Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEMS FOR OCULAR MEASUREMENTS
Related Application
The present application claims priority under 35 U.S.C 119(e) to provisional
application No. 61/040,638, filed on March 28, 2008 and to United States
patent
application no. 11/739,392, filed April 24, 2007, the entire contents of each
of which
applications are hereby incorporated by reference in their entirety for all
purposes as if
fully set forth herein.
Background of the Invention
Field of the Invention
[0001] The present invention relates generally to devices, systems, and
methods
for making and using ocular measurements, more particular for making and using
ocular
measurements of a cavity size within an eye such as the capsular bag of a
human eye.
Description of the Related Art
[0002] A great deal of effort has been devoted to developing an accommodating
intraocular lens, which can adjust its power over a particular range to
clearly view both
near and far objects. The accommodating intraocular lens is generally inserted
into a
capsular bag, a transparent structure of an eye that houses the natural lens
and generally
remains in the eye after the natural lens has been surgically removed.
[0003] The accommodating intraocular lens changes its power and/or axial
location in response to a squeezing and/or expanding force applied to the lens
by the
capsular bag via the ciliary muscle.
[0004] It is generally important to know the size (or more precisely, the
inner
diameter or circumference) of the capsular bag for each patient's eye prior to
insertion of
an intraocular lens. The capsular bag size may vary patient-to-patient or eye-
to-eye of
the same patient, and if the bag is larger or smaller than expected, the lens
may end up
slightly expanded or squeezed upon implantation. This, in turn, may result in
a shift in
the nominal base power and/or a reduction in the accommodation range.
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[0005] Although the capsular bag diameter is a desirable and useful quantity,
it is
also quite difficult to measure accurately. There have been various attempts
to measure
the capsular bag size with ultrasound. While ultrasound may be useful for
determining
the central thickness of the natural crystalline lens, it is not generally
versatile enough to
image the entire lens, and cannot reliably read out to the perimeter of the
lens.
[0006] There have also been attempts to measure the capsular bag by inserting
a
capsular tension ring (CTR) into the eye. See, for instance, K. STRENN, R.
MENAPACE, and C. VASS, "Capsular bag shrinkage after implantation of an open-
loop
silicone lens and a poly(methyl methacrylate) capsule tension ring," J
Cataract Refract
Surg, 1997, pp. 1543-1547, Vol. 23, which is hereby incorporated by reference
in its
entirety. In this reference, a CTR indicates the capsular diameter, based on
linear
measurement of a peripheral gap. After the measurement, the CTR is generally
not
removed from the eye and remains resident in the eye, which may be
undesirable.
[0007] There have been attempts to correlate capsular bag size with other eye
properties that can be measured more easily. See, for instance, C. VASS, R.
MENAPACE, K. SCHMETTERER, O. FINDL, G. RAINER AND I. STEINECK,
"Prediction of pseudophakic capsular bag diameter based on biometric
variables," J
Cataract Refract Surg, October 1999, pp. 1376-1381, Vol. 25, which is hereby
incorporated by reference in its entirety. In this reference, measurements of
capsular bag
diameter were taken on a sample of patients, using the CTR noted above. In
addition,
measurements of corneal power and axial length were taken on the same
patients, using
known methods. A regression analysis of the measurements produced a
statistically
significant correlation between capsular bag diameter and corneal power and
axial length,
but not with a sufficient accuracy for predicting the required size of an
accommodating
intraocular lens.
[0008] There have also been attempts to convert the capsular bag circumference
dimension to a linear dimension, then to measure the linear dimension with a
camera or
visually. See, for instance, M. TEHRANI, H. B. DICK, F. KRUMMENAUER, G.
PFIRRMANN, T. BOYLE and B. STOFFELNS, "Capsule measuring ring to predict
capsular bag diameter and follow its course after foldable intraocular lens
implantation,"
J Cataract Refract Surg, November 2003, pp. 2127-2134, Vol. 29, which is
hereby
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incorporated by reference in its entirety. In this reference, a Koch capsule
measuring ring
is inserted into the eye. The ring is an incomplete circle, with appendices on
each end, so
that when the ring is inserted into the capsular bag, the separation between
the appendices
is related to the capsular bag circumference. The ring is left in the eye
after the
measurement is taken, which may be undesirable.
[0009] In addition, for the above reference, the measurement of the appendix
separation may be disadvantageous for two reasons. First, the measurement is
taken at
the peripheral edge of the eye, which is a difficult region for eye
measurements. For
instance, the region to be measured might be outside the area of the pupil,
and might
require the use of a slit lamp, or unusual and undesirable handling of the
pupil. Second, it
is generally difficult to measure a linear dimension in the eye. Often, such a
measurement is taken through the cornea, which can magnify the linear
dimension,
especially at the periphery of the eye. Because corneal powers may vary from
patient-to-
patient and eye-to-eye, there may be uncertainty in any linear measurements
taken
through the cornea. In addition, because most eye surgery is performed through
a
microscope, the measurement may have to be taken through the microscope, which
may
have a zoom feature or a variable focal length that may further complicate a
linear
dimension measurement.
[0010] Accordingly, there exists a need for an apparatus and method for
measuring the size of the capsular bag of an eye that is relatively simple and
accurate,
and does not rely on a linear measurement at the periphery of the eye.
Brief description of the drawings
[0011] FIG. 1 is a flow chart of a method of replacing a lens in the capsular
bag
of an eye.
[0012] FIG. 2 is a front-view plan drawing of an angle indicator according to
an
embodiment of the present invention.
[0013] FIG. 3 is a schematic drawing of the angle indicator of FIG. 2 at three
exemplary capsular bag sizes.
[0014] FIG. 4 is a schematic drawing of an approximate geometry of the angle
indicator of FIGS. 2 and 3.
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[0015] FIG. 5 is a plot of capsular bag diameter versus measured angle A, for
a
variety of straight segment lengths, for the approximate geometry of FIG. 4.
[0016] FIG. 6 is a close-up of the q=0.6 plot of FIG. 5.
[0017] FIG. 7 is an isometric drawing of a protractor according to an
embodiment
of the present invention.
[0018] FIG. 8 a set of views of the protractor of FIG. 7.
[0019] FIG. 9 is a plan view of a sizing gauge according to an embodiment of
the
present invention.
[0020] FIG. 10 is a plan view of a sizing gauge according to an embodiment of
the present invention that includes a handle or grip.
[0021] FIG. 11 is a plan view of a system according to an embodiment of the
present invention where a sizing gauge is disposed over an angle indicator
placed within
the capsular bag of a subject eye.
[0022] FIG. 12 is a plan view of another embodiment of a sizing gauge
incorporating a plurality of linear marks or line segments.
[0023] FIG. 13 is a plan view of a system according to an embodiment of the
present invention where the sizing gauge of FIG. 12 is disposed over an angle
indicator
placed within the capsular bag of a subject eye.
[0024] FIG. 14 is a perspective view of another embodiment of a sizing gauge
that comprises two notches or wedge-shaped portions .
[0025] FIG. 15 is a perspective view of a kit or set of sizing gauges like the
sizing
gauge shown in FIG. 14.
[0026] FIG. 16 is a front view of a kit or set of sizing gauges like the
sizing gauge
shown in FIG. 14 that are joined together to facilitate choosing different
gauges during
use.
