Abstract:
This apparatus is a device for removal of cataracts from the eyes of patient. The apparatus includes a hand piece, with an irrigation water line, a vacuum line and a power line provided therein, are all connected with the hand piece. Within the hand piece the vacuum line is attached to a tube, identified as the horn, concentric with the outer shell of the hand piece. Through a hooks and slider joint, bayonet type or threaded joint in the front end, the horn connects with a surgical needle. At the front end of the irrigation tube it discharges water into a chamber, which irrigation water passes between the needle and an outer sleeve and into the anterior chamber of the eye. Ultrasonic waves transmitted to the horn are conveyed to the tip of the needle where the axial vibrations of the tip may be used to comminute cataract material.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This continuation-in-part application for patent claims priority to the non-provisional patent application having Ser. No. 11/656,869, which was filed Jan. 22, 2007, now abandoned, which claims priority to the provisional patent application having Ser. No. 60/855,278, which was filed on Oct. 30, 2006. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to a needle-horn configuration which significantly reduces the heat generated in the needle. Available needles may become hot enough to damage the cornea tissue on the incision through which the needle penetrates into the anterior chamber of the eye. 
     To date there is a significant number of needles with different characteristics. A careful analysis of their similarities and differences would show that their effect on the needle performances is minimal. Some have smooth surfaces and some striated surfaces. Some have left handed threads and others have right handed threads. To minimize the size of the incision some needles have smaller diameters than others. The configurations of the tips themselves may also vary from needle to needle, but none of the available needles have tips which are hydrodynamically significantly better than the others. In other words, their suction power is roughly the same and relatively low. 
     All needles analyzed to date use the same type of attachment: horn with internal thread and needle with external thread. It is the main, and extremely important, technical advantage of our invention that we exchange the positions of the threads in the horn and in the needle. In one of the embodiments the needle has the internal thread while the horn has the external thread. With this arrangement the ultrasound waves may travel in an almost continuous and uniform path from the transducer to the tip of the needle. Furthermore, our design includes an element that it is not used by any other needle. Presently available needles establish direct contact between the horn&#39;s vertical front end surface and the mating vertical surface of the needle hub. Both the horn and the needle are made of titanium alloy (Ti-6Al-4V) in a relatively hard condition. It would be technically impossible that both surfaces were perfectly planar and parallel using the technology used at present. The areas of contact would be a small percent of the total area. The ultrasound waves would be reflected back by the contact free areas of the horn. Because of the needle hub geometries in use today, even those waves that cross the areas of contact would be subjected to multiple reflections within the hub with the consequent generation of significant amounts of heat and increasing temperatures in the hub and needle. 
     The problems described in the previous paragraph are eliminated in our invention. The interface problem is eliminated by placing a 0.005″ thick washer of annealed and magnetized pure nickel. Such a washer could be in a range of about 0.002″ to 0.050″ in thickness. The washer has the same internal diameter as both the horn and the needle. The outside diameter of the washer is equal to the outside diameter of the horn front surface. When the needle and the horn are tightened together the applied torque will generate enough pressure on the washer that it will deform completely filling the space between the end surfaces of the horn and the needle hub. Two positive effects will take place due to the tightening of the needle-horn joint. The gaps resulting from the machining irregularities will be eliminated and, because Ni has an ultrasound speed very close to that of Ti-6Al-4V, a large percentage of the arriving waves will go through the interface with minimum losses and great reduction in heat generation. 
     SUMMARY OF THE INVENTION 
     This invention addresses three operational needs resulting from the inadequate design of all present surgical needles used in the removal of cataracts. The attachment of the needle to the horn created a tortuous path for the ultrasonic waves to travel from the transducer to the tip of the needle. Furthermore, the interface between the horn front end and the mating face at the needle hub resulted in a very inefficient transmission of waves from the horn to the needle. Lastly, the designs of the tips of the needles are so simple minded and inefficient that the removal of cataract debris is difficult, resulting in longer operating times than necessary. 
