WO1993005719A1

WO1993005719A1 - Microsurgical cutting device

Info

Publication number: WO1993005719A1
Application number: PCT/US1992/007954
Authority: WO
Inventors: Thomas Ying-Ching Lo; Franklin Tao; Tolentino Escorcio
Original assignee: Visionary Medical, Inc.
Priority date: 1991-09-23
Filing date: 1992-09-21
Publication date: 1993-04-01

Abstract

A microsurgical cutting device (20) for cutting tissue, such as ocular tissue is disclosed. The device includes a handle body (24), a linear actuator (26) carried within the body (24) for movement of an armature (28) between retracted and extended positions, typically through an excursion of between about 50-100 mils, and a circuit which can drive the actuator (26) in a proportional or slow oscillatory modes. The device is designed to engage a cutting tool assembly (80), preferably a disposable assembly, through a two-clamp structure (78, 79) which holds one part of the assembly (80) stationary and connects a cutting tool (88) in the assembly to the actuator's armature.

Description

MICROSURGICAL CUTTING DEVICE This application is a continuation-in-part of U.S. patent application Serial No. 764,518, filed on September 23, 19.91.^{" ■■ " ■} . ^'.^{' •};_. *

1. Field of the Invention

This invention relates to a surgical cutting device for cutting tissue, such as ocular tissue.

2. Backcrround of the Invention

Surgical cutting devices, such as for use in cutting ocular tissue, are widely employed in surgical procedures in which fine tissue cutting is to be achieved. Three types of driver (actuation) systems for scissor-type cutting devices in current use: Manually operated handles with squeeze-type or lever depression actuation, pneumatic piston linear drivers, and electrical motors of direct current or solenoid drive.

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 level extending from the handle (Southerland-Grieshaber) 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 driver, 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 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 released. 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 footpedal 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. Motor drivers of either rotary or linear solenoid style activate scissor closure by controlled transfer of the motor energy to the movable blade. One commercially available cutting -tool is an automated, solenoid-style microscissprs that has a 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.

The blade excursion is again 60 to 70 mils (0.060 to 0.070 inch) and travels at a rate of 1000 mm/sec from the open to the closed position. The moving blade cuts in about 5 milliseconds and remains shut for about 15 milliseconds before automatically returning to the open position. The device operates to produce a series of repetitive_^ cuts or oscillations at a rate of one to five strokes per second, with each stroke traveling at 1000 mm/sec.

Often with cutting tools of this type, the tissue is torn or inefficiently cut, due to tendency of the tissue to be pushed away from the cutting regions of the blades at relatively low scissor speeds.

Another general type of fine-tissue surgical cutting device uses an ultrasonic probe to cut or macerate tissue by vibration at ultrasonic frequencies, typically between about 30 and 80 kHz. However, not all tissues absorb ultrasound energy effectively and thus are efficiently macerated. In addition, ultrasonic probe is a very effective heat transfer device, and can cause thermal damage to the surrounding tissues. It is also generally difficult to control the area and degree of cutting and thus not widely used in microsurgeries except for cataract removal procedures.

It would thus be desirable to provide a surgical cutting tool which overcomes the limitations of these two general types of^' surgical cutting tools.

3. Summary of the Invention

The present invention includes a icrosurgical cutting device for cutting tissue, such as ocular tissue. The device includes a handle-like body for gripping by the surgeon during the cutting operation, a linear actuator carried in the handle body, and having an armature which is movable axially, under the influence of a voltage applied to the actuator, between a fully extended and a fully retracted position, and structure for clamping a microsurgical cutting tool to the actuator's armature, for movement therewith between such extended and retracted positions, typically between about 50-100 mils. A controller circuit in the device is designed to drive the armature in one of the following selectable modes:

(a) a proportional mode in which the position of the armature between its fully extended and fully retracted positions is controllable by a user-operate switch, by supplying a switch-controlled DC voltage to the actuator; and

(b) an oscillatory mode in which the armature can be moved between its fully extended and fully retracted positions at a frequency less than about 20 Hz, by supplying a oscillating-wave voltage to the actuator.

In one embodiment,, the circuit controller is effective, in either the proportional mode or oscillatory mode, to supply a high-frequency voltage signal, in the range-between about 50-1,000 Hz, to the actuator, to produce a superimposed vibrational component whose amplitude is substantially less, than that of total excursion distance of the armature between its fully retracted and fully extended positions. The cutting tool used in the device may be part of a tool assembly that includes an outer sleeve having an axial bore, an inner sleeve, a portion of which is mounted within the axial bore of the outer sleeve for limited axial movement with respect thereto, and a cutting tool having a proximal end secured to the inner sleeve and a distal cutting end. The clamping structure in the device includes a first clamping structure carried on the handle-like body for receiving the outer sleeve in clamping engagement therewith, and a second clamping structure carried on the armature for receiving the inner sleeve in clamping engagement therewith.

