Abstract:
An intraocular lens (IOL) insertion apparatus including a cartridge with an IOL-receiving chamber, a handpiece into which the cartridge is loaded, and a plunger rod that extends through a lumen in the cartridge to reliably engage the IOL therein. The chamber is stepped in one section to cause the IOL positioned therein to assume a complex curve. A lip or projection on the plunger rod is aligned with the complex curve and intersects the IOL to reliably engage the IOL across its thickness. The cartridge may be a folding type with a pair of arcuate walls and extension wings joined at a living hinge. The stepped section of the chamber may coincide with the location of the hinge.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to apparatus and methods for inserting an intraocular lens through a small incision into an eye. More particularly, the invention relates to such apparatus and methods utilizing a plunger to displace an intraocular lens through a tubular insertion apparatus, wherein the intraocular lens is reliably and safely engaged by the plunger.  
           [0002]    An intraocular lens (IOL) is implanted in the eye, for example, as a replacement for the natural crystalline lens after cataract surgery or to alter the optical properties of (provide vision correction to) an eye in which the natural lens remains. IOLs often include an optic, and preferably at least one flexible fixation member or haptic, which extends from the optic and becomes affixed in the eye to secure the lens in position. The optic normally includes an optically clear lens. Implantation of such IOLs into the eye often involves making an incision in the eye. Making the incision as small as possible reduces trauma and speeds healing.  
           [0003]    IOLs are known which are foldable (deformable) so that the IOL can be inserted into the eye through an incision smaller than the diameter of the lens.  
           [0004]    Some of the most generally accepted insertion apparatus employ a hollow insertion tube having a diameter which permits the folded IOL to pass freely through the tube without permanent deformation, and without causing the surgeon to apply excessive force to overcome friction between the walls of the insertion tube and the IOL. Excessive force can result in the premature ejection of the IOL before the surgeon is ready to position it within the patient&#39;s eye. Such an apparatus can be seen in Brady, U.S. Pat. No. 5,702,402. It would be advantageous to provide IOL insertion apparatus and methods which facilitate the passage of a folded IOL through the apparatus and the insertion of the IOL in the eye in easy, effective and controlled manner while avoiding damage to the IOL and undue trauma to the patient.  
           [0005]    In these generally accepted apparatuses, the insertion tube is held in a handpiece which is coupled to a plunger rod. The plunger rod is moved distally through the insertion tube to urge the IOL to pass through the tube and into the eye.  
           [0006]    An intraocular lens insertion apparatus of this type is disclosed in Brown, et al., U.S. Pat. No. 6,010,510, and includes an injector plunger having a blunt, rounded tip offset from the centerline of the plunger rod. The offset tip assures that the tip is biased downward against the bottom of the cartridge bore to help ensure proper engagement of the intraocular lens therein. However, there is a possibility that the plunger tip might ride underneath or otherwise fail to engage the intraocular lens.  
           [0007]    There is thus a need for a more effective and safe means for engaging and displacing an intraocular lens from within an insertion apparatus.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention provides an improved apparatus for inserting an intraocular lens through an incision into an eye. The apparatus operates in an environment that is similar to existing systems, with a cartridge being loaded into a handpiece, and plunger rod of the handpiece extending through a lumen in the cartridge to push an intraocular lens from an injection tube of the cartridge through an incision in the eye. The apparatus of the present invention provides structure within the cartridge and on the plunger rod that ensures positive engagement between the plunger rod and the intraocular lens to more reliably advance the intraocular lens into the eye in the desired orientation.  
           [0009]    In one embodiment of the invention, an apparatus for inserting a foldable intraocular lens through an incision into an eye includes a cartridge having a longitudinal lumen generally arranged along an axis. The cartridge has a distal injection tube terminating in a mouth opening to the lumen, and a proximal loading end having a generally cylindrical inner surface defining a load chamber sized to contain an intraocular lens and form part of the lumen. The load chamber is configured to cause the foldable intraocular lens to conform around the inner surface substantially in a first curvature to define an inner lens face and an outer lens face. The load chamber is further configured to form a section of the intraocular lens having a second curvature centered outward of the outer lens face.  
           [0010]    The inner surface may be radially stepped to form the section of the intraocular lens having the second curvature. In one embodiment, the inner surface of the loading end is defined by opposed arcuate walls having different radii of curvature, wherein the radially stepped configuration of the inner surface is formed between adjacent axially extending ends of the arcuate walls. Desirably, the cartridge is a folding-type cartridge with the opposed arcuate walls connected at a hinge. Furthermore, the arcuate walls may be aligned at adjacent axially extending first ends and misaligned at adjacent axially extending second ends, such that the second ends define the radially stepped configuration of the inner surface.  
