Note: Descriptions are shown in the official language in which they were submitted.
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INTERNAL LIMITING MEMBRANE RAKE
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of Applicant's co-pending U.S.
Design
Application No. 29/215,250, entitled "Internal Limiting Membrane Rake", filed
October 15, 2004; and U.S. Provisional Application No. 60/631,509, entitled
"Internal
Limiting Membrane Rake," filed November 30, 2004, which are hereby
incorporated
by reference in their entirety.
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
[0002] The present invention relates to a medical device used for removing a
membrane provided on an inner surface of a retina of an eye.
DISCUSSION OF RELATED ART
[0003] Certain diseases involve the presence of a thin membrane of scar tissue
that must be removed via a medical procedure. Examples of these procedures are
the peeling of epiretinal membranes and possibly internal limiting membranes
that
are the result of idiopathic epiretinal membranes. These membranes may also be
associated with macular holes and in vitreo macular traction syndrome, the
peeling
of epiretinal membranes in diabetic retinopathy, peeling of epiretinal
membranes in
proliferative vitreo retinopathy, peeling of epiretinal membranes after
trauma, and the
peeling of epiretinal membranes after intraocular inflammation, including
uveitis and
ophthalmitis.
[0004] Currently, these procedures are typically performed using one of three
types
of medical devices. Referring to FIG. 1(a), the first type is a sharp pick 1
comprising
a needle 2, typically of size 20 to 23 gage, that is bent at one end. The bent
end of
the needle 2 forms a sharp point 3, which is used to engage the membrane 20.
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However, prior to using the sharp pick 1, a small incision often must be made
in the
membrane 20, as shown by the arrow in FIG. 1(a). Thereafter, the sharp pick 1
is
inserted into the incision where the pick 1 is used to scrape along an edge of
the
incision between an inner surface of the retina 30 and a lower surface of the
membrane 20 in an attempt to lift up the membrane 20 in a direction indicated
by the
arrows of FIG. 1(b).
[0005] However, the pick I has drawbacks. In particular, the pick I is able to
engage a relatively small area of the membrane 20, making removal of all or
large
portions of the membrane 20 at the same time extremely problematic.
[0006] Referring to FIG. 2, the second medical device currently used to remove
the
membrane 20 is a pair of forceps 4, which are used to clamp a small portion of
the
membrane 20 along an outer edge or along an edge of an incision made therein.
The forceps 4 grip the portion of the membrane 20 and lift the membrane 20 off
of
the retina 30. Because the forceps 4 engage such a small portion of the
membrane
20, the forceps 4 have difficulty removing the membrane 20 in one piece and
imparts
the risk of leaving behind pieces of the membrane.
[0007] Referring to FIG. 3, the third medical device currently used to remove
retinal
membranes is a scraper 5, which commonly includes a piece of silicon tubing 6
with
small pieces of diamonds 7 embedded onto an outer surface of the tubing 6. A
region of the tubing 6 having the diamond pieces 7 embedded therein is applied
to
and scraped along an inner surface of the membrane 20, as indicated by the
arrow
in FIG. 3. The scraping action dislodges the membrane 20 from the surface of
the
retina 30. However, the scraping action requires downward pressure to be
exerted
on the retina 30, which creates a substantial risk of injury to the retina 30
and
adjacent structures. Similarly, the scraper 6 is only able to engage a small
area of
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the membrane 20, making removal of the membrane 20 in one piece very difficult
and increasing the possibility of leaving pieces of the membrane behind.
Finally, the
scraper 6 necessitates the insertion of an additional instrument (not shown)
into the
eye to complete removal of the membrane 20 from the retina 30.
[0008] An additional drawback associated with each of the above devices, that
is,
the pick 1, the forceps 4, and the scraper 6, is that relatively high
magnification levels
must be used during the corresponding procedures for removing the membrane 20.
The high magnification levels inherently decrease the area of the retina 30
that can
be viewed by medical personnel when attempting to remove the membrane 20,
thereby extending the time necessary to perform the procedure as well as
making it
more difficult for the medical personnel to successfully remove the membrane
20 in a
single piece.
