Abstract:
Intraocular lens inserters and methods of use are disclosed. An example intraocular lens inserter may include an interior assembly having a movable member disposed therein. The movable member is movable in response to a pressure of a compressed gas. In response to the pressure of the compressed gas, the moveable member pressurizes a substantially incompressible fluid. The pressurized substantially incompressible fluid is used to advance a plunger. The plunger advances an intraocular lens through a lumen for insertion into an eye.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/249,185, filed Oct. 31, 2015, the entire contents of which are incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to systems, devices, and methods for inserting an intraocular lens into an eye and, particularly, to utilizing a compressed fluid to insert an intraocular lens into an eye. 
       SUMMARY 
       [0003]    A first aspect of the present disclosure may include an intraocular lens inserter having an inserter body defining a first interior cavity, a compressed gas container coupled to the inserter body, an assembly disposed within the cavity and moveable within the first interior cavity relative to the inserter body, and a plunger. The assembly may include a housing, a second interior cavity formed within the housing, and a moveable member disposed within the second interior cavity and moveable therein relative to the housing. The moveable member may divide the second interior cavity into a first portion adapted to receive a compressed gas from the compressed gas container and a second portion configured to contain a substantially incompressible fluid. The moveable member may be configured to impart a pressure from the pressurized gas to the substantially incompressible fluid contained. The plunger may be movable in response to pressure imparted by the substantially incompressible fluid. 
         [0004]    According to another aspect, the disclosure describes an intraocular lens inserter that may include an inserter body defining a first interior cavity, a pressurized gas canister disposed in the first interior cavity, an assembly disposed in the first interior cavity and moveable therein relative to the inserter body, and an actuator pivotably coupled to the inserter body. The assembly may include a first housing defining a second interior cavity, a valve body disposed at a first end of the first housing, a moveable member disposed in the second interior cavity and movable relative to the first housing, and a piercing member disposed at a second end of the first housing that is opposite the first end. The actuator may include a lever arm that engages the assembly. The actuator may be operable to displace the assembly within the inserter body when the actuator is pivoted relative to the inserter body. 
         [0005]    The various aspects may include one or more of the following features. An actuator may be moveable between an unactuated position and an actuated position. The actuator may be operable to displace the interior assembly between an initial position and a displaced position relative to the compressed gas canister in response to movement of the actuator to the actuated position. A resilient member may be disposed between the housing and the compressed gas canister. The resilient member may be configured to apply a biasing force that urges the assembly towards the initial position when the actuator is moved into the actuated position. The assembly may include a piercing member configured to pierce the compressed gas container. The piercing member may be configured to pierce the compressed gas container in response to displacement of the assembly relative to the gas canister. The intraocular lens inserter may include an orifice, and the assembly may include a valve body. The valve body may include an aperture and a needle valve receivable into the orifice. Displacement of assembly within the inserter body may displace the needle valve relative to the orifice to provide in fluid communication between the second portion of the second interior cavity and the orifice via the aperture. 
         [0006]    The various aspects may also include one or more of the following features. a plunger housing may also be included. The plunger housing may form a third interior cavity configured to receive the plunger. The third interior cavity may be in fluid communication with the orifice, and the substantially incompressible fluid may flow through the aperture and the orifice to apply pressure to the plunger to displace the plunger within the third interior cavity in response to displacement of the assembly within the inserter body. The needle valve may include a tapered surface, and displacement of the needle valve within the orifice may form a gap between the tapered surface of the needle valve and the orifice that varies with an amount by which the needle valve is moved relative to the orifice. 
         [0007]    The various aspects may further include one or more of the following features. The piercing member may be configured to pierce the pressurized gas canister when the assembly is displaced within the inserter body. The assembly may include a passage operable to communicate compressed gas released from the compressed gas canister into the second interior cavity. The moveable member may be displaceable within the second interior cavity in response to pressurized gas released from the pressurized gas canister. The moveable member may divide the interior cavity into a first portion and a second portion, and a substantially incompressible fluid may be disposed in the second portion. The assembly may include a passage between the first portion and the compressed gas canister, and wherein compressed gas released from the compressed gas canister may be communicated to the first portion via the passageway. 
