Patent Publication Number: US-2022233353-A1

Title: Ophthalmic cutting instruments having integrated aspiration pump

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/778,755 filed Jan. 31, 2020, which claims the benefit of priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application Ser. Nos. 62/800,198, filed Feb. 1, 2019, 62/815,673, filed Mar. 8, 2019, and 62/868,688, filed Jun. 28, 2019. The disclosures of which are hereby incorporated by reference in their entireties. 
    
    
     FIELD 
     The present technology relates generally to ophthalmic microsurgical tools and systems, in particular, ophthalmic microsurgical tools and systems having integrated pumping. 
     BACKGROUND 
     Certain types of conventional ophthalmic surgery require breaking up lenticular tissue and solid intraocular objects, such as the intraocular lens or vitreous into pieces so that it can be extracted from the eye. For example, extraction of lenses for cataract surgery is one of the most common outpatient surgical fields with more than 3 million cases performed annually in the United States alone. During cataract surgery a commonly used method for lens extraction is phacoemulsification, which incorporates using ultrasonic energy to break up the lens and then aspiration to remove the lens fragments through the instrument. Other methods of lens fragmentation and extraction may include the use of instruments such as hooks, knives, or laser to break up the lens into fragments and then extract through an incision in the cornea in an ab interno approach. Intraocular, ab interno fragmentation of the lenticular tissue is extremely important in cataract surgery in order to allow removal of cataracts from ocular incisions that are typically not exceeding 2.8-3.0 mm. 
     Typical phacoemulsification systems include a console in operative communication with a phacoemulsification hand piece. The console typically includes a cabinet, including a power supply, a pump, electronic and associated hardware. The console provides the control of the electronics of the hand piece, aspiration, and irrigation. The hand piece includes a resonating bar directly attached to a set of piezoelectric crystals on a first end and a needle-like cutting tube on the second end. The crystals supply ultrasonic vibration needed to drive the resonating bar and attached cutting tube during phacoemulsification. 
     During typical phacoemulsification procedures, the tip of the cutting tube extending past the distal end of the irrigation sleeve is inserted into the anterior segment of the eye through a small incision in the outer tissue of the eye. The tip of the cutting tube is brought into contact with the lens of the eye so that the vibrating tip fragments the lens. The fragments are aspirated out of the eye through the inner lumen of the cutting tube, along with any irrigation fluid provided to the eye during the procedure through the irrigation sleeve and directed toward a waste container. During cutting, irrigation fluid is delivered to the eye (i.e. passively or actively) through the irrigation sleeve positioned over the cutting tube. The irrigation fluid is intended to maintain the pressure balance within the eye and prevent collapse of the anterior chamber during the removal of the emulsified lens. 
     A challenge associated with conventional phaco devices and other devices using a remote vacuum source is that the suction lines are quite long and flexible contributing to the fluidic system compliance. Lastly, the system often contains compressible gas or other material that further adds to the compliance of the system. Long, compliant suction lines containing compressible material affects the responsive times at the tip when suction is turned on and off. Yet another problem with some systems, such as venturi-based systems, is that the waste fluid disposal enclosure is also exposed to vacuum pressure and, as such, the container and gas or other compressible material therein, also responds to changes in pressure and further contributing to the delay in initiation and termination of suction at the tip and contributing to the low responsiveness of some systems. 
     Conventional methods and devices for delivery of irrigation to an eye, for example during cataract surgery, may also use a substantial amount of circulated irrigation balanced saline solution (BSS). For example, bottles and bags of BSS may be in the range of 250 cc to 500 cc. Corneal endothelial cells can be damaged in multiple ways including the amount of ultrasonic energy delivered to the eye as well the amount of irrigation fluid that circulates through the anterior chamber. Additionally, when larger amounts of irrigation fluid are used, flow rates through the eye are higher and therefore additional turbulence of the irrigating fluid may exist and further cause corneal endothelial cell damage. 
     SUMMARY 
     According to a first aspect, disclosed is a device for extracting lens material from an eye. The device includes a distal, disposable portion releaseably coupleable to a proximal, reusable portion. The distal, disposable portion includes a cutting tube having a distal cutting tip and an inner lumen having an open distal end. The cutting tube is sized and configured to extend through an anterior chamber of the eye and to a capsular bag. The distal, disposable portion includes an aspiration pump housed within the disposable portion and fluidly coupled to the inner lumen of the cutting tube and a cutting tube drive mechanism configured to oscillate the cutting tube. When in use, the device is configured to aspirate lens material from the capsular bag into the inner lumen. The proximal, reusable portion is configured to remain outside of the eye. The proximal, reusable portion includes an aspiration pump motor configured to drive the aspiration pump; and a coupler for releaseably operatively coupling the pump motor to the aspiration pump. 
     The aspiration pump can be a peristaltic pump. The peristaltic pump can be a linear peristaltic pump having a central camshaft extending longitudinally through a symmetrical double chamber pumping manifold. The central camshaft can have a rotational axis that is coaxially aligned with a longitudinal axis of the distal, disposable portion. The aspiration pump motor rotates the central camshaft. The linear peristaltic pump can further include two tubes extending through the pumping manifold, each of the two tubes having a longitudinal axis that is positioned parallel with the rotational axis of the central camshaft. A first tube of the two tubes is positioned on one side of the camshaft and a second tube of the two tubes is positioned on a second, opposite side of the camshaft. The linear peristaltic pump can further include a proximal flow path and a distal flow path. The proximal flow path can split into two flow paths connected on a proximal end with the two tubes within the pumping manifold. The two tubes can combine distal to the pumping manifold into the distal flow path. The camshaft can further include a plurality of lobed cams that work in time to drive a plurality of cam followers towards and away from the two tubes to create sequential, progressive compression of the two tubes to push a fluid volume toward the distal flow path. Motion of the plurality of cam followers can be in a plane perpendicular to the rotational axis of the camshaft and to the longitudinal axis of the two tubes. The plurality of cam followers can sequentially compress the two tubes in a wave-like fashion. The plurality of cam followers can apply no force in a direction of the longitudinal axis of the two tube and generate little to no friction on the two tubes. 
     The device can further include an external vacuum source operatively releasably coupleable to at least one of the proximal, reusable portion and the distal, disposable portion. The external vacuum source can be configured to provide a level of continuous negative pressure within the inner lumen. The level of continuous negative pressure can be less than a level of the negative pressure generated by the aspiration pump of the distal, disposable portion. 
     The cutting tube drive mechanism can cause oscillatory motion of the cutting tube via a mechanical hinge. The cutting tube drive mechanism can incorporate less than 2 nodal inflection points between a point of application of a drive force and the distal cutting tip of the cutting tube. The cutting tube drive mechanism can include a base, a rocker, and a pivot pin, the rocker being movably coupled to the base by the pivot pin and configured to rotate relative to the base around a rotational axis of the pivot pin. The cutting tube can extend through a center of the rocker and the pivot pin is substantially aligned along the longitudinal axis of the cutting tube creating a fulcrum for the rocker. 
     The drive mechanism can further a piezoelectric stack and a spring stack, the piezoelectric stack and the spring stack being positioned on opposite sides of the cutting tube. The spring stack can create an upward force against a first end of rocker urging a second, opposite end of the rocker downward against the piezoelectric stack. The piezoelectric stack can expand under varying voltage rotating the rocker about the rotational axis of the pivot pin causing the cutting tube to move in at least one direction. Retraction of the piezoelectric stack can allow the upward force of the spring stack against the first end of the rocker to urge the second, opposite end of the rocker downward maintaining contact with the retracting piezoelectric stack. The drive mechanism can further include a motor-driven cam and cam follower coupled to the rocker. The drive mechanism can further include a motor and a motor shaft, the motor shaft having an offset weight configured to cause motion of the rocker as the motor shaft spins. The rocker can be a straight rocker and the pivot pin is aligned with the rocker along the longitudinal axis of the cutter tube. The rocker can be an offset rocker and the pivot pin is positioned proximal to the rocker along the longitudinal axis of the cutter tube. 
     The cutting tube drive mechanism can create a drive force applied to generate longitudinal oscillatory motion and/or torsional oscillatory motion. The oscillatory motion can be in an ultrasonic frequency range or in a frequency range that is less than ultrasonic. A frequency of oscillation of the distal cutting tip can be between about 0.5 Hz to 5000 Hz. 
     The cutting tube can incorporate a non-circular cross-sectional geometry along at least a portion of its length. The non-circular cross-sectional geometry can include oval, elliptical, lentoid, tear-drop, or diamond shape. The cutting tube can incorporate at least a first tapered profile extending laterally from a central axis of the cutting tube. The cutting tube can have an asymmetric cross-section forming a single tapered profile extending from one side of the cutting tube and a circular profile on an opposite side of the cutting tube. The cutting tube can have a cross-sectional shape that varies along its length. The cutting tube can incorporate a non-circular geometry in only a distal-most length of the cutting tube. The distal-most length can be approximately 1 mm. 
     The proximal, reusable portion can further include a throttle mechanism for varying a speed of the aspiration pump motor, the throttle mechanism operatively coupled to an actuator. The device can further include an irrigation lumen coupleable to a source of irrigation fluid. The irrigation lumen can include an annular space at least in part surrounding the cutting tube. 
     In an interrelated aspect, provided is a device for extracting lens material from an eye including a cutting tube having a distal cutting tip and an inner lumen, the cutting tube sized and configured to extend through an anterior chamber of the eye and to a capsular bag; and a cutting tube drive mechanism configured to oscillate the cutting tube via a mechanical hinge. The cutting tube drive mechanism incorporates less than 2 nodal inflection points between a point of application of a drive force and the distal cutting tube of the cutting tube. 
     The cutting tube drive mechanism can include a base, a rocker, and a pivot pin, the rocker being movably coupled to the base by the pivot pin and configured to rotate relative to the base around a rotational axis of the pivot pin. The cutting tube can extend through a center of the rocker and the pivot pin is substantially aligned along the longitudinal axis of the cutting tube creating a fulcrum for the rocker. The drive mechanism can further include a piezoelectric stack and a spring stack, the piezoelectric stack and the spring stack being positioned on opposite sides of the cutting tube. The spring stack can create an upward force against a first end of rocker urging a second, opposite end of the rocker downward against the piezoelectric stack. The piezoelectric stack can expand under varying voltage rotating the rocker about the rotational axis of the pivot pin causing the cutting tube to move in at least one direction. Retraction of the piezoelectric stack can allow the upward force of the spring stack against the first end of the rocker to urge the second, opposite end of the rocker downward maintaining contact with the retracting piezoelectric stack. The drive mechanism can further include a motor-driven cam and cam follower coupled to the rocker. The drive mechanism can further include a motor and a motor shaft, the motor shaft having an offset weight configured to cause motion of the rocker as the motor shaft spins. The rocker can be a straight rocker and the pivot pin aligned with the rocker along the longitudinal axis of the cutter tube. The rocker can be an offset rocker and the pivot pin positioned proximal to the rocker along the longitudinal axis of the cutter tube. The cutting tube drive mechanism can create a drive force applied to generate longitudinal oscillatory motion and/or torsional oscillatory motion. The oscillatory motion can be in an ultrasonic frequency range or in a frequency range that is less than ultrasonic. The frequency of oscillation of the distal cutting tip can be between about 0.5 Hz to 5000 Hz. 
     The device can further include an aspiration pump fluidly coupled to the inner lumen of the cutting tube, wherein, in use, the device is configured to aspirate lens material from the capsular bag into the inner lumen. The aspiration pump can be a peristaltic pump. The peristaltic pump can be a linear peristaltic pump having a central camshaft extending longitudinally through a symmetrical double chamber pumping manifold, the central camshaft having a rotational axis that is coaxially aligned with a longitudinal axis of the distal, disposable portion. The camshaft can include a plurality of lobed cams that work in time to drive a plurality of cam followers towards and away from two tubes extending through the pumping manifold to create sequential, progressive compression of the two tubes to push a fluid volume toward the distal flow path. Each of the two tubes can include a longitudinal axis that is positioned parallel with the rotational axis of the central camshaft. A first of the two tubes can be positioned on one side of the camshaft and a second tube of the two tubes is positioned on a second, opposite side of the camshaft. Motion of the plurality of cam followers can be in a plane perpendicular to the rotational axis of the camshaft and to the longitudinal axis of the two tubes. The plurality of cam followers can sequentially compress the two tubes in a wave-like fashion. The plurality of cam followers can apply no force in a direction of the longitudinal axis of the two tubes and generate little to no friction on the two tubes. 
     In an interrelated aspect, provided is a device for extracting lens material from an eye including a cutting tube having a distal cutting tip and an inner lumen having an open distal end, the cutting tube sized and configured to extend through an anterior chamber of the eye and to a capsular bag, wherein, in use, the device is configured to aspirate lens material from the capsular bag into the inner lumen. The device includes a cutting tube drive mechanism configured to oscillate the cutting tube torsionally. The cutting tube incorporates a non-circular cross-sectional geometry along at least a portion of its length. 
     The oscillatory motion can be in an ultrasonic frequency range or in a frequency range that is less than ultrasonic. The non-circular cross-sectional geometry can include oval, elliptical, lentoid, tear-drop, or diamond shape. The non-circular cross-sectional geometry can incorporate at least a first tapered profile extending laterally from a central axis of the cutting tube. The non-circular cross-sectional geometry can be asymmetric and incorporate a single tapered profile extending from one side of the cutting tube and a circular profile on an opposite side of the cutting tube. The cutting tube can incorporate the non-circular cross-sectional geometry in only a distal-most length of the cutting tube. The distal-most length can be approximately 1 mm. 
     In some variations, one or more of the following can optionally be included in any feasible combination in the above methods, apparatus, devices, and systems. More details of the devices, systems, apparatus, and methods are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other aspects will now be described in detail with reference to the following drawings. Generally speaking, the figures are not to scale in absolute terms or comparatively, but are intended to be illustrative. Also, relative placement of features and elements may be modified for the purpose of illustrative clarity. 
         FIG. 1  is a block diagram of a phacoemulsification system; 
         FIG. 2A  is a cross-sectional view of a phacoemulsification hand piece; 
         FIG. 2B  is a distal-end perspective view of a cutting tube incorporating tapered profile geometry; 
         FIG. 2C  is a planform view of the cutting tube of  FIG. 2B ; 
         FIGS. 2D-2G  are cross-sectional views of implementations of cutting tubes incorporating tapered profiles of varying geometry; 
         FIGS. 2H-2J  are cross-sectional views of implementations of cutting tubes incorporating tapered profiles of varying external and internal (luminal) geometry; 
         FIG. 2K  is a cross-sectional schematic view of a Kelman style cutting tube; 
         FIG. 2L  is a distal-end view of the cutting tube of  FIG. 2K  incorporating tapered profile geometry; 
         FIG. 2M  is a distal-end perspective view of a cutting tube incorporating an asymmetric tapered profile geometry; 
         FIG. 3  is a block diagram of a phacoemulsification system according to an implementation including a hand piece with an integrated aspiration pump; 
         FIG. 4  is a block diagram of the phacoemulsification system of  FIG. 3  illustrating the fluidics components; 
         FIG. 5A  shows an implementation of a hand piece of  FIG. 3 ; 
         FIG. 5B  shows the hand piece of  FIG. 5A  with the durable portion removed from the disposable portion; 
         FIG. 5C  shows the hand piece of  FIG. 5B  illustrating a pulsatile vacuum valve; 
         FIG. 6  shows a distal end region of the hand piece having an irrigation sleeve attached over a lens cutting tip; 
         FIG. 7A  shows the distal end region of the hand piece of  FIG. 6  with the irrigation sleeve and tip removed; 
         FIG. 7B  shows the lens cutting tip of  FIG. 6 ; 
         FIG. 7C  shows a bag polishing tip having a bag polishing nub for use with the phacoemulsification hand piece of  FIG. 7A ; 
         FIG. 8A  shows a bag polishing tip attached to the hand piece of  FIG. 6  and an irrigation sleeve attached over the bag polishing protective sleeve; 
         FIG. 8B  shows a bag polishing tip attached to a hand piece and an irrigation sleeve attached over the bag polishing protective sleeve; 
         FIG. 8C  is a cross-sectional view of the bag polishing tip of  FIG. 8B ; 
         FIGS. 9A-9B  shows the lens cutting tip of the hand piece of  FIG. 7B  having an irrigation reservoir; 
         FIG. 10A  shows a symmetric, sinusoidal motion profile of a cutting tube; 
         FIG. 10B  shows an asymmetric, non-sinusoidal motion profile of a cutting tube; 
         FIG. 10C  shows a symmetric motion profile for a cutting tube where an extension speed profile is the same as a retraction speed profile of the elongate member; 
         FIG. 10D  shows an asymmetric motion profile for a cutting tube where an extension speed profile differs from a retraction speed profile of the cutting tube; 
         FIGS. 10E-10F  show additional examples of extension speed profiles and retraction speed profiles of a cutting tube where the profiles are different; 
         FIG. 10G  shows a non-sinusoidal movement of the distal tip of a cutting tube (bottom panel) relative to its extension speed profile (top panel); 
         FIG. 11A  shows an implementation of a vacuum profile for a piston pump of the hand piece; 
         FIGS. 11B-11D  show overlap between an asymmetric, non-sinusoidal motion profile for a cutting tube (solid line) and a vacuum profile for aspiration through the cutting tube (hatched line) with the piston pump; 
         FIG. 11E  shows overlap between an asymmetric, non-sinusoidal motion profile for a cutting tube (solid line) and a vacuum profile for aspiration through the cutting tube (hatched line) with the piston pump; 
         FIG. 11F  shows overlap between an asymmetric, non-sinusoidal motion profile for a cutting tube (solid line) and a vacuum profile for aspiration through the cutting tube (hatched line) 
         FIG. 11G  shows an implementation of a vacuum profile for a peristaltic pump in the hand piece; 
         FIG. 12  shows a perspective view of the durable and disposable portions of an implementation of a hand piece separated from one another; 
         FIGS. 13A-13B  show side views of an implementation of a hand piece for cutting and aspirating material from an eye configured to be used with a microsurgical control system; 
         FIGS. 13C-13E  show various view of a rotating cam of the hand piece of  FIGS. 13A-13B . 
         FIGS. 13F-13L  are additional views of various components of the device of  FIGS. 13A-13B ; 
         FIGS. 14A-14B  illustrate views of a hand piece for cutting and aspirating material from an eye; 
         FIG. 15A  schematically illustrates piston movements on a cam surface; 
         FIGS. 15B-15D  schematically illustrate piston movements on another cam surface; 
         FIG. 16A  illustrates an implementation of a cutter tube drive mechanism incorporating an off-set rocker; 
         FIGS. 16B-16C  are side and cross-sectional views, respectively, of the cutter tube drive mechanism of  FIG. 16A ; 
         FIG. 16D  illustrates the implementation of  FIG. 16A  having a dome-shaped interface between the piezoelectric stack and the off-set rocker; 
         FIG. 17A  illustrates an implementation of a cutter tube drive mechanism incorporating a straight rocker; 
         FIGS. 17B-17C  are side and cross-sectional views, respectively, of the cutter tube drive mechanism of  FIG. 17A ; 
         FIG. 18  is a perspective view of an implementation of a cutter tube drive mechanism incorporating a hinge clamp; 
         FIG. 19A  illustrates an implementation of a cutter tube drive mechanism incorporating a parallel Belleville spring; 
         FIGS. 19B-19C  are side and cross-sectional views, respectively, of the cutter tube drive mechanism of  FIG. 19A ; 
         FIG. 20A  illustrates an implementation of a cutter tube drive mechanism; 
         FIG. 20B  is a cross-sectional view of the cutter tube drive mechanism of  FIG. 20A ; 
         FIG. 21A  illustrates an implementation of a cutter tube drive mechanism incorporating a motor-driven cam; 
         FIG. 21B  is the cutter tube drive mechanism of  FIG. 21A  with the base hidden; 
         FIG. 21C  is a close-up view of the cam mechanism of  FIG. 21A ; 
         FIG. 21D  is a view of the cam mechanism of  FIG. 21C  with the cam hidden; 
         FIG. 22A  shows a perspective view of an implementation of an aspiration pump configured to be integrated within a working portion of a microsurgical instrument; 
         FIG. 22B  shows a top view of the aspiration pump of  FIG. 22A ; 
         FIGS. 22C-22D  show a camshaft of the aspiration pump of  FIG. 22A ; 
         FIGS. 23A-23D  show end views of the aspiration pump of  FIG. 22A  illustrating side-to-side motion of a cam follower as the camshaft rotates; 
         FIG. 24A  shows an example of aspiration flow rate provided by an aspiration pump; 
         FIG. 24B  shows another example of aspiration flow rate provided by an aspiration pump; 
         FIGS. 25A-25C  illustrate an implementation of a cutter tube drive mechanism incorporating a vibrating motor; 
         FIGS. 26A-26C  illustrate another implementation of a cutter tube drive mechanism incorporating a vibrating motor; 
         FIGS. 27A-27B  illustrate other implementations of cutter tube drive mechanisms. 
     
    
    
     It should be appreciated that the drawings are for example only and are not meant to be to scale. It is to be understood that devices described herein may include features not necessarily depicted in each figure. 
     DETAILED DESCRIPTION 
     Described herein are systems, devices, and methods for ophthalmic microsurgical tools useful for intraocular fragmentation and removal of the lens, vitreous, and other tissues during intraocular surgery. The various systems, devices, and methods are configured to perform one or more functions useful in ophthalmic procedures including, but not limited to, cutting, fragmentation, emulsification, aspiration, and/or irrigation of material present at a target location during a procedure in the eye. 
     “Material” as used herein can include fluids (from the eye or provided to the eye), tissues, or fragments of tissues such as lenticular tissue, vitreous tissue, cells, and any other fluid or tissue or other material that may be present during a procedure in the eye (e.g. cataract procedure, vitrectomy procedures, and the like). 
     The systems, devices, and methods described herein are configured to apply vacuum and deliver fluids to maintain a pressure balance within the eye. The systems, devices, and methods described herein that apply vacuum and/or deliver fluids may also be configured to cut, fragment, emulsify, or otherwise make smaller material in and near the surgical site. The systems, devices, and methods described herein that allow for vacuum to be applied can provide that vacuum using pulsed vacuum with or without interspersed pulsed positive pressure to provide momentary retrograde flow. 
     The various features and functions of the devices described herein may be applied to one or more devices described herein even though they may not be expressly described in combination. It should also be appreciated that various features and functions of the devices described herein can be applied to conventional devices and systems known in the art also useful for cutting, fragmenting, emulsifying, or otherwise impacting tissues at or near a surgical site, including, but not limited to phacoemulsification systems, vitrectomy systems, bag polishing systems, and other tools useful in performing cataract surgeries or vitrectomy surgery, and the like. 
       FIG. 1  is a functional block diagram of a phacoemulsification system  10 . The system  10  has a control unit  12 , which can include a variable speed peristaltic pump  14 , which provides a source of vacuum for aspiration, an ultrasonic power source  16 , and a microprocessor computer  18  that provides control outputs to pump speed controller  20  and ultrasonic power level controller  22 . A vacuum sensor  24  provides an input to computer  18  representing the vacuum level on the output side of the peristaltic pump  14 . The vacuum sensor  24  may also be within the hand piece  30 . Suitable venting is provided by vent  26 . The control unit  12  supplies ultrasonic power on line  28  to a phacoemulsification hand piece  30 . An irrigation fluid source  32  is fluidly coupled to hand piece  30  through line  34 . The irrigation fluid and ultrasonic power are applied by hand piece  30  to a patient&#39;s eye  36 . Aspiration of the eye  36  is achieved by peristaltic pump  14  through lines  38  and  40 . Delivery of irrigation fluid from irrigation fluid source  32  can be provided via gravity or using an irrigation fluid pump additionally incorporated within the control unit  12 . The computer  18  responds to preset vacuum levels in output line  42  from peristaltic pump  14  via signals from the vacuum sensor  24 . 
       FIG. 2A  is a cross-sectional view of a phacoemulsification hand piece  30 . The hand piece  30  has a cutting tip  112 , which can be a tube having a lumen  110 , hand piece shell  114 , ultrasound horn  116 , and a multi-stack of ultrasound crystals. The hand piece  30  can include a first set of ultrasound crystals  118  and a second set of ultrasound crystals  120 . The first set of ultrasound crystals  118  may be arranged perpendicular to the longitudinal axis of the cutting tube  112  such that they produce what is conventionally referred to as “torsional” motion. The second set of ultrasound crystals  120  may be arranged coaxial with the longitudinal axis of the cutting tube  112  such that they produce what is conventionally referred to as “longitudinal” or “axial” motion. Crystals  118  are polarized to produce torsional motion. Torsional motion can include any of a variety of motions relative to the longitudinal axis of the cutting tube  112 , but includes substantial side-to-side motion over axial motion. Crystals  120  are polarized to produce longitudinal motion. Longitudinal motion can also include any of a variety of motions of the cutting tube  112  relative to its longitudinal axis, but includes substantial axial motion over side-to-side. Crystals  118 ,  120  also may be configured to produce both longitudinal and torsional motion. 
     The ultrasound crystals need not be arranged perpendicular to the longitudinal axis of the cutting tube  112  in order to produce torsional motion, which will be described in detail below. 
     The horn  116  is held within the shell  114  by isolator  117 . Crystals  118  and  120  are held within shell  114  and in contact with horn  116  by back cylinder  122  and bolt  124 . Crystals  118  and  120  vibrate ultrasonically in response to a signal generated by an ultrasound generator  126 . The ultrasound generator  126  provides the drive signal to power the ultrasonic hand piece  30 . 
