U.S. patent application number 09/841165 was filed with the patent office on 2002-07-11 for automatic surgical device for cutting a cornea.
Invention is credited to Hellenkamp, Johann F..
Application Number | 20020091401 09/841165 |
Document ID | / |
Family ID | 24394558 |
Filed Date | 2002-07-11 |
United States Patent
Application |
20020091401 |
Kind Code |
A1 |
Hellenkamp, Johann F. |
July 11, 2002 |
Automatic surgical device for cutting a cornea
Abstract
A surgical device for cutting substantially across a cornea of
an eye of a patient, the device including a positioning ring
structured to be temporarily attached to a portion of the eye
surrounding the cornea to be cut, and defining an aperture sized to
receive and expose the cornea to be cut. The surgical device
further includes a cutting head assembly structured to be guided
and driven over an upper surface of the positioning ring in a
generally arcuate path, and having a cutting element positioned
therein and structured to oscillate laterally to facilitate smooth
and effective cutting of the cornea. The cutting head assembly is
structured to be detachably coupled to the positioning ring while
simultaneously permitting movement of the cutting head assembly
relative to the positioning ring along the generally arcuate
path.
Inventors: |
Hellenkamp, Johann F.;
(Miami, FL) |
Correspondence
Address: |
MALLOY & MALLOY, P.A.
2800 S.W. Third Avenue
Historic Coral Way
Miami
FL
33129
US
|
Family ID: |
24394558 |
Appl. No.: |
09/841165 |
Filed: |
April 24, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09841165 |
Apr 24, 2001 |
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08840430 |
Apr 29, 1997 |
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6296649 |
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08840430 |
Apr 29, 1997 |
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08598180 |
Feb 7, 1996 |
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5624456 |
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Current U.S.
Class: |
606/166 |
Current CPC
Class: |
A61F 2009/0052 20130101;
A61B 34/10 20160201; A61F 9/013 20130101 |
Class at
Publication: |
606/166 |
International
Class: |
A61F 009/00 |
Claims
What is claimed is:
1. A method for cutting a cornea portion of an eye comprising the
steps of: temporarily maintaining the eye in an immobile, cornea
exposed orientation, and driving a cutting element across the
cornea along an arcuate path from a lower region of the cornea to
an upper region of the cornea so as to at least partially cut the
cornea and such that normal, post-operative blinking of the eye
results to substantially advance healing of the eye.
2. A method for cutting a cornea portion of an eye as recited in
claim 1 further including a step of defining said arcuate path
along the cornea prior to driving said cutting element
therealong.
3. A method for cutting a cornea portion of an eye comprising the
steps of: temporarily maintaining the eye in an immobile, cornea
exposed orientation, and driving a cutting element across the
cornea so as to at least partially cut the cornea and so as to
define a generally horizontally disposed corneal flap at an upper
region of said cornea.
4. A method for cutting a cornea portion of an eye as recited in
claim 3 further including a step of defining an arcuate path along
the cornea and driving said cutting element along said arcuate
path.
5. A method for cutting a cornea portion of each of a patient's
eyes comprising the steps of: temporarily and selectively
maintaining each of the patient's eyes in an immobile, cornea
exposed orientation, and driving a cutting element across the
cornea of each eye so as to at least partially cut the cornea of
each eye and so as to define a corneal flap remaining attached at a
hinge on an upper region of said cornea of each eye, with said
hinge being disposed in generally transverse relation to a
direction of normal, post-operative blinking of each of the
eyes.
6. A surgical device for cutting across a cornea of an eye of a
patient, said device comprising: a) a positioning ring structured
to be at least temporarily attached to a portion of the eye
surrounding the cornea to be cut; said positioning ring defining an
aperture; b) said positioning ring including a guide assembly
defining a generally arcuate path; c) a cutting head assembly
including a cutting element for cutting the cornea; and d) said
cutting head assembly structured to move over said positioning ring
along said generally arcuate path defined by said guide
assembly.
7. A surgical device as recited in claim 6 wherein said cutting
path defined by said guide assembly terminates at an upper portion
of the cornea of both the patient's left and right eye.
8. A surgical device as recited in claim 6 wherein said cutting
head assembly is structured for automated movement over said
positioning ring.
9. A surgical device for cutting across a cornea of an eye of a
patient, said device comprising: a) a positioning ring structured
to be at least temporarily attached to a portion of the eye
surrounding the cornea to be cut; said positioning ring defining an
aperture; b) said positioning ring including a guide assembly
defining a generally arcuate path; c) said guide assembly including
at least a post member structured to define an axis of rotation for
said generally arcuate path; d) a cutting head assembly including a
cutting element for cutting the cornea; and e) said cutting head
assembly structured to be at least temporarily operatively coupled
to said post member and to move over said positioning ring along
said generally arcuate path.
10. A surgical device as recited in claim 9 further including a
coupling member structured and disposed to detachably couple said
cutting head assembly to at least said post member and to permit
movement of said cutting head assembly relative to said positioning
ring along said generally arcuate path.
11. A surgical device for cutting across a cornea of an eye of a
patient, said device comprising: a) a positioning ring structured
to be at least temporarily attached to a portion of the eye
surrounding the cornea to be cut; said positioning ring defining an
aperture; b) said positioning ring including a guide assembly
defining a generally arcuate path; c) said guide assembly including
at least a post member disposed on said positioning ring and
structured to define an axis of rotation for said generally arcuate
path; d) a cutting head assembly including a cutting element for
cutting the cornea; and e) said cutting head assembly at least
temporarily operatively coupled to said post member and structured
to move over said positioning ring along said generally arcuate
path.
12. A surgical device as recited in claim 11 wherein said post
member is disposed over the patient's eye on said positioning
ring.
13. A surgical device for cutting across a cornea of an eye of a
patient, said device comprising: a positioning assembly structured
to position the cornea of the eye in an exposed, cuttable
orientation; and a cutting head assembly including a cutting
element for cutting the cornea, said cutting head assembly
structured to move over the cornea along a cutting path which
terminates in generally aligned relation with a direction of normal
postoperative blinking of the eye.
14. A surgical device as recited in claim 13 wherein said cutting
path which terminates in generally aligned relation with the
direction of normal post-operative blinking of the eye is defined
by a generally arcuate path.
15. A surgical device as recited in claim 13 wherein said cutting
path terminates at an upper portion of the cornea of both the
patient's left and right eye.
16. A surgical device for cutting across a cornea of an eye of a
patient, said device comprising: a positioning assembly structured
to position the cornea of the eye in an exposed, cuttable
orientation; and a cutting head assembly including a cutting
element for cutting the cornea, said cutting head assembly
structured to move over and cut the cornea and to define a corneal
flap secured at generally an upper region of the eye.
17. A surgical device for selectively cutting across a cornea of
each of the eyes of a patient, said device comprising: a
positioning assembly structured to selectively and at least
temporarily position the cornea of each of the eyes in an exposed,
cuttable orientation; a cutting head assembly including a cutting
element for cutting the cornea; and said cutting head assembly and
said positioning ring being cooperatively structured with one
another so as to selectively move said cutting head assembly over
the cornea of each of the eyes along a cutting path which
terminates in generally aligned relation with a direction of normal
post-operative blinking of each of the eyes.
18. A surgical device as recited in claim 17 wherein said cutting
path which terminates in generally aligned relation with the
direction of normal post-operative blinking of the eye is defined
by a generally arcuate path.
19. A surgical device for cutting across a cornea of an eye of a
patient, said device comprising: a) a positioning ring structured
to be at least temporarily attached to a portion of the eye
surrounding the cornea to be cut; said positioning ring defining an
aperture; b) said positioning ring including a guide assembly
defining a cutting path which terminates in generally aligned
relation to a direction of normal post-operative blinking of the
eye; c) a cutting head assembly including a cutting element for
cutting the cornea, said cutting head assembly being structured and
disposed to be driven across said positioning ring along said
cutting path defined by said guide assembly; and d) a drive
assembly operably connected to said cutting head assembly for
causing movement of said cutting head assembly across said
positioning ring and for causing oscillating movement of said
cutting element.
