Patent Application
20050080441
The present invention relates generally to surgical implements and techniques, especially ophthalmic microsurgical instruments.
During ophthalmic microsurgery, such as lens removal, instruments are used to cut and remove unwanted tissues, vitreous and the like. There are, of course, numerous examples of ophthalmic surgical instruments which are adapted to remove vitreous and other tissue during an ophthalmic surgical procedure, as shown in U.S. Pat. No. 3,776,238 to Peyman et al and U.S. Pat. No. 4,986,827 to Akkas et al (the entire content of each being expressly incorporated hereinto by reference). However, each of these prior examples of conventional ophthalmic surgical instruments rely on a coaxially sleeved “tube-in-tube” needle structure whereby an inner tube is moveable relative to a stationary outer tube so as to perform cutting and aspiration. As may be appreciated, as the size of the needle tubes deceases, the effective lumen diameter will also decrease thereby potentially resulting in less than desirable aspiration through the needle tubes of unwanted biological material from the surgical site. This decrease in lumen size is therefore exacerbated when there is a need for a pair of coaxially sleeved needle tubes as in the prior art. Thus, the effective size of the instrument may be limited somewhat by the countervailing need to have sufficient lumen diameter to allow for adequate aspiration of unwanted biological material from the surgical site.
According to the present invention, however, the further miniaturization of ophthalmic microsurgical instruments is enabled largely due to the fact that the conventional need for a “tube-in-tube” cutter assembly may now be avoided.
Broadly, therefore, the present invention is embodied in microsurgical instruments whereby a needle member is longitudinally sectioned to form respective needle segments, and a sleeve member surrounding the needle segments exerting circumferential radial compressive force thereon. Thus, collectively the needle segments define respective opposed longitudinal bearing edges which contact one another and thereby allow for one of the needle segments to be moveable longitudinally relative to another of the needle segments. As such, the lumen within the sectioned needle member may be maximized while the overall dimension of the instrument is minimized.
In one preferred embodiment of the present invention, the needle member may be longitudinally bifurcated so as to establish said one and another needle segments. Alternatively, according to another preferred embodiment of the present invention, the needle member may be longitudinally trifurcated so as to establish a pair of stationary outer needle segments, and an intermediate needle segment sandwiched between but longitudinally moveable relative to said outer needle segments.
These and other aspects and advantages will become more apparent after careful consideration is given to the following detailed description of the preferred exemplary embodiments thereof.
Reference will hereinafter be made to the accompanying drawings, wherein like reference numerals throughout the various FIGURES denote like structural elements, and wherein;
One preferred embodiment of a surgical instrument 10 according o the present invention is depicted in accompanying
Accompanying
As shown in
The relative positions and movements of the segments 16, 18 are achieved by means of a tubular sleeve 22. The sleeve 22 is dimensioned in such a manner that sufficient circumferential radial compression of the needle segments 16, 18 occurs so as to maintain the relative positions of the segments 16, 18, while yet allowing for relative longitudinal movements to occur between the opposed contacting bearing edges 16-1, 18-1. Advancement of the distalmost tip of segment 16 beyond the distalmost tip of segment 18 may be prevented by means of notched stops 16-2, 18-2 formed in each segment proximally of their tips.
Although the needle cutter assembly 14 is depicted in accompanying
Accompanying
The needle segments are most preferably formed by any conventional micromachining technique. By way of example, a microneedle, preferably about 20 gauge or smaller (e.g., between about 20 gauge to about 25 gauge or smaller) may be longitudinally bifurcated to form segments 16, 18 by means of conventional electrical discharge machining (EDM) techniques. Thus, the distal end of a length of microtubing (e.g., a section of a conventional 20 ga. or smaller stainless steel tubular needle) may be axially translated relative to an EDM wire provided as a component part of a conventional EDM system. When energized, the EDM wire thereby bifurcates the needle as it is translated longitudinally relative to the wire. Once the needle has been bifurcated, the distalmost end may be formed into a smooth tip by reforming, machining and/or soldering.
The outer sleeve 22 is most preferably formed of a plastics material. Plastics materials which have cold-flowable properties are especially presently preferred. By cold-flowable property is meant the permanent distortion, deformation of dimensional change which occurs in a plastics material under continuous load at temperatures below the heat-softening temperature. One preferred cold-flowable plastics material is polyimide. Pre-formed polyimide tubing is commercially available from Microtubing, Inc. of Tampa, Fla. and may be satisfactorily employed in the practice of the present invention. In such a situation, the needle segments will be positioned within the preformed tubing forming the sleeve 22.
Thermoplastic materials may also be employed for use in the outer sleeve 22 according to the present invention and may be extruded onto the needle segments 16, 18. Especially preferred thermoplastic materials include polymethylpentenes (e.g., TPX® plastics commercially available from Mitsui Products) and polyacetals (e.g., DELRIN® polyacetal commercially available from DuPont). IN such a situation, the thermoplastic material may be extruded onto an exterior circumferential surface of the needle segments thereby forming the sleeve 22.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
