Abstract:
A capsulotomy cutting device includes a planar cutting head sized to fit into intraocular tissue. The planar cutting head includes at least one sharp edge and an oscillation mechanism adapted to oscillate the cutting head. Capsulotomy is achieved by inserting the planar cutting head through an incision in the eyeball, placing the cutting edge of the cutting head against the tissue of the lens capsule therein, and then oscillating the cutting head by an oscillation mechanism coupled to the cutting head.

Description:
RELATED APPLICATIONS 
     The present application claims the benefit under 119(e) of U.S. provisional patent application 60/670,705, filed Apr. 13, 2005, the disclosure of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to eye surgery and particularly to anterior capsulotomy. 
     BACKGROUND OF THE INVENTION 
     The human eye includes a lens enclosed by a transparent capsule. Cataract is a condition characterized by opacity of the lens causing partial or total blindness. Cataracts are treated by removal of the defective lens and replacement with an artificial lens. An initial step of cataract surgery is an anterior capsulotomy, wherein an opening is made in the outer capsule to allow the removal of the defective lens. 
     The most common method of performing a capsulotomy is to rupture the capsule with a needle, in order to create a tear. The surgeon then grasps the free edge of the tear with either forceps or the needle and maneuvers, by manual dexterity, to create an approximately circular opening in the center of the capsule. Performing a capsulotomy with needle and forceps is difficult and the results are neither uniform nor predictable. This non-uniformity of the result is a disadvantage, because the success of the capsulotomy dictates to a large extent the quality and success of the entire cataract operation. 
     In order to access the capsule for the capsulotomy, an opening must be made in the cornea or sclera, which are layers of the eye external to the lens capsule. Fast recovery of the cornea or sclera is aided when the access opening has a minimal size. Therefore, the surgical manipulations of the capsulotomy are generally performed through an access wound in the cornea or sclera, which is expected to be no greater than 3.0 mm in length and 0.1 mm in height. Though the tissue in the cornea and sclera is somewhat distensible, it currently accommodates instruments no greater than 0.75 mm in height. As cataract surgery instrumentation advances, entrance wounds are being made smaller and smaller, in order to shorten the post operative recovery period. 
     U.S. Pat. No. 6,165,190 to Nguyen, the disclosure of which is incorporated herein by reference, describes a capsulectomy device having a needle that rotates up and down radially relative to the eye lens capsule, in order to cut the capsule. The needle is mounted on a rotating arm that controls the radius of the cut in the capsule. The radial rotation of the needle requires space, which may not be easily available in capsulectomy procedures. 
     U.S. Pat. No. 6,551,326 to Van Heugten et al., the disclosure of which is incorporated herein by reference, describes a capsulorrhexis device having a super elastic rod that is entered into the eye and formed into a circular loop with a desired radius. The rod cuts the eye lens capsule when it is retracted from the eye. This device may have problems of accurate operation and mechanical failure. 
     U.S. Pat. No. 6,629,980 to Eibschitz-Tsimhoni, the disclosure of which is incorporated herein by reference, describes an eye lens capsule cutting device having a curvilinear head portion. The force required by a physician in order to cut a hole in the capsule using such a cutting device is large, such that the physician is required to apply a substantial force in an accurate manner, in order to achieve the cutting, without cutting too deep into the eye and damaging the eye. 
     U.S. Pat. No. 6,066,138 to Sheffer et al., the disclosure of which is incorporated herein by reference, describes a medical instrument for burning a lens capsule of an eye. 
     U.S. Pat. No. 5,728,117 to Lash, the disclosure of which is incorporated herein by reference, describes a capsulorrhexis instrument that is retractable within a tube and extendable into a position projecting out of the tube. In the position out of the tube, the instrument has a circular shape with a sharp blade for cutting a hole in the capsule. 
