ULTRASOUND PROBE

Abstract: According to the present invention a body (40) is inserted between an ultrasound crystal (30) and an output port (27) in a probe filled with a fluid, to centrally defocus generated ultrasound and create an output ultrasound field having limited propagation, especially for higher intensities, after passing the output port. The casing is divided into three portions (21, 22, 23), whereby a front conical portion (21) including the output port (27) and the centrally defocusing body (40) is easily replaceable, the fluid in the casing being refilled via a tube connection (12) to a fluid storage connected as a communicating vessel to the ultrasound device. Moreover, the output port of the device is provided with a thin membrane (10), preferably of replaceable latex rubber, which is attached by a special fixing means (11) to prevent the fluid in the casing from emerging, but at the same time enabling the effective transfer of generated ultrasound, whereby the fixing means preferably constitutes an O-ring gasket being placed in a circularly formed slot (25) on the conical portion.

Description: ULTRASOUND PROBE Technical field The present invention relates to an ultrasound probe, and particularly to a defocusing device for an ultrasound generator forming and delimiting an outgoing ultrasound field, for instance in the field of medical applications. Prior art In connection with the treatment of glaucoma, there is a general desire to treat this disease without necessarily resorting to direct surgical operation on the eye. It is known that in a glaucoma condition, small particles are gradually clogging the filter, which forms the so called trabecular meshwork, thereby increasing the pressure in the eye caused by the continuing building up of the eye aqueous fluid, that can not be drained in a natural manner, thus causing harmful pressure to the eye. Apart from the usual treatment by means of using various kinds of eye drops, there are a number of patent documents describing different instruments for ths treatment of glaucoma, to mention among others WO 91/12046 and WO 93/20783, which are related to transplantation of a drainage device into the eye, to in an artificial manner control the pressure in the eye. A number of documents, for example U.S. Patents No. 4,928,697 and 4,945,913 describe devices used to measure the pressure in the eye without making direct contact to the eye itself. Furthermore there are other devices described which comprise ultrasound probes which are surgically applied into the eye to remove unwanted tissue. Examples of such devices are: U.S. Patent No. 3,528,410, U.S. Patent No 3,857,387 and U.S. Patent No. 3,942,519. A new method, which recently has been proposed, is based upon by means of ultrasound having a specially designed field form generated, so to say, to from outside the eye shake out the particles clogging the drainage path of the eye aqueous fluid. In order to achieve this, an ultrasound probe is required being able to produce a suitable ultrasound field, which may be concentrated just around the trabecular meshwork such that during the treatment it will not affect or damage other parts of the sensitive eye. There are known many different forms of ultrasound generators. Examples of such generators appear for instance in the German patent documents: DE 945 417, DE-1 120 784, DE-4 Oil 017, DE-4 034 533, DE-4 122 590 and DE-4 136 004. The first one of these generators (DE 945 417) was disclosed already in 1956, while the last one (DE-4 136 004) dates back to 1991. DE 945 417 discloses an absorption cover, preferably of felted material which can attenuate production of standing waves. DE-1 120 784 discloses a membrane consisting, for example, of an electromechanical active ceramic material, like barium titanate, for transmission of ultrasound waves from the generator to a medium. DE-4 011 017 discloses a device for generating focused shock waves provided with two-sided shock wave sources, whereby the sources are of different types and focusing takes place by moving the sources in relation to each other. From the last three mentioned patent documents (DE-4 011 017, DE-4 122 590 and DE-4 136 004) DE-4 034 533 discloses a shock wave source with focusing of the generated pressure pulses to a convex lens serving as a focusing zone, whereby the upper face of the convex lens forming the output sound surface presents a form different from the necessary form for focusing of the pressure pulses. DE-4122590 additionally discloses a shock wave generator having a focusing means, whereby at the same time there are means, the defocusing action of which is adjustable and less than the action of the focusing means. The disclosed design is primarily intended for splitting up renal stones whereby its purpose is to create a considerably larger focusing zone in order to manage splitting up large stones. This design is not applicable for the treatment of the eye according to the suggested method. Finally DE-4 136 004 discloses a generator for generation of acoustic waves with a liquid lens adjusting the focal distance and thereby moving the focal point of the acoustic waves. The design moreover discloses a complicated construction which is not applicable for the purpose of treating eyes according to the suggested method. Description of the invention. According to the present invention, an ultrasound device is disclosed, which can generate an adapted ultrasound field, applicable, for example, in an suggested method for treatment of glaucoma, which device can be directed towards the trabecular meshwork of an eye without affecting or harming the other parts of the sensitive eye in such a treatment. According to a first objective of the present invention, a body is inserted between the ultrasound crystal and an output port of the fluid filled portion of the device in order to centrally defocus the generated ultrasound and provide a reduced ultrasound field having a limited propagation of primarily higher intensi¬ ties after passing the output port. According to a second objective of the present invention, the casing is divided into several portions, whereby a forward conical front portion, including the output port and the centrally defocusing body, is easily replaceable, whereby fluid