Note: Descriptions are shown in the official language in which they were submitted.
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Description
A POSITIONING ASSEMBhY FOR RETAINING AND POSITIONING A CORNEA
BACKGROUND OF THE INVENTION
This is a continuation-in-part patent application based on
a currently pending U.S. patent application having Serial No.
08/840,430, filed on April 29, 1997, which is a continuation of
then pending patent application filed on February 7, 1996 and
having Serial No. 598,180, which since issued as U.S. Patent No.
5,624,456 on April 29, 1997.
Field of the Invention
The present invention relates generally to a medical
apparatus used during the performance of eye surgery, and in
particular, is directed towards an improved suction ring, also
termed a positioning assembly, for retaining, positioning and
exposing a patient's eye for cutting of the cornea during a
surgical procedure, such as to correct for refractive error. More
specifically, the present invention is directed to an easily
assembled and safe to use positioning assembly which minimizes the
potential for improper cutting of the eyelid andJor eye, and
further, which is capable of achieving and maintaining effective
attachment on an eye, even one having a latitudinally narrowed
ocular access, such as may be encountered in certain individuals,
most notably, but not exclusively, children and persons of Asian
descent.
Description of the Related Art
The eye works on a principle very similar to that of a camera
wherein the iris, or colored portion of the eye about the pupil,
functions like a shutter to regulate the amount of light admitted
to the interior of the eye. The cornea or clear window of the
eye, and the lens, which is located behind the pupil, serve to
focus the light rays from an object being viewed onto the retina
at the back of the eye. The retina then transmits the image of
the object viewed to the brain via the optic nerve. Normally,
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these light rays will be focused exactly on the retina, which
permits the distant object to be seen distinctly and clearly.
Deviations from the normal shape of the corneal surface however,
produce errors of refraction in the visual process so that the eye
becomes unable to focus the image of the distant object on the
retina, with the result that one sees a blurred image.
Many years ago, such refractive errors could only be treated
with eyeglasses or contact lens, both of which have well known
disadvantages for the user. Since then, however, surgical
operations have been developed to change the refractive condition
of the eye. Several methods and special instruments have been
designed for performing this kind of surgery, which are primarily
directed to reshape the cornea. It will be appreciated that the
goal of corneal reshaping is to modify the curvature of the
cornea, i.e., either to flatten or increase its curvature
depending on the patient's condition, so that light rays passing
through the cornea will thereafter be refracted to focus or
converge directly onto the retina, thereby permitting the patient
to view a distant object clearly.
One such surgical operation is keratomileusis, which requires
a precise reshaping of the cornea by cutting and separating a thin
layer of corneal tissue, termed the corneal cap, by lathing that
tissue and then, by suturing the reshaped corneal tissue back into
place on the eye. Keratomileusis is viewed, however, as having
several drawbacks, and consequently, has been abandoned in recent
years. Automated Lamellar Keratectomy (ALK) is another surgical
technique which developed as an outgrowth of keratomileusis. In
an ALK procedure, the eye is typically first numbed by a drop of
anesthetic, and then, a device having a ring shaped configuration
is placed on the eye to carefully position the cornea (termed
"centration" in the art) for being cut by a very fine
microsurgical instrument known as a microkeratome. The
microkeratome is generally a blade carrying device that must be
manually pushed or mechanically driven in a cutting path across
the ring shaped device to cut into the cornea. Under an ALK
procedure to treat near-sightedness, the microkeratome is
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typically first used to cut and lift a thin layer of the cornea,
instead of severing it, and second, to carry out a reshaping of
the cornea by way of a second pass of the microkeratome over the
cornea with the cutting element adjusted to pass therethrough at
a desired and pre-determined corrective depth. Thereupon the
thin, raised layer of corneal tissue is put back in place over the
cornea for healing.
