Abstract:
A surgical handpiece having two coaxial tubes or channels mounted within a body. The first tube is used for aspiration and is smaller in diameter than the second tube so as to create an annular passage between the first and second tube. The annular passage communicates with a pumping chamber formed between two electrodes. The pumping chamber works by boiling a small volume of the surgical fluid. As the fluid boils, it expands rapidly, thereby propelling the liquid downstream of the pumping chamber out of the annular passage. The distal end of the annular gap is sealed by sealing together the distal ends of the first and second tube and a plurality or orifices or ports may be formed near the seal. As the expanding gas is propelled down the annular gap, the gas/liquid stream is forced out of the distal orifices in a controlled and directed manner. The distal end of the first and second tubes may contain a bend.

Description:
This application is a continuation-in-part application of U.S. patent application Ser. No. 09/429,456, filed Oct. 28, 1999, which is a continuation-in-part application of U.S. patent application Ser. No. 09/090,433, filed Jun. 4, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to the field of cataract surgery and more particularly to a handpiece tip for practicing the liquefracture technique of cataract removal. 
     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. 
     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). 
     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. 
     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 tubes. Through the electric cable, the console varies the power level transmitted by the handpiece to the attached cutting tip and the flexible tubes supply irrigation fluid to and draw aspiration fluid from the eye through the handpiece assembly. 
     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. 
     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. 
     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 concurrently with the injection of the heated solution and the injection of a relatively cool 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 content 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 tubes 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 tube. 
     U.S. Pat. No. 5,885,243 (Capetan, et al.) discloses a handpiece having a separate pumping mechanism and resistive heating element. Such a structure adds unnecessary complexity to the handpiece. 
     Therefore, a need continues to exist for a simple surgical handpiece and tip that can heat internally the solution used to perform the liquefracture technique. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention improves upon the prior art by providing a surgical handpiece having two coaxially mounted tubes or channels mounted to a body. The first tube is used for aspiration and is smaller in diameter than the second tube so as to create an annular passage between the first and second tube. The annular gap communicates with a pumping chamber formed between two electrodes. The pumping chamber works by boiling a small volume of the surgical fluid. As the fluid boils, it expands rapidly, thereby propelling the liquid downstream of the pumping chamber out of the annular gap. The distal end of the annular gap is sealed by sealing together the distal ends of the first and second tube and a plurality or orifices or ports may be formed near the seal. As the expanding gas is propelled down the annular gap, the gas/liquid stream is forced out of the distal ports in a controlled and directed manner. The distal end of the first and second tubes may contain a bend. 
     Accordingly, one objective of the present invention is to provide a surgical handpiece having at least two coaxial tubes. 
     Another objective of the present invention is to provide a handpiece having a pumping chamber. 
     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. 
     Still another objective of the present invention is to provide a handpiece having a pumping chamber formed by two electrodes. 
     Yet another objective of the present invention is to provide a handpiece having two electrodes wherein the electrodes are insulated. 
     Still another objective of the present invention is to provide a handpiece that delivers fluid pulses in a controlled and directed manner. 
     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 
     FIG. 1 is a front, upper left perspective view of a first embodiment of the handpiece of the present invention. 
     FIG. 2 is a rear, upper right perspective view of a first embodiment of the handpiece of the present invention. 
     FIG. 3 is a cross-sectional view of a first embodiment of the handpiece of the present invention taken along a plane passing through the irrigation channel. 
     FIG. 4 is a cross-sectional view of a first embodiment of the handpiece of the present invention taken along a plane passing through the aspiration channel. 
     FIG. 5 is an enlarged partial cross-sectional view of a first embodiment of the handpiece of the present invention taken at circle  5  in FIG.  4 . 
     FIG. 6 is an enlarged partial cross-sectional view of a first embodiment of the handpiece of the present invention taken at circle  6  in FIG.  3 . 
     FIG. 7 is an enlarged cross-sectional view of a first embodiment of the handpiece of the present invention taken at circle  7  in FIGS. 3 and 4. 
     FIG. 8 is a partial cross-sectional view of a second embodiment of the handpiece of the present invention. 
