Abstract:
An apparatus for controllably delivering an IOL into the eye of a patient is disclosed. The device is configured for convenient and reliable positioning of a plunger rod assembly at different stages of the IOL injection procedure, such that various aspects of the insertion procedure can be performed precisely and reliably by a user of the device. In addition, the present invention assists the user during the procedure by accurately and consistently positioning the plunger rod assembly prior to ejection of the folded or rolled IOL from the insertion device.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    The present application claims priority to U.S. Provisional Patent Application No. 60/______, filed Sep. 25, 2002, entitled “SYSTEM FOR IOL INSERTION” the contents of which are fully incorporated herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    When a natural lens of the eye becomes occluded, it is conventional practice to remove the occluded lens, such as by phacoemulsification, and replace the natural lens with an artificial intraocular lens (IOL). During cataract surgery, a small incision is made in the cornea and the IOL is implanted in the eye as a replacement for the natural crystalline lens after cataract surgery. Alternatively, an IOL (e.g., phakic IOL) may also be used to alter the optical properties of or provide vision correction to an eye in which the natural lens remains.  
           [0003]    An IOL often includes 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 of the IOL normally includes an optically clear lens. As described above, implantation of an IOL into the eye involves making an incision in the eye. Preferably, the incision is made as small as possible to reduce trauma, speed healing and decrease patient recovery time.  
           [0004]    In order to decrease the size of the corneal incision required for insertion of the IOL, the IOL can be formed of resilient material that can be “folded” or rolled for insertion into the lens capsule. The foldable (deformable) IOL automatically unfolds after it has passed through the incision. A substantial number of instruments have been devised to aid in inserting such a foldable lens into the eye. The advantages of the foldable lens in cataract removal and lens replacement are so significant that the majority of lens replacement procedures are performed with folded lenses inserted into the eye and released therein to assume their initial unfolded state.  
           [0005]    Conventional insertion devices employ a hollow insertion tube having a diameter that permits the folded IOL to pass through the hollow space defined by the tube without permanent deformation. These devices typically include a plunger assembly having a rod, often made of metal, which is moved longitudinally in the hollow space of the device and in contact with the optic of the IOL to push the IOL through the hollow space.  
           [0006]    Several disadvantages are apparent in such insertion devices. For example, pushing, without trapping or holding, the IOL through and out of the hollow space defined by the tube can cause the IOL to be released from the insertion device without precise control. The uncontrolled release of the IOL may damage the eye and/or cause the IOL to be incorrectly positioned within the capsule of the eye.  
           [0007]    Other disadvantages of conventional insertion devices involve the plunger assembly. For example, the metal rod of the insertion device can mark the surface of the optic and/or even tear the optic, particularly when the optic is made of soft materials, such as soft elastomeric silicone polymeric materials. In addition, the metal rod may completely by-pass the IOL in the hollow space. That is, as the rod is being moved distally through the hollow space of the device, the rod may actually pass through a fold in the folded optic. If this occurs, the rod becomes ineffective to push the IOL through the hollow space. This problem has been avoided in the past by increasing the cross-sectional area of the rod. However, a rod with a large cross-sectional area presents its own problems. For example, pushing such a large rod through the hollow space can damage the IOL and/or the inserter or result in an uncontrolled release of the IOL into the eye, possibly with inserter debris being disadvantageously introduced into the eye.  
           [0008]    In view of the foregoing, it is apparent that there is a need for an IOL insertion device that can fold and controllably deliver an IOL into the eye of a patient. In addition, the device should be configured so that the IOL can be inserted through an optimally small incision in the cornea of the eye. There is also a need to provide a method of using such a device that is uncomplicated, efficient and cost effective. Such a device and method should further include properties that reduce the incidence of tissue trauma over a variety of material designs and properties, facilitate proper IOL delivery and improve patient recovery times.  
         BRIEF SUMMARY OF THE INVENTION  
         [0009]    The present invention provides an IOL insertion device that can fold and controllably deliver an IOL into the eye of a patient. The device is configured for convenient and reliable positioning of the plunger rod assembly at different stages of the IOL injection procedure, such that various aspects of the insertion procedure can be performed precisely and reliably by a skilled technician rather than the surgeon. In addition, the present invention assists the surgeon during the procedure by accurately and consistently positioning the plunger rod assembly prior to ejection of the folded or rolled IOL from the insertion instrument.  
