Abstract:
An articulating optical surgical probe includes a handle sized to fit in a single hand and a single rigid cannula extending from the handle having a diameter of 20 Ga or less. The probe further includes a slotted tip at a distal end of the cannula and at least one optical fiber extending through the handle, the single rigid cannula and the slotted tip, and a pull-wire secured to the slotted tip. When the pull-wire exerts tension on the slotted tip, the slotted tip will deviate from straight to a bend angle controlled by the tension in the pull-wire. The slotted tip is formed from a resilient material that will restore to the straight position when the tension exerted by the pull-wire is released.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. provisional application Ser. No. 61/514,751, filed on Aug. 3, 2011, the contents which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to ophthalmic surgical equipment and more particularly to posterior segment ophthalmic surgical probes. 
       BACKGROUND OF THE INVENTION 
       [0003]    Microsurgical instruments typically are used by surgeons for removal of tissue from delicate and restricted spaces in the human body, particularly in surgery on the eye, and more particularly in procedures for removal of the vitreous body, blood, scar tissue, or the crystalline lens. Such instruments include a control console and a surgical handpiece with which the surgeon dissects and removes the tissue. With respect to posterior segment surgery, the handpiece may be a vitreous cutter probe, a laser probe, or an ultrasonic fragmenter for cutting or fragmenting the tissue and is connected to the control console by a long air-pressure (pneumatic) line and/or power cable, optical cable, or flexible tubes for supplying an infusion fluid to the surgical site and for withdrawing or aspirating fluid and cut/fragmented tissue from the site. The cutting, infusion, and aspiration functions of the handpiece are controlled by the remote control console that not only provides power for the surgical handpiece(s) (e.g., a reciprocating or rotating cutting blade or an ultrasonically vibrated needle), but also controls the flow of infusion fluid and provides a source of vacuum (relative to atmosphere) for the aspiration of fluid and cut/fragmented tissue. The functions of the console are controlled manually by the surgeon, usually by means of a foot-operated switch or proportional control. 
         [0004]    During posterior segment surgery, the surgeon typically uses several handpieces or instruments during the procedure. This procedure requires that these instruments be inserted into, and removed out of the incision. This repeated removal and insertion can cause trauma to the eye at the incision site. To address this concern, hubbed cannulae were developed at least by the mid-1980s. These devices consist of a narrow tube with an attached hub. The tube is inserted into an incision in the eye up to the hub, which acts as a stop, preventing the tube from entering the eye completely. Surgical instruments can be inserted into the eye through the tube, and the tube protects the incision sidewall from repeated contact by the instruments. In addition, the surgeon can use the instrument, by manipulating the instrument when the instrument is inserted into the eye through the tube, to help position the eye during surgery. 
         [0005]    Many surgical procedures require access to the sides or forward portion of the retina. In order to reach these areas, the surgical probes must be pre-bent or must be bendable intra-operatively. Various articulating optical surgical probes for providing laser and/or illumination light are known. See for example, U.S. Pat. No. 5,281,214 (Wilkins, et al.) and U.S. Pat. No. 6,984,130 (Scheller, et al.). The articulation mechanism, however, adds extra complexity and expense. One flexible laser probe needing no articulation mechanism is commercially available, but this device uses a relatively large diameter optical fiber sheathed in a flexible tube comprising the distal tip, resulting in a large bend radius and large distal tip diameter with significant bend stiffness. These characteristics require that the distal tip contain a non-bent straight portion for ease of insertion of the bent portion, which must flexibly straighten as it passes through the hubbed cannula. The straight portion of the distal tip allows the bent portion to flexibly pass through the hubbed cannula before the distal cannula of the handpiece enters the hubbed cannula, to allow maximum bending clearance of the flexible portion, thereby minimizing the bending strain and corresponding frictional insertion forces. Such a large bend radius, large diameter flexible tube, and straight distal tip causes the useable portion of the fiber to extend a relatively long distance from the distal tip of the probe and limits access of the probe. 
