Patent Description:
The present disclosure relates generally to surgical systems. More specifically, the present disclosure relates to systems for controlling fluid flow in aspiration and/or irrigation circuits during a surgical procedure using one or more selectively moveable valve elements.

The human eye functions to provide vision by transmitting light through a clear outer portion called the cornea, and focusing the image by way of the lens onto the retina. The quality of the focused image depends upon many factors including the size and shape of the eye, and the transparency of the cornea and lens.

When age or disease causes the lens to become less transparent, vision deteriorates because of the diminished light which can be transmitted to the retina. This deficiency in the lens of the eye is known as a cataract. Ophthalmic surgery is required for treating this condition. More specifically, surgical removal of the deteriorated lens and replacement with an artificial intraocular lens (IOL).

One known technique for removing cataractous lenses is phacoemulsification. During this procedure, a thin phacoemulsification cutting tip is inserted into the diseased lens and vibrated ultrasonically. The vibrating cutting tip liquefies or emulsifies the lens so that the diseased lens may be aspirated out of the eye. Once removed, an artificial lens is inserted therein.

A typical ultrasonic surgical device suitable for ophthalmic procedures includes an ultrasonically driven handpiece, an attached cutting tip, an irrigation sleeve and an electronic control console. The handpiece assembly is attached to the control console by an electric cable and flexible tubing. Through the electric cable, the console varies the power level transmitted by the handpiece to the attached cutting tip and the flexible tubing supplies irrigation fluid to, and draws aspiration fluid from, the eye through the handpiece assembly.

The operative part of the handpiece includes a hollow resonating bar or horn directly attached to a set of piezoelectric crystals. The crystals supply the required ultrasonic vibration needed to drive both the horn and the attached cutting tip during phacoemulsification and are controlled by the console. The crystal/horn assembly is suspended within the hollow body or shell of the handpiece. The handpiece body terminates in a reduced diameter portion or nosecone at the body's distal end. The nosecone accepts the irrigation sleeve. Likewise, the horn bore receives the cutting tip. The cutting tip is adjusted so that the tip projects only a predetermined amount past the open end of the irrigating sleeve.

In use, the ends of the cutting tip and irrigating sleeve are inserted into a small incision of predetermined size in the cornea, sclera, or other location of the eye. The cutting tip is ultrasonically vibrated along its longitudinal axis within the irrigation sleeve by the crystal-driven ultrasonic horn, thereby emulsifying the selected tissue in situ. A hollow bore of the cutting tip communicates with the bore in the horn that in turn communicates with the aspiration line from the handpiece to the console. A reduced pressure or vacuum source in the console draws or aspirates the emulsified tissue from the eye through the open end of the cutting tip, through the cutting tip and horn bores and through the aspiration line, into a collection device. The aspiration of emulsified tissue is aided by a saline flush solution or irrigant that is injected into the surgical site through a small annular gap between the inside surface of the irrigating sleeve and the cutting tip.

Known phacoemulsification systems may even use a surgical cassette to provide a variety of functions for vitreoretinal surgical procedures to assist with effectively managing irrigation and aspiration flows into and out of the surgical site through the surgical device. More specifically, the cassette acts as the interface between surgical instrumentation and the patient and delivers pressurized irrigation and aspiration flows into and out of the eye. A variety of pumping systems have been used in connection with a surgical cassette in fluidics systems for cataract surgery, including positive displacement systems (most commonly, peristaltic pumps) and vacuum based aspiration sources. A peristaltic system uses a series of rollers acting upon an elastomeric conduit to create flow in the direction of rotation, while vacuum based systems employ a vacuum source, typically applied to the aspiration flow through an air-liquid interface. <CIT>, <CIT>, and <CIT> are representative of the state of the art.

During surgical procedures, the hollow, resonating tip can become occluded with tissue. In such an instance, vacuum can build in the aspiration line downstream of the occlusion. When the occlusion eventually breaks apart, this pent up vacuum can, depending upon vacuum level and the amount of aspiration path compliance, draw a significant amount of fluid from the eye, thereby increasing the risk of anterior chamber shallowing or collapse. This situation is commonly referred to as occlusion break surge.

To address this concern, surgical consoles are configured with sensors in the aspiration path to allow detection of vacuum level and limiting of vacuum by the system to a predetermined maximum level. While limiting the maximum vacuum level in such a manner may be effective to reduce the potential magnitude of an occlusion break surge, such limitations on the maximum vacuum level can reduce effectiveness of lens removal and increase overall surgical time. In some systems, an audible indication of relative vacuum level and/or vacuum reaching the user preset limit may be provided so that the surgeon can take appropriate precautions.

For example, in some systems, vacuum is commonly relieved upon a command from the surgeon to open a vent valve that connects the aspiration line to a pressure source that is maintained at or above atmospheric pressure. Depending upon the system, this might be the irrigation line, the pump exhaust line or a line connected to atmospheric air (air venting system). However, there are some concerns with known vent valves. First, known vent valves are only configured for simple "on/off action. For example, pinched tubing valves or elastomer dome type valves may provide satisfactory on/off control of fluid flow but do not exhibit consistent variable flow characteristics. As such, this type of valve has a very sharp surge recovery curve. Moreover, the configuration of dome type valves also may present operational challenges. For example, the operation of the valve is highly dependent upon the elastomer material to obtain a proper seat position, thus consistency of the material is very important. Further, the flow through the valve may also become clogged by debris if the opening formed by the elastomer is small. In addition, such a configuration may undesirably trap air bubbles. Use of these type of valves is also limited in that due to the nature of the on/off flow control limitation, an array of valves are need to support directing fluid flow from one circuit to another.

Alternatively, vacuum may be reduced or relieved by reversal of the pump rotation in positive displacement systems. While it is known to employ a system having bidirectional pump rotation to allow control of pressure/vacuum level based on user input and feedback from a pressure sensor in the aspiration line, such a system requires rapid acceleration and deceleration of the pump head mass. This can limit response time and cause objectionable acoustical noise.

Known cassettes used with consoles also allow the aspiration line to be vented, either to atmosphere or to a liquid so as to reduce or eliminate vacuum surge upon occlusion break. Prior art air vented cassettes allow ambient air to enter the aspiration line, however, venting air into the aspiration line changes the fluidic performance of the aspiration system by greatly increasing aspiration path compliance. Increased compliance can significantly increase the magnitude of occlusion break surge and also negatively affect system responsiveness. Liquid venting systems allow irrigation fluid to bleed into the aspiration line, thereby reducing any impact on the fluidic performance of the aspiration system. When higher aspiration vacuums are used, cassettes that vent the aspiration line to the irrigation line can cause high pressure surges in the irrigation line. Other systems provide a separate source of irrigation fluid to vent the aspiration line, requiring the use of two irrigation fluid sources and increasing the cost and complexity of the system.