The first and second clamping structures may include annular clamps for releasably engaging the outer surfaces of the tool assembly's outer and inner sleeves, respectively.

In another aspect, the invention includes a -cool assembly for use with a cutting device of the ~ype described. The assembly includes an outer sleeve having an axial bore, an inner sleeve, a portion of which is mounte within the axial bore for limited axial movement with respect thereto, and a cutting tool having a proximal end secured to the inner sleeve and a distal cutting end. The outer and inner sleeves may have recessed portions adapted to receive first and second clamping structures in the cutting device releasably therewith, respectively.

In one embodiment, the tool assembly is designed for tissue cutting by a scissors action. The assembly further includes a tube attached to the outer sleeve, and a fixed- position blade mounted in the tube, where the cutting tool is movable within the tube, as the actuator is moved between its fully extended and fully retracted positions, to positions at which the cutting end of the cutting tool is open and closed with respect to the fixed-position blade. In another embodiment, the assembly is designed for- tissue removal. The assembly further includes a tube attached to the outer sleeve and defining an axially extending opening adjacent the tube's distal end, where the cutting end of the cutting tool is designed to move within the tube, adjacent this opening, and the assembly is adapted for use with a cutting device designed to exert a vacuum within the tube.

In still another embodiment, the assembly is designed for tissue fragmentation,^' and the cutting tool includes-a tube having a bladed^' end.

These and other objects and features of the invention will become more fully apparent when the following detailed description of the invention is read in conjunction with the accompanying drawings.

Brief Description of the Drawings Fig. 1 is a sectional view of an microsurgical cutting device constructed according to one embodiment of the invention; Fig. 2 is a sectional view of a portion of the handpiece of the device of Fig. l with its linear actuator removed;

Fig. 3 is a sectional view of the linear actuator of the device shown in Fig. l;

Fig. 4 is a sectional view showing one of the clamping structures in the Fig. 1 device;

Fig. 5 is a sectional view taken along line 5-5 in Fig. 4; Fig. 6 is an exploded view of a cutting tool assembly designed for use with the device of the invention;

Fig. 7 is an enlarged side view of the outer sleeve in the Fig. 6 assembly;

Fig. 8 is a sectional view taken on line 8-8 of Fig. 7;

Fig. 9 is an enlarged sectional view of the coupling structure by which the armature shaft in the cutting device is coupled to the cutting tool in the coupling assembly;

Figs. 10A, 10B, and IOC illustrate the relative positions of the cutting tool assembly blades in their fully open, partially open, and closed positions, respectively;

Figs. 11A and 11B show the positions of the armature in the cutting device at retracted and extended positions, respectively;

Fig. 12 is a schematic circuit diagram of a controller circuit in the device;

Figs. 13 shows the relationship between voltage level applied to the linear actuator, in a proportional mode, and position of relative positions of cutting blades seen in Figures 10A-10C;

Figure 14 show signals which can be supplied by the controller circuit in an oscillatory mode with a square- wave output (solid line left) , an oscillatory mode with a sine wave output (dotted line left) , and a square-wave output with a high-frequency vibrational component (solid line right) ;

Figure 15 is a side sectional view of a tool assembly sed with the cutting device of the invention for tissue removal; and ^•

Figure 16 is a side sectional view of a tool assembly used with the cutting device of the invention for tissue fragmentation.

Detailed Description of the Preferred Embodiment

Referring to .Figs_, 1-3 of the drawings, there is shown a microsurgical cutting device 20 constructed according to one embodiment of the invention. The device generally includes a handpiece 22 having a handle-type body 24, a linear actuator 26 housed within the body, and a controlling circuit (described below with respect to Fig. 12) , by which the linear actuator can be driven in one of a number of selectable modes. The cutting device is designed for use with a detachable tool assembly, to be described below.

The linear actuator or motor in the device is a linear voltage-to-displace ent transducer. It is of low mass and low reluctance so that it may perform the functions of driving a cutting tool 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 a cutting tool at oscillatory frequencies preferably between 1-20 Hz and vibrational frequencies preferably between 50- 1,000 Hz. The low mass of the armature of the actuator 26 is advantageous in achieving movement at these velocities.