SUMMARY OF THE INVENTION
[0009] The present invention addresses the above-discussed and other drawbacks
in t he k nown m edical d evices. T he p resent i nvention p rovides a m
embrane rake
which engages any region of the membrane along a large surface area of the
membrane and is not limited to engaging an edge of the membrane or the edge of
an incision made in the membrane. Moreover, the structural configuration of
the
membrane rake permits the user to engage a much larger surface area of the
membrane than any of the known medical devices.
[0010] F urthermore, the present i nvention d oes n ot require the formation
of an
incision in the membrane or the introduction of an additional instrument into
the eye
to aid or complete the process of removing the membrane from the retina of the
eye.
Moreover, the present invention applies significantly less pressure onto the
retina
when initially engaging the membrane relative to the pressure applied onto the
retina
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by some of the known medical devices described above. Additionally, once the
present invention has engaged the membrane on the retina, relatively minimal
tangential and lifting forces are applied to the retina when using the present
invention
to remove the membrane from the retina.
[0011] Finally, the present invention is used at lower magnification levels
relative to
the relatively higher magnification levels which the known medical devices
must be
used, thereby providing a significantly larger field of view during the
membrane
removal procedure. The aforementioned benefits and features of the present
invention greatly reduce the risk of injury to the eye while significantly
simplifying the
process of removing the membrane from the retina, as well as increasing the
likelihood the membrane is removed entirely in a single piece.
[0012] To achieve the aforementioned and other benefits, the present invention
provides a rake configured to remove a thin membrane formed on an inner
surface
of a retina of an eye. In one embodiment, the rake includes a handle and a
plurality
of tines which are retractable into and extendable from the handle either
manually or
mechanically. Ideally, the handle has a hollow body and at least one barb or
other
such tissue engaging mechanism is provided on a tip of each tine.
[0013] According to one embodiment of the invention, the tines are slidingly
retracted into the hollow handle body as well as slidingly extended from the
hollow
handle body. Once extended from a working end of the handle body, the tines
spread apart and outward from each other. As such, the rake is able to engage
a
relatively large area of the membrane surface.
[0014] In another embodiment of the present invention, the tines are flexible,
wherein the flexibility of the tines depend on the amount the tines are
extending from
the working end of the handle body. The farther the tines extend from the
working
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end of the handle body, the greater the amount of flexibility. Similarly, the
closer the
tines are to the working end of the handle body, that is, the less the tines
are
extended from the working end of the handle body, the lesser the amount of
flexibility
the tines posses.
[0015] According to another aspect of the present invention, once the extended
tines engage the upper surface of the membrane, the tines are retracted,
drawing up
and securing the membrane between the at least one barb or other tissue
engaging
feature and the working end of the handle.
[0016] Additional advantages and novel features of the present invention will
be set
forth in the following description, and will also become apparent to those
skilled in
the art upon examination of the following or upon learning by practice of the
invention.
BRIEF DESCRIPTION OF DRAWINGS
[0017] Other aspects of the present invention will be better understood from
the
following description, along with the accompanying drawings, wherein:
[0018] FIGs. 1(a) and 1(b) illustrate a conventional sharp pick device used to
remove a membrane from a retina;
[0019] FIG. 2 illustrates a conventional forceps device used to remove the
membrane from the retina;
[0020] FIG. 3 illustrates a conventional scraper device used to remove the
membrane from the retina;
[0021] FIG. 4 is a cross-sectional view of a rake according to an embodiment
of the
present invention;
[0022] FIG. 5 is a diagram illustrating the different states in which the
tines of the
rake shown in FIG. 4 can be extended from the handle of the rake
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[0023] FIG. 6 illustrates an embodiment of the tissue engaging features
provided at
the free end of each tine;
[0024] FIG. 7 illustrates another embodiment of the tissue engaging features
provided at the free end of each tine;
[0025] FIG. 8 illustrates the tangential and lifting forces created by the
rake of the
present invention that are used to remove a membrane from the retina of an
eye;
[0026] FIG. 9 illustrates the different states of the rake engaging the
membrane on
the retina of an eye and removing the membrane therefrom; and
[0027] FIG. 10 illustrates the rake engaging the membrane in an intermediate
portion of the membrane remote from the peripheral edges of the membrane.
