Plunger device for a delivery device - Patent application

Abstract

A plunger device comprising a housing, a plunger, a source of stored mechanical energy, a rotatable element, and an actuator, wherein rotation of the rotatable element provides a controlled release to the plunger for moving the plunger in response to a force provided by the source of stored mechanical energy, and the actuator allows the plunger device to be manipulated by an operator to induce rotation of the rotatable element relative to the housing to provide a controlled release to the plunger for axial movement in response to a force provided by the source of stored mechanical energy.

Description

[Technical Field]

[0001] The present invention relates to a plunger device for a delivery device for deploying a substance or object, and related methods. The present invention relates particularly, but not exclusively, to a plunger device for a device for implanting an intraocular lens (IOL) into a subject's eye, and corresponding methods for manufacturing and using such a device. [Background technology]

[0002] There are many medical and non-medical procedures in which a medical professional or other operator must deliver adhesive objects or deploy small objects (often held in an adhesive medium) in a precise and controlled manner. Such procedures typically require a highly skilled operator to apply relatively large forces (often routinely) while maintaining a high degree of precision.

[0003] One such procedure is the implantation of an intraocular lens (IOL) into a patient's eye as part of a procedure to treat conditions such as cataracts or myopia.

[0004] To support such procedures, IOL injectors or insertion instruments have been developed that allow surgeons to insert an IOL into a patient's eye through an incision significantly narrower than the width of the lens. Such instruments typically fold the lens to a small size by advancing the lens through a narrow nozzle using a plunger. For clinical reasons, a viscoelastic or adhesive substance known as an "ophthalmic adhesive device" (OVD) is added as the lens is delivered to the nozzle.

[0005] Friction between the lens and the nozzle of the IOL injector can be significant, and depending on the size and type of lens, the delivery plunger may have to be actuated with correspondingly large force by the attending physician. Delivery must be performed in a very controlled manner to avoid rapid release of stored energy as the lens exits the nozzle and enters the eye.

[0006] Existing devices are typically in the form of syringe-like manual delivery devices. However, these devices can be difficult for operators to control, particularly because the force required for delivery drops rapidly as the IOL exits the injector, from a relatively high level of force required to push the lens through the nozzle to nearly zero immediately after the lens leaves the nozzle. When the force drops rapidly, there is a risk that the operator will lose control of the device, resulting in injury to the eye caused by the nozzle, which is located within the tiny incision in the eye.

[0007] The risks associated with incremental changes in applied force may be ameliorated in manual screw IOL delivery devices, but these devices tend to deliver lenses relatively slowly. Additionally, the rotational movement applied by the operator to actuate a screw or similar device can result in undesirable nozzle movement, with the associated risk of tearing ocular tissue adjacent to the incision.

[0008] Generally, manual screw-type instruments require two hands for operation. However, some surgeons prefer to have one hand free to stabilize the patient's eye and guide the lens into place during lens implantation. Electric, hydraulically driven, compressed gas driven, and spring-driven delivery mechanisms have been envisioned and introduced to the market. While these instruments have the advantage of freeing up one of the surgeon's hands to assist with the insertion procedure, existing instruments tend to be heavy, poorly balanced, mechanically complex, and expensive.

[0009] It will be appreciated that similar problems may arise with similar devices for other applications that require an operator to deliver an adhesive substance or deploy a device held in an adhesive medium in a precisely controlled manner. Even if the force or precision required is not particularly high, there is a risk of repetitive strain injury in similar procedures that require operators to use this type of delivery device routinely.

[0010] It is an object of the present invention to provide improved plunger devices and related devices, for example plunger devices for delivery devices, that overcome or at least partially ameliorate one or more of the problems noted above, and one or more associated methods for making or using such plunger devices.

[0011] Aspects of the invention are set out in the independent claims, while other optional features are set out in the dependent claims.

[0012] According to one embodiment, there is provided a plunger device for a delivery device comprising: a housing; a plunger configured to move axially relative to the housing to force at least one object and / or substance out of a nozzle of the delivery device; a source of stored mechanical energy to provide a force to drive movement of the plunger axially relative to the housing; a rotatable element carried by the housing and configured to rotate relative to the housing, wherein rotation of the rotatable element provides controlled release of the plunger to move axially relative to the housing in response to the force imparted by the stored mechanical energy source; and an actuator for operation by an operator of the plunger device to induce rotation of the rotatable element relative to the housing to provide controlled release of the plunger to move axially in response to the force imparted by the stored mechanical energy source.

[0013] The rotatable element can, for example, rotate about an axis of rotation parallel to the axial direction. If the rotation of the rotatable element is by a given cumulative rotational displacement, the plunger device can be configured to move the plunger axially relative to the housing for a longitudinal displacement that depends on the cumulative rotational displacement.

[0014] The plunger and housing can be mutually configured for axial movement relative to one another, whereby rotation of the plunger relative to the housing is inhibited when the plunger moves axially. The plunger and rotatable element can each have a respective threaded surface. If the plunger and rotatable element have a respective threaded surface, the threaded surfaces of the plunger and rotatable element can optionally be configured to engage with one another, whereby the rotatable element can be configured to rotate relative to the plunger when the rotatable element rotates relative to the housing to provide a controlled release to the plunger.