20. A surgical device for selectively cutting across a cornea of
each eye of a patient, said device comprising: a) a positioning
ring having means for selectively and at least temporary attachment
to a portion of the eye surrounding the cornea to be cut; said
positioning ring defining an aperture; b) said positioning ring
including a guide assembly defining a cutting path which terminates
in generally aligned relation to a direction of normal
post-operative blinking of the eye; c) said guide assembly
including at least a post member structured to define an axis of
said cutting path; and d) a cutting head assembly including a
cutting element for cutting the cornea, said cutting head assembly
being operatively coupled to said post member and structured and
disposed to be selectively driven across said positioning ring
along said cutting path which terminates generally in aligned
relation with said direction of normal post-operative blinking of
each of the eyes.
21. A surgical device as recited in claim 20 wherein said guide
assembly further comprises a guide track.
22. A method for cutting a cornea portion of a either eye
comprising the steps of: selecting an eye whose cornea is to be
cut, identifying whether the selected eye is a left eye or a right
eye; temporarily maintaining the selected eye in an immobile,
cornea exposed orientation, positioning a cutting element on the
selected eye in accordance with whether the selected eye is a left
or right eye, driving a cutting element forward across the cornea
along an arcuate path which, at least partially as a result of the
positioning of the cutting element, is from a lower region of the
cornea to an upper region of the cornea and at least partially cuts
the cornea to define a generally horizontally disposed corneal flap
at an upper region of said cornea.
23. A method for cutting a cornea portion of an eye comprising the
steps of: temporarily maintaining the eye in an immobile, cornea
exposed orientation, moving a cutting element across the cornea
from a lower region of the cornea towards an upper region of the
cornea, cutting the cornea with the cutting element at least during
a portion of its movement so as to define a corneal flap, stopping
the cutting element in the upper region of the cornea prior to
complete severing of the corneal flap, and removing the cutting
element from engaging relation with the cornea while the corneal
flap remains connected to the cornea at a generally horizontal
segment in the upper region of the cornea.
24. A method for cutting a cornea portion of an eye comprising the
steps of: temporarily maintaining the eye in an immobile, cornea
exposed orientation utilizing a positioning ring, driving a cutting
element over the positioning ring across the cornea so as to at
least partially cut the cornea and so as to define a generally
horizontally disposed corneal flap at an upper region of said
cornea, and removing the cutting element from a cornea engaging
relation with the positioning ring.
25. A method for cutting a cornea portion of an eye comprising the
steps of: positioning a cutting element on a positioning ring
structured to at least temporarily maintain the eye in an immobile,
cornea exposed orientation, driving a cutting element over the
positioning ring so as to at least partially cut the cornea and so
as to define a generally horizontally disposed corneal flap at an
upper region of said cornea, and removing the cutting element from
the positioning ring.
26. The method of claim 25 wherein removing the cutting element
from the positioning ring further comprises removing the cutting
element from the positioning ring while maintaining the positioning
ring in engaging relation with the eye.
27. A surgical device for cutting across a cornea of an eye of a
patient, said device comprising: a) a positioning ring structured
to be at least temporarily attached to a portion of the eye
surrounding the cornea to be cut; b) said positioning ring
including a guide assembly defining a generally arcuate path; c) a
cutting head assembly including a cutting element for cutting the
cornea; and d) said cutting head assembly and said positioning ring
being structured to operably associated with one another such that
said cutting head assembly moves over said positioning ring along
said generally arcuate path defined by said guide assembly from
generally a lower region of the cornea to an upper region of the
cornea of either a left eye or right eye.
28. A surgical device for cutting across a cornea of an eye of a
patient, said device comprising: a) a positioning ring structured
to be at least temporarily attached to a portion of the eye
surrounding the cornea to be cut as a result of a vacuum; b) said
positioning ring including a guide assembly defining a generally
arcuate path; c) a cutting head assembly including a cutting
element for cutting the cornea; d) said cutting head assembly
structured to move over said positioning ring along said generally
arcuate path defined by said guide assembly; and e) said cutting
head assembly structured to be removed from said positioning ring
without interrupting said vacuum.
29. A surgical device for cutting across a cornea of an eye of a
patient, said device comprising: a) a positioning ring structured
to be at least temporarily attached to a portion of the eye
surrounding the cornea to be cut; b) said positioning ring
including a guide assembly defining a generally arcuate path; c)
said guide assembly including at least a post member structured to
define an axis of rotation for said generally arcuate path; d) a
cutting head assembly including a cutting element for cutting the
cornea; e) said cutting head assembly structured to be selectively
coupled to said post member in an orientation corresponding a left
eye or a right eye, and to move over said positioning ring along
said generally arcuate path.
30. A surgical device for cutting across a cornea of an eye of a
patient, said device comprising: a) a positioning ring structured
to be at least temporarily attached to a portion of the eye
surrounding the cornea to be cut by a vacuum; b) said positioning
ring including a guide assembly defining a generally arcuate path;
c) said guide assembly including at least a post member structured
to define an axis of rotation for said generally arcuate path; d) a
cutting head assembly including a cutting element for cutting the
cornea; and e) said cutting head assembly structured to be
removably coupled to said post member without interruption of said
vacuum at said positioning ring and to move over said positioning
ring along said generally arcuate path.
31. A surgical device for cutting across a cornea of either eye of
a patient, said device comprising: a positioning assembly
structured to position the cornea of either eye in an exposed,
cuttable orientation; and a cutting head assembly including a
cutting element for cutting the cornea, said cutting head assembly
structured to move over the positioning assembly and cut the cornea
of the selected eye to define a corneal flap secured at generally
an upper region of the eye in generally aligned relation with a
direction of normal post-operative blinking of the selected
eye.
32. A surgical device for cutting across a cornea of either eye of
a patient, said device comprising: a) a positioning ring structured
to be at least temporarily attached to a portion of the eye
surrounding the cornea to be cut; b) said positioning ring
including a guide assembly, said guide assembly structured to
define a cutting path which terminates at an upper portion of the
cornea in generally aligned relation to a direction of normal
post-operative blinking of either of the eyes on which said
positioning ring is disposed; c) a cutting head assembly including
a cutting element for cutting the cornea, said cutting head
assembly being structured to be driven across said positioning ring
along said cutting path defined by said guide assembly towards said
upper portion of the cornea of the eye on which said positioning
ring is disposed; and d) a drive assembly operably connected to
said cutting head assembly for causing movement of said cutting
head assembly across said positioning ring and for causing
oscillating movement of said cutting element.
33. A surgical device for selectively cutting across a cornea of
each eye of a patient, said device comprising: a) a positioning
ring structured to be selectively and at least temporary attached
to a portion of the eye surrounding the cornea to be cut by a
vacuum; b) said positioning ring including a vacuum port through
which said vacuum is applied; c) said positioning ring further
including a guide assembly defining a cutting path which terminates
in generally aligned relation to a direction of normal
post-operative blinking of the eye; d) said guide assembly
including at least a post member independent from said vacuum port
and structured to define an axis of said cutting path; and e) a
cutting head assembly including a cutting element for cutting the
cornea, said cutting head assembly being operatively coupled to
said post member and structured and disposed to be selectively
driven across said positioning ring along said cutting path which
terminates generally in aligned relation with said direction of
normal post-operative blinking of each of the eyes.
34. The surgical device of claim 33 wherein said cutting head
assembly is removably coupled to said post member.
Description
Claim of Priority
[0001] The present application is a Continuation application of
previously filed, now pending application having Ser. No.
08/840,430 which was filed on Apr. 29, 1997, which is a
Continuation-In-Part of U.S. patent application having Ser. No.
