each of the anterior viewing element 106 and the posterior
viewing element 118 preferably comprises an optic having refractive power. In
one
preferred embodiment, the anterior viewing element 106 comprises a biconvex
lens
having positive refractive power and the posterior viewing element 118
comprises a
convexo-concave lens having negative refractive power. The anterior viewing
element 106 may comprise a lens having a positive power advantageously less
than 55
diopters, preferably less than 40 diopters, more preferably less than 35
diopters, and
most preferably less than 30 diopters. The posterior viewing element 118 may
comprise a lens having a power which is advantageously between -25 and 0
diopters,
and preferably between -25 and -15 diopters. In other embodiments, the
posterior
viewing element 118 comprises a lens having a power which is between -15 and 0
diopters, preferably between -13 and -2 diopters, and most preferably between -
10 and
-5 diopters. Advantageously, the total power of the optic(s) employed in the
lens
system 100 is about 5-35 diopters; preferably, the total power is about 10-30
diopters;
most preferably, the total power is about 15-25 diopters. (As used herein, the
term
"diopter" refers to lens or system power as measured when the lens system 100
has
been implanted in the human eye in the usual manner.) It should be noted that
if
materials having a high index of refraction (e.g., higher than that of
silicone) are used,
the optics may be made thinner which facilitates a wider range of motion for
the
optics. This in turn allows the use of lower-power optics than those specified
above.
In addition, higher-index materials allow the manufacture of a higher-power
lens for a
given lens thickness and thereby reduce the range of motion needed to achieve
a given
range of accommodation.
Some lens powers and radii of curvature presently preferred for use with an
embodiment of the lens system 100 with optic(s) having a refractive index of
about
1.432 are as follows: a +31 diopter, biconvex lens with an anterior radius of
curvature
of 5.944 mm and a posterior radius of curvature of 5.944 mm; a +28 diopter,
biconvex
lens with an anterior radius of curvature of 5.656 mm and a posterior radius
of
curvature of 7.788 mm; a +24 diopter, biconvex lens with an anterior radius of
curvature of 6.961 mm and a posterior radius of curvature of 8.5 mm; a -10
diopter,
biconcave lens with an anterior radius of curvature of 18.765 mm and a
posterior
radius of curvature of 18.765 mm; a -8 diopter, concavo-convex lens with an
anterior
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CA 02767318 2012-01-31
radius of curvature of between 9 mm and 9.534 mm and a posterior radius of
curvature of 40 mm; and a -5 diopter, concavo-convex lens with an anterior
radius of
curvature of between 9 mm and 9.534 mm and a posterior radius of curvature of
20
mm. In one embodiment, the anterior viewing element comprises the +31 diopter
lens
described above and the posterior viewing element comprises the -10 diopter
lens
described above. In another embodiment, the anterior viewing element comprises
the
+28 diopter lens described above and the posterior viewing element comprises
the -8
diopter lens described above. In another embodiment, the anterior viewing
element
comprises the +24 diopter lens described above and the posterior viewing
element
comprises the -5 diopter lens described above.
The combinations of lens powers and radii of curvature specified herein
advantageously minimize image magnification. However, other designs and radii
of
curvature provide modified magnification when desirable.
The lenses of the anterior viewing element 106 and the posterior viewing
element 118 are relatively moveable as discussed above; advantageously, this
movement is sufficient to produce an accommodation of at least one diopter,
preferably at least two diopters and most preferably at least three diopters.
In other
words, the movement of the optics relative to each other and/or to the cornea
is
sufficient to create a difference between (i) the refractive power of the
user's eye in
the accommodated state and (ii) the refractive power of the user's eye in the
unaccommodated state, having a magnitude expressed in diopters as specified
above.
Where the lens system 100 has a single optic, the movement of the optic
relative to the
cornea is sufficient to create a difference in focal power as specified above.
Advantageously, the lens system 100 can be customized for an individual
patient's needs by shaping or adjusting only one of the four lens faces, and
thereby
altering the overall optical characteristics of the system 100. This in turn
facilitates
easy manufacture and maintenance of an inventory of lens systems with lens
powers
which will fit a large population of patients, without necessitating complex
adjustment
procedures at the time of implantation. It is contemplated that all of the
lens systems
in the inventory have a standard combination of lens powers, and that a system
is
fitted to a particular patient by simply shaping only a designated "variable"
lens face.
This custom-shaping procedure can be performed to-order at a central
manufacturing
facility or laboratory, or by a physician consulting with an individual
patient. In one
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CA 02767318 2012-01-31
embodiment, the anterior face of the anterior viewing element is the
designated sole
variable lens face. In another embodiment, the anterior face of the posterior
viewing
element is the only variable face. However, any of the lens faces is suitable
for such
designation. The result is minimal inventory burden with respect to lens power
(all of
the lens systems in stock have the same lens powers) without requiring complex
adjustment for individual patients (only one of the four lens faces is
adjusted in the
fitting process).
IV. THE LENS SYSTEM: ALTERNATIVE EMBODIMENTS
Figure 17M depicts another embodiment of the lens system 100 in which the
anterior viewing element 106 comprises an optic with a smaller diameter than
the
posterior viewing element 118, which comprises an optic with a peripheral
positive-
lens portion 170 surrounding a central negative portion 172. This arrangement
enables the user of the lens system 100 to focus on objects at infinity, by
allowing the
(generally parallel) light rays incident upon the eye from an object at
infinity to bypass
the anterior viewing element 106. The peripheral positive-lens portion 170 of
the
posterior viewing element 118 can then function alone in refracting the light
rays,
providing the user with focused vision at infinity (in addition to the range
of visual
distances facilitated by the anterior and posterior viewing elements acting in
concert).
In another embodiment, the anterior viewing element 106 comprises an optic
having a
diameter of approximately 3 millimeters or less. In yet another embodiment,
the
anterior viewing element 106 comprises an optic having a diameter of
approximately
3 millimeters or less and a refractive power of less than 55 diopters, more
preferably
less than 30 diopters. In still another embodiment, the peripheral positive-
lens portion
170 has a refractive power of about 20 diopters.
Figure 17N shows an alternative arrangement in which, the anterior viewing
element 106 comprises an optic having a central portion 176 with refractive
power,
and a surrounding peripheral region 174 having a refractive power of
substantially
zero, wherein the central region 176 has a diameter smaller than the optic of
the
posterior viewing element 118, and preferably has a diameter of less than
about 3
millimeters. This embodiment also allows some incident light rays to pass the
anterior viewing element (though the zero-power peripheral region 174) without
refraction, allowing the peripheral positive-lens portion 170 posterior
viewing element
118 to function alone as described above.
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CA 02767318 2012-01-31
Figures 18 and 19 depict another embodiment 250 of the intraocular lens. It is
contemplated that, except as noted below, this embodiment 250 is largely
similar to
the embodiment disclosed in FIGS. 3-17. The lens 250 features an anterior
biasing
element 108 and posterior biasing element 120 which are arranged
asymmetrically as
the lens system 100 is viewed from the side. As used herein to describe the
biasing
elements 108, 120, "asymmetric" or "asymmetrically" means that, as the lens
system
250 is viewed from the side, the first anterior translation member 110 and the
first
posterior translation member 122 extend from the first apex 112 at unequal
first
anterior and posterior biasing angles 81, 82 with respect to the line B-B
(which
represents the edge of a plane which is substantially orthogonal to the
optical axis and
intersects the first and second apices 112, 116) and/or that the second
anterior
translation member 114 and the second posterior translation member 124 extend
from
the second apex 116 at unequal second anterior and posterior biasing angles
63, 84
with respect to the line B-B.
In the embodiment shown in Figures 18-19, the first and second anterior
biasing angles 81, 63 are greater than the corresponding first and second
posterior
biasing angles 62, 84. This arrangement advantageously maintains the posterior
viewing element 118 and apices 112, 116 in a substantially stationary
position.
Consequently, the moving mass of the lens system 250 is reduced, and the
anterior
viewing element 106 can move more quickly over a wider range along the optical
axis
under a given motive force. (Note that even where the posterior biasing
element 120
and its constituent first and second posterior translation members 122, 124
are
substantially immobile, they are nonetheless "biasing elements" and
"translation
members" as those terms are used herein.) In another embodiment, the anterior
biasing element 108 and posterior biasing element 120 are arranged
asymmetrically in
the opposite direction, i.e. such that the first and second anterior biasing
angles 81, 83
are smaller than the corresponding first and second posterior biasing angles
62, 54.
This arrangement also provides for a wider range of relative movement of the
viewing
elements, in comparison to a "symmetric" system.
