Abstract:
A phacoemulsification system includes a platform controlling the phacoemulsification process and a handpiece attached to the platform and used by a surgeon to perform an operation. The handpiece includes a hollow phaco needle with a flexible sleeve around the needle and provides an infusion fluid sourced at the platform into the eye. The sleeve, which may be disposable, is provided with a sensor device configured to sense the instantaneous fluid pressure in the eye during the operation and send this information to the platform. This information is used by the process to control the pressure of the infusion fluid to insure that the eye is not injured and to otherwise protect the eye during the operation.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 62/166,821 filed May 27, 2015 and incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Modern cataract surgery typically utilizes an integrated mechanical and fluidics system supporting a surgeon hand-piece whose front-end houses a hollow needle surrounded by a soft sleeve typically of a silicone material. The hollow needle provides (usually) ultrasonic vibrations used to emulsify the cataractous lens. Infusion fluid (physiologic saline) enters the eye and is used as a medium for transport of the fragmented lens material to the tip of the hollow ultrasound needle. This infusion fluid runs down the surgeon&#39;s hand-piece between the ultrasonic needle (measuring about 0.9 mm in diameter) and the surrounding sleeve. This infusion fluid is delivered through distal ports (typically two, positioned 180 degrees from one another) on the sleeve into the anterior chamber of the eye filling the space, maintaining the vault and thus preventing collapse of the cornea or iris against the phaco needle/sleeve complex during the emulsification process. The infusion fluid and the lens material are aspirated from the eye through the hollow needle and into a waste receptacle on the system platform. 
         [0003]    Balancing fluid infusion into the eye against its exit from the eye via aspiration through the hollow needle and passive leakage around the surgical entry wound has long been a concern of the industry. As a general term the performance of fluid infusion into the eye is referred to as fluidics. 
         [0004]    Recently the industry—both surgeons as end users and manufacturers—have come to realize that both the safety and efficacy of phacoemulsification surgery is associated with previously unknown or under-appreciated risks, as demonstrated by a number of peer reviewed publications. These findings include cataractous lens material accumulating in the posterior portion of the eye as well as trauma to the iris. Both of these phenomena may cause inflammation in the post-operative period and, secondarily, diminish visual potential.
       1. Novak, J, Retrolenticular Lens Fragments: a problem of phacoemulsification; J. Ev. Purkyne Praha: 1999 September; 55(5): 268-273   2. Ang A, Menezo i Rallo V, Shepstone L, Burton R L. Retrocapsular lens fragments after uneventful phacoemulsification cataract surgery, J Cataract Refract Surg 2004; 30:849-853   3. Koplin R S, Ritterband D C, Dodick J M, Donnenfeld E D, Schafer, M: (in press) Untoward events associated with aberrant fluid infusion during cataract surgery: a laboratory study with corroborative clinical observations.   4. Chang D F, Campbell J R. Intraoperative floppy iris syndrome associated with tamsulosin. J Cataract Refract Surg. 2005:31:664-73.   5. Oh J H, Chuck R S, Do J R, Park C Y. Vitreous Hyper-Reflective Dots in Optical Coherence Tomography and Cystoid Macular Edema after Uneventful Phacoemulsification Surgery Published: PLOS ONE 2014; 9:1-9       
 
         [0010]    These risks are directly related to inconsistent regulation of infusion fluid entering the eye, admixing with lens material, and adversely impacting intraocular anatomy. Importantly, the volume of fluid delivered into the eye at any given time also affects the control of the procedure. The result of unregulated fluid infusion is variable and unpredictable intraocular pressure that relates to constant fluctuations in anterior chamber depth and increased turbulence and inertial forces—facilitating a higher Reynolds Number. This process compromises the ability to maintain lens material at the phaco tip for efficient emulsification and promoting untoward lens transport to the back of the eye and aggravation the iris causing disquieting and damaging flapping movements of the iris. (Often called Floppy Iris Syndrome.) These phenomena affect both the efficiency and safety of the operation. 
         [0011]    Fluid infusion into the eye during phacoemulsification surgery is historically provided by gravity feed. Typically, a bottle of a physiologic saline solution is positioned at approximately 60-120 cm above the eye and tubing from the bottle is connected through a surgical hand-piece to the needle/sleeve complex where fluid leaving the eye—through aspiration defined by a linear process (surgeon presses the foot-pedal to increase aspiration flow rate of fluid) and leakage from various wounds in the eye will commensurately dictate the rate of fluid infusion. The average the rate of infusion into an eye at surgery is about 30 cc/minute, but can vary widely depending on the aspiration rate, leakage from surgical wounds, and the size of the eye as well as certain preset platform functions, including bottle height. 
