CA2112095A1

CA2112095A1 - Intraocular surgical scissors

Info

Publication number: CA2112095A1
Application number: CA002112095A
Authority: CA
Inventors: Kirk H. Packo; Thomas Ying-Ching Lo; Franklin Tao; Tolentino Escorcio
Original assignee: Individual
Current assignee: Alcon Grieshaber AG
Priority date: 1991-09-23
Filing date: 1992-09-22
Publication date: 1993-04-01
Also published as: JPH07507935A; AU2651392A; EP0610247A1; ATE197238T1; WO1993005718A1; US5275607A; ES2150920T3; JP3381792B2; DE59209876D1; EP0610247B1; EP0610247A4

Abstract

An intraocular scissors (20) including a handpiece (22) which supports a detachable assembly (24) having a pair of elongated relatively reciprocable blade members (28, 30) suitable for intraocular surgery. One of the blade members (28) is fixedly mounted with respect to the handpiece (22) and the other (30) is mounted for reciprocating movement. Drive means (26) including a linear actuator are provided to operate the scissors (20) in various modes including different rates of movement of the reciprocating blade member (30). The various modes include (1) oscillating the blades open and closed at a low frequency of 1-5 cps; (2) oscillating at low frequency and simultaneously vibrating at a high frequency;
and (3) vibrating the blades a small amount at a high frequency of 500 cps or greater with the blades in a selected partially open position.

Description

2~11209~ .
INTRAOC~LAR 8URGICAL 8C~880R~

This application is a continuation-in-part of United States patent application Serial No. 76~,~18, filed on September 23, 1991.

Bac~roun~ o$ tho I~ention This invention relates to an improved intraocular surgical instrument which can be used with microsurgical scissors, forceps, knives and the like.
The invention will be described in connection with its preferred usaqe and that is a microsurgical scissor. Microsurgical scissors are in widespread use during intraocular operations by surgeons worldwide.
Three types of driver (actuation) systems for these scissors are in current use: manually operated handles wit~ squeeze-type or lever depr~ssion actuation, pneumatic piston linear drivers, and electrical motors of direct current or ~olenoid drive.
Grieshaber and Co., A.G. of Switzerland produces a wide variety of microsurgical scissors and driver systems including the Proportional Control System (PCS), a M~mbrane Peeler Cutter ~MPC) and manual drive handles (Southerland Style). Pneumatic drivers are produced by Storz Instrument Co. of St. Louis, Missouri;
Alcon Surgical, Inc. of Ft. Worth, Texas; The Dutch Ophthalmic Re~ear h Corporation (D~RC) of Holland; and TREK ~edical of Muckwamago, Wisconsin. Each company provides various scissortips attachable to these drivers, or allow them to cross adapt to other manufacturer's designs. Manual handles are provided by Grieshaber, Alcon, Storz, DORC, TREK and others.
Most intraocular scissors have design similarities in which a pair of cutting blades extend 350 from the end of a tubular need~e with one blade being fixed and the opposite opposing blade end being reciprocated between an open and closed position with 211209~ -2-respect to the fixed blade. This reciprocating movement is accomplished through the action of one of the three above-listed driving systems, i.e., manual, pneumatic or motor.
In the manual driver, actuation of one blade end against the other is through the transfer of movement to the movable blade by depression of a single lever extending from the handle (Southerland-Griesha~er) or by squeezing two opposing platforms on opposing sides of the handle. The movable blade moves through an excursion of 60 to 70 mils (0.060 to 0.070 inch) from the fully open to the fully closed portion during actuation.
In the pneumatic dEiver, actuation is achieved by pressurizing a piston with a compressed gas source into a chamber within the handle, which causes the piston to move forward against a spring, moving the one blade against the other, closing the blades. Opening the - blades is accomplished by movement in the opposite direction through energy stored in the spring, as the gas within the piston chamber is releaseid. Control of the gas pressure release to the piston is accomplished by depression of a foot pedal by the surgeon. Scissor actuation is thus accomplished via foot pedal control rather than via finger control, allowing the surgeon to hold the instrument steady without inducing any unnecessary tremor or motion to the blades due to finger movement. ~he foot switch is a linear depression switch which also allows selection between a "proportional cut"
mode versus a 'Imulticut'' mode by the manufacturer~ In the "proportional cut" mode, the scissor blades close at a rata and poisition directly related to the rate and position of depression of the pedal, e.g., one-half depression of the pedal will close the scissors half way, full depression will close the scissors fully, etc. The scissors will move open and closed inducing a cutting force only as the foot pedal is depressed and released, with a more rapid depression resulting in a more rapid W093/05718 2 1 1 2 0 9 5 PCT/USg2/07g47 closure, etc. A full depression of the foot pedal by the surgeon closes the blades to reduce the width of the scissor blade profile so that it can be inserted through r a small slit, e.g., 1.0 mm slit, in the eyeball. Once 5 within the eyeball, the ~cissor blade can be opened and closed by the foot pedal action described above. To remove the scissors from the eyeball, the blades are fully closed by complete deprecsion of the foot pedal to again reduce the scissor width. In the event of failure 10 of the piston driver while it is in the eyeball, the surge~n can manually close the scissors in this emergency situation by screwing a thumbscrew down on the driver to allow its safe removal from ~he eye. While the scissors are in the eye, the surgeon can select the "multi-cut"
15 mode by the temporary lateral motion of the foot pedal.
Depression of the pedaI in this mode causes movement of the blade from its opén to $ts closed position and back to its open position repetitively at a rate of approximately one stroke per ~econd. A slight depression 20 of the foot pedal activates this multiple repetition mode, which continues at the same rate regardless of the amount of depression to the pedal. The surgeQn returns to the "proportional cut" mode and fully depresses the pedal to fully close the scissor blades and holds them 25 closed to remove them from the eye.
Motor drivers of the rotary solenoid style activate scissor closure by controlled transfer of the motor energy to the movable blade. The NPC is an automated solenoid-style microscissors that has a 30 nondetachable pair of cutting blades extending from the end of a tubular needle, with the outer blade end being fixed and the inner blade end being reciprocated between an open and closed position with respect to the fixed blade. A first foot switch is operated by the surgeon to 35 move the movable blade to a closed position reducing its profile~allowing its introduction into the eye. Once inside the eye, the first foot pedal is released and the ':
~: ~ .. . . ..

W093/Os718 PCT/US92/o~g47 21 1 209 ~ -4-movabla blade snaps open due to energy stored in a spring within the driver handle. Depression of a second foot pedal causes the blades to move from an open position to a closed position against a spring, and then back to an open position. The scissors always default to an open position during activation of the second foot pedal. The blade excursion is again 60 to 70 mils (0.060 to 0.070 inch) and travels at a rate of lO00 mm/sec from the open to the closed position. The moving blade cuts in about S
milliseconds and remains shut for about lS milliseconds before automatically returning to the open position. The MPC can also be operated in a "single cut" mode versus a "multicut" mode. In a single cut mode, depression of the second foot pedal results in one excursion of the movable lS blade and one resulting cut. Release and re-depression ~; of the second foot pedal is required to initiate a second excursion and cut. In the "multicutH mode, hereinafter referred to as an oscillation or oscillatory mode, the blade moves through a series of repetitive cuts or oscillations at a rate of one to five ~trokes per second, with each stroke traveling at lO00 mm/sec. These oscillations continue while the second foot switch is held in the depressed position. This MPC microsurgical scissor is gas sterilizable and is not recommended to be steam autoclaved, except in "emergency situations", as would be desirable for an intraocular scissor.
In the PCS-Grieshaber system, there is a power operation and control of a variety of Southerland intraocular instrument tips including a sciæsors by energy from a D.C. motor within the handle. This PCS
system includes movement of the cutting blade in either the "single" stroke cutting mode or a continuous . , , . .~
oscillatory motion mode. Manual selector switches allow choice between these modes, as well as selection of the rate of scissor closure for either mode, and the rate of oscillations in the oscillatory mode. Additionally, a manual dial switch allows the opening distance between , .