[0015] When the plunger and the rotatable element each have respective threaded surfaces, the threaded surfaces of the plunger and the rotatable element can be configured to back-drive the rotatable element relative to the plunger. The threaded surfaces of the plunger and the rotatable element can be configured to inhibit axial movement of the plunger relative to the housing when the rotatable element is not rotating.

[0016] The rotatable element and plunger may be mutually configured for axial movement relative to one another, with rotation of the rotatable element relative to the plunger being inhibited when the plunger moves axially.

[0017] The plunger and the housing can each have a respective threaded surface. When the plunger and the housing each have a respective threaded surface, the threaded surfaces of the plunger and the housing can optionally be configured to engage with each other, whereby the plunger is configured to rotate relative to the housing when the rotatable element rotates relative to the housing to provide a controlled release to the plunger.

[0018] The rotatable element and the housing may be mutually configured for rotational movement relative to one another, with axial movement of the rotatable element relative to the housing being constrained.

[0019] The source of stored mechanical energy can comprise a spring arranged to store elastic potential energy prior to actuation of the plunger arrangement to provide a force to drive movement of the plunger. The spring can be arranged to be in a compressed state to store elastic potential energy prior to actuation of the plunger arrangement to provide a force to drive movement of the plunger. Alternatively, the spring can be arranged to be in a tensioned state to store elastic potential energy prior to actuation of the plunger arrangement to provide a force to drive movement of the plunger.

[0020] The source of stored mechanical energy may comprise a pneumatic actuator for providing pneumatic pressure as the force to drive movement of the plunger.

[0021] The actuator can be configured for axial movement relative to the housing by an operator, whereby axial movement of the actuator induces rotation of the rotatable element relative to the housing to provide controlled release to the plunger. The actuator and housing can be mutually configured for axial movement relative to each other, whereby rotation of the actuator relative to the housing can be inhibited when the actuator is moved axially.

[0022] The actuator and the rotatable element can each have a respective threaded surface. When the actuator and the rotatable element each have a respective threaded surface, the threaded surfaces of the actuator and the rotatable element can optionally be configured to engage with each other, whereby the rotatable element is configured to rotate relative to the actuator when the actuator moves axially, thereby providing a controlled release to the plunger. The threaded surfaces of the actuator and the rotatable element can be configured to retract the rotatable element relative to the actuator.

[0023] The rotatable element and the actuator may be mutually configured for axial movement relative to one another, and when the actuator moves axially, rotation of the rotatable element relative to the actuator may be inhibited.

[0024] The actuator and the housing can each have a respective threaded surface. When the actuator and the housing each have a respective threaded surface, the threaded surfaces of the actuator and the housing can optionally be configured to engage with each other, whereby the actuator is configured to rotate relative to the housing, rotating the rotatable element relative to the housing and providing a controlled release to the plunger.

[0025] The actuator may comprise an electromechanical mechanism for driving rotation of the rotatable element relative to the housing, and optionally a switch for actuation of the electromechanical mechanism by an operator, to control actuation of the rotatable element and provide controlled release to the plunger.

[0026] The plunger device may also include at least one further source of mechanical energy to provide a force to drive rotation of the rotatable element. For example, the at least one further source of mechanical energy may include a spring, such as a torsion spring or the like, and / or may include a power source of mechanical energy.

[0027] The plunger device may also include at least one element for providing a preconfigured resistance between the actuator and the housing to resist axial movement of the actuator relative to the housing, whereby the actuator may be movable by an operator, for example, by applying a substantially uniform force sufficient to overcome the preconfigured resistance.

[0028] The housing, plunger, rotatable element and actuator may be mutually configured such that an operator operates the actuator by applying a substantially equal force to move the actuator axially, thereby rotating the rotatable element relative to the housing and providing a controlled release to the plunger from a first position relative to the housing in which the plunger device is ready for use, to a second position relative to the housing in which the plunger device is configured to expel at least one object and / or substance from the nozzle of the delivery device during actuation.

[0029] According to one embodiment, there is provided a delivery device for extruding at least one object and / or substance, the delivery device comprising a nozzle for extruding at least one object and / or substance and a plunger device as claimed above.

[0030] The delivery device can be configured to push the intraocular lens into the patient's eye.

[0031] According to one embodiment, there is provided a method for extruding at least one object and / or substance, the method comprising: providing a delivery device as described above, the delivery device containing the at least one object and / or substance to be extruded; and actuating an actuator of a plunger device of the delivery device to induce rotation of a rotatable element relative to the housing to provide a controlled release to the plunger to axially move the plunger under force provided by a source of stored mechanical energy, thereby extruding the at least one object and / or substance.

[0032] According to one embodiment, there is provided a method of manufacturing the plunger device described above, the method including providing a housing, a plunger, a source of stored mechanical energy, a rotatable element, and an actuator of the plunger device, and assembling the housing, plunger, source of stored mechanical energy, the rotatable element, and the actuator to form the plunger device.