         [0008]    The various aspects may include one or more of the following features. An intraocular lens inserter may also include a plunger housing, a plunger received into a chamber formed in the plunger housing, and an orifice formed in the plunger housing. The orifice may be in fluid communication with the chamber formed in the plunger housing. The valve body may include a needle valve removably received into the orifice. The needle valve may be displaceable from the orifice in response to a displacement of the assembly within the inserter body. Displacement of the needle valve from the orifice may provide fluid communication between a substantially incompressible fluid contained within the second portion of the second interior cavity and the chamber formed in the plunger housing. The assembly may be moveable between a first position in which the needle valve is seated within the orifice and a second position in which the needle valve is unseated from the orifice and the piercing member penetrates the gas canister to release the compressed gas into the first portion in response to articulation of the actuator from a third position to a fourth position. The movable member may be displaceable within the second interior cavity and operable to transmit the pressure of the compressed gas within the first portion to the substantially incompressible fluid contained in the second portion in response to the pressure of the compressed gas. The substantially incompressible fluid may be flowable into the chamber via the orifice in response to displacement of the moveable member, and the plunger may be movable within the chamber in response to pressure transmitted thereto by the substantially incompressible fluid. A biasing member may be disposed between the assembly and the compressed gas canister. The biasing member may apply a biasing force when the assembly is displaced from the first position that urges the assembly back into the first position. The needle valve may include a tapered surface, and a gap may be formed between the tapered surface of the needle valve and the orifice when the needle valve is unseated from the orifice. A size of the gap may be altered by the amount by which the needle valve is displaced relative to the orifice. The size of the gap may be altered in response to an amount by which the actuator is pivoted relative to the inserter body. 
         [0009]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory in nature and are intended to provide an understanding of the present disclosure without limiting the scope of the present disclosure. In that regard, additional aspects, features, and advantages of the present disclosure will be apparent to one skilled in the art from the following detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is an example intraocular lens inserter. 
           [0011]      FIG. 2  shows a top vie of the example intraocular lens inserter of  FIG. 1 . 
           [0012]      FIG. 3  shows a side view of the example intraocular lens inserter shown in  FIG. 1 . 
           [0013]      FIG. 4  is a cross-sectional view of the example intraocular lens inserter shown in  FIG. 1 . 
           [0014]      FIG. 5A  is a partial cross-sectional view of an example intraocular lens inserter that includes a valve body, an interior assembly of the example intraocular lens inserter being in an initial, unarticulated position. 
           [0015]      FIG. 5B  also shows a partial cross-sectional view of an example intraocular lens inserter that includes a bulkhead, an interior assembly of the example intraocular lens inserter being in an initial, unarticulated position. 
           [0016]      FIGS. 6A and 6B  are detail views of the partial cross-sectional view of the example intraocular lens inserter of  FIG. 5  with the interior assembly in an articulated position. 
           [0017]      FIG. 7  is a back view of an example valve body. 
           [0018]      FIG. 8  is a perspective view of an example intraocular lens inserter with a portion of thereof removed. 
           [0019]      FIG. 9  is a perspective view of an example lever lock. 
           [0020]      FIG. 10  is a perspective view of an example intraocular lens inserter with a lever lock installed thereonto. 
           [0021]      FIG. 11  shows a side detail view of a portion of the lever and valve body. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the implementations illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is intended. Any alterations and further modifications to the described devices, instruments, methods, and any further application of the principles of the present disclosure are fully contemplated as would normally occur to one skilled in the art to which the disclosure relates. In particular, it is fully contemplated that the features, components, and/or steps described with respect to one implementation may be combined with the features, components, and/or steps described with respect to other implementations of the present disclosure. 
         [0023]    The present disclosure relates to systems, methods, and devices for inserting an intraocular lens (“IOL”) into an eye. Particularly, the present disclosure describes methods, devices, and systems that utilize a compressed fluid to insert an intraocular lens into an eye. 
