Abstract:
A phacoemulsification needle has a polygonally-shaped tip with an axis that is offset from the axis of the needle body. The material forming the tip is non-uniformly distributed, adding to the motion of the tip when it is vibrated torsionally. In one embodiment, the tip has tip wall segments of varying thicknesses. In another embodiment, the tip has a series of external ribs formed on the tip wall segments, on the wall segment, at the apex where adjacent wall segments meet, or both.

Description:
[0001]    This application claims priority from U.S. patent application Ser. No. 61/295,763, filed Jan. 18, 2010 and entitled “Phacoemulsification Needle”, which is incorporated herein in its entirety by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This disclosure relates to surgical instruments and surgical techniques used in eye surgery and more particularly, to phacoemulsification apparatus and methods for their use. 
       BACKGROUND OF THE INVENTION 
       [0003]    A common ophthalmological surgical technique is the removal of a diseased or injured lens from the eye. Earlier techniques used for the removal of the lens typically required a substantial incision to be made in the capsular bag in which the lens is encased. Such incisions were often on the order of 12 mm in length. 
         [0004]    Later techniques focused on removing diseased lenses and inserting replacement artificial lenses through as small an incision as possible. For example, it is now a common technique to take an artificial intraocular lens (IOL), fold it and insert the folded lens through the incision, allowing the lens to unfold when it is properly positioned within the capsular bag. Similarly, efforts have been made to accomplish the removal of the diseased lens through an equally small incision. 
         [0005]    One such removal technique is known as phacoemulsification. A typical phacoemulsification tool includes a handpiece to which is attached a hollow needle. Electrical energy is applied to vibrate the needle at ultrasonic frequencies in order to fragment the diseased lens into small enough particles to be aspirated from the eye through the hollow needle. Commonly, an infusion sleeve is mounted around the needle to supply irrigating liquids to the eye in order to aid in flushing and aspirating the lens particles. 
         [0006]    It is extremely important to properly infuse liquid during such surgery. Maintaining a sufficient amount of liquid prevents collapse of certain tissues within the eye and attendant injury or damage to delicate eye structures. As an example, endothelial cells can easily be damaged during such collapse and this damage is permanent because these cells do not regenerate. One of the benefits of using as small in incision as possible during such surgery is the minimization of leakage of liquid during and after surgery and the prevention of such a collapse. 
         [0007]    Phacoemulsification needles and tips are well represented in the prior art. Needles and tips of varying configurations are well known. A particular shape for a tip or needle is often dictated by the type of handpiece with which the needle is to be used. 
         [0008]    U.S. Pat. No. 5,725,495 (Strukel et al) teaches and describes a phacoemulsification handpiece, sleeve and tip illustrating a wide variety of tip configurations and needle cross-sectional configurations. 
         [0009]    U.S. Pat. No. 6,007,555 (Devine) teaches and describes an ultrasonic needle for surgical emulsification. The needle and its tip are shown in both circular and oval configurations. 
         [0010]    U.S. Pat. No. 6,605,054 (Rockley) teaches and describes a multiple bypass port phacoemulsification tip having multiple aspiration ports and a single discharge port to infuse liquid into the eye. 
         [0011]    U.S. Pat. No. 5,879,356 (Geuder) teaches and describes a surgical instrument for crushing crystalline eye lenses by means of ultrasound and for removing lens debris by suction which demonstrates the use of a sleeve positioned concentric to the needle and having a pair of discharge ports formed thereon. 
         [0012]    U.S. Pat. No. 5,645,530 (Boukhny) teaches and describes a phacoemulsification sleeve, one variation of which has a bellows portion attached to a discharge port ring which directs an annular flow of liquid around the needle and into the eye. The use of the bellows is intended to allow the sleeve to absorb spikes in liquid pressure during the operation. 
         [0013]    Published U.S. Patent Application No. 2003/0004455 (Kadziauskas) teaches and describes a bi-manual phacoemulsification needle using separate emulsification and aspiration needles inserted into the eye simultaneously during surgery. 
         [0014]    Published U.S. Patent Application No. 2006/0217672 (Chon) teaches and describes a phacoemulsification tip that is swaged or crimped at its distal end. The tip is intended for use with a handpiece producing torsional motion and the crimping forms cutting edges at the distal end. 
