Abstract:
A length or strand of resilient material is formed into a continuous ring having multiple tissue-engaging portions for engaging and spreading eyeball tissue segments apart. The strand is formed with elongated straight sides joined by corner portions which are enlarged in directions transverse to the length dimension of each adjacent side. The corner portions constitute the tissue-engaging portions and have top and bottom sections and a connecting section that forms a gap for receiving the tissue. Each side of the ring extends from a bottom section of one corner to a top section of an adjacent corner. When the ring is deployed, the tissue is captured in the gaps at the corners of the ring and also is engaged along each side as that side transitions from a position situated below the tissue to a position situated above the issue.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 13/291,946, filed Nov. 8, 2011, which claims the benefit of U.S. Provisional Application No. 61/411,870, filed Nov. 9, 2010, and this application is a continuation-in-part of U.S. patent application No. 12/074,731, filed Mar. 5, 2008, which claims the benefit of U.S. Provisional Application No. 60/918,404, filed Mar. 15, 2007. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to a ring used to maintain an opening in eyeball tissue in an expanded condition during an ophthalmic procedure. 
         [0003]    During ophthalmic surgery, it is sometimes desirable to enlarge an opening in eyeball tissue, such as holding the iris open for access through the pupil. For example, cataracteous lenses can be replaced in a procedure commonly referred to as phacoemulsification, or “phaco” for short. In a phaco procedure access through the pupil is required to insert and manipulate an ultrasonically driven tool to break apart and aspirate the lens. It has been proposed that, at least in some cases, expansion of the opening be achieved mechanically by hooks that engage and pull against edge portions of the eyeball tissue, such as inner edge portions of the iris to expand the pupil during a phaco procedure. See, for example, the hooks disclosed in U.S. Pat. No. 5,716,328. 
       SUMMARY 
       [0004]    This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
         [0005]    The present invention provides a length or strand of resilient material formed into a continuous ring having multiple tissue-engaging portions for engaging and spreading eyeball tissue segments apart. The strand is formed with elongated straight sides joined by corner portions which are enlarged in directions transverse to the length dimension of each adjacent side. The corner portions constitute the tissue-engaging portions and have top and bottom sections and a connecting section that forms a gap for receiving the tissue. Each side of the ring extends from a bottom section of one corner to a top section of an adjacent corner. When the ring is deployed, the tissue is captured in the gaps at the corners of the ring and also is engaged along each side as that side transitions from a position situated below the tissue to a position situated above the issue. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0006]    The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
           [0007]      FIG. 1  is an enlarged, diagrammatic top perspective of an expansion ring in accordance with the present invention; 
           [0008]      FIG. 2  is a further enlarged, fragmentary detail thereof; 
           [0009]      FIG. 3  is a diagrammatic top plan thereof; 
           [0010]      FIG. 4  is a diagrammatic top plan thereof corresponding to  FIG. 3  but with parts in different positions; 
           [0011]      FIG. 5  is a diagrammatic side elevation thereof; 
           [0012]      FIG. 6  is an enlarged, fragmentary detail of a corner portion thereof viewed generally in the direction indicated by the arrow A 6  in  FIG. 1  and showing such corner portion in elevation looking toward the center of the ring; 
           [0013]      FIG. 7  is an enlarged, fragmentary detail of such corner portion corresponding to  FIG. 6  but showing such corner portion in an oblique orientation; and 
           [0014]      FIG. 8  is a perspective of an injector and ring holder that can be used to load and inject the ring, with some parts shown in exploded relationship; 
           [0015]      FIG. 9  is a diagrammatic top plan of a modified expansion ring in accordance with the present invention; 
           [0016]      FIG. 10  is a diagrammatic top perspective thereof during manufacture; 
           [0017]      FIG. 11  is a diagrammatic top perspective of manufacturing equipment therefor; 
           [0018]      FIG. 12  is a diagrammatic section of the manufacturing equipment therefor; 
           [0019]      FIG. 13  is a diagrammatic top perspective of equipment for insertion thereof; 
           [0020]      FIG. 14  is a diagrammatic top perspective of equipment for insertion thereof corresponding to  FIG. 13  but with parts in different positions; 
           [0021]      FIG. 15  is a diagrammatic top plan illustrating insertion thereof; and 
           [0022]      FIG. 16  is a diagrammatic top plan illustrating aspects thereof after insertion. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    In the embodiment of the present invention shown in  FIG. 1 , a continuous ring  10  is formed from a single long strand of resilient material, such as a molded plastic material. In the illustrated embodiment, the ring  10  has four corners  12 ,  14 ,  16 , and  18  connecting four straight sides  20 ,  22 ,  24 , and  26 . As described in more detail below, each corner is formed by a loop of the strand. Although a square ring is illustrated, it is to be understood that the ring may have a rectangular configuration, or a nonrectangular shape. For example, the ring may be formed as a triangle that has three sides and three loops located at the ring corners, as represented by the broken line in  FIG. 1  representing a triangular ring having corners  12 ,  18 , and  14 . 