There have been other significant developments in this field
of art, however. For example, a procedure known as Laser
Intrastromal Keratomileusis (LASIK), wherein a laser is utilized
to re-shape and/or contour the cornea, is becoming increasingly
accepted as both a safe, painless and rapidly effective procedure
for correcting vision problems such as, but not limited to,
nearsightedness, farsightedness and astigmatism, both regular and
irregular. The LASIK procedure is currently considered optimal
because it allows sculpting of the cornea without damaging
adjacent tissues, and further, because with the aid of computers,
the laser can be programmed by a surgeon to more precisely control
the amount of tissue removed, and significantly, to permit more
options for the reshaping of the cornea. Under LASIK procedures,
the eye is still typically positioned within a ring shaped device
and a microkeratome cutting head assembly is typically also used
as a preliminary step to cut and raise a thin layer of corneal
tissue in order to expose underlying portions of the eye for
treatment with the laser. The cutting of a thin layer of corneal
tissue is commonly known as a keratectomy, and in the most common
case, a ""corneal flap" will be cut, which leaves a hinged portion
of tissue attached to the cornea, although there are special cases
where a '"free caps' is cut wherein the raised layer of corneal
tissue is left detached from the eye.
Turning more specifically to how the eye is maintained in the
desired position for a LASIK procedure, the ring shaped device
referred to above is commonly used and is attached to the eyeball
temporarily by way of a suctioning force or vacuum. As such, such
devices are often referred to as suction rings, and a typical
suction ring includes an annular, hollow ring that defines a
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central aperture, which allows the cornea to be exposed
therethrough, and an open bottom side having a standard dimension
and which is structured to engage the surface of the eye around
the cornea. The suction ring is typically in communication with
a hollow suction tube, which is in fluid flow communication with
the open bottom side of the ring. A vacuum is commonly applied
to such suction rings, via the suction tube, with a relative
vacuum of typically between 20" Hg and 28" Hg, being applied,
which draws the suction ring down upon the globe of the eye under
the influence of external atmospheric pressure. As such, the
suction ring attaches to the surface of the eyeball surrounding
the cornea, with the suction force being applied and holding the
ring in a reasonably secure fashion to the eyeball throughout the
LASIK procedure. As a result, the suction ring has become a
conventional device in ophthalmic practice, and it should be
noted, is designed to be re-usable so as to accommodate a large
number of patients over the course of its useful life.
while the use of such suction rings have become quite common
in the art, there have been some drawbacks associated with them.
For example, the configuration and size of known suction rings do
not readily permit them to be comfortably and/or properly
positioned within the ocular recess of many persons. More
specifically, it has been determined that some individuals, and
especially children and persons of Asian decent, tend to exhibit
certain physical characteristics which result in there being a
somewhat constricted area available for placement of the suction
ring. For example, such individuals may either have a more narrow
ocular recess and/or may not be able to open their eyes as wide
as some other persons, especially in the latitudinal and/or up and
down direction. This restricted access can often lead to
difficulties for the practitioner performing a surgical procedure
such as LASIK on the eye, as an insufficient surface area for
proper securement of a traditional suction ring exists.
As a result, it would be highly beneficial to provide a
microkeratome assembly, and in particular an improved suction ring
for use with such an assembly, which is especially well suited for
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use in the eyes of all patients, including those having
latitudinally smaller ocular accesses. Any such improved suction
ring developed, however, should be able to be effectively and
comfortably secured to the exposed portions of the patient s eye,
5 while still exposing and presenting a sufficient depth and/or
diameter of the cornea for cutting by the microkeratome cutting
head assembly. Furthermore, if any such improved suction ring
were developed, it would be very beneficial if it were structured
for effective use with a cutting head assembly of the type
1o configured to cut along an arcuate path, such as that disclosed
in U.S. Patent No. 5,624,456 and considered by many to perform a
keratectomy with optimal results, without interfering with the
cutting process and/or diminishing its accuracy, despite there
being a more confined area or ocular recess.
It is also noted that conventional suction rings can be
difficult to manufacture and/or assemble, particularly given the
degree of precision which is necessary for safe and effective use
during opthamological procedures. If a suction ring were
developed which is suitable for a smaller ocular recess, which is
commonly found on children and persons of Asian descent, these
issues would also have to be addressed satisfactorily. Thus, it
would be beneficial to provide an improved suction ring or
positioning assembly which integrates all of the necessary
components into an efficient, streamlined, and compact
configuration, which is readily capable of being manufactured
accurately and precisely, and which still allows for the safe and
precise utilization of a microkeratome assembly. Lastly, it would
also be beneficial if any improved suction ring were developed
which could reasonably ensure that during a keratectomy, the
microkeratome cutting head assembly will initiate cutting of the
cornea at a uniform and rather precise position relative to the
eyelid and/or cornea so as to avoid the possibility that an
improper cut will occur. More in particular, it would be
beneficial to provide an improved suction ring or positioning
assembly that does not allow the cutting of an incision to begin
unless the cutting head assembly is properly positioned.
