Abstract:
The present invention is directed to the provision of an intraocular lens delivery device having a plunger with a multi-part plunger tip. The plunger tip includes a first part and a second part wherein the first part releases from the second part during travel of the plunger through the body of a delivery cartridge.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation of patent application Ser. No. 12/615,527 filed Nov. 10, 2009, which; claims priority under 35 U.S.C. §119 to U.S. Provisional Patent Application No. 61/113,627, filed Nov. 12, 2008, the entire contents of which are incorporated herein by reference. 
     
    
     TECHNICAL FIELD OF THE INVENTION 
       [0002]    The present invention relates to an intraocular lens delivery device with a multi-part plunger tip. More particularly, the present invention relates to an intraocular lens delivery device that includes a plunger tip with a first part and a second part wherein the first part releases from the second part during travel of the plunger through the body of a delivery cartridge. 
       BACKGROUND OF THE INVENTION 
       [0003]    The human eye 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 a 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. 
         [0004]    When trauma, age, disease or other malady cause an individual&#39;s natural crystalline 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 often referred to as a cataract. The treatment for this condition is surgical removal of the natural crystalline lens and implantation of an intraocular lens (IOL). 
         [0005]    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. One commonly used injector cartridge design is illustrated in U.S. Pat. No. 4,681,102 (Bartell), and includes a split, longitudinally hinged cartridge. Other designs are illustrated in U.S. Patent Nos. 5,494,484 and 5,499,987 (Feingold) and U.S. Pat. Nos. 5,616,148 and 5,620,450 (Eagles, et al.), the entire contents of which are incorporated herein by reference. Still other cartridges are described in U.S. Pat. No. 5,275,604 (Rheinish, et al.), U.S. Pat. No. 5,653,715 (Reich, et al.) and U.S. Pat. No. 5,947,876 (Van Noy, et al.), the entire contents of which are incorporated herein by reference. 
         [0006]    At least a portion of the lumen of the cartridge typically becomes progressively smaller (i.e., smaller in cross-sectional area) closer to the nozzle or exit point of the cartridge and the IOL typically becomes rolled, folded and/or compressed as it travels along this portion of the lumen. To foster the movement of the IOL along the lumen, it is generally desirable for the tip of plunger to substantially fill the cross-sectional area of the lumen as the plunger is moved along the length of the lumen. By substantially filling the cross-sectional area, the plunger tip helps ensure that an IOL is reliably pushed along the lumen without a portion of the IOL becoming undesirably trapped between the plunger tip and the cartridge. 
         [0007]    To allow the plunger tip to move along the progressively smaller cross-sectional area while continuing to substantially fill the cross-sectional area of the lumen, the plunger tip would traditionally be formed of a soft compressible material that is compressed as it travels along the lumen. This approach can be problematic however. The amount of compression of the plunger tip can become undesirably high particularly toward the nozzle of the cartridge where the cross-sectional area of the lumen can become quite small. In turn, such compression can cause undesirable resistance to travel of the plunger along the lumen as well as other undesirable effects. 
         [0008]    Thus, it would be quite desirable to provide an intraocular lens delivery device having a plunger that includes a plunger tip wherein the plunger tip can compress as it moves along a lumen that is becoming progressively smaller and wherein the plunger tip avoids the development of undesirably high forces associated with conventional soft tips. 
       SUMMARY OF THE INVENTION 
       [0009]    Accordingly, the present invention is directed to an IOL delivery device that includes a delivery cartridge and a plunger having a plunger tip. The delivery cartridge includes an internal surface defining a lumen extending along the cartridge. At least a portion of the lumen has a cross-sectional area that becomes progressively smaller as the cross-sectional area is taken at locations progressively closer to the nozzle. The plunger tip is being defined by an internal member, an external member and an intermediate member, the external member being formed of a relatively compressible material and the intermediate member being formed of a relatively non-compressible material. During delivery of an IOL, the plunger tip travels along the at least a portion of the lumen causing the external member to compress a substantial amount while the intermediate member remains substantially non-compressed. Upon achieving the substantial amount of compression, the internal member releases from the intermediate member and continues the delivery of the IOL. 