         [0024]      FIG. 1  shows a perspective view of an example IOL inserter  100  having a body  102 , a lever  104  that is pivotably coupled to the body  102 , and a nozzle  106  connected to a distal end  108  of the body  102 . The body  102  defines a cavity  103 , as shown in greater detail below in relation to  FIG. 4 . In some instances, the nozzle  106  may be integrally connected to the body  102 . In other instances, the nozzle  106  may be separate from the body  102  and may be coupled to the body  102  via an interlocking relationship. In some instances, the body  102  may have a slender, elongated shape. In some instances, the body  102  may have a first half  110  and a second half  112 . The first half  110  may include a plurality of apertures  114 . The second half  112  may include a plurality of tabs  116  that are received into the apertures  114  to join the first half  110  and the second half  112 . The tabs  116  may form an interlocking fit with the apertures  114 . However, the construction of the body  102  is not so limited. Rather, in some instances, the body  102  may be a single unitary piece. In some instances, the body  102  may include one or more cylindrical pieces. Moreover, the body  102  may be constructed in any desirable manner from any number of components. 
         [0025]    Referring to  FIGS. 1-3 , the body  102  may also include reliefs  118 ,  119 , and  120 . The reliefs  118 ,  119 , and  120  are shallow recesses formed in the body to accommodate, for example, one or more fingers of a user. One or more of the reliefs  118 ,  119 , and  120  may include a textured surface  122  that may provide a user with an improved grip of and control over the IOL inserter  100 . As shown in  FIGS. 1-2 , the reliefs  118  and  119  include texture surfaces  122 . However, the scope is not so limited. Rather any, all, or none of the reliefs  118 ,  119 , and  120  may include a textured surface. Similarly, the lever  104  is shown as including a textured surface  124 . However, in some instances, the lever  104  may not include a textured surface. 
         [0026]    The nozzle  106  includes a distal tip  126  that defines an opening  128 , shown in greater detail in  FIG. 4 . The nozzle  106  may also include a flared portion or wound guard  130 . The distal tip  118  is adapted to be inserted into a wound formed in an eye in order to deliver an IOL thereinto. The wound guard  130  includes an end surface  132  that is operable to contact an exterior surface of an eye in order to limit the depth to which the distal tip  118  may penetrate the eye. In some instance, though, the wound guard  130  may be omitted. 
         [0027]    In some implementations, the IOL inserter  100  may be preloaded. That is, when provided to an end-user, the IOL inserter  100  may have an IOL already present therewithin and ready to deliver. Having the IOL inserter  100  preloaded with an IOL reduces the number of steps a user is required to accomplish before delivering the IOL into a patient. With a reduced number of steps, error and risk associated with delivery of an IOL into a patient may be reduced. Further, an amount of time required to deliver an IOL may also be reduced. 
         [0028]    Referring to  FIGS. 1 and 4 , the nozzle  106  includes a chamber  134  into which an IOL in received. A lumen  135  extends from the chamber  134  to the opening  128 . The lumen  135  is configured to fold an IOL as the IOL passes through the lumen  135 . The IOL may be inserted into the chamber  134  via an opening  136  formed in a first side  138  of the nozzle  106 . The opening  136  may be enclosed by a door  140 . In some instances, the door  140  may be pivotably connected to the nozzle  106  via a hinge  141 . In some instances, the door  140  may be integrally formed with the nozzle  106 . In other instances, the door  140  may be fully removable from the nozzle  106 . 
         [0029]    Referring to  FIGS. 4, 5A, and 5B , the IOL inserter  100  includes a valve body  142 , a moveable member or piston  144 , a bulkhead  146 , a canister  148 , and an inner housing  150 . The inner housing  150  defines a cavity  151 . At least a portion of the valve body  142 , the piston  144 , and the bulkhead  146  may be disposed within the cavity  151  of the inner housing  150 . Further, the valve body  142  and the bulkhead  146  may be fixedly attached to the inner housing  150 . For example, the inner housing  150  may include tabs  152  that are received into an annular recess  154  formed in the valve body  142 . A proximal end  156  of the inner housing  150  may be contoured to conform to the proximal end  158  of the bulkhead  146 , and the inner housing  150  may include a protruding portion  160  that engages a lip  162  formed on the bulkhead  146 , securing the bulkhead  146  relative to the inner housing  150  to maintain a position of the bulkhead relative to the inner housing  150 . However, the valve body  142  and the bulkhead  146  may be fixedly coupled to the inner housing  150  in any desired or suitable manner. As a consequence, the inner housing  150 , the valve body  142 , the piston  144 , and the bulkhead  146  define an assembly  161  and are moveable together within the body  102 . 
