Patent Publication Number: US-8974480-B2

Title: Nucleus chopper and splitter

Description:
This is a division of application Ser. No. 11/069,774, filed 1 Mar. 2005 and entitled “Combined Chopper and Splitter” which claims priority from application Ser. No. 60/600,673, filed 10 Aug. 2004 and entitled “Combined Chopper and Splitter”, both of which are hereby fully incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to surgical instruments used in opthalmological surgery and, more particularly, to an instrument which can perform both chopping and splitting operations as part of cataract removal. 
     BACKGROUND OF THE INVENTION 
     Phacoemulsification has come to be a technique of choice for the removal of damaged or diseased lenses from the eye. Commonly, such surgery is called for when a patient develops cataracts, a condition in which a portion of the eye lens becomes hard and opaque. Unless the damaged lens is removed and replaced with a properly selected artificial lens, blindness or severely impaired vision will result. 
     Phacoemulsification is the use of ultrasonic energy to emulsify the damaged lens and aspirate the resulting lens particles from the eye. One of the most significant advantages of the use of phacoemulsification is that the apparatus itself is small and can fit through a relatively small incision, resulting in less fluid leakage from the eye capsule and shorter patient recovery times. It is desirable to limit the amount of ultrasonic energy used as much as possible in order to minimize the risk of damage to eye tissue. Often, the lens nucleus (the hardest portion of the lens) is chopped or split into smaller pieces prior to or during phacoemulsification. Smaller pieces require less energy to emulsify, and this shortens the time during which ultrasonic energy is actually being supplied to the phacoemulsification apparatus. 
     Known fractionating techniques include making incisions into the lens and, thereafter, prying the incisions open to split the lens into halves or quarters. As an example, U.S. Pat. No. 5,147,368 (Brown) teaches and describes a nucleus splitter in the form of a forceps, the jaws of which are intended to be inserted into a groove or incision already cut in the nucleus. When the handle of the nucleus splitter is squeezed, the jaws are forced apart thereby prying apart the groove or incision or splitting or cracking the nucleus into fragments. 
     U.S. Pat. No. 4,428,748 (Peyman, et al.) teaches and describes a combined ultrasonic emulsifier and mechanical cutter for surgery. This device includes the typical components of a phacoemulsification apparatus, namely, an ultrasonically vibrated hollow needle and one or more aspiration ports through which the emulsified lens particles are drawn and evacuated from the eye capsule. Peyman, et al. also includes a rotary mechanical cutter formed in the tip of the apparatus to be used for cutting nuclear tissue. 
     U.S. Pat. No. 6,592,541 (Kurwa) teaches and describes an opthamological surgical instrument device and method of use in which the tip of a phacoemulsification needle is formed with a cutting edge which can be inserted into the nucleus for the purpose of making an incision. As described by the inventor, a nucleus cracker or pre-chopper is then required to split the nucleus after which the phacoemulsification instrument is reinserted and used to emulsify and aspirate the lens fragments. 
     As used throughout, the term “pre-chopping” refers to the opthalmological surgical technique of making a plunge cut directly downward into the nucleus in order to form a channel or incision. The term “chopping” refers to the technique of forming grooves or incisions in the eye by drawing an instrument having a cutting edge across the lens. 
     Examples of known prior art choppers are illustrated in the accompanying drawings. One such chopper identified as Model No. AE-2515 sold by ASICO LLC of Westmont, Ill. is shown in  FIGS. 1 ,  2  and  3  and consists of an elongated shaft having a blade portion formed at the end of the shaft and extending at an angle to the shaft. The cutting edge of the blade portion faces toward the handle of the instrument, meaning an incision is made when the instrument is placed on the nucleus and then drawn across the nucleus. This instrument is available in both 90 degree and 60 degree angled cutting edges. 
     Another prior art chopper is identified as Model No. AE-2523 manufactured by ASICO LLC and consists of an elongated shaft with a hook-like projection extending at an angle to the shaft. As with the Model AE-2515, a cutting edge is formed on the interior surface of the hook and cutting occurs when the chopper is drawn across the nucleus. The hook shape allows the Model AE-2523 to be used to manipulate the lens within the capsule. Thus, once a first incision is made, the lens may be rotated 90 degrees and a second incision made to divide the lens into four quadrants. 
