Abstract:
An ophthalmic surgical hand piece has a horn and two transducers. The horn has a central axis. A flange having a generally flat surface is coupled to the horn. The flange extends radially from the horn and generally perpendicular to the central axis. A first ear having a generally flat surface is coupled to the horn. The first ear extends from the horn such that the generally flat surface of the first ear is generally perpendicular to the generally flat surface of the flange. A first transducer is held against the flange, and a second transducer held against the ear.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to phacoemulsification surgery and more particularly to phacoemulsification hand piece that is capable of imparting both longitudinal and torsional motion to a cutting tip. 
         [0002]    The human eye functions to provide vision by transmitting light through a clear outer portion called the cornea, and focusing the image by way of a crystalline lens onto a retina. The quality of the focused image depends on many factors including the size and shape of the eye, and the transparency of the cornea and the lens. When age or disease causes the lens to become less transparent, vision deteriorates because of the diminished light which can be transmitted to the retina. This deficiency in the lens of the eye is medically known as a cataract. An accepted treatment for this condition is surgical removal of the lens and replacement of the lens function by an artificial intraocular lens (IOL). 
         [0003]    In the United States, the majority of cataractous lenses are removed by a surgical technique called phacoemulsification. A typical surgical hand piece suitable for phacoemulsification procedures consists of an ultrasonically driven phacoemulsification hand piece, an attached hollow cutting needle surrounded by an irrigating sleeve, and an electronic control console. The hand piece assembly is attached to the control console by an electric cable and flexible tubing. Through the electric cable, the console varies the power level transmitted by the hand piece to the attached cutting needle. The flexible tubing supplies irrigation fluid to the surgical site and draws aspiration fluid from the eye through the hand piece assembly. 
         [0004]    The operative part in a typical hand piece is a centrally located, hollow resonating bar or horn directly attached to a set of piezoelectric crystals. The crystals supply the required ultrasonic vibration needed to drive both the horn and the attached cutting needle during phacoemulsification, and are controlled by the console. The crystal/horn assembly is suspended within the hollow body or shell of the hand piece by flexible mountings. The hand piece body terminates in a reduced diameter portion or nosecone at the body&#39;s distal end. Typically, the nosecone is externally threaded to accept the hollow irrigation sleeve, which surrounds most of the length of the cutting needle. Likewise, the horn bore is internally threaded at its distal end to receive the external threads of the cutting tip. The irrigation sleeve also has an internally threaded bore that is screwed onto the external threads of the nosecone. The cutting needle is adjusted so that its tip projects only a predetermined amount past the open end of the irrigating sleeve. 
         [0005]    During the phacoemulsification procedure, the tip of the cutting needle and the end of the irrigation sleeve are inserted into the anterior capsule of the eye through a small incision in the outer tissue of the eye. The surgeon brings the tip of the cutting needle into contact with the lens of the eye, so that the vibrating tip fragments the lens. The resulting fragments are aspirated out of the eye through the interior bore of the cutting needle, along with irrigation solution provided to the eye during the procedure, and into a waste reservoir. 
         [0006]    Power is applied to the hand piece to vibrate the cutting needle. In general, the amplitude of needle movement (or vibration) is proportional to the power applied. In conventional phacoemulsification systems, the needle vibrates back and forth producing a longitudinal needle stroke. In improved systems, the needle may be caused to vibrate in a twisting or torsional motion. One way to achieve twisting or torsional motion is described in U.S. Pat. No. 7,651,490. Twisting or torsional motion of the cutting tip has proven a very effective way of removing lens material. Twisting or torsional movement of the cutting tip avoids repulsion that can occur with traditional longitudinal movement of the cutting tip and leads to more effective lens removal. In other instances, longitudinal motion may be used to clear an occluded tip by pushing the lens material away from the tip. As such, during cataract surgery both longitudinal and torsional or twisting motion may be desirable depending on the circumstances. Moreover, it may also be desirable to have both types of motion at the cutting tip simultaneously. 