It should be further noted that the viewing elements 106, 118 shown in Figures
18-19 are asymmetrically positioned in that the posterior viewing element 118
is
closer to the line B-B than is the anterior viewing element 106. It has been
found that
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CA 02767318 2012-01-31
this configuration yields desirable performance characteristics irrespective
of the
configuration of the biasing elements 108, 120. In alternative embodiments,
the
viewing elements 106, 118 may be positioned symmetrically with respect to the
line
B-B, or they may be positioned asymmetrically with the anterior viewing
element 106
closer to the line B-B than the posterior viewing element 118 (see Figure 4
wherein
the line in question is denoted A-A). Furthermore, the symmetry or asymmetry
of the
biasing elements and viewing elements can be selected independently of each
other.
Figure 20 shows another embodiment 350 of an intraocular lens in which the
posterior viewing element 118 comprises an annular frame member defining a
void
therein, while the anterior viewing element 106 comprises an optic having
refractive
power. Alternatively, the posterior viewing element 118 could comprise a zero
power
lens or a simple transparent member. Likewise, in another embodiment the
anterior
viewing element 106 could comprise an annular frame member with a void therein
or
a simple zero power lens or transparent member, with the posterior viewing
element
118 comprising an optic having refractive power. As a further alternative, one
or both
of the anterior and posterior viewing elements 106, 118 may comprise an
annular or
other perimeter frame member which can receive a removable optic (or a "one-
time
install" optic) with an interference type fit and/or subsequent adhesive or
welding
connections. Such a configuration facilitates assembly and/or fine-tuning of
the lens
system during an implantation procedure, as will be discussed in further
detail below.
V. THE LENS SYSTEM: ADDITIONAL FEATURES
Figure 21 depicts the function of the distending portion 132 in greater
detail.
The lens system 100 is shown situated in the capsular bag 58 in the customary
manner
with the anterior viewing element 106 and posterior viewing element 118
arranged
along the optical axis. The capsular bag 58 is shown with a generally circular
anterior
opening 66 which may often be cut into the capsular bag during installation of
the lens
system 100. The first and second distending members 134, 136 of the distending
portion 132 distend the capsular bag 58 so that intimate contact is created
between the
posterior face of the posterior viewing element and/or the posterior biasing
element
120. In addition, intimate contact is facilitated between the anterior face of
the
anterior viewing element 106 and/or anterior biasing element 108. The
distending
members 134, 136 thus remove any slack from the capsular bag 58 and ensure
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CA 02767318 2012-01-31
optimum force coupling between the bag 58 and the lens system 100 as the bag
58 is
alternately stretched and released by the action of the ciliary muscle.
Furthermore, the distending members 134, 136 reshape the capsular bag 58
into a taller, thinner configuration along its range of accommodation to
provide a
wider range of relative motion of the viewing elements 106, 118. When the
capsular
bag 58 is in the unaccommodated state, the distending members 134, 136 force
the
capsular bag into a thinner configuration (as measured along the optical axis)
in
comparison to the unaccommodated configuration of the capsular bag 58 with the
natural lens in place. Preferably, the distending members 134, 136 cause the
capsular
bag 58 to taken on a shape in the unaccommodated state which is about 1.0-2.0
mm
thinner, more preferably about 1.5 mm thinner, along the optical axis than it
is with
the natural lens in place and in the unaccommodated state.
With such a thin "starting point" provided by the distending members 134,
136, the viewing elements 106, 118 of the lens system can move a greater
distance
apart, and provide a greater range of accommodation, without causing
undesirable
contact between the lens system and the iris. Accordingly, by reshaping the
bag as
discussed above the distending members 134, 136 facilitate a range of relative
motion
of the anterior and posterior viewing elements 106, 118 of about 0.5-4 mm,
preferably
about 1-3 mm, more preferably about 1-2 mm, and most preferably about 1.5 mm.
The distending portion 132/distending members 134, 136 are preferably
separate from the anterior and posterior biasing elements 108, 120; the
distending
members 134, 136 thus preferably play no part in biasing the anterior and
posterior
viewing elements 106, 118 apart toward the accommodated position. This
arrangement is advantageous because the apices 112, 116 of the biasing
elements 108,
120 reach their point of minimum protrusion from the optical axis (and thus
the
biasing elements reach their minimum potential effectiveness for radially
distending
the capsular bag) when the lens system 100 is in the accommodated state (see
Figure
16), which is precisely when the need is greatest for a taut capsular bag so
as to
provide immediate response to relaxation of the ciliary muscles. The preferred
distending portion is "static" (as opposed to the "dynamic" biasing members
108, 120
which move while urging the viewing elements 106, 118 to the accommodated
position or carrying the viewing elements to the unaccommodated position) in
that its
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member(s) protrude a substantially constant distance from the optical axis
throughout
the range of motion of the viewing elements 106, 118. Although some degree of
flexing may be observed in the distending members 134, 136, they are most
effective
when rigid. Furthermore, the thickness and/or cross-sectional profile of the
distending
members 134/136 may be varied over the length of the members as desired to
provide
a desired degree of rigidity thereto.
The distending portion 132/distending members 132, 134 advantageously
reshape the capsular bag 58 by stretching the bag 58 radially away from the
optical
axis and causing the bag 58 to take on a thinner, taller shape throughout the
range of
accommodation by the eye. This reshaping is believed to facilitate a broad (as
specified above) range of relative motion for the viewing elements of the lens
system
100, with appropriate endpoints (derived from the total system thicknesses
detailed
above) to avoid the need for unacceptably thick optic(s) in the lens system.
If desired, the distending members 134, 136 may also function as haptics to
stabilize and fixate the orientation of the lens system 100 within the
capsular bag. The
openings 134c, 136c of the preferred distending members 134,136 permit
cellular
ingrowth from the capsular bag upon positioning of the lens system 100
therein.
Finally, other methodologies, such as a separate capsular tension ring or the
use of
adhesives to glue the capsular bag together in selected regions, may be used
instead of
or in addition to the distending portion 132, to reduce "slack" in the
capsular bag.
A tension ring can also act as a physical barrier to cell growth on the inner
surface of the capsular bag, and thus can provide additional benefits in
limiting
posterior capsule pacification, by preventing cellular growth from advancing
posteriorly on the inner surface of the bag. When implanted, the tension ring
firmly
contacts the inner surface of the bag and defines a circumferential barrier
against cell
growth on the inner surface from one side of the barrier to another.
Figure 21A shows an alternative configuration of the distending portion 132,
in which the distending members 134, 136 comprise first and second arcuate
portions
which connect at either end to the apices 112, 116 to form therewith an
integral
perimeter member. In this arrangement it is preferred that the distending
members
and apices form an oval with height I smaller than width J.
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Figure 21B shows another alternative configuration of the distending portion
132, in which arcuate rim portions 137 interconnect the apices 112, 116 and
the free
ends 134b, 136b of the distending members 134, 136. Thus is formed an integral
perimeter member with generally higher lateral rigidity than the arrangement
depicted
in Figure 21A.
Figure 21C shows another alternative configuration of the distending portion
132, in which the distending members 134, 136 are integrally formed with the
first
and second posterior translation members 122, 124. The distending members 134,
136 and translation members 122, 124 thus form common transition members 139
Figure 22 shows the function of the retention portion 126 in greater detail.
It
is readily seen that the first and second retention members 128, 130
facilitate a broad
contact base between the anterior portion of the lens system 100 and the
anterior
aspect of the capsular bag 58. By appropriately spacing the first and second
retention
As best seen in Figures 21 and 22, the anterior portion 102 of the lens system
100 forms a number of regions of contact with the capsular bag 58, around the
perimeter of the anterior viewing element 106. In the illustrated embodiment,
at least
some of these regions of contact are located on the anteriormost portions of
the
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portion 102 of the lens system 100 seals the anterior opening 66 of the bag
58, the
resulting prevention of fluid flow can cause the aqueous humor in the capsular
bag to
stagnate, leading to a clinically adverse event, and can inhibit the movement
of the
lens system 100 between the accommodated and unaccommodated states.
If desired, one or both of the retention members 128, 130 may have an opening
129 formed therein to permit fluid flow as discussed above. (See Figure 21A.)