       FIGS. 6 ,  7  and  8  show a prior art pre-chopper identified as Model No. AE-4287, sold by ASICO LLC. As described in more detailed herein, the Model AE-4287 has a spring steel blade assembly positioned within a tube with the end of the blade assembly forming a pair of blade leaves. The handle of the instrument is manufactured with a linkage which, in its normal position, is spread apart, a position in which the blade leaves are separated. When the handle is squeezed, the blade assembly is drawn into the blade tube and the two leaves are forced together to form a single solid blade. This blade has an upper straight surface which is sharpened and a lower curved surface which is blunt. In use, the AE4287 pre-chopper is inserted into the eye capsule and is rotated to bring the straight sharpened edge into contact with the upper surface of the lens. A plunge cut is then made to form a partial incision. The instrument is then turned 180 degrees to bring the blunt portion of the blade assembly into contact with the lens, within the incision. Thereafter, when the handle linkage is released, the leaves separate exerting a splitting or cracking force on the lens along the incision made by the pre-chopper. After several such incisions are made, and the lens is fractionated, the lens fractions may be emulsified and removed by phacoemulsification. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention is a surgical instrument which both incises and splits the nucleus of a lens in a manner which does not require the use of a pre-chopper. 
     Pursuant to the present invention, and in accordance with the teachings of the pre-chopper described above, a pair of spring steel segments are inserted into a metallic tube and may be drawn inwardly and outwardly along the tube axis. Along most of its length, each spring steel segment has a constant cross sectional dimension and is identical in dimension to the mating spring steel segment. For the purposes of this description, the spring steel segment&#39;s assembly will be referred to as a having a left hand and a right hand segment which are mirror images of each other. Each segment has an inner and an outer surface and, when assembled, the inner surfaces abut one another. 
     At the distal end of each spring steel segment a tip is formed. The tip consists of a first, ramped section formed on the outer surface and extending generally axially with the tube axis, and a second depending segment having a blunt leading edge and a sharpened trailing edge. Each depending segment terminates in a rounded, blunt end. 
     As the spring steel segments are drawn inward axially into the tube, the ramp portions on the outer surfaces contact the inner surface of the tube and the tips are pressed tightly together to form a single, virtually solid cutting blade. The blade may then be placed at one edge of the lens and drawn across the lens to form an incision. 
     The present invention also includes a handle with a spring biased linkage which, when unstressed, allows the spring steel segments to extend from the tube, leaving the left and right tips separated. When the handle of the instrument is squeezed the linkage acts to pull the spring steel segments into the tube thereby forcing the tips together to form the single, virtually solid cutting blade. 
     In use, after an incision has been made, the tip is placed in the incision and the pressure on the handle is released, allowing the blades to separate and exert a separating or cracking force along the length of the incision. Where required the first incision is deepened by subsequent additional passes of the tip until the incision is deep enough to allow the lens to be split by allowing the blade segments to separate. These steps can be repeated until the lens is successfully fractionated. 
     The size and shape of the blade ends is such that a relatively small incision along the order of 0.8 mm can be used to allow access to the lens. 
