Patent Publication Number: US-2022233352-A1

Title: Ophthalmic cannula with external engagement feature

Description:
BACKGROUND 
     Ophthalmic surgeries require that a portion of a surgical instrument must pass through the wall of the eye and into the interior of the eye. A simple incision through the wall of the eye can suffice to provide such a passageway. In modern practice, however, an ophthalmic cannula is usually placed into this incision. The cannula provides a rigid tubular passageway through the wall of the eye. During some surgeries, three ophthalmic cannulae are placed at various locations in the wall of the eye. Two of these facilitate the passage of surgical instruments held in the surgeon&#39;s two hands. The third provides an attachment point for an infusion tube, which delivers fluid into the eye to replace material removed through the surgical instruments and to maintain the fluid pressure inside the eye. 
     Ophthalmic surgical instruments typically include a handle portion and a needle portion. The needle portion comprises a cylindrical tube. The distal end of the tube incorporates functional elements such as cutting blades or forceps tips, and the mechanisms for operating these functional elements pass through the interior of the tube. The needle portion of the surgical instrument passes through the ophthalmic cannula into the interior of the eye. In order to place the functional elements at the tip of the needle at the location in the eye where the surgical function is to be performed, it is necessary to insert the needle through the cannula to various depths and to rotate the needle (and with it the cannula) to various angles with respect to the wall of the eye. These manipulations can place a stress on the needle, and on the mechanisms disposed therein, particularly at the location where the needle enters the ophthalmic cannula. 
     With the trend toward smaller needle sizes (from approximately 0.9 mm diameter for earlier instruments to approximately 0.4 mm diameter for more recent instruments) instrument failure due to needle bending stresses is increasingly common. One solution to this problem is proposed in U.S. Pat. No. 10,179,007, the entire contents of which are incorporated by reference herein. The surgical instrument includes a reinforcing slider coaxial with the needle. The reinforcing slider is movable with respect to the handle and the needle, such that the position of the reinforcing slider may be adjusted to vary the length of the portion of the needle that extends past the slider end portion. It is intended that the slider end portion be in contact with the cannula during use, such that movements of the instrument handle to cause rotation of the needle and the cannula with respect to the wall of the eye are communicated to the cannula through the reinforcing slider rather than through the needle. 
     SUMMARY 
     The present disclosure relates, for example, to engagement features incorporated into an ophthalmic cannula which facilitate communication of forces from a reinforcing slider to the cannula. These engagement features may also be used to facilitate attachment of an infusion tube to the cannula. While current cannula systems also have engagement features for attachment of an infusion tube, the structures of the systems described herein are unique (at least in part) in the location of the engagement features relative to other features such as a valve. 
     Specifically, the systems described herein relate for example to structures in which an engagement feature(s) is disposed at or near the end of a cannula opposite an end which enters the eye. If a valve is present in such a structure, it is disposed between the engagement feature(s) and an interior of the cannula. 
     In accordance with one example embodiment, an ophthalmic surgical system includes a cannula having a receptacle or a cannula closure. The receptacle includes a valve and a first lip extending inwardly and defining at least a portion of a chamber in the receptacle. The ophthalmic surgical system also includes a surgical instrument having a second lip that is sized and shaped to engage with the first lip of the cannula to couple the surgical instrument to the cannula. 
     In accordance with another example embodiment, a cannula includes a tubular portion having a hollow interior, and a receptacle coupled to the tubular portion. The receptacle includes an internal chamber disposed at a first end of the receptacle and adjacent to and open to the hollow interior of the tubular portion. The receptacle also includes an external chamber disposed at an opposite end of the receptacle, and a valve disposed between the internal chamber and the external chamber. The valve is movable between a closed position and an opened position. The cannula also includes a lip defining at least a portion of the external chamber. The lip is configured to engage a portion of a surgical instrument. 
     In accordance with another example embodiment, a method of coupling a surgical instrument to a cannula includes moving a lip of a surgical instrument axially into an external chamber of a receptacle of the cannula, extending a needle of the surgical instrument through a valve in the receptacle, and bending the needle of the surgical instrument until a surface of the lip of the surgical instrument is moved within the exterior chamber and into engagement with a surface of a lip of the receptacle. 
     Other embodiments and aspects of various embodiments will become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an ophthalmic cannula. 
         FIG. 2  is a partial, enlarged cross-sectional view of a portion of the ophthalmic cannula. 
         FIG. 3  is a perspective view of a surgical instrument. 
         FIG. 4  is a partial, enlarged cross-sectional view of a portion of the surgical instrument. 