       SUMMARY OF THE INVENTION 
       [0007]    In one embodiment consistent with the principles of the present invention, the present invention is an ophthalmic surgical hand piece having a horn and two transducers. The horn has a central axis. A flange having a generally flat surface is coupled to the horn. The flange extends radially from the horn and generally perpendicular to the central axis. A first ear having a generally flat surface is coupled to the horn. The first ear extends from the horn such that the generally flat surface of the first ear is generally perpendicular to the generally flat surface of the flange. A first transducer is held against the flange, and a second transducer held against the ear. 
         [0008]    In another embodiment consistent with the principles of the present invention, the present invention is an ophthalmic surgical hand piece having a horn with a central axis. A flange is coupled to the horn. The flange has a first surface generally perpendicular to the central axis of the horn and a second surface generally parallel to the central axis of the horn. A first ear is coupled to the horn. The first ear has a generally flat surface extending from the horn such that the generally flat surface of the first ear is generally parallel to the second surface of the flange. A first transducer is held against the first surface of the flange. A second transducer held between the first ear and the second surface of the flange. 
         [0009]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the invention as claimed. The following description, as well as the practice of the invention, set forth and suggest additional advantages and purposes of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention. 
           [0011]      FIG. 1  is a diagram of the components in the fluid path of a phacoemulsification system. 
           [0012]      FIGS. 2A-2D  are perspective views of the distal end of a phacoemulsification needle and irrigation sleeve according to the principles of the present invention. 
           [0013]      FIG. 3  is a perspective view of a horn and needle assembly according to the principles of the present invention. 
           [0014]      FIG. 4  is a perspective view of a horn according to the principles of the present invention. 
           [0015]      FIGS. 5A and 5B  are diagrams of two embodiments of a transducer and horn according to the principles of the present invention. 
           [0016]      FIGS. 6A and 6B  are diagrams of two embodiments of a transducer and horn according to the principles of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0017]    Reference is now made in detail to the exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like parts. 
         [0018]    In one embodiment of the present invention,  FIG. 1  is a diagram of the components in the fluid path of a phacoemulsification system.  FIG. 1  depicts the fluid path through the eye  1145  during cataract surgery. The components include an irrigation fluid source  1105 , an irrigation pressure sensor  1130 , an irrigation valve  1135 , an irrigation line  1140 , a hand piece  1150 , an aspiration line  1155 , an aspiration pressure sensor  1160 , a vent valve  1165 , a pump  1170 , a reservoir  1175  and a drain bag  1180 . The irrigation line  1140  provides irrigation fluid to the eye  1145  during cataract surgery. The aspiration line  1155  removes fluid and emulsified lens particles from the eye during cataract surgery. 
         [0019]    When irrigation fluid exits irrigation fluid source  1105 , it travels through irrigation line  1140  and into the eye  1145 . An irrigation pressure sensor  1130  measures the pressure of the irrigation fluid in irrigation line  1140 . An optional irrigation valve  1135  is also provided for on/off control of irrigation. Irrigation pressure sensor  1130  is implemented by any of a number of commercially available fluid pressure sensors and can be located anywhere in the irrigation fluid path (anywhere between the irrigation source  1105  and the eye  1145 ). 
         [0020]    A hand piece  1150  is placed in the eye  1145  during a phacoemulsification procedure. The hand piece  1150  has a hollow needle (as seen in  FIG. 2 ) that is ultrasonically vibrated in the eye to break up the diseased lens. A sleeve located around the needle provides irrigation fluid from irrigation line  1140 . The irrigation fluid passes through the space between the outside of the needle and the inside of the sleeve (as more clearly shown in  FIG. 2A ). Fluid and lens particles are aspirated through the hollow needle. In this manner, the interior passage of the hollow needle is fluidly coupled to aspiration line  1155 . Pump  1170  draws the aspirated fluid from the eye  1145 . An aspiration pressure sensor  1160  measures the pressure in the aspiration line. An optional vent valve can be used to vent the vacuum created by pump  1170 . The aspirated fluid passes through reservoir  1175  and into drain bag  1180 . 
