Surgery – Means for introducing or removing material from body for... – With means for cutting – scarifying – or vibrating tissue
Reexamination Certificate
2001-01-23
2003-03-18
Maust, Timothy L. (Department: 3751)
Surgery
Means for introducing or removing material from body for...
With means for cutting, scarifying, or vibrating tissue
C604S027000, C604S035000, C604S043000, C604S187000, C604S239000, C604S264000, C606S167000
Reexamination Certificate
active
06533750
ABSTRACT:
The present invention generally relates to ultrasonic surgical instruments, and more particularly, relates to a needle specifically designed for promoting cavitation in eye tissue and for the removal of fragmented tissue from the eye.
Phacoemulsification involves utilization of a hand held microsurgical tool known as a phacoemulsification handpiece or probe. The phacoemulsification handpiece utilizes a small diameter needle with a tip that is designed for emulsifying, fragmenting and/or cutting tissue after it is inserted into an incision into the cornea or sclera of an eye.
The needle typically includes a central channel, or lumen, connected to a source of suction, which aspirates the emulsified, or fragmented, tissue from the eye.
The needle and tip is vibrated by an ultrasonic source and a hydrodynamic flow of a saline solution is established in order to prevent collapse of the eye interior chamber. As particles of cataract tissue are emulsified, cut, or fragmented from the cataract mass, the particles are removed from the chamber through the tip central lumen.
Many attempts have been made to improve the performance of the needle by way of enhancing the introduction of ultrasonic energy in order to provide cavitation of tissue to facilitate the fragmentation or emulsification thereof within the needle. Several types of needles have been developed, which include a design having a beveled or stepped edge in order to enhance the cutting efficiency of the cutting tip. Such as, for example, described in U.S. Pat. No. 5,993,408 to Zaleski.
Other developments include constant diameter needles having a tip wherein a forward projected surface at a beveled cutting edge is provided to enhance cavitation within the needle. See for example, a phaco tip geometry described in Ophthalmology Times V17 N14 P64 (Jul. 15, 1992). This article teaches a suction channel having a outward-tapering section that tapers conically in toward the suction channel toward the aperture at the tip of the needle.
This article asserts that a needle widening enables fragmentation of lens material with lower levels of power and permits higher suction pressures.
Further developments in needle tips include boring the tip to various sizes in a step-like progression as set forth in U.S. Pat. No. 5,451,229 to Geuder et al.
Unfortunately, none of the prior art has discovered the importance of emulsifying tissue particles before they enter the needle. The present invention is directed to the design of a needle tip with a radiation surface in order to enhance the efficiency of the needle tip by increasing a forward ultrasonic projection area of the needle.
SUMMARY OF THE INVENTION
Phacoemulsification needle in accordance with the present invention generally includes a needle body having a aspiration lumen therethrough and a hub disposed at a proximal end of the needle body for engaging an ultrasonic handpiece in order to couple ultrasonic energy to the needle body.
A tip is provided and disposed at a distal end of the needle body for penetrating tissue to be emulsified. The tip includes a larger diameter than a needle body diameter in order to provide for a conical ultrasonic radiation surface disposed at the tip for promoting cavitation in tissue forward of the needle tip. The conical ultrasonic radiation surface extends from the lumen to an end of the tip, that is, the conical surface intersects the end of the tip rather than an interior surface of the tip at a spaced apart distance from the end of the tip.
This structure causes a focusing of ultrasonic beyond the end of the tip and promotes cavitation of tissue particles before such tissue particles enter the needle. This prior cavitation significantly reduces the likelihood of plugging and/or clogging the aspiration lumen.
Importantly, the angle of disposition of the conical ultrasonic radiation surface is determined by maximizing the forward facing or focusing area of the interior of the tip. It has been found that the efficiency of ultrasonic radiation from the tip, which provides for forward cavitation, can be enhanced when the angle of radiation surface is selected in accordance with maximizing the forward focusing area within the geometrical constraints of a phaco tip. In this regard, the larger diameter of the tip enables a larger maximum diameter of the conical surface and a greater focusing area.
For example, the conical radiation surface may be disposed at an angle of between about 2 degrees and about 10 degrees with respect to a longitudinal axis of the needle body. Specifically, the ultrasonic radiation may be disposed at an angle of about 6 degrees with respect to the needle body longitudinal axis.
The present invention may also be defined as having a conical ultrasonic radiation surface of revolution which is disposed at the tip for promoting cavitation in tissue beyond the needle with the surface of revolution being established about a longitudinal axis of the needle body by a straight line extending between the lumen and a bitter end of the tip. The straight line intersecting between the longitudinal axis defines a disposition of the conical radiation surface which as hereinabove noted it may be between 2 degrees and about 10 degrees.
REFERENCES:
patent: 4297886 (1981-11-01), Anikeev et al.
patent: 4808153 (1989-02-01), Parisi
patent: 4816018 (1989-03-01), Parisi
patent: 5213569 (1993-05-01), Davis
patent: 5242385 (1993-09-01), Strukel
patent: 5451229 (1995-09-01), Geuder et al.
patent: 5653724 (1997-08-01), Imonti
patent: 5989209 (1999-11-01), Barrett
patent: 5993408 (1999-11-01), Zaleski
patent: 5993409 (1999-11-01), Maaskamp
patent: 6007499 (1999-12-01), Martin et al.
patent: 6007555 (1999-12-01), Devine
patent: 6039715 (2000-03-01), Mackool
patent: 6159175 (2000-12-01), Strukel et al.
Article: New Phaco Tip Geometry Balances Power, Suction from Ophthalmology Times dated Jul. 15, 1992.
Kadziauskas Kenneth E.
Sutton Thomas B.
Advanced Medical Optics
Gluck Peter Jon
Hackler Walter A.
Maust Timothy L.
Ramana Anu
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