           [0011]    Another aspect of the present invention is an intraocular lens insertion apparatus comprising a cartridge, a handpiece for receiving the cartridge, and a plunger rod coupled to the handpiece. The cartridge has a non-tubular load chamber for receiving an intraocular lens defined by a generally arcuate inner surface interrupted by a radial step. The plunger rod is adapted to be displaced into the load chamber adjacent the radial step. The plunger rod may include an intraocular lens engaging end having a pair spaced lips, wherein a first lip is aligned to pass directly over the radial step and a second lip is spaced toward an axis of load chamber. Desirably, the radial step defines a shoulder projecting into the load chamber to which the intraocular lens conforms. The shoulder is stepped radially inward from adjacent portion of the arcuate inner surface to which the intraocular lens also conforms such that the lens is caused to curve radially inward at a section between the shoulder and the adjacent portion. In this regard, the first lip is aligned to pass over both the shoulder and the adjacent portion and transversely intersect the thickness of the intraocular lens at the section that curves radially inward. Again, the cartridge of the system may be a folding-type cartridge with a pair of opposed arcuate walls and a hinge enabling relative pivoting of the walls. The arcuate walls are opened to permit placement of the intraocular lens in an unfolded state on the inner surface, and walls may then be closed to create the load chamber and fold the intraocular lens therewithin.  
           [0012]    These and other aspects of the present invention will become apparent in the following detailed description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a perspective view of an intraocular lens insertion apparatus of the present invention;  
         [0014]    [0014]FIG. 2 is a schematic perspective drawing showing the placement of an insertion tube of the insertion apparatus of FIG. 1 in the eye;  
         [0015]    [0015]FIG. 3 is an end elevational view of a foldable cartridge of the present invention for use in an insertion system as in FIG. 1 and having an intraocular lens positioned therein;  
         [0016]    [0016]FIG. 4 is a longitudinal sectional view through the foldable cartridge taken along line  4 - 4  of FIG. 3;  
         [0017]    [0017]FIG. 5 is a partially cutaway perspective view of a loading chamber of the cartridge of FIG. 3 having an intraocular lens positioned therein and showing a distal tip of a plunger rod used to displace the lens through the cartridge;  
         [0018]    [0018]FIG. 6A is a partial sectional view taken along line  6 - 6  of FIG. 5 of a proximal portion of the cartridge and an intraocular lens positioned therein, prior to entry of the plunger rod into the cartridge;  
         [0019]    [0019]FIG. 6B is a partial sectional view as in FIG. 6A after entry of the plunger rod into the cartridge and as the rod engages the lens; and  
         [0020]    [0020]FIG. 7 is a transverse sectional view taken along line  7 - 7  of FIG. 6B showing the relative positions of a pair of engaging lips of the plunger rod relative to the intraocular lens at the point of engagement therebetween. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]    [0021]FIG. 1 illustrates an IOL insertion apparatus, shown generally as  10 , in accordance with the present invention. The apparatus  10  comprises a distal housing  12 , a proximal housing  14  and a folding cartridge  16 . Distal housing is operatively coupled to proximal housing  14 . Distal housing  12  includes a through opening  20  through which the folding cartridge  16  can be placed. Distal housing  12  includes a forward opening  22  through which the injection tube  24  of folding cartridge  16  extends distally. Proximal housing  14  includes two oppositely disposed finger supports  26  which extend outwardly from the outer peripheral surface  28  of the proximal housing.  
         [0022]    Apparatus  10  also includes a plunger rod  30  which includes an enlarged proximal end  32  effective to push plunger rod  30  through proximal housing  14 , as will be discussed hereinafter.  
         [0023]    Before proceeding to describe the operation of insertion apparatus  10 , a brief description of the operation of folding cartridge  16  is provided. With reference to FIG. 2, the IOL is to be placed in the eye  40  into an area formerly occupied by the natural lens of the eye. With the IOL in its folded position within apparatus  10 , as described below, injection tube  24  is ready for insertion through an incision  42  in the sclera  44  of eye  40 . Capsular bag  46  protects the posterior segment of the eye  40  and as one of the eye&#39;s constituent parts which is not injured by the insertion of the IOL with the injection tube  24  inserted within the eye  40  and the distal end properly positioned, the surgeon advances plunger rod  30  by manually pushing the plunger rod  30  relative to proximal housing  14 . This action moves IOL distally into injection tube  24 . If needed, IOL can be repositioned in the eye by a small, bent needle or similar tool inserted into the same position.  