         FIG. 5  is a perspective view of an infusion tubing set. 
         FIG. 6  is a partial, enlarged cross-sectional view of a portion of the infusion tubing set. 
         FIG. 7  is a cross-sectional view of both the ophthalmic cannula and the surgical instrument during a first assembly step. 
         FIG. 8  is a cross-sectional view of both the ophthalmic cannula and the surgical instrument during a second assembly step. 
         FIG. 9  is a cross-sectional view of both the ophthalmic cannula and the surgical instrument during a third assembly step. 
         FIG. 10  is a cross-sectional view of both the ophthalmic cannula and the infusion tubing set during a first assembly step. 
         FIG. 11  is a cross-sectional view of both the ophthalmic cannula and the infusion tubing set during a second assembly step. 
         FIG. 12  is a cross-sectional view of an alternate embodiment of both the ophthalmic cannula and the infusion tubing set during a first assembly step. 
         FIG. 13  is a cross-sectional view of both the ophthalmic cannula and the infusion tubing set of  FIG. 12 , during a second assembly step. 
         FIG. 14  is a cross-sectional view of an alternate embodiment of both the ophthalmic cannula and the surgical instrument during a first assembly step. 
         FIG. 15  is a cross-sectional view of both the ophthalmic cannula and the surgical instrument of  FIG. 14  during a second assembly step. 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments are explained in detail, it is to be understood that embodiments are not limited in their application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. Other embodiments are possible and embodiments described and illustrated are capable of being practiced or of being carried out in various ways. 
       FIGS. 1 and 2  illustrate an example cannula  100 . The cannula  100  is described in the context of being used as an ophthalmic cannula, and being used with surgical instruments and/or infusion tubing sets during ophthalmic surgery. The cannula  100 , however, may also be used in conjunction with other surgeries and/or procedures, and/or may be coupled to other instruments other than the ophthalmic surgical instruments and infusion tubing sets described herein. 
     In the example illustrated, the cannula  100  includes a tubular portion  110 . The tubular portion  110  may be rigid, and made, for example, at least in part of a hard material (e.g., metal). In some embodiments, the tubular portion  110  includes an angled and/or pointed distal tip, to facilitate insertion through an incision in an eye. As illustrated in  FIG. 2 , the tubular portion  110  includes a hollow interior  115 , to facilitate passage of fluid or other material through the cannula  100  and either into or out of the eye. Other embodiments may include a tubular portion  110  made of a softer and/or flexible material, and/or a tubular portion  110  having a size and shape other than that illustrated. 
     With continued reference to  FIGS. 1 and 2 , in some embodiments the tubular portion  110  includes an enlarged proximal end  116  (e.g., generally cup shaped or funnel shaped) with, in one example, a rolled outer periphery  118 . The cannula  100  includes a receptacle  120  coupled to (e.g., releasably coupled to, fixed to, or integrally formed as a single piece with) the enlarged proximal end  116  of the tubular portion  110 . The receptacle  120 , or at least a portion of the receptacle  120 , may be softer than the tubular portion  110  (including the enlarged proximal end  116 ), and made for example at least in part of an elastomeric material. The cannula  100  may slide over or otherwise be coupled to the enlarged proximal end  116 . Other embodiments may include different shapes and sizes for a receptacle  120  than that illustrated. In some embodiments the receptacle  120  is co-molded to the end of the tubular portion  110 . During use, the receptacle  120  is an external portion of the cannula  100  disposed outside the eye at all times. 
     With reference to  FIG. 2 , in the illustrated example embodiment, an internal chamber  130  is disposed within the receptacle  120 . The internal chamber  130  is located adjacent to and opens into the hollow interior  115  of the tubular portion  110 . In the example illustrated in  FIG. 2 , the internal chamber  130  has a tapered diameter that extends to the hollow interior  115  of the tubular portion  110 . In other embodiments, the internal chamber  130  may have a constant cross-sectional diameter, or a different diameter (e.g. tapered in a different direction) other than that illustrated. 