-the radius of curvature of the blades to range from 1/3, 2/3 or full.
In the NPC auto~ated microscissors and in some other Southerland and manual scissors, the scissor tip is of the vertical design in which the outer fixed blade has a cutting edge substantially Darallel to the cutting edge of an inner movable blade such that the cutting edges cut on a substantially straight line on a guillotine principle. The surfaces are not perfectly parallel, however, and do have some angle between them, creating a cutting point where the blades are in contact. The ~PC
scissors close so quickly, however, that their cutting point is effectively a strai~ht line rather than a single point as in conventional angled scissors described below.
Shear is a force responsible for division of the tissue held within the scissor blades regardless of their design, and describes a vector perpendicular to the vector of movement of the direction of closure to the blades. The strength of the force vector pushing the blades one against the other i8 responsible for the creation of the shear force vector.
Guillotine or parallel blade scissors tend to crush the tissue between the blades before the shear begins to divide the tissue. This crush action has an advantage of holding ~he tissue within the blades and preventing forward thrust of the ti~sue out from the blades. It has a distinct disadvantage, however, of creating crush artifact in the tis ues due to tissua deformation that occurs prior to its shearing, as illustrated in FIGS. 25 and 26 hereinafter. Due to motion of the scissors between cuts and the ina~ility to begin a cut immediately in the exact same position as the ending of the previous cut, the tissue is engaged in a slightly different location, resulting in steps or shoulders between cuts and also in curved or scalloped surfaces on the cut tissue wall, as shown in FIGS. 25 and 26. Parallel or vertical-style scissors manually driven ~ 211209~ -6-exhibit the same tissue sectioning artifacts as the MPC
microsurgical scissor and is shown in FIG. 22.
Angled or horizontal-style scissors can be manually or automatically driven depending on the 0 5 manufacturer, but the cutting characteristics are similar, and different from vertical scissors. In angled scissors, the blades pivot from a fulcrum point and create a single cutting point where the blades are in contact. When the blades are fully open, this point is closest~to the fulcrum and successively moves forward down the scissor blades toward the tip as the scissor closes. The blades also become relatively more parallel as they close and begin to induce some crush action near the tip.
As the forward movement of the cutting point ~ proceeds toward the tips of the blades it induces a s`~ forward thrusting motion to the tisæue due to the resistance of the tissue being æheared, thus serving to push the tissue ahead of the ~cissors as it closes.
-~ 20 Al`so, a greater area of tissue is included between the ~ blades during closure, further increasing tissue , .
resistance and thus contributing to increased forward thrust. Forward thrust of tissue during ocular surgery is annoying and clinically undesirable as it contributes to irregular cuts and longer procedures. Needing to "chase" the target tissue puts additional traction on surrounding normal tissue and contributes to tears and accidental cuts within the normal tissue.
With a force applied about the fulcrum of the scissor blades the shear forces are at a maximum when`the ~ cutting point is nearest to the pivot or fulcrum point of - the blades. The blades will sta~ together with the greatest force near the pivot and thus shear is maximum here. Further, less $orce is required to close the blades to create this shear force when the cutting point is near the pivot. As the cut proceeds and the cutting point moves farther from the pivot, mechanical advantage WO g3/05718 PCr/USg2/07947 211209-~

is lost, greater forces are reguired to close the blades, shear force i8 lo~t and the sci~sor blades may actually be pushed apart at the tips if the tissue resistance force becomes greater than the shear force.
In order to maintain a force pushing the blades together at the cutting points, the blades are positioned against each other by two opposing forces called camber.
The radius of curvature of the camber increases along the length of the blade, to create more shear force at the tip to try to overcome some of the loss of shear force due to the loss of mechanical advantage, as shown in FIG.
29.
In cross-section, ~cissor blades are actually asymmetric wedges opposed to each other, and each want to drive into the tissue at an oblique angle called the "preferential wedge path" (FIG. 30). The camber and , closing movement of the blades want to drive the blades , ~ , into the tissue 60- to 90- away from the wedge path (FIG.
31).~ The resulting actual movement of the blade is more ~-~ 20 of a twistina motion as shown in FIG. 32. Because the tissue has resistance to shear, it too will be twisted, more or less by the twisting motion of the blades with softer and thicker tissues twisting and deforming more than harder and thinner tissues. The resulting cross-sectional cut has an "S" shape rather than being perpendicular to tissue surface, as shown in FIG. 33.
Ocular tissues are usually æoft enough to result in "S"
shape cuts by conventional scissors, which is less desirable due to its irregular surface, as shown in FIGS.
23 and 24.
As more of the blade surface becomes buried within the tissue during the cut, the lateral resistance increases, preventing a side-to-side motion or a "steering" re-direction to the scissors. If the scissors 35 ~are wide open, the lateral resistance is at a minimum and the scissors can be steered to a new location without - distortion induced by lateral resistance.

W093/Os7~8 PCTIUS92/07~7 ~t~

211209~ ;
A vibratory angled scisFors was sold by Storz Instrument Company of St. Louis, Nissouri for making corneal incisions. This angled scis~or has been discontinued; and it is described in an article, Spitznas, M., and Krieger, A., n Vibration als Neuartiges Schneideprinzip fur de Augenchirurgie", Klin. Mbl.
Augenheilk, 166: 557-558, 1975. In contrast to guillotine style scissors in which the diameter of the shaft is very small and can be introduced into the eye lo through and operated through a small opening in the eye about the same diameter as the shaft, this angled scissors re~uires a much larger opening. More specifically, in order to create the suitable mechanical advantage in the angled scissors, the proximal end of the scissor needs to be displaced a great distance from the stationary blade end, and this displacement is in a direction perpendicular to the longitudinal dimension of the scissor while the distal scissor displacement is parallel to the longitudinal dimension of the scissor.
In contrast, the guillotine scissors have the excursion ~; of the movable blade parallel to the excursion of the movable blade with both excursions being parallel to the longitudinal dimension of the scissors. Since the excursion of the movable guillotine blade is longitudinal, it generates less friction and less heat through the opening of introduction into the eye than would the Spitznas scissor introduced in a similar fashion. The Spitznas scissor's excursion appears to be about 1 mm and less, which is relatively large excursion, and it oscillates at about 60 Hz. In order to provide a much finer shear point, it is preferred to reduce the excursion very substantial and to increase the frequency of closure very substantially. The Storz scissor would appear to be adequate to cutting corneal tissue which have a much higher mass and thickness and a lower resonance frequency than intraocular tissues which have a :
.

WO93/05718 PCT/US92/07g47 2I1209.~
g higher resonance frequency due to their much lower mass and thickr s.
Every micro~urgical scissor currently available for ocular surgery has more or less of the following disadvantages dependent on its individual design: (l) forwàrd thrust during closure pushes the target tissue out of the scissors because of forward motion of the cutting point; (2) crush artifact deforms the tissue during shear; (3) irregular ~S" shaped cross-sectional cuts occur, the severity of which is determined by ; individual ocular tissue characteristics; (4) loss of mechanical advantage during closure causes loss of shear, creating tissue incarceratio~ at the tips, and resultant lateral crush artifact; and (5) increased lateral lS resistance during closure prevents re-direction of the scissors~ along a curved line without creating crush and - distortion artifact into the cut.