[0033] Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0034] [Figure 1(a)] FIG. 1(a) is a schematic perspective view of a preferred plunger arrangement for a delivery device. [Figure 1(b)] FIG. 1(b) is a schematic perspective view of the preferred plunger device of FIG. 1(a) when employed as part of a delivery device for an intraocular lens (IOL). [Figure 2(a)] FIG. 2(a) is a schematic perspective exploded view of the preferred plunger device of FIG. 1(a). [Figure 2(b)] FIG. 2(b) is a schematic perspective view of a portion of the preferred plunger device of FIG. 1(a). [Figure 3(a)] FIG. 3(a) is a schematic perspective cross-sectional view of a portion of the preferred plunger device of FIG. 1(a). [Figure 3(b)] FIG. 3(b) is another schematic perspective cross-sectional view of the preferred plunger device of FIG. 1(a). [Figure 4] FIG. 4 is a diagram conceptually illustrating the forces acting on various parts of the preferred plunger device of FIG. 1(a) during operation. [Figure 5] FIG. 5 is a schematic, partially exploded, perspective cross-sectional view of the preferred plunger device of FIG. 1(a) during assembly.

[0035] overview Figures 1(a) and 1(b) show a plunger device for a delivery device, generally designated 100. Figure 1(a) is a schematic perspective view of a preferred plunger device for a delivery device. Figure 1(b) is a schematic perspective view of the plunger device 100 of Figure 1(a) employed as part of a delivery device for deployment of an intraocular lens (IOL) 102.

[0036] As shown in FIG. 1(a), plunger device 100 resembles a medical syringe or the like and includes a plunger 104, a housing 106, an actuator 108, and a spring 110 that are coaxially arranged about a longitudinal axis (i.e., about axis X-X' in FIGS. 1(a) and 1(b)). Housing 106 is configured to slidably receive a portion of plunger 104 into one end of housing 106 and a portion of actuator 108 in the other end of housing 106. Spring 110 comprises a compression spring that is in a pre-compressed state when plunger device 100 is fully assembled and ready for use. Spring 110 is arranged to provide a driving force to drive plunger 104 in the direction of arrow A, away from actuator 108 and housing 106.

[0037] As shown in FIG. 1(b), the IOL delivery device comprises an elongated, sheath-like cover 112 of generally circular cross-section. The cover 112 forms an internal chamber within which the IOL 102 (along with a viscoelastic / ophthalmic adhesive device (OVD)) is positioned for deployment. The cover 112 has a nozzle 114 (coaxial with axis X-X′) longitudinally disposed at one end of the internal chamber, through which the IOL 102 disposed in the chamber is driven by the plunger 104 upon actuation. An opening 116 is longitudinally disposed at the end of the internal chamber opposite the nozzle 114 for receiving the plunger device 100 for assembly to form the IOL delivery device. It should be understood that the illustration of the IOL delivery device is provided as an example of how the plunger device 100 can be used and is simplified for clarity.

[0038] Plunger device 100 is arranged so that, upon actuation, a user of plunger device 100 can operate the device by applying a relatively low, generally constant force between actuator 108 and housing 106 (arrows F-F') and sliding the actuator in the direction of arrow A. For example, the device can be operated one-handed, like a syringe, by the user holding housing 106 in place between two fingers while depressing actuator 108 with their thumb.

[0039] Advantageously, the internal features of plunger apparatus 100 are configured to decouple the force required to move plunger 104 (the "plunger force") from the force that must be applied to actuator 108 relative to housing 106 to actuate the device (the "actuation force"). Specifically, as explained in more detail below, the internal features of plunger apparatus 100 are configured so that when a relatively low, constant force is applied to the actuator, movement of the actuator as it slides into housing 106 causes corresponding movement of plunger 104. The features of plunger apparatus 100 are advantageously configured so that plunger 104 is driven in direction A entirely (or at least predominantly) by the spring force applied by pre-compressed spring 110.

[0040] The internal features of plunger device 100 are also configured such that when plunger device 100 is assembled and no force is applied to the actuator, plunger 104 remains in a predetermined position and spring force cannot drive plunger 104 in the direction of arrow A. Thus, movement of actuator 106 by an operator controls the displacement and delivery rate of plunger 104.

[0041] Thus, when implemented as part of an IOL delivery device, plunger 104, during manipulation by a user such as a surgeon, pushes the IOL through the narrowest cross-section of nozzle 114 and into the anterior chamber of the eye. The relatively high force required for this (which can be up to 50 N, depending on the lens and viscoelastic material selection) is provided by spring 110. Fine adjustment of actuator 108 provides the fine control required to prevent trauma to the eye when the insertion force drops off sharply once most of the lens has passed through the narrowest cross-section of nozzle 114.

[0042] Thus, the preferred plunger device introduced above can be applied to an IOL delivery device (or similar device) for relatively easy one-handed insertion of an IOL (or delivery of other objects or adhesives). The preferred delivery device improves upon many existing one-handed devices by reducing the force the surgeon must apply to the lens to force it through the nozzle and improving control over the lens's exit from the nozzle. The force required to push the IOL through the nozzle 114 would otherwise be uncomfortable for one-handed delivery.

[0043] Plunger Device The plunger device 100 will now be described in more detail, by way of example, with reference to Figures 2(a) and 2(b) and Figures 3(a) and 3(b). Figure 2(a) is a schematic perspective exploded view of the plunger device 100 of Figure 1(a). Figure 2(b) is a schematic perspective cross-sectional view of the plunger 104 of the plunger device 100. Figure 3(a) is a schematic perspective cross-sectional view of the plunger 104 and housing 106 of the preferred plunger device 100 of Figure 1(a) in a partially assembled state. Figure 3(b) is a schematic perspective cross-sectional view of the plunger 104, housing 106, and actuator 108 of the preferred plunger device 100 of Figure 1(a) in an assembled state.