Detailed description of the drawings
[0027] Implantation of an intraocular lens in an eye may require the accurate
measurement of the size, position, or other property of the capsular bag of
the eye.
Embodiments of the present invention are generally directed devices, systems,
and
methods for determining the size, extent, location, or physical property of a
capsular bag
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or other cavities of a subject eye. While such devices, systems, and methods
may be used
in conjunction with any intraocular lens or similar device to be placed within
a capsular
bag, embodiments of the present invention may be particularly useful when used
with
accommodating intraocular lenses, where function of the intraocular lens may
be
particularly sensitive to fit of the lens inside the capsular bag.
[0028] In some embodiments, the natural crystalline lens is surgically removed
and a size indicator is subsequently inserted into the capsular bag for
measuring a size or
other property of the capsular bag. As used herein, the term "size" means the
extent of an
object and includes at least the diameter, circumference, cross-sectional
area, and volume
of an object (e.g., of the capsular bag of an eye). As used herein the term
"size indicator"
means a physical device that changes size or shape when placed inside the
capsular bag
of an eye, or some other part of an eye, and is configured to allow an
estimate or
measurement of a size of the size indicator itself and/or a size, shape, or
physical property
of the capsular bag or cavity into which the device is placed, the estimate or
measurement
being based on a visible size or shape of one or more elements of the size
indicator. In
some cases, the size indicator may be used for determining the position of the
capsular
bag, for example, relative to the pupil of the eye. When a size of a capsular
bag is
measured or estimated, the size may be an actual size of a capsular bag at the
time of the
measurement or a size of the capsular upon or after implantation of an
intraocular lens or
similar ophthalmic device.
[0029] In some embodiments, the size indicator is visually inspected by a user
to
make an estimate of size of the size indicator and/or the capsular bag or
other part of the
eye. In such embodiments, a geometric feature of the size indicator may be
compared to
a feature of a measurement device or to a template showing different
configurations of
the geometric feature being inspected. In other embodiments, the size
indicator is part of
a measurement system that also includes a measurement device configured for
estimating
or measuring a size of one or more elements of the measurement device, either
by eye or
using a digitized image and analysis software or algorithms.
[0030] In certain embodiments, the size indicator is an angle indicator. As
used
herein the term "angle indicator" is a size indicator in which an angle
between two
elements or arms of the angle indicator may be observed, estimated, or
measured in order
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to determine a size of the angle indicator itself and/or a size or other
property of a
capsular bag or other part of an eye into which the angle indicator is placed.
[0031] FIG. 1 is a flow chart of an exemplary method 10 for using an angle
indicator for replacing a lens in the capsular bag of an eye.
[0032] In element 11, a lens is removed from a capsular bag of an eye. The
removed lens may be the natural crystalline lens of the eye, which may have
become
opaque due to cataracts or become damaged by some other disease or injury.
Alternatively, the removed lens may be an existing intraocular lens that is
being replaced.
Typically, the lens is removed in a surgical procedure in which the lens is
broken up and
vacuumed out of the eye. The capsular bag, which supports the lens before
removal, is
generally retained for support of the replacement lens.
[0033] The replacement lens may be an intraocular lens, such as an
accommodating intraocular lens, which relies on forces transferred by the
zonular fibers
in the eye to the capsular bag and/or on forces produced by a resiliency of
the capsular
bag itself. These forces can change the power and/or location of the lens by
change the
lens shape and/or translating one or both of the lens surfaces. The ocular
force exerted by
the ciliary muscle, capsular bag, and/or zonular fibers is generally limited,
and typically
the accommodating intraocular lens is designed to use this limited force to
change power
to cover all or part of a desired range of accommodation for the eye. As a
result, the
intraocular lens may be quite sensitive to compressive or expansive forces
applied to its
equator. Importantly, a particular accommodating intraocular lens may be
designed to
work optimally for a specific capsular bag size or size range. If the
patient's capsular bag
is larger or smaller than expected, the intraocular lens may experience a
shift in nominal
power, or a truncation of the accommodation range, which may be undesirable.
Accordingly, it may be useful during a surgical procedure to accurately
measure the size
of the capsular bag, so that an intraocular lens may be selected for
implantation that
corresponds to the actual size of the capsular bag or provides a predetermined
fit within
the capsular bag.
[0034] In element 12, an angle indicator, is inserted into the capsular bag.
During
insertion, it is often desirable to use as small an incision as possible, so
the angle
indicator may optionally be inserted in a folded state.
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[0035] In element 13, the angle indicator is expanded to coincide with a size
or
diameter of the capsular bag. If the angle indicator is inserted in a folded
state, it may be
first unfolded to reach its full size. The capsular bag material is flexible,
so that it may be
bent and reshaped. It may be relatively straightforward to position the angle
indicator,
which may be generally ring-shaped, along the equator of the capsular bag.
Typically,
some gentle, back-and-forth motions applied by the surgeon are sufficient to
move the
angle indicator to lie along the equator of the capsular bag. In general, the
shape of the
empty capsular bag is such that it may be well-approximated as circular when
viewed
from the front. Any azimuthal errors in the positioning of the angle indicator
generally
do not significantly affect the angular reading from the angle indicator, or
the measured
value for the capsular bag size.
[0036] In element 14, once the angle indicator is aligned along the equator of
the
capsular bag and the angle is read from the angle indicator. The angle may be
formed
from the intersection of two generally straight elements on the angle
indicator. In some
embodiments, the intersection is substantially centrally disposed within the
pupil of an
eye into which it has been placed, for example, to aid in measuring the angle
thus formed.
Alternatively, the straight elements of the angle indicator may be relatively
long (e.g., to
provide a predetermined sensitivity), wherein the intersection between the two
generally
straight elements may be near the edge of the pupil or outside the pupil. The
angle may
be seen visually by the surgeon or by a camera or microscope trained on the
subject eye.
Alternatively or additionally, the angle may be determined by producing an
electronic or
digital image of the angle indicator and processing the image using software
or
algorithms to analyze the image.
[0037] In element 15, once the angle has been read, the angle indicator may be
removed from the capsular bag of the eye. The angle indicator may be folded
upon itself
for removal, which is especially convenient if the angle indicator is inserted
in the folded
state. Alternatively, the angle indicator may be broken or separated into
segments, and
then the segment may be removed through the incision in the eye. In one
embodiment,
the angle indicator includes cutaways on its posterior surface, or other
location, which
may allow sectioning in vivo for removal of the angle indicator.
[0038] In element 16, the read angle is converted to a capsular bag size or
other
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property of the capsular bag. The size may be reported as a diameter, or,
equivalently, as
a circumference. The conversion may be done by reading values off a printed
table, by
reading values off a graph, by plugging the read angle into a predictive
formula, by a
computer, or directly by comparing the angle to a dedicated device.
Alternatively or
additionally, the location of the capsular bag may be determined within the
eye, for
example, relative to the location of the pupil or the macula.
[0039] In element 17, once element 16 has produced a value of the capsular bag
size, an intraocular lens may be selected or otherwise specified (e.g., the
parameters of a
custom lens may be specified). The lens selection or specification may be
based in part
on the capsular bag size, as well as on other data, such as the required lens
power, an
available amount of accommodative force, and/or a targeted range of
accommodation.
[0040] For instance, for a given required nominal lens power, there may be
several intraocular lenses available, each sized for a particular capsular bag
diameter.