     While the following describes a preferred embodiment or embodiments of the present invention, it is to be understood that this 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 
       The foregoing will become more apparent upon consideration of the accompanying drawing figures in which: 
         FIG. 1  is a perspective view of a first prior art chopper, ASICO Model AE-2515; 
         FIG. 2  is an enlarged view of the blade end of the chopper of  FIG. 1  showing the blade with a 90 degree cutting edge; 
         FIG. 3  is an enlarged view of the blade end of  FIG. 1  showing the blade with a 60 degree cutting edge; 
         FIG. 4  is a perspective view of a second prior art chopper, ASICO Model AE-2523; 
         FIG. 5  is an enlarged view of the blade end of the chopper shown in  FIG. 4 ; 
         FIG. 6  is a perspective view of a prior art pre-chopper, ASICO Model AE-4287; 
         FIG. 7  is an enlarged view of the blade leaves of the pre-chopper shown in  FIG. 6  shown in the closed position; 
         FIG. 8  is an enlarged view of the blade leaves of the pre-chopper shown in  FIG. 6  shown in the separated position; 
         FIG. 9  is a perspective view of a preferred embodiment of the present invention; 
         FIG. 10  is an enlarged view of a portion of the instrument shown in  FIG. 9  showing the handle linkage in its open position; 
         FIG. 11  is an enlarged view of a portion of the view of  FIG. 10  showing the linkage in greater detail; 
         FIG. 12  is a lateral schematic view of a left blade segment; 
         FIG. 13  is a top schematic view of the blade segment of  FIG. 12 ; 
         FIG. 14  is an enlarged view of the blade leaves extending from the blade tube shown in the open position; 
         FIG. 15  is an enlarged detail of the blades shown in the open position; 
         FIG. 16  is an enlarged perspective view of the blade leaves extending from the blade tube and shown in the closed position; 
         FIG. 17  is an enlarged detail of the blade leaves shown in the closed position; and 
         FIG. 18  is a partial sectional view taken along line  18 - 18  of  FIG. 12 . 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Referring now to  FIG. 1 , the numeral  10  indicates generally a first prior art chopper having a solid metallic body  12  from which a chopper blade  14  extends. As seen in  FIG. 1 , blade  14  has a first segment  16  generally coaxial with handle  12  a second segment  18  angled with respect to first segment  16  and a blade tip  20 . 
     Referring now to  FIG. 2 , blade tip  20  is shown in an enlarged view as having a depending blade segment  22  extending at generally right angles to second blade segment  18 . Blade segment  22  has a lead surface  24  which is polished and rounded in shape and a trailing surface  26  formed as a cutting edge. Cutting edge  26  terminates in a rounded bottom  28 , formed as a smooth surface to protect other tissue in the eye. 
     Referring now to  FIG. 3 , a second tip embodiment  30  is shown having a lead or distal edge  32  which is formed with a rounded and smoothed surface  34 . Opposite surface  34 , a cutting edge  36  is formed and the small sectional view shown in  FIG. 3  demonstrates that cutting edge  36  is formed by the intersection of surfaces  38  and  40  at a 60° angle. 
     Referring now to  FIG. 4 , a second prior art chopper  42  is shown, identified as ASICO Model AE-2523. Chopper  42  has a solid metallic handle  44  with a blade  46  extending therefrom. Blade  46  has a first segment  48  coaxial with handle  44 , a second segment  50  extending at an angle to first segment  48  and a hook segment  52  which forms the terminus of segment  50 . As seen in  FIG. 5 , hook segment  52  has a first hook segment  54  angled with respect to segment  50 , a second hook segment  56  and a terminus  58 . Terminus  58  is rounded and smoothed to protect any eye tissue with which it may come into contact from being cut. The trailing surface of second hook segment  56  has a cutting edge  60  formed thereon which performs the cutting or incising operation when chopper  42  is drawn across an eye lens. 
     Referring now to  FIG. 6 , the numeral  62  refers generally to a prior art pre-chopper identified above as ASICO Model AE-4287. Pre-chopper  62  has a handle assembly  64  to which is affixed a guide tube  66  from which protrudes a pre-chopper blade assembly  68 . Blade assembly  68 , while not shown herein in detail, comprises a pair of blade segments formed from spring steel which have a natural tendency to curl away from each other. 
     Referring now to  FIG. 7 , an enlarged view of pre-chopper blade assembly  68  is shown. Left hand leaf  70  is shown having an upper cutting edge  72  and a lower blunt edge  74  formed thereon. In this embodiment, sharp edge  72  is formed as a straight edge while blunt edge  74  is formed as a curved edge. 
     Referring now to  FIG. 8 , left blade leaf  70  is shown paired with right leaf  76 . As with left leaf  74 , right leaf  76  has an upper, sharpened surface  78  and a lower blunt surface  80 . It should be understood that left leaf  70  and right leaf  76  are mirror images of each other and that the interior surface  82  of left leaf  70  is flat as is the interior surface of right leaf  84 . 
     Also as seen in  FIG. 8 , left leaf  70  has a blade ramp  86  formed thereon and right blade leaf  76  has a mirror image ramp  88  formed thereon. 
