Abstract:
A tip for a liquefraction surgical handpiece. The tip uses at least two channels or tubes. One tube is used for aspiration and at least one other tube is used to inject heated surgical fluid for liquefying a cataractous lens. The distal portion of the injection tube terminates just inside of the aspiration tube and can be steered or directed so that heated fluid escaping the injection tube can be injected directly into the eye or reflected off of the internal wall of the aspiration tube prior to entering the eye. Alternatively, the injection tube may be relatively rigid but be extendable or contain a rotatable deflector that alternatively allows the heated fluid to be injected directly into the eye or reflected off of the internal wall of the aspiration tube. The handpiece may also contain other tubes, for example, for injecting relatively cool surgical fluid.

Description:
[0001]    This application is a continuation-in-part application of U.S. patent application Ser. No. 09/130,131, filed Aug. 6, 1998, which was a continuation-in-part application of U.S. patent application Ser. No. 09/090,433, filed Jun. 4, 1998. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    This invention relates generally to the field of cataract surgery and more particularly to a handpiece for practicing the liquefracture technique of cataract removal.  
           [0003]    The human eye in its simplest terms functions to provide vision by transmitting light through a clear outer portion called the cornea, and focusing the image by way of the lens onto the retina. The quality of the focused image depends on many factors including the size and shape of the eye, and the transparency of the cornea and lens.  
           [0004]    When age or disease causes the lens to become less transparent, vision deteriorates because of the diminished light which can be transmitted to the retina. This deficiency in the lens of the eye is medically known as a cataract. An accepted treatment for this condition is surgical removal of the lens and replacement of the lens function by an artificial intraocular lens (IOL).  
           [0005]    In the United States, the majority of cataractous lenses are removed by a surgical technique called phacoemulsification. During this procedure, a thin phacoemulsification cutting tip is inserted into the diseased lens and vibrated ultrasonically. The vibrating cutting tip liquifies or emulsifies the lens so that the lens may be aspirated out of the eye. The diseased lens, once removed, is replaced by an artificial lens.  
           [0006]    A typical ultrasonic surgical device suitable for ophthalmic procedures consists of an ultrasonically driven handpiece, an attached cutting tip, and 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.  
           [0007]    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 by flexible 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. Ultrasonic handpieces and cutting tips are more fully described in U.S. 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; 4,922,902; 4,989,583; 5,154,694 and 5,359,996, the entire contents of which are incorporated herein by reference.  
           [0008]    In use, 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. The cutting tip is ultrasonically vibrated along its longitudinal axis within the irrigating sleeve by the crystal-driven ultrasonic horn, thereby emulsifying 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 cutting tip and horn bores 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 cutting tip.  
           [0009]    Recently, a new cataract removal technique has been developed that involves the injection of hot (approximately 45° C. to 105° C.) water or saline to liquefy or gellate the hard lens nucleus, thereby making it possible to aspirate the liquefied lens from the eye. Aspiration is conducted with the injection of the heated solution and the introduction of a relatively cool irrigating solution, thereby quickly cooling and removing the heated solution. This technique is more fully described in U.S. Pat. No. 5,616,120 (Andrew, et al.), the entire contents of which is incorporated herein by reference. The apparatus disclosed in the publication, however, heats the solution separately from the surgical handpiece. Temperature control of the heated solution can be difficult because the fluid tubings feeding the handpiece typically are up to two meters long, and the heated solution can cool considerably as it travels down the length of the tubing.  
           [0010]    Therefore, a need continues to exist for a surgical handpiece that can heat internally the solution used to perform the liquefracture technique.  
         BRIEF SUMMARY OF THE INVENTION  
         [0011]    The present invention improves upon the prior art by providing a tip for a liquefraction surgical handpiece. The tip uses at least two channels or tubes. One tube is used for aspiration and at least one other tube is used to inject heated surgical fluid for liquefying a cataractous lens. The distal portion of the injection tube terminates just inside of the aspiration tube and can be steered or directed so that heated fluid escaping the injection tube can be injected directly into the eye or reflected off of the internal wall of the aspiration tube prior to entering the eye. Alternatively, the injection tube may be relatively rigid but be extendable or contain a rotatable deflector that alternatively allows the heated fluid to be injected directly into the eye or reflected off of the internal wall of the aspiration tube. The handpiece may also contain other tubes, for example, for injecting relatively cool surgical fluid.  
           [0012]    Accordingly, one objective of the present invention is to provide a surgical handpiece having at least two tubes.  