         [0024]    [0024]FIG. 2 shows the sclera  44  having an incision through which the distal end portion of the injection tube  24  is passed. Alternately, the incision may be made through the cornea. Injection tube  24  preferably has a sufficiently small cross-section to pass into the eye  40  through an incision of about 3.5 mm or about 3.0 mm in the sclera  44 . Once IOL is properly positioned in eye  40 , and apparatus  10  is withdrawn from the eye, the incision in the sclera may be closed, for example, using conventional techniques. After use, folding cartridge  13 , which is made of a polymeric material, such as polypropylene, preferably is disposed of. Remaining portions of apparatus  10 , which preferably are made of metal, such as surgical grade stainless steel, may be reused after sterilization and disinfection. Any suitable material or materials of construction may be employed in the various components of the apparatus in accordance with the present invention.  
         [0025]    [0025]FIGS. 3 and 4 illustrate an exemplary cartridge  50  of the present invention to be used as explained above with reference to the cartridge  16  of FIG. 1. That is, the combination of the cartridge  50  and intraocular lens (IOL) is coupled with an insertion apparatus  10  and positioned such that a distal tip of the cartridge is within the eye for delivery of the lens. It will be understood that the insertion apparatus  10  as described above is exemplary only, and the cartridge of the present invention may be utilized with other such apparatusses that include a plunger rod for displacing the IOL from within the cartridge. A common problem with such devices is obtaining reliable engagement between the plunger rod and IOL, and the present invention provides an improved cartridge  50  for this purpose.  
         [0026]    The cartridge  50  includes a distal injection tube  52 , and a proximal loading end  54  defining a load chamber  56  therewithin. The injection tube  52  defines an elongate injection lumen  58  that is open to the load chamber  56  and provides a narrowing channel through which an IOL  60  passes. That is, the IOL  60  passes in the distal direction from its illustrated positioned within the load chamber  56  through the narrowing injection lumen  58  and out of a distal mouth  62  of the injection tube  52 . As will be more fully explained below, a plunger rod extends entirely through the elongated lumen of the cartridge  50  and pushes the IOL  60  therethrough.  
         [0027]    The cartridge  50  is desirably of the type that has relatively hinged portions for folding the IOL  60  therewithin. Specifically, the loading end  54  of the IOL  60  is defined by a pair of arcuate walls  70   a,    70   b  pivotally connected at a living hinge  72 . With reference to FIG. 3, and for orientation purposes only, the living hinge  72  is disposed axially along a lower generatrix of the loading end  54 , with the arcuate walls  70   a,    70   b  defining a stepped tubular inner surface and a generally cylindrical load chamber  56  therewithin. The upper ends of the arcuate walls  70   a  contact each other in a closed condition of the loading end  54 , each continuing radially upward in a respective folding wing  74   a,    74   b.  In a preferred embodiment, one of arcuate walls  70   a,    70   b  is fixed with respect to the injection tube  52 , while the other wall pivots with respect to the first wall and injection tube. In the illustrated embodiment, for example, the arcuate wall  70   a  shown on the left in FIG. 3 pivots about the hinge  72  away from the right-hand arcuate wall  70   b  in the direction of arrow  75 . Although not shown, the arcuate wall  70   a  pivots about 180 degrees to open up the loading end  54  and permit placement of the IOL  60  therewithin. Subsequently, the arcuate wall  70   a  is folded in the opposite direction into the configuration shown in FIG. 3, which action also folds the IOL  60  substantially into a tube; the tube defining an inner lens face  76   a  and an outer lens face  76   b.  A rib  77  formed by a radially inward extension of one of the folding wings  74   a,    74   b  may be provided to help retain the IOL  60  in a predetermined position during the folding operation.  
         [0028]    The cartridge  50  of the present invention has a stepped tubular configuration as shown wherein one of the arcuate walls  70   a,    70   b  has a larger radius of curvature than the other. In a preferred embodiment, the upper end of both of the walls  70   a,    70   b  meet at approximately the same location, but the lower ends are misaligned. Therefore, the left side arcuate wall  70   a  may have a larger radius of curvature than the right side wall  70   b  such that the lower end of the left wall is offset below the lower end of the right wall, with a radial step  78  formed therebetween. The curvature of the left side wall  70   a  is centered about an axis  80   a,  while the right side wall  70   b  is centered about a different axis  80   b,  with both of the axes generally being positioned along a vertical midplane of the loading end  54 , as oriented in FIG. 3.  
         [0029]    The step  78  is desirably radially disposed with respect to both arcuate walls  70   a,    70   b,  with the hinge  72  being located at a lower end thereof. In this regard, the hinge  72  is desirably created via removal of material from a step  78 , and from the lower end of the left side arcuate wall  70   a,  to form a notch  82 . In a preferred embodiment, the cartridge  50  is molded from a suitable polymer such as [please provide some alternative materials].  
         [0030]    With respect to the contour of the load chamber  56 , the step  78  creates a shoulder  84  between the inner surfaces of the arcuate walls  70   a,    70   b.  The shoulder  84  is desirably rounded to prevent damage to the IOL  60 , and projects into the load chamber  56  so as to deform the IOL into a multi-curvate (i.e., complex curve) configuration that facilitates engagement thereof by a plunger rod.  