         [0010]    The external member is formed of a material typically having an elongation at break that is at least 350%, more typically at least 800%, still more typically at least 1500%. The intermediate member is formed of a material typically having an elongation at break that is no greater than 300%, more typically no greater than 100%, still more typically no greater than 50%. Moreover, the material forming the external member has an elongation at break that is at least 2×, more typically at least 4× and still more typically at least 8× an elongation at break of the material forming the intermediate member. The internal member can be an end portion of a shaft of the plunger. Further, it is contemplated that the delivery cartridge can include a stop feature that stops the travel of the external member after substantial amount of compression of the external member. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a sectional view of a portion of an exemplary IOL delivery device according to an aspect of the present invention. 
           [0012]      FIG. 2  is another sectional view of a portion of the exemplary IOL delivery device shown in  FIG. 1 . 
           [0013]      FIG. 3  is another sectional view of a portion of the exemplary IOL delivery device shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    The present invention is predicated upon the provision of an IOL delivery device that includes a delivery cartridge and a plunger having a multi-part plunger delivery tip. The delivery tip includes a relatively compressible member, a relatively incompressible member and an internal member. The delivery cartridge defines a lumen having a cross-sectional area that becomes progressively smaller as the cross-sectional area is taken closer to a nozzle of the cartridge. During delivery of an IOL, the compressible member of the plunger tip member undergoes substantial compression as the plunger tip travels along the progressively smaller cross-sectional area. During such compression, the relatively incompressible member shields the internal member from being substantially compressed by or lodged within the external member. The internal member of the plunger tip is then released from the relatively compressible member, the relatively incompressible member or both and completes the delivery of the IOL. 
         [0015]    With reference to  FIGS. 1-3 , there is illustrated an exemplary IOL delivery device  10  according to the present invention. The device  10  includes a delivery cartridge  12  having an internal surface  14  defining a lumen  16  extending along the cartridge  12 . The illustrated lumen  16  extends along a length (L) of the cartridge  12 . As can be seen, a cross sectional area  24  of the lumen  16  becomes progressively smaller along at least a portion of the lumen  16  as the cross-sectional area  24  is taken at locations progressively closer to a nozzle (not shown) of the cartridge  12 . 
         [0016]    The device  10  includes a plunger  30  having an elongated member  32  and a plunger tip  32  at a distal end of the elongated member  32 . The plunger tip  32  is defined by an internal member  34 , an external relatively compressible member  36  and an intermediate relatively incompressible member  40 . 
         [0017]    In the embodiment shown, the internal member  34  is a portion of the elongated member  32 . Also as shown, the internal member  34  is integrally formed of the same material and as a singular part with the elongated member  33 . However, it is contemplated that the internal member  34  may be a separate part formed of a separate material and attached to the elongated member  32  directly or through one or more other components. 
         [0018]    The internal member  34  and hence the elongated member  33  may be formed of variety of materials such as metals or polymeric materials. In a preferred embodiment, the internal member is formed of a relatively rigid polymeric material. Exemplary potential polymeric materials include, without limitation, polystyrenes, polypropylenes, polycarbonates, combinations thereof or the like. It is also contemplated that the internal member  34  may itself include its own tip (not shown), which would typically be formed of material that is softer or more compressible than the material of the internal member  34 . 
         [0019]    The intermediate member  40  can also be formed of a variety of materials such as metal or polymeric materials as long as the material is relatively rigid as compared to the material that forms the external member  36 . The material forming the intermediate member  40  is preferably a polymeric material and, like the internal member  34 , suitable materials can include, without limitation, polystyrenes, polypropylenes, polycarbonates, polyetherimides, polyethylether ketones, polyether ether ketones, styrenics (e.g., acrylonitrile butadiene styrene), combinations thereof or the like. Preferably, the material forming the intermediate member  40  has a an elongation at break that is no greater than 300%, more typically no greater than 100%, still more typically no greater than 50%. 
         [0020]    Elongation at break, as used herein, can be determined in accordance with ASTM D412. 
         [0021]    As suggested, the material forming the external member  36  is relatively soft and compressible relative to the material forming the intermediate member  40 . The material forming the external member is also preferably a polymeric material and will typically be entirely or substantially entirely an elastomer (e.g., a thermoset or thermoplastic elastomer). Examples of suitable materials include, without limitation, polyurethanes, butadiene rubbers, styrenic block copolymers, polyolefin blends such as ethylene propylene diene monomer elastomers, thermoplastic copolyesters, thermoplastic polyamides, polyurethanes, combinations thereof or the like. Preferably, the material forming the external member  36  has an elongation at break that is at least 350%, more typically at least 800% and still more typically at least 1500%. It is also preferable that the material of the external member  36  has an elongation at break that is at least 2 33  , more typically at least 4× and still more typically at least 8× an elongation at break of the material forming the intermediate member  40 . As used herein, 2×, 4× and 8× respectively means two times, four times and eight times and as applied to an elongations of 100% would respectively mean 200%, 400% and 800%. 