           [0010]    It is an object of the present invention to provide an IOL insertion device configured to allow insertion of the IOL through an optimally small incision in the cornea of the eye.  
           [0011]    It is a further object of the present invention to provide an IOL insertion device that accommodates a variety of IOL materials including, but not limited to, silicone and hydrophobic acrylics.  
           [0012]    It is a further object of the present invention to provide an apparatus and methods of use wherein the desired insertion of the IOL is easily, controllably and effectively achieved over a variety of material factors.  
           [0013]    It is a further object of the present invention to provide a method of using an IOL delivery device that is uncomplicated, efficient and cost effective.  
           [0014]    It is a further object of the present invention to provide a device and method that reduce the incidence of tissue trauma, facilitate proper IOL delivery and improve patient recovery times.  
           [0015]    It is a further object of the present invention to provide a spring-biased device that provides a user of the device with correct or sufficient pressure when using the insertion device of the present invention. In this regard, the device creates a continuous back pressure that allows the user to controllably release the IOL into the patient&#39;s eye when the IOL begins to exit the cartridge. As such, even with reduced material/cartridge friction as the IOL exits the cartridge, the potential to overshoot or launch the IOL in the eye too quickly is reduced and/or eliminated. In addition, the device allows the user to apply pressure consistently to the IOL as it moves along the shaft of the device, thereby reducing or eliminating any sudden starts and stops during the injection procedure.  
           [0016]    These and other objects not specifically enumerated here are addressed by the present invention which, in at least one embodiment, may include a device for inserting, controllably releasing and accurately positioning a folded intraocular lens into an eye comprising a plunger rod assembly in communication with an inserter housing, wherein the inserter housing is adapted to house an intraocular lens. The device also includes a first drive mechanism for providing contact between and causing lateral movement of the plunger rod assembly and the intraocular lens within the inserter housing. The device may further include a positioning mechanism for preventing proximal lateral movement of the plunger rod assembly so that the intraocular lens may be accurately positioned within the eye.  
           [0017]    The present invention also contemplates a method of inserting an intraocular lens into an eye. The method includes providing an insertion device comprising a plunger rod assembly, an inserter housing and a control knob assembly. The method also includes providing a cartridge having a folded intraocular lens positioned therein, loading the cartridge into the inserter housing, actuating the control knob assembly to couple a distal end of the plunger rod assembly with the intraocular lens and inserting a distal end of the cartridge into the eye. The method further includes applying a force to the control knob assembly to move the intraocular lens through the cartridge and partially eject the intraocular lens from the cartridge, actuating a latch and pin mechanism of the plunger rod assembly and removing the force to the control knob assembly without causing movement of the plunger rod assembly, positioning the intraocular lens in the eye, applying a force to the control knob assembly to eject the intraocular lens into the eye, and removing the distal end of the cartridge from the eye.  
           [0018]    The present invention further contemplates an intraocular lens insertion device comprising an inserter housing comprising a plunger rod assembly and a control knob assembly, the control knob assembly having an unlocked position and a locked position the device also includes a cartridge for housing an intraocular lens, the cartridge adapted to be received within the inserter housing and engageable with the plunger rod assembly, a drive mechanism in communication with the control knob assembly and the plunger rod assembly and capable of causing lateral movement of the plunger rod assembly via the control knob assembly. The device further includes a biasing mechanism in communication with the plunger rod assembly to limit the lateral movement of the plunger rod assembly, and a locking mechanism in communication with the control knob assembly for preventing lateral movement of the plunger rod assembly when the control knob assembly is in the locked position. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    Other features and advantages of the present invention will be seen as the following description of particular embodiments progresses in conjunction with the drawings, in which:  
         [0020]    [0020]FIG. 1 is perspective view of an embodiment of an insertion device in accordance with the present invention;  
         [0021]    [0021]FIG. 2 is a sectional view of an embodiment of an insertion device in accordance with the present invention;  
         [0022]    [0022]FIG. 3 is an exploded view of an embodiment of an insertion device in accordance with the present invention;  
         [0023]    [0023]FIG. 4 is a perspective view of an embodiment of an intraocular lens holding cartridge in accordance with the present invention;  