DETAILED DESCRIPTION OF THE INVENTION
[0028] The present invention provides a membrane rake 10 which engages any
region of the membrane 20 along the entire surface of the membrane 20. The
structural configuration of the membrane rake 10 permits the user to engage a
much
larger surface area of the membrane 2 0 than any of the known medical devices.
Furthermore, the present invention does not require the formation of an
incision in
the membrane 20 or the introduction of an additional instrument into the eye
to aid or
complete the process of removing the membrane 20 from the retina 30 of the
eye.
Moreover, the rake 10 applies significantly less pressure onto the retina and
adjacent
structures when initially engaging the membrane 20 relative to the pressure
applied
onto the retina by some of the known medical devices described above. Finally,
the
rake 10 is used at lower magnification levels relative to the relatively
higher
magnification levels which the known medical devices must be used, thereby
providing a significantly larger field of view during the membrane removal
procedure.
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[0029] FIG. 4 illustrates an exemplary rake 10 of an embodiment of the present
invention, for use in removing a membrane 20 (FIGs. 6 and 8-10) from an inner
surface of the retina 30 (FIGs. 6 and 8-10) of the eye. The rake 10 of this
embodiment comprises a handle 40 and a telescoping slide member 50. The handle
40 comprises a hollow tube, through which the slide member 50 telescopes
freely
within an interior surface of the handle 40 (e.g., a central opening extending
the
length of the handle). Although the body of the handle 40 is preferably
tubular, it
should be noted that it is within the scope of the invention to provide the
body of the
handle 40 with any suitable geometric shape that promotes gripability of the
handle
40, such as, for example only, oval, rectangular, trapezoidal, hemi-spherical
and the
like in cross-section.
[0030] Fixedly provided at an end of the slide 50 are multiple tines 60 each
having
one end attached to the slide 50, with the opposite end freely extending
therefrom.
A free end of each tine 60 has a barb or other tissue engaging feature 70
(FIGs. 5-6)
provided thereon.
[0031] As shown in FIG. 5, the rightmost rake 10, when the slide member 50 is
fully retracted, such that the slide member 50 and most of the length of the
tines 60
are contained within the body of the handle 40, the tissue engaging features
70
protrude from the end of the handle 40. As shown in the rakelO second from the
right in FIG. 5, as the tines 60 extend from the handle 10, the outer ends of
the tines
60 spread apart from each other and away from a longitudinal axis of the rake
10,
allowing the tissue engaging features 70 to separate from one another in an
unobstructed manner. Once fully extended, as shown in the rake 10 third from
the
right in FIG. 5, tines 60 increase the potential area of engagement, providing
for
better control when removing the membrane 20. Finally, the leftmost rake 10
shown
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in FIG. 5 illustrates the feature of the fully extended tines 60, wherein the
slide
member 50 telescopes or slides out of the body of the handle 40.
[0032] In this embodiment, the amount the tines 60 are permitted to extend
beyond
the handle 40 is effectuated by pulling/pushing on an end of the slide member
50
that is opposite the end from which the tines 60 extend. It will b e
recognized by
those familiar with the art that, for embodiments of the present invention
incorporating extending and spreading tines, alternate features to provide
such
extension and spreading may be used. For example, the tines may be retracted
or
extended from the handle without the use of a slide member. Further, while the
relative position of the slide member 50 and handle 40 of FIG. 5 are
maintained by
simple frictional engagement between the slide member 50 and the handle 40,
other
features may be provided to maintain the relative position, such as locking
pins
within openings, screw retainers, clips engaging slots, and the like,
including
mechanical, hydraulic, and electromechanical mechanisms.
[0033] Referring to FIG. 6, in one embodiment of the present invention, the
tissue
engaging features 70 comprise a plurality of serrated barbs 71 extending from
the
free end of each tine 60. As shown in FIG. 6, each tissue engaging feature 70
includes a flexible body portion 70a joined to an engaging portion 70c by a
transverse portion 70b. In a fully retracted state, the transverse portion 70b
extends
orthogonally relative to the longitudinal axis of the rake 10. Further, while
in the fully
retracted state, the engaging portion 70c extends in a direction that is
parallel
relative to the longitudinal axis of the rake 10 and opposite to the direction
in which
the slide member 50 telescopes away from the body of the handle 40. Also, as
shown in FIG. 6, at least one and preferably a plurality of barbs 71 are
provided on a
free end of each engaging portion 70c of the tine 60. Additionally, in the
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embodiment of the FIG. 6, the tissue engaging features 70 may include a
serrated
end to increase friction or other gripping engagement with a surface of the
membrane 20.