Actuator 26 includes an armature 28 which is mounted for axial movement within the body. With reference particularly to Fig. 3, armature 28 includes a shaft 30 which is mounted for reciprocating axial movement in bearings 32, 34 mounted in end plates 36, 38, respectively, in the actuator. Also forming part of the armature is a plurality of magnets, such as magnets 40, 42, 44, which are separated by spacers, such as spacer 46 between adjacent pairs of magnets 40, 42. The magnets 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 ield for a given weight and has the capacity to retain its magnetization over time and when heated to high temperatures during steam autoclaving for sterilizatio . The magnets are polarized with axially spaced poles arranged with their respective fluxes in opposition. Thus, the confronting faces of the adjacent magnets, such as adjacent magnets 40, 42, have the same polarity (either N or S polarity) . Therefore the four magnets in the armature would have the pole orientation NS-SN-NS-SN, or SN-NS-SN- NS. The magnets in the assembly are secured against axial movement on shaft 30 by resilient C-rings, such as ring 48, received in annular grooves in the shaft.

Provided at the outermost pole faces and retained in position by the C-rings 48 are spacers, such as spacer 50, which provide high permeability flux paths, as do the internal spacers, such as spacer 46. The spacers in the armature are preferably made of Hi-Mu80 material which is a commercially available high permeability material. Disposed between C-ring 48 and end plate 36 at the forward side of armature in Fig. 3 is a pair of springs or Belleville washers 52, 54, which are carried or. the armature shaft. These washers act to bias the armature to a retracted "at rest" position shown in Figs. 1 and 3. The washers are compressed against the end plate as the armature shaft moves forwardly in its mounting bearings;. The washers tend to reduce the shock or bouncing that would therwise occur at the extremity of travel of the armature and also provide a rest position of the armature when the motor is not energized.

With continued reference to Fig. 3, surrounding the movable armature is a coil bobbin 56 which supports five spaced coils, such as coils 58, 60, 62. The coils are displaced axially with respect to the magnets, such that each coil is aligned with one of the spacers, such as coil 60 aligned with spacer 46 (The armature in Fig. 3 is in a fully retracted position, where the armature is shifted toward the right in the figure with respect to the coil bobbin. In an intermediate armature position, the coils. are symetrically aligned, in an axial direction, with the associated spacers in the armature) ,

Surrounding and supporting the coils is a casing 59, which is also made of a high permeability material such as Hi-Mu80. End plates 36, 38 and the coil bobbin are retained within the casing by E-rings, such as E-ring 64 (Fig. 1) , which are received within annual grooves in the ends of casing to restrain the parts form axial displacement.

The coils are connected in circuit so that adjacent coils carry current in opposite directions. 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 spacers, such as spacer 46, along with the casing results 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 are additive and displace the armature in proportion to the magnitude of the applied voltage; The actuator is held within housing or body 24 by annular shouldered rings, such as ring 66, as best seen in Fig. l. With reference to Fig. 2, body 24 is formed by a cylindrical member 68. This member has an open end 70 through which the actuator is assembled. This end is closed a cap 72 which has an opening ^"through which a power cord 74 extends for supplying current to the actuator coils. An O-ring seal 76 is positioned between cap 72 and member 68 to seal the motor enclosure against the entrance of moisture.

The forward end of member 68 is formed with an annular wall 71 that defines an opening 73 through which the forward end of the actuator shaft extends. In order to seal the motor shaft with respect to opening 73, there is provided a flexible boot 75 which has an outer flange 75a, which is clamped between wall 71 and shoulder ring 66. The boot is in sealed engagement with a coupling member 78, as shown in Fig. 1. The boot permits the shaft to reciprocate axially while sealing the actuator against moisture and contaminants.

The forward end of the cutting tool includes a pair of clamp structures, or means, 78, 79 for clamping in a cutting tool assembly designed for releasable attachment to the cutting device. Before describing the two clamping structures, it is useful to consider the construction of the cutting assembly. One exemplary tool assembly, for use as a scissors type cutting tool, is shown in exploded view at 80 in Fig. 6. The assembly generally includes an outer sleeve 82 (Fig. 6-8) having an axial bore 84 (Fig. 8) , an inner sleeve 86, a portion of which is mounted within the axial bore for limited axial movement with respect thereto, and a cutting tool 88 having a proximal end 90 secured to the inner sleeve .and a distal cutting end 92.

Considering details of the tool assembly, and with reference to Figs. 6 8, the outer surface of sleeve 82 is formed with a series of annular grooves, such as grooves 94, which facilitate grasping the assembly 24 to withdraw it from engagement with the handpiece 22. The proximal end of the sleeve (the right end in Figs. 7 and 8) has a smaller-diameter outer surface region in which is formed an annular groove 96 for use in engaging clamping structure in the cutting device, as will be described.

