HK1031190B

HK1031190B - A cutting blade assembly for cutting cornea and the medical apparatus having the same

Info

Publication number: HK1031190B
Application number: HK01100463.7A
Authority: HK
Inventors: F. Hellenkamp Johann
Original assignee: F. Hellenkamp Johann
Priority date: 1997-04-25
Filing date: 1998-04-24
Publication date: 2005-12-30

Description

Cutting blade assembly for cutting cornea and medical device comprising same

Technical Field

The present invention relates to improvements in a medical device for use in ophthalmic surgery. In particular, the present invention relates to an improved cutting blade assembly for use with an automated surgical device for cutting the cornea of an eye of a patient. The invention also relates to a medical device comprising the cutting blade assembly.

Background

Until about 20 years ago, the refractive error of light as it passes through the eye could only be corrected by spectacles or contact lenses, all of which have well-known disadvantages for the user. Later, over the last few years researchers began using surgical procedures to alter the refractive condition of the eye, i.e., to decrease or increase the curvature of the patient's eye depending on the patient's condition. The ideal result is that light rays passing through the cornea are refracted and focused on the retina, thereby enabling the patient to clearly see objects at near or far.

Automatic corneal Ablation (ALK) is a surgical technique in which the eye is first anesthetized with a drop of anesthetic, after which a suction ring is placed on the eye to carefully position the cornea (known in the art as "centering") in order to cut it with a very fine microsurgical device called a microkeratome. The microkeratome is typically a blade carrying device that must be manually pushed or mechanically moved across the suction ring along a cutting path while the cutting element is automatically moved in a direction transverse to the cutting path. To perform an ALK procedure on a myopic patient, a microkeratome is typically first cut into the cornea to cut and lift a thin anterior layer of cornea between 100 and 200 microns in depth and about 7 mm in diameter. Thereafter, the microkeratome is moved a second time across the cornea to ablate, i.e., remove, a smaller portion of the cornea, typically about 4 to 6 mm in diameter, which is discarded. Next, the anterior corneal flap cut upon the first pass through the cornea is replaced in its original position without the need for sutures to await healing. The ideal result of this procedure is that the cornea has a new curvature due to the removal of tissue, thus constituting a new refractive surface for the patient to correct the near vision condition. On the other hand, when using ALK surgery to treat hyperopia, a microkeratome is required to cut deep across the cornea once. The cut cornea is replaced without having to remove any other tissue. As a result of this deep cut, intraocular pressure causes the cornea to re-steepen, thereby forming a new refractive surface to correct the patient's original hyperopic condition.

A more recent development in surgical methods for correcting refractive errors of the eye has been the introduction of laser treatment. Such a procedure, known as intrastromal corneal Laser Angioplasty (LASIK), is currently considered optimal because it allows sculpting of the cornea without damaging adjacent tissue. In addition, with the aid of a computer, the surgeon can program the laser to precisely control the amount of tissue removed, thereby allowing a variety of options for reshaping the cornea. In LASIK surgery, the eye is also typically positioned in a ring-shaped device prior to reshaping the cornea by the laser, and is also typically cut into the cornea with a microkeratome to lift a thin layer of the cornea.

In recent years it has been recognized that microkeratomes used to cut the cornea, whether for ALK or LASIK surgery, do not produce a corneal flap nor completely separate the corneal tissue to be cut from the remaining cornea. The reason is mainly divided into two aspects: first, there is the possibility that when the corneal cap is placed back onto the cornea, it will not properly align over the remaining corneal tissue, which has several disadvantages for the patient; second, there is the possibility that the corneal flap will be lost during the procedure, and once this occurs, the result is catastrophic to the patient. In a principal effort to solve these problems, one of the points of the present inventors is to develop and produce an improved surgical device for cutting the cornea that automatically and reliably "hinges" a portion of the raised and separated corneal tissue on the eye to form a raised corneal layer, referred to as a corneal membrane F, hinged to the eye, as shown in fig. 1.

Importantly, it has been determined that the best results are obtained when the thickness of the corneal lamellae is not less than 130 microns and not greater than 160 microns. It should be considered that extremely delicate instruments are required to achieve this result during surgery, since a unit of length such as a micron is equal to one thousandth of a millimeter. It is also desirable, if not necessary, that the microkeratome cut through the cornea in a manner that cuts the corneal tissue in a very fine and smooth manner. In this respect, when the smoothness of the incision made in the cornea by the existing microkeratome apparatus is examined microscopically, it can be seen that the incision and the edge of the corneal tissue are slightly irregular, even slightly jagged, which is a significant improvement. Ideally, not only is it possible to cut and lift the corneal tissue microsheet, which is currently considered optimal, when the microkeratome apparatus cuts through the cornea, but the resulting cut corneal tissue edge is very fine, smooth and nearly undetectable, thereby significantly improving the quality of the corneal incision.

In addition, existing microkeratome devices have room for improvement in the assembly of the device prior to performing surgery on a patient's eye, as well as the disassembly, sterilization, and cleaning of the device or its components after surgery. In particular, microkeratome devices, and in particular the cutting blades of the devices that are required to penetrate and cut the cornea, are required to be in a properly cleaned and sterilized condition prior to surgery on the eye. However, existing microkeratome devices require manipulation of the housing of the cutting blade to create access to the interior of the housing and to mount the cutting blade within the housing, and the cutting blade itself is typically manipulated, after which the housing must be manipulated again to close the access device in order to properly seat the cutting blade. However, it is not beneficial to require excessive manipulation of existing microkeratome devices in order to maintain the proper disinfection and cleanliness required for the procedure. In addition, some surgeons may inadvertently unseat the cutting blade or, worse, bend the cutting blade while operating the access device of some prior microkeratome devices, thus requiring the assembly to be restarted. In addition, the mechanism for holding the cutting blade in the existing microkeratome apparatus is intended for reuse. This factor exacerbates the problem encountered with existing microkeratome devices, which also requires the blade holding mechanism to be removed from the microkeratome device after surgery in order to be properly cleaned and/or sterilized for the next use. The assembly and disassembly of such mechanisms is both tedious and time consuming, and presents difficulties in maintaining sterility and ensuring proper reassembly.

In addition, the blades in prior art microkeratome devices are generally rectangular. For example, EP0442156a1 discloses an automatic keratome device comprising a motor and drive shaft assembly, a forming head assembly, and a positioning ring. The motor and the transmission shaft assembly are used for driving the forming head assembly to move longitudinally while oscillating transversely to cut the cornea. The forming head assembly includes a cutting blade and a shank, wherein the cutting blade has a rectangular shape. Such rectangular cutting blades have some disadvantages, such as inconvenient installation and easy interference with surrounding structures.

Accordingly, there is a need in the art for an improved microkeratome apparatus for cutting the cornea of an eye of a patient that can readily receive and facilitate proper positioning of a cutting blade without requiring excessive manipulation. There is also a need for an improved cutting blade assembly that can be easily inserted into a microkeratome device with little risk of buckling, while providing the user with information that it is securely and properly in place. Any such improved cutting blade should be capable of being removed from the microkeratome apparatus as quickly and easily and preferably be disposable. It would be desirable if such an improved cutting blade assembly were pre-packaged in a container so as to be sterilizable prior to shipment and maintained in a sterile condition while in transit, and further, such an assembly could be readily removed from sterile packaging for insertion into a microkeratome while maintaining sterility. In this regard, it is desirable for such an improved cutting blade assembly to include a tool to facilitate removal of the assembly from a sterile container and insertion into a microkeratome while maintaining sterility.

There is another significant drawback to existing microkeratome devices. For example, during surgery on a patient's eye, the suction or vacuum required to temporarily attach the suction ring to the cornea is sometimes disconnected or interrupted. Since such a procedure requires a precise cut, it is highly undesirable to continue cutting the eye in such a situation. To date, existing microkeratomes continue to cut under such conditions. It would therefore be highly desirable to provide an improved microkeratome apparatus having a control assembly that detects problems encountered during surgical cutting of the cornea and shuts off power to the device to stop the microkeratome from cutting the cornea when a problem is detected. Furthermore, if the surgery on the patient's eye is performed well and a power outage occurs suddenly, such a control assembly can ensure that the microkeratome apparatus continues to operate without interruption for a short period of operation, thereby ensuring that power is continuously supplied to the device and to the positioning ring.