     The inefficient transmission of the ultrasonic waves also has a tendency to cause a build up of energy that generates heat in the needle, at its juncture with the horn, which can cause a hazard to the ophthalmologist and other technicians handling of this apparatus during usage, and actually interfere with their efficient performance during a cataract operation. 
     To address the previously described shortcomings three main improvements were added to this invention: 1) In the basic embodiment referred to as “threadlock needle”, the threaded ends of the horn and the needle were exchanged in comparison with presently used surgical needles, as shown in  FIG. 1 ; the external threads of the joint are now in the front end of the horn while the internal thread is on the rear end of the needle. As a result the ultrasonic wave path is free of heat promoting interferences. 2) In the “twistlock” preferred embodiment the threaded joint is replaced entirely by a bayonet type joint that completely eliminates all barriers to the advance of the ultrasonic waves. 3) In a second preferred embodiment the threaded joint is replaced entirely by a different approach where the horn is, basically, a smooth hollow cylinder with a built in retaining ring locked to the needle by a group of hooks actuated by a sliding ring. The front end of the horn is pressed against the Ni washer and the matching surface on the rear of the needle. 4) The addition of a magnetized and annealed Ni washer at the interface between the horn front face and the needle back face will allow the transmission of a much higher percent of the ultrasound waves than is possible with present needles and horns. The sound speed in Ti and Ni (magnetized) are very close: 6070 m/s and 6040 m/s respectively. 5) The use of a Venturi nozzle at the tip of the needle will increase the dragging force of the suction water at the tip of the needle by as much as a factor of twenty. 
     It is, therefore, the principal object of this invention, to provide a path to the ultrasound waves such that they can travel from the transducer to the tip of the needle with minimum energy dissipation. 
     Another object of this invention is to reduce the heating of the needle below temperatures which may otherwise damage cornea tissue. 
     A further object of this invention is to reduce the ultrasound power required to operate the needle without overheating but without losing the attrition power of the needle tip. 
     Another object of this invention is to incorporate at the tip of the needle a Venturi type nozzle to increase substantially the suction power of the needle tip. 
     Still another object of this invention is to, eventually, replace the present silicon elastomer irrigation sleeve with a Ti one. 
     Another object of this invention is to incorporate in the fabrication of the needles methods such as “diffusion bonding” and “super-plastic forming” widely used in the aero space vehicle fabrication using Ti, and Ti alloys, with more flexibility and control than those methods used today to fabricate the needles. 
     Other objects of this invention may become more apparent to those skilled in the art upon review of the Summary of the Invention as provided herein, and upon undertaking a study of the description of its preferred embodiments, in view of the drawings. 
     The invention relates to devices that are used to remove cataracts from the eyes of patients. These devices are designed in such a fashion that several, and different, functions are, typically, integrated within the body of a single hand-piece. On the back end of the hand-piece the irrigation water line, the vacuum suction line and the power line, are connected to the hand-piece. Within the hand-piece the vacuum line is attached to a tube, called the “horn”, concentric with the outer shell of the hand-piece and connected, as in our first embodiment, through a threaded joint in the front end, to a surgical needle. The irrigation line is connected, in some embodiments, on the back side of the hand-piece to a rigid tube which follows the external contour of the hand-piece. In the front end the irrigation tube discharges the water into a chamber which, itself, discharges the irrigation water into an annular space defined by the surgical needle on the inside boundary and an a molded elastomer or metallic sleeve on the outside boundary. The back end of the sleeve is attached to a coupling integral with the front end of the hand-piece; the front end of the sleeve rests tightly around the tip of the needle. One or more holes are placed towards the end of the sleeve so the irrigation water may be delivered into the anterior chamber of the eye close to the needle tip but in a direction away from the tip. As already mentioned, the vacuum line is attached to the rear end of the horn thereby allowing the water and cataract fragments in the anterior chamber of the eye to be suctioned away from the chamber. To improve the suction power of the needle the tip will take the shape of a Venturi nozzle. The heart of the whole system is the needle, which in its original design (designated “threadlock needle”) is attached to the forward end of the horn through an external thread in the horn and an internal thread in the needle. Alternatively, in the first preferred embodiment (designated “twistlock needle”) the threaded joint is replaced by a bayonet type joint and, in the second preferred embodiment (designated “slidelock needle”) the joint is made up of a set of hooks actuated by a sliding ring that pushes the hooks inwards towards the locking ring in the horn; thereby preventing the separation of the needle from the horn and, simultaneously, exerting a very strong force on the washer and the needle. Finally, the power line carries high frequency electrical signals to an ultrasonic transducer concentric and in contact with the horn. The ultrasonic waves transmitted to the horn are conveyed to the tip of the needle where the axial vibrations of the tip may be used to comminute cataract material. In summary, the complete system consists of these few elements and functions: an irrigation tube that controls the supply of water to the needle/sleeve system, a flexible sleeve that carries the irrigation water to the anterior chamber of the eye through holes on the tip of the sleeve, an anterior chamber between the cornea and the crystalline lens, and a posterior chamber between the iris and the lens. The tip of the needle suctions the liquid in the anterior chamber as a result of the vacuum applied on the back end of the hand-piece and transmitted through the inner tube of the horn. Also, and very critical, is the transmission of ultrasound waves (US waves) from the transducer to the tip of the needle. All present needle designs, under certain power and cycle conditions, generate a great deal of heat due to the inadequate design of the ultrasound wave path. By having the horn end with an internal thread and the needle with a matching external thread the sound waves are forced to follow a tortuous path with multiple reflections and, consequently, large generation of heat. In some instances cornea tissue in contact with the needle has been damaged by said heat. Our patent, in particular in a possible embodiment, is based on providing a smooth path for the ultrasound waves by having the external thread on the horn and the internal one on the needle. In two preferred embodiments of this patent the threads are either replaced by a bayonet type joint (twistlock) or by an array of hooks actuated by a sliding ring (slidelock), that completely eliminates any possible barriers to the US waves but for the unavoidable direct contact between the horn/washer/needle hub interfaces. The latter should pose only a minor perturbation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In referring to the drawings,  FIGS. 1A-C  show three variations upon prior art needle-horn configurations; 
         FIG. 2  shows prior art attachment between the horn and needle as currently used by the professionals; 
         FIG. 3  shows an embodiment of the current invention with a threadlock device where external threads on the front of the horn and the internal threads provided on the hub furnish interconnection between the two with minimum interference; 
         FIG. 4  discloses a modified embodiment of the apparatus with a twistlock device to attach the horn to the needle; 
         FIG. 5  provides a partial view of the horn and needle apparatus with a twistlock or bayonet mechanism for locking the two together; 
         FIG. 6  is a back view of the needle as shown in  FIG. 5  and including torqueing flats; 
         FIG. 7  shows the interconnection between the horn and the neede is a bayonet type of lock, as noted at  27  and  28 ; 
         FIG. 8  shows the slidelock embodiment with the locking slider in the retracted position and the hooks in the open position; 
         FIG. 9  shows the slidelock embodiment with the locking slider in the operational position and the hooks attached to the horn ring; 
         FIG. 10  shows the slidelock embodiment locked into position holding the needle to the horn; 
         FIG. 11  discloses the interference caused in the transmission of the ultrasonic waves from the horn and into the needle when the prior art and standard type of interconnection is formed having air gaps between these components, and which wave interference and its congestion, as noted, generates a significant amount of heat at this juncture; 
         FIG. 12  shows how the current invention routinely passes the ultrasonic waves from the horn and into the needle and forwardly thereof to its tip for use in the effective fracture of cataracts during an operation, all without the generation of any noticeable heat; and 
         FIG. 13  shows the location of the nickel washer which occupies all space between the front of the horn, and the interior back shoulder of the hub. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In reference to the drawings, and in particular  FIGS. 3 ,  4 ,  5 ,  6 ,  7 ,  8  and  9  the preferred embodiments are shown. In these preferred embodiments the complete elimination of barriers to the advance of ultrasonic waves has been achieved. 
