Ophthalmic fluidic system with eddy current pressure sensor

Abstract

To provide an improved system and method for monitoring fluid pressure in an ophthalmologic procedure.SOLUTION: An exemplary ophthalmic surgical system comprises a fluid flow path and a pressure sensor system for measuring pressure in the fluid flow path. The pressure sensor system comprises a conductive, movable diaphragm having a first side and a second side, the first side of the diaphragm facing the fluid flow path, and an eddy current position sensor positioned on the second side of the diaphragm without contacting the diaphragm. The eddy current position sensor comprises a position sensor coil activatable by high frequency alternating current and signal conditioning electronics capable of sensing inductance or impedance or resonant frequency variation in the position sensor coil as a gap between the diaphragm and the position sensor coil changes and of translating that variation into a displacement signal correlated to fluid pressure.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure is directed to systems and methods relating to ophthalmic surgery, and more particularly, to monitoring fluid pressure during ophthalmic surgery. [Background technology]

[0002] In ophthalmic surgical procedures, fluids are often aspirated from the eye during surgery. For example, in vitreous retinal surgery, devices may be used to aspirate vitreous material from the eye. As another example, in cataract surgery, devices may be used to fragment or emulsify the lens and aspirate the broken down or emulsified lens from the eye. In these and other procedures, a balanced salt solution (BSS) or other irrigation fluid may be introduced into the eye and removed as part of the aspirated fluid during the procedure.

[0003] In such ophthalmic surgical procedures, it may be desirable to monitor the pressure of the fluid being aspirated while it is being aspirated. This may help the operator to adjust the procedure, monitor the intraocular pressure, and / or determine if there is any partial or complete blockage in the aspiration line. In addition, it may be desirable to monitor the pressure of the fluid being introduced into the eye. This may also help the operator to adjust the procedure and / or monitor the intraocular pressure.

[0004] Conventional systems for fluid irrigation and aspiration and / or pressure measurement in ophthalmic procedures are disclosed in U.S. Pat. Nos. 6,261,283, 6,293,926, 6,572,349, 6,632,214, 6,740,074, 6,902,542, 6,962,488, 7,393,189, 8,011,905, 8,545,198, 8,790,096, 9,482,216, and 9,931,447, the disclosures of which are incorporated herein by reference in their entireties. Conventional pressure sensors are further disclosed in US Pat. Nos. 5,910,110 and 5,470,312, the disclosures of which are incorporated herein by reference in their entireties.

[0005] Conventional systems for monitoring fluid pressure during ophthalmic procedures include using load cells to measure the deflection of a diaphragm in contact with the fluid, and optical measurements of the deflection of a diaphragm in contact with the fluid. Load cell systems involve a load cell transducer contacting the diaphragm on the opposite side of the diaphragm from the fluid. This contact method can have limited frequency response and relatively high hysteresis, and may require additional protection for the sensor to meet safety requirements. Optical systems involve reflecting light off the diaphragm to measure its displacement. Although this is a non-contact method, such systems can be sensitive to variations in the optical alignment and / or surface finish of the diaphragm.

[0006] Accordingly, there is a need for improved systems and methods for monitoring fluid pressure in ophthalmic procedures. Summary of the Invention [Means for solving the problem]

[0007] The present disclosure relates to systems and methods for measuring fluid pressure in ophthalmic surgical systems.

[0008] In some embodiments, the ophthalmic surgical system includes a handpiece having a working tip for performing an ophthalmic surgical procedure inside the eye; an irrigation system for delivering irrigation fluid to the eye during the ophthalmic surgical procedure, the irrigation system including an irrigation source, an irrigation path in the handpiece, and an irrigation tube between the irrigation source and the irrigation path in the handpiece; an aspiration system for aspirating fluid from the eye during the ophthalmic surgical procedure, the aspiration system including an aspiration path in the handpiece, an aspiration tube extending from the aspiration path in the handpiece, and a pump for providing suction through the aspiration tube and the aspiration path in the handpiece; and an eddy current pressure sensor system. In some embodiments, an exemplary eddy current pressure sensor system includes a conductive movable diaphragm having a first side and a second side, the first side of the diaphragm facing a flow path for either an aspiration fluid to be aspirated from the eye or an irrigation fluid to be delivered to the eye; and an eddy current position sensor disposed on the second side of the diaphragm without contacting the diaphragm, the eddy current position sensor including a position sensor coil actuable by a high frequency alternating current; and signal conditioning electronics capable of sensing changes in inductance or impedance, or changes in resonant frequency, in the position sensor coil as a gap between the diaphragm and the position sensor coil changes and converting the changes into a displacement signal related to fluid pressure.