     Piezoelectric crystals generally have a resonant frequency where the input voltage corresponds to a maximum current and a maximum amplitude. This often occurs when the voltage and the current are in phase with one another. Ultrasonic drive systems that are described herein and also commonly used in ultrasonic welders, ultrasonic cutter, ultrasonic cleaners, etc., use the horn  116  to amplify the movement of the cutting tube  112 . The horn length may be constructed to be a multiple of a half wavelength of the sound wave traveling through the horn material. Therefore the ends of the horn  116  are nodes that move at a maximum amplitude. The horn  116  is often stepped or constructed in a way to amplify the movement of the tube  112  by tapering such that the distal end of the horn  116  moves a greater distance than the proximal end of the horn  116 , which is rigidly connected to the piezoelectric crystals  118 ,  120 . The horn  116  is often designed to match the resonance of the piezoelectric crystal  118 ,  120  such that the most efficient energy transfer is achieved. 
     The cutting tube  112  of conventional phacoemulsification hand pieces are circular in cross-section. Torsional or transverse motion (i.e. substantially side-to-side motion relative to the longitudinal axis of the cutting tube  112 ) can create microscopic cavitation bubbles on the low pressure side (i.e. trailing side) of the circular cutting tube  112  that then implode when the direction of travel is reversed. The cutting tubes  112  described herein can incorporate a non-circular geometry configured to mitigate the creation of cavitation bubbles on one or both sides of the cutting tube  112  during the substantially side-to-side motion of the cutting tube  112  during torsional or transverse cutting motion. The non-circular geometry can include oval, elliptical, lentoid, tear-drop, diamond, or other non-circular geometry. The geometry can include one or more airfoils or hydrofoils extending from a central axis of the cutting tube  112 . 
       FIGS. 2B-2C  show the cutting tube  112  of the hand piece  30  may include first and second tapers or tapered profiles  111   a,    111   b  extending laterally from a central axis A of the tube  112 .  FIG. 2C  shows the planform of the cutting tube  112  can be substantially rectangular along at least a portion of its length. The geometry of the cutting tube  112  can mitigate creation of these cavitation bubbles on the trailing, low pressure sides as the cutting tube  112  moves side-to-side.  FIG. 2B  shows a distal-end view of a substantially straight cutting tube  112 .  FIG. 2C  is a planform view of the cutting tube  112  illustrating that when undergoing torsional motion toward right (arrow T) tapered profile  111   a  forms the leading edge and tapered profile  111   b  forms the trailing edge. The tapered profiles  111   a,    111   b  extend outward from the lumen  113  on opposing sides of the longitudinal axis A of the cutting tube  112 . The distance between the longitudinal axis A and the wing tip of the tapered profile  111  can vary between about 0.25 mm and about 1.5 mm or between about 0.5 mm and about 1.0 mm. As such, the distance D end-to-end between the tapered profiles  111   a,    111   b  (i.e. wing span) can be between about 0.5 mm and about 3 mm or between about 1 mm and 2 mm. The aspect ratio of the winged cutting tube  112  can be relatively high (see  FIG. 2E ) or relatively low (see  FIG. 2F ). The aspect ratio of the winged cutting tube  112  can between 1.1 and 4. The cross-sectional geometry of the winged cutting tube  112  can incorporate substantially symmetrical tapered profiles  111   a,    111   b  relative to the chord line C. Alternatively, the winged cutting tube  112  can incorporate a camber or have a curvature relative to the chord line C. The wing tip of each tapered profile  111  can be curved as shown in  FIG. 2F  or more angular as shown in  FIG. 2G . The lumen  113  of the cutting tube  112  may be substantially cylindrical as shown in  FIGS. 2B, 2D-2G  or can have a non-circular geometry as shown in  FIGS. 2H-2J  such as elliptical, lentoid, oval, or other geometrical shape. 
     In some implementations, the tapered profile of the cutting tubes described herein can reduce or eliminate the amount of turbulent flow over the profile of the cutting tube, thereby increasing the amount of laminar flow as the tube moves as compared to a cutting tube having a circular profile. The cutting tubes described herein can incorporate surface treatments and/or coatings on an outer surface to further reduce the likelihood of or mitigate turbulent flow. For example, the cutting tube may be mechanically polished or buffed, electro-polished, plasma treated, coated with substances like PTFE, or any number of other suitable coatings or methods. Treatments and/or coatings may decrease the roughness of the cutting tube and/or reduce the friction of the fluid over the cutting tube such that portions of the cutting tube create laminar flow as the cutting tube travels through the fluid and decreased turbulent flow. 
     In some implementations, the cutting tube  112  can be asymmetric in cross-section (see  FIG. 2M ). The cutting tube  112  can have a single tapered profile  111  extending from only one side of the cutting tube  112  and the other side of the cutting tube  112  may have any of a variety of other geometries or profiles, including a circular profile  108 . As will be described in more detail herein, motion of the cutting tube  112  may be asymmetric (e.g. speed or velocity of movement in a first direction can be different from speed or velocity of movement in a second, different direction). Torsional or side-to-side motion of the cutting tube  112  may be asymmetric such that the movement is optimize for the geometry of the cutting tube  112  (or the geometry of the cutting tube  112  is optimized for the movement). For example, as shown in  FIG. 2M , one side of the cutting tube  112  has the tapered profile  111  and the other side does not and has instead a circular profile  108 . The movement of the cutting tube  112  may be faster along direction arrow F when the circular profile  108  is the leading edge and the tapered profile  111  is the trailing edge compared to movement of the cutting tube  112  along direction arrow S when the tapered profile  111  is the leading edge and the circular profile  108  is the trailing edge. In this way, the trailing edge of the cutting tube  112  can be similar to a smooth hydrofoil having a tapered profile geometry when the cutting tube  112  is moving fast and the trailing edge of the cutting tube  112  can be circular in profile when cutting tube  112  is moving slowly. Thus, the geometry of the trailing edge together with the motion of the cutting tube  112  can be optimized to break up the lens tissue while still mitigating cavitation. The striking edge or leading edge profile of the cutting tube  112  may be a circular profile or any profile that optimizes striking and breaking apart lens pieces while the trailing edge can be optimized for reducing cavitation such as by incorporating a hydrofoil or tapered profile  111 . Asymmetric motion of the cutting tube  112  allows each edge to be optimized for its respective purpose. 
     The winged geometry can be present from the distal-most end of the cutting tube  112  to a proximal-most end of the cutting tube  112 . In some implementations, only a distal portion of the cutting tube  112  has the winged geometry. For example, only the distal-most 1 mm of the cutting tube  112  may be winged. The irrigation sleeve may be shaped at its distal end to conform to the shape of the tapered profile  111 . Alternatively, the irrigation sleeve may be a standard circular shape, but may be positioned just proximal to the region of the tapered profile  111  at the distal end of the cutting tube  112 . 
     The cutting tube  112  having the winged geometry can be straight along its longitudinal axis A as shown in  FIGS. 2A-2B  or may be bent or curved along at least a portion of its length. In some implementations, the cutting tube  112  may incorporate a Kelman-style tip (see  FIGS. 2K-2L ) having a bend forming an angle θ relative to the longitudinal axis A. The effect of a bent or curved tip is that the rotational displacement or side-to-side cutting motion at the distal-most tip  115  is larger compared to the relatively small rotational displacement of more proximal regions of the cutting tube  112  where the cutting tube  112  extends through the incision. When the cutting tube  112  is rotated about its longitudinal axis A, the distal-most tip of the cutting tube  112  sweeps back and forth along a greater distance. The sweeping distal tip of the cutting tube  112  can incorporate the tapered profiles  111   a,    111   b  as best shown in  FIG. 2L . 
     In some implementations, a tab  117  or other surface feature can be coupled to an outer surface of the cutting tube  112  a distance away from the distal-most tip  115 . The tab  117  and the cutting tube  112  can be constrained such that it only moves in a rotational manner. A cutter tube drive mechanism  119 , which can be piezoelectric, motor, electromagnetic, voice coil, or other drive mechanism configured to apply a force to tab  117  causing small rotational motions of the tab  117  and thus, the cutting tube  112 . The cutting tube  112  can be constrained to move only torsionally. As an example, the cutter tube drive mechanism  119  can incorporate a piezoelectric crystal stack that pushes against the tab  117  urging it away from the stack. The crystal stack can be energized to push the tab  117  in a first direction and reverse energy moves the tab  117  back in the opposite direction (arrow P of  FIG. 2L ). In this configuration the piezoelectric crystal stack and the tab  117  may be fixed to one another. Other cutter tube drive mechanisms will be described in more detail below. The cutting tube  112  shown in  FIG. 2L  and incorporating the tab  117  is shown having a winged geometry. The geometry of the tube  112  need not incorporate these tapered profiles  111   a,    111   b  and can be cylindrical. 
     It should be appreciated that any of the cutting tubes described herein can incorporate tapered profiles  111  such that the winged geometry may mitigate cavitation regardless the drive mechanism used to drive the torsional motion (i.e. piezo, voice coil, motor-driven cam, or other drive mechanism). Similarly, the winged cutting tube may be incorporated with any of a variety of hand pieces described herein including those hand pieces having an integrated aspiration pump and/or a trigger or finger-pedal on at least a portion of the hand piece. 
       FIG. 3  is a functional block diagram of a phacoemulsification system  1010  according to an implementation. The system  1010  can include a control unit  1012 , which can include an ultrasonic power source  1016  and a processor  1018  that provides control outputs to a pump controller  1020  and ultrasonic power level controller  1022 . The control unit  1012  can supply ultrasonic power on line  1028  to a hand piece  1030  (e.g. 400V for driving piezoelectric crystals). The hand piece  1030  can include an integrated aspiration pump  1014  powered by the control unit  1012 . The control unit  1012  can supply power to the aspiration pump  1014  of the hand piece  1030  via a line, which can be the same or a different line as line  1028  (e.g. lower voltage than for piezo, 5-12 V for driving a motor). It should appreciated that the hand piece  1030  can incorporate electronics such that the hand piece  1030  can be used independently of the control unit  1012 . An irrigation fluid source  1032  can be fluidly coupled to the hand piece  1030  through irrigation line  1034 . The irrigation fluid and ultrasonic power may be applied by the hand piece  1030  to a patient&#39;s eye  36 . Aspiration of the eye  36  may be achieved by the aspiration pump  1014  in the hand piece  1030  through an aspiration line  1038 . Delivery of irrigation fluid from irrigation fluid source  1032  can be provided via gravity and/or using an irrigation fluid pump within the control unit  1012 . 
       FIG. 4  is a functional block diagram of the phacoemulsification system  1010  illustrating the fluidics of the system  1010 . The fluidics of the system  1010  can include the irrigation fluid source  1032 , the irrigation fluid line  1034 , the aspiration pump  1014  within the hand piece  1030 , a waste line  1038  (sometimes referred to herein as the aspiration line), and a waste container  1044 . The system  1010  may optionally include an irrigation fluid pump configured to deliver irrigation fluid from the irrigation fluid source  1032 . The irrigation fluid source  1032 , which can optionally include one or more pressure sensors and/or valves for controlling flow through the irrigation line  1034 , is fluidly coupled to the hand piece  1030 , either directly or through the irrigation port  1044 . Irrigation fluid may exit the irrigation fluid source  1032  and travel toward the hand piece  1030  through irrigation fluid line  1034  during a phacoemulsification procedure. An optional irrigation fluid reservoir  1046  may be incorporated within the distal end of the hand piece  1030 , as will be described in more detail below. The hand piece  1030  and/or the irrigation line  1034  may optionally include one or more valves and/or sensors configured to provide additional control of fluid flow to the hand piece  1030 . The hand piece  1030  and/or the waste line  1038  may optionally include one or more valves and/or sensors configured to provide additional control of fluid flow from the hand piece  1030 . The pump  1014  may draw fluid and other materials from the eye  36  through waste line  1038  directing the material toward the waste container  1044 . 
     The system  1010  can also include a remote aspiration pump within a region of the control unit  1012  in addition to the aspiration pump  1014  within the hand piece  1030 . The aspiration pump in the control unit  1012  can be configured to apply continuous, semi-continuous, and/or discontinuous pulsatile aspiration. The aspiration pump in the control unit  1012  can be configured to apply a continuous low-level flow rate. The aspiration pump in the control unit  1012  can be any of a variety of different aspiration pumps including volumetric flow or positive displacement pumps (e.g. peristaltic, linear peristaltic, piston, scroll pump) or vacuum-based pumps (e.g. venturi, pneumatic, diaphragm, or rotary-vane). In an implementation, the aspiration pump in the control unit  1012  can include a low pressure, peristaltic pump integrated within the control unit  1012  to support the aspiration provided by the integrated aspiration pump  1014  within the hand piece  1030 . For example, during a first portion of use, aspiration through the hand piece  1030  may be provided by the remote aspiration pump within the control unit  1012  and during a second portion of use, aspiration through the hand piece  1030  may be provided by the integrated aspiration pump  1014  within the hand piece  1030 . Additional implementations of the aspiration support are described in more detail below. 
       FIGS. 5A-5B  are cross-sectional views of an implementation of the hand piece  1030  of  FIG. 3  having the aspiration pump  1014  driven by pump motor  1115 . The hand piece  1030  is configured for surgeries (such as cataract surgeries) that are performed in a minimally-invasive, ab interno approach through clear corneal incisions. The hand piece  1030  requires less energy, time, and fluid to remove the tissues from the eye than conventional phaco. 
     The hand piece  1030  includes a hollow cutting tip or cutting tube  1112  reciprocated by a cutter tube drive mechanism. The cutting tube  1112  can be oscillated by any of a variety of drive mechanisms including the piezoelectric drive mechanisms described above as well as electric, magnetostrictive, electromagnetic, hydraulic, pneumatic, mechanic, voice coil, or other type of drive mechanism known in the art. Where the cutting tube  1112  is described as being oscillated by a piezoelectric drive mechanism is should be appreciated that other cutter tube drive mechanisms are considered as well. In some implementations, the cutting tube  1112  is reciprocated by a drive mechanism including a motor contained within an interior of the hand piece  1030 . The configuration of the motor can vary including, any of a variety of rotation motors, stepper motor, AC motor, DC motor, a piezoelectric motor, a voice coil motor, or other motor. The motor may be coupled to a gear reduction system such as a harmonic drive to produce the desired output speed. 
     In an implementation, the cutting tube  1112  is oscillated by a piezoelectric drive mechanism. The cutting tube  1112  may be coupled to a horn  1116  driven by piezoelectric crystals  1120 . The crystals  1120  may be held within the housing  1114  in contact with the horn  1116  by a back cylinder  1122  and bolt  1124 . The crystals  1120  may be polarized to produce longitudinal and/or torsional motion when a drive signal is provided to power the hand piece  1030  by the control unit  1012 . The piezoelectric crystals  1120  may be natural piezoelectric substrates, such as quartz single crystals, piezoelectric ceramics, such as lithium niobate, gallium arsenide, zinc oxide, aluminum nitride, or lead zirconate-titanate (PZT). In some implementations, the piezoelectric crystals  1120  are formed of polymer-film piezoelectrics, such as polyvinylidene fluoride. Such plastic-based crystal stacks may be lower cost and potentially disposable. 
     Conventional ultrasound horns are configured to augment the oscillation displacement amplitude provided by the piezoelectric crystals. Conventionally, the horn is rigidly connected to the ultrasonic transducer using a threaded stud at a proximal end and tapers distally. Conventional ultrasound horns are resonant. “Horn” as used herein can, but need not function as a conventional ultrasound horn does. Meaning, the horn can, but need not, be in resonance during use. The horn described herein can be used in a non-resonant, direct drive manner as will be described in more detail herein. Use of the term “horn” herein is not intended to be limiting to the conventional use of the term ultrasound horn. 
     The cutter tube drive mechanisms described herein can incorporate a piezoelectric stack. Piezos can suffer damage and cracking when misaligned with other components. Stacks of disc-shaped piezos are less prone to damage because they can be arranged fully parallel to one another. However, the piezoelectric stacks described herein can be arranged in non-concentric manner relative to the cutting tube and can directly drive motion of various components that are not necessarily arranged completely parallel. Meaning, if any angularity exists at the interface with the piezoelectric stack, the point loads can lead to cracking. 
     The piezoelectric stack can be a multilayer of thin piezoelectric/electrostrictive ceramic sheets stacked together. These multilayers have a relatively low driving voltage (100 V), quick response, high generative force, and high electromechanical coupling. The displacement though is usually on the order of 10 microns and is generally not sufficient alone for cutting tube displacement. As mentioned above, the motion of the cutting tip can be what is known as “torsional” or primarily side-to-side motion over longitudinal, forward-backward motion. This tip motions is considered to be more efficient lens removal motion, particularly for dense and hard lens nuclei. Regardless the direction or orientation of the motion of the cutting tip, a primary goal in piezoelectric drive mechanisms is amplification of the tiny motion of the piezoelectric material into sufficient physical displacement or stroke of the cutting tip. 
     Described herein are various interrelated implementations of cutter tube drive mechanisms configured to achieve a minimum tip speed of 3 meters/second and within a frequency range that is less than ultrasonic (i.e., less than 20,000 Hz), including less than 10,000 Hz, less than 5,000 Hz, less than 4,000 Hz, less than 3,000 Hz down to sub-sonic frequency ranges that are less than 20 Hz, less than 15 Hz, less than 10 Hz, less than 5 Hz, down to about 0.5 Hz. In some implementations, the tip speed target is approximately 5 meters/second to ensure cutting of denser material. The cutter tube drive mechanisms are capable of amplifying motion of the cutting tube while mitigating the likelihood of damage due to the incorporation of movable components. The cutter tube drive mechanism can incorporate a piezoelectric stack or motor driven cam or vibrating motor that directly drives the cutting tube via a conventional hinge to generate oscillatory motion. The oscillatory motion achieved can be in the frequency range that is less than ultrasonic. The drive mechanism can incorporate less than 2 nodal inflection points between a point of drive force application and the distal tip of the cutting tube. The drive force can be applied to generate longitudinal motion as well as side-to-side (“torsional”) motion. It should be appreciated that the torsional motion need not be constrained to a single plane. The drive mechanism can also drive the cutting tube via a “living” hinge to generate the oscillatory motion. 
       FIGS. 16A-16D  illustrate an implementation of a cutter tube drive mechanism  119  incorporating a conventional or mechanical hinge coupled to a rocker arm or rocker plate. The rocker  1605  can be an off-set rocker  1605 . The cutter tube drive mechanism  119  can include a base  1610  configured to couple to or be integrated with an interior of the hand piece (not shown). The rocker  1605  can be movably attached to the base  1610  via a rocker pivot pin  1615 , which allows the rocker  1605  to freely rotate relative to the base  1610  about the rotational axis of the pivot pin  1615 . A piezoelectric stack  1120  can be coupled to the base  1610  on a lower end and the rocker  1605  on an upper end. The cutting tube  1112  can extend through generally central regions of the base  1610  and the rocker  1605 . The piezoelectric stack  1120  can be positioned off-set or on one side of the base  1610 . The piezoelectric stack  1120  can be coupled to the base  1610  and the rocker  1605  via movable couplings. For example, the cutter tube drive mechanism can incorporate a pair of toggles  1620   a,    1620   b.  The lower toggle  1620   a  can be attached to the base  1610  via a lower toggle pin  1622  and the upper toggle  1620   b  can be attached to the rocker  1605  via an upper toggle pin  1624 . The toggles  1620   a,    1620   b  can freely rotate relative to the base  1610  and the rocker  1605 . This motion allows for some degree of non-paralellism to exist between the proximal end of the piezoelectric stack  1120  where it contacts the base  1610  and the distal end of the piezoelectric stack  1120  where it contacts the rocker  1605  thereby mitigating damage at the edges of the piezoelectric stack  1120 . The pivot of the toggles  1620   a,    1620   b  allow for misalignment and cancels out any inaccuracies in the parallel to non-parallel motion transfer. Additionally, a dome  1621  may be positioned near the interface with the piezoelectric stack  1120  to eliminate any point loads (see  FIG. 16D ). 
     The cutter tube drive mechanism  119  can include a spring post  1625  and a spring stack  1627 . As mentioned above, the cutting tube  1112  can extend through the central region of the base  1610  and rocker  1605 . The piezoelectric stack  1120  can be positioned off-set or on one side of the base  1610 . The spring post  1625  and spring stack  1627  can be positioned opposite the piezoelectric stack  1120  such that the cutting tube  1112  is positioned between the piezoelectric stack  1120  positioned on one side of and the springs on the opposite side. 
     The spring stack  1627  can be one or more Belleville springs encircling a boss  1638  on an upper end region of the spring post  1625  (see  FIG. 16C ). The boss  1638  of the spring post  1625  can extend at least partially into a hole  1637  through the rocker  1605 . The spring post  1625  can also include a lower boss  1638  configured to mate with a corresponding hole on the base  1610 . The bosses  1638  on the spring post  1625  can freely slide axially within the holes  1637  on the rocker  1605  and the base  1610 . The bosses  1638  can keep the spring stack  1627  contained in the desired position on the spring post  1625 . 
     An upper surface of the spring stack  1627  engages with a lower surface of the rocker  1605  and a lower surface of the spring stack  1627  abuts against a ledge of the spring post  1625 . The spring stack  1627  can apply a upwardly-directed force against the lower surface of the rocker  1605 . The force on the rocker  1605  can be transmitted as a pre-load onto the upper end of the piezoelectric stack  1120  via the toggles  1620   a,    1620   b.  Pre-load ensures constant contact is maintained between the piezoelectric stack  1120  and other components parts so no motion of the piezoelectric stack  1120  is lost. 
     The cutting tube  1112  can extend through a bore in the rocker  1605  and through a bore in the base  1610 . The cutting tube  1112  can be fixed to each via glue, welding, or other method of fixation. A support bushing  1630  can be incorporated that aids in preventing the tube from cracking after prolonged use. The support bushing  1630  can be coupled to an upper surface of the rocker  1605  aligned with the bore through the rocker  1605 .  FIG. 16C  shows a side section view of the off-set rocker  1605 . The tube  1112  is shown attached to the base  1610  via a stiffener bushing  1635 . The stiffener bushing  1635  can ensure that the tube  1112  is forced to bend relative to the base  1610  when the piezoelectric stack  1120  is activated. 
     The piezoelectric stack can change with varying voltage including alternating current or DC variable voltage. In an implementation, an alternating current (e.g., 100 Hz to 20 Khz) applied to the piezoelectric stack  1120  causes the piezoelectric stack  1120  to expand and contract. As the piezoelectric stack  1120  expands, the rocker  1605  and therefore the tube  1112  attached to the rocker  1605  can bend about the base  1610 . As the piezoelectric stack  1120  contracts, the spring stack  1627  can assist the piezoelectric stack  1120  in quickly returning to its starting length and ensure there is constant contact between the piezoelectric stack  1120  and the two toggles  1620   a,    1620   b.  The cutting tube  1112  can undergo bending where it extends through the rocker  1605 . There also can be some bending of the tube  1112  below the rocker  1605  and additional motion due to the “whipping”. The cutting tip motion is generally much larger than what is predicted for the piezoelectric stack  1120  due to the presence of additional “whipping” motion by the cutting tube  1112 . The piezoelectric stack  1120  incorporated in the cutter tube drive mechanisms described herein can be mechanically configured to use any piezoelectric charge coefficient, i.e., d 33 , d 31 , d 15 . 
       FIGS. 17A-17C  illustrate an interrelated implementation of a cutter tube drive mechanism  119  incorporating a conventional or mechanical hinge coupled to a rocker arm or rocker plate. The rocker can be a straight rocker  1605 . The straight rocker  1605  can be movably attached to the base  1610  via a rocker pivot pin  1615 , which allows the rocker  1605  to freely rotate relative to the base  1610  about the rotational axis of the pivot pin  1615 . The location of the hinge (i.e., rocker pivot pin  1615  shown in  FIGS. 17A-17C ) is further towards a distal end of the cutting tube  1112  compared to the location of the hinge in the offset rocker implementation shown in  FIGS. 16A-16C . The rocker pivot pin  1615  in the straight rocker  1605  can be substantially aligned along the longitudinal axis of the tube  1112  and the rocker  1605  creating a fulcrum for the rocker  1605  The location of the rocker pivot pin  1615  relative to the tube  1112  may change the wag characteristics at the tip of the tube  1112  and may alter the “whipping” effect the tube  1112  exhibits during use. In the straight rocker, the pivot pin is substantially aligned with the rocker along the longitudinal axis of the cutter tube. In the offset rocker, the pivot pin is positioned proximal to the rocker along the longitudinal axis of the cutter tube. 
     The piezoelectric stack  1120  can be coupled to the base  1610  on a lower end and to the rocker  1605  on an upper end. The cutting tube  1112  can extend through a generally central regions of the base  1610  and the rocker  1605 . The piezoelectric stack  1120  can be positioned off to one side of the base  1610 . The piezoelectric stack  1120  can be attached to the base  1610  and rocker  1605  or unattached. The interfaces can incorporate one or more features that mitigate damage and point loads to the piezoelectric stack  1120  as described elsewhere herein. 
