Patent Description:
During ophthalmic surgery, an ophthalmic surgical apparatus is used to perform surgical procedures in a patient's eye. An ophthalmic surgical apparatus typically includes a handheld medical implement or tool, such as a handpiece with a tip and/or sleeve, and operating controls for regulating settings or functions of the apparatus and tool. Operation of the tool requires control of various operating settings or functions based on the type of tool used. Such apparatuses typically include a control module, power supply, an irrigation source, one or more aspiration pumps, as well as associated electronic hardware and software for operating a multifunction handheld surgical tool. The handpiece may include a needle or tip which is ultrasonically driven once placed with the incision to, for example, emulsify the lens of the eye. In various surgical procedures, these components work together in order to, for example, emulsify eye tissue, irrigate the eye with a saline solution, and aspirate the emulsified lens from the eye.

Intraocular pressure (IOP) is the fluid pressure inside the anterior chamber of the eye. In a normal eye, intraocular pressure may vary depending on the time of day, activities of the patient, fluid intake, medications, etc. Intraocular pressure may be measured as static (a specific value) or dynamic (a range of values). As can be appreciated, the static IOP and dynamic IOP of a patient's eye can fluctuate greatly during an ophthalmic surgery procedure. It is well known that the IOP in an anterior chamber of the eye is required to be controlled and maintained during such surgical procedures in order to avoid damage to the patient's eye. For the correct function of the eye and its structure (e.g. shape) and to preserve sharp and undamaged vision, it is very important to keep the IOP in normal, physiological values.

An exemplary type of ophthalmic surgery is phacoemulsification. Phacoemulsification includes making a corneal and/or scleral incision and the insertion of a phacoemulsification handpiece that includes a needle or tip that is ultrasonically driven to emulsify, or liquefy, the lens. A phacoemulsification system typically includes a handpiece coupled to an irrigation source and an aspiration pump. The handpiece includes a distal tip that emits ultrasonic energy to emulsify a crystalline lens within the patient's eye. The handpiece includes one or more irrigation ports proximal to the distal tip and coupled to the irrigation source via an irrigation input line. The handpiece further includes an aspiration port at the distal tip that is coupled to the aspiration pump via an aspiration output line. Concomitantly with the emulsification, fluid from the irrigation source (which may be a bottle or bag of saline solution that is elevated above the patient's eye, to establish positive pressure by gravity, and/or with external pressure source) is irrigated into the eye via the irrigation line and the irrigation port(s). This fluid is directed to the crystalline lens in the patient's eye in order to maintain the anterior chamber and capsular bag and replenish the fluid aspirated away with the emulsified crystalline lens material. The irrigation fluid in the patient's eye and the crystalline lens material is aspirated or removed from the eye by the aspiration pump and line via the aspiration port.

Similarly, cataract surgery is a complex procedure performed by highly skilled surgeons using extremely complex and expensive equipment. The surgeon undergoes years of training to perfect their technique while using only a fraction of the system's capabilities and features. For example, cataract tissue, which may be denser, may be removed by aspiration. When the material has been emulsified or softened to the point where aspiration is sufficient to remove the material an occlusion break occurs. It is well known that excessive energy application after an occlusion break occurs, known as a post occlusion surge, could potentially damage the tissue. In practice, the surgeon may anticipate this occurrence and discontinue ultrasonic power to prevent any damage to the eye. If the occlusion break occurs faster than the surgeon can discontinue power, the surgeon may apply more power than needed. Studies have shown that the human reaction time is approximately <NUM> milliseconds (ms). That means the patient may be subjected to an additional <NUM> or more of ultrasonic energy every occlusion break.