     SUMMARY OF THE INVENTION 
     An aspect of an embodiment of the invention relates to a capsulotomy cutting device having a planar cutting head and a handle adapted to oscillate the cutting head. The term planar cutting head refers herein to a cutting head whose points adapted to come in contact with a surface to be cut are not concentrated around a single point and are not included in a single straight line. The handle optionally oscillates the cutting head along an axis tangent to a plane of the cutting head and hence tangent to the lens capsule. The oscillation optionally is performed in small steps, which achieve the cutting of a planar cut in the lens capsule. The oscillation achieves a relatively smooth cut, which allows a safer and more predictable cut, which can be more accurately controlled and customized by the surgeon. 
     Optionally, the planar cutting head has a convex shape. In some embodiments of the invention, the cutting head has a curvilinear shape. 
     In some embodiments of the invention, the cutting head has sharp edges on two planar sides, such that it can be easily used for cutting both right and left opening curvilinear cuts, by simply turning over the cutting head. Optionally, the cutting head is small enough to allow turning over of the cutting head within the anterior chamber of the patient&#39;s eye. 
     There is therefore provided in accordance with an exemplary embodiment of the invention, a capsulotomy cutting device, comprising a planar cutting head sized to fit into intraocular tissue, including at least one sharp edge and an oscillation mechanism adapted to oscillate the cutting head. 
     Optionally, the at least one sharp edge comprises a pair of edges on opposite surfaces of the cutting head. Optionally, the planar cutting head comprises a convex cutting head. Optionally, the planar cutting head comprises a curvilinear cutting head. Optionally, the cutting head is semicircular. Optionally, the cutting head has a shape of half of an ellipse. Optionally, the sharp edge spans over at least 135°. Optionally, the sharp edge has a diameter of between about 3-9 millimeters. Optionally, the cutting head has a shape adjustable within intraocular tissue. Optionally, the cutting head comprises a super elastic material. Optionally, the oscillation mechanism oscillates at a rate of at least 10 Hz. Optionally, the oscillation mechanism comprises an eccentric motor and/or is driven by a piezoelectric crystal. 
     Optionally, the cutting head is held on a handle and the oscillation mechanism oscillates the cutting head along a longitudinal axis of the handle. Optionally, the cutting device is removably coupled to the oscillation mechanism. Optionally, the at least one sharp edge has a length of more than 1 mm. 
     Optionally, the cutting device includes a removable cover adapted to cover the cutting head and to be removable within intraocular tissue. Optionally, the cutting device includes a pivot coupled to the cutting head, allowing controllable rotation of the cutting head. 
     There is further provided in accordance with an exemplary embodiment of the invention, a method of cutting an incision in internal body tissue, comprising inserting a planar cutting head through an incision in body tissue, placing a cutting edge of the cutting head against tissue, and oscillating the cutting head, by an oscillation mechanism coupled to the cutting head. 
     Optionally, the cutting edge has a larger diameter than the incision through which the cutting head is inserted. Optionally, the cutting edge has a first configuration when it is inserted through the incision and a second configuration when placed against tissue. 
     Optionally, the cutting head is compressed to a thin straight line in the first configuration. Optionally, the cutting edge has a same configuration when inserted through the incision and when placed against tissue. 
    
    
     
       BRIEF DESCRIPTION OF FIGURES 
       Particular non-limiting exemplary embodiments of the invention will be described with reference to the following description of embodiments in conjunction with the figures. Identical structures, elements or parts which appear in more than one figure are preferably labeled with a same or similar number in all the figures in which they appear, in which: 
         FIG. 1  is a cross-sectional view of a capsulotomy cutting device, in accordance with an exemplary embodiment of the invention; 
         FIG. 2  is an enlarged view of a cutting head, in accordance with an exemplary embodiment of the invention; 
         FIGS. 3A-3C  are schematic illustrations of possible relative positions of cuts made by a cutting device, in accordance with an exemplary embodiment of the invention; 
         FIG. 4  is an enlarged cross-sectional view of the capsulotomy cutting device of  FIG. 1  placed against an eye, in accordance with an exemplary embodiment of the invention; and 
         FIG. 5  is a schematic sectional view of a capsulotomy cutting device, in accordance with another exemplary embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       FIG. 1  is a cross-sectional view of a capsulotomy cutting device  100 , in accordance with an exemplary embodiment of the invention. Cutting device  100  includes a cutting head  102  connected through a handle  104  to an oscillation mechanism  108 , which moves cutting head  102  back and forth in an axial direction, defined by the long axis of cutting device  100 , indicated by arrow  110 . The movement of cutting head  102  in direction  110  when placed on tissue achieves a cut in the tissue, in the shape of cutting head  102 . In some embodiments of the invention, a housing  120  serves as a handle of cutting device  100 . In addition, housing  120  optionally hosts batteries  122 , which power oscillation mechanism  108 . A switch, button or any other control (not shown) mounted on housing  120  is used to control the operation of oscillation mechanism  108 . 
