Abstract:
A phacoemulsification tip is formed from a tube that encloses an aspiration lumen surrounded by and generally concentric with a structure section. The structure section has a plurality of structures (ridges, vanes, ribs, or fins). The plurality of structures project inward from an inner wall of the tube at the distal end of the tube. The plurality of the structures are disposed at an angle with respect to a face of the distal end of the tube. Alternatively, the plurality of the structures are disposed at a non-perpendicular angle with respect to a plane that is tangent to a curved outer surface of the tube.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to the field of phacoemulsification and more particularly to phacoemulsification cutting tips. 
     The human eye in its simplest terms functions to provide vision by transmitting light through a clear outer portion called the cornea, and focusing the image by way of the lens onto the 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 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 IOL. 
     In the United States, the majority of cataractous lenses are removed by a surgical technique called phacoemulsification. During this procedure, a thin phacoemulsification cutting tip is inserted into the diseased lens and vibrated ultrasonically. The vibrating cutting tip liquefies or emulsifies the lens so that the lens may be aspirated out of the eye. The diseased lens, once removed, is replaced by an artificial lens. 
     A typical ultrasonic surgical device suitable for ophthalmic procedures consists of an ultrasonically driven handpiece, an attached cutting tip, and irrigating sleeve and an electronic control console. The handpiece assembly is attached to the control console by an electric cable and flexible tubings. Through the electric cable, the console varies the power level transmitted by the handpiece to the attached cutting tip and the flexible tubings supply irrigation fluid to and draw aspiration fluid from the eye through the handpiece assembly. 
     The operative part of the handpiece 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 tip during phacoemulsification and are controlled by the console. The crystal/horn assembly is suspended within the hollow body or shell of the handpiece by flexible mountings. The handpiece body terminates in a reduced diameter portion or nosecone at the body&#39;s distal end. The nosecone is externally threaded to accept the irrigation sleeve. 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 tip is adjusted so that the tip projects only a predetermined amount past the open end of the irrigating sleeve. 
     In use, the ends of the cutting tip and irrigating sleeve are inserted into a small incision of predetermined width in the cornea or sclera. The cutting tip is ultrasonically vibrated along its longitudinal axis within the irrigating sleeve by the crystal-driven ultrasonic horn, thereby emulsifying the selected tissue in situ. The hollow bore of the cutting tip communicates with the bore in the horn that in turn communicates with the aspiration line from the handpiece to the console. A reduced pressure or vacuum source in the console draws or aspirates the emulsified tissue from the eye through the open end of the cutting tip, the cutting tip and horn bores and the aspiration line and into a collection device. The aspiration of emulsified tissue is aided by a saline flushing solution or irrigant that is injected into the surgical site through the small annular gap between the inside surface of the irrigating sleeve and the cutting tip. 
     In one phacoemulsification procedure the horn is driven to produce oscillatory or rotational movement at the tip. Driving the tip in a torsional motion produces more effective cutting and less repulsion of lens material. Torsional tip motion also lends itself to improved tip designs. One such design is described herein. 
     SUMMARY OF THE INVENTION 
     In one embodiment of the present invention, a phacoemulsification tip comprises a tube having a generally circular cross section and a distal end. The distal end has an opening. The tube encloses an aspiration lumen surrounded by and generally concentric with a structure section. The structure section comprises a plurality of structures selected from the group consisting of ridges, vanes, ribs, and fins. The plurality of structures project inward from an inner wall of the tube at the distal end of the tube. The plurality of the structures are oriented at an angle with respect to a face of the distal end of the tube. 
     In another embodiment of the present invention, a phacoemulsification tip comprises a tube having a generally circular cross section and a distal end. The distal end has an opening. The tube encloses an aspiration lumen surrounded by and generally concentric with a structure section. The structure section comprises a plurality of structures selected from the group consisting of ridges, vanes, ribs, and fins. The plurality of structures project inward from an inner wall of the tube at the distal end of the tube. The plurality of the structures are disposed at a non-perpendicular angle with respect to a plane that is tangent to a curved outer surface of the tube. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts the operative portion of an ultrasonic hand piece. 