The available lenses may be part of a kit, with diameter spacings of 0.5 mm,
0.25 mm,
0.2 min, 0.15 mm, 0.1 min, 0.05 iron, or any suitable value. Typically, the
exact size
value given from element 16 may not be exactly available in the kit, and the
surgeon or
practitioner may have to round off to the nearest size that is available in
the kit or specify
a custom lens.
[0041] Alternatively, the intraocular lens may have an adapter that can be
attached to the circumference of the lens, which allows a single lens to be
used with
multiple sizes of capsular bags.
[0042] As a further alternative, the intraocular lens may itself be
adjustable, for
instance, with an adjustable haptic that can couple a particular optic to a
capsular bag
sized within a particular range.
[0043] In element 18, once an intraocular lens is selected from element 17,
the
selected lens may be surgically implanted in the capsular bag.
[0044] Note that element 15 follows element 14, and elements 16 and 17 follow
element 14, but elements 16 and 17 need not follow element 15. For instance,
element 15
may follow element 17, which follows element 16, which follows element 14. The
conversion of the read angle to a capsular bag size and the selection of a
lens based on the
capsular bag size are essentially independent of removal of the angle
indicator from the
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capsular bag, and these elements may be performed in any suitable order.
[0045] Referring to FIG. 2, an angle indicator 30 suitable for use with the
method
is shown. The angle indicator 30 comprises a broken ring or incomplete annulus
31,
with the broken portion of the ring replaced by two arms, segments, or
straight sections
32 and 33 that connect to the broken ring 31 and are hingedly connected to
each other at a
location within the interior of the broken ring 31. The angle indicator is
inserted into the
capsular bag and the ring 31 expands until it is coincident with a diameter of
the capsular
bag. As the ring itself expands and contracts, the angle between the two
segments
increases and decreases. The angle indicator 30 is generally configured to
provide an
indication or measurement of a capsular bag size or other property
independent, or at
least substantially independent, of corneal or camera magnifications. The size
indicator
30 extends into the center of the capsular bag and is compliant, so that it
may be safely
removed by grasping the central features and withdrawing it from the capsular
bag.
Additionally or alternatively, the size indicator 30 may be used for sizing
other portions
of the eye such as the sulcus or anterior chamber of the eye. The shape or
shape change
may be measured visually by eye, with or without the use of an external gauge
or
template, or may be measured using a camera and associated image processing
software.
[0046] With additional reference to FIG. 3, the angle indicator 30 is designed
so
that a relatively small change in diameter of the ring 31 produces a
relatively large
change in angle between arms 32, 33. For instance, three exemplary diameters
D1, D2
and D3, are shown in FIG. 3, along with their corresponding angles Al, A2 and
A3. The
relationship between measured angle and ring (and, therefore, capsular bag)
diameter is
shown in the exemplary plot in FIG. 3. Note that the relationship need not be
truly linear,
as shown in FIG. 3, but may have any suitable increasing relationship, such as
a quadratic
or more complex polynomial relationship. During use, the practitioner inserts
the angle
indicator 30 into the capsular bag, expands the angle indicator 30 to fill the
capsular bag,
reads the angular value from angle indicator 30, and converts the read angular
value to a
capsular bag diameter, or equivalently, circumference.
[0047] Note that the angle is viewable near the center of the pupil of the
lens,
rather than only at the edge of the pupil or the edge of the capsular bag.
This reduces the
need for unusual viewing techniques, or extra handling of the pupil, and may
help reduce
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distortion of the angle when viewed through the patient's cornea.
[0048] In one embodiment, the angle indicator 30 remains substantially round,
for
all angles/diameters within a particular range. This is accomplished by
varying the radial
thickness of the ring, with a maximum thickness opposite the two segments, and
a
minimum thickness in the regions adjacent to the joints that attach the
straight segments
to the rest of the ring. This is shown more clearly in FIG. 2.
[0049] The incomplete annulus 31 of the angle indicator 30 may optionally have
a
varying radial thickness around its circumference. Adjacent to the hinges 34
and 35, the
radial thickness 36 may be its minimum. The radial thickness may increase
farther away
from the hinges 34 and 35, reaching an intermediate value 37 partially around
the ring,
and may finally reach a maximum value 38 directly opposite and between the
hinges 34
and 35. Alternatively, the radial thickness may be constant around its
circumference, or
may vary in a manner other than the exemplary manner described above.
[0050] In the exemplary design of FIG. 2, the out-of-plane thicluless is
essentially
constant along the incomplete annulus 31 and segments 32 and 33. The corners
may be
rounded, or may be un-rounded.
[0051] The variation in radial thickness around the ring helps ensure that the
incomplete annulus stays essentially round, even as the angle between the
straight
segments 32 and 33 varies. As such, the diameter dimensions D1, D2 and D3 in
FIG. 3
are truly diameters, and the outermost shapes of the angle indicators are
essentially round
at each of the three sizes shown. The angle indicator 30 retains its round
periphery as it
is compressed.
[0052] Alternatively, the radial thickness of the angle indicator 30 may
remain
essentially constant around the ring, and the out-of-plane thickness may vary
along the
ring. As further alternatives, both the radial thickness and the out-of-plane
thickness may
vary around the ring and/or the radial thickness may remain constant but the
material
modulus or strength may vary along the ring, for example, being stiffer away
from the
hinges.
[0053] The hinges 34 and 35 may be formed integrally as weakened portions of
the angle indicator 30. In one embodiment, the hinges 34 and 35 are formed at
regions of
reduced in-plane thickness at the intersections of the straight segments 32
and 33 with the
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incomplete annulus 31. As such, the hinges 34 and 35 may bend freely in the in-
plane
direction, allowing the angle indicator to freely expand and contract to
attain its
maximum size inside the capsular bag. The hinges 34 and 35 may be configured
to
preclude or reduce movement of the two segments 32, 33 out of the plane of the
angle
indicator 30. Generally, the angle indicator 30 may be made integrally as a
single unit, or
may be made from several pieces that are assembled. The assembled pieces may
be
made from the same or from different materials.
[0054] The segments 32, 33 are joined to each other by a third hinge 39,
formed
by an in-plane thickness reduction, also permits free in-plane movement of the
segments
32, 33 with respect to each other. The helps to provide free diametric
expansion and
compression of the angle indicator 30 and restricts out-of-plane movement.
[0055] Note that the segments 32 and 33 are shown in the figures as being
entirely straight. In practice, there may be some curvature to all or a
portion of either or
both of the segments. For instance, there may be some local waviness to all or
a portion
of the segments 32 and 33. Alternatively, there may be a more global
curvature, having a
radius on the order of or larger than the angle indicator radius. In one
embodiment of the
angle indicator, the segments 32 and 33 are straight throughout.
[0056] Note that the angle indicator 30 may measure capsular bags having a
size
larger than the incision through which the angle indicator is inserted. For
instance, the
angle indicator may measure capsular bag diameters on the order of 11 mm. In
general,
the diameter of the angle indicator in an uncompressed state is at least about
9
millimeters in diameter, but may be between about 8 millimeters and about 15
millimeters, preferably between about 9 millimeters and about 12 millimeters.