For example, during segment removal, the surgeon may confront a multitude of decisions as he/she attempts to balance the inflow and outflow of fluid in the eye while trying to control the movement of material with the handpiece and deciding when to apply ultrasonic power. Additionally, lens material may create a blockage at the tip preventing fluid from being evacuated. This blockage can result in post-occlusion surge and lead to eye trauma. When faced with a potential post occlusion surge situation, the surgeon has to decide whether to preempt the surge by clearing the occlusion by applying power to knock the piece off the tip and having to reacquire the piece or discontinue the procedure by gradually (or quickly) releasing the foot pedal to change the pump speed and/or vacuum. Depending on the density of the material, length of occlusion, maximum aspiration rate, maximum vacuum and a wide variety of other factors, the occlusion may clear before the surgeon can take action. A disadvantage in releasing the footpedal is the fact that cataract lens material in the aspirating phacoemulsification handpiece may flow back into the eye chamber leading to a longer, less efficient cataract extraction.

Techniques to overcome post inclusion surge have been developed that include smaller or specialized tips that allow fluid to enter through a secondary port to allow continuous fluid flow. Alternatively, other techniques include modifying predefined vacuum or aspiration settings, adjusting vacuum manually during the procedure or automatically "on-the-fly", and releasing the foot pedal to discontinue aspiration. These techniques have had varying levels of success.

<CIT> discloses a method and apparatus for controlling particle movement relative to a phacoemulsification needle tip. The design monitors actual vacuum present and calculates a pulse shape amplitude waveform proportional to the amount of measured vacuum. An increase in vacuum indicates that the handpiece/needle is becoming occluded by a large particle. The design determines whether additional power is required to bump or move a large particle away from the needle tip. The design employs a control loop that senses and continuously monitors vacuum. The design dynamically varies the amount of ultrasonic energy delivered to the surgical area in response to the observed actual vacuum, and actively varies the amount of power delivered to the surgical area based on the size of the particle and the resultant vacuum realized. <CIT> discloses an ultrasonic surgery apparatus which includes an ultrasonic chip, a vibration inducing unit which induces ultrasonic vibration to the ultrasonic chip, an aspiration unit which aspirates tissue emulsified by vibration of the ultrasonic chip, a detection unit which detects a clogging condition of the ultrasonic chip, a footswitch, having a pedal, for emitting an output signal which is based on a depression amount or a depression position of the pedal, and a control unit which controls at least one of ultrasonic power and a pulse-duty ratio of the ultrasonic vibration based on the output signal from the footswitch and a detection result obtained by the detection unit.

Thus, there exists a need for a simplified cataract extraction system where surgeons of many skill levels could safely and efficiently remove cataract lenses with a minimal amount of effort using a system that automates high portion the lens extraction procedure.

The present invention provides a system for managing occlusions during phacoemulsification surgery as recited in claim <NUM>. Optional features are recited in the dependent claims. The present invention provides for ones of the irrigation inflow (which determines intraocular pressure), aspiration (speed in which the pump is pulling fluid from the eye), vacuum (which quantifies the quality of the occlusion) and power (which breaks up the particle or creates separation from the phaco tip) to be combined into a synergistic controlled system where lens material is drawn to the tip, aspirated and removed from the eye with limited user interaction. For example, such a system may be activated when a user simply positions the handpiece and depresses the foot pedal, thus activating the process.

The organization and manner of the structure and function of the disclosure, together with the further objects and advantages thereof, may be understood by reference to the following description taken in connection with the accompanying drawings, and in which:.

The following description and the drawings illustrate specific embodiments sufficiently to enable those skilled in the art to practice the described system and method. Other embodiments may incorporate structural, logical, process and other changes. Examples merely typify possible variations. Individual components and functions are generally optional unless explicitly required, and the sequence of operations may vary. Portions and features of some embodiments may be included in or substituted for those of others.

<FIG> and <FIG> illustrate an exemplary phacoemulsification/diathermy/vitrectomy system <NUM>. As illustrated, the system <NUM> includes, for example, a handpiece or wand <NUM>, an irrigation source <NUM>, an aspiration source <NUM>, an optional pressure supply <NUM>, and a control module <NUM>. In illustrative embodiments, fluid is controllably directed through the system <NUM> in order to irrigate a patient's eye, illustrated representatively at <NUM>, during an ocular surgical procedure. Various embodiments of the handpiece <NUM>, irrigation source <NUM>, aspiration source <NUM>, optional pressure supply <NUM> and control module <NUM> are well known in the art and are embodied in this disclosure.

