Patent Description:
Needles that are actuated at ultrasonic frequencies may be used in various contemporary eye surgical procedures. For example, the lens of a human eye may develop a cataractous condition that affects a patient's vision. Cataractous lenses are sometimes removed and replaced in a procedure commonly referred to as phacoemulsification. Phacoemulsification procedures are typically performed with a handpiece that actuates a needle at ultrasonic frequencies. The needle is inserted through an incision in the cornea up to a desired insertion depth, and then ultrasonic actuation at one specific frequency is used to break the lens within the lens capsule of the eye. The broken lens may be removed through an aspiration line that is coupled to the handpiece, drawing irrigation fluid and aspirated tissue from a hollow passage through the needle. It is to improvements in ultrasonic actuation of a phacoemulsification needle that embodiments of the present invention are generally directed.

<CIT> discloses a phacoemulsification surgical instrument which includes a handpiece that includes a piezoelectric transducer, and a hollow titanium needle having a substantially cylindrical portion and a free distal tip attached to the handpiece by way of a threaded supported end structure. The piezoelectric transducer is driven by a circuit to periodically expand and contract at a high-ultrasound frequency that rings the hollow titanium needle with a high-ultrasound frequency standing wave having a node of minimum amplitude residing in the substantially cylindrical portion between the supported end structure and the free distal tip, and to periodically expand and contract at an ultrasound frequency that rings the hollow titanium needle with an ultrasonic frequency standing wave, the circuit adapted to between the high-ultrasonic frequency and the ultrasonic frequency.

The present invention is directed to a phacoemulsification arrangement as recited in claim <NUM>. The arrangement can switch between equal to or above <NUM> and below <NUM>. The two frequencies produce different surgical effects when used to emulsify a cataractous lens. Optional features are recited in the dependent claims.

The needle may comprise a hollow needle and the transducer may comprise a piezoelectric crystal transducer. The dual frequency producing circuit may be electrically connected to the piezoelectric crystal transducer by way of wires. The low-frequency oscillator is configured to drive the piezoelectric crystal transducer to periodically vibrate the hollow needle at a low frequency defined as being less than <NUM>, preferably without producing a node of minimum amplitude along the hollow needle. The high-frequency voltage pathway may be electrically tuned with the physical high natural frequency of the handpiece (and possibly the needle) and the low-frequency voltage pathway may be electrically tuned with the physical low natural frequency of the handpiece (and possibly the needle).

Initially, this disclosure is by way of example only, not by limitation. Thus, although the instrumentalities described herein are for the convenience of explanation it will be appreciated that the principles herein may be applied equally in other similar configurations involving eye surgery. If the specification states a component or feature "may", "can", "could", or "might" be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic. As used herein, the terms "having", "have", "including" and "include" are considered open language and are synonymous with the term "comprising". In what follows, similar or identical structures may be identified using identical callouts.

Described herein are phacoemulsification devices configured to ultrasonically vibrate a phacoemulsification needle to advantageously fragment and emulsify a cataractous lens of a human eye. Generally speaking, described below is a surgical instrument is directed to phacoemulsification for cataract eye surgery. The instrument generally includes a dual frequency voltage producing circuit comprising a low-frequency voltage pathway with a low-frequency LC Network and a high-frequency voltage pathway with a high-frequency LC network. A phacoemulsification needle extends from a handpiece able to be driven by a piezoelectric crystal transducer. The piezoelectric crystal transducer is electrically connected to the dual frequency voltage producing circuit. The high-frequency voltage pathway is electrically tuned with the physical high natural frequency of the handpiece and the low-frequency voltage pathway is electrically tuned with the physical low natural frequency of the handpiece for efficient transfer of energy to the phaco needle.

<FIG> is a cross-section view line drawing of a phacoemulsification device inserted in an eye. As depicted, the phacoemulsification device <NUM> generally comprises a handpiece <NUM>, an aspiration needle <NUM> that extends from the handpiece <NUM>, an irrigation sleeve <NUM> that concentrically surrounds a portion of the aspiration needle <NUM> (also known as a phacoemulsification needle or needle), and at least one irrigation port <NUM> extending through the irrigation sleeve <NUM>.

During an ultrasonic phacoemulsification surgical procedure, a cataractous lens may be broken into particles by the combined cavitation effects and cutting action of the ultrasonically vibrating free distal tip <NUM> of needle <NUM>. The vibration improves penetrating the needle <NUM> into lens tissue, while the cavitation of surrounding ocular liquid/fluid helps to emulsify or otherwise disintegrate lens tissue into small particles that can be aspirated through a narrow tube <NUM> (also known as an aspiration passageway) in the needle <NUM>. Cavitation occurs because of rapid compression and expansion along the longitudinal axis of the phacoemulsification needle <NUM> at or near the free distal tip <NUM> thereby generating longitudinal waves in the surrounding ocular fluid. Unlike torsional and shear waves, longitudinal waves propagate well in fluids.

A back cylinder <NUM> and a front cylinder <NUM> define the handpiece <NUM>. A pair of piezoelectric crystals <NUM> and <NUM> (together <NUM>) are sandwiched between a front rear cylinder portion 124B and a back rear cylinder portion 124A that collectively make up the rear cylinder <NUM>. The pair of piezoelectric crystals <NUM> and <NUM> are connected through a central bolt (not shown). The piezoelectric transducer <NUM>/<NUM> may be identified as including the rear cylinder <NUM> and the piezoelectric crystals <NUM>. As shown, the needle <NUM> is attached to the handpiece <NUM> at the supported end <NUM> via a supported end structure <NUM> that includes external threads that mate with internal threads in the handpiece <NUM>. The needle <NUM> possesses a substantially cylindrical portion between the supported end structure <NUM> and the free distal tip <NUM>. Substantially cylindrical defined herein is that the needle <NUM> may not be a perfect cylinder, but rather may be something between a cylinder to a slight taper (such a taper under <NUM>%, for example) with the diameter of the needle <NUM> at the supported end structure <NUM> being larger than at the needle free distal tip <NUM>. Moreover, the needle <NUM> may not be perfectly circular. The needle <NUM> may be titanium or any other suitable material known in the art. The needle <NUM> comprises an aspiration passageway <NUM> that aligns with a handpiece aspiration passageway <NUM> forming a contiguous aspiration passageway <NUM>. As ocular fluid and broken up cataract <NUM> are sucked through the aspiration passageway <NUM>, replacement fluid <NUM> is transported along an infusion/irrigation pathway <NUM> and infused in the eye <NUM> via the irrigation ports <NUM> to prevent the eye <NUM> from collapsing.

One handpiece <NUM> envisions the back cylinder <NUM> possessing an outer diameter that is in a range between <NUM> and <NUM>. In some configurations, the front and rear back cylinder portions 124B and 124A are (more or less) comprised of stainless steel, but could just as easily be comprised of another suitable material, e.g., titanium, known to those skilled in the art. The handpiece <NUM> may also optionally include a front cylinder <NUM> that may have a front cylinder outer diameter that is preferably in the range <NUM> to <NUM>. In this case, the piezoelectric transducer <NUM>/<NUM> is preferably disposed between the rear back cylinder portion 124A and the front cylinder <NUM>.

With reference to <FIG> in conjunction with <FIG>, a block diagram of a phacoemulsification system <NUM> is presented. As shown, the phacoemulsification system <NUM> includes an infusion bottle <NUM> filled with balanced salt solution (irrigation fluid) <NUM> that is generally positioned between <NUM> to <NUM> above the eye <NUM>, or to a level that gravitationally provides balanced intraocular pressure (IOP) in the eye <NUM>. A pressurized fluid source may be employed in addition to or in the alternative to infusion bottle <NUM>. IOP is generally between <NUM> Hg and <NUM> Hg and averages to <NUM> Hg in a human eye. During a cataract surgery, a surgeon tries to keep the IOP above <NUM> Hg, especially after a vacuum surge. Osmotically balanced salt solution is compatible with the ocular fluid in the eye <NUM>. The system <NUM> further comprises a pinch valve <NUM> that opens and closes an infusion/irrigation pathway <NUM> to the eye <NUM>. An aspiration pump <NUM> sucks or otherwise pulls emulsified lens/ocular material <NUM> from the eye <NUM> through the hollow opening in the free distal tip <NUM> of needle <NUM>. During a phacoemulsification procedure, the aspiration needle <NUM> is inserted through an incision 101in the anterior chamber of the eye <NUM> (at the cornea) up to and including the irrigation port <NUM>. The needle <NUM> may be vibrated at either an ultrasonic frequency or at a high ultrasonic frequency to break up (emulsify) lens material in the eye <NUM>. Ultrasonic frequency as described herein is defined as a frequency below <NUM>, and high ultrasonic frequency is defined herein as a frequency equal to or above <NUM>. The small pieces of the emulsified lens material/an ocular fluid <NUM> are sucked through the needle <NUM> away from the eye <NUM> along the aspiration passageway <NUM> by way of a vacuum generated by the aspiration pump <NUM>. The aspiration pump <NUM> is configured to pull (vacuum) a specific volume of emulsified lens material at a particular rate from the eye <NUM>. Generally, the aspiration rate is approximately <NUM> to <NUM> cc of fluid/minute. Irrigation fluid <NUM> replaces the removed lens material (at the same particular rate of aspirated lens material) by way of gravity from the infusion bottle <NUM> that is raised at an appropriate distance above the eye <NUM> to maintain IOP. The irrigation fluid <NUM> flows and is discharged into the inside of the eye <NUM> through the irrigation port(s) <NUM> while the irrigation ports are located inside of the eye <NUM>. In other words, the irrigation fluid <NUM> replaces the aspirated lens and ocular material <NUM> at the same rate at which the lens and ocular material <NUM> is removed from the eye <NUM> to maintain appropriate IOP, thus avoiding collapse of the anterior chamber of the eye <NUM>. Hence, the irrigation flow rate into the eye <NUM> essentially equals the aspiration flow rate from the eye <NUM>. The word essentially is used here to indicate that at some level, the flow rate is not exactly equal, but for all intents and purposes the two flow rates are more or less equal. The irrigation port <NUM> is an aperture or pathway into the irrigation sleeve <NUM>, whereby irrigation fluid <NUM> passes from inside of the irrigation sleeve <NUM> out through the irrigation port <NUM> and into the eye <NUM>. The irrigation sleeve <NUM> is spaced apart from the needle <NUM> thereby forming an irrigation pathway <NUM> over the needle <NUM>, as shown. The irrigation pathway <NUM> extends from the infusion bottle <NUM>, through the handpiece <NUM> to the irrigation port <NUM>.

The effectiveness of a surgical instrument for phacoemulsification depends on the rate at which tissue is removed, which may be substantially affected by cavitation since cavitation may reduce partial or total occlusions of the needle <NUM>. On the other hand, cavitation can cause a larger particle that is not readily sucked up through the free distal tip <NUM> to be pushed/chased away from the vibrating needle <NUM>. Likewise, a larger particle may not sufficiently disintegrate to be aspirated away and simply shake off of the free distal tip <NUM> and get pushed/chased away from the vibrating needle <NUM>. Either way, the surgeon may lose the particle and have to spend time maneuvering around the eye <NUM> to reengage the particle in order to suck it away. Hence, it is desirable to retain tissue particles once engaged with the needle <NUM>. This is referred to as "followability. " Followability is generally controlled and even enhanced by reducing cavitation during phacoemulsification.

One way to reduce cavitation is to excite the needle <NUM> to vibrate torsionally rather than longitudinally, so that the free distal tip <NUM> alternately rotates clockwise and counter-clockwise in relation to its longitudinal axis. Torsional vibrations do not readily propagate as waves in fluid, so that cavitation effects are substantially reduced. However, a free distal tip <NUM> that is vibrating purely torsionally may too easily core into the eye's lens material without sufficient disintegration of tissue into particles, which consequently, may disadvantageously lead to total occlusions in the needle <NUM>.

