WO2001024744A1

WO2001024744A1 - Sleeve for microsurgical instrument

Info

Publication number: WO2001024744A1
Application number: PCT/US2000/016558
Authority: WO
Inventors: Mikhail Boukhny
Original assignee: Alcon Universal Ltd.
Priority date: 1999-10-01
Filing date: 2000-06-15
Publication date: 2001-04-12
Also published as: AU5493000A

Abstract

An improved sleeve for a microsurgical instrument, such as a phacoemulsification handpiece, is disclosed. The sleeve has a hollow body for receiving a moving tip, and an electrically conductive film disposed on an outer surface of the body. The film may be electrically coupled to electrical circuitry that measures the temperature of the film. The temperature may be provided to a surgical console. The console may visually display the temperature, may provide an audible warning when the temperature exceeds a certain threshold, or may adjust console parameters, such as ultrasound power, in response to the temperature value.

Description

SLEEVE FOR MICROSURGICAL INSTRUMENT

Field of the Invention

The present invention relates generally to endoscopic surgical equipment and more specifically to phacoemulsification sleeves and sleeves for other microsurgical instruments that utilize an ultrasonic or other moving tip. Description of the Related Art

Phacoemulsification involves emulsifying the natural lens in situ using an ultrasonically vibrating hollow needle. The emulsified lens is aspirated out of the eye through the hollow needle simultaneously with the infusion of a saline solution. The saline solution is generally infused through the space between the outside of the needle and a thin, flexible sleeve that is held coaxial with the needle. One of the primary benefits of phacoemulsification is that the lens can be removed through a very small incision. With the introduction of foldable intraocular lenses, and the ability to insert these replacement lenses through even smaller incisions, the desirable size of the incision through which the phacoemulsification tip and irrigating sleeve must pass is also becoming smaller.

While the desirable phacoemulsification incision size has become smaller, the overall diameter of the cutting tip/sleeve combination has remained relatively constant. As a result, the tip/sleeve combination must be used in a very tight wound. While the elasticity of the eye tissue allows adequate manipulation of the tip/sleeve within the wound, this tight wound structure compresses the sleeve around the vibrating tip, allowing heat to be generated by the vibrating tip rubbing against the sleeve. If the amount of heat generated is excessive, or occurs for a relatively long period of time, burning of the eye tissue can result. For example, exposing eye tissue to a temperature of about 140 °F or higher for a period of time as short as 0.1 seconds may cause burning. As another example, exposing eye tissue to a temperature as low as about 110 °F for an extended period of time may cause burning. In addition, the current trend in surgical technique relying on prolonged occlusion of the vibrating tip during phacoemulsification increases the likelihood of burning of the eye tissue.

Temperature measurement at the phacoemulsification incision has conventionally been accomplished using thermocouples. However, thermocouples only measure temperature at a single point of the incision, and such point temperature measurement may not reflect the highest temperature over the entire incision. In addition, even the smallest thermocouples are large enough to cause damage if the bead of the thermocouple contacts the endothelial cells. Accordingly, a need exists for a device that more effectively measures the temperature at the incision in which the moving tip of a microsurgical instrument is utilized. The device should be easy for the surgeon to use, should be non-invasive, should maximize patient safety, and should be economically feasible.

Summary of the Invention A preferred embodiment of the present invention is an improved sleeve for a microsurgical instrument. The sleeve has a hollow body for receiving a moving tip, and an electrically conductive film disposed on an outer surface of the body. The film may be electrically coupled to electrical circuitry that measures the temperature of the film. The temperature may be provided to a surgical console. The console may visually display the temperature, may provide an audible warning when the temperature exceeds a certain threshold, or may adjust console parameters, such as ultrasound power, in response to the temperature value.

Brief Description of the Drawings

For a more complete understanding of the present invention, and for further objects and advantages thereof, reference is made to the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a side view schematically illustrating a sleeve according to the preferred embodiment of the present invention; and

FIG. 2 is a side, partially sectional view schematically illustrating the sleeve of FIG. 1 removably coupled to a microsurgical instrument having a moving tip.

Detailed Description of the Preferred Embodiment

The preferred embodiment of the present invention and its advantages are best understood by referring to FIGS. 1 and 2 of the drawings, like numerals being used for like and corresponding parts of the various drawings. FIGS. 1 and 2 schematically illustrate a sleeve 10 for a microsurgical instrument

12 having a moving tip 14. By way of example, microsurgical instrument 12 may be a conventional phacoemulsification handpiece having an outer shell 16, an ultrasonically vibrating horn 18, and a cutting tip 14. Alternatively, microsurgical instrument 12 may be any conventional microsurgical instrument having a moving tip. For convenience of description, but not by way of limitation, the present invention will be described hereinbelow with reference to a phacoemulsification handpiece 12. Sleeve 10 is preferably made from a flexible, electrically insulating material.