     The cutter tube drive mechanism  119  can include a spring post  1625  and a spring stack  1627  positioned opposite the piezoelectric stack  1120  such that the cutting tube  1112  is positioned between the piezoelectric stack  1120  and the springs. The tube  1112  can run through the rocker  1605  and the base  1610  and as described above, be attached or unattached to the rocker  1605  and base  1610 . The spring stack  1627  is compressed when in a resting state thereby applying an upward force to a first end the rocker  1605  and a preload force to the piezoelectric stack  1120  applied by a second, opposite end of the rocker  1605 . As the piezoelectric stack  1120  expands or grows under varying voltage, it rotates the rocker  1605  about the rotational axis of the pivot pin  1615  on the base  1610  and thereby moves or “wags” the tube  1112  in at least one direction. As the piezoelectric stack  1120  retracts the upward force applied by the spring stack  1627  against the first end of the rocker  1605  urges the second, opposite end of the rocker  1605  downward with the retracting piezoelectric stack  1120 . The rocker  1605  rotates in the opposite direction, wagging the tube  1112  in the opposite direction. The spring stack  1627  can force the rocker  1605  to rotate and maintain contact with the end of the piezoelectric stack  1120 . 
     The cutter tube drive mechanism  119  can include a piezoelectric stabilizer  1665 . The piezoelectric stabilizer  1665  can surround where the piezoelectric stack  1120  and spring post  1625  contact the base  1610  to ensure the piezoelectric stack  1120  does not work its way out of position during operation. Any of the implementations described herein can incorporate a piezoelectric stabilizer  1665 . 
       FIG. 18  illustrates an interrelated implementation of a cutter tube drive mechanism  119  incorporating a hinge clamp. The hinge clamp can include a lower clamp  1640  and an upper clamp  1645 . The tube  1112  can be inserted through the holes on the upper clamp  1645  and lower clamp  1640 . The lower clamp  1640  may be rotatably attached to the upper clamp  1645  via a hinge pin  1647 . The lower clamp  1640  may be attached to the handle (not shown). The piezoelectric stack  1120  can fit in between the upper clamp  1645  and the lower clamp  1640 . The piezoelectric stack  1120  can either be attached or unattached to the clamps  1640 ,  1645  as described elsewhere. During installation, a clamping force can be applied to the upper clamp  1645  and lower clamp  1640  forcing them to apply a preload force to the piezoelectric stack  1120  positioned therebetween. With the preload force applied, the tube  1112  can be attached to the upper and lower clamps  1645 ,  1640  such that when the clamping force is removed, the preload force is transferred to the tube  1112  and maintained on the piezoelectric stack  1120 . As the piezoelectric stack  1120  grows, it rotates the upper clamp  1645  about the hinge pin  1647  and thereby wags the tube  1112  in one direction. As the piezoelectric stack  1120  retracts, the upper clamp  1645  rotates in the opposite direction, wagging the tube  1112  in the opposite direction. The preload carried in the tube  1112  ensures that the upper clamp  1645  retracts and maintains constant contact with the piezoelectric stack  1120 . Additional clamping can ensure constant contact between the piezoelectric stack  1120  and other components, for example, on a portion of the upper and lower clamps  1645 ,  1640  on an outside region of the tube opposite the hinge pin  1647 . 
       FIGS. 19A-19C  illustrate an interrelated implementation of a cutter tube drive mechanism  119  also incorporating a hinge clamp. It should be appreciated that the various drive mechanisms described herein may incorporate one or more features of any other drive mechanism described herein even though that feature may not be explicitly described for a particular implementation. The hinge clamp can include a lower clamp  1640  and an upper clamp  1645 . The lower clamp  1640  can be attached to the base  1610  via glue, welding, or other coupling means. The upper clamp  1645  can be attached to the lower clamp  1640  via the hinge pin  1647  such that the upper clamp  1645  is free to rotate about the hinge pin  1647 . The piezoelectric stack  1120  can fit in between the upper clamp  1645  and the lower clamp  1640 . 
     The cutting tube  1112  can run through both the upper clamp  1645  and lower clamp  1640 . The cutting tube  1112  can be attached to the upper and lower clamps via glue, welding, or other attachment although the tube  1112  need not be mechanically coupled. A support bushing  1650  can slip around the tube  1112  or be attached to the cutting tube  1112  as described elsewhere. 
     The cutter tube drive mechanism  119  can include a spring stack  1627  and a preload screw  1655 . The preload screw  1655  can be arranged parallel to the cutting tube  1112 . The preload screw  1655  can run through the upper clamp  1645  and lower clamp  1640  and be threaded into a preload nut  1660  below the lower clamp  1640 . The spring stack  1627 , which can include Belleville springs, can be captured between the head of the preload screw  1655  and the upper surface of the upper clamp  1645 . As the preload screw  1655  is tightened into the preload nut  1660  below the lower clamp  1640  during installation, the screw head compresses the spring stack  1627  against the upper clamp  1645 . This, in turn, applies a preload force onto the piezoelectric stack  1120  positioned between the upper and lower clamps  1645 ,  1640 . 
     The piezoelectric stack  1120  and the preload screw  1655  can be positioned on the same side relative to the location of the cutting tube  1112  in contrast to the implementation shown in  FIGS. 16A-16C  in which the piezoelectric stack  1120  and the preload mechanism are located on opposite sides relative to the location of the cutting tube  1112 . An upper surface of the piezoelectric stack  1120  can engage a lower surface of the upper clamp  1645  and a lower surface of the piezoelectric stack  1120  can engage an upper surface of the lower clamp  1640  such that the piezoelectric stack  1120  is positioned and clamped between the upper and lower clamps  1645 ,  1640 . The piezoelectric stack  1120  can be fixed to the upper and lower clamps  1645 ,  1640  via glue or other mechanical fixation. 
     As the piezoelectric stack  1120  grows, the upper clamp  1645  can be forced upwards. The upper clamp  1645  rotates about the hinge pin  1647  and compresses the spring stack  1627  against the head of the preload screw  1655 . As the piezoelectric stack  1120  retracts, the spring stack  1627  forces the upper clamp  1645  downwards around the axis of the hinge pin  1647  maintaining constant contact against the upper end of the piezoelectric stack  1120 . The preload screw  1655  allows for the amount of preload to be dialed in and adjusted during manufacturing to achieve the desired load. 
       FIGS. 20A-20B  illustrate an interrelated implementation of a cutter tube drive mechanism  119  incorporating a biplane configuration. The drive mechanism  119  can include a base  1610 , a top plate  1670 , and two intervening piezoelectric stacks  1120   a,    1120   b.  The two piezoelectric stacks  1120   a,    1120   b  can either be unattached or attached to the top plate  1670  and base  1610 .  FIG. 20B  shows the two piezoelectric stacks  1120   a,    1120   b  can fit into pockets on the base  1610  to control the position of the piezos. The drive mechanism  119  can additionally include a preload screw  1655  and nut  1660 . The screw  1655  can extend through the base  1610  and into corresponding threads available from a lower surface of the top plate  1670 . As the preload screw  1655  is tightened, a preload force is applied to the piezoelectric stacks  1120   a,    1120   b  via the top plate  1670 . The tube  1112  can run through the top plate  1670  and through a central bore  1675  in the preload screw  1655  (see  FIG. 20B ). The tube  1112  may be unattached or attached to the top plate  1670  and preload screw  1655 . As mentioned elsewhere herein, the piezoelectric stack can change with varying voltage. In an implementation, two separate alternating currents can be applied to the piezoelectric stacks  1120   a,    1120   b.  The alternating currents may be out of phase such that one piezoelectric  1120   a  expands as the other piezoelectric  1120   b  retracts and vice versa. This can allow the top plate  1670  to pivot or rock thereby causing the tube  1112  to wag back and forth. The alternating currents can also be timed to one another in any manner that creates a desirable effect on the end of the tube  1112 . 
     The drive mechanisms described above are configured to provide torsional motion to the cutting tube with a minimum peak tip velocity (e.g., at least 2.5 meters/second, but less than about 12 m/s). In any of the implementations described herein, the piezoelectric stack  1120  can be stacked parallel to the longitudinal axis of the tube  1112  (i.e., a vertical stack) or can be stacked perpendicular to the tube. Whether stacked parallel or perpendicular to the tube  1112 , the direction of elongation can be the along the longitudinal axis of the tube  1112 . The piezoelectric stack  1120  can be mechanically configured to use any piezoelectric charge coefficient including as examples d 33 , d 31 , and d 15 . 
     It should be appreciated that the drive mechanism  119  need not be a piezoelectric drive mechanism.  FIGS. 21A-21D  illustrate an implementation of a cutter tube drive mechanism incorporating a motor-driven cam that is capable of achieving a minimum tip speed. The drive mechanism  119  can include a base  1610 , a motor  1680  configured to turn a cam  1682 . The cam  1682  can incorporate a wave pattern on both ends. As the cam  1682  turns, the wave pattern of the cam  1682  drives a cam follower  1684  up and down. The cam follower  1684  is coupled to a rocker  1605  via a cam follower pin  1681 . As the cam follower  1684  moves up and down it pivots a rocker  1605  about a rocker hinge pin  1615 . As the rocker  1605  pivots back and forth, it can pivot the cutting tube  1112  back and forth. A support bushing  1650  can be incorporated that aids in distributing the forces on the tube  1112  and to help prevent the rocker  1605  from damaging the tube  1112 .  FIG. 21B  is a side view of the drive mechanism  119  with the base  1610  hidden. The base  1610  can include a second support bushing  1650  that can contact the tube  1112  and provide a point of bending for the tube  1112  as it is driven back and forth. 
       FIG. 21C  shows a close-up view of the cam mechanism. The upper cam surface  1686  of the cam  1682  can feature a radius so that the cam following surface  1683  of the cam follower  1684  can ride along the cam surfaces of the cam  1682  smoothly. The cam  1682  features an upper cam surface  1686  and a lower cam surface  1688 . The shapes of the upper and lower cam surfaces  1686 ,  1688  can be inverses of each other such that the distance in the axial direction between the upper and lower cam surfaces  1686 ,  1688  is constant. The cam  1682  features a cam constraint rib  1690  that slides into the cam constraint slot  1692  on the cam constraint  1694 . The cam constraint  1694  can be fixed to the base  1610  or can be integrated as one piece with the base  1610 . The cam constraint slot  1692  can prevent the cam  1682  from moving axially as it turns and applies force to the cam follower  1684 .  FIG. 21D  shows a close-up view of the cam mechanism with the cam  1682  hidden. The lower cam follower surface  1698  contacts the lower cam surface  1688  of the cam  1682  and drives the cam follower  1683  downwards. The lower cam follower surface  1698  can have the same radius as the upper cam follower surface  1683  to ensure smooth movement along the cam  1682 . 
       FIGS. 25A-25C  and also  FIGS. 26A-26C  illustrate implementations of a cutter tube drive mechanism  119  incorporating a vibrating motor and a mechanical hinge incorporating a rocker  1605 . The drive mechanism  119  can include a base  1610  configured to couple to a hand piece (not shown). The rocker  1605  can be attached to the base  1610  via a rocker pivot pin  1615  allowing the rocker  1605  to freely rotate relative to the base  1610 . A motor  1680  can be coupled to the base  1610  such as on a top surface of the base  1610  at a coupling  1695 . The coupling  1695  is configured to allow the motor  1680  to pivot side-to-side. In some implementations, the coupling  1695  can be a rounded ridge or other geometry. The coupling  1695  can be one of the other movable couplings described elsewhere herein. The cutting tube  1112  can extend through a bore in the rocker  1605  and through a bore in the base  1610 . The motor shaft  1685  can extend through a bore in the rocker  1605 . The motor shaft  1685  can be free to rotate relative to the rocker  1605 . An eccentric or offset weight  1696  can be attached to the motor shaft  1685 . As the motor shaft  1685  spins, the mass of the weight  1696  oscillating side-to-side causes the rocker  1605  to move or rock from side-to-side. In some implementation, the motor  1680  has a housing that is rigidly attached to the rocker  1605  and shakes the rocker  1605  and cutter tube  1112 . In other implementations, the motor shaft  1685  is attached to a cam wobble plate that pushes on a cam follower that is rigidly connected to the rocker  1605  and cutter tube  1112 . In another implementation, the motor housing is allowed to pivot such as via a rounded ridge, dome, or other geometry and the vibrating end is rigidly attached to the rocker  1605  and the cutter tube  1112 . This can reduce the mass of the rocker  1605  and cutter tube  1112 . 
       FIGS. 26A-26C  illustrate another implementation of a cutter tube drive mechanism  119  incorporating a vibrating motor and incorporating a spring. In this implementation, the motor  1680  can be coupled on its lower end via welding, glue, or another mechanism to a motor support  1697 . The motor support  1697  can extend from the bottom of the rocker  1605 . The motor shaft  1685 , which can extend through the rocker  1605  such that it can rotate freely, can be coupled to an offset weight  1696  configured to cause the rocker  1605  to rotate back and forth about the pivot pin  1615  as the motor shaft  1685  spins. This wags the tip of the tube  1112  back and forth. A spring post  1625  with a spring stack  1627  can be positioned on the opposite side of the pivot pin  1615  from the motor  1680 . The rocker  1605  compresses the spring stack  1627  as it rotates counter-clockwise and the spring stack  1627  urges the rocker  1605  back in a clockwise direction. 
     In an interrelated implementation, the cutter tube drive mechanism can include a motor-driven cam. The drive mechanism can incorporate a small motor that drives a wheel  1687  having a pin  1689  positioned near a perimeter of the wheel  1687  (see  FIG. 27A ). The pin  1689  can be positioned within a slot  1691  of a pivot arm  1693  that is attached to the cutter tube  1112  a distance away from the distal cutting tip. The cutter tube  1112  can be fixed longitudinally by a pivot pin  1615 , but movable around the rotational axis of the pivot pin  1615 . The rotational axis of the pivot pin  1615  is substantially parallel to a rotational axis of the wheel  1687 . As the wheel  1687  rotates, the eccentrically positioned pin  1689  moves up and down within the slot  1691  of the pivot arm  1693 . The pivot arm  1693 , in turn, can oscillate about the rotation axis of the pivot pin  1615  causing corresponding wag of the distal cutting tip of the cutter tube  1112 . 
       FIG. 27B  illustrates an interrelated implementation of the cutter tube drive mechanism. The drive mechanism can again include a wheel  1687  driven by a small motor. The wheel  1687  can include an eccentrically positioned pin  1689  positioned near a perimeter of the wheel  1687 . The pin  1689  can couple by a link arm  1699  to the pivot arm  1693  attached to the cutter tube  1112  a distance away from the distal cutting tip. The cutter tube  1112  can be fixed longitudinally by the pivot pin  1615 , but movable around the rotational axis of the pivot pin  1615 . As the wheel  1687  rotates, the pin  1689  causes the cutter tube  1112  to oscillate side-to-side around the rotational axis of the pivot pin  1615 . 
       FIGS. 16A-16D, 18, 19A-19C, 20A-20B, 21B, and 25A-25C  illustrate the lower (i.e., proximal) end of the cutting tube  1112  extending beyond the base  1610 . A vacuum may be applied to the proximal end of the tube  1112  in order to evacuate material through the lumen of the tube  1112 . Vacuum may be applied via an aspiration pump  1014  in the hand piece, which will be described in more detail below. It should be appreciated that the cutter tube drive mechanism can be incorporated within the disposable portion of the hand piece  1030 . 
     The aspiration pump  1014  of the hand piece  1030 , which can be integrated within, on or attached to the hand piece  1030 , can draw the aspiration fluid and materials from the eye. As mentioned, the hand piece  1030  includes a hollow cutting tip or cutting tube  1112  that is configured to oscillate such as by a multi-stack of piezoelectric crystals  1120  or another cutter tube drive mechanism (i.e. voice coil, motor-driven cam mechanism, vibrating motor with eccentric weight) to break up the diseased lens. The fluid and materials from the eye enter a lumen  1110  through the cutting tube  1112 . The inner lumen  1110  of the cutting tube  1112  is fluidly coupled to the waste line  1038 . The aspirated material can be directed through the waste line  1038  towards the waste container  1044  by the aspiration pump  1014 . An irrigation sleeve  1113  can be positioned over the cutting tube  1112  to provide irrigation fluid from the irrigation line  1034  through one or more irrigation openings  1111  (shown, e.g., in  FIG. 9A ) to the eye. 
     As best shown in  FIG. 5B  and also  FIG. 12 , the hand piece  1030  can include a disposable portion  1031  configured to be releasably coupled to a durable, reusable portion  1033 . The disposable portion  1031  includes the components of the hand piece  1030  configured to come into direct contact with fluids and materials from the eye. The disposable portion  1031  of the hand piece  1030  can include the cutting tube  1112 , irrigation sleeve  1113 , the aspiration pump  1014 , and connection sites for connecting the irrigation line  1034  and the waste line  1038  to the hand piece  1030 . The irrigation line  1034  and waste line  1038  need not extend through the reusable proximal portion  1033 . The reusable portion  1033  includes the components of the hand piece  1030  that are configured to remain outside the fluid path. The reusable portion  1033  may be sterilized and reused. The reusable portion  1033  can include the components configured to drive the aspiration pump  1014  and one or more of the components configured to drive the cutting tube  1112 . For example, the pump motor  1115 , the horn  1116 , the piezoelectric crystals  1120  and the housing  1114  for containing the crystals  1120  can all be part of the reusable portion  1033 . It should be appreciated that the reusable portion  1033  may also be disposable. For example, the drive mechanism for the cutting tube  1112  can be manufactured with lower cost materials such that it is financial feasible for portion  1033  to also be disposed of after a procedure. Lower cost materials such as polymer-based piezoelectric materials may allow for a significant reduction in cost. 
     The disposable portion  1031  may also include one or more components of the cutter tube drive mechanism  119 . For example, the cutter tube drive mechanism including the rocker and pivot pin as well as the one or more components configured to rotate the rocker around the pivot pin can be positioned within the disposable portion  1031 , including the piezoelectric stack(s)  1120  and associated couplings, clamps, and preload components. The cutter tube drive mechanisms shown in  FIGS. 16A-16D, 17A-17C, 18, 19A-19C, 20A-20B, 21A-21D  as well as  25 A- 25 C and  26 A- 26 C can all be incorporated within the disposable portion  1031  of the hand piece. 
     The coupling between the disposable portion  1031  and the reusable portion  1033  may be purely mechanical or may involve both mechanical and electronic couplings. For example, the disposable portion  1031  may have an electronic input configured to electronically couple with a portion of the reusable portion  1033 . Alternatively, the disposable portion  1031  may have an input configured to mechanically couple and interact with the reusable portion  1033 . The electronics configured to activate the cutter tube drive mechanisms can remain in the reusable portion  1033  of the hand piece such that upon coupling the disposable and reusable portions can be engaged with the cutter tube drive mechanism to activate the piezoelectric stack or motor, etc. 
     The disposable portion  1031  or the durable portion  1033  of the hand piece  1030  can include one or more inputs or actuators. The hand piece  1030  may also be actuated remotely. The instruments are sometimes referred to herein as a “device” or “tool” or “peripheral device” or “hand piece” or “hand held unit”. Use of the term “hand piece” herein can include a hand piece coupled to a robotic arm or robotic system or other computer-assisted surgical system in which the user uses a computer console to manipulate the controls of the instrument. The computer can translate the user&#39;s movements and actuation of the controls to be then carried out on the patient by the robotic arm. 
     Each of these components as well as the coupling between the disposable and durable, reusable portions  1031 ,  1033  of the hand piece  1030  will be described in more detail below. 
     The systems described herein can include a single, reusable driver portion (sometimes referred to herein as a “durable portion”) configured to operatively couple with one or more disposable working portions (sometimes referred to herein as a “disposable portion”) in an interchangeable manner. The disposable working portions can be configured for different types of ophthalmic procedures including lens fragmentation, phacoemulsification, vitrectomy, bag polishing, aspiration, irrigation, coagulation, illumination, visualization, intraocular lens (IOL) insertion, and others. The operating parameters of the instrument can differ according to, for example, the configuration of the disposable working portion that is attached to the reusable driver portion. 
     The various features and functions of the devices described herein may be applied to one or more devices described herein even though they may not be expressly described in combination. It should also be appreciated that various features and functions of the devices described herein can be applied to conventional devices and systems known in the art also useful for cutting, fragmenting, emulsifying, or otherwise impacting tissues at or near a surgical site, including, but not limited to phacoemulsification systems, vitrectomy systems, bag polishing systems, and other tools useful in performing cataract surgeries or vitrectomy surgery, and the like. 
     Again with respect to  FIGS. 5A-5B , the cutting tube  1112  can be a conventional phacoemulsification needle having a proximal end  1128  configured to couple with the horn  1116  extending through to a distal end region of the disposable portion  1031  upon coupling the disposable and durable portions  1031 ,  1033  of the hand piece  1030 . The cutting tube  1112  is shown as being curved slightly away from a longitudinal axis of the hand piece  1030  and having a bevel tip. It should be appreciated the cutting tube  1112  can also be coaxial with the longitudinal axis such that extends substantially straight from the distal end of the hand piece  1030 . Any of a variety of geometries and tip shapes are considered herein. At least a distal end region of the cutting tube  1112  and the irrigation sleeve  1113  are configured to be inserted into the eye in a minimally-invasive manner to cut, aspirate, and irrigate, such as during a cataract procedure. 
     As will be described in more detail below, the cutting tube  1112  is configured to oscillate (e.g., longitudinally, torsionally) in order to jackhammer or shear lens tissue and aspirate the emulsified lens tissue and fluid out of the eye. Cutting tube motion is described in more detail below. As used herein, “oscillate” or “oscillating movements” can include any periodic, repetitive movement that occurs according to a pattern and need not be sinusoidal. The oscillating movement can include reciprocating sliding movements that occur in a back and forth manner relative to the hand-held unit as described above. The oscillating movement can include repeatedly advancing and retracting the cutting tube along its longitudinal axis. The repeated advancing and retracting may occur along the longitudinal axis, but the path the oscillating movements take need not be linear. The path of movement can occur non-linearly (i.e. away from the longitudinal axis during at least a portion of the movement) along an elliptical pathway or a curvilinear pathway. The path of movement can be rotational, orbital, or torsional around the longitudinal axis of the device or other type of movement relative to the longitudinal axis of the device including three-dimensional movements in which the cutting tube moves back and forth as well as from side-to-side. The oscillating movements include profiles of repetitive patterns that may change depending on where in the cycle of oscillation the movement occurs. The oscillating movements can be asymmetric in profile, as will be described in more detail below. 
     The elongate component of the instrument being oscillated may be referred to herein as a “shaft” or “cutter” or “cutting tube” or “elongate member” and can be configured for different techniques, including phacoemulsification, vitrectomy, bag polishing, or other technique. At least a portion of the cutter can be tubular and having an internal lumen extending through it such that fluids can be delivered and/or aspirated through the internal lumen between a distal opening and a proximal opening from the lumen. 
     Any of a variety of configurations of the elongate cutting tube  1112  are considered herein. The cutting tube  1112  may have inner and outer members or the cutting tube  1112  can include only a single tubular element configured to oscillate relative to the hand piece  1030  to cut and aspirate material. Where the cutting tube  1112  is described as having an inner elongate member coaxially arranged within an outer tubular member the inner elongate member can be a solid rod and need not include an inner lumen. In some implementations, the cutting tube  1112  has a sharpened cutting tip or bevel, which can include a needle tip. The hand piece  1030  can include a cutting element having a sharpened needle tip and can be a solid element extending through an outer tubular member and aspiration forces applied through the lumen of the outer tubular member such that fluids and tissues are drawn into an annular gap extending between the inner and outer members. The cutting tube  1112  can have an inner lumen  1110  and distal edge configured to cut tissue. The distal edge can be sharpened while the opening into the tube can be cut at an angle to the elongate axis of the elongate member or perpendicular to the elongate axis of the elongate member. The inner lumen  1110  of the cutting tube  1112  can be configured to aspirate material therethrough, such as ocular lens material, lens fragments, vitreous, and/or fluids from the eye. Thus, aspiration forces can be applied through the inner lumen  1110  of the cutting tube  1112 . However, aspiration forces can also be applied through a lumen of a tubular outer member extending over the cutting tube  1112  such that aspiration occurs through the annular space between the two. In such a configuration, the gap between the tubular outer member and the inner member can vary, for example, between about 0.001″ to about 0.100″. In some implementations, the aspiration forces can be applied through both the inner elongate member having a lumen and the lumen through the outer tubular member. 
       FIG. 6  and also  FIG. 9A  illustrate a distal end region of the disposable portion showing the cutting tube  1112  extending beyond a distal end of the irrigation sleeve  1113 . The irrigation sleeve  1113  may include one or more openings  1111  near its distal end through which irrigation fluid may be delivered into the eye near the terminus of the cutting tube  1112 . The irrigation sleeve  1113  can extend proximally over the cutting tube  1112  and couple with a distal end region of the disposable portion  1031 . The distal end region of the disposable portion  1031  can include a nose cone or tip  1132  configured to receive the irrigation sleeve  1113 . The tip  1132  and the irrigation sleeve  1113  can each be removably attached to the hand piece  1030 . The irrigation sleeve  1113  can be a standard irrigation sleeve (e.g. irrigation tips by MST, Redmond, Wash.) having a substantially flexible, distal tubular portion  1117  and a less compliant, proximal coupling portion  1118 . The tip  1132  can include external threads  1133  (see  FIG. 9B ) or other coupling features on a front end region configured to engage with corresponding threads or features on the proximal coupling portion  1118  of the irrigation sleeve  1113 . 