     The foreseeable success of the preferred embodiments is due to a remarkable simplification of its design resulting in almost complete elimination of all spurious interferences to the advance of the ultrasonic waves from transducer to nozzle. 
     In the twistlock embodiment shown in  FIGS. 4 ,  5  and  6 , the locking pins in the horn are press fitted to the horn and made of the same alloy as the horn and the needle, hence, they cannot pose any problem to the advance of the ultrasonic waves. 
     In the slidelock embodiment shown in  FIG. 7  the hooks are in the open position and the sliding ring is pressed forward against the hub flange. See also  FIG. 8 . In  FIG. 9  the slider ring is shown in contact with the stops on the tips of the hooks while themselves are pressed by the ring against the edge of the horn ring producing a significant force between the horn, the washer and the needle. 
     The path of the ultrasonic waves from transducer to needle tip is now free of obstacles. Furthermore, compared with the nozzles of all previous needles, the Venturi can produce suction forces in an order of magnitude higher than those obtained with the simple apertures used at the tips of all previous needles. 
     Summarizing, the preferred embodiments of this invention have been simplified to an extreme such that: 
     a) The sources of uncontrolled heat have been completely eliminated by providing for the ultrasonic waves a path free of any obstacles from the transducer to the tip of the needle. 
     b) The geometry of the needle has been greatly streamlined, hence, the flow of ultrasonic waves and suction water will not be hindered by obstacles that may result in losses due to heat generation and/or cavitation. 
     c) The attachment of the needle to the horn has been simplified in its operation and fabrication. 
     d) From the medical point of view some advantages are evident:
         The superior suction ability of this invention will make it easier to remove cataract debris.   The durations of the operations can, therefore, be shortened.   The danger of cornea damage can be completely suppressed.       

       FIGS. 1A-C  show three variations of needles which are in use today. They do not differ much from each other. Needle  1 A exhibits a relatively large suction tube without any attempt to implement some kind of nozzle. Needle  1 B exhibits also a large diameter suction tube but half way to the threaded end introduces a sudden restriction with an exit hole which produces a significant amount of turbulence without increasing the suction power at the tip entrance, where higher suction is necessary. Finally, Needle  1 C is widely used based on the assumption that the longitudinal striations improve the passage of the irrigation water between the sleeve and the metal tube. In practice, this needle does not perform any better than the others, it costs more to produce and requires a longer incision in the cornea. 
       FIG. 2  shows the means of attachment between the horn  11  and the needle  12  that is used by the great majority, if not all, of the brands and eye surgeons. When the ultrasonic waves, at velocities over 500 m/s, reach the threaded joint they are subjected to multiple reflections at the threads, at the contact surface  13  between horn and needle hub, and, also, inside the hub  1  of the needle where they are reflected at the walls of the hub, and interfered by other strayed waves. 
     As can be seen in  FIG. 11 , where the horn thread engages onto the back end of the needle, and abuts against the shoulder of the needle, the transmission of the ultrasonic waves through the horn, and into the needle, becomes obstructed, because of the abutting surfaces provided, causing the ultrasonic waves to congest at the smaller tapered section of the needle as noted, where heat of significant proportions can be generated to the detriment of usage of this particular prior art apparatus. It has been determined that as many as seventy percent of the generated ultrasonic waves, being transmitted, can be reflected back, which causes that shown congestion and the generation of heat within the prior art style of needle. 
       FIG. 3  shows an embodiment of this invention where the external thread is machined on the front end of the horn and the internal thread is machined in the hub of the needle. One can easily see that the waves coming in the horn from the left could continue through the interface  15 , washer  13 , threads  16  and modified hub  14  to the tip of the needle with a minimum of interference from the threads. 