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Sumrnary of the Invention
The present invention is structured to address these and
other needs which remain in the art and is directed towards an
improved suction ring, and more specifically, a positioning
assembly for retaining and positioning the cornea of patient's eye
for the performance of a surgical procedure thereon. The
positioning assembly of the present invention is, in at least one
embodiment, especially suited for use on patients exhibiting a
latitudinally narrowed ocular recess or ocular access, meaning
that dimension which corresponds to the direction of blinking, as
is commonly found on children and individuals of Asian descent.
Also, while the present invention has application to the eye of
any patient, it is expected that it will typically be used on the
human eye.
More in particular, the present invention is directed towards
a positioning assembly which at least partially exposes, positions
and retains an eye during a surgical procedure. The positioning
assembly is, therefore, preferably incorporated as part of a
microkeratome assembly, and as a result, may be utilized in
conjunction with a microkeratome cutting head assembly that is
configured to form an incision in and/or cut across the eye,
whether that results in the creation of a corneal flap or not.
The positioning assembly includes a positioning segment which is
structured to retain and position the eye during the surgical
procedure such that the cornea is maintained in a properly exposed
position throughout. As such, the positioning segment includes
a retention plate. The retention plate preferably includes a
generally planar configuration, and has an aperture defined
therein. The aperture, which in the preferred embodiment is
generally centrally disposed on or within the retention plate, is
structured to receive and expose the cornea of the eye therein,
so as to generally define the area to be cut.
The position segment also includes a flange member. The
flange member depends generally downward from the retention plate
and is disposed in preferably enclosing relation about the
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aperture. As such, the flange member is structured to engage the
eye at least substantially along a bottom edge thereof.
Accordingly, a vacuum chamber is generally defined between the
aperture, bottom edge of the flange member, and the surface of the
eye extending therebetween. The flange member of the present
invention is also preferably disposed a relatively close, spaced
apart distance from the aperture of the positioning segment, at
least generally along a latitudinal radius thereof. As a result,
in circumstances wherein the patient has a latitudinally narrowed
ocular access, not as much of the surface of the eye need be
exposed by the ocular access in order to achieve effective contact
between the positioning segment and the eye, and in order to
effectively expose a sufficient quantity of the cornea within the
aperture.
The positioning assembly of the present invention may further
include, at least in part, a suctioning assembly. In particular,
a suctioning assembly is preferably operatively associated with
the positioning segment, preferably at the vacuum chamber, thereby
at least temporarily attaching the positioning segment to the eye.
Specifically, the suctioning assembly includes a vacuum port
connected in fluid flow communication between the vacuum chamber
and an exterior source of vacuum. As a result, a suction force
is applied at the vacuum chamber, and effective securement of the
positioning assembly to the eye is achieved. Preferably, however,
the vacuum port, unlike traditional, perpendicularly-oriented
vacuum ports, is at least partially angled outwardly away from the
vertical axis of the aperture, thereby providing effective
clearance for movement of the microkeratome cutting head assembly,
as will be described subsequently herein.
In the more preferred embodiments of the present invention,
the positioning assembly of the present invention includes a guide
track. The guide track is preferably integrally formed with the
positioning segment, and further, defines a preferably arcuate
cutting path, which guides the microkeratome cutting head assembly
at least partially across the aperture defined in the retention
plate. The guide track preferably extends latitudinally beyond
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the retention plate of the positioning segment and is preferably
disposed in close proximity to the vacuum port. As such, the
generally outward, angled nature of the vacuum port away from the
guide track ensures that a suction tube or like structure coupled
to the vacuum port will not interfere with the movement of the
cutting head assembly in operative association with the guide
track.
Additionally, the positioning assembly preferably includes
a pivot assembly and associated coupling member. Specifically,
the pivot assembly defines a pivot axis for the cutting head
assembly, which as indicated preferably moves arcuately across the
aperture as defined at least by the guide track and also
preferably by the pivot assembly. Preferably, a post member is
included in the pivot assembly to define the pivot axis about
which the cutting head assembly rotates, the coupling member
pivotally interconnecting the post member with the cutting head
assembly at least for this purpose. The pivot assembly, however,
also further comprises a cut origination control. The cut
origination control is structured to define at least one
origination point for the commencement of operative pivotal
movement of the coupling member, and accordingly the cutting head
assembly, across the positioning segment. As a result, a
practitioner is ensured that the cutting head assembly engages the
eye and begins the formation of the incision only at a proper
point, such as at the edge of the aperture, and generally cannot
be inadvertently positioned to form an incision commencing at an
intermediary point of the exposed cornea.