         [0024]    [0024]FIG. 5 is a perspective view of an embodiment of a pushing member in accordance with the present invention;  
         [0025]    [0025]FIG. 6 is a side perspective view of an embodiment of a pushing member in accordance with the present invention;  
         [0026]    [0026]FIG. 7 is an end view of an embodiment of a pushing member in accordance with the present invention;  
         [0027]    [0027]FIG. 8 is a perspective view of an embodiment of an elongate body in accordance with the present invention;  
         [0028]    [0028]FIG. 9 is a side perspective view of an embodiment of an elongate body in accordance with the present invention;  
         [0029]    [0029]FIG. 10 is a sectional view of an embodiment of an elongate body in accordance with the present invention;  
         [0030]    [0030]FIG. 11 is an end view of an embodiment of an elongate body in accordance with the present invention;  
         [0031]    [0031]FIG. 12 is a sectional view of a distal end of an embodiment of an elongate body in accordance with the present invention;  
         [0032]    [0032]FIG. 13 is a perspective view of an embodiment of a latch pin in accordance with the present invention;  
         [0033]    [0033]FIG. 14 is an end view of an embodiment of a latch pin in accordance with the present invention;  
         [0034]    [0034]FIG. 15 is a side view of an embodiment of a latch pin in accordance with the present invention;  
         [0035]    [0035]FIG. 16 is a perspective view of an embodiment of a control knob assembly in accordance with the present invention;  
         [0036]    [0036]FIG. 17 is an end view of an embodiment of a control knob assembly in accordance with the present invention;  
         [0037]    [0037]FIG. 18 is a sectional view of an embodiment of a control knob assembly in accordance with the present invention;  
         [0038]    [0038]FIG. 19 is a perspective view of an embodiment of a forward tube in accordance with the present invention;  
         [0039]    [0039]FIG. 20 is a top sectional view of an embodiment of a forward tube in accordance with the present invention;  
         [0040]    [0040]FIG. 21 is a side sectional view of an embodiment of a forward tube in accordance with the present invention;  
         [0041]    [0041]FIG. 22 is an end view of an embodiment of a forward tube in accordance with the present invention;  
         [0042]    [0042]FIG. 23 is another end view of an embodiment of a forward tube in accordance with the present invention;  
         [0043]    [0043]FIG. 24 is a perspective view of an embodiment of a clip in accordance with the present invention;  
         [0044]    [0044]FIG. 25 is a top sectional view of an embodiment of a clip in accordance with, the present invention;  
         [0045]    [0045]FIG. 26 is a side sectional view of an embodiment of a clip in accordance with the present invention;  
         [0046]    [0046]FIG. 27 is a sectional view of a distal end of an embodiment of a clip in accordance with the present invention;  
         [0047]    [0047]FIG. 28 is an end view of an embodiment of a clip in accordance with the present invention;  
         [0048]    FIGS.  29 - 33  illustrate of a method of operating an embodiment of an insertion device in accordance with the present invention; and  
         [0049]    FIGS.  34 - 37  illustrate alternate embodiments of latching mechanisms in accordance with the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0050]    Referring to FIGS.  1 - 3 , an embodiment of an IOL insertion device  10  in accordance with the present invention includes a plunger rod assembly  12 , an inserter housing  14 , a protective sheath  16 , a finger grip  18  and a control knob assembly  20 . The plunger rod assembly  12  includes an elongate body  22  and a pushing member  24  that act to controllably push the IOL out of the cartridge and into the lens capsule (not shown). The inserter housing  14 , which includes a forward tube  26  and a rearward tube  28 , houses the plunger rod assembly  12  and includes a chamber  30  configured to hold the cartridge (not shown) during an insertion procedure. Surrounding the inserter housing  14  are a protective sheath  16  and finger grip  18 . The finger grip  18  and/or control knob (or handle) assembly  20  allow a user of the device  10  to accurately and consistently position the plunger rod assembly  12  for controlled release of the IOL into the chamber of the eye, as explained in further detail below.  
         [0051]    The inserter device  10  of the present invention is used in combination with a lens holding cartridge  32 . Lens holding cartridges  32 , such as those disclosed in U.S. Pat. No. 6,398,788 and U.S. Pat. No. 6,334,862, whose contents are fully incorporated herein by reference, generally include a lens-folding portion  34 , a holding chamber  36  and a hollow injection tube  38 . As shown in FIG. 4, the lens-folding portion  34  includes a loading compartment  40  and integral hinged tabs  42  movable to open and closed states. The open state permits placement of the IOL (not shown) into the lens-folding portion of the cartridge  32 , whereas the closed state folds the IOL and holds it in the resulting cylindrical lumen. During the insertion procedure, explained in further detail below, the folded IOL is advanced through the holding chamber  36  and into the hollow injection tube  38  of the cartridge  32 . The decreased diameter of the injection tube  38 , further folds and compresses the IOL so that the IOL can be passed through an incision in the eye no larger than about 4 mm.  