       FIG. 4  shows a second and preferred embodiment of the approach shown in  FIG. 3 . In this case the thread is completely eliminated and replace by a bayonet type, twistlock engagement  19 , washer  17 , and hub  18 . This embodiment represent just about the optimum solution to the problem of perturbations to the motions of the ultrasonic waves. 
       FIG. 5  shows more complete details of the twistlock style of lock, as at  19 , with the suction tube  20  provided within the needle, and the rear end of the needle including the identified Ni washer  17 . Reference  22  shows the needle itself, with the suction tube extending therethrough, and  23  discloses a uniquely shaped Venturi, at the front nozzle, effectively increasing the dragging force of the water at the tip of the needle, to enhance its operations. Reference  24  shows the smooth end of the horn, and inserted within the bore of the needle and  21  shows the grooves of the bayonet type locking. 
       FIG. 6  shows a backside view of the complete needle where the torqueing flats on the hub  25  and the internal diameters of the suction tube in the horn and part of the hub flange  20  and in the needle itself  22  and the Venturi  23  as shown in  FIG. 5 . The smallest diameter of the Venturi  23  is equal to that of the needle hub  22 . 
       FIGS. 5 and 6  show the embodiment of what can be considered the optimal design of a surgical needle for the removal of cataracts. The virtues of this embodiment of this invention consists in the elimination of problems that plague other designs: uncontrolled heating even at lower ultrasonic power settings, elimination of potential incompatibility between horn and needle by the addition of Ni washer between them and a Venturi type nozzle at the tip. The interface of the needle with the horn consists of two parts. See  FIG. 5 . A cylindrical part  24  and a front part  17  that includes the Ni washer. The suction tube  20  consists of four segments, including the Venturi nozzle  23 , with smooth transition between them guaranteeing the elimination of cavitation, and concomitant pressure losses. In particular  FIG. 5  shows a more detailed sketch of the proposed mechanism to lock the horn and needle hub together,  19  is the locking pin in the horn and  21  is the guiding groove in the hub. This mechanism will eliminate all geometrical interferences, except for the washer, to the advance of the ultrasonic waves from the transducer to the tip of the Venturi. 
       FIGS. 8-10  show details of the mechanism involved in the slidelock joint design. The joint incorporates the use of flexible hooks  27  to attach the needle to the horn. The latter has an integral attachment ring  28  which is an integral part of it. The operation required to engage or disengage the hooks  27  is performed by a sliding ring  29 , on the periphery. When the ring is in contact with the hub flange  33  the hooks are disengaged with the horn. When the ring is slid to the opposite end, the hooks engage the horn ring  28  and press the horn against the washer and the needle. 
     As can be seen in  FIG. 12 , the advantages of providing a hub that engages or interlocks within the back end of the needle can be readily seen. As noted, the horn end  31  engages internally within the back end of the needle, as can be seen at  30 . In this particular embodiment, the integral attachment ring  32  cooperates with the sliding ring  31 , to hold the various hooks  30  in place. The Ni washer  37  locates between the front of the horn, and the internal back end of the needle, as at  32 , to provide a very compatible fit between the two components. Thus, when ultrasonic waves are transmitted through the horn, as noted at w, they are transmitted directly through the washer and into the needle, and encounter little or no obstruction to their continuing flow, as noted at w 1 , towards the front of the needle, where the ultrasonic waves fracture the cataracts for their removal during this operation. 
     As can be seen in  FIG. 13 , the Ni washer  37  occupies all space between the internal shoulder, as at  38 , of the needle  35 , and the washer occupies all space, leaving no air gaps at its interface with the internally threaded horn  34 . Thus, as can be noted, the ultrasonic waves pass directly from the horn into the needle and are not disrupted as a result of the presence of any air gaps, such as occurs in the prior art style of apparatus as shown in the prior art, and as identified and described in  FIG. 11 . 
     Variations or modifications to the subject matter of this invention may occur to those skilled in the art upon review of the development as provided herein. If within the scope of this development, are intended to be encompassed within the invention as described. The depiction of the preferred embodiments, and their disclosure in the drawings, are set forth for illustrative purposes only.