Disclosure of Invention

The present invention is designed to meet the needs in the art of microkeratome devices for cutting the cornea of an eye of a patient.

It is a primary object of the present invention to provide an improved cutting blade assembly which significantly improves the corneal dissection process by cutting and lifting a microscopic layer of corneal tissue and making the resulting dissected corneal tissue edge very fine, smooth and nearly undetectable and which can be easily and more accurately placed back in place in the cornea following corneal reshaping.

It is another primary object of the present invention to provide a microkeratome apparatus with an improved access device for ensuring that either or both of the cutting blade and the handle can be easily and quickly installed at the same time for performing a procedure on a patient, while at the same time facilitating cleaning of the microkeratome and its internal mechanism or mechanisms.

It is another important object of the present invention to provide a cutting blade assembly that can be easily and quickly inserted into a microkeratome apparatus in preparation for surgery without requiring excessive manipulation to maintain the sanitary condition of the assembly and apparatus, and that can also quickly determine whether the assembly is securely and properly seated in the microkeratome.

It is another object of the present invention to provide an improved cutting blade and handle that are integrally formed so as to be easily removable from the microkeratome apparatus and are preferably disposable.

It is another object of the present invention to provide a cutting blade assembly that can be easily packaged in a container so that it can be sterilized prior to shipment and maintained in a sterilized condition while in transit, and further, can be easily removed from a sterile packaged container and inserted into the cutting head assembly of a microkeratome while maintaining sanitary conditions.

It is another object of the present invention to provide a cutting blade assembly that can be used in both existing microkeratome devices and in future developed devices.

To achieve the above object, the present invention provides a cutting blade assembly comprising:

a) a cutting blade having:

i) a front portion, said front portion comprising a sharpened forward cutting edge;

ii) a rear traction portion comprising a rear edge;

iii) a pair of side edges connecting said front portion and said rear traction portion; and

b) a handle operably connected to said cutting blade driven by said drive means of the surgical device, wherein said at least one side edge of said cutting blade at least partially tapers from said forward portion toward said rearward traction portion.

In the above cutting blade assembly, the cutting blade may further comprise at least one aperture, preferably a pair of apertures, disposed on the trailing traction portion and substantially flush with each other. Preferably, the cutting blade is substantially flat and made of stainless steel, with the forward portion of the cutting blade having an overall dimension greater than the rearward traction portion. The improved cutting blade assembly has a shank shaped such that an underside thereof is secured to the cutting blade at least one aperture in the cutting blade, and a top side of the shank includes means for being operably driven by the microkeratome device drive means, which may include a recess formed in the shank. In a preferred embodiment, the shank is molded from plastic and press-fit into at least one hole in the cutting blade during manufacture to form an integrally formed cutting blade assembly. In a most preferred embodiment, the cutting blade assembly of the present invention further comprises a tool for facilitating removal of the cutting blade and handle from a sterile packaging container and insertion into the microkeratome assembly while maintaining sterility.

In addition, the present invention provides a medical device comprising a cutting blade assembly and a surgical device for cutting through a cornea of an eye of a patient, the cutting blade assembly comprising:

a) a cutting blade having:

ii) a rear traction portion comprising a rear edge;

iii) a pair of side edges connecting said front portion and said rear traction portion;

b) a shank operatively associated with a cutting blade, said at least one side edge of said cutting blade at least partially tapering from said forward portion to said rearward traction portion;

the surgical device includes:

a) a positioning ring having means for temporary attachment to a portion of the eye around a cornea to be cut; said positioning ring defining an aperture sized to receive and expose a cornea to be cut;

b) said retaining ring including guide means formed along an arcuate path on one surface of the retaining ring;

c) a cutting head assembly housing said cutting blade assembly for cutting the cornea, said cutting head assembly being constructed and arranged to be driven through said positioning ring along said arcuate path defined by said guide;

d) a drive means operably connected to said cutting head assembly for causing said cutting head assembly to move through said positioning ring and cause said cutting blade assembly to oscillate;

e) the cutting head assembly comprises a main housing having: a top surface, a bottom surface, a front face, a rear face and a surrounding sidewall structure between said surfaces and faces; an inner cavity configured to receive and retain said cutting blade assembly in a cutting position; and a cutting opening formed in said bottom surface for exposing a leading cutting edge of said cutting blade assembly.

These and other objects, features and advantages of the present invention will be more readily understood upon consideration of the drawings and the following detailed description of a preferred embodiment of the present invention.

Drawings

For a fuller understanding of the nature of the present invention, reference should be made to the following detailed description taken together with the accompanying figures in which:

FIG. 1 is a schematic representation of the cornea of an eye in which a corneal flap has been created.

FIG. 2 is an exploded perspective view of a preferred microkeratome retention and positioning device and a preferred microkeratome attachment member of a preferred microkeratome cutting head assembly according to the present invention.

Figure 3 is a cross-sectional view of the spacing and locating means shown in figure 2.

Fig. 4 is a partial side view of the preferred microkeratome shown in fig. 2 in an assembled form and positioned over a patient's cornea.

Fig. 5 is a partial cross-sectional view of the preferred microkeratome shown in fig. 4.

Fig. 5-a is a partial side view of a preferred microkeratome in a partially disassembled state with no cutting blade assembly inserted to show an improved access device.

Figure 6-a is a side view of a cutting blade assembly according to the present invention in a preferred embodiment.

Figure 6-B is a top view of the cutting blade assembly shown in figure 6-a.

Fig. 6-C is a bottom view of the cutting blade assembly shown in fig. 6-a.

FIG. 7 is a side view of another preferred embodiment of the cutting blade assembly of the present invention.

FIG. 8 is a side view of a tool for removing the cutting blade assembly shown in FIGS. 6 and 7 from a sterile packaging container and inserting the cutting blade assembly into a microkeratome while maintaining sterility.

FIG. 9 is an isolated perspective view of the drive means of the preferred microkeratome apparatus and illustrates the operation and connection of the worm, worm gear and oscillating shaft with the means on the handle in the form of a groove for being operatively driven by the drive means of the microkeratome apparatus.

Fig. 10-a is a front schematic view of a preferred microkeratome apparatus for use with the left and right eyes of a patient, with the cutting head assembly shown in an initial position.

Fig. 10-B is a schematic view of the front of the preferred microkeratome shown in fig. 10-a, but with the cutting head assembly shown in a motion stop position in which a corneal membrane has been formed and the hinged portion of the corneal membrane oriented to allow the corneal membrane to coordinate with eye blinking after surgery.

FIG. 11 is a perspective view, partially in section, of a preferred control assembly according to the present invention that may be used with, for example, the microkeratome apparatus shown in FIG. 2.

FIG. 12 is an isolated schematic view of a preferred optocoupler for use in a control assembly according to the present invention.

Like reference symbols in the various drawings indicate like elements.

Detailed Description

As shown in the figures, the present invention is directed to an improved automatic microkeratome apparatus for smoothly cutting the cornea of an eye, generally designated 10, a cutting blade assembly for use in the apparatus, generally designated 105, and a control assembly for use in the apparatus, generally designated 200.

The preferred and improved automatic microkeratome apparatus of the present invention, which will be explained first, is used to substantially, but not completely, cut through the cornea of a patient's eye to lift a thin layer of the cornea and create an articulated piece of corneal tissue. As shown in FIGS. 2 and 3, the preferred microkeratome device 10 includes means 30 for locating and positioning the eye to be operated on. The spacing and locating means 30 may be made of high grade stainless steel and preferably includes a locating ring 32 having a hole 33 formed therein. The aperture 33 is sized to allow the cornea C of the eye to pass through and be exposed, as shown in FIG. 3. As shown in the figures, the positioning ring 32 preferably has a generally teardrop shape.