     Cutting Head 
       FIG. 2  is an enlarged perspective view of cutting head  102 , in accordance with an exemplary embodiment of the invention. Cutting head  102  optionally has a semicircular shape for cutting a circular or semi-circular incision in the lens capsule. Cutting head  102  optionally has sharp edges  132  and  134  on both planar sides of the cutting head, such that cutting can be performed on either planar side of the cutting head. 
     In cutting a circular or a semi-circular hole in eye tissue, cutting head  102  is placed in the eye tissue with first sharp edge  134  placed against a surface to be cut. Thus, at a single time, a substantial portion (e.g., more than 25% or even more than 35%) of the length of the lens capsule which needs to be cut, e.g., more than 1-2 mm, is in contact with the sharp edge. Oscillation mechanism  108  is then operated until a cut in the size and shape of sharp edge  134  is achieved. Cutting head  102  is then turned over, such that second sharp edge  132  is placed against tissue to be cut. Oscillation mechanism  108  is then re-operated, so that a cut of the size and shape of sharp edge  134  is achieved. 
       FIGS. 3A-3C  are schematic illustrations of openings in the anterior chamber achieved using cutting device  100 , in accordance with exemplary embodiments of the invention. As shown in  FIG. 3A , first and second cuts  162  and  164 , achieved by sharp edges  132  and  134 , respectively, define an incision  166 . A top end  172  (in  FIG. 3A ) and a bottom end  182  of cut  162  substantially coincide with top and bottom ends  174  and  184  of cut  164 , such that incision  166  is completely cut out of the underlying tissue and cuts  162  and  164  do not substantially extend into tissue not included in incision  166 . 
     In  FIG. 3B , the top ends  172  and  174  of cuts  162  and  164  substantially coincide, while the bottom ends  182  and  184  leave an uncut gap  168  between them. Optionally, the uncut gap  168  is not cut out in the cutting procedure, but rather is allowed to remain for the healing process. Alternatively, the uncut gap  168  is removed at a later stage using a third application of cutting head  102  or using any other cutting tool. In  FIG. 3B , the incision  166  is larger than in  FIG. 3A , due to gap  168 . 
     In  FIG. 3C , cuts  162  and  164  intersect, such that the cuts include external portions  192  that extend beyond that required in order to cut out incision  166 . Generally, external portions  192  heal naturally and do not cause complications in the eye. In  FIG. 3C , incision  166  is smaller than in  FIG. 3A , due to the intersection of the cuts  162  and  164 . 
     By selecting a relative layout of cuts  162  and  164 , a physician determines a desired size and shape of incision  166 . Thus, a single cutting device  100  can be used to form incisions  166  of a plurality of different sizes. Referring to a farthest point  200  from the longitudinal axis of cutting device  100 , the distance between point  200  in cuts  162  and  164  defines, in some embodiments of the invention, the size and shape of incision  166 . Optionally, markings  187  along cutting head  102  aid the physician in positioning the second sharp edge (e.g.,  132 ) relative to the first cut (e.g.,  164 ) in order to achieve a cut of a desired size. Alternatively or additionally, cutting head  102  includes visible markings  180 , which identify the end points of sharp edges  132  and  134 . 