Viewing Fig. 8, the inner bore of sleeve 82 includes a smaller diameter distal region 84a, and a larger-diameter proximal region 84b in which inner sleeve 86 is slidably received. A pin 98 carried in an central part of the larger bore region serves to limit reciprocal motion of the inner sleeve within this bore region, as seen below.

A tube 100 (Fig. 6) is received, e.g., by press fitting, in the proximal bore region of sleeve 84. One- exemplary tube is a 20 gauge stainless steel needle having a length of about 2.5 cm, and an inner diameter of about 26 mils. The tube supports a fixed-position cutting blade 102 which is carried at the distal end of a shaft 104 which itself is attached, as by welding, to the inner wall of the tube.

Sleeve 86 includes a bore 106 which receives and in which is attached the proximal end of tool 88, for axial movement therewith. Formed in the outer surface of this sleeve is a notch 10-8 which provides clearance for pin 91 in the assembly. The notch serves to limit the excursion of the inner sleeve within bore 84b between an extended position at which the right end wall of the notch in Fig. 6 contacts the pin, and a retracted position at which the left end wall of the notch in the figure makes contact with the pin. Also formed in the outer surface of sleeve 86 is a groove 110 for use in engaging clamping structure in the cutting device, as will be described.

In the assembly, movement of sleeve 86 between its extended and retracted positions moves- blade or blade end 90 back and forth with respect to fixed-position blade 102, as illustrated in Figs. 10A-10C, which show the relative positions of the blades at a fully extended, closed or cutting position (10A) , a partially open position (10B) , and a fully retracted, open position (IOC) .

Although the detachable cutting assembly has been described with respect to a scissors-type instrument with relatively moving blades, it will be appreciated that the assembly cutting tool(s) may be designed for performing a variety of microsurgical functions. Embodiments of a cutting assembly designed for use in tissue removal and tissue fragmentation are described below with respect to Figs. 15 and 16, respectively.

Returning to the clamping structures in the cutting device, reference is made particularly to Figs. 1, 2, 4, and 5. The clamping structures are part of an assembly 112 which is mounted on an annular extension 114 of body 24, for axial shifting with respect thereto. Assembly 112 includes a unitary ring structure 116 composed of three cylindrical members 118, 120, 122 having the cross- sectional shapes shown in Fig. 2 and threaded or press fitted together. Member 122 slides within a cavity 124 formed in extension 114, and member 120 slides within a cavity 126 formed within a cap 128 which serves to hold assembly 122 within body 24. A spring 130 interposed between a ridge 132 on the cap and a radial lip 134 in member 120 serves to bias the assembly tov/ard the left in Fig. 2.

As seen best in Figs. 4 and 5, member 118 has three angularly spaced, radial channels, such as channel 136, each of which contains a ball, such as ball 138-, which can move radially within the channel. The balls are confined in the channels by a cap 140 which fits over member 118 as seen in Fig. 2, and is axially slidable thereon. The cap is biased towards the stop position shown in Fig. 2 by a spring 142. The cap has an annular step 144 which allows the balls in member 118 to move outwardly in a radial direction, when the cap is moved inwardly on member 118, to a position where the cap contacts lip 134 on member 120. Member 118, cap _.140 mounted slidably thereon, spring 142 and the balls in member 118 which collectively form clamping structure or means 79 for releasably clamping sleeve 82 in the cutting tool assembly, as will be described below. Considering now clamping structure 78, Fig. 9 shows details of^•' aboye.-described coupling member 77 and the forward end of shaft 30 which is coupled thereto. As seen, the coupling member is composed of a coupling sleeve 146, a proximal region of which is rigidly attached to the shaft in the armature, as by press fitting, and a distal region of which is adapted to receive a portion of inner sleeve 86 of the tool assembly, as shown. In constructing the coupling member, one or more O-rings, such as O-ring 148, are placed in the sleeve at the position shown, and forced into place against an annular lip 150 in the sleeve by a sleeve-like coupler 154 which is press fitted into the distal region of sleeve 148 as shown. The opposite end of coupler 154 is press fitted into a cap 156 which houses a C-ring 158 adapted to releasably engage groove 110 in the inner sleeve of the tool assembly, when such is forced into the cylindrical cavity formed by the coupling member. This releasable engagement couples the inner sleeve of the tool assembly to shaft 30 in the armature, for reciprocal motion therewith during operation of the cutting device. The coupling member, O-rings, and C-ring collectively form the clamping structure or means 78 in the cutting device.

Completing the description of the cutting device, Fig. 12 is a schematic view of the circuit controller, or circuit means, 160 used in driving the linear actuator in the device in one of a variety of selectable modes. The device generally includes a potentiometer switch 162, typically in the form of a foot switch.