In some
embodiments, the diameter of the angle indicator in an uncompressed state has
a nominal
value of 11 mm or about 11 mmn (i.e., 11 min plus or minus 0.5 mm). As such,
the angle
indicator 30 may be compressed in an injector or folded upon itself during
insertion (and
later, during extraction), and may be unfolded and expanded for performing the
measurement. When used in conj unction with an accommodating intraocular lens,
the
angle indicator is configured to fit through an incision in the eye that is
less than about 5
millimeters, preferably less than 4 millimeters. In other embodiments, for
example when
used with an intraocular lens that does not provide accommodation, the angle
indicator is
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configured to fit through an incision in the eye that is less than about 3
millimeters,
preferably less than 2 millimeters.
[0057] During insertion and positioning of the angle indicator 30, it may be
beneficial to gently "force open" the straight segments 32 and 33 of the angle
indicator
30. This may be accomplished by applying a force on or near the rear
(essentially flat)
side of the hinge 39, directed outward from the ring, toward the opening
between the
segments. The force may be applied by the practitioner using the equipment
that is
typically used to position objects during surgery, such as a hook or forceps.
Because the
force may be applied directly to angle indicator 30, there may be no need for
extra holes
or tabs for this purpose, although holes and/or tabs may optionally be used.
[0058] In certain embodiments, the angle indicator 30 is configured to produce
a
relatively small force when placed within a capsular bag. For example, the
force
produced by the angle indicator 30 when the diameter is compressed 2
millimeters may
be between about 0.5 gram and about 20 grams, preferably between about 0.5
gram and 5
grams. Such low forces may beneficially reduce the possibility of damaging the
capsular
bag during use of the angle indicator 30, but may require manipulation by the
practitioner
to insure that the incomplete annulus 31 fully engages the equatorial region
of the
capsular bag. Alternatively, a higher force may be used to ensure positive
engagement of
the equatorial region of the capsular bag with a minimal amount of adjustment
by a
practitioner, for example, a force of between about 10 grams and about 30
grams or more.
[0059] The length of the segments 32 and 33 may be varied, so that the hinge
that
joins them may fall on either side of the center of the ring at its nominal
position. As the
segment length is increased, the angle becomes easier for the practitioner to
read during
use, although the sensitivity is decreased. Likewise, as the segment length is
decreased,
the angle becomes more difficult for the practitioner to read during use, but
the sensitivity
is increased. In practice, the designer of ordinary skill in the art
understands this trade-
off, and may design an angle indicator 30 with a suitable range of operation,
a suitable
sensitivity, and a suitable ease of angle viewing.
[0060] Optionally, there may be more than one angle indicator for a particular
eye
or patient, with each angle indicator covering a particular range of capsular
bag sizes.
For instance, one angle indicator may be used for capsular bag diameters in
the range of 9
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to 10 mm, and another angle indicator may be used for the range 10 to 11 mm.
These
values are merely exemplary, and any suitable ranges may be used.
[0061] Note that because the angle may be measured from roughly the center of
the pupil, there is generally little distortion of the angle caused by the
cornea. If the
cornea imparts a magnification an image of the segments forming the angle, the
segments
themselves may appear to grow or shrink in size, but the angle between the
segments
remains essentially unchanged. This holds for a wide range of cornea radii,
and a wide
range of magnifications caused by the cornea.
[0062] It is instructive to perform some trigonometry to more accurately show
the
graphical dependence of measured angle A and capsular bag diameter D, which is
not
truly linear as shown schematically in FIG. 3, but has a more complicated
dependence.
[0063] FIG. 4 shows an exemplary geometry for one embodiment of an angle
indicator. We assume for this simplistic analysis that the lengths of the
incomplete
annulus (i.e., the open ring-shaped segment) and the straight segments remain
constant
during use; this is a good approximation for this purpose.
[0064] Both the length of the incomplete annulus and the length of each
straight
segment may be related to a "closed diameter" Do, which is the diameter of the
angle
indicator when the segments are parallel, or "closed". The length of the
incomplete
annulus is mD0, and the length of each straight segment is qDo, where q is a
dimensionless
quantity than can between 0 and 1. When q is 0.5, the straight segments extend
to exactly
the center of the ring when the ring is "closed". When q is 1, the straight
segments
extend all the way to the opposite end of the ring when the ring is "closed".
When q is 0,
the straight segments are infinitesimally small.
[0065] During use, the angle indicator expands to a diameter of D, with a
measured angle A between the straight segments. Length y and angle A are
mathematical constructs. We attempt to solve for A in terms of D.
[0066] First, solve for y: y = D sin(A/2).
[0067] Next, we express angle A in terms of the length irpo of the incomplete
annulus: A = (2n - 2mcDo/D).
[0068] Plug into expression for y: y = D sin (it - mDo/D) = D sin(itDo/D)
[0069] Can also solve for y in terms of A and qDo: y = 2 qD0 sin(A/2)
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[0070] Set these two expressions for y equal to each other and rearrange to
get:
sin(A/2) = sin(mDo/D) / (2 qDo/D)
[0071] Solve for A and rewrite as A= 2sin-'([n/2q] [sin(itDo/D) / (mDo/D)])
[0072] FIG. 5 is a graph of the above equation, which predicts capsular bag
diameter D versus measured angle A, for several values of q.
[0073] The choice of q is related to both sensitivity and dynamic range. For
relatively short straight segments (low q), there is high sensitivity and low
dynamic
range. Similarly, for relatively long straight segments (high q), there is low
sensitivity
and high dynamic range.
[0074] In some embodiments, it is preferable if the vertex, or intersection
between the straight segments, is located at or near the center of the ring
for at least part
of the range of use. The circles superimposed on the various plotted curves in
FIG. 5
show the operating condition at which the vertex is at the center of the ring.
Note that for
short segments (q < 0.5), there is no condition under which the vertex can be
located in
the center of the ring; these segments are just too short to extend to the
center, regardless
of angle A.
[0075] Note that for q = 0.6 (i.e., where the straight segments are 20% longer
than
the radius of the "closed" ring), the vertex falls at the center of the ring
at a measured
angle A of 60 degrees. In one embodiment, this may be a preferable set of
conditions;
the plotted region for q = 0.6 is enlarged and is shown in FIG. 6.
[0076] For FIG. 6, we choose a convenient set of numbers, which are merely
exemplary and are not intended to be limiting in any way. For instance, if we
wish to
measure capsular bags having a diameter in the range of 11 mm to 13 mm, we use
an
angle indicator having a "closed" diameter of 10 mm and a short segment length
of 6
mm, and detect angles between 30 and 90 degrees. If our detection scheme
allows us to
detect angle A to the nearest 15 degrees, we may measure the diameter of the
capsular
bag to the nearest 0.5 mm (based on the 10 mm diameter of the angle
indicator). These
values are merely exemplary, and any lengths and diameters may be scaled
upwards or
downwards. Other suitable values may also be used.
[0077] Note also that the mathematical analysis that generates the plots of
FIGS.
and 6 is approximate, and assumes that the lengths of the ring-shaped segments
and the
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two straight segments all remain constant throughout operation. This is only
an
approximation, and one of ordinary skill in the art will readily appreciate
that more
sophisticated simulations may be performed that account for local stresses and
deformations, bending of the materials, and other effects not considered in
the simplistic
analysis presented above.
[0078] The discussion thus far has focused primarily on the angle indicator
30,
which generates an angle as a function of the capsular bag size or shape. The
following
paragraphs focus primarily on measurement devices for estimating or measuring
the
angle between arms 32, 33 of the angle indicator 30 or other size indicators.