As illustrated in <FIG> and <FIG>, the irrigation source <NUM> is configured to supply a predetermined amount of fluid to the handpiece <NUM> for use during a surgical operation. Such fluid is supplied in order to, for example, stabilize or maintain a certain Intraocular Pressure (IOP) in the anterior chamber of the eye during surgery, as well as provide means for fluidly transporting any particles (e.g. lens particulates that are created during emulsification) out of the eye. Various aspects (e.g. the flow rate, pressure) of fluid flow into and out of the anterior chamber of the eye will typically affect the operations of the surgical procedure.

In illustrative embodiments, fluid may flow from the irrigation source <NUM> to the handpiece <NUM> via an irrigation line <NUM>. The irrigation source <NUM> may be any type of irrigation source <NUM> that can create and control a constant fluid flow. In illustrative embodiments, the irrigation source is elevated to a predetermined height via a support <NUM> coupled with an extension arm <NUM>. In illustrative embodiments, the irrigation source <NUM> may be configured to be an elevated drip bag <NUM> that supplies a steady state of fluid <NUM> to the irrigation line <NUM>. Irrigation line <NUM> is coupled with proximal end <NUM> of handpiece <NUM>. The pressure supply <NUM> may be coupled to the irrigation source <NUM> in order to maintain a constant pressure in the irrigation source <NUM> as fluid exits the irrigation source <NUM>, as is known in the industry. Other embodiments of a uniform irrigation source are well known in the art.

During the surgical procedure, it is typically necessary to remove or aspirate fluid and other material from the eye. Accordingly, fluid may be aspirated from the patient's eye, illustrated representatively at <NUM>, via the handpiece <NUM> to flow through an aspiration line <NUM> to the aspiration source <NUM>. Aspiration line <NUM> is coupled with proximal end <NUM> of handpiece <NUM>. The aspiration source <NUM> may be any type of aspiration source <NUM> that aspirates fluid and material from the eye. In illustrative embodiments, the aspiration source <NUM> may be configured to be a flow-based pump <NUM> (such as a peristaltic pump) or a vacuum-based pump (such as a Venturi pump) that are well known in the art. The aspiration source <NUM> may create a vacuum system to pump fluid and/or material out of the eye via the aspiration line <NUM>. A sensor system <NUM> may be present to measure the pressure that the vacuum creates. Other embodiments of an aspiration source are well known in the art.

The irrigation port <NUM> is fluidly coupled to the irrigation line <NUM> to receive fluid flow from the irrigation source <NUM>, and the aspiration port <NUM> is fluidly coupled to the aspiration line <NUM> to receive fluid and/or material flow from the eye. The pressure in the aspiration line may be measured by the sensor system <NUM>. The handpiece <NUM> and the tip <NUM> may further emit ultrasonic energy into the patient's eye, for instance, to emulsify or break apart the crystalline lens within the patient's eye. Such emulsification may be accomplished by any known methods in the industry, such as, for example, a vibrating unit (not shown) that is configured to ultrasonically vibrate and/or cut the lens, as is known in the art. Other forms of emulsification, such as a laser, are well known in the art. Concomitantly with the emulsification, fluid from the irrigation source <NUM> is irrigated into the eye via the irrigation line <NUM> and the irrigation port <NUM>. During and after such emulsification, the irrigation fluid and emulsified crystalline lens material are aspirated from the eye by the aspiration source <NUM> via the aspiration port <NUM> and the aspiration line <NUM>. Other medical techniques for removing a crystalline lens also typically include irrigating the eye and aspirating lens parts and other liquids. Additionally, other procedures may include irrigating the eye and aspirating the irrigating fluid within concomitant destruction, alternation or removal of the lens.