         [0052]    As noted in the Background of the Invention set forth above, uncontrolled release or ejection of the IOL from the insertion device  10  may damage the eye and/or cause the IOL to be incorrectly positioned within the capsule of the eye. As the present invention substantially eliminates these undesirable characteristics, it is instructive to describe the components of the device  10  that allow for convenient, reliable and controlled delivery of the IOL during an insertion procedure. For this purpose, reference is made to FIGS. 3 and 5- 15 .  
         [0053]    Plunger Rod Assembly  
         [0054]    [0054]FIGS. 3 and 5- 15  illustrate an embodiment of the plunger rod assembly  12  of the present invention. The plunger rod assembly  12  may be fabricated as a disposable, single-use component or a reusable, multi-use component. As such, a variety of materials may be used to fabricate the plunger assembly  12 . These materials include, but are not limited to, metals (such as stainless steel, aluminum or titanium), ceramics, plastics and the like, including combinations thereof. By way of illustrative example, with no limitation being intended or implied, the reusable plunger rod assembly  12  is fabricated from stainless steel to enable autoclaving after each use.  
         [0055]    As shown in FIGS.  5 - 7 , the cylindrically shaped pushing member  24  of the plunger rod assembly  12  includes a blunt or rounded distal tip  44  that contacts and/or pushes the IOL through and out of the cartridge  32  during an insertion procedure. In one embodiment of the invention, the distal tip  44  is fabricated from a relatively soft material, such as silicone polymeric elastomer. In an alternate embodiment, the tip  44  is fabricated from a rigid material and surrounded by a soft, elastomeric coating or cover. Preferably, the distal tip  44  of the pushing member  24  is fabricated from one or more materials and designed to prevent marks or tears in the IOL during the insertion procedure.  
         [0056]    Proximal to the distal tip  44  is an annular channel  46  and several annular chamfered edges  48 . The channel  46  and chamfered edges  48  provide a friction fit to secure the soft tip  44  onto the pushing member  24  of the insertion device  10 . The resulting ridges and grooves of the soft tip  44 , together with additional channels and chamfers formed on the exterior surface of the soft tip  44 , function to hold the soft tip  44  in the fold of the IOL during an insertion procedure. In particular, as the tip  44  passes through a bore in the cartridge  32  and contacts the IOL, the surface configuration of the tip  44  provides additional contacts points with the IOL which facilitate in pushing the IOL through the cartridge  32 .  
         [0057]    Proximal to the channel  46  of the pushing member  24  is an annular rib or projection  50 . The projection  50  functions as a shoulder or stop to properly locate and position the pushing member  24  within the elongate body  22 .  
         [0058]    FIGS.  8 - 14  illustrate the cylindrically shaped elongate body  22  of the plunger rod assembly  12  in accordance with one embodiment of the present invention. As shown in FIGS.  8 - 12 , the distal end  52  of the elongate body  22  includes an axial, interior bore  54  that extends along a portion of the elongate body  22  and is sized to accommodate the proximal end  56  of the pushing member  24 . To assemble the two components  22 ,  24 , the proximal end  56  of the pushing member  24  is simply press-fit into the distal bore  54  of the elongate body  22 . Although the illustrated embodiment of the plunger rod assembly  12  shows the two components  22 ,  24  press-fit together, alternate means of assembling the device  10 , including, but not limited to, snap-fit, pins, adhesives and mating threads, may also be used and are included within the scope of the claimed invention.  
         [0059]    As best seen in FIGS. 8 and 10, the elongate body  22  includes a longitudinal groove or cut-out  58  that extends along a portion of the body  22 . The cut-out  58  forms an opening surrounded by a distal surface  60 , a proximal surface  62  and a bottom surface  64  that extends within the elongate body  22  to a depth approximately one-third of its total diameter. The cut-out  58  provides rotational limits for the elongate body  22  relative to the forward tube  26 . In particular, a pin  65  (best seen in FIG. 3) located near the proximal end of the forward tube  26  cooperates with the cut-out  58  of the elongate body  22 , thereby preventing rotation of the elongate body  22  relative to the forward tube  26 .  