         [0024]      FIG. 2  shows a preferred construction in which the ring is formed from one length of material with two ends  30  and  32  that are “butt attached” by adhesive represented at  34 . Each of the ends  30  and  32  has an indent  36 ,  38 , respectively, such that the adhesive  34  can flow into the indents to increase the strength of the butt attachment. The indents create surface structure that minimizes shearing and de-lamination of the adhesive  34  from the ring  10 . A representative adhesive is a Class VI epoxy, applied by a tool that ensures a repeatable volume and dimension of the solidified adhesive form. 
         [0025]    With reference to  FIGS. 3-5 , the ring  10  can be drawn into an insertion tube T and, after insertion of the tube into the posterior chamber of the eye, projected from the tube and manipulated to expand the opening of the iris.  FIG. 3  shows the initial stages of the ring  10  being inserted into the pupil P. The corner loop  18  remote from the tube is manipulated to capture an edge portion of the iris. Corners  12  and  16  at the sides form deflection areas or “hinges” between the sides adjacent to them. With reference to  FIG. 4 , as the ring is inserted farther it can be manipulated so that iris tissue is received in such side loops  12  and  16 . As seen in  FIG. 5 , each corner loop has a gap  58  that receives and captures iris tissue. The loop design provides an easy means of inserting and capturing iris tissue. 
         [0026]    More specifically,  FIG. 6  is an enlarged elevation view looking inward toward the center of the ring at corner  12 , and  FIG. 7  is a corresponding view but at an oblique angle from a higher viewpoint. Although corner  12  is referenced, all four corners are identical, as shown in the drawings. Each corner connects two adjacent straight sides, each long and narrow and elongated in the direction of its length (which can be referred to as the “x” dimension). For corner  12 , the adjacent sides connected are side  20  which is inclined up from the bottom of corner  18  (see  FIG. 1 ) to the top of corner  12 . Similarly, side  22  is inclined away from the bottom of corner  12  to the top of corner  14  ( FIG. 1 ), and so on around the ring. Each side extends from the bottom of one corner to the top of another, and each corner is enlarged in a first direction transverse to the x dimension of a side it connects (which can be referred to as the “y” dimension; vertical in the orientation of  FIG. 6 ). The broken line L in  FIG. 6  represents the location of the outermost point of the corner where the widest part of the gap  58  is located (and where the corner is presented to the tissue to be captured). From line L the corner loop has an arcuate section  59  that spirals down and to the inside of the ring like a single loop or coil of a helix. As compared to the x and y dimensions, the inward direction can be referred to as the “z” dimension (which is into the page in the orientation of  FIG. 6 , and which is orthogonal to the y dimension). The corner is enlarged in the y and z dimensions as compared to the narrow height and width of a side. As seen in  FIG. 6 , the inner part of the section  59  will extend diagonally along the edge of the tissue captured in the gap  58  resulting in a broad contact area at the edge of the iris, for example. The gap  58  can be proportioned such that there is a clamping force applied to the iris tissue captured in the corner loop. 
         [0027]    As represented diagrammatically in  FIG. 4 , the iris is expanded further as the ring is inserted and the corners capture the edge of the iris and spread it open, providing a larger space for an ophthalmic procedure to be performed. 
         [0028]      FIG. 8  shows an embodiment of an injector  100  that can be used to inject a ring  10  into a patient&#39;s eye. The ring can be loaded into the injector with the use of a holder  102 . The holder  102  may include a cover  104  that is attached to a base plate  106  by fasteners  108 . The base plate  106  has a channel  110  and a recess  112 . The recess  112  receives the ring  10 . 