For the
purposes of this document, the term "measurement device" means any device or
system
suitable for measuring or estimating a size or location of a size indicator or
angle
indicator disposed within an eye, for example, by measuring or estimating an
angular or
linear dimension of one or more elements of the size indicator or angle
indicator. The
measurement device may, for example, be a sizing gauge, an image processing
system,
software package, or the like. The measurement device may include software,
hardware,
firmware, or algorithms suitable for providing a measurement or estimate of a
size or
location of a size indicator or angle indicator.
[0079] For the purposes of this document, the term "sizing gauge" means a
physical measurement device suitable for providing an estimate or measurement
of a size
or location of a size.indicator or angle indicator. For example, a sizing
gauge may be a
template, chart, set of reference images, reticle, protractor, or the like. In
certain
embodiments, a sizing gauge includes a flexible sheet that may be placed on
the eye (e.g.,
a contact lens) having marks configured for measuring or estimating a
dimension of a
size indicator or angle indicator. In other embodiments, a sizing gauge may
include a
calibrated reticle or protractor, which may be used for visual inspection by
eye, or used
with an optical instrument, such as a microscope or a camera. When used with
the angle
indicator 30, or similar device, the sizing gauge may include angular
increments on the
reticle or protractor may include one half degree, one degree, five degrees,
10 degrees, 15
degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45
degrees, or any
suitable increment. Alternatively, the sizing gauge may be marked with indicia
that
correspond directly to the capsular bag size or appropriate ranges
corresponding to
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available implant sizes. As used herein, the term "protractor" means a device
that can
read, measure, or indicate an angle of a size indicator or angle indicator,
either by visual
inspection or by electronic means.
[0080] An exemplary protractor 70 for use with the angle indicator 30, or
another
size indicator for sizing a capsular bag, is shown in the isometric drawing of
FIG. 7 and
the three views of the plan drawing of FIG. 8.
[0081] The protractor 70 has a generally circular ring 71 that is sized to
rest on
the cornea to allow measurement of the angle from the angle indicator. The
ring 71 is
small enough to fit on the eye of the patient, and large enough to surround
the pupil of the
eye. A typical range of diameters for the protractor ring may be from about 3
min to
about 12 mm, or from about 5 min to about 8 min.
[0082] Note that the straight segments 32 and 33 of the angle indicator 30 are
viewable from roughly the center of the pupil, rather than requiring a
measurement taken
at the edge of the capsular bag. As a result, ring 71 of the protractor need
not extend all
the way to the edge of the capsular bag or to the edge of the cornea. The ring
71 may
optionally have rounded or chamfered edges that may reduce the risk of
scratching the
cornea.
[0083] The protractor 70 has a reference portion 72 that has radial edges 73
and
77. During use, the reference portion 72 generally extends out of the plane of
the ring 71,
so that it may rest upon or extend over the cornea, which is curved. When
viewed from
the front, the intersection of radial edges 73 and 77 may fall at or near the
center of the
ring 71, and/or at the intersection of the straight segments 32 and 33 (e.g.,
at the hinge
39). Note that the reference portion 72 may deform so that this intersection
of radial
edges 73 and 77 may lie away from the center when the protractor is not in
use.
[0084] In one embodiment, the protractor is rigid, so that the protractor
roughly
maintains its shape before, during and after use. In this embodiment, the
reference
portion 72 may extend out of the plane of the ring 71 in its relaxed state
before use.
Alternatively, the reference portion may 72 may be located roughly in the
plane of the
ring 71 before use, and may pivot in the anterior direction during use. The
pivoting may
occur around a weakened portion of the reference portion, which may include an
optional
hole, opening, or void area 81. In some embodiments, the void area 81 may have
a more
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complex shape that the hole shown in FIG. 7, for example, to provide a
weakened zone
with predetermined bending characteristics or to avoid confusion that the void
area 81
represents an alignment mark with the straight segments 32 and 33.
[0085] In another embodiment, the protractor 70 is flexible, and may be draped
onto the cornea of the eye. Such a flexible protractor conforms generally to
the shape of
the cornea, without significantly deforming in the plane of the protractor.
The protractor
70 may be made from a largely transparent material, and may include markings
or
features that indicate predetermined angle values. For instance, the
protractor 70 may
include a central feature that may be overlaid with the lunge 39 during use,
and various
angular features, such as reticle marks or other radial lines or features. In
one
embodiment of a flexible protractor 70, the protractor may be formed on or be
made
integral with a contact lens that is placed onto the cornea during use.
[0086] For the protractor 70 of FIG. 7, the protractor is positioned during
use so
that one of the radial edges 73 and 77 lines up with one of the straight
segments 32 and
33. The other straight segment falls elsewhere around the circumference of the
ring, and
may fall near one of several calibration features, such as notches, tabs,
holes, extensions,
annotations, colors or members.
[0087] For instance, if radial edge 73 is aligned with straight segment 32,
then
straight segment 33 may fall near one of feature 74, feature 75 or feature 76.
The
features may be in calibrated increments, such as 30 degrees, 20 degrees, 15
degrees, 10
degrees, 5 degrees, 1 degree or less, or any suitable increment. For instance,
if the
increment is 30 degrees between each of the features 74-76, then if the
straight segment
32 falls closest to the feature 74, then the angle of the indicator is closest
to 30 degrees.
Similarly, if the straight segment 32 falls closest to the feature 76, then
the angle of the
indicator is closest to 90 degrees.
[0088] In addition, there is a second set of radial edge 77 and features 78-
80,
which may be used equally as well as the first set of radial edge 73 and
features 74-76.
The second set may be calibrated with the same angular increment as the first,
or with a
different angular increment as the first.
[0089] Alternatively, there may be more than three or fewer than three
features.
In addition, the features may be evenly or unevenly spaced.
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[0090] Once the measurement has been taken, the protractor 70 may be removed
from the cornea of the patient. In one embodiment, the protractor 70 may be
removed by
grasping it with the hole 81, or by an optional elevated feature or tab (not
shown).
[0091] In certain embodiments, a more conventional protractor may be used,
with
notches, tick marks, lines, or other visual cues extending around the
circumference at a
prescribed interval, such as every 30 degrees, or any other suitable interval.
This more
conventional protractor may lack the reference portion 72. As another example,
the
protractor may be made from a soft material that is draped over the cornea or
rests on the
facial tissue that surrounds the eye, rather than on the eye itself.
Alternatively, the angle
may be measured from an image formed of the eye on a screen or in software. As
a
further alternative, there may be an angular reticle supplied with a camera or
microscope,
which may allow a reading of the angle.
[0092] Both the angle indicator 30 and the protractor 70 may be made from any
suitable biocompatible and flexible materials. For instance, either or both
may be made
from silicone or any polymeric material, PMMA, or any other suitable material.
In one
embodiment, the material or materials used may be moldable, and may not be
hydrophilic. In one embodiment, the material is sterilizable by autoclave, by
ETO, or by
any suitable sterilization process. The angle indicator 30 and protractor 70
may be made
from the same or from different materials. Either or both angle indicator 30
and
protractor 70 may be made of a transparent or translucent material.
Alternatively, either
or both angle indicator 30 and protractor 70 may be made of a tinted, opaque
or
fluorescing material, so that they may easily be read visually. In one
embodiment, the
angle indicator and protractor may be supplied in pre-sterilized, sealed
packages that
accompany an intraocular lens. Both the angle indicator and protractor may be
unsealed
when needed, and disposed of once a measurement has been taken.
