Patent Document

RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. provisional application Ser. No. 61/185428, filed on Jun. 9, 2009, the contents which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to intraocular lenses (IOLs) and more particularly to devices use to inject IOLs into an eye. 
       BACKGROUND OF THE INVENTION 
       [0003]    The human eye in its simplest terms functions to provide vision by transmitting and refracting light through a clear outer portion called the cornea, and further focusing the image by way of the lens onto the retina at the back of the eye. The quality of the focused image depends on many factors including the size, shape and length of the eye, and the shape and transparency of the cornea and lens. When trauma, age or disease cause the lens to become less transparent, vision deteriorates because of the diminished light which can be transmitted to the retina. This deficiency in the lens of the eye is medically known as a cataract. The treatment for this condition is surgical removal of the lens and implantation of an artificial lens or IOL. 
         [0004]    While early IOLs were made from hard plastic, such as polymethylmethacrylate (PMMA), soft, foldable IOLs made from silicone, soft acrylics and hydrogels have become increasingly popular because of the ability to fold or roll these soft lenses and insert them through a smaller incision. Several methods of rolling or folding the lenses are used. One popular method is an injector cartridge that folds the lenses and provides a relatively small diameter lumen through which the lens may be pushed into the eye, usually by a soft tip plunger, such as the one described in U.S. Pat. No. 4,681,102 (Bartell), which includes a split, longitudinally hinged cartridge. Similar designs are illustrated in U.S. Pat. Nos. 5,494,484 and 5,499,987 (Feingold) and 5,616,148 and 5,620,450 (Eagles, et al.). Other cartridge designs include, for example, U.S. Pat. No. 5,275,604 (Rheinish, et al.) and 5,653,715 (Reich, et al.). 
         [0005]    It is desirable for any combination of cartridge and handpiece used in an intraocular lens delivery system to be comfortable and intuitive for the surgeon to use. An intraocular lens delivery system with a good “feel” for the surgeon can improve the ease and success rate of surgical procedures in which the intraocular lens delivery system is employed. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    In a particular embodiment of the present invention, an intraocular lens delivery system includes an injector body having a bore surrounded by an inner wall. The system further includes a plunger configured to fit within the bore. The system also includes a plurality of deflectable members connected to the plunger and configured to contact the inner wall and to be deflected when the plunger is inserted within the bore. The deflectable members center the shaft and, when inserted within the injector body, contribute to producing a predetermined force resisting advancement of the plunger when deflected in the bore. 
         [0007]    In another embodiment of the present invention, a method of manufacturing an intraocular lens delivery system includes determining a resistance force to advancement of a plunger within an injector body having a bore surrounded by an inner wall. The method also includes determining a shape for a plurality of deflecting members connected to the plunger that will deflect when the plunger is received within the bore of the injector body to contribute to producing the predetermined resistance force. The method further includes manufacturing an intraocular lens delivery system including the injector body, the plunger, and the plurality of deflecting members. 
         [0008]    Other objects, 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 
         [0009]      FIG. 1  illustrates an intraocular lens delivery system according to a particular embodiment of the present invention; 
           [0010]      FIGS. 2A and 2B  show different views of a plunger according to a particular embodiment of the present invention; and 
           [0011]      FIG. 3  is a flowchart showing an example method of manufacturing an intraocular lens delivery system according to another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0012]      FIG. 1  illustrates an intraocular lens delivery system  100  according to a particular embodiment of the present invention. The delivery system  100  includes an injector body  102  having a bore  104  along with a plunger  200  to advance an intraocular lens within the injector body  102 . As used within this specification, the term “injector body,” an example of which is injector body  102 , refers to any portion, components, or collection of components enclosing a bore  104  through which the plunger  200  advances when pushing the intraocular lens. The term “plunger” describes any component advanced through the bore  104  to push an intraocular lens through the injector body, which can be (but need not be) connected to other components of the intraocular lens delivery system  100 . In particular, plungers  200  of various embodiments of the present invention may be made compatible with the lens delivery systems described in detail in U.S. Pat. No. 7,156,854 to Brown et al., which is incorporated herein by reference. 
         [0013]    In particular embodiments, the entire injector body  102  may be formed as a single piece from a suitable material, which may include, for example, polypropylene or polyethylene. In other embodiments, the injector body  102  may be formed by coupling part of a reusable handpiece that forms a continuous bore  104  to a disposable cartridge holding the intraocular lens having a nozzle portion for injecting the intraocular lens through a surgical incision. Various embodiments may also include a lubricious coating within the bore  104  of the injector body  102  to facilitate advancement of the intraocular lens. However, one difficulty with previous intraocular lens delivery systems is that the plungers may also slide too easily within the bore  104 , thus removing any real tactile feedback during advancement of the intraocular lens. Particular embodiments of the present invention provide a solution to this difficulty by producing a resistance to advancement of the plunger  200 , as described in greater detail below. 