     Sharp edges  132  and  134  optionally extend over substantially the entire extent of cutting head  102 . In some embodiments of the invention, sharp edges  132  and  134  do not extend over a distal tip  136  of cutting head  102 , so that distal tip  136  does not cause inadvertent cutting when inserted into the patient&#39;s eye. Alternatively, sharp edges  132  and/or  134  extend over the entire distal tip  136  of cutting head  102 . In some embodiments of the invention, sharp edges  132  and  134  do not extend to a connection point of cutting head  102  with handle  104 , so as to limit the chance of inadvertent undesired cutting. In an exemplary embodiment of the invention, sharp edges  132  and  134  extend over about 145°-165°. Alternatively, sharp edges  132  and  134  extend over at least 180°, so that a complete circle cut can be made when a circular cut of a maximal radius of cutting head  102  is desired. 
     In some embodiments of the invention, sharp edges  132  and  134  have a same extent. Alternatively, sharp edges  132  and  134  have different extents, allowing formation of unsymmetrical cuts, when required. 
     The size of cutting head  102  is optionally a compromise between a large size for achieving large cutting edges and a small size which is easier to manipulate in the anterior chamber. In some embodiments of the invention, cutting head  102  extends over about half a circle, e.g., about 175°-185°, such that a distal tip  136  of cutting head  102  is substantially on the longitudinal axis of cutting device  100 . 
     Cutting Head Size 
     In some embodiments of the invention, the semi-circular portion of cutting head  102  has a diameter of between about 6.5-7.5 millimeters. Cutting head  102  is optionally larger than the size of a required incision, by between about 10-20%, or even 40-50%, as the area of the cut is defined by the crossing of the curved lines cut out by both of sharp edges  132  and  134 . Alternatively, cutting head  102  has a smaller size, optionally having a diameter smaller than 5 millimeters or even smaller than 2 millimeters. In an exemplary embodiment of the invention, cutting head  102  has a diameter of between about 0.5-1.5 millimeters. Such small cutting heads are optionally used in procedures in which the lens of the eye is removed by liquidification or partial liquidification and therefore only a small incision is required. 
     Oscillation 
       FIG. 4  is an enlarged view of oscillation mechanism  108  and cutting head  102  placed against an eye  210 , in accordance with an exemplary embodiment of the invention. Oscillation mechanism  108  optionally comprises a motor  106  which pushes cutting head  102  distally, and a spring  112 , which retracts cutting head  102  proximally, so as to generate the oscillating movement. Optionally, motor  106  includes a piezoelectric crystal. Alternatively or additionally, any oscillation method and/or apparatus known in the art, may be used for inducing the oscillations of cutting head  102 , for example apparatus used for power-driven toothbrushes. Some of such mechanisms are described, for example, in U.S. Pat. No. 6,845,537 to Wong and/or U.S. Pat. No. 6,371,294 to Blaustien et al., the disclosures of which are incorporated herein by reference. 
     Alternatively or additionally, motor  106  comprises a small eccentric motor (e.g., a motor with an off-axis weight) with an attached mass which moves the center of mass of the motor away from the central axis of the motor. Further alternatively or additionally, an oscillation mechanism as used in portable cellular telephones is used instead of or in addition to motor  106 . 
     In some embodiments of the invention, cutting head  102  oscillates at a rate of at least 10 Hz, or even at least 20 Hz. Optionally, cutting head  102  oscillates at a rate of less than 100 Hz, less than 50 Hz or even less than 30 Hz. Alternatively, cutting head  102  oscillates at higher or lower rates. In some embodiments of the invention, the rate of oscillation of cutting head  102  is adjustable by a physician, according to personal preferences and/or the texture of tissue being cut. The oscillation rate is optionally selected to achieve the cut of the tissue while requiring from a physician minimal pressure of the cutting head against the tissue. 
     The amplitude of the oscillations of cutting head  102  is optionally at least 0.02 mm or even at least 0.1 mm. In some embodiments of the invention, the amplitude of the oscillations is smaller than 1 millimeter or even smaller than 0.5 millimeters. In an exemplary embodiment of the invention, the amplitude of the oscillations is smaller than 0.2 millimeters. 