           [0013]    Another objective of the present invention is to provide a safer tip for a surgical handpiece having a pumping chamber.  
           [0014]    Another objective of the present invention is to provide a surgical handpiece having a device for delivering the surgical fluid through the handpiece in pulses that do not directly enter the eye.  
           [0015]    Another objective of the present invention is to provide a surgical handpiece having a steerable device for delivering the surgical fluid through the handpiece in pulses.  
           [0016]    Another objective of the present invention is to provide a surgical handpiece having a deflector for delivering the surgical fluid through the handpiece in pulses into the eye alternatively directly or indirectly.  
           [0017]    These and other advantages and objectives of the present invention will become apparent from the detailed description and claims that follow.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 is a front, upper left perspective view of the handpiece of the present invention.  
         [0019]    [0019]FIG. 2 is a rear, upper right perspective view of the handpiece of the present invention.  
         [0020]    [0020]FIG. 3 is a cross-sectional view of the handpiece of the present invention taken along a plane passing through the irrigation channel.  
         [0021]    [0021]FIG. 4 is a cross-sectional view of the handpiece of the present invention taken along a plane passing through the aspiration channel.  
         [0022]    [0022]FIG. 5 is an enlarged partial cross-sectional view of the handpiece of the present invention taken at circle  5  in FIG. 4.  
         [0023]    [0023]FIG. 6 is an enlarged partial cross-sectional view of the handpiece of the present invention taken at circle  6  in FIG. 3.  
         [0024]    [0024]FIG. 7 is an enlarged cross-sectional view of the handpiece of the present invention taken at circle  7  in FIGS. 3 and 4, and showing a resistive boiler pump.  
         [0025]    [0025]FIG. 8 is a schematic cross-sectional view of a heating element boiler pump that may be used with the present invention.  
         [0026]    [0026]FIG. 9 is an exploded, partial cross-section view of one embodiment of the handpiece of the present invention.  
         [0027]    [0027]FIG. 10 is an enlarged cross-sectional view of one alternative tip design for use with the present invention.  
         [0028]    [0028]FIG. 11 is an enlarged cross-sectional view of a second alternative tip design for use with the present invention showing the flexible tip in a straight configuration.  
         [0029]    [0029]FIG. 12 is an enlarged cross-sectional view of the second alternative tip design for use with the present invention illustrated in FIG. 11 showing the flexible tip in a curved configuration.  
         [0030]    [0030]FIG. 13 is an enlarged cross-sectional view of a third alternative tip design for use with the present invention showing the flexible tip in a straight configuration.  
         [0031]    [0031]FIG. 14 is an enlarged cross-sectional view of the third alternative tip design for use with the present invention illustrated in FIG. 13 showing the flexible tip in a curved configuration.  
         [0032]    [0032]FIG. 15 is a perspective view of a fourth alternative tip design for use with the present invention showing the slidable nozzle in an extended position.  
         [0033]    [0033]FIG. 16 is a perspective view of the fourth alternative tip design for use with the present invention illustrated in FIG. 15 showing the nozzle in retracted position.  
         [0034]    [0034]FIG. 17A is a front plan view of a fifth alternative tip design for use with the present invention showing the rotatable deflector in a straight configuration.  
         [0035]    [0035]FIG. 17B is a longitudinal cross-sectional view of the fifth alternative tip design for use with the present invention illustrated in FIG. 17.  
         [0036]    [0036]FIG. 18A is a front plan view of the fifth alternative tip design for use with the present invention showing the rotatable deflector in a rotated configuration.  
         [0037]    [0037]FIG. 18B is a longitudinal cross-sectional view of the fifth alternative tip design for use with the present invention illustrated in FIG. 18. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0038]    Handpiece  10  of the present invention generally includes handpiece body  12  and operative tip  16 . Body  12  generally includes external irrigation tube  18  and aspiration fitting  20 . Body  12  is similar in construction to well-known in the art phacoemulsification handpieces and may be made from plastic, titanium or stainless steel. As best seen in FIG. 6, operative tip  16  includes tip/cap sleeve  26 , tube  28  and tube  30 . Sleeve  26  may be any suitable commercially available phacoemulsification tip/cap sleeve or sleeve  26  may be incorporated into other tubes as a multi-lumen tube. Tube  28  may be any commercially available hollow phacoemulsification cutting tip, such as the TURBOSONICS tip available from Alcon Laboratories, Inc., Fort Worth, Tex. Tube  30  may be any suitably sized tubing to fit within tube  28 , for example  29  gauge hypodermic needle tubing. Alternatively, as best seen in FIG. 10, tube  30 ′ may be external to tube  28 ′ with a distal tip  27  that terminates within bore  29  of tube  28 ′ near distal tip  31  of tube  28 ′. Preferably, tube  30 ′ is angled at between 25° and 50° and terminates approximately 0.1 mm to 3.0 mm from distal tip  31 . Such an arrangement causes fluid exiting tube  28 ′ to reflect off of internal wall  33  of tube  28 ′ prior to exiting out of distal tip  31 , thereby reducing the intensity of the pressure pulse prior to contact with eye tissue. The intensity of the pressure pulse decays with distance from tip  31 ; consequently, efficiency is best for tissue that is held at or within tip  31 .  