[0044] 2(a)-3(b), the plunger 104 includes a plunger tip 118 for pushing the IOL 102 out of the nozzle 114 of the IOL delivery chamber, a generally disk-shaped spring holder 120 for holding the spring 110, and a generally cylindrical plunger body 122. The plunger tip 118, the spring holder 120, and the plunger body 122 are coaxially aligned relative to one another along a common central axis (axis X-X'). The plunger body 122 extends in one direction from the spring holder 120 along the central axis X-X', and the plunger tip 118 extends in the opposite direction.

[0045] Plunger body 122 includes a threaded portion 124, an interlocking portion 126, and a plunger stopper 128, which are arranged along a central axis X-X'. Threaded portion 124 is located at an end of plunger body 122 farthest from plunger tip 118, plunger stopper 128 is located at an end of plunger body 122 closest to plunger tip 118, and interlocking portion 126 is located between plunger stopper 128 and threaded portion 124.

[0046] The housing 106 comprises a hollow, elongated, generally cylindrical first casing portion 130 and a hollow, elongated, generally cylindrical second casing portion 132. The first casing portion 130 has a smaller diameter than and is coaxially aligned with the second casing portion 132. When assembled, the first casing portion 130 extends away from the second casing portion 132 toward the plunger tip of the plunger device 100.

[0047] A generally annular flange 134 is located on one end of the second casing 130 that is furthest from the plunger tip 118 when the plunger device 100 is assembled. The flange 134 has a larger diameter than the second casing portion 132 and is coaxially aligned therewith. The flange 134 thus allows a user to place two fingers on the plunger-facing surface of the flange during operation to hold the housing 106 in place while applying pressure to the actuator 108, such as with a syringe or the like.

[0048] 3(a) and 3(b), the housing 106 also includes a hollow, elongated, generally cylindrical interior portion 136 that extends into the second casing portion 132 opposite the first casing portion 130. The interior portion 136 has a smaller diameter than and is coaxially aligned with the inner chamber formed by the second casing portion 132. Thus, the interior portion 136 and the second casing portion 130 together define a chamber 137 of annular cross section within the second casing portion 132.

[0049] The interior portion 136 and the first casing portion 130 each define a respective generally cylindrical interior chamber that is open at both ends. These interior chambers are coaxially aligned with one another to form a substantially continuous central passageway 138 that is open at both ends. The interior portion 136 and the first casing portion 130 of the housing 106 and the threaded portion 124 and interlocking portion 126 of the plunger body 122 are shaped and sized to be mutually configured such that the threaded portion 124 and interlocking portion 126 are slidably received into and through the central passageway 138 of the housing 106 when the plunger device 100 is assembled.

[0050] The first casing portion 130 and the plunger stopper 128 of the plunger body 122 are mutually configured such that, when the plunger body 122 is slidably received into the central passage 138 during assembly, the plunger stopper 128 ultimately abuts the end of the first casing portion 130 closest to the plunger tip 118, preventing further movement of the plunger body 122 into the central passage 138.

[0051] The interlocking portion 126 of the plunger body 122 has approximately the same length as the first casing portion 130 and, as can be seen in FIG. 2(b), includes a plurality of keying features 126'. These keying features 126' are configured to engage with corresponding keying features 130' provided on the first casing portion 130 to prevent rotation of the plunger 104 when the plunger body 122 is received in the central passage 138. In this example, the keying features 126' of the interlocking portion 126 include a plurality of splines extending along the length of the interlocking portion 126. The keying features 130' of the first casing portion 130 include a plurality of grooves extending along the length of the first casing portion 130 and along the central passage 138 and configured to engage with the splines 126'. However, it should be appreciated that any suitable mechanism can be used to prevent rotation of the plunger 104.

[0052] The threaded portion 124 of the plunger body 122 has a length greater than the length of the second casing portion 132 of the housing 106 so that when the plunger body 122 is fully received within the central passage 138 and the plunger stopper 128 abuts the first casing portion 130, the threaded portion extends through and beyond the end of the second casing portion 132 furthest from the plunger tip 118.

[0053] The actuator 108 comprises an elongated, generally cylindrical, hollow actuator body 140 having one or more helical grooves on its interior surface to form an internally threaded surface 142 and a generally circular opening at each end. An actuator button 144 is located at the end of the actuator 108 farthest from the plunger tip 118 when the plunger device 100 is assembled. The actuator button 144 comprises a generally annular portion 144-1 having a larger diameter than the actuator body 140 and coaxially aligned therewith, and a cap 144-2. The annular portion 144-1 and the actuator body 140 are mutually configured to define a recess into which the cap 144-2 can be removably received to close the actuator 108 at the end farthest from the plunger tip 118.

[0054] A friction element 146 is disposed around the inner surface of the opening at the end of the actuator 108 furthest from the plunger tip 118. As can be seen in FIG. 3(b), the friction element 146 is configured to interengage with the cylindrical interior portion 136 of the housing 106 when the plunger device 100 is assembled, to provide a constant resistance force when the actuator 108 is pushed into the housing 106 in the direction of arrow A along the axis X-X'.