Followability may be enhanced by longitudinally ringing needle <NUM> at a carefully selected and substantially higher frequency than has been used previously for phacoemulsification. The ringing frequency may be chosen so that the phacoemulsification needle length corresponds to an approximately three-quarter vibration wavelength. Such a higher ultrasonic frequency, in combination with the proper length of the needle <NUM>, leads to reduced heating of tissue at the incision <NUM> in the cornea. This is considered a 'cold needle' herein and will generate a larger quantity of smaller sized cavitation bubbles per unit volume. The energy delivered by a cavitation bubble is related to the bubble radius, which is inversely related to the frequency of vibration. Hence, a higher ultrasonic frequency generates smaller cavitation bubbles than a lower ultrasonic frequency. For example, a bubble generated by a <NUM> wave may be approximately <NUM> in diameter, yet at <NUM> a bubble size may have a diameter of approximately <NUM>. When a greater quantity of smaller bubbles is generated, cavitation patterns are more uniformly distributed over the cutting area as compared with fewer larger bubbles. One of the results is enhanced followability compared with a phacoemulsification needle operating at conventional longitudinal ultrasonic vibrations.

<FIG> is a line drawing of an ultrasonic frequency response plot aligned with a handpiece and needle <NUM> (the phacoemulsification assembly). As shown, this is a vibration amplitude standing wave plot in relation to (along) the length of a handpiece <NUM> and needle <NUM> wherein the handpiece is generating longitudinal vibrations operating at an (low) ultrasonic frequency below <NUM>. Consistent with <FIG>, the handpiece <NUM> includes a back cylinder <NUM> and a front cylinder <NUM> comprising a pair of piezoelectric crystals <NUM> sandwiched via a central bolt (not shown). Four or six piezoelectric crystals or more are contemplated. A control feedback circuit <NUM> (shown in detail in <FIG>) connects to the piezoelectric transducer <NUM>/<NUM> to provide an oscillating voltage that drives the piezoelectric crystals <NUM> and <NUM>. The wavelength λ of a longitudinally ringing phacoemulsification device is defined by λ=c/f, where c is the speed of sound through the structure's material and f is the frequency of operation. The speed of sound in titanium material is approximately <NUM>,<NUM>,<NUM>/sec. Accordingly, the needle <NUM> longitudinally vibrating at a frequency of <NUM> (<NUM>) has a wavelength of (<NUM>,<NUM>,<NUM>/s) / (<NUM>,<NUM>) = <NUM>.

In <FIG>, the combined length of the front cylinder <NUM> and the back cylinder <NUM> is approximately ½ the wavelength during conventional ultrasonic operation, with a node of zero vibration amplitude at a location <NUM> at the interface between the two piezoelectric crystals <NUM>, <NUM>. For that reason, the handpiece <NUM> may be referred to as a "half-wavelength horn.

<FIG> is a block diagram of a control feedback circuit <NUM> that provides an oscillating voltage to the piezoelectric transducer <NUM>/<NUM>. As generally shown, a high frequency generator <NUM> provides high ultrasonic frequency voltage input to the piezoelectric transducer <NUM>/<NUM> in the handpiece <NUM> and a low frequency generator <NUM> provides a low (or regular) ultrasonic frequency voltage input to the piezoelectric transducer <NUM>/<NUM> in the handpiece <NUM>. A switch <NUM> directs either the high or low ultrasonic frequency voltage to the power amplifier <NUM> and a transformer <NUM>. More specifically, a computer controller <NUM> sends signals to modulate input from either the high frequency generator <NUM> or the low frequency generator <NUM>, wherein that signal (from one of the generators <NUM>, <NUM>) passes through the switch <NUM>. The switch <NUM> selected voltage is amplified by the power amplifier <NUM> and then translated to the two piezoelectric crystals <NUM>, <NUM> via the transformer <NUM> to drive the needle <NUM> with the selected frequency wave. The transformer <NUM> is arranged to detect slight impedance changes, or resonance mismatches, between the piezoelectric transducer <NUM>/<NUM> and the circuit <NUM>. Those impedance changes are communicated to the high frequency generator <NUM> and low frequency generator <NUM> along the tuning feedback loops 384A and 384B, respectively. Accordingly, the frequencies generated by the high frequency generator <NUM> and/or the low frequency generator <NUM> are adjusted to more closely match the resonance of the handpiece <NUM>. Also, feedback from the transformer <NUM> along control feedback <NUM> facilitates switching between the signals produced by the high frequency generator <NUM> or the low frequency generator <NUM> via the computer controller <NUM>. The computer controller <NUM> may blend the high frequency and low frequency signals in a desired proportion. In this way, by sensing increased loading to the system, e.g., an engaged particle occluding the free distal tip <NUM> of needle <NUM>, the computer controller <NUM> can be made to toggle the switch <NUM> (or vice versa if the particle is no longer engaged with the needle <NUM>) via a controlling algorithm, for example.

The phacoemulsification assembly <NUM> of <FIG> is not drawn to scale, so that the needle <NUM> may be more clearly depicted as a hollow cylinder. The needle <NUM> is attached to the handpiece <NUM> using supported end structure <NUM> having threads, however other attachment options known to those skilled in the art can be readily employed. One assembly contemplates the length of the needle <NUM> having a small cross-sectional area with a length that is less than a ¼ wavelength (<NUM> at <NUM>), for example <NUM>. The mass of the needle <NUM> is also small when compared with the mass of the handpiece <NUM>. Consequently, the needle <NUM> does not dramatically change the dynamic resonance characteristics of the handpiece <NUM>. As discussed previously, the needle <NUM> includes a narrow tubular passage <NUM> there through. The tubular passage <NUM> contiguously connects to the handpiece aspiration passageway <NUM> forming the uninterrupted aspiration passageway <NUM> so that fluid and tissue can be aspirated through the needle <NUM> to aspiration tubing (not shown) that is connected to the handpiece <NUM>. The aspiration tubing is linked to a pump <NUM> that provides sub-ambient pressure to the aspiration passageway <NUM> in the handpiece <NUM> to suck/aspirate lens and ocular material <NUM> from the eye <NUM>.

The cross-sectional area of the front cylinder <NUM> of the handpiece <NUM> is smaller than the cross section area of the back cylinder <NUM>, in order to generate the displacement magnification as shown by the standing wave plot <NUM> above the phacoemulsification device, as shown in <FIG>. Specifically, the displacement at the rightmost extent <NUM> of the front cylinder (step horn) <NUM> may be approximately <NUM> times the displacement at the leftmost edge (proximal handle end <NUM>) of the rear cylinder <NUM> and the front cylinder (step horn)/rear cylinder interface <NUM>. Note that the vertical axis <NUM> of the graph <NUM> represents displacement amplitude (longitudinal compression and expansion increasing upwards). The horizontal axis <NUM> of the graph <NUM> represents the longitudinal coordinate along the length of the handpiece <NUM> and needle <NUM>. Longitudinal strain in the needle <NUM> marginally increases the displacement in the vertical direction as plotted in the vibration response <NUM>, though the entire needle <NUM> longitudinally translates the vibration in the horizontal direction. In this example, the displacement at the location <NUM> of the free distal end <NUM> of the needle <NUM> is somewhat greater than the displacement at the rightmost extent <NUM> of the front cylinder <NUM>. Note that there is no location of zero vibration (i.e. nodal point) along the length of the needle <NUM>.

One assembly contemplates the needle <NUM> being substantially cylindrical, with an outer diameter in the range <NUM> to <NUM> and a length in the range <NUM> to <NUM>, the length being defined along a longitudinal axis of the needle <NUM> (i.e. parallel to graph axis <NUM>). In this context "cylindrical" does not necessarily mean cylindrical with a circular or annular cross section. Rather, any closed hollow extruded shape may be used (e.g. a closed hollow square cross-section). However, an annular cross-section having circular inner and outer peripheries may be preferred for manufacturability.

<FIG> is a line drawing of a high ultrasonic frequency response (standing wave) plot aligned with a handpiece and needle <NUM>. <FIG> depicts the phacoemulsification assembly <NUM> of <FIG> whereby the handpiece <NUM> is ringing the needle <NUM> at a high ultrasonic frequency, equal to or above <NUM>. As previously described, the handpiece <NUM> includes a piezoelectric transducer <NUM>/<NUM>, wherein the piezoelectric transducer <NUM>/<NUM> comprises a sandwich structure of two piezoelectric elements <NUM>, <NUM>, which meet at an interface location <NUM> in-between the front and rear back cylinder portions 124B and 124A. The piezoelectric crystals <NUM>, <NUM> may comprise piezoelectric ceramics or crystals, preloaded to be in compression by a bolt in tension, for example.

The front cylinder <NUM> may also be substantially made out of titanium, for example, to match the speed of sound of the titanium needle <NUM> and thereby reduce acoustic reflections at the interface between the front cylinder <NUM> and the needle <NUM>.

The surgical instrument depicted in <FIG> includes the circuit <NUM> that controls an oscillating voltage to the piezoelectric transducer <NUM>/<NUM> in the handpiece <NUM>. The voltage oscillating at a driving frequency that rings the needle <NUM> at different ultrasonic frequencies with corresponding standing waves characterized by longitudinal expansion and longitudinal contraction. The high frequency (generated from the high frequency generator <NUM>) with which the control feedback circuit <NUM> drives the piezoelectric transducer <NUM>/<NUM> is preferably in a range above <NUM>. Optional assemblies envision the high frequency being above <NUM> and the low frequency (generated by the low frequency generator <NUM>) being below <NUM>. For example, in this embodiment, the total length of the needle <NUM> may be approximately <NUM>, and the driving frequency may optionally be equal to or above <NUM>. Higher frequencies may introduce additional nodal waves along the length of the titanium needle <NUM>.

Such dimensional ranges and driving frequencies may advantageously result in ¾ wavelengths of the longitudinal standing wave lying along the needle <NUM>, such as if it is a titanium needle of <NUM> total length, for example. This can be verified by referring again to the formula λ=c/f. Specifically, according to this formula the wavelength of the standing longitudinal wave in a titanium needle in this configuration is (<NUM>,<NUM>,<NUM>/s) / <NUM>,<NUM>) = <NUM>. Hence, the ¾ wavelength would proportionally lie along a needle having a length of <NUM>.

An example of the amplitude of the longitudinal expansion and contraction causing displacement along the handpiece <NUM> and the needle <NUM> is plotted with a standing wave <NUM> versus longitudinal position in the graph <NUM> that is aligned above the handpiece <NUM> in <FIG>. The vertical axis <NUM> of the graph <NUM> represents displacement amplitude (increasing upwards). The displacement amplitude in the graph <NUM> is dimensionless. The horizontal axis <NUM> of the graph <NUM> represents the longitudinal coordinate along the length of the handpiece <NUM> and the needle <NUM>.

In <FIG>, the standing wave plot <NUM> shown in graph <NUM> preferably has a distal node of minimum amplitude at a node location <NUM> on the substantially cylindrical needle <NUM> between the free distal tip <NUM> and the supported end <NUM>. This is depicted on the standing wave plot <NUM> as a minimum point at the node location <NUM>. Unlike ultrasonic vibrations in a range under <NUM> (e.g. like that shown in <FIG>), the portion of the needle <NUM> that is most likely to contact the incision <NUM> in the cornea, will be in a corneal contact region <NUM>. The corneal contact region <NUM> includes a minimum node <NUM> in the standing vibration wave <NUM>, which exhibits significantly lower motion than does the free distal tip <NUM> (i.e., this is a 'cold needle' region <NUM>). The 'cold needle' region <NUM> may advantageously reduce heating of the tissue at and near the incision <NUM> (of <FIG>) in the cornea when this 'cold needle' region <NUM> of the needle <NUM> interfaces the incision <NUM>.

