Abstract:
IOL injector system and method for injecting an IOL into an eye which incorporates the benefits of both a rigid and soft plunger tip lens engagement surface while at the same time reduces or eliminates the disadvantages associated therewith.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to intraocular lens injector systems, and more particularly relates to an intraocular lens (“IOL”) injector system having a rigid lens engagement surface for advancing the IOL within the injector body during a first stage of plunger advancement, and a soft lens engagement surface for advancing the IOL during a second stage of plunger advancement which concludes by expressing the IOL from the injector and into an eye. 
         [0002]    IOLs are well known and are used for implanting into an eye to replace the eye&#39;s extracted natural lens in a common surgical procedure known as cataract surgery. There are many different types of IOLs available and the surgeon chooses the IOL according to one or more factors including, for example, the physiology and refractive needs of the patient&#39;s eye. IOLs are configured with an optic and one or more haptics extending from the optic which act as anchoring elements to properly position the IOL within the eye. The IOL is implanted in the eye with the optic aligned along the eye&#39;s visual axis. The IOL may be implanted in a variety of locations within the eye, but typically is positioned within the capsular bag from which the natural lens has been extracted. 
         [0003]    An IOL is implanted in an eye with the aid of an implantation tool such as an IOL injector having a main body portion with a lumen and a plunger telescoping within the lumen. The IOL is placed inside the lumen and the injector tip is inserted into an incision made in the eye. The plunger is then advanced with the lens engagement surface of the plunger tip engaging and pushing the IOL out of the injector tip and into the eye. The injector tip tapers inwardly toward the tip opening causing the IOL to compress as it is pushed further therethrough by the injector tip. Since IOLs are very delicate, there is the chance the plunger tip may damage the IOL as it is pushed, compressed and ultimately ejected from the injector tip by the plunger. The highest (peak) delivery forces against the IOL occur at the injector tip opening, the diameter of which is typically less than about 3 mm, for example. 
         [0004]    Plunger tips are designed with a lens engagement surface for engaging and pushing the IOL through the lumen and out the injector tip opening. Both rigid and soft lens engagement surfaces have been proposed in the prior art with each having their own advantages and disadvantages. For example, a plunger tip having a lens engagement surface made of a rigid material has the benefit of providing a secure and controlled engagement profile with the IOL, particularly as the IOL is advanced within the injector lumen. However, a rigid lens engagement surface also has the disadvantage of possibly damaging the IOL due to the unyielding characteristic of the rigid material, particularly at the point of peak delivery force at the tip opening as described above. On the other hand, a plunger tip having a lens engagement surface made of a soft material has the benefit of yielding to the lens during the period of peak delivery force which reduces the risk of damaging the lens, but has the disadvantage of not providing as secure and controlled engagement profile with the IOL as does a rigid plunger tip lens engagement surface. 
         [0005]    There therefore remains a need for an improved IOL injector system and method for injecting an IOL into an eye which incorporates the benefits of both a rigid and soft plunger tip lens engagement surface while at the same time reduces or eliminates the disadvantages associated therewith. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention addresses, in one or more embodiments thereof, the above-described need by providing an IOL injector system including a plunger assembly slidably disposed within the lumen of an injector body extending to an injector tip having an opening. The plunger assembly includes a first component comprising a rigid body having a lens engagement surface at its distal end and an interference feature. A compressible sleeve is slidably positioned on the first component. The plunger assembly further includes a second component having proximal and distal ends and a central opening extending longitudinally therebetween. The first component is slidably disposed within the central opening of the second component. The first component, the second component, and the sleeve are configured to slide within the lumen in a first state in which the engagement surface is disposed distally of the compressible sleeve and the IOL is carried in the lumen by the rigid lens engagement surface, thus having the benefit of a secure and controlled lens engagement profile as described above. 
         [0007]    The second component of the plunger assembly is configured such that, after the interference feature of the first component interferes with a portion of the injector body, the second component moves relative to the first component causing at least a portion of the sleeve to slide on the first component to become positioned distally of the lens engagement surface. Once the IOL approaches the injector tip, at least a portion of the compressible sleeve advances past the lens engagement surface of the first component and takes over pushing the IOL through the tip and out the tip opening. As mentioned above, the forces imparted on the IOL peak as the IOL is pushed through the tip opening. With the soft, compressible sleeve pushing the IOL out of the tip opening, the benefit of reducing the risk of damage to the IOL during peak delivery force is realized. 