         [0015]    Many phacoemulsification needles and tips are designed for use with handpieces that vibrate the needle longitudinally at relatively low frequencies. In addition to longitudinal vibration, the NeoSoniX® handpiece sold by Alcon, Inc. of Ft. Worth, Tex. has a rotational or torsional oscillation vibration frequency of about 100 cycles/second. There are also handpieces that provide torsional oscillation of the phacoemulsification tip at frequencies of about 32,000 cycles/second. 
         [0016]    U.S. Pat. No. 6,077,285 (Bouhkny) teach and describe a torsional ultrasound handpiece having two sets of piezo-electric crystals, one set arranged to operate the handpiece in a longitudinal mode and the other set arranged to operate the handpiece in a torsional mode. 
         [0017]    Use of the torsional-type handpiece has called for phacoemulsification needle tip designs differing from those used with the longitudinal-type handpiece. For example, needles have been designed with tips that are shaped, swaged and angled to take advantage of the torsional motion created by the handpiece. 
         [0018]    Many surgeons favor phacoemulsification needles having the straight tip design most commonly used with longitudinal handpieces but have found that using them with torsional handpieces does not produce good results. 
         [0019]    I have found that forming the needle tip in an off-axis position relative to the axis of the needle body causes sufficient eccentric motion, or “wobble” during torsional motion to produce improved phacoemulsification results while retaining the straight-tip configuration. Forming the needle body in an asymmetric configuration also produces useful “wobble”. I have also determined that use of an off-axis needle tip or needle body improves performance when the needle is used in a non-longitudinal type of handpiece, such as in the torsional mode or the elliptical mode. 
         [0020]    In accordance with a preferred embodiment of the apparatus a phacoemulsification needle is provided for use with a high-frequency torsional phacoemulsification handpiece with the needle having a straight needle tip with the tip being formed off-axis with respect to the hollow passage formed through the needle. 
         [0021]    In accordance with another preferred embodiment, the needle body is formed with an off-axis central aspiration passageway, a central aspiration passageway with a cross-sectional shape different from that of the needle body, or a combination of these configurations, and combined with a standard or an off-axis needle tip. 
         [0022]    While the following describes a preferred embodiment or embodiments of the present invention, it is to be understood that such description is made by way of example only and is not intended to limit the scope of the present invention. It is expected that alterations and further modifications, as well as other and further applications of the principles of the present invention will occur to others skilled in the art to which the invention relates and, while differing from the foregoing, remain within the spirit and scope of the invention as herein described and claimed. Where means-plus-function clauses are used in the claims such language is intended to cover the structures described herein as performing the recited functions and not only structural equivalents but equivalent structures as well. For the purposes of the present disclosure, two structures that perform the same function within an environment described above may be equivalent structures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    Further aspects of the present invention will be best understood by reference to the accompanying drawings in which like numbers are used to identify like parts, and which are presented to illustrate the aspects of the invention although not necessarily to actual scale, wherein: 
           [0024]      FIG. 1  is a drawing showing prior art straight oval- and square-shaped tips; 
           [0025]      FIG. 2  is a drawing showing several prior art needle cross-sectional configurations; 
           [0026]      FIG. 3  is a lateral sectional view of a portion of a phacoemulsification needle constructed in accordance with certain principles of the present invention; 
           [0027]      FIG. 4  is an end view of the needle of  FIG. 3 ; 
           [0028]      FIG. 5  is a lateral sectional view of a second embodiment of a phacoemulsification needle applying certain principles of the present invention; 
           [0029]      FIG. 6  is an end view of the needle of  FIG. 5 ; 
           [0030]      FIG. 7  is an end view of a third embodiment of a phacoemulsification needle applying certain principles of the present invention; 
           [0031]      FIG. 8  is a lateral view of the needle of  FIG. 7 ; 
           [0032]      FIG. 9  is an end view of a fourth embodiment of a phacoemulsification needle applying certain principles of the present invention; and 
           [0033]      FIG. 10  is a lateral view of the needle of  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0034]    Referring now to  FIG. 1 , the numeral  10  indicates generally a prior art phacoemulsification needle tip as shown in U.S. Pat. No. 6,007,555. Needle  10  terminates in a mouth  12  defined by a lip  14  at the end of needle body  16 , with lip  14  and needle body  16  formed as having an oval cross-section configuration. 
         [0035]    Referring to  FIG. 1 , the numeral  18  indicates generally a prior art phacoemulsification needle tip from U.S. Pat. No. 6,007,555, having a mouth  20  defined by a lip  22  at the end of needle  24 . The cross-sectional configuration of needle  18  and mouth  20  is a rectangle. 