With continued reference to <FIG>, the standing wave plot <NUM> has a proximal node of minimum amplitude <NUM> near or adjacent the supported end <NUM>. This is depicted as a minimum point on the standing wave plot <NUM>, just to the left of line <NUM>, which corresponds to the supported end <NUM> of front cylinder <NUM>. Note that the proximal node of minimum amplitude <NUM> is not the same as the distal node of minimum amplitude at node location <NUM>, and of course does not serve as a 'cold needle' region <NUM>. Here, the standing wave <NUM> may have a distal anti-node <NUM> of maximum amplitude at or near the free distal tip <NUM> thereby enhancing tissue penetration by the free distal tip <NUM>. The constant thickness of the needle <NUM> responds with a vibration peak essentially equal for anti-nodes <NUM> and <NUM>.

Other nodes (e.g. node <NUM>) may exist in the displacement amplitude graph along the front cylinder <NUM>, but these are not the same as the distal node at node location <NUM>, nor do they serve the same purposes as described for the distal node at node location <NUM>. Another anti-node <NUM> may exist in the substantially cylindrical portion of the needle <NUM>, but it does not serve the same purpose as does the distal anti-node <NUM> of maximum amplitude at the free distal tip <NUM>. However, the existence and location of the anti-node <NUM> is an expected consequence of the desired placement of the distal node of minimum amplitude <NUM>. Other anti-nodes (e.g. anti-nodes <NUM>, <NUM>) may exist in the displacement amplitude graph along the front cylinder <NUM>, but these are not the same as the distal anti-node <NUM> of maximum amplitude at the free distal tip <NUM>, nor do they serve the same purpose as does the distal anti-node <NUM> of maximum amplitude at the free distal tip <NUM>.

Certain assemblies contemplate switching the applied vibration frequency to the needle <NUM> between ultrasonic frequency and high ultrasonic frequency. As previously discussed, at high ultrasonic frequency there is a node of minimum amplitude <NUM> along the substantially cylindrical portion of the needle <NUM> between the distal free end <NUM> and the supported end <NUM> whereby near or at the distal node of minimum amplitude <NUM> there is little to no heat generated. As previously discussed, this is considered a 'cold needle'. Also as previously discussed, the control feedback circuit <NUM> is configured to modulate, or change, the frequency between the ultrasonic frequency and high ultrasonic frequency.

Certain assemblies contemplate a routine (either in hardware or in software) that causes the control feedback circuit <NUM> to modulate frequencies driving the needle <NUM> between the ultrasonic frequency and high ultrasonic frequency after a predetermined time interval. One assembly envisions the frequency modulating between ultrasonic frequency and high ultrasonic frequency over a predetermined amount of time that is symmetrical or otherwise equal for high and low ultrasonic frequencies. For example, after every <NUM> seconds (or some other amount of time) the control feedback circuit <NUM> drives the hollow titanium needle <NUM> from the ultrasonic frequency to the high ultrasonic frequency and then back again. Yet another example includes causing the control feedback circuit <NUM> to change from ultrasonic to high ultrasonic in an asymmetric amount of time, such as for example, <NUM> seconds (or some other amount of time) at ultrasonic frequency then <NUM> seconds (or some other amount of time) at high ultrasonic frequency and then repeat. The predetermined amount of time is envisioned to be set either manually by someone in the operating room or default routines set by the manufacturer, just to name a couple of examples of how to set the time at each frequency. The software that controls the different frequencies can be executed via the computer controller <NUM> or equivalent computing device. Other assemblies contemplate manual intervention to modulate frequencies driving the needle <NUM> between the ultrasonic frequency and high ultrasonic frequency. One assembly envisions a foot pedal or other manually operated switching device (or potentiometer) modulating the frequency between ultrasonic frequency and high ultrasonic frequency.

Yet other assemblies contemplate managing an event during a phacoemulsification procedure that advantageously utilizes driving the needle <NUM> to modulate or otherwise shift between the ultrasonic and high ultrasonic frequency. For example, and with reference to <FIG>, depicted is a particle <NUM>, such as lens material, that is occluding the aspiration passageway <NUM> at the free distal tip <NUM> of the hollow titanium needle <NUM>. When a particle <NUM> is engaged in such a way, it can decrease flow rate in an aspiration passageway <NUM>. For example, with a peristaltic pump, the aspiration flow rate is always constant. The pump automatically increases vacuum to overcome an increased resistance to aspiration flow. If the occluded aspiration passageway <NUM> (such as from the particle <NUM>) is not cleared by the pump's maximum vacuum/effort, the aspiration flow could drop to zero. In general, the aspiration flow rate is either constant or zero. With a Venturi type pump, the aspiration flow rate decreases or increases as a function of pipe resistance, which can be caused by an occlusion (such as from the particle <NUM>). In either situation, the irrigation flow along pathway <NUM> is reduced or drops to zero to match the pump flow rate in order to maintain proper IOP. A reduction or stoppage of irrigation fluid <NUM> can cause localized heating at the cornea. In this situation, increasing the frequency of the needle <NUM> from ultrasonic to high ultrasonic can reduce localized heating at the incision site <NUM> (of <FIG>) of the cornea and can help break up the particle <NUM> to allow aspiration and irrigation to proceed normally at an unblocked flow rate.

Feedback in the phacoemulsification system <NUM> (of <FIG>) to an occlusion or partial occlusion of the aspiration passageway <NUM> due to a particle <NUM> can trigger a routine that causes the needle <NUM> to modulate from the ultrasonic frequency to the high ultrasonic frequency (or optionally back and forth). Modulating between the ultrasonic frequency and the high ultrasonic frequency will likely break up the particle <NUM> and reduce heating at the corneal incision <NUM> during a phacoemulsification procedure. Some embodiments contemplate using feedback in the phacoemulsification system <NUM> to identify if a particle is engaged in an occluding or partial occluding manner. This can include a diminished aspiration flow rate of ocular material aspirated from an eye <NUM> causing a diminished irrigation flow rate of irrigation fluid into the eye <NUM> (to maintain balanced IOP), an increased aspiration vacuum (which could be based on how hard an aspiration pump <NUM> has to work to aspirate ocular material from the eye <NUM>), or an increase in load to drive the frequency of the needle <NUM> due to an increased mass of a particle engaged/lodged in or on the free distal tip <NUM> of needle <NUM>. Sensors can be employed to evaluate these aforementioned scenarios to initiate modulating the ringing frequency. For example, a sensor (not shown) can be located in the aspiration passageway <NUM> or irrigation pathway <NUM>, or elsewhere, to sense a diminished flow rate of aspiration material from the eye <NUM> or irrigation fluid into the eye <NUM>, given that these flow rates are intrinsically connected to maintain IOP. Similarly, the aspiration pump <NUM> can be used to sense an occlusion based on what is considered a normal resistance to flow. For example, back electromagnetic force (EMF) of the pump is an effective way to identify if there is an occlusion in the aspiration passageway <NUM>. When the aspiration ocular material is flowing at an expected flow rate that does not reflect an occluded or partially occluded aspiration passageway <NUM>, the control feedback circuit <NUM> can be made to operate in a manner before the occlusion occurred. Some assemblies contemplate using the piezoelectric transducer <NUM>/<NUM> to identify the presence of a particle <NUM> based on an increase in mass of the needle <NUM> due to the particle <NUM> engaged therewith. An increase in the mass of the needle <NUM> due to the engaged particle can correspond to an increase in voltage load to drive the frequency via the piezoelectric transducer <NUM>/<NUM>. When the mass of the needle <NUM> returns to a level that does not reflect an increased voltage level to drive the circuit, the system can return to the state before the occlusion occurred.

Certain assemblies contemplate employing frequencies ringing the needle <NUM> in a manner opposite to the above assemblies describing ultrasonic frequencies modulating to high ultrasonic frequencies. For example, generally ringing the needle <NUM> at a high ultrasonic frequency and then modulating the ringing to a lower ultrasonic frequency may improve breaking up an occluding particle <NUM> with cavitation. In this scenario, an occlusion may be cleared faster at a low ultrasonic frequency where larger bubbles are generated by increased cavitation effects.

Certain assemblies contemplate ringing the needle <NUM> between the ultrasonic (low) frequency range (<NUM> to below <NUM>) and a sonic frequency range (less than <NUM>). A sonic frequency, or frequency that is in the sound range, greatly reduces the heating effects of vibration on the needle <NUM>. A sonically vibrating needle <NUM> is also considered a 'cold needle' because there is little risk of burning the incision site <NUM> of the cornea. Much like the assemblies described herein that are directed to modulating the frequency ringing the needle <NUM> between an ultrasonic frequency and a high ultrasonic frequency, the same assemblies are further contemplated using the condition where sonic frequency is substituted in place of the high ultrasonic frequency. In other words, some assemblies are further envisioned to modulate the needle <NUM> from ultrasonic frequency to sonic frequency when there is an occlusion or partial occlusion, or optionally when a surgeon wants to manually switch between ultrasonic and sonic frequencies, or optionally toggling between the two after a predetermined amount of time, for example.

Certain assemblies contemplate employing frequencies ringing the needle <NUM> in a manner similar to the above assemblies but with a substitution of modulating ultrasonic frequencies to sonic frequencies. For example, ringing the needle <NUM> at a sonic frequency and then modulating to an ultrasonic frequency to break up an occluding particle <NUM>.

Another optional assembly is depicted in <FIG>, which contemplates the needle <NUM> (which is hollow and may be titanium, or other suitable material known in the art) including a shoulder <NUM>. The shoulder <NUM> is essentially a step that defines where the outer diameter of needle <NUM> changes from a larger diameter to smaller diameter. More specifically, the needle <NUM> includes a first substantially cylindrical portion <NUM> between the shoulder <NUM> and the free distal tip <NUM> and a second substantially cylindrical portion <NUM> between the shoulder <NUM> and the supported end <NUM>. The first substantially cylindrical portion <NUM> is smaller in diameter than the diameter of the second substantially cylindrical portion <NUM>. In this case, the shoulder <NUM> is preferably located between <NUM> and <NUM> from the free distal tip <NUM>. The inequality of the diameters advantageously amplifies the ringing amplitude in the first substantially cylindrical portion <NUM> as illustratively depicted by the standing wave plot <NUM> of the needle <NUM> subjected to a high ultrasonic frequency equal to or above <NUM>. In more detail, there is a distal node of minimum amplitude at a node location <NUM> on the substantially cylindrical needle <NUM> approximately at the shoulder <NUM>. Accordingly, the needle <NUM> is considered 'cold' at or near the shoulder <NUM> because the needle <NUM> is not vibrating with a significant amplitude. Also, if the shoulder <NUM> is visible, a surgeon can readily see where the coolest part of the needle <NUM> is during surgery. The standing wave shown in graph <NUM> has a distal anti-node <NUM> of maximum amplitude at the free distal tip <NUM> (which has a peak higher than the amplitude of the anti-node <NUM> because the needle <NUM> possesses the smaller diameter of the first substantially cylindrical portion <NUM>). The high displacement amplitude at distal anti-node <NUM> at the distal tip <NUM> enhances tissue penetration by the free distal tip <NUM> during operation.

The advantage of reduced corneal incision <NUM> heating may be obtained by the distal node of minimum amplitude <NUM> preferably located between <NUM> - <NUM> from the free distal tip <NUM>. Although in <FIG> the shoulder <NUM> is depicted as being essentially at the distal node of minimum amplitude <NUM> this is not a requirement. Indeed, it is preferred that the distal node of minimum amplitude <NUM> does not coincide or otherwise reside at the shoulder <NUM>. For example, the distal node of minimum amplitude <NUM> may be located more distally towards the free distal tip <NUM> instead of essentially (such as +/- <NUM>) at the shoulder <NUM>.

