Patent Publication Number: US-2009240257-A1

Title: Limit Control for IOL Injector

Description:
This invention relates to injectors for foldable intraocular lenses and, more particularly, to a control for adjusting the length to which the injector plunger is extended. 
     BACKGROUND OF THE INVENTION 
     A common ophthalmological surgical technique for treating cataracts and other diseases of the lens is to fractionate, emulsify and remove the diseased lens and replace it with a synthetic, plastic lens. To do so, an incision is made in the eye through which the diseased lens is removed and through which the new lens is inserted. 
     It is desirable to make the incision for removing the diseased lens and inserting the new lens to be as small as possible. This aids in shortening recovery time and limits the leakage of fluid through the incision after surgery without requiring sutures. 
     When originally introduced, replacement intraocular lenses (IOLs) were made from rigid plastics such as polymethylmethacrylate and required a relatively large corneal incision through which the lens would be inserted. Such incisions had to be sutured to limit the loss of fluid from the eye. The development of the soft lens, made from materials such as hydrogels, silicones and soft acrylics made it possible to fold or roll the lens prior to insertion. It is now a common surgical technique to fold such an IOL, insert it through the incision and allow the lens to unfold and position itself within the eye. When folded, the lens needs a much smaller incision for insertion than if the lens were inserted in its fully unfolded state. 
     Examples of foldable IOLs and systems for injecting them are well represented in the prior art. 
     U.S. Pat. No. 5,947,976 (Van Noy et al.) teaches and describes an asymmetric IOL injection cartridge having an asymmetric bore. The IOL is inserted into the cartridge in its unfolded state, and when pushed through the cartridge, is partially folded when it exits the cartridge tip. 
     U.S. Pat. No. 5,976,150 (Copeland) teaches and describes an IOL injection system using a foldable substrate to compress and fold an IOL around an outer edge of the substrate. The folded assembly is then placed in an injector and expressed through the injector nozzle into the eye. 
     U.S. Pat. No. 6,083,231 (Van Noy et al) teaches and describes an asymmetric IOL injection cartridge. This patent is a continuation in part of the previously described U.S. Pat. No. 5,947,976 and adds to the disclosure in the &#39;976 patent a peg used to engage the haptic on an IOL to keep the haptic in position as the lens is injected through the injector nozzle. 
     U.S. Pat. No. 6,143,001 (Brown et al) teaches and describes an asymmetric intraocular lens injection cartridge. This patent is a continuation in part of the previously described U.S. Pat. No. 6,083,231 as well as the &#39;976 patent. Brown et al adds to the teachings of the prior mentioned patents a modified asymmetric bore which acts to fold the IOL as it is forced through the bore and the cartridge nozzle. 
     U.S. Pat. No. 6,398,789 (Capetan) teaches and describes an IOL injector cartridge similar in construction to the cartridge shown in the &#39;976, &#39;231 and &#39;001 patents and which adds to the elements of those patents a heat-retention agent to keep the IOL warmed during the injection process. 
     U.S. Pat. No. 6,537,283 (Van Noy) teaches and describes an IOL shipping case and injection cartridge comprising an injection cartridge to which a case for an unfolded IOL is hingedly attached. The case can be rotated to align the lens with the central bore of the cartridge to let the lens thereafter be pushed through the cartridge and expressed through the cartridge tip. 
     U.S. Pat. No. 4,681,102 (Bartell) teaches and describes apparatus and method for insertion of an IOL where the system consists of an injector and a foldable load chamber within which the unfolded lens is placed. The chamber is then folded shut thereby folding the lens in half and a plunger is used to force the lens from the load chamber through a tip and into the eye. 
     U.S. Patent Application Publication No. 2004/0117012 (Vincent) teaches and describes an injector for an intraocular lens, the injector having a hollow cylindrical body and a plunger that, when pushed into the body, ejects a folded IOL from the injector nozzle. 
     U.S. Pat. No. 6,607,537 (Binder) teaches and describes an injector for implanting a folded intraocular lens, container for storing and transporting the injector and method for injecting the lens in a folded state. The injector has a hollow body within which a folded IOL is placed and a plunger that, when pressed into the body, forces the IOL outward through the injector nozzle. 
     The injectors typified by the foregoing references have plungers with a maximum travel length but lack an adjustment to select a travel length less than maximum. For the surgeon, selecting a travel length is necessary to accommodate variations in the physiology of individual eyes. Some patients have deeper-set eyes or eye lengths that are longer or shorter than others. Using commonly available injectors requires the surgeon to observe the progress of the IOL into the eye and stop pushing the plunger when the surgeon feels the IOL is correctly positioned. 
     A prominent feature of the present invention is reproducibly preset mechanism to intercept the plunger at a point short of its maximum travel and thus allow the surgeon to preselect a length of travel prior to the injection of the IOL. 