08/598,180 filed Feb. 7, 1996, also incorporated herein by
reference, which matured into U.S. Pat. No. 5,624,456 on Apr. 29,
1997.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a medical apparatus used
during the performance of eye surgery. In particular, the present
invention is directed towards an automatic surgical device for
cutting the cornea of a patient's eye and creating a hinged flap of
corneal tissue. More particularly, the automatic surgical device of
this invention includes a cutting head assembly which is
specifically structured to move across the patient's eye along a
generally arcuate path, and further, is readily usable on both eyes
of the patient.
[0004] 2. Description of the Related Art
[0005] The eye works on a principle very similar to that of a
camera and is illustrated generally in FIG. 1. The iris I, or
colored portion of the eye about the pupil P, functions like a
shutter to regulate the amount of light admitted to the interior of
the eye. The cornea C or clear window of the eye, and the lens L,
which is located behind the pupil, serve to focus the light rays
from an object being viewed onto the retina R at the back of the
eye. The retina then transmits the image of the object viewed to
the brain via the optic nerve, O. Normally, these light rays will
be focused exactly on the retina, see dashed lines in FIGS. 2 and
3, which permits the distant object to be seen distinctly and
clearly. Deviations from the WA 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. As one example, illustrated in FIG.
2, hyperopia or "farsightedness" is an error of refraction in which
the light rays from a distant it object are brought to focus at a
point behind the retina, as indicated by the solid lines. As
another example, illustrated in FIG. 3, myopia or "nearsightedness"
is an error of refraction in which the light rays from a distant
object are brought to focus in front of the retina, as indicated by
the solid lines, such that when the rays reach the retina, R, they
become divergent, forming a circle of diffusion and consequently, a
blurred image.
[0006] Until about twenty years ago, such refractive errors could
only be treated with eyeglasses or contact lens, both of which have
well known disadvantages for the user. As one example, a patient
having a large degree of refractive error will commonly be
prescribed to wear a very thick and cumbersome pair of glasses,
which the patient should wear at all times to correct his/her
extremely poor vision. As another example, contact lenses, which
are designed to fit directly over the cornea, can be difficult to
insert and remove, and in any event, must be carefully cleaned and
cared for. Even then, contact lenses may at times irritate the eyes
of those patients who can wear them.
[0007] Consequently, in the last several years, research has been
directed to surgical operations to change the refractive condition
of the eye. Several methods and special instruments have been
designed for performing this kind of surgery. One such technique
was keratomileusis, developed by Dr. Jose Barraquer of Colombia in
1949, which required a precise reshaping of the cornea. 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, with the desired result being that light rays
passing through the cornea will then be refracted to converge
directly onto the retina. Keratomileusis was extremely difficult to
perform because it required cutting the cornea to separate and
remove a thin layer or section of corneal tissue from a patient's
eye, termed the corneal cap, precise lathing of it into a new
shape, and then replacing it and suturing it back onto the
patient's cornea.
[0008] Keratomileusis has been abandoned in recent years to
eliminate the requirement of lathing the corneal tissue and
suturing it back into place. Automated Lamellar Keratectomy (ALK)
is another surgical technique which developed as an outgrowth of
keratomileusis, wherein the eye is first numbed by a drop of
anesthetic, and then a suction ring 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 suction ring simultaneous with the
motorized movement of the cutting element, which movement is
transverse to the direction of the cutting path. For treating
myopia pursuant to ALK procedures, the microkeratome is typically
used to first cut into the cornea so as to raise a thin layer of
the anterior cornea of between 100-200 microns in depth and about 7
millimeters in diameter. Next, the microkeratome is then used to
make a second pass over the cornea to resect or remove a smaller
part of the cornea, generally about 4 to 6 millimeters in diameter,
which is then discarded. The anterior corneal cap which was cut
away with the first pass of the microkeratome is then put back into
its original position, without suturing, for healing to occur. The
desired result of this procedure is that the cornea will have a new
curvature because of the resected tissue, which provides a new
refracting surface to correct the patient's original myopic
condition. To correct hyperopia under ALK however, the
microkeratome is typically used to make a single deep pass over the
cornea. The cut layers are put back into their original position,
without any removal of any other tissue. Because of the depth of
the cut, the intraocular pressure within the eye causes a
steepening of the cornea to again, provide a new refracting surface
which hopefully will correct the patient's original hyperopic
condition.
[0009] In recent years, it has been learned that in using the
microkeratome to cut and separate a thin layer of the cornea,
termed the anterior corneal cap, it is highly undesirable to
completely separate this cap from the rest of the cornea. First,
the corneal cap has been lost in some instances which is calamitous
because the anterior segment of the eye must then be completely
reconstructed. Second, it is also now known that following the
reshaping of the cornea, the corneal cap should be carefully and
precisely aligned back into its original position on the cornea;
failure to do so may result in astigmatism or some unbeknownst
refractive error. Consequently, it is now understood that the
microkeratome should not sever the cap from the eye but instead,
should leave a portion connected or "hinged" to the eye, thereby
forming a raised layer of corneal tissue hinged to the eye, known
as a corneal flap F, illustrated in FIG. 4. A significant problem
however, is that presently known microkeratome devices do not
readily permit the formation of a corneal flap, F. Instead, known
microkeratomes involve a degree of guesswork for determining where
on the eye to stop cutting movement of the microkeratome across the
cornea so as to form the corneal flap. Further, there are multiple
issues that a surgeon needs to consider in corneal flap
construction, the three most important factors being: flap
thickness, flap size and hinge size.
[0010] Another advance has been made in more recent years in
surgical procedures to correct refractive errors of the eye,
namely, the introduction of laser procedures to accomplish the
reshaping of the cornea. One such procedure, known as Laser
Intrastromal Keratomileusis, (LASIK), is currently considered
optimal because it allows sculpting of the cornea without damaging
adjacent tissues. Moreover, with the aid of computers, the laser
can be programmed by a surgeon to 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 suction ring and a microkeratome is
typically used to cut into the cornea so as to raise a thin layer
of the cornea. As described, it is now preferred that a corneal
flap be formed. Significantly, it has been determined that the
corneal flap should have a depth of no less than 130 microns and no
more than 160 microns to yield optimal results. It should be borne
in mind that achieving this result during surgery requires an
extremely precise instrument as one micron is a unit of length
equal to one thousandth of a millimeter. During laser surgery, the
flap of corneal tissue is then gently pushed aside to expose and
permit reshaping of the cornea by the laser. Consequently, the
microkeratome is less frequently used to reshape the cornea, as
occurred under ALK procedures, but is still used to cut into and to
raise a thin layer of corneal tissue. A significant problem
however, is that presently known microkeratome devices do not offer
the degree of precision currently needed to properly and
consistently form a corneal flap, instead of a corneal cap, let
alone a corneal flap having a dimension within the range of
currently desirable depth and a vastly improved smooth cut.
Further, it has been determined that a larger diameter of the eye
should be presented, as much as 8 to 10 millimeters, for corneal
reshaping by the laser. This is because the laser can now be used
to re-shape the corneal surface about a perimeter of the eye rather
than at the center, which is believed to result in more accurate
correction of refractive errors. Doing so however, requires that a
sufficiently large diameter of the eye be presented and exposed,
which is not possible to achieve with known microkeratome devices.
For example, known suction rings for positioning the eye during
surgery would likely require a greatly expanded frame, and that
that frame be located lower on and about the girth of the eyeball,
in order to expose a greater portion thereof. Such an assembly
would likely be very difficult to employ given the physical space
limitations of the eye socket.