<FIG> are line drawings of alternate inner bore geometries that affect the vibration response of an ultrasonically driven needle. <FIG> illustratively depicts a needle <NUM> (which is hollow and may be titanium, or other suitable material known in the art) comprising an elliptical shaped bore <NUM> that possesses a thicker needle wall as it approaches the supported end <NUM> and a thinner needle wall as it approaches the free distal tip <NUM>. The outer needle diameter <NUM> is essentially constant or otherwise cylindrical between the supported end <NUM> and the free distal tip <NUM>. <FIG> illustratively depicts another needle <NUM> (which is hollow and may be titanium, or other suitable material known in the art) comprising a linear angulated bore <NUM> comprising a thicker needle wall towards the supported end <NUM> and a thinner needle wall towards the free distal tip <NUM>. The outer needle diameter <NUM> is essentially constant between the supported end <NUM> and the free distal tip <NUM>. <FIG> illustratively depicts yet another needle <NUM> (which is hollow and may be titanium, or other suitable material known in the art) comprising an internal stepped bore <NUM>, <NUM> that possesses a thicker needle wall along bore <NUM> proximal to the supported end <NUM> that steps to a thinner needle wall along bore <NUM> as it approaches the free distal tip <NUM>. The outer needle diameter <NUM> is essentially constant between the supported end <NUM> and the free distal tip <NUM>. <FIG> illustratively depicts yet another needle <NUM> (which is hollow and may be titanium, or other suitable material known in the art) comprising an internal stepped bore <NUM>, <NUM>, and <NUM> comprising a needle wall along bore <NUM> that is thickest proximal to the supported end <NUM>, that steps down to an intermediate thickness wall along bore <NUM> in the middle of the needle <NUM>, with another step to a thinner needle wall along bore <NUM> towards the free distal tip <NUM>. The outer needle diameter <NUM> is essentially constant between the supported end <NUM> and the free distal tip <NUM>. Though the bore <NUM> in <FIG> and the bores <NUM> and <NUM> in <FIG> have thicknesses that are essentially parallel to the outer diameter <NUM> of the needle <NUM>, certain assemblies contemplate such a condition not being required. For example, the thicknesses can be tapered, curved, etc., within the scope of different thickness bores. Moreover, the different thickness bores may be implemented to alter the frequency profile to create nodes of minimum amplitude or create varied frequency responses at specific locations along the length of the needle.

<FIG> illustratively depicts a handpiece with respect to a driving frequency of approximately <NUM>. An example of a driving frequency is an applied resonant frequency that excites the phacoemulsification device (or whatever element is being driven) subjected to the driving frequency causing the phacoemulsification device to resonate with a standing wave as shown in <FIG> and <FIG>. With respect to the present phacoemulsification device <NUM>, the handpiece <NUM> includes a back cylinder <NUM> that comprises piezoelectric crystals <NUM> driven to vibrate by a control feedback circuit <NUM>, which delivers an oscillating voltage to the piezoelectric transducer <NUM>/<NUM>. The back cylinder <NUM>, which as depicted in <FIG> includes a rear portion 124A and a front portion 124B, includes two or more piezoelectric crystals <NUM> (e.g. ceramic discs) sandwiched between two metal cylinders, which can be made from titanium. The two or more piezoelectric crystals <NUM> can be compressed through a central bolt (not shown). Certain assemblies envision a Langevin transducer made up of four PZT8 piezo ceramics sandwiched between a stainless steel rod and a titanium rod. The two or more piezoelectric crystals <NUM> convert an applied voltage to longitudinally expand and contract. This is known as a "Langevin transducer". A step horn <NUM> is distal to the back cylinder <NUM> and the piezoelectric crystals <NUM>. The step horn <NUM> comprises a tapered section <NUM> that tapers from a large diameter at a proximal end of step horn <NUM> to a small diameter at distal end <NUM> of step horn <NUM>. Certain other assemblies envision the step horn <NUM> being a titanium cylinder with a smaller diameter than the Langevin transducer diameter. The aspiration passageway <NUM> extends through the handpiece <NUM> and the substantially cylindrical titanium needle (or just "needle") <NUM> exiting at a free distal tip <NUM>. The needle <NUM> may or may not be cylindrical because in some cases, the substantially cylindrical titanium needle <NUM> may be tapered approximately five-thousandths of an inch (<NUM>) from the supported end structure <NUM> to the free distal tip <NUM>, which is near cylindrical or substantially cylindrical (in one example substantially means within +/- <NUM>% of being a perfect cylinder). The needle <NUM> screws into the step horn <NUM> distal end <NUM> via a supported end structure <NUM>, which in this case are threads. A fastening hub (not shown) can further retain the needle <NUM> to the handpiece <NUM> at the distal end <NUM> of step horn <NUM>. Certain assemblies contemplate the needle length being <NUM> inches (<NUM>) long and the hub length being about <NUM> inches (<NUM>) long with the needle OD being between <NUM> and <NUM> inches (<NUM> and <NUM>) and an ID being between <NUM> and <NUM> inches (<NUM> and <NUM>), or some variation thereof.

The response plot is aligned with the phacoemulsification device <NUM> in that the length of the phacoemulsification device <NUM> spans of the length of abscissa <NUM> with a vibration response graph <NUM>. The graph's y-axis <NUM> represents the displacement of the phacoemulsification device <NUM> and the x-axis <NUM> is the position/length along the phacoemulsification device <NUM>. Hence, the amplitude response plot <NUM> is the vibrational displacement response of the low ultrasonic standing wave <NUM> along the length of the phacoemulsification device <NUM> at a driving frequency of approximately <NUM>. As shown by the amplitude response <NUM>, a handle node of minimum amplitude <NUM> is between the two piezoelectric crystals <NUM> that form the transducer <NUM>/<NUM>. A second node of minimum amplitude (or tapered section node) <NUM> resides in the tapered section <NUM> of the step horn <NUM>. At this low ultrasonic frequency, there is no node of minimum amplitude along the needle <NUM>. Certain assemblies contemplate ensuring that there is no node of minimum amplitude in the tapered segment <NUM> that is higher than ¼ of the low frequency wavelength, which in this case is around <NUM>. For example, based on the physics of the system, the length of the tapered section <NUM> must be at least <NUM> inches (<NUM>) with a wavelength of <NUM> inches (<NUM>) (traversing the device <NUM>) at a resonant frequency of <NUM>. A distal antinode <NUM> at the free distal tip <NUM> causes a high displacement that is effective in fragmenting and emulsifying a cataractous lens of an eye <NUM>. Certain assemblies envision a low driving frequency between <NUM> and <NUM> to provide both fragmentation and emulsification of cataractous lens material.

<FIG> illustratively depicts the handpiece of <FIG> with respect to a driving frequency of approximately <NUM>. As with <FIG>, the length of the phacoemulsification device <NUM> spans or is otherwise aligned with the x-axis <NUM> along the vibration response graph <NUM>. The vibration response graph <NUM> plots the amplitude standing wave response <NUM> of the phacoemulsification device <NUM> at a driving frequency of approximately <NUM>. The amplitude standing wave response <NUM> is a high ultrasonic frequency standing wave. More specifically, the x-axis <NUM> corresponds with the position/length along the phacoemulsification device <NUM>. Accordingly, the amplitude standing wave response <NUM> is the vibrational displacement response <NUM> along the length of the phacoemulsification device <NUM>. As shown by the amplitude standing wave response <NUM>, there are a number of different nodes of minimum amplitude at <NUM> including a handle node <NUM>, a handle-step horn/back handpiece interface node <NUM>, a tapered section node <NUM>, and a needle node <NUM>. There is a high amplitude/displacement antinode <NUM> at or essentially at the free distal tip <NUM> (e.g., within <NUM>).

Some assemblies envision driving the frequency of the phacoemulsification device <NUM> between the low frequency of approximately <NUM> and the high frequency of approximately <NUM> to manage fragmentation and cavitation of cataractous lens material. As previously presented, fragmentation is the action of cutting or splitting the lens in fragments like a knife moving rapidly or otherwise very fast in a medium. In some cases, the ocular fragments <NUM> are sometimes too large to be sucked/aspirated through the aspiration passageway <NUM>, let alone into the lumen/opening at the free distal tip <NUM>. As discussed previously, this is a problem because a large fragment <NUM> (of <FIG>) can occlude or otherwise block the aspiration passageway <NUM> at the free distal tip <NUM>. Not only will a large fragment <NUM> block/obstruct the phacoemulsification device from aspirating ocular fragments <NUM> and providing irrigation fluid <NUM>, heat can build up along the needle <NUM> potentially burning the eye incision/interface <NUM> (of <FIG>). At lower frequencies, under <NUM> and more typically between <NUM> and <NUM>, cavitation of the liquid in the eye <NUM> at the free distal tip <NUM> serves to emulsify or otherwise disintegrate the fragmented cataractous lens material into small particles that are small enough to pass through the opening at the free distal tup <NUM> and into the aspiration passageway <NUM>. Intense cavitation induced waves may push the lens fragments away from the free distal tip <NUM>, which complicates maneuvering the free distal tip <NUM> in the eye <NUM>. These ways can also have negative effects by dislocating healthy eye tissue. There have been reports of fragmented cataractous lens material being pushed/chased into the posterior portion of an eye <NUM>. Higher frequencies, especially those equal to or above <NUM>, generate less cavitation and above <NUM>, cavitation almost disappears.

With this in mind, switching from a lower frequency under <NUM> to a high frequency equal to or above <NUM> has a number of benefits. For example, as shown in <FIG>, at a high frequency the needle node of minimum amplitude <NUM> is considered a 'cold needle' because there is no ultrasonic vibration occurring at the node of minimum amplitude <NUM>. The needle node of minimum amplitude <NUM> is in an eye interface region (where the needle <NUM> will mostly interface an eye incision <NUM> during surgery) along the needle <NUM> depicted by the double arrow between the boundary lines <NUM>. Hence, if the needle <NUM> becomes occluded with a cataractous lens fragment at a low frequency, by switching to a high frequency the cataractous lens fragment can break up and be sucked through the aspiration passageway <NUM> more quickly avoiding overheating the needle <NUM> at the incision <NUM> if in the eye interface region between the boundary lines <NUM>. Furthermore, the high frequency reduces cavitation generation, which as previously mentioned has its own problems. Some assemblies contemplate the high frequency and the low frequency both being purely longitudinal waves.

The tapered region <NUM> of the phacoemulsification device <NUM> can be lengthened, shortened, widened, etc., in order to better control the placement of a node of minimum amplitude along a needle <NUM> when vibrated at a high ultrasonic frequency. The geometry of the tapered region <NUM> further influences keeping a node of minimum amplitude from forming or otherwise existing along the needle <NUM>. Certain other embodiments of the present invention do not limit the tapered region <NUM> from being conical but entertain additional shapes/profiles including elliptical, exponential, Gaussian, and Fourier, just to name a few. Certain commercial embodiments envision the total length of the handpiece <NUM> being approximately <NUM> inches (<NUM>) long with a diameter of approximately <NUM> inches (<NUM>). The step horn <NUM> can be made of a titanium rod (matching the handpiece material) that is approximately <NUM> inches long (<NUM>) and about <NUM> inches (<NUM>) in diameter tapering conically down to <NUM> inches (<NUM>) in diameter over a tapered region <NUM> that is approximately <NUM> inches (<NUM>) long. The needle <NUM> can be approximately <NUM> inches (<NUM>) long with an outside diameter of approximately <NUM> inches (<NUM>) and an inside diameter of approximately <NUM> inches (<NUM>). The aspiration passageway <NUM> can be about <NUM> inches (<NUM>) in diameter. A high frequency of equal to or above <NUM> can be preferably, about <NUM>, and a low frequency below <NUM>, can be approximately <NUM>. Other assemblies envision a low frequency below <NUM> and a high frequency above <NUM>. The phacoemulsification device <NUM> can be made to toggle between the low frequency and the high frequency automatically with the feedback system that may take into account one or more of the following: vacuum, flow rate, bottle height, procedure modes, or by way of an operator (surgeon command) toggling a foot switch, hand switch, or voice control, just to name a few examples. The software that controls the low frequency and high frequency can be executed via the computer controller <NUM> or equivalent computing device.