[0093] In other embodiments, either or both the angle indicator 30 and the
protractor 70 may be configured for single-use or a limited number of uses.
For example,
the protractor 70 may be made of an autoclavable material for reuse in
subsequent
procedures, while the angle indicator 30 is made of a disposable material that
is discarded
after one use or after use on a single subject. In such embodiments, the angle
indicator
30 or a set of angle indicators 30 may be shipped in a sterile condition along
with an
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intraocular lens to be inserted into a subject eye.
[0094] In one embodiment, there may be sets of angle indicators and
protractors,
with each set corresponding to a different range of capsular bag sizes. For
instance, one
set may be used for a size range of 9 to 10 mm, and another set may be used
for a size
range of 10 to 11 mm. Each set may be color-coded so that the particular
protractor is
easily associated with its corresponding angle indicator, and the measured
angles are
easily associated with their proper measured capsular bag sizes.
Alternatively, there may
be other identifying characteristics for matched sets of angle indicators and
protractors,
such as texture, etching, surface characteristics, ridges and so forth.
[0095] In certain embodiments, an electronic or digital image of the angle
indicator 30 in the eye and/or the protractor 70 is produced. The digital
image may be
captured and processed using a computer or other electronic system in order to
determine
the angle between the two straight sections 32 and 33. The resulting digital
representation may be used to increase the accuracy of the angle measurement,
as a cross-
check to a manual measurement, or to provide other information (e.g., the
location of the
angle indicator and/or capsular bag within the eye, or to determine a change
in size of the
capsular bag, as discussed in greater detail below).
[0096] In one embodiment, the outer edges of the angle indicator may expand
through viscoelastic/OVD in the capsular bag.
[0097] In one embodiment, the straight segments, or central arms, of the angle
indicator may extend past the center of the angle indicator. These longer
straight
segments may fill a larger area of the pupil, and may provide an easier
measurement than
smaller or shorter straight segments.
[0098] In one embodiment, the angle indicator may be inserted into the
capsular
bag by an injector.
[0099] In one embodiment, the angle indicator may include a tether, so that
the
angle indicator may be more easily withdrawn after the measurement has been
taken.
The withdrawing may be done directly by the tether. Alternatively, the tether
may attach
the angle indicator to an injector, so that the withdrawal may be done by the
injector.
[00100] In one embodiment, the angle indicator may include one or more loops
on
the straight segments or on the incomplete annulus that extend in the anterior
direction
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(i.e., away from the patient's eye), for positioning and removal of the angle
indicator.
[00101] In one embodiment, the flexural characteristics of the straight
segments, or
arms, their bases, and/or the central hinge may be "tuned" in shape or
stiffness, so that
the angle indicator may stay round over a wide range of compression.
[00102] In certain embodiments, the angle indicator 30 is made of a silicone
material having a hardness of between about 70 durometer and about 80
durometer which
approximately corresponds to a modulus of elasticity that may provide a
desired
compressive force when the angle indicator is placed within a capsular bag. In
other
embodiments, the modulus of elasticity of the angle indicator material (e.g.,
silicone or
acrylic) and/or the width of the various angle indicator sections may be
varied, so that
reliable measurements may be made without excessively stretching the capsular
bag.
[00103] In certain embodiments, the angle indicator 30 may be used to
determine
or estimate the resiliency of the capsular bag into which it is implanted. For
example, the
angle indicator 30 may be made of a material having a relatively high modulus
of
elasticity and/or may be otherwise configured to be relatively resilient or
stiff. In some
embodiments, two or more angle indicators 30 may be used. For example, a first
angle
indicator 30' may be inserted into the capsular bag that produces a relatively
low force on
the capsular bag (e.g., between about 0.1 grain to about 10 grams of force).
As such, the
first angle indicator 30' may be used to determine the size of the capsular
bag when in a
substantially unstressed state, as described in greater detail above. The
first angle
indicator 30' may then be removed from the eye and replaced by a second angle
indicator
30" that is stiffer than the first angle indicator 30', thus producing a
higher, radially
outward force (e.g., in the range of about 5 grams to about 30 grains or more)
when
compressed by about the same amount as the first angle indicator 30'. Due to
the
increased force on the capsular bag, the bag is stretched by the second angle
indicator 30"
and thus produces a different bag size measurement. In some embodiments, the
second
angle indicator 30" additionally or alternatively has a diameter that is
greater than the
first angle indicator 30', thereby increasing the force produced on the
capsular bag
compared to that produced by the first angle indicator 30'. Other differences
between the
angle indicators 30', 30" may be advantageously used to provide a different
radially
outward force and/or to determine the resiliency of the capsular bag.
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[00104] Alternatively, a single angle indicator 30 may be used that remains in
the
capsular bag; however, the size of the angle indicator 30 and/or on the
capsule wall may
be changed by increasing or decreasing the radially outward force of the
incomplete
annulus 31 or exerted on the incomplete annulus 31. The change in force may be
produced by changing the resiliency of the angle indicator 30 and/or by
inserting another
device or apparatus that applies additional force on the equatorial region of
the capsular
bag and/or angle indicator 30. In some embodiments, a surgeon may change the
outward
force on the incomplete annulus 31 by using one or more probes or other
devices to push
or pull at one or more locations on the incomplete annulus 31.
[00105] However the difference in size is induced, the resulting size
difference
may be measured and used to calculate a resiliency of the capsular bag and/or
estimate
the amount of accommodative force available for accoimnodation. In some
embodiments, the change is size is quantitatively measured to determine a
resiliency or
other property of the capsular bag. Alternatively, the change in size may be
qualitatively
assessed so that the surgeon may broadly characterize a resiliency or other
property of the
capsular bag.
[00106] In certain embodiments, the angle indicator 30 is implanted within a
capsular bag and the force produced by the ciliary muscle is changed in order
to measure
a change in the size and/or amount of force produced by the capsular bag. For
example, a
muscarinic agent such as a muscarinic agonist or a muscarinic antagonist may
be used to
alter the amount of accommodative force produced by the eye, as disclosed in
USPN
6,598,606 or US Patent Application Number 2005/0251254, which are herein
incorporated by reference.
[00107] In one embodiment, a plurality of angle indicators 30 is provided in
the
form of a kit, with each angle indicator 30 having a different elasticity or
tensile strength.
Such a kit may be used to determine the elasticity of a particular evacuated
capsular bag,
in order to best determine the most compatible accommodating intraocular lens.
[00108] In one embodiment, the angle indicators 30 are provided in a kit, with
each angle indicator 30 having a different axial thiclaness. Such a kit may
help match the
measurement of the capsular bag size to the axial thickness of the intended
implanted
intraocular lens, both at the edge of the lens and centrally.
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[00109] In one embodiment, the arms 32, 33 include overlapping, curved vernier
extensions. With reference to the exemplary design of FIG. 2, arm 32 may
include one or
more tangentially-curved extensions that protrude toward arm 33, and arm 33
may also
include one or more tangentially-curved extensions that protrude toward arm
32, with the
tangentially-curved extensions being located next to each other. In this
manner, the angle
may be read directly from the extensions, rather than with an additional
external device
such as a measurement device or sizing gauge.
[00110] In one embodiment, the incomplete annulus 31 may include extensions or
tabs protruding from one or both of the straight segments 32, 33 and disposed
along the
circumference of, and in the plane of, the incomplete annulus 31. These
optional
extensions may help maintain the capsular circularity in the region between
the straight
segments 32, 33.
