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 . in one embodiment of the present invention , fig1 is a diagram of the components in the fluid path of a phacoemulsification system . fig1 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 . 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 ). 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 fig2 ) 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 fig2 a ). 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 . fig2 a is a perspective view of the distal end of a phacoemulsification hand piece according to the principles of the present invention . in fig2 , 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 fig2 b - 2d . in fig2 b , needle 1210 vibrates in longitudinal mode ( back and forth ). in fig2 c , needle 1210 vibrates in torsional mode ( or in a twisting or sweeping manner ). in fig2 d , needle 1210 vibrates in both longitudinal and torsional modes simultaneously . the two different modes ( longitudinal and torsional ) produce two different needle motions as shown in fig2 b - 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 . 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 . fig3 is a perspective view of a horn and needle assembly according to the principles of the present invention . in fig3 , 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 fig4 , 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 . the assembly shown in fig3 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 . 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 fig3 . 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 fig3 . 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 . fig4 shows a horn and transducer assembly according to the principles of the present invention . in the example of fig4 , 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 . 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 fig4 , 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 . as shown in fig5 a 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 . in fig5 a , transducers 1410 and 1420 are held flush against ears 1320 and 1321 . in fig5 b , 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 . 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 fig5 b , 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 fig5 a , 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 fig5 a is greater than the angle between the transducers 1410 and 1420 and the ears 1320 and 1321 , respectively , in fig5 b . the reduced angle in fig5 b results in less stress on the transducers 1410 and 1420 which may prevent them from cracking . fig6 a and 6b are diagrams of two embodiments of a transducer and horn according to the principles of the present invention . in fig6 a 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 fig6 a 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 . fig6 b 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 fig5 b . likewise , transducer 1420 may be held at an angle against ear 1321 in a manner similar to that depicted in fig5 b . in the embodiment of fig6 a 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 . 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 . 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 . 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 . 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 .
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 .