         [0039]    As best seen in FIG. 5, tube  30  is free on the distal end and connected to pumping chamber  42  on the proximal end. Tube  30  and pumping chamber  42  may be sealed fluid tight by any suitable means having a relatively high melting point, such as silver solder. Fitting  44  holds tube  30  within bore  48  of aspiration horn  46 . Bore  48  communicates with fitting  20 , which is journaled into horn  46  and sealed with O-ring seal  50  to form an aspiration pathway through horn  46  and out fitting  20 . Horn  46  is held within body  12  by O-ring seal  56  to form irrigation tube  52  which communicates with irrigation tube  18  at port  54 .  
         [0040]    As best seen in FIG. 7, in a first embodiment of the present invention, pumping chamber  42  contains a relatively large pumping reservoir  43  that is sealed on both ends by electrodes  45  and  47 . Electrical power is supplied to electrodes  45  and  47  by insulated wires  49  and  51 , respectively. In use, surgical fluid (e.g. saline irrigating solution) enters reservoir  43  through port  55 , tube  34  and check valve  53 , check valves  53  being well-known in the art. Electrical current (preferably Radio Frequency Alternating Current or RFAC) is delivered to and across electrodes  45  and  47  because of the conductive nature of the surgical fluid. As the current flows through the surgical fluid, the surgical fluid boils. As the surgical fluid boils, it expands rapidly out of pumping chamber  42  through port  57  and into tube  30  (check valve  53  prevents the expanding fluid from entering tube  34 ). The expanding gas bubble pushes the surgical fluid in tube  30  downstream of pumping chamber  42  forward. Subsequent pulses of electrical current form sequential gas bubbles that move surgical fluid down tube  30 . The size and pressure of the fluid pulse obtained by pumping chamber  42  can be varied by varying the length, timing and/or power of the electrical pulse sent to electrodes  45  and  47  and by varying the dimensions of reservoir  43 . In addition, the surgical fluid may be preheated prior to entering pumping chamber  42 . Preheating the surgical fluid will decrease the power required by pumping chamber  42  and/or increase the speed at which pressure pulses can be generated.  
         [0041]    While several embodiments of the handpiece of the present invention are disclosed, any handpiece producing adequate pressure pulse force, rise time and frequency may also be used. For example, any suitable handpiece producing a pressure pulse force of between 0.03 grams and 20.0 grams, with a rise time of between 1 gram/sec. and 20,000 grams/sec. and a frequency of between 1 Hz and 200 Hz may be used, with between 20 Hz and 100 Hz being most preferred. The pressure pulse force and frequency will vary with the hardness of the material being removed. For example, the inventors have found that a lower frequency with a higher pulse force is most efficient at debulking and removing the relatively hard nuclear material, with a higher frequency and lower pulse force being useful in removing softer epinuclear and cortical material. Infusion pressure, aspiration flow rate and vacuum limit are similar to current phacoemulsification techniques.  
         [0042]    As best seen in FIG. 8, the fluid in reservoir  143  in pumping chamber  142  may also be heated by the use of heating element  145  that is internal to reservoir  143 . Heating element  145  may be, for example, a coil of 0.003 inch diameter stainless steel wire which is energized by power source  147 . The size and pressure of the fluid pulse obtained by pumping chamber  142  can be varied by varying the length and timing of the electrical pulse sent to element  145  by power source  147  and by varying the dimensions of reservoir  143 . The numbers in FIG. 8 are identical to the numbers in FIG. 7 except for the addition of “100” in FIG. 8.  