         [0030]    The bulkhead  146  includes a piercing member  147 , such as a puncture pin, and the canister  148  may include a lid  149 . The canister  148  confines a compressed gas. In some instances, the canister  148  confines carbon dioxide (CO 2 ). In some instances, the CO 2  within the canister  148  is in liquid form. In still other instances, the CO 2  within the canister  148  may be in a two-phase form. That is, a portion of the CO 2  within the canister may be in a gaseous form while another portion of the CO 2  may be in a liquid form. As explained in more detail below, the piercing member  147  is adapted to pierce the lid  149 . Upon puncture of the lid  149 , the CO 2  escapes the canister  148  in the form of gaseous CO 2 . However, a portion of the CO 2  remaining within the canister  148  may remain in liquid form. The portion of CO 2  remaining in liquid form provides for a constant gas pressure released into the cavity  151 . The CO 2  remaining in liquid form operates to provide a constant gas force as the IOL inserter  100  operates to fold and deliver an IOL. As discussed in more detail below, upon puncture of the lid  149 , the gaseous CO 2  escapes the canister  148  and displaces the piston  144 . Displacement of the piston increases a volume occupied by the gaseous CO 2 . However, because liquid CO 2  is present, the gas pressure is not diminished notwithstanding the increase in volume. Rather, a portion of the liquid CO 2  changes phases forming a gas so that the CO 2  gas pressure remains constant. In some implementations, the amount of liquid CO 2  remaining is selected so that the gas pressure and, hence, driving force of the IOL inserter  100  remains constant throughout the entire stroke of plunger  182 . In other words, the amount of CO 2  may be selected so that the force applied to engage, fold, and expel an IOL out of the IOL inserter remains constant. 
         [0031]    While CO 2  may be used in some implementations, any gas may be used. Still further, in some instances, the canister  148  may not include a lid, and the piercing member  147  may puncture the canister  148  at any desired or suitable location. 
         [0032]    The piston  144  is slideable within the cavity  151  and relative to the inner housing  150 . The piston  144  divides the cavity  151  into a first portion  153  and a second portion  155 . The piston  144  may include a seals  164  that engage an inner surface  166  of the inner housing  150 . The seals  164  are adapted to provide a fluid-tight or substantially fluid-tight seal between the inner housing  150  and the piston  144 . In some implementations, the each of the seals  164  may be disposed in corresponding annular grooves  168  formed in the piston  144 . In some instances, the seals  164  may be O-rings. However, the seals  164  may be any desired or suitable material or device operable to provide a fluid-tight or substantially-fluid tight seal between the inner housing  150  and the piston  144 . Further, in some instances, the seals  164  may be coupled to the piston  144  in any desired or suitable manner. For example, the seals  164  may be bonded to the piston  146 , such as with an adhesive, ultrasonic weld, or any other type of bonding manner. 
         [0033]    The valve body  142  may also include seals  170  that engage the inner surface  166  of the inner housing  150 . The seals  170  may be similar to the seals  164 . For example, the seals  170  may be O-rings disposed in the annular groove  172 . However, in other instances, the seals  170  may be any desired or suitable sealing material attached or fitted to the valve body  142  in any desired or suitable manner. 
         [0034]    The canister  148  may have a fixed position relative to the housing  102 . The canister  148  may include a neck portion  174  that is received into an opening  176  formed in the proximal end  156  of the inner housing  150 . A seal  178  is disposed circumferentially between a portion of the neck portion  174  and inner surface  166  of the inner housing  150 . In some instances, the seal  178  may be an  0 -ring. Further, the seal  178  may be contained within a compartment  180  formed at the proximal end  156  of the inner housing  150 . The seal  178  is adapted to provide a fluid-tight or substantially fluid-tight seal between the inner housing  150  and the canister  148 . As also shown in  FIG. 4 , a biasing member  181  may be disposed between canister  148  and the inner housing  150 . In some instances, the biasing member  181  may be a spring. Particularly, in some instances, the biasing member  181  may be a coil spring, a tapered coil spring, or any other type of device operable to apply a biasing force. 