         [0021]      FIG. 2A  is a perspective view of the distal end of a phacoemulsification hand piece according to the principles of the present invention. In  FIG. 2 , a phacoemulsification needle  1210  is surrounded by an irrigation sleeve  1230 . The phacoemulsification needle  1210  has an open end  1220  through which lens particles are aspirated from the eye during cataract surgery. The irrigation sleeve  1230  has an optional opening  1240  through which irrigation fluid flows into the eye. The needle  1210  and sleeve  1230  are both inserted into the anterior chamber of the eye during cataract surgery. When power is applied to the hand piece, the needle  1210  vibrates ultrasonically in a longitudinal mode, a torsional mode, or in both modes simultaneously. This is more clearly seen in  FIGS. 2B-2D . In  FIG. 2B , needle  1210  vibrates in longitudinal mode (back and forth). In  FIG. 2C , needle  1210  vibrates in torsional mode (or in a twisting or sweeping manner). In  FIG. 2D , needle  1210  vibrates in both longitudinal and torsional modes simultaneously. 
         [0022]    The two different modes (longitudinal and torsional) produce two different needle motions as shown in  FIGS. 2B-2D . In general, longitudinal mode can act to cut a cataractous lens by impacting the end of the needle  1210  against the lens much like a jackhammer. Torsional mode can act to cut a lens with a side to side sweep of the end of the needle  1210 . Depending on the needle geometry, the twisting motion imparted to the needle  1210  in torsional mode generally produces a side to side sweep of the end of the needle  1210 . In other instances, the end of the needle  1210  sweeps in an arc. Regardless, torsional mode may be more effective in cutting a lens because it allows aspiration through open end  1220  of needle  1210  to hold the lens material on the needle  1210  for more effective cutting. In addition, in torsional mode, each sweep of the needle  1210  acts to cut the lens. In contrast, longitudinal mode produces a jack hammer motion that impacts the lens only in a forward direction (and not in a return direction). Moreover, longitudinal mode may act to repel the lens material away from the needle which may reduce cutting efficiency. However, when the open end  1220  of the needle  1210  is occluded or blocked by lens material, the repulsion effect of longitudinal mode may be effective at clearing the material which can be desirable. 
         [0023]    When both modes are operated simultaneously, the needle  1210  moves both longitudinally and torsionally at the same time. The amount of longitudinal and torsional motion can be controlled independently as explained below. In some instances, this combination motion may be more effective at cutting the lens and/or clearing lens material from the open end  1220  of needle  1210 . 
         [0024]      FIG. 3  is a perspective view of a horn and needle assembly according to the principles of the present invention. In  FIG. 3 , horn  1300  has a flange  1310 , and two ears  1320  and  1321 . A needle  1210  with an open end  1220  is coupled to horn  1300  via hub  1340 . Needle  1210  is typically coupled to horn  1300  via a threaded connection at hub  1340 . The horn  1300  is coupled to one or more transducers as shown in  FIGS. 4 ,  5 A, and  5 B. Horn  1300  is typically made of a solid material such as a titanium alloy. One or more transducers produce vibrations which are imparted to horn  1300 . As horn  1300  vibrates, needle  1210  also vibrates. In this manner, if horn  1300  is vibrated longitudinally, then needle  1210  also vibrates longitudinally. Likewise, if horn  1300  vibrates torsionally, then needle  1210  also vibrates torsionally. 
         [0025]    The assembly shown in  FIG. 3  is a part of a larger phacoemulsification hand piece. The horn  1300  and associated transducer(s) are held within a hand piece shell (not shown). The hand piece shell is of a form factor suitable to be held in the hand and manipulated by a surgeon during cataract surgery. As such, the shell is typically about the size of a large pencil or pen. The needle  1210  and hub  1340  typically extend from one end of the hand piece shell (not shown). In this manner, the needle  1210  (and irrigation sleeve) can be inserted into the eye and vibrated ultrasonically to fragment the lens. 