         [0029]    The injector includes a cannula  120  attached to a handle  122 . Within the cannula  122  is a wire hook  124 . The wire hook  124  is connected to an inner slide tube  126  located within the handle  122 . A button  128  is attached to the inner slide tube  126 . The injector  100  may also have a pair of guide pins  130  that are attached to the handle  122  and cooperate with the corresponding channel features  132  of the base plate  106  to properly align the injector  100  when the cannula is inserted into the base plate channel  110 . 
         [0030]    In operation, the cannula  120  is inserted into the base plate channel  110 . When fully inserted the wire hook  124  extends into the ring  10 . The cover  104  may have an opening that allows an operator to visually see the hook  124 . An operator pulls the button  128  in the direction indicated by the arrow. Pulling the button  128  causes the hook  124  to grasp the ring at a corner loop and pull the ring into the cannula  120 . The recess  112  has tapered walls  136  to assist in the ring collapsing within the channel  110  for insertion into the cannula  120 . Once loaded, the ring  10  can be injected into a patient&#39;s eye by pushing the button  128  in the opposite direction. 
         [0031]      FIG. 9  shows a modified iris extension ring  60  in accordance with the present invention. It should be noted that in  FIG. 9 , and all drawings, sizes are exaggerated for ease of illustration and understanding. Ring  60  is formed from a single long strand of resilient material such as 4-0 or 5-0 polypropylene surgical suture. The ring material has memory characteristics such that when held taut in a desired shape and then heat treated and cooled, such shape will be retained in the relaxed or “at rest” state. Due to the resiliency of the material, from the relaxed state the material can be deformed, in which case it applies a resisting force tending to return to the preformed shape. 
         [0032]    In the case of the embodiment of the present invention shown in  FIG. 9 , ring  60  has four straight sides  62 ,  64 ,  66 , and  68 . Side  62  has the end butt joint  70  where a drop of adhesive  72  secures the ends  74 ,  76 , such ends preferably having the indented portions  78  to increase the holding effectiveness of the adhesive. 
         [0033]    In the plan view of  FIG. 9 , side  64  is perpendicular to side  62 . These sides are joined by a corner portion  63  which has three distinct bends, namely, a first obtuse bend  80  (essentially 135° inward and to the left as viewed in  FIG. 9 ), a second return bend  82  (essentially 180° inward and then down away from the viewer and then toward the right as viewed in  FIG. 9 ), and a third obtuse bend  84  (essentially 135° up and to the left as viewed in  FIG. 9 ). Corner  65  joining sides  64  and  66  is identical to corner  63  with the three distinct portions  80 ,  82 ,  84 , as are the two additional corner portions  67  (joining sides  66  and  68 ) and  69  (joining sides  68  and  62 ). 
         [0034]    The shape of the ring embodiment  60  can be achieved by use of a winding fixture, aspects of which are shown diagrammatically in  FIG. 10 . The fixture includes a composite jig having a thin plate  100  with four generally radially extending arms  102  spaced 90° apart. Vertical pins  104  extend upward through holes in the outer end portions of the arms  102  at locations corresponding to the obtuse bends  80 . The end portions of the arms  102  also have short tabs  106  curved down from the plane of the remainder of the plate  100 , approximately aligned with the pins  104 . 
         [0035]    Aspects of the ring  60  may be better appreciated in conjunction with the manner in which the ring is manufactured. Starting at the left of  FIG. 10 , a length of the suture material S is stretched to the lowermost pin  104  and wound around the outer periphery of the pin to achieve the inward obtuse bend  80  of approximately 135° for the corner portion  63 . From there the suture extends along the top of the plate  100  to the inner edge of the associated tab  106 , then down under the plate and back outward to form the inner bend  82  of approximately 180°. This section of the suture extends along the face of the tab adjacent to the corresponding arm  102  and then along the outer edge of tab and toward the next pin  104  to form the last obtuse bend  84  of corner portion  63 . Thus, there is a short stretch of suture that extends almost radially along the face of the tab and the obtuse bend  84  which leads to the side  64 . The winding procedure is the same at corner portions  65 ,  67 , and  69 , with the opposite (“exiting”) end portion S′ of the length of suture extending to the right as seen in  FIG. 10 , along side the entering portion S. 