The aspiration source <NUM> is configured to aspirate or remove fluid and other materials from the eye in a steady, uniform flow rate. Various means for steady, uniform aspiration are well known in the art. In illustrative embodiments, the aspiration source <NUM> may be a Venturi pump, a peristaltic pump, or a combined Venturi and peristaltic pump. In illustrative embodiments, and as shown in <FIG>, a peristaltic pump <NUM> may be configured to include a rotating pump head <NUM> having rollers <NUM>. The aspiration line <NUM> is configured to engage with the rotating pump head <NUM> as it rotates about an axis. As the pump head <NUM> rotates the rollers <NUM> press against the aspiration line <NUM> causing fluid to flow within the aspiration line <NUM> in a direction of the movement for the rollers <NUM>. Accordingly, the pump <NUM> directly controls the volume or rate of fluid flow, and the rate of fluid flow can be easily adjusted by adjusting the rotational speed of the pump head <NUM>. Other means of uniformly controlling fluid flow in an aspiration source <NUM> are well known in the art. When the aspiration source <NUM> includes a combined Venturi and peristaltic pump, the aspiration source <NUM> may be controlled to automatically switch between the two types of pumps or user controlled to switch between the two types of pumps.

In illustrative embodiments, the control module <NUM> is configured to monitor and control various components of the system <NUM>. For instance, the control module <NUM> may monitor, control, and provide power to the pressure supply <NUM>, the aspiration source <NUM>, and/or the handpiece <NUM>. The control module <NUM> may be in a variety of forms as known in the art. In illustrative embodiments, the control module <NUM> may include a microprocessor computer <NUM>, a keyboard <NUM>, and a display or screen <NUM>, as illustrated in <FIG> and <FIG>. The microprocessor computer <NUM> may be operably connected to and control the various other elements of the system, while the keyboard <NUM> and display <NUM> permit a user to interact with and control the system components as well. In an embodiment a virtual keyboard on display <NUM> may be used instead of keyboard <NUM>. A system bus <NUM> may be further provided to enable the various elements to be operable in communication with each other. The control module <NUM> may be powered by an energy source. One skilled in the art would appreciate that the energy source may be a power source - such as a 110v plug - or conventional commercial power sources.

The screen <NUM> may display various measurements, criteria or settings of the system <NUM> - such as the type of procedure, the phase of the procedure and duration of the phase, various parameters such as vacuum, flow rate, power, and values that may be input by the user, such as bottle height, sleeve size, tube length (irrigation and aspiration), tip size, vacuum rate. The screen <NUM> may be in the form of a graphical user interface (GUI) <NUM> associated with the control module <NUM> and utilizing a touchscreen interface, for example. The GUI <NUM> may allow a user to monitor the characteristics of the system <NUM> or select settings or criteria for various components of the system. For instance, the GUI <NUM> may permit a user to select or alter the maximum pressure being supplied by the pressure supply <NUM> to the irrigation source <NUM> via line <NUM>. The user may further control the operation of the phase of the procedure, the units of measurement used by the system <NUM>, or the height of the irrigation source <NUM>, as discussed below. The GUI <NUM> may further allow for the calibration and priming of the pressure in the irrigation source <NUM>.

In illustrative embodiments, the system <NUM> may include a sensor system <NUM> configured in a variety of ways or located in various locations. For example, the sensor system <NUM> may include at least a first sensor or strain gauge <NUM> located along the irrigation line <NUM> and a second sensor or strain gauge <NUM> located along the aspiration line <NUM>, as illustrated in <FIG>. Other locations for the sensors <NUM> and <NUM> are envisioned anywhere in the system <NUM>, e.g. on the handpiece <NUM>, and may be configured to determine a variety of variables that may be used to determine pressure measurements in the aspiration line, as discussed below. This information may be relayed from the sensor system <NUM> to the control module <NUM> to be used in the determination of the presence of an occlusion break. The sensor system <NUM> may also include sensors to detect other aspects of the components used in the system, e.g. type of pump used, type of sleeve used, gauge of needle tip (size), etc..

Those of skill in the art will recognize that any step of a method described in connection with an embodiment may be interchanged with another step without departing from the scope of the disclosure. Those of skill in the art would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention as defined by the claims.

The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed using a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein.

Any options available for a particular medical device system may be employed with the present invention. For example, with a phacoemulsification system the available settings may include, but are not limited to, irrigation, aspiration, vacuum level, flow rate, pump type (flow based and/or vacuum based), pump speed, ultrasonic power (type and duration, e.g. burst, pulse, duty cycle, etc.), irrigation source height adjustment, linear control of settings, proportional control of settings, panel control of settings, and type (or "shape") of response.