[00111] In addition to measuring the capsular bag size for intraocular lens
implantation, the angle indicator 30, or variations thereof, may be used for
other fields as
well, such as measuring the diameters and stenosis of body cavities,
especially in
endoscopic and catheter-based procedures for sizing shunts and implants. The
angle
indicator allows estimation of a particular diameter, regardless of viewing
magnification.
This may also be used in the fields of interventional cardiology, as well as
vascular,
bariatric and gastroenteric surgeries. Furthermore, the angle indicator 30, or
variations
thereof, may also be used to measure the size of the anterior chamber or other
cavities of
the eye.
[00112] Referring to FIGS. 9-11, in some embodiments, a sizing gauge 102 is
configured for measuring or estimating a size of a size indicator (e.g., the
angle indicator
30) or for measuring or estimating a size or other characteristic of a
capsular bag or other
cavity into which a size indicator is inserted. Where applicable, the sizing
gauge 102
incorporate features and functions of the protractor 70 discussed above, or
visa versa.
[00113] In the illustrated embodiments in FIG. 11, the sizing gauge 102 is
part of a
measurement system comprising an angle indicator 90 and the sizing gauge 102,
the
system configured for measuring a size or other characteristic of a capsular
bag of an eye.
The angle indicator 90 may be similar or equal to the angle indicator 30. The
angle
indicator 90 includes a peripheral portion 92 configured to contact a capsular
bag of a
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subject eye and a pair of arms 94 operably coupled to the peripheral portion
92 and joined
at an intersection of the arms 94. The arms 94 are configured so that an angle
formed by
the arms 94 varies in response to a size of the capsular bag and/or other
property, such as
a resiliency or elasticity of the capsular bag.
[00114] The sizing gauge 102 comprises a body 110 having a front surface 112.
Various features of sizing gauge 102 are visible when viewed from in front of
the front
surface 112, these features being useful for measuring an angle of the angle
indicator 90
or similar device. Any or all of these features may be disposed on the front
surface 112
and/or on a surface of the sizing gauge 102 that is opposite the front surface
112.
Alternatively, at least some of the features may be disposed between front and
back
surfaces of the sizing gauge 102, for example, on a laminate surface that is
between front
and back surfaces of the sizing gauge 102.
[00115] In the illustrated embodiment, the sizing gauge 102 includes an inner
portion 115, an outer portion 118, and a border or boundary 120 disposed
therebetween.
The boundary 120 is configured to provide a comparison, estimate, or
measurement of an
angle of the arms 92 of the angle indicator 90 when the sizing gauge 102 is
disposed in
front of the angle indicator 90.
[00116] Optionally, the sizing gauge 102 may comprise a handle or grip 128, as
illustrated in FIG. 10 for the sizing gauge 102'. The handle 128may be sized
and
configured to allow the sizing gauge 102' to be held by a practitioner in
order to move
the sizing gauge 102' into a desired location and orientation in front of the
angle indicator
90. Additionally or alternatively, the handle 128 may be configured to be held
by a
robotic or automated positioning device that is controlled either by an
electronic
controller configured to move the sizing gauge 102 relative to the angle
indicator 90.
[00117] The sizing gauge 102, 102' may be made of a metal or polymer material,
or any material suitable for a clinical environment and providing necessary
physical
properties. The sizing gauge 102, 102' may be made of a single material or may
comprises different materials. For example, the handle 128 of the sizing gauge
102' may
be made of a different material than the rest of the sizing gauge 102'. In
some
embodiments, all or portions of the sizing gauge may be made of a transparent
or
substantially transparent material, for example, in order to facilitate
viewing of the angle
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indicator 90 when used therewith.
[00118] The inner portion 115 may be an opening or aperture 124 in the body
110,
wherein the boundary 120 is an inside edge of sizing gauge 102. In such
embodiments,
the outer portion 118 may be made of either a transparent material or an
opaque material.
The aperture 124 and the boundary 120 are configured to allow the angle
between the
pair of arms 94 of the angle indicator 90 to be estimated or measured.
[00119] In some embodiments, the inner and outer portions 115, 118 are made of
a
common or similar material, wherein the boundary 120 is a border between the
portions
115, 118. In such embodiments, the inner and outer portions 115, 118 may both
be made
of a transparent, semi-transparent, or clear material, wherein the border 120
may be dark,
opaque, or otherwise configured to allow delineation between the inner and
outer
portions 115, 118. Alternatively, at least one of the portions 115, 118 may be
opaque,
colored, translucent, frosted, darkened, or only partially transparent, while
the other
portion 118, 115 may transparent or semitransparent.
[00120] The border 120 in the illustrated embodiments comprises a
quadrilateral
shape 125 in which opposite vertices 126a, 126b join sides of the
quadrilateral to form
angles that are different from one another, the angles being selected to
correspond
different angles between the pair of arms of the angle indicator 90. The
sizing gauge 102,
102' may further comprise alphanumeric characters 130, for example, in the
inner or
outer portions 115, 118 and/or indicating a size or other value correlating to
one or more
angles of the angle indicator 90.
[00121] During use one of the vertices 126a, 126b is aligned to a vertex of
the
angle indicator 90 located at the intersection of the arms 94. As illustrated
in FIG. 11, the
angle between the sides forming the vertex 126b is approximately equal to the
angle
formed by the arms 94 of the angle indicator 90. The alphanumeric "10 mm" near
the
vertex 126b indicates that the match or approximate match between these two
angles
correlates to a capsular bag diameter of 10 mm or approximately 10 mm.
Alternatively,
the alphanumeric characters on the sizing gauge 102 may be used to indicate or
correlate
to other quantities such as, an angle between the pair of arms of the angle
indicator 90, a
circumference, cross-sectional area, or volume of the capsular bag, a
resiliency of the
capsular bag, or the like.
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[00122] The outer portion 118, inner portion 115, surface 112, and/or the back
surface opposite surface 112 of sizing gauge 102, 102'may be either planar or
curved. If
curved, the radius of curvature may be selected to allow the sizing gauge to
be draped
over the cornea of an eye. For example, the sizing gauge 102 may be a contact
lens that
has a radius of curvature that is approximately equal to the radius of
curvature of the
cornea. Alternatively, the surface curvature of the sizing gauge 102' may be
configured
to fit or closely fit the shape of the cornea. In any event, the sizing gauge
102, 102' may
be configured to have little or no optical power. Alternatively, the sizing
gauge 102,
102' may be configured to have an optical power, for example, a negative
optical power
that at least partially compensates or nullifies the optical power of the
cornea of an eye.
In other embodiments, the optical power is selected to provide a desired
magnification or
to form part of an imaging system configured to view the angle indicator 90 or
a portion
of the eye into which the angle indicator 90 is implanted.
[00123] In some embodiments, a kit comprising a plurality of sizing gauges 102
is
provided, for example, with each sizing gauge 102 have a different radius of
curvature or
shape. Additionally or alternatively, the kit may include a plurality of
sizing gauges 102,
wherein different sizing gauges 102 have different included angle between the
sides of
the ironer portion 115.