The positioning ring 32 also includes means for temporarily attaching to a portion of the eye surrounding the cornea on which the procedure is to be performed. Desirably, the temporary attachment means comprises a suction device. For example, the positioning ring 32 preferably includes a connector 37, as shown in FIGS. 2 and 3, that is in fluid communication with the bottom surface of the positioning ring 32. The connector 37 is adapted to be connected to a vacuum hose 202. As shown in FIG. 11, the vacuum hose 202 may be connected to a vacuum pump 210 so that, when suction is initiated, the bottom surface of the positioning ring 32 forms a seal around and is constrained to the corneal portion of the eye to be operated on. In addition, the configuration of the positioning ring 32, in combination with suction, acts on the cornea C in a suitable position for performing the procedure and maintaining that position during the procedure. Typically, a vacuum of about 635 cm (25 inches) mercury column height above sea level may be used.

The spacing and positioning means 30 further comprise a guide means 40, as shown in figure 3. The guide 40 may be formed directly on the retaining ring 32 so as to be integral with the retaining ring, or may be operably attached to the retaining ring as a separate component. In either form, the guide 40 rests on the positioning ring 32 to guide and facilitate movement of the cutting head assembly 50 during surgical cutting of the cornea, as described hereinafter. Referring to FIG. 3, in the preferred embodiment, it can be seen that the guide 40 includes a channel member 42 extending along the length of at least one side of the positioning ring 32 and preferably located on the upper surface of the positioning ring 32. As can be seen, the trough 42 follows an arcuate or semi-circular path through the ring 32. In this most preferred embodiment, the channel member 42 is formed by two separate elements connected together, namely an upwardly facing and arcuately extending side wall 36 of the formed retaining ring 32 and a toothed track 43 connected to the side wall 36. Referring also to FIG. 3, in this most preferred embodiment, it can be seen that the upwardly facing and arcuately extending side wall 36 included in the retaining ring 32 includes a ridge 38, the ridge 38 being formed on the upper surface of the side wall and extending along a portion or even all of at least one side of the retaining ring 32. Further, in this preferred embodiment, the toothed track 43 is operably connected to the spine 38 by mating structure. For example, the mating structure may be in the form of a receiving slot disposed in the bottom surface of the toothed track 43 and/or may extend through the retaining ring 32 and into the toothed track 43 in the bore 39 using a conventionally known fastener 39', such as a screw, rivet, or the like. Also shown in fig. 3, the toothed track 43 includes a lip 43' therein that is sized and dimensioned to extend from the vertical plane defined by the side wall 36. Thus, the guide 40 is in the form of a generally "C" shaped channel member 42 and is formed by the side wall 36 and a toothed track 43 with a lip 43'. It can be seen that the toothed track 43 may cooperate with a drive 80 (see fig. 4 and 9) to drive the cutting head assembly 50 through the positioning ring 32, as explained in detail below.

The guide means 40 also comprise a rigid upright 44, which is arranged on the stop and positioning means 30 and substantially opposite the toothed track 43. As can also be seen in the drawings, in the preferred embodiment in which the positioning ring 32 is tear-drop shaped, the rigid upstanding member 44 includes a post member 45 fixedly attached to the positioning ring at the upper surface of the positioning ring 32 and located at or near one end 35 of the positioning ring. As will be seen from the description below, the trough member 42 and rigid upright member 44 enable the cutting head assembly 50 of the present invention to be guided and securely received within the locating ring 32 in two positions while still enabling the cutting head assembly 50 to smoothly slide across the locating ring 32 in a rotational motion about the rigid upright member 44 along a path that travels through a generally arcuate path.

Referring now to FIG. 2, it can be seen that the preferred microkeratome apparatus includes a cutting head assembly 50. One primary function of the cutting head assembly 50 is to house a cutting element 70, such as a cutting blade, see FIG. 5, a cutting surface of which is operably exposed from the cutting head assembly. Thus, the cutting head assembly 50 has the cutting element 70 operably disposed therein, and the cornea can be accurately cut by the cutting element 70 as the cutting head assembly 50 moves through the cornea constrained within the positioning ring 32. To this end, the cutting head assembly 50 includes a main housing 51 that houses a cutting element 70. In addition, the main housing 51 contains an aperture 58 therein which is constructed and arranged so that a drive mechanism 80 (see FIGS. 4 and 9) can be operatively connected therein to drive the cutting head assembly 50 across the positioning ring 32 for effective cutting of the cornea. In addition, since the cutting head assembly 50 must be moved across the cornea in a smooth and controlled manner, the housing 51 contains a guide track arrangement 60 which is structured and arranged to fit and be guided within the channel member 42 of the positioning ring 32 so as to precisely guide the cutting head assembly 50, and thus the cutting element 70, along a defined arcuate path. Finally, since one of the salient features of the preferred microkeratome apparatus of the present invention is the cutting of a portion, but not complete severing of the cornea, a stop or brake 65 is provided for limiting, and preferably completely preventing, the complete cutting of the assembly through the cornea when cutting head assembly 50 is moved completely through the cornea. The arresting or braking means is preferably arranged in the main housing 51. These features will be explained in detail later.

Referring also to fig. 2, it can be seen that the preferred microkeratome apparatus also includes a connector 90. The coupling member 90 is configured and arranged to movably couple the cutting head assembly 50 to the positioning ring 32 while permitting movement of the cutting head assembly 50 relative to the positioning ring 32. As shown in fig. 2, the connecting member 90 comprises two pieces: a) one stop segment 92 and b) one rotation segment 95. The retainer segment 92 is constructed and arranged to fit over a top wall surface 56' of the main housing 51 and includes downwardly depending flanges 91, 93 for closely receiving and gripping a portion of the housing 51. The retention segment 92 also includes a hole 94 formed therein that corresponds to the hole 58 in the housing 51. Thus, the aperture 94 is sized and shaped to allow a drive shaft of the drive device 80 (see FIGS. 4 and 9) to pass therethrough and be inserted into the aperture 58 of the housing 51. In this way, since the drive means 80 engages with the housing 51 through the stopper section 92, the connecting member 90 is connected to the head assembly 50 in a firm and detachable manner in the assembled state. Turning now to the rotating segment 95 of the connecting member 90, it is structured and arranged to be connected to the rigid upright 44 of the positioning ring 32 and to allow the connecting member 90, and thus the cutting head assembly 50, to be connected to the upright for rotational movement about the post member 45. Preferably, the swivel section 95 includes a sleeve 97 having an internal bore 96 formed therein and sized to receive a substantial portion of the height of the post member 45 to capture the post member therein. Furthermore, the rotating section 95 preferably comprises retaining means 46, see fig. 3, for retaining the rigid upright 44 in the sleeve 97 and snap means 98 for retaining the sleeve 97 on the rigid upright 44. As shown in fig. 2 and 3, the retaining means 46 preferably comprises an enlarged head 47 on the rigid upright 44 and an annular groove 48 or cone around the neck of the upright 44. As shown, the engaging means 98 preferably comprises a threaded shaft which passes through the side wall of the sleeve 97 and can be selectively engaged with the upright 44 by rotating the handle 99 with one end of the threaded shaft extending into the annular recess 48, thereby preventing removal of the rotatable section 95 from the upright 44 during surgery. Thus, it will be appreciated that in the assembled state, the engagement means 98 and the retaining means 46 cooperate to allow the connecting member 90 and the cutting head assembly 50 to rotate about the upright 44 while preventing the sleeve 97 from sliding upwardly out of the upright 44. It will be seen that in the assembled state, the upstanding members 44 also serve as a proximal guide to ensure that the cutting head assembly 50 can be driven in an arcuate path in a smooth and controlled manner across the positioning ring 32 and, thus, across the cornea C.

Referring to fig. 2, a cutting head assembly 50 of the preferred microkeratome apparatus and the manner of operation thereof is explained in detail. As previously described, the main housing 51 of the cutting head assembly 50 includes a top surface 56', a bottom wall, and a surrounding sidewall structure 53 defining a front face 52 and an oppositely disposed rear face 54. Because the cutting head assembly 50 is driven through the positioning ring 32 in an arcuate path during surgery, the front face 52 preferably defines a tapered nose for cooperating with the arcuate path of the channel member 42. As also previously described, the main housing is adapted to receive a cutting member 70, such as a cutting blade, and to operatively expose a cutting surface of the cutting member. To accomplish this, the main housing 51 preferably defines an internal cavity 88 therein, as shown in FIG. 5, for receiving and accommodating the operation of the cutting element 70, preferably a cutting blade assembly 300, which will be explained in greater detail hereinafter, during surgery. A cutting opening 56 is formed in the bottom of the housing 51 for exposing a cutting surface of the cutting element 70, as shown in fig. 5.