         [0035]    Referring to  FIGS. 5A, 5B, 6A, and 6B , the IOL inserter  100  may also include a plunger  182  and a plunger housing  184 .  FIG. 5  illustrates a portion of the IOL inserter  100  with the assembly  161  in an initial, unactuated position. In this position, the needle valve  206  is seated within an orifice  190 , particularly an enlarged portion  193  of the orifice  190 . The orifice  190  also includes a reduced portion  197 . The reduced portion  197  may extend distally from the enlarged portion  193 .  FIG. 6  illustrates the portion of the IOL inserter  100  shown in  FIG. 5  with the assembly  161  in an articulated position. In the articulated position, the piercing member  147  has pierced and extends into the canister  148  and the needle valve  206  is unseated from the orifice  190 . 
         [0036]    While  FIGS. 5A, 5B, 6A, and 6B  show the orifice  190  as including an enlarged portion  193  and a reduced portion  197 , the scope of the disclosure is not so limited. Rather, in some implementations, the orifice  190  may omit the enlarged portion  193 . For example, in some implementations, the orifice  190  may form a passage having a uniform cross-sectional shape. In such instances, a valve, such as a needle valve similar to needle valve  206 , may include a valve body that extends into an end of the orifice to control fluid flow through the orifice. 
         [0037]    In other instances, the valve body may abut a valve seat formed at an end of the orifice to control fluid flow through the orifice. For example, the valve seat may be a portion of an end surface of an insert, which may be similar to insert  192 , through which the orifice is formed. The portion of the end surface forming the valve seat may surround the orifice opening formed in the end surface. When the valve body is in contact with the valve seat, fluid flow through the orifice is prevented. When the valve body is displaced from the valve seat, fluid is permitted to flow through the orifice. An orifice and valve body configuration of this type may form an on/off valve such that, when the valve body engages the valve seat, the valve is in an “off” configuration preventing fluid flow. When the valve body is displaced from the valve seat, the valve is in an “on” configuration permitting fluid flow. Further, once the valve is placed in the “on” configuration, the fluid flow rate through the orifice is substantially constant and unchanging notwithstanding the amount by which the valve body is separated from the valve seat. 
         [0038]    Continuing with reference to  FIGS. 5A, 5B, 6A, and 6B , the plunger  182  is disposed within a cavity  186  formed in the plunger housing  184 , and a portion of the plunger housing  184  is received in a cavity  188  formed in the valve body  142 . The plunger  182  is slideable within the cavity  186 . The orifice  190  is formed within a passage  195  of the plunger housing  184 . The passage  195  and the cavity  186  are in fluid communication with each other. The orifice  190  may be formed by an insert  192  that is disposed within the passage  195 . As indicated above, the enlarged portion  193  of the orifice  190  is adapted to receive a needle valve  206 , which is discussed in more detail below. In some instances, the orifice  190  may have a size of 0.10 mm to 1.0 mm. In other instances, the size of the orifice  190  may be larger or smaller than the indicated range. For example, in some instances, the orifice  190  may have a size of 0.005 mm to 0.05 mm. More generally, the size of the orifice  190  may be any desired size. In other instances, the orifice  190  may be integrally formed within the plunger housing  184 , e.g., within the passage  195  of the plunger housing  184 . 
         [0039]    One or more seals  194  may be disposed between an inner surface  196  of the passage  188  and plunger housing  184 . In some instances, the seals  194  may be disposed in annular grooves  198  formed in the proximal end  200  of the plunger housing  184 . Similar to seals  164  and  170 , described above, the one or more seals  194  may be one or more O-rings or any other desired or suitable sealing device or material adapted to provide a fluid-tight or substantially fluid-tight seal between the plunger housing  184  and the valve body  142 . 
         [0040]    The plunger  182  may also include a sealing member  202  disposed between an inner surface  204  of the cavity  186  and the plunger  182 . The sealing member  202  may be formed from any desired or suitable material and is adapted to provide a fluid-tight or substantially fluid-tight seal between the plunger housing  184  and the plunger  182 . 