[0009] In some embodiments, the position sensor coil is contained within a non-conductive housing. In some embodiments, the eddy current position sensor includes a high frequency oscillator for energizing the position sensor coil at a high frequency.

[0010] In some embodiments, the ophthalmic surgical system includes a fluid module in combination with a fluid cassette, the fluid module and fluid cassette together including an irrigation pathway through which irrigation fluid is delivered to the eye during an ophthalmic surgical procedure, an aspiration pathway through which aspirated fluid is removed from the eye during an ophthalmic surgical procedure, and an eddy current pressure sensor system as disclosed herein.

[0011] In some embodiments, a method for measuring fluid pressure in an ophthalmic surgical system includes: passing fluid through a fluid flow path during an ophthalmic surgical procedure, the conductive movable diaphragm being positioned such that a first side of the diaphragm faces the fluid flow path; actuating a position sensor coil with a high frequency alternating current, the position sensor coil being positioned on a second side of the diaphragm without contacting the diaphragm; sensing a change in inductance or impedance or resonant frequency in the position sensor coil as a gap between the diaphragm and the position sensor coil changes due to a change in fluid pressure in the fluid flow path, and converting the change into a displacement signal related to the fluid pressure. In some embodiments, the fluid flow path can be an aspiration path. In some embodiments, the fluid flow path can be an irrigation path.

[0012] The accompanying drawings illustrate implementations of the systems and methods disclosed herein and, together with the description, serve to explain the principles of the present disclosure. [Brief description of the drawings]

[0013] [Figure 1] 1 illustrates an example of an ophthalmic surgical console that may be used in systems and methods according to the present disclosure. [Diagram 2] 1 is a schematic diagram of an example of a fluid system that may be used in the systems and methods according to the present disclosure. [Diagram 3] FIG. 1 illustrates an exploded view of an example cassette that may be used in the systems and methods according to the present disclosure. [Figure 4]1 illustrates an example of a diaphragm and fluid module that is part of an ophthalmic surgical console that may be used in systems and methods according to the present disclosure. [Diagram 5] 1 is a schematic diagram of an example of a pressure sensor that may be used in the systems and methods according to the present disclosure. [Figure 6] FIG. 7 is a schematic diagram of the pressure sensor of FIG. 6 showing the magnetic field and induced eddy currents. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The accompanying drawings can be better understood with reference to the following detailed description.

[0015] For the purpose of facilitating an understanding of the principles of the present disclosure, reference will now be made to the implementations shown in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation on the scope of the disclosure is intended. Any alternatives and further modifications to the described systems, devices, apparatus, and methods, as well as any further applications of the principles of the present disclosure, are fully contemplated as would normally occur to one skilled in the art to which the present disclosure pertains. In particular, features, components, and / or steps described with respect to one implementation may be combined with features, components, and / or steps described with respect to other implementations of the present disclosure. For simplicity, in some cases, the same reference numbers are used throughout the drawings to refer to the same or similar parts.

[0016] 1 illustrates an example of an ophthalmic surgical console 100 that can be used with the systems and methods according to the present disclosure. The ophthalmic surgical console 100 may be similar to the ophthalmic surgical console shown and described in U.S. Patent No. 9,931,447, the entire disclosure of which is expressly incorporated herein by reference. The ophthalmic surgical console 100 may be similar to known and used ophthalmic surgical consoles, such as the CONSTELLATION® Vision System available from Alcon Laboratories, Inc. (Fort Worth, Texas), or the CENTURION® available from Alcon Laboratories, Inc. (Fort Worth, Texas), or any other ophthalmic surgical console suitable for use with the principles described herein.