in the probe is refilled via a tube joint connected to a liquid storage acting as a communicating vessel to the probe. According to a third objective of the present invention, the output port is provided with a thin replaceable membrane, preferably of latex rubber, fixedly held by an fixing means to prevent the fluid from emerging, but at the same time enabling effective transfer of the generated ultrasound, whereby the fixing means consists of an 0-ring gasket placed in a circular slot of the conical portion. Further objectives and purposes of the present invention are set forth in the dependent claims 5 - 8. Description of the drawings The invention will be described in form of a preferred illustra¬ tive embodiment by means of the attached drawings, wherein same reference numbers indicate equal or corresponding members, and where : Fig. 1 demonstrates an illustrative embodiment of an ultrasound probe according to the present in¬ vention; Fig. 2 demonstrates a cross section of a disassembled ultrasound probe according to Fig. 1; Fig. 3 demonstrates a front view of an illustrative embodiment of a defocusing member according to the present invention; and Fig. 4 demonstrates an enlarged cross section view of the adjustment device of the ultrasound probe. Description of an illustrative embodiment Fig. 1 presents an illustrative embodiment of an ultrasound probe according to the present invention. The probe, totally designated as 1, presents a casing 2 consisting of three portions, according to Fig. 2, a front conical portion 21, a central portion 22 provided with a tube connection 12, and a rear portion 23 provided with a coaxial socket 14, preferably of type BNC. The front conical portion 21 additionally, in its outer conical surface, is provided with a circular slot 25 in order to receive an O-ring gasket 11. The O-ring gasket is used to secure in position a membrane 10, preferably a portion of a condom, to flexibly close a front opening port 27 of the front conical portion 21. Between the central portion 22, which is threaded into the rear portion 23, an ultrasound crystal 30 is inserted, the center of which will then abut a spring biased electrically conducting plate 31 through a spring 32 electrically connected to the center pin of the BNC socket 14. The tube connection 12 onto the central portion 22 is connected by a suitable flexible tube to a fluid storage (not shown) , preferably containing distilled water. Thus the portions 21 and 22 of the assembled device, are filled with fluid acting as transmission medium for the ultrasound waves, which are electrically generated by means of the crystal 30. The very thin membrane 10 covering the opening 27 prevents the fluid from emerging, but does not prevent the generated ultrasound waves from propagating further through the opening 27 towards an outer medium in contact with the membrane. The crystal 30, which preferably in the preferred embodiment normally has a thickness of about 0.5 to 0.9 mm abuts the outer edge of the side facing the conical portion 21 and against a slightly inclined flange 33 in the central portion 22, and which is adopted to the crystal 30. The flange 33 is then arranged to make electrical contact with the side of the crystal facing the conical portion and thereby connecting it to the outer sleeve of the BNC socket. The flange 33 also centers the crystal 30 in the device. To electrically make connection, an electrically conductive material is used which at the same time serves as sealing substance to prevent the space behind the crystal 30 from being filled with fluid. For instance, in a preferred embodiment of the ultrasound probe, preferably a nylon or teflon ring (not shown) is positioned against the circumferential edge of the crystal 30 at the side facing the BNC socket and which ring further is pressed against the crystal 30 by a strong helical spring (not shown) and which has an external diameter corresponding to the internal diameter of the rear portion 23. By means of this latter arrangement, the crystal is ensured to maintain its position during operation and that no liquid may leak into the rearmost space area. Moisture eventually leaking will, according to the state of the art, be detected by the electronic unit feeding power to the crystal 30. Additionally there is, inside the conical portion 21, centered a body 40, preferably made of rubber. In the illustrated embodiment the body 40 has the form of a cone with rounded top, and it is centered with great precision in the conical portion 21 by means of three beams 41. In the illustrative embodiment the beams 41 are made of thin injection needles which have a small spacing rivet soldered at the ends facing the body 40, the rivet defines exactly how deep the beams should reach into the, in advance designed, fastening holes in the body 40 to guarantee a good centering therein. The other ends of the three beams 41, according to the disclosed embodiment, are attached to the inner wall of the conical portion 21. The conical portion 21 is attached to the central portion 22 by a threaded attachment, whereby an oval O-ring gasket 50, shown enlarged in Fig 4, seals the connection between the two sections 21 and 22. The O-ring gasket 50 is made oval to allow an exact adjustment of the conical portion, and thereby the body 40, relative to the crystal 30. The oval cross section of the O-ring 50 allows a position range variation of about 1 mm between the portions 21 and 22 with a retained satisfactory sealing quality. In Fig 2 and 4, 51 designates a clearance zone for the conical portion 21. The device, according to the illustrated embodiment, may operate with replaceable conical portions 21, which, for example, may have different length and/or different sized output opening, and/or a different body 40. In a preferred embodiment of the present invention the opening 27 of the conical portion 21 is slanted about 10°-15° (not seen in Fig. 2) relative to the longitudinal axis of the conical portion 21 to obtain an easy application of the device to the area middle over the trabecular meshwork of the eye. Even a larger slanting of the opening 27 could be advantageous in a particular operation with the device. Before utilization, the portion 21 will be assembled to the rest of the casing and a