         [0012]    The negative characteristics of a gravity feed fluid infusion system is the sudden impact on the anatomy as unrestrained fluid enters the eye as the surgeon engages a position on the system foot pedal to initiate infusion. Also to contend with are fluid surges when vacuum is relieved at the needle tip one a piece of cataractous lens (at first blocking aspiration into the hollow needle) is suddenly aspirated into the hollow needle causing vacuum to fall abruptly. Depending on the size of the eye and the stability of the lens to be emulsified infusion fluid entering the eye in unregulated fashion may cause an alarming deepening of the anterior chamber, forcing the lens posteriorly, causing the patient pain, and making surgery more risky. In other cases, where the eye is small, fluid infusion may be forced into constrained anatomical compartments where this crowding may cause disconcerting movements of the iris out of the surgical wounds. Secondary to this blockage the anterior chamber may become abruptly shallower in the presence of an unrestricted inflow of the fluid, requiring the surgeon to remove the instruments perform emergency measures to relieve the high pressure disrupting the procedure. 
         [0013]    In order to mitigate the damaging effects of unregulated fluid infusion into the eye—and attempting to balance this with aspiration and leakage—the surgeon is required to empirically decrease or increase preset platform values for aspiration and/or place the infusion bottle at varying heights (lower the bottle to attempt to decrease the volume of infusion entering the eye or raise the bottle in order to increase infusion). Because of these concerns there is a growing acknowledgement that a form of active controls is required maintain control of of fluid infusion at phaco surgery. 
         [0014]    Active fluidics, that is the process of controlling fluid infusion utilizing control mechanisms responsive to changes in intraocular pressure, is essentially a sensor regulated process that is designed to respond to monitored changes in eye pressure. However, a major failing of existing active fluidic designs is that there is a lag time between a call for a response to changes in fluid pressure within the eye because the sensor is positioned down the line (responding via fluid pressure within a flexible tubing transporting fluid into the eye and installed within the tubing or at its terminus in the platform several feet away). The delay significantly impacts the system&#39;s ability to engage the mechanism (peristaltic pump, gas, Venturi) facilitating the response to adequately provide and accurate amount of fluid flow into the eye. Because of this lag-time the benefits to patients and surgeons provided by the present state of of active fluidics is significantly degraded. So, in spite of the active fluidics presently installed in certain platforms, the surgeon still experiences extreme surges of infusion impacting the contents of the eye, resulting in turbulence and visibly driving cataractous lens particles about the eye—in both anterior and posterior segments. 
         [0015]    Intraocular pressure measurements (fluid eye pressure measurements) have been a staple for understanding the health of the eye for many years. Elevated intraocular fluid pressure (usually measured in mm Hg) was not routinely assessed until the latter part of the 19th century when von Graefe developed the first instrument for measuring intraocular pressure in (1865). 
         [0016]    Intraocular pressure is typically measured to aid in the monitoring and treatment of a disorder called glaucoma, where an untoward elevation in the eye pressure may result in damage to the optic nerve and impact vision. Investigators have long imagined implanting permanent sensors in eye tissues to provide real-time monitoring of eye pressure and allowing more timely treatment of a patient&#39;s glaucoma. 
       SUMMARY OF THE INVENTION 
       [0017]    It is clear that in order to provide a real time monitor for an active fluidics system a sensor must be within the anterior chamber and wirelessly disposed where it can provide real time information to a (trans)receiver on the surgical platform a few feet away. Only in this way can the monitor maintain a timely response for adequate control of fluid infusion into the eye. 