[0011] Finally, known microkeratome devices typically cut across
the cornea in a linear direction along a horizontal plane. That is,
known microkeratome devices typically cut across the cornea in a
direction starting from the side of the eye near the temple,
proceeding horizontally across the face towards the nose. As a
result, even if such microkeratomes were able to be effectively
used to construct a corneal flap, let alone one of the currently
desired more precise dimensions, the hinged portion of the corneal
flap would be oriented at right angles to the natural blinking
action of the patient, which is in the vertical plane. It is
believed that it would be most optimal to construct a corneal flap
having a hinged portion which is oriented to correspond with the
natural blinking action of the patient in the vertical plane. It is
however, believed that known microkeratomes cannot move linearly in
a vertical plane because of the restrictions presented by the size
of the eye socket formed by the cheek and brow bones of the human
skull.
[0012] Thus, there is a need for an improved automated
microkeratome which automatically and consistently permits the
formation of a corneal flap, and which allows for even more precise
construction of the corneal flap so as to result in a flap
thickness of no less than 130 microns and no more than 160 microns,
and a flap size between 8 and 10 millimeters in diameter. There is
also a need for an improved automated microkeratome which more
smoothly cuts across the cornea in forming the corneal flap so as
to permit it to be precisely aligned back into its original
position on the cornea following the reshaping of the cornea.
Ideally, any such improved automated microkeratome will also permit
construction of the corneal flap in such a way that the hinged
portion of the flap will be oriented to correspond the natural
blinking of the eye.
SUMMARY OF THE INVENTION
[0013] The present invention is designed to satisfy the needs in
the art and is directed towards a new and improved automatic
surgical device known as a microkeratome. The improved
microkeratome of the present invention is adapted to cut and raise
a thin layer of the cornea of a patient's eye and to create a
hinged flap of corneal tissue. The present invention is seen to
comprise means for retaining and positioning the eye on which
surgery is to be performed, a cutting head assembly including a
cutting element positioned therein for cutting the cornea of the
eye, and a coupling member for detachably coupling the retaining
and positioning means and cutting head assembly while permitting
movement of the cutting head assembly relative to the retaining and
positioning means along a generally arcuate path.
[0014] In the preferred embodiment, the retaining and positioning
means comprise a positioning ring having means for temporary
attachment to a portion of the eye surrounding the cornea to be
cut, and which expose and present the cornea for cutting. The
positioning ring includes guide means thereon, preferably disposed
on an upper surface thereof and extending in a generally arcuate
path.
[0015] The cutting head assembly of the present invention is
structured and disposed to be at least partially received in the
guide means of the retaining and positioning means and to be driven
substantially but not completely over the cornea of the eye so as
to cut the cornea and form a corneal flap. The cutting head
assembly is also structured and disposed to be guided by the guide
means on the retaining and positioning means along a generally
arcuate path during movement of the assembly thereacross. The
cutting head assembly is seen to comprise a main housing which
carries a cutting element positioned therein and disposed for
cutting and raising the corneal flap. In the preferred embodiment,
the cutting head assembly includes a flap receiving gap formed
within an undersurface thereof forward of the cutting element for
protectively receiving the corneal flap of tissue formed by the
forward movement of the cutting head assembly. Further, the cutting
head assembly is structured and disposed to be movably coupled to
the positioning ring by way of a coupling member which detachably
couples the cutting head assembly and the positioning ring and yet,
permits movement of the cutting head assembly relative to the
positioning ring along a generally arcuate path. The present
invention further comprises driving means for driving the cutting
head assembly over the retaining and positioning means, and in the
preferred embodiment, includes stop means, which are structured and
disposed to limit movement of the cutting head assembly across the
retaining and positioning means. The stop means may be formed on
the cutting head assembly and may be structured and disposed to
engagingly abut the guide means of the retaining and positioning
means so as to limit further movement of the cutting head assembly
at a point before the cutting element has passed completely over
the cornea of the eye, thereby forming a corneal flap on the eye
undergoing surgery. In the preferred embodiment, the drive means
are operably connected to the cutting head assembly at a top
surface thereof and are capable of stopping and reversing the
direction of movement of the cutting head assembly once the stop
means have prevented movement of the cutting head assembly in a
first direction across the retaining and positioning means.
[0016] A primary object of the present invention is to provide an
improved automated surgical device, for cutting and raising a thin
layer of tissue from the cornea of an eye undergoing surgery,
without completely severing the layer from the cornea of the eye,
thereby creating a corneal flap.
[0017] Another primary object of the present invention is to
provide an improved automated surgical device which forms a corneal
flap wherein the hinged portion of the flap is oriented so as to
cooperate with the blinking of the eye, and thereby, assist proper
repositioning and alignment of the corneal flap on the cornea
following surgery.
[0018] It is also an object of the present invention to provide an
improved automated surgical device which permits a surgeon to more
precisely and consistently construct a corneal flap and to obtain a
flap thickness of not less than 130 microns and not more than 160
microns.
[0019] A feature of the present invention is that it permits a
surgeon to expose a diameter of the cornea which is between 8 to 10
millimeters, and ideally about 9.5 millimeters, so as to permit the
construction of a relatively large diameter flap size which is
preferable in reshaping a cornea utilizing laser procedures.
[0020] Another object of the present invention is to provide an
improved automated surgical device which more smoothly cuts across
the cornea in forming the corneal flap so as to permit the flap to
be more precisely aligned back into its original position on the
cornea following the reshaping of the cornea.
[0021] A further object of the present invention is to provide an
improved automated surgical device which can be readily used on
either a patient's left or right eye.
[0022] Still another object of the present invention is to provide
an improved automated surgical device having a center of gravity
during operation which is substantially centered over the patient's
eye.
[0023] An additional object of the present invention is to provide
an improved automated surgical device which exposes and permits
cutting of a larger diameter across the eye without a greatly
expanded assembly for positioning the eye.
[0024] Yet another object of the present invention is to provide an
improved automated surgical device which as a result of its arcuate
path of travel, facilitates the formation of a larger diameter cut
to the cornea, without having to locate the assembly positioning
the eye to a lower position about the eye.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] 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:
[0026] FIG. 1 is a schematic illustration of a horizontal section
of the eye;
[0027] FIG. 2 is a schematic illustration of a hyperopic eye
wherein refracted rays converge at a point behind the retina;
[0028] FIG. 3 is a schematic illustration of a myopic eye wherein
refracted rays converge at a point which is short of the
retina;
[0029] FIG. 4 is schematic illustration of a cornea of an eye
wherein a corneal flap has been created.
[0030] FIG. 5-A is a perspective view of an embodiment of the
retaining and positioning means according to the present invention,
namely a positioning ring;
[0031] FIG. 5-B is an exploded perspective view of a preferred
embodiment of the retaining and positioning means according to the
present invention, which include a positioning ring having guide
means and a toothed track;
[0032] FIG. 5-C is a cross sectional view of the retaining and
positioning means shown in FIG. 5-B;
[0033] FIG. 6 is an exploded perspective view of the cutting head
assembly according and the coupling member according to the At
present invention;
[0034] FIG. 7 is a side view of the present invention in assembled
form and in position on a patient's cornea;
[0035] FIG. 8 is a partial cross sectional view of the present
invention in assembled form and in position on a patient's
cornea;
[0036] FIGS. 9-A, 9-B and 9-C are partial, cross sectional views
taken along the plane of the arrowed lines 9-9 of FIG. 8, and
illustrating sequential views during the cutting of the cornea in
which:
[0037] FIG. 9-A illustrates the cutting head assembly in an initial
position in contacting relation with the positioning ring and the
guide means thereon;
[0038] FIG. 9-B illustrates the cutting head assembly moving
through an intermediate position where cutting of the cornea
occurs;
[0039] FIG. 9-C illustrates the cutting head assembly in a movement
stopped position wherein the abutting or stop means are in
contacting relation with the guide means of the positioning
ring;
[0040] 12 FIG. 10-A is a front schematic illustration of the
present invention in use on both a patient's left and right eyes
and illustrating the cutting head assembly in the initial
position;
[0041] FIG. 10-B is also a front schematic illustration of the
present invention in use on both a patient's left and right eyes
and depicting the cutting head assembly in the movement stopped
position, wherein a corneal flap has been formed with the resulting
hinged portion being oriented so as to cooperate with the blinking
of the eye following surgery; and
[0042] FIG. 11 is an isolated perspective view of the drive means
illustrating the operation and interconnection of the worm, worm
gear, and oscillating shaft.