         [0022]    Again with reference to  FIGS. 1-3 , the illustrated exemplary external member  36  is annular in shape and extends about and/or substantially or entirely surrounds and encircles the intermediate member  40 , the internal member  34  or both. The illustrated exemplary intermediate member  40  is also annular in shape and extends about and/or substantially or entirely surrounds and encircles the internal member  34 . Of course, the skilled artisan will be able to contemplate other arrangements of these members within the scope of the present invention. 
         [0023]    The internal member  34 , the external member  36 , the intermediate member  40  or a combination thereof typically includes one or more retention features  50  for releasably maintaining the intermediate member  40 , the external member  36  or both in the same position relative to the internal member  34 . In the illustrated embodiment the retention features  50  include a protrusion extending from the intermediate member  40  and a cavity disposed in the internal member  34 , the cavity receiving the protrusion for maintaining the aforementioned relative position. Of course, the skilled artisan will be able to contemplate multiple other retention feature configurations within the scope of the present invention. 
         [0024]    During delivery of an IOL, an individual or machine pushes the plunger  30  causing the plunger tip  32  to travel along the lumen  16 . At some point, the plunger tip  32  travels along at least the portion of the lumen  16  having the progressively smaller cross-sectional area  24 . In turn, this causes the external member  36  to compress a substantial amount while the intermediate member  40  remains substantially non-compressed. As used herein, a substantial amount of compression includes a movement of an outer surface of the external member to a distance at least 10%, more typically at least 20% and even more typically at least 30% closer to the intermediate member  40 . For exemplary purposes, 10% closer means 10% of the original distance or, more particularly, for a surface that is 10 millimeters (mm) away, 10% closer means 9 mm away. 
         [0025]    Upon achieving the substantial amount of compression of the external member  36 , the retention features  50  release the internal member  34  from the intermediate member  40 . The internal member  34  then extends out away from the external member  36 , the intermediate member  40  or both and continues to push the IOL to continue the delivery of the IOL typically all of the way out through the nozzle of the cartridge  12 . 
         [0026]    In the embodiment shown, the external member  36  is gradually compressed until enough force is built up against the retention features  50 , causing the retention features  50  to release the internal member  34  from the intermediate and external members  40 ,  36 . However, it is to be understood that the cartridge  12  could include a stop (not shown) that the external member  36  or intermediate member  40  or both contact thereby causing stoppage of travel of the external member  36  and intermediate member  40  and release of the internal member  34  after substantial compression of the external member  36 . For example, and without limitation, the internal lumen  16  could include a portion of rapidly decreasing cross-sectional area or the cartridge  12  could include a protrusion that would quickly stop travel of the external member  36  and intermediate member  40 . 
         [0027]    Advantageously, the plunger tip of the present invention provides a relatively large surface area for pushing an IOL prior to release of the internal member. Moreover, that surface area conforms to the lumen through which it travels at least until the internal member releases from the intermediate and external members. Upon such release, the IOL is sufficiently folded and/or compressed such that the internal member provides sufficient surface area to continue the advancement of the IOL. In this manner, the IOL can be reliably delivered without frictional and/or compressive forces generated by the tip becoming undesirably high. 
         [0028]    It is contemplated that multiple different IOL delivery systems can be modified to include the lumen and plunger of the present invention. Example of such systems are disclosed in, without limitation, U.S. Pat. Nos. 4,615,701; 6,398,789; 6,592,591; 7,033,366; 7,156,852; and 7,156,854, all of which are incorporated herein by reference for all purposes. 
         [0029]    The entire contents of all cited references in this disclosure are specifically incorporated herein by reference. Further, when an amount, concentration, or other value or parameter is given as either a range, preferred range, or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values recited when defining a range. 
         [0030]    Other embodiments of the present invention will be apparent to those skilled in the art from consideration of the present specification and practice of the present invention disclosed herein. It is intended that the present specification and examples be considered as exemplary only with a true scope and spirit of the invention being indicated by the following claims and equivalents thereof.