     SUMMARY OF THE INVENTION 
     The present invention comprises an injector having a hollow cylindrical body having a first, discharge end and a second, plunger end, and a plunger which is axially slidable within the body. A first end of the plunger is adapted to contact either an IOL or a cartridge containing an IOL and to force the IOL out of the injector or cartridge into the eye. A second end of the plunger has a knob or stop proximate the pushing end, used to grip the plunger and move it into the housing. Located on the housing proximate the second end is a micrometer barrel rotatably and threadedly mounted to the injector housing. When the plunger is fully pushed into the injector housing, the knob contacts the micrometer collar thus halting the inward movement of the plunger. The micrometer collar is rotatably adjustable with respect to the housing thereby altering the position at which the plunger knob contacts the micrometer dial and, thereby, adjusting the distance to which the the plunger extends toward or past the discharge end of the injector. 
     These and other aspects of the present invention will become apparent upon consideration of the accompanying description and the accompanying drawings in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a prior art cartridge injector; 
         FIG. 2  is a perspective view of a preferred embodiment of the present invention showing the plunger fully withdrawn from the housing; 
         FIG. 3  is a perspective view of the injector of  FIG. 2  showing the plunger fully pushed into the injector housing; 
         FIG. 4  is a lateral view of the injector shown in  FIG. 2 ; 
         FIG. 5  is a lateral view of the injector shown in  FIG. 3 ; 
         FIG. 6  is a perspective view of a second embodiment of the present invention showing an injector without an external damping spring; 
         FIG. 7  is a lateral view of the injector shown in  FIG. 6  with the plunger fully withdrawn from the housing; 
         FIG. 8  is a lateral view of the injector shown in  FIG. 6  with the plunger fully pushed into the housing; 
         FIG. 9  is a detailed view of the micrometer dial; 
         FIG. 10  is a lateral view of an adjustment mechanism with preset discrete adjustment steps or positions; and 
         FIG. 11  is an enlarged detail of the adjustment mechanism of  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Referring now to  FIG. 1 , numeral  10  identifies a prior art IOL injector sold by Asico LLC of Westmont, Ill. as its Model No. AE-9045. Injector  10  has an injector body  12  which is hollow and generally cylindrical in cross section. A plunger  14  is slidably received at first injector body end  16 . Plunger  14  terminates in a pusher end  18  adapted to contact and push an IOL. 
     Injector  10  is intended for use with a cartridge into which the IOL is placed and the cartridge is held in cartridge slot  20 . When plunger  14  is pushed into housing  12 , pusher end  18  enters the cartridge, contacts the IOL and forces it out through the cartridge nozzle into the eye. Other types of injectors have hollow cylindrical bodies terminating in a nozzle and have the folded IOL placed within the injector body itself, whereupon the pusher end of the plunger contacts the IOL and forces it through the injector nozzle. The present invention finds utility on injectors designed to handle only a specific type of cartridge or many types of cartridges, or injectors that inject an IOL directly with no cartridge. 
     At the actuation end of the injector  10 , plunger  14  terminates in a knob  22  to which a thumb ring  24  is attached. Knob  22  and ring  24  give the surgeon a firm and positive grip when using injector  10 . 
     When plunger  14  is pushed into housing  12  the IOL is forced either from the cartridge or from the injector body. When using such an injector, the surgeon must determine either by feel or by eye, how far plunger  14  must be advanced into body  12  to force the IOL into a proper position within the eye. 
     Referring now to  FIG. 2 , the numeral  26  identifies an injector having a hollow cylindrical body  28  which slidably receives a plunger  30  at a micrometer plug  32 . The injector shown in  FIG. 2  has a cartridge receiving slot  34  and a finger grip  36 . Plunger  30  terminates at one end with a pusher  38  movable axially and slidably within housing  28  and, at the other end, a plunger knob  40  and a thumb ring  42 . In the embodiment shown in  FIG. 2 , a damping spring  44  is mounted concentrically about plunger  30  intermediate knob  40  and micrometer plug  32 . Spring  44  provides a positive “feel” to the surgeon when, as plunger  30  is advanced into housing  28 , spring  44  is compressed between micrometer plug  32  and knob  40 . When plunger  30  has been advanced a sufficient distance to eject the IOL from either the cartridge or the injector nozzle, spring  44  aids in withdrawing pusher  38  by expanding against knob  40  and moving plunger  30  rearward. In  FIG. 2 , plunger  30  is shown in a position prior to the insertion of an IOL. 
     Referring now to  FIG. 3 , injector  26  is shown with plunger  30  fully axially advanced into housing  28 . As shown in  FIG. 3 , pusher end  38  thus extends fully through cartridge slot  34  and extends beyond injector discharge end  46 . 