     The tip  1132  can be configured for any of a variety of techniques a user desires to perform with the hand piece  1030  during a procedure. Any of a variety of tips  1132  may be reversibly coupled to the distal end region of the disposable portion  1031  depending on the procedure in the eye a user desired to perform. The tips  1132  may be configured for phacoemulsification, bag polishing, vitrectomy, and other procedures. The tip  1132  can be reversibly coupled to the disposable portion  1031 .  FIG. 7A  illustrates the distal end region of the disposable portion and the cutting tube  1112  without the tip  1132  being attached.  FIG. 7B  illustrates a first implementation of an exchangeable tip  1132  and  FIG. 7C  illustrates a second implementation of an exchangeable tip  1132 . The proximal end region of the exchangeable tip  1132  can incorporate a reversible coupling feature  1136  and a sealing element  1138  such as an O-ring. The configuration of the coupling feature  1136  can vary including, but not limited to threads, snap lock, interference fit, bayonet, or other feature configured to allow the tip  1132  to affix to and seal with the disposable portion  1031 . 
     The exchangeable tip  1132  shown in  FIG. 7B  includes a lens removal protective sleeve  1130  configured to be used during phacoemulsification. The lens removal protective sleeve  1130  can be fixedly coupled and extend from the distal end region of the tip  1132 . The lens removal protective sleeve  1130  is sized and shaped to be positioned concentrically over the cutting tube  1112  along at least a portion of the proximal length of the tube  1112 . The lens removal protective sleeve  1130  is configured to protect corneal tissues from damage where the cutting tube  1112  extends through the corneal incision during cutting tube  1112  motion when performing phacoemulsification. The lens removal protective sleeve  1130  may be formed of substantially flexible material such as silicone or substantially rigid materials such as a rigid plastic extrusion or metal hypotube. In some implementations, the lens removal protective sleeve  1130  can be a rigid tube having an inner diameter that is closely matched to an outer diameter of the cutting tube  1112  resulting in a low clearance between the two. The low clearance between the cutting tube  1112  and the lens removal protective sleeve  1130  means the lens removal protective sleeve  1130  maintains a small outer diameter such that the incision size through the cornea is minimized while still allowing for relative sliding between the inner and outer shafts. The cutting tube  1112  can have a maximum outer dimension of between 0.5 mm and 1.4 mm. The lens removal protective sleeve  1130  may be rigidly coupled to the tip  1132 , exchangeable, or may be retractable. The length of the lens removal protective sleeve  1130  can vary, but is generally at least as long as necessary to cover the region of the cutting tube  1112  that extends through the incision. A user can cover the oscillating cutting tube  1112  and use a different sort of tip during a procedure, for example for capsular bag polishing and cortical tissue removal following lens extraction. Longer length of the lens removal protective sleeve  1130  can cover half the stroke length of the oscillating cutting tube  1112 , thereby reducing exposed stroke length of the oscillating cutting tube  1112 . The lens removal protective sleeve  1130  can be longitudinally positionable such that the effective stroke length of the oscillating cutting tube  1112  can be adjusted from zero to 100% of its uncovered stroke length. The lens removal protective sleeve  1130  can also be positioned so that the oscillating cutting tube  1112  remains recessed a certain depth within the lens removal protective sleeve  1130 . This can prevent ocular tissue from coming into contact with the oscillating cutting tube  1112 , and effectively resulting in a suction-only mode of operation. The lens removal protective sleeve  1130  when positioned to reduce the effective cutting tube stroke length can prevent tissues from lollipopping&#39; on the end of the cutting tube  1112  by pushing stuck tissue off the cutting tube  1112  as the cutting tube  1112  tip retracts within the lens removal protective sleeve  1130 . 
     The color of the exchangeable tip  1132  and/or the sleeve of the tip  1132  can provide information regarding the length of the sleeve and for what purpose it is useful.  FIG. 7B  shows a lens removal tip  1132  having a shorter lens removal protective sleeve  1130  configured for protecting the cornea during phacoemulsification.  FIG. 7C  shows a bag polishing tip  1132  having a longer bag polishing protective sleeve  1131  coupled to a bag polishing nub  1142  (see also  FIGS. 8A-8C ). The lens removal tip  1132  may be a first distinguishable color such as blue and the bag polishing tip  1132  may be a second distinguishable color such as white. Other markers, indicators, colors, are considered as well for easily distinguishing between the tips. The bag polishing protective sleeve  1131  of the bag polishing tip  1132  in  FIG. 7C  has a length sufficient to receive the cutting tube  1112  such that the distal end of the cutting tube  1112  is always contained within the bag polishing protective sleeve  1131  with the inner lumen of the bag polishing nub  1142  extending beyond the distal tip of the fully extended cutting tube  1112  thereby completely isolating cutting tube  1112  action from ocular structures.  FIGS. 8A-8C  illustrate the bag polishing tip  1132  positioned on the distal end region of the disposable portion  1131 . The cutting tube  1112  is fully contained within the bag polishing protective sleeve  1131 . The bag polishing nub  1142  is positioned beyond the distal tip of the irrigation sleeve  1113 . 
     Surgeons commonly perform a bag polishing step following lens removal cataract. The bag polishing nub  1142  is gently slid along the surface of the capsular bag to release any adhered cortical material. The cortical material that is released is then aspirated through small holes in the bag polishing nub  1142 . The nub  1142  may include a small hole  1143  through at least one side of its diameter (see  FIG. 8C ). The hole(s)  1143  may have any of a variety of sizes, shapes, and distributions along the wall depending on the overall number of holes  1143  incorporated. The hole  1143  may have a diameter in the range of about 0.002″ to about 0.030″, or preferably about 0.008″ to about 0.012″. In an implementation, the hole  1143  may face downward relative to the perspective of a user holding the hand piece  1030  or may face sideways or upwards relative to a user holding the hand piece  1030 . In some implementations, the hole  1143  may be partially or fully on the distal face of the nub  1142 . The distal face of the nub  1142  may be substantially rounded such as a semi-hemispherical shape or the distal face may be substantially flat. The flat face of the nub  1142  may be angled relative to the diametrical axis of the nub  1142 . A relief hole may be positioned along at least a portion of the bag polishing tip  1132 , such as the bag polishing protective sleeve  1131  or the nub  1142 . The relief hole may be substantially smaller than the hole  1143 , for example about 0.0001″ to about 0.008″, or more preferably between 0.001″ to about 0.004″. The relief hole may function as a bypass when the hole  1143  is occluded. The relief hole also allows vacuum to dissipate when the hole  1143  is occluded and the user releases a trigger  1180  on the hand piece  1030  when the hand piece  1030  is idle. Any accumulated vacuum may dissipate via the movement of fluid through the relief hole. The nub  1142  may include a surface texture for freeing the cortical tissue. The shape of the nub  1142  may be substantially atraumatic such that contact between the nub  1142  and the capsular bag does not risk puncturing the capsular bag during scrubbing motions. 
     It should be appreciated any of a variety of accessory tips can be coupled to the distal end of the disposable portion  1031 . In some implementations, a vitrectomy style cutting sleeve having a side opening for cutting in a guillotine style fashion. The sleeve can be inserted over the cutting tube  1112  such that the cutting tube  1112  extends through and is coaxially arranged within an outer tube such that the cutting tube  1112  slides reciprocally within the outer tube. This style cutting element can be particularly useful for chopping and removing harder lens material. The outer tube can be a stationary tubular element coupled to a distal end region of the hand held portion  1030  and the cutting tube  1112  can be movable such that it can oscillate within the lumen of the outer tube. The distal tip of the cutting tube  1112  can be formed into a cutting edge, such as a short, sharpened bevel. In operation, tissue may enter into the outer tube through the side opening and be dissected by the cutting edge as the cutting tube  1112  is reciprocated within the outer tube. This vitrectomy style cutting tip can further include a removable or retractable outer sheath for sliding over the side openings, for example, during insertion of the shaft into the anterior chamber. During insertion, the cutting area of the shaft can remain covered within the outer protective sheath to prevent snagging on the incision or other eye tissues prior to cutting. After insertion, the sheath can be retracted or otherwise removed when the operator is ready to start cutting and/or aspirating. The retraction can be manually activated by a user or can be automatically retracted by the device upon actuation of cutting and/or aspiration. After cutting/aspiration is complete and the instrument is ready to be removed from the eye, the sheath can be advanced distally to once again cover the openings. 
     The exchangeable tips  1132  can be used with cutting tubes  1112  that are substantially straight, particularly where the sleeves of the tips  1132  are rigid. In some implementations where the cutting tube  1112  is curved away from the longitudinal axis or incorporates a feature angled relative to the longitudinal axis, the sleeve of the exchangeable tips  1132  may be flexible to allow for the sleeve to insert over the cutting tube  1112 . 
     A single reusable driver portion  1033  can be configured to operatively couple with one or more disposable working portions  1031  in an interchangeable manner. The disposable working portions  1031  can be configured for different types of procedures including lens fragmentation, emulsification, vitrectomy, bag polishing, aspiration, irrigation, coagulation, illumination, visualization, IOL insertion, and others. The disposable working portions  1031  therefore may be used for any of a variety of procedures including vitrectomy, phacoemulsification, intraocular lens insertion, etc. The operating parameters of the instrument can differ according to, for example, the disposable working portion  1031  attached to the reusable driver portion  1033  and/or the particular procedure being performed, the different stages of the procedure, the surgeon&#39;s personal preferences, whether the procedure is being performed in the anterior or posterior portion of the patient&#39;s eye, and so on. The components of the working portion  1031  can vary depending on the type of procedure and each of the different working portions  1031  regardless the procedure it is configured to perform can operatively couple and be operated by a single reusable driver portion  1033 . The different disposable working portions  1031  will be described in more detail below. 
     Again with respect to  FIGS. 5A-5B , the irrigation fluid line  1034  can connect to the disposable portion  1031  of the hand piece  1030  via an irrigation port  1144 . The location of the irrigation port  1144  can vary, but generally the irrigation port  1144  is arranged relative to the irrigation fluid line  1034  such that the irrigation fluid line  1034  is not integrated or embedded within or extending through a significant length of the hand piece  1030  as is the case with conventional hand pieces. In an implementation, the irrigation port  1144  can be located near a distal end region of the disposable portion  1031  near where the irrigation sleeve  1113  couples with the tip  1132 . The irrigation port  1144  provides a substantially rigid connection to the otherwise flexible irrigation line  1034  such that fluid from the irrigation source  1032  may be delivered through the irrigation sleeve  1113  to the eye. The location of the aspiration port  1154  can also vary. 
     The irrigation source  1032  can couple to the irrigation sleeve  1113  via the irrigation fluid line  1034 . The irrigation sleeve  1113  can extend over at least a portion of the protective sleeve  1130 ,  1131  as shown in  FIG. 8C or 9A . The irrigation sleeve  1113  can be removed from the hand piece  1030 , for example, as part of a removable tip  1132  or removed individually from the tip  1132  via threads or other coupling feature.  FIG. 9A  shows the irrigation sleeve  1113  threaded onto a forward end of the tip  1132  having external threads  1133  and extending over a proximal region of the cutting tube  1112 . 
     In some implementations, the hand piece  1030  can incorporate an irrigation fluid reservoir  1046  in communication with the irrigation flow path between the irrigation port  1144  and the irrigation sleeve  1113 . In an implementation, the irrigation fluid reservoir  1046  is located within the tip  1132  near the distal tip of the disposable portion  1031  of the hand piece  1030  allowing for virtually immediate replenishment of the aspirated fluid volume (see  FIG. 9B ). The reservoir  1046  can be configured to store an amount of fluid from the irrigation line  1034  near where the irrigation fluid is being delivered through the sleeve  1113 . The reservoir  1046  can fill with irrigation fluid such that in the event of a cutting tube occlusion and the resulting increase in vacuum pressure, the sudden outrush or “surge” of fluid removed when the occlusion resolves, the irrigation fluid stored up in the reservoir  1046  can be available to very quickly replace the surge volume removed. The fluid from the reservoir  1046  can be pulled into the eye almost instantaneously upon the increase in negative pressure to maintain sufficient pressure within the eye to avoid collapse of the anterior chamber. The reservoir  1046  can be a compliant chamber such as balloon or elastic membrane, or incorporate another compliant element configured to urge fluid out of the reservoir  1046  when there is a decrease in anterior chamber pressure. In some implementations, the reservoir  1046  is contained on one end by a spring-loaded piston that may elastically move such that the volume of the fluid in the reservoir  1046  changes as the pressure within the eye changes. The piston may be connected mechanically to the pumping mechanisms of the device such that any pulses of suction are actively timed with inspiration of fluid into the eye. 
     The distal cutting tube  1112  including any protective sleeves, tips, or irrigation sleeves can have a maximum cross-sectional diameter that is suitable for minimally-invasive procedures in the eye to minimize the corneal incision size. In some implementations, the maximum cross-sectional diameter of the cutting tube  1112  is about 1.25 mm. The maximum cross-sectional diameter can be smaller than this or can be larger than this diameter, for example, no more than about 2 mm in diameter, no more than about 3 mm in diameter, up to about 4 mm in diameter, or up to about 5 mm in diameter. As described elsewhere herein, a distal opening from the cutting tube  1112  can have a smaller inner diameter in relation to the inner diameter of the remainder of the lumen  1110  extending through the cutting tube  1112  to mitigate problems with clogging. In some implementations, the difference between the nominal inner diameter of the cutting tube  1112  and the inner diameter of the distal opening can be between about 0.003″ to about 0.006″. In some implementations, the cutting tube  1112  can have a nominal inner diameter of about 0.0375″ that narrows at the distal opening to about 0.033″. The nominal inner diameter of the cutting tube  1112  can be between about 0.012″ to about 0.036″. Thus, eye tissue pieces that are smaller than the tip diameter can be aspirated through the lumen  1110  of the cutting tube  1112  and once inside the lumen  1110  are less likely to get stuck or cause a clog because the inner diameter of the remainder of the lumen  1110  is larger than the inner diameter of the distal opening. 
     Again with respect to  FIGS. 5A-5B , the phacoemulsification hand piece  1030  can include an integrated aspiration pump  1014  within the disposable portion  1031  of the hand piece  1030 . The aspiration pump  1014  can be located in, on, or otherwise near the hand piece  1030  thereby minimizing a length of the aspiration line  1038  between the vacuum source provided by the pump  1014  and the distal tip of the cutting tube  1112  within the eye  36 . Incorporating a vacuum source within the hand piece  1030  (e.g. near the distal cutting tip) minimizes the volume of the aspiration flow path improving control and responsiveness while decreasing latency or hysteresis. Conventional phaco devices and other devices using a vacuum source remote from the hand-piece suffer from slow responsiveness and lower effective vacuum applied at the treatment site. Conventional systems have long, compliant suction lines connecting the vacuum source to the hand-piece. Compliance within a fluidic system can increase the time for suction to be transmitted from the suction source to the treatment site when the suction source is activated (and deactivated). Compliance within a fluidic system can also contribute to losses in vacuum transmitted to the treatment site resulting in the effective vacuum amount being different from the theoretical vacuum setting at the source. Additionally, the longer the fluidic lines between the vacuum source and the treatment site, the greater the friction losses, further reducing the vacuum available at the treatment site. For example, a remote vacuum source set at 600 mmHg may effectively transmit to the treatment site only 200 mmHg during some periods. The latency and hysteresis in conventional phaco devices having a remote vacuum source causes these designs to be susceptible to surges in fluid volume aspirated following a clog, particularly when the vacuum source is set at the higher flow rates. The actual surge volume in conventional systems is approximately equal to the degree of volumetric compliance in the suction line extending between the remote vacuum source and the hand-piece, which can be quite large (e.g. greater than 20 mL in some instances). This is a large surge volume to manage considering average patients have an anterior chamber volume of less than 0.3 mL. Users tend to set the vacuum source to lower levels to mitigate the increased surge volume risk associated with higher flow rates. 
     The hand pieces described herein can apply greater effective vacuum at the treatment site and more rapidly respond to pressure changes, and by avoiding the line losses associated with conventional systems. The hand pieces described herein have improved responsiveness and control even when used as higher vacuum settings. If an occlusion occurs due to a piece of lens blocking the distal opening, the vacuum will build (e.g. up to about 500 to 600 mmHg or more). When the blockage passes breaking the seal, the surge associated with the devices described herein is significantly improved as compared to conventional devices having remote vacuum sources. For example, the surge volume of the devices described herein can be as low as about 100 cubic mm, 200 cubic mm, or no more than about 300 cubic mm, whereas conventional phaco machines can have surge volumes that can be 10×, 20×, 50×, or 100× greater than this volume. The surge volume is smaller because the hand pieces described herein have a comparatively shorter aspiration flow path between vacuum source and target treatment site. The short aspiration flow path may also be substantially rigid or non-compliant, which further reduces the surge volume. For example, greater than 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% of the aspiration flow path of the devices described herein can be rigid resulting in no more than 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50% compliance in the aspiration flow path. The substantially non-compliant and short aspiration flow path of the devices described herein reduces the potential surge volume and also reduces the dead space that can contribute to the latency effect and lack of responsiveness. 
     The configuration of the pump  1014  within the hand piece  1030  can vary. Preferably, the aspiration pump  1014  has a small form factor such that it does not significantly impact the relative ergonomics of the hand piece  1030 . The aspiration pump  1014  can be a piston pump, roller pump, peristaltic pump, linear peristaltic pump, scroll-type pump, venturi, rotary vane, gear, screw, diaphragm, centrifugal, or other pump. In an implementation, the aspiration pump  1014  of the hand piece  1030  is a roller or peristaltic pump (see  FIGS. 5A-5C ). In another implementation, the aspiration pump  1014  of the hand piece  1030  is a piston pump (see  FIGS. 13A-13L ). In another implementation, the aspiration pump  1014  of the hand piece  1040  is a linear peristaltic pump (see  FIGS. 221-22D, 23A-23D, 24A-24B ). The aspiration pump  1014  can be the piston pump described in U.S. Patent Publication No. 2018/0318133, published Nov. 8, 2018, which is incorporated by reference herein. 
     The pump  1014  can be configured to apply continuous, semi-continuous, and/or pulsatile aspiration. The hand piece  1030  can also include more than a single aspiration source where each source may be programmed to apply (simultaneously, if desired) different flow rates. For example, the hand piece  1030  may include a first aspiration pump internal to the hand piece  1030  configured to apply a continuous or semi-continuous flow rate (low-level or high-level aspiration) and a second aspiration pump internal to the hand piece configured to apply a pulsatile flow rate. The different flow rates and flow types can also be applied by a single pump that may be selectively activated to achieve the different aspiration types. 
     In an implementation and as shown in  FIGS. 5A-5C , the aspiration pump  1014  of the hand piece  1030  is a roller pump or peristaltic pump contained within the housing  1145  near distal end of the disposable portion  1031  of the hand piece  1030  configured to draw fluid and materials into the distal tip of the cutting tube  1112  and direct it toward the waste line  1038 . The aspiration pump  1014  can include a roller housing  1146 , one or more peristaltic rollers  1148 , and fluid tubing  1150  contained within a peristaltic housing wall, which can be formed by the inner surface of the housing  1145  of the disposable portion  1031 . The fluid tubing  1150  can be wound in a helical or spiral configuration from near the distal end of the housing  1145  towards the proximal end of the housing  1145 . The number of helices or complete turns the fluid tubing  1150  makes can vary, but may be at least 1, 2, 3, 4, or 5 turns. The fluid tubing  1150  can be in communication with the lumen  1110  of the cutting tube  1112  such as via a port (not shown) at a first end and in communication with the aspiration port  1154  at a second end. The waste line  1038  can connect to the disposable portion  1031  via an aspiration port  1154 . Alternatively, the waste line  1038  does not need to connect to an aspiration port  1154  per se and can be a continuation of the same tubing line  1150  of the roller pump  1014 . The one or more peristaltic rollers  1148  can be radially disposed cylindrical pins configured to compress the fluid tubing  1150  against the inner, peristaltic housing wall  1145 . The number of rollers can vary including 1, 2, 3, 4, 5, or more rollers  1148 . As the peristaltic rollers roll along the tubing  1150 , fluid is urged towards the waste line  1038  as well as drawn into the lumen  1110  of the cutting tube  1112 . The peristaltic rollers  1148  may be positioned between the co-axial roller housing  1146  and the fluid tubing  1150 , and the fluid tubing  1150  may be positioned between the peristaltic rollers  1148  and the peristaltic housing wall  1145 . The rollers  1148  may be rolled by the inner, coaxial cylindrical roller housing  1146  and thus, the aspiration pump  1014  functions like roller bearings with rolling pins. Alternatively, the relative locations of the tubing  1150  and pins  1148  and roller housing  1146  can be reversed such that the rollers exist at a larger radius than the tubing, squeezing the tubing to the inside. The roller housing  1146  can be a cylindrical element having a proximal end that is driven by the pump motor  1115  within the durable portion  1033  of the hand piece  1030 , which will be described in more detail below. The roller housing  1146  can couple with the pump motor  1115  upon coupling the disposable portion  1031  with the durable portion  1033 . Any of a variety of coupling features are considered herein. For example, the roller housing  1146  and the pump motor  1115  can couple together via a dog clutch or spline or other type of reversible coupling that connects two rotating components. The proximal end of the roller housing  1146  can include a set of regularly spaced recesses (or protrusions) that engage with a set of corresponding protrusions (or recesses) on the distal end of the motor  1115 . Alternatively, the rollers  1148  and roller housing  1146  may be part of the reusable portion instead of the disposable portion thereby eliminating the need for the coupling mechanism that connects the two rotating components and reducing the disposable portion component cost. 
     The vacuum can be applied by the aspiration pump  1014  in the hand piece  1030  in disconnected pulses of negative pressure, for example, by actuation of one or more valves or due to movement of one or more pistons or by the pattern of the roller movement. As described elsewhere herein the cycling of the negative pressure pulses and positive pressure pulses can vary (e.g. between 1 Hz and about 10,000 Hz, or 100 Hz to about 5,000 Hz, or about 500 Hz to about 2000 Hz) and very small volumes (e.g. 10 uL up to about 1 mL). The cycling of negative pressure can be very fast (e.g. between about 5,000 Hz to about 10,000 Hz) or can be not as fast (e.g. 1 Hz up to about 1000 Hz). 
     Peristaltic pumps may provide negative pressure in a less pulsatile manner than, for example, piston pumps. Still, peristaltic pumps may create somewhat uneven, semi-continuous aspiration. As each roller  1148  contacts the tubing  1150  and starts to roll there may be a brief pause in vacuum generation. As the roller  1148  moves, the vacuum generation is relatively smooth until the next roller  1148  makes contact with the tubing  1150  and so on. Thus, pulsation with the peristaltic pump can be achieved depending on the number of rollers  1148  and the timing of roller  1148  contact with the tubing  1150 . In contrast, piston pumps can create a sharp spike in vacuum as the piston retracts backwards. This sharp spike in vacuum can be leveraged to create pulsatile aspiration, for example, by incorporating a plurality of pistons retracting sequentially. 
     It should be appreciated that conventional phacoemulsification hand pieces (e.g., those utilizing piezoelectric resonant drive systems) can incorporate an aspiration pump within or on the hand piece as described above. The aspiration pump can be positioned near the distal end of the hand piece, for example, in front of the piezoelectric crystals. The aspiration pump can also be positioned near the proximal end of the hand piece, for example, behind the piezoelectric crystals. The pump can be integrated with the hand piece or coupled to a region of the hand piece in a snap-on or modular fashion to generate aspiration forces near the cutting tube and minimize the length of the compressible tubing. The aspiration pump on the conventional phacoemulsification hand piece can vary in configuration including peristaltic, linear peristaltic, scroll, piston, or other pump type as described elsewhere herein. 
     The pulsatile aspiration also can be achieved using valving in the hand piece  1030  to control exposure of the cutting tube  1112  to the vacuum pressure generated in the hand piece  1030 . The valving can be incorporated to provide more pulsatile, discontinuous aspiration regardless of the type of pump  1014  and regardless whether the pump is incorporated in the hand piece  1030  or external to the hand piece  1030 . For example, a conventional phacoemulsification system having a remote pump within the console may incorporate one or more valves near the cutting tube of the hand piece  1030  to control exposure of the cutting tube to the negative pressure generated. The one or more valves may be integrated within the hand piece positioned near a distal end (i.e. the location of the cutting tube) or near a proximal end of the hand piece. 
     The valves allow for a full vacuum to be applied through the cutting tube  1112  in short pulses. The one or more valves may be coupled to the hand piece  1030  and positioned along a portion of the aspiration path. The valve may be movable from a closed configuration that blocks the aspiration path towards a fully open position opening the aspiration path to the lumen of the cutting tube  1112 . The valve may be positioned in any position between the closed and fully open positions. The valve may be a movable element configured to move relative to an aperture to open and close the aspiration path. For example, the valve may be moved to a first position that exposes a small portion of the aperture. The valve may be moved to a second position that exposes a larger portion of the aperture. The valve may be moved to a first position for a period of time until the vacuum pressure within the cutting tube  1112  reaches a certain percentage of a target maximum pressure (e.g. 75% or 570 mmHg of a target 760 mmHg). Once the target vacuum pressure is reached, the valve may be actuated to move to achieve a cycling of the suction pressure. The first phase may help in establishing the desired suction pressure that is then transitioned to a cyclic/periodic or modulated phase of vacuum. Motion of the valve may be achieved manually upon actuation by a user or may be achieved automatically upon initiation of the pump  1014  or cutting tube  1112  motion. It should be appreciated that the valving of the aspiration through the cutting tube  1112  can be used to control application of aspiration from the pump  1014  within the hand piece  1030  or to control application of aspiration from a pump remote from the hand piece  1030 . 