8t~t~ment of the Invontion The present invention provides a scissor tip design and actuation which alleviates all of the above -~ disadvantages thereby resulting in a much more controlled, efficient and uniform shearing action to the tissue.
The present invention has vertical scissor blades in the sense that the movable blade reciprocates in the needle shaft and the movable blade edge projects at substantially a right angle to the blade portion connecting to the driver. Rather than having a guillotine, parallel line cut simultaneously across the entire blades as in the MPC scissors, the blades are curved to diverge from each other so that a wide open space is defined between the free ends of the scissor blades prior to its complete closure, which further serves to funnel tissue to the cutting point.
The present invention is directed to providing an improved cut from an intraocular instrument such as a WO g3/05718 PCI/US92/07g47 21120 9~ -lO-~cissors and, as illustrated in FIGS. 27, 27A, 27B and 28, hereinafter, provides a cut with no significant steps or shoulders between succes~ive cuts as shown in the illustrations made with the prior art scissors. Also, there is no need to physically hold the tissue to overcome forward thrust. For reasons to be explained, one would like to cut at a frequency higher than the natural resonant frequency of the tissue. Operating above tissue-resonant frequencies utilizes tissue inertia in which it will shear or cut before it will resonate or move forward. The material frequency of tissue is defined by the formula:

15f = ~ K(st fness) ~: .
- From the formula, it is ~een that the stiffer the tissue and the lower the ~a~, the higher will be the tissue resonance (f). Ocular ti~SUQs have very low mass and variable but ueually ~oderate stiffness and thus a relatively high resonant frequency.
The present invention provides a vibrating mode of operation in which the movable scissor blade are moved one against the other at a high frequency, e.g., 200-800 cycles per second, and through a low excursion, e.g., 1-10 mils, to allow operation in excess of the natural resonance of living tissue. This rapid vibration serves to create tremendous shear forces where the blades contact.
When the vibration actuation to the blade closure is accompanied by a forward, manual push of the scissors into the tissue, the greatly increased shear forces cut the tissue as the surgeon glides the scissors through it. The funneling action of the partially-opened scissor tips cause the tissue to be evenly directed to WO g3/05718 PCr/USg2/07947 211209~

the rapidly vibrating cutting point, causing the tissue to be cut without "stepsn.
The vibratory cut is made with the scissor blades partially open, e.g., if the entire movable blade excursion is about 0.060 inch between the open and closed positions, the blades may be open only 0.020 inch"and a vibratory excursion of the movable blade will reduce the opening to -0.017 inch and then returning the opening to 0.020 inch dimension.
Since the excursion of the blades is minimal, e.g., the range of 3 mil, the forward movement of the cutting point is also quite minimal, the amount of which is determined by the angle and geometry of the scissor blades. On average the cutting point moves forward and backward with each rapid excursion only 1 to s mil, as shown in FIG. 34. Since the forwàrd movement of the cutting point is clinicalIy negligible, forward thrust of tissue is;negligible. Since the scissors are operating with the tips more open, the amount'of tissue within the cutting surfaces is minimal, further decreasing tissue resistance and further reducing forward thrust. This shear action without forward thrust in non-parallel -~ soissors is not heretofore available in intraocular scissors.
Since shear is created continuously with the ~; vibration action near the pivot point of the blad'es, the mechanical advantage of the system is at a physical maximum. With increased mechanical advantage, less force is required to sect the tissue during the cut. This maximization of mechanical advantage does not exist in ~'~ prior art intraocular scissors. Preferably, the scissors handle body is round and tubular and is held between the ~ forefinger and thumb so that the direction of cut may be -~ easily made b~ the surgeon spinning the tubular handle body to re-d -ct the cutting edges.
Since the present invention scissor is capable J, .
-'~ ' of creating continuous shear with the scissor blades ,' , ~

WOg3/057t8 PCT/US92/07947 2112095 ~

relatively wide open, the cutting point acts as a true functional static point rather than a moving or kinetic point. Less scissor blade is buried within the tissue`
and lateral resistance is minimized, allowing the scissors to be steered and continuously re-directed within the tissue if necessary. This ability to re-direct scissors without lateral distortion artifact does not exist in prior art intraocular scissors.
The excursion of 3 mils occurring 500 times per second creates adequate and uniform shear, allowing the surgeon to push the "relatively non-moving" cutting point against the tissue, separating and cutting the tissue without the large steps, wit~out large crush artifact and without large "S" shape cross-section cuts in the wall, as in FIGS. 27 and 28, as was noted in the prior art intraocular scissors seen in FIGS. 2I through 26. The lack of the "S" cross-section despite the softness of the tissue is due to the fact that the preferential wedge path and the movement guidance paths are relatively uniform due to the extremely small excursion, and minimal twist to the blades.
~:
Importantly, the frequency of vibration of the ^ blades is higher than the natural tissue resonance, and thus inertial forces keep the tissue from twisting as the shear continues through its thickness, as diagrammed in FIGS. 35a and 35b and as was noted clinically, comparing FIG. 21 to 26.
The present invention also provides a cutting mode having both the oscillatory and the vibratory cutting action. As explained above, if the movable blade oscillates between its open and closed position several times a second, e.g., four to five times to complete a full excursion of 0.060 inch, the blade may also be vibrated to move through the small vibratory excursions of .001 to .003 at a frequency of 200-800 cycles per second. This is a combined or multi-operation of both oscillatory and vibrational movement simultaneously of W093/0s718 PCT/US92/07947 211209~

the cutting edges. A cutting action not heretofore available in intraocular ~cissors.
These surgical intraocular instruments are small and lightweight and must operate in a surgical environment and preferably should be ~team autoclavable.
To obtain the frequency desired, it was found necessary to develop an electromagnet drive or linear actuator operating at a frequency exceeding substantially the usual 60 Hz. In addition to being able to provide a low frequency drive for the oscillatory mode in the range of 1-5 cps, it was also desired that vibration drive at this high frequency, preferably at about 500 Hz, and a low excursion of about 1 to 10 mil. be superimposed on the larger excursion of e.g., 0.060 inch at the low frequency to vibrate the solenoid at a high frequency. This has been accomplished by the use of a D.C. signal to drive the solenoid in the oscillatory low frequency mode and to superimpose thereon an A.C. signal of high frequency.
The A.C. sign~l was formed into a square wave to achieve the vibration reciprocatory movement desired. A small mass is needed for the solenoid and the movable cutting blade in order to achieve the acceleration, deceleration and reversal of movement. Also, it is desirable that the deceleration of the cutting blade and solenoid be made smooth, as with a shock absorbing action, and that the reversal of direction and acceleration in the opposition takes place without a jerky operation that would be felt by the surgeonu A further consideration is to have the movable blade at its open position at the end of a cutting operation so that the surgeon's next movement of the scissors is not accompanied by the tissue tearing where it is caught between closed scissor blades.
Another consideration, for a commercially desirable intraocular instrument such as a scissors using a reciprocating solenoid, is that the reciprocation does not induce a positive pressure that would blow air into the eye; and, on the other hand, does not produce a W093/oS7t8 PCT/US92/n7s47 211209~ -14-vacuum that would suck tissue into the hollow needle in the space between the blade and the surrounding annular wall of the needle.
The driver of the intraocular instrument may be provided with a hollow shaft through the solenoid and provided with an attached infusion tube to inject liquid into the eye. The preferred driver has a connection or coupling that it allows it to be used with a number of surgical tools, e.g., disposable intraocular scissors, an intraocular forceps, vitreous cutter, cataract tissue cutter, intraocular trephine, or reciprocating knife or shear. Also, the preferred driver has its solenoid structure sealed to moisture so that it can be steam autoclaved and reused with any of these other intraocular instruments.
Accordingly, a general object of the invention ~ - is to provide a new and improved intraocular, -~ microsurgical instrument of the foregoing kind usable with one or more intraocular tools.
A further object of the invention is to provide a vibratory intraocular scissors.
A still further object of the invention is to - provide an intraocular scissors that oscillates between open and closed positions at a low frequency and that also has a small vibratory motion at a substantially higher frequency.