In addition, in order to enable a used cutting element 70 to be removed and replaced, an access device 55 is included in the housing 51. In one embodiment, as shown in fig. 5, the access device 55 at least partially forms the bottom wall of the housing 51 at the rear end 54, and desirably includes a door member 57 hingedly connected to the surrounding side wall structure 53 at the rear end 54. The gate member 57 is movable between a closed operative position, in which surgery can be performed, and an open position, in which a used or soiled cutting element 70 can be removed and replaced with a new and sterilized cutting element. The gate member 57 can be selectively held in the closed position by conventional fasteners of the prior art as shown in fig. 5. It should be noted that gate member 57 does not completely span cutting element 70 to form a stronger, less brittle structure to avoid bending the cutting element when it is inserted and closed in place for use in a microkeratome.

However, a unique feature of the present invention is the provision of an improved access device for the cutting head assembly 50 of the microkeratome apparatus, as shown in FIG. 5-A, generally indicated at 155, so that a fresh and sterile cutting element can be easily and quickly inserted into the cutting head assembly 50 in preparation for surgery, while minimizing manipulation of the cutting element to maintain the cutting element in a hygienic condition. Preferably, the modified access means 155 enables a fresh cutting element 70, ideally a cutting blade assembly 300 comprising a cutting blade and a handle as described hereinafter, to be slidably inserted into the cutting head assembly 50 and easily and suitably secured in place in the cutting head assembly to be used in surgery. To this end, the modified access device 155 preferably includes a side access opening formed in the cutting head assembly 50. As shown in FIG. 5-A, the surrounding sidewall structure 53 of the cutting head assembly 50 preferably includes an access opening 156 formed therein that is positioned to substantially correspond to and align with the interior cavity 88 of the cutting head assembly 50 so that the cutting element 70 can be received in a suitable cutting position in the cutting head assembly 50 to be used in surgery. Desirably, the access opening 156 is constructed and arranged to extend from one side of the surrounding sidewall structure 53 to the other so as to extend completely through the cutting head assembly 50 so that the cutting element 70 can be easily inserted from either side of the cutting head assembly 50. As can be seen from the foregoing, the improved access means 155 is also constructed and arranged to allow the used and soiled cutting element 70 to be easily and quickly removed from the cutting head assembly. It will also be seen that although the gate member 57 of the cutting head assembly 50 may also be moved to an open position to allow insertion of the cutting element 70 into the cutting head assembly 50, the gate member is preferably only moved to an open position to allow cleaning of other internal mechanisms mounted in the cutting head when required.

Referring to fig. 5, the cutting member 70 is explained as follows. First, in this preferred embodiment, the cutting element 70 is positioned in the main housing 51 at about 20 to 30 degrees off horizontal. In addition, the cutting element 70 preferably comprises a blade with a sharpened cutting edge 71, the cutting tip of which is preferably offset from the horizontal axis of the blade by an angle, which is typically between about 5 and 10 degrees. To accomplish this preferred objective, in a preferred embodiment, cutting member 70 comprises a cutting blade that is operably coupled to a handle 72. The handle is operatively connected to and disposed within the interior 88 of the cutting head assembly 50 and communicates with a drive means 80, see fig. 9, which is operatively connected to the housing 51 of the cutting head assembly 50 and thus to the microkeratome as a whole. As previously described, drive 80 imparts an oscillating motion to tool shank 72, thereby causing tool shank 72 and its attached blade 70 to move back and forth within interior chamber 88 of cutting head assembly 50 and substantially between the opposing sidewalls of the surrounding sidewall structure 53 of the cutting head assembly. Thus, interior cavity 88 of housing 51 is sized to accommodate not only a cutting element, such as a cutting blade 70 and a handle 72, but also an oscillating cutting motion of the cutting element within housing 51. In order for the modified microkeratome and cutting blade assembly to cut and lift a microscopic layer of corneal tissue and to produce a very fine, smooth and nearly undetectable edge of cut corneal tissue, in a preferred embodiment, the drive mechanism 80 will cause the handle 72 and blade 70 to oscillate at a very rapid rate, typically between 5,000 and 10,000 times per minute, ideally about 8,500 times per minute, than could be achieved with other devices, thereby achieving optimal cutting of the cornea. In this regard, as described hereinafter, the drive means preferably drives the cutting head assembly 50 through the positioning ring 30 and the eye held therein at a speed such that the cutting head assembly 50 requires approximately 3 to 6 seconds of application, ideally approximately 4 to 5 seconds. These preferred cutting speed ranges for the microkeratome are intended to provide optimal and significantly improved cutting of corneal tissue.

In addition, to facilitate and facilitate installation of the cutting member 70 in the cutting head assembly 50 without undue manipulation to maintain the sterile condition, the present invention incorporates a cutting blade assembly, as shown in FIGS. 6-8, and generally designated by the reference numeral 300. It can be seen that the cutting blade assembly of the present invention comprises an improved cutting blade 310 and handle 320. The cutting blade 310 includes a forward portion 312 with a sharpened forward cutting edge 313; a rear traction portion 314 with a rear edge 315; and a pair of side edges 316, 317 that extend and taper between the front and rear traction portions. In a preferred embodiment, the rear edge 315 is generally parallel to the forward cutting edge 313 of the forward portion 312. In addition, the cutting blade 310 also includes at least one aperture 318 and preferably a pair of apertures 318, 319 that are desirably circular and are positioned in substantial alignment on the trailing traction portion 314. Preferably, the cutting blade 310 is substantially flat and made of stainless steel, with the forward portion 312 of the cutting blade being of a larger overall size than the rearward traction portion 314. In one embodiment, as shown in fig. 7, the side edges 316, 317 on the modified cutting blade 310' extending between the front portion 312 and the rear traction portion 314 are rounded. This feature enables the cutting blade assembly 300 in the preferred microkeratome apparatus to be manipulated to move along an arcuate path across the positioning ring 32. In particular, the cutting blade 310' illustrated in FIG. 7 is configured such that, as it oscillates during surgery, all or a portion of the blade side edge can always extend beyond the surrounding sidewall structure 53 of the cutting head assembly 50 without contacting the positioning ring 32 or being affected by movement of the cutting head assembly along an arcuate path past the positioning ring. The cutting blades 310, 310' may also have other shapes to accomplish this. For example, as shown in fig. 6-a through 6-C, in a more preferred embodiment, the forward portion 312 of the cutting blade 310 is generally rectangular and the rearward traction portion 314 is generally trapezoidal such that the side edges 316, 317 taper from a larger width dimension at the forward portion 312 to a smaller width dimension at the rearward traction portion 314.

Cutting blade assembly 300 also includes a modified handle 320. The tool shank 320 is shaped such that its bottom side 321 is fastened to the cutting blade 310 at the at least one hole 318 of the cutting blade, and the top side 322 of the tool shank 320 carries means 325 for being operatively driven by the driving means 80 of the microkeratome device. In the preferred embodiment, the means 325 comprises a recess 326 formed in the shank, which is desirably oval in shape, although a slot, groove or other recess may be formed in the insert holder 320 without departing from the scope of the invention. Further, in the preferred embodiment, shank 320 is molded from plastic and press fit into at least one hole 318 of cutting blade 310 during manufacture to form an integrally formed cutting blade assembly. It should be noted that by integrating cutting blade 310 and handle 320, which will become contaminated during surgery, cutting blade assembly 300 can be more easily removed from the cutting head 50 of the microkeratome, and, because handle 320 is made of plastic, cutting blade assembly 300 can be disposable. Preferably, the shank 320 includes at least one locking segment 328 on its bottom side 321 that is configured and arranged to pass through the aperture 318 formed in the cutting blade 310 to lock in the aperture 318. More preferably, the handle includes a pair of locking segments that are circularly shaped and are closely received in a preferred pair of apertures 318, 319 formed in the blade 310. Further, in this embodiment, the locking segment 328 includes a flange portion 329 for engaging at least a portion of an edge of an aperture formed in the blade 310.