         FIG. 2  is a perspective view of the end of a cutting tip according to the principles of the present invention. 
         FIG. 3  is an end view of a cutting tip according to the principles of the present invention. 
         FIG. 4  is an end view of a cutting tip according to the principles of the present invention. 
         FIG. 5  is an unrolled view of a cutting tip according to the principles of the present invention. 
         FIG. 6  is an unrolled view of a cutting tip according to the principles of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     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. 
       FIG. 1  depicts an ultrasonic hand piece. In  FIG. 1 , hand piece  100  is coupled to console  140 . Console  140  is coupled to foot switch  150 . Hand piece  100  has a cutting tip  110 , a horn  120 , and a set of piezoelectric crystals  130 . A tip interface  115  connects cutting tip  110  to a reduced diameter portion  125  of horn  120 . 
     Tip  110  is typically a thin needle made of titanium or stainless steel that is designed to emulsify a lens when vibrated ultrasonically. Tip  110  is typically cylindrical in shape, has a small diameter of about 20-30 gauge, and has a length suitable for removal of a lens when inserted into the anterior chamber of the eye. 
     Horn  120  is typically made of a rigid material suitable for medical use (such as a titanium alloy). Horn  120  has a reduced diameter section  125  that is connected to a tip interface  115 . Tip interface  115  typically has a threaded connection that accepts tip  110 . In this manner tip  110  is screwed onto horn  120  at tip interface  115 . This provides a rigid connection between tip  110  and horn  120  so that vibration can be transmitted from horn  120  to tip  110 . 
     Piezoelectric crystals  130  supply ultrasonic vibrations that drive both the horn  120  and the attached cutting tip  110  during phacoemulsification. Piezoelectric crystals  130  are affixed to horn  120 . Crystals  130  are typically ring shaped, resembling a hollow cylinder and constructed from a plurality of crystal segments. When excited by a signal from console  140 , crystals  130  resonate, producing vibration in horn  120 . 
     Console  140  includes a signal generator that produces a signal to drive piezoelectric crystals  130 . Console  140  has a suitable microprocessor, micro-controller, computer, or digital logic controller to control the signal generator. In operation, console  140  produces a signal that drives piezoelectric crystals  130 . Piezoelectric crystals  130 , when excited, cause horn  120  to vibrate. Tip  110 , connected to horn  120 , also vibrates. When tip  110  is inserted into the anterior chamber of the eye and vibrated, it acts to emulsify a cataractous lens. 
       FIG. 2  is a perspective view of the end of a cutting tip according to the principles of the present invention. The end of cutting tip  205  is generally cylindrical with a section  210  that contains ridges, ribs, vanes, fins, or the like (hereinafter referred to as “structure” or “structures”) and a section  215  that forms an aspiration lumen. In this manner, a central aspiration lumen section  215  is surrounded by and concentric with a section  210  that contains the structures. Lens material is cut by tip  205  when it is ultrasonically vibrated and aspirated through aspiration lumen section  215 . The presence of structures in section  210  assists to improve cutting and/or improve the removal of lens material as better described below. A front face of tip  205  lies in a plane that is coplanar with the shaded region ( 210 ) of  FIG. 2 . The bold arrow shows the direction of aspiration or removal of lens material through the tip. 
       FIG. 3  is an end view of a cutting tip according to the principles of the present invention. In this view, aspiration lumen  315  is surrounded by structures  320  that protrude from the interior surface of cutting tip  310 . Cutting tip  310 , as previously noted, is generally cylindrical in shape and has a generally circular cross section as depicted in  FIG. 3 . The wall of cutting tip  310  has thickness that yields a suitably rigid tube to which the structures  320  are attached. In the embodiment of  FIG. 3 , the structures  320  are generally perpendicular to a tangent line drawn on the circular cross section of cutting tip  310 . They are also evenly spaced. In other embodiments, the structure  320  need not be evenly spaced. 