[0017] 1, an exemplary ophthalmic surgical console 100 includes a housing 102 within which a computer system is disposed and an associated display screen 104 that displays data related to system operation and performance during an ophthalmic surgical procedure. The console 100 also includes foot pedals 106 that an operator can use to control one or more functions.

[0018] The console 100 includes one or more systems that may be used in performing an ophthalmic surgical procedure. For example, the console 100 includes a fluid system 200 (FIG. 2) that includes an irrigation system for delivering fluid to the eye and an aspiration system for aspirating fluid from the eye. The console 100 may also include an ultrasound generator system for driving an ultrasonic vibration handpiece, such as for phacoemulsification during cataract surgery, and / or a pneumatic vitrectomy cutter system for driving a vitrectomy handpiece. The systems may overlap and cooperate to perform various aspects of the surgery.

[0019] 2 is a schematic diagram of an example of a fluid system 200 that may be used in the systems and methods according to the present disclosure. Fluid system 200 may be similar to the fluid system shown and described in U.S. Patent No. 9,931,447, or may be similar to known and used fluid systems such as the CONSTELLATION® Vision System or the CENTURION® Vision System, or may be similar to any other fluid system suitable for use with the principles described herein.

[0020] Fluid system 200 includes irrigation system 300 and aspiration system 302, each of which is in communication with handpiece 118. Irrigation system 300 includes an irrigation source 304, such as a sterile solution reservoir, an irrigation valve 306 that regulates flow from the reservoir to the surgical site, flexible irrigation tubing 308, an irrigation pathway 310 within handpiece 118, and a sleeve 312, which may be considered a component of handpiece 118. Handpiece 118 includes a working tip 334 (such as a phacoemulsification tip or vitrectomy needle), and in some embodiments, irrigation sleeve 312 may be disposed around working tip 334.

[0021] The exemplary irrigation system 300 extends between the irrigation source 304 and the handpiece 118 and delivers irrigation fluid through an irrigation channel to a surgical site (labeled as eye 10 in FIG. 2) during a surgical procedure. The irrigation source 304 may be, for example, a mechanically pressurized source of fluid, such as a clamp pressure system. In other embodiments, the irrigation source 304 may be a source suspended by a pole (e.g., an IV pole), which may or may not be adjustable. Other fluid sources may be used. In one example, the sterile fluid is saline, although other fluids may be used.

[0022] In some embodiments, the irrigation tubing 308 is formed of multiple segments, some of which are rigid and others of which are flexible. Also, in some embodiments, at least a portion of the irrigation system 300 is formed in a cassette 314 that cooperates with the console 100 of FIG. 1 to provide fluid communication between the irrigation source 304 and the patient's eye 10. The pressure of the fluid in the irrigation flow path may be monitored via a pressure sensor in the handpiece or via pressure sensor 602 (as described below).

[0023] The exemplary aspiration system 302 includes an aspiration pathway 316 in the hand piece 118, a flexible aspiration tube 318, a pump 322, a vent valve 324, a drain line reservoir 326, and a drain or drain reservoir 328. A hand piece connector 330 connects the aspiration pathway 316 in the hand piece 118 to the aspiration tube 318. A cassette connector 332 connects the aspiration tube 318 to a cassette aspiration line in the cassette 314. As can be seen, the aspiration system 302 extends from the surgical site (eye 10) to the drain reservoir 328. The aspiration system 302, including the aspiration fluid pathway 316, may be in fluid communication with a bore of a working tip 334 of the hand piece 118. The aspiration system 302 is used to aspirate fluid from the eye during a surgical procedure, as well as any other material to be aspirated from the eye, such as emulsified particles or vitreous fibers, through the aspiration flow path.

[0024] In some embodiments, the aspiration tube 318 is formed of multiple segments, some of which are rigid and others of which are flexible, and in some embodiments, at least a portion of the aspiration system 302 is formed in a cassette 314 that cooperates with the console 100 of FIG. 1 to provide fluid communication between the handpiece 118 and a drain reservoir 328. The drain reservoir 328 may be a bag or any suitable container, and in some embodiments, it may be a drain instead of a completely self-contained reservoir.