         [0018]    The present invention is not fixed within the eye (not implanted), is not attached or adherent to any eye tissues; and is not directed to measure eye pressure for disease prevention or treatment. Infusion fluid (typically a physiologic saline solution) is provided directly from a source in the surgical platform (via a pump: peristaltic, or Venturi, or gas) through a flexible tubing into the phaco needle/sleeve complex incorporated within a hand-piece within the eye during phaco surgery. There is a measurable fluid pressure within the eye (specifically for our purposes a measure within the anterior chamber) that dictates the environmental stability of the anterior and posterior chambers. In order to produce a beneficial homeostatic fluid environment during phaco surgery, the intraocular pressure must be regulated thus producing a predictable balance of fluid infusion entering the eye as well as exiting the eye. The basis for this balancing process is the pressure within the eye at any given instant. This pressure must be measured in real-time for the regulation to be effective. In the present invention, this pressure is measured and communicated (preferably wirelessly) to a receiving device within the phaco platform for real-time control of the servo mechanism controlling fluid inflow to the eye. 
         [0019]    Thus, the invention is designed to provide a temporary monitoring of eye pressure during the phacoemulsification surgery, with a sensor being placed on or within the disposable silicone sleeve surrounding the phaco needle. The sensor provides a relative or absolute pressure reading of the intraocular pressure during surgery, in the form of a continuous data stream that can be monitored at the terminus of the fluid line from the eye at the system platform. This data can be utilized by the surgeon&#39;s to preset controls at the servo pump or gas infusion device within the platform in order to maintain a constant pressure environment within the eye during surgery. This information from the sensor within the eye and on or in the sleeve is preferably transmitted to a relay or repeater near the patient&#39;s eye and from there to a transceiver positioned within the surgical platform. The surgical platform houses the mechanism for servicing a call for infusion using the differential between the platform preset target pressure (as determined by the surgeon) and the actual intraocular pressure as determined by the sensor situated in or on the sleeve. The mechanism is meant to call for fluid infusion for not) when the data stream suggests a there is a differential in the preset and actual intraocular pressure. Thus a control loop is provided to operate as a real-time active fluidics mechanism as if the fluid environment within the eye, the aspiration line, and the infusion line were continuous and in a state of equilibrium. 
         [0020]    The sensor, attached to the sleeve can be rendered inoperable once the surgical instruments—along with the sensor—are removed from the eye at the conclusion of the operation. 
         [0021]    In one embodiment, the sensor is implemented as an RFID disposed on a chip using, for example, a silicon-on-insulator process. This configuration is advantageous because it provides a practical system architecture with low power and size, characteristics that are advantageous for the present invention. 
         [0022]    One embodiment of the present invention includes a micro-, or nano sensor powered sensing and amplification device that is provided as a package for placement outside or within the wall of a silicone sleeve specific to the infusion process for phacoemulsification surgery. 
         [0023]    In one embodiment of the present invention, the sensor is disposed on a second instrument that is temporarily inserted into the eye during the phacoemulsification procedure and then is removed, and, optionally disposed of at the conclusion of surgery. 
         [0024]    Another embodiment of the present invention provides for the temporary placement of the sensor through the corneal tissue to enter the eye at minimum where only the sensor is exposed to the intraocular environment. Another embodiment of the present invention provides for a system wherein the flow of infusion fluid is used as a source of energy inside the eye. 
         [0025]    Another embodiment of the present invention includes a power supply configured as a radio frequency receiver and powered externally. 
         [0026]    Another embodiment of the present invention provides an antenna configured as a wireless source of data transmission 
         [0027]    Another embodiment of the present invention provides the envisioned system as having a storage unit as a source of reliable power. 
         [0028]    Another embodiment of the present invention provides a capacitor as is utilized as a power storage unit. 
         [0029]    Another embodiment of the present invention utilizes a battery configured as the power storage unit. 
         [0030]    Another embodiment of the present invention provides for such a system where the sensor package continuously monitors and transmits data from the eye to the external transceiver and then to the platform console for instantaneous response by a servo mechanism to control infusion fluid. 
         [0031]    Another embodiment of the present invention provides for such a system where the sensor package continuously monitors and transmits data from the eye to the external transceiver and then to the platform console for real-time response by a servo mechanism to control infusion fluid as well to a responsive transceiver coordinating the aspiration process where a fine balance between the two can further maintain intraocular pressure. 
         [0032]    Furthermore, the sensor-sleeve complex is designed for temporary use and once removed from the eye can be disposed of, or in certain cases, re-sterilized for multiple use. 
         [0033]    Another embodiment of the present invention the pressure sensor is a micro-electro-mechanical (MEMS) pressure sensor. 
         [0034]    Another embodiment of the present invention provides that an RFID chip with the sensor built into the chip and an external source querying the RFID chip also provides the energy for the sensor. 