[0055] Friction element 146 may comprise any suitable mechanism for providing the required amount of resistance to movement of actuator 108. In this example, friction element comprises a ring of suitable material (e.g., rubber or the like) configured to fit around interior portion 136 of housing 106 when plunger device 100 is assembled, as seen in FIG. 3(b). Thus, friction element resembles a rubber stopper or the like that provides friction during actuation of a disposable syringe. However, it should be appreciated that a similar friction element could alternatively or additionally be positioned around the exterior surface of actuator body 140 to engage the interior surface of second casing portion 132 of housing 106. Furthermore, more sophisticated arrangements could be used in which friction element 146 and / or related features of housing 106 are specifically configured to reduce the difference between static and dynamic friction.

[0056] The second casing portion 132 of the housing 106 and the actuator body 140 are mutually configured to slidably receive the actuator body 140 into the housing 106 from the end of the second casing portion 132 farthest from the plunger tip 118 during operation. The second casing and inner portions 132, 136 of the housing 106, the actuator body 140, and the friction element 146 are mutually configured such that when the actuator body 140 slides into the housing 106 and the end of the actuator 108 closest to the plunger tip 118 enters the annular cross-section of the chamber 137, the friction element 146 engages around the outer surface of the inner portion 136 to provide a constant resistance to movement of the actuator 108.

[0057] The actuator body 140 also includes a plurality of keying features 148 for engaging corresponding keying features located on the second casing portion 132 to restrain rotation of the actuator 108 when the actuator body 140 is slidably received within the housing 106. In this example, the keying features 148 on the actuator body 140 include a plurality of splines extending substantially the length of the actuator body 140. The keying features on the second casing portion 132 include a plurality of grooves extending substantially the length of the second casing portion 132 and configured to engage with the splines 148 on the actuator body. However, any suitable mechanism for restraining rotation of the actuator 108 may be used.

[0058] The spring 110 is mounted coaxially around and aligned with the plunger body 122 and first casing portion 130. The plunger body 122 and housing casing portions 130, 132 are configured such that when the plunger assembly 100 is fully assembled and ready for use, the spring is in a pre-compressed state and is retained between the spring retainer 120 of the plunger assembly 100 and the end of the larger diameter second casing portion 132. The spring therefore exerts a spring force against the plunger 104 in the direction of arrow A, away from the actuator 108 and housing 106.

[0059] As can be seen in Figures 2(a)-3(b), the plunger device 100 also includes a rotatable element, in this example in the form of a nut 150. The nut 150 has an internally threaded surface 152 and an externally threaded surface 154.

[0060] The internal threaded surface 152 of the nut 150 and the threaded portion 124 of the plunger body 122 are configured to interengage to threadingly engage the nut 150 onto the threaded portion 124 and to move linearly relative to the threaded portion 124 as the nut 150 rotates about the central axis X-X'. In this example, the threads of the internal threaded surface 152 of the nut 150 and the threads of the threaded portion 124 have a relatively high pitch and are mutually configured to increase the displacement of the nut 150 relative to the plunger tip 118 (and vice versa) as the nut 150 rotates in the direction Φ. In this example, the threads of the threaded portion 124 advantageously have multiple thread starts, but this is not required.

[0061] For example, in this example of a retractable plunger, a typical range for the pitch is 1 to 2 times the pitch diameter of the plunger thread, although material selection will affect the optimum pitch, so values ​​outside this range may be suitable depending on the material used.

[0062] The externally threaded surface 154 of the nut 150 and the internally threaded surface 142 of the actuator body 140 are configured to engage one another to thread the nut 150 into the actuator body 140 and to allow linear movement relative to the actuator body 140 as the nut 150 rotates about the central axis X-X'. In this example, the threads of the externally threaded surface 154 of the nut 150 and the threads of the internally threaded surface 142 of the actuator body 140 have a relatively high pitch and are mutually configured such that the displacement of the nut 150 relative to the actuator button 144 decreases as the nut 150 rotates in the direction Φ (and vice versa). In this example, the threads of the internally threaded surface 142 advantageously have multiple thread starts, but this is not required.

[0063] 3(b), when the plunger device 100 is fully assembled, the nut 150 is disposed in threaded engagement both onto the threaded portion 124 of the plunger body 122 and into threaded engagement with the inner surface 142 of the actuator body 140. The nut 150 is disposed within the actuator body 140 between the friction element 146 and the actuator button 144 and abuts the end of the interior portion 136 of the housing 106. Thus, linear movement of the nut 150 in the direction of arrow A toward the plunger tip 118 is inhibited. This mechanism allows the displacement of the plunger tip 118 to be controlled by rotation of the nut 150.

[0064] In this example, the threads at the interface between the threaded portion 124 and the nut 150 are configured to allow the nut 150 to retract relative to the plunger body 122. Thus, when an operator applies force to the actuator button 144 to slide the actuator body 140 into the housing 106, movement of the actuator 108 is not restrained by the nut 150. Instead, the nut 150 begins to rotate within the actuator body 140 about the threaded portion 124 of the plunger body 122, and does not move axially because it is restrained from doing so by the interior portion 136 of the housing 106. The plunger 104 therefore begins to move axially in the direction of arrow A under the force applied by the spring 110 against the spring retainer 120, and does not rotate because the rotation of the plunger 104 is restrained by the keying feature 126' of the interlocking portion 126.

[0065] It can be seen that rotation of nut 150 through a given cumulative rotational displacement will release the plunger in the direction of arrow A under the force provided by spring 110 for a cumulative axial displacement equal to that rotational displacement. This dependency between rotational and linear displacement provides significantly improved control over clutch mechanisms and the like, which act to hold the plunger against the spring force until the clutch or similar mechanism is activated, causing the spring to release more abruptly and more uncontrolled. The dependency between rotational and linear displacement is typically proportional, with a relatively large rotational displacement of nut 150 providing a relatively small axial movement of the plunger in the direction of arrow A.