[0025] If the aspiration path becomes obstructed, such as if lens debris becomes lodged in a portion of the aspiration path during surgery, the surgical system may detect a vacuum or pressure differential via a pressure sensor in the handpiece or via pressure sensor 600 (as described below). The surgical system may control vent valve 324 to open to relieve the vacuum or pressure differential in the aspiration path and reduce the effects of the obstruction. This reduces the magnitude of any resulting surge and maintains a predetermined level of vacuum so as not to reduce the efficiency of the surgery.

[0026] FIG. 3 illustrates an exploded view of an example of a cassette 314 that may be used with the fluid system 200 of FIG. 2 according to the present disclosure. The body of the cassette 314 may be formed by an upper housing 410 and a lower housing 420 coupled together. The housings 410 and 420 may be formed of a rigid thermoplastic material, such as polycarbonate and / or polysulfone, to provide rigidity and structure. A pump interface portion 450 may be disposed within the cassette 314 to engage with the pump 322. The pump 322 may be an elastomeric pump configured to drive fluid flow in the aspiration flow path. A cover 452 having an arc-shaped elastomeric channel cover 454 may be disposed on the pump interface portion 450 as part of the pump 322. A vent valve chamber 430 and an irrigation valve chamber 440 may also be provided within the cassette 314. The vent valve chamber 430 may be configured to accommodate the vent valve 324. The irrigation valve chamber 440 may be configured to accommodate the irrigation valve 306.

[0027] Portions of the irrigation and aspiration flow paths may extend within the body of the cassette 314 as channels and / or tubes. A vent valve chamber 430 may be disposed within the vent pathway 350 to selectively open and close the vent valve 324 to allow vacuum venting via the vent pathway 350. In some embodiments, the vent valve 324 may be a rotary stopcock valve formed of a high density resilient polymer such as polyethylene or acetal such that the vent valve 324 may be press fit within the vent valve chamber 430. The vent valve 324 may thus be rotated within the vent valve chamber 430 driven by a valve motor (not shown) having an angular position encoder to selectively open and close the vent pathway 350.

[0028] The cassette 314 has holes 462, 464 and notches 466, 468 for aligning the cassette 314 with the console 100 when the cassette 314 is loaded into the console 100. The cassette 314 may be removable and disposable or consumable that may be used for a single patient treatment. A new cassette 314 may be used for a new treatment.

[0029] 3 also shows a diaphragm 402 that may be used in a pressure sensor for an aspiration system, and a diaphragm 404 that may be used in a pressure sensor for an irrigation system. Diaphragm 402 is held in place within cassette 314 by a retaining ring 406. Diaphragm 404 is held in place within cassette 316 by a retaining ring 408. Retaining rings 406, 408 may be attached to a housing of cassette 314, and diaphragms 402, 404 may be secured between the respective retaining rings 406, 408 and the housing of cassette 314, and / or may be otherwise secured to the respective retaining rings 406, 408 and / or the housing of cassette 314, for example by adhesive or welding. Diaphragms 402, 404 and their functions in pressure sensors are described further below.

[0030] 4 illustrates a diaphragm 402 and a fluid module 500 that are part of an ophthalmic surgical console 100 that may be used in the systems and methods according to the present disclosure. The fluid module 500 is designed to receive the cassette 314 and to interact with the cassette 314 as part of the fluid system 200. The fluid module 500 has lugs 562, 564 that align with holes 462, 464 in the cassette 314 and lugs 566, 568 that align with notches 466, 468 in the cassette 314 to load the cassette 314 into the console 100.

[0031] The fluidic module 500 includes a pump housing region 550 that houses the mechanism of the pump 322 that interacts with the arcuate elastomeric channel cover 454 of the cassette 314. The fluidic module 500 includes regions 506, 524 for housing the irrigation valve 306 and the vent valve 324, respectively. The fluidic module 500 further includes regions 502, 504 for housing the diaphragms 402, 404, respectively. The regions 502, 504 may be shaped and sized accordingly to the diaphragms 402, 404, respectively. For example, the diaphragms 402, 404 may be circular and the regions 502, 504 may be circular. The fluidic module 500 may include a non-conductive pressure sensor coil housing 510 for housing the coil of the pressure sensor 600 and / or a non-conductive pressure sensor coil housing 512 for housing the coil of the pressure sensor 602. Alternatively, the coil of pressure sensor 600 and / or the coil of pressure sensor 602 may be implemented using traces (e.g., copper or another suitable conductor) on a printed circuit board.