     When handle  64  of pre-chopper  62  is unstressed, the left and right leaves  70 ,  76  are positioned apart as shown in  FIG. 8 . When handle  64  is squeezed, guide tube  66  is moved axially forward. When ramps  86 ,  88  come into contact with the interior surface of tube  66 , leaves  70 ,  76  are forced inward towards each other until they abut as shown in  FIG. 7 . In this position, edges  72 ,  78  act as a single cutting edge while lower surfaces  74 ,  80  act as a single blunt surface. 
     Referring now to  FIG. 9 , the numeral  90  refers generally to an instrument for chopping and splitting lenses incorporating a preferred embodiment of the invention. Instrument  90  has a handle  92  with a distal end  94  and a proximal end  96 . A mounting hub  98  is attached to handle  90  at proximal end  96 . A guide tube  100  is slidable received through a central channel formed in hub  98 , shown in greater detail below. As shown in the embodiment of  FIG. 9 , guide tube  100  has a first, rectilinear segment  102  extending from hub  98  and a second curved segment  104  integral with segment  102 . 
     Referring now to  FIG. 10  handle  92  is shown having a left handle grip  106  and a right handle grip  108 . Handle  92  also includes a central handle plate  110 . As seen in  FIG. 9 , left handle grip  110  has a proximal end  112  and a distal end  114 . Left handle grip  106  is attached to central handle plate  110  at distal end  114 . 
     In like fashion, right handle grip  108  has a proximal end  116  and a distal end  118 , and is attached to central handle plate  110  at distal end  118 . 
     Preferably, left and right handle grips  106 ,  108  are formed from spring steel segments or segments having a natural spring such that when distal ends  114 ,  118  are attached to central handle plate  110 , left and right handle grips  106 ,  108  bend away and are spaced apart from central handle plate  110 . In other words, proximal ends  112 ,  116  when not gripped extend apart and away from central handle plate  110 . 
     Referring now to  FIG. 11 , central handle plate  110  has a slider plate channel  120  formed therethrough proximate nib  98 . A slider plate  122  is inserted into plate channel  120  and slides axially along channel  120  between the forwardmost and rearmost ends of channel  120 . For the purposes of this description, the direction axially toward tube  100  will be referred to as the forward axial direction and movement axially toward distal end  94  will be referred to as the rearward direction. 
     As seen in  FIG. 11 , a left handle link  124  has two ends, one of which is pivotally attached to slider plate  122 . The remaining end of left handle link  124  is slidably secured to left handle grip  106  as described below. 
     A right handle link  128  having two ends is pivotally secured at one end to slider plate  122  in the same manner as left handle link  124 . 
     Right handle grip  108  has a right handle slider groove  130  formed therein, proximate end  116 . As seen in  FIG. 11 , right handle line  128  is slidably secured at its other end within right hand slider groove  130 . In identical fashion, left handle link  124  is secured within identical formed groove  126  (not shown) formed in left handle grip  106  proximate proximal end  112 . Links  124 ,  128  are mechanically attached such that when left and right handle grips  106 ,  108  are gripped and moved toward central handle plate  110 , slider plate  122  moves in an axially forward direction. 
     Referring now to  FIG. 12 , a schematic lateral elevation of a blade segment  132  is shown. Segment  132  is preferably formed from flat spring type surgical stainless steel. In this preferred embodiment, blade segment  132  has a distal end  134  and a proximal end  136 .  FIG. 13  is a top view of the blade segment  132  of  FIG. 12 . As seen, blade segment  132  has an interior surface  138  and an exterior surface  140 . Interior surface  138  is formed as a flat surface throughout. External surface  140  is formed with a first flat segment  142  integrally formed with a ramp segment  144  which is progressively thicker in dimension than segment  142  until it reaches a maximum thickness at break  146 . Thereafter, surface  140  tapers along segment  148  to proximal end  136 . 
     Referring again to  FIG. 12 , distal end  136  is shown having a depending blade  150 , depending from segment  148  at approximately a 90 degree angle. Blade  150  has a lead surface  152  which, in this preferred embodiment, is machined to be smooth and curved. 
