Abstract:
A handpiece tip having a set of longitudinally vibrating piezoelectric elements. To obtain oscillatory or torsional movement, a deep, spiral groove is cut on the exterior of the tip shaft. The groove translates longitudinal vibrations into oscillatory or torsional vibrations, and does not require the use of a specialized handpiece.

Description:
[0001]    This application is a continuation-in-part patent application of U.S. patent application Ser. No. 09/450,800, filed Nov. 29, 1999.  
     
    
     
         [0002]    This invention relates to ultrasonic devices and more particularly to an ophthalmic phacoemulsification tips.  
         BACKGROUND OF THE INVENTION  
         [0003]    A typical ultrasonic surgical device suitable for ophthalmic procedures consists of an ultrasonically driven handpiece, an attached hollow cutting tip, an irrigating sleeve and an electronic control console. The handpiece assembly is attached to the control console by an electric cable and flexible tubings. Through the electric cable, the console varies the power level transmitted by the handpiece to the attached cutting tip and the flexible tubings supply irrigation fluid to and draw aspiration fluid from the eye through the handpiece assembly.  
           [0004]    The operative part of the handpiece is a centrally located, hollow resonating bar or horn directly attached to a set of piezoelectric crystals. The crystals supply the required ultrasonic vibration needed to drive both the horn and the attached cutting tip during phacoemulsification and are controlled by the console. The crystal/horn assembly is suspended within the hollow body or shell of the handpiece at its nodal points by relatively inflexible mountings. The handpiece body terminates in a reduced diameter portion or nosecone at the body&#39;s distal end. The nosecone is externally threaded to accept the irrigation sleeve. Likewise, the horn bore is internally threaded at its distal end to receive the external threads of the cutting tip. The irrigation sleeve also has an internally threaded bore that is screwed onto the external threads of the nosecone. The cutting tip is adjusted so that the tip projects only a predetermined amount past the open end of the irrigating sleeve.  
           [0005]    When used to perform phacoemulsification, the ends of the cutting tip and irrigating sleeve are inserted into a small incision of predetermined width in the cornea, sclera, or other location in the eye tissue in order to gain access to the anterior chamber of the eye. The cutting tip is ultrasonically vibrated along its longitudinal axis within the irrigating sleeve by the crystal-driven ultrasonic horn, thereby emulsifying upon contact the selected tissue in situ. The hollow bore of the cutting tip communicates with the bore in the horn that in turn communicates with the aspiration line from the handpiece to the console. A reduced pressure or vacuum source in the console draws or aspirates the emulsified tissue from the eye through the open end of the cutting tip, the bore of the cutting tip, the horn bore, and the aspiration line and into a collection device. The aspiration of emulsified tissue is aided by a saline flushing solution or irrigant that is injected into the surgical site through the small annular gap between the inside surface of the irrigating sleeve and the outside surface of the cutting tip.  
           [0006]    There have been prior attempts to combine ultrasonic longitudinal motion of the cutting tip with rotational or oscillating motion of the tip, see U.S. Pat. Nos. 5,222,959 (Anis), 5,722,945 (Anis, et al.) and 4,504,264 (Kelman), the entire contents of which are incorporated herein by reference. These prior attempts have used electric motors to provide the rotation of the tip which require O-ring or other seals that can fail in addition to the added complexity and possible failure of the motors. All electronic handpieces using specially polarized piezoelectric crystals are described in U.S. Pat. No. 6,077,285 (Boukhny), the entire contents of which is incorporated herein by reference.  
           [0007]    Accordingly, a need continues to exist for a simple, reliable ultrasonic handpiece that will oscillate.  
         BRIEF SUMMARY OF THE INVENTION  
         [0008]    The present invention improves upon prior art ultrasonic devices by providing a handpiece having a set of longitudinally vibrating piezoelectric elements. To obtain oscillatory or torsional movement, a deep, spiral groove is cut on the exterior of the tip shaft. The groove translates longitudinal vibrations into oscillatory or torsional vibrations, and does not require the use of a specialized handpiece.  
           [0009]    It is accordingly an object of the present invention to provide an ultrasound handpiece having both longitudinal and torsional motion.  
           [0010]    It is a further object of the present invention to provide an ultrasound handpiece tip with a spiral groove along its shaft to produce torsional motion.  
           [0011]    Other objectives, features and advantages of the present invention will become apparent with reference to the drawings, and the following description of the drawings and claims.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is an elevational view of the ultrasonic horn that may be used with the handpiece of the present invention.  
         [0013]    [0013]FIG. 2 is a cross-section view of the ultrasonic horn that may be used with the handpiece of the present invention taken at line  2 - 2  in FIG. 1.  
         [0014]    [0014]FIG. 3 is a perspective view of the ultrasonic horn that may be used with the handpiece of the present invention.  
         [0015]    [0015]FIG. 4 is a perspective view of the handpiece of the present invention.  
         [0016]    [0016]FIG. 5 a block diagram of a first driving circuit that may be used with the present invention.  
         [0017]    [0017]FIG. 6 is a block diagram of a second driving circuit that may be used with the present invention.  