         [0036]    Referring now to  FIG. 2 , the numeral  26  identifies several prior art phacoemulsification needles as described in U.S. Pat. No. 5,725,495, with needle  28  having a circular cross-section as shown at  30 , needle  32  having a triangular cross-section as shown at  34  and needle  36  having an octagonal cross-section as shown at  38 . 
         [0037]    Both tips  10  and  18  in  FIG. 1  exemplify one form of a “straight” needle tip, that is, a tip that is coaxial with or centered on the hollow aspiration passageway formed through the needle body. Other straight tips are known which have needle tips that are flared, that is, larger in cross-sectional area than the needle&#39;s aspiration passageway yet which are centered on the passageway. 
         [0038]    Referring now to  FIG. 3 , the numeral  40  indicates, generally, a phacoemulsification needle embodying certain aspects of the present invention. Needle  40  has a hollow needle body  42  through which an aspiration passageway  44  is formed. Needle  40  terminates at a tip  46  having a lip  48  which defines a tip mouth  50 . Tip  46  is hollow having a tip cavity  52  which communicates with aspiration passageway  44 . 
         [0039]    As seen in  FIG. 4 , tip  46  is formed with an octagonal cross-sectional shape having outer tip wall segments  46   a ,  46   b ,  46   d ,  46   e ,  46   f ,  46   g , and  46   h.    
         [0040]    As further seen in  FIGS. 3 and 4 , tip  46  has a central axis  58  while a needle body  42  has a central axis  60 . In the embodiment shown, needle axis  58  is offset from tip body axis  60  by an offset distance  62 . 
         [0041]    Offset  62  results from the fact that while a portion of tip  46  is coextensive with a portion of tip body  42 , other portions of tip  46  extend past tip body  42 . In other words, tip  46  is flared, meaning that a significant portion of the cross-sectional configuration of tip  46  is larger in diameter than that of needle body  42  and that the flare with which tip  46  is constructed is not symmetrical about needle body  42 . 
         [0042]    As seen in  FIG. 3 , tip wall segment  46   a  has a first inner wall segment  64  which terminates at lip  48  and extends axially in a direction distal from lip  48  at an angle to tip wall segment  46   a . First inner wall segment  64  is contiguous with a second inner wall segment  66  which, in this embodiment extends generally parallel to and extending in a rear axial direction from first inner wall segment  64 . A third inner wall segment  68  is formed at an angle to second wall segment  66  and extends from second wall segment  62  to needle body  42 . In similar fashion, outer wall segment  70  of tip  46  extends at an angle to tip wall segment  46   a  and terminates at and is integral with needle body  42 . Thus, when tip wall segment  46   a , outer wall segment  70  and outer needle body wall segment  54  are contiguous as are inner first wall segment  64 , second wall segment  66 , third wall segment  68  and inner needle body  56 . 
         [0043]    As further seen in  FIGS. 3 and 4 , outer tip wall segment  46   e  which is diametrically opposite to wall segment  46   a  is not offset from needle body  42 , with inner wall segment  72  of tip  46  being contiguous with inner wall  56  of needle body  42 . 
         [0044]    As can be appreciated from the drawings, wall segments  46   b ,  46   c  and  46   d  are offset, to varying degrees, from needle body outer wall  54 . In like fashion, segments  46   f ,  46   g  and  46   h  are similarly and varyingly offset. 
         [0045]    In a preferred embodiment, segment  46   e  has little or no offset, segments  46   d  and  46   f  have identical offsets, being greater than the offset to segment  46   e , segments  46   c  and  46   g  have identical offsets, said offsets being greater than the offsets to segments  46   d  and  46   f , segments  46   b  and  46   h  have identical offsets with said offsets being greater than the offsets of segments  46   c  and  46   g , and  46   a  has an offset greater than the offsets for segments  46   b  and  46   h.    
         [0046]    As further seen in  FIG. 3 , the portion of tip  40  defined by segments  46   a ,  70 ,  64 ,  66  and  68  include a greater amount of tip material than the portion defined by segment  46   e  and inner surface  56 . In like fashion, varying amounts of tip material are contained in segments  46   b  and  46   h ,  46   c  and  46   g , and  46   d  and  46   f . This non-uniform distribution of tip material or tip mass makes tip  46  asymmetrical with respect to mass distribution as well as asymmetrical with respect to axis  60  of needle body  42 . 