[0032] FIG. 5 is a schematic diagram of an example pressure sensor 600 that may be used in the systems and methods according to the present disclosure. As shown in FIG. 5, the pressure sensor 600 includes a position sensor with a position sensor coil 610. As will be understood by one of ordinary skill in the art, the position sensor coil 610 is shown diagrammatically. In some embodiments, as described above, the position sensor coil 610 (and / or the position sensor coil 612 of the pressure sensor 602) may be implemented using traces on a printed circuit board. As can be seen from FIGS. 4 and 5 and the disclosure herein, the position sensor is a non-contact sensor; that is, the position sensor is not in physical contact with the diaphragm 402. The position sensor is also not in contact with the fluid being measured, as the diaphragm separates the fluid from the position sensor.

[0033] Diaphragm 402 is a conductive sheet or plate that moves in response to fluid pressure applied to it. For example, diaphragm 402 can be a thin metallic material, such as stainless steel or another suitable metal or conductive material. By way of example, the diaphragm can be approximately 0.5 inches in diameter and approximately 0.003 inches thick. Other suitable materials, shapes, and dimensions are possible and are contemplated within the scope of this disclosure.

[0034] The position sensor coil 610 is a conductive coil that is part of an AC circuit. The position sensor coil 610 can be relatively small, for example, 2-4 millimeters in diameter and about 0.5 millimeters in height, although other suitable dimensions are possible and are contemplated within the scope of this disclosure.

[0035] The system further includes an AC power supply and high frequency oscillator 620, and a measurement device 630, which includes signal conditioning circuitry that measures changes in impedance, inductance, or resonant frequency of the position sensor coil 610, making measurements as described below. The high frequency oscillator generates a suitable frequency for the purposes described herein, for example 2 MHz or any other suitable frequency. The position sensor coil 610 is connected to the rest of the circuit via leads. When the position sensor coil 610 is activated by the high frequency oscillator, it generates a magnetic field due to a current flowing through the coil.

[0036] The pressure sensor 600 operates as an eddy current pressure sensor. Figure 6 is a schematic diagram of the pressure sensor 600 of Figure 5 showing the magnetic field and the induced eddy currents. When the position sensor coil 610 is actuated with an alternating current, it generates a magnetic field 710 as shown. This magnetic field 710 induces local currents in the form of eddy currents 720 in the conductive diaphragm 402 in close proximity to the position sensor coil 610. The eddy currents 720 generate a magnetic field 730 that opposes the magnetic field 710. The eddy currents 720 and the resulting magnetic field 730 cause a change in the inductance or impedance or resonant frequency of the position sensor coil 610.

[0037] As can be seen from Figure 3, the diaphragm 402 is in contact with the fluid aspirated from the eye via the aspiration line. The diaphragm 402 is non-invasive and isolates the fluid from the rest of the pressure sensor 600. As the fluid pressure on the diaphragm 402 changes, the position of the diaphragm 402 changes slightly in response to the change in pressure. As a result, the position of the diaphragm 402 changes relative to the fixed position of the position sensor coil 610. These position changes result in different eddy currents 720 and different magnetic fields 730, which in turn result in a difference in the inductance or impedance or resonant frequency of the pressure sensor coil 610.

[0038] The measuring device 630 can measure changes in inductance or impedance or resonant frequency of the position sensor coil 610. As the gap between the diaphragm 402 and the position sensor coil 610 changes, the signal conditioning electronics senses the variation in inductance or impedance or resonant frequency. The signal conditioning electronics converts this variation into a usable displacement signal. That is, from these measurements, the position of the diaphragm 402 is determined using the position sensor. The signal conditioning electronics may include available electronics such as the LDC 1614 Inductance to Digital Converter available from Texas Instruments. By calibrating the determined position with the fluid pressure, a correlation is established in which the fluid pressure is determined based on the measurements of the measuring device 630. Thus, the eddy current pressure sensor 600 is used to determine the fluid pressure acting on the diaphragm 402.