     FIG. 9 is an enlarged partial cross-sectional view of the second embodiment of the handpiece of the present invention taken at circle  9  in FIG.  8 . 
     FIG. 10 is an enlarged partial cross-sectional view of the pumping chamber used in the second embodiment of the handpiece of the present invention taken at circle  10  in FIG.  9 . 
     FIG. 11 is a partial cross-sectional view of a third embodiment of the handpiece of the present invention. 
     FIG. 12 is an enlarged partial cross-sectional view of the distal end of the third embodiment of the handpiece of the present invention taken at circle  12  in FIG.  11 . 
     FIG. 13 is an enlarged partial cross-sectional view of the pumping chamber used in the third embodiment of the handpiece of the present invention shown in FIGS. 11 and 12. 
     FIG. 14 is a front perspective view of one embodiment of a distal tip that may be used with the handpiece of the present invention. 
     FIG. 15 is a front perspective view of a second embodiment of a distal tip that may be used with the handpiece of the present invention. 
     FIG. 16 is a front perspective view of a third embodiment of a distal tip that may be used with the handpiece of the present invention. 
     FIG. 17 is a front perspective view of a fourth embodiment of a distal tip that may be used with the handpiece of the present invention. 
     FIG. 18 is a front perspective view of a fifth embodiment of a distal tip that may be used with the handpiece of the present invention. 
     FIG. 19 is a longitudinal cross-sectional view of the tip illustrated in FIG.  18 . 
     FIG. 20A is a front perspective view of a sixth embodiment of a distal tip that may be used with the handpiece of the present invention operating at high pressure with a short coherence length. 
     FIG. 20B is a front perspective view of a sixth embodiment of a distal tip that may be used with the handpiece of the present invention operating at low pressure with a long coherence length. 
     FIG. 21A is a front perspective view of a seventh embodiment of a distal tip that may be used with the handpiece of the present invention. 
     FIG. 21B is a cross sectional view of the tip illustrated in FIG.  21 A. 
     FIG. 22 is a block diagram of a control system that can be used with the handpiece of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     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 , needle  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. Needle  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 tube to fit within needle  28 , for example 29 gauge hypodermic needle tubing. 
     As best seen in FIG. 5, tube  30  is free on the distal end and connected to boiling or 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 a silicone gasket, glass frit or 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 . 
     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, not shown. In use, surgical fluid (e.g. saline irrigating solution) enters reservoir  43  through 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 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. 
     As best seen in FIGS. 8-10, in a second embodiment of the present invention, handpiece  110  generally includes body  112 , having power supply cable  113 , irrigation/aspiration lines  115 , pumping chamber supply line  117 . Distal end  111  of handpiece  110  contains pumping chamber  142  having a reservoir  143  formed between electrodes  145  and  147 . Electrodes  145  and  147  are preferably made from aluminum, titanium, carbon or other similarly conductive materials and are electrically insulated from each other and body  112  by insulating layer  159  such as anodized layer  159  formed on electrodes  145  and  147 . Anodized layer  159  is less conductive than untreated aluminum and thus, acts as an electrical insulator. Electrodes  145  and  147  and electrical terminals  161  and  163  are not anodized and thus, are electrically conductive. Layer  159  may be formed by any suitable insulating or anodization technique, well-known in the art, and electrodes  145  and  147  and electrical terminals  161  and  163  may be masked during anodization or machined after anodization to expose bare aluminum. Electrical power is supplied to electrodes  145  and  147  through terminals  161  and  163  and wires  149  and  151 , respectively. Fluid is supplied to reservoir  143  through supply line  117  and check valve  153 . Extending distally from pumping chamber  142  is outer tube  165  that coaxially surrounds aspiration or inner tube  167 . Tubes  165  and  167  may be of similar construction as tube  30 . Tube  167  is of slightly smaller diameter than tube  165 , thereby forming an annular passage or gap  169  between tube  165  and tube  167 . Annular gap  169  fluidly communicates with reservoir  143 . 
     In use, surgical fluid enters reservoir  143  through supply line  117  and check valve  153 . Electrical current is delivered to and across electrodes  145  and  147  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  142  through annular gap  169 . The expanding gas bubble pushes forward the surgical fluid in annular gap  169  downstream of pumping chamber  142 . Subsequent pulses of electrical current form sequential gas bubbles that move or propel the surgical fluid down annular gap  169 . 