         [0006]    A further disadvantage in the known art is the flexibility of the distal cannula, which is a function of the material properties and cross sectional moment of inertia, as determined by the gauge size of the outside diameter of the cannula to fit within the hubbed cannula, and the inside diameter of the cannula to accept the flexible tube. For any given material, the outer and inner diameters of the cannula determine the flexibility of the cannula. This flexibility limits the surgeon&#39;s ability to use the instrument to manipulate the position of the eye during surgery. 
         [0007]    A flexible-tip probe is disclosed in U.S. Patent Application Publication 2009/0093800 (Auld, et al.) that does not require a straight portion of flexible tube, which thus provides a more compact useable tip length, thereby allowing greater access to internal posterior structures of the eye without compromising insertion forces. The flexible-tip probe provides increased rigidity of the distal cannula to facilitate manipulation of the position in the eye during surgery. While this probe provides a relatively smaller cross section as compared to the previous probes, such as those disclosed by Scheller et al., it does not provide controllable articulation over a range of angles in the manner those probes do. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    An articulating optical surgical probe includes a handle sized to fit in a single hand and a single rigid cannula extending from the handle having a diameter of 20 Ga or less. The probe further includes a slotted tip at a distal end of the cannula and at least one optical fiber extending through the handle, the single rigid cannula and the slotted tip, and a pull-wire secured to the slotted tip. When the pull-wire exerts tension on the slotted tip, the slotted tip will deviate from straight to a bend angle controlled by the tension in the pull-wire. The slotted tip is formed from a resilient material that will restore to the straight position when the tension exerted by the pull-wire is released. 
         [0009]    Other objectives, features and advantages of the present invention will become apparent with reference to the drawings, and the following description of the drawings and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a schematic of an articulating optical surgical endoprobe, according to a particular embodiment of the present invention; 
           [0011]      FIG. 2  illustrates an end view of an example of a slotted tip  20  according to a particular embodiment of the present invention; 
           [0012]      FIGS. 3A-3H  illustrate various slot designs for a slotted tip according to particular embodiments of the present invention; and 
           [0013]      FIGS. 4A-4K  illustrate various mechanisms for increasing the tension in the pull-wire  22  according to particular embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Various embodiments of the present invention may avoid difficulties associated with previous articulating optical surgical probes. In particular, certain embodiments of the present invention may provide a single rigid cannula with a small diameter not only capable of insertion into very small incisions but also capable of articulating in a controlled fashion through a range of angles. Thus, such embodiments of the present invention combine the advantages of a relatively rigid articulating optical surgical probe with the controllable articulation of dual cannula probes that require a larger diameter. 
         [0015]    Particular embodiments of the present invention include a single rigid cannula with a slotted tip of resilient material secured to a pull wire. Tension in the pull wire causes the slotted tip to bend in a particular direction, while releasing the tension allows the resilient tip to restore to its straight position. Pull-wire technology has been used previously to deviate a distal end of a surgical catheter, but not in a small-diameter, rigid cannula used in handheld optical surgical probes nor with the degree of angular movement used in the relatively small spaces found within the interior of an eye. Consequently, the application of pull-wire tension in the context of hand-held surgical probes is uniquely advantageous. In particular embodiments of the present invention, one or more of the optical fibers used in the endoprobe  10  may also be used as the pull-wire. 
         [0016]      FIG. 1  is a schematic of an articulating optical surgical endoprobe  10 , according to a particular embodiment of the present invention, with a handle  12  suitable for being held in a single hand and a cannula  14 . (For ease of illustration, the handle  12  and cannula  14  are not shown to scale and certain external features of the handle  12 , such as the control mechanism for an internal pull-wire, are not shown.) The proximal end of the endoprobe  10  is connected to one or more light sources (not shown) that provide laser and/or illumination light by connection to at least one optical fiber running through the interior of the endoprobe  10 . 