[0039] Although pressure sensor 600 is shown as a pressure sensor for an aspiration fluid, the eddy current pressure sensors disclosed herein may also be used as pressure sensor 602 for an irrigation fluid. For example, in Figures 5 and 6, diaphragm 402 may be diaphragm 404, pressure sensor 600 may be pressure sensor 602, and position sensor coil 610 may be position sensor coil 612 (as shown generally in Figure 2). Diaphragm 404 may be similar to diaphragm 402 as described herein, and pressure sensor 602 for an irrigation fluid may be designed and operated as described herein for pressure sensor 600 for an aspiration fluid. When two or more eddy current pressure sensors as described herein are used in the same system (e.g., one for an aspiration fluid and one for an irrigation fluid), it may be desirable to operate the different sensors at different frequencies to avoid interference.

[0040] The use of eddy current pressure sensors 600 and / or 602 in an ophthalmic surgical system as disclosed herein allows for non-contact, non-invasive measurement of fluid pressure in an ophthalmic procedure. The system uses a load cell sensor in a contact manner that contacts a diaphragm, providing advantages over conventional ophthalmic surgical systems that may have drawbacks of limited frequency response, relatively high hysteresis, as well as potential additional protection required for the sensor to meet safety requirements. Additionally, the use of eddy current pressure sensors 600 and / or 602 in an ophthalmic surgical system as disclosed herein provides advantages over conventional ophthalmic surgical systems that use optical pressure sensors and may have drawbacks due to sensitivity to variations in optical alignment and / or diaphragm surface finish. The use of eddy current pressure sensors 600 and / or 602 in an ophthalmic surgical system as disclosed herein does not require narrow beam light generation, complex optical alignment, or high speed image processing as required for conventional optical pressure sensors in ophthalmic surgical systems. Instead, the use of eddy current pressure sensors 600 and / or 602 in an ophthalmic surgical system as disclosed herein provides faster response and simple implementation.

[0041] The use of eddy current pressure sensors 600 and / or 602 in an ophthalmic surgical system as disclosed herein is also advantageous in terms of small size and ease of operation. The position sensor is not in direct contact with the diaphragm. The position sensor does not require a sharp optical image on the diaphragm. Both the sensor and control electronics are temperature compensated during the manufacturing process and can be further compensated at run time.

[0042] Those skilled in the art will understand that the implementations encompassed by the present disclosure are not limited to the specific exemplary implementations described above. In this regard, while exemplary implementations have been shown and described, a wide range of modifications, changes, and substitutions are contemplated in the foregoing disclosure. It is understood that such variations may be made to the foregoing without departing from the scope of the present disclosure. Accordingly, it is appropriate that the appended claims be construed broadly and consistent with the disclosure.

Claims

1. 1. An ophthalmic surgery system, comprising: a handpiece having a working tip for performing an ophthalmic surgical procedure inside the eye; an irrigation system for delivering irrigation fluid to the eye during the ophthalmic surgical procedure, the irrigation system including an irrigation source, an irrigation pathway in the handpiece, and irrigation tubing between the irrigation source and the irrigation pathway in the handpiece; an aspiration system for aspirating fluid from the eye during the ophthalmic surgical procedure, the aspiration system including an aspiration path in the handpiece, an aspiration tube extending from the aspiration path in the handpiece, and a pump for providing suction through the aspiration tube and the aspiration path in the handpiece; A pressure sensor system; Including, The pressure sensor system includes: a conductive movable diaphragm having a first side and a second side, the first side of the diaphragm facing a flow path for either an aspiration fluid to be aspirated from the eye or an irrigation fluid to be delivered to the eye; an eddy current position sensor disposed on the second side of the diaphragm without contacting the diaphragm, the eddy current position sensor including a position sensor coil actuable by a high frequency alternating current and signal conditioning electronics capable of sensing variations in inductance, impedance, or resonant frequency in the position sensor coil as a gap between the diaphragm and the position sensor coil changes and converting the variations into a displacement signal related to fluid pressure. Ophthalmic surgery system.