         [0008]    The present invention further addresses, in one or more embodiments thereof, the above-described need by providing a method of injecting an intraocular lens into an eye, comprising the steps of providing a plunger assembly and an injector body comprising a lumen extending to an injector tip, the plunger assembly disposed in the lumen, then sliding the plunger assembly within the lumen in a first state during which a first component comprising a rigid lens engagement surface is in contact with the intraocular lens, then interfering the first component with the injector body, and then sliding a second component relative to the first component to move the sleeve relative to the first component to achieve a second state in which the compressible sleeve is in contact with the IOL and the IOL lens exits the injector tip. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0009]      FIG. 1  is a perspective view of an IOL injector system in accordance with an embodiment of the invention; 
           [0010]      FIG. 2  is a cross-sectional view of the system of  FIG. 1  showing the plunger assembly thereof in the beginning of a first stage of plunger assembly advancement; 
           [0011]      FIG. 3  is the view of  FIG. 2  showing the plunger assembly thereof at the end of the first stage of plunger assembly advancement; 
           [0012]      FIG. 4  is the view of  FIG. 2  showing the plunger assembly thereof in the second, concluding stage of plunger assembly advancement  FIG. 5A  is a plan view of an embodiment of the second component  28  as seen in the direction of arrow  5 A in  FIG. 4 ; 
           [0013]      FIG. 5B  is a plan view of an embodiment of first component  22  as seen in the direction of arrow  5 A in  FIG. 4 ; 
           [0014]      FIG. 6  is a fragmented, longitudinal cross-sectional view of another embodiment of the interface between the first and second components; 
           [0015]      FIG. 7  is an enlarged, fragmented, perspective view of another embodiment of the injector body and interface between the first and second components; and 
           [0016]      FIG. 7A  is a fragmented, cross-sectional view thereof as taken along the line  7 A- 7 A in  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    An IOL is implanted in an eye by a surgeon with the aid of an injector tool such as IOL injector system  10 . Injector system  10  includes an injector body  12  and a plunger assembly  14  which is slidably disposed within a lumen  16  of injector body  12 . Lumen  16  of injector body  12  extends to an injector tip  18  terminating in an opening  18 ′ wherethrough an IOL  20  may pass and thereby expressed from injector system  10  and into an eye (not shown). 
         [0018]    Plunger assembly  14  includes a first component  22  comprising a shaft having a lens engagement surface  24  at distal end  22   a  thereof. First component  22  including lens engagement surface  24  is made from any suitable rigid material such as a metal or plastic, for example. An interference feature  26  is provided at proximal end  22   b  thereof for the purpose to be explained below. 
         [0019]    Plunger assembly  14  further includes a second component  28  having a central opening  30  extending longitudinally between distal and proximal ends  28   a ,  28   b , respectively, and a thumb press  32  located at proximal end  28   b . First component  22  is slidably disposed within central opening  30  of second component  28  and first component  22  are together slidably disposed within lumen  16  generally along longitudinal axis X-X seen in  FIG. 1 . Plunger assembly  14  is advanced within injector body  12  in the manner of a syringe by a user pressing their thumb against thumb press  32  with injector body  12  held between the fingers and against the distal facing surface of flange  12   a.    
         [0020]    As seen in  FIG. 2 , a compressible sleeve  34  is slidably positioned (e.g., via a press fit) on first component  22  in a first state with lens engagement surface  24  located distally of sleeve  34 . Compressible sleeve  34  may be made of any suitable soft material which will compress such as a silicone elastomer, for example. Second component distal end  28   a  is located close to and abuts compressible sleeve  34 . In this first state, thumb press  32  of second component  28  is spaced from interference feature  26  of first component  22 . 
         [0021]      FIGS. 2 to 3  show the first stage of plunger assembly advancement where, in  FIG. 2 , interference feature  26  is spaced from injector body  12 . As a user presses upon thumb press  32  as described above, plunger assembly  14  slides within lumen  16  toward tip  18 . A stop  23  may be provided on first component  22  to prevent sleeve  34  from sliding on first component  22  toward proximal end  22   b  thereof during advancement of plunger assembly  14  within lumen  16 .  FIG. 3  shows the conclusion of the first stage of plunger assembly advancement wherein interference feature  26  of first component  22  is abutting injector body  12  which prevents further advancement of first component  22  within injector body  12 . This concludes the first stage of plunger assembly advancement wherein the lens engagement surface  24  has carried IOL  20  within lumen  16  toward tip  18  and is still located distally of sleeve  34 . 