[0034] Although FIG. 6 illustrates the barbs 71 as having pointed or serrated
bodies, it should be noted that it is within the scope of the invention for
the barbs 71
to have any suitable geometric shape that will promote the gripping and
lifting of the
membrane 20 off of the retina 30. For example, in an envisioned alternate
variation
(not shown), the tissue engaging features 70 of the embodiment of FIG. 6 are
not
serrated but, rather, have a sharpened unserrated edge. In yet another
example,
FIG. 7 illustrates another embodiment of the present invention wherein the
tissue
engaging features 70' are curved.
[0035] As shown in FIG. 8, when engaged with the membrane 20, the tissue
engaging features 70 and 70' create tangential and lifting forces to remove
the
membrane 20 and reduce downward pressure on the retina 30 as illustrated by
the
arrows. The extension and retraction of the tines 60 into and out of the
handle 40, in
combination with the tissue engaging features 70 and 70', offers yet another
benefit.
In particular, once the extended tines 60 engage the membrane 20, the tines 60
can
thereafter be retracted, drawing up and clamping the membrane 20 between the
tissue engaging features 70 and 70' and the end of the handle 40 from which
the
slide member 50 telescopes. Such clamping action further reduces the need to
introduce a second instrument into the eye for removing the membrane 20.
Further,
the ability to retract the tines 60 into the handle 40 decreases the
likelihood that the
inner surface of the retina 30 and any other part of the eye may be damaged by
the
tines 60, by retracting the tines 60 when the rake 10 is inserted or withdrawn
from
the eye.
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[0036] FIG. 9 illustrates an exemplary rake 10 removing a membrane 20 from the
surface of the retina 30. The right-most representation of the rake 10 of FIG.
9
shows the tissue engaging features 70 and 70' engaging an edge of the membrane
20. The progression of figures of the rake 10, from right to left, as shown in
FIG. 9,
depicts how the rake 10 may be used to both pull and lift the membrane 10.
FIG. 9
also shows the tines 60 flexing, in accordance with some embodiments of the
present invention.
[0037] In the embodiment of FIG. 9, the further the tines 60 are extended from
the
handle 40, the more the tines 60 are able to flex when pressed against an
object.
The increased flexibility of the tines 60 decreases the pressure exerted upon
the
upper surface of retina 30 by the rake 10. For example, in one embodiment,
when
the tines 60 are fully extended and contacting the membrane 20, the handle 40
can
be moved downward toward the retina 30 up to a millimeter without any
significant or
noticeable force on the retina 30. Such flexibility reduces the risk of injury
to the eye
during use of the rake 10. The flexibility of the tines 60 can be decreased,
that is,
the tines 60 can be made stiffer, by simply retracting the tines 60 into the
handle 40
until a desired stiffness is reached.
[0033] FIG. 10 illustrates the ability of the rake 10 to engage the membrane
20 at a
location along the inner surface of the membrane 20, with the location not
being
required to include an outer edge of the membrane 20 to be removed. The rake
10
is dragged along the upper surface of membrane 20 until the tissue engaging
features 70 and 70' engage the surface of the membrane 20. Once the tissue
engaging features 70 and 70' engage the membrane surface, the rake 10 is
simply
pulled upward and tangentially away from the upper surface of the retina 30 to
remove the membrane 20 therefrom. Once the rake 10 engages the membrane 20,
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no additional downward force is exerted upon the retina 30, which reduces the
risk of
eye injury.
[0039] Example embodiments of the present invention have now been described in
accordance with the above advantages. It will be appreciated that these
examples
are merely illustrative of the invention. Many variations and modifications
will be
apparent to those skilled in the art without departing from the scope and
spirit of the
invention.
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