[00124] Referring to FIGS. 12 and 13, in some embodiments, a sizing gauge 202
is
configured for measuring or estimating a size of a size indicator (e.g., angle
indicators 30,
90) or for measuring or estimating a size or other characteristic of a
capsular bag or other
cavity into which a size indicator is inserted. Where applicable, the sizing
gauge 202
incorporate features and functions of the protractor 70 and/or the sizing
gauges 102, 102'
discussed above, or visa versa. In the illustrated embodiments in FIG. 13, the
sizing
gauge 202 is part of a measurement system comprising the angle indicator 90
and the
sizing gauge 202, the system being configured for measuring a size or other
characteristic
of a capsular bag of an eye.
[00125] The sizing gauge 202 comprises a body 210 having a front surface 212
and various features that are visible when viewed from in front of the front
surface 212,
these features being useful for measuring an angle of the angle indicator 90
or similar
size indicator. Like the sizing gauge 102, the features of the sizing gauge
202 may be
CA 02719935 2010-09-28
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disposed on one or more of the front or back surfaces of the sizing gauge 202,
or between
the front and back surfaces.
[00126] The sizing gauge 202 comprises a first feature 224 and a second
feature
226 that are disposed on or behind the surface 212. The first feature 224 is a
vertex mark
224 that is configured to be aligned to the vertex of the angle indicator 90
formed at the
intersection of the arms 94. In the illustrated embodiment, the vertex mark
224
comprises an aperture that may be a through hole in the body 210 or may
comprise a
clear material, for example, the same material as the remaining portions of
the body 210.
Alternatively, the vertex mark 94 comprises a pair of crosshairs, a bull's eye
pattern, or
other marking suitable for facilitating alignment of the sizing gauge 202 to
the
intersection of the arms 94 of angle indicator 90.
[00127] The second feature 226 of the sizing gauge 202 comprises three lines
that
are disposed parallel to one another and perpendicular to a longitudinal axis
of the sizing
gauge 202. In other embodiments, the second feature comprises a different
number of
lines (e.g., 2 lines or 4 lines). In any event, the lines 226 are disposed a
different
distances from the vertex mark 224 and may have different lengths, as in the
illustrated
embodiment shown in FIG. 12. The endpoints of each line 226 and the center of
vertex
mark 224 are configured to correspond to different angles between the arms 94
of the
angle indicator 90.
[00128] Referring to FIG. 13, during use, the vertex mark 224 of the sizing
gauge
202 is aligned to an intersection between arms 94 of the angle indicator 90.
The angle of
between the arms 94 may be determined or estimated based upon which of the
line 226
endpoints touches, or is closest to touching, a predetermined part of the arms
94 (e.g., an
inner or outer edge of each of the arms 94). In this manner, the measured or
estimated
angle between the arms 94 may be correlated to a size or other property of the
capsular
bag into which the angle indicator 90 has been placed. In the illustrated
embodiment,
alpha numeric characters 230 are disposed near the lines 226 to show a
correspondence of
the lines 226 to a capsular bag size of either 9.5 mm, 10 mm, or 10.5 mm. It
is not
necessary that each line be associated with a particular alphanumeric
character 230. For
example, in FIGS. 13 and 14 the sizing gauge 202 does not have an alphanumeric
symbol
associated with the center line 226, but it is understood that if the arms of
the angle
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indicator just touch the center line 226, then this correlates to a capsular
bag diameter of
mm.
[00129] Referring to FIG. 14, in some embodiments, a sizing gauge 302 is
configured for measuring or estimating a size of a size indicator (e.g., angle
indicators 30,
90) or for measuring or estimating a size or other characteristic of a
capsular bag or other
cavity into which a size indicator is inserted. Where applicable, the sizing
gauge 302
incorporate features and functions of the protractor 70 and/or the sizing
gauges 102, 102',
202 discussed above, or visa versa. In the illustrated embodiments in FIG. 14,
the sizing
gauge 202 may be part of a measurement system that comprises the angle
indicator 90
and the sizing gauge 302, the system being configured for measuring a size or
other
characteristic of a capsular bag.
[00130] The sizing gauge 302 comprises a body 310 having a front surface 312
and various features that are visible when viewed from in front of the front
surface 312,
these features being useful for measuring an angle of the angle indicator 90
or other size
indicator. Like the sizing gauges 102, 102', 202, the various features of the
sizing gauge
302 may be disposed on one or more of front or back surfaces of the sizing
gauge 202, or
between the front and back surfaces. The body 310 of the sizing gauge 302 may
be made
of a clear, colored, frosted, or opaque material, according to the
requirements of the user
or manufacturer.
[00131] The body 310 comprises a pair of notches or wedge-shaped features 324
disposed along side and top edges of the body 310. The use of two wedge-shaped
features 324 may be configured to allow easy manipulation of the sizing gauge
302 in
order to align one of the wedge-shaped feature 324 to the arms 94. In the
illustrated
embodiment, each wedge-shaped feature 324 has the same angular extent - in
this case
both angles corresponding to a capsular bag size of 10.8 mm. Alternatively,
each of the
wedge-shaped features 324 may have a different angle between the edges of the
wedge-
shaped feature, for example, to facilitate measurement of different arm 94
angles with a
single sizing gauge 302. In some embodiments, the sizing gauge 302 comprises
only one
wedge-shaped feature 324. In other embodiments, the sizing gauge 302 comprises
three
wedge-shaped features 324 or more than three wedge-shaped features 324.
[00132] The sizing gauge 302 in the illustrated embodiment comprises an
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elongated body 312; however, other shapes may be used. For example, two,
three, four,
or more wedge-shaped features 324 may be configured on a circular body,
wherein each
of the wedge-shaped features 324 has a different angle between the edges of
the wedge-
shaped features'324.
[00133] Referring to FIGS. 15 and 16, the sizing gauge 302 may be part of a
kit or
set 300 or 300' of sizing gauges 302 that are used for estimating or measuring
the size or
other property of a capsular bag. The sizing gauges 302 in the set 300' are
attached
together at a proximal end of each sizing gauge 302, for example, to
facilitate easy
selection between individual gauges 302 during use.
[00134] During use, the angle indicator 90 is disposed within the capsular bag
of
an eye or inside another portion or cavity of the eye. One of the sizing
gauges 302 of the
kit 300 or 300' is then selected and located in front of the angle indicator
90 or other size
indicator. The sizing gauge is next aligned to the angle indicator 90 so that
a vertex 330
(see FIG. 14) of the wedge-shaped features 324 is disposed at the intersection
of the pair
of arms 94 of the angle indicator 90, and so that at least one of the edges of
the wedge-
shaped feature 324 is aligned to at least one edge of one of the arms 94. An
assessment
can then be made as to whether or not the angle of the wedge-shaped feature is
sufficiently close to the angle between the arms 94. If so, then the angle may
be
correlated to a size of the angle indicator or a size or other property of the
capsular bag
into which the angle indicator 90 has been placed. If the angles do not match,
then
another sizing gauge 302 from the kit 300, 300' is selected and the process is
repeated
until a correspondence is found between the angle of the wedge-shaped feature
324 and
the angle between the arms 94 of the angle indicator 90.
[00135] The description of the invention and its applications as set forth
herein is
illustrative and is not intended to limit the scope of the invention.
Variations and
modifications of the embodiments disclosed herein are possible, and practical
alternatives
to and equivalents of the various elements of the embodiments would be
understood to
those of ordinary skill in the art upon study of this patent document. These
and other
variations and modifications of the embodiments disclosed herein may be made
without
departing from the scope and spirit of the invention.
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