The retention members 128, 130 and the transition members 138, 140 also
prevent contact between the iris and the anterior viewing element 106, by
separating
the anterior opening 66 from the anterior face of the viewing element 106. In
other
words, the retention members 128, 130 and the transition members 138, 140
displace
the anterior aspect of the capsular bag 58, including the anterior opening 66,
anteriorly
from the anterior viewing element 106, and maintain this separation throughout
the
range of accommodation of the lens system. Thus, if contact occurs between the
iris
and the lens system-capsular bag assembly, no part of the lens system will
touch the
iris, only the capsular bag itself, in particular those portions of the bag 58
overlying
the retention members 128, 130 and/or the transition members 138, 140. The
retention members 128, 130 and/or the transition members 138, 140 therefore
maintain a separation between the iris and the lens system, which can be
clinically
adverse if the contacting portion(s) of the lens system are constructed from
silicone.
As depicted in Figure 22A, one or more stop members or separation members
190 may be located where appropriate on the anterior and/or posterior biasing
elements 108, 120 to limit the convergent motion of the anterior and posterior
viewing
elements 106, 118, and preferably prevent contact therebetween. As the lens
system
100 moves toward the unaccommodated position, the stop member(s) located on
the
anterior biasing element 108 come into contact with the posterior biasing
element 120
(or with additional stop member(s) located on thereon), and any stop member(s)
located on the posterior biasing element 120 come into contact with the
anterior
biasing element 108 (or with additional stop member(s) located thereon). The
stop
members 190 thus define a point or state of maximum convergence (in other
words,
the unaccommodated state) of the lens system 100/ viewing elements 106, 118.
Such
definition advantageously assists in setting one extreme of the range of focal
lengths
which the lens system may take on (in those lens systems which include two or
more
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viewing elements having refractive power) and/or one extreme of the range of
motion
of the lens system 100.
The stop members 190 shown in Figure 22A are located on the first and
second anterior translation members 110, 114 of the anterior biasing element
108 and
extend posteriorly therefrom. When the anterior and posterior viewing elements
106,
118 move together, one or more of the stop members 190 will contact the
posterior
translation member(s) 122, 124, thereby preventing further convergent motion
of the
viewing elements 106, 118. Of course, in other embodiments the stop member(s)
190
can be in any suitable location on the lens system 100.
Figures 44-48 depict another embodiment of the lens system 100 having a
number of stop members or separation members 190. In this embodiment the stop
members 190 include posts 190a and tabs 190b, although it will be apparent
that any
number or combination of suitable shapes may be employed for the stop members
190. Each of the stop members 190 has at least one contact surface 191, one or
more
of which abuts an opposing surface of the lens system 100 when the anterior
and
posterior viewing elements 106, 118 converge to a minimum separation distance
SD
(see Figure 47). In the embodiment shown, one or more of the contact surfaces
191 of
the posts 190a are configured to abut an opposing surface defined by a
substantially
flat anterior perimeter portion 193 of the posterior viewing element 118, when
the
viewing elements 106, 118 are at the minimum separation distance SD. One or
more
of the contact surfaces 191 of the tabs 190b are configured to abut opposing
surfaces
defined by substantially flat anterior faces 195 of the distending members
134, 136,
only if the viewing elements 106, 118 are urged together beyond the minimum
separation distance SD. This arrangement permits the tabs 190b to function as
secondary stop members should the posts 190a fail to maintain separation of
the
viewing elements.
In other embodiments all of the contact surfaces 191 of the posts 190a and
tabs
190b may be configured to contact their respective opposing surfaces when the
viewing elements 106, 118 are at the minimum separation distance SD. In still
further
embodiments, the contact surfaces 191 of the tabs 190b may be configured to
contact
the opposing surfaces when the viewing elements 106, 118 are at the minimum
separation distance SD and the contact surfaces 191 of the posts 190a
configured to
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contact the opposing surfaces only if the viewing elements 106, 118 are urged
together
beyond the minimum separation distance SD. In one embodiment, the minimum
separation distance SD is about 0.1 - 1.0 mm; in another embodiment the
minimum
separation distance SD is about 0.5 mm.
When one of the contact surfaces abuts one of the opposing surfaces, the two
surfaces define a contact area CA (see Figure 48, depicting an example of a
contact
area CA defined when the contact surface 191 of a post 190a contacts an
opposing
surface defined by the perimeter portion 193 of the posterior viewing element
118).
Preferably, the contact surface and opposing surface are shaped to
cooperatively
minimize the size of the contact area, to prevent adhesion between the contact
surface
and the opposing surface, which is often a concern when one or both of these
surfaces
has an adhesive affinity for the other. In the embodiment shown, this non-
adhesive
characteristic is achieved by employing a substantially hemispherical contact
surface
191 and a substantially flat opposing surface (perimeter portion 193). Of
course, other
configurations can be selected for the contact surface(s) 191, including
conical,
frustoconical, hemicylindrical, pyramidal, or other rounded, tapered or
pointed shapes.
All of these configurations minimize the contact area CA while permitting the
cross-
sectional area CS of the stop member 190 (such as the post 190a depicted) to
be made
larger than the contact area CA, to impart sufficient strength to the stop
member
despite the relatively small contact area CA. Indeed, when constructing the
contact
surface(s) 191 any configuration may be employed which defines a contact area
CA
which is smaller than the cross-sectional area CS of the stop member 190. As
further
alternatives, the contact surface(s) 191 may be substantially flat and the
opposing
surface(s) may have a shape which defines, upon contact with the opposing
surface, a
contact area CA which is smaller than the cross-sectional area CS of the stop
member.
Thus, the opposing surface(s) may have, for example, a hemispherical, conical,
frustoconical, hemicylindrical, pyramidal, or other rounded, tapered or
pointed shape.
Other design features of the stop members 190 can be selected to maximize
their ability to prevent adhesion of the contact surface(s) to the
corresponding
opposing surface(s), or adhesion to each other of any part of the anterior and
posterior
portions 102, 104 of the lens system 100. For example, the contact and
opposing
surfaces may be formed from dissimilar materials to reduce the effect of any
self-
adhesive materials employed in forming the lens system 100. In addition the
shape
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CA 02767318 2012-01-31
and/or material employed in constructing one or more of the stop members 190
can be
selected to impart a spring-like quality to the stop member(s) in question, so
that when
the stop member is loaded in compression as the viewing elements are urged
together
at the minimum separation distance, the stop member tends to exert a resisting
spring
force, due to either bending or axial compression (or both) of the stop
member, which
in turn derive from the elasticity of the material(s) from which the stop
member is
constructed, or the shape of the stop member, or both. This springlike quality
is
particularly effective for inhibiting adhesion of areas of the anterior and
posterior
portions 102, 104 other than the contact surface(s) and opposing surface(s).
As used herein, the term "adhesion" refers to attachment to each other of (i)
an
area of the anterior portion 102 of the lens system 100 and (ii) a
corresponding area of
the posterior portion 104 (other than the apices 112, 116), wherein such
attachment is
sufficiently strong to prevent, other than momentarily, the anterior and
posterior
viewing elements 106, 118 from moving apart along the optical axis under the
biasing
force of the anterior and/or posterior biasing elements 108, 120. If the areas
in
question are formed of different materials, adhesion may occur where at least
one of
the materials has an adhesive affinity for the other material. If the areas in
question
are formed of the same material, adhesion may occur where the material has an
adhesive affinity for itself.
In the embodiment shown, four posts 190a are positioned near the perimeter of
the anterior viewing element 106, equally angularly spaced around the optical
axis. In
addition, two tabs 190b are located on either side of the anterior viewing
element,
midway between the apices 112, 116 of the lens system. Naturally, the number,
type
and/or position of the stop members 190 can be varied while preserving the
advantageous function of maintaining separation between the anterior and
posterior
portions of the lens system.
The illustrated embodiment employs stop members 190 which extend
posteriorly from the anterior portion 102 of the lens system 100, so that the
contact
surfaces 191 are located on the posterior extremities of the stop members 190
and are
configured to abut opposing surfaces formed on the posterior portion 104 of
the lens
system 100. However, it will be appreciated that some or all of the stop
members 190
may extend anteriorly from the posterior portion 104 of the lens system 100,
so that
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CA 02767318 2012-01-31
their contact surfaces 191 are located on the anterior extremities of the stop
members
190 and are configured to abut opposing surfaces formed on the anterior
portion 102
of the lens system 100.
VI. MOLD TOOLING
Figures 23-34 depict a mold system 500 which is suitable for molding the lens
system 100 depicted in Figure 3-17. The mold system 500 generally comprises a
first
mold 502, a second mold 504 and a center mold 506. The center mold 506 is
adapted
to be positioned between the first mold 502 and the second mold 504 so as to
define a
mold space for injection molding or compression molding the lens system 100.
The
mold system 500 may be formed from suitable metals, high-impact-resistant
plastics
or a combination thereof, and can be produced by conventional machining
techniques
such as lathing or milling, or by laser or electrical-discharge machining. The
mold
surfaces can be finished or modified by sand blasting, etching or other
texturing
techniques.