Switch 162 includes, in addition to the potentiometer, a two-position switch 165 at one end of travel, which will turn on a solid-state CMOS analog switch 166, such as an

AD221 Analog Devices switch. Switch 165 also enables a selected waveform or combination of waveforms to reach a class-B power amplifier 168 which drives the coil in the linear actuator. A second two-position switch 170 at the other end of travel of switch 162 is used in providing a positive DC voltage 164 to the actuator, to fully close the cutting blades in the tool assembly, as described below.

A mode selector 171 in the circuit includes four switches 174, 176, 178, 192 which are preferably CMOS switches driven by simple logic gates determined by the operating mode selected. The output of the switches is connected to a summing amplifier 180, which is a conventional inverting operational amplifier, such as an amplifier TL084 supplied by Texas Instruments. When switch 170 in the potentiometer switch is activated, switch 192 will close, with switches 174, 176, 178 open, such that a positive DC voltage 164 only will be applied to switch 166, to fully close the blades. The switch 170 is needed only with a scissors type tool assembly, so that regardless of which mode is selected, the surgeon will have a means to close the blades fully before introducing the cutting blades into the surgical site.

Amplifier 168 includes a pnp (TIP-127) and an npn

(TIP-127) Darlington pair, and an inverting op amp, and is of conventional design, with appropriate feedback and compensation network for the inductive load of a motor to ensure stability.

An oscillator 182 in the circuit is preferably a function generator such as an ICL8038 generator supplied by Harris Semiconductor. The oscillator provides square, sinusoidal, or triangular waveforms. The output frequency is adjustable by a potentiometer 184.to achieve a selected output frequency, preferably between 1-20 Hz, and more preferably between 1-10 Hz. A higher-frequency oscillator, referred to herein as vibrator 186, may be a function generator or simply an op amp with positive feedback which oscillates with a square wave output. The vibrator can be preset to output a selected square-wave frequency, preferably between 50- 1,000, e.g. , 500 Hz.

A monostable multivibrator 188 in the circuit is a digital IC, e.g., 74HC123 multivibrator that is activated when the foot pedal is fully released (activating switch 165) . At that moment, a negative pulse is generated to' push the shaft of the motor back, to ensure that the two cutting blades will be fully open at their rest positions.

The operation of the cutting device will now be described, first with respect to releasably attaching a cutting tool assembly, such as assembly 80 to the device. As a first step, the assembly is inserted into the clamping structure, as indicated in Figs. 11A and 11B, with cap 140 moved rearwardly against spring 142 to allow the balls in clamping structure 79 to move radially outwardly within radial step 144. When the tool assembly has been moved. axially to a position where the balls in clamping structure can engage groove 96 in sleeve 82 of the assembly, cap 140 is released, to lock the balls into a -position of positive engagement with groove 96.

With reference particularly to Figs. 2, 9, and 11A and 11B, the tool assembly is now pushed rearwardly to engage

C-ring 158 in clamping structure 78 with groove 110 in sleeve 86 of the tool assembly. ■ As the tool assembly is initially pushed rearwardly (toward the right in the figures) the armature in the actuator is pushed in the same direction until it reaches its fully retracted position, shown in Fig. 11A and can move no further. At this point, continued pushing of the assembly in. a rearward direction forces sleeve 86 further into coupling member to a position at which groove 110 of sleeve 86 is disposed somewhat to the left of C-ring 158 in the coupling member. Releasing the assembly, sleeve 82 is moved to the left in the figures by spring 126, placing sleeve 86 in a retracted position.

It will be appreciated that when the armature is first activated to move toward its extended position, as shown in Fig. 11B, the coupling member will be forced to the left in Fig. 9 until it engages groove 110 in sleeve 86, thus coupling the sleeve in positive engagement with shaft 30. At this point continued movement of the armature shaft toward its fully extended and fully retracted positions serves to move sleeve 86 relative to sleeve 82 in the tool assembly between fully extended and fully retracted positions. The various modes of movement of the tool assembly will now be considered.

In one mode of operation, referred to herein as a proportional or linear mode, the movable blade in the tool assembly is moved away from an intermediate position selectively according to the setting of a user-controlled foot switch, identified as switch 162 in Fig. 12. In this mode, the circuit controller is set to engage switch 176, connecting the output of switch 162 with the coils in actuator 26. The voltage level produced in switch 162, as the potentiometer in the switch is moved in either direction away from a 0 volt output is shown in Fig. 13.