These and other features of the present invention are
described in further detail in the following detailed description
and associated drawings.
Brief Description of the Drawings
For a fuller understanding of the nature of the present
invention, reference should be had to the following detailed
description taken in connection with the accompanying drawings in
which:
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Figure 1 is a perspective view of the positioning assembly
of the present invention;
Figure 2 is a cross section view of the positioning assembly
of the present invention;
Figure 3 is an exploded perspective view of the coupling
assembly of the positioning assembly, and an associated
microkeratome cutting head assembly;
Figure 4 is an isolated side view of the post member of the
pivot assembly of the present invention;
Figure 5 is a top plan view of the post member;
Figure 6 is a cross-section of the coupling assembly;
Figure 7 is a top plan view of the positioning assembly of
the present invention without the post member and coupling
assembly coupled thereto;
Figure 8 is an illustration of a microkeratome assembly
incorporating the positioning assembly of the present invention
appropriately disposed on a corresponding eyes of a patient; and
Figures 9A-9C are a series of sequential illustrations
demonstrating a normal cutting path for a microkeratome assembly
with which the positioning assembly of the present invention is
preferably associated.
Like reference numerals refer to like parts throughout the
several views of the drawings.
Detailed Description of the Preferred Embodiment'
Illustrated throughout the drawings, the present invention
is directed generally towards a positioning assembly for improved
retaining and positioning of a patient's eye, and preferably the
cornea of the patient's eye which is to be cut during a surgical
operation, and is generally indicated by reference numeral 10.
More specifically, the present invention is directed towards a
more compact, precision assemblable and manufacturable, safety
enhancing and stable positioning assembly 10 that can be used not
only on the average patient, but which can also be used
effectively on a patient having a latitudinally reduced ocular
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access wherein the eye is contained. In particular, the ocular
access is generally defined as the eye socket and associated eye
lid, all of which limit and/or otherwise restrict the amount of
a patient's eyeball that can be exposed, such as for securing to
5 a positioning assembly. In some cases, and most prevalently with
children and patient's having characteristic, Asian facial
features, the ocular access exhibits a smaller than normal
latitudinal dimension. (For purposes of this description, a
latitudinal dimension is defined as an up and down dimension
10 relative to the patient's face, up being towards the patient's
eyebrow and down being towards the patient's chin.) As a result,
a conventional positioning assembly is generally not able to
sufficiently engage the latitudinal sides of the eyeball.
Naturally, such a restriction results in improper centration,
and/or less of the cornea being exposed for cutting. As will be
described, the present invention provides a more compact
configuration, which is beneficial not only in the case of a
latitudinally reduced ocular access, but which is generally
beneficial when performing surgery on the eye for a variety of
reasons including ease and precision of assembly, safety, and
stability during cutting.
The positioning assembly 10 of the present invention is
preferably directed for use with a microkeratome assembly such as,
but not necessarily like the one described in U.S. Patent No.
5,642,456, and incorporated herein by reference. As illustrated
in Figures 1, 2 and 7, the positioning assembly 10 comprises a
positioning segment 20, also known as an eye positioning ring.
The positioning segment 20 preferably includes an enclosed ring
configuration, so as to maximize its engagement with the eye, and
is used to centrate the eye, that is, to retain, position and
properly present the cornea of a patient's eyeball in a precise
and aligned manner for surgery. Thus, the positioning segment 20
has a main body which includes and defines, a preferably enclosed
aperture 25 therein. The aperture 25 is sized to receive and
permit the cornea C, of the eye to pass therethrough so as to
expose the cornea C, and a pre-determined depth thereof, for
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cutting during surgery. Typically, the cornea C will be cut
during surgery when a microkeratome cutting head assembly 15, also
preferably part of the microkeratome assembly, is moved over the
face of the positioning segment 20 and thus, over the exposed
cornea C, which as is clear from the drawings, protrudes through
the aperture 25. The aperture 25 itself is preferably sized to
expose a sufficient amount of the cornea so that a diameter of
generally about 7.5 to 10 millimeters may be cut. The positioning
segment 20 is preferably formed of a rigid material and
preferably, a metallic material. Ideally, however, the
positioning segment 20 will be made of a high grade stainless
steel, which enhances precision engagement with the eyeball, can
be formed to have a smooth, safe and glare-retardant surface
finish, and which provides for ease of sterilization. Along thee
lines, although the present positioning assembly may be made
disposable, out of a variety of materials, and/or molded of
plastic or metal, in the illustrated embodiment, the positioning
assembly 10 is preferably machined so as to achieve the degree of
precision and quality generally desired.