     A small reservoir or vacuum accumulator may be incorporated within a region of the hand piece  1030 . The accumulator may maintain the vacuum level achieved by the aspiration pump  1014  in the hand piece  1030  for a period of time. Momentary opening of the one or more valves within the hand piece  1030  may expose the vacuum reservoir to the lumen  1110  of the cutting tube  1112  enables the discontinuous, pulsatile application of suction. In some implementations, the valve is one as described in U.S. Publication No. 2018/0318132, filed May 3, 2018, and which is incorporated by reference herein. The configuration and arrangement of the valves can vary including poppet, ball, needle, leaf, pinch, or other rotationally sliding type of valve useful for controlling vacuum. 
       FIG. 5C  illustrates an implementation of a valve within the hand piece  1030  configured to momentarily expose the lumen  1110  of the cutting tube  1112  to vacuum. The vacuum may be stored within an accumulator or any internal volume space available within the vacuum system. As discussed above, the roller housing  1146  may be a cylindrical element driven to rotate by the pump motor  1115 . The roller housing  1146  may include an inner bore  1147  that is configured to be placed in fluid communication with the lumen  1110  of the cutting tube  1112  through one or more through-holes  1149  in the cylindrical wall of the roller housing  1146 . When the through-hole  1149  in the roller housing  1146  aligns with an opening from the inner lumen  1110  of the cutting tube  1112  the lumen  1110  is exposed to vacuum created by the aspiration pump  1014 . The more through-holes  1149  in the wall of the roller housing  1146 , the greater the number of vacuum pulses per rotation of the housing  1146 . Communication between the through-holes  1149  and the inner lumen  1110  may be sealed with one or more O-ring seals  1151 . 
     Additionally, the cycles of negative pressure can be interspersed with short regurgitation via application of positive pressure between pulses of negative pressure. In some implementations, the cycles of negative pressure include short periods of vacuum interspersed by short periods of decreasing vacuum or no vacuum. In some implementations, the cycles of negative pressure include short periods of vacuum interspersed by short periods of positive pressure thereby resulting in a short regurgitation of fluid through the cutting tube, for example, between each roll of the peristaltic pin or during each cycle of piston movement. 
     Whether or not positive pressure is applied between the pulses of vacuum, the pulsatile vacuum creates pulses of discontinuous negative pressure through the cutting tube that can be between about 4 inHg up to about 30 inHg, preferably as close to full vacuum as possible with very little loss in pressure. In some implementations, the hand piece  1030  can create pulses of discontinuous negative pressure through the internal lumen of the cutting tube  1112  at a cycling frequency. The hand piece  1030  can also create pulses of discontinuous positive pressure having the same cycling frequency. Thus, the pulses of discontinuous negative pressure are interspersed by the pulses of discontinuous positive pressure. The cycling frequency of the pulses can be a relatively fast frequency, for example, at least about 0.5 Hz up to about 5000 Hz, or between 1 Hz and 4000 Hz, or between about 10 Hz up to about 2000 Hz. In some implementations, the cycling frequency of the pulses of discontinuous negative pressure is between about 1 Hz up to about 500 Hz. The pulses of discontinuous negative pressure aspirate a first amount of material into the internal lumen through the opening at the cycling frequency. The pulses of discontinuous positive pressure expel a second amount of material at the cycling frequency from the internal lumen through the opening. The volume of material being moved per cycle can vary, but is generally relatively small, for example, between about 0.1 mL up to about 1.0 mL, or approximately 0.5 mL. In some implementations, the nominal amount of fluid removed per pulse is about 100 microliters, or between 10 microliters up to about 1000 microliters. The second amount of material can be substantially less than the first amount of material within this general range of fluid amounts. The pulses of discontinuous negative pressure can be interspersed by discontinuous periods of lessening vacuum, no vacuum, or positive pressure at the same frequency. 
     In some implementations, the hand piece  1030  is limited from achieving maximum vacuum by incorporating a feature that automatically bypasses the cutting tube lumen  1110  depending on whether a threshold vacuum is reached. For example, a bleed valve, shunt, or other bypass mechanism can be incorporated to prevent a threshold amount of vacuum from being applied at a distal opening of the cutting tube  1112  and into the eye. A bypass to turn on or off the suction can limit the maximum amount of vacuum that can be generated within the eye even if the opening into the cutting tube  1112  is clogged. This bypass can prevent the vacuum from building in the event of cutting tube tip occlusion to decrease surge upon removal of that blockage. The bypass mechanism can be adjustable or selective such that a user can choose whether or not they want the potential for maximum vacuum or something less than maximum vacuum applied. An implementation of a vacuum bypass is described in more detail below with respect to  FIG. 13L . 
     The disposable portion  1031  or the durable portion  1033  of the hand piece  1030  can include one or more inputs or actuators. The one or more inputs can vary including such as a trigger, button, slider, dial, keypad, switch, touchscreen, or other input that can be retracted, pressed, squeezed, slid, tapped, or otherwise actuated to activate, modify, or otherwise cause a response of the hand piece  1030 . In an implementation, the hand piece  1030  includes a trigger  1180  positioned on a region of the disposable portion  1031  (see  FIG. 6  and  FIG. 12 ). The one or more user inputs can also be remote from the hand piece  1030  (e.g. on the system  1010  or on an external computing device in operative communication with the system  1010 ) or in a wired or wireless actuating device such as a foot pedal. 
     The hand piece  1030  can include separate inputs to activate each function of the device and/or the system  1010  in operative communication with the device (i.e. cutting, infusion, aspiration, including continuous or semi-continuous aspiration, pulsed vacuum, and/or pulsed vacuum with regurgitation between pulses, etc.). Alternatively, the input can be a multi-way button or trigger  1180  to activate more than a single function. For example, the hand piece  1030  can be configured for fluid delivery, fluid aspiration, and cutting. The trigger  1180  can activate irrigation-only function, continuous aspiration-only function, irrigation-plus-continuous aspiration function, or irrigation-plus-pulsed aspiration-plus-cutting function, etc. Generally, cutting without aspiration is not desired, however, a cutting-only function is considered herein as well. As an example and not to be limiting, a user can activate a first button or place the trigger  1180  in a first position to turn on the irrigation-only function or continuous aspiration-only function. After the first button is activated, the user can then activate a second button or place the trigger  1180  in a second position to turn on the irrigation-plus-continuous aspiration function. The user can then activate a third button or place the trigger  1180  in a third position to turn on the irrigation-plus-pulsed vacuum-plus-cutting function. The user can then commence cutting while vacuum continues. In some implementations, the second trigger activation is only possible after the first trigger activation occurs. The input can be a multi-way trigger  1180  as described above that has a first position configured to turn on both vacuum and oscillate the cutting tube (i.e. vacuum-plus-cutting function) and a second position configured to pause oscillation of the cutting tube while the vacuum through the cutting tube continues. 
     In some implementations, the hand piece  1030  can allow suction within the system to dissipate, for example, when a user desires to release an inadvertently captured capsular bag or when the device is idle. The venting mechanism can be coupled functionally to the trigger  1180  of the hand piece  1030 , such as the multi-stage trigger  1180  shown in  FIG. 12 . When the trigger  1180  is idle, the venting mechanism can actively vent the device and when the trigger  1180  is activated to aspirate, the venting mechanism can be shut off. In some implementations, the trigger  1180  in its first, idle configuration can be biased upwards such that upon release of manual pressure on the trigger aspiration shuts off. Downward motion of the trigger  1180  can trigger aspiration (as well as irrigation and/or oscillation as described elsewhere herein). When the trigger  1180  is in the idle configuration and biased upwards, the system vents. When the trigger is urged downwards to activate aspiration, venting is turned off. 
     In some implementations, the drive mechanism can be a piezoelectric drive mechanism or motor-driven cam mechanism or vibrating motor with eccentric weight as described elsewhere herein capable of achieving side-to-side motion or “wag” of the cutting tube  1112  via a rocker, clamp, or other configurations (see, for example,  FIGS. 16A-21D, and 25A-25C, 26A-26C ) to translate the retraction and expansion of the piezoelectric along a first axis into motion of the cutting tube  1112  along a different axis that is generally orthogonal to the first axis. These cutter tube drive mechanisms can be positioned within the disposable portion as well. 
     As mentioned above and again with respect to  FIGS. 5A-5C , the reusable, durable portion  1033  of the hand piece  1030  may include the pump motor  1115  with or without a gearbox and a drive mechanism. The drive mechanism can include the horn  1116 , the piezoelectric crystals  1120  contained within the housing  1114 , and a power cord  1160  configured to connect to the control unit  1012  of a phacoemulsification system  1010  to provide ultrasonic power for the piezoelectric drive system as well as DC power for the pump motor  1115 . The piezoelectric crystals  1120  can be arranged coaxial to the longitudinal axis of the cutting tube  1112  for longitudinal motion and/or perpendicular to the longitudinal axis of the cutting tube  1112  for torsional motion. 
     Where the disposable portion  1031  is configured to come into contact with eye material, the durable portion  1033  is configured to remain outside of the eye and to not come into contact with material extracted from the eye. The cutting tube  1112  of the disposable portion  1031  may couple to the horn  1116  of the durable portion  1033 , which in turn is driven by the piezoelectric crystals  1120 . It should be appreciated that the durable portion  1033  may include any of a variety of drive mechanisms besides piezoelectric, such as magnetostrictive, electric, electromagnetic, hydraulic, pneumatic, mechanic, voice coil, or other type of drive mechanism. It should also be appreciated that the cutter tube drive mechanism can be within the disposable portion  1031  or with the durable portion  1033 . Each of these components will be described in more detail below. 
     The motor  1115  for the aspiration pump  1014  can be a brushless DC motor or any type of motor or driver suitable for rotating a shaft. In an implementation, the pump motor  1115  can be an electric motor including a stator  1162  and a rotor  1164 . The rotor  1164  can be a cylindrical shaped rotor configured to rotate due to interaction with the stator  1162 . The movable rotor  1164  can couple to the co-axial roller housing  1146  as described above via a dog clutch or other type of coupling. The connection between the aspiration pump  1014  and the pump motor  1115  may incorporate gear reduction via gearbox or other mechanism. In an implementation, the durable portion  1033  incorporates a HarmonicDrive gear reduction configured to achieve at least a 30:1 reduction. The speed of the motor  1115  can be controlled by a potentiometer linked to the trigger  1180  or a non-contact sensor configured to sense motion of the trigger  1180 . 
     In an implementation, the durable portion  1033  can include a potentiometer ribbon extending between a distal end region of the durable portion  3210  and configured to activate the potentiometer. For example, the proximal end of the potentiometer ribbon can include a cut-out or other feature configured to engage with the potentiometer such that movement of the ribbon impacts the activation of the potentiometer. The trigger  1180  can be linked to a button rod that is movable along a longitudinal axis of the device as the trigger  1180  is actuated into one of a plurality of position. For example, when the trigger  1180  is moved from a first actuated position, the trigger can move the button rod a distance proximal such that a proximal end of the button rod extends a first distance into the proximal durable portion of the hand piece. The extension of the button rod into the durable portion can impact the speed of the motor by interacting with the distal end of the potentiometer ribbon extending with in the durable portion. Movement of the potentiometer ribbon in turn can activate the potentiometer engaged with the cut-out of the ribbon. The potentiometer can, in turn, change the speed of motor rotation. In some implementations, a non-contact sensor such as a Hall Effect sensor may be used to sense the distance the button rod has moved as a result of the trigger being depressed. 
     Still with respect to  FIGS. 5A-5C , the motor  1115  can including a motor housing  1168  that is fixedly coupled to a forward end of the housing  1114  containing the multi-stack of piezoelectric crystals  1120 . The crystals  1120  may be held within the housing  1114  by a back cylinder  1122  and bolt  1124 . In other implementations, the piezoelectric stack can be part of the disposable portion as discussed above. 
     In conventional phacoemulsification, the piezoelectric crystal stack is driven at a very high frequency (e.g. 40,000 cycles/second) to achieve about 0.004″ amplitude (about 100 μm) at the distal cutting tip. The piezoelectric crystals in conventional phacoemulsification are driven at their resonant frequency of the system and thus, only sinusoidal, symmetric motion at the cutting tip can be achieved. The conventional piezoelectric stacks and resonant mass rely on harmonics for cutting tip motion and thus, asymmetric motion is not possible without increasing significantly the energy and/or causing significant vibration. 
     In the case of the hand piece  1030  described herein, the oscillating system mass may be reduced to the greatest degree possible allowing the cutting tube  1112  to be driven directly (with or without amplifying components such as a rocker or other feature) by the piezoelectric stack  1120  in a non-resonant manner at a frequency that is less than ultrasonic (below 20 kHz). Despite being driven in a non-resonant manner, the cutting tube  1112  can have some additional “whipping” motion that results in greater overall displacement of the cutting tube  1112  than would otherwise be predicted. 
     Direct piezoelectric drive allows for obtaining asymmetrical motion of the cutting tube  1112 , if desired, such that the retraction speed can be slower than the advancement speed. This allows for a fast advancement speed sufficient to achieve cutting, but a retraction speed kept below a cavitation threshold. In some implementations, this may include increasing the frequency of the piezoelectric crystal stack  1120 . As discussed above the length of the horn  1116  is typically designed such that the distal end of the horn  1116  is at least  1  half wavelength away from the end of the piezoelectric crystal stack  1120 . There are multiple ways to potentially reduce this length and thereby decrease the length and size of the horn  1116 . The equation for wavelength λ=c/f, where λ is the wavelength, c is the wave speed, and f is the frequency. In some implementations, the frequency can be increased in order to decrease the wavelength and therefore the required length of the horn  1116 . As described elsewhere in this application, certain implementations reduce the retraction speed of the cutting tube  1112  such that cavitation may be avoided. Using such devices and methods provides an opportunity to increase the frequency of the cutting tube  1112  such that the horn  1116  may be smaller without adversely increasing the amount of cavitation. In still other implementations, the stroke distance of the cutting tip  1112  can be reduced while the frequency of oscillation is increased. Therefore the retraction speed of the cutting tube  1112  remains below a critical cavitation inducing level. By increasing the frequency as described above, the horn  1116  may be smaller. 
     Cataracts are typically classified based on severity on a scale of 1 to 5. The hand piece  1030  incorporating a piezoelectric stack  1120  configured for non-resonant, direct drive of the cutting tube  1112  may be particularly useful for cataracts in a range of 1 to 3. Users may choose to switch to conventional resonant phacoemulsification for harder cataracts above 3 to about 4. The systems described herein may be configured to switch between ultrasound and non-ultrasound modes. Switching between modes can be achieved by switching hand pieces entirely. For example, the console may be configured to couple with a conventional phacoemulsification hand piece as well as a non-ultrasound, direct drive hand piece. In another implementation, the same hand piece may be driven at different frequencies. For example, the drive mechanism may include a voice coil type drive mechanism that can be programmed to drive the cutter tube at ultrasound frequencies or at non-ultrasound frequencies in order to achieve asymmetric cutter tube motion. 
     The displacement or travel distance of the cutting tube  1112  of the hand piece  1030  described herein can vary. The longitudinal amplitude or displacement of the tip of the cutting tube  1112  can be equal to or greater than conventional phacoemulsification needles (i.e. 100 um or 0.004″). The longitudinal amplitude can be achieved via direct drive and at a lower frequency than conventional phacoemulsification (e.g. about 10,000 cycles/second). In an implementation, the displacement achieved by the cutting tube  1112  can be between about 0.005 mm-1.0 mm at a frequency of oscillation of the distal tip that is about 0.5 Hz-10,000 Hz, 0.5 Hz to 5000 Hz, or more preferably between 2000 Hz and 5000 Hz, or between 2,500 Hz and 4,000 Hz, or between 3,000 Hz and 3,600 Hz. In some implementations, the frequency is about 3,200 Hz. In this way, the devices described herein would not be ultrasonic and therefore would avoid generating the heat and cavitation associated with harmful effects in the eye during cataract surgery. In some implementations, the cutting tube  1112  of the hand piece  1030  can have a greater amplitude or displacement distance while being moved at a lower frequency than conventional phaco needles. In some implementations, the cutting tube  1112  is moved 0.012″ to about 0.019″. The amplitude can be between 0.005 mm to about 1.0 mm, or more preferably between 0.05 mm to about 0.1 mm. The frequency of oscillation can be less than 30,000 Hz, less than 25,000 Hz, less than 20,000 Hz, less than 15,000 Hz, or less than 10,000 Hz and down to about 0.5 Hz, or down to about 1 Hz, or down to about 2 Hz, or down to about 5 Hz, or down to about 10 Hz, or down to about 25 Hz, or down to about 50 Hz, or down to about 100 Hz, or down to about 250 Hz, or down to about 500 Hz. The frequency of oscillation can be between about 0.5 Hz to about 30,000 Hz, or between 1 Hz to about 5000 Hz, or between about 2 Hz to about 2000 Hz. 
     As mentioned elsewhere herein, pulsatile vacuum may be applied through the cutting tube  1112  using the aspiration pump  1014  in the hand piece  1030 . The relative coordination of the pulses of vacuum and oscillating motion of the cutting tube  1112  can vary. A pulse of vacuum may be applied during at least a portion of the extension of the cutting tube  1112 . A pulse of vacuum may be applied during at least a portion of the retraction of the cutting tube  1112 . A pulse of vacuum may be applied during at least a portion of both extension and retraction of the cutting tube  1112 . In some implementations, the pulse of vacuum may begin before and be maintained during extension of the cutting tube  1112 . The pulse of vacuum may begin after extension of the cutting tube  1112  begins. A single pulse of vacuum may be applied during multiple extensions and retractions. For example, the vacuum may be applied continuously through the cutting tube  1112  during at least about 1 oscillation, at least about 2 oscillations, at least about 5 oscillations, at least about 10 oscillations, at least about 20 oscillations, at least about 30 oscillations, at least about 40 oscillations, at least about 50 oscillations, up to about 100 oscillations of the cutting tube  1112 . As an example, the cutting tube  1112  may oscillate 50 times during a single vacuum pulse that lasts 25 ms such that the frequency of oscillation of the cutting tube  1112  is about 2000 Hz. 
     The piezoelectric crystal stack  1120  in the hand piece  1030  can be longer than in conventional resonant drive phacoemulsification (e.g., about 2″ in length) in order to achieve the amplitudes found in conventional, resonant phacoemulsification systems. 
     Again with respect to  FIGS. 5A-5C , the horn  1116  can extend from a distal end of the piezoelectric stack  1120 . The piezoelectric crystals  1120  move the horn  1116 , which in turn moves the cutting tube  1112 . Upon coupling the disposable and reusable portions  1031  and  1033  of the hand piece  1030 , the horn  1116  can insert centrally through the aspiration pump  1014  in the disposable portion  1031 . The roller housing  1146 , the peristaltic rollers  1148 , and the tubing  1150  thereby can radially surround the horn  1116 . The distal end of the horn  1116  can extend through the inner bore  1147  of the roller housing  1146  and distally beyond the pump  1014  and is available near the distal end region of the disposable portion  1031  of the hand piece  1030  for coupling with the cutting tube  1112 . As best shown in  FIG. 5C  showing the disposable portion  1031  removed from the reusable portion  1033 , the horn  1116  can include an inner threaded recess  1170  configured to receive and engage with outer threads  1172  on a proximal end of the cutting tube  1112 . The proximal opening from the lumen  1110  of the cutting tube  1112  can communicate with the inner recess  1170  of the horn  1116 . The inner recess  1170  of the horn  1116  can include an opening or port  1176  configured to communicate with the helical tubing  1150  of the pump  1014 . This port  1176  allows for fluid and other material aspirated into the lumen  1110  of the cutting tube  1112  to enter the pump  1014  and be urged toward the waste line  1038 . Vacuum is applied to the inner lumen  1110  of the cutting tube  1112  upon alignment of the through-holes  1149  in the roller housing and the opening  1176  in the horn  1116 . As the roller housing  1146  rotates the through-holes  1149  and the opening  1176  in the horn  1116  go in and out of alignment with one another. This cycling effectively turns on and off aspiration through the cutting tube  1112 . 
     The horn  1116  can be formed of any suitable material or combination of materials for the purposes described herein. The material used for the horn  1116  affects the speed of sound in the horn material and therefore the length of the horn  1116  required such that the tip is located at least one half wavelength away from the piezoelectric crystals  1120 . The horn  1116  may be formed of aluminum, stainless steel, titanium, or other commonly used materials. For example, the speed of sound in titanium is on the order of 6,070 m/s. In some embodiments, other materials may be considered for the horn material that have lower speeds of sound. For example, copper has a speed of sound on the order of 3,900 m/s and lead has a speed of sound on the order of 1,300 m/s. The slower the speed of sound, the smaller the horn  1116  may be needed such that the end of the horn is at a maximum amplitude node. 
     In some implementations, the hand piece  1030  can incorporate a drive mechanism configured to directly drive the cutting tube  1112  forward and backward or oscillating the cutting tube  1112  side-to-side as described elsewhere herein, rather than relying on resonance. The piezoelectric stack  1120  can respond to changes in voltage by decreasing or increasing in size. A voltage profile powering the piezoelectric stack  1120  can generate a motion profile of the cutting tube  1112  to produce the desired cutting tube movement. In some implementations, the voltage waveform sent to the piezoelectric stack  1120  can be generally non-sinusoidal in shape and therefore the cutting tube  1112  moves in a generally non-sinusoidal pattern as described elsewhere herein. The voltage may have a waveform that contracts the piezoelectric stack  1120  slower than it allows it to expand. This moves the cutting tube  1112  slower on the retraction stroke than on the extension stroke. Any number of motion profiles may be commanded based on the voltage waveform supplied to the piezoelectric stack  1120 . For example, two or more overlapping voltage sinusoidal waveforms can be supplied to the piezoelectric stack  1120  that creates an interference effect such that a non-sinusoidal wave form is created. These drive mechanisms can be incorporated within the disposable or the reusable portions of the hand piece  1030 . In a preferred implementation, the drive mechanism incorporates a piezoelectric stack  1120  that is contained within the disposable portion of the hand piece  1030 . 
     In still further implementations, a combination of mechanisms and modalities are incorporated in the device to drive the cutting tube  1112  with a non-sinusoidal motion profile. For example, an electromagnetic coil can be configured to move a ferritic or magnetic core forward with the application of a current through the coil. The core can be configured to be driven forward by the electromagnetic coil, but then retract backwards (i.e. proximally) through the force of a compressed spring. Therefore, with an increase in current through the coil, the core is driven forward. With the current is reduced, the core retracts backward. In this manner, the core may be connected to cutting tube  1112  so that the extension forward can be executed quickly by the sudden increase in voltage in the coil, but the retraction may be slower by the force of the compressed spring. 
     The cutting tube  1112  can be driven so as to have an asymmetrical or sinusoidal motion profile. For example, some drive mechanisms providing a torsional cutting tube motion (see, e.g.,  FIGS. 16A-16D, 17A-17C, 18, 19A-19C, 20A-20B, 21A-21D, 25A-25C, 26A-26C, 27A-27B ) need not provide asymmetrical motion profiles. 
     The hand piece  1030  can be capable of multiple functions (i.e. irrigation, aspiration, and cutting functions) all while maintaining full portability, flexibility, and freedom of movement. The functions of the hand piece  1030  can be initiated using an input (trigger  1180 ) on the hand piece  1030  capable of being actuated with a single finger or thumb. Because the hand piece  1030  requires no foot pedal, a user can stand more comfortably and naturally (e.g. on two feet or shifting their weight from foot to foot however they please) to perform a procedure. As described above, the hand piece  1030  may be actuated using the one or more inputs or triggers  1180  on the hand piece  1030  and/or remote from the hand piece  1030  such as on the control unit of the system  1010 . The one or more inputs can be urged by a user into a position that causes the drive mechanism to ramp up one or more of the actions. For example, the trigger  1180  on the hand piece  1030  (or a foot pedal) can connect to the control unit that in turn interprets the signal and supply an appropriate drive waveform to the piezoelectric crystal stack  1120 . 
     Use of the term “hand piece” herein can include a hand piece that is coupled to a robotic arm or robotic system or other computer-assisted surgical system in which the user uses a computer console to manipulate the controls of the instrument. The computer can translate the user&#39;s movements and actuation of the controls to be then carried out on the patient by the robotic arm. Thus, where the term “hand” or “hand piece” is used herein it should be appreciated that the hand may be a surgeon&#39;s own hand or a robotic “hand” manipulating the hand piece. 
     Coupling Between Disposable/Durable Portions 
     As mentioned above, the hand piece  1030  can include the disposable portion  1031  that is configured to releasably couple to the durable portion  1033 . The disposable portion  1031  generally includes components configured to be exposed to human fluids and materials whereas the durable portion  1033  is intended to be reused with a new disposable portion  1031  coupled to it. The disposable and durable portions  1031 ,  1033  of the hand piece  1030  can couple together using a variety of mechanisms such as threads, snap-lock, bayonet lock, and the like. 
     In some implementations, the proximal end region of the housing  1145  of the disposable portion  1031  can define a chamber having a proximal opening through which at least a portion of the durable portion  1033  may be inserted and coupled to the disposable portion  1031  such as via bayonet lock mechanism (see  FIGS. 5A-5C ). For example, the horn  1116  and the motor  1115  within the motor housing  1168  may be inserted through the proximal opening of the housing  1145  of the disposable portion  1031  such that the motor housing  1168  is received within the chamber of the housing  1145 . The two portions  1031 ,  1033  may then be in locked engagement with one another such as via a bayonet lock mechanism by turning a certain number of degrees once the horn  1116  and motor housing  1168  are received within the chamber. The connection between the disposable and durable portions  1031 ,  1033  can be purely mechanical or both mechanical and electrical connection. It should be appreciated that the motor  1115  may also remain outside the chamber of the disposable portion such that only the horn  1116  or another portion of the durable portion  1033  is inserted within the disposable portion chamber. The durable portion  1033  may insert into the disposable portion until a forward end of the rotor  1164  engages with the proximal end of the roller housing  1146  of the aspiration pump  1014 . The two portions can be turned relative to one another (e.g. clockwise or counterclockwise) to fix the engagement and lock the two portions together. The coupling mechanism can include a release button configured to uncouple the two housing portions. In some implementations, the coupling can incorporate one or more markings on the respective housings to guide a user&#39;s alignment of the respective portions for insertion prior to locking. The locking mechanism between the portions can be mechanical such as a spring-loaded pin that must be retracted prior to detaching. The coupling between the disposable and durable portions creates a smooth continuous housing for the hand piece  1030 . 