The present invention provides an aspiration circuit for a fluidics system for selectively controlling aspiration, in accordance with claims which follow. Various arrangements of fluidics systems are disclosed. In one exemplary arrangement, an aspiration circuit for a fluidics system is proposed that selectively controls aspiration. The aspiration circuit comprises an aspiration line operatively connected to a surgical instrument, an aspiration exhaust line operatively connected to a waste receptacle; an aspiration vent line connected at a first end to the aspiration line; and a selectively variable vent valve operatively connected to the aspiration vent line. The variable vent valve is configured to be selectively actuated to vary aspiration pressure within the aspiration line. In another exemplary arrangement, the variable vent valve is configured as a multi-purpose valve that can vary aspiration pressure and selectively interrupt irrigation fluid flow. In yet another exemplary arrangement, the variable vent valve is configured as a multi-purpose valve that can vary aspiration pressure, as well as direct aspiration from either a displacement-based and/or vacuum-based aspiration source.

Exemplary embodiments of the present disclosure will now by described by way of example in greater detail with reference to the attached figures, in which:.

Referring now to the discussion that follows and also to the drawings, illustrative approaches to the disclosed devices and methods are shown in detail. Although the drawings represent some possible approaches, the drawings are not necessarily to scale and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present disclosure. Further the descriptions set forth herein are not intended to be exhaustive or otherwise limit or restrict the claims to the precise forms and configurations shown in the drawings and disclosed in the following detailed description.

Phacoemulsification machines are typically used in cataract eye surgery to remove cataract-affected eye lenses, such machines typically employ fluidics systems for introducing irrigative fluid into the surgical site, as well as providing aspiration from the surgical site to remove emulsified tissue. In some known systems a positive displacement system, such as a pump, is employed to provide appropriate aspiration. Referring to <FIG>, an exemplary arrangement of a pump <NUM> for a phacoemulsification system is shown. Pump <NUM> includes a pump motor <NUM> and a roller head <NUM> containing one or more rollers <NUM>. Pump <NUM> may be used in combination with a cassette <NUM> having an elastomeric sheet <NUM> applied to the exterior of a relatively rigid body or substrate <NUM>. Pump motor <NUM> may be a stepper or DC servo motor. Roller head <NUM> is attached to a shaft <NUM> of pump motor <NUM> such that pump motor <NUM> rotates roller head <NUM> in a plane generally perpendicular to the axis A-A of shaft <NUM>. Shaft <NUM> may also contain a shaft position encoder <NUM>.

Sheet <NUM> of cassette <NUM> contains a fluid channel <NUM> that may be molded therein, channel <NUM> being configured to be generally planar and arcuate in shape (within the plane). Fluid channel <NUM> has a radius approximating that of rollers <NUM> about shaft <NUM>.

Cassette <NUM> is designed to be mounted in a cassette receiver <NUM> of a console <NUM> (as shown in <FIG>). Cassette <NUM> operatively couples console <NUM> to a handpiece <NUM> (an exemplary schematic arrangement of handpiece <NUM> is shown in <FIG>). Handpiece <NUM> generally includes an infusion sleeve <NUM> and a tip member <NUM>, whereby tip member <NUM> is positioned coaxially within infusion sleeve <NUM>. Tip member <NUM> is configured for insertion into an eye <NUM>. Infusion sleeve <NUM> allows irrigation fluid to flow from console <NUM> and/or cassette <NUM> into the eye. Aspiration fluid may also be withdrawn through a lumen of tip member <NUM>, with console <NUM> and cassette <NUM> generally providing aspiration/vacuum to tip member <NUM>. Collectively, the irrigation and aspiration functions of phacoemulsification system <NUM> are hereby referred to as a phaco fluidics system <NUM>.

Referring now to <FIG>, an exemplary phaco fluidics system <NUM><NUM> will be described for use with a positive displacement system (i.e., pump <NUM>). Infusion sleeve <NUM> of handpiece <NUM> is connected to an irrigation source <NUM>, which contains an irrigation fluid, by suitable tubing (i.e., irrigation line <NUM>). In one exemplary arrangement, irrigation source <NUM> may be a pressurized irrigation source (e.g., a bag of irrigation fluid that is selectively compressed to deliver irrigation fluid to an irrigation supply line). Tip member <NUM> is connected to an input port <NUM> of a pump, such as pump <NUM>, by a length a suitable tubing (i.e., aspiration line <NUM>).

An aspiration exhaust line <NUM> extends from pump <NUM>. In one exemplary arrangement, aspiration exhaust line <NUM> is fluidly connected to a drain line reservoir <NUM>. Reservoir <NUM> may also drain into an optional drain bag <NUM>. Alternatively, as shown in phantom, exhaust line <NUM>' may be fluidly connected directly to drain bag <NUM>.

An aspiration vent line <NUM> is fluidly connected between aspiration line <NUM> and aspiration exhaust line <NUM>. Vent line <NUM> is configured as a bypass circuit. A vent valve <NUM>, to be discussed in further detail below, is fluidly connected to aspiration vent line <NUM> so as to selectively control the aspiration pressure within aspiration line <NUM>. A pressure sensor <NUM> is also in fluid communication with aspiration line <NUM> to detect aspiration pressure within aspiration line <NUM>. Pressure sensor <NUM> is also operatively connected to a control system in console <NUM>. The control system may be configured to provide pre-set aspiration pressure levels for fluidics system <NUM>, as will be explained below in further detail.

As described above, irrigation source <NUM>, which may be pressurized, is fluidly connected to handpiece <NUM> by irrigation line <NUM>. An irrigation valve <NUM> is fluidly connected to and positioned between irrigation line <NUM> and infusion sleeve <NUM>. Irrigation valve <NUM> provides selective on/off control of irrigation fluid in irrigation line <NUM>.

Vent valve <NUM> is configured to provide a variable orifice size within vent line <NUM> to selectively modulate aspiration within aspiration line <NUM>. More specifically, use of a variable vent valve <NUM> enables unidirectional rotation of pump <NUM> in a first direction to generate flow/vacuum, while permitting a mechanism for dynamically controlling aspiration pressure to handpiece <NUM>. In one exemplary vent valve <NUM> may be configured as a multi- position rotary type valve that would allow predictable and precise control of the orifice size based on angular position of vent valve <NUM> within vent line <NUM>.