     Blade  150  terminates in a bottom  154  which is also smooth and rounded. Blade  150  has a cutting edge  156  formed along a portion of trailing surface  158 . In the embodiment shown, cutting edge  156  is shown by the intersection of angled surfaces  160 ,  162  which, in a preferred embodiment, meet at an angle of 90 degrees. 
     Segments  144 ,  146 ,  148  and  150  constitute left tip  162 . 
     In this preferred embodiment, a right blade segment  164  is formed as a mirror image of left segment  132  and has a right inner surface  166 . When assembled, left and right inner surfaces  138 ,  166  are in face-to-face contact along their respective lengths as described hereinafter. 
     Referring now to  FIG. 14 , a portion of guide tube  66  is shown with left and right blade segments  132 ,  164  slidably inserted therein. As shown in  FIG. 14 , the entire length of segment  132  is within tube  66 . Protruding from tube end  168  is tip  162 , including ramp segment  144 , break  146 , segment  148  and blade  150  of left blade segment  132 . In similar fashion, segment  164  has a corresponding ramp segment  172 , a corresponding break  174 , a corresponding segment  176 , and a corresponding blade  178  which collectively form right tip  180 . It is to be understood that a right blade segment  170  corresponding to left blade segment  142  is also inserted within tube  66  in face to face contact with left segment  142 . 
     Referring now to  FIG. 15 , an enlarged view of end  168  of tube  100  is shown with left and right lead surfaces  152 ,  178 , left cutting edge  156  and a corresponding right cutting edge  182 , a portion of right inner surface  166  and left and right ramps  144 ,  172 . 
     In this preferred embodiment, left and right blade segments  132 ,  164  are secured to handle plate  110  and are held stationary with respect to instrument  90 . 
     Referring now to  FIG. 16 , a portion of guide tube  100  is shown with guide tube  100  in its extended position as left and right handle segments  106 ,  110  are compressed to move slider plate  122  in an axially forward position. As shown in greater detail in  FIG. 17 , when left and right ramps  144 ,  172  contact guide tube  100 , as slider plate  122  is being moved forward, left tip  162  is moved toward right tip  180  until inner surfaces  138 ,  166  are in contact along the entire length of blade segments  132 ,  164 . When this occurs, left and right cutting edges  156 ,  182  are juxtaposed along their entire lengths to form, effectively a single cutting blade  192  as shown in  FIG. 17 . 
     Referring now to  FIG. 18  a partial sectional schematic view of a preferred embodiment showing slider block  122  is shown. Hub  96  has a centrally positioned axial tube guide channel  194  formed therethrough. Slider block  122  has a central, axially extending tube mounting aperture  196  formed therethrough. within which guide tube  100  is received and gripped after it has been passed though aperture  194 . Left and right spring steel segments  132 ,  164  are positioned within guide tube  100  and, because they are attached to handle plate  110  do not move when slider block  122  is moved in slot  120  to move guide tube  100  into or out of hub  96 . 
     As seen in  FIGS. 16 and 17 , with left and right handle grips  106 ,  108 , compressed, instrument  90  may be used as a chopper by positioning blade  192  at a far end of the lens and drawing it across the lens to form a groove. After the groove is formed, blade  192  is positioned within the groove and the pressure on handle grips  106 ,  108  is controllably released to allow blade segments  132 ,  164  to again extend from guide tube  100  thereby separating tips  162 ,  180 . When this occurs, surface segments  144 ,  146 ,  148  and  150  of left segment  132  and corresponding surfaces  172 ,  174 ,  176  and  178  of right segment  164  contact side walls of the groove and force the groove to widen. In this embodiment, the actions of chopping and “cracking” are repeated until the lens has separated into distinct segments. 
     When blade  192  is formed, it may also be used to manipulate and maneuver the lens into a position where a second cut may be made. 
     Thus, the procedures of chopping and cracking are accomplished through the use of a single instrument which, when inserted into the eye capsule, need not be removed until the chopping and splitting procedures have been completed. Once completed, the phacoemulsification instrument may be inserted and the chopped segments may be emulsified and aspirated in less time, using less energy than would be possible if the lens were not to be cracked.