[0043] Like reference numerals refer to like parts throughout the
several views of the drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0044] Illustrated throughout the drawings, the present invention
is a mechanical apparatus used in the performance of surgery on the
eye, and is generally indicated as 10 in FIGS. 10-A and 10-B. More
specifically, the invention is directed towards an automatic
surgical device, known as a microkeratome, to be utilized on an eye
which is about to undergo surgery to correct refractive errors of
the eye such as hyperopia, myopia or astigmatism. The improved
microkeratome of the present invention is structured to cut
substantially but not completely across the cornea of a patient's
eye so as to raise a thin layer thereof and create a hinged flap of
corneal tissue. The hinged portion of corneal tissue created by the
present invention is also oriented so as to cooperate with the
blinking of the eye following surgery.
[0045] Referring now to FIGS. 5-A, 5-B, and 5-C, the device 10
includes means 30 for retaining and positioning the eye on which
surgery is to be performed. The retaining and positioning means 30,
which may be made of high grade stainless steel, preferably
comprise a positioning ring 32 having an aperture 33 formed
therein. The aperture 33 is sized to permit the cornea C, of the
eye to pass therethrough and be exposed, as depicted in FIG. 5-C.
In the preferred embodiment, and as illustrated in the drawings,
positioning ring 32 is defined by a generally tear-drop shape,
which is readily suited for accommodating the movement of a cutting
head assembly, 50, discussed below, along an arcuate path, and
further, which is structured and disposed to present the cornea so
that a diameter of generally about 8 to 10 millimeters may be cut.
The positioning ring 32 could, however, be formed to have another
shape and still function for the intended purpose.
[0046] Positioning ring 32 further includes means for being
temporarily attached to a portion of the eye surrounding the cornea
on which surgery is to be performed. Ideally, the temporary
attachment means include suctioning means. For example, positioning
ring 32 preferably includes a connection member 37, which as
illustrated in FIG. 5-C, is in fluid communication with an
undersurface of positioning ring 32. Connection member 37 is
adapted to be interconnected with a vacuum hose (not shown) which
in turn may be connected to a vacuum means (also not shown) such
that when suction occurs, the undersurface of positioning ring 32
forms a seal about and is retained about the cornea portion of the
eye which is about to undergo surgery. Further, the structure of
positioning ring 32, accompanied by the suctioning, acts to
properly position the cornea C, for surgery and to maintain the
position during surgery as well. Typically, a vacuum of about 25
inches of Hg at sea level will be used.
[0047] The retaining and positioning means 30 further include guide
means or a guide assembly 40 formed thereon. Guide means 40 may be
formed directly on the positioning ring 32, so as to be integral
therewith, or may be operably connected thereto as a separate
element. In any event however, the guide means 40 will be disposed
on positioning ring 32 so as to guide and facilitate movement of
the cutting head assembly 50, discussed below, during the surgical
cutting of the cornea. Referring to FIGS. 5-A and 5-C, in the
preferred embodiment, guide means 40 are seen to comprise a channel
member 41, 42, which extends along a length of at least one side of
positioning ring 32 and preferably, on an upper surface of
positioning ring 32. It will also be appreciated from the drawings
that channel member 41, 42 extends across ring 32 in an arcuate or
semi-circular path. As depicted in FIG. 5-A, channel member 41 may
comprise an elongated, generally "C" shaped structure or even an
inverted "L" shaped structure, which is operably connected to an
upper surface of ring 32, such as designated by numeral 34. As
illustrated in FIGS. 5-B and 5-C however, in the most preferred
embodiment channel member 42 is formed by the interconnection of
two separate elements, namely, an upwardly and arcuately extending
sidewall 36 formed on positioning ring 32, and a toothed track 43
which is interconnected with sidewall 36. Still referring to FIG.
5-C, in the most preferred embodiment, positioning ring 32 is seen
to include the upwardly and arcuately extending sidewall 36 having
a ridge 38 formed on an upper surface thereof, and extending
partially if not completely along, at least one side of positioning
ring 32. Further, in this preferred embodiment, the toothed track
43 is structured to be operably connected to ridge 38 by way of
mating structure. For example, the mating structure can be in the
form of a receiving groove disposed on the undersurface of toothed
track 43, and/or by way of conventionally known fasteners 39' such
as screws, rivets, etc. which may pass through positioning ring 32
at apertures 39 and extend into toothed track 43. As further
illustrated in FIG. 5-C, toothed track 43 is seen to include a lip
43' which is sized and dimensioned to protrude beyond the vertical
plane formed by sidewall 36. Thus, guide means 40 in the form of a
generally "C" shaped channel member 42 is comprised by the combined
structure of sidewall 36 and toothed track 43, having lip 43'. With
respect to the embodiment shown in FIG. 5-A, it is contemplated
that a toothed track may also be mounted to an upper surface of
positioning ring 32 or to an upper surface of channel member 41. It
will be appreciated that toothed track 43 cooperates with the drive
means 80 (see FIGS. 7 and 11) so as to drive the cutting head
assembly 50 across positioning ring 32, as more fully discussed
below.
[0048] In a preferred embodiment, the guide means 40 further
comprise a rigid upstanding member 44 disposed on the retaining and
positioning means 30, and generally opposite the toothed track 43.
As will again be appreciated from the drawings, in the preferred
embodiment, wherein positioning ring 32 is of a tear-drop shape,
rigid upstanding member 44 comprises a post member 45 securely
connected to positioning ring 32 on an upper surface thereof at or
near a tip 35 thereof. From the explanation which follows, it will
become clear that channel member 42 and rigid upstanding member 44
permit the cutting head assembly 50 of the invention, in a
preferred embodiment, to become effectively guided and securely
received on the it positioning ring 32 in two places while still
permitting cutting head assembly 50 to be smoothly and slidably
moved over positioning ring 32 along a generally arcuate path, by
way of a pivoting motion about rigid upstanding member 44. Of
course, the positioning ring could be formed to include another
channel member, such as 41, 42, which extends along a length of the
other side of positioning ring 32, also preferably, on an upper
surface thereof, so as to also permit the cutting head assembly 50
of the invention to become effectively guided and securely received
on the positioning ring 32 in two places while still permitting the
cutting head assembly 50 to be smoothly and slidably moved over
positioning ring 32 along a generally arcuate path.
[0049] Referring now to FIG. 6, the present invention is seen to
include a cutting head assembly 50. A primary purpose of the
cutting head assembly 50 is to house a cutting element 70, see FIG.
8, with a cutting surface operatively exposed therefrom. As such,
upon the cutting head assembly 50, with the cutting element 70,
being moved across the cornea retained within positioning ring 32,
the cornea may be precisely cut by cutting element 70. To
accomplish this, cutting head assembly 50 includes a main housing
51 containing the cutting element 70. Additionally, included in the
main housing 51 is an aperture 58 structured and disposed to permit
drive means 80 to be operably connected thereto (see FIGS. 7 and
11) and to thereby drive the cutting head assembly 50 across
positioning ring 32 in order to effectively cut the cornea.
Further, as the cutting head assembly 50 must be driven in a smooth
and controlled manner across the cornea, housing 51 includes
tracking means 60 which are structured and disposed for mating
communication with and tracking within channel member 42, of
positioning ring 32, in order to precisely guide the cutting head
assembly 50, and therefore the cutting element 70, along the
defined arcuate path. Finally, as a significant feature of the
present invention is to cut a portion of the cornea without
completely severing it, abutting or stop means 65 are provided,
which serve the purpose of limiting and preferably, completely
stopping the movement of the cutting head assembly 50 from cutting
completely across the cornea, that is, before the assembly has
passed completely over the cornea. The abutting or stop means are
preferably disposed on the main housing 51. These features will be
discussed in more detail below.