Suitable materials include silicone rubber, the polymeric materials disclosed in U.S. Patent No. 5,282,786 to Ureche and U.S. Patent No. 5,505,693 to Mackool, which are incorporated herein in their entirety by reference, and other conventional polymeric materials. Sleeve 10 has a body 20 having open distal end 22, an open proximal end 24, and an internal chamber 26. Chamber 26 is for receiving cutting tip 14 and physically separating tip 14 from an incision into eye tissue. Sleeve 10 is preferably removably coupled to phacoemulsification handpiece 12 via conventional female threads 28. More specifically, female threads 28 preferably mate with male threads 30 on an outer surface of outer shell 16 of handpiece 12. The annular space between tip 14 and an inner wall 23 of chamber 26 preferably defines a path for the infusion of a surgical fluid into the eye via open distal end 22. The flow of surgical fluid is represented by arrows 32 in FIG. 2. The surgical fluid is preferably a surgical saline solution, such as BSS PLUS® sterile irrigating solution available from Alcon Laboratories, Inc. of Fort Worth, Texas.

Sleeve 10 has an outer surface 34. As shown best in FIG. 1, a thin film 40 of an electrically conductive material is disposed on outer surface 34. Film 40 may comprise gold, nickel, alloys thereof, or other conventional electrically conductive materials. Film 40 may be formed using a masking and sputter deposition technique or other conventional thin film forming methods. Sleeve 10 and film 40 may be coated with a conventional electrically insulative material to insulate film 40 from the surgical fluid that is infused into the eye or from the eye tissues.

The preferred pattern 42 for film 40 on outer surface 34 is shown in FIG. 1. Pattern 42 is an application of the conventional four-probe method used to measure resistance. Pattern 42 has four probes 44, 46, 48, and 50 that preferably converge at a point 52 proximate where sleeve 10 contacts eye tissue when it is fully inserted into an incision in the eye. Although not shown in the FIGS., pattern 42 forms a ring around outer surface 34 of sleeve 10 at point 53 to establish electrical conductivity between probes 44 through 50. Contacts 54, 56, 58, and 60 are electrically and physically coupled to conventional electrical leads 62, 64, 66, and 68. Conventional "press-on" contacts may be utilized for contacts 54 through 60. Leads 62 through 68 are connected to conventional electrical circuitry 70 shown schematically in FIG. 1. Although not shown in FIGS. 1 and 2, leads 62 through 68 are preferably disposed within or on handpiece 12, and electrical circuitry 70 is preferably located in handpiece 12 or a surgical console to which handpiece 12 is operatively coupled. Of course, pattern 42 may be formed with different geometries than the preferred geometry shown in FIG. 1. By way of example, pattern 42 may be formed with only two probes 46 and 48 for certain applications of sleeve 10. Pattern 42, leads 62 through 68, and electrical circuitry 70 define a resistance measuring sensor 72. The four-probe method is preferred for pattern 42 because it provides a very high signal to noise ratio and does not depend on the resistance of leads 62 through 68, which can be highly variable and may be significantly higher than the resistance of the remaining portions of sensor 72. Electrical circuitry 70 includes a power source for pattern 42. Electrical circuitry

70 may be an AC circuit, such as a conventional lock-in amplifier having an oscillator that acts as a voltage source and a receiving circuit for frequency tuning. An AC circuit allows the selection of a frequency that minimizes noise. Typically, higher frequencies produce less noise. Electrical circuitry 70 may alternatively be a DC circuit. While more susceptible to noise, a DC circuit is typically less susceptible to electromagnetic interference than an AC circuit.

If electrical circuitry 70 supplies a known current to probes 46 and 48, the voltage across probes 44 and 50 can be measured. From the measured voltage, resistance of pattern 42 can be calculated using Ohm's law (V=IR). Alternatively, if electrical circuitry 70 supplies a known voltage across probes 44 and 50, the current through probes 46 and

48 can be measured. From the measured current, resistance of pattern 42 can be calculated using Ohm's law. In either case, the resistance of pattern 42 is proportional to its temperature. Therefore, sensor 72 may be calibrated to define a relationship between the resistance and temperature of pattern 42. This temperature will be a measure of the average temperature between a first point where probes 44 and 46 merge, and a second point where probes 48 and 50 merge. Both of these points are located at point 52, where sleeve 10 contacts the eye tissue when it is inserted into an incision in the eye. The preferred use of sleeve 10 on a phacoemulsification handpiece 12 will now be described in greater detail. Tip 14 and sleeve 10 of handpiece 12 are inserted via an incision in the eye up to point 52. Sleeve 10 prevents contact between tip 14, horn 18, and the surrounding eye tissue. Outer surface 34 is in contact with the surrounding eye tissue. As horn 18 ultrasonically vibrates tip 18 in a reciprocating manner, sleeve 10 is in sliding contact with the surrounding eye tissue. This frictional contact transfers heat and ultrasound energy to the surrounding eye tissue. Sensor 72 monitors the resistance of pattern 42, and thus the temperature of pattern 42 and the surrounding eye tissue. The temperature of the surrounding eye tissue is preferably communicated to the surgeon via electrical circuitry 70 in real-time.