     Referring now to  FIG. 4 , injector  26  is shown in a lateral view with plunger  30  withdrawn from housing  28 . Micrometer plug  32  is threadably and rotatably attached to housing  28  such that micrometer plug  32  overlaps injector body end segment  48 . When micrometer knob  32  is rotated in a first direction, it moves relative to end portion  48  in an axial direction toward discharge end  46 . This allows plunger  30  to travel a greater distance before spring  44  is compressed tightly against micrometer plug  32  by knob  40 , thereby stopping the advance of plunger  30  into housing  28 . When rotated in the opposite direction, micrometer plug  32  moves rearwardly or away from delivery end  46 , thus shortening the distance plunger  30  can travel before being stopped against end surface  50  of micrometer plug  32 . 
     Referring now to  FIG. 5 , the injector of  FIG. 4  is shown with plunger  30  fully pushed into housing  28  and with spring  44  compressed fully against micrometer plug surface  50  by knob  40 . This is the maximum distance plunger  30  can travel, and marks the maximum distance pusher end  18  can extend toward or past discharge end  46 . 
     Referring now to  FIG. 6 , the numeral  52  identifies an injector having a plunger  54  terminating in a knob  56 . Plunger  54  is slidably received by a micrometer plug  58  but with no external damping spring. It is well known in the art to provide such injectors either with simply a sliding action undamped by any spring or an internally positioned spring. The remaining components of injector  52  correspond to those discussed in connection with  FIGS. 2-6  above. In particular, micrometer plug  58  is threadedly mounted to injector  52  and is thus axially adjustable as described above. 
     Referring now to  FIG. 7 , a lateral view of injector  52  is shown with plunger  54  withdrawn from injector  52 . 
     Referring now to  FIG. 8 , the injector of  FIG. 7  is shown with plunger  54  fully advanced into injector  52 , and with knob  56  in contact with and thereby limited by rear surface  60  of micrometer plug  58 . As discussed above, the position of micrometer plug  58  determines the extent of travel of plunger  54  and, thereby, the distance the pusher end of plunger  54  will travel. 
     Referring now to  FIG. 9 , an enlarged detailed view of micrometer plug  32  is shown, it being understood that the features of micrometer plug  32  are common to a micrometer plug  58  as well. Plug  32  has a numbered scale  62 , divisions of which, when plug  32  is rotated, come into and out of registry with a scribe line  64  formed on rear housing  66  of injector  26 . In a well-known fashion, the end position of pusher  38  can be reproduceably and accurately set by adjusting micrometer plug  32  to bring a selected scale marking  62  in registry with scribe line  64 . 
     Referring now to  FIG. 10 , the numeral * identifies an injector having a travel adjustment which features discrete, stepped settings rather than the continuously-adjustable action of a micrometer dial. 
     [insert description after drawings received from ASICO] 
     In this fashion, a single injector can be used with a variety of cartridge configurations which may vary in the length of travel of pusher  38  required to expel an IOL from the cartridge. 
     The foregoing invention can readily be adapted and used with injectors having an internal spring, an external spring, a combination of both internal and external springs, or a plunger having no damping spring at all, relying on the frictional engagement between the plunger and the housing to give the injector its “feel”. The invention can also readily be adapted for use with injectors made from metal or plastic. 
     Referring now to  FIG. 10  the numeral  68  identifies a surgical instrument having a plunger  70  received axially into body  72 . An adjusting barrel  74  limits the distance plunger  70  can travel, as described below. 
     In  FIG. 11 , barrel  74  is shown in an enlarged view as having slots  76 ,  78  and  80  formed in a direction parallel to the longitudinal axis of instrument  68 . Preferably, each said slot has a different length, corresponding to a selected distance of travel for plunger  70 . The number and size of such slots is selected to create a range of movement suitable for the use of instrument  68 . 
     A stop tab  82  is formed on or attached to plunger  70  and is sized and shaped to fit into slots  76 ,  78  or  80 . As seen in  FIG. 11 , when tab  82  is aligned with and inserted into slot  78  the inward axial movement of plunger  70  will be interrupted when tab  82  reaches slot end  84 . 
     Plunger  70  is pulled outward from body  72  and stop tab  82  is aligned with a selected slot to make possible a selected distance of travel. This mechanism can be substituted for the micrometer mechanism described heretofore to provide the adjustability required for the injection of an IOL. 
     While the foreging describes a preferred embodiment or embodiments of the present invention, it is to be understood that this description is made by way of example only and is not intended to limit the scope of the present invention. It is expected that alterations and further modifications, as well as other and further applications of the principles of the present invention will occur to others skilled in the art to which the invention relates and, while differing from the foregoing, remain within the spirit and scope of the invention as herein described and claimed. Where means-plus-function clauses are used in the claims such language is intended to cover the structures described herein as performing the recited functions and not only structural equivalents but equivalent structures as well. For the purposes of the present disclosure, two structures that perform the same function within an environment described above may be equivalent structures.