As illustrated in the figures, the main body of the
positioning segment ~20 is preferably defined by a generally
circular shape about the aperture 25, although it will be
appreciated that it could be formed to have another shape, such
as a square, rectangular, hexagonal or other shape about the
aperture 25, and still function for the intended purpose.
Moreover, the entire positioning assembly 10 is preferably
configured in a generally tear drop type shape. In the preferred
embodiment, the main body of the positioning segment 20 comprises
a retention plate 23, which includes the aperture 25 defined
therein, and preferably a flange member 24 extending generally
downwardly from the retention plate 23 and defining a generally
open bottom side to the main body 22. Ideally, the flange member
24 is disposed in spaced apart, generally surrounding relation to
the aperture 25 defined in the retention plate 23. Also in the
preferred embodiment, the flange member 24 of the positioning
segment 20 preferably includes a lower edge 27 which is structured
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and disposed to engage the portion of the eye about the cornea in
a fluid impervious manner. Similarly, the retention plate 23 may
also be said to include an interior rim 26 disposed in
surrounding, defining relation about the aperture 25, and which
is structured to engage the eye disposed therein, also in a fluid
impervious manner. It will therefore be appreciated that upon the
positioning segment 20 being disposed in engaging relation with
the eye, that an effective, generally air-tight seal can be
achieved about the eyeball and a vacuum chamber 22 between
retention plate 23 and flange member 24. Additionally, as
illustrated in Figure 2, a channel 29 may also be defined in the
vacuum chamber 22, the channel 29 enhancing the effectiveness of
a vacuum applied, either alone or in combination with a rigid or
flexible insert as provided in U.S. Patent No. 5,772,675.
hooking further to the flange member 24, as it defines the
outer perimeter for engagement with the eye, in the illustrated
embodiment, the flange member 24 is disposed in more closely
spaced relation to a perimeter of the aperture 25 than is the case
in conventional positioning assemblies. Although this closer
spacing may be defined only at a latitudinal radius of the
aperture 25 in response to the reduced dimension of the narrowed
ocular access, it is generally preferred that the flange member
24 define a circular configuration which is uniformly spaced from
the aperture 25 and facilitates proper centration of the eye. In
the illustrated embodiment, the latitudinal diameter of the flange
member 24, generally at the lower edge 27 which engages the eye,
is generally between about .675 and .725 inches. More precisely,
a latitudinal diameter of less than generally about .79 inches,
or .708 inches (l8mm) is preferred to correspond an aperture 25
diameter of generally between about .350 to .475 inches, or more
precisely, .420 inches in order to form an 8.5 mm flap. For
example, the present invention, with the closely space flange
member 24 can be utilized to form a 7.5mrn, 8.5mm, 9.5mm, or other
dimension incision merely by modifying a size of the aperture to
the corresponding .375 inch, .420 inch and .465 inch diameters.
As can be appreciated, however, reducing a diameter of the flange
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member 24, while retaining a necessary sized opening, reduces the
depth to which the positioning assembly 20 can pass down onto the
eye. Still, however, it is desirable to maintain the same
diameter of the eye exposed through the cornea, and through
preferably a standard dimension aperture 25 so as to generate the
appropriately sized corneal flap. As such, the present invention
also preferably includes a reduced depth of the positioning
segment 20, as defined by the flange member 24. In the
illustrated embodiment, the depth of the positioning segment 20,
as generally defined from an upper surface of the retention plate
23 to the lower edge 27 of the flange member 24, is preferably
less than generally about .175 inches and more preferably between
about .1 to .15 inches. In the illustrated embodiment wherein a
preferred .420 inch diameter aperture 25 and .708 diameter flange
member are utilized, the preferred depth is .115 inches. As a
result of the preceding, however, a sufficient portion of the eye
is exposed through the aperture 25, and restrictions in access to
the eye based upon the physical characteristics of the patient are
obviated, with the positioning segment 20 fully and securely
engaging the surface of the eye.