An exemplary configuration of vent valve <NUM> is shown in <FIG>. In <FIG>, in one exemplary configuration, multi-position vent valve <NUM> includes a channel <NUM> defined by first and second openings <NUM> and <NUM>. While channel <NUM> is shown in <FIG> as being generally uniformly sized from first opening <NUM> to second opening <NUM>, it is understood that channel <NUM> may be configured with a variable size. For example, first <NUM> and second openings <NUM> may be configured with a diameter that is larger than a central portion of channel <NUM> such that first and second openings <NUM> and <NUM> flare outwardly toward a periphery <NUM> of vent valve <NUM>.

In operation, vent valve <NUM> is selectively rotatable in an aspiration circuit, such that the angular position of channel <NUM> is selectively moveable within vent line <NUM>. Such movement may full open, partially occlude, and/or completely occlude, first and second opening <NUM> and <NUM> so as to selectively control the aspiration pressure within aspiration line <NUM>.

Pressure sensor <NUM> is operably connected to a control system mounted in console <NUM>. Pressure sensor <NUM> detects and communicates pressure changes in aspiration line <NUM> during operation of the phacoemulsification machine. In one exemplary configuration, predetermined pressure thresholds can be set within the control system such that when pressure readings from pressure sensor <NUM> exceed those thresholds, the control system may selectively modify the aspiration pressure within aspiration line <NUM>. For example, if the pressure sensor <NUM> detects that the aspiration pressure has exceed the predetermined pressure threshold, console <NUM> triggers movement of vent valve <NUM> within vent line <NUM> by a predetermined amount to permit venting of aspiration line <NUM> sufficient to drop the aspiration pressure below the pre-set threshold. Thus, pressure sensor <NUM>, vent valve <NUM> and the control system cooperate to permit real-time modulation of aspiration within aspiration line <NUM> which permits a higher maximum aspiration level to be utilized, but still providing effective occlusion break surges.

For example, referring back to <FIG>, channel <NUM> of vent valve <NUM> is positioned such that first and second openings <NUM> and <NUM> are positioned out of alignment with vent line <NUM>. In this position, vent valve <NUM> is in a "fully closed" position thereby blocking vent line <NUM> and providing unimpeded aspiration pressure to aspiration line <NUM>. If pressure sensor <NUM> detects that aspiration pressure has increased within aspiration line <NUM> above the threshold level, vent valve <NUM> may be selectively moved by a predetermined amount so as to move first and second openings <NUM> and <NUM> into at least partial alignment, thereby partially opening aspiration exhaust line <NUM>/<NUM>'. This action quickly and effectively restores the aspiration pressure within aspiration line <NUM> to a predetermined acceptable amount, without requiring pump reversal. However, it is understood that due to the configuration of channel <NUM>, a variety of aspiration pressures may be achieved by selective movement of the vent valve <NUM>.

Vent valve <NUM> is operably connected to an actuator, such as a motor <NUM>, having an angular position encoder (such as encoder <NUM>). One such exemplary motor <NUM> includes a stepper motor. When pressure sensor <NUM> detects that aspiration pressure has exceed a predetermined threshold, the controller may automatically operate motor <NUM> to rotate vent valve <NUM> to a predetermined angular position, thereby quickly changing aspiration pressure within aspiration line <NUM>. Further, the controller, in cooperation with a pressure sensor positioned in irrigation line <NUM>, may be configured to detect and minimize an occlusion break onset. More specifically, vent valve <NUM> may be automatically rotated by motor <NUM> to reduced aspiration pressure within aspiration line <NUM>. This function would operate to lessen an effect of a post occlusion break surge. Because vent valve <NUM> permits selective and dynamic control of aspiration levels within aspiration line <NUM>, vacuum levels may be easily modulated for the user's preference, thereby providing quicker and more efficient lens removal.

Referring now to <FIG>, components of an alternative exemplary phaco fluidics system <NUM> for use with a positive displacement pumping system is shown. Phaco fluidics system <NUM> includes many of the same components as shown and described above in connection with <FIG>. Accordingly, like components have been given the same reference numbers. For a description of those components, reference is made to the discussion above with respect to <FIG>.

In phaco fluidics system <NUM>, an aspiration exhaust line <NUM>' extends from pump <NUM> and is fluidly connected to a drain bag <NUM>. Alternatively, as shown in <FIG>, phaco fluidics system <NUM> may include an exhaust line <NUM> that is fluidly connected to a drain line reservoir.

An aspiration vent line <NUM> is fluidly connected between aspiration line <NUM> and atmosphere <NUM>. A variable vent valve <NUM> is fluidly connected to aspiration vent line <NUM> so as to selectively control the aspiration pressure within aspiration line <NUM>. Pressure sensor <NUM> is also in fluid communication with aspiration line <NUM>.

As discussed above, vent valve <NUM> is configured to provide a variable orifice size to selectively modulate vacuum, thereby allowing unidirectional rotation of pump <NUM> to generate flow/vacuum, while permitting selective control of vacuum/aspiration to handpiece <NUM> based on angular position of vent valve <NUM>. Vent valve <NUM> is configured to be selectively rotatable to dynamically control aspiration within aspiration line <NUM>.

As discussed above, in operation, pressure sensor <NUM> is operably connected to a control system mounted in console <NUM>. Pressure sensor <NUM> detects and communicates pressure changes in aspiration line <NUM> during operation of the phacoemulsification machine. In one exemplary configuration, predetermined pressure thresholds are set by the users within the control system. Accordingly, when pressure sensor <NUM> detects an aspiration pressure level that exceeds the pre-set thresholds, the control system moves vent valve <NUM> by a predetermined amount to reduce the aspiration pressure within aspiration line <NUM> by positioning channel <NUM> in vent valve <NUM> in at least partial communication with atmosphere <NUM>. It is also understood that vent valve <NUM> may be fully opened to atmosphere <NUM> to effectively fully vent aspiration line <NUM>. It is also understood that vent valve <NUM> may be selectively moved to fully close vent line <NUM> to atmosphere <NUM>, thereby effectively providing full vacuum/aspiration pressure in aspiration line <NUM> to tip member <NUM>. Movement of vent valve <NUM> to selectively adjust the aspiration pressure within aspiration line <NUM> may be accomplished either manually (e.g., selective operation of a footswitch treadle based on prior user settings) or automatically by motor <NUM> that is operatively connected to the control system.