Brief De~cription of the Drawinas FIG. 1 is an exploded sectional view of an intraocular surgical scissors embodying the invention;
FIG. 2 is a side elevational view of a bushing which provides the support for the scissor blades as shown in FIG. l;
FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;
FIG. 4 is a sectional view taken on line 4-4 of FIG. ~;

W O 93/05718 2 1 1 2 o 9 ~ PC~r/US92/07947 ` ~. .

FIG. 5 is an enlarged fragmentary side elevational view of the stationary cutting blade used in the scissors of FIG. 1;
FIG. 6 is a sectional view taken on line 6-6 of FIG. 5;
FIG. 7 is an enlarged fragmentary side elevational view of a portion of the movable blade member of the scissors of FIG. l;
FIG. 8 is a sectional view taken on line 8-8 of lo FIG. 7;
FIG. 9 is an enlarged perspective view of a portion of the tube or needle which supports the blade members in the scissors of FIG. l;
FIG. 10 is a perspective view of the sleeve which supports and drives the movable blade member of the scissors of FIG. l;
~FIGS. lla, llb and llc are schematic showings :~of the blade portions of the scicsors of FIG. 1 showing the blades in their closed, partially opened and fully opened positions, respectively;
FIG. 12 is a showing of the control means for the scissors embodying the invention;
FIG. 13 is a schematic circuit diagram of the motor control circuit for the scissors embodying the invention;
FIG. 14 is a diagram of the voltage wave form applied to thei motor under various modes of operation;
FIG. 15 is a sectional view of a portion of the handpiece of the scissors of FIG. 1 with the motor removed;
FIG. 16 is a sectional view of the motor of the scissors of FIG. l;
FIG. 17 is a sactional view taken on line 17-17 of FIG. 15;
35FIG. 18 is a sectional view taken on line 18-18 of FIG. 17;

W093/Os7t8 PCT/USg2/07947 211~09~ -16- ;

FIG. 19 is a cross-sectional view of the surgical scissors of FIG. ~ ~howing the cutting blades in the full open position;
FIG. 20 is a cross-sectîonal view identical to FIG. 19 but æhowing the cutting blades in the closed position;
FIGS. 21 to 26 are photomicrographs of tissue from the corneas of chickens showing the results of sectioning this tissue with prior art intraocular scissors; and FIGS. 27 and 28 are photomicrographs of such chicken cornea tissue showing the results of sectioning this tissue with the scissors of the present invention;
FIG. 29 is a schematic diagram of the scissor blades in various positions;
FIGS. 30, 31 and 32 are diagrams of the forces acting on scissor blades;
FIG. 33 is a sketch of scissors cut on various types of tissue;
FIG. 34 is a pair of diagrams illustrating the change in cutting point position under a vibrating mode;
and FIGS. 35a and 35b are sketches of a prior art tissue cut and a cut by the scissors of the present invention.

Details~ D~soriptio~ Or the P _f0rr~d Embodime~t Referring to FIGS. 1, 19 and 20 of the drawings, there is shown an intraocular surgical scissors embodying ~he invention and designated generally by reference numeral 20. The scissors 20 includes a handpiece 22 and a detachable assembly 24 with a motor means 26 provided to power the scissors 20.
Considering first the detachable assembly 24, it includes a stationary blade member 28, and a movable blade member 30. To support the blade members 28 and 30, there is provided a bushing 32 which is generally 211209~

cylindrical in shape, having a central bore 32a within which a tube 34 is supported. The tube 34 serves to support and encloae the blade members 28 and 30 and is formed of 20 gauge stainless steel needle. The stationary blade member 28 is welded at its inner end to the inner end of the tube 34 to fix member 28 against relative movement within the tube 34. The tube or needle 34 is fixedly secured to the bushing 32 by soldering the inner end of tube 34 to the bushing 32. As shown in the upper portion of FIG. 1, the bushing 32, the tube 34 and the stationary blade member 28 are fixedly secured together. To facilitate removal of the assembly 24 from the handpiece 22, the outer surface of the bushing 32 is formed with annular grooves 32b which facilitate grasping the assembly 24 to withdraw it from engagement with the handpiece 22.
- As shown in FIGS. 1 and 5, the stationary blade member 28 includes an elongated portion 28a which is received within the tube 34 and also includes a laterally extending blade 28b. The blade 28b is provided with a cutting edge 28c which extends along the edge of the blade 28b which is facing toward the elongated portion 28a. The cutting edge 28c is formed by the intersection of flat sidewall 28d of the stationary blade member 28 and a beveled edge 28e, the planes intersecting at an angle of about 45-. As shown in FIG. 5 and in the schematic views of FIGS. lla, llb and llc, the cutting edge 28c is slightly concave in configuration and extends at an angle of about 60- to the lengthwise axis of the - 30 tube-34. It is also noted that the stationary blade member 28 terminates at a pointed end 28f, and the outer surface of the blade 28b is formed with a gently curved surface which connects to the lengthwise extending back edge of the blade 28b.
The movable blade member 30, which is also a part of the detachable assembly 24, is supported for reciprocation within the tube 34 by a sleeve 38 which is W093/0s718 PCT/US92/07947 2112Ug.~ ' secured to the blade member 30 by soldering the inner end of the blade member 30 to the ~leeve 38. The sleeve 38 includes a bore 38a within which the end of the blade member 30 i8 received and soldered to the sleeve 38. In addition, the sleeve 38 is formed with a cutout area 38b which provides cle~rance for the sleeve 38 to reciprocate with respect to the bushing 32 and a limit pin 41 which is press fitted into aligned openings 42 in the bushing 32, as shown in FIGS. 2 and 4. The pin 41 in the bushing 32 engages the opposite ends of the cutout 38b, thus limiting the distance through which the sleeve 38 may reciprocate with respect to the bushing 32.
The movable blade member 30 includes an elongated portion 30a and a transversely or laterally extending blade 30b. The end of the movable blade member 30 remote from the end to which the sleeve 38 is attached ~ includes the bla~e 30b, which is best shown in FIG. 7 and 2~ the schematic views of FIGS. lla, ~lb and llc. The blade 30b;has a autting edge 30d formed on the outer edge of the blade 30b rather than on the inner edge as is the oase with the cutting edge on the stationary blade 28b.
Thè cutting edge 30d has a convex curvature, while the cutting edge is at substantially right angles to the axis of the` elongated portion of the blade members. As shown ~ Z5 in FIG. 8, the cutting edge 30d is defined by the side -~ surface 30e and the beveled surface 30f of the blade 30b.
The surfaces 30e and 30f define an angle of about 30 which terminates at the cutting edge 3Od. The cutting edge 3Od terminates at the outer end of the blade 3Ob at a pointed tip 30g. The blades 28b and 30b are shown in - ~their fully closed position in FIG. lla. In FIG. llb, the blades are shown in their open position at which the ~; shearing engagement between the cutting edges 28c and 30d commence. In FIG. llc, the blades are shown in their fully open position in which the cutting edges are widely ~ spaced from each other. In the closed position with the -~ ~ cutting edges completely covered by the adjacent blade, ,. ~
, ,~,; ' .