The first mold 502 includes a first mold cavity 508 with a first anterior mold
face 510 surrounded by an annular trough 512 and a first perimeter mold face
514.
The first mold 502 also includes a projection 516 which facilitates easier
mating with
the second mold 504.
The center mold 506 includes a first center mold cavity 518 which cooperates
with the first mold cavity 508 to define a mold space for forming the anterior
portion
102 of the lens system 100. The first center mold cavity 518 includes a
central
anterior mold face 520 which, upon placement of the center mold 506 in the
first mold
cavity 508, cooperates with the first anterior mold face 510 to define a mold
space for
the anterior viewing element 106. In so doing, the first anterior mold face
510 defines
the anterior face of the anterior viewing element 106 and the central anterior
mold
face 520 defines the posterior face of the anterior viewing element 106. In
fluid
communication with the chamber formed by the first anterior mold face 510 and
the
central anterior mold face 520 are lateral channels 522, 524 (best seen in
Figure 31)
which form spaces for molding the first and second transition members 138,
140,
along with the arms 110a, 110b of the first anterior translation member 110 as
well as
the arms 114a, 114b of the second anterior translation member 114. The first
center
mold cavity 518 also includes retention member cavities 526, 528 which define
spaces
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CA 02767318 2012-01-31
for molding the first and second retention members 128, 130 to the anterior
viewing
element 106.
The second mold 504 includes a second mold cavity 530 with a second
posterior mold space 532, a generally cylindrical transition 534 extending
therefrom
and connecting to a second perimeter mold face 536. Lateral notches 538, 540
(best
seen in Figures 26 and 27) are formed in the second perimeter mold face 536.
The
second mold 504 also includes an input channel 542 connected to an input
channel
opening 544 for introducing material into the mold system 500. Also formed in
the
second mold 504 is an output channel 546 and an output channel opening 548. A
generally cylindrical rim 550 is included for mating with the projection 516
of the first
mold 502.
The center mold 506 includes a second center mold cavity 552 which
cooperates with the second mold cavity 530 to define a mold space for the
posterior
portion 104 of the lens system 100. The second center mold cavity 552 includes
a
central posterior mold face 554 which, upon placement of the center mold 506
in
engagement with the second mold cavity 530, cooperates with the second
posterior
mold face 532 and the transition 534 to define a chamber for forming the
posterior
viewing element 118. In fluid communication with the chamber formed by the
central
posterior mold face 554 and the second posterior mold face 532 are lateral
channels
556, 558, 560, 562 which provide a mold space for forming the arms 122a, 122b
of
the first posterior translation member 122 and the arms 124a, 124b of the
second
posterior translation member 124. The second center mold cavity 552 includes
lateral
projections 564, 566 which coact with the notches 538, 540 formed in the
second
mold cavity 530. The chambers formed therebetween are in fluid communication
with the chamber defined by the central posterior mold face 554 and the second
posterior mold face 532 to form the first and second distending members 134,
136
integrally with the posterior viewing element 118.
The center mold 506 includes a first reduced-diameter portion 568 and a
second reduced-diameter portion 570 each of which, upon assembly of the mold
system 500, defines a mold space for the apices 112, 116 of the lens system
100.
In use, the mold system 500 is assembled with the center mold 506 positioned
between the first mold 502 and the second mold 504. Once placed in this
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CA 02767318 2012-01-31
configuration, the mold system 500 is held together under force by appropriate
techniques, and lens material is introduced into the mold system 500 via the
input
channel 542. The lens material then fills the space defined by the first mold
502,
second mold 504, and the center mold 506 to take on the shape of the finished
lens
system 100.
The mold system 500 is then disassembled, and in one embodiment the lens
system 100 is left in position on the center mold 506 after removal of the
first and
second molds 502, 504. This technique has been found to improve the
effectiveness
of any polishing/tumbling/deflashing procedures which may be performed (see
further
discussion below). Whether or not these or any other additional process steps
are
performed, the lens system 100 is preferably removed from the center mold 506
while
maintaining the interconnection of the various components of the lens system
100.
In another embodiment, the lens system 100 or a portion thereof is formed by a
casting or liquid-casting procedure in which one of the first or second molds
is first
filled with a liquid and the center mold is placed then into engagement with
the liquid-
filled mold. The exposed face of the center mold is then filled with liquid
and the
other of the first and second molds is placed into engagement with the rest of
the mold
system. The liquid is allowed or caused to set/cure and a finished casting may
then
removed from the mold system.
The mold system 500 can advantageously be employed to produce a lens
system 100 as a single, integral unit (in other words, as a single piece of
material).
Alternatively, various portions of the lens system 100 can be separately
molded,
casted, machined, etc. and subsequently assembled to create a finished lens
system.
Assembly can be performed as a part of centralized manufacturing operations;
alternatively, a physician can perform some or all of the assembly before or
during the
implantation procedure, to select lens powers, biasing members, system sizes,
etc.
which are appropriate for a particular patient.
The center mold 506 is depicted as comprising an integral unit with first and
second center mold cavities 518, 552. Alternatively, the center mold 506 may
have a
modular configuration whereby the first and second mold cavities 518, 552 may
be
interchangeable to adapt the center mold 506 for manufacturing a lens system
100
according to a desired prescription or specification, or to otherwise change
the
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CA 02767318 2012-01-31
power(s) of the lenses made with the mold. In this manner the manufacture of a
wide
variety of prescriptions may be facilitated by a set of mold cavities which
can be
assembled back-to-back or to opposing sides of a main mold structure.
Figures 49-53 depict one embodiment of a method for manufacturing the
center mold 506. First, a cylindrical blank 1500 formed from any material
(such as
Ultem) suitable for use in the mold tooling, is loaded into a holder 1502 as
shown in
Figure 49. The holder 1502 has a main chamber 1504 which has an inner diameter
substantially similar to that of the blank 1500, a smaller-diameter secondary
chamber
1506 rearward of the main chamber 1504, and a passage 1508 located rearward of
the
secondary chamber 1506 and further defined by an annulus 1510. The holder also
includes two or more holder bores 1512 which facilitate attachment of the
holder 1502
to a blocker (discussed in further detail below). The blank is "blocked" in
the holder
by filling the secondary chamber 1506 and passage 1508 with water-soluble wax
1514.
Once the blank 1500 has been loaded and blocked into the holder 1502, the
holder 1502 is secured to a blocker 1516 by bolts or pins (not shown) which
fit snugly
into the holder bores 1512. The holder bores 1512 align precisely with
corresponding
blocker bores 1517, by virtue of a snug fit between the blocker bores 1517 and
the
bolts/pins. The blocker-holder assembly is then loaded into a conventional
machine
tool, such as a lathe and/or a mill, and one of the first and second center
mold cavities
518, 552 (the second cavity 552 is depicted in Figure 51) is machined from the
exposed face of the blank 1500 using conventional machining techniques. The
holder
1502 and blank 1500, with the second center mold cavity 552 formed thereon,
are
then removed from the blocker 1516 as shown in Figure 51.
The main chamber 1504 is then filled with water-soluble wax 1520 forward of
the second center mold cavity 552, and the wax 1514 is removed from the
secondary
chamber 1506 and the passage 1508. Next the holder 1502 is fixed to the
blocker
1516 with the as-yet unmodified portion of the blank 1500 facing outward. Upon
re-
loading the holder-blocker assembly into the machine tool, a portion of the
annulus
1510 is then cut away to facilitate tool access to the blank 1500. A series of
machining operations are then performed on the blank 1500 until the remaining
mold
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CA 02767318 2012-01-31
cavity (the first center mold cavity 518 is depicted in Figure 53) has been
formed. The
completed center mold 506 may then be removed from the holder 1502.
The machining technique depicted in Figures 49-53 is advantageous in that it
facilitates fabrication of the center mold 506 (with both the first and second
center
mold cavities 518, 552) from a single piece of material. While it is possible
to
machine the first and second center mold cavities 518, 552 from separate
pieces of
material which are subsequently glued together, such assembly creates a seam
in the
center mold which can retain contaminants and introduce those contaminants
into the
mold when forming the lens system 100. In addition, the assembly of the center
mold
506 from two halves introduces errors wherein the first and second center mold
cavities 518, 552 may be angularly shifted with respect to each other about
the optical
axis, or wherein the mold cavities 518, 552 are non-concentric (i.e., shifted
with
respect to each other in a direction orthogonal to the optical axis). The
method
depicted in Figures 49-53 eliminates these problems by retaining the blank
1500 in the
holder 1502 throughout the fabrication process and by enforcing precise axial
alignment, via forced alignment of the bores 1512 with the blocker bores 1517,
when
machining of both mold cavities.