         [0035]    The features and advantages described herein are not all-inclusive and, in particular, many added features and advantage will be apparent to one of ordinary skilled in the art and conversant with the drawings, specifications, and claims. Moreover it should be noted that the language used in the specification has been purposefully selected for readability and instructional purposes, and not to limit the scope of the inventive subject. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]      FIG. 1  shows a prior art phacoemulsification system with gravity fed infusion; 
           [0037]      FIG. 2  shows a prior art phacoemulsification system with a liquid infusion pump; 
           [0038]      FIG. 3  shows a block diagram a phacoemulsification system a liquid infusion pump and a sensor constructed in accordance with this invention; 
           [0039]      FIG. 4  shows an alternate embodiment of the system of  FIG. 3  using an air pump for pressurizing the infusion fluid; 
           [0040]      FIG. 5  shows a circuit diagram for a sensor device used in the phacoemulsification systems of  FIG. 3 or 3A ; 
           [0041]      FIG. 6  shows a circuit diagram of an alternate embodiment for the sensor device. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0042]    Referring to  FIG. 1 , a first conventional phacoemulsification system  10  includes a platform  12  is associated with a handpiece  14 . The handpiece  14  includes a hollow needle  16  that is connected to the platform  12  and is vibrated at known ultrasonic frequencies so that when its tip  18  is inserted into proximal to a cataractous lens within the eye (not shown), it can emulsify the lens contained therein. A bottle  20  provides through a tube  22  an infusion fluid that flows around the needle  16  through a sleeve  24  and exits, as at  26  adjacent to the tip  18 . The pressure of the fluid at the exit points  26  can be controlled in this system  10  only by raising or lowering the bottle  20 . 
         [0043]    A somewhat more sophisticated system  30  is shown in  FIG. 2 . System  30  includes a platform  32  that is connected to handpiece  34  also having a hollow needle  36  surrounded by a sleeve  38  and having an emulsification tip  40 . Infusion fluid is provided from the platform  32  to the sleeve  38  and this fluid is then ejected near tip  40 , as at  42 . In this system, the infusion fluid is provided by a bag  44  to a pump  46 . The pump  46  then forces the fluid through tube  48  to the sleeve  38 . The platform  32  also includes a sensor  50  that senses the fluid pressure through the line (tubing) as it leaves the pump  46 . The operation of the pump  46  is controlled by a control servo  52  which receives an input from the surgeon indicative of the desired fluid pressure and another input from the sensor  50 . Ideally, this feedback-type control scheme should be able to control the pressure of the fluid as it is ejected at  42 . However, in practice it has been found that this scheme is less than ideal because there has a substantial and measurable lag between the time that surgeon sets a desired pressure demand as an input for the servo and the time the loop adjusts itself to the desired pressure. As a result, the pressure at the fluid exit points  52  can be either much higher or much lower than desired for a considerable time, leading to complications within the eye. 
         [0044]    A system  100  constructed in accordance with this invention is shown in  FIG. 3 . As shown in this Figure, the system  100  includes a platform  102  associated with a handpiece  104 . The handpiece includes a needle  106  terminating a tip  108  used for emulsification. A sleeve  110  surrounds the needle  106  and provides fluid near the tip  108  through exit ports  110 . The needle  106  is vibrated at ultrasonic frequencies by a conventional ultrasonic generator disposed in the platform  102  (not shown). The sleeve may be disposable. 
         [0045]    The infusion fluid originates from a bag  114  and is pushed by a pump  116  through fluid tube  118 . The pump  116  is controlled by a servo  120 . Importantly, a sensor device  122  is disposed adjacent to one of the exit ports along or in the sleeve  112 . The sensor device  122  is arranged to measure the instantaneous fluid pressure at that point. The pressure information from sensor device  122  is transmitted to an information relay (such as an RE transceiver or repeater)  124 . The relay  124  then transmits the pressure information to a receiver  126  in the platform  102 . The pressure information is then provided to a servo  120 . The platform  102  is also provided with a surgeon interface  128  that receives demand information from the surgeon. The interface  128  may include a dial or a digital keypad used by the surgeon to set a certain fluid pressure or request a pressure increase or decrease. The servo  120  then uses the pressure information and a demand signal from the interface  128  to control the operation of the pump  116 . Since the pressure information originates directly from the fluid exit port  112 , it is much more accurate or current then in the prior art and hence the system  130  operates much faster and more reliably. 