       FIG. 4  is an end view of a cutting tip according to the principles of the present invention. In this view, aspiration lumen  415  is surrounded by structures  420  that protrude from the interior surface of cutting tip  410 . Cutting tip  410 , as previously noted, is generally cylindrical in shape and has a generally circular cross section as depicted in  FIG. 4 . The wall of cutting tip  410  has thickness that yields a suitably rigid tube to which the structures  420  are attached. In the embodiment of  FIG. 4 , the structures  420  are not perpendicular to a tangent line drawn on the circular cross section of cutting tip  410 . In this manner, the angle of the structure  420  can vary with respect to a tangent line drawn on the circular cross section of cutting tip  410 . This angle can be adjusted to optimize the cutting properties of tip  410 . In addition, this angle can be adjusted to optimize the manner in which aspirated material is removed from through aspiration lumen  415 . For example, when the structures  420  are oriented as shown in  FIG. 4 , rotation of tip in one direction causes structures  420  to bite into lens material, more effectively cutting it. When rotated in the opposite direction, cutting action is lessened and aspiration may be improved. 
       FIG. 5  is an unrolled view of a cutting tip according to the principles of the present invention. In this view, the generally cylindrical tip is unrolled to expose the orientation of the structures  520 . Generally, the structures  520  are oriented at an angle with respect to a face  540  of the distal end of the tip. The face  540  of the tip is located at the distal end of the tip. The structures  520  are oriented at an angle of x degrees with respect to the face  540  of the cutting tip. This angle is preferably between about five and 85 degrees. In this embodiment, the structures  520  are generally linear. When rotated in one direction, the structures  540  act to enhance cutting as the angle x causes the structures to bite into the lens material. When rotated in the opposite direction, the structures  540  act to reduce cutting action as the angle x causes the structures to assist in aspiration of the lens material. Additionally, the structures  520  may be generally perpendicular to the inner wall of the tip as shown in  FIG. 3 , or they may be oriented at an angle as shown in  FIG. 4  (resulting in structures  520  being oriented at a compound angle with respect to the inner wall of the tip). The bold arrow shows the direction of aspiration or removal of lens material through the tip. 
       FIG. 6  is an unrolled view of a cutting tip according to the principles of the present invention. In this view, the generally cylindrical tip is unrolled to expose the orientation of the structure  620 . Generally, the structures  620  are oriented at an angle with respect to the face  640  of the distal end of the tip. The structures  620  are oriented at an angle of y degrees with respect to the face  640  of the cutting tip. This angle is preferably between about five and 85 degrees. In this embodiment, the structures  620  are not linear—instead having a curved or spiral shape. Additionally, the structures  620  may be generally perpendicular to the inner wall of the tip as shown in  FIG. 3 , or they may be oriented at an angle as shown in  FIG. 4  (resulting in structures  620  being oriented at a compound angle with respect to the inner wall of the tip). The bold arrow shows the direction of aspiration or removal of lens material through the tip. 
     When the tips of  FIGS. 2-6  are coupled to a phacoemulsification hand piece that produces torsional or oscillatory movement at the tip, the structures are oriented such that they enhance the cutting action when rotated in one direction and enhance the removal of lens material (or assist aspiration) when rotated in the other direction. In this manner, the structures can act much like the cutting surfaces of a drill bit. The structures are also more effective at reducing occlusions—i.e. a blockage of the aspiration lumen that results in an increase in aspiration pressure. Further, the faces or edges of the structures may be sharpened or serrated to promote cutting of the lens material. They may also be rounded or blunt to promote removal of lens material. In another example, the front face or edge may be sharpened to promote cutting when the tip is rotated in one direction, and the back face or edge may be blunt or rounded to promote removal when the tip is rotated in the opposite direction. 
     From the above, it may be appreciated that the present invention provides an improved phacoemulsification tip useful for the removal of a cataractous lens. In the present invention, the cutting tip is has a plurality of internal oriented structures. These structures facilitate cutting and/or removal of lens material. 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.