         [0018]    [0018]FIG. 7 is a side elevational view of one embodiment of the handpiece tip of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]    As best seen in FIG. 4, handpiece  10  of the present invention generally includes handpiece shell  12 , infusion sleeve  14  and cutting tip  16 . As best seen in FIGS.  1 - 3 , handpiece  10  contains ultrasonic horn  18 . Handpiece  10  generally contain at least one pair of piezoelectric crystals (not shown) coupled to horn  18  so as to create longitudinal vibratory motion in horn  18  when the crystals are excited. The materials used for and the construction of handpiece  10  and horn  18  (except as to slits  20 ) are well-known to those skilled in the art. See, for example, U.S. Pat. Nos. 4,169,984 (Parisi), 4,515,583 (Sorich), 4,989,588 (Kubota, et al.) and 5,359,996 (Hood), the entire contents of which being incorporated herein by reference. Horn  18  contains a series of generally parallel, circumferential, diagonal slits  20  near distal end  22  of horn  18 . The angle of slits  20  preferably is around 45 degrees to the longitudinal axis of horn  18 , which is the principal stress angle for horn  18 , but any angle between 10 degrees and 80 degrees may be used, with between 45 degrees and 60 degrees being preferred. As one skilled in the art will recognize, the exact location, number and size of slits  20  needed to convert the longitudinal motion of the crystals to torsional or oscillatory motion of distal end  22  of horn  18  will vary depending upon the amount of torsional motion desired. Generally speaking, efficient conversion will occur with slits  20  of between 0.001 inches and 0.4 inches deep. In addition, slits  20  need not be parallel to each other.  
         [0020]    As seen in FIG. 5, ultrasound generator  26  employs a broad-spectrum source to generate at least a component of the signal that drives an ultrasonic handpiece (“the drive signal”). The broad-spectrum source may be programmable and thus easily adjustable by varying certain input information fed to the source. However, a fixed-spectrum source may also be used without difficulty. A fast fourier transform (“FFT”) digital signal processor (“DSP”) may be used to analyze the response of handpiece  10  to the broad-spectrum component of the drive signal. In real-time applications, the output of the FFT DSP is used to generate control parameters embodied within an appropriate feedback signal, which is fed to the circuitry generating the drive signal in order to alter aspects of the drive signal. As seen in FIG. 6, ultrasound generator  26  may also use a conventional signal processor to analyze the response of handpiece  10  to the drive signal. The term “drive signal” as used here encompasses at least a signal useful solely for powering an ultrasonic handpiece, a signal useful solely for tuning or calibrating a handpiece, and a combination of such a power signal and such a tuning or calibration signal.  
         [0021]    As shown in FIG. 5, broad spectrum signal source  28  generates drive signal  4  which is combined with drive signals  5  and  6  from torsional single frequency source  30  and longitudinal single frequency source  32 , respectively, in amplifier  34 . Amplifier  34  delivers drive signal  36  to handpiece  10  and to FFT DSP  38 . FFT DSP  38  also receives feedback signal  40  from handpiece  10 . FFT DSP  38  processes drive signal  36  and feedback signal  40  in the manner more fully disclosed in commonly owned U.S. patent application Ser. No. 08/769,257 (corresponding to PCT Patent Application No. PCT/US97/15952), the entire contents of which being incorporated herein by reference, to determine the operating characteristics of handpiece  10 . FFT DSP  38  determines the electrical response of handpiece  10  on broad spectrum signal  4  and provides signal  42  to DSP  39  which generates adjusting signals  60  and  61  to adjust the frequencies and/or output voltage of sources  32  and  30 , respectively so as to adjust drive signals  5  and  6 .  
         [0022]    As shown in FIG. 6, two conventional drive signal sources, such as those described in U.S. Pat. No. 5,431,664, the entire contents of which is incorporated herein by reference, or U.S. patent application Ser. No. 08/769,257 (corresponding to PCT Patent Application No. PCT/US97/15952), may be used. For example, source  44  may generate drive signal  45  for torsional crystals  18  and source  46  may generate driving signal  47  for longitudinal crystals  20 . Drive signals  45  and  47  are combined in amplifier  134  and drive signal  136  delivered to handpiece  110 . Handpiece feedback signal  140  is filtered through separator  48  to provide adjusting signals  50  and  52  to sources  44  and  46 . Separator  48  may be any number of commercially available analog or digital devices such low pass or high pass filters or heterodyne receiver.  
         [0023]    As best seen in FIG. 7, as an alternative, or in addition to slits  20 , tip  116  may contain a spiral groove  120  along a portion of shaft  117  of tip  116 . Groove  120  must be suffiently deep to allow shaft  117  to flex. For example, the depth of groove  120  may be cut to a depth of approximately 10% to 90% of the thickness of shaft  117 , with between approximately 40% to 60% being preferably and with approximately 50% being most preferable, with a twist or angle of between 10 degrees and 70 degrees to the longitudinal axis of tip  116 , with between 30 degrees and 45 degrees being preferable. Preferably, groove  120  does not extend onto hub  122  of tip  116 , nor along portion  126  of shaft  117  that is in contact with sleeve  14 .  
         [0024]    While certain embodiments of the present invention have been described above, these descriptions are given for purposes of illustration and explanation. Variations, changes, modifications and departures from the systems and methods disclosed above may be adopted without departure from the scope or spirit of the present invention.