Referring now to FIG. 8, in a most preferred embodiment, it is seen that cutting blade assembly 300 of the present invention further comprises a tool 330 that facilitates removal of cutting blade 310 and handle 320 from a sterile packaging container and insertion into a microkeratome assembly while maintaining sterility. Preferably, the tool is in the form of a handle assembly 360 that is attached to handle 320 and facilitates the introduction of cutting blade assembly 300 into access opening 156 on cutting head assembly 50. In the preferred embodiment, handle assembly 360 includes an elongated stem 362 for threaded attachment to the handle, preferably along a side wall of the handle, to facilitate introduction and installation of cutting blade assembly 300 into cutting head assembly 50. If desired, in this or other embodiments, the handle assembly may allow the elongated stem 362 to be reattached to the handle after surgery to remove a soiled cutting blade assembly from the cutting head assembly 50. In an alternative embodiment, handle assembly 360 may comprise an elongated stem that is integrally formed with the handle and may be separated from the handle after the cutting blade assembly is introduced and installed into cutting head assembly 50. It should be appreciated that in this alternative embodiment, the handle assembly may be made of a suitable plastic so that it is formed integrally with the preferred handle 320, while the entire cutting blade assembly may be easily packaged in a container so that it can be sterilized prior to shipment and maintained in a sterilized condition while in transit. In this manner, handle assembly 360 and the attached cutting blade assembly 300 may be easily removed from the sterile package, while handle assembly 360 is used to quickly and easily insert cutting blade assembly 300 into cutting head assembly 50 of the microkeratome while maintaining sanitary conditions. Thereafter, the handle assembly 360 may be broken away from the cutting blade assembly 300 and discarded or disposed of.

Reference is now made to fig. 5 for an explanation of other features of the preferred microkeratome apparatus. In this preferred embodiment, the housing 51 of the cutting head assembly 50 contains a depth adjustment device 75 therein to adjust the depth to which the cutting element 70 cuts into the cornea. As shown in fig. 5, the depth adjustment device 75 is preferably disposed on the front face 52 of the main housing 51 and constitutes at least a portion of the bottom wall of the housing 51 in the vicinity of the front face 52. Preferably, the depth adjustment means 75 comprises a separate nose section 76 which is securely but removably attached to the housing 51 by conventional fasteners 74, such as screws, bolts or the like, as is conventional. Preferably, the nose section 76 includes a bite section 77 and a variable depth plate 78. The bite section 77 preferably includes a distal end 79 that forms a "V" shape and preferably extends across the width of the nose section 76. The structure is sized and shaped to be received and nest within a corresponding cavity forming an inverted "V" shape and formed between oppositely disposed side wall structures 53 of the housing 51 adjacent the front face 52. It will be appreciated that this configuration provides for an extremely stable nesting or retention of the tip 79 within the housing 51 even though the cutting head assembly 50 is moving along an arcuate path past the positioning ring 32. Further, as shown, the variable depth plate 78 is preferably integrally formed with the bite section 77 and is disposed substantially horizontally. In FIG. 5, the depth of the variable depth plate 78, which is preselected by the surgeon based on the desired depth of incision into the cornea, is indicated by "H". Another feature of the present invention is the provision of a set of nose segments 76, each of which contains a plate member 78 having a different depth "H". As can be seen in FIG. 5, as the cutting head assembly 50 is advanced in the direction of arrow "A" and pressed against the cornea during surgery, the depth of plate member 78 has an inverse relationship to the depth of the incision into the cornea. For example, a plate 78 having a greater depth "H" will obscure more of the blade cutting edge 71, while a plate 78 having a lesser depth "H" will expose a greater area above the blade cutting edge. Thus, it will be appreciated that different sized depth adjustment devices 75 may be replaced in the cutting head assembly 50 to precisely meet the needs of the patient undergoing the procedure. Ideally, the present invention provides two different sizes of nose segments 76, one size for a 130 micron cutting depth and the other size for a 160 micron cutting depth, which are currently the most desirable depths to cut into and expose the cornea for reshaping.

As previously mentioned, the housing 51 of the cutting head assembly 50 also contains a rail arrangement 60. Referring to fig. 2, in the preferred embodiment, the track arrangement 60 is disposed on a lower peripheral region of the housing 51 for mating engagement with and being guided within the channel member 42 of the positioning ring 32, the channel member 42 being as shown in fig. 3. For example, in the preferred embodiment, the rail means 60 is in the form of a flange 62 that rests on the depth adjustment means 75 and is integrally formed with and in the same plane as the variable depth plate 78, see FIG. 2. Preferably, the flange 62 extends in a vertical direction beyond the perimeter of the housing 51 defined around the side wall 53. In addition, while the cutting head assembly 50 is configured to receive the nose section 76 with the variable depth plate member 78, the flanges 62 extending from the variable depth plate member are of the same height to accommodate and effectively mate with and be guided within the channel member 42 of the retaining ring 32. Although the flange 62 may extend from only one side of the housing 51, in the preferred embodiment, a flange 62 is positioned on each side of the variable depth plate 78 to facilitate use of the invention with both the left and right eyes of a patient.

Also as previously described, the main housing 51 carries a stop or detent 65 thereon which serves to limit, and preferably completely prevent, the movement of the cutting head assembly 50 past the positioning ring 32. In the preferred embodiment, the stop means 65 is formed on the surrounding side wall structure 53 generally at the rear end surface 54 and includes a shoulder 66 formed between the side wall structure 53 and the rear end surface 54 of the housing 51 and of sufficient size to not pass through the channel member 42 of the guide means 40 and thereby prevent any further forward movement of the cutter head assembly 50 past the locating ring 32. When shoulder 66 engages channel member 42 via lip 43' against it, drive 80 is stopped and reversed to move cutter head assembly 50 in the reverse direction. As previously mentioned, it was determined that in the last few years, the corneal layer that was cut off should not be completely severed when corneal surgery was performed. A unique feature of the cutting head assembly 50 of the present invention is that cutting the cornea C results in a corneal flap F, as shown in fig. 1, which is also safely preserved by the assembly 50. To preserve the corneal flap F, the housing 51 includes a corneal flap receiving slot 59 formed in the housing 51. As shown in FIGS. 2 and 5, the corneal web receiving slot 59 is disposed generally at the front face 52 of the housing 51 and, in particular, is formed by a gap formed between immediately forward of the blade cutting edge 71 and immediately rearward of the variable depth plate 78. Thus, the corneal-membrane receiving slot 59 is disposed on a pair of bottom surfaces of the housing 51 and extends upwardly into the housing 51. Desirably, the corneal web receiving slot 59 extends into the two opposing sidewall structures 53 of the housing 51.

In preparation for use of this preferred microkeratome apparatus to cut the cornea: a) a sterile modified cutting blade assembly 300 is slid into place in the cutting head assembly 50, and b) the coupling 90 is installed in the cutting head assembly 50, coupling the drive means 80 and engaging the cutting head assembly. Referring to FIG. 2, as an additional feature, the cutting head assembly 50 may contain indicia 67 for indicating to the surgeon which eye the device will be used to cut. For example, it is preferable to use such a mark as the letter "L" for the abbreviation "left side" or "left eye" and the letter "R" for the abbreviation "right side" or "right eye", or equivalent words, foreign abbreviations or symbols may be used. This indicia is preferably present on two opposing sidewall structures 53 of the main housing 51 of the cutting head assembly 50 in a position that can be selectively concealed by the coupling 90. Specifically, when connected to the cutting head assembly 50 and used to cut a right eye, the connector 90 extends down into the left side of the main housing 51 of the cutting head assembly 50, exposing only the right side, so that the preferred "R" indicia on the right side is visible. Conversely, when assembled to cut the left eye, the connector 90 extends down into the right side of the housing 51, leaving only the left side and the indicia on the left side visible. It will be seen that a further safety feature may be obtained in this way to ensure that the device is properly aligned with the patient's eye.