W093/05718 PCT/US92~07947 211209.~
--19-- .
the assembly may be moved into position with a minimum of damage or cutting of adjacent tissues. In the starting-to-cut position of FIG. llb, there is a very small angle at which the cutting edges 28c and 30d intersect or extend across each other, thereby reducing the tendency of the scissors to displace tissue which is to be cut.
The curvature of the movable blade 3Ob has a tendency to hold the tissues while cutting rather than displacing them from between the two blades. The configuration of the cutting edges 28c and 30d is very important in the various modes in which the scissors 20 may be operated, as will be explained in greater detail below. The diverging nature of the cutting edges as positioned in FIG. llb is useful in gathering in tissues to be cut as -the blades move forward. At the same time, the very acute angle at the point where the cutting edges 28c and 3Od intersect or cross is important in providing a cutting action in which there is little outward thrust against the tissue being cut as the blades move together.
The handpiece 22, as shown in FIGS. l, l9 and 20, is adapted to receive, support and drive the detachable assembly 24. The handpiece 22 comprises a housing 48 which provides an enclosure for the motor 26.
The motor 26 is a linear voltage-to-displacement transducer and is also known as a linear solenoid, linear motor or linear actuator. It is of low ma~s and low reluctance so that it may perform the functions of driving the blade 30 in its various modes of operation to be described below. Through the use of rare earth magnets of low mass, the motor may be operated to oscillate and vibrate the scissors 20 at frequencies from 1 to lOOO Hz. The low mass of the armature of the motor 26 is necessary to permit movement at these velocities.
The linear motor 26 includes an axially displaceable shaft 26a which is mounted for sliding movement in bearings in end plates 26b. Affixed to the shaft 26a are a plurality of magnets 26c which are W093/0s7t8 PCT/US92/07947 separated by spacers 26d. The magnets 26 are preferably made of rare earth magnetic materials that will retain their magnetic strength even after being subjected to high temperatures common in steam autoclave sterilization. One such magnetic material used in a constructed embodiment of the invention is Neodymium Iron Boron (NdFeB). This material may be magnetized to provide a strong magnetic field for a given weight and has the capacity to retain its magnetization over time and when heated to high temperatures during steam autoclaving for sterilization.
The linear motor 26 described herein is very small in that it fits in the surgeon's hand in the manner of other conventional scissors while in the scissor's handle. Yet, the linear motor is capable of oscillating and vibrating at very high frequencies, e.g., 200 to 1,000 cycles per second, and with sufficient power to sever corneal or intraocular tissue.
The magnets are polarized with axially spaced poles arranged with their respective fluxes in opposition. Thus, the adjacent faces of the magnets 26c, separated only by a spacer 26d, are of the same polarity and the outermost poles on the end magnets 26c are of the same polarity. The magnets 26c are secured against axial movement on the shaft 26a by resilient C-rings 49 received in annular grooves in the shaft 26a. Provided at the outermost pole faces and retained in position by the C-rings 49 are spacers 26k which provide high permeability flux paths as do the spacers 26d. The spacers 26d and 26k are preferably made of Hi-Mu80 material which is a commercially available high permeability material.
Surrounding the movable armature including the shaft 26a and the magnets 26c, is a coil bobbin 26e which 3S supports a number of spaced coils 26f. The number of spaced coils exceeds the number of magnets by one more coil than magnets. The coils 26f are displaced axially W093/057t8 . PCT/US92/079~7 21I209~

with respect to the magnets 26c so that each coil is aligned with one of the spacers 26d and 26k whereby the magnetic flux extending radially from each spacer intersects one of the coils. Surrounding and supporting the coils 26f is a casing 26g which is also made of a high permeability material such as Hi-Mu80. The end plates 26b and the coil bobbin 26e are retained within the casing 26g by E-rings 26h which are received within annular grooves in the ends of casing 26g to restrain the parts form axial displacement.
The coils 26f are connected in circuit so that each adjacent coil carries current in the opposite direction from the current in the adjacent coils. Thus, as viewed along the axis of the coils, the current would be clockwise in one coil and counter-clockwise in the immediately adjacent coils~. The magnetic flux path provided by the ~pacers 26d and 26k along with the casing 26g reæults in the flux from each magnet passing through one coil going outwardly and through an adjacent coil coming inwardly. As a consequence, the forces produced by the currents through the coils 26f are all additive ; and displace the armature in proportion to the magnitude of the current flow.
In order to support the motor 26 within the housing 48, there are pro~ided annular shouldered rings 26j as are best shown in FIG. l. The housing 48 is formed by a cylindrical member 52. As best shown in FIG. 15, the cylindrical member 52 has an open end 52a through which the motor 26 is assembled, and which open end is closed by a cap 54 which has an opening through which a power cord 56 extends for connection with the coils 26f of the motor 26. An 0-ring seal 55 is positioned between the cap 54 and the cylindrical member 52 to seal the motor enclosure against the entrance of moisture. The cord entrance through the cap 54 may be sealéd with silicone, RTV or epoxy in a conventional manner.-~ O ....... e ~

WO93/05718 PCT/US92/07g47 The forward end of the cylindrical member 52 isformed with an annular wall that defines an opening 52b through which one end of the motor shaft 26a extends forwardly. In order to ~eal the motor shaft with respect to the housing opening 52b, there is provided a flexible boot 58 which has an outer flange 58b, which is clamped between the cylindrical member 52 and the annular support ring 26j. The sealing boot 58 is in sealed engagement with a coupling member 60 at its inner diameter, as shown in FIG. 16. The boot 58 permits the shaft 26a to reciprocate axially while sealing the opening 52b against the entrance of moisture into the motor enclosure. The coupling member 60 is formed with an inner bore 60a which is adapted to receive and drivingly connect the sleeve 38 to the armature shaft 26a. Within the coupling 60 there are 0-ring seals and a resilient C-ring 60b which is adapted to snap into engagement with a corresponding annular recess 38c formed in the sleeve 38. Thus, when the assembly 24 is inserted axially into the handpiece 22, the sleeve 38 enters the coupling 60 as shown in FIG.
16, and the C-ring 60b snapæ into engagement with the annular groove 38c in the sleeve 38 to provide a detent action in retaining the movable blade member 30 coupled to the armature shaft 26a. As the motor is actuated by an alternating current, the armature shaft 26a reciprocates axially, thereby driving the movable blade member 30 through the slee~e 38. During this motion of the armature a pair of springs or Belleville washers 62 mounted on the armature shaft 26a are alternatively compressed against the end plates 26b as the armature shaft 26a moves forward and backwardly in its mounting bearings. The springs 62 tend to reduce the shock or bouncing that would otherwise occur at the extremity of travel of the armature and also provide a centered rest -~35 position of the armature when the motor is not energized.
In order to mount the assembly 24 on the ~handpiece 22, there is provided a latch mechanism 64 ,,~

WOg3/057t8 - PCT/US92/07947 211209~
? 23 which is supported on a cylindrical wall 52c which extends from cylindrical member 52. An outer ~pring '~ enclosure 66 and an inner support 68 are each secured to the outer diameter and inner diameter respectively of the cylîndrical member or wall 52c. The inner support 68 receives for axial sliding movement a bearing support 69 to which is secured a bearing 70 for slidably supporting the coupling member 60, as is evident from FIG. 1.
Affixed to the bearing support 69 is a tubular member 72 - lo which has an internal bore 72a adapted to slidably receive the bushing 32 to mount the assembly 24 with respect to the handpiece 22. The bushing 32 is formed with a reduced diameter portion 32e which is receiv~d within the bore 72a.
In order to retain the bushing 32 within the bo,re 72a, there are provided a group of three detent balls 74, which are received within openings 72b formed '~ in the tubular member 72. The openings 72b are tapered so that the balls 74 may project into bore 72a but may not move inwardly beyond the position shown in FIGS. 17 and 18. A camming member 76 is mounted on the exterior of the tubular member 72, to retain the detent balls 74 within the tapered openings 72b. The camming ring 76 is biased to a forwardmost position by a helical spring 78.
With the application of pressure on the camming ring 76, it may be displaced axially, compressing the spring 78 to move the ring 76 to a point where relief openings 80, as best shown in FIG. 18, permit the balls 74 to move outwardly, thereby releasing the engagement with a annular'groove 32f formed in the bushing 32. In ord~r to assemble or disassemble the assembly 24 from the handpiece 22, it is necessary to move the camming ring 76 inwardly or to the right as shown in FIG. 1 to thereby permit the balls 74 to move outwardly and accept the end of the bushing 32.
The tubular member 72 is attached at its inner end to the bearing support 69 which is secured to a W O 93/05718 . PC~r/US92/07947 211209~ `"