         [0060]    Opposite to the cut-out  58  and near the distal end  52  of the elongate body  22  is a relatively shallow cylindrical hole or opening  66 . The opening  66  is positioned transverse to the longitudinal axis of the elongate body  22  and extends through the bottom surface  58  of the cut-out  58 . As shown in FIG. 3, the opening  66  is sized to accommodate the stem  68  of the latch pin  70 .  
         [0061]    Referring to FIGS.  13 - 15 , one embodiment of the latch pin  70  in accordance with the present invention includes a post  72 , a collar  74  and a stem  68 . As described above, the stem  68  of the latch pin  70  is configured for engagement with the opening  66  in the elongate body  22 . When inserted within the opening  66 , the post  72  of the latch pin  70  protrudes from the exterior surface of the elongate body  22 . As shown in FIGS. 13 and 14, the post  72  includes a plurality of sides or surfaces  76 , with adjacent surfaces forming sharply angled edges  78  there-between. Preferably, one of the post&#39;s edges  78  is not angled but, rather, includes a radius of curvature  80 . In this configuration, the latch finger of the inserter housing (not shown) is able to easily slide over the curved edge  80  of the latch pin  70  and catch or hook onto one of the angled edges  78  of the post  72  during the IOL insertion procedure, as further explained below. A collar  74 , positioned between the post  72  and the stem  68 , provides additional support to further stabilize the latch pin  70  in the opening  66  and prevent it from being unintentionally pulled out of the elongate body  22  during use of the device  10 .  
         [0062]    Although the illustrated embodiment shows the two components  70 ,  22  press-fit together, alternate means of assembling the latch pin  70  into the elongate body  22 , including, but not limited to, snap-fit, pins, adhesives and mating threads, may also be used and are included within the scope of the claimed invention. In another embodiment of the invention, the latch pin  70  and elongate body  22  may be fabricated as a single, continuous component whereby the latch pin  70  is configured, for example, as a projection on the external surface of the elongate body  22  (not shown). Additional component designs and assembly methods, not disclosed herein but known by those skilled in the art, are also included within the scope of the claimed invention.  
         [0063]    As shown in FIG. 3, a helical compression spring  82  and slide ring  84  are located on the external surface near the proximate end of the plunger rod assembly  22 . The slide ring  84 , which is configured as an annular rim or shoulder against which the proximate end of the spring  82  acts, is moveable along a proximate portion of the plunger rod assembly  22 . The spring  82 , which is also moveable along a proximate portion of the plunger rod assembly  22 , acts between the proximate end of the forward tube  26  and the slide ring  84 , thereby forcing the slide ring  84  rearward (proximally) along the plunger rod assembly  22 . However, rearward travel of the slide ring  84  is limited by engagement against an inturned lip and/or one or more pins  86  near the proximate end of the rearward tube  28 . As explained in further detail below, the particular configuration of the slide ring  84  and compression spring  82  limits movement of the plunger rod assembly  12  so that a user of the device can controllably deliver an IOL into the eye of a patient.  
         [0064]    Referring back to FIGS.  8 - 10 , the proximal end of the elongate body  22  of the plunger rod assembly  12  further includes an annular channel or groove  88 . The annular groove  88  is sized to accommodate one or more pins  90  which project from an interior surface of the control knob assembly  20  (not shown) and extend into the annular groove  88  of the plunger rod assembly  12 . As explained in further detail below, moving the control knob assembly  20  along the longitudinal axis of the device results in equivalent longitudinal movement of the plunger rod assembly  12 . However, rotating the control knob assembly  20  about the axis of the device does not produce corresponding rotation of the plunger rod assembly  12 , as the pins  90  of the control knob assembly  20  can freely rotate within the groove  88  and about the axis of the plunger rod assembly  12 . From this description, it is evident that accurate and reliable positioning of the IOL into the eye of the patient are controlled, in part, by the control knob assembly  20  of the present invention. Hence, additional disclosure concerning the structure and function of this assembly is helpful to further understand the present invention. For this purpose, attention is directed to FIGS.  16 - 18 .  
         [0065]    control Knob Assembly  
         [0066]    FIGS.  16 - 18  depict one embodiment of the control knob assembly  20  of the inserter device  10  which includes a cylindrically shaped, hollow stem  92  in communication with a disc-shaped handle  94 . The disc-shaped handle  94  further includes a circular pushing surface  96  and a ring-shaped gripping surface  98 . The pushing surface  96  and ring-shaped gripping surface  98  are configured for a user&#39;s finger(s) to securely press against the surface and rotate the knob assembly  20  during an injection procedure.  