Referring now to <FIG>, components of another alternative exemplary phaco fluidics system <NUM> for use with a positive displacement pumping system is shown. Phaco fluidics system <NUM> includes many of the same components as shown and described above in connection with <FIG> and <FIG>. Accordingly, like components have been given the same reference numbers. For a detailed discussion of those components, reference is made to the discussion above with respect to <FIG>.

An aspiration vent line <NUM> is fluidly connected between aspiration line <NUM> and a vent pressure source <NUM>. Examples of suitable vent pressure sources include, but are not limited to, a pressurized fluid or saline. Variable vent valve <NUM> is fluidly connected to aspiration vent line <NUM> so as to selectively control the aspiration pressure within aspiration line <NUM>. Pressure sensor <NUM> is also in fluid communication with aspiration line <NUM>.

Vent valve <NUM> is configured to provide a variable orifice size to selectively modulate vacuum, thereby allowing unidirectional rotation of pump <NUM> in a first direction to generate flow/vacuum, while permitting selective control of vacuum/aspiration to handpiece <NUM> based on the angular position of vent valve <NUM>.

Pressure sensor <NUM> is operably connected to a control system mounted in console <NUM> and detects and communicates pressure changes in aspiration line <NUM> during operation of the phacoemulsification machine. In one exemplary configuration, predetermined pressure thresholds are set within the control system such that when pressure readings from pressure sensor <NUM> exceed those thresholds, vent valve <NUM> is moved by a predetermined amount to reduce the aspiration pressure within aspiration line <NUM>. This is accomplished by positioning channel <NUM> in vent valve <NUM> in at least partial communication with a vent pressure source <NUM>, thereby opening vent line <NUM>, and permitting pressurized fluid (for example) to enter into aspiration line <NUM>. Motor <NUM> may be operably connected to vent valve <NUM> to automatically move vent valve <NUM> by a predetermined amount to automatically control the level of vacuum/aspiration pressure in aspiration line <NUM> based on information received from sensor <NUM>. It is also understood that vent valve <NUM> may be fully opened to vent pressure source <NUM> to effectively negate aspiration pressure in aspiration line <NUM>, without need to interrupt pump <NUM> operation. Alternatively, it is also understood that vent valve <NUM> may be fully closed, i.e., channel <NUM> being positioned completely out of alignment with vent line <NUM>, such that vent pressure source <NUM> is not in communication with vent line <NUM>. This configuration effectively provides full vacuum/aspiration pressure in aspiration line <NUM> to tip member <NUM>.

Referring now to <FIG>, components of a yet another alternative exemplary phaco fluidics system <NUM> for use with a positive displacement pumping system is shown. Phaco fluidics system <NUM> includes many of the same components as shown and described above in connection with <FIG> and <FIG>. Accordingly, like components have been given the same reference numbers. For a detailed discussion of those components, reference is made to the discussion above with respect to <FIG>.

An aspiration vent line <NUM> is fluidly connected between aspiration line <NUM> and irrigation line <NUM>. Variable vent valve <NUM> is fluidly connected to aspiration vent line <NUM> so as to selectively control the aspiration pressure within aspiration line <NUM>. A pressure sensor <NUM> is also in fluid communication with aspiration line <NUM>.

Vent valve <NUM> is configured to provide a variable orifice size to selectively modulate vacuum, thereby allowing uninterrupted unidirectional rotation of pump <NUM> in a first direction to generate flow/vacuum, while permitting selective control of vacuum/aspiration to handpiece <NUM> based on angular position of vent valve <NUM>.

Pressure sensor <NUM> is operably connected to a control system mounted in console <NUM> and detects and communicates pressure changes in aspiration line <NUM> during operation of the phacoemulsification machine. In one exemplary configuration, predetermined pressure thresholds are set within the control system such that when pressure readings from pressure sensor <NUM> exceed those thresholds, vent valve <NUM> may be selectively moved by a predetermined amount to reduce, for example, the aspiration pressure within aspiration line <NUM>. For example, channel <NUM> in vent valve <NUM> is moved so as to be in at least partial alignment with vent line <NUM>, thereby placing aspiration line <NUM> in at least partial communication with irrigation line <NUM> by a predetermined amount to automatically control the level of vacuum/aspiration pressure in aspiration line <NUM> based on information received from sensor <NUM>. It is understood that vent valve <NUM> may be fully opened to irrigation line <NUM> to effectively negate aspiration pressure in aspiration line <NUM>. Alternatively, it is also understood that vent valve <NUM> may be positioned so as to fully close irrigation line <NUM>, thereby effectively providing full vacuum/aspiration pressure in aspiration line <NUM> to tip member <NUM>. In such a configuration, channel <NUM> is fully aligned with vent line <NUM>.

Referring now to <FIG>, components of yet another alternative exemplary phaco fluidics system <NUM> for use with a positive displacement pumping system is shown. Phaco fluidics system <NUM> includes many of the same components as shown and described above in connection with <FIG> and <FIG>.

Phaco fluidics system <NUM> includes infusion sleeve <NUM> of handpiece <NUM> that is connected to an irrigation source <NUM> by irrigation line <NUM>. Phaco fluidics system <NUM> may also include a multi-position irrigation valve <NUM> that is fluidly connected to and positioned at a three-way junction between an irrigation supply line <NUM>, irrigation line <NUM> and a shunt line <NUM>. An irrigation line pressure sensor <NUM> may be positioned in irrigation line <NUM> between shunt line <NUM> and infusion sleeve <NUM>. Handpiece <NUM> may also be provided with a handpiece pressure sensor <NUM>.

While irrigation source <NUM> may be any suitable irrigation source, in one exemplary arrangement, irrigation source <NUM> is pressurized. More specifically, an irrigation bag <NUM> may be provided that is positioned against a platform <NUM> and a pressurizing force, represented by arrows <NUM>, is applied to irrigation bag <NUM> so as to force infusion fluid out of irrigation bag <NUM> and into irrigation supply line <NUM>. Other pressurized fluid systems are also contemplated.

Tip member <NUM> is connected to input port <NUM> of a peristaltic pump <NUM> by aspiration line <NUM>. While any suitable pump arrangement may be utilized, in one exemplary configuration, pump <NUM> is a pump such as described in <CIT> , entitled "Multiple Segmented Peristaltic Pump and Cassette" or a pump such as described in <CIT>, entitled "Surgical Cassette Having an Aspiration Pressure Sensor. Aspiration exhaust line <NUM> extends from pump <NUM> and is fluidly connected to a vent reservoir <NUM>. Vent reservoir <NUM> is fluidly connected to a drain bag <NUM>.