     With continued reference to  FIG. 2 , the receptacle  120  includes a valve  140  within an interior of the receptacle  120 . The receptacle  120  receives components but also acts as a closure (particularly when the valve  140  is closed). In the example illustrated, the valve  140  includes at least one flexible membrane or other flexible structure (e.g., a flap or flaps) that define a slit  145 . In one example, the slit  145  is positioned in a center of the valve  140 . The valve  140  is movable between a closed (e.g., sealed) position and an opened (e.g., unsealed) position. As illustrated in  FIG. 2 , in the closed position “CP” the slit  145  may be tightly closed such that the valve  140  is sealed. When the valve  140  is in the closed position, fluid and other materials are inhibited or prevented from passing through the slit  145  and the valve  140  from the internal chamber  130  and the tubular portion  110 . The valve  140  may thus maintain the fluid pressure inside the eye. With reference to  FIGS. 7 and 8 , in the opened position “OP” the valve  140  is pushed or otherwise deformed by a surgical instrument or other device (e.g., deformed toward the tubular portion  110 ). The force from the surgical instrument or other device expands the slit  145  radially outwardly to form an opening to allow a surgical instrument or device to extend through the valve  140 . Other embodiments include different shapes and sizes of a valve  140  than that shown. 
     With reference to  FIGS. 1 and 2 , the receptacle  120  also includes an external chamber  150 . The external chamber  150  is at an opposite side of the receptacle  120  than the internal chamber  130 , such that the valve  140  is disposed between the internal chamber  130  and the external chamber  150 . The external chamber  150  is disposed adjacent to and is open to the valve  140 , such that fluid or other material may flow through the external chamber  150 , through the valve  140  (when the valve  140  is opened), through the internal chamber  130 , and into the tubular portion  110  (or in a reverse flow). 
     As illustrated in  FIG. 2 , the receptacle  120  also includes at least one engagement feature that is used to couple the cannula  100  to another device (e.g., a surgical instrument, an infusion tubing set, etc.). In the illustrated embodiment, the engagement feature includes the external chamber  150 , as well as a lip  160 . The lip  160  defines at least a portion of the external chamber  150  and is located generally at the end of the receptacle  120 . The lip  160  may be a rigid or flexible protrusion or other structure that extends for example radially inwardly, and/or includes a surface or surfaces that facilitate engagement between the cannula  100  and another device (e.g., a surgical device or infusion tubing set). The lip  160  may extend partially or entirely around the external chamber  150  and/or the end of the receptacle  120  (e.g., circumferentially). As illustrated in  FIG. 2 , the valve  140  is positioned between the lip  160  and the internal chamber  130 . The lip  160  protrudes inwardly (e.g., radially inwardly), thus making the external chamber  150  smaller or narrower near the end of the receptacle  120 . Other embodiments include different shapes and orientations of the lip  160  than that illustrated. The lip  160  may also be positioned at a location different than the location illustrated. 
     With reference to  FIGS. 3 and 4 , the cannula  100  may be coupled to a surgical instrument  200 . The surgical instrument  200  may include, for example, a handle  210 , a needle  220 , and a reinforcing slider  230 . In the example illustrated, the reinforcing slider  230  includes a tubular portion  240  and an end portion  250 . The end portion  250  includes a central passageway  260 . The needle  220  passes through the central passageway  260 . In some embodiments, the central passageway  260  is substantially larger than the needle  220 . The reinforcing slider  230  is movable with respect to handle  210  and the needle  220 , such that the position of the reinforcing slider  230  may be adjusted to vary the length of the portion of the needle  220  that extends past the slider end portion  250 . 
     With continued reference to  FIGS. 3 and 4 , the surgical instrument  200  also includes at least one engagement feature that is used to couple the surgical instrument  200  to the cannula  100 . In the example illustrated, the engagement feature includes a lip  270  disposed at (e.g., extending from, integrally formed as a single piece with, or otherwise coupled to) the end portion  250 . The lip  270  extends (e.g., axially and/or radially outwardly from the end portion  250 ), and as described further below is shaped and sized to engage with at least a portion the lip  160  of the cannula  100 . In other embodiments, the lip  270  may have a different shape, orientation, and/or location. 
     With reference to  FIGS. 5 and 6 , the cannula  100  may also, or alternatively, be coupled to an infusion tubing set  300 . In the example illustrated, the infusion tubing set  300  includes a first connector  310 , a flexible tubing  320  coupled to the first connector  310  at one end of the flexible tubing  320 , and a second connector  330  coupled to the flexible tubing  320  at a second, opposite end of the flexible tubing  320 . The infusion tubing set  300  also includes a central passageway  340  that extends through the first connector  310 . In some embodiments, the second connector  330  may be attached to a source of infusion fluid, which is then delivered through tubing  320  and the central passageway  340  of first connector  310 . 
     With continued reference to  FIG. 6 , the first connector  310  also includes at least one engagement feature that is used to couple the infusion tubing set  300  to the cannula  100 . In the illustrated embodiment, the engagement feature includes a lip  350 . The lip  350  projects radially outwardly, and defines a barb. As described further below, the lip  350  may engage with at least a portion of the lip  160  of the cannula  100 . Other embodiments include different shapes, locations, and orientations of a lip  350  than that illustrated. 
