Surgery – Means for introducing or removing material from body for... – With means for cutting – scarifying – or vibrating tissue
Reexamination Certificate
1999-07-28
2001-02-27
Bockelman, Mark (Department: 3734)
Surgery
Means for introducing or removing material from body for...
With means for cutting, scarifying, or vibrating tissue
C604S028000, C604S031000, C606S107000
Reexamination Certificate
active
06193683
ABSTRACT:
The present invention is generally directed to apparatus and a method for controlling power to a phacoemulsification handpiece needle as well as for controlling the flow of fluid to and from the handpiece needle during phacoemulsification.
More specifically, the present invention relates to the control of power and fluid flow to a phacoemulsification handpiece based on a determination of handpiece needle temperature.
Phacoemulsification systems typically include a handpiece having an ultrasonically vibrated hollow needle and an electronic control therefor.
As is well known in the art, the phacoemulsification handpiece is interconnected with a control console by an electric cable for powering and controlling the piezoelectric transducer and tubing for providing irrigation fluid to the handpiece and withdrawing aspiration fluid from an eye through the handpiece.
The hollow needle of the handpiece is typically driven or excited along its longitudinal axis by the piezoelectric effect in crystals created by an AC voltage applied thereto. The motion of the driven crystal is amplified by a mechanically resonant system within the handpiece, such that the motion of the needle connected thereto is directly dependent upon the frequency at which the crystal is driven with a maximum motion occurring at a resonant frequency.
Vibration of the needle also causes heating thereof which can be detrimental to corneal tissue. In fact, overheating of the needle tip during phacoemulsification procedures can cause non-recoverable corneal burns. Accordingly, it is beneficial to the ophthalmologist performing the phacoemulsification procedure to be able to prevent these occurrences.
In addition, overheating of the needle may increase bubble formation at the tip of the needle which may interfere with the phacoemulsification procedure.
The present invention overcomes these problems by providing control of the phacoemulsification apparatus through closed loop temperature control.
SUMMARY OF THE INVENTION
The phacoemulsification apparatus in accordance with the present invention generally includes the phacoemulsification handpiece having a needle and electrical means for ultrasonically vibrating the needle. The power source means is included for providing electrical power to the handpiece electrical means. Also included are means for providing irrigation fluid to the handpiece needle and means for aspirating the fluid from the handpiece needle.
Importantly, means for sensing a temperature of the handpiece needle and control means are provided for varying a power level provided to the handpiece and electrical means from the power source means in response to the needle temperature.
More particularly, the control means may vary a pulse duty cycle of the power provided to the handpiece needle by the power source means in response to the sensed needle temperature.
Alternatively, the control means may vary the irrigation fluid rate to the handpiece in response to the needle temperature or vary an aspiration fluid rate from the handpiece needle in response to the needle temperature.
More particularly, the apparatus includes an irrigation sleeve surrounding the handpiece needle and the means for sensing needle temperature comprises at least one temperature sensor disposed along the irrigation sleeve. The temperature sensor may be installed next to the junction of the handpiece needle and a handpiece horn either inside or outside of a handpiece shell.
Alternatively, the means for sensing the needle temperature may include a plurality of spaced apart temperature and sensors which may be insert molded into the irrigation sleeve. A harness means may be provided for interconnecting each of the temperature sensors to the control means.
The present invention also provides for a method for operating a phacoemulsification system. Such a system includes a phacoemulsification handpiece needle and an ultrasonic power source, a vacuum source, a source of irrigating fluid and a control unit for controlling ultrasonic power provided to the handpiece needle and the aspiration of irrigation fluid from the handpiece needle. The method includes the steps of placing the handpiece needle in an operative relationship with an eye for a phacoemulsification procedure and thereafter supplying irrigation fluid from the irrigation fluid source to and through the handpiece needle and into the eye.
The steps in accordance with the present invention further include providing ultrasonic power from the ultrasonic power source to the handpiece needle for performing the phacoemulsification procedure and applying vacuum from the vacuum source to the handpiece needle and thereby aspirating the irrigating fluid from the eye through the handpiece at a selected rate. The temperature of the handpiece needle is sensed and in response thereto, the method in accordance with the present invention, variably controls, in response to the needle temperature, the ultrasonic power being provided to the handpiece needle.
Alternatively, in response to the needle temperature, the irrigation fluid flow and/or aspiration of the irrigation fluid from the handpiece needle may be controlled.
REFERENCES:
patent: 4328803 (1982-05-01), Pape
patent: 5616120 (1997-04-01), Andrew et al.
patent: 5700240 (1997-12-01), Barwick, Jr. et al.
patent: 5766146 (1998-06-01), Barwick, Jr. et al.
patent: 5830176 (1998-11-01), MacKool
patent: 5944687 (1999-08-01), Benett et al.
patent: 6001069 (1999-12-01), Tachibana et al.
Ludin Lev
Zaleski Edward R.
Allergan
Bockelman Mark
Hackler Walter A.
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