An aspiration vent line <NUM> is fluidly connected between aspiration line <NUM> and vent reservoir <NUM>, so as to bypass pump <NUM>. Variable vent valve <NUM> is fluidly connected to aspiration vent line <NUM> so as to selectively control the aspiration pressure within aspiration line <NUM>. An aspiration pressure sensor <NUM> is also in fluid communication with aspiration line <NUM>. Vent valve <NUM> is configured to provide a variable orifice size within vent line <NUM> to selectively modulate vacuum, thereby allowing unidirectional rotation of pump <NUM> in a first direction to generate flow/vacuum, while permitting selective control of vacuum/aspiration to handpiece <NUM> based on the angular position of vent valve <NUM>.

In operation, pressure sensor <NUM> is operably connected to a control system mounted in console <NUM>. Pressure sensor <NUM> detects and communicates pressure changes in aspiration line <NUM> during operation of the phacoemulsification machine. In one exemplary configuration, predetermined pressure thresholds are set within the control system such that when pressure readings from pressure sensor <NUM> exceed those thresholds, vent valve <NUM> may be selectively moved by a predetermined amount to reduce the aspiration pressure within aspiration line <NUM>. This is accomplished by positioning channel <NUM> in vent valve <NUM> in at least partial communication with vent line <NUM>. Because vent line <NUM> is operably connected to vent reservoir <NUM>, the partial communication of channel <NUM> with vent line <NUM> effectively reduces aspiration pressure within aspiration line <NUM>. Movement of vent valve <NUM> may be accomplished by motor <NUM> that is connected to vent valve <NUM>. More specifically, motor <NUM> may be configured to automatically move vent valve <NUM> by a predetermined amount to automatically control the level of vacuum/aspiration pressure in aspiration line <NUM> based on information received from sensor <NUM>. It is understood that vent valve <NUM> may be oriented to a fully opened position to fully vent aspiration line to vent reservoir <NUM> to effectively close off input port <NUM> to pump <NUM>. Alternatively, it is also understood that vent valve <NUM> may be fully closed, i.e., such that channel <NUM> is out of alignment with vent line <NUM>, thereby closing vent reservoir <NUM> to aspiration line <NUM>, thereby effectively providing full vacuum/aspiration pressure in aspiration line <NUM> to tip member <NUM>.

As stated above, phaco fluidics system <NUM> also provides a multi-position irrigation valve <NUM> that is positioned at a junction between irrigation supply line <NUM>, irrigation line <NUM> and shunt line <NUM>. As explained in further detail below, irrigation valve <NUM> is configured as a rotary valve that may be operatively positioned to selectively control irrigation in phaco fluidics system <NUM>. As shown in <FIG>, in one exemplary arrangement, multi-position irrigation valve <NUM> includes an intersecting channel
configuration <NUM>. More specifically, channel <NUM> includes a first branch 474A, a second branch 474B and a third branch 474C. While shown as having a T-shaped configuration, it is understood that other intersecting configuration may be utilized, depending on the configuration of the various fluid lines in fluidics system <NUM>.

In operation, as shown in <FIG>, when irrigation valve <NUM> is oriented such that first branch 474A is fully aligned with irrigation supply line <NUM> and third branch 474B is fully aligned with irrigation line <NUM>, but second branch 474C is oriented out of alignment with shunt line <NUM>, normal, full irrigation flow is provided to irrigation line <NUM>. However, to prime irrigation supply <NUM> of phaco fluidics system <NUM>, irrigation valve <NUM> may be selectively rotated such that first branch 474A is fully aligned with shunt line <NUM> and third branch 474C is fully aligned with irrigation supply line <NUM>. Accordingly, when phaco fluidics system <NUM> is operated, fluid from irrigation supply <NUM> is directed to drain bag <NUM>. To prime irrigation pressure sensor <NUM>, irrigation valve <NUM> may be selectively rotated such that second arm 474B is fully aligned with shunt line <NUM> and third arm 474C is fully aligned with irrigation line <NUM>.

While the various branches of irrigation valve <NUM> shown in <FIG> has been described as operating so as to be fully aligned with either the irrigation line <NUM>, shunt line <NUM> and irrigation supply line <NUM>, it is also understood that branches 474a-474c need not be fully aligned with the respective lines <NUM>, <NUM>, and <NUM>. Indeed, irrigation valve <NUM> may be configured to be selectively positioned so as to effectively control the amount of fluid to be delivered to eye <NUM>. Indeed, in some patients, a full irrigation flow (such a shown in <FIG>), may lead to patient discomfort, while a controlled opening whereby certain branches of irrigation valve <NUM> is positioned at various angular positions with respect to irrigation line <NUM> may be desirable. Thus, similar to vent valve <NUM>, irrigation valve <NUM> may also be configured for variable irrigation delivery.

Another alternative configuration for a multi-position irrigation valve is shown in <FIG>. In this arrangement, a multi-position irrigation valve <NUM>' is provided having an L-shaped pathway formed therein. Multi-position irrigation valve <NUM>' includes a first branch 474A' and a second branch 474B'. Use of multi-position irrigation valve <NUM>' will be described below in connection with <FIG> OA- I OC.

Referring to <FIG>, components of another alternative exemplary phaco fluidics system <NUM>' for use with a positive displacement pumping system is shown. Phaco fluidics system <NUM>' includes many of the same components as shown and described above in connection with <FIG> and <FIG>. In some embodiments, the components inside of the dashed box may at least partially be included in a fluidics cassette configured to be secured to a surgical console.

Phaco fluidics system <NUM>' includes infusion sleeve <NUM> of handpiece <NUM> that is connected to an irrigation source <NUM> by irrigation line <NUM>. A multi-position irrigation valve <NUM>' is fluidly connected to and positioned at a three-way junction between an irrigation supply line <NUM>, irrigation line <NUM> and a shunt line <NUM>. An irrigation line pressure sensor <NUM> may be positioned in irrigation line <NUM> between irrigation supply <NUM> and handpiece <NUM>. While irrigation source <NUM> may be any suitable irrigation source, in one exemplary arrangement, irrigation source <NUM> includes an irrigation container that utilizes gravity to force infusion fluid out of the irrigation container and into irrigation supply line <NUM>.