Next, once the positioning ring 32 is centered on the eye and a suitable vacuum is applied to temporarily attach it to the eye, c) the guide track arrangement 60 of the cutting head assembly 50 can be mated to the guide 40 of the positioning ring 32 in an initial, i.e., starting, position. After power is supplied to the microkeratome apparatus, the cutting head assembly 50 may be moved across the positioning ring and cut the cornea C until the stop 65 contacts the channel member 42 of the positioning ring 32 to limit, and preferably prevent, further forward movement of the assembly. It can also be seen that in this rest position, the cutting element 70 does not move completely across the cornea C, but cuts a portion of the cornea up to this point, thereby creating a corneal flap which adheres to the cornea and is represented by the area marked "F", as shown in figures 10-A and 10-B. In addition, as shown in FIG. 5, the resulting corneal flap is guided upwardly into the corneal flap receiving slot 59 of the housing 51 by the forward motion of the assembly to be stored and to keep the cutting element 70 clean. Once the assembly is stopped, as shown in FIG. 10-B, the drive mechanism 80 will be reversed to move the cutting head assembly 50 in a reverse direction so that no more cornea is cut and the corneal membrane F is safely removed from the corneal membrane receiving slot 59 of the housing 51. Thus, when the cutting head assembly 50 is returned to a position similar to that shown in FIG. 10-A, it can be disengaged from the stop 30. The corneal sheet F can then be manipulated, preferably by laser surgery, to reshape the cornea. Once the procedure is complete, the corneal flap will be replaced to cover the cornea.

Another unique feature of the present invention is that not only can a corneal membrane be created, but importantly, the corneal membrane is positioned in such a way that blinking of the eye after surgery does not dislocate the corneal membrane. Referring also to fig. 10-a and 10-B, a preferred microkeratome apparatus is shown schematically on the left and right eyes of a patient. In fig. 10-a, the reference points of the working environment are the same as some of the numbers on the dial of the clock. Thus, in fig. 10-A, it can be seen that the cutting head assembly 50 is preferably positioned in an initial position at approximately five o 'clock relative to the patient's left eye. The cutting head assembly 50 is preferably positioned in an approximately seven o 'clock position relative to the patient's right eye in the initial position. Turning now to fig. 10-B, the cutting head assembly 50 has been moved to a position approximately aligned with twelve o' clock with the stop 65 bearing against the channel member 42 engaging the retaining ring 32, thereby preventing further forward movement of the assembly. Thus, it will be appreciated that the cutting head assembly 50 is preferably aligned approximately at the twelve o 'clock position, whether the procedure is applied to the patient's left or right eye. As can also be seen in FIG. 10-B, the resulting corneal flap F is attached to the cornea in an upper region of the cornea. As a result, after the cosmetic surgery on the cornea is completed, the orientation of the corneal lamellae is substantially the same as the natural blinking direction of the eye. That is, it is believed that the patient's downward blinking action may hit the corneal flap downward, thereby helping to keep the corneal flap in its recovered position on the cornea to avoid astigmatism.

Referring now to fig. 9, the driving device 80 of the present invention: a) for driving the cutting head assembly 50 through the previously described eye stop and positioning device 30; and b) for causing the cutting element 70 to oscillate back and forth within the housing 51. In a most preferred embodiment, the drive assembly 80 will drive the cutting head assembly 50 through the eye position and location apparatus 30 and the eye held therein at a speed that will allow the cutting head assembly to travel in the first direction for 3 to 6 seconds and in the second direction for the same amount of time. Further, in a preferred embodiment, the drive device 80 includes a motor 100, which, as well as other components included in the drive device, will be explained hereinafter, the motor is electrically controlled, and more preferably is a micro-motor that operates at a constant and uniform speed regardless of the load size. In particular, under normal conditions, the natural resistance encountered by the cutting head assembly 50 as it is driven across the cornea will cause the resistance in the micro-motor coil to increase, resulting in a decrease in voltage and a decrease in speed. While some prior art systems in microkeratome devices attempt to avoid excessive speed reduction by employing an overpowered motor to maintain the speed reduction within 10%, the motor 100 of the present invention preferably monitors the current flowing through the motor, for example, by an operational amplifier, and uses this information to control the supply voltage and maintain a substantially constant speed. This method of monitoring and compensation is sometimes referred to as IR compensation, so that a common 12V regulated voltage can be used for the DC motor to effectively maintain a constant velocity of the cutting head assembly 50 across the eye.

Referring now to fig. 4 and back to fig. 9, it can be seen that in the preferred embodiment, the microkeratome apparatus drive assembly 80 also includes a gear box 81 into which a motor main drive shaft 101 extends. A cutting assembly main drive shaft operably extends from the gearbox 81, and in particular, concentrically extends from a constraining hub 110, as shown in fig. 4 and 5. The cutting assembly main drive shaft comprises two main parts, namely: a) a threaded drive screw or "worm" 115, shown in FIG. 9, which is the middle portion and passes through the constraining hub 110; and b) an oscillating shaft 130, also shown in FIG. 9, which is the innermost portion and passes through the screw 115.

Looking first at the constraining bushing 110, as shown in FIG. 4, it is the outermost portion, preferably extending downwardly from the gear case 81, for mating and preferably threaded engagement in the threaded bore 58 formed in the main housing 51. In this manner, constraining sleeve 110 serves to lock drive 80 to cutting head assembly 50. In addition, it can be seen that the drive means 80 can enter the cutting head assembly 50 through a top surface 56' and thus be disposed generally vertically. It is believed that this feature will result in less interference with the surgical field and more convenient precision manipulation by the surgeon than existing conventional microkeratome devices. In particular, the drive means in existing microkeratome devices are typically horizontally positioned, resulting in the surgeon having to carefully handle the drive means, which, if not properly handled, can delay operation of the microkeratome device and/or result in differential pressure being applied to the microkeratome. In addition, the configuration of the present invention allows the center of gravity to be maintained substantially over the center of the eye, unlike older systems, thereby improving balance and ensuring that the cutting head assembly does not accidentally topple over the surface of the eye during use.

As shown in fig. 5, the oscillation shaft also extends from the gear case. Turning now to fig. 9, the oscillating shaft 130 extends into the housing through the bore 58 in the housing 51 and preferably as a separate element concentrically through the screw 115 and out both ends of the screw. The oscillating shaft 130 is preferably free to rotate relative to the screw 115 and includes an upper drive portion 132 which may be welded to the shaft 130 and which is in timed driving engagement with a main drive shaft 102 secured to the motor main drive shaft 101. Thus, a rotational movement of the motor main drive shaft 101 will result in a corresponding rotation of the oscillation shaft 130. Furthermore, an oscillating pin 135 eccentrically projects from the opposite end 134 of the oscillating shaft 130. Oscillating pin 135 is preferably biased downward to maintain a restraining pressure on cutting element 70, and extends into a slot 72' formed in an upper surface of preferably shank 72, or other means 325 formed on the shank for receiving the oscillating pin and allowing the oscillating pin to transmit motion. Thus, as oscillation pin 130 is axially rotated, oscillation pin 135 rotates at a predetermined off-center radius and alternately engages opposite sides of slot 72' in shank 72, thereby imparting alternating oscillating motion to blade 72 and the cutting blade it holds.

Referring to fig. 9, the oscillating shaft 130 further includes a sub-driving portion 133. The secondary drive portion 133 drivingly engages a first internal drive gear 103 housed within the gear housing 81. The first internal drive gear 103 is connected and drivingly secured to an internal drive shaft 104. the internal drive shaft 104 preferably includes a second internal drive gear 105 spaced from the first internal drive gear 103. Thus, as the oscillation shaft 130 rotates, the second internal drive gear 105 also rotates.

Referring also to FIG. 9, a threaded drive screw or "worm" 115 is drivingly connected to the second inner drive gear 105 and extends from the interior of the gear housing 81 concentrically through the constraining bushing 110. A screw 115 extending upwardly into the gear box 81 includes a drive head 116 which engages the second internal drive gear 105. As a result, as the inner drive shaft 104 rotates, the screw 115 correspondingly rotates within the housing 51 of the cutting head assembly 50. In addition, a worm gear 120 is rotatably disposed in the housing 51 and operatively engages the screw 115. The worm gear 120 preferably comprises a radially enlarged central portion 120 having a plurality of drive recesses formed around the periphery of the central portion for engaging the outer threaded surface of the screw 115 so that when the screw 115 is rotated about a vertical axis, the central portion 122 and thus the entire worm gear 120 rotate about a horizontal axis. Note that the screw-like threaded surface of the screw 115 ensures that the screw 115 does not move vertically when rotated and does not overly engage the drive recess on the turbine when the drive turbine 120 is rotated. A propeller shaft 125 extends from at least one, but preferably both, vertical surfaces of the turbine's central portion 122. The propeller shaft 125 with attached guide means extends from the side wall structure 53 of the main housing 51 and engages the toothed track 43 on the locating ring 32 so that as the worm gear 120 rotates, the propeller shaft 125 rides along the toothed track 43 as the propeller shaft 125 rotates and moves the cutting head assembly 50 smoothly over the locating ring 32 in a constant and defined step. In addition, it can be seen that as the motor main drive shaft 101 changes direction of rotation within the gear box 81, the direction of rotation of the worm 115 and hence the worm gear 120 changes, thereby back-driving the cutting head assembly 50 across the locating ring 32. In addition, to facilitate the movement on the toothed track 43 and its arcuate path, it is preferable to include a helical gear structure on the propulsion shaft 125 portion of the turbine 120, i.e., with a set of inclined ridges, to more effectively align and move on the curved toothed track 43.