At the 0-volt position of the switch, the actuator is in a position intermediate the two positions shown in Fig. 11A and 11B. At this position, blades 90, 108 in the attached tool assembly are in an intermediate position, somewhat more open than that shown in Fig. 10B. Assuming the total allowed excursion of the armature is between 50- 100 mils, this distance between blades at this midpoint is between about 25-50 mils.

As the foot-switch potentiometer is moved to output a negative voltage, the armature is moved proportionately toward its retracted position, moving blade 90 rearwardly with respect to fixed-position blade 102. It is appreciated that the extent of relative movement of the blades can be finely controlled in this manner, allowing the user to position the blades and hold the positioned blades at a selected position until further foot switch movement is made. As the foot switch is operated to bring the potentiometer to its most-negative output position, shown in Fig. 13, the armature is moved to its fully retracted position, shown in Fig. 11A, at which the blades are in their fully open position, shown in Fig. 10C- Similarly, as the foot switch is operated to bring the potentiometer to its most-positive output position, shown in Fig. 13, the armature is moved to its fully extended position, shown in Fig. 11B, at which the blades are in their fully closed position, shown in Fig. 10A.

In a second general operational mode, the device is set, through switch 178, to connect oscillator 182 in the circuit with actuator 26. In this mode, the circuit controller is further set to a selected frequency, typically between 1-20 Hz, and a desired wave output. Fig. 14 shows the waveforms of a sine wave output (dotted lines) or square-wave output (solid lines) . One advantage of the sine wave output (or a triangular wave output) is that the armature approaches its fully extended and fully retracted positions gradually, and therefore with substantially smoother action.

Regardless of waveform selected, the amplitude of the signal is preferably greater than that required to move the armature between its fully extended and fully retracted positions, typically 50-100 mils. However, a lower- amplitude signal will result in a smaller excursion of the armature away from its "at rest" position.

In either the proportional or oscillatory modes described above, the circuit controller can also be set to provide a relatively high frequency vibrational component superimposed on the linear or slow-frequency oscillatory movement. This is done- by connecting switch 174 in combination with either switch 176 (for linear mode) or switch 178 (for oscillatory mode) . Fig. 14 show a square wave oscillatory-mode output having a superimposed square-wave component produced by vibrator 186. Because of the relatively high-frequency of the superimposed component, the inertia of the armature will confine it to undergo a vibrational excursion which is substantially less than the total excursion between fully extended and retracted positions. Typically, the small displacement vibration excursion is from 1-3 mils, compared with a total excursion of 50 mils or more. The extent of vibrational excursion can be increased by reducing vibrational frequency or increasing vibration-signal amplitude.

As indicated above, switch 162 is designed to operate a switch 165 at one extreme position of the foot pedal in the switch. When switch 165 is depressed it will direct the selected voltage signal to the power amp when depressed. When released, the switch will activate switch 166 to the position shown in Fig. 12, causing multi¬ vibrator 188 to deliver a short negative pulse to amplifier 168 and actuator 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 procedure and thereafter be returned to the closed position by the positive DC signal.

It is advantageous for safety reasons to provide means for causing the blades in the tool assembly to be in overlapping, i.e., fully closed, relationship in the event of a power failure to the device. If, during a surgical procedure the power were to be interrupted, the biasing springs in the armature would locate the movable blades at an intermediate position, as noted above, making it difficult for the surgeon to remove the tool assembly blade end 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. 10A. It will be appreciated from Figs. 11A that by moving assembly 80 manually in a rearward direction, sleeve 82 and its attached fixed-position blade 102 is also moved rearwardly, ultimately to a position where the two blades are overlapping. The tool assembly disclosed includes a detachable assembly having relatively reciprocable scissors blades. It is contemplated that the device can also be used with a variety of other tool assemblies for use in tissue removal, tissue fragmentation, and other specialized microsurgical operations.

Fig. 15 shows a tool assembly 192 having inner and outer sleeves 194, 196, respectively, which have substantially the same construction as sleeves 86, 82, respectively. A tube 198 in the assembly is rigidly attached to sleeve 196, and defines an inner bore 200 and adjacent its distal end, an axially extending opening 202. A needle-like tube 204 rigidly attached to and extending through sleeve 194 in the assembly has a bladed distal end 206 designed to move back and forth across opening 202 when sleeve 194_, is moved between fully retracted and extended positions with respect to sleeve 196, producing a cutting action of tissue disposed adjacent the opening.

The assembly is preferably designed for use with a cutting device of the type described above, but additionally providing a vacuum source communicating with the coupling member in the device, and therefore also communicating with the open proximal end of tube 204, during a tissue removal operation. The suction in the tube acts to draw tissue into opening 202, when tube 204 is in a retracted position. As the bladed tube is then extended past the opening, tissue is sliced away, then drawn into tube 204 at the next retraction position.