         [0026]    Horn  1300  may be machined from a single piece of material. Flange  1310  extends radially from the horn&#39;s central body as shown in  FIG. 3 . In this example, flange  1310  is in the general shape of a disc, though it may be other shapes. Flange  1310  is arranged such that one or more transducers can be held against it. Likewise, ears  1320  and  1321  extend outward from the horn&#39;s central body as shown in  FIG. 3 . In this example, ears  1320  and  1321  are generally square or rectangular in shape, though they may be of other shapes. Ears  1320  and  1321  are arranged so that one or more transducers can be held against them. 
         [0027]      FIG. 4  shows a horn and transducer assembly according to the principles of the present invention. In the example of  FIG. 4 , horn  1300  has a flange  1310  and two ears  1320  and  1321 . A lumen  1330  extends through horn  1300 . Aspirated lens material flows through lumen  1330 . In this manner, lumen  1330  is coextensive with the internal lumen of needle  1210  (when needle  1210  is coupled to horn  1300 ). As such, when needle  1210  fragments lens material, that lens material can be aspirated through the internal lumen of needle  1210  and lumen  1330  of horn  1300 . 
         [0028]    Transducer  1400  is held against flange  1310  such that vibration produced by transducer  1400  results in vibration of horn  1300  (and needle  1210  when needle  1210  is coupled to horn  1300 ). In  FIG. 4 , transducer  1400  vibrates longitudinally (back and forth). Since transducer  1400  is held against flange  1310  (which is a part of horn  1300 ), horn  1300  also vibrates longitudinally. Consequently, a needle attached to horn  1300  would also vibrate longitudinally. In this manner, transducer  1400 , when activated, operates the hand piece in longitudinal mode. 
         [0029]    As shown in  FIGS. 5A and 5B , transducers  1410  and  1420  are held against ears  1320  and  1321 . Transducers  1410  and  1420  vibrate longitudinally (back and forth). Since transducers  1410  and  1420  are held against ears  1320  and  1321 , horn  1300  is caused to vibrate torsionally or in a twisting or rotating manner. This torsional or twisting movement of horn is produced as the transducers  1410  and  1420  press against ears  1320  and  1321  causing a partial rotation of horn  1300 . In this manner, transducers  1410  and  1420  produce vibration that is generally orthogonal to the vibration produced by transducer  1400 . A needle coupled to horn  1300  would also vibrate torsionally or in a twisting fashion (i.e. in torsional mode). Typically, transducers  1400 ,  1410 , and  1420  are piezoelectric crystals which are commonly used in ophthalmic ultrasound hand pieces. 
         [0030]    In  FIG. 5A , transducers  1410  and  1420  are held flush against ears  1320  and  1321 . In  FIG. 5B , transducers  1410  and  1420  are held at an angle against ears  1320  and  1321 . Since transducers  1410  and  1420  vibrate longitudinally and ears  1320  and  1321  can only rotate about the central axis of horn  1300 , either of these two configurations can produce sufficient torsional or twisting motion of horn  1300  and an attached needle. 
         [0031]    To achieve torsional or twisting motion of horn  1300  and attached needle  1210 , the transducers  1410  and  1420  move longitudinally to cause a rotation of ears  1320  and  1321  about the central axis of horn  1300 . In  FIG. 5B , the transducers  1410  and  1420  may be held at an angle equal to one half of the targeted ear rotation angle. In this way, when the transducers  1410  and  1420  move the ears  1320  and  1321  to the targeted rotation angle, the maximum angle between the transducers  1410  and  1420  and the ears  1320  and  1321  would only be one half of the targeted ear rotation angle. In contrast, in  FIG. 5A , the angle between the transducers  1410  and  1420  and the ears  1320  and  1321 , respectively, would be the full ear rotation angle. In this manner, the angle between the transducers  1410  and  1420  and the ears  1320  and  1321 , respectively, in  FIG. 5A  is greater than the angle between the transducers  1410  and  1420  and the ears  1320  and  1321 , respectively, in  FIG. 5B . The reduced angle in  FIG. 5B  results in less stress on the transducers  1410  and  1420  which may prevent them from cracking. 