         [0046]    In one embodiment of the invention, instead of using relay  124 , the pressure information from the sensor device  122  is transmitted to the receiver  126  by a hard wire, an RF transmission, etc. 
         [0047]    Sensor device  122  is preferably a miniaturized IC chip that can be mounted at a location preferably near one of the exit ports  112 . For example, device  122  can be mounted on the inner or outer wail of sleeve  110 . The information relay or repeater  124  is disposed preferably outside the eye but near enough so that it can be within the transmitting range of device  122 . 
         [0048]    In the embodiment described above, the infusion fluid for the handpiece  104  is pressurized directly and controlled using a pump  116 , which may be, for example, a peristaltic pump. In an alternate embodiment, instead of using a direct pressurizing means, an air (or gas) pump may be used, as shown in  FIG. 3A . In this Figure, a pressurized vessel  140  holds an infusion fluid  142 . This fluid  142  is fed to the handpiece  104  as described in conjunction with  FIG. 3 . The vessel  140  is pressurized by an air pump  144  that is operated by a control signal from the servo  120 . 
         [0049]      FIG. 5  shows a block diagram of a first embodiment  120 A of the sensor device. It includes a power supply  150 , a sensor element  152 , a preamplifier and filter  154 , a mixer  156 , an impedance matching network  158  and an antenna  160 . 
         [0050]    The sensor element  152  is preferably a MEMS-type pressure sensor in communication with the infusion fluid within or exiting from the sleeve  110 . The sensor output is conditioned and amplified by preamplifier and filter  154  and fed to a mixer  156 . The mixer  156  further receives an RF signal from a local oscillator  162 . The resulting RE signal is fed to an impedance matching network  158  and output by antenna  160 . 
         [0051]    While the output signal from the antenna could be transmitted straight to the platform  102 , or it can be transmitted through a repeater  124  as discussed above. The RF output signal is received by an antenna  126 A incorporated into platform  102  and then fed to the receiver  126  and servo  120  as discussed above. 
         [0052]    The power supply  150  can be either a battery, a supercapacitor or other conventional static power source. Alternatively, power to the sensor device  122  can be provided by an active source. For example, in  FIG. 5  such as an inductor  170  is provided in an external excitation member  172 . Excitation member  172  is disposed outside the eye during surgery and is provided power from an external power source  174 . During surgery, the inductor  170  generates a magnetic field that in turn generates a current through internal inductor  176 . The inductor  176  with a capacitor  178  form an active power source  150 A for the sensor device shown in  FIG. 4 . 
         [0053]      FIG. 6  shows several other alternative embodiments. In this Figure sensor  120 C is a digital device as opposed to the analog device shown in  FIG. 4 . The sensor element  152  generates sensor data that, after processing by the amplifier and filter  154  is provide to an ADC  202 . The digital sensor data from the ADC is sent out either directly or fed to a microprocessor  204 . The microprocessor then generates corresponding digital output data that is fed to the impedance matching network  158  and then to antenna  160 . In one embodiment this output data is sent either directly to the receiver of the platform  102  either directly, or via repeater  124 . In this configuration, power for the sensor device  120 C is provided by battery  150 A. 
         [0054]    In another embodiment, RFID technology is used to query and power the sensor device  120 C. For this purpose, an external RFID transceiver  192  is provided that is positioned during surgery adjacent to the surgery site. The sensor device  120 C includes an RFID receiver and tank circuit  200  feeding a charging circuit  202 . When activated, the RFID transceiver sends a query to the RFID receiver  200  in the form of an RF signal. This RF signal is preferably continuous. 
         [0055]    The RFID receiver  200  receives the RF signal and uses its energy to power a charging circuit  202 . The charging circuit then generates power that is either used to energize the other elements of the device  120 C directly, or is used to charge battery  150 A. Then, in response to the query, the sensor element detects the respective fluid pressure and generates a corresponding output signal indicative of this instantaneous fluid pressure. In one embodiment, the output signal from the antenna  160  is transmitted to the platform  102  directly or via repeater  124 . In another embodiment, the RFID external transceiver  192  also acts as the repeater  124 . In this case, the antenna  160  is part of the RFID receiver  200  and the output signal is sensed by the transceiver  192  which then transmits it to the platform  102 . 
         [0056]    Numerous modifications may be made to this invention without departing from its scope as defined in the appended claims.