[0050] Still referring to FIG. 6, the preferred embodiment of the
present invention is also seen to include a coupling member 90.
While the cutting head assembly 50 might be directly and yet
movably engaged with the positioning ring 32 for performing an
operation on the eye, preferably, a coupling member 90 is utilized
as part of the invention, which is structured and disposed to
movably couple the cutting head assembly 50 to the positioning ring
32 while simultaneously permitting movement of the cutting head
assembly 50 relative to positioning ring 32. As illustrated in FIG.
6, coupling member 90 comprises two segments: a) a retaining
segment 92 and b) a pivot segment 95. The retaining segment 92 is
structured and disposed to be fitted onto a top wall surface 56' of
main housing 51 and may include downwardly depending flanges 91, 93
to snugly receive and grip a portion of housing 51 therebetween.
The retaining segment 92 also includes an aperture 94 formed
therein to correspond to aperture 58 of housing 51. As such,
aperture 94 is sized and configured to allow passage of the driving
shaft of the driving means 80 (shown in FIGS. 7 and 11)
therethrough and into aperture 58 of the housing 51. Thus, in
assembled form, coupling member 90 is securely yet removably
coupled to head assembly 50 as a result of the engagement of the
driving means 80 with the housing 51 through retaining segment 92.
Turning to the pivot segment 95 of coupling member 90, it is
structured and disposed to be coupled to rigid upstanding member 44
of positioning ring 32 and to permit coupling member 90, and
accordingly, the cutting head assembly 50 connected thereto, to
pivotally move about post member 45. Preferably, pivot segment 95
includes a bushing 97 having a bore 96 formed therein, which is
sized to receive a substantial height of post member 45, thereby
captivating it therein. Further, in the preferred embodiment, the
pivot segment 95 includes maintaining means 46, see FIG. 5-C, for
maintaining rigid upstanding member 44 within bushing 97 and
engagement means 98 for maintaining bushing 97 over rigid
upstanding member 44. Referring now to FIGS. 5-B and 5-C, the
maintaining means 46 preferably include an enlarged head 47 on
rigid upstanding member 44, and an annular recess 48 or taper about
the neck section of upstanding member 44. As illustrated in FIG. 6,
the engagement means 98 preferably comprise a threaded shaft which
passes through a sidewall of bushing 97 and can be selectively
moved into engagement with upstanding member 44 by rotating handle
99 and causing a tip thereof to extend into the annular recess 48,
thereby preventing removal of the pivot segment 95 from the
upstanding member 44, when surgery is to take place. It will be
therefore be appreciated that in assembled form, the engagement
means 98 and maintaining means 46 cooperate to permit coupling
member 90 and cutting head assembly 50 to rotate about upstanding
member 44 while preventing bushing 97 from sliding up and off of
upstanding member 44. It will also be appreciated that in assembled
form, upstanding member 44 acts as additional guide means for
enabling the cutting head assembly 50 to be driven along an arcuate
path in a smooth and controlled manner across positioning ring 32
and thus, the cornea C.
[0051] Referring back to FIG. 6, as well as to FIGS. 7 and 8, the
cutting head assembly 50 as well as its operation will now be
described in more detail. As previously recited, the cutting head
assembly 50 comprises the main housing 51 which includes a top
surface 56', a bottom wall, and a surrounding sidewall structure 53
defining a front end face 52, and an oppositely disposed rear end
face 54. Because during surgery, the cutting head assembly 50 is
driven across positioning ring 32 along an arcuate path, front end
face 52 preferably defines a tapered nose to cooperate with the
arcuate path of channel member 42. Also as previously recited, the
main housing is structured to contain the cutting element 70 and
operatively expose a cutting surface thereof. In the preferred
embodiment, the cutting head assembly 50 as well as the cutting
element 70, are structured and disposed to permit a diameter of the
cornea of generally about 8 to 10 millimeters to be cut, and
ideally, about 9.5 millimeters. Although the cutting element 70 may
be formed integrally with main housing 51, in the preferred
embodiment the main housing 51 includes an interior chamber 88, see
FIG. 8, structured to receive and maintain an independent cutting
element 70 in a cutting position. Most preferably, the cutting
element 70 is disposed within the main housing 51 at about 20 to 30
degrees from the horizontal plane. Also, a cutting opening 56 is
formed at a bottom of housing 51 so as to expose a cutting surface
of cutting element 70, see FIG. 8. In the preferred embodiment,
cutting element 70 comprises a blade having a sharpened cutting
edge 71, the cutting tip of which is preferably formed to have an
angle of approximately and generally between 5 to 10 degrees from
the horizontal axis of the blade, and further, the blade itself is
operably connected to yet removable from, a blade holder 72. Blade
holder 72 is operably connected to the drive means 80, see FIG. 11,
connected to housing 51 through aperture 58, and drive means 80
impart an oscillating movement causing blade holder 72 and blade 71
to move back and forth generally between opposite walls of the
surrounding sidewall structure 53 of housing 51. Accordingly, the
interior chamber 88 within housing 51 will be sized to receive the
cutting element or blade 70 and blade holder 72 and to permit the
oscillating cutting movement of same within housing 51.
[0052] Additionally, in order to permit a used cutting element 70
to be removed and replaced, housing 51 includes access means 55.
Although the access means 55 may include an exterior slot or like
access, in the preferred embodiment, and as illustrated in FIG. 8,
access means 55 at least partially form bottom wall of housing 51
near rear end face 54, and ideally, comprise a door member 57 which
is hingedly connected to the surrounding sidewall structure 53 at
rear end face 54. Door member 57 is movable between a closed
operative position for surgery and an open position for permitting
a used or contaminated cutting element 70 to be removed from the
housing 51 and replaced with a new or sterile cutting element. Door
member 57 may be selectively maintained in the closed position by
conventionally known fasteners as depicted in FIG. 8. It will be
appreciated from FIG. 8 that door member 57 does not completely
bridge the cutting element 70. It is believed that this structure
is sturdier and less fragile than the structure of known
microkeratomes, which are prone to being bent if, when the cutting
element is inserted, it is not properly aligned within the
microkeratome.
[0053] Also, in the preferred embodiment, housing 51 of cutting
head assembly 50 will include depth adjusting means 75 for
adjusting the depth at which cutting element 70 cuts into the
cornea. As illustrated in FIG. 8, the depth adjusting means 75 are
preferably disposed at the front end face 52 of main housing 51 and
form at least a portion of the bottom wall of housing 51 near front
end face 52. Preferably, the depth adjusting means 75 comprise a
separate nose segment 76, which is structured to be securely, yet
removably interconnected with housing 51 by way of a conventionally
known fasteners 74 such as a screw, a bolt, etc. Preferably, the
nose segment 76 comprises an engagement segment 77 and a variable
depth plate member 78. Engagement segment 77 preferably includes a
terminal end 79 which is formed to define an inverted "V" shape,
and preferably extends across the width of the nose segment 76.
This structure is sized and configured to be received and to nest
within a corresponding void, also shaped like an inverted "V",
formed within housing 51 on and between oppositely disposed
sidewall structures 53, adjacent front end face 52. It will be
appreciated that this structure permits a highly stable nesting or
dwelling of terminal end 79 within housing 51 even as the cutting
head assembly 50 is moved along an arcuate path over positioning
ring 32. Further, as illustrated, variable depth plate member 78 is
preferably integral with engagement segment 77 and is disposed
substantially in the horizontal plane. Variable depth plate member
78, has a depth depicted as "H" in FIG. 8, which is a dimension
pre-selected by the surgeon to correspond the desired depth of the
cut to be made into the cornea. A significant feature of the
present invention is to provide a plurality of nose segments 76,
each including a plate member 78 having a differently dimensioned
depth "H". It will be appreciated from FIG. 8 that there is an
inverse relationship between the depth of plate member 78 and the
depth of the cut to the cornea as the cutting head assembly 50
proceeds forward during surgery in the direction of the arrow "A"
and pushes down on the cornea. For example, a plate member 78
having a larger depth "H", will shield more of the blade's cutting
edge 71 whereas a plate member 78 having a smaller depth "H" will
expose more of area above the blade's cutting edge. It will thus be
recognized that the cutting head assembly 50 is designed to be
interchangeable with differently sized depth adjusting means 75 so
as to precisely meet the needs of the patient undergoing surgery.