     The coupling between the disposable and durable portions  1031 ,  1033  of the hand piece  1030  can incorporate one or more sealing elements to ensure the hand piece  1030  does not leak during use. For example, the one or more sealing elements may be O-ring type seals  1152  positioned to prevent leaks where the horn  1116  of the durable portion inserts within the disposable portion. For example, a first O-ring  1152  can be positioned distal to the opening from the recess  1170  in the horn  1116  and a second O-ring  1152  can be positioned around the horn  1116  on a proximal end of the recess opening (see  FIGS. 5A-5C ). Additionally, a compliant seal can be positioned around a proximal end region of the horn  1116  near where it extends outside the piezoelectric stack housing  1114 . In another implementation, the cutting tip  1112  can include one or more seals within the disposable portion  1031 . In this configuration, no fluid from the surgical site comes into contact with the disposable internally. This has the benefit of eliminating the potential for cross-contamination that exists with conventional phaco hand pieces. 
     As discussed above, some implementations of the cutter tube drive mechanism  119  can be part of the disposable portion  1031  of the hand piece (e.g.,  FIGS. 16A-16D ) whereas other implementations of the cutter tube drive mechanism  119  can be part of the reusable durable portion  1033  of the hand piece  1030  (see  FIGS. 5A-5C ). It should be appreciated that any of a variety of configurations are considered herein and the location of one or more components of the hand piece  1030  whether in the disposable or reusable portions can vary. 
     Other Pump Configurations 
     As mentioned above, the aspiration pump  1014  within the hand piece can be any of a variety of low profile aspiration pumps including a peristaltic pump, linear peristaltic, piston pump, scroll-type pump, and the like.  FIG. 5A-5C  illustrate an implementation of a hand piece  1030  having an aspiration pump  1014  that is a peristaltic pump.  FIGS. 22A-22B  illustrate an implementation of a hand piece having an aspiration pump  1014  that is a linear peristaltic pump.  FIGS. 13A-13L  illustrate various views of an implementation of a hand piece  1030  of a phacoemulsification system having an aspiration pump  1014  that is a piston pump. The aspiration pump can include one or more pistons  2799  movable within respective pumping chambers  2705  of a piston manifold  2798 . The pistons  2799  are powered by a drive mechanism such as a motor (not shown) that may be located within the durable portion  1033  of the hand piece  1030 .  FIGS. 13F-13H  shows a vacuum manifold  2774  coupled to the piston manifold  2798  such that a vacuum chamber  2703  of the vacuum manifold  2774  is in fluid communication with the one or more pumping chambers  2705  in the piston manifold  2798 . The one or more pistons  2799  powered by the motor generate a vacuum within the pumping chambers  2705  as well as the vacuum chamber  2703  for aspiration of material through the lumen  1110  of the cutting tube  1112 . 
     It should be appreciated that any number of pistons  2799  can be positioned within respective pumping chambers  2705 . Multiple pistons  2799  bouncing back and forth within their pumping chambers  2705  may create a pulsatile vacuum or full vacuum delivered to a distal portion of the lumen of the cutting tube  1112  in pulses of negative pressure. The pulsatile vacuum allows for application of full vacuum through the cutting tube  1112  without risk for collapse of the anterior chamber. While at the peak of the pulse, the system can generate a high vacuum. However, since it is pulsed, the average aspiration flow rate can be low enough for the irrigation inflow to maintain proper anterior chamber support even under these high vacuums at the pulse peak. 
       FIG. 14A  shows a notch or proximal opening  2788  in the cutting tube  1112  positioned within the vacuum chamber  2703 . Vacuum can pull lens material through the cutting tube  1112 . The lens material may exit the lumen  1110  of the cutting tube  1112  through the proximal opening  2788  and enter into the vacuum chamber  2703  of the vacuum manifold  2774 . Lens material is not intended to travel proximal of the proximal opening  2788  in the cutting tube  1112 . The vacuum chamber  2703  is configured to be in fluid communication with the one or more pumping chambers  2705  via a respective opening  2706  regulated by a one-way valve  2707  (see  FIG. 13I ). The configuration of the one-way valve  2707  can vary including a duckbill valve, ball check valve, lift-check valve, stop-check valve and other types of valves that allow flow of fluid in a single direction and cut-off flow of fluid in the opposite direction. Movement of the pistons  2799  in a first direction within the pumping chambers  2705  (i.e. proximally or towards the rear of the hand piece) creates a vacuum that can be supplied to the lumen of the cutting tube  1112  through the openings  2706  on the vacuum manifold  2774  that surround the cutting tube  1112 . A gasket  3262  separates the vacuum chamber  2703 , which can be defined by the cavity in the center, and the evacuation chamber  2709  (see  FIG. 14A ). Upon supplying vacuum to the lumen of the cutting tube  1112 , material from the eye is drawn into the lumen  1110  of the cutting tube  1112 , emptied into the vacuum chamber  2703 , and pulled through the one-way valve  2707  into the pumping chamber  2705 . Movement of the pistons  2799  in a second, opposite direction within the pumping chambers  2705  (i.e. distally or towards the front of the hand piece) causes pressure to build within the piston manifold  2798  and expels material from the pumping chamber  2705  and out of the system. The material can be expelled from the system into a disposal enclosure coupled to an exit port as described elsewhere herein. 
     Again with respect to  FIG. 13I , the vacuum manifold  2774  can additionally include an evacuation chamber  2709 . The evacuation chamber  2709  is sealed off from the vacuum chamber  2703  such that material drawn into the system can be purged from the system without being pushed back out through the cutting tube  1112 . The seal between the chambers  2703  and  2709  can be provided by one or more O-rings  2786 . The vacuum chamber  2703  is configured to be in fluid communication with the one or more pumping chambers  2705  through respective one-way valves  2707  positioned within openings  2706 . The evacuation chamber  2709  is in fluid communication with each of the one or more pumping chambers  2705  through other openings  1038  regulated by respective valves  2713 . The configuration of the valves  2713  can vary including a ball type check valve. Movement of the pistons  2799  in a first direction within their respective pumping chambers  2705  (e.g. towards a proximal end of the hand piece  1030 ) draws material from the vacuum chamber  2703  into the pumping chamber  2705  through the valves  2707 . Movement of the pistons  2799  in a second, opposite direction within their respective pumping chambers  2705  (e.g. towards the distal end of the hand piece  1030 ) pressure builds within the piston manifold  2798 . The pressure opens the valves  2713  in the piston manifold  2798 . The waste material may enter the vacuum manifold  2774  through the waste channels  1038  (e.g. three openings shown in  FIG. 14A ). The waste may combine in the vacuum manifold  2774  and exit the device through the evacuation chamber  2709 . The evacuation chamber  2709  is shown in  FIG. 14A  as an oval-shaped channel that runs through the vacuum and piston manifolds  2774 ,  2798  although it should be appreciated that other shapes are considered herein. During this purge of material, the one-way valves  2707  between the one or more pumping chambers  2705  and the vacuum chamber  2703  prevents the backflow of material into the vacuum chamber  2703 , the lumen  1110 , and out the cutting tube  1112 . However, the openings  1038  between the one or more pumping chambers  2705  and the evacuation chamber  2709  allows for the material to freely enter the evacuation chamber  2709  and ultimately out an exit or aspiration port  1154  of the evacuation chamber  2709  at least until flow is cut off by the valves  2713 . 
     Again with respect to  FIG. 13J , movement of the pistons  2799  in a proximal direction creates a vacuum within the pumping chamber  2705 . The ball  2717  of the valve  2713  is pushed proximally by the spring  2719  away from opening  1038  between the pumping chamber  2705  and the evacuation chamber  2709  thereby opening the valve  2713 . Upon movement of the pistons  2799  in a distal direction, fluid pressure builds within the pumping chamber  2705  increasing fluid pressure within the chamber and urging the material towards the opening  1038  of the valve  2713 . The ball  2717  of the valve  2713  is pushed distally against the spring  2719  such that the spring  2719  compresses and the ball  2717  is urged against the valve opening  1038  thereby closing the valve. The pumping chambers  2705  are substantially devoid of material upon closure of the valve  2713 . In some implementations, valves  2707  may be slightly compliant such as a silicone valve like a duckbill valve. The ball  2717  can be rigid and substantially non-compliant such as a hard plastic or metal material. The compliant valves may deform as a reverse positive pressure is imparted on them whereas the non-compliant valves do not deform. If the valve between the vacuum chamber  2703  and the pumping chamber  2705  is a compliant valve and the ball  2717  is substantially non-compliant, then as the piston is travelling distally and generating positive pressure to evacuate the material from the pumping chamber  2705 , the positive pressure can cause a deformation of the compliant valve and a small purge or regurgitation of an amount of fluid out the cutting tube  1112 . This regurgitation may occur on every back and forth cycle of the piston  2799 . In some embodiments, the regurgitation may be optimized further by the design of the pumping chamber  2705 . In the pumping chamber  2705 , the outlet opening connecting the pumping chamber  2705  to the evacuation chamber  2709  may be located, for example, on the side of the chamber and configured such that the piston  2799  may travel beyond the outlet opening. In this embodiment, after the piston  2799  has moved distally beyond the outlet opening there is no other route for fluid evacuation. Therefore, as the pistons  2799  continue to travel distally creating a moment of positive pressure within the pumping chamber  2705  after closure of the valves  2713  that causes a short regurgitation of material at the distal end of the cutting tube  1112 . 
     As best shown in  FIGS. 13F-13G  and also  FIG. 13K-13L , and  FIG. 14B , each of the pistons  2799  can include an elongate central piston rod  2721  surrounded by a spring  2701  extending between piston heads  2723   a,    2723   b.  A distal piston head  2723   a  and sliding O-ring seal  2794  are positioned within the pumping chamber  2705 . The piston rod  2721 , spring  2701 , and proximal piston head  2723   b  are positioned within a piston chamber  2704  within the piston manifold  2798  located proximal to the pumping chamber  2705 . The distal piston head  2723   a,  sliding seal  2794 , and piston rod  2721  are capable of sliding within the pumping chamber  2705 . The pumping chamber  2705  has an inner dimension that is smaller than the piston chamber  2704  and the outer dimension of the spring  2701 . Thus, as the piston  2799  move towards the distal end region of the pumping chamber  2705 , the spring  2701  gets compressed within the piston chamber  2704  between the proximal piston head  2723   b  and the lower end of the pumping chamber  2705 . The spring  2701  is biased to urge the piston  2799  proximally towards a proximal end of the pumping chamber  2705 . 
     The hand piece can include a rotating cam  2769  having a proximal end operatively coupled to a motor either directly or via a motor coupler. The rotating cam  2769  can convert rotary motion of the motor into linear motion of the pistons  2799 . The spring  2701  is biased to urge the pistons  2799  proximally towards the proximal end of the pumping chamber  2705 . The rotating cam  2769  positioned proximal to the pistons  2799  is configured to urge the pistons  2799  distally towards the distal end of their respective pumping chambers  2705 . As the cam  2769  rotates, it applies a distally-directed force sequentially against the proximal pistons heads  2723   b  of the pistons  2799 . The springs  2701  of the pistons  2799  are, in turn, sequentially compressed. Upon further rotation of the cam  2769 , the distally-directed force against the proximal piston heads  2723  is sequentially removed and the springs  2701  sequentially urge the pistons  2799  backwards creating a vacuum within the respective pumping chambers  2705  through the one-way valves  2707 . 
     As best shown in  FIGS. 13C-13E , the rotating cam  2769  can couple with a motor coupler  2795 . The motor coupler  2795  can have a bore  2789  in a proximal end configured to receive the gear head  2752  and one or more projections  2796  on a distal end. The projections  2796  are configured to abut and engage with corresponding wedged-shaped projections  2797  on the proximal end of the cam  2769 . The cam  2769  rotates as the gear head  2752  rotates. A distal end of cam  2769  has a cam surface  2725  configured to provide reciprocal linear motion of the pistons  2799 . The geometry of the cam surface  2725  can be designed to provide different motion profiles of the pistons  2799  in their respective bores and thereby create different vacuum profiles (i.e. smooth continuous, continuous with spikes in negative pressure, or discontinuous pulsed negative pressure). The cam surface  2725  can be elliptical, eccentric, egg, or snail-shaped. During a first fraction of rotation of the cam  2769 , the proximal piston heads  2723   b  slide along the ramped portion of the cam surface  2725  and the piston  2799  is moved distally along the longitudinal axis of the device. During a second fraction of rotation of the cam  2769 , the proximal piston heads  2723   b  slide past the cam surface  2725  that terminates at ledge  2726 . When the piston heads  2723   b  drop off ledge  2726  the distally-directed force against the pistons  2799  by the cam  2769  is released. The spring  2701  surrounding the piston rod  2721  urges the proximal piston head  2723   b  in a proximal direction towards the proximal end region of the piston chamber  2704 . A complete revolution of the cam  2769  therefore allows for axial movement of each piston  2799  in succession. The piston heads  2723   b  slide along the cam surface  2725  and extend in the distal direction at a first rate and the piston heads  2723   b  drop off the cam surface  2725  and retract in the proximal direction at a second rate that is much faster than the first rate. The timing of this piston movement can vary based on the geometry of the cam surface  2725  and the location of the ledge  2726  relative to the cam surface  2725 . For example, the timing of when one piston retracts to create a negative pressure within the chamber relative to when the next piston retracts to create a negative pressure can be a function of the cam surface  2725  geometry. The cam surface  2725  can incorporate a ledge  2726  such that each piston retracts quickly upon reaching the ledge  2726  as shown in  FIG. 13C . The piston extends at a first rate in a distal direction as it moves along the cam surface  2725  and then at a second, faster rate in the proximal direction as it drops off the ledge  2726 . In other implementations, the cam surface  2725  has a first ramp connected to the ledge  2726  by a second ramp. The first ramp of the cam surface  2725  allows for gradual extension of each piston and the second ramp allows for gradual retraction of each piston. Thus, each piston will gradually retract a distance before the piston drops off the ledge  2726  to quickly retract the rest of the rearward travel. Movement of the pistons involved in creating aspiration forces and movement of the cutting tube can be linked due to the rotating cam mechanism, as described in U.S. Patent Publication No. 2018/0318133, published Nov. 8, 2018, which is incorporated by reference herein. 
     The vacuum pulses can be designed to occur suddenly, for example, by a piston  2799  falling off the ledge  2726  of the cam surface  2725  and being pushed proximally towards the proximal end of the pumping chamber  2705  by the piston spring  2701 . The timing of this retraction due to the ledge  2726  can be leveraged to achieve a more pulsatile vacuum profile. Pulsatile vacuum can be beneficial for breaking up the lens and removing the lens material from the eye in that the peak vacuum level can be higher for these short bursts of time than can be achieved if steady vacuum is applied because the flow rate is kept below a nominal amount (e.g. 50 cc/minute). High peaks of vacuum are created, but a low overall flow rate can be maintained. 
     The timing of when a first piston is retracting and the next piston retracts can be a function of the geometry of the cam surface  2725  and the relative movements of the pistons within the piston chamber. The vacuum pulses can be designed to occur more smoothly such that the vacuum provided is substantially continuous, rather than discontinuous with momentary pauses between vacuum pulses. In some implementations, a first piston may retract and the second piston not start retracting until after a dwell period of the first piston retraction (see  FIG. 15A ) thereby creating a pulsatile vacuum profile. As described above, the device can include a cam  2769  having a cam surface  2725  configured to provide reciprocal linear motion of the pistons  2799 .  FIG. 15A  illustrates in schematic movement of the pistons  2799   a,    2799   b,    2799   c  along the cam surface  2725  of the cam  2769 . The cam surface  2725  terminates at a sharp drop-off or ledge  2726 . During rotation of the cam  2769 , the pistons  2799   a,    2799   b,    2799   c  slide along the cam surface  2725  and thereby extend in a distal direction. Upon reaching the ledge  2726 , a first piston  2799   a  drops off the ledge  2726  retracting quickly in a proximal direction creating a spike in negative pressure. The geometry of the cam surface  2725  creates a dwell time of no negative pressure before the next piston  2799   b  reaches the ledge  2726  and retracts creating a second spike in negative pressure. The result is a series of discontinuous pulses of negative pressure. 
     In other implementations, the second piston may start retracting during a phase of the first piston retraction such that the vacuum profile is smoother and more continuous.  FIGS. 15B-15D  illustrate in schematic an implementation of the cam  2769  where the geometry of the cam surface  2725  is designed to having a more gradual slope for piston retraction prior to terminating at the ledge  2726 . The geometry of the cam surface  2725  can be designed such that one of the plurality of pistons  2799  is retracting (i.e. creating a negative pressure within the pumping chamber  2705 ) at a constant rate.  FIG. 15B  shows the first piston  2799   a  near the end of its proximal travel within the piston chamber just prior to the ledge  2726 . The second piston  2799   b  is poised to begun its retraction along the gradual slope prior to the first piston  2799   a  dropping off the ledge  2726 .  FIG. 15C  and  FIG. 15D  illustrate further rotation of the cam  2769  and movement of the pistons along the cam surface  2725 . Before the second piston  2799   b  drops off ledge  2726 , the third piston  2799   c  will begin its retraction along the gradual slope of the cam surface  2725 . This timing of piston retractions creates a flow rate of fluid out of the eye that is substantially continuous compared to the geometry of the cam surface  2725  shown in  FIG. 15A  that is discontinuous with moments of no vacuum being drawn. However, the presence of the ledge  2726  can create small spikes in negative pressure on top of the continuous negative pressure being applied by the retracting pistons. The first piston  2799   a  retract a first distance along the cam surface  2725  at a first rate thereby creating a first negative pressure. The second piston  2799   b  can start retracting at the first rate along the cam surface  2725  prior to the first piston  2799   a  dropping off the ledge  2726  maintaining that negative pressure. The first piston  2799   a  then drops off the ledge  2726  retracting the remaining distance at a second, faster rate thereby creating a spike in negative pressure. 
     As best shown in  FIGS. 13K-13L , a piston stop  2727  can be coupled to a proximal end region of the piston manifold  2798 . The piston stop  2727  can be a generally cylindrical element surrounding the rotating cam  2769 . A distal end region of the piston stop  2727  can define one or more projections  2729  configured to project into a proximal end region of each of the piston chambers  2704  in the piston manifold  2798 . The projections  2729  abut against the proximal piston heads  2723   b  of respective pistons  2799  when positioned at a proximal-most end region of their respective piston chambers  2704 . For example, if the hand piece  1030  includes three pistons  2799  positioned in three piston chambers  2704 , the piston stop  2727  includes three projections  2729  configured to abut against the proximal piston head  2723   b  of each of the three pistons  2799 . The piston stop  2727  provides a hard stop to the linear travel of the pistons  2799  in a proximal direction upon expansion of the springs  2701  and thus, the overall volume of the pumping chamber  2705  that can be achieved. The relative position of the projections  2729  within the piston chambers  2704  can be adjustable. In some implementations, an adjustment ring  2730  can be positioned around an outer surface of the piston stop  2727  and available to a user through one or more windows  2731  in the housing of the hand-held portion  1030  (see  FIGS. 13A-13B ). The adjustment ring  2730  can have a threaded inner surface configured to engage with a corresponding pin  2732  on an outer surface of the piston stop  2727 . The pin  2732  is configured to slide within the threads of the adjustment ring  2730  such that the piston stop  2727  travels axially along the longitudinal axis of the device. As the piston stop  2727  is adjusted to be positioned further distal relative to the piston manifold  2798 , the projections  2729  extend further into the piston chambers  2704  and limit the linear travel of the pistons  2799  in the proximal direction upon expansion of the springs  2701 . This, in turn, limits the size of the pumping chamber  2705 . As the piston stop  2727  is adjusted to be positioned more proximally relative to the piston manifold  2798 , the projections  2729  are withdrawn from the piston chambers  2704  and do not limit (or limit to a lesser degree) the linear travel of the pistons  2799  in a proximal direction upon expansion of the springs  2701 . This, in turn, maximizes the size of the pumping chamber  2705 . The piston stop  2727  also can be adjusted to determine the type of vacuum applied by the pistons within their respective chambers  2704  (e.g. smooth continuous vacuum or smooth continuous with spikes in pulsatile vacuum), as will be described in more detail below. 
     In some implementations, the vacuum source can create a sudden rise in vacuum forming a vacuum profile that causes the cornea and the eye to effectively “bounce” up and down during application of pulsed vacuum. For example, when the pistons  2799  are sprung backwards they can create the sudden rise in vacuum forming a vacuum profile that resembles a “saw tooth” (i.e. suction—pause—suction). Limiting the backwards travel of the pistons  2799  inside their respective pumping chambers  2705  can reduce the amount of suction impact or shock that is created each time the pistons are sprung backwards. The piston limit thereby limits the maximum suction created with each piston travel reducing the impact this abrupt suction can have on the eye. The vacuum created with each backwards travel of the piston  2799  can be greater than 500 mmHg up to about 700 mmHg. 
     In some implementations, the device can be switched between two vacuum modes. The first mode can be a substantially continuous vacuum mode without the spike in negative pressure due to the pistons  2799  dropping off the ledge  2726 . The second mode can be a substantially continuous vacuum mode with the spikes in negative pressure. When in the first mode, the piston retraction can be limited to a fraction of the maximum piston travel within the chamber. For example, the piston stop  2727  can be selectively used to limit the piston travel within its chamber to a distance less than the maximum distance. As described elsewhere herein, the device can include a piston stop  2727  coupled to a proximal end region of the piston manifold  2798 . The piston stop  2727  can be a generally cylindrical element surrounding the cam  2769  such that the cam  2769  extends through the cylindrical piston stop  2727  to contact the proximal ends of the pistons  2799 . The piston stop  2727  can include a projection  2729  configured to project into a proximal end region of its respective piston chamber  2704  to make contact with the proximal ends of the pistons  2799 . Thus, both the cam  2769  and the projections  2729  of the piston stop  2727  are configured to contact the proximal ends of the pistons  2799 , the cam  2769  on an inner region and the projections  2729  on an outer region. The projections  2729  of the piston stop  2727  can provide a hard stop to the linear travel of the pistons  2799  in a proximal direction. For example, maximum piston travel within its piston chamber can be a distance of 5 mm. The projection  2729  of the piston stop  2727  can be advanced into the piston chamber by 2 mm to thereby limit proximal retraction of the piston  2799  to a distance of 3 mm rather than the maximum 5 mm. As the cam  2769  turns and the pistons  2799  extend and retract along the cam surface  2725 , the projections  2729  of the piston stop  2727  can effectively prevent the pistons  2799  from dropping off the ledge  2726  creating a smooth, continuous negative pressure without the spike in negative pressure. When the projections  2729  of the piston stop  2727  are withdrawn from the piston chamber, the pistons  2799  can once again travel the maximum distance and can drop off the ledge  2726  creating a spike in negative pressure. 
     In some implementations, the hand piece is limited from achieving maximum vacuum by incorporating a feature that automatically bypasses the cutting tube  1112  depending on whether a threshold vacuum is reached. For example, a bleed valve or other bypass mechanism can be incorporated to prevent a threshold amount of vacuum from being applied at a distal opening of the cutting tube  1112  and into the eye. A bypass to turn on or off the suction can limit the maximum amount of vacuum that can be generated within the eye even if the opening into the cutting tube  1112  is clogged. This bypass can prevent the vacuum from building in the event of a blockage to create less surge upon removal of that blockage. The bypass mechanism can be adjustable or selective such that a user can choose whether or not they want the potential for maximum vacuum or something less than maximum vacuum applied. 
     It can be desirable to limit the maximum vacuum pressure that can be achieved with each proximal travel of each piston. Limiting the maximum vacuum can provide additional safety with regard to the capsular bag and the eye as a whole. For example, the impact the system has on the integrity of the capsular bag and the anterior chamber can be directly related to the degree of suction applied at the distal tip. Limiting the overall vacuum pressure (e.g. by at least about 2%, 3%, 4%, 5%, 10%, 15%, 20%, 25%, up to about 50% of maximum vacuum otherwise achievable) can prevent issues such as tearing of the capsular bag or “trampolining” of the anterior chamber. 