         [0067]    Adjacent the disc-shaped handle  94  is the stem  92  of the control knob assembly  20 . As shown in FIGS. 16 and 18, the bore or internal diameter  100  of the hollow stem  92  is sized to accommodate the proximal end of the plunger rod assembly  12  (not shown). Located on the interior surface and near the proximal end of the stem  92  are one or more pins  90 . The pins  90  are configured to project inwardly from the stem&#39;s interior surface and extend into the annular groove  88  of the plunger rod assembly  12  when assembled therein. As such, the control knob assembly  20  is free to rotate relative to the plunger rod assembly  12  without corresponding rotation of the plunger rod assembly  12 .  
         [0068]    The distal end of the control knob assembly  20  includes one or more threads  102  formed on the stem&#39;s exterior surface. The threaded section  102  of the stem  92  is configured for engagement with one or more inwardly projecting pins  86  formed on the interior surface near the proximal end of the rearward tube  28  of the inserter housing (not shown). As such, when the control knob assembly  20  is moved laterally within the rearward tube  28  of the inserter housing  14 , the pin(s)  86  of the rearward tube  28  abut the distal-most thread  102  of the stem  92  and prevent further lateral movement of the knob assembly  20 . To laterally advance the control knob assembly  20 , the knob assembly  20  must be rotated about its axis. Rotation of the knob assembly  20  causes the pin(s)  86  of the inserter housing  14  to run along the groove of the external threads  102  of the stem  92  resulting in lateral movement of the knob assembly  20 .  
         [0069]    Inserter Housing  
         [0070]    Referring back to FIG. 3, the inserter housing  12 , which includes a forward tube  26  and a rearward tube  28 , houses the plunger rod assembly  12  and includes a chamber  30  configured to hold the cartridge  32  during an insertion procedure. As described above, the rearward tube  28  includes one or more pins  86  near its proximal end which cooperate with external threads  102  on the control knob assembly  20  to control lateral movement of the control knob  20  and plunger rod assemblies  12 . In addition, the rearward tube  28  also includes an annular rib or shoulder  104  located on its exterior surface. The annular rib  104  together with the distal end of the protective sheath  16  secure the finger grip  18  to the device  10  for added positioning control. Although the illustrated embodiment of the device  10  shows the two components press-fit together, alternate means of assembling the device  10 , including, but not limited to, snap-fit, pins, adhesives and mating threads, in addition to forming the finger grip  18  as an integral member of the rearward tube  28  or protective sheath  16 , may also be used and are included within the scope of the claimed invention.  
         [0071]    Located near the distal end of the rearward tube  28  is an attachment section which is used to attach and/or secure the forward tube thereto. As depicted in FIG. 3, the attachment section includes an internally threaded portion  106  configured for engagement with an externally threaded portion  108  on the proximal end of the forward tube  26 . Although the illustrated embodiment of the device  10  shows the two components  26 ,  28  threaded together, alternate means of assembling the components  26 ,  28 , including, but not limited to, snap-fit, pins, and adhesives, may also be used and are included within the scope of the claimed invention.  
         [0072]    Referring to FIGS.  19 - 28 , the forward tube  26  of the inserter housing  12  includes a body member  110  and clip  112 . A slot  114 , formed on the external surface and in communication with the internal bore  116  of the body member  110 , extends along the longitudinal axis of the body member  110  and is configured to allow the loaded lens holding cartridge  32  to be inserted therein. In particular, the wider portion  118  of the slot  114  allows the loaded cartridge  32  to be inserted downward into the interior bore  116  of the body member  110  and slid forward (distally) to the position shown in the FIG. 1. The narrow, distal portion  120  of the slot  114  stabilizes the cartridge  32  and holds the tabs  42  in a closed position.  
         [0073]    As shown in FIGS. 3 and 24- 28 , the clip  112  of the forward tube  26  includes a mounting ring  122  in communication with a latch finger  124 . The mounting ring  122 , which attaches to the mid-section of the forward tube  26 , is axially aligned on the forward tube  26  so that the latch finger  124  extends over and partially within the slot  30 , proximal to the wider portion  114  of the slot  30 . The latch finger  124 , which includes an angled tip  126  at the distal end of the cantilevered arm  128 , is configured to catch or hook onto the latch pin  70  of the plunger rod assembly  12  as the plunger rod assembly  12  is moved toward the distal end of the forward tube  26 . Engagement of the latch finger  124  with the latch pin  70  prevents retraction or proximal movement of the plunger rod assembly  12  thereby enabling a user of the device  10  to controllably release the IOL into the chamber of the eye, as described in further detail below.  