Multi-position irrigation valve <NUM>' may be configured as a rotary valve that may be operatively positioned to selective control irrigation in phaco fluidics system <NUM>'. Thus, in operation, as shown in <FIG>, when irrigation valve <NUM>' is oriented such that first branch 474A' is aligned with irrigation line <NUM> and second branch 474B' is oriented so as to be out of alignment with irrigation supply line <NUM> and shunt line <NUM>, no irrigation is supplied to irrigation line <NUM>.

Referring now to <FIG>, to supply irrigation to handpiece <NUM>, irrigation valve <NUM>' may be selectively rotated such that first branch 474A' is at least partially aligned with irrigation supply line <NUM> and second branch 474B' is at least partially aligned with irrigation line <NUM>. Accordingly, fluid from irrigation supply <NUM> is directed through irrigation supply line <NUM>, to irrigation line <NUM> through irrigation valve <NUM>' and to handpiece <NUM>. As with irrigation valve <NUM>, it may be desirable to selectively position first and second branches 474A' and 474B' so as to effectively control the amount of fluid to be delivered to eye <NUM>. Thus, it is contemplated that irrigation line <NUM> may be subject to a controlled opening with irrigation supply line <NUM>, whereby first and second branches 474A' and 474B' of irrigation valve <NUM>' is positioned at various angular positions to provide less than full irrigation flow through irrigation line <NUM>. Thus, similar to vent valve <NUM>, irrigation valve <NUM>' may also be configured for variable irrigation delivery.

<FIG> illustrates a priming operation for irrigation supply <NUM> of phaco fluidics system <NUM>' by actuation of irrigation valve <NUM>'. More specifically, irrigation valve <NUM>' may be selectively rotated such that first branch 474A' is at least partially aligned with shunt line <NUM> and second branch 474B' is at least partially aligned with irrigation supply line <NUM>. Accordingly, when phaco fluidics system <NUM> is operated, fluid from irrigation supply <NUM> is directed to drain bag <NUM>.

While multi-position irrigation valves <NUM> and <NUM>' have both been described in connection with a phaco fluidics system <NUM> that also incorporates a variable vent valve <NUM>, it is understood that the scope of the present disclosure is not limited to a phaco fluidics system <NUM> that includes both a multi-position irrigation valve <NUM>/<NUM>' and a variable vent valve <NUM>. Further, multi-position irrigation valves <NUM>/<NUM>' are capable of operating in an "on/off type fashion, or, as described above, multi-position irrigation valves <NUM>/<NUM>' may also be configured to provide a variable orifice so as to selectively control the amount of irrigation, in a manner similar to that which has been previously described in connection with variable vent valve <NUM>. For example, the amount of irrigation to be provided to handpiece <NUM> from irrigation supply line <NUM> may be selectively controlled by a multi-position variable irrigation line, such that less than full irrigation from irrigation supply line <NUM> may be supplied to irrigation line <NUM> (and thus handpiece <NUM>). In such an instance, multi-position variable irrigation valve <NUM>/<NUM>' is selectively rotated so as to provide only partial communication with both irrigation supply line <NUM> and irrigation line <NUM>.

Referring now to <FIG>, components of a yet another alternative exemplary phaco fluidics system <NUM> for use with a positive displacement pumping system is shown. Phaco fluidics system <NUM> includes many of the same components as shown and described above in connection with <FIG>, and <FIG>. Accordingly, like components have been given the same reference numbers. For a detailed discussion of those components, reference is made to the discussion above with respect to <FIG>.

Phaco fluidics system <NUM> includes infusion sleeve <NUM> of handpiece <NUM> that is connected to irrigation source <NUM> by an irrigation supply line <NUM> that is fluidly connected to an irrigation line <NUM>. An aspiration exhaust line <NUM> extends from pump <NUM>. In one exemplary arrangement, aspiration exhaust line <NUM> is fluidly connected to a drain line reservoir <NUM>. Reservoir <NUM> may also drain into an optional drain bag <NUM>. Alternatively, as shown in phantom, exhaust line <NUM>' may be fluidly connected directly to drain bag <NUM>.

An aspiration vent line <NUM> is fluidly connected between aspiration line <NUM> and irrigation line <NUM>. A multi-purpose proportional valve <NUM> is fluidly connected between aspiration vent line <NUM> and irrigation line <NUM> so as to selectively control the aspiration pressure within aspiration line <NUM> and irrigation flow within irrigation line <NUM>. Pressure sensor <NUM> is also in fluid communication with aspiration line <NUM>.

Multi-purpose valve <NUM> is configured to provide a variable orifice size to selectively modulate aspiration, thereby allowing unidirectional rotation of pump <NUM> in a first direction to generate flow/vacuum, while permitting selective control of vacuum/aspiration to handpiece <NUM> based on the angular position of multi-purpose valve <NUM>, as well as providing irrigation control. More specifically, in one exemplary configuration, referring to <FIG>, the body of multi-purpose valve <NUM> is defined by a periphery <NUM>. The body has a first flow path 563A formed in one portion of the periphery <NUM> and a second flow path 563B formed in another portion of the periphery <NUM>.

Referring back to <FIG>, in operation, multi-purpose valve <NUM> is selectively rotatable within a groove <NUM> formed in cassette <NUM>. More specifically, operably connected to groove <NUM> are a plurality of fluid lines that are selectively connectable to one another via the angular position of multi-purpose valve <NUM>. For example, in phaco fluidics system <NUM> shown in <FIG>, multi-purpose valve <NUM> serves to operatively connect irrigation supply line <NUM>, irrigation line <NUM>, aspiration line <NUM> and aspiration exhaust line <NUM>/<NUM>' via first and second flow paths 563A, 563B. Multi-purpose valve <NUM> is moveable within groove <NUM> so as to provide a variety of connection arrangements with respect to aspiration line <NUM>, irrigation line <NUM>, irrigation supply line <NUM> and aspiration exhaust line <NUM>/<NUM>' may be achieved, as will be explained in further detail below.

Pressure sensor <NUM> is operably connected to a control system mounted in console <NUM> and is configured to detect and communicate pressure changes in aspiration line <NUM> during operation of the phacoemulsification machine. In one exemplary configuration, predetermined pressure thresholds are set within the control system such that when pressure readings from pressure sensor <NUM> exceed those thresholds, the control system may selectively move multi-purpose valve <NUM> by a predetermined amount to reduce the aspiration pressure within aspiration line <NUM>. More specifically, second flow path 563B in multi-purpose valve <NUM> is moveable with respect to aspiration vent line <NUM>.