<FIG> is a line drawing of yet another phacoemulsification assembly. As shown, the phacoemulsification handpiece <NUM> does not have a tapered region in the step horn <NUM>. Rather, there is a tapered region <NUM> at the proximal end of the needle <NUM>. The tapered region <NUM> is configured to control the node of minimum amplitude along the substantially cylindrical portion <NUM> of the needle <NUM> when at a low ultrasonic frequency. As with the tapered portion <NUM> of the step horn <NUM> of <FIG> and <FIG>, a tapered node of minimum amplitude <NUM> can be designed to fall either within the tapered region <NUM> of the needle <NUM> or in the cylindrical step horn <NUM>. Some assemblies envision the needle <NUM> being a unitary titanium element. For reference, a longitudinal axis <NUM> that extends from the back of the handpiece cylinder <NUM> to the free distal tip <NUM> is illustratively shown. The longitudinal axis <NUM> is a theoretical axis that can equally be applied to the other phacoemulsification devices, such as <NUM>, described herein. During high ultrasonic frequencies, a node of minimum amplitude <NUM> can exist in the cylindrical portion <NUM>, to create a 'cold needle' region at the cornea incision <NUM>.

<FIG> is an illustration of a low frequency plot superimposed on a high frequency plot consistent. More specifically, graphs of three frequency signals are plotted with voltage being in the y-axis (ordinate) <NUM> and time being in the x-axis <NUM> (abscissa) is shown. The low frequency signal <NUM> is added to the high frequency signal <NUM> to generate the combined frequency signal <NUM>. As shown, the low frequency <NUM> and the high frequency <NUM> are each generated with essentially equal power, hence both the low frequency <NUM> and the high frequency <NUM> have about the same amplitude. In this way, the combined frequency <NUM> is not dominated by either the low frequency <NUM> or the high frequency <NUM>. Certain assemblies envision the low frequency <NUM> having higher power than the high frequency <NUM> thereby generating a situation where the low frequency <NUM> is essentially a carrier frequency (not shown) of the high frequency <NUM>. Likewise, if the high frequency <NUM> is generated via a higher applied power than the low frequency <NUM>, the high frequency <NUM> will have a more dominating effect on the combined frequency (not shown). Certain assemblies envision the piezoelectric transducer <NUM>/<NUM> of any phacoemulsification handpiece described herein generating the two frequencies <NUM> and <NUM>, as shown in <FIG>.

<FIG> is a plot of a standing wave at the combined frequencies with respect to a phacoemulsification device <NUM>. As shown, the vibration response graph <NUM> is of a standing wave plot <NUM> of the combined two frequencies <NUM> and <NUM> resonating the phacoemulsification device <NUM>. Here, the low frequency is approximately <NUM> and the high frequency is approximately <NUM>, however other certain embodiments envision the low frequency below <NUM> and the high frequency being equal to or above <NUM>. It is further envisioned that the standing wave plot <NUM> created by the high and low frequencies <NUM> and <NUM> is essentially a superposition of the high frequency standing wave <NUM> over the low frequency standing wave <NUM> (depicted in <FIG> and <FIG>). Accordingly, the displacement response plot <NUM> (i.e., the resonant displacement <NUM> of the phacoemulsification device <NUM> along the length <NUM> of the device <NUM>) comprises a semi-node of low amplitude <NUM> in the tapered section <NUM> of step horn <NUM> and a single semi-node of low amplitude <NUM> along the length of the needle <NUM>. Unlike the nodes of minimum amplitude <NUM> and <NUM> of <FIG>, the semi-node of low amplitudes <NUM> and <NUM> do not have a near zero displacement of vibration on the device <NUM>, rather they create a mere depression in the resonant response of the device <NUM>. Accordingly, the needle <NUM> has a 'cool region' <NUM> instead of a 'cold region', depicted by the double arrow between the lines <NUM>, The 'cool region' keeps the eye <NUM> from burning where the needle <NUM> interfaces the eye <NUM>. As further shown, there is an antinode <NUM> approximately at the free distal tip <NUM> to enhance the cutting action and particle breakup.

Some assemblies further envision a surgeon/operator adjusting power to the phacoemulsification device <NUM> to drive one of the frequencies to dominate over the other. More specifically, certain assemblies envision a switch, a foot pedal, voice control, or some other input, to simultaneously increase power of the high frequency mode <NUM> while proportionally decreasing power to the low frequency mode <NUM>, and vise-versa. Increasing power to the high frequency mode <NUM> (with a proportional decrease in power to the low frequency mode <NUM>) could be accomplished in discrete intervals or optionally smoothly over an infinite range of power levels, or somewhere in between. In this way, the needle <NUM> can be made to more effectively cut cataractous material into fragments while minimizing cavitation with a "cool" needle <NUM>. Decreasing power to the high frequency mode <NUM> while proportionally increasing power to the low frequency mode <NUM> can serve to emulsify the fragments for better aspiration through the aspiration passageway <NUM>. Having both frequencies used together provides certain benefits of more efficiently cutting and emulsifying fragments of cataractous eye material. When providing a surgeon with the opportunity to adjust the power of one frequency over another, maneuvering through a cataract surgery to remove cataracts can be accomplished more efficaciously. In short, in consideration that while lowering ultrasonic frequencies enhances cavitation but generates more heat, the higher frequencies increase fragmentation without increasing heat, the two frequencies can be combined in different proportions to best suit the situation. For example, driving the lower frequency with lower power and increasing power for the high frequency could help fragment harder cataract tissue when cutting is more important than most of the occasion. This can be done with purely longitudinal waves. By turning up or down the low frequency (and inversely proportionally forcing a down or up response to the high frequency), a surgeon will have improved control.

Though assemblies described in conjunction with <FIG> are directed to phacoemulsification device <NUM> with the tapered region <NUM>, other phacoemulsification assemblies <NUM> with no such taper can be employed as well. In other words, the aforementioned vibration concepts can be used in conjunction with any number of different phacoemulsification devices.

<FIG> depict various piezoelectric transducer circuits arranged to drive a phacoemulsification needle at various frequencies. Though any of the phacoemulsification device assemblies are combinable with at least the foregoing circuit diagrams described, the phacoemulsification assembly <NUM> of <FIG> is used in conjunction with the various circuits for purposes of explanation. As previously described, the piezoelectric transducer <NUM>/<NUM> includes two or more piezoelectric crystals <NUM> that are compressed or otherwise sandwiched between the rear back cylinder portion 124A and the front back cylinder portion 124B via a central bolt (not shown). The rear back cylinder portion 124A, the front back cylinder portion 124B, the step horn <NUM> and the needle <NUM> may all be made out of titanium. The piezoelectric crystals <NUM> may be arranged in a Langevin transducer configuration that converts an applied cycled voltage to longitudinally expand and contract thereby driving vibrational resonance in the phacoemulsification assembly <NUM>. The displacement at the front cylinder (step horn)/rear cylinder interface <NUM> is amplified compared to the displacement of the piezoelectric crystals <NUM>. The step horn <NUM> further amplifies the vibration relative to the front cylinder/rear cylinder interface <NUM> because of the lower mass. Amplification of the step horn <NUM> is envisioned to be as much as <NUM> times greater at the distal end of the step horn <NUM> compared with the front cylinder/rear cylinder interface <NUM>. Certain other assemblies envision changing the geometry/dimensions of the phacoemulsification device and/or materials used to alter or otherwise tailor the resonance. For example, a <NUM> inch (<NUM>) long piezoelectric transducer <NUM>/<NUM> plus step horn <NUM> and a <NUM> inch long (<NUM>) attached needle <NUM> may have a resonance frequency of about <NUM> with higher resonances at <NUM>, <NUM>, <NUM>, <NUM> and so on. Some of these resonances generate motion at the needle tip and some do not.

<FIG> is a line drawing of a circuit layout embodiment for a dual frequency ultrasonic driver consistent with embodiments of the present invention. As shown, the dual frequency ultrasonic diagram of a phacoemulsification arrangement <NUM> depicts the phacoemulsification assembly <NUM> electrically connected to a dual frequency ultrasonic driver circuit <NUM>. When in operation, the ultrasonic driver circuit <NUM> is envisioned to energize or otherwise drive the phacoemulsification assembly <NUM> with two different frequencies, a low-frequency and a high-frequency, applied either simultaneously or one at a time.

A low-frequency path <NUM>, as shown by the dashed oval <NUM>, generally includes a low-frequency oscillator <NUM>, a first voltage amplifier <NUM>, a first switch <NUM> and a first impedance matching network <NUM>. When powered, the low-frequency oscillator <NUM> generates a low frequency voltage signal, which may be under <NUM>. The low frequency voltage signal can be in the form of a sine wave or a square wave, just to name a few of the many wave profiles known to those skilled in the art. The low-frequency voltage signal is amplified by a first power amplifier <NUM> represented by an output voltage V1, which is then passed through a first impedance matching network <NUM>. In this configuration, the first impedance matching network <NUM> comprises a first tapped transformer <NUM> (depicted as inductor L1) electrically connected to a first LC filter <NUM> (LC1) that filters the amplified low frequency signal generated by the low-frequency oscillator <NUM>. The LC1 filter <NUM> can reduce noise, separate out or condition desired signals, for example. Typically, when capacitors or inductors are involved in an AC circuit, the current and voltage do not peak at the same time. When a voltage is applied to an inductor, the inductor resists the change in current. The current builds up more slowly than the voltage, lagging it in time and phase. On the other hand, since the voltage applied to a capacitor is directly proportional to the charge on the capacitor, the current must lead the voltage in time and phase to conduct charge to the capacitor plate and raise the voltage. The fraction of a period difference between the peaks expressed in degrees is considered the phase difference. The phase difference is obviously less than or equal to <NUM> degrees. Those skilled in the art generally use the angle by which the voltage leads the current, which results in a positive phase for inductive circuits since current lags the voltage in an inductive circuit. The phase is negative for capacitive circuit since current leads the voltage. Hence, in order to deliver the alternating current and voltage efficiently to the piezoelectric transducer <NUM>/<NUM>, certain assemblies envision balancing the LC1 circuit <NUM> to output essentially an in-phase alternating voltage and current. Certain other assemblies envision the phase difference between the voltage and current being within +/- <NUM>%. Likewise, the high-frequency path <NUM>, as shown by the dashed oval <NUM>, includes a high-frequency oscillator <NUM>, a second voltage amplifier <NUM>, a second switch <NUM> and a second impedance matching network <NUM>. When powered, the high-frequency oscillator <NUM> generates a high frequency voltage signal, which may be equal to or above <NUM>. The high-frequency voltage signal is amplified by a second power amplifier <NUM> represented by an output V2, which is then passed through a second impedance matching network <NUM>. The second impedance matching network <NUM> comprises a second tapped transformer <NUM> (depicted as an inductor L2) electrically connected to a second LC filter <NUM> (LC2). For single frequency operation, the secondary winding of a tapped transformer multiplies the voltages V1 and V2 by the transformer turn ratio and the resonance matching effect of the impedance matching network <NUM>/<NUM>. Some assemblies envision the power amplifiers <NUM> and <NUM> each being a class AB amplifier, a half bridge class C amplifier or a full bridge class D amplifier.