Ideally, the present invention will offer two differently sized
nose segments 76, namely one sized for 130 microns and another for
160 microns which are currently the most desirable depths for
cutting into the cornea and exposing same for reshaping.
[0054] As has been described, housing 51 of cutting head assembly
50 also includes tracking means 60. Referring to FIG. 6, tracking
means 60, which in the preferred embodiment are disposed on a lower
peripheral zone of housing 51, are structured for mating
communication with and tracking within channel member 42, see FIG.
5-C, of positioning ring 32. For example, tracking means 60 may
comprise an outwardly extending flange disposed on a side of the
housing 51, along the lower edge thereof, and may take the form of
a continuous flange about the housing 51, or alternatively a
plurality of pin members disposed thereabout. In the preferred
embodiment however, the tracking means 60 are disposed on the depth
adjusting means 75 and are integral with and planar to the variable
depth plate member 78 in the form of a flange 62, see FIG. 6.
Preferably, flange 62 extends out beyond the periphery defined by
surrounding sidewall 53 of housing 51 in generally perpendicular
relation thereto. Further, although the cutting head assembly 50 is
designed to receive nose segments 76 having variable depth plate
members 78, flange 62 which extends therefrom is of a uniform
height so as to correspond and effect mating communication with and
tracking within channel member 42, of positioning ring 32. Although
flange 62 could extend only from one side of the housing 51, in the
preferred embodiment, flange 62 is disposed on each side of
variable depth plate member 78, thereby facilitating use of the
present invention on either a patient's left or right eye.
[0055] Also as previously recited, the main housing 51 includes
abutting or stop means 65 which serve the purpose of limiting and
preferably stopping, the forward movement of cutting head assembly
50 across positioning ring 32. In the preferred embodiment, stop
means 65 are formed generally at rear end face 54 on surrounding
sidewall structure 53 and are seen to comprise a shoulder 66 formed
at the juncture between sidewall structure 53 and rear end face 54
of the housing 51, which shoulder is sized to be too large to pass
within the channel member 42 of the guide means 40, thereby
preventing any further forward motion of the head assembly 50
across positioning ring 32. When abutting engagement occurs between
shoulder 66 and channel member 42, by way of lip 43', the driving
means 80 can be stopped and then reversed to permit movement of the
cutting head assembly 50 in the opposite direction. As has been
described, it has been determined in recent years that in
performing surgery on the cornea, the layers of the cornea which
are cut should not be completely severed. A unique feature of the
cutting head assembly 50 and of this invention 10 is that the
cutting of the cornea results in the formation of a corneal flap F,
as illustrated in FIG. 4, which is also safely preserved by the
assembly 50. To preserve the corneal flap F, housing 51 includes a
flap receiving gap 59 formed within housing 51. As illustrated in
FIG. 6 and more clearly in FIG. 8, flap receiving gap 59 is
disposed generally near the front end face 52 of housing 51 and
more particularly, is defined by a gap formed just forward of the
blade's cutting edge 71 and just rearward of variable depth plate
member 78. Thus, flap receiving gap 59 is disposed on an
undersurface of housing 51 and extends upwardly and into housing
51. Ideally, flap receiving gap 59 extends through the opposite
sidewall structure 53 of housing 51.
[0056] Referring now to FIGS. 9-A, 9-B and 9-C, the cutting head
assembly is illustrated in sequential positions during its movement
in a cutting path over the cornea being treated. As a preliminary
step in the cutting the cornea, FIG. 9-A depicts a) the retaining
and positioning means 30, and b) the cutting head assembly 50
coupled as previously described by coupling member 90, as the
tracking means 60 of the head assembly 50 have been initially
matingly connected to the guide means 40 of positioning ring 32.
More specifically, it is seen in FIG. 9-A that first, a front end
of flange 62 has been matingly received in channel member 42 of
retaining ring 32 and also, that the worm gear 120 is alignedly
received on toothed track 43 of positioning ring 32. Turning to
FIG. 9-B, the cutting head assembly 50 has moved into position
across the positioning ring and cutting of the cornea C is taking
place. FIG. 9-C illustrates the cutting head assembly 50 in a
position wherein the stop means 65 are contacting channel member 42
of the positioning ring 32, to limit and preferably, prevent any
further forward motion of the assembly. It will also be clear from
FIG. 9-C that in this stopped position, the cutting element 70 has
not moved completely across the cornea C, but rather has cut a
portion of the cornea up until this point, creating a corneal flap
which is left attached to the cornea as designated by the area
marked "F" which is shown in the FIG. 9-C. Moreover, as illustrated
in FIG. 8, the corneal flap created has been directed by the
forward movement of the assembly, upwardly and into flap receiving
gap 59 of housing 51 to be preserved and kept clear of cutting
element 70. Once the assembly has been stopped as in FIG. 9-C, the
drive means 80 can be reversed to permit movement of the cutting
head assembly 50 in the opposite direction, which does not result
in any further cutting of the cornea, but rather, in the safe
removal of the corneal flap F out of flap receiving gap 59 of
housing 51. Thus, when head assembly 50 returns through to a
position analogous to that shown in FIG. 9-A, the head assembly can
be disconnected from the retaining means 30. The corneal flap F can
then be maneuvered so as to permit the cornea to be reshaped,
preferably by way of a laser surgical procedure. Once the surgery
has been completed, the corneal flap is returned to a covering
relation over cornea.
[0057] Another unique feature of the present invention is not only
that a corneal flap can be created, but significantly, that the
corneal flap is positioned in such a way that the blinking of the
eye will not improperly position the corneal flap on the cornea
following surgery. Referring now to FIGS. 10-A and 10B, the
invention is schematically illustrated on both a patient's left and
right eyes. As depicted in FIG. 10-A, reference points of the work
environment can be equated with the position of some numerals on
the face of a clock. Thus, in FIG. 10-A, it will be noted that with
respect to the patient's left eye, the cutting head assembly 50 in
the initial position is preferably disposed at a generally five
o'clock position. With respect to the patient's right eye, the
cutting head assembly 50 in the initial position is preferably
disposed at a generally seven o'clock position. Turning now to FIG.
10-B, the cutting head assembly 50 is shown to have moved towards a
position generally aligned with the twelve o'clock position,
wherein the stop means 65 are in abutting engagement with channel
member 42 of the positioning ring 32, such that any further forward
motion of the assembly is prevented. It will thus be appreciated
that regardless of whether the surgical procedure is being
performed on a patient's left or right eye, the cutting head
assembly 50 is preferably aligned generally with a twelve o'clock
position. It will also be appreciated from FIG. 10-B that the
resulting corneal flap F, remains attached to the cornea at an
upper region thereof. Consequently, following the surgical
procedure to reshape the cornea, the orientation of the corneal
flap will be in generally the same direction as the natural
blinking action. That is, it is believed that the downward blinking
motion of the patient will tend to stroke the corneal flap down and
thereby assist with maintaining the corneal flap in proper
re-position on the cornea so as to avoid the development of
astigmatism.