The positioning assembly of the present invention is further
directed for use with and may at least partially comprise a
suctioning assembly 30 for at least temporarily attaching the
positioning segment 20 to the eye on which surgery is to be
performed once it has been properly positioned thereon.
Preferably, the suctioning assembly 30 comprises a vacuum port 32
formed in the positioning segment 20 and a vacuum assembly (not
shown) for providing a suction force. The vacuum assembly is
structured to apply a suction force which is sufficient to attach
the positioning segment 20 to the eyeball about the cornea, C, and
cause the cornea to be urged upwardly and to protrude through the
aperture 25 of the positioning segment 20, while not being so
strong as to cause damage to the eyeball. It will be appreciated
from the drawings that the vacuum port 32 formed in the
positioning segment 20 is operably coupled to and in fluid flow
communication with the vacuum assembly such that the suction force
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is applied therethrough. Specifically, a preferably removable,
externally threaded vacuum handle (not shown), which may also
provide a convenient means of grasping and manipulating the
positioning assembly 10, is preferably screwed into the vacuum
port 32 in a secure, fluid impervious manner. Indeed, such an
internally threaded configuration of at least a portion of the
vacuum port 32 ensures a more secure engagement and significantly
facilitates cleaning of the positioning assembly 10 as the vacuum
handle can be secured to ensure no gap, which could potentially
become clogged, is present therebetween, and easy access to the
interior of the vacuum port 32 can be achieved for cleaning.
Moreover, in the preferred embodiment, the vacuum port 32 extends
to an undersurface 28 of positioning segment 20 either through
retention plate 23 or flange member 24 and into the vacuum chamber
22. Thus, the vacuum port 32 is disposed to provide a suction
force, once the vacuum assembly is activated, to a point radially
exterior of the aperture 25 and radially interior of the flange
member 24, so as to form a seal about the cornea of the eye about
to undergo surgery. It should be clear at this point that the
structure of positioning segment 20, when accompanied by a suction
force, acts to properly position and align the cornea C, for
surgery and to generally maintain that position during surgery.
Typically, a vacuum of about 25 inches of Hg at aea level will be
used.
The positioning assembly 10 of the present invention also
preferably includes a guide track 40 formed thereon. The guide
track 40 is preferably formed directly on and integrally with the
positioning segment 20 so as to guide and facilitate movement of
the microkeratome cutting head assembly 15 during the surgical
cutting of the cornea. The integral machining is preferred in the
illustrated, more compact embodiment, as it ensures that a secure
and stable connection between the guide track 40 and the
positioning segment 20 is maintained at all times, and ensures
that no mis-alignment therebetween will occur as a result of
assembly and manufacturing. In particular, some positioning
assemblies include a separately machined guide track secured to
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the positioning segment 20 by one, but typically two or more
screws. Two or more screws were generally preferred because the
use of one screw might lead to improper alignment of the guide
track relative to the aperture if extreme care and precision is
5 not maintained during manufacture and assembly. Based upon the
more compact design of the illustrated embodiment, however, it is
generally impractical to include multiple screws. Accordingly,
in the illustrated more compact embodiment, as well as in other
embodiments, in order to maintain precision and ease of assembly,
10 the guide track 40 is preferably integrally formed, such as by
machining to a width of about .03 inches, with the positioning
segment. Also, referring to Figures 1 and 2, in the preferred
embodiment, the guide track 40 extends along a length of at least
one side of positioning segment 20, but preferably extends
15 latitudinally beyond the positioning segment 20 so that engagement
between the cutting head assembly and the guide track occurs at
a point before the aperture. The present invention recognizes
that although a limited dimension must be employed for the
outermost engagement by the flange member 24 with the eye, a
relatively elevated guide track 40 need not be constrained to the
same extent. The guide track 40 of the present invention is
configured to extend beyond the retention plate 23 so as to
further guide and/or stabilize the microkeratome cutting head
assembly 15 before and during a cut across the aperture 25,
thereby ensuring complete formation of the corneal flap desired
in most cases, and at a starting point before the edge of the
aperture 25. It will also be appreciated from the drawings that
the guide track 40 includes a toothed upper surface 42 and a
retaining lip 44, and extends across the positioning segment in
a generally arcuate or semi-circular path. The guide track
thereby retains and/or pins the cutting head assembly 15
operatively and downwardly engaged on the eye, and may at least
partially guide the movement of the cutting head assembly 15,
along the arcuate cutting path best illustrated in Figures 9A-9C
with regard to a left eye, such as through the engagement of a
gear structure of the cutting head assembly 15 on the toothed
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upper surface 42 of the guide track 40.