         [0041]    The valve body  142  also includes a needle valve  206  at a proximal end  208  thereof. One or more apertures  210  may be formed in the proximal end  208  of the valve body  142 . The one or more apertures  210  provide fluid communication between the cavity  151  and cavity  188 . The needle valve  206  extends into the enlarged portion  193  of the orifice  190 . When the assembly  161  is in an unactuated position, the needle valve  206  may be seated within the orifice  190 , sealing off the cavity  151  from the cavity  186 . 
         [0042]    In some instances, the needle valve  206  may have a tapered shape. For example, the needle valve  206  may taper from a proximal end  212  to a distal tip  214 . In some instances, the enlarged portion  193  of the orifice  190  may have a constant cross-sectional size. However, the scope of the disclosure is not so limited. Rather, in some instances, the needle valve  206  may have a constant cross-sectional shape, and the enlarged portion  193  of the orifice  190  may be flared. In still other instances, the needle valve  206  may have a tapered shape and the enlarged portion  193  of the orifice  190  may be flared. In still other implementations, the needle valve  206  and the enlarged portion  193  of the orifice  190  may have constant cross-sectional shapes. As discussed in more detail below, the needle valve  206  is moveable relative to the orifice  190 . 
         [0043]      FIG. 7  shows a proximal end view of the valve body  142 . In this example, the valve body  142  includes three apertures  210 . However, the valve body  142  may include one, two, or any number of apertures  210 . 
         [0044]    A fluid may be disposed in the second portion  155  of the cavity  151  between the piston  144  and the valve body  142 . In some instances, the fluid may be a substantially incompressible fluid, such as a liquid. Example liquids include an oil (such as a silicone oil), propylene glycol, glycerin, water, saline, or any other substantially incompressible fluid. The seals  164  and  170  retain the fluid between the piston  144  and the valve body  142 . 
         [0045]    Referring to  FIGS. 8 , the lever  104  includes protrusions  216 . One of the protrusions  216  is shown, while the other is provided on a side of the lever  104  opposite the side shown in  FIG. 8 . The protrusions  216  may be integrally formed in the lever  104 , or, in other instances, the protrusions  216  may be separate components added to the lever  104 . Each of the protrusions  216  is received into mating receptacles formed in the body  102 . The protrusions  216  and mating receptacles define a pivoting axis  218  of the lever  102 . Thus, when the lever is depressed, the lever  104  pivots about this pivoting axis  218 . 
         [0046]    Referring to  FIGS. 8 and 11 , the lever  104  includes lever arms or legs  220  that are received into recesses  222  formed in the valve body  142 . The legs  220  are operable to displace the valve body  142 , piston  144 , and bulkhead  146  proximally when the lever  104  is depressed. For example, when the lever  104  is depressed, a corner edge  221  of the leg  220  contacts a surface  223  of the recess  222 . As the lever  104  continues to be depressed, the legs  220  swing proximally, resulting in displacement of the valve body  142  (and, consequently, the assembly  161 ) in the proximal direction. 
         [0047]    The biasing member  181  may provide a dual function.  FIG. 5  shows the inner housing  150  in an unactuated position. The biasing member  181  may provide a biasing force to maintain the inner housing  150  in the unactuated position. This may be desirable during shipping and/or handling of the IOL inserter  100  prior to use. Thus, in this condition, the biasing member  181  aids in preventing unintended operation of the IOL inserter  100 . The biasing member  181  also provides a return force during actuation of the IOL inserter  100  and the associated displacement of the inner housing  150 , as shown in  FIGS. 6A and 6B . 
         [0048]    In operation, a user grasps the body  102  of the IOL injector  100  and inserts the distal tip  126  into a wound formed in an eye. In some instances, the distal tip  126  may be advanced through the wound until the end surface  132  of the wound guard  130  contacts an outer surface of the eye. The lever  104  may then be depressed. As explained above, depressing the lever  104  moves the assembly  161  proximally as a result of the interaction between the legs  220  of the lever  104  and the recesses  222  formed in the valve body  142 . As the valve body  142 , piston  144 , inner housing  150 , and bulkhead  146  are moved proximally, the piercing member  147  pierces the lid  149  of the canister  148 . In addition, the needle valve  206  is moved distally, unseating the needle valve  206  from the orifice  190 , such as the enlarged portion  193  of the orifice  190 . As a result, fluid communication between cavity  188  and the passage  204  is provided. Additionally, the biasing member  181  is compressed between the inner housing  150  and the canister  148 . Thus, as the lever  104  is depressed, the lid  149  of the canister  148  is punctured and the needle valve  206  is unseated simultaneously. 