[0066] The force applied by an operator, such as a surgeon, to the actuator 108 is therefore a constant force. This substantially constant force is equal to the force required to overcome the resistance provided by the friction element 146 to move the actuator 108 relative to the housing 106 minus the resultant force in the direction of arrow A that the external threads of the nut 150 apply to the threads of the actuator body 140 (e.g., as a result of the force from the spring 110 acting on the plunger 104 to drive rotation of the nut 150).

[0067] By appropriately designing the various thread pitches and friction element 146, the plunger arrangement can be configured such that the spring force is insufficient to cause back-induced rotation of the nut 150 without actuation of the actuator 108.

[0068] In this example, the threaded portion of the plunger assembly 100 described above is also configured to provide an essentially one-to-one relationship between actuator displacement and plunger displacement.

[0069] In this example, there are numerous design options that can be used to optimize plunger assembly 100, particularly to minimize axial forces from nut 150 without effectively changing direction of forces. These options include, for example, the type of material used, the surface finish, the thread pitch and profile, and the design of the thrust bearing between nut 150 and housing 106.

[0070] FIG. 4 is a diagram conceptually illustrating the forces acting on various portions of the preferred plunger device 100 of FIG. 1(a) as a function of the displacement of the plunger tip 118 during actuation when implemented as part of an IOL delivery device.

[0071] 4, the spring force decreases substantially linearly from a maximum when spring 110 is pre-compressed and plunger tip 118 is at zero displacement to a lower value as IOL 102 is dispensed. The delivery force required to deliver IOL 102 into the eye increases as IOL 102 is forced into the narrowing nozzle 114 before rapidly decreasing as IOL 102 passes through the end of nozzle 114. The operator force required to actuate actuator 108 remains low and constant throughout the process.

[0072] As those skilled in the art will appreciate, dynamic dry friction can be significantly less than static dry friction. If the difference between these frictions is too great, it can cause significant and undesirable stiction. Therefore, the materials used are selected with this in mind so that stopping and starting do not cause significant peaks in operator force.

[0073] Thus, the plunger force is decoupled from the actuation force, and displacement of the actuator 106 by the operator results in a corresponding displacement of the plunger tip 118, which can be more precisely controlled. Thus, the plunger device 100 can be used one-handed, which reduces the force that the operator would otherwise have to apply and allows for better control.

[0074] Assembly and storage of plunger devices A possible assembly and storage of the plunger device will now be described by way of example with reference to Figure 5, which is a schematic, partially exploded, perspective cross-sectional view of the preferred plunger device 100 of Figure 1(a) during assembly. It will be appreciated that the assembly method described is exemplary, and that various assembly methods can be used depending on how the plunger device 100 is implemented.

[0075] During assembly, the plunger 104, spring 110, housing 106, friction element 146, and actuator 108 are assembled together as shown in FIG. 5 in an initial group of assembly steps. Specifically, the spring 110 is placed over the plunger body 122 against the spring retainer 120, and the plunger 104 is inserted into the first casing portion 130 of the housing 106 and pushed to a start position, thereby compressing the spring 110. The friction element 146 is positioned within the actuator body 140 or at a precise location around the protruding end of the interior portion 136 of the housing 106. The actuator body 140 of the actuator 108 is inserted into the first casing portion 130 of the housing 106 to engage the friction element 146 at a precise location within the actuator body 140 and around the interior portion 136 of the housing 106, placing the actuator 108 in its start position.

[0076] For ease of assembly and disassembly, as shown in FIG. 5, the plunger device 100 of this example is configured to allow access for installation and removal of the nut 150 through an opening in the end of the actuator body 140 farthest from the plunger tip 118 by removing the cap 144-2.

[0077] Nut 150 is fed through an access opening in actuator body 140 and threaded until it engages the protruding end of interior portion 136 of housing 106. A tool such as a tube spanner or the like along with a pair of handling protrusions can be provided for this purpose. Once nut 150 has reached its final position, plunger device 100 is mechanically primed and the opening in actuator body 140 can be covered with cap 144-2.

[0078] A removable spring clip 160 or the like can be provided to fit over the end of the pre-compressed spring and to receive the load of the spring 110 during storage. The clip 160 protects the plunger device 100 from creep that may otherwise occur as a result of the force exerted by the loaded spring. The clip 160 can be removed as part of the procedure for preparing the device before use.

[0079] Modifications and Changes Detailed examples have been described above. Those skilled in the art will appreciate that numerous modifications and variations can be made to the above-described embodiments and still benefit from the invention embodied therein.

[0080] For example, while the above examples are described with respect to IOL delivery devices, the technical principles described above can extend to procedures outside of IOL delivery. For example, the principles can be applied in any situation where a medical professional or other operator may need to apply a large amount of force while maintaining a high degree of precision and control to administer a substance or object. Even when the required force or precision is not particularly great, the features described above have the potential to reduce the risk of repetitive strain injury in similar procedures where operators are required to administer substances or objects on a routine basis. For example, in orthopedic surgery, similar procedures include the injection of biomaterials, bone cement, and hyaluronic acid. Similar applications may be found in spinal surgery and dentistry.