In another embodiment, the center mold 506 is formed by a molding process
rather than by machining. The center mold 506 may be molded from any of the
materials disclosed herein as suitable for forming the lens system 100 itself,
including
but not limited to silicone, acrylics, polymethylmethacrylate (PMMA), block
copolymers of styrene-ethylene-butylene-styrene (C-FLEX) or other styrene-base
copolymers, polyvinyl alcohol (PVA), polyurethanes, hydrogels or any other
moldable
polymers or monomers. .
The lens system which is formed when employing the molded center mold 506
may itself be molded from the same material as the center mold 506. For
example,
the center mold 506 may be molded from silicone, and then the lens system 100
may
be molded from silicone by using the mold system 500 with the molded silicone
center mold 506.
The center mold 506 can be molded by any suitable conventional techniques.
A polished, optical quality initial mold set can be used to make center molds
which in
turn will produce lens systems with optical quality surfaces on the posterior
face of the
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anterior optic, and the anterior face of the posterior optic. Alternatively
(or
additionally), the molded center mold can be polished and/or tumbled to
produce an
optically-accurate center mold.
The molded center mold 506 offers several advantages over a machined center
mold. First, it is quicker, cheaper and easier to produce the center mold in
large
quantities by molding instead of machining. This in turn facilitates leaving
the lens
system in position on the center mold (see Figure 54) while the lens system is
tumbled, polished and/or deflashed, without incurring undue expense. The
presence
of the center mold between the optics increases the effectiveness of the
tumbling/polishing/deflashing by increasing the hoop strength of the lens
system, so
that the energy of the impacting tumbling beads is not dissipated in
macroscopic
deformation of the lens system. Molding
also permits softer materials to be
employed in forming the center mold, and a softer center mold is more
resistant to
damage from deflashing tools and processes, resulting in fewer center molds
lost to
such process-related damage.
VII. MATERIALS/SURFACE TREATMENTS
Preferred materials for forming the lens system 100 include silicone,
acrylics,
polymethylmethacrylate (PMMA), block copolymers of styrene-ethylene-butylene-
styrene (C-FLEX) or other styrene-base copolymers, polyvinyl alcohol (PVA),
polyurethanes, hydrogels or any other suitable polymers or monomers. In
addition,
any portion of the lens system 100 other than the optic(s) may be formed from
stainless steel or a shape-memory alloy such as nitinol or any iron-based
shape-
memory alloy. Metallic components may be coated with gold to increase
biocompatibility. Where feasible, material of a lower Shore A hardness such as
15A
may be used for the optic(s), and material of higher hardness such as 35A may
be used
for the balance of the lens system 100. Finally, the optic(s) may be formed
from a
photosensitive silicone to facilitate post-implantation power adjustment as
taught in
United States Patent No. 6,450,642, issued September 17, 2002, titled LENSES
CAPABLE OF POST-FABRICATION POWER MODIFICATION.
Methyl-methylacrylate monomers may also be blended with any of the non-
metallic materials discussed above, to increase the lubricity of the resulting
lens
system (making the lens system easier to fold or roll for insertion, as
discussed further
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CA 02767318 2012-01-31
below). The addition of methyl-methylacrylate monomers also increases the
strength
and transparency of the lens system.
The optics and/or the balance of the lens system 100 can also be formed from
layers of differing materials. The layers may be arranged in a simple sandwich
fashion, or concentrically. ln addition, the layers may include a series of
polymer
layers, a mix of polymer and metallic layers, or a mix of polymer and monomer
layers.
In particular, a nitinol ribbon core with a surrounding silicone jacket may be
used for
any portion of the lens system 100 except for the optics; an acrylic-over-
silicone
laminate may be employed for the optics. A layered construction may be
obtained by
pressing/bonding two or more layers together, or deposition or coating
processes may
be employed.
Where desired, the anterior optic may be formed from a material different
from that used to form the posterior optic. This may be done to take advantage
of
differences between the respective materials in refractive index, mechanical
properties
or resistance to posterior capsule pacification ("PCO"), or to achieve an
appropriate
balance of mechanical and optical properties. Additionally, the use of
differing
materials can increase resistance to intra-lenticular pacification ("ILO").
For
example, the material forming the posterior optic may be selected for its
resistance to
PCO, and/or for its rigidity (so as to form a relatively rigid base for the
biasing action
of the biasing elements 108, 120, thereby maximizing anterior displacement of
the
anterior biasing element). Thus, the posterior optic may be formed from
acrylic; for
example, a hydrophobic acrylic. The material forming the anterior optic may be
selected for its high index of refraction, to keep to a minimum the size and
weight of
the anterior optic (and the lens system as a whole), thereby maximizing the
range and
speed of motion of the anterior optic in response to a given biasing force. To
achieve
these properties the anterior optic may be formed from silicone; for example,
high-
refractive-index silicones (generally, silicones with a refractive index
greater than
about 1.43, or silicones with a refractive index of about 1.46).
In other embodiments, the anterior optic may be formed from any suitable
material (including those disclosed herein), and the posterior optic may be
formed
from any suitable material (including those disclosed herein) other than the
material
chosen to form the anterior optic. In one embodiment the anterior optic is
formed
from silicone and the posterior optic is formed from acrylic; in another
embodiment
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the anterior optic is formed from acrylic and the posterior optic is formed
from
silicone.
The optics may be considered to be formed from different polymeric materials
where no more than about 10 mole percent of recurring units of the polymer
employed
in the anterior optic are the same as the primary recurring units of the
polymer
employed in the posterior optic; and/or where no more than about 10 mole
percent of
recurring units of the polymer employed in the posterior optic are the same as
the
primary recurring units of the polymer employed in the anterior optic. In
general,
these conditions are desirable in order for the two materials to have
sufficiently
different material properties. As used herein, a "primary" recurring unit of a
given
polymer is the recurring unit which is present in such polymer in the greatest
quantity
by mole percentage.
In another embodiment, the optics may be considered to be formed from
different polymeric materials where no more than about 10 mole percent of
recurring
units of the polymer employed in the anterior optic are of the =same type as
the primary
recurring units of the polymer employed in the posterior optic; and/or where
no more
than about 10 mole percent of the recurring units of the polymer employed in
the
posterior optic are of the same type as the primary recurring units of the
polymer
employed in the anterior optic. As used herein, recurring units of the same
"type" are
in the same chemical family (i.e., having the same or similar functionality)
or where
the backbone of the polymers formed by such recurring units is essentially the
same.
In one embodiment, portions of the lens system 100 other than the optic(s) are
formed from a shape-memory alloy. This embodiment takes advantage of the
exceptional mechanical properties of shape-memory alloys and provides fast,
consistent, highly responsive movement of the optic(s) within the capsular bag
while
minimizing material fatigue in the lens system 100. In one embodiment, one or
both
of the biasing elements 108, 120 are formed from a shape-memory alloy such as
nitinol or any iron-based shape-memory alloy. Due to the flat stress-strain
curve of
nitinol, such biasing elements provide a highly consistent accommodation force
over a
wide range of displacement. Furthermore, biasing elements formed from a shape-
memory alloy, especially nitinol, retain their spring properties when exposed
to heat
(as occurs upon implantation into a human eye) while polymeric biasing
elements tend
to lose their spring properties, thus detracting from the responsiveness of
the lens
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CA 02767318 2012-01-31
system. For similar reasons, it is advantageous to use shape-memory alloys
such as
those discussed above in forming any portion of a conventional (non-
accommodating)
intraocular lens, other than the optic.
Where desired, various coatings are suitable for components of the lens system
100. A heparin coating may be applied to appropriate locations on the lens
system
100 to prevent inflammatory cell attachment (ICA) and/or posterior capsule
opacification (PC0); naturally, possible locations for such a coating include
the
posterior biasing element 120 and the posterior face of the posterior viewing
element
118. Coatings can also be applied to the lens system 100 to improve
biocompatibility;
such coatings include "active" coatings like P-15 peptides or RGD peptides,
and
"passive" coatings such as heparin and other mucopolysaccharides, collagen,
fibronectin and laminin. Other coatings, including hirudin, teflon, teflon-
like
coatings, PVDF, fluorinated polymers, and other coatings which are inert
relative to
the capsular bag may be employed to increase lubricity at locations (such as
the optics
and distending members) on the lens system which contact the bag, or Hema or
silicone can be used to impart hydrophilic or hydrophobic properties to the
lens
system 100.