flanged member 82 having its peripheral inner end in engagement with a coil spring 84 received within the cylindrical spring enclosure 66 for a purpose to be explained more completely below. The bearing 8upport 6g secured to the tubular member 72 is supported for axial sliding movement by inner support 68 and thereby permits the tubular member 72 to be displaced axially. As a consequence of the sliding bearing engagement between the support 69 and the member 68, when an inward force is applied to the tubular member 72, through the bushing 32, the assembly, including the tubular member 72, the flanged member 82 and the support 69 may be moved axially inwardly or to the right as viewed in FIG. 1. This movement in effect causes the stationary blade member 28 to be moved with respect to the movable blade member 30, which, of courser is attached to the armature shaft 26a.
It is important for saf~ty reasons to provide means for causing the blades 28b and 30b to be positioned in overlapping relationship in the event of a power failure to the handpiece 22. If, during a surgical procedure the power were to be interrupted, the springs 62 would locate the movable blade member 30 in a center position with the cutting blades 28b and 30b spaced apart as in FIG. llb, making it difficult for the surgeon to remove the scissors 20 from the eye of a patient.
Accordingly, it is necessary that means be provided to move the blades to the overlapping position as shown in FIG. lla. The latch mechanism 64 permits the operator to grasp the bushing 32 or the forward portion of the `30 tubular member 72 to press the assembly 24 inwardly, thereby moving the stationary blade 28b in line with the movable blade 30b, which would otherwise be in a central position.
As discussed above, it is contemplated that the handpiece 22 may be used with a variety of other surgical tools that require a solenoid or oscillatory drive of this type. Such instruments would include in addition to W093/0571~ PCT/US92/07947 ~
211209~

intraocular scissors, vitrectomy instruments, intraocular forceps, intraocular trephine, reciprocating or vibrating -knife or shear. It may be desirable and is contemplated that liquids might be in~ected into, or tissue withdrawn -from, the eye through a passageway extending axially of the shaft 26a.
In order to prevent the unwanted withdrawal of liquid or tissue through the tube 34 or the possible pumping of air into the eye, it is necessary to provide vent passageway 86 extending through the cylindrical wall 52c and the inner support 68. The oscillation of the -shaft 26a and accompanying flexure of the boot 58 tends ;`
to create presæure or vacuum surges within the handpiece 22, which surges are transmitted through tube 34 to the --15 interior of the eye being operated upon. The passageways -86 vent the area adjacent the boot 58 to the outside atmosphere and prevent any such surges.
Turning now to the vàrious modes in~which the scissors 22 may be operated, attention is directed to the control as shown in FIG. 12 and the circuit diagram of FIG. 13. As shown in FIG. 12, there is provided a control means designated generally by reference numeral - 90. The control means 90 includes a mode selection means 92 whic~ permits the operator to select between four different modes of operation~ Th first mode is a so-called "linear mode" in which a current is applied to the field coils 26f of the motor 26, to achieve a desired displacement of the armature shaft 26a and thereby, a specific displacement of the movable blade member 30 with respect to the fixed blade member 28. This total displacement or excursion of the movable blade is on the order of 50 to 70 mils (0.050 to 0.070 inch). The control of the blade position in the linear setting is accomplished by a foot pedal 93 which operates a 35 potentiometer 94, to deliver a selected D.C. voltage to ~
~- the motor 26. As shown in the circuit diagram of FIG. `-13,~in the linear mode setting for the mode selection ~,.

W093/0~718 PCT/US92/07947 ~

.....
~ os~ -26-means 92, a first switch 96 is closed to deliver a '~
voltage amplified by amplifier 98 through a summing amplifier 100, through a switch 102, amplifier 104, to o the motor 26. The switch 102 is associated with the foot pedal control 93 and is a double pole switch for foot pedal 93 which is shown in FIG. 13 in its off position. - ~;
- Switch 102 is closed upon the initial operation of the foot pedal to connect the D.C. signal from potentiometer ''' 94 in the case of the linear operation, to the motor 26.
As discussed earlier, the linear mode permits '-`' the operator to open and close the blades 28b and 30b to -`
make individual cuts as the foot pedal 93 is depressed.
This mode also permits the operator to select a desired spacing of the blades for any desired procedure.
In the second position of the mode selection means 92, designated as "linear oscillatory", the position of the movable blade is again controlled in a iinear fashion by the position of the food pedal which ~"`
adjusts the potentiometer 94. In the linear oscillatory 20 mode, the switch 96 is still closed, but the control also -'~-connects in circuit an oscillator 105 by closing a switch ~-~
` 106, thereby connecting the oscillator 105 as well as the potentiometer 94 to the summing amplifier 100. The summing amplifier 100 combines the D.C. signal and high-frequency oscillation signal and delivers it through theswitch 102 and the power amplifier 104 to the motor 26.
In this mode, with this circuit arrangement, the scissors 20 may be operated in a particularly advantageous mode for many types of surgical procedures. The movable blade 30a may be positioned ~y the foot'pedal operation of the potentiometer 94 to any desired degree of separation from the stationary blade 28b. At the same time, the high- ' frequency oscillator 105 causes the armature of the motor :~
26 to vibrate at a rate of 500 Hz through a relatively 35 small displacement. This small displacement vibration, ~`
which may be from .001 to .003 inches, produces an effect ~-~ on cutting of certain types of tissue which allows the ~-`

WO g3/05718 ' PCr/US92/O7g47 . ' -21120g.~ '' blade to move easily through the tissue, cutting with a minimum amount of distortion or displacement of the tissue.
As discussed above, the high frequency 5 vibratory motion in combination with the partially opened ~'~
blades provides significant advantages in having the vibratory motion to cut tissues while maintaining an optimum position of the cutting point or intersection of the cutting edges. Under this condition, there is a 10 small outward thrust against the tissue which is gathered `~
and fed into the cutting point by the diverging cutting edges. The operator may move the blades forwardly with the blades spaced as in FIG. llb, to cut tissue along a flat plane with little or no tissue deformation and may ;
easily change the direction of cutting, since the tips of the blades are not buried in the tîssue being cut.
The third setting provided on the mode selection~means 92 is for a multiple cut. In the multiple cut setting of the control means 92, an oscillator 108 is connected through a switch 110 to the amplifier 100, as shown in FIG. 13. The oscillator 108 includes control means 112, so that the output frequency of the oæcillator 108 may be varied between 1 and 4 Hz, or between 60 an~ 240 oscillations per minute. The control means 112 for the oscillator 108 may be adjusted by a control knob 114 on the control 90, as shown in FIG.
12. In the multiple-cut mode, the movable blade 3Ob ~ ;
reciprocates at a selected frequency with respect to the stationary blade 28. As discussed above, the contour of the cutting edgès 30d and 28c of the movable and stationary blades provides improved cutting of delicate tissue in any of the modes of operation described. The diverging angle of the cutting edges allows the tissue to be gathered in as the instrument moves forward, and the 35 acute angle of engagement of the two cùtting edges ;
reduces the outward thrust on the tissue being cut.
.
, ~ O
:' ~ `