[0081] It can be seen that the preferred plunger device described above is configured to avoid backlash in the component chain from the actuator to the plunger tip, and that there is essentially a one-to-one relationship between actuator position and plunger position. This means that this concept is useful for any application where the plunger tip needs to be precisely positioned by controlling the displacement of the actuator. Applications that can benefit from such control include, for example, in cardiology for the placement of heart valves and stents, and in neurology.

[0082] The presence of a preload spring, which allows the delivery device to be essentially backlash-free, means that the same principles could potentially be used to provide high-precision instruments that can be used to deliver expensive drugs in an accurate and measurable manner.

[0083] It will be appreciated, however, that the relationship between actuator displacement and plunger displacement need not be one-to-one. With proper design, the actuator and plunger body can be configured so that a small actuator displacement leads to a large plunger displacement, which can be advantageous if the device in which the plunger device is implemented is used to rapidly deliver a specific amount of substance. Conversely, the actuator and plunger body can be configured so that a large actuator displacement leads to a small plunger displacement (e.g., to allow for more precise control of the plunger tip). The ratio between actuator displacement and plunger displacement can be configured to be essentially a fixed number. For example, an actuator displacement of 10 mm will result in a plunger displacement of, say, 0.5 mm.

[0084] It should be appreciated that the device may be implemented as a disposable device or as a reusable device.

[0085] While the use of a pre-compressed spring to provide the power source for driving the plunger is particularly advantageous, it will be appreciated that another mechanical power source can be used instead of or in addition to a spring. For example, a pneumatic actuator or the like can be used. Such a pneumatic actuator could, for example, be powered by a source of compressed air that is separate from the injector device and delivered to the device by flexible tubing or the like. While compressed air is generally a readily available power source, pneumatic actuators can sometimes be difficult to control.

[0086] It will be appreciated that the spring can be arranged to be in tension to provide a power source to drive the plunger.

[0087] In the above example, rotation of the retraction nut is controlled by movement of the axial control actuator, but rotation can be controlled in other ways. For example, rotation control can be provided by a rotational damper, such as an electromechanical damper. In this case, the operator would be provided with, for example, a means to switch the damper on or off and / or a wheel attached to a variable resistor to control the delivery rate.

[0088] While the threads in the above example are selected so that the nut is retractable relative to the threaded portion of the plunger body, the plunger arrangement can be configured so that the nut is not retractable relative to the plunger. Rotation of the nut in an arrangement that is not retractable by the plunger can be driven by an actuator as described in the above example, but the force acting between the nut and actuator will be different when engaging different surfaces of the thread profile. For example, if the nut is not retractable relative to the plunger, the force applied by the operator to the actuator will typically be the sum of the force required to move the actuator relative to the housing and the force the actuator applies to the nut threads to rotate the nut.

[0089] A mechanism can be provided on the plunger device to apply a force that actively rotates the nut and drives the plunger forward. Such a mechanism is particularly advantageous when the nut is not retractable, but can also be used to advantage when the nut is retractable. For example, the rotation of the nut can be driven by electromechanical means such as a gear motor or stepper motor, providing the surgeon with a means to stop and start the rotation and perhaps a means to control the delivery rate. The advantage of having a pre-compressed spring providing the primary mechanical driving force in this case is that the motor only needs to provide a relatively low torque—i.e., enough to overcome friction.

[0090] Alternatively or additionally, a torsion spring can be installed in the annular cavity that is preloaded when the device is assembled, and the torsion spring can be configured to act on the nut to provide a positive force to rotate the nut in a direction that actuates the plunger.

[0091] In the embodiment described with reference to the drawings, neither the plunger nor the actuator can rotate relative to the housing due to a keying feature in the form of a spline and associated groove. It will be appreciated that there are other ways to achieve a similar effect. The keying feature between the housing and plunger can, for example, be helical, with a different pitch and direction than the threaded engagement between the plunger and nut. In configurations where the interface between the plunger and housing is threaded, the interface between the nut and plunger can be selected to be a straight spline.

[0092] Similarly, the interfaces between the nut and actuator and between the actuator and housing can be modified: the interface between the nut and actuator can be straight splinted and the interface between the housing and actuator can be threaded, or both can be threaded.

[0093] The threads between the nut and the actuator can be in the opposite direction to the threads on the plunger. In this arrangement, the plunger and actuator travel in opposite directions during actuation, requiring the operator to withdraw the actuator from the housing to be able to drive the plunger forward.

[0094] Various other modifications will be apparent to those skilled in the art and will not be described in further detail herein.

Claims

1. A plunger device of a delivery device, the plunger device comprising: Housing and a plunger configured to move axially relative to the housing to expel at least one object and / or substance from a nozzle of the delivery device; a source of stored mechanical energy for providing a force to drive movement of the plunger in the axial direction relative to the housing; a rotatable element carried by the housing and configured to rotate relative to the housing about an axis of rotation parallel to the axial direction, wherein rotation of the rotatable element through a given cumulative rotational displacement provides a controlled release to the plunger to move the plunger in the axial direction relative to the housing under a force imparted by the stored mechanical energy source for a longitudinal displacement responsive to the cumulative rotational displacement; an actuator for actuating the plunger arrangement by an operator to induce rotation of the rotatable element relative to the housing to provide the release of control to the plunger for the axial movement of the plunger in response to the force provided by the source of stored mechanical energy; A plunger device comprising:

2. 2. The plunger device of claim 1, wherein the plunger and the housing are mutually configured for axial movement relative to one another, and wherein rotation of the plunger relative to the housing is inhibited when the plunger moves in the axial direction.