It is also desirable subject the lens system 100 and/or the mold surfaces to a
surface passivation process to improve biocompatibility. This may be done via
conventional techniques such as chemical etching or plasma treatment.
Furthermore, appropriate surfaces (such as the outer edges/surfaces of the
viewing elements, biasing elements, distending members, retention members,
etc.) of
the lens system 100 can be textured or roughened to improve adhesion to the
capsular
bag. This may be accomplished by using conventional procedures such as plasma
treatment, etching, dipping, vapor deposition, mold surface modification, etc.
As a
fiirther means of preventing ICA/PCO, a posteriorly-extending perimeter wall
(not
shown) may be added to the posterior viewing element 118 so as to surround the
posterior face of the posterior optic. The wall firmly engages the posterior
aspect of
the capsular bag and acts as a physical barrier to the progress of cellular
ingrowth
occurring on the interior surface of the capsular bag. Finally, the relatively
thick
cross-section of the preferred anterior viewing element 118 (see Figures 9,
10) ensures
that it will firmly abut the posterior capsule with no localized flexing.
Thus, with its
relatively sharp rim, the posterior face of the preferred posterior viewing
element 118
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CA 02767318 2012-01-31
can itself serve as a barrier to cellular ingrowth and ICA/PCO. In order to
achieve this
effect, the posterior viewing element 118 is preferably made thicker than
conventional
intraocular lenses. As an alternative or supplement to a thick posterior
viewing
element, cell growth may be inhibited by forming a pronounced, posteriorly-
extending
perimeter rim on the posterior face of the posterior viewing element 118. Upon
implantation of the lens system 100, the rim firmly abuts the inner surface of
the
capsular bag 58 and acts as a physical barrier to cell growth between the
posterior face
of the posterior viewing element 118 and the capsular bag 58.
The selected material and lens configuration should be able to withstand
secondary operations after molding/casting such as polishing, cleaning and
sterilization processes involving the use of an autoclave, or ethylene oxide
or
radiation. After the mold is opened, the lens should undergo deflashing,
polishing and
cleaning operations, which typically involve a chemical or mechanical process,
or a
combination thereof. Suitable mechanical processes include tumbling, shaking
and
vibration; a tumbling process may involve the use of a barrel with varying
grades of
glass beads, fluids such as alcohol or water and polishing compounds such as
aluminum oxides. Process rates are material dependent; for example, a tumbling
process for silicone should utilize a 6" diameter barrel moving at 30-100 RPM.
It is
contemplated that several different steps of polishing and cleaning may be
employed
before the final surface quality is achieved.
In one embodiment, the lens system 100 is held in a fixture to provide
increased separation between, and improved process effect on, the anterior and
posterior viewing elements during the deflashing/polishing/cleaning
operations. In
another embodiment, the lens system 100 is everted or turned "inside-out" so
that the
inner faces of the viewing elements are better exposed during a portion of the
deflashing/polishing/cleaning. Figure 34A shows a number of expansion grooves
192
which may be formed in the underside of the apices 112, 116 of the lens system
100 to
facilitate eversion of the lens system 100 without damaging or tearing the
apices or the
anterior/posterior biasing elements 108, 120. For the same reasons similar
expansion
grooves may be formed on the opposite sides (i.e., the outer surfaces) of the
apices
112, 116 instead of or in addition to the location of grooves on the
underside.
A curing process may also be desirable in manufacturing the lens system 100.
If the lens system is produced from silicone entirely at room temperature, the
curing
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time can be as long as several days. If the mold is maintained at about 50
degrees C,
the curing time is reduced to about 24 hours; if the mold is preheated to 100-
200
degrees C the curing time can be as short as about 3-15 minutes. Of course,
the time-
temperature combinations vary for other materials.
VIII. MULTIPLE-PIECE AND OTHER EMBODIMENTS
Figure 35 is a schematic view of a two-piece embodiment 600 of the lens
system. In this embodiment the anterior portion 102 and the posterior portion
104 are
formed as separate pieces which are intended for separate insertion into the
capsular
bag and subsequent assembly therein. In one embodiment, each of the anterior
and
posterior portions 102, 104 is rolled or folded before insertion into the
capsular bag.
(The insertion procedure is discussed in further detail below.) The anterior
portion
102 and posterior portion 104 are represented schematically as they may
generally
comprise any anterior-portion or posterior-portion structure disclosed herein;
for
example, they may simply comprise the lens system 100 shown in Figures 3-17,
bisected along the line/plane A-A shown in Figure 4. The anterior portion 102
and
posterior portion 104 of the two-piece lens system 600 will include first and
second
abutments 602, 604 which are intended to be placed in abutting relation (thus
forming
the first and second apices of the lens system) during the assembly procedure.
The
first and second abutments 602, 604 may include engagement members (not
shown),
such as matching projections and recesses, to facilitate alignment and
assembly of the
anterior and posterior portions 102, 104.
As a further alternative, the anterior and posterior portions 102, 104 of the
lens
system 600 may be hingedly connected at one of the abutments 602, 604 and
unconnected at the other, to allow sequential (but nonetheless partially
assembled)
insertion of the portions 102, 104 into the capsular bag. The individual
portions may
be separately rolled or folded before insertion. The two portions 102, 104 are
"swung" together and joined at the unconnected abutment to form the finished
lens
system after both portions have been inserted and allowed to unfold/unroll as
needed.
Figure 36 depicts schematically another embodiment 700 of a two-piece lens
system. The lens system 700 is desirably similar to the lens system 600 shown
in
Figure 35, except for the formation of relatively larger, curled abutments
702, 704
which are assembled to form the apices 112, 116 of the system 700.
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Figures 37 and 38 show a further embodiment 800 of the lens system, in which
the anterior and posterior biasing elements 108, 120 comprise integral "band"
like
members forming, respectively, the first and second anterior translation
members 110,
114 and the first and second posterior translation members 122, 124. The
biasing
elements 108, 120 also form reduced-width portions 802, 804 which meet at the
apices of the lens system 800 and provide regions of high flexibility to
facilitate
sufficient accommodative movement. The depicted distending portion 132
includes
three pairs of distending members 134, 136 which have a curved configuration
but
nonetheless project generally away from the optical axis.
Figures 38A and 38B depict another embodiment 900 of the lens system, as
implanted in the capsular bag 58. The embodiment shown in Figures 38A and 38B
may be similar to any of the embodiments described above, except that the
biasing
elements 108, 120 are dimensioned so that the apices 112, 116 abut the zonules
62
and ciliary muscles 60 when in the unaccommodated state as seen in Figure 38A.
In
addition, the lens system 900 is configured such that it will remain in the
unaccommodated state in the absence of external forces. Thus, when the ciliary
muscles 60 contract, the muscles 60 push the apices 112, 116 closer together,
causing
the biasing elements 108, 120 to bow out and the viewing elements 106, 118 to
separate and attain the accommodated state as shown in Figure 38B. When the
ciliary
muscles 60 relax and reduce/eliminate the force applied to the apices 112, 116
the
biasing elements 108, 120 move the lens system 900 to the unaccommodated state
depicted in Figure 38A.
Figures 38C and 38D depict biasers 1000 which may be used bias the lens
system 100 toward the accommodated or unaccommodated state, depending on the
desired operating characteristics of the lens system. It is therefore
contemplated that
the biasers 1000 may be used with any of the embodiments of the lens system
100
disclosed herein. The bias provided by the biasers 1000 may be employed
instead of,
or in addition to, any bias generated by the biasing elements 108, 120. In one
embodiment (see Figure 38C), the biasers 1000 may comprise U-shaped spring
members having apices 1002 located adjacent the apices 112, 116 of the lens
system
100. In another embodiment (see Figure 38D), the biasers 1000 may comprise any
suitable longitudinal-compression springs which span the apices 112, 116 and
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interconnect the anterior and posterior biasing elements 108, 120. By
appropriately
selecting the spring constants and dimensions of the biasers 1000 (in the case
of U-
shaped springs, the apex angle and arm length; in the case of longitudinal-
compression springs, their overall length), the biasers 1000 can impart to the
lens
system 100 a bias toward the accommodated or unaccommodated state as desired.
The biasers 1000 may be formed from any of the materials disclosed herein as
suitable for constructing the lens system 100 itself. The material(s) selected
for the
biasers 1000 may be the same as, or different from, the material(s) which are
used to
form the remainder of the particular lens system 100 to which the biasers 1000
are
connected. The number of biasers 1000 used in a particular lens system 100 may
be
equal to or less than the number of apices formed by the biasing elements of
the lens
system 100.
