Ultrasound handpiece

The present invention relates to an ultrasonic device and, more specifically, to a device for controlling a handpiece for ophthalmic phacoemulsification.

A typical ultrasonic surgical device applicable to ophthalmic surgery is equipped with an ultrasonically driven handpiece, an attached hollow cutting tip, a water injection sleeve, and an electronically controlled console. The handpiece assembly is connected to the control console described above by an electric cable and flexible tubes. The control console changes the power level transmitted by the handpiece to the cutting tip via an electrical cable. The flexible tube also supplies the water injection fluid to the eye via the handpiece assembly and removes the suction fluid from the eye.

The moving part of the handpiece is a hollow resonance rod or horn placed in the center, to which a set of piezoelectric crystals is attached directly. This piezoelectric crystal provides the essential ultrasonic vibrations needed to drive both the horn and the accompanying cutting tip while performing phacoemulsification. At this time, the piezoelectric crystal is controlled by the console. Piezoelectric crystal / horn assemblies are suspended at nodes within the shell of a hollow body or handpiece by a relatively inflexible mounting method. The handpiece fuselage terminates at a reduced diameter portion, a nose cone at the distal end of the fuselage. The nose cone is mounted on the outside to accommodate the water injection sleeve. Similarly, the horn hole is fitted medially at the distal end of the fuselage to accommodate the external thread of the cutting tip. The water injection sleeve also has a through hole inside, which is screwed towards the outer thread of the nose cone. The cutting tip is adjusted so that the tip allows only a predetermined amount of water to be discharged through the open end of the water injection sleeve. Ultrasonic handpieces and cutting tips are described in detail in US Pat. Nos. 3,589,363, 4,223,676, 4,246,902, 4,493,694, 4,515,583, 4,589,415, 4,609,368, 4,869,715, and 4,922,902. All of these statements are incorporated herein by reference.

When performing phacoemulsification, the tip of the cutting tip and water injection sleeve has a predetermined width in the cornea, sclera, or elsewhere to allow access to the anterior chamber of the eye. It is inserted up to the small incision of. The cutting tip is ultrasonically vibrated along the vertical axis in the water injection sleeve by an ultrasonic horn driven by a piezoelectric crystal. As a result, the cutting tip emulsifies a predetermined location by contacting the selected eye tissue. The hollow holes in the cutting tip communicate with the holes in the horn, and the holes in the horn communicate in sequence with the suction line leading from the handpiece to the console. A decompressed pressure or vacuum source in the console aspirates the emulsified tissue from the eye through the open end of the cutting tip, the holes in the cutting tip and horn, and the suction line and removes it into the collector. .. Aspiration of emulsified tissue is assisted by wash saline. That is, this suction is assisted by the cleaning fluid injected into the surgical site through a small annular gap between the inner surface of the water injection sleeve and the outer surface of the cutting tip. The irrigation also helps maintain fluid balance in the eye and maintain the shape of the eye.

Conventionally, there have been attempts to combine the ultrasonic longitudinal motion of a cutting tip with the rotational motion of the tip. These attempts can be referred to in US Pat. No. 5,222,959 (Inventor: Anis), US Pat. No. 5,722,945 (Inventor: Anis, et al.), And US Pat. No. 4,504,264 (Inventor: Kelman). The entire contents of these patents are incorporated herein by reference. These conventional attempts have used electric motors to achieve rotational motion of the chip. This required, in addition to the complexity and potential for failure added by the use of electric motors, an O-ring or another seal that could result in failure.

There have also been conventional attempts to generate both longitudinal and twisting motions without the use of electric motors. For example, US Pat. Nos. 6,028,387, 6,077,285, and 6,402,769 (inventor: Bowfney) describe a handpiece with two pairs of piezoelectric crystals. One pair is polarized to produce longitudinal motion. Another pair is polarized to produce a twisting motion. Two separate drive signals are used to drive two pairs of piezoelectric crystals. In practice, it is difficult to make a handpiece that uses two pairs of piezoelectric crystals that resonate in both the longitudinal and twist directions. Also, one possible solution is described in US Patent Application Publication No. 2001/0011176A1 (Inventor: Bowfney). This reference is on a single set of piezoelectric crystals that produce longitudinal motion and on the horn or chip that produces twisting motion when the horn or chip of the handpiece is driven at the resonant frequency of the piezoelectric crystal. A handpiece having a continuous slit in an oblique direction is disclosed. In this case as well, as a practical matter, it was difficult to achieve longitudinal motion and twisting motion at the same time because the resonance frequencies of the piezoelectric crystal and the chip or horn did not match.