3. 3. The plunger device of claim 1 or 2, wherein the plunger and the rotatable element each have a respective threaded surface, the threaded surfaces of the plunger and the rotatable element are configured to engage with each other, and the rotatable element is configured to rotate relative to the plunger when the rotatable element rotates relative to the housing to provide the controlled release to the plunger.

4. The plunger device of claim 3 , wherein the threaded surfaces of the plunger and the rotatable element are configured such that the rotatable element is retractable relative to the plunger.

5. The plunger device of claim 3 , wherein the threaded surfaces of the plunger and the rotatable element are configured to inhibit axial movement of the plunger relative to the housing when the rotatable element is not being rotated.

6. 2. The plunger arrangement of claim 1, wherein the rotatable element and the plunger are mutually configured for axial movement relative to one another, and wherein rotation of the rotatable element relative to the plunger is inhibited when the plunger moves axially.

7. 7. The plunger device of claim 1 or 6, wherein the plunger and the housing each have a respective threaded surface, the threaded surfaces of the plunger and the housing configured to engage with each other and to rotate relative to the housing when the rotatable element rotates relative to the housing to provide the controlled release to the plunger.

8. 3. The plunger arrangement of claim 1 or 2, wherein the rotatable element and the housing are mutually configured for rotational movement relative to one another, and axial movement of the rotatable element relative to the housing is constrained.

9. 3. The plunger arrangement of claim 1 or 2, wherein the source of stored mechanical energy comprises a spring arranged to store elastic potential energy prior to actuation of the plunger arrangement to provide a force to drive movement of the plunger.

10. 10. The plunger device of claim 9, wherein the spring is arranged in a compressed state to store the elastic potential energy prior to actuation of the plunger device to provide a force to drive movement of the plunger.

11. A plunger device as described in claim 1 or 2, wherein the stored mechanical energy source comprises a pneumatic actuator for applying pneumatic pressure as a force to drive movement of the plunger.

12. 3. The plunger device of claim 1, wherein the actuator is configured to be axially moved by the operator relative to the housing, and the axial movement of the actuator induces the rotation of the rotatable element relative to the housing to provide the controlled release to the plunger.

13. 3. The plunger device of claim 1 or 2, wherein the actuator and the housing are mutually configured for axial movement relative to one another, and rotation of the actuator relative to the housing is inhibited when the actuator moves axially.

14. 3. The plunger device of claim 1 or 2, wherein the actuator and the rotatable element each have a respective threaded surface, the threaded surfaces of the actuator and the rotatable element being configured to engage with each other, such that the rotatable element is configured to rotate relative to the actuator when the actuator moves in the axial direction, thereby providing the controlled release to the plunger.

15. 15. The plunger device of claim 14, wherein the threaded surfaces of the actuator and the rotatable element are configured such that the rotatable element is retractable relative to the actuator.

16. 3. The plunger arrangement of claim 1 or 2, wherein the rotatable element and actuator are mutually configured for axial movement relative to one another, and wherein rotation of the rotatable element relative to the actuator is inhibited when the actuator moves in the axial direction.

17. 3. The plunger device of claim 1 or 2, wherein the actuator and the housing each have a respective threaded surface, the threaded surfaces of the actuator and the housing are configured to engage with each other, and the actuator is configured to rotate relative to the housing to rotate the rotatable element relative to the housing, thereby providing the controlled release to the plunger.

18. 3. The plunger device of claim 1, wherein the actuator comprises an electromechanical mechanism for driving rotation of the rotatable element relative to the housing to control actuation of the rotatable element and provide the release of control to the plunger, and a switch for operating the electromechanical mechanism.

19. 3. The plunger arrangement of claim 1 or 2, further comprising at least one further source of mechanical energy for providing a force to drive rotation of the rotatable element.

20. 3. The plunger device of claim 1, further comprising at least one element for providing a preconfigured resistance between the actuator and the housing to resist axial movement of the actuator relative to the housing, wherein the actuator is movable by an operator applying a substantially uniform force sufficient to overcome the preconfigured resistance.

21. 3. The plunger device of claim 1 or 2, wherein the housing, the plunger, the rotatable element and the actuator are configured relative to one another such that an operator activates the actuator by applying substantially equal forces to move the actuator in the axial direction, thereby rotating the rotatable element relative to the housing and providing the control release to the plunger from a first position relative to the housing in which the plunger device is ready for use to a second position relative to the housing in which the plunger device is configured to expel at least one object and / or substance from the nozzle of the delivery device upon activation.

22. A delivery device for extruding at least one object and / or substance, said delivery device comprising the nozzle for extruding said at least one object and / or substance and a plunger device according to claim 1 or 2.

23. 23. The delivery device of claim 22, wherein the delivery device is configured to expel an intraocular lens into a patient's eye.

24. A method for manufacturing a plunger device according to claim 1 or 2, said method comprising: providing the housing, the plunger, the source of stored mechanical energy, the rotatable element and the actuator of the plunger device of claim 1 or 2; assembling the housing, the plunger, the source of stored mechanical energy, the rotatable element, and the actuator to form the plunger device of claim 1 or 2; A method comprising:

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