     One skilled in the art will recognize that the numbering in FIGS. 8-10 is identical to the numbering in FIGS. 1-7 except for the addition of “ 100 ” in FIGS. 8-10. 
     As best seen in FIGS. 11-13, in a third embodiment of the present invention, handpiece  210  generally includes body  212 , having power supply cable  213 , irrigation/aspiration lines  215 , pumping chamber supply line  217 . Distal end  211  of handpiece  210  contains pumping chamber  242  having a reservoir  243  formed between electrodes  245  and  247 . Electrodes  245  and  247  are preferably made from aluminum and electrically insulated from each other and body  212  by anodized layer  259  formed on electrodes  245  and  247 . Anodized layer  259  is less conductive than untreated aluminum and thus, acts as an electrical insulator. Electrodes  245  and  247  and electrical terminals  261  and  263  are not anodized and thus, are electrically conductive. Layer  259  may be formed by any suitable anodization technique, well-known in the art, and electrodes  245  and  247  and electrical terminals  261  and  263  may be masked during anodization or machined after anodization to expose bare aluminum. Electrical power is supplied to electrodes  245  and  247  through terminals  261  and  263  and wires  249  and  251 , respectively. Fluid is supplied to reservoir  243  though supply line  217  and check valve  253 . Extending distally from pumping chamber  242  is outer tube  265  that coaxially surrounds aspiration or inner tube  267 . Tubes  265  and  267  may be of similar construction as tube  30 . Tube  267  is of slightly smaller diameter than tube  265 , thereby forming an annular passage or gap  269  between tube  265  and tube  267 . Annular gap  269  fluidly communicates with reservoir  243 . 
     In use, surgical fluid enters reservoir  243  through supply line  217  and check valve  253 . Electrical current is delivered to and across electrodes  245  and  247  because of the conductive nature of the surgical fluid. As the current flows through the surgical fluid, the surgical fluid boils. The current flow progresses from the smaller electrode gap section to the larger electrode gap section, i.e., from the region of lowest electrical resistance to the region of higher electrical resistance. The boiling wavefront also progresses from the smaller to the larger end of electrode  247 . As the surgical fluid boils, it expands rapidly out of pumping chamber  242  through annular gap  269 . The expanding gas bubble pushes forward the surgical fluid in annular gap  269  downstream of pumping chamber  242 . Subsequent pulses of electrical current form sequential gas bubbles that move or propel the surgical fluid down annular gap  269 . 
     One skilled in the art will recognize that the numbering in FIGS. 11-13 is identical to the numbering in FIGS. 1-7 except for the addition of “ 200 ” in FIGS. 11-13. 
     As best seen in FIGS. 14-21, a variety of different distal tips may be used with the handpiece of the present invention. For example, as illustrated in FIGS. 14-16, tip  600  may contain distal end  602  having a plurality of discharge orifices  604 . Orifices  604  may be arranged in a divergent pattern, as illustrated in FIG. 14, a convergent pattern, as illustrated in FIG. 15, or in a non-converging, near miss pattern, as illustrated in FIG. 16, depending upon the targeted tissue and the desired surgical outcome. The converging streams create a high pressure region where the streams meet, producing a zone of maximum liquefracture. The diverging streams exhibits maximum average pressure directly in front of tip  600 , making that the most efficient liquefracture zone in that region. The near miss streams create a region of high shear between the streams, which can contribute to shear fracture of the material in the proximity of tip  600 . One skilled in the art will recognize that orifices  604  may be arranged so as to create the designed pattern external to tip  600  or internal to bore  611 . Distal end  602  may be formed, for example by crimping the ends of tubes  165  and  167 , or  265  and  267 , respectively (as illustrated in FIGS. 19 and 20) so that annular gap  169  or  269  is in fluid communication with orifices  604 . One skilled in the art will recognize that tip  600  may be formed as a separate piece and press fit or otherwise attached to tubes  165  and  167  or  265  and  267  so that tips  600  may be interchangeable. For example, different tip  600  designs may be desired during different portions of a surgical procedure. 