For example, multi-purpose valve <NUM> may be positioned within groove <NUM> and selectively rotated such that second flow path 563B fully closes aspiration vent line <NUM> off from aspiration line <NUM>, such that full vacuum, as dictated by the user's pre-selected pressure settings, is provided. However, if pressure has increased within aspiration line <NUM> by an undesirable amount (such as, for example, because of an occlusion break surge), multipurpose valve <NUM> may be selectively moved by a predetermined amount such that second flow path 563B operatively connects aspiration line <NUM>/<NUM>' directly to aspiration line <NUM>, via aspiration vent line <NUM>, thereby bypassing pump <NUM>. This action quickly and effectively restores the aspiration pressure within aspiration line <NUM> to the predetermined acceptable amount, without requiring pump reversal.

In one exemplary arrangement, multi-purpose valve <NUM> may be operably connected to a footswitch treadle. Accordingly, the user may operate the footswitch treadle to rotate multi-purpose valve <NUM> to selectively vent (e.g., by lifting his/her foot from the treadle) aspiration line <NUM>. The footswitch treadle may be configured to rotate multi-purpose valve <NUM> by a predetermined amount and in a predetermined direction, based on the control system settings, based on user input. Due to the configuration of second flow path 563B, a variety of aspiration pressures may be achieved by selective movement of multi-purpose valve <NUM>. In some exemplary situations, it may be desirable to fully open exhaust line <NUM>/<NUM>', thereby fully venting aspiration line <NUM>.

In another exemplary arrangement, multi-purpose valve <NUM> is operably connected to a motor <NUM> such as a stepper motor, having an angular position encoder (such as encoder <NUM>). When pressure sensor <NUM> detects that aspiration pressure has exceed a predetermined threshold, the controller automatically operates motor <NUM> to rotate multipurpose valve <NUM> to a predetermined position, thereby quickly changing aspiration pressure within aspiration line <NUM>. As the controller, in cooperation with pressure sensor <NUM>, may be configured to detect an occlusion break onset, multi-purpose valve <NUM> may be automatically rotated by motor <NUM> to reduced aspiration pressure within aspiration line <NUM> below predetermined settings. This function would operate to lessen the post occlusion surge. Because multi-purpose valve <NUM> permits selective and dynamic control of aspiration levels within aspiration line <NUM>, higher vacuum rates may be selected and employed by the user for quicker and more efficient lens removal.

In addition to selectively controlling the aspiration levels within the system <NUM>, multi-purpose valve <NUM> also serves an additional purpose, namely controlling irrigation through irrigation line <NUM>. More specifically, first flow path 563A is configured to selectively connect irrigation supply line <NUM> to irrigation line <NUM> when first flow path 563A is in communication with both irrigation supply line <NUM> and irrigation line <NUM>. However, multipurpose valve <NUM> may be selectively rotated such that first flow path 563A is placed out of communication with irrigation supply line <NUM>, thereby effectively closing off irrigation.

Moreover, the configuration of multi-purpose valve <NUM> also permits the selective control of the aspiration level while simultaneously controlling irrigation. For example, multi-purpose valve <NUM> and fluid lines <NUM>, <NUM>, <NUM>/<NUM>', and <NUM> are configured such that when first flow path 563A is in communication with both irrigation line <NUM> and irrigation supply line <NUM>, second flow path 563B is only in communication with exhaust line <NUM>/<NUM>', leaving aspiration line <NUM> closed to exhaust line <NUM>/<NUM>'. In this arrangement, irrigation is supplied to handpiece <NUM> and vent line <NUM> is closed. Alternatively, multi-purpose valve <NUM> may be rotated slightly from the "irrigation line open, vent line closed" position such that second flow path 563B is open to both aspiration line <NUM> and exhaust line <NUM>/<NUM>', while first flow path 563A is in communication with both irrigation line <NUM> and irrigation supply line <NUM>. In this configuration, irrigation is being supplied to handpiece <NUM> and aspiration line <NUM> is operatively connected to exhaust line <NUM>/<NUM>' thereby reducing, if not eliminating aspiration pressure within aspiration line <NUM>. This design effectively eliminates a valve element from system <NUM>, while still providing for selectively varying aspiration pressure and selectively controlling irrigation.

Referring now to <FIG>, a partial schematic of an alternative aspiration circuit <NUM> for use in a phaco fluidics system is shown. Aspiration circuit <NUM> employs both displacement-based and/or vacuum-based aspiration modes. Aspiration circuit <NUM> includes an aspiration line <NUM> that fluidly connects to handpiece <NUM> to either an input port <NUM> of peristaltic pump <NUM> or an input port <NUM> of a venturi reservoir <NUM>. Aspiration exhaust lines <NUM>/<NUM>' extend from input port <NUM> of venturi reservoir <NUM> and input port <NUM> of peristalitic pump <NUM>, respectively. While prior art configurations used separate valves to close and open input port <NUM> of venturi reservoir <NUM> and to provide selective venting of aspiration line <NUM> to a drain bag <NUM>, aspiration circuit <NUM> employs a multi-purpose valve <NUM> that is disposed within a sealed groove of a cassette (similar to that shown in <FIG> above) that provides both functions.

More specifically, referring to <FIG>, in one exemplary arrangement multi-purpose valve <NUM> is configured with a channel <NUM> that is defined by a first opening <NUM> and a second opening <NUM>. In one exemplary arrangement, second opening <NUM> may be configured with an outwardly extending flare. Alternatively, channel <NUM> may be configured with a triangular shape that flares outwardly toward a periphery <NUM> of multi-purpose valve <NUM>. First opening <NUM> is positioned transverse to channel <NUM>. Second opening is formed through a periphery <NUM> of multi-purpose valve <NUM>.

Referring to <FIG>, during operation, multi-purpose valve <NUM> may be positioned such that aspiration is delivered to aspiration line <NUM> by pump <NUM>. In this configuration, multi-purpose valve <NUM> is selectively rotated such that input line <NUM> to venturi reservoir is closed and aspiration exhaust line <NUM> is closed off from aspiration line <NUM>. In this configuration, full aspiration is provided by pump <NUM>.