         [0022]    A variety of configurations may provide the interface between interference feature  26  and second component  28 . In  FIGS. 5A  and B, second component  28  is bifurcated into two portions  28   a  and  28   b  which extend through first and second openings  25   a  and  25   b , respectively, formed in interference feature  26 . Although thumb press  32  and interference feature  26  are shown as generally rectangular in  FIGS. 5A  and B, other shapes are of course possible (e.g., square, circular, oval, etc.). In  FIG. 6 , second component  28  includes a longitudinally extending slot  31  wherethrough interference feature  26 ′ extends. In  FIGS. 7 and 7A , second component  28  is bifurcated into portions  28   c  and  28   d  as in the embodiment of  FIG. 5A  and interference feature  26  is formed as first and second flanges  16   a  and  26   b  which are adapted to extend through the longitudinally extending openings  28   e  and  28   f  defined between portions  28   c  and  28   d , respectively. The length “L” of flanges  26   a ,  26   b  may vary to set the appropriate stopping point for second component  28  relative to body flange  12   a ′. In the embodiment of  FIGS. 7 ,  7 A, lens engagement surface  24 , sleeve  34  and tip  18  are not shown for the sake of clarity. Also, body  12 ′ is shown as circular in cross-section and interference feature  26   a,b  extends in a plane parallel to injector axis X-X while in the embodiments of  FIGS. 1-6 , body  12  is rectangular and interference feature  26  extends in a plane perpendicular to injector axis X-X. Other configurations for the injector parts including the injector body and the sliding interface between first and second components  22  and  28  allowing interference feature  26 ,  26 ′,  26   a,b  to interfere with injector body  12  are of course possible as will be appreciated by those skilled in the art. 
         [0023]    Once interference feature  26 ,  26 ′ is slid into abutting contact with injector body  12 , the user continues pressing on thumb press  32  causing second component  28  to slide in the distal direction relative to the first component  22  which itself is prevented from further advancement due to interference feature  26 ,  26 ′ abutting injector body  12 . During the second stage of plunger assembly advancement occurring between  FIGS. 3 and 4 , the space between interference feature  26  and thumb press  32  closes and second component distal end  28   a  pushes against sleeve  34  causing sleeve  34  to slide in the distal direction (toward injector tip  18 ) with respect to first component  22 . Once the distal-most portion of sleeve  34  slides past lens engagement surface  24 , it makes contact with and disengages IOL  20  from lens engagement surface  24  and begins advancing IOL  20  toward injector tip opening  18 ′. As sleeve  34  is pushed through injector tip  18 , the sleeve compresses due to the inward tapering of the tip  18 . Upon full advancement of second component  28 , sleeve  34  expels IOL  20  from opening  18 ′ as seen in  FIG. 4 . 
         [0024]    It will be appreciated that during the first stage of plunger assembly advancement occurring between  FIGS. 2 and 3 , IOL  20  is carried through lumen  16  by lens engagement surface  24  which is rigid and thus has the benefit of a secure and controlled lens engagement profile as described above. Once interference feature  26 ,  26 ′ abuts injector body  12  and second component  28  is advanced further with respect to the now stationary first component  22 , at least a portion of compressible sleeve  34  is caused to advance past lens engagement surface  24  and thereby takes over pushing lens  20  through tip  18  and out opening  18 ′. As mentioned above, the forces imparted to IOL  20  peak as the IOL  20  is pushed through opening  18 ′. With soft sleeve  34  pushing the IOL  20  out of opening  18 ′, the benefit of reducing the risk of damage to IOL  20  during peak forces imparted on IOL  20  is also realized. 
         [0025]    There is thus provided an IOL injector system and method which obtains the benefit of a rigid lens engagement surface during a first stage of plunger assembly advancement, and the benefit of a soft lens engagement surface during the second or final stage of plunger assembly advancement during peak IOL delivery force.