Now turning to the motor 100, it is preferably controlled by a foot pedal or similar actuator. Where a foot pedal is used, it is preferred to use a dual function foot pedal, such that one side is used to drive the motor main drive shaft 101 and cutting head assembly 50 in a forward direction and the other side is used to drive them in a reverse direction. In addition, the system may be set to a manual mode, such that the surgeon himself must positively change the direction of movement, or may be set to an "automatic reverse" mode, such that the cutting head assembly 50 automatically travels in the reverse direction when it is moved to the maximum distance. In either case, however, the motor 100 is preferably equipped with a sensor to detect a sudden increase in current. Specifically, when the cutting head assembly 50 touches the brake 65, its continued forward movement is partially or completely prevented, and a sudden increase in current may occur in the motor 100. Upon detection of such a sudden increase in current, a signal is sent to turn off the power or reverse the motion, depending on the desired settings of the physician.

As previously mentioned, the preferred microkeratome device can be used on both eyes of a patient, see FIGS. 10-A and 10-B. In particular, the cutting head assembly may be applied to the patient's other eye by passing the worm gear 120 through the housing 51 and extending from the other side of the housing 51 around the side wall structure 53. To this end, because the cutting head assembly 50 has a symmetrical configuration, the drive device 80 need not be removed from the housing 51 and the attachment device 90 to be rotated 180 degrees for use on the other eye of the patient.

Considering again the drive means 80, it should be noted that when performing surgery on the eye, the drive means must operate together and in synchronism as a whole. Thus, the present invention is also directed to the combination of the drive device 80 and the suction device as part of a single overall control assembly 200. The control assembly 200 of the present invention comprises a portable housing 205 from which power and control signals are passed via a cable 203 to the drive means 80 interacting with the cutting head assembly 50, and from which the vacuum source for the suction means is supplied by a vacuum hose 202. The suction device and its vacuum source will be accessed first. Specifically, the vacuum source generally comprises a vacuum pump 210 housed in the housing 205 and supplied with a common power source and operable to generate a vacuum to create a suction force on the retaining ring. In addition to the vacuum pump 210, the suction device of the present invention also includes a vacuum storage tank 215. The vacuum reservoir 215 may be charged with vacuum after the control assembly 200 is activated. Furthermore, if operation of the vacuum pump is interrupted, such as upon loss of power, the vacuum reservoir 215 preferably immediately creates sufficient vacuum to hold the positioning ring on the eye until movement of the cutting head assembly 50 over the eye is complete. In particular, the control assembly 200 may automatically activate the vacuum reservoir 215 when operation of the vacuum pump 210 is interrupted due to a loss of power or other reason, so that the cutting head assembly can be moved completely across the eye without a dangerous and unintended interruption due to interruption of operation of the vacuum pump 210.

The vacuum pump 210 is preferably controlled by a computerized process controller 220 in the housing 205 in accordance with the present invention. The process controller 220 is primarily functional when the control assembly 200 is on and/or in a "ready" mode. Specifically, when the control module 200 is first turned on, it may perform a plurality of overall tests and display them on a display screen 211, while the vacuum pump 210 is preferably controlled to first create a vacuum in the vacuum reservoir 215. Thereafter, the vacuum pump preferably continues to operate until a desired vacuum relative to atmospheric pressure is created. Once the desired vacuum is achieved, the operation of the vacuum pump is cycled. For example, once the desired level is reached, the vacuum pump 210 may be turned off until the vacuum drops to a predetermined point relative to atmospheric pressure. At this point, the vacuum pump 210 is preferably turned on again by the process controller 220 to return the vacuum state above the desired level. In this way, a back-up vacuum can be provided for use when needed.

In this preferred embodiment, the control assembly 200 remains in the "ready" mode until the user wants to initiate operation or perform additional tests as needed. Once operation has begun, the user typically depresses the next foot pedal 216 or other switch to activate the vacuum and switch the control assembly to an "operating" mode. Before entering the "before operation" mode, a "before operation" mode is preferably initiated, wherein the control assembly 200 will complete a plurality of internal tests. Unlike the "ready" mode, the vacuum pump 210 will preferably remain on once the "operating" mode is entered, ensuring that sufficient vacuum is always provided. Furthermore, to ensure that vacuum generation is not affected in the event of a failure of process controller 220, once the "run" mode is entered, control of the vacuum pump is disengaged/interrupted from process controller 220 and switched to a separate logic controller 225, such as one or more PAL chips. Preferably, the control transfer is accomplished by a latching switch 228 connected between the process controller 220 and the logic controller 225. The latching switch 228 is used in its normal position to connect the process controller 220 to the vacuum pump 210, but after entering the "run" mode, the latching switch is used to connect and activate the independent logic controller 225. Preferably, this connection to the separate logic controller 225 will be maintained until positively reset by the user. For example, a reset switch 229 may be incorporated into the housing 205 to reset the latching switch 228.

Referring now also to the suction device, while the power supply to the vacuum pump 210 requires a high voltage, the vacuum pump and other high voltage components in the control assembly need to be isolated from the low voltage portion in the housing 205, as the low voltage portion is about to come into contact with the patient. In this regard, in some cases, the vacuum pump 215 sometimes experiences a temporary loss of power, thus requiring a state reset prior to normal operation. For example, if the current jumps from about 0.6 amps to about 1.3 amps, the control assembly will preferably recognize a "pump blocked" condition and initiate a warning signal. If a "pump-up" condition is identified that continues to exist, the vacuum reservoir is preferably immediately activated to maintain vacuum to ensure that the procedure is completed. However, if the "pump blocked" condition is identified only temporarily, the vacuum pump will continue to operate normally. If a full vacuum is still maintained, the vacuum pump will not normally be re-operated even if a temporary blockage occurs, which temporarily releases the vacuum before the vacuum pump is re-operated. However, the release of the vacuum must be controlled by the low voltage side of the control assembly 200. Therefore, the present invention preferably employs an optocoupler 240 to initiate the temporary release of vacuum. Specifically, when the current jump phenomenon described above, which is typically associated with a "pump-up" condition, occurs, the current jump across a resistor 241, preferably 0.75 ohms, is sufficient to activate an LED 242 on the optocoupler 240. The LED 242, preferably passing through a pulse expander 243, will preferably activate a facing semiconductor chip 245 which in turn activates a valve 247 to cause the temporary release of vacuum required for continued operation of the vacuum pump 210. Therefore, full isolation is maintained between the high voltage side and the low voltage side of the assembly.

Turning now to the other aspect of the control assembly 200, namely the drive means 80, the drive means is preferably powered by a motor 250 housed within the control assembly 200. The motor 250 is sufficient to drive the cutting head assembly 50 across a positioning ring, such as the positioning ring 32, and is preferably capable of operating in forward and reverse directions. Furthermore, to prevent overloading and/or burnout of the motor, the control assembly 200 may detect when the increase in amperage exceeds a predetermined limit, preferably at least 300 milliamps, which typically means that movement of the cutting head assembly 50 is stopped and operation of the motor and drive is prevented. The stopping of the cutting head assembly 50 may be due to either an obstruction in the path of movement across the positioning ring, such as some eyelashes or other particles, or due to the normal stopping of the cutting head assembly 50 after the cutting is completed. In either case, however, if the motor 250 increases in amperage by at least 300 milliamps over a continuous time interval, preferably about 3 seconds, the motor will shut down until reset by the user. At reset, the user may temporarily remove pressure from foot pedal 252 to reset and restart the foot pedal, thereby allowing motor 250 to continue to move until the next increase in amperage is detected for more than 3 seconds. In this preferred embodiment, such incremental timer amperage detection is used only for the forward direction and not for the reverse direction. Alternatively, a more absolute limit, preferably set at 400 ma, may be used for both forward and reverse directions.