         [0074]    Operation  
         [0075]    The device  10  in accordance with the present invention is prepared for use by first fitting an IOL (not shown) in the lens-holding cartridge  32  and folding or rolling the IOL by manipulation of the cartridge tabs  42 . Next, the cartridge  32  is inserted downward through the wider portion  118  of the slot  114  and forward (distal) such that the tabs  42  fit in the narrower portion  120  of the slot  114 . During this procedure, as shown in FIG. 29, the push rod assembly  112  is retracted rearward (proximal) from the wider portion  118  of the slot  114 . Note that the latch pin  70  is positioned far to the rear (proximally) of the latch finger  124  and the external threads  102  of the control knob assembly  20  are disengaged from the pins  86  of the rearward tube  28 . In addition, the compression spring  82  has forced the slide  82  rearward (proximally) adjacent to the proximate end of the rearward tube  28 .  
         [0076]    With reference to FIG. 30, the control knob assembly  20  is then slid forward (distally) resulting in equivalent distal movement of the plunger rod assembly  12 . The threads  102  of the control knob assembly  20  butt against the pins  86  of the rearward tube  28  at a position in which the distal end  42  of the plunger rod assembly  12  is approximately aligned with the distal end of the lens-folding tabs  42 , i.e., the lens is forced from between the tabs  42  into the holding chamber  36 . In this configuration, the pins  86  block additional linear sliding movement of the plunger rod assembly  12  in the device  10 .  
         [0077]    To further advance the plunger rod assembly  12 , it is necessary to rotate the control knob assembly  20 . In this regard, the external threads  102  cooperate with the pins  86  such that the knob assembly  20  may be turned in a direction to gradually advance the plunger rod assembly  12  from the position shown in FIG. 30 to the position shown in FIG. 31. At the same time, the distal end of the control knob assembly  20  engages the slide  84  and moves the slide  84  distally against the force of the compression spring  82 . The axial extent of the threads  102  is configured to move the distal end of the plunger rod assembly  12  approximately half-way into the holding chamber  36  of the cartridge  32 . Once the proximate end of the externally threaded portion  102  clears the pins  86 , no additional advancement of the plunger rod assembly  12  occurs with continued rotation of the control knob assembly  20 . In addition, an audible “click” will sound when the proximal-most thread  102  clears the pins  86  and the slide  84  and control knob assembly  20  are biased rearwardly (proximally) by the compression spring  82 .  
         [0078]    In the position shown in FIG. 31, the latch pin  70  is positioned generally alongside the center portion of the latch finger  124 . Further advancement of the plunger rod assembly  12  and latch pin  70  are achieved by pressing the control knob assembly  20  toward the distal end of the device  10 , such as by engagement of the handle  94  with the thumb or palm while the fingers (e.g., index and middle fingers) grasp the finger grip  18 . As such, any rotational movement of the finger grip  18  and/or protective sheath  16  may be accomplished independent of longitudinal movement of the pushing member  24  and rotational movement of the control knob assembly  20 . This configuration allows for increased control and manipulation of the device using a single-handed approach, thereby freeing the user&#39;s second hand for other manipulation. Alternatively, a two-handed approach may also be used whereby the user&#39;s second hand is used to rotate the protective sheath, independent of longitudinal movement of the pushing member  24 .  
         [0079]    Referring to FIG. 32, the tip  44  and/or distal end of the plunger rod assembly  12  forces the IOL from the holding chamber  36  and into the ejection tube  38 . As this occurs, the leading edge  80  of the latch pin  70  engages the angled tip  126  of the latch finger  124 , wedging the latch finger  124  sideways and upward in orientation, as shown in FIG. 32. The upward movement of the latch finger  124  is contrary to its natural, centered position. Once the latch pin  70  has cleared the angled tip  126  of the latch finger  124 , the latch finger  124  springs back toward its central, relaxed position. When the latch finger  124  is engaged with the latch pin  70 , the inward (distal) directed force on the control knob assembly  20  applied by the user&#39;s hand is relieved thereby preventing retraction of the plunger rod assembly  12 , as shown in FIG. 33. The user of the device can then use the distal end of the ejection tube  38  as a manipulation tool inside the chamber of the patient&#39;s eye.  