Looking once again to the vacuum port 32 of the suctioning
assembly 30, as illustrated in the Figures, it is preferably
angled outwardly away from a vertical axis of the aperture 25
and/or outwardly away from the guide track 40. As a result, when
a hose or other conduit is coupled thereto for supplying the
suction force, neither the vacuum port or the conduit will
obstruct or otherwise interfere with the movement of the cutting
head assembly 15 at least partially over the guide track 40.
Furthermore, in the illustrated embodiment, such a configuration
permits the more compact, preferably circular configuration of the
positioning segment 20 to be maintained, while still effectively
directing the suction force to the vacuum chamber 22. Moreover,
the integral formation of the guide track 40 with the positioning
segment, and generally the vacuum port 32, further contributes to
the more compact configuration, as a space for screws and/or other
fasteners need not be provided. It is also noted that the vacuum
port 32 itself preferably does not extend above a plane of the
guide track 40, also contributing to the streamlined nature of the
present positioning assembly 10.
Also in the illustrated embodiment, the present invention
also preferably includes a pivot assembly. The pivot assembly is
structured to provide increased stability to the cutting head
assembly 15 during its movement along the arcuate path, and also
preferably to define a pivot axis which can stabilize or
alternately further guide the movement of the cutting head
assembly 15 in conjunction with the guide track 40. The pivot
assembly preferably includes a post member 50. The post member
50 is preferably a rigid upstanding element disposed generally
opposite the guide track 40. As will again be appreciated from
the drawings, in the preferred embodiment, wherein positioning
assembly 10 has a tear-drop shape, a base section 55, also
preferably part of the pivot assembly, is integrally formed with
and extends from the positioning segment 20. The base section 55
provides a support surface at which the preferably separately
formed post member is secured, as will be described subsequently,
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during assembly. Moreover, from the explanation which follows,
it will become clear that guide track 40 and post member 50 permit
the cutting head assembly 15 of the invention, in a preferred
embodiment, to become effectively guided and securely received on
the positioning assembly 10 in two places, while still permitting
the cutting head assembly 15 to be smoothly and slidably moved
over the positioning segment 20 along a generally arcuate path,
by way of a pivoting motion about the pivot axis defined by the
post member 50. Of course, the positioning assembly 10 could also
be formed to include another guide track, which extends along a
length of the other side of positioning segment 20, also
preferably, on an upper surface thereof, so as to also permit the
cutting head assembly 15 of the invention to become effectively
guided and securely received on the positioning segment 2D in two
places while still permitting the cutting head assembly 15 to be
smoothly and slidable moved over positioning segment 20 along a
generally arcuate path. As a result, either the pivot assembly
and/or one or more guide tracks function to direct the arcuate
movement of the cutting head assembly 15.
Also preferably included as part of the pivot assembly is a
coupling member 70. While the cutting head assembly 15 might be
directly and yet movably engaged with the positioning segment 20
for performing an operation on the eye, preferably, the coupling
member 70 is utilized as part of the invention, which is
structured and disposed to movably and operably couple the cutting
head assembly 15 to the positioning segment 20, preferably via the
post member 50, while simultaneously permitting movement of the
cutting head assembly 15 relative to positioning segment 20. As
illustrated in Figure 3, the coupling member 70 preferably
comprises two segments: a) a retaining segment 72 and b) a pivot
segment 74. The retaining segment 72 is preferably structured and
disposed to be fitted onto a top surface of the cutting head
assembly 15 so as to be effectively and removably secured thereto,
and move in association with the movement of the cutting head
assembly 15. Turning to the pivot segment 74 of coupling member
70, it is structured and disposed to be coupled to the post member
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50 and to permit coupling member 70, and accordingly, the cutting
head assembly 15 connected thereto, to pivotally move about the
pivot axis. Preferably, the pivot segment 74 includes a bushing
having a bore 75 formed therein, which is sized to receive a
substantial height of the post member 50, thereby captivating it
therein.