Fig. 16 shows a tool assembly 206 having inner and outer sleeves 208, 210, respectively, these sleeves having substantially the same construction as sleeves 86, 82, respectively. A tube 212 in the assembly extends slidably through a bore 214 in sleeve 210 and extends through and is rigidly attached, as by press fitting, within a bore 216 in sleeve 208.. The tube has a bladed distal end 218. The assembly is preferably designed for use with a cutting device of the type described above, but also additionally providing a vacuum source communicating with the coupling member in the device, and therefore also communicating with the open proximal end of tube 212, during a tissue removal operation. The suction in the tube acts to draw tissue into opening the bladed opening of the tube, as the tube is move by oscillation, or a combination of oscillation and vibration, to fragment tissue at a microsurgical site. In one aspect, the present invention includes a cutting tool assembly of the type illustrated by assemblies 80, 192, and 206, for use with a microsurgical tool having a handle body of the type described above.

The assembly generally includes an outer sleeve having an axial bore, an inner sleeve, a portion of which is mounted within the axial bore of the outer sleeve for limited axial movement with respect thereto, and a cutting tool having a proximal end secured to the inner sleeve and a distal cutting end. In a preferred embodiment, the assembly is disposable after a single use, and is removed for disposal simply by releasing cap 140 in the cutting device to release clamping structure 79, then forcibly pulling the inner sleeve in the assembly out of its C-ring attachment by clamping structure 78. Assembly 80, which is designed for tissue cutting .by a scissors action, further includes a tube attached to the outer sleeve, a fixed-position blade mounted in this tube, and the cutting tool is movable within the tube, as the actuator is moved between its fully retracted and extended positions, to positions at which the cutting end of the cutting tool is open and closed with respect to the fixed- position blade, respectively.

Assembly 192, which is designed for use in tissue removal, further includes a tube attached to the outer sleeve and defining an axially extending opening adjacent the tube's distal end. The cutting end of the cutting tool is designed to move within the tube, adjacent this opening. The assembly is preferably adapted for use with a cutting device designed to exert a vacuum within the bladed tube. In assembly 208, which is designed for tissue fragmentation, the cutting tool includes a tube having a bladed end.

From the foregoing, it will be appreciated how various^' objects and features of the invention are met. The cutting device is designed for controlled-position linear or oscillatory motion of cutting blade. The linear mode allows a surgeon to set blade distances precisely for particular types of cutting operations, and to cut with a controlled cutting motion, as though the surgeon had direct manual control of two bladed elements. In a combined linear/vibrational mode, the linear operation can be coupled with a vibrational mode to effect vibration-type cutting at a selected blade-distance setting. Similarly in the oscillatory mode, the full-excursion blade motion can be coupled with a vibrational mode to effect snipping, a vibrational cutting action.

The cutting tool assembly of the invention is releasably coupled to the cutting device by a pair of clamping structures which allow the two sleeves in the assembly to be positively clamped, during a cutting operation, but also easily released after use. The assemblies may be disposable to avoid problems of contamination and infection, or damaging the blades during cleaning.

Although the invention has been described with respect to particular cutting tools and applications, it will be appreciated that a variety of tools and applications suitable for fine tissue cutting in a surgical setting can be achieved with the present invention.

Claims

IT IS CLAIMED:

1. A microsurgical cutting device for cutting tissue, such as ocular tissue, comprising: a handle body for gripping by a surgeon during a cutting operation; a linear actuator carried in said body, and having an armature which is movable axially, under the influence of a voltage applied to the actuator, between fully extended and fully retracted positions, means for clamping a microsurgical cutting tool to the actuator's armature, for movement therewith between sucn extended and retracted positions, and circuit means for driving the armature in one of the following selectable modes:

(a) a proportional mode in which the position of the armature between its fully extended and fully retracted positions is controllable^' by a user-operate switch, by supplying a switch-controlled DC voltage to the actuator; and

2. The cutting^' device of claim 1, wherein said circuit means is effective, in either the proportional mode or oscillatory mode, to supply a high-frequency wave voltage, in the range-between about 50-1,000 Hz, to the actuator, to produce a superimposed vibrational component whose amplitude is substantially less than that of total excursion distance of the armature between its fully retracted and fully extended positions.

3. The device of claim 1, wherein the circuit means is effective to supply a square, sinusoidal, or triangular wave to the actuator, to drive the actuator in its oscillatory mode.

4. The device of claim 1, wherein the actuator moves through an excursion of between about 50-100 mils between its fully extended and retracted position.