       FIG. 13L  illustrates an implementation of a vacuum bypass feature  2708  configured to limit the maximum vacuum pressure in each pumping chamber  2705 . The bypass feature  2708  can have any of a variety of configurations. In an implementation, the bypass feature  2708  can be a small longitudinal indentation, divot or groove in the cylindrical wall of each pumping chamber  2705  (see  FIG. 13L ). As described above, the piston  2799  can include an elongate central piston rod  2721  surrounded by a spring  2701  extending between piston heads  2723   a,    2723   b.  A sliding O-ring seal  2794  can be positioned around the distal piston head  2723   a  that maintains a vacuum within the pumping chamber  2705 . The piston  2799  shown in  FIG. 13L  is positioned in the cylindrical pumping chamber  2705  near the end of its proximal travel path such that proximal piston head  2723   b  abuts against the piston stop  2727 . When the piston head  2723   b  abuts against the piston stop  2727 , the seal  2794  can be aligned with the bypass feature  2708  near the proximal end of piston travel. The bypass feature  2708  can have a length along the longitudinal axis of the cylindrical chamber such that at least a portion of the feature  2708  is located distal to the seal  2794  and at least a portion of the feature  2708  is located proximal to the seal  2794 . The presence of the bypass feature  2708  on both distal and proximal sides of the seal  2794  (i.e. the higher and lower pressure sides of the chamber  2705 ) means an amount of ambient air can bleed momentarily from the higher pressure side into the lower pressure side of the chamber  2705  (i.e. distal to the seal  2794 ) at the proximal end of piston travel. The leak or bleed of ambient air can limit the extent of the vacuum pressure that would otherwise be achieved upon retraction of the piston  2799  in the proximal direction. The venting of the aspiration cavity can be to the atmospheric air or to the irrigation fluid pathway, to the waste fluid pathway, or any other cavity allowing for fluid or air to enter the aspiration cavity and the vacuum level achieved within the aspiration cavity is decreased. The venting can release the vacuum level within the aspiration cavity as well as reduce the maximum achievable vacuum level during operation. The bypass feature  2708  can be designed to achieve a desired maximum pressure value depending on a length, width, and/or depth of the groove as well as the number of grooves incorporated. The geometry of the bypass feature  2708  can also control the speed at which this vacuum pressure is created with each sequential piston retraction. 
     The bypass feature  2708  can vent the vacuum to atmosphere passively, as described above, or actively. For example, the bypass feature  2708  can be user-actuated as will be described in more detail below. The bypass feature  2708  can have an adjustable and/or user-selectable geometry to provide additional user control over the desired maximum pressure value that can be achieved. In an implementation, the bypass feature  2708  can be a small hole extending through the wall of the pumping chamber  2705 . The diameter, length, and/or location of the hole can be variable and selectable by a user so as to achieve the desirable control of the maximum suction pressure achieved. 
     In some implementations, the device can incorporate a venting mechanism that can be useful in certain situations, for example, when the capsular bag is inadvertently captured in or lens material occludes the distal end of the cutting tube  1112 . Similar to the bypass feature  2708  described above, the venting mechanism can include a small hole through the wall of the pumping chamber  2705  that can be selectively exposed or covered. The hole can be covered and/or exposed by a movable element actuatable by a button or other input on the user interface of the device allowing for a user to vent any accumulated vacuum in the pumping chambers  2705  to the atmosphere. Venting the vacuum allows, for example, material such as the capsular bag to be released from the tip of the cutting tube  1112 . Selective activation of the venting mechanism can include pressing a button that moves a movable element normally covering the hole exposing it to atmosphere. Alternatively, selective activation of the venting mechanism can include pressing a button that moves a movable element causing it to cover a normally open hole thereby preventing venting to the atmosphere. In an implementation, the button can be coupled to the multi-stage trigger  1180  of the device described elsewhere herein. As an example, when the trigger  1180  is at its neutral state and the device is at rest, the vacuum can be vented and the suction within the system dissipates. When the trigger  1180  is depressed to activate suction, the venting can be shut off. In this example, a user having the capsular bag sucked into the tip of the device (or a piece of lens occluding the lumen) can simply let go of the trigger  1180  to vent and release the tissue. 
     The venting purge mechanism can additionally create a small volume of retrograde flow of fluid out the distal tip of the device in addition to venting the tip of the cutting tube  1112 . The small fluid flow at the tip can aid in fully releasing the bag or any other materials causing a clog. In this implementation, the button to actuate the purge mechanism can be a depressible button that when depressed can force a small volume of fluid out the irrigation outlet. As such, releasing the trigger  1180  can cause venting of accumulated vacuum in the pumping chambers  2705  and pressing the purge button can urge fluid out the distal tip to further push the capsular bag away. 
       FIGS. 22A-22B  show perspective and top views of an implementation of an aspiration pump  1014  for incorporation within a disposable, working portion  1031  configured to provide smooth, continuous aspiration through the cutting tube  1112 . The working portion  1031  can be used for procedures in which smooth flow aspiration through an oscillating cutting tube  1112  is desired.  FIGS. 22C-22D  show a camshaft  405  of the aspiration pump  1014  of  FIG. 22A . 
     The aspiration pump  1014  can be a linear peristaltic pump having a symmetrical double chamber pumping manifold  420 , a central camshaft  405  extending longitudinally through the manifold  420  along longitudinal axis A, a plurality of cam followers  410 , and a pair of peripheral tubes  415 . The pumping manifold  420  can be disposed within the working portion  1031  between a proximal manifold and a distal manifold. The camshaft  405  can couple on a proximal end region of the camshaft  405  to a drive shaft such as via the rotating camshaft coupler  2795  in the disposable portion  1031 . As the pump motor  1115  spins the drive shaft drives rotation of the camshaft  405  thereby powering the aspiration pump  1014 . The camshaft  405  can also couple on a distal end region of the camshaft  405  to the cutting tube  1112  such as via rotating cam follower. 
     The two tubes  415  can be positioned on either side of a centerline C of the pumping manifold  420  (see  FIG. 23A ). The two tubes  415  can extend through the pumping manifold  420  in a substantially straight manner such that each forms a longitudinal axis T (see  FIG. 22B ) through the pumping manifold  420  that are positioned parallel with the longitudinal axis A of the camshaft  405  extending through the pumping manifold  420 . A first tube  415   a  of the two tubes  415  can be positioned on one side of the camshaft  405  and a second tube  415   b  of the two tubes  415  can be positioned on a second, opposite side of the camshaft  405 . A proximal flow path splits into two flow paths connected on a proximal end with the pair of tubes  415  within the proximal manifold (not shown). The two tubes  415  can combine distal to the pumping manifold  420  into the distal manifold (not shown). The distal flow path can be in fluid communication with the lumen of the distal cutting tube  1112 . 
       FIGS. 22C-22D  show the camshaft  405  of the aspiration pump  1014  in  FIGS. 22A-22B . The camshaft  405  can incorporate a plurality of lobed cams  425  that work in time to drive the plurality of cam followers  410  side-to-side or towards and away from the pair of tubes  415  such that the tube experiences sequential, progressive compression, thereby pushing its fluid volume along its flow path. The pair of tubes  415  can be aligned with the longitudinal axis A (rotational axis) of the camshaft  405 . The side-to-side motion of the cam followers  410  can be in a plane perpendicular to the longitudinal axis A of the camshaft  405  and the longitudinal axis T (see  FIG. 22B ) of each of the tubes  415 . As an example, the tubing  415  can extend spatially parallel to or along the rotational axis of camshaft  405  through the pumping manifold. The tubing  415  can be compressed by the cam followers  410  along an axis that is substantially  90  degrees relative to the rotational axis of the camshaft  405 . For example, the cam followers  410  can be driven side-to-side along the horizontal position or along the vertical position relative to the camshaft  405 . Although the relative angle of the cam followers  410  and the tubing  415  can be more than or less than a 90 degree angle, the cam followers  405  do not translate axially along the side wall of the tubing  415  as occurs in conventional peristaltic pumps that use rollers, which compress and roll along the length of the tubing moving its fluid volume along its flow path. 
     Each of the tubes  415  can be sequentially compressed by the cam followers  410  in a wave-like fashion. The maximum extent of the compression closes off the tube, capturing a discrete volume of fluid that is urged along the tube&#39;s length resulting in aspiration fluid flow moving through the tubes  415 . Conventional peristaltic pumps can involve the translation of a roller or other component along the longitudinal axis of the tubing thereby urging fluid through the tube. This sort of linear translation along a tube can lead to the creation of holes or tears in the side wall of the tubing as it wears over time. The aspiration pump  1014  described herein need not involve translation of a compression element along the longitudinal axis of the tubing  415  (i.e., axis T shown in  FIG. 22B ). Rather, the compression of each tube  415  is in a plane perpendicular to the longitudinal axis T of the tube  415 . This arrangement avoids pulling or stretching of the tube and generates little to no friction on its side wall. In other words, the plurality of cam followers apply no force in a direction of the longitudinal axis T of the two tubes  415   a,    415   b.  The chamber volume is maintained consistent and the pump  1014  has a lower risk of tube failure or loss of pump performance that can result from compression that translates along the tube length. 
     As best shown in  FIGS. 23A-23D , each of the plurality of cam followers  410  can include an inner slot  430  configured to receive their respective cam lobes  425 . The cam lobes  425  can travel up and down relative to and within the inner slot  430  as the camshaft  405  rotates about its longitudinal axis A. The cam followers  410  in turn are urged side-to-side by the cam lobes  425  relative to a centerline C of the pumping manifold  420 .  FIG. 23A  shows one cam follower  410  aligned with the centerline C. The cam lobe  425  is shown substantially aligned with the centerline C and positioned in an upper end region of the slot  430  of the cam follower  410 . As the camshaft  405  turns a first degree around its axis A along arrow A, the cam follower  410  is urged away from the centerline C along axis C′ in the direction of arrow R and the cam lobe  425  travels downward through the slot  430  of the cam follower  410  ( FIG. 23B ). As the camshaft  405  turns a second further degree around its axis A along arrow A, the cam follower  410  is urged back towards the centerline C along axis C′ in the direction of arrow L and cam lobe  425  travels further downward through the slot  430  of the cam follower  410  ( FIG. 23C ). As the camshaft  405  turns a third further degree around its axis A along arrow A, the cam follower  410  is urged away from the centerline C along axis C′ in the direction of L′ as cam lobe  425  travels back up through slot  430  of the cam follower  410  towards the upper end region of the slot  430  ( FIG. 23D ). 
     The side-to-side motion of the cam followers  410  can create incremental, sequential compressions of each tube  415  such that the aspiration created in the distal flow path that is in communication with the cutting tube is smooth or substantially non-pulsatile aspiration. The geometry of the camshaft  405  (e.g. pitch, length) as well as the number of cam lobes  425  and cam followers  410  can vary to achieve a particular timing along the longitudinal axis T of the tubes  415 . The number of cam followers  410  in the pump  1014  can vary, for example, at least 2, 3, 4, 5, 6, 7, 8, 9, 10, up to about 20 cam followers  410 . The number of cam lobes  425  and cam followers  410  can more closely approximate perfect smooth flow as the number of lobes and followers increases. For example, the implementation of the aspiration pump  1014  shown in  FIG. 22B  includes 10 cam lobes  425  and 10 cam followers  410 . The aspiration pump  1014  can thereby create a smooth, sine wave sort of curve as each cam follower  410  is urged side-to-side to compress the opposing tubes  415 . 
       FIG. 24A  shows how initially, the pump  1014  can undergo a warm-up period upon activation as the camshaft  405  starts rotating. The cam followers  410  are urged side-to-side within the pumping manifold  420  to sequentially compress the pair of tubes  415  and the negative pressure within the flow line of tube  415   a  and tube  415   b  builds. The flow rate through tube  415   a  can be offset from the flow rate through tube  415   b  such that the target flow rate achieved is substantially constant with minimal pulsatile flow through the distal flow path. 
     The pump  1014  can include fewer cam followers  410  than is shown in the embodiment of  FIGS. 22A-22B . In such an implementation, the timing of the camshaft  405  can create a curve that is more like an off-on type of square curve (see  FIG. 24B ). The on-off square curve can provide a more consistent chamber length (i.e., the sealed volume within the tubing between the locations where it is closed off by the cam followers) compared to, for example, a helical driven peristaltic pump where the tube is squeezed shut using a more gradual motion. The cam lobes of the implementation of the pump shown in  FIGS. 22A-22B  follow a circular path relative to the device at large and a linear path relative to the cam follower. The cam followers compress the tubes on both sides. As it moves one direction, it compresses one tube and as it moves in the opposite direction, it compressed the opposite tube. However, the cam lobes need not be driven by a helical path with such gradual compression. Rather, the layout of the cam lobes can be positioned radially or lengthwise along axis T relative to one another such that the spacing between each cam lobe can create compression on the tube  415  to achieve the desired timing. 
     Again with respect to  FIGS. 23A-23D , the shape of the cam followers  410  not only provides for the travel of the cam followers  410  in a side-to-side motion as the camshaft  405  spins. The shape of the cam followers  410  provides efficient compression of the pair of tubes  415 . Each cam follower  410  can incorporate a first compression zone  435  on an outer surface of the cam follower  410  on a first side of centerline C and a second compression zone  437  on an outer surface of the cam follower  410  on a second, opposite side of centerline C. Each of the first and second compression zones  435 ,  437  can be arranged substantially aligned with the centerline C′. As the cam follower  410  moves along arrow R, the first compression zone  435  compresses tube  415   b  ( FIG. 23B ). As the cam follower  410  moves along arrow L′, the second compression zone  437  compresses tube  415   a  ( FIG. 23D ). Each cam follower  410  can also include two displacement zones  440 ,  442  for each compression zone  435 ,  437 . As the tubes  415  are compressed by the compression zones  435 ,  437 , the corresponding two displacement zones  440 ,  442  can receive the material of the tubes  415  that are being compressed by the compression zones  435 ,  437  of the cam follower  410 . 
     The pair of tubes  415  can extend in a straight line along longitudinal axis T and parallel with the longitudinal axis A of the camshaft  405 . The pair of tubes  415  extend generally parallel to the rotational axis of the camshaft  405  through the pumping manifold. As such, the compression on the tubes  415  occurs in a side-to-side motion along a horizontal plane relative to the rotational plane of the camshaft, which can be in a plane perpendicular to the longitudinal axis A (and also axis T). This compression does not therefore translate axially along the sidewall of the tubing thereby providing the advantage of less wear on the tubing material. Additionally, the configuration of the pair of straight tubes  415  can provide additional side-to-side force on the cam follower  410 . For example, as one tube  415   a  is being compressed by the cam follower  410 , the opposing tube  415   b  that just got compressed by a cam follower  410  can spring back to its original shape. The spring force can help to compress the opposing tube  415 . Each tube  415  can aid in causing compression of its partner by urging the cam follower  410  in the opposite direction of the compression. 
     As mentioned above, the proximal end region of the camshaft  405  can couple to the drive shaft such as via the coupler in the disposable portion  1031  and the distal end of the camshaft  405  can couple to the cutting tube  1112 . Thus, the drive mechanism that drives the aspiration pump  1014  can also drive oscillation of the cutting tube  1112 . Despite being physically coupled, the pump and the oscillation can be functionally decoupled. The pump  1014  can be configured to turn on at maximum flow levels and full aspiration potential by the drive mechanism. The aspiration delivered through the cutting tube  1112  can be controlled by a bleed valve. The bleed valve can be open to the atmosphere so that no aspiration is drawn through the cutting tube  1112  upon initiation of the pump  1014  despite the drive motor turning at full speed. The bleed valve can start to close upon actuation of a trigger  1180  such that aspiration through the cutting tube  1112  will slowly increase. The greater the trigger  1180  is actuated the greater the aspiration until the bleed valve achieves the fully closed position and full aspiration is directed through the lumen. The valve can be positioned distal to the aspiration pump  1014  and proximal to the cutter assembly. 
     The aspiration pump  1014  generally requires a slower turning speed for driving aspiration compared to the turning speed needed for oscillation of the cutting tube  1112 . For example, in vitrectomy it can be desirable to achieve up to 5000 cuts per minute and to achieve a vacuum capability of 650 mmHg or 25 cc/minute volume. The instrument can incorporate a small transmission or gear train to effect a desired oscillation speed. The gear train can be positioned between the camshaft  405  and the cutting tube  1112  and can be configured to engage and disengage the cutting tube  1112  acting as a clutch mechanism in the oscillation of the tube  1112 . A gear train can effect a fixed ratio between the cutting tube oscillation speed and the aspiration pump rotational speed. In some implementations, the aspiration pump  1014  can be activated and running at maximum speed. The valve can control delivery of aspiration through the lumen of the cutting tube  1112 . The input  1180  can be actuated to engage or disengage the cutting of the cutting tube  1112 . 
     The lobed cams  425  of the camshaft  405  can drive and cause motion of a plurality of cam followers  410  configured to sequentially compress tubing  415  and translate that generated aspiration pressure to the cutting tube  1112  positioned within an eye. The plurality of cam followers  410  can be driven by the cams of the camshaft  405  to move in a plane that is substantially perpendicular to the longitudinal axis to sequentially compress the tubing  415 . As an example, the tubing  415  can extend spatially parallel to or along the z-axis, or the center of rotation of the camshaft  405 . The tubing  415  can be compressed by the cam followers  410  along an axis that is aligned substantially  90  degrees relative to the z-axis. For example, the cam followers  410  can be driven side-to-side along the horizontal position or x-axis relative to the z-axis of the camshaft  405 . The cam followers  410  can also be driven along the vertical position or along the y-axis relative to the z-axis of the camshaft  405 . The relative angle of the cam followers  410  and the tubing  415  can be more than or less than a 90 degree angle as well. However, the cam followers  405  do not translate axially along the side wall of the tubing  415  (i.e. along the z-axis). The camshaft  405  can also drive oscillation of the cutting tube  1112 , which can be a lens fragmentation working tip or a vitrectomy probe. 
     The configuration of the peristaltic pump within the disposable portion  1031  can vary and need not be a linear peristaltic pump. For example, the peristaltic pump can be a helical design or a horseshoe peristaltic pump. 
     Asymmetric Cutting Motion and Aspiration Profiles 
     As mentioned above, the hand pieces described herein can include a cutting tube  1112  or other elongate shaft configured to be inserted into the eye in a minimally-invasive manner to cut, aspirate, and/or inject material in the eye. The elongate shaft can be configured as a vitrectomy-style cutting element having a hollow, elongate member extending through an outer member with a side opening configured to capture and cut pieces of tissue. The elongate shaft can be configured as a phacoemulsification (“phaco”) style tip, which also includes a movable cutting tube with or without an outer member. Oscillating movements of the elongate shaft can occur using any of a variety of mechanisms, such as a piezoelectric drive system described elsewhere herein. Certain oscillating movements can be created in a manner that avoids the deleterious effects that conventional phacoemulsification has on the delicate eye tissues such as corneal endothelial cells. 
     Conventional phacoemulsification can incorporate two main methods of action: 1) mechanical jack hammering, and 2) cavitation. In the case of jackhammering, the oscillating movements of the tip mechanically impacts the tissue at a high speed to break up the tissue into ever smaller fragments. Cavitation involves the creation of gas bubbles as a consequence of high velocity oscillation of the tip. Retraction speeds of the tip in conventional phacoemulsification are sufficient to create zones of pressure low enough to cause the formation of gas bubbles as dissolved gases are drawn out of the fluid. As the tip transitions from retraction to forward motion, these bubbles then collapse and implode, which results in very high temperatures (e.g. 3000° C.) and pressures (e.g. 10,000 atm). It is generally thought that the combination of high temperatures and high pressures helps to emulsify the tissue fragments. While the role cavitation plays in breaking up eye tissue is debatable, the role cavitation plays as the primary driver behind the deleterious effects of conventional phacoemulsification on the surrounding eye tissue during cataract surgery is not. High temperatures, shock waves, and the creation of free-radicals in the eye during conventional phacoemulsification are of concern to the health of the corneal endothelial cells. 
     The hand pieces described herein can include a drive mechanism that oscillates the cutting tube longitudinally in a manner that reduces, attenuates, or prevents problems of cavitation during conventional phacoemulsification. When in use, the drive mechanism retracts the cutting tube in a proximal direction with a retraction speed profile and advances the cutting tube in a distal direction with an extension speed profile. The retraction speed profile can be different from the extension speed profile. Additionally, the movement profile of the cutting tube can be coordinated with a vacuum profile. For example, while a pulse of vacuum is being applied through the cutting tube (i.e. through the distal opening), the cutting tube can be simultaneously fired in the distal direction. The pulsed vacuum can be internally generated within the hand held portion  1030  and/or externally generated and valved within the handle, as described elsewhere herein. Where the cutting tube is described as moving in forward and distal directions relative to the treatment site vibrations of the cutting tube are considered as well. The cutting tube can be vibrated in a similar fashion to conventional phacoemulsification machines. Thus, the cutting tube can be vibrated while a pulse of vacuum is applied and at some phase in the vacuum pulse or thereafter, the vibration and the vacuum can be turned off such that the system comes to rest before initiating a vibration-vacuum sequence again. The coordination between the movement and/or vibration of the cutting tube and the vacuum applied through the cutting tube is described in more detail below. 
     The maximum tip retraction speed can remain below the critical ‘cavitation threshold speed’ that would otherwise result in cavitation in the eye. The average retraction speed can be slow, i.e. below the cavitation threshold speed, but the average extension speed can be fast, i.e. close to or higher than the average retraction speed of a typical phacoemulsification tip. Thus, the benefits of mechanical jackhammering can be achieved while the deleterious effects of cavitation are entirely avoided. 
       FIGS. 10A and 10C  illustrate typical sinusoidal motion profile of a phacoemulsification tip in which the average speed of the tip is substantially the same during proximal retraction as during distal extension (see  FIG. 10A ). The maximum tip speed of the retraction speed profile R is substantially the same as the maximum tip speed of the extension speed profile E and thus, the motion profiles substantially overlap (see V maxR,E  of  FIG. 10C ).  FIG. 10C  illustrates a motion profile in which the extension and retraction speed profiles are substantially the same. For example, a 40,000 Hz phaco machine having a 0.1 mm amplitude may have a V max  of approximately 12.6 meters/second where the time T 1  is approximately 0.0125 ms.  FIG. 10B  shows the oscillating cutting tube  1112  having a generally non-sinusoidal motion profile in which the average tip speed of the retraction speed profile and the average tip speed of the extension speed profile can be substantially different providing an overall asymmetric movement profile for the oscillating cutting tube. The oscillating cutting tip  1112  has maximum tip speed (V maxR ) of the retraction speed profile R that is substantially lower than the maximum tip speed (V maxE ) of the extension speed profile E and thus, the motion profiles do not substantially overlap (see  FIG. 10D ).  FIG. 10D  illustrates a motion profile provided where V maxR  may be substantially lower such that full retraction is complete at time T 2 . Thus, the device may have a lower V avg . 
       FIGS. 10E-10F  illustrate additional asymmetric motion profiles considered herein. The extension speed E can increase linearly to V maxE  as the piezoelectric drive compels the cutting tube  1112  forward until it reaches its stroke limit and drops to zero before being retracted. As the cutting tube  1112  is retracted, the retraction speed R increases to V maxR  where the speed profile R can form a plateau during which time the retraction speed is roughly constant. Retraction phase is complete at time T 2 , which is longer than the time T 1  it took to complete the extension phase. A dwell or pause period can exist between the extension and retraction phases. The V maxE , can be roughly the same as conventional phaco machines (e.g. between about 8 to 12 meters/second). The V maxR  can be much lower than conventional phaco machines (e.g. less than about 0.02 meters/second). It should be appreciated that speeds of extension and retraction can vary and that any of a number of non-sinusoidal tip motion profiles are considered herein. In some implementations the V maxE  can be between about 2 meters/second and 50 meters/second and the V maxR  can be between about 0.001 meters/second and 2 meters/second. In some implementations, the tip speed can be at least 3 meters/second with frequencies less than ultrasonic as described elsewhere herein. 
     The speed profile and movement profile of the movable cutting tube can be generally sinusoidal such that the movement of the distal tip of the cutting tube oscillates in a sinusoidal pattern, corresponding to the frequency of a supplied voltage to the piezoelectric crystal and the resonance of the system it excites. The speed of the distal tip therefore also oscillates in a sinusoidal manner as the derivative of the movement profile.  FIG. 10G  shows an implementation of non-sinusoidal movement of the distal tip of a cutting tube  1112  (bottom panel) relative to its extension and retraction speed profiles (top panel). Both the speed profiles and the corresponding movement profiles are shown as being non-sinusoidal. The distal tip can have a dwell time between the extension and retraction cycles. Between to and t 1 , the distal tip can extend forward with a speed profile that may be a sine wave or any other profile. At ti, the distal tip can pause for a dwell period between t 1  and t 2 . The dwell period can be about 0.050 milliseconds, or between about 0.001 and 0.025 milliseconds. At t 2 , the distal tip can retract with a speed profile that may also follow a sine curve. The movement of the distal tip resembles a sine wave having a dwell at its most extended position. 
     The non-sinusoidal patterns, for example as shown in  FIG. 10G , can reduce the likelihood of cavitation because the dwell time allows for the fluid in the eye that is displaced by movement of the cutting tube  1112  during extension to return to a zero momentum state before retraction of the cutting tube  1112  begins. Sinusoidal patterns of cutting tube motion pushes the fluid away from the distal tip and then retracts immediately while the fluid may still be traveling away from the distal tip thereby increasing the likelihood of cavitation due to the relative velocity of the fluid to the distal tip. The relative velocity of the fluid to the distal tip is higher if the fluid of the eye is being carried away from the tip by momentum while the distal tip itself begins retracting. The dwell period can allow the fluid being displaced to return towards a zero momentum or zero velocity state before the distal tip begins to retract. In this implementation, the extension speed profile and the retraction speed profile may be similar or identical, but the overall speed profile and movement of the distal tip is non-sinusoidal. Other implementations are contemplated herein. For example, the cutting tube  1112  can slow down more gradually as it approaches its fully extended position than a typically sine wave pattern would. As the cutting tube  1112  retracts, the profile would follow a more symmetric path. Any number of other non-sinusoidal patterns are considered. 