         [0032]      FIGS. 6A and 6B  are diagrams of two embodiments of a transducer and horn according to the principles of the present invention. In  FIGS. 6A and 6B , transducers  1410  and  1420  are held against ears  1320  and  1321  by a flange  1510  that is integral with or coupled to horn  1300 . In  FIGS. 6A and 6B , transducer  1400  is held between torque ring  1520  and flange  1510 . A nut  1530  secures torque ring  1520  and transducer  1400  against flange  1510 . In this manner, when transducer  1400  vibrates, horn  1300  also vibrates. 
         [0033]      FIG. 6B  shows the location of transducers  1410  and  1420 . Transducer  1410  is held between flange  1510  and ear  1320 . Likewise, transducer  1420  is held between flange  1510  and ear  1321  (not shown). While shown as being held flush against ear  1320 , transducer  1410  may be held at an angle against ear  1320  in a manner similar to that depicted in  FIG. 5B . Likewise, transducer  1420  may be held at an angle against ear  1321  in a manner similar to that depicted in  FIG. 5B . 
         [0034]    In the embodiment of  FIGS. 6A and 6B , flange  1510  may be generally planar as shown or may have a radius of curvature about the central axis of horn  1300  (i.e. the axis along the lumen  1330  of horn  1300 ). In this example, transducers  1410  and  1420  are fitted in horn  1300 . When transducers  1410  and  1420  vibrate, the vibration is localized at horn  1300 . When transducer  1400  vibrates, the transducers  1410  and  1420  move with the flange  1510 , ear  1320 , and ear  1321 . 
         [0035]    While transducers  1400 ,  1410 , and  1420  are shown on different figures, all three transducers may be employed in a single assembly. In this manner, all three transducers can be activated to vibrate the needle in longitudinal mode and torsional mode simultaneously. In addition, since transducers  1400 ,  1410 , and  1420  can each be operated separately, the amount of torsional and longitudinal motion imparted to a needle can be precisely controlled. Transducers  1400 ,  1410 , and  1420  are each typically driven by a voltage or current source. Generally, the amount of voltage (or power) applied to each transducer  1400 ,  1410 , and  1420  determine its amplitude of vibration. The higher the voltage applied, the greater the amplitude of vibration. By controlling the voltage (or power) applied to each transducer individually, the amount of longitudinal and torsional vibration can be precisely controlled. The voltages (or power) applied to transducers  1400 ,  1410  and  1420  may be applied, for example, via lead wires coupled to the transducers. 
         [0036]    For example, transducer  1400  may be driven with a low voltage that produces a small amount of longitudinal vibration in the horn  1300  and attached needle  1210 . At the same time, a greater voltage can be applied to transducers  1410  and  1420  to produce a relatively large amount of torsional or twisting vibration in horn  1300  and attached needle  1210 . Expressed as a percentage of maximum vibration, this example may yield 10% longitudinal vibration and 90% torsional vibration. In this manner, if all transducers  1400 ,  1410 , and  1420  are driven at their maximum voltages, then the longitudinal vibration is 100% and the torsional vibration is also 100%. By adjusting the driving voltages for each transducer, any combination of percentages can be produced. This manner of operating the hand piece may be beneficial in that precise amounts and types of vibration can be applied to the needle  1210  to produce a desired cutting effect. 
         [0037]    From the above, it may be appreciated that the present invention provides an improved hand piece for phacoemulsification surgery. The present invention provides a horn that is designed to impart longitudinal and torsional motion to a cutting tip simultaneously and in any proportion. The present invention is illustrated herein by example, and various modifications may be made by a person of ordinary skill in the art. 
         [0038]    Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.