     With reference to  FIGS. 7-9 , the surgical instrument  200  may be coupled to the cannula  100  using the engagement feature(s) on the surgical instrument  200  and the cannula  100 . For example, in the illustrated embodiment the lip  160  of the cannula  100  is disposed at an entrance to the external chamber  150 . The lip  160  projects inwardly, defining an opening. An internal diameter  164  of the opening through the lip  160  is less than an internal diameter  166  of the external chamber  150  adjacent the lip  160 . As illustrated in  FIG. 7 , the lip  160  is also disposed adjacent an external surface  168  at the end of receptacle  120 . 
     With continued reference to  FIGS. 7 and 8 , in the illustrated example embodiment the surgical instrument  200  includes additional engagement features in the form of an external surface  272  at the end portion  250 , and a cylindrical extension  274  projecting from the external surface  272  coaxial with the central passageway  260 . As illustrated in  FIG. 7 , the external surface  272  curves to form a groove or indentation along an area near a base of the cylindrical extension  274 , and the lip  270  forms at least a portion of the cylindrical extension  274 . 
     In the illustrated example, a principal diameter  275  of the cylindrical extension  274  is slightly smaller than the internal diameter  164  formed by the lip  160  on the cannula  100 , enabling the cylindrical extension  274  to slide into the external chamber  150  with limited or no resistance from the lip  160 . In other embodiments, the cylindrical extension  274  may include features with a diameter slightly larger than the internal diameter  164  of a flexible lip  160  so as to provide a slight engagement force between surgical instrument  200  and cannula  100 . In general, however, it must be possible to withdraw the surgical instrument  200  from engagement without applying forces which might pull the cannula  100  out of the eye. 
     When the surgical instrument  200  and the cannula  100  are aligned (and before or after the cylindrical extension  274  has moved into the external chamber  150 ) the needle  220  of the surgical instrument  200  may be advanced through the external chamber  150  and through the rest of cannula  100 , forcing open the valve  140  and advancing into the tubular portion  110 . As illustrated in  FIG. 8 , the external surface  272  of the surgical instrument  200  may come to rest (e.g., be pressed) against the external surface  168  of the cannula  100 . In this position, the surgical instrument  200  and the cannula  100  are fully engaged. 
     In some embodiments, and with reference to  FIG. 9 , a torsional force  30  may initially bend the needle  220  slightly, forcing the lip  270  to slide up against the lip  160 . A torsional force  30  may then be applied to rotate the axis of the cannula  100  without further loading of the needle  220 .  FIG. 9  illustrates force vectors  10  and  11  applied at an interface of the lip  160  and the lip  270 . Note that these are counterbalanced by force vectors  20  and  21  at the interface of the external surfaces  168  and  272 . Very large forces can be applied in this manner while protecting the needle  220  from excessive loading. For the purpose of transmitting such large forces, the lip  160  of the cannula  100  may be rigid (e.g., may be made of metal, hard plastic, or other materials). In the illustrated embodiment, however, the lip  160  is elastic, to allow the cannula  100  to also be coupled to the infusion tubing set  300 . In some embodiments, the needle  220  may pass through the cannula  100  such that forces of engagement that occur when coupling the surgical instrument  200  to the cannula  100  are directed away from the more delicate portions of the surgical instrument  200 . 
     As shown in  FIGS. 10 and 11 , the infusion tubing set  300  may also be coupled to the cannula  100  using the engagement features on the infusion tubing set  300  and the cannula  100 . In the example illustrated, the engagement features on the infusion tubing set  300  include the lip  350  (e.g., barb) described above, a first cylindrical portion  362 , and a second cylindrical portion  366 . The lip  350 , the first cylindrical portion  362 , and second cylindrical portion  366  are coaxially disposed around the central passageway  340 . A diameter  367  of the second cylindrical portion  366  is less than the internal diameter  164  defined by the lip  160  on the cannula  100 . A diameter  365  of the barbed lip  350  is larger than the internal diameter  164 , and in some embodiments may even be slightly larger than the internal diameter  166  of the external chamber  150 . 