         [0017]    The cannula  14  is formed of a rigid biocompatible material, such as stainless steel. Endoprobes, according to various embodiments of the present invention, use a “single” rigid cannula, referring to the fact that there is no other relatively rigid, self-supporting cannula formed separately inside or outside the single cannula and/or independently movable with respect to the single cannula. However, the term “single” is not intended to exclude the use of multiple layers or coatings to form the single cannula, nor does it exclude the use of soft polymer sleeves or sheaths that conform to the shape of the cannula. The cannula  14  has a slotted tip  20  at a distal end (referring to the end farthest from the surgeon during use). The slotted tip  20  may articulate in a selected direction in a controllable manner by applying tension to a pull wire secured within the slotted tip  20  (not shown in  FIG. 1 ). 
         [0018]    The slotted tip  20  is formed from a resilient material, referring to a material that can restore to the straight orientation after the tension from the pull-wire is removed. The resilient material for the slotted material may be, for example, nitinol, which can be both sufficiently rigid to insert through an incision hub and sufficiently resilient to restore after articulation. Other metals, such as spring steel, or other materials with similar properties known in the art could be used. Depending on the particular slot configuration of the slotted tip, it may be possible to use relatively rigid materials that are not exceptionally elastic, such as stainless steel, Ni-base super-alloys, Co—Cr alloys, or the like without applying so much force as to exceed the yield point and permanently deform the material. The resilient materials may themselves be biocompatible, or they could be enclosed in another material, such as a polymer sheath, to prevent contact with tissue. The cannula  14  and the slotted tip  20  can be, but need not be, formed from the same material. The cannula  14  and/or the slotted tip  20  may also be coated with a stiffening material, such as synthetic diamond or metal plating (e.g., chromium), to provide improved stiffness for insertion into an incision hub and to reduce the likelihood of breakage. 
         [0019]      FIG. 2  illustrates an end view of an example of a slotted tip  20  according to a particular embodiment of the present invention. In the embodiment depicted in  FIG. 2 , a pull-wire  22  is secured to what is shown as the top side of the slotted tip  20 . The slotted tip  20  encloses two optical fibers  24  and  26 , an illumination fiber  24  having a diameter of 183 μm and a laser fiber  26  having a diameter of 108 μm. Allowing for the width of the slotted tip  20 , this allows for the diameter of the cannula  14  to be made smaller relative to dual cannula systems. 
         [0020]      FIGS. 3A-3H  illustrate various slot designs for the slotted tip  20  according to particular embodiments of the present invention (respectively labeled as “ 20 A,” “ 20 B,” etc., and collectively referred to as “slotted tip  20 ”). In  FIG. 3A , slots deeper than the radius of the slotted tip  20 A are cut into the side of the slotted tip  20 A toward which the slotted tip  20 A is to bend. Shallow slots are cut into the opposite side permitting that side to bend as well.  FIGS. 3B and 3C  illustrate straight and curved “keyhole” slots having a wider base as the slot extends deeper into the respective slotted tips  20 B and  20 C. The wider base reduces the amount of force required to deviate the slotted tip  20 B or  20 C to its curved position, potentially making the endoprobe  10  more comfortable to use. 
         [0021]      FIGS. 3D-3G  illustrate slot designs that can be used for more rigid tip materials to allow the slotted tip  20  to resiliently restore to the straight position after being deviated into the curved position. In  FIG. 3D , slots that are generally oblong along the length of the cannula  14  are set opposed to shallow back slots, which tends to reduce the force required to deviate the slotted tip  20 D to the curved position. In  FIG. 3E , a continuous spiral cut, allowing the slotted tip  20 E to bend, is interspersed with back slots (in this case, keyhole slots), causing the slotted tip  20 E to bend in the direction of the back slots.  FIG. 3F  shows a spiral cut pattern wherein the spiral path is perpendicular to the longitudinal axis of the slotted tip  20 F on one side, causing the slotted tip  20 F to preferentially deviate toward the side where the spiral path is perpendicular.  FIG. 3G  shows a spiral cut pattern with the cut widened selective on one side, causing slotted tip  20 G to selectively deviate toward the side where the spiral cut is wider. 