         [0043]    As best seen in FIGS. 3, 4 and  7 , surgical fluid may be supplied to pumping chamber  43  through tube  34  or, as seen in FIG. 9, surgical fluid may be supplied to pumping chamber  243  through irrigation fluid tube  234  which branches off main irrigation tube  235  supplying cool surgical fluid to the operative site. As seen in FIG. 9, aspiration tube  237  may be contained internally to handpiece  10 . The numbers in FIG. 9 are identical to the numbers in FIG. 7 except for the addition of “200” in FIG. 9.  
         [0044]    As best seen in FIGS. 11 and 12, in an alternative embodiment of the present invention, distal tip  327  of tube  330  terminates within bore  329  of tube  328  and may be made from an elastomeric covered spring  335  that may be flexed by use of pull wire  337  or other suitable method well-known in the art. For example, U.S. Pat. Nos. 4,921,482, 4,998,916, 5,037,391, 5,108,368, 5,203,772, 5,308,324, 5,372,587, 5,378,234 (all to Hammerslag, et al.) and 5,217,465 (Steppe), the entire contents of which being incorporated herein by reference, all disclose method of steering a flexible tube of similar construction as the present invention. As a result, the pressure pulse exiting tip  327  may be directed against internal wall  333  of tube  328  (as shown in FIG. 11) or directed out tip  331  (as shown in FIG. 12).  
         [0045]    As best seen in FIGS. 13 and 14, in yet another alternative embodiment of the present invention similar to the embodiment illustrated in FIGS. 11 and 12, tube  430  may be coaxial with tube  428  and contained within bore  429  of tube  428 . Distal tip  427  of tube  430  and distal tip  439  of tube  428  may be made from an elastomeric covered springs  435  and  441 , respectively that may be flexed by use of pull wires  437  and  443 , respectively. As a result, the pressure pulse exiting tip  427  may be directed against internal wall  433  of tube  428  (as shown in FIG. 14) or directed out tip  431  (as shown in FIG. 13) and tip  431  may be steered within the eye as required, as shown in FIG. 14. Alternativley, tube  430  may be attached to tube  428  so that tube  430  flexes with tube  428 , thereby eliminating the need for pull wire  437 . Tube  430  may have any fixed orientation desired with respect to tube  428 .  
         [0046]    In still another embodiment of the present invention, illustrated in FIGS. 15 and 16, distal tip  527  is slidably received on the end of the heated fluid injection tube (not shown), and may be extended out of tip  531 , as shown in FIG. 15, or retracted into tip  531 , as shown in FIG. 16. In the extended position, tip  527  directs the heated pressure pulses directly at the targeted tissue. In the retracted position, tip  527  directs the heated pressure pulses against internal wall  533  of tube  528 . Suitable methods for extending and retracting tip  527  include the pull wires illustrated in FIGS.  11 - 14  and  17 A- 18 B (not shown).  
         [0047]    As best seen in FIGS.  17 A- 18 B, in yet another embodiment of the present invention, tube  630  is contained within bore  629  of tube  628  so that tip  627  terminates internal to bore  629 . Deflector  660  attaches to tube  628  near tip  631  just outside tip  627  so that deflector  660  rotates about pivot pin  662  by the urging of control wire  664 . As seen in FIGS. 17A and 17B, pushing forward (toward tip  631 ) on wire  664  rotates deflector  660  clockwise about pin  662 , thereby rotating deflector  660  relatively clear of fluid exiting tip  627  of tube  630  and allowing the fluid to flow out of tip  627  relatively freely and contact directly the targeted tissue. Alternatively, the force of the pressure pulse may be used to rotate deflector  660  about pin  662 . As seen in FIGS.  18 A- 18 B, pulling on wire  664  (away from tip  631 ) causes deflector  660  to rotate counterclockwise about pin  662 , thereby partially deflecting fluid exiting tip  627  of tube  630  and directing the fluid against internal wall  633  of tube  628 .  
         [0048]    Any of a number of methods can be employed to limit the amount of heat introduced into the eye. For example, the pulse train duty cycle of the heated solution can be varied so that the total amount of heated solution introduced into the eye does not vary with the pulse frequency. Alternatively, the aspiration flow rate can be varied as a function of pulse frequency so that as pulse frequency increases aspiration flow rate increases proportionally.  
         [0049]    This description is given for purposes of illustration and explanation. It will be apparent to those skilled in the relevant art that changes and modifications may be made to the invention described above without departing from its scope or spirit. For example, it will be recognized by those skilled in the art that the present invention may be combined with ultrasonic and/or rotating cutting tips to enhance performance.