W093/Os718 PCT/~S92/07g47 2 1 1 2 0 9 ~ -28-The fourth possible mode of operation for the scissors 20 is the multiple-oscillatory mode, and is indicated as the most cloc~wise setting for the mode selection means 92. At the multiple-oscillatory setting, S the two switches 106 and 110 are both closed, connecting the oscillators 105 and 108 to the summing amplifier 100, through the switch 102 and the power amplifier 104 to the motor 26. In this particular mode of operation, the two oscillator signals are combined together to open and ;
close the scissors periodically at a frequency of from 1 to 4 Hz, and at the same time cause the moving blade to oscillate or vibrate at a high frequency. To best appreciate the nature of the signal applied to the motor 26, attention is directed to FIG. 14 which is a diagram -of the voltage or current signal applied to the motor 26.
The first two square waves represent the output of the oscillator 108 as amplified and fed to the motor 26, as ~would exist in the normal multiple-cut setting of the control means 92. ~ith the control means set for the 20 multiple-oscillatory mode, the oscillator 105 would be -providing a signal superimposed on the signal from the oscillator 108. Thus, the square wave from oscillator 108 might be at a 2 Hz frequency, whereas the oscillator 105 would be producing a 500 Hz signal which would be superimposed on the signal from the oscillator 108. The result is that the movable blade continually vibrates as it is moved from one position to another. While FIG. 14 shows the applied signal, it should be appreciated that the inertia of the system results in the movable blade -not moving immediately between one position and the other, since this movement would be slowed by the necessity to accelerate the blade, the coupling, the armature shaft, etc. As a consequence, the results obtained from applying a signal of this nature is a constant vibration of the movable blade as it moves from the various positions in opening and closing. --~": `'' WO93/05718 PCT/US92/07947 ``~
2 1 1 2 0 9 ~

As indicated above, the switch 102 is closed at -the time the food pedal is operated to move the potentiometer to a desired position. When the foot pedal -is released, the sw~tch 102 is activated to the position shown in FIG. 13, causing a mono-stable multi-vibrator 116 to deliver a short negative pulse to the power amplifier 104 and the motor 26. The purpose of this negative pulse is to cause the movable blade to be displaced to an open position at the end of the surgical . , .
o io procedure and thereafter be returned to the closed position by the positive D.C. signal.
FIG. 21 is a photomicrograph of a chicken cornea lens cut with a conventional, manually-operated scisso~s of the horizontal angled kind. A re-direction or extra-cut and step 130 is shown in FIG. 21 along with compressea tissue 1~1 that was compressed during the ~iving a puckered cro~s-section at the tissue section 13~1. The steps 130 occurring a manual closure of manually-operable scissors of guillotine-type are also shown at 130 in FIG. 22. A manually-operated scissors ~also cuts steps 130 as the ~cisso~s is closed to make one cut, and then i8 opened and advanced to make the next cut -and step 130a. The steps 130a-130d are made when the scissors completes the cut. An "S" shape 134 is formed in the tissue by the horizontal, angled scissors. Thç
portion of the cut 135 is lower down from the plane at section 136, which is raised and is closer to the camera;
and it is this difference in vertical heights in FIG. 23 that gives the HS~ shape in cross-section. FIG. 21A
illustrates cuts made with a horizontal angled, manual closure scissors. ~he long shaft of the scissors creates relatively long "step" incisions. A line of crushing artifact is seen along the leading edge of each re-direction step 130. As the tissue is cut after this line of crush artifact, the tissue sectioning is reasonably uniform. A striking feature of the slow closure of the manual scisoors is that it allows the tissue to twist ~ ~ , WOg3/05718 PCT/US92/07947 211209S _30_ within the scissor blades creating the "S" shape to the cut edge.
The MPC conventional scissors, when operated at low speed, cuts in tissue as ~hown in FI~. 23A with the S irregular tissue sectioning or steps 130 being shown in s -~
the left-hand portion of FIG. 23A. When the frequ-ency of oscillation is increased, steps of shorter length are indicated by the scallops 138 in the right-hand portion of FIG. 23A. As the scissors is re-directed in the lo tissue, a gouge 139 may occur in the tissue. FIG. 23B
shows a higher power photomicrograph of a step 130 in FIG. 23A, and shows that approximately 25~ of the tissue thickness is crushed artifact 140. A horizontal scissor cut section is shown at 100 power in FIG. 24, and shows the steps 130. As shown in FIG. 24, the epithelium cut 142 has a different cross-section character than the character of the central stroma cut 143. -~
A 100 power microphotograph of a cut made by ~
the MPC scissors in FIG. 25 discloses a crushed artifact ~-145~because the scissor blades are guillotine and tend to crush the tissue. $he scallop edges 147 and 148 are shown at the top and bottom edges of the tissue, which is shown in FIG. 25. A further view of a cut section made with the NPC scissors shows a severely crushed artifact at 148 while a reasonably smooth section 149 is shown in the left hand of FIG. 26.
Cuts made with the present invention operating in a vibratory mode are shown in FIGS. 27, 27A, 27B and 28. As shown in FIG. 27, the tissue illustrated has three layers with a top layer 150 of corneal epithelium and a thick cornea stroma layer 151. Between the epithelium layer 150 and the stroma layer 151 is Bowman's layer 152. The cuts shown in FIG~ 27 and 27A are `
extremely uniform throughout the entire length of the -- 3S ~issue sectioning; no re-direction steps are noted, and the cut edge of the tissue is perpendicular to the plane , .

211209~

of the tissue itself, rather than being "S" shape, as described above.
FIG. 27B illustrates a high power view of cut made with a scissors of the present invention. Only a thin stripe of crush artifact 160 is demonstrated running directly down the center of the tissue section and represents less than 10% of the entire width of the tissue sectioning. This stripe represents the portion of the tissue that actually is fed into the shear point at which the scissor blades come in contact. To the right and left of the line of crush artifact is seen a very uniform tissue sections 161 and 162. These even sections -~
are produced by the knife action of each scissor blade, ;;~
the shear of which is maximized by the vibration effect. -The epithelium 150 of the tissue is poorly adherent to the body of~the cornea and is easily detached, as indicated at 163. Despite the fact that the epithelium can freely detach and slide free from the remainder of the tissue, it also is cut by the scissors in a uniform even fashion, and still perpendicular to the plane of the tissue. Thus, it will be seen that the present invention provides an improved tissue sectioning, as shown in the tissue sectioning of FIGS. 27, 27A, 27B and 28..
The specific embodiment disclosed includes a detachable assembly having relatively re~iprocable scissor blades. It is contemplated that the handpiece 22 would be used as a driver for a single blade instrument such as a knife or scalpel, or for a pair of surgical forceps. The handpiece 22 would drive the blade in the vibration mode to provide improved cutting action. In connection with the forceps, it i5 often necessary in ocuIar surgery to separate layers of tissue using forceps. It has been found that by vibrating the forceps, the task of separating such layers of tissue is facilitated considerably.
It is also contemplated that the scissors 20 and the handpiece 22 may be used for vitrectomy and '' WO93/0571X pcTlus92/o~s47 frag~entation. The handpiece is a suitable source of power for the well-known vitrectomy instruments having cylindrical cutters in a hollow needle with suction means for withdrawing the cut tissue. For fragmentation of cataracts, the handpiece 22 may be used to drive a cylindrical aspirating tube at a high frequency of soo to 800 Hz.
It is noted that the form of the ocular scissors may be varied within the scope of the present invention and those various scissors may be used with a handpiece in the various modes of operation discussed above. Thus, a scissors having blades oscillating in a ~-`
plane perpendicular to the axis of the tube or needle may 0 be mounted on a handpiece and driven in the four various vibrating and oscillating modes disclosed above.
W~ile the disclosed embodiment of the ocular scissors is intended primarily for retinal surgery at the ~-back of the eye, it is contemplated that the invention is suitable for corneal or lens surgery at the front of the `
eye. The only adaptation or difference between the instruments suitable for these different areas of surgery -relates to the amount of movement of the movable blade, . .,~
since the depths of cut required in corneal surgery is considerably greater than in retina surgery.

