Abstract:
A phacoemulsification tip having an arched or curved shaft. Such a feature serves to produce more efficient cutting during torsional vibration of the tip while maintaining a greater space between the distal end of the tip and the posterior capsule.

Description:
BACKGOUND OF THE INVENTION  
       [0001]     This invention relates generally to the field of phacoemulsification and more particularly to torsional phacoemulsification cutting tips.  
         [0002]     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.  
         [0003]     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.  
         [0004]     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 liquifies 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.  
         [0005]     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.  
         [0006]     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. Ultrasonic handpieces and cutting tips are more fully described in U.S. Pat. Nos. 3,589,363; 4,223,676; 4,246,902; 4,493,694; 4,515,583; 4,589,415; 4,609,368; 4,869,715; 4,922,902; 4,989,583; 5,154,694 and 5,359,996, the entire contents of which are incorporated herein by reference.  
         [0007]     In use, the ends of the cutting tip and irrigating sleeve are inserted into a small incision of predetermined width in the cornea, sclera, or other location. 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.  
         [0008]     One phacoemulsification tip that has gained widespread acceptance has a belled or flared distal end. Such a tip is described in U.S. Pat. No. 4,816,018 (Parisi). Such a design allows for larger lens material purchase as well as increased holding force when vacuum is applied to the tip while maintaining a smaller bore in the shaft of the tip. This combination of features increases anterior chamber stability, by reducing sudden outflow from the anterior chamber when the distal end becomes occluded and this occlusion breaks.  
         [0009]     Another phacoemulsification tip is an angled or “bent” tip with or without a flared distal end. These tips are described in U.S. Pat. No. 6,039,715 (Mackool), U.S. Pat. No. 5,653,724 (Imonti) and U.S. Pat. No. 5,154,694 (Kelman). These tips have a predominantly straight shaft with the far distal portion of the shaft being bent on an angle. Bent tips are used by a great many surgeons, and are particularly useful when used in conjunction with a oscillatory phacoemulsification handpiece, such as those described in U.S. Pat. No. 6,352,519 (Anis, et al.) and U.S. Pat. No. 6,602,193 (Chon) and commercially available as the NeoSoniX® handpiece from Alcon Laboratories, Inc., Fort Worth, Tex., however; some surgeons are reluctant they feel that due to the proximal location of the bend it is more difficult to judge the position of the proximal cutting edge based on the extrapolation of the sleeved portion of the tip.  
         [0010]     The inventors have discovered that angled phacoemulsification tip are particularly advantageous when used in combination with torsional ultrasound handpiece. Torsional ultrasound handpieces are more fully disclosed in U.S. Pat. No. 6,077,285 (Boukhny). Therefore, a need continues to exist for an angled phacoemulsification tip that is safer to use near the posterior capsule.  
       BRIEF SUMMARY OF THE INVENTION  
       [0011]     The present invention improves upon the prior art by providing a phacoemulsification tip having an arched or curved shaft. Such a feature serves to produce more efficient cutting during torsional vibration of the tip while maintaining a greater space between the distal end of the tip and the posterior capsule.  
         [0012]     Accordingly, one objective of the present invention is to provide a phacoemulsification cutting tip having increased efficiency, particularly during torsional ultrasound movement.  
         [0013]     Another objective of the present invention is to provide a phacoemulsification cutting tip having a curved shaft.  
         [0014]     These and other advantages and objectives of the present invention will become apparent from the detailed description and claims that follow. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is a perspective view of the distal end of a typical prior art straight shaft phacoemulsification tip.  
         [0016]      FIG. 2  is an elevational view the distal end of a typical prior art angled or bent phacoemulsification tip.  
         [0017]      FIG. 3  is an elevational view the distal end of the phacoemulsification tip of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]     As best seen in  FIG. 1 , prior art phacoemulsification tip  10  contains shaft  12  that is straight all the way to distal tip  14 . As best seen in  FIG. 2 , prior art phacoemulsification tip  100  contains shaft  112  that is straight up to distal end  113 . Distal end  113  is angled or bent on an angle relative to centerline  115  of shaft  112  from intersection  117  of shaft  112  and distal end  113  all the way to distal tip  114 .  
         [0019]     The inventor has discovered that ultrasonic vibration of tip  1   10  causes a twisting of shaft  112  that is not present if tip  110  is rotarily oscillated. Such twisting causes distal tip  114  to assume a whipping motion which although less that the rotary motion generated in distal tip  114  when tip  110  is rotarily oscillated, the whipping motion greatly increases the cutting efficiency of tip  110 . As discussed above, lateral displacement L 1  of distal tip  114  from longitudinal centerline  115  of shaft  112  can place distal tip  114  near the posterior capsule during surgery, and the exact location of distal tip  114  can be difficult to determine. As a result, some surgeons prefer not to use a phacoemulsification tip of the design shown in  FIG. 2 .  
         [0020]     As best seen in  FIG. 3 , phacoemulsification tip  210  of the present invention contains shaft  212  that is not straight but instead is bent on a slight arch along the entire length of shaft  112 . So constructed, lateral displacement L 2  of distal tip  214  from reference line  215  is less than lateral displacement L 1  of distal tip  114  from centerline  115 . Such a construction makes it easier for the surgeon to locate distal tip  214  and maintain a more comfortable distance from the posterior capsule during use, but still benefits from the increase cutting efficiency discussed above.  
         [0021]     Cutting tip  210  is preferably made from stainless steel or titanium, but other materials may also be used. Cutting tip  210  preferably has an overall length of between 0.50 inches and 1.50 inches, with 1.20 inches being most preferred. Cutting tip  210  may be formed using conventional metalworking technology and preferably is electropolished to remove any burrs.  
         [0022]     Shaft  212  is generally tubular, with an outside diameter of between 0.005 inches and 0.100 inches and an inside diameter of between 0.001 inches and 0.090 inches. Distal end  214  of shaft  212  may be cut square or cut at any suitable angle between 0° and 90°.  
         [0023]     This description is given for purposes of illustration and explanation. It will be apparent to those skilled in the relevant art that changes and modifications may be made to the invention described above without departing from its scope or spirit.