         [0080]    At this point in the procedure, the plunger rod assembly  12  is maintained in a position in which the IOL (not shown) is largely projecting from the distal end of the ejection tube  38 , but has not yet been fully pushed out of the cartridge  32 . This position allows the user of the device  10  to precisely place the IOL without having to maintain pressure on the control knob assembly  20 . When the desired position within the eye has been reached, the knob assembly  20  is further depressed to eject the IOL from the cartridge  32 . At the same time, the latch pin  70  moves distally beyond the distal end of the latch finger  124 , causing the latch finger  124  to spring back to its relaxed condition. As the force on the control knob assembly  20  is relieved, the latch pin  70  slides rearward along and past the latch finger  124  causing the device  10  to return to the position shown in FIG. 31. The ejection tube is then removed from the corneal incision and the parts returned to their position as shown in FIG. 29 for removal of the empty cartridge  32 . At this point, -the device is ready for insertion of a new loaded cartridge.  
         [0081]    In addition to the above-described device configurations and method of use, the present invention contemplates alternative embodiments and applications that are also included within the scope of the claimed invention. For example, alternative latch designs may be used in place of or in combination with the latch pin and latch finger designs.  
         [0082]    In one embodiment, shown in FIG. 34, an off-axis clamp  130  and lock  132  are located near the proximal section of the rearward tube  28 . The off-axis clamp  130  is spring loaded  131  and sized to prevent lateral sliding of the handle  94  in a proximal direction under action of the compression spring  82 . This configuration allows the plunger rod assembly  12  to advance the IOL through the cartridge  32  (not shown) without backlash or spring-back of the handle  94 . To unlock or release the handle  94 , the off-axis clamp  130  is moved in a distal direction toward the finger grip  18 . To completely disengage or unlock the handle  94 , the lock  132  is latched onto the finger grip  18  of the insertion device  10 . The off-axis clamp can be re-engaged with the handle  94  any time throughout the plunger rod translation by simply unlatching the lock  132  from the finger grip  18 . This configuration allows a user to freely latch and unlatch the plunger rod assembly  12  throughout operation of the device  10 .  
         [0083]    In an alternate embodiment, a lock nut  134  and friction collar  136  are used to prevent lateral movement of the plunger rod assembly  12 . As shown in FIG. 35, the lock nut  135  is threaded onto the rearward tube  28  and configured to engage the external surface of a friction collar  136 . As the lock nut  134  is secured onto the rearward tube  28 , the friction enhanced internal surface of the collar  136  engages the plunger rod assembly  12 . Further tightening of the lock nut  134  produces increased friction between the friction collar  136  and plunger rod assembly  12 , thereby preventing any lateral movement of the plunger rod assembly  12 . To release the locking mechanism, the lock nut  134  is unscrewed or loosened, thereby reducing the amount of friction between the plunger rod assembly  12  and friction collar  136  so that the plunger rod assembly can freely move in a lateral direction.  
         [0084]    [0084]FIG. 36 illustrates an alternate embodiment of the locking mechanism of the present invention. As shown in the illustration, the rearward tube  28  includes a spring plunger  138  and release pin  139 . The spring plunger  138  is configured to engage one or more detents  140  located in the handle  94  or plunger rod assembly  12  of the insertion device  10 . The lateral position of the plunger rod assembly  12  is locked in place when the spring plunger  138  engages one of the detents  140 . Activating the release pin  139  causes the spring plunger  138  to disengage from the detent  140 . When the spring plunger  138  is unlocked or disengaged from the detent  140 , the plunger rod assembly  12  can once again freely move in a distal or proximal lateral direction.  
         [0085]    In an alternate embodiment of the invention, a cantilever spring  142  and pin  144  are attached to the rearward tube  28  and configured to engage one or more detents  146  located on the handle  94 . As such, when the plunger rod assembly  12  is advanced, the cantilever spring  142  and pin  144  engage the detents  146  and prevent proximal lateral movement of the plunger rod assembly  12 . To release the plunger rod assembly  12  from this locked position, a release collar  148  is pulled in a proximal direction until it engages the cantilever spring  142  and pin  144 . This in turn disengages the cantilever spring  142  and pin  144  from the detents  146  to once again allow lateral movement of the plunger rod assembly  12 .  
         [0086]    Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.