         [0049]    Puncture of the lid  149  releases the compressed gas contained therein. The released gas passes through a passage  224  formed through the bulkhead  146  and impinges upon the proximal end  226  of the piston  144 . The gas pressure applied to the piston  144  moves the piston  144  distally within the cavity  151  of the inner housing  150 . As mentioned above, in some instances, a portion of the material contained within the canister  148  remains in liquid form. This liquid provides an additional volume of gas to fill a portion of the cavity  151  between the bulkhead  146  and the piston  144  that results as the piston moves distally. The portion of liquid within the canister  148  is available to vaporize and fill this increasing volume, thereby maintaining a substantially constant gas pressure on the piston  144  during operation of the IOL inserter  100 . 
         [0050]    As the piston  144  travels distally within the inner housing  150 , the piston  144  forces the liquid contained within the second portion  155  of the cavity  151  into the orifice  190 . The liquid passes through the orifice  190  and impinges upon the proximal end of the plunger  202  and displaces the plunger  202  distally. While the lever  104  remains depressed, the plunger  202  will continue to be displaced distally. As the plunger  202  moves distally, the plunger tip  228  engages the IOL disposed in the chamber  134  and displaces the IOL distally, folding the IOL in the process. As the lever  104  remains depressed, the displacement of the plunger  202  continues, causing the folded IOL to emerge from the opening  128  and, ultimately, to be fully expelled from the IOL inserter  100 . 
         [0051]    In some instances, the rate at which the plunger  202  may be made to move may be varied by the amount by which the lever  104  is depressed. For example, if a user desires a low rate of advancement, the user may depress the lever  104  only a small amount. If a user desires a larger rate of advancement, the lever  104  may be depress a larger amount. A change in the rate of advancement of the plunger  202  caused by a variation in the amount by which the lever  104  is depressed may be, for example, the result of a tapered shape of the needle valve  206 . As the amount by which the needle valve  206  is withdrawn from the enlarged portion  193  of the orifice  190 , an annular space formed between the proximal end of the enlarged portion  193  and the needle valve  206  increases due to the tapered shape of the needle valve  206 . As this annular space increases, the fluid flow resistance of liquid decreases, thereby resulting in a higher hydraulic flow being exerted against the plunger  202 . As a result, the rate of movement of the plunger  202  increases. As the amount by which the needle valve  206  is further withdrawn, the cross sectional area of the annular gap increases to exceed the cross sectional area of the orifice  190 , thereby imparting a throttling limit to the flow exerted against the plunger  202 . As a result, the rate of movement of the plunger  202  is controlled to an upper limit defined by the orifice  190  and the viscosity of the liquid. 
         [0052]    As movement of the plunger  202  continues, such as distal movement through the cavity  186  formed in the plunger housing  184 , a distal tip of the plunger  202  contacts an intraocular lens housed within the chamber  134  and displaces the intraocular lens distally within the chamber  134  and lumen  135 . As the intraocular lens is advanced by the plunger  202 , the intraocular lens is folded and ultimately expelled from the IOL inserter  100  via the opening  128 . 
         [0053]    The rate at which the plunge  202  may be advanced may be varied by the amount by which the lever  104  is depressed. In some instances, the relationship between the rate at which the plunger  202  is advanced and an amount by which the lever  104  is depressed may be a linear relationship. In other instances, this relationship may be nonlinear. Further, in some instances, when the lever  104  is released, the lever  104  returns to an initial position, such as due to the biasing force provided by the biasing member  181 , urging the assembly  161  distally and returning the assembly  161  to its initial position. As a result, the needle valve  206  reseats within the orifice  190 , sealing the orifice  190  and preventing the fluid within the second portion  155  of the cavity  151  from acting on the plunger  202 . Consequently, advancement of the plunger  202  ceases. 