The switches, SW1 <NUM> and SW2 <NUM>, connect the low-frequency path <NUM> and/or the high-frequency path <NUM> to facilitate single or simultaneous frequency operation. For example, when the first switch <NUM> (SW1) is closed, the low-frequency path <NUM> actively drives the piezoelectric transducer <NUM>/<NUM> to vibrate at the low-frequency by way of transforming energy through third tapped transformer <NUM> (depicted as an inductor L3) that is in the piezoelectric transducer connecting circuit leg <NUM>. L1 <NUM>, L2 <NUM> and the third tapped transformer <NUM> (depicted as an inductor L3) generally make up the inductive transformer <NUM> that supplies power to the two wires <NUM> and <NUM> used for connecting the dual frequency driver circuit <NUM> through the piezoelectric crystals <NUM>. When the second switch <NUM> (SW2) is closed, the high-frequency path <NUM> actively drives the piezoelectric transducer <NUM>/<NUM> to vibrate at the high-frequency by way of transforming energy through L3 <NUM>. If both the first switch <NUM> (SW1) and the second switch <NUM> (SW2) are closed, the piezoelectric crystals <NUM> can make the phacoemulsification assembly <NUM> vibrate at a combined frequency, like the combined frequency <NUM> depicted in <FIG>. For single frequency operation the secondary winding of a tapped transformer multiplies the voltages V1 and V2 by the transformer turn ratio and the resonance effect of the matching network. For simultaneous frequency operation, the sum of V1 and V2 is multiplied. In this example, the secondary winding L3 <NUM> is connected to the piezoelectric crystals <NUM>. Only two wires are used for connecting the driver circuit <NUM> to the piezoelectric transducer <NUM>/<NUM>. The inductive transformer <NUM> can further function as a frequency mixer that changes the percent contribution of the output low voltage and low current relative to and inversely proportional to the output high voltage and high current. For example, if the inductive transformer <NUM> changes the output low voltage and low current to <NUM>%, the output high voltage and high current is <NUM>% of the total combined (superimposed) output voltage and current. An example of a combined output voltage is graphically depicted in <FIG>. Another mixer is by way of proportionally changing the amplification of the respective high and low signals output via the amplifiers <NUM> and <NUM>, just to name another example of many. This can be accomplished by an actuator (not shown) controlled either manually (i.e., a foot pedal, knob, button, voice control, etc.) or via a computer system.

<FIG> are line drawings of various LC network block diagrams using a tapped transformer with a primary LT winding. Each of the LC networks <NUM> and <NUM> generally comprise an inductor and capacitor configuration that connects to a primary LT winding, which in <FIG>, the primary LT winding is L1 <NUM> and L2 <NUM>. These LC (inductor and capacitor) networks can assume a number of different configurations, with three depicted examples. LC filter network LC1 1020A of <FIG> is a simple capacitor <NUM> (C) connected to the LT winding <NUM>, which in <FIG> is either L1 <NUM> or L2 <NUM>, however it could be L1 <NUM> and L2 <NUM>. <FIG> is LC filter network LC1 1020B comprising an inductor <NUM> (L) and capacitor <NUM> (C) connected to the LT winding <NUM>. <FIG> is LC filter network LC1 1020C comprising inductor <NUM> (L) and two capacitors (C1 <NUM> and C2 <NUM>) connected to the LT winding <NUM>. Certain assemblies contemplate that the impedance matching network 1020A, B or C comprise an LC network (LC1 <NUM> and LC2 <NUM> of <FIG>) and the primary winding of a tapped transformer (L1 <NUM> and L2 <NUM>, also of <FIG>). Different LC networks inductor/capacitance configurations can be used without departing from the scope of the present invention.

<FIG> is a line drawing of a circuit layout for a half bridge class C ultrasonic driver circuit for a piezoelectric transducer. As shown, the half bridge class C ultrasonic driver circuit <NUM> connects to the piezoelectric transducer <NUM>/<NUM> by way of the inductive transformer <NUM>. Square wave oscillator-<NUM><NUM> must run out of phase with square wave oscillator-<NUM><NUM> such that only the corresponding transistor Q1 <NUM> or Q2 <NUM> is turned ON at a given time. In other words, when square wave oscillator-<NUM><NUM> produces a 'high' square wave signal amplitude, transistor Q1 <NUM> is turned ON while transistor Q2 <NUM> is turned OFF. In this scenario, square wave oscillator-<NUM><NUM> produces a 'low' square wave signal amplitude while square wave oscillator-<NUM><NUM> is producing a 'high' square wave signal amplitude. Of course, the opposite scenario can equally occur wherein transistor Q1 <NUM> is turned OFF when square wave oscillator-<NUM><NUM> produces a 'high' square wave signal amplitude and transistor Q2 <NUM> is turned ON while square wave oscillator-<NUM><NUM> produces a "low" square wave signal amplitude.

The two transistors Q1 <NUM> and Q2 <NUM> amplify the low voltage pulses produced by the square wave oscillators <NUM> and <NUM> into a high-voltage square wave Vcc. Because the piezoelectric transducer has a high quality factor, if the frequency of the two square wave oscillators <NUM> and <NUM> match the resonant frequency of the phacoemulsification assembly <NUM> then the high-voltage square wave Vcc is converted to a near perfect sine wave. Certain assemblies envision the output voltage <NUM> (Vout) driving the piezoelectric transducer <NUM>/<NUM> with a voltage of about <NUM> V peak-to-peak. The impedance matching network <NUM>, which includes L1 <NUM>, C1 <NUM>, C2 <NUM>, and the inductive transformer <NUM> are electrically matched with the natural frequency of the piezoelectric transducer <NUM>/<NUM> (handpiece <NUM> and possibly the needle <NUM> as well). This can be modeled to include equivalent (imaginary) electrical elements, which in this example includes capacitors Co1 <NUM>, Cm1 <NUM>, inductor Lm1 <NUM> and resistor Rm1 <NUM>, shown in phacoemulsification assembly dashed box <NUM>. At the physical resonant frequency or frequencies of the phacoemulsification assembly <NUM> (represented by the electrical elements in the phacoemulsification assembly dashed box <NUM>), Lm1 <NUM> and Cm1 <NUM> cancel out. This is referred to as series resonance. In one example, when the phacoemulsification assembly <NUM> has a natural frequency that resonates at <NUM>, and there is series resonance, there is no phase offset between the output voltage Vout and the output current when the input signal pulses from the square wave oscillators <NUM> and <NUM> are also <NUM>. For example, by matching the impedance of the power amplifiers <NUM> and <NUM> with the impedance of the phacoemulsification assembly <NUM> and running the square wave oscillators <NUM> and <NUM> at the resonant frequency of <NUM>, a Vcc of <NUM> Vdc is converted to about a <NUM> V sine wave necessary to drive/vibrate the phacoemulsification assembly <NUM>. This will generate a near maximum transfer of power, which in this case is about <NUM> W. When calculating the matching network components, the circuit of <FIG> can be used to determine the resonant frequency of between +/- <NUM>%.

<FIG> is an example of a circuit layout for modeling the half bridge class C ultrasonic driver circuit of <FIG>. The matching impedance components and test configuration of <FIG> assumes that capacitor Co1 <NUM> and resistor resister Rm1 <NUM> are the same as the inherent components of the phacoemulsification assembly <NUM>, represented by the phacoemulsification assembly dashed box <NUM>. Capacitor Co1 <NUM> corresponds with the capacitance of the piezoelectric crystals <NUM> plus the capacitance of the handpiece <NUM> measured at the operating frequency. Resistor Rm1 <NUM> is the electrical equivalence of the resistive part of the phacoemulsification assembly load plus the mechanical losses. These components (capacitor Co1 <NUM> and resistor resister Rm1 <NUM>) can be measured using an impedance analyzer. Values from the components, inductors L1 <NUM>, L2 <NUM>, L3 <NUM>, and capacitors C1 <NUM> and C2 <NUM>, are calculated as a function of capacitor Co1 <NUM> and resistor Rm1 <NUM>.

<FIG> is a line drawing circuit diagram of yet another driving circuit. In this optional dual frequency driver <NUM>, the ultrasonic frequency circuit configuration <NUM> only uses one amplifier <NUM> to amplify both the low-frequency oscillator <NUM> and the high-frequency oscillator <NUM>. In this example, the low-frequency oscillator <NUM> and the high frequency oscillator <NUM> generate a sinusoidal waveform that energizes the piezoelectric transducer <NUM>/<NUM> via the inductive transformer <NUM>. As shown, the low-frequency path <NUM> incorporates the common amplifier <NUM> as does the high-frequency path <NUM>. The amplifier <NUM> is a class AB amplifier. The components that comprise the LC networks <NUM> and <NUM> included in the impedance matching network may create one or more resonances different from the resonant frequencies of the phacoemulsification assembly <NUM> that includes the piezoelectric transducer <NUM>/<NUM>. As previously discussed, if the impedance network <NUM> is closely matched with the output frequency of the phacoemulsification assembly <NUM>, the phacoemulsification assembly <NUM> will resonate at its natural frequency. By matching the natural frequency of at least the handpiece <NUM>, and possibly the needle <NUM>, with the electrical output frequency of the circuit <NUM>, the system is more efficient. Certain assemblies envision matching the natural frequency of only the handpiece <NUM> with the circuit <NUM> because the handpiece <NUM> (and not the needle <NUM>) overwhelmingly dictates the natural frequency. In other words, the mass and therefore the frequency response of the handpiece <NUM> contributes to the majority of the phacoemulsification assembly <NUM>. Matching the electrical circuit <NUM> with the natural frequency of the handpiece <NUM> (and possibly the needle <NUM> too) avoids excessive heat generation, buzzing, and other losses. In practice, it may be acceptable to match these frequencies within +/- <NUM>% to the frequencies generated by the oscillators <NUM> and <NUM>.

<FIG> is a line drawing circuit diagram of multiple oscillators producing different system matched frequencies. <FIG> is an example of a dual frequency ultrasonic system <NUM> powered by the ultrasonic driver circuit <NUM>. In this ultrasonic driver circuit <NUM>, a low-frequency oscillator <NUM> and a high frequency oscillator <NUM> generate respective frequency signals that can be applied to the phacoemulsification assembly <NUM> simultaneously or successively (i.e., one at a time). As shown, the low-frequency oscillator <NUM> feeds into the upper LC circuit of L1 <NUM> and C2 <NUM> and the high-frequency oscillator <NUM> feeds into the lower LC circuit of L2 <NUM> and C3 <NUM>. The upper LC circuit and the lower LC circuit share a common capacitor C1 <NUM>. The oscillating voltage is transferred from the ultrasonic driver circuit <NUM> to the piezoelectric transducer <NUM>/<NUM> via the inductive transformer <NUM>, which comprises inductor L3 <NUM>, inductor L4 <NUM> and inductor L5 <NUM>.

Here, the network for the low ultrasonic electrical frequency (F-low) is matched with a low physical natural frequency of the phacoemulsification assembly <NUM> and the high ultrasonic electrical frequency (F-high) is likewise matched with a higher physical natural frequency of the phacoemulsification assembly <NUM>. Hence, in this dual frequency driver <NUM>, the resonant frequencies of the impedance matching networks for the high and low ultrasonic frequency circuit configuration <NUM> closely match the natural frequencies of the phacoemulsification assembly <NUM>. Certain practical assemblies envision matching these frequencies within +/- <NUM>% being acceptable. Though not shown, a feedback system is envisioned to determine F-low and F-high (and the contribution of impedance matching network frequency responses) by reading the natural frequencies of the phacoemulsification assembly <NUM> and matching F-low and F-high against those natural frequencies to increase a resonance response.

Another aspect of a balanced system is providing an in-phase current and voltage that are produced along both the low-frequency path <NUM> and the high-frequency path <NUM>. <FIG> illustratively depicts a current/voltage graph <NUM> displaying a voltage plot <NUM> essentially in-phase with a current plot <NUM>. Both the voltage plot <NUM> and the current plot <NUM> are of a combined high and low frequency, exemplified in the voltage plot <NUM> of <FIG>. As shown, though the voltage plot <NUM> has a different amplitude than the current plot <NUM>, the two plots <NUM> and <NUM> are essentially in-phase. For reference, the current/voltage graph <NUM> present voltage <NUM> and current <NUM> in the y-axis versus time <NUM> in the x-axis. Voltage values <NUM> are displayed along the left y-axis and current values <NUM> are displayed along the right y-axis. Because in reality no two systems are alike and perfectly aligning the phases of current and voltage is impractical in production, certain assemblies envision essentially in-phase to mean within less than +/- <NUM>% having the same phase. Because the circuit elements described herein generally relate to LC networks, such as LC1 <NUM> and LC2 <NUM> of <FIG>, LC networks are preferably balanced to maintain in-phase current and voltage. Out of phase current and voltage generally leads to losses in the system, such as a buildup of heat instead of a clean transfer of signal, for example. Typically, when capacitors or inductors are involved in an AC circuit, the current and voltage do not peak at the same time. When a voltage is applied to an inductor, the inductor resists the change in current. The current builds up more slowly than the voltage, lagging it in time and phase. On the other hand, since the voltage applied to a capacitor is directly proportional to the charge on the capacitor, the current must lead the voltage in time and phase to conduct charge to the capacitor plate and raise the voltage. The fraction of a period difference between the peaks expressed in degrees is considered the phase difference. The phase difference is obviously less than or equal to <NUM> degrees. Those skilled in the art generally use the angle by which the voltage leads the current, which results in a positive phase for inductive circuits since current lags the voltage in an inductive circuit. The phase is negative for a capacitive circuit since current leads the voltage. Hence, in order to deliver the alternating current and voltage efficiently to the piezoelectric transducer <NUM>/<NUM>, certain assemblies envision balancing the LC1 circuit <NUM> to output essentially an in-phase alternating voltage and current.