Claims

What Is Claimed Is:

1. An ocular scissor system for cutting tissue of eye comprising:
a handle body for gripping by the surgeon during the cutting operation;
a pair of blades extending from the body with at least one of the blades being movable relative to the other blade between a fully open position and a fully closed position;
a tubular needle extending from the handle body and having the movable blade movable therein; and a driver means in the handle body for operating at least one of said blades in an vibratory mode with a small, predetermined amplitude and a high, predetermined frequency, the driver driving the movable scissor blade simultaneously in an oscillating mode through an amplitude substantially greater than the small predetermined amplitude and at a lower frequency than the high predetermined frequency to open and close the scissors while the blades moving through the small amplitude vibrate the tissue to sever tissue in the vibratory mode as the movable blade oscillates.

2. An ocular scissor system in accordance with Claim 1 in which the driver is an electrical solenoid;
and a D.C. current drives the solenoid to oscillate the movable blade and an A.C. current is superimposed on the D.C. current to drive the solenoid to vibrate the movable blade.

3. An ocular scissor system in accordance with Claim 2 in which the oscillating frequency is in the range of 1 to 5 cycles per second, and in which the vibratory frequency is in excess of 200 cycles per second.

4. An ocular scissor system in accordance with Claim 2 including a manual operator to shift the blades to a closed position when the power fails to allow removal of the scissor blades from the eye in a closed position if the power should fail.

5. An ocular scissor system in accordance with Claim 4 in which one of the blades is normally a stationary blade; and in which the manual operator shifts the normal stationary blade to a closed position next to the normally movable blade.

6. An ocular scissor system in accordance with Claim l including a foot pedal to shift the scissor blades to a partially open position and to the open and closed positions.

7. An ocular scissor system in accordance with Claim 5 including a control means which controls the driver f or operating in a vibratory mode only, an oscillatory mode only, a multiple mode having both the linear and oscillating modes simultaneously, and a linear mode in which an operation of the foot pedal causes a single closing and opening movement of the movable blade.

8. An ocular scissor system in accordance with Claim 1 in which the pair of blades and the tubular needle are detachably mounted to the handle body and the tubular needle, and a coupling means is affixed to the tubular needle and blades to releasably couple them to the handle body.

9. An ocular scissor system in accordance with Claim 1 in which the movable blade reciprocates in a first direction and has a cutting edge extending laterally relative to the first direction, the other blade extending parallel to the movable blade and having a cutting edge extending laterally to the first direction, the cutting edges of the movable and fixed blades defining an opening therebetween converging to a contact point, the converging cutting edges funnelling tissue to the vibratory contact point.

10. An ocular scissor system in accordance with Claim 1 including a detachable assembly carrying the blades for detachment from the handle body for steam autoclaving, the driver including a linear electric motor in the handle body, and seals in the handle body for sealing the electric linear motor against intrusion of steam when the handle body is steam autoclaved.

11. An ocular scissor system in accordance with Claim 10 in which the seals include a flexible boot secured at one end to a stationary part of the handle body and secured at another end of the boot to a movable member of the linear motor connected to reciprocate the movable blade.

12. An ocular scissor system in accordance with Claim 1 in which the movable blade is rotatable in the tubular needle towards its closed position to provide an angled scissor cutting system.

13. An ocular scissor system in accordance with Claim 1 in which the handle body is tubular in shape and fits between the thumb and forefinger of a surgeon, the tubular body being rotatable between the surgeon's thumb and forefinger to change the direction of cutting.

14. An intraocular scissor system for cutting tissue of the eye comprising:
a handle body for gripping by the surgeon during the cutting operation;

a pair of blades extending from the body with at least one of the blades being movable relative to the other blade between a fully open position and a fully closed position;
a tubular, elongated needle extending from the handle body in a longitudinal direction and having the movable blade movable therein;
the pair of blades having cutting surfaces movable relative to each other in a direction parallel to the longitudinal direction of the needle to form a guillotine scissor cut; and a driver means in the handle body for operating the at least one movable blade in the longitudinal direction with a small amplitude substantially less than the distance between the fully open and closed positions, and at a frequency above the natural frequency of the tissue being cut, the blades adapted to be pushed through the tissue while being held at the opened position and with the blades moving through the small amplitude to vibrate the tissue and to sever tissue in a vibratory mode.

15. A microsurgical, intraocular instrument for eye surgery comprising:
a handle body for gripping with one hand by the surgeon during surgery;
a surgical tool projecting from the handle body and having a member adapted to be reciprocated at a frequency above the natural frequency of vibration of the tissue in the eye;
an adapter for detachably connecting each of a plurality of surgical tools to the handle body for reciprocal movement during the surgery, the adapter and surgical tools being steam autoclavable;
an electric linear motor in the handle body for reciprocating the surgical tool at a frequency in excess of 200 cycles per second; and means to seal the electric linear motor in the handle body to allow autoclaving of the handle body with the linear motor therein between attachments of different surgical tools.

16. A microsurgical, intraocular instrument in accordance with Claim 15 in which the surgical tool is a scissors.

17. A microsurgical, intraocular instrument in accordance with Claim 15 in which the surgical tool is a forceps.

18. A microsurgical, intraocular instrument in accordance with Claim 15 in which the surgical tool is a knife blade.

19. A microsurgical, intraocular instrument in accordance with Claim 15 in which the surgical tool is a trephine for coring holes.

20. A microsurgical, intraocular instrument in accordance with Claim 15 in which the surgical tool vibrates and cavitates cataract tissue in the eye.

21. A microsurgical, intraocular instrument in accordance with Claim 15 in which a suction tube is connected to the hollow body and through the surgical tool that vibrates and cavitates cataract tissue in the eye.

22. A microsurgical, intraocular scissor system for operating in an eye comprising:
a tubular handle body for gripping by the surgeon with one hand during surgery;
a fixed tubular needle projecting from the handle body for insertion through a slit into the eye;

a pair of blades extending from an end of the tubular needle with the blades being movable relative to one another between a closed position and an open position through a first large amplitude; and a driver motor in the tubular handle body for driving at least one of the blades between its open and closed positions and for driving the one blade through a series of vibratory cutting strokes each having an amplitude which is small fraction of the first large amplitude and at a frequency substantially above 200 cycles per second.

23. A microsurgical, intraocular scissor system in accordance with Claim 22 in which the driver motor is an electric linear motor operable at a frequency substantially faster than 2,000 cycles per second.

24. A microsurgical, intraocular scissor system in accordance with Claim 23 in which the linear motor is driven by a D.C. current to oscillate the scissors through the first large amplitude between the fully open and the fully closed positions, at a lower frequency, an A.C. current superimposed on the D.C.
current motor current to drive the movable scissor blade at the high frequency through the very small amplitude as the movable blade is moving toward or from the fixed blade.

25. A microsurgical, intraocular scissor system in accordance with Claim 22 including a vent hole in the tubular handle body to vent air to prevent air from being pushed by the driver through the tubular needle and into the eye.

26. A microsurgical, intraocular scissor system in accordance with Claim 22 which includes a manual operable means to shift the blades to a closed position for removal through a slit in the eye if the power should fail.

27. A microsurgical, intraocular scissor system in accordance with Claim 22 in which cutting edges on the blades define therebetween a converging shape from their outer edges to a point of contact therebetween to guide tissue to the point of contact, the movable blade being reciprocated in its direction of length with its cutting edge extending laterally from its direction of reciprocation.