         [0014]    The plunger  200  pushes the intraocular lens by advancing a shaft  202  of the plunger  200  through the bore  104 . Coupled to the plunger  200  are two deflectable members  204  on opposite sides of the plunger  200 .  FIGS. 2A and 2B  show additional views of the deflectable members  204  of  FIG. 1 . In the depicted embodiment, the deflectable members  204  are arc-shaped, resilient extensions from the shaft  202  of the plunger  200 . The peaks of the deflectable member  204  are configured to contact and to be deflected by an inner wall of the injector body  102  when the plunger  200  is placed within the bore  104 . The resulting force from the deflection of the deflectable members  204  helps to position the plunger  200  within the bore  104  so that the shaft  202  of the plunger  200  is reliably oriented relative to the intraocular lens. The deflectable members  204  also fit sufficiently tightly within the bore  104  that, when the deflectable members  204  are compressed by the inner wall of the injector body  102 , the friction against the inner wall resists advancement of the plunger  200 . This produces a tactile resistance to the plunger  200  sliding through the bore  104 , which in turn both assists the surgeon in realizing when the plunger  200  is correctly engaged in the intraocular lens delivery system  100  and provides a steady resistance that facilitates controlled application of force during the lens delivery process. 
         [0015]    Because the resistance varies with the force produced by deflection of the deflectable members  204 , it is possible to adjust a design for the deflectable members  204  in order to vary the resistance of the intraocular lens delivery system  100 . Advantageously, the force can be adjusted to correspond to a desired “feel” for surgeons. For example, the resistance may be calibrated based on a survey of physicians to evaluate what resistance feels most suitable. In another example, typical resistance forces for handpieces of intraocular lens delivery systems preferred by various surgeons can be measures, and the deflectable members  204  can be adjusted to produce a suitable resistance. In yet another example, multiple different resistance values can be selected for multiple intraocular lens delivery systems  100 , allowing physicians to choose plungers  200  that are relatively “stiff” (i.e., having high resistance to advancement) or plungers  200  that are relatively “yielding” (i.e., having lower resistance to advancement). 
         [0016]    The deflectable members  204  can be formed separately from the plunger  200  or formed simultaneously as a single piece with the plunger  200  from a selected material suitable for use in ophthalmic applications, e.g., polypropylene. Forming the plunger  200  with the deflectable members  204  as a single piece has an advantage in reducing the number of manufacturing steps using techniques such as injection molding. The resistance force created by the deflectable members  204  can then be adjusted by varying the shape of the deflectable members  204  with respect to a selected material, so that plungers  200  with characteristic resistances can be produced. Alternatively, the same shape for the deflectable members  204  could be used with a variety of selected materials of different resiliency. In general, any adjustment known to be suitable to change the resistance of the plunger  200  to advancement may be employed. 
         [0017]    Multiple deflectable members  204  placed along the plunger  200  could also be used to help the stability of the plunger  200 . Thus, for example, one pair of deflectable members  204  could be placed closer to a distal end of the plunger  200  (“distal” in this context referring to an end of the plunger  200  configured to be placed nearest the incision during lens injection), while another pair is placed nearer to a proximal end (“proximal” referring to the end farthest from the incision during lens injection). Such configurations of deflectable members  204  can help to keep the plunger  200  aligned within the bore  104  as it is advanced. 
         [0018]      FIG. 3  is a flowchart  300  illustrating an example method of manufacturing an intraocular lens delivery system  100  according to a particular embodiment of the present invention. At step  302 , a desired resistance to advancement of a plunger  200  for the intraocular lens delivery system  100  is determined. The desired resistance may be determined based on a survey of physicians using various designs, force measurements of lens delivery systems used by the physicians, theoretical calculations based on the overall sources of resistance in the system  100 , or a combinations of these techniques and/or any other suitable techniques for determining the value. At step  304 , a shape for at least two deflectable members  204  is determined so that the deflectable members  204  hold the plunger  200  within the bore  104  and provide the predetermined resistance to advancement of the plunger  200 . The deflectable members  204  may be designed according to any of the various considerations described above, including consideration of the material for the deflectable members  204  in determining the shape of the deflectable members  204 . Steps  302  and  304  may also be repeatedly iteratively, such as particular designs being made and evaluated by physicians providing feedback used in the next design iteration. Finally, at step  306 , the intraocular lens delivery system  100  is manufactured. Suitable manufacturing techniques may include injection molding, press formation, lathing, or any other technique known for forming the material in the art. 
         [0019]    In a variation of the method presented above, multiple plungers  200  for intraocular lens delivery systems  200  with different resistances can be manufactured by selecting different forces at step  302 . In particular embodiments of this variant method, step  302  may include selection of multiple resistance values based on considerations similar to the ones described above to provide for different surgical needs. Likewise, multiple designs for the deflectable members  204  may be determined that correspond to the different resistances, and step  306  would then include the manufacture of multiple plungers  200  along with injector bodies  102  that may be either common to the various plungers  200  or customized to work with plungers  200  having particular deflectable members  204 . Although this particular variation has been described in detail, it should also be understood that other variations to the manufacturing method consistent with the description of the various embodiments of the intraocular lens delivery system  100  described herein could also be employed. 
         [0020]    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 devices and methods disclosed above may be adopted without departure from the scope of the present invention as claimed.

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