The present invention may also monitor and control fluid inflow and outflow to generate a fluid balance within the eye that may bring particles and segments to the handpiece tip, detect occlusion by sensing vacuum, and discretely apply power to liquefy and aspirate material in a smooth, gentle manner that provides excellent holdability and followability. For example, extended periods of vacuum above a predetermined pressure threshold may indicate that the power being applied at the point of surgery is not effective or that the target lens material is denser than anticipated. In either of these situations, additional power or time may be needed. The present invention provides for increasing the amount of power after a specified duration and further provides subsequent power increases based on a time specification.

A surgeon may control the system of the present invention using, for example, a foot pedal associated with the system. There may be at least four "zones" in the foot pedal denoted by number for ease of explanation, with each zone being assigned a particular task and/or function. For example, a first zone may start at <NUM>, representing no activity, a second zone may be "zone <NUM>" and may engage and/or control irrigation functionality, "zone <NUM>" may engage and/or control aspiration functionality, and "zone <NUM>" may engage and/or control other aspects of the handpiece, such as the cutting tip. For example, when manually operating the foot pedal, a surgeon may press the pedal through positions <NUM> and <NUM> to control the fluidics of the system. Similarly, a surgeon my press the pedal to position <NUM> to apply ultrasonic power and then revert back to position <NUM> to discontinue power, for example.

A user is provided with control when power is to be activated and engage an algorithm to determine how much power gets applied while the user is in, for example, foot pedal position <NUM>. By way of non-limiting example only, if no occlusion exists, zero to a minimal amount of power may be applied. If, for example, an occlusion exists, power may applied in two levels. A first power level may be provided to assist in acquiring the particle and may be provided for a defined initial period, such as, for example, <NUM> seconds. As the vacuum level increases, a second power level may be obtained and, for example, the system may discontinue the use of power given the expiration of the initial period and wait for a second designated period. This is to determine whether aspiration and vacuum alone is sufficient to remove the tissue. If the first period of time elapses and the occlusion remains, primary power may be applied to help emulsify the material. Additional power may be applied over a specific time period until the blockage is cleared. Once the blockage is cleared, power may be immediately reduced to the minimal power level. The user may remain in position <NUM> throughout this entire process while the amount or amplitude of power applied is determined automatically through the algorithm.

During a phacoemulsification procedure, the user may engage the foot pedal to initiate irrigation (foot pedal position <NUM>) and activate aspiration (foot pedal position <NUM>). Cataract lens material may be drawn to the tip and vacuum may be generated. The user may activate ultrasonic power (foot pedal position <NUM>), for example, to aid in embedding the tip to acquire the material. Typically, the user will transition back into foot pedal position <NUM> for maintaining a hold over the material and then use a second instrument such as, for example, a chopper, to segment the material into smaller, more manageable pieces. This process of moving from foot pedal position <NUM>, to foot pedal position <NUM>, and back to foot pedal position <NUM>, may be repeated until the user is satisfied with the quantity and size(s) of the material to be removed.

A user may engage foot pedal position <NUM> to attract a segment of loose tissue and attempt to remove it by aspiration alone. If the aspiration is not sufficient to remove the tissue, a complete blockage of the tip may occur creating at least a partial occlusion. The user may then engage foot pedal position <NUM> to activate ultrasonic power to emulsify the material to aid in aspiration. When, for example, the blockage has cleared or when the user determines the material has been emulsified satisfactorily, the user may revert back to foot pedal position <NUM>, discontinuing ultrasonic power. This process is repeated until all lens material has been removed.

Furthermore, upon occlusion detection and applying an algorithm, such as described herein, to modulate the aspiration rates, increase and decrease the peristaltic pump speed to pulsate the pump, causing shearing forces on the particle. Ideally, these shearing forces will be sufficient to aspirate the tissue without the application of ultrasonic power. Power may be applied sparingly and ideally, within a duty cycle that may maximize the reduction of thermal issues as power may only be applied if and when an occlusion is detected. If, for example, aspiration and vacuum are not sufficient to remove a blockage, ultrasonic power may be applied. Power is applied via an automated algorithm (described herein) that detects the quality and length of the occlusion. In the proposed solution, ultrasonic power is applied through a surgical console and handpiece combination which may allow for the application of power via a longitudinal (forwards and backwards) motion and/or via an elliptical pattern in a two-dimensional plane.