With the present description in mind, below are some examples illustratively complementing some of the methods and apparatus to aid the reader. The elements called out below are examples provided to assist in the understanding of the present invention and should not be considered limiting.

In that light, a phacoemulsification arrangement <NUM> is shown in <FIG> comprising a needle <NUM> extending from a handpiece <NUM> that includes a piezoelectric crystals <NUM> connected to a dual frequency producing circuit <NUM> comprising a low-frequency oscillator <NUM> and a high-frequency oscillator <NUM>. The dual frequency producing circuit <NUM> electrically connected to the piezoelectric crystals <NUM> by way a wires <NUM> and <NUM>. The low-frequency oscillator <NUM> is configured to drive the piezoelectric transducer <NUM>/<NUM> to periodically vibrate the needle <NUM> at a low frequency defined as being less than <NUM> without producing a node of minimum amplitude along the needle <NUM>. The high-frequency oscillator <NUM> is configured to drive the piezoelectric crystals <NUM> to periodically vibrate the needle <NUM> at a high frequency of more than <NUM> while producing a single node of minimum amplitude <NUM> along the needle <NUM>.

The phacoemulsification arrangement <NUM> further envisioning wherein the dual frequency producing circuit is external to the needle <NUM> and the handpiece <NUM>.

The phacoemulsification arrangement <NUM> further pondering wherein the low-frequency oscillator <NUM> is operable with the high-frequency oscillator <NUM> to collectively periodically vibrate the needle <NUM> with a standing wave <NUM> that is defined by the low frequency standing wave <NUM> superimposed over the high frequency standing wave <NUM>. This can further comprise an actuator that changes a percent contribution of the low-frequency standing wave <NUM> inversely proportional to the high-frequency standing wave <NUM> when generating the standing wave <NUM>. Optionally, the standing wave <NUM> can comprise a single node of reduced amplitude <NUM> along the needle <NUM>, where the single node of reduced amplitude <NUM> is a higher amplitude than the single node of minimum amplitude.

The phacoemulsification arrangement <NUM> further imagining wherein the dual frequency producing circuit <NUM> comprises a low-frequency pathway and a high-frequency pathway, the low-frequency pathway comprising a low-frequency LC network <NUM> tied to the low-frequency oscillator <NUM> and the high-frequency pathway comprising a high-frequency LC network <NUM> tied to the high-frequency oscillator <NUM>. Here, a tapped output transformer <NUM> is inductively coupled to the low-frequency LC network <NUM> and the high-frequency LC network <NUM>. The tapped output transformer <NUM> is electrically connected to the piezoelectric crystal transducer <NUM>. The tapped output transformer <NUM> is configured to drive the piezoelectric crystals <NUM> with a low-frequency voltage from the low-frequency LC network <NUM> and a high-frequency voltage from the high-frequency LC network <NUM>, or combination of the high frequency voltage and the low-frequency voltage. This can further comprise a low-frequency circuit resonance corresponding to the low-frequency LC network <NUM> and a high-frequency circuit resonance corresponding to the high-frequency LC network <NUM>, the low frequency circuit resonance matching a first natural frequency of the needle <NUM> and the handpiece <NUM>, the high-frequency circuit resonance matching a second natural frequency of the <NUM> and the handpiece <NUM>.

In the phacoemulsification arrangement <NUM> the needle <NUM> and the handpiece <NUM> can be only applicable to cataract surgery using the phacoemulsification procedure.

The phacoemulsification arrangement <NUM> further contemplating wherein the dual frequency producing circuit <NUM> further comprising a low-frequency LC network <NUM> corresponding to and connected to the low-frequency oscillator <NUM> and the high-frequency LC network <NUM> corresponding to and connected to the high-frequency oscillator <NUM>, the low-frequency LC network <NUM> comprising electrical components that define a low natural electrical frequency response that matches a low natural physical frequency of the handpiece <NUM>. Thigh-frequency LC network <NUM> may further comprise different electrical components that define a high natural electrical frequency response that matches a high natural frequency of the handpiece <NUM>. The high natural frequency being a physical resonance of the handpiece <NUM> (and optionally the needle <NUM>) above <NUM>.

A phacoemulsification configuration <NUM> may comprise a dual frequency voltage producing circuit <NUM> comprising a low-frequency voltage pathway <NUM> that includes a low-frequency oscillator <NUM> and a low-frequency LC network <NUM> and a high-frequency voltage pathway <NUM> that includes a high-frequency oscillator <NUM> and a high-frequency LC network <NUM>. A needle <NUM> extends from a handpiece <NUM> wherein the handpiece <NUM> includes piezoelectric crystals <NUM>. The piezoelectric crystals <NUM> is electrically connected to the dual frequency voltage producing circuit <NUM>. When the high-frequency oscillator <NUM> is in a high-frequency on state and the low-frequency oscillator <NUM> is in a low-frequency off state, the needle <NUM> comprises a single node of minimum amplitude <NUM> (of <FIG>) that has essentially no vibration displacement. When the low-frequency oscillator <NUM> is in a low-frequency on state and the high-frequency oscillator <NUM> is in an off state, the needle <NUM> does not comprise a single non-displacement region (shown in <FIG> and <FIG> are directed to a tapered horn <NUM>, however these regions are not contingent on the tapered horn <NUM>.

The phacoemulsification configuration <NUM>, further contemplating wherein the phacoemulsification configuration <NUM> is only operably used (meaning during operation) for a cataract surgery.

The phacoemulsification configuration <NUM>, further imagining wherein the handpiece <NUM> comprises at least a low frequency mode <NUM> and a high frequency mode <NUM>. The low-frequency LC network <NUM> comprises a first set of electrical components, such as one or more capacitors, inductors, resistors, etc., that electrically match the low frequency mode <NUM> within +/- <NUM>% and the high-frequency LC network <NUM> comprises a second set of electrical components that electrically match the high frequency mode <NUM> within +/- <NUM>%.

The phacoemulsification configuration <NUM> further considering that the low-frequency pathway <NUM> and the high-frequency pathway <NUM> are located externally from the handpiece <NUM> and the needle <NUM>. The externally located circuit may be in a power unit or box that connects to the handpiece <NUM> via wires or cables.

The phacoemulsification configuration <NUM> further comprising a frequency mixer configured to produce a combined frequency output voltage, which is a combination of a low-frequency output voltage <NUM> from the low-frequency oscillator <NUM> when in the low-frequency on state and a high-frequency output voltage <NUM> from the high-frequency oscillator <NUM> when in the high-frequency on state. When the piezoelectric crystal transducer <NUM> is subjected to the combination frequency output voltage, the hollow phacoemulsification needle <NUM> comprises a single node of reduced amplitude <NUM> (of <FIG>), the single note of reduced amplitude <NUM> has higher displacement than the single node of minimum amplitude870 (of <FIG>). The frequency mixer (such as a tapped transformer or amplifier/s) may be an operator controlled actuator that adjusts the high-frequency output voltage <NUM> inversely proportional to the low-frequency output voltage <NUM>.

Also described is a method for driving a phacoemulsification assembly <NUM>. The phacoemulsification assembly <NUM> comprising a dual frequency producing circuit <NUM> electrically connected to a phacoemulsification assembly <NUM> comprising a needle <NUM> extending from a handpiece <NUM>. The handpiece <NUM> comprising piezoelectric crystals <NUM>. The steps can include generating one of an independent high-frequency ringing in the needle <NUM>, an independent low-frequency ringing in the needle <NUM> or a combination high-low frequency ringing in the needle <NUM>. The high-frequency ringing of the needle <NUM> is produced by energizing the piezoelectric crystals <NUM> with a high-frequency voltage <NUM> from the dual frequency producing circuit <NUM>. The high-frequency ringing generates a high-frequency standing wave <NUM> comprising a single node of minimum amplitude <NUM> that is along the needle <NUM>. The low-frequency ringing of the needle <NUM> is produced by energizing the piezoelectric crystals <NUM> with a low-frequency voltage <NUM> from the dual frequency producing circuit <NUM>. The low-frequency ringing of the needle <NUM> generates a low-frequency standing wave <NUM> that is devoid of any node of minimum amplitude <NUM> along the needle <NUM> (see <FIG> for example).

The method further comprises producing the combination high-low frequency ringing of the needle <NUM> by energizing the piezoelectric transducer <NUM>/<NUM> with both the low-frequency voltage <NUM> combined with the high-frequency voltage <NUM>, a combined frequency standing wave <NUM> comprising a single node of low amplitude <NUM> along the needle <NUM> at the combination high-low frequency ringing, the node of low amplitude <NUM> is a higher amplitude then the node of minimum amplitude <NUM>.

The method further contemplates the dual frequency circuit <NUM> comprising a low-frequency voltage pathway <NUM> that includes a low-frequency oscillator <NUM> and a low-frequency LC network <NUM> and a high-frequency voltage pathway <NUM> comprising a high-frequency oscillator <NUM> and a high-frequency LC network <NUM>. The low-frequency voltage pathway <NUM> provides the low-frequency voltage <NUM> and the high-frequency voltage pathway <NUM> provides the high-frequency voltage <NUM>. The method further comprises balancing at least a portion of the low-frequency voltage pathway <NUM> with electrical components that electrically oscillate within +/- <NUM>% of a low natural frequency of at least the handpiece <NUM>.

Yet another phacoemulsification device <NUM> comprises: a handpiece <NUM> that includes a piezoelectric transducer <NUM>/<NUM> and a step horn <NUM>; a needle <NUM> having a free distal tip <NUM> and a supported end structure <NUM> that is attached to the handpiece <NUM>, the supported end structure <NUM> includes external threads that mate with internal threads in the handpiece <NUM>, the needle <NUM> having a substantially cylindrical portion extending from the free distal tip <NUM> towards the step horn <NUM>; a tapered section <NUM> in step horn <NUM>, the step horn <NUM> is between the piezoelectric transducer <NUM>/<NUM> and the needle <NUM>; and the piezoelectric transducer <NUM>/<NUM> configured to periodically vibrate the needle <NUM> at either a low mode (frequency) or a high mode (frequency), the substantially cylindrical portion devoid of a node of minimum amplitude at the low mode and the substantially cylindrical portion of needle <NUM> possessing a single node of minimum amplitude <NUM> at the high mode.

In the surgical instrument the low mode may be below <NUM> and the high mode may be equal or above <NUM>.

In the surgical instrument the tapered section may be selected from a group consisting of a geometry that is conical, elliptical, Gaussian, exponential, and Fourier.

In the surgical instrument the piezoelectric transducer <NUM>/<NUM> may be configured to switch between the high mode and the low mode by a surgeon command.

In the surgical instrument the tapered section <NUM> may extend approximately to the supported end structure <NUM>.

In the surgical instrument the piezoelectric transducer <NUM>/<NUM> may be configured to switch automatically between the high mode and the low mode by a command received from the phaco machine controller <NUM>.

In the surgical instrument there may be a single node of minimum amplitude <NUM> along the tapered section <NUM> at the high mode and a single node of minimum amplitude <NUM> along the tapered substantially cylindrical section of the needle <NUM>, which is shown by way of example in <FIG>.