         [0022]      FIG. 3H  shows a slotted tip  20 H formed out of a wound wire of material, such as by winding material drawn into wires around a mandrel. At a proximal and distal end of the slotted tip  20 H the coils of the wound wire are welded together. In the intermediate region between the proximal and distal ends, one side of the tube has widened interstitial slots formed between the coils of the wound wire, causing the slotted tip  20 H to selectively deviate toward the widened slots when tension is applied via the pull-wire. Forming the slotted tip  20  of a wound wire of material may have advantages by permitting the use of materials that can more easily be formed into wires than tubes. Although a single wound wire is shown in  FIG. 3H , multiple wire strands could also be used. 
         [0023]      FIGS. 4A-4K  illustrate various mechanisms for increasing the tension in the pull-wire  22  according to particular embodiments of the present invention. In  FIGS. 4A and 4B , the pull-wire  22  is wound on a pinion  40  secured between a control button  42  and a base  44 . The pinion  40  comprises two surfaces, a smaller diameter surface r which rolls between the control button  42  and a base  44 , and a larger diameter surface R about which the pull wire  22  winds. The radial difference between the smaller and larger diameter surfaces r and R results in a differential displacement Δ1 in the pull wire as the pinion  40  rotates and translates. By selecting appropriate diameters for the smaller and larger diameter surfaces r and R, a relatively small amount of pull wire displacement Δ1 can be achieved during a relatively large amount of control button translation, providing the user with precise control over the deflection in the slotted tip  20 . In one embodiment, the smaller diameter surface r comprises gear teeth with mating gear teeth on the control button  42  and the base  44 . This may reduce the likelihood of slippage. 
         [0024]      FIGS. 4C and 4D  illustrate a lever arm  50  with a sliding actuation pin  52  held in place by a fixed pin  54  at a pivot of the arm. A control button (not shown) can be used to advance the sliding pin  52 , permitting the proximal portion of the lever arm  50  to rise, thus rotating a lanyard  56  at a distal end of the lever arm  50  to apply tension to the pull-wire  22 .  FIGS. 4E and 4F  show a pull-wire  22  threaded over a sliding pin  60  and a first fixed pin  62  and anchored to a second fixed pin  64 . Advancing a control button  66  attached to the sliding pin  60  increases the tension in the pull-wire  22 . 
         [0025]      FIGS. 4G and 4H  illustrate a pull-wire  22  threaded over a sliding pin  70  that is directed in a generally upward direction by a guide track  72  as a control button  74  is advanced. The path of the guide track  72  determines how the tension in the pull-wire  22  varies as the control button is advanced, thus providing a smooth and controlled increase in tension. In the case of a linear guide, like the one illustrated in  FIG. 4G and 4H , the pull-wire take up will occur in the latter portion of the advancement of the control button  74 . In the alternative configuration shown in  FIG. 4I , the guide track  72  is reshaped to provide greater take-up of the pull-wire at the beginning of the advancement by the control button  74  to produce a more balanced increase in tension throughout the stroke of the control button  74 . In  FIG. 4J , the guide track  72  inclines even more sharply so that most of the tension increase takes place early in the stroke of the control button  74 .  FIG. 4K  illustrates an alternative embodiment of the guide track  72  with detents  80 , allowing for distinct “stops” along the path corresponding to different angles of the slotted tip  20 . A shelf or surface with detents can be also be used with any of the various embodiments of endoprobe  10  using a sliding pin or similar actuation mechanism, including any of the embodiments shown in  FIGS. 4A-4K . 
         [0026]    While certain embodiments of the present invention have been described above, these descriptions are given for purposes of illustration and explanation. Variations, changes, modifications and departures from the systems and methods disclosed above that would be apparent to one skilled in the art may be adopted without departure from the scope of the present invention as recited in the following claims.