     Possibly, those portions of cutting head  102  which are relatively parallel to the direction  110  of oscillation, operate as a saw when the oscillating is performed. The parallel portions generally cut into the tissue in a first stage of the cutting. The movement of the parallel portions of cutting head  102  downward into the cut tissue, possibly causes the portions of cutting head  102  that are perpendicular to the oscillation to cut into the tissue as they decline into the tissue with the parallel portions. 
     Alternatively or additionally to oscillating along the axis of cutting device  100 , cutting head  102  oscillates in other directions, for example in a direction indicated by an arrow  111 , in the plane of the axis of cutting device  100  perpendicular to the axis. In some embodiments of the invention, the oscillation is in a diagonal direction, for example 45° to the axis of the cutting device. In some embodiments of the invention, the direction of the oscillation changes during a cutting procedure, so that different portions of cutting head  102  have a saw effect on the tissue. In some embodiments of the invention, cutting head  102  oscillates in a direction normal to the cut surface, or in a diagonal direction having a component normal to the cut surface. 
     Cutting Head Shape 
     Cutting head  102  has a shape that defines an incision having a substantial area. Optionally, cutting head  102  is defined as a portion of a substantially perfect circle. Alternatively, in order to achieve a non-circular cut, a semi-elliptical (e.g., half an ellipse) cutting head is used. Further alternatively, a triangular or rectangular shape, or any other shape is used for cutting head  102 . In some embodiments of the invention, cutting head  102  is formed from a relatively soft material or structure, which allows a physician to adjust the shape of cutting head  102 . Optionally, cutting head  102  is relatively rigid in the cutting direction, while being relatively flexible in a direction allowing adjustment of the planar shape of the cutting head. 
     In some embodiments of the invention, rather than having an open shape, cutting head  102  has a closed shape, such as a full circle or elliptic shape. Optionally, the cutting head in accordance with this embodiment has a flexible shape which can be condensed for insertion into the eye. After insertion, the cutting head is expanded to its cutting shape, for example as described in above mentioned U.S. Pat. No. 5,728,117. After the expanding of the cutting head, the cutting head is oscillated to perform the cutting. 
     In an exemplary embodiment of the invention, cutting head  102  comprises a super elastic rod that is entered into the eye and formed into a predetermined shape within the eye. After the predetermined shape is formed, the oscillation is activated. In some embodiments of the invention, the predetermined shape comprises a circle with a predetermined radius, such as described in above mentioned U.S. Pat. No. 6,551,326. 
     Alternatively or additionally, any other method of adjusting the shape of the cutting head within the eye is performed before applying the oscillation. 
     Protective Cover 
     In some embodiments of the invention, a protective cover (not shown) is slid over cutting head  102  when not in use. Alternatively or additionally, the protective cover covers cutting head  102 , while the cutting head is maneuvered into the patient&#39;s anterior chamber. In some embodiments of the invention, the cover is connected to a control on housing  120 , which allows a physician to remove the cover, while cutting head  102  is within the anterior chamber. Alternatively or additionally, the physician can move the cover back onto cutting head  102 , while cutting head  102  is within the anterior chamber. Optionally, the control comprises a thin string running along or within housing  120 . Alternatively, any other mechanism, such as described below in relation to  FIG. 5 , is used. 
     In some embodiments of the invention, cutting head  102  and handle  104  are permanently mounted on housing  120 . Alternatively, housing  120  includes a receptacle adapted to receive a manual prior art cutting device and to provide oscillation to the cutting head. Further alternatively, handle  104  detachably connects to cutting head  102 , allowing, for example, mounting of different size cutting heads  102  on handle  104  and/or replacement for sterilization of the cutting heads. 
     Alternatively to requiring that a physician turn over the cutting head by turning over cutting device  100 , an automatic mechanism is provided within cutting device  100  for flipping the cutting head, as is now described in relation to  FIG. 5 . 