         [0036]      FIG. 11  shows the winding fixture on a smaller scale (dimensions still exaggerated due to the extremely small nature of the ring, particularly the suture which may be on the order of 0.006 to 0.008 inch diameter). Plate  100  is mounted on a central hub  110  fixed to an upper elevator block  112 . Block  112  is guided for vertical movement by bolts  114  and the pins  104  that extend somewhat loosely through the elevator block  112  to a base block  115 . An entrance screw  116  is provided to anchor the stretch of suture that leads to the winding pins, and an exit screw  118  is used to anchor the opposite or exiting end portion of the suture after the winding operation is completed (i.e., after the suture is routed as shown in  FIG. 10 ). With the suture thus held in the desired form, it is heated in an oven to close to the softening temperature for a period of time sufficient to achieve the desired memory characteristics. In a representative embodiment, the heat treating can be at a temperature of 165° C. to 170° C. for 6 to 8 minutes, but the temperature and time may be adjusted depending on the particular material used. Thereafter, the fixture and iris extension ring contained thereon are cooled. 
         [0037]    With reference to  FIG. 10 , after cooling, the entering and exiting stretches of suture can be severed in one snip, preferable approximately midway between the adjacent corners, such as at the location indicated by the broken line L′ in  FIG. 10 . Then, as represented in  FIG. 12 , the upper elevator block  112  is raised such that the winding plate  100  is lifted to a position above the tops of the pins  104 , which simplifies removal of the ring  60  from the fixture, prior to completion of the ring by joining the cut ends as previously described. 
         [0038]    With reference to  FIG. 13 , a single completed ring  60  can be fitted in a recess of a holder having a bottom section  120  and lid section  122 . Such holder has a channel leading to the recess in which the ring  60  is positioned, for reception of the insertion tube  124  of an implanting instrument  126 .  FIG. 14  illustrates the parts connected with the insertion tube received in the channel. 
         [0039]      FIG. 15  illustrates ejecting of the ring  60  in the eye, with the inner bend  82  of corner portion  65  engaged against an edge portion of the iris. Such edge portion rides into the gradual arc of bend  82  with little or no friction that could cause abrasion. Each corner is enlarged in two directions transverse to the length (x dimension) of each narrow strand side that it connects. One transverse direction (y dimension) forms the gap or opening presented to the tissue to be captured. The other transverse direction (z dimension) extends inward and limits the extent of insertion of the tissue into the channel or pocket formed by the inner portion (bend  82  for this embodiment) of the corner.  FIG. 16  illustrates the position after the ring  60  has been fully deployed. The innermost bend  82  of each of the corner portions receives a portion of the inner edge of the iris. The ring is sized such that it is in a slightly compressed state when deployed, so that an expansion force is applied against the iris to increase the opening. Also, it can be seen in  FIG. 16  that the bends  82  do not apply the only edge-contacting portions of the ring. A top obtuse bend  80  at each corner leads to the corresponding return bend  82 . Such return bend  82 , in turn, leads to a bottom obtuse bend  84  (shown in broken lines). The side to which a bottom obtuse bend  84  leads is inclined upward (outward) slightly due to the positioning of the suture on the winding fixture, just as the straight sides of the previously described embodiment transition from the bottom of one corner to the top of the next, and each side of the ring emerges from the pupil approximately midway between adjacent bends (or corners), or at least somewhat centrally between the bends. Thus, there are eight spaced points of contact of the iris edge portion by the contracted ring  60  (or ring  10 ) for a more even application of an expanding force. 
         [0040]    As seen in  FIG. 16  ring  60  can be formed with no parts of any corner that directly overlie one another. The dimensions of the ring and the various bends are chosen so that minimal abrasive force is applied to the iris, and no or essentially no pinching or clamping force. However, the bends  82  do not extend diagonally across the inner edge of the iris as in the previously described embodiment. Dimensions are selected such that the opening formed by each return bend  82  is at least as great as the marginal thickness of the iris, with no coils or loops located one above the other. 
         [0041]    More specifically, it can be seen in  FIG. 10  that each obtuse bend  80  (best seen for the bend  80  at the top of the view) is angled outward slightly from its pin  104  to the corner between the plate arm  102  and the corresponding tab  106  where the central portion of the return bend  82  is formed. The bottom part of such return bend is canted slightly away from the top part of the bend to the outer edge of the tab. The radius of curvature of the return bend is determined primarily by the thickness of the plate  100 . In a representative embodiment, the plate can be 0.015″ thick. It has been found, however, that the total depth of the channel or notch formed by the return bend will be somewhat greater than the plate thickness, such as 0.019″ to 0.020″ in a representative embodiment. 
         [0042]    While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.