[0058] Referring now to FIG. 11, the present invention includes
drive means 80 both: a) for driving the cutting head assembly 50
across the previously described eyeball retaining and positioning
means 30; and b) for causing the cutting element 70 to oscillate
back and forth within housing 51. The driving means preferably
include a motor 100, preferably electrically operated and most
preferably, a micromotor capable of operating at a constant and
uniform speed, regardless of the load. Specifically, under normal
circumstances the natural resistance encountered by the cutting
head assembly, as it is driven over the cornea, would result in an
increased resistance in the winding of the micromotor, which would
tend to cause a voltage drop and therefore a drop in speed. While
some known systems attempt to avoid excessive drops in speed by
incorporating an overpowered motor to keep losses below a 10% slow
down, the motor 100 of the present invention is preferably equipped
to monitor current flowing therethrough, such as using an op amp,
and utilize that information to control the applied voltage and
maintain the constant speed. This monitoring and compensation,
sometimes referred to as I R compensation, thereby permits a
conventional, regulated 12 V supply to be used with a DC motor in
order to maintain the effective constant speed of travel over the
eye.
[0059] Referring now to FIGS. 8 and 11, the driving means 80
further include a gear box 81 into which a motor main drive shaft
101 extends. From the gear box 81, and specifically concentrically
through an engagement hub 110 as shown in FIGS. 7 and 8, a cutting
assembly main drive shaft operatively extends. The cutting assembly
main drive shaft comprises two primary sections, namely: a) a
threaded drive screw or "worm" 115 shown in FIG. 11, which is an
intermediate section that extends through the engagement hub 110;
and b) an oscillation shaft 130, also shown in FIG. 11, and which
is the inner most section and extends through the worm 115.
[0060] Turning first to the engagement hub 110, shown in FIG. 8, it
is an outer most section that preferably extends downwardly from
the gear box 81 and is structured to be matingly, and preferably
threadingly engaged within the threaded aperture 58 formed in the
main housing 51. As such, the engagement hub 110 functions to
secure the drive means 80 to the cutting head assembly 50. Further,
it will be recognized that the drive means 80 are thereby permitted
to enter the cutting head assembly 50 through a top surface 56' and
are thus, generally vertically disposed. It is believed that this
feature results in less interference with the surgical field and
facilitates finer handling by the surgeon than is offered by
conventionally known microkeratomes. Specifically, known
microkeratomes have typically provided for horizontally disposed
drive means, which resulted in the surgeon having to handle a cord
of the driving means, which if not held properly could cause drag
on the operation of the microkeratome and/or result in a different
pressure being applied to the microkeratome. Moreover, the
structure of the present invention maintains its center of gravity
substantially over the center of the eye, unlike old systems,
thereby providing increased balance and ensuring that the cutting
head assembly does not inadvertently tip away from the surface of
the eye during use.
[0061] As illustrated in FIG. 8, the oscillation shaft also extends
from the gear box 81. Turning now to FIG. 11, the oscillation shaft
130, which extends into the housing 51 through its aperture 58, is
preferably an independent element that extends concentrically
through and protrudes from both ends of the worm 115. The
oscillation shaft 130, which is preferably structured to freely
rotate relative to the worm 115 includes an upper drive portion 132
which may be welded onto shaft 130 but which is in any event,
drivingly engaged with a main drive gear 102 secured to the motor
main drive shaft 101. Accordingly, rotation of the motor main drive
shaft 101 results in corresponding rotation of the oscillation
shaft 130. Further, protruding off center from an opposite end 134
of the oscillation shaft 130 is an oscillation pin 135. The
oscillation pin 135, which is preferably downwardly biased to
maintain engagement pressure on the cutting element 70 is
structured to extend into a slot 72' formed in an upper surface of
the blade holder 72. As such, upon axial rotation of the
oscillation shaft 130, the oscillation pin 135 rotates a
predetermined radius off center and alternatingly engages opposite
side edges of the slot 72' of the blade holder 72 to result in
alternating, oscillating movement of the blade holder 72 and the
cutting element 70 held thereby.
[0062] The oscillating shaft 130 further includes a secondary drive
portion 133. The secondary drive portion 133 is drivingly connected
with a first interior drive gear 103 contained within the gear box
81. The first interior drive gear 103 is connected with and
drivingly secured to an interior drive shaft 104, which preferably
includes a second interior drive gear 105 disposed thereon in
spaced apart relation from the first interior drive gear 103. As
such, upon rotation of the oscillation shaft 130, the second
interior drive gear 105 also rotates.
[0063] Drivingly connected with the second interior drive gear 105
and structured to extend from an interior of the gear box 81,
concentrically through the engagement hub 110, is the threaded
drive screw or "worm" 115. The worm 115, which extends up into the
gear box 81 includes a drive head 116 which engages the second
interior drive gear 105. As a result, upon rotation of the interior
drive shaft 104, the worm 115 correspondingly rotates within the
housing 51 of the cutting head assembly 50. Further, rotatably
disposed within the housing 51, in operative engagement with the
worm 115, is a worm gear 120. The worm gear 120 preferably includes
an increase diameter central portion 122 having a plurality of
drive recesses formed about a perimeter thereof and structured to
engage the exterior threaded surface of the worm 115 such that the
central portion 122, and accordingly the entire worm gear 120,
rotates about a horizontal axis as a result of the rotation of the
worm 115 about a vertical axis. It is noted that the screw-like
threaded surface of the worm 115 enables the worm 115 to rotate
without moving vertically and successively engage the drive
recesses on the worm gear 120 to effect rotation thereof. Extending
from at least one, but preferably both vertical faces of the
central portion 122 of the worm gear 120 is a propulsion shaft 125.
The propulsion shaft 125, which comprises additional tracking
means, is structured to protrude from the sidewall structure 53 of
the main housing 51 and engage the toothed track 43 on the
positioning ring 32 such that upon rotation of the worm gear 120,
and accordingly rotation of the propulsion shaft 125, the
propulsion shaft 125 rides along the toothed track 43 and drives
the cutting head assembly 50 across the positioning ring 32
smoothly and at a steady and defined pace. Furthermore, it is seen
that by reversing the rotational direction of the interior drive
shaft 101 within the gear box 81, the direction of rotation of the
worm 115 and therefore the worm gear 120 are reversed to effectuate
reverse driven movement of the cutting head assembly 50 over the
positioning head 32. Also, so as to facilitate movement over
toothed track 43 and the arcuate path thereof, it is preferred that
the propulsion shaft 125 portion of the worm gear 120 include a
helical gear configuration or plurality of angled ridges to permit
more effective alignment with the curved toothed track 43 and
movement thereover.
[0064] Referring once again to the motor 100, it is preferred that
it be controlled by a foot pedal or like actuation means. In the
case of a foot pedal, it is preferred that it be a dual function
foot pedal such that one side will function to drive the motor main
drive gear 101, and therefore the cutting head assembly 50 in a
forward direction, and the second side will drive them in a reverse
direction. Further, the system may be set to a manual mode whereby
a doctor must affirmatively reverse the direction of movement, or
an "auto-reverse" mode wherein upon the cutting head assembly 50
traveling its maximum distance it automatically reverses direction.
In either case, however, the motor 100 will preferably be equipped
with a sensor to detect an abrupt current increase. Specifically,
when the cutting head assembly 50 reaches the stop means 65 and
further forward movement is either partially or completely
resisted, an abrupt current increase will occur in the motor 100.
That abrupt current increase, once detected, can signal either the
power to shut off, or the reverse movement to commence, depending
upon a doctor's desired setting.
[0065] Finally, it will be appreciated that the present invention
can be utilized on both eyes of the patient. Specifically, as worm
gear 120 runs through housing 51 and juts out of the opposite
surrounding sidewall structure 53 of housing 51, the cutting head
assembly is ready to use on the opposite eye of a patient. In order
to accomplish this, and due to the symmetric shape of the cutting
head assembly 50, the drive means 80 need only be removed from the
housing 51 and thus, coupling member 90, whereupon, it can be
re-oriented 180 degrees for use with the opposite eye of a
patient.
[0066] 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 as illustrative
and not in a limiting sense. Thus, the scope of the invention
should be determined by the appended claims and their legal
equivalents.
[0067] Now that the invention has been described,
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