Electrical circuitry 70 is preferably operatively coupled to the surgical console so as to provide a visual or audible indication of the temperature of the surrounding eye tissue to the surgeon, or to adjust console parameters in response to the temperature. For example, the temperature may be visually displayed to the surgeon via a display of the console. As another example, an audible warning may occur if the temperature rises above a certain threshold, or rises above a certain threshold for a given period of time. These thresholds and time periods may be pre-set into electrical circuitry 70, or selectable by the surgeon. Alternatively, the temperature may be used to adjust any console parameter, such as ultrasound power. By way of example, as the temperature increases, ultrasound power may be decreased, either by decreasing amplitude or by maintaining a given amplitude but pulsing the ultrasound power on and off. Progressively higher temperatures preferably result in progressively lower amplitudes, or in progressively longer delays between pulses.

From the above, it may be appreciated that the present invention provides an improved device that more effectively measures the temperature at the incision in which the moving tip of a microsurgical instrument is utilized. The device is easy for the surgeon to use, non-invasive and safe for the patient, and relatively inexpensive to manufacture.

The present invention is illustrated herein by example, and various modifications may be made by a person of ordinary skill in the art. For example, although the preferred device is described hereinabove in connection with a phacoemulsification handpiece, the present invention is applicable to any microsurgical instrument having a moving tip, as well as microsurgical instruments that are used in surgeries other than cataract surgery. As another example, the geometry of the sleeve may be changed to accommodate different microsurgical instruments.

It is believed that the operation and construction of the present invention will be apparent from the foregoing description. While the apparatus and methods shown or described above have been characterized as being preferred, various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the following claims.

Claims

What is claimed is:

1. A sleeve for a microsurgical instrument, comprising: a hollow body for receiving a moving tip of a microsurgical instrument; and an electrically conductive film disposed on an outer surface of said body, said film for electrically coupling to electrical circuitry to provide a measurement of a temperature of said film.

2. The sleeve of claim 1 wherein said film is arranged in a pattern.

3. The sleeve of claim 2 wherein said pattern is a four-probe resistance measuring pattern.

4. The sleeve of claim 1 wherein said microsurgical instrument is a phacoemulsification handpiece.

5. A microsurgical instrument, comprising: an outer shell; an ultrasonic vibrating horn disposed within said outer shell; a cutting tip coupled to said horn; a hollow sleeve removably coupled to said outer shell and receiving said cutting tip; and an electrically conductive film disposed on an outer surface of said sleeve, said film for electrically coupling to electrical circuitry to provide a measurement of a temperature of said film.

6. The microsurgical instrument of claim 5 wherein said film is arranged in a pattern.

7. The microsurgical instrument of claim 6 wherein said pattern is a four- probe resistance measuring pattern.

8. The microsurgical instrument of claim 5 further comprising electrical circuitry electrically coupled to said film and capable of determining a resistance of said film.

9. The microsurgical instrument of claim 8 wherein said electrical circuitry correlates said resistance of said film to a temperature of said film.

10. The microsurgical instrument of claim 9 wherein: said electrical circuitry is for operatively coupling to a surgical console; and said console provides a visual or audible indication of said temperature.

11. The microsurgical instrument of claim 8 wherein said electrical circuitry is disposed within said outer shell.

12. The microsurgical instrument of claim 10 wherein said electrical circuitry is disposed within said console.

13. The microsurgical instrument of claim 5 wherein said instrument is a phacoemulsification handpiece.

14. The microsurgical instrument of claim 13 wherein said sleeve and said tip define an annular space for the passage of a surgical fluid.

15. A method of measuring a temperature of a sleeve of a microsurgical instrument, comprising the steps of: providing a hollow sleeve for receiving a cutting tip of a microsurgical instrument, said sleeve having an outer surface with a conductive film disposed thereon; disposing said cutting tip within said sleeve; and electrically coupling said film to electrical circuitry for measuring a temperature of said film.

16. The method of claim 15 further comprising: disposing said cutting tip and said sleeve in an incision into body tissue; moving said tip in a reciprocating manner; utilizing said electrical circuitry to measure said temperature of said conductive film.

17. The method of claim 16 wherein said utilizing step comprises: utilizing said electrical circuitry to measure a resistance of said conductive film; correlating said resistance to a temperature of said film.

18. The method of claim 16 further comprising: operatively coupling said electrical circuitry to a surgical console; and providing said temperature to said console.

19. The method of claim 18 wherein said step of providing said temperature comprises visually displaying said temperature on said console.

20. The method of claim 18 wherein said step of providing said temperature comprises providing an audible warning when said temperature exceeds a threshold temperature.

21. The method of claim 15 wherein said conductive film is disposed in a four- probe resistance measuring pattern.

22. The method of claim 18 wherein said step of providing said temperature comprises adjusting a parameter of said console in response to said temperature.

23. The method of claim 22 wherein said microsurgical instrument is a phacoemulsification handpiece, and said parameter is ultrasound power.

24. The microsurgical instrument of claim 9 wherein: said electrical circuitry is for operatively coupling to a surgical console; and said console adjusts a parameter of said console in response to said temperature.

25. The microsurgical instrument of claim 24 wherein: said microsurgical instrument is a phacoemulsification handpiece; and said parameter is ultrasound power.