     To couple the infusion tubing set  300  to the cannula  100 , the second cylindrical portion  366  is advanced into the opening through the lip  160  on the cannula  100  until the barbed lip  350  on the infusion tubing set  300  comes into contact with the lip  160 . Force is then applied to press the lip  350  through the elastic lip  160  and on into the external chamber  150 . The elastic lip  160  then closes down around the first cylindrical portion  362 . The portion of the receptacle  120  forming the external chamber  150  may also be elastic, so a hermetic seal may be formed around the lip  350 . When in this engaged position ( FIG. 11 ), the second cylindrical portion  366  extends past the external chamber  150  and forces open the valve  140 . Opening of the valve  140  facilitates flow of infusion fluid through the central passageway  340 , the valve  140 , and the internal chamber  130  and into the tubular portion  110 . The infusion of fluid then enters the eye. In this engaged position, the lips  160 ,  350  remain engaged with one another, making it difficult to easily remove the infusion tubing set  300 . 
     With reference to  FIGS. 12 and 13 , in some embodiments the lip  160  of the cannula  100  may be rigid, rather than elastic. In the illustrated embodiment the rigid lip  160  is formed as part of a separate piece from the rest of the cannula  100 , and extends over a portion of the valve  140 , such that the valve  140  is sandwiched between the lip  160  and the rest of the cannula  100 . In other embodiments the lip  160  is formed integrally as a single piece with the rest of the cannula  100 . 
     The lip  160  may be formed, for example, with a slight taper on an inner surface  162 . In the illustrated embodiment, the tapering of the inner surface  162  defines an internal diameter that decreases moving along a direction toward the tubular portion  110 . The first connector  310  may also include a tapered portion  370 . In the illustrated embodiment, the tapered portion  370  decreases in diameter moving along a direction toward the tubular portion  110 . The inner surface  162  tapers at an identical or nearly identical angle as the tapered portion  370 . Other embodiments include different angles and/or tapers for the inner surface  162  and the tapered portion  370  other than that illustrated, as well as different sizes for the lip  160  and the tapered portion  370  other than that illustrated. 
     With continued reference to  FIGS. 12 and 13 , when the tapered portion  370  is pressed into the inner surface  162 , an interference fit is created which holds the cannula  100  and the infusion tubing set  300  together. In some embodiments, the tapered portion  370  of the first connector  310  is at least partially elastic, such that when the tapered portion  370  is pressed into the inner surface  162 , the tapered portion  370  compresses slightly radially inwardly and continues to push radially outwardly, facilitating a tight fit against the rigid lip  160  and the inner surface  162 . As illustrated in  FIG. 13 , once the tapered portion  370  has been inserted into the cannula  100 , the valve  140  is forced open, thereby opening a passageway to the tubular portion  110 . 
     With reference to  FIGS. 14 and 15 , in some embodiments the engagement features of the surgical instrument  200  may include additional features which facilitate use with a cannula  100  having a rigid lip  160 . For example, the cylindrical extension  274  projecting from the external surface  272  may include a radially projecting lip  278  (e.g., defined by an undercut at a distal end of the cylindrical extension  274 ) intended to engage with the rigid lip  160  when a torsional force  30  is applied. Torsional force  30  may initially bend the needle  220  slightly, forcing the cylindrical extension  274  to slide up against the inner surface  162  of lip  160  with projecting lip  278  engaged behind the lip  160 . A torsional force  30  may then be applied to rotate the axis of the cannula  100  without further loading of the needle  220 . As illustrated in  FIG. 15 , force vectors  10  and  11  are applied at an interface of the lip  160  and the lip  278 , and are counterbalanced by force vectors  20  and  21 . 
     At least one purpose of the engagement features described above is to communicate forces between the cannula  100  and some other object. For example, the engagement features described above may serve the purpose of attaching the infusion tubing set  300  to the cannula  100 , and may also serve to communicate forces between the cannula  100  and some portion of the surgical instrument  200 , such that the more delicate portions of the surgical instrument  200  are protected from excessive force. 
     Additionally, and as described above, the lip  160  (and external chamber  150 ) of the cannula  100  may specifically be located with the valve  140  positioned between the lip  160  (and external chamber  150 ) and the internal portion of the cannula  100 . This is in contrast, for example, to cannulas where engagement features are located instead between a valve and an internal portion of the cannula. 
     Additionally, and as described above, engagement features in current cannulas are generally of two principal types. The most common type relies on an interference fit between essentially rigid portions of the cannula and an infusion connector. The second type employs an elastic structure in the cannula to engage a rigid infusion connector. The cannula  100  described above employs for example an elastic structure in the cannula  100 , such that the cannula  100  may be coupled for example to both the infusion tubing set  300  and to the surgical instrument  200 . However, the objectives of the cannula  100  may also be met with a rigid structure. 
     Although various embodiments have been described in detail with reference to certain examples illustrated in the drawings, variations and modifications exist within the scope and spirit of one or more independent aspects described and illustrated.