Figure 38E depicts a further embodiment of the lens system 100 in which the
anterior translation members 110 and the posterior translation members 120 are
paired
in a number (in the example depicted, four) of separate positioners 1400 which
are
radially spaced, preferably equally radially spaced, about the optical axis.
In the
depicted embodiment, the anterior and posterior translation members 110, 120
connect directly to the periphery of the viewing elements 106, 118; however,
in other
embodiments any of the connection techniques disclosed herein may be employed.
As
shown, the anterior translation members 100 preferably extend anteriorly from
the
periphery of the anterior viewing element before bending and extending
posteriorly
toward the apex/apices 112. As discussed above, this configuration is
advantageous
for promotion of fluid flow through an opening formed in the anterior aspect
of the
capsular bag 58. It has been found that the lens configuration shown in Figure
38E is
well suited for the folding technique shown in Figures 40A and 40B below. In
additional embodiments, the lens system 100 shown in Figure 38E may
incorporate
any other suitable features of the other embodiments of the lens system 100
disclosed
herein, such as but not limited to the distending members and/or retention
members
detailed above.
IX. IMPLANTATION METHODS
Various techniques may be employed in implanting the various embodiments
of the lens system in the eye of a patient. The physician can first access the
anterior
aspect of the capsular bag 58 via any appropriate technique. Next, the
physician
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incises the anterior of the bag; this may involve making the circular opening
66 shown
in Figures 21 and 22, or the physician may make a "dumbbell" shaped incision
by
forming two small circular incisions or openings and connecting them with a
third,
straight-line incision. The natural lens is then removed from the capsular bag
via any
of various known techniques, such as phacoemulsification, cryogenic and/or
radiative
methods. To inhibit further cell growth, it is desirable to remove or kill all
remaining
epithelial cells. This can be achieved via cryogenic and/or radiative
techniques,
antimetabolites, chemical and osmotic agents. It is also possible to
administer agents
such as P15 to limit cell growth by sequestering the cells.
In the next step, the physician implants the lens system into the capsular
bag.
Where the lens system comprises separate anterior and posterior portions, the
physician first folds or rolls the posterior portion and places it in the
capsular bag
through the anterior opening. After allowing the posterior portion to
unroll/unfold,
the physician adjusts the positioning of the posterior portion until it is
within
satisfactory limits. Next the physician rolls/folds and implants the anterior
portion in
a similar manner, and aligns and assembles the anterior portion to the
posterior
portion as needed, by causing engagement of mating portions, etc. formed on
the
anterior and posterior portions.
Where the lens system comprises anterior and posterior portions which are
partially assembled or partially integral (see discussion above in the section
titled
MULTIPLE-PIECE AND OTHER EMBODIMENTS), the physician employs
appropriate implantation procedures, subsequently folding/rolling and
inserting those
portions of the lens system that are separately foldable/rollable. In one
embodiment,
the physician first rolls/folds one portion of the partially assembled lens
system and
then inserts that portion. The physician then rolls/folds another portion of
the partially
assembled lens system and the inserts that portion. This is repeated until the
entire
system is inside the capsular bag, whereupon the physician completes the
assembly of
the portions and aligns the lens system as needed. In another embodiment, the
physician first rolls/folds all of the separately rollable/foldable portions
of the partially
assembled lens system and then inserts the rolled/folded system into the
capsular bag.
Once the lens system is in the capsular bag, the physician completes the
assembly of
the portions and aligns the lens system as needed.
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CA 02767318 2012-01-31
It is contemplated that conventional intraocular lens folding devices,
injectors,
syringes and/or shooters can be used to insert any of the lens systems
disclosed herein.
A preferred folding/rolling technique is depicted in Figures 39A-39B, where
the lens
system 100 is shown first in its normal condition (A). The anterior and
posterior
viewing elements 106, 118 are manipulated to place the lens system 100 in a
low-
profile condition (B), in which the viewing elements 106, 118 are out of axial
alignment and are preferably situated so that no portion of the anterior
viewing
element 106 overlaps any portion of the posterior viewing element 118, as
viewed
along the optical axis. In the low-profile position (B), the thickness of the
lens system
100 is minimized because the viewing elements 106, 118 are not "stacked" on
top of
each other, but instead have a side-by-side configuration. From the low-
profile
condition (B) the viewing elements 106, 118 and/or other portions of the lens
system
100 can be folded or rolled generally about the transverse axis, or an axis
parallel
thereto. Alternatively, the lens system could be folded or rolled about the
lateral axis
or an axis parallel thereto. Upon folding/rolling, the lens system 100 is
placed in a
standard insertion tool as discussed above and is inserted into the eye.
When the lens system 100 is in the low-profile condition (B), the system may
be temporarily held in that condition by the use of dissolvable sutures, or a
simple clip
which is detachable or manufactured from a dissolvable material. The sutures
or clip
hold the lens system in the low-profile condition during insertion and for a
desired
time after insertion. By temporarily holding the lens system in the low-
profile
condition after insertion, the sutures or clip provide time for fibrin
formation on the
edges of the lens system which, after the lens system departs from the low-
profile
condition, may advantageously bind the lens system to the inner surface of the
capsular bag.
The physician next performs any adjustment steps which are facilitated by the
particular lens system being implanted. Where the lens system is configured to
receive the optic(s) in "open" frame members, the physician first
observes/measures/determines the post-implantation shape taken on by the
capsular
bag and lens system in the accommodated and/or unaccommodated states and
select(s)
the optics which will provide the proper lens-system performance in light of
the
observed shape characteristics and/or available information on the patient's
optical
disorder. The physician then installs the optic(s) in the respective frame
member(s);
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the installation takes place either in the capsular bag itself or upon
temporary removal
of the needed portion(s) of the lens system from the bag. If any portion is
removed, a
final installation and assembly is then performed with the optic(s) in place
in the
frame member(s).
Where the optic(s) is/are formed from an appropriate photosensitive silicone
as
discussed above, the physician illuminates the optic(s) (either anterior or
posterior or
both) with an energy source such as a laser until they attain the needed
physical
dimensions or refractive index. The physician may perform an intervening step
of
observing/measuring/determining the post-implantation shape taken on by the
capsular bag and lens system in the accommodated and/or unaccommodated states,
before determining any needed changes in the physical dimensions or refractive
index
of the optic(s) in question.
Figure 40 depicts a technique which may be employed during lens
implantation to create a fluid flow path between the interior of the capsular
bag 58 and
the region of the eye anterior of the capsular bag 58. The physician forms a
number of
fluid-flow openings 68 in the anterior aspect of the capsular bag 58, at any
desired
location around the anterior opening 66. The fluid-flow openings 68 ensure
that the
desired flow path exists, even if a seal is created between the anterior
opening 66 and
a viewing element of the lens system.
Where an accommodating lens system is implanted, the openings 68 create a
fluid flow path from the region between the viewing elements of the implanted
lens
system, and the region of the eye anterior of the capsular bag 58. However,
the
technique is equally useful for use with conventional (non-accommodating)
intraocular lenses.
Figures 40A and 40B illustrate another embodiment of a method of folding the
lens system 100. In this method the anterior viewing element 106 is rotated
approximately 90 degrees about the optical axis with respect to the posterior
viewing
element 118. This rotation may be accomplished by applying rotational force to
the
upper edge of the first transition member 138 and the lower edge of the second
transition member 140 (or vice versa), as indicated by the dots and arrows in
Figure
40A, while holding the posterior viewing element 118 stationary, preferably by
gripping or clamping the distending members 134, 136. Alternatively,
rotational force
may be applied in a similar manner to a right edge of one of the retention
members
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CA 02767318 2012-01-31
128, 130 and to a left edge of the other of the retention members while
holding the
posterior viewing element 118 stationary. As still further alternatives, the
anterior
viewing element 106 could be held stationary while rotational force is applied
to the
posterior viewing element 118, at an upper edge of one of the distending
members
134, 136 and at a lower edge of the other of the distending members; or both
the
anterior and posterior viewing elements 106, 118 could be rotated with respect
to each
other.
Preferably, the viewing elements 106, 118 are spread apart somewhat as the
rotation is applied to the lens system so that the translation members and
apices are
drawn into the space between the viewing elements 106, 118 in response to the
rotational force. Once the anterior viewing element 106 has been rotated
approximately 90 degrees about the optical axis with respect to the posterior
viewing
element 118, the lens system 100 takes on the configuration shown in Figure
40B,
with the retention members 128, 130 generally radially aligned with the
distending
members 134, 136 and the translation members and apices disposed between the
viewing elements 106, 118. This configuration is advantageous for inserting
the lens
system 100 into the capsular bag 58 because it reduces the insertion profile
of the lens
system 100 while storing a large amount of potential energy in the translation
members. From the folded configuration the translation members thus exert a
high
"rebound" force when the lens system has been inserted to the capsular bag 58,
causing the lens system to overcome any self-adhesion and spring back to the
unfolded configuration shown in Figure 40A without need for additional
manipulation
by the physician.