<p> Therefore, there remains a need for reliable ultrasonic handpieces that vibrate in both longitudinal and twisting motions, either simultaneously or separately.</p>

<p> The present invention presents a handpiece having at least one pair of piezoelectric elements polarized to generate longitudinal motion when excited at the relevant resonance frequency, thereby operating a prior art ultrasonic handpiece. It is an improvement on the method. The piezoelectric crystal is connected to an ultrasonic horn to which a cutting tip is attached. The horn and / or cutting tip includes a plurality of diagonal slits or grooves. These slits or grooves produce an optimized twist motion within the cutting tip when the piezoelectric crystal is excited at a second resonance frequency. When in twist mode, material can clog the cutting tip. The method of the present invention includes a step of supplying a pulse for longitudinal movement of the chip when a clogged state is detected.</p><p> Therefore, one of the objects of the present invention is to present an ultrasonic handpiece having both longitudinal and twisting motions.</p><p> A further object of the present invention is to present an ultrasonic handpiece with a horn with continuous diagonal slits to generate a twisting motion.</p><p> Another object, feature and advantage of the present invention will be clarified by reference to the following description in drawings and drawings and the like.</p>

As best shown in FIG. 4, the surgical console 320 suitable for use of the present invention can be any commercially available surgical control console. For example, the console could be an INFINITI® surgical system available from Alcon Laboratories in Fort Worth, Texas. The console 320 is connected to the handpiece 10 via a water injection line 322 and a suction line 50, and the flow through both of the above lines 322 and 50 is controlled by the user, for example, via a foot-operated switch 326. Power is supplied to the handpiece 10 via the electrical cable 400.

As best shown in FIG. 1, the handpiece 10 of the present invention generally includes an ultrasonic horn 12, which is usually made of a titanium alloy. The ultrasonic horn 12 has a plurality of spiral slits, and these slits will be described below. A plurality of ring-shaped piezoelectric elements 14 (generally one or two pairs) are held by a compression nut 15 with respect to the horn 12. The suction shaft 16 extends to the full length of the handpiece 10 and extends to the distal end of the handpiece 10 via the horn 12, the piezoelectric element 14, the nut 15 and the plug 18. The tube portion of the suction shaft 16 can suck a substance through the hollow tip 20. This tip is attached to the horn 12 and is inserted and removed from the handpiece 10. The plug 18 seals the fluid-sealing outer shell 11 of the handpiece 10 so that the handpiece 10 can be pressure sterilized without adversely affecting the piezoelectric element 14. An additional groove 22 is provided above the horn 12 to seal the O-ring gasket (not shown).

As best shown in FIG. 2, the horn 12 includes a plurality of spiral slits 24. Preferably, the width of the slit 24 is between 2% and 65% of the outer diameter of the horn 12. Of course, this affects the number of slits 24 that can be made on the horn 12 (for example, when the width of the slits 24 is 65% of the outer diameter of the horn 12, only one slit 24 is the horn 12). Engraved on). The width of the slit 24 selected will depend on the required width of the torsional motion. The depth of the slit 24 within the horn 12 is preferably between 4% and 45% of the outer diameter of the horn 12. The slit 24 can have a flat or square bottom cut, but preferably it can also have a circular or radial bottom, the latter being easier to make. The length of the slit 24 is preferably between 8% and 75% of the larger diameter of the horn 12. The pitch of the slits 24 is preferably between 125% and 500% of the larger diameter of the horn 12. As an example, an example of a properly placed slit on a horn 12 with an outer diameter of 0.475 inches (1.21 cm) is 0.04 inches (0.10 cm) wide and 0.140 inches (0.36 cm) deep at the bottom of the full radius. A total of eight slits 24 having a length of 0.7 inches (1.78 cm) and a pitch of 1.35 inches (3.43 cm) were arranged. It was found that the one manufactured with this arrangement gives a twisting motion suitable for the horn 12 and does not jeopardize the vertical motion of the horn 12.

As best shown in Figure 1, the positions of the twisting and longitudinal nodes (zero velocity points in individual mode) are important for the proper functioning of the handpiece 10. If the twist node 26 is preferably close to the vertical node 28, the twist node 26 and the vertical node 28 will be in the same location, for example, both will be on the plug 18. The handpiece 10 will also include a terminal longitudinal node 30 placed on the reduced diameter portion 32 of the horn 12.

As best shown in FIG. 3, the drive circuit 34 that can be used with the handpiece 10 of the present invention is preferably similar to that described in US Pat. No. 5,431,664. The contents of this patent are incorporated herein by reference. Among them, the drive circuit 34 detects the admittance of the handpiece 10 and controls the frequency of the handpiece 10 so as to maintain a constant admittance. However, the drive circuit 34 monitors both twist and longitudinal modes and uses two different drive frequencies to control both modes within the handpiece 10. Preferably, the twist drive signal is about 32 KHz and the vertical drive signal is 44 KHz, but these frequencies depend on the size and shape of the piezoelectric element 14, the horn 12 and the slit 24 used. Will be changed. Although both the longitudinal motion signal and the twisting motion signal can be continuously supplied, preferably, the twisting motion signal and the longitudinal motion signal are alternately performed to request the drive signal. The number of pulses is supplied at one frequency, and then the same number of pulses is switched to another frequency for supply. However, there is no overlap between the two frequencies, but there is no gap or interruption in the drive signal. As an alternative, the drive signal can be operated in the same manner as described above to introduce a short pause or gap in the drive signal. In addition, the amplitude of the drive signal can be modulated and set individually for each frequency.