     It should be appreciated that the term “non-sinusoidal” as used herein can be defined as a movement or speed profile that does not follow a simple sine wave pattern of oscillating movement. A simple sine wave may be defined by a single frequency, a single phase shift, and a single amplitude. Certain complex profiles may be generated by adding or subtracting sine waves. However, these complex profiles may also be considered non-sinusoidal because their addition or subtraction does not follow a simple, single sine wave pattern. Where the non-sinusoidal cutting tube motion is referred to herein as retracting and extending, side-to-side, torsional motion is considered as well. 
     The drive mechanism is capable of retracting the cutting tube  1112  in a proximal direction with a retraction speed profile and advancing the cutting tube  1112  in a distal direction with an extension speed profile such that the retraction speed profile is different from the extension speed profile. The average retraction speed of the cutting tube from the retraction speed profile can be lower than the average extension speed of the cutting tube from the extension speed profile. Thus, the drive mechanism operatively coupled to the cutting tube  1112  is configured to asymmetrically oscillate the cutting tube  1112 . The extension speed profile E can include a V maxE  and the retraction speed profile R can include a V maxR  where the V maxR  is less than the V maxE . The V maxR  of the cutting tube  1112  is generally kept below a threshold speed at which cavitation bubbles would be generated in the eye. Without limiting this disclosure to any particular threshold speed, one of skill in the art would understand the theoretical speed of retraction at which cavitation occurs is generally about 5 meters/second. As such, the V maxR  of the cutting tube  1112  may be maintained below about 5 meters/second. 
     It should be appreciated that preventing cavitation can be achieved even in instances of purely sinusoidal/resonant oscillation motion of the cutting tube  1112 . The sinusoidal resonant oscillation can be sufficient velocity to disrupt lens tissue, but is slow enough to avoid cavitation as it retracts. For example, the frequency of oscillation can be reduced or the stroke distance can be reduced. In an implementation, the amplitude of the cutting tube  1112  is 0.016 inch or about 0.4 mm and the frequency is 3,900 Hz in a sinusoidal/resonant oscillation motion. The V maxR/E  in this configuration may be kept below 5 m/s, which is fast enough to disrupt the lens tissue and slow enough to avoid cavitation. The V maxR/E  can be at least about 3 m/s, but remain within the sub-ultrasonic frequency range. 
     The oscillating movements of cutting tube driven by conventional phacoemulsification systems may have a degree of variability due to normal losses during movement (e.g. due to friction or variability in material compression under load or other environmental factors). This variability may impact the maximum and average speeds achieved during retraction and extension such that the retraction speed profile and extension speed profile are not identical or perfectly sinusoidal. However, this normal variability during movements of component parts is not intentionally engineered or designed to occur (i.e. a control processor operating according to program instructions stored in a memory; or hardware in operable communication with the control processor designed to achieve different speeds depending on phase of cycling). Thus, normal variability in speed during movement is not considered to be contributing to or resulting in an asymmetric motion profile. The asymmetric motion profiles described herein are consciously engineered or designed motion profiles intended to be substantially reproducible during each cycling and not merely due to chance variability. 
     As described elsewhere herein, the aspiration pump  1014  of the hand piece  1030  can be configured to provide pulses of discontinuous negative pressure. Movement of the rollers or the pistons creates vacuum pulses that can be coordinated or linked to phases of movement of the elongate cutting tube  1112 . 
     For example, a pulse of aspiration can be drawn through the lumen  1110  of the cutting tube  1112  during at least a portion of the extension as the cutting tube  1112  moves in a distal direction and/or during at least a portion of the retraction as the cutting tube  1112  moves in a proximal direction.  FIG. 11A  illustrates an implementation of a vacuum profile over time for the pulsatile vacuum applied through the distal end region of the lumen  1110  of the cutting tube  1112  where the pump  1014  is a piston pump having a plurality of pistons. The plurality of pistons may be configured to move sequentially within their respective pumping chambers creating periods of increasing vacuum interspersed by periods of decreasing vacuum. It should be appreciated that a pulsatile aspiration can be achieved with other pump configurations such as a peristaltic pump or other pump configuration. In some implementations, the increase in vacuum can occur faster than the decrease in the vacuum providing a vacuum profile. The pulsatile vacuum profile applied through the lumen  1110  of the cutting tube  1112  can be synchronized with the motion profile of the cutting tube  1112  performing the cutting such that at least a part of the period of negative pressure is applied during a certain phase of movement.  FIGS. 11B-11D  show the movement of the cutting tube  1112  (solid lines) relative to the periods of negative pressure (hatched lines) applied through the cutting tube  1112 . The period of negative pressure (i.e. vacuum pulse) can occur before forward stroke or distal extension E of the cutting tube  1112 , during at least part of the forward stroke or distal extension E of the cutting tube  1112 , dwell time after distal extension E and before proximal retraction R, and/or during at least part of the proximal retraction R of the cutting tube  1112 . For example,  FIG. 11B  shows a first pulse of vacuum pressure occurs during the extension E of the cutting tube  1112  as well as the dwell time after extension E and before retraction R. The first pulse of vacuum pressure ends during the retraction R phase and a second pulse of vacuum begins and ends before the same retraction phase ends.  FIG. 11C  shows another implementation where a first pulse of vacuum pressure begins during extension E of the cutting tube  1112  and is maintained during retraction R phase of the cutting tube  1112  as well as during a second extension E of the cutting tube.  FIG. 11B  shows the vacuum pulse having about 2× the frequency of tip movement and  FIG. 11C  and also  FIG. 11F  shows the tip movement having about 2× the frequency of the vacuum pulse. Both  FIG. 11B  and  FIG. 11C  show vacuum pulse occurring during a portion of the extension E and retraction R.  FIG. 11D  shows another implementation of the coordination between cutting tube movement and application of negative pressure. The motion profile of the cutting tube (solid lines) need not correspond with a single trapezoidal vacuum pulse (hatched lines). Rather, the motion of the cutting tube can allow for multiple extensions E and retractions R (or oscillations) during a single pulse of vacuum.  FIGS. 11D and 11F  illustrate the movement of the cutting tube or tip oscillation can begin after the vacuum pulse is initiated. The cutting tube can undergo multiple extensions and retractions for each pulse of vacuum.  FIG. 11F  shows two cycles of cutting tube extension and retraction for each pulse of vacuum. The cutting tube can extend and retract a number of times (1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 times) for each pulse of vacuum such that the ratio of hits per vacuum pulse is 1:1, 2:1, 3:1, 4:1, 5:1, 10:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1 and so on. The cutting tube or tip oscillation can also begin before the vacuum pulse is initiated (see  FIG. 11C ). It should be appreciated that the hand piece can apply vacuum pulses without any cutting tube motion at all such that vacuum pulses alone are used to break up the lens. The vacuum pulses can vary in frequency from about 1 vacuum cycles/second to about 100, or from about 5 to about 50, or from about 10 to about 25 vacuum cycles/second, and any range or vacuum cycles/second amount in between. 
     Once the pulse of vacuum returns back to zero, the movement of the cutting tube or tip oscillation can cease. The system can then enter a rest period for both motion and vacuum for a period of time before the next sequence begins. The frequency of extensions and retractions of the cutting tube  1112  within a single pulse of vacuum can vary. For example, the cutting tube  1112  can undergo 1, 2, 3, 4, 5, or more extension/retraction movements for each pulse of vacuum up to about 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, or more extension/retraction movements for each pulse of vacuum. In an implementation, the speed of the retraction is half the speed of extension. In other words, the retraction time takes twice as long as the extension time to travel the same distance. The frequency for this configuration is ⅓ rd  less than the frequency for a configuration where the retraction speed is identical to the extension speed. For example, a 40 kHz, 0.1 mm phaco system would have a frequency of 27 kHz. 
     The frequency of cutting tube  1112  oscillations can change with different amplitudes and velocity thresholds. The amplitude can be between 0.005 mm to about 1.0 mm, or more preferably between 0.05 mm to about 0.1 mm. The frequency of oscillation can be less than 30,000 Hz, less than 25,000 Hz, less than 20,000 Hz, less than 15,000 Hz, or less than 10,000 Hz and down to about 0.5 Hz, or down to about 1 Hz, or down to about 2 Hz, or down to about 5 Hz, or down to about 10 Hz, or down to about 25 Hz, or down to about 50 Hz, or down to about 100 Hz, or down to about 250 Hz, or down to about 500 Hz. The frequency of cutting tube oscillation can be between about 0.5 Hz to about 30,000 Hz, or between 1 Hz to about 5000 Hz, or between about 2 Hz to about 2000 Hz. 
     As mentioned elsewhere herein, a vacuum pulse may be applied through the cutting tube  1112 . The relative coordination of the vacuum pulse and the motion of the cutting tube  1112  can vary. A pulse of vacuum may be applied during at least a portion of the extension of the cutting tube  1112 . A pulse of vacuum may be applied during at least a portion of the retraction of the cutting tube  1112 . A pulse of vacuum may be applied during at least a portion of both extension and retraction of the cutting tube  1112 . In some implementations, the pulse of vacuum may begin before and be maintained during extension of the cutting tube  1112 . The pulse of vacuum may begin after extension of the cutting tube  1112  begins. A single pulse of vacuum may be applied during multiple extensions and retractions. For example, the vacuum may be applied continuously through the cutting tube  1112  during at least about 1 oscillation, at least about 2 oscillations, at least about 5 oscillations, at least about 10 oscillations, at least about 20 oscillations, at least about 30 oscillations, at least about 40 oscillations, at least about 50 oscillations, at least about 100 oscillations of the cutting tube  1112 , up to about 500 oscillations of the cutting tube  1112 . The length of the vacuum pulse for an oscillation frequency of about 25 kHz can be at least about 2 ms up to about 25 ms. As an example, the cutting tube  1112  may oscillate 50 times during a single vacuum pulse that lasts 25 ms such that the frequency of oscillation of the cutting tube  1112  is about 2000 Hz. 
     In some implementations, the aspiration pump  1014  is a piston pump having multiple pistons. The motions of the plurality of pistons can provide pulsatile, discontinuous aspiration. The retraction periods of the plurality of pistons may overlap in a manner that provides smooth continuous aspiration (with or without a spike in negative pressure in between movements).  FIG. 11E  shows the movement of the cutting tube  1112  (solid lines) relative to the periods of negative pressure (hatched lines) applied through the cutting tube  1112  where the aspiration pump  1014  is a piston pump having a plurality of pistons. Retraction of a first piston can create a first pulse of vacuum and retraction of a second piston can create a second pulse of vacuum that overlaps with the first pulse. Retraction of a third piston can create a third pulse of vacuum that overlaps with the second pulse of vacuum and so on. The result is a substantially continuous vacuum pressure that occurs during both extension and retraction of the cutting tube. The vacuum applied during the period of overlapping pulses can, but need not, have a reduced maximum vacuum compared to the implementation of pulsed vacuum where the pulses do not significantly overlap. 
     In some implementations, the aspiration pump  1014  is a peristaltic pump having one or more rollers.  FIG. 11G  shows an implementation of a vacuum profile over time for the pulsatile vacuum applied through the distal end region of the lumen  1110  of the cutting tube  1112  where the pump  1014  is a peristaltic pump having one or more rollers. 
     It should be appreciated that any number of various relative frequencies are considered herein and that these are illustrations of some examples of the relative speed profiles and vacuum profiles. 
     Control Unit 
     Again with respect to  FIGS. 3-4 , the hand piece  1030  may be part of or coupled to the phacoemulsification system  1010  to provide irrigation and aspiration support as well as power for the cutting tube drive mechanism and the aspiration pump  1014  in the hand piece  1030 . It should be appreciated, however, that the hand piece  1030  can be used independently of the phacoemulsification system  1010 . As described above, the system  1010  can include the control unit  1012 , which can include the ultrasonic power source  1016  and the microprocessor  1018  that provides control outputs to the pump controller  1020  and the ultrasonic power level controller  1022 . 
     The hand piece  1030  can be plugged into a socket coupled to the ultrasonic power source  1016  of the system  1010 . A proximal end of the reusable portion  1033  of the hand piece  1030  can include power cords  1160  configured for providing power to the piezoelectric stack  1120  as well as the pump motor  1115 . Power for the pump motor  1115  can be DC power whereas the power for the piezoelectric stack  1120  can be ultrasonic power similar to conventional phacoemulsification systems. 
     The control unit  1012  of the system  1010  can be controlled, adjusted, and/or programmed remotely such as via an external computing device and/or the hand piece  1030 . The control unit  1012  of the system  1010  can also be controlled, adjusted, and/or programmed directly via one or more inputs. The inputs of the system  1010  can include one or more triggers, buttons, sliders, dials, keypads, switches, touchscreens, foot pedals, or other input that can be retracted, pressed, squeezed, slid, tapped, or otherwise actuated to activate, modify, or otherwise cause a response of the system  1010 . In some implementations, the one or more inputs includes a microphone configured to receive voice commands to control, adjust, and/or program one or more components of the system  1010  as well as peripheral devices in operative communication with the system  1010 , such as a smart phone or tablet application. 
     One or more aspects of the hand piece  1030  and the system  1010  can be programmed by a user. For example, one or more aspects of the drive mechanism can be programmed by a user to control the motion of the cutting tube  1112  including, but not limited to travel distance of the cutting tube  1112 , frequency of oscillation of the cutting tube  1112 , maximum extension speed (V maxE ), minimum extension speed (V minE ), maximum retraction speed (V maxR ), minimum retraction speed (V minR ), average extension speed (V avgE ), average retraction speed (V avgR ), or any other aspect of the motion profile. In some implementations, the distance the cutting tube  1112  moves with each cycle can be adjustably programmed such that the amplitude and/or frequency of its oscillation is selectable within a range. The range of amplitude can be 0.005 mm up to about 0.4 mm. The range of frequency can be between about 0.5 Hz to about 5000 Hz, or frequency in a range of about 2 Hz to about 2000 Hz. The oscillation frequency can be less than ultrasonic, for example, less than about 20,000 Hz or within the ultrasonic range (e.g. about 20,000 Hz, to about 120,000 Hz, up to the gigahertz range). The system  1010  (and/or the hand piece  1030 ) can be programmed to provide limits on a particular action upon actuation of the input. For example, the drive mechanism can be programmed to have a minimum and/or maximum upon actuation of the input or, in the case of fluid infusion and aspiration, the device can be programmed to have a minimum and/or maximum fluid pressure upon actuation of an input. Thus, the devices described herein can be programmed using inputs adjustable by a user as well as by pre-programmed instructions that impact the one or more aspects of the device upon actuation of the inputs. 
     As mentioned above, the system  1010  can additionally include a remote aspiration pump within the control unit  1012  in addition to the aspiration pump  1014  within the hand piece  1030 . The aspiration pump  1014  integrated within the hand piece  1030  can be a relatively high pressure pump. The remote aspiration pump can be a lower pressure pump, such as a peristaltic pump within the control unit  1012  that can provide fluid movement within the aspiration line  1038  towards the waste container  1044 . The remove aspiration pump can be configured to directly accept the aspiration line  1038  to direct fluid into the waste container  1044 . For example, the remote aspiration pump can include rotating pump head having rollers around its perimeter. As the pump head rotates, the rollers press again the aspiration line  1038  causing fluid to flow within the aspiration line  1038  a certain direction (i.e. towards the waste container  1044 ). The remote aspiration pump can also accept a pump cartridge having an integrated waste container  1044 . The aspiration pump  1014  in the hand piece  1030  can be used for certain parts of a procedure, for example, during cutting of the lens material, and the remote aspiration pump in the control unit  1012  can be used for cleanup of small particles remaining in the eye after the cutting is complete. The remote aspiration pump can be activated manually such as by an input on the system  1010  and/or upon actuation of the hand piece  1030 . 
     One of more aspects of the internal aspiration pump  1014  (and any remote aspiration pump) can be programmed by a user to control the vacuum applied at the distal end region of the cutting tube  1112  including, but not limited to flow rate of aspiration, minimum vacuum pressure, maximum vacuum pressure, frequency of vacuum pulses, or any other aspect of the vacuum profile. In some implementations, the flow rate of aspiration can be adjustably programmed within a range of between about 5-100 ml/min. 
     The hand pieces described herein are configured to deliver irrigation to the work site from an irrigation fluid source  1032  fluidly coupled to the hand piece  1030  through an irrigation line  1034 . Conventional irrigation containers for ophthalmic surgery can be between 250 mL to about 500 mL each resulting in a relatively large volume of irrigation fluid available for delivery to the eye. The volume of irrigation fluid needed and thus, the size of the irrigation fluid source  1032  used during a procedure using the hand piece  1030  described herein can be drastically reduced compared to conventional systems. As described above, the hand piece  1030  has an aspiration pump  1014  positioned near the distal cutting tip, e.g. a peristaltic or roller pump, a scroll pump, a piston pump, and the like, configured to create a pulsatile vacuum profile. The strength of the pulsatile vacuum to aspirate fluid may be much stronger than vacuum applied in conventional systems not incorporating pulse. The very strong and very short pulses are sufficient to remove the lenticular tissue and thus, require only relatively small amounts of fluid. The ratio of lenticular tissue to fluid being aspirated from the anterior chamber may be higher in the hand-held devices described herein than in other currently used devices and methods. Also, the fluid volumes delivered using the devices described herein can be significantly reduced compared to known systems because irrigation is delivered only upon activation of the device. The total volume of irrigation fluid needed for a procedure using the devices described herein is significantly less (e.g. as low as about 10 mL) compared to conventional systems. In some implementations, the aspiration is delivered by a vacuum source located within the hand-held instrument (i.e. pump  1014  integrated within the hand piece  1030 ). The aspiration can be activated with finer control than currently used devices and methods. For example, the hand piece  1030  can use a finger control that allows the surgeon to easily activate the device for short periods of time in a manner more convenient and easier than would a foot pedal used in most conventional phacoemulsification machines. Further, since the vacuum source can be located within the hand piece  1030  there may be a significantly faster response time for the surgeon to activate device on and off than in other devices where the vacuum source is located in a console that is several feet away and connected by tubing. The hand piece  1030  has a relatively low amount of surge volume, and therefore cycling the device on and off has minimal downside. These features can allow the hand piece  1030  to be activated for only brief periods when the surgeon is ready to remove lenticular tissue. This contributes to overall less irrigation fluid being removed and thus less irrigation fluid needed to be delivered. 
     The volume of a human lens is about 0.10 mL-0.15 mL. The total irrigation fluid volume needed for a procedure using the devices described herein is generally less than 250 mL, such as about 10 mL, 25 mL, 50 mL, 75 mL, 100 mL, 125 mL, 150 mL, 200 mL. Generally, for the devices described herein, the ratio of irrigation fluid volume needed for a procedure to lens fluid volume is kept very low, between about 50:1, 75:1, 100:1, 150:1, 200:1, up to about 2000:1. As an example, using 10 mL of BSS is a ratio of about 100:1. In contrast, using 250 mL of BSS is a ratio of about 2500:1 of irrigation fluid to lenticular tissue. 
     The irrigation source  1032  can be suspended from a pole assembly of the system  1010 , including one or more features typical of an intravenous (IV) pole of more conventional systems. The pole assembly can include a telescoping pole configured to be movable relative to a base such that the height of one or more hangers suspending the irrigation source  1032  can be adjusted. The height of the irrigation source  1032  can be calculated to create the proper fluid pressure in the irrigation fluid line  1034 . The pole assembly can incorporate one or more buttons, levers, or foot pedals configured to adjust the height of the irrigation source  1032  thereby altering the irrigation fluid pressure and, correspondingly, alter the flow rate of the fluid in the irrigation fluid line  1034 . The height of the irrigation source  1032  can be adjusted manually and/or via a powered adjustment. For example, the pole assembly can include a motorized system configured to move the telescoping pole relative to the base. The adjustment of the telescoping pole can be a powered, automatic adjustment by the control unit  1012  depending on the fluid needs during a procedure. The irrigation fluid source  1032  can be suspended above the level of the patient by hangers on the pole assembly and one or more valves configured to control flow from the source  1032  through the irrigation fluid line  1034 . The one or more valves can include pinch valves or pinch clamps configured to tightly pinch the irrigation line  1034  thereby preventing fluid flow towards the hand piece  1030  or allowing flow of fluid from the irrigation source  1032  upon opening the valve. The valves can be manual valves or can be actuated upon an input by the control unit  1012 . 
     It should be appreciated that the irrigation fluid source  1032  need not hang from an IV pole. The volume of the irrigation fluid source  1032  can be sized small enough that it can be placed near the surgical site. For example, the irrigation fluid can be delivered from a small container, such as a syringe-type container or collapsible bag that can provide the irrigation flow without the need for gravity or for being suspended from an IV pole. The container can be fluidly coupled to the hand piece  1030  with a short irrigation line length. The container can be positioned on a user&#39;s wrist or arm (e.g. via a wristband or armband) or patient&#39;s sterile drape during use of the hand piece  1030 . In an implementation, the irrigation fluid source  1032  can be limited to volumes that are less than 250 mL, for example, between about 25 mL to about 100 mL, or as little as 10 mL up to about 100 mL. 
     The relative amounts of fluids entering and exiting the surgical field of the eye are preferably balanced such that the anterior chamber of the eye does not collapse. The irrigation fluid source  1032  can provide a constant pressure of irrigating fluid that does not change with the vacuum level provided by the aspiration pump  1014  in the hand piece  1030 . The suction flow rate out of the eye during the peak vacuum can be higher than the irrigation flow rate into the eye resulting in a momentarily lower pressure in the eye. The pressure source of the irrigating fluid can be raised so that its nominal flow rate is higher than the maximum suction flow rate at the peak vacuum pulse to avoid this low pressure situation. It is preferable, however, to keep the pressure of the irrigating fluid source lower so that the pressure within the eye remains lower than a set amount during a procedure when the vacuum is not being applied. Alternatively, the hand piece  1030  can incorporate a mechanism that is capable of delivering quick rushes or discontinuous pulses of irrigating fluid into the eye, such as from an irrigation fluid reservoir within the hand piece  1030  near the distal tip as described elsewhere herein. Each pulse of irrigation fluid can be timed to occur during each pulse of negative pressure when the suction flow rate is at its maximum. The balance of fluid within the eye can remain more consistent and the drop in pressure within the eye during the peak vacuum point is minimized. 
     Aspects of the subject matter described herein may be realized in digital electronic circuitry, integrated circuitry, specially designed ASICs (application specific integrated circuits), computer hardware, firmware, software, and/or combinations thereof. These various implementations may include an implementation in one or more computer programs that are executable and/or interpretable on a programmable system including at least one programmable processor, which may be special or general purpose, coupled to receive signals, data and instructions from, and to transmit signals, data, and instructions to, a storage system, at least one input device, and at least one output device. 
     These computer programs (also known as programs, software, software applications, or code) include machine instructions for a programmable processor, and may be implemented in a high-level procedural and/or object-oriented programming language, and/or in assembly/machine language. As used herein, the term “machine-readable medium” refers to any computer program product, apparatus, and/or device (e.g., magnetic discs, optical disks, memory, Programmable Logic Devices (PLDs)) used to provide machine instructions and/or data to a programmable processor, including a machine-readable medium that receives machine instructions as a machine-readable signal. The term “machine-readable signal” refers to any signal used to provide machine instructions and/or data to a programmable processor. 
     In various implementations, description is made with reference to the figures. However, certain implementations may be practiced without one or more of these specific details, or in combination with other known methods and configurations. In the description, numerous specific details are set forth, such as specific configurations, dimensions, and processes, in order to provide a thorough understanding of the implementations. In other instances, well-known processes and manufacturing techniques have not been described in particular detail in order to not unnecessarily obscure the description. Reference throughout this specification to “one embodiment,” “an embodiment,” “one implementation, “an implementation,” or the like, means that a particular feature, structure, configuration, or characteristic described is included in at least one embodiment or implementation. Thus, the appearance of the phrase “one embodiment,” “an embodiment,” “one implementation, “an implementation,” or the like, in various places throughout this specification are not necessarily referring to the same embodiment or implementation. Furthermore, the particular features, structures, configurations, or characteristics may be combined in any suitable manner in one or more implementations. 
     The use of relative terms throughout the description may denote a relative position or direction. For example, “distal” may indicate a first direction away from a reference point. Similarly, “proximal” may indicate a location in a second direction opposite to the first direction. However, such terms are provided to establish relative frames of reference, and are not intended to limit the use or orientation of an anchoring delivery system to a specific configuration described in the various implementations. 
     While this specification contains many specifics, these should not be construed as limitations on the scope of what is claimed or of what may be claimed, but rather as descriptions of features specific to particular embodiments. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or a variation of a sub-combination. Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Only a few examples and implementations are disclosed. Variations, modifications and enhancements to the described examples and implementations and other implementations may be made based on what is disclosed. 
     In the descriptions above and in the claims, phrases such as “at least one of” or “one or more of” may occur followed by a conjunctive list of elements or features. The term “and/or” may also occur in a list of two or more elements or features. Unless otherwise implicitly or explicitly contradicted by the context in which it is used, such a phrase is intended to mean any of the listed elements or features individually or any of the recited elements or features in combination with any of the other recited elements or features. For example, the phrases “at least one of A and B;” “one or more of A and B;” and “A and/or B” are each intended to mean “A alone, B alone, or A and B together.” A similar interpretation is also intended for lists including three or more items. For example, the phrases “at least one of A, B, and C;” “one or more of A, B, and C;” and “A, B, and/or C” are each intended to mean “A alone, B alone, C alone, A and B together, A and C together, B and C together, or A and B and C together.” 
     Use of the term “based on,” above and in the claims is intended to mean, “based at least in part on,” such that an unrecited feature or element is also permissible.