         [0031]    With reference still to FIG. 3, the IOL  60  includes a pair of edges  90   a,    90   b  located at the upper end of the load chamber  56  on either side of the rib  77 , and a midsection  92  located at the lower end of the load chamber. Most IOLs  60  are somewhat thicker in the midsection  92  that the edges  90   a,    90   b.  Furthermore, the IOL  60  is flexible to enable folding, and thus conforms to the contour of the load chamber  56 . Therefore, the IOL  60  closely conforms to the inner arcuate surfaces of the walls  70   a,    70   b,  and has a first majority curvature centered within the load chamber  56 . At the lower end, the shoulder  84  causes the midsection  92  of the IOL  60  to form a second curvature in the opposite direction, creating a point of inflection such that the midsection bows toward the axis of the load chamber  56 . Stated another way, the second curvature at the midsection  92  is centered outward of the outer lens face  76   a  (FIG. 3). A separation space  94  may be created between the midsection  92  and the arcuate wall  70   b  because of this change in curvature and the resiliency of the material.  
         [0032]    Importantly, the midsection  92  follows the left side arcuate wall  70   a  below the level of the shoulder  84  before curving upward and over the shoulder. Of course, the particular contour of the IOL  60  depends on the material, with silicone-based IOLs more closely conforming to the shape of the inner wall of the load chamber  56  than acrylic-based IOLs.  
         [0033]    The section line  4 - 4  in FIG. 3 extends between the folding wings  74   a,    74   b  and is offset in the middle of the load chamber  56  to avoid passing through the step  78  so that the elevation of the IOL  60  below the shoulder  84  is seen in cross-section in FIG. 4. Additionally, the section line  4 - 4  angles through the notch  82  so as to better illustrate the living hinge  72 .  
         [0034]    Now with reference to FIGS.  5 - 7 , interaction of the cartridge  50  with a plunger rod  100  of an insertion apparatus (such as the apparatus  10  in FIG. 1) is shown. The plunger rod  100  may take a variety forms, but is desirably of a type that has an IOL engaging end  102  defined by a pair of lips  104   a,    104   b  spaced apart to define a recess  106  therebetween. Although not shown, the plunger rod  100  has a thickness and a length that permits it to extend entirely through the load chamber  56  and injection lumen  58  of the cartridge  50 . In use, the plunger rod  100  engages the IOL  60  and pushes it through the cartridge  50  and from the mouth  62  into the eye of a patient.  
         [0035]    The plunger rod  100  is rotationally oriented with respect to the cartridge  50  as shown in the figures. That is, at least until engagement with the IOL  60 , lips  104   a,    104   b  are vertically spaced apart with respect to the aforementioned orientation of the cartridge  50 . FIG. 5 illustrates the direction  108  of advancement of the plunger rod  100  into the load chamber  56 , which is only partially shown. Additionally, the plunger rod  100  is desirably centered with respect to the load chamber  56 , and thus passes directly over the shoulder  84 .  
         [0036]    As seen in FIG. 6A, the lower lip  104   b  is aligned to pass closely over the arcuate wall  70   b  and shoulder  84 . As the plunger rod  100  continues distally, as seen in FIG. 6B, the engaging head  102  eventually contacts the IOL  60  as shown. FIG. 7 illustrates the positioning of the lips  104   a,    104   b  with respect to the midsection  92  of the IOL  60 . The projection of lower lip  104   b  extends across the midsection  92  from the outer lens face  76   a  to the inner lens face  76   b  (see FIG. 3). Because of the curvature of the midsection  92  caused by its conformance with the shoulder  84 , the lower lip  104   b  crosses substantially transversely to the thickness of the midsection to insure engagement therewith. In contrast, if the load chamber  56  was defined by a purely cylindrical inner surface, the lower lip  104   b  would be generally aligned parallel to the midsection  92 , and would potentially ride over the midsection and fail to engage it. The present invention insures that the lower lip  104   b  extends completely across the thickness of the midsection  92  which prevents such engagement failure.  
         [0037]    Although not shown, as the plunger rod  100  continues in the distal direction from its position shown in FIG. 6B, the IOL  60  will deform somewhat and be pushed along through the load chamber  56 . Depending on the material of the IOL, the midsection  92  may eventually be captured within the recess  106  between the lips  104   a,    104   b.  Even without such capture, the lower lip  104   b  is positioned so that it cannot ride over the midsection  92  by virtue of the stepped contour of the IOL  60 .  
         [0038]    While this invention has been described with respect of various specific examples and embodiments, it is to be understood that the invention is not limited thereto and that it can be variously practiced within the scope of the following claims.