Once the lens system 100 is in the folded configuration shown in Figure 40B,
it may be further folded and/or inserted into the capsular bag 58 by any
suitable
methods presently known in the art or hereafter developed. For example, as
shown in
Figure 40C the folding method may further comprise inserting the folded lens
system
100 between the prongs 1202, 1204 of a clip 1200, preferably with the prongs
1202,
1204 oriented to extend along the transition members 138, 140, or along the
retention
members 128, 130 and the distending members 134, 136.
Figures 40D - 40F illustrate the use of jaws 1250, 1252 of a pliers or forceps
to
fold the lens system 100 as it is held in the clip 1200. (Figures 40D - 40F
show an end
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view of the clip-lens system assembly with the jaws 1250, 1252 shown in
section for
clarity.) As shown in Figures 40D and 40E, the edges of the jaws 1250, 1252
are
urged against one of the anterior and posterior viewing elements 106, 118
while the
jaws 1250, 1252 straddle the prong 1202 of the clip 1200. The resulting three-
point
load on the lens system 1200 causes it to fold in half as shown in Figure 40E.
As the
lens system 100 approaches the folded configuration shown in Figure 40F, the
jaws
1250, 1252 slide into a pincer orientation with respect to the lens system
100,
characterized by contact between the inner faces 1254, 1256 of the jaws 1250,
1252
and the anterior viewing element 106 or posterior viewing element 118. With
such a
pincer orientation established, the forceps may be used to grip and compress
the lens
system with inward-directed pressure and the clip 1200 can be withdrawn, as
shown
in Figure 40F. With the lens system 100 thus folded, it can be inserted to the
capsular
bag 58 by any suitable method presently known in the art or hereafter
developed.
Figure 40G depicts a folding tool 1300 which may be employed to fold the
lens system 100 as discussed above in connection with Figures 40A and 40B. The
tool 1300 includes a base 1302 with brackets 1304 which hold the lens system
100 to
the base 1302 by gripping the distending members 134, 136. Formed within the
base
1302 are arcuate guides 1306. The tool further comprises a rotor 1308 which in
turn
comprises a horizontal rod 1310 and integrally formed vertical rods 1312. The
vertical rods 1312 engage the arcuate guides 1306, both of which have a
geometric
center on the optical axis of the lens system 100. The vertical rods 1312 and
the
arcuate guides 1306 thus coact to allow the horizontal rod to rotate at least
90 degrees
about the optical axis of the lens system 100. The horizontal rod 1310 is
fixed with
respect to the anterior viewing element 106 of the lens system 100 so as to
prevent
substantially no relative angular movement between the rod 1310 and the
anterior
viewing element 106 as the rod 1310 (and, in turn, the anterior viewing
element 106)
rotates about the optical axis of the lens system 100. This fixed relationship
may be
established by adhesives and/or projections (not shown) which extend downward
from
the horizontal rod 1308 and bear against the upper edge of one of the
transition
members 138, 140 and against the lower edge of the other of the transition
members
as shown in Figure 40A. As an alternative or as a supplement to this
arrangement, the
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projections may bear against the retention members 128, 130 in a similar
manner as
discussed above.
Thus, when the rotor 1308 is advanced through its range of angular motion
about the optical axis of the lens system 100, it forces the anterior viewing
element
106 to rotate in concert therewith about the optical axis, folding the lens
system as
discussed above in connection with Figures 40A and 40B. It is further
contemplated
that the folding tool 1300 may comprise the lower half of a package in which
the lens
system is stored and/or shipped to a customer, to minimize the labor involved
in
folding the lens system at the point of use. Preferably, the lens system is
stored in the
tool 1300 in the unfolded configuration, so as to avoid undesirable
deformation of the
lens system.
X. THIN OPTIC CONFIGURATIONS
In some circumstances it is advantageous to make one or more of the optics of
the lens system relatively thin, in order to facilitate rolling or folding, or
to reduce the
overall size or mass of the lens system. Discussed below are various optic
configurations which facilitate a thinner profile for the optic; any one of
these
configurations may be employed as well as any suitable combination of two or
more
of the disclosed configurations.
One suitable technique is to employ a material having a relatively high index
of refraction to construct one or more of the optics. In one embodiment, the
optic
material has an index of refraction higher than that of silicone. In another
embodiment, the material has an index of refraction higher than about 1.43. In
further
embodiments, the optic material has an index of refraction of about 1.46, 1.49
or 1.55.
In still further embodiments, the optic material has an index of refraction of
about
1.43 to 1.55. By employing a material with a relatively high index of
refraction, the
curvature of the optic can be reduced (in other words, the radius/radii of
curvature can
be increased) thereby reducing the thickness of the optic without loss of
focal power.
A thinner optic can also be facilitated by forming one or more of the surfaces
of one or more of the optics as an aspheric surface, while maintaining the
focal power
of the optic. As shown in Figure 41, an aspheric, convex optic surface 1100
can be
formed with the same radius of curvature (as a comparable-power spherical
surface) at
the vertex 1102 of the surface 1100 and a longer radius of curvature (with a
common
center point) at its periphery 1104, creating a thinner optic without
sacrificing focal
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CA 02767318 2012-01-31
power. This contrasts with a spherical optic surface 1106, which is thicker at
its
vertex 1108 than is the aspheric surface 1102. In one embodiment, the
thickness of
the optic is reduced by about 19% at the vertex relative to a comparable-power
spherical optic. It is contemplated that thinner, aspheric concave optic
surfaces may
be used as well. A further advantage of an aspheric optic surface is that it
provides
better image quality with fewer aberrations, and facilitates a thinner optic,
than a
comparable spherical surface.
Figure 42 depicts a further strategy for providing a thinner optic 1150. The
optic 1150 has a curved (spherical or aspheric) optic surface 1152 and a flat
or planar
(or otherwise less curved than a comparable refractive surface) diffractive
optic
surface 1154 in place of a second curved surface 1156. The diffractive optic
surface
1154 can comprise any suitable diffraction grating, including the grooved
surface
depicted or any other diffractive surface presently known or hereafter
developed,
including holographic optical elements. By appropriately configuring the
diffractive
surface 1154 as is well known in the art, the optic 1150 can be made thinner
than one
having both curved surfaces 1152, 1154, while providing the same focal power.
The
use of the diffractive surface 1154 not only facilitates a thinner optic, but
also reduces
aberrations in the resulting image.
A further alternative for facilitating a thin, easy-to-fold optic is to
employ, in
place of a biconvex optic of refractive index greater than aqueous humor
(i.e., greater
than about 1.336), a biconcave optic of refractive index less than about
1.336, which
is thinner at the optical axis than the biconvex optic. By constructing the
biconcave
optic of material having a refractive index less than about 1.336, the
biconcave optic
can be made to have the same effective focal power, when immersed in aqueous
humor, as a given biconvex optic.
Still another alternative thin optic, shown in Figure 43, is a biconcave optic
1160 of low refractive index (for example, about 1.40 or less or about 1.336
or less)
which is clad with first and second cladding portions 1162, 1164 constructed
of
higher-index material (for example, about 1.43 or greater). Such an optic can
be made
to have the same effective focal power, when immersed in aqueous humor, as a
thicker biconvex optic.
As a further alternative, one or more of the surfaces of the optics may be
formed as a multifocal surface, with spherical and/or aspheric focal regions.
A
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CA 02767318 2012-01-31
multifocal surface can be made with less curvature than a comparable-power
single-
focus surface and thus allows the optic to be made thinner. The additional
foci provide
added power which replaces or exceeds the power that is "lost" when the
surface is
reduced in curvature. In one embodiment, the multifocal optic is constructed
as a
concentric-ring, refractive optic. In another embodiment, the multifocal optic
is
implemented as a diffractive multifocal optic.
Although this invention has been disclosed in the context of certain preferred
embodiments and examples, it will be understood by those skilled in the art
that the
present invention extends beyond the specifically disclosed embodiments to
other
alternative embodiments and/or uses of the invention and obvious modifications
and
equivalents thereof. Thus, it is intended that the scope of the present
invention herein
disclosed should not be limited by the particular disclosed embodiments
described
above, but should be determined only by a fair reading of the claims that
follow.
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