       FIG. 5  is a schematic sectional view of a capsulotomy cutting device  500 , in accordance with an exemplary embodiment of the invention. Cutting device  500  comprises a cutting head  502  with a handle  504  extending within a housing  520 . A blade cover  530  is used to cover a blade of cutting head  502  and hence prevent inadvertent cutting by the blade. As shown, blade cover  530  is half employed, covering only a proximal half of cutting head  502 . A cover manipulation handle  534  is moved axially in parallel to handle  504 , in order to remove blade cover  530  from covering cutting head  502  and/or in order to cover cutting head  502 . Moving handle  534  proximally, as indicated by an arrow  532 , exposes the blades of cutting head  502  for cutting, while moving handle  534  distally, in the direction opposite that indicated by arrow  532 , conceals the blade of cutting head  502 . Blade cover  530  optionally comprises a semi-rigid plastic, which on the one hand moves without folding over itself, and on the other hand can follow the contours of cutting head  502 . Alternatively, blade cover  530  is formed of any other material that allows movement back and forth to conceal and expose the blades of cutting head  502 . 
     In some embodiments of the invention, cutting head  502  is inserted into the patient&#39;s eye with blade cover  530  completely covering cutting head  502 . When cutting head  502  is in place, blade cover  530  is retracted and the cutting is performed. When the cutting is completed, blade cover  530  is moved back to cover cutting head  502  and the cutting head is removed from the patient&#39;s eye. In some embodiments of the invention, cutting head  502  is also covered before flipping cutting head  502  within the patient&#39;s eye. Alternatively, blade cover  530  can be moved within the patient&#39;s eye only proximally (or only distally). In accordance with this alternative, the production of blade cover  530  is simpler. 
     An oscillation motor  526  optionally oscillates cutting head  502  under control of a button (or other control)  518 . 
     In some embodiments of the invention, a pivot  524  controlled by a rotation motor  514  is used by the physician to rotate handle  504  and hence cutting head  502 . In some embodiments of the invention, the rotation of pivot  524  is used to flip cutting head  502 , instead of turning housing  520 . Optionally, rotation motor  514  is actuated by a button  516 . In some embodiments of the invention, the actuating of button  516  causes pivot  524  to rotate 180°. Alternatively, actuating of button  516  causes pivot  524  to rotate in small steps (e.g., 15°, 30°, 45°, 60°), allowing the physician to control the angle of the cutting head. Further alternatively, pivot  524  rotates in a continuous manner when button  516  is actuated. 
     Alternatively to a rotation motor  514 , pivot  524  is controlled mechanically, for example by a lever directly attached to pivot  524 , which is rotated by the physician. In some embodiments of the invention, rather than being battery operated, cutting head  102  is operated by a power cable or other energy source. 
     While the above description relates to a capsulotomy cutting device, the device of the present invention may be used to cut tissue in other body organs, such as the brain, head or neck, especially where it is desired to cut a circular, semi-circular or other planar cut beneath tissue, using an access hole smaller than the desired cut. 
     It will be appreciated that the above described methods of using the cutting device may be varied in many ways, including performing three or more cuts in achieving an incision. In some embodiments of the invention, however, a complete incision is achieved with no more than ten or even five placements of cutting head  102  against different locations on the lens capsule. It should also be appreciated that the above described description of methods and apparatus are to be interpreted as including apparatus for carrying out the described methods and methods of using the described apparatus. 
     The present invention has been described using non-limiting detailed descriptions of embodiments thereof that are provided by way of example and are not intended to limit the scope of the invention. It should be understood that features and/or steps described with respect to one embodiment may be used with other embodiments and that not all embodiments of the invention have all of the features and/or steps shown in a particular figure or described with respect to one of the embodiments. Variations of embodiments described will occur to persons of the art. 
     It is noted that some of the above described embodiments may describe the best mode contemplated by the inventors and therefore may include structure, acts or details of structures and acts that may not be essential to the invention and which are described as examples. Structure and acts described herein are replaceable by equivalents which perform the same function, even if the structure or acts are different, as known in the art. Therefore, the scope of the invention is limited only by the elements and limitations as used in the claims. When used in the following claims, the terms “comprise”, “include”, “have” and their conjugates mean “including but not limited to”.