A pressure sensor <NUM> may be positioned in input line <NUM> to detect and monitor the pressure in aspiration line <NUM>. Pressure sensor <NUM> is operably connected to a control system mounted in a console. Pressure sensor <NUM> detects and communicates pressure changes in aspiration line <NUM> during operation of the phacoemulsification machine. In one exemplary configuration, predetermined pressure thresholds can be set within the control system such that when pressure readings from pressure sensor <NUM> exceed those thresholds, the system prompts movement of multi-purpose valve <NUM> by a predetermined amount to reduce the aspiration pressure within aspiration line <NUM>. More specifically, referring to <FIG>, multi-purpose valve <NUM> may be rotated such that second opening <NUM> of channel <NUM> is in at least partial fluid communication with aspiration exhaust line <NUM>. Thus, if pressure has increased within aspiration line <NUM> by an undesirable amount (such as, for example, because of an occlusion break surge), multi-purpose valve <NUM> may be selectively moved by a predetermined amount so as to partially open aspiration exhaust line <NUM>, as shown in <FIG>. This action quickly and effectively restores the aspiration pressure within aspiration line <NUM> to the predetermined acceptable amount, without requiring pump reversal. It is understood, however, that channel <NUM> may be rotated such that aspiration line <NUM> is fully opened to aspiration exhaust line <NUM>, if need be.

As discussed above, multi-purpose valve <NUM> may also be used to switch aspiration source from pump <NUM> to venturi reservoir <NUM>. Referring to <FIG>, in this configuration, channel <NUM> is positioned such that second opening <NUM> is in communication with input <NUM> of venturi reservoir <NUM>, thereby connecting aspiration line <NUM> to venturi reservoir <NUM>. However, aspiration exhaust line <NUM> is sealed off from aspiration line <NUM>.

In some embodiments, a fluidics system for use in a surgical system may include an aspiration circuit (comprising an aspiration line operatively connected to a surgical instrument, an aspiration exhaust line operatively connected to a waste receptacle, an aspiration vent line connected at a first end to the aspiration line, and a selectively variable valve operatively connected to the aspiration vent line (wherein the variable valve may be selectively actuated to selectively change aspiration pressure within the aspiration line)) and an irrigation circuit (comprising an irrigation source, an irrigation supply line connected to the irrigation source, and an irrigation line having a first end operatively connected to the irrigation supply line and a second end operatively connected to the surgical device). The fluidics system may further include a shunt path, wherein a first end of the shunt path is operatively connected to the irrigation supply line and a second end of the shunt path is connected to the waste receptacle. The fluidics system may further include a selectively positionable irrigation valve that operatively connects the irrigation supply line, the irrigation line, and the shunt path such that the selectively positionable irrigation valve may be moved to direct irrigation from the irrigation supply line. In some embodiments, the irrigation valve may be a rotary valve and include an intersecting channel formed therein, the channel defining a first branch, a second branch, and a third branch. In some embodiments, the irrigation valve is selectively moveable between a first position, a second position and a third position, wherein in the first position, the first branch is positioned in communication with the irrigation supply line and the second branch is positioned in communication with the irrigation line; wherein in the second position, the first branch is positioned in communication with the shunt path and the third branch is in communication with the irrigation supply line; and wherein in the third position, the first branch is positioned in communication with the irrigation line, the second branch is positioned in communication with irrigation supply line and the third branch is positioned in communication with the shunt path. In some embodiments, the variable valve may also be connected to the irrigation line such that the variable valve may be selectively moved to selectively interrupt fluid flow in the irrigation line and to selectively vary aspiration pressure within the aspiration line. In some embodiments, the variable valve may be configured with first and second flow paths formed therein, wherein the first flow path may be selectively aligned with the irrigation supply line and the irrigation line to open the irrigation line to the irrigation supply source, and wherein the second flow path may be selectively aligned with the aspiration line and the aspiration exhaust line to selectively vary aspiration pressure within the aspiration line.

In some embodiments, an aspiration circuit for a fluidics system for selectively controlling aspiration may include an aspiration line operatively connected to a surgical instrument, a first aspiration exhaust line operatively connected to a waste receptacle, a second aspiration exhaust line operatively connected to a waste receptacle, a displacement-based aspiration source operatively connected to the first aspiration exhaust line, a vacuum-based aspiration source operatively connected to the second aspiration exhaust line, and a selectively variable valve operatively connected to both the displacement-based aspiration source and the vacuum-based aspiration source; wherein the variable valve may be actuated to selectively change aspiration pressure within the aspiration line when the displacement-based aspiration source is employed. In some embodiments, the variable valve may be selectively actuated to provide aspiration pressure to the aspiration line from the vacuum-based aspiration source. In some embodiments, the displacement-based aspiration source is a peristaltic pump and the vacuum-based aspiration source includes a venturi reservoir. In some embodiments, the variable valve further comprises a valve body that includes a channel that is defined by a first opening and a second opening, wherein the first opening is positioned transverse to the length of the channel and wherein the second opening is formed through a periphery of the valve body.

It will be appreciated that the devices and methods described herein have broad applications. The foregoing embodiments were chosen and described in order to illustrate principles of the methods and apparatuses as well as some practical applications. The preceding description enables others skilled in the art to utilize methods and apparatuses in various embodiments and with various modifications as are suited to the particular use contemplated. In accordance with the provisions of the patent statutes, the principles and modes of operation of this invention have been explained and illustrated in exemplary embodiments.

Claim 1:
An aspiration circuit for a fluidics system (<NUM>) for selectively controlling aspiration, comprising:
an aspiration line (<NUM>) operatively connected to a surgical instrument;
an aspiration pump to create an aspiration flow in the aspiration line;
an aspiration exhaust line (<NUM>) operatively connected to the aspiration pump on one end and to a waste receptacle (<NUM>) on an opposing end;
an aspiration vent line (<NUM>) connected at a first end to the aspiration line between the aspiration pump and the surgical instrument; and
a selectively variable vent valve (<NUM>) operatively connected to the aspiration vent line (<NUM>), wherein the variable vent valve (<NUM>) may be selectively moved to selectively change aspiration pressure within the aspiration line;
an irrigation line (<NUM>) operatively connected to the surgical instrument (<NUM>);
an irrigation pressure sensor (<NUM>, <NUM>) and an actuator, the irrigation pressure sensor being positioned to detect irrigation pressure in the irrigation line and the actuator being operatively connected to the vent valve (<NUM>);
characterised in that the irrigation pressure sensor (<NUM>, <NUM>) and the actuator are connected to a controller (<NUM>), and
wherein the controller (<NUM>) is operative to initiate the actuator to move the vent valve (<NUM>) in response to pressure detected by the irrigation pressure sensor (<NUM>, <NUM>).