In addition to the cessation of operation of the drive mechanism 80 which may be caused by the cessation of motion, when there is a loss of suction to the positioning ring which may result in the temporary or complete detachment of the positioning ring from the eye, the control assembly 200 also preferably immediately turns off the motor 250 and thus the drive mechanism. As a result, the cutting head assembly 50 will not continue to cut if the positioning ring is loosened from the eye or is not properly temporarily attached to the eye. Furthermore, if such a shutdown occurs, the mode of operation must be completely resumed before the motor 250 resumes operation, including a normal series of system checks and reestablishment of vacuum.

It should be noted that the vacuum pump 210 of the present invention is preferably provided with a back-up device in the form of a vacuum reservoir 215 that will operate when the vacuum pump 210 fails, for example, due to a loss of voltage. Similarly, the motor 250 is also preferably provided with a backup power source 260, such as one or more lithium batteries, disposed in the housing 205 of the control assembly 200. The backup power supply 260 is most preferably included in and forms a part of the control assembly 200 and supplies the operating power to the motor 250 immediately upon loss of power from the ordinary supply power. In this way, the eye can be completely cut even if a power failure occurs, thus eliminating the need to remove and/or restart the cutting head assembly 50 mid-cut.

Finally, it should be noted that in some instances, the user may not readily observe the display screen 211 of the control assembly 200 while monitoring the patient's condition, particularly after they have observed a larger display table for monitoring other patients. Thus, the control assembly 200 of the present invention includes an interface 265, such as a serial interface, through which a computer interface is available and information regarding the operation of the control assembly 200 is transmitted for convenient use and display on a larger computer display.

Since many modifications, improvements and changes in the embodiments described above are possible, it is intended that all aspects described above and shown in the accompanying drawings be considered in all respects as illustrative and not restrictive.

Claims

1. A cutting blade assembly (300) for use with a surgical device for at least partially cutting through a cornea of an eye of a patient, the surgical device including a drive mechanism, said cutting blade assembly comprising:

a) a cutting blade (310) having:

i) a front portion (312), said front portion comprising a sharpened forward cutting edge (313);

ii) a rear traction portion (314) comprising a rear edge (315);

iii) a pair of side edges (316, 317) connected to said front portion and said rear traction portion; and

b) a handle (320) operably connected to said cutting blade (310) driven by said drive means of the surgical device, wherein said at least one side edge (316, 317) of said cutting blade (310) tapers at least partially from said forward portion (312) to said rearward traction portion (314).

2. A cutting blade assembly according to claim 1, wherein said pair of side edges (316, 317) extending between said front portion (312) and rear traction portion (314) are rounded.

3. The cutting blade assembly of claim 1, wherein said cutting blade (310) is flat.

4. The cutting blade assembly of claim 1, wherein said shank (320) is made of plastic so as to be disposable.

5. The cutting blade assembly of claim 1, wherein said trailing edge (315) of said trailing portion (314) of said cutting blade (310) is parallel to said forward cutting edge (313) of said forward portion (312) of said cutting blade (310).

6. The cutting blade assembly of claim 1, wherein said forward portion (312) of said cutting blade (310) is larger than said rearward trailing portion (314) of said cutting blade.

7. The cutting blade assembly of claim 1, wherein said forward portion (312) of said cutting blade (310) has a rectangular shape and said rearward trailing portion (314) of said cutting blade (310) has a trapezoidal shape.

8. The cutting blade assembly of claim 1, wherein said cutting blade (310) includes at least one aperture (318) formed therein.

9. The cutting blade assembly of claim 8, wherein said cutting blade (310) is shaped to include at least one second aperture (319) therein, said aperture (318) and second aperture (319) having a circular configuration.

10. The cutting blade assembly of claim 9, wherein said aperture (318) and second aperture (319) formed in the cutting blade (310) are located in said trailing portion (314) of said cutting blade and have a circular shape.

11. The cutting blade assembly of claim 9, wherein said rear traction portion (314) of said cutting blade (310) includes a pair of said aperture (318) and a second aperture (319) formed therein that are disposed flush with one another.

12. The cutting blade assembly of claim 9, wherein said shank (320) has a bottom side, said bottom side of said shank being secured to said cutting blade (310) at said aperture (318) and second aperture (319) formed in said cutting blade, and a top side (322) containing means for being operably driven by a driving means.

13. The cutting blade assembly of claim 12, wherein said means on said handle (320) for being operably driven by said drive means comprises a recess (326) formed in said handle.

14. The cutting blade assembly of claim 13, wherein said recess (326) in said shank (320) is oval.

15. The cutting blade assembly of claim 8 or 9, wherein the shank (320) includes a locking section (328) configured to pass through the aperture (318) in the cutting blade (310).

16. The cutting blade assembly of claim 15, wherein said locking segment (328) includes a flange portion (329) configured to engage an edge of said aperture (318) formed in said cutting blade (310).

17. A cutting blade assembly according to claim 1, wherein said sharpened forward cutting edge (313) of said cutting blade (310) is shaped to have an angle which is between 5 and 10 degrees offset from a horizontal axis of said cutting blade (310).

18. The cutting blade assembly of claim 1, further comprising a handle assembly (360) removably attached to the handle (320) of said cutting blade assembly and configured to facilitate introduction of said cutting blade assembly into an access opening (156) of a cutting head assembly (50).

19. The cutting blade assembly of claim 18, wherein said handle assembly (360) is configured to be reattached to said handle (320) to facilitate removal of said cutting blade assembly from the cutting head assembly (50).

20. The cutting blade assembly of claim 18 or 19, wherein the handle assembly (360) includes an elongated stem (362) configured to be coupled to the handle (320) along a sidewall of the handle.

21. A cutting blade assembly according to claim 18 or 19, wherein said handle assembly (360) includes an elongate stem (362) formed integrally with said shank (320) and configured to be separated therefrom upon introduction of said shank (320) into the cutting head assembly.

22. A medical device comprising a cutting blade assembly (300) and a surgical device for cutting through a cornea of an eye of a patient,

the cutting blade assembly includes:

a) a cutting blade (310) having:

ii) a rear traction portion (314) comprising a rear edge (315);

b) a shank (320) operably associated with a cutting blade (310), said at least one side edge (316, 317) of said cutting blade (310) at least partially tapering from said forward portion (312) to said rearward traction portion (314);

the surgical device includes:

a) a positioning ring (32) with means for temporary attachment to a portion of the eye around a cornea to be cut; said positioning ring (32) defining an aperture (330) sized to receive and expose a cornea to be cut;

b) said retaining ring including guide means (40) formed along an arcuate path on one surface of the retaining ring;

c) a cutting head assembly (50) housing said cutting blade assembly (300) for cutting the cornea, said cutting head assembly being constructed and arranged to be driven through said positioning ring (32) along said arcuate path defined by said guide means (40);

d) a drive (80) operably connected to said cutting head assembly (50) for causing said cutting head assembly to move through said positioning ring (32) and cause said cutting blade assembly (300) to oscillate;

e) said cutting head assembly (50) comprises a main housing (51) having: a top surface (56'), a bottom surface, a front end surface (52), a rear end surface (54), and a surrounding sidewall structure (53) located between said surfaces and end surfaces; an internal cavity (88) configured to receive and retain said cutting blade assembly (300) in a cutting position; and a cutting opening (56) formed in said bottom surface for exposing a leading cutting edge of said cutting blade assembly.

23. The medical device of claim 22 wherein said surrounding sidewall structure (53) has an access opening (156) formed therein and disposed in correspondence with said interior cavity (88) to allow at least said cutting blade assembly to be easily inserted into and removed from said main housing (51).

24. The medical device of claim 23, wherein said access opening (156) is constructed and arranged to pass completely through said surrounding sidewall structure (53) of said cutting head assembly (50) from side to side.