2. The ophthalmic surgical system of claim 1 , wherein the signal conditioning electronics is capable of sensing inductance in the position sensor coil.

3. The ophthalmic surgical system of claim 1 , wherein the signal conditioning electronics is capable of sensing impedance at the position sensor coil.

4. The ophthalmic surgical system of claim 1 , wherein the signal conditioning electronics is capable of sensing a resonant frequency in the position sensor coil.

5. The ophthalmic surgical system of claim 1 , wherein the first side of the diaphragm faces a flow path for aspirating fluid to be aspirated from the eye.

6. The ophthalmic surgical system of claim 1 , wherein the first side of the diaphragm faces a flow path for irrigation fluid delivered to the eye.

7. The ophthalmic surgical system of claim 1 , wherein the position sensor coil is contained within a non-conductive housing.

8. The ophthalmic surgical system of claim 1 , further comprising a radio frequency oscillator for radio frequency energizing the position sensor coil.

9. 1. An ophthalmic surgical system including a fluid module in combination with a fluid cassette, the fluid module and the fluid cassette together comprising: an irrigation flow path through which irrigation fluid is delivered to the eye during an ophthalmic surgical procedure; an aspiration flow path through which aspirated fluid is aspirated from the eye during the ophthalmic surgical procedure; a pressure sensor system; The pressure sensor system comprises: a conductive movable diaphragm having a first side and a second side, the first side of the diaphragm facing either the irrigation flow path or the aspiration flow path; an eddy current position sensor disposed on the second side of the diaphragm without contacting the diaphragm, the eddy current position sensor including a position sensor coil actuable by a high frequency alternating current and signal conditioning electronics capable of sensing variations in inductance, impedance, or resonant frequency in the position sensor coil as a gap between the diaphragm and the position sensor coil changes and converting the variations into a displacement signal related to fluid pressure. Ophthalmic surgery system.

10. The ophthalmic surgical system of claim 9 , wherein the signal conditioning electronics is capable of sensing inductance in the position sensor coil.

11. The ophthalmic surgical system of claim 9 , wherein the signal conditioning electronics is capable of sensing impedance at the position sensor coil.

12. The ophthalmic surgical system of claim 9 , wherein the signal conditioning electronics is capable of sensing a resonant frequency in the position sensor coil.

13. The ophthalmic surgical system of claim 9 , wherein the first side of the diaphragm faces the aspiration channel.

14. The ophthalmic surgical system of claim 9 , wherein the first side of the diaphragm faces the irrigation channel.

15. The ophthalmic surgical system of claim 9 , wherein the position sensor coil is contained within a non-conductive housing.

16. The ophthalmic surgical system of claim 9 , further comprising a radio frequency oscillator for radio frequency energizing the position sensor coil.

17. 1. A method for measuring fluid pressure in an ophthalmic surgical system, the method comprising: passing a fluid through a fluid flow path during an ophthalmic surgical procedure, a conductive movable diaphragm being positioned such that a first side of the diaphragm faces the fluid flow path; energizing a position sensor coil with a high frequency alternating current, the position sensor coil being disposed on a second side of the diaphragm without contacting the diaphragm; sensing variations in inductance or impedance or resonant frequency in the position sensor coil as a gap between the diaphragm and the position sensor coil changes due to changes in fluid pressure in the fluid flow path and converting the variations into a displacement signal related to fluid pressure; The method includes:

18. 20. The method of measuring fluid pressure in an ophthalmic surgical system of claim 17, wherein the step of sensing a variation in inductance or impedance or resonant frequency in the position sensor coil comprises the step of sensing an inductance variation in the position sensor coil.

19. 20. The method of measuring fluid pressure in an ophthalmic surgical system of claim 17, wherein the step of sensing a variation in inductance or impedance or resonant frequency in the position sensor coil comprises the step of sensing an impedance variation in the position sensor coil.

20. 20. The method of measuring fluid pressure in an ophthalmic surgical system of claim 17, wherein the step of sensing a variation in inductance or impedance or resonant frequency in the position sensor coil comprises the step of sensing a variation in resonant frequency in the position sensor coil.

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