     Alternatively, as illustrated in FIG. 17, tip  600 ′ may be closed on distal end  602 ′ so that discharge orifices  604 ′ project fluid to the targeted tissue, but tip  600 ′ performs no aspiration function. 
     As seen in FIGS. 18 and 19, distal end  602 ″ of tip  600 ″, in addition to discharge orifices  604 ″ projecting forward and outward discharge streams  611 , may contain orifice or orifices  606  that discharge a fluid stream  610  rearward into aspiration bore  608 . Stream  610  helps to assure that bore  608  does not become occluded at end  602 ″. 
     As best seen in FIGS. 21A and 21B, distal end  802  of tip  800  may contain bend  812 , bend  812  being at an angle of between 0° and approximately 90° with between 0° and approximately 60° being preferred and between 0° and approximately 20° being most preferred. Such a bend in distal end  802  allows tip  800  to access different areas within the capsular bag more easily. As discussed above, orifice  804  may be arranged to direct stream  810  internal to bore  808 . 
     While several embodiments of the handpiece of the present invention are disclosed any handpiece producing adequate pressure pulse force, temperature, rise time and frequency may also be used. For example, any handpiece producing a pressure pulse force of between 0.02 grams and 20.0 grams, with a rise time of between 1 gram/second and 20,000 grams/second and a frequency of between 1 Hz and 200 Hz may be used, with between 10 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. 
     As seen in FIGS. 20A and 20B, the inventors have determined that the coherence length of the fluid stream is affected by many factors, including the properties of the fluid, ambient conditions, orifice geometry, flow regime at the orifice and pressure of the fluid. By varying the operating parameters of the system (e.g., pressure, temperature, flow development), the coherence length of the fluid pulse stream can be varied. Tip  700  contains orifice  704  internal to bore  708 . When operated at relatively high pressures, as shown in FIG. 20A, the coherence length of discharge stream  711  is relatively short, degrading internal to bore  708  around distal end  702 . As seen in FIG. 20B, when operated at relatively low pressures, the coherence length of discharge stream  711  is relatively long, degrading external to bore  708 , past distal end  702 . For example, a pressure stream having a coherence length of approximately between −1.0 millimeters and +5.0 millimeters from distal end  702  is suitable for use in ophthalmic surgery. 
     As seen in FIG. 22, one embodiment of control system  300  for use in operating handpiece  310  includes control module  347 , power gain RF amplifier  312  and function generator  314 . Power is supplied to RF amplifier  312  by DC power supply  316 , which preferably is an isolated DC power supply operating at several hundred volts, but typically +200 volts. Control module  347  may be any suitable microprocessor, micro controller, computer or digital logic controller and may receive input from operator input device  318 . Function generator  314  provides the electric wave form in kilohertz to amplifier  312  and typically operates at around 450 kHz or above to help minimize corrosion. 
     In use, control module  347  receives input from surgical console  320 . Console  320  may be any commercially available surgical control console such as the LEGACY® SERIES TWENTY THOUSAND® surgical system available from Alcon Laboratories, Inc., Fort Worth, Tex. Console  320  is connected to handpiece  310  through irrigation line  322  and aspiration line  324 , and the flow through lines  322  and  324  is controlled by the user via footswitch  326 . Irrigation and aspiration flow rate information in handpiece  310  is provided to control module  347  by console  320  via interface  328 , which may be connected to the ultrasound handpiece control port on console  320  or to any other output port. Control module  347  uses footswitch  326  information provided by console  320  and operator input from input device  318  to generate two control signals  330  and  332 . Signal  332  is used to operate pinch valve  334 , which controls the surgical fluid flowing from fluid source  336  to handpiece  310 . Fluid from fluid source  336  is heated in the manner described herein. Signal  330  is used to control function generator  314 . Based on signal  330 , function generator  314  provides a wave form at the operator selected frequency and amplitude determined by the position of footswitch  326  to RF amplifier  312  which is amplified to advance the powered wave form output to handpiece  310  to create heated, pressurized pulses of surgical fluid. 
     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 as a function of the pulse frequency 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. 
     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.