In the surgical instrument the free distal tip <NUM> may be configured to periodically vibrate at a high amplitude in both the low mode and the high mode.

In the surgical instrument the tapered section may be integral with the handpiece.

In the surgical instrument the piezoelectric transducer <NUM>/<NUM> may be adapted to switch between the high mode and the low mode after a predetermined time interval.

Also described is a method to drive oscillations in a surgical instrument <NUM> during phacoemulsification, the method comprising: providing a handpiece <NUM> that includes a piezoelectric transducer <NUM>/<NUM> and a step horn <NUM>, the step horn <NUM> possessing a tapered section <NUM> that tapers towards a distal handpiece end <NUM>, a needle <NUM> having a free distal tip <NUM> and a supported end structure <NUM> that is attached to the distal handpiece end <NUM>, the needle <NUM> possessing a length being defined along a longitudinal axis <NUM> of the needle <NUM>; energizing the piezoelectric transducer <NUM>/<NUM> to periodically longitudinally expand and contract in at least two ultrasonic driving frequencies that rings the needle <NUM> with at least either a high ultrasonic standing wave <NUM> or a low ultrasonic standing wave <NUM>; inserting the needle <NUM> in an eye <NUM>; after the inserting step, energizing the piezoelectric transducer <NUM>/<NUM> to drive the needle <NUM> at either the high ultrasonic standing wave <NUM> or the low ultrasonic standing wave <NUM>, only the high ultrasonic standing possessing a node of minimum amplitude <NUM> along the length <NUM> of the needle <NUM>.

In the method the high and the low standing waves may have a proximal node of minimum amplitude <NUM> along the tapered section <NUM>.

In the method the high and the low standing waves may have a distal anti-node of maximum amplitude <NUM>/<NUM> at the free distal tip <NUM>.

The method may further comprise switching the ultrasonic driving frequencies from ringing the needle <NUM> at the high ultrasonic standing wave <NUM> to the low ultrasonic standing wave <NUM> after a predetermined amount of time.

The method may further comprise switching from the low ultrasonic standing wave <NUM> to the high ultrasonic standing wave <NUM> when the hollow titanium needle <NUM> becomes at least partially occluded and switching from the high ultrasonic standing wave <NUM> to the low ultrasonic standing wave <NUM> when the hollow titanium needle <NUM> is no longer partially occluded.

In the method the low ultrasonic standing wave <NUM> may be defined by a frequency below <NUM> and the high ultrasonic standing wave <NUM> may be defined by a frequency equal to or above <NUM>.

In the method the tapered section <NUM> may be defined by a profile that is selected from a group consisting of a geometry that is conical, elliptical, Gaussian, exponential, and Fourier.

Also disclosed is a phacoemulsification device comprising: a phacoemulsification device <NUM> possessing a handpiece <NUM> that tapers <NUM> to a tapered end <NUM>, a needle <NUM> attached to the tapered end <NUM>, the needle <NUM> having a substantially cylindrical portion that extends from approximately the tapered end <NUM> to a free distal tip <NUM>; and a piezoelectric transducer <NUM>/<NUM> configured to drive the needle <NUM> with either a low ultrasonic standing wave <NUM> or a high ultrasonic standing wave <NUM>, the high ultrasonic standing wave <NUM> having a single node of minimum amplitude <NUM> along the needle <NUM>, the low ultrasonic standing wave <NUM> devoid of any node of minimum amplitude along the needle <NUM>.

In the phacoemulsification device the piezoelectric transducer <NUM>/<NUM> may be configured to change between the low ultrasonic standing wave <NUM> and the high ultrasonic standing wave <NUM>.

In the phacoemulsification device the low ultrasonic standing wave <NUM> may have a frequency of less than <NUM> and the high ultrasonic standing wave <NUM> may have a frequency of more than or equal to <NUM>.

Also disclosed is a phacoemulsification device <NUM> comprising: a handpiece <NUM> that includes a piezoelectric transducer <NUM>/<NUM>; a needle <NUM> having a free distal tip <NUM> and a supported end structure <NUM> that is attached to the handpiece <NUM>, the supported end structure <NUM> includes external threads that mate with internal threads in the handpiece <NUM>, the needle <NUM> having a substantially cylindrical portion extending from the free distal tip <NUM> towards the handpiece <NUM>; and the piezoelectric transducer <NUM>/<NUM> configured to periodically vibrate the needle <NUM> with a standing wave <NUM> defined by a high frequency mode <NUM> superimposed over a low frequency mode <NUM>, the standing wave <NUM> defining a single semi-node of low amplitude <NUM> along the substantially cylindrical portion of needle <NUM> and an anti-node of high amplitude <NUM> at the free distal tip <NUM>.

In the phacoemulsification device <NUM> the low frequency mode <NUM> may be below <NUM> and the high frequency mode <NUM> may be equal or above <NUM>.

In the phacoemulsification device <NUM> there may be a tapered section <NUM> between the piezoelectric transducer <NUM>/<NUM> and the substantially cylindrical portion of the needle <NUM>.

In the phacoemulsification device <NUM> the piezoelectric transducer <NUM>/<NUM> may be configured to be adjusted by a surgeon command to increase or decrease power of the high frequency mode <NUM> inversely to the low frequency mode <NUM>.

In the phacoemulsification device <NUM> the tapered section <NUM> may extend approximately to the supported end structure <NUM>.

In the phacoemulsification device <NUM> the piezoelectric transducer <NUM>/<NUM> may be configured to adjust power of the high frequency mode <NUM> inversely proportional to the low frequency mode <NUM> by a command received from the phaco machine controller <NUM>.

In the phacoemulsification device <NUM> there may be a single node of low amplitude <NUM> located along the tapered section <NUM>.

In the phacoemulsification device <NUM> the low frequency mode <NUM> and the high frequency mode <NUM> may both vibrate longitudinally along the needle <NUM>.

In the phacoemulsification device <NUM> the tapered section <NUM> may be selected from a group consisting of a geometry that is conical, elliptical, Gaussian, exponential, and Fourier.

In thee phacoemulsification device <NUM> embodiment the piezoelectric transducer <NUM>/<NUM> may be adapted to adjust power of the high frequency mode <NUM> inversely proportional to the low frequency mode <NUM>.

Also described is a method to drive oscillations in a phacoemulsification device <NUM> during phacoemulsification, the phacoemulsification procedure method comprising: providing a handpiece <NUM> that includes a piezoelectric transducer arrangement <NUM>/<NUM>, a needle <NUM> having a free distal tip <NUM> and a supported end structure <NUM> that is attached to the distal handpiece end <NUM>, the needle <NUM> possessing a length being defined along a longitudinal axis <NUM> of the needle <NUM>; energizing the piezoelectric transducer <NUM>/<NUM> to periodically longitudinally expand and contract in at least two simultaneously driving ultrasonic frequencies <NUM> made up of at least a high ultrasonic frequency <NUM> and a low ultrasonic frequency <NUM>, the at least two simultaneously driving ultrasonic frequencies <NUM> ring the needle <NUM> with a standing wave <NUM> defined by at least a high ultrasonic standing wave <NUM> superimposed over a low ultrasonic standing wave <NUM>; inserting the needle <NUM> in an eye <NUM>; and after the inserting step, energizing the piezoelectric transducer <NUM>/<NUM> to drive the needle <NUM> at the simultaneously driving ultrasonic frequencies <NUM>, the standing wave <NUM> defining a single semi-node of low amplitude <NUM> along the needle <NUM> and an anti-node of high amplitude <NUM> at the free distal tip <NUM>.

In the phacoemulsification procedure method the handpiece <NUM> may further possess a tapered section <NUM> that tapers towards a distal handpiece end <NUM>.

In the phacoemulsification procedure the standing wave <NUM> may have a proximal node of low amplitude <NUM> along the tapered section <NUM>.

In the phacoemulsification procedure method embodiment the anti-node of high amplitude <NUM> may be a distal anti-node of maximum amplitude <NUM> at the free distal tip <NUM>.

The phacoemulsification procedure method may comprise increasing power to the high frequency mode <NUM> while inversely decreasing the power to the low frequency mode <NUM>, or decreasing the power to the high frequency mode <NUM> while inversely increasing the power to the low frequency mode <NUM>.

The phacoemulsification procedure method may further comprise increasing the power to the high frequency mode <NUM> while inversely decreasing the power to the low frequency mode <NUM> when the needle <NUM> becomes at least partially occluded and switching from the high ultrasonic frequency mode <NUM> to the low ultrasonic frequency mode <NUM> when the needle <NUM> is no longer partially occluded.

In the phacoemulsification procedure method the low ultrasonic frequency <NUM> may be below <NUM> and the high ultrasonic frequency <NUM> may be equal to or above <NUM>.

Also disclosed is a hand-held surgical instrument comprising: a phacoemulsification device <NUM> possessing a handpiece <NUM>, a needle <NUM> attached to the handpiece <NUM>, the needle <NUM> having a substantially cylindrical portion that extends from approximately the handpiece <NUM> to a free distal tip <NUM>; and a piezoelectric transducer <NUM>/<NUM> configured to drive the needle <NUM> with at least two simultaneous driving frequencies <NUM> and <NUM> that define a standing wave <NUM> with a single semi-node of low amplitude <NUM> along the hollow titanium needle <NUM> and an anti-node of high amplitude <NUM> at the free distal tip <NUM>.

In the hand-held surgical instrument the transducer <NUM>/<NUM> may be configured to increase power to the high frequency mode <NUM> while inversely decreasing the power to the low frequency mode <NUM>, or decrease the power to the high frequency mode <NUM> while inversely increasing the power to the low frequency mode <NUM>.

In the hand-held surgical instrument at least two simultaneous driving frequencies <NUM> may comprise a high ultrasonic frequency <NUM> of equal to or more than <NUM> and a low ultrasonic frequency <NUM> of less than <NUM>.

It is to be understood that even though numerous characteristics and advantages have been set forth in the foregoing description, together with the details of the structure and function, this disclosure is illustrative only, and changes may be made in detail, especially in matters of structure and arrangement of parts to the full extent indicated by the broad general meaning of the terms used herein. For example, though modulating between a high ultrasonic frequency and an ultrasonic (or low ultrasonic) frequency is described, it is contemplated that multiple ultrasonic frequencies and high ultrasonic frequencies can be used while still maintaining substantially the same functionality. Furthermore, though various LC circuit designs are described herein to provide structure, they are by example and by no way are limiting to the various potential circuit configurations that can be constructed to meet the functionality. The specification and drawings are to be regarded as illustrative and exemplary rather than restrictive. For example, the word "preferably," and the phrase "preferably but not necessarily," are used synonymously herein to consistently include the meaning of "not necessarily" or optionally. "Comprising," "including," and "having," are intended to be open-ended terms.

Claim 1:
A phacoemulsification arrangement (<NUM>) for a phacoemulsification procedure, comprising:
a needle (<NUM>) extending from a handpiece (<NUM>) that includes a piezoelectric transducer (<NUM>); and
a dual frequency producing circuit (<NUM>) comprising a low-frequency oscillator (<NUM>) and a high-frequency oscillator (<NUM>),
the dual frequency producing circuit (<NUM>) is electrically connected to the piezoelectric transducer (<NUM>),
the low-frequency oscillator (<NUM>) is configured to drive the piezoelectric transducer (<NUM>) that periodically vibrates the needle (<NUM>) at a low frequency of less than <NUM>, and
the high-frequency oscillator (<NUM>) is configured to drive the piezoelectric transducer (<NUM> that periodically vibrates the needle (<NUM>) at a high frequency of greater than or equal to <NUM> while producing a single node (<NUM>) of minimum amplitude along the needle (<NUM>),
characterized in that the low-frequency oscillator (<NUM>) is operable with the high-frequency oscillator (<NUM>) to collectively periodically vibrate the needle (<NUM>) with a hybrid standing wave (<NUM>) that is defined by a low frequency standing wave (<NUM>) superimposed over a high frequency standing wave (<NUM>).