5. The device of claim 4, wherein the armature in the actuator is composed of an inner shaft and a series of annular magnets carried at spaced axial intervals along the shaft, with the magnetic pole of one magnet having the same polarity as the confronting magnetic pole of the adjacent magnet and being spaced therefrom by an axial gap, and the actuator further includes a series of stationary windings which are spaced axially along the body at positions corresponding to said gaps between magnets, wherein application of voltage in opposite directions to adjacent windings causes the armature to move in a selected direction, and reversal of the directions of such voltage causes the armature to move in the opposite direction.

6. The device of claim 5, wherein said circuit means includes a low-frequency oscillator whose frequency can be selectively varied between about 1-20 Hz to control the rate of oscillatory movement of the armature.

7. The device of claim 6, wherein said circuit means includes a high-frequency oscillator whose frequency can be selectively varied between about 50-1,000 Hz to. control the rate of vibratory movement of the armature.

8. The device of claim 1, for use with a microsurgical cutting tool which is part of a tool assembly that includes an outer sleeve having an axial bore, an inner sleeve, a portion of which is mounted within said axial bore for limited axial movement with respect thereto, and a cutting tool having a proximal end secured to the inner sleeve and a distal cutting end, wherein said clamping means includes first clamping means -carried on said handle-like body for receiving said outer sleeve in clamping engagement therewith, and second clamping means carried on the armature for receiying -said ^".inner sleeve in clamping engagement therewith.

9. The device of claim 8, wherein said first and second clamping means include annular clamps for releasably engaging the outer surfaces of said outer and inner sleeves, respectively.

10. A microsurgical cutting device for cutting tissue, such as ocular tissue, comprising a handle body for gripping by the surgeon during the cutting operation, an actuator carried in said handle body, and having an armature which is movable axially, under the influence of a voltage applied to the actuator, between a fully extended and a fully retracted position, a tool assembly having an outer sleeve having an axial bore, an inner sleeve, a portion of which is mounted within said axial bore for limited axial movement with respect thereto, and a cutting tool having a proximal end secured to the inner sleeve and a distal cutting end, first clamping means carried on said handle-like body for receiving said outer sleeve in clamping engagement therewith, and second clamping means carried on the armature for receiving said inner sleeve in clamping engagement therewith.

11. The device of claim 10, wherein said first and second clamping means are designed to ^"releasably engage and clamp said outer and inner sleeves, respectively.

12. The device of claim 11, wherein said tool assembly is designed for tissue cutting by a scissors action, which further includes a tube attached to the outer sleeve, a fixed-position blade mounted in said tube, and said cutting tool is movable within the tube, as the actuator is moved between its fully retracted and fully extended positions, to positions at which the cutting end of the cutting tool is open and closed with respect to the. fixed-position blade, respectively.

13. The device of claim 11, wherein said tool assembly is designed for tissue removal, which further includes a tube attached to the outer sleeve and defining an axially extending opening' adjacent the tube's distal end, the cutting end of said cutting tool is designed to move within said tube, adjacent said opening, and the device further includes means for exerting a suction within said tube, to draw tissue into said opening.

14. The device of claim 11, wherein said tool assembly is designed for tissue fragmentation, wherein the cutting tool includes a tube having a bladed end.

15. A disposable cutting tool assembly for use with a microsurgical tool having a handle body, a first clamp structure attached to body, an actuator carried in the handle body, and including an armature which is movable axially, under the influence of a voltage applied to the actuator, in an axial direction between a fully extended and a fully retracted position, and a second clamp structure coupled to the armature for axial movement therewith, said tool assembly comprising: an outer sleeve having an axial bore, an inner sleeve, a portion of which is mounted within said axial bore for limited axial movement with respect thereto, and a cutting tool having a proximal end secured to the inner sleeve and a distal cutting end.

16. The assembly of claim 15, wherein said outer and inner sleeves include recessed portion adapted to receive first and second clamping means releasably therein, respectively.

17. The assembly of claim 15, which is designed for tissue cutting by a scissors action, which further includes a tube attached to the outer sleeve, a fixed-position blade mounted in said tube, and said cutting tool is movable within the tube, as the actuator is moved between its fully retracted and fully extended positions, to positions at which the cutting end of the cutting tool is open and closed with respect to the fixed-position blade/ respectively.

18. The assembly of claim 15, which is designed for tissue removal, which further includes a tube attached to the outer sleeve and defining an axially extending opening adjacent the tube's distal end, the cutting end of said cutting tool is designed to move within said tube, adjacent said opening, and the assembly is adapted for use with a cutting device designed to exert a vacuum within said tube.

19. The assembly of claim 11, which is designed for tissue fragmentation, wherein the cutting tool includes a tube having a bladed end.