         [0047]    Referring now to  FIG. 5 , a phacoemulsification needle  74  is shown having a hollow needle body  76  through which an aspiration passageway  78  is formed. At the distal end of needle body  76 , a needle tip  80  is formed which, as seen in  FIG. 5 , is flared and has a larger cross-sectional area than needle body  76 . Tip  80  terminates at a lip  82  which defines a tip mouth  84 . 
         [0048]    As seen in  FIG. 5 , tip body  76  has a central axis  86  while tip  80  has a central axis  88  with axes  86  and  88  being offset by a distance  90 . 
         [0049]    As seen in  FIG. 6 , tip  80  has a square cross-sectional shape having tip wall segments  92 ,  94 ,  96  and  98  terminating at and communicating with aspiration passageway  78 . As seen in  FIG. 6 , each tip wall segment has a corresponding inner wall portion with tip wall segment  92  having an inner wall portion  100 , tip wall segment having an inner wall portion  102 , tip wall segment  96  having an inner wall portion  104 , and tip wall portion  98  having an inner wall portion  106 . As seen in  FIG. 5 , inner wall portion  100  is formed at an angle to tip axis  88 . In like fashion, inner tip wall portions  102  and  106  are formed at angles to tip axis  88  and, in this embodiment, are formed at identical angles while inner wall portion  104  is formed at an angle to tip axis  88  that differs from the angles of inner wall portions  100 ,  102  and  106 . 
         [0050]    As seen in  FIG. 5 , the angle at which inner wall portion  100  is inclined creates a tip body portion  108  differing in size and dimension than the tip wall portions defined by inner wall segments  102 ,  104  and  106 . This configuration results in a non-uniform distribution of tip material which creates a “wobble” effect when needle  74  is vibrated by a phacoemulsification handpiece. 
         [0051]    As seen in  FIGS. 3-6 , the needle embodiments described herein have outer tip wall surfaces which act as cutting or emulsifying surfaces when the tips are moved in a torsional direction. The non-uniform distribution of tip wall material adds to the efficiency of the tip when used in the torsional mode by adding increased torsional motion to the tip. 
         [0052]    Referring now to  FIG. 7 , the numeral  110  identifies a needle tip having a generally octagonal configuration such as that shown in  FIG. 4 . Tip  110  has flats  112 , with adjacent flats  112  meeting at apices  114 . An octagonal tip will have eight such flats and eight such apices. 
         [0053]    In the embodiment shown, an external ridge  116  is formed at each such apex  114 . As seen in  FIG. 8 , ridges  116  are formed integrally with tip  110 . It is also possible to form ridges  116  on tip  110  after tip  110  has been manufactured. 
         [0054]    As seen in  FIG. 7 , ridges  116  can be of varying lengths when tip  110  is formed with an angled or Kellman configuration. Thus, ridge  116  is longer than ridge  116 ′ which, in turn, is longer than ridge  116 ″ which, in turn, is longer than ridge  116 ′. 
         [0055]    While tip  110  is shown with an octagonal configuration, various other geometric shapes may also be used, with ridges formed and sized to fit at corresponding apices. 
         [0056]    Referring now to  FIGS. 9 and 10 , the numeral  118  identifies generally a needle tip having a generally octagonal shape. Tip  118  has eight flats  120 , with adjacent flats meeting at apices  122 . As seen in  FIG. 9 , a series of blocks are formed on selected of flats  20   120 . In the embodiment shown, a first block  124  is formed on flat  120 ′, a second block  126  is formed on flat  120 ″, a third block  128  is formed on flat  120 ′″ and a fourth block  130  is formed on flat  120 ″. In this embodiment, none of flats  120 ′- 120 ′″ are adjacent to one another. 
         [0057]    Each block is formed with a generally rectangular cross-section which rises above 25 its corresponding flat to a selected height and may extend a selected lateral distance between adjacent apices. 
         [0058]    As seen in  FIG. 10 , each block maybe tapered at its lead edge. Thus, block  124  has a lead taper  132  and block  128  has a lead taper  134 . [0059] The blocks shown in  FIGS. 9 and 10  are formed on non-adjacent flats: it is also possible to form blocks on selected flats depending upon the cross-sectional configuration  5  of the tip and the desired phaco effect. 
         [0059]    It is believed that configurations such as shown in  FIGS. 7-10  benefit from having longitudinally-extending external ridges or blocks which have exposed lateral surfaces which, it is believed, increases phaco efficiency when the tip is moved torsionally.