fluid connection is made to a storage container, for instance a plastic bag filled with distilled water or saline. Such liquid bags are well known in the technical field. By keeping the device 1 at a suitable height in relation to the liquid bag, fluid will flow into the device 1. The device should preferably be held with its opening 27 directed upward so that when the device is fully filled, the water will be pressed out through the opening 27. By properly balancing the height, as stated above, and utilizing the fluid surface tension, fluid is obtained all the way out to the discharge opening of the portion 21, and thus, all air has been evacuated from the device. At this point, a piece of latex rubber, in the simplest case a piece of a condom, will be placed over the opening 27, and the latex rubber will be tightened over the conical portion by means of rolling upwards a suitable O-ring gasket 11 until it locks into the slot 25. At this stage, the device is ready for use after, in addition, the tip of the conical portion 21 preferably has been provided with a smear of gel to be able to transmit the ultrasound to an area, middle over the trabecular meshwork of the eye, to be treated. In a case when the device will be used for the treatment in connection to glaucoma, the tip having the gel is placed carefully to the area middle over the trabecular meshwork and the crystal 30 is powered and thereby an ultrasound field is obtained, the energy of which is intended, only of an order of 0.6 to 1 mm, to be active into the eye, according to the present state of the art. The probe 1 is then moved carefully around the iris along the trabecular meshwork. Thus the desired effective field pattern of the active ultrasound is obtained through the combination of the shape of the conical portion and the form of the body 40 and its central position in front of the crystal 30 according to the present invention, whereby a direct wave from the crystal is restricted from propagating through the opening 27 and into the eye, where such a wave could reach too deep and even could be harmful . A number of standard portions 21 could be manufactured, based on the medical requirements for field patterns of the ultrasound. The ultrasound device according to the present invention can of course be modified in various ways by a person skilled in the art without departing from the spirit and scope of the invention as being defined in the attached claims.

Claims: Claims 1. A device for generation of a centrally limited ultrasound field comprising an ultrasound crystal (30) , mounted within a casing (2) which in a part of the internal space includes a liquid allowing propagation of an electric ultrasound field, said ultrasound field being generated by said ultrasound crystal driven by an electric source connected via a socket (14) characterized in that between said ultrasound crystal (30) and an output port (27) a body (40) is inserted into a liquid filled part of the probe (1) in order to centrally defocus said generated field and to create an output ultrasound field having a limited propagation, primarily of higher intensities, after passing said output port (27) . 2. The device according to claim 1, characterized in that said casing is divided into several portions ( 21, 22, 23) , whereby a front conical portion including said output port (27) and said central defocusing body (40) easily is replaceable, said liquid in said casing being refilled through a tube connection (12) to a liquid storage connected as a communicating vessel to said device (1) . 3. The device according to claim 2, characterized in that said output port of the device is provided with a thin membrane, preferably of replaceable latex rubber, which is secured by a locking means (11) preventing said liquid from emerging, but at the same time enabling an effective transfer of the generated ultrasound. 4. The device according to claim 3, characterized in that said locking means (11) comprises an O-ring gasket being placed in a circular slot on a conical portion (21) . 5. The device according to claim 2, characterized in that the connection between said conical portion (21) and a central portion (22) of said casing is provided with a sealing means (50) enabling a certain fine adjustment of the distance between said output port (27) and said ultrasound crystal (30), whereby a coupling between said portions (21, 22) is achieved by a mutual thread. 6. The device according to claim 2, characterized in that said ultrasound crystal (30) bears on said central portion (22) of the casing such that a liquid proof coupling is achieved to prevent fluid from penetrating into a rear space containing a power connection to an active driven electrode of said ultrasound crystal. 7. The device according to claim 1, characterized in that said body (40) to centrally defocus said generated ultrasound, is precisely fitted at the center by means of thin stable booms (41), which in turn are attached to an inner surface of said conical portion (21). 8. The device according to claim 1, characterized in that said body (40) is made of, preferably a rubber-casted cone body having a rounded top, or a ball. 9. The device according to claim 1, characterized in that an opening, constituting said output port (27) of said conical portion (21), is given an angle relative to the longitudinal axis of said conical portion allowing the device to be held in a inclined position during a treatment for obtaining an easy application of the device to an area middle over the trabecular meshwork of the eye. 10. Application of the device according to any of the claims 1 to 9, in which said membrane of the device, externally provided with a suitable gel, is brought into contact with an area over the trabecular meshwork of an eye, by means of ultrasound, to shake off small particles generally clogging the eye aqueous fluid drainage canals, in connection with a glaucoma illness condition.

Inventors: EKBERG LARS, SUNDSTROEM KARL-ERIK, SVEDBERGH BJOERN, EKBERG, LARS, SUNDSTROEM, KARL-ERIK, SVEDBERGH, BJOERN
Applicants: EKBERG LARS, SUNDSTROEM KARL ERIK, SVEDBERGH BJOERN, EKBERG, LARS, SUNDSTROEM, KARL-ERIK, SVEDBERGH, BJOERN
Application year: 1996
Main classification: A61N7
IPC codes: A61B17, A61B18, A61F9, A61N7, B06B3, G10K11