Looking once again to the pivot assembly, and preferably the
post member 50 thereof, it preferably defines a cut origination
control. The cut origination control is structured to define at
least one origination point, as in Figure 9A, at which operative
pivotal movement of the coupling member 70, and accordingly the
cutting head assembly 15, about the pivot axis commences. In
particular, the cut origination control is configured to
substantially ensure that the cutting head assembly 15 cannot
engage the eye and/or the guide track 40, such that an incision
can be formed, unless it is properly disposed an appropriate
origination point. Additionally, the cut origination control
ensures that the cutting head assembly 15 is not positioned so as
to begin to cut the retention plate 23, eye lid and/or other
instruments and articles disposed peripherally to the aperture 25
and the eye. In the illustrated embodiment, the cut origination
control includes at least one, but preferably a pair of slots 51,
52 defined in the post member 50. The slots 51, 52, which are
preferably, but not necessarily, generally vertically oriented,
each define an origination point, such as for the left and right
eye, and in the illustrated embodiment are disposed at an angular
separation of approximately 100 degrees from center line to center
line. In particular, as the positioning assembly 10 of the
present invention is structured preferably for use on either eye,
as illustrated in Figure 8, a different origination point on
opposite sides of the positioning segment 20 must be defined
depending upon the direction of travel. In either instance,
however, the slot 51, 52 is structured to at least partially
receive a restrictor element 78 defined preferably in the bore 75
of the coupling member 70. Specifically, the restrictor element
is structured and disposed to fit within a corresponding slot 51,
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52, but to restrict passage of the coupling member 70 onto the
post member 50 if they are not properly aligned. Along these
lines, it is noted that multiple and/or more elaborate
configurations could be equivalently utilized so as to provide the
restriction if the members are not aligned. Furthermore, although
inadvertent passage of the restrictor element 78 into the
incorrect slot 51, 52 could result, the necessary positioning of
said slots 51, 52 is such that the cutting head assembly 15 would
be disposed with its blade beyond the aperture 25 such that an
improper cut could still not result.
Because the orientation of the slots 51, 52 relative to the
positioning segment 20 generally defines the location of the
origination point, it is necessary to ensure that the post member
50 be secured to the base section 55 in a precisely aligned
manner. Although a multiple screw configuration could be utilized
to provide a certain degree of precision alignment, in the
illustrated embodiment, the post member 50 includes an alignment
segment 57 structured to operatively engage the base section 55
so as to ensure properly axially aligned securement of the post
member 50 thereto. In particular, the base section 55 includes
an alignment edge 56 which is matingly engaged by the alignment
segment 57 of the post member 50. In the illustrated embodiment,
the alignment segment 57 and alignment edge 56 are straight
surfaces which can be confrontingly engaged to provide the aligned
securement, however, other mating configurations could also be
employed. Based upon the preceding structure, however, proper,
precise aligned securement of the post member 50 on the base
section 55 can be achieved, such as through the passage of a
fastener element through an opening 55' in the base section 55 and
to the post member 50.
As a result, based upon the preceding, the cutting head
assembly 15 cannot engage the eye unless it is at the appropriate
starting point. Furthermore, however, so as to permit the
requisite pivotal movement between the post member 50 and the
coupling member 70, a channel 58 is preferably formed in the post
member 50 so as to permit slided passage of the restrictor element
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78 therethrough during pivotal movement of the coupling member 70,
and accordingly the cutting head assembly 15 relative to the post
member 50. It is of course understood that the restrictor member
could be equivalently disposed on the post member, with the
S slots) defined in the coupling member. In either configuration,
however, the channel 58 also functions to ensure that the coupling
member 70 does not pivot relative to the post member 50, but
rather that it is pinned down into a uniform plane of motion in
much the same manner that the retaining lip 44 pins down the
cutting head assembly 15 at the guide track 40.
Since many modifications, variations and changes in detail
can be made to the described preferred embodiment of the
invention, it is intended that all matters in the foregoing
description and shown in the accompanying drawings be interpreted
in the illustrative and not in a limiting sense. Thus, the scope
of the invention should be determined by the appended claims and
their legal equivalents.
Now that the invention has been described,