Power control decisions may be based on monitoring vacuum level(s) after a user activates power via, for example, foot pedal position <NUM>. By way of non-limiting example only, during manual nucleus removal, a surgeon may position the phacoemulsification needle in proximity to the tissue to be removed and draw it towards the tip of the needle. Once the portion of tissue is at least proximate to the needle tip, the surgeon may apply a small amount of power to embed the tip into the tissue to aid in segmenting the lens material. Using a combination of irrigation and aspiration may allow for pieces of tissue to brought to the needle tip to be removed. If a blockage occurs, the algorithm may determine when and how much power is to be applied.

If a vacuum rises above a predetermined threshold, for example, "threshold <NUM>", an initial amount of power may be applied to help embed the tip into the target material. This may allow the surgeon to control the piece of material and may aid in the attempt to segment the target material. For example, a threshold may set based on a percentage of the maximum vacuum. For example, if the threshold is <NUM>% and the maximum vacuum is preset to <NUM> mmHg, then the pressure threshold is <NUM> mmHg. Power may be applied based on a percentage of the maximum allowable power and may be incremented over time. For example, if the maximum allowable power is <NUM>, the initial power applied is <NUM>% of that maximum or <NUM>. Power may be immediate or delayed based on user preference.

As discussed above, the present invention provides for increasing the amount of power after a specified duration and further provides subsequent power increases based on a time specification. In the example cited above, a power of <NUM> would be applied when the actual vacuum exceeds <NUM> mmHg. By way of further example, if the vacuum remains above the threshold after two seconds (user adjustable) additional power may applied. Power is expressed using the formula x + ax, wherein x represents the previous power being applied and ax represents a percentage of the x power to be added to the then applied power. The formula is also expressed as: f(x) = x + ax, where f(x) is a function of x and is the new calculated power; where "a" is any factor or decimal constant number less than <NUM>, e.g. <NUM>, <NUM> or any other number less than <NUM>. For example, power is increased in a step-wise fashion, such as in increments of <NUM>% of applied power, such that the next incremental power level to apply would be <NUM>, then <NUM>, <NUM>, <NUM> and then <NUM> - each occurring after a two second period of power application. In this example, it would take ten seconds of occlusion to reach the full maximum power of <NUM>.

As would be understood by those skilled in the art, power may be discontinued after the vacuum level falls below the vacuum threshold. As an occlusion clears, the system may increase aspiration and attract other particles and the process may be repeated.

Claim 1:
A system (<NUM>) for managing occlusions during phacoemulsification surgery, the system comprising:
a surgical console (<NUM>) having at least one system bus communicatively connected to at least one computing processor (<NUM>) capable of accessing at least one computing memory associated with the at least one computing processor (<NUM>);
at least one vacuum source (<NUM>) associated with the surgical console for providing a vacuum pressure;
at least one energy source associated with the surgical console for providing ultrasonic energy;
an aspiration line (<NUM>) for providing the vacuum pressure to a surgical handpiece (<NUM>); and
a sensor system (<NUM>) for measuring the vacuum pressure in the aspiration line (<NUM>);
characterized in that the power of the ultrasonic energy is configured to be increased once and in subsequent step-wise increases using the formula f(x) = x + ax, wherein each increase occurs after a user-adjustable time period when the sensor system identifies that an absolute value of the vacuum pressure in the aspiration line (<NUM>) exceeds a predetermined pressure threshold for a specified duration, wherein each subsequent step-wise increase is applied if the vacuum pressure in the aspiration line (<NUM>) remains above the predetermined pressure threshold;
wherein f(x) is a new power of a step of the ultrasonic energy, x equals a power of the previous step of the ultrasonic energy, and a is a constant decimal less than <NUM>.