Pauses or gaps between drive signals can serve a variety of purposes. One purpose is to allow the ultrasonic motion to the piezoelectric element 14 and the horn 12 to be attenuated or stopped so that the crystalline lens debris can be sucked up again by the chip 20 or the blocked state can be restored. As a result, the holding force on the crystalline lens portion is increased. Restoring the obstruction will increase the cutting efficiency of subsequent ultrasonic pulses, whether in longitudinal or twisting motions. Another purpose of pauses or gaps between drive signals is to allow the ultrasonic motion to the piezoelectric element 14 and the horn 12 to be damped or stopped before the other mode (either longitudinal or twisting) is excited. Is to do. This attenuation between the drive signals will reduce the amount of non-linear interactions latent in the system. This non-linear interaction can generate unwanted heat and can lead to premature deterioration of the piezoelectric element 14 or mechanical damage to the entire assembly.

As an alternative, there can be a slight overlap in the drive signals for longitudinal and twisting motions. This overlap, can be provided in a relatively short time interval, twisting movements and Tateun displacement of the chip when the both operation of the dynamic is applied would occur particularly fast changes in phacoemulsification. However, this overlap is short enough to prevent premature deterioration of the piezoelectric element 14 or mechanical damage to the entire assembly as a result of excessive stress.

Yet another alternative is to completely overlap the drive signals of longitudinal or twisting motions, which results in high levels of stress on the lens material when the two signals overlap, but Placing a dormant state between the drive signals will improve the efficiency of subsequent pulse application for recovery of the blockage state and enhancement of the degree of vacuum.

Yet another alternative is to apply a continuous longitudinal signal with a pulsed twist signal. Alternatively, the above application is reversed and a continuous twist signal is applied together with a pulsed vertical signal. Continuous application of twisted ultrasonic waves does not generate repulsive forces. This is because the movement of the tip 20 is directed in the direction in which the tip 20 engages in the direction perpendicular to the crystalline lens. Also, the pulsed application of longitudinal ultrasonic waves is short enough to prevent overheating or mechanical loss to the piezoelectric element 14.

Moreover, as already described, both the longitudinal and twist drive signals can be applied continuously and simultaneously with the amplitudes of both signals selected to reduce overheating and excessive mechanical stress on the system. it can. When using such a drive scheme scheme, two pairs of piezoelectric elements 14 may apply a twist signal to one pair and a vertical signal to another pair. Recommended.

Finally, the longitudinal motion of the tip helps remove the material sucked into the tip in a manner similar to a peristaltic pump. The twisting motion of the tip does not produce the motion like the above-mentioned percussion. As a result, the tip 20 can become clogged when simply using a twisting motion. The clogging of the tip is evidenced by the vacuum created by the pump 70 increasing the degree of vacuum on the suction side within the suction line 50. Therefore, when the increase in vacuum on the suction side is detected in the suction line 50 by the pressure sensor 60, the pressure sensor 60 provides this sensing information to the drive circuit 34. When the perceived degree of vacuum exceeds a given threshold, longitudinal mode can be used either for a short period of time, for increased strength, or for continuous use until the clogging is cleared. become. Those skilled in the art will recognize that variations in the duration and / or timing of longitudinal pulses are required to properly clear any clogging of the tip. In addition, the power of certain high levels of twist can tend to be more clogged than the power of lower levels. Thus, when the twist power level reaches a preselected power level, the longitudinal motion can be initiated automatically and at a variable power level. Those skilled in the art will also recognize that the phrase "power level" includes both amplitude (stroke) and pulse load cycles.

Although described above in certain embodiments of the invention, these descriptions are provided for the purpose of providing illustration and description. Modifications, modifications, modifications, and innovations from the systems and methods disclosed above are applicable without departing from the scope and spirit of the invention. For example, a primary drive signal can have a first frequency and allow twisting motion, while a secondary drive signal can have a second frequency and allow longitudinal motion. To do. Or vice versa.

<figref num="1">It is a perspective view when the outer case of the handpiece which can be used by the method of this invention is removed.</figref><figref num="2">It is a perspective view of the ultrasonic horn which can be used by the method of this invention.</figref><figref num="3">It is a block diagram of a drive circuit that can be used in this invention.</figref><figref num="4">It is a perspective view of the handpiece and the control console which can be used in this invention.</figref>

Code description

10 handpiece 11 outer shell 12 Ultrasonic horn 14 Piezoelectric element 20 cutting tips 24 slit 34 Drive circuit 50 suction line 60 pressure sensor 70 pump