         [0054]    Various aspects of the IOL inserter  100  may affect a speed at which the plunger  202  may be made to advance, and these aspects may be varied in order to establish a desired rate of advancement. Some of these aspects may include the viscosity of liquid contained within the second portion  155  of the cavity  151 , a pressure within the canister  148 , a size of the orifice  190 , an amount by which the needle valve  206  has been withdrawn from the orifice  190 , an amount by which the needle valve  206  and/or the enlarged portion  193  of the orifice tapers, and/or a material of the IOL. One or more of these aspects may be varied in order to achieve a desired rate of advancement of the plunger  202 . 
         [0055]      FIG. 9  shows an example lever lock  900 . The lever lock  900  may be coupled to the IOL inserter  100  and a portion of the lever lock  90  may be interposed between the body  102  and the lever  104 . The lever lock  900  may be coupled to the IOL inserter  100  prior to use (for example, prior to shipping and during shipping) in order to prevent inadvertent actuation of the lever  104 . 
         [0056]    The lever lock  900  may include a first portion  902  and a second portion  904 . The first portion  902  and the second portion  904  may be connected with hinged connection. A proximal end  908  of the second portion  904  may form a bore therethrough, and a distal end  910  of the first portion  902  may also define a bore. The bore defined by the proximal end  906  of the second portion  904  may align with the bore defined formed in the distal end  910  of the first portion  902  to define a passage  912 . A hinge pin  914  may be received into the passage  912 . In some instances, a first end of the hinge pin  914  may have a flanged portion  915  that is larger than a size of the passage  912 . A second end of the hinge pin  914  may include flexible members  920  separated by a gap  922 . The flexible members  920  include an enlarged portion  924  at their respective ends. 
         [0057]    The hinge pin  914  may be received into the passage  912 . As the flexible members  920  are passed through the passage  912 , the flexible members  920  may flex towards each other. When the flexible members  920  exits the passage  912 , the flexible members  920  return to their at-rest position, causing retention of the hinge pin  914  within the passage  912 . The flanged portion  915  and the enlarged portions  924  cooperate to keep the hinge pin  914  retained within the passage  912  and the first and second portions  902 ,  904  pivotably connected. 
         [0058]    As shown in  FIGS. 8 and 10 , the first portion  902  may be interposed between the body  102  and the lever  104 , preventing depression of the lever  104 . One or more protrusions protruding from surface  926  may be received into corresponding receptacles  928  formed in the body  102 . In some implementations, the first portion  902  may include additional protrusions located proximate to the proximal end of body  102  are may be received into corresponding openings formed in body  102 . The second portion  904  may be received into a recess  930  formed in the door  140 . A first aperture  932  may also be formed into the door  140 . The first aperture  932  provides fluid communication between the exterior of the IOL inserter  100  and the chamber  134 . A protrusion  933  formed on the second portion  904  of the lever lock  900  is received into the first aperture  932 . The protrusion  933  acts as a barrier that prevents advancement of the IOL within the chamber  134 . In some instances, the protrusion  933  may reside between a distal haptic and an optic of the IOL. 
         [0059]    A second aperture  935  may also be formed in the door  140 . The aperture  935  may be utilized to introduce a lubricant (such as a viscoelastic material) to reduce friction between the nozzle  106  as an intraocular lens is pushed through the lumen  135 . As shown in  FIGS. 9-10 , the second portion  904  of the lever lock  900  may include an aperture  934  that aligns with the aperture  932  when the second portion  904  is properly seated in the recess  930 . This permits introduction of a lubricant into the chamber  134  while the lever lock  900  remains coupled to the body  102 . 
         [0060]    A user, such as a physician or other medical professional, may remove the lever lock  900  by grasping a protrusion  936  and pivoting the second portion  902  about the hinge pin  914  away from the body  102  so as to unseat the second portion  902  from the recess  930  and remove the protrusion  933  from the aperture  932 . The user may then pull the second portion  902  distally to remove the first portion  902  and, consequently, the entire lever lock  900  from the IOL inserter  100 . In some instances, the lever lock  900  may be discarded thereafter. 
         [0061]    Although the disclosure provides numerous examples, the scope of the present disclosure is not so limited. Rather, a wide range of modification, change, and substitution is contemplated in the foregoing disclosure. It is understood that such variations may be made to the foregoing without departing from the scope of the present disclosure.