WO2001050969A1

WO2001050969A1 - Laser therapy device

Info

Publication number: WO2001050969A1
Application number: PCT/EP2001/000284
Authority: WO
Inventors: Gerhard Müller; Friedrich Hoffmann; Valeska MÜLLER
Original assignee: Laser- Und Medizin Technologie Gmbh Berlin
Priority date: 2000-01-12
Filing date: 2001-01-11
Publication date: 2001-07-19
Also published as: DE10000909A1

Abstract

The aim of the invention is to provide technical measures for creating a fistula toward the Schlemm's canal with the goal of minimizing the scarring stimulus such that the duration in which the fistula can perform its function is maximized. To this end, the Schlemm's canal is subjected to an ab interno puncturing using a Q-switched erbium laser (1) having a pulse length of distinctly less than 200 ns. A preoperative filling of the Schlemm's canal with a biocompatible fluorochrome, which can be excited using a pilot laser (7), serves to prevent a complete perforation. The fluorescence detected via the active waveguide (4) serves as a switch-off criterion for the active radiation with which only the Schlemm's canal is opened. According to the invention, the scarring stimulus is further reduced by the fluorochrome that acts as a photosensitizer for inducing a non-traumatic cell death.

Description

Laser therapy device

The invention relates to a device, in particular for goniopuncture, with a pulsed laser which is connected to a probe and to a switching device, the probe being designed to emit pulsed laser radiation at a distal end of the probe.

The aim of the invention is in particular to provide a device and a method with which it is possible to open the Schlemm's canal on the human eye with minimally traumatizing access.

A large number of methods and devices are described in the literature in which goniopuncture is carried out both internally and externally via optical waveguides, a fistula generally being used to generate a subconjunctival oozing pillow is produced. All of these methods show relatively high scarring stimuli, so that the channel once created closes itself again relatively quickly through wound healing processes.Moreover, in the case of ab-externo accesses, microsurgical interventions are necessary to produce a seepage pillow, which in turn represent a scarring stimulus and the time interval in the postoperative course , in which the therapeutically desired relief via the fistula works, shortens. Typically, either excimer lasers via fibers or free-running erbium YAG lasers via mirror joint arms and short distal fiber end pieces made of special materials are used for such interventions.

Also surprisingly for the person skilled in the art, it has been found that the thermal necrosis zone which triggers the scarring stimulus and which arises during goniopuncture with lasers according to the prior art can be dramatically reduced by the fact that a Q-switched erbium-YAG laser with pulse lengths of significantly less than 200 ns applied.

Accordingly, the invention also consists in a method for goniopuncture which is characterized in that a Q-switched erbium-YAG laser with pulse lengths of significantly less than 200 ns is used.

The method for goniopuncture preferably comprises delivering pulses of an erbium-YAG laser to the tissue to be treated with a pulse duration of the order of 50 ns and a pulse energy of 1-3 mJ. With these preferred parameters, ab-interno puncture of the Schlemm's canal is achieved with approximately 3 to a maximum of 5 individual pulses in such a controlled manner that only the proximal side of the Schlemm's canal lying towards the chamber angle with the juxta-canalicular trabecular meshwork, which represents the main discharge resistance for aqueous humor. However, the structure of the channel itself remains intact, thus maintaining physiological hydrodynamics. A preferred process variant therefore includes the delivery of 3-5 individual pulses. Due to the very low individual pulse energy, it is also possible to use these pulses to be led completely from the laser generator to the goniopuncture handpiece using state-of-the-art sapphire fibers or hollow waveguides. In continuation of the inventive concept, instead of the erbium-YAG laser with an emission wavelength at 2.94 μm, an erbium-YSGG laser with an emission wavelength at 2.79 μm or an erbium-tulium laser with an emission wavelength at 2.64 μm can also be used be used.

According to the invention, the aim is also achieved with a device of the type mentioned in the introduction, in which the pulsed laser radiation is characterized by a wavelength, a pulse duration and a pulse energy of a laser pulse and by a number of pulses within a sequence of pulses, the control device and / or the laser are designed to deliver laser pulses with a duration of less than 200 ns. The control device is preferably designed to control the laser for emitting laser pulses with a pulse duration of the order of 50 ns and alternatively or additionally to control the laser for emitting laser pulses with an energy between 1 and 3 mJ and alternatively or additionally to trigger the laser for emitting an Sequence with a pulse number of 3 - 5 pulses. For this purpose, the control device preferably comprises a program memory in which at least one of the values for the pulse duration, the pulse energy or the pulse display is stored in a pulse train. Accordingly, the objective mentioned at the beginning is also achieved by a program memory for a control device, which contains values for the pulse duration, the pulse energy and the number of pulses, of which the values for the pulse duration are of the order of 50 ns, the values for the pulse energy between 1 and 3 mJ and the values for the number of pulses are between 3 and 5.

One problem with goniopuncture is that the Schlemm'sche Kana! can not only be opened, but can be completely perforated, as a result of which the rear wall of the Schlemm's canal is injured, which experience has shown that when traumatized it reacts with a clear wound healing process. This problem is solved according to the invention by a device of the type mentioned at the outset, which is designed to receive control radiation in the vicinity of the distal end of the probe and to guide it to the control device. The control device can be designed to interrupt the delivery of pulsed laser radiation via the distal end of the probe as soon as the control device receives control radiation or receives control radiation of a specific intensity, energy or duration.

In a preferred embodiment variant, the device also has means for emitting a pilot radiation, which is suitable for exciting a potentially fluorescent substance to fluoresce, in addition to the laser radiation used for the treatment, via the distal end of the probe. The pilot radiation is emitted simultaneously with the radiation serving for the treatment and excites a fluorescent substance previously introduced into the tissue to fluoresce as soon as a channel to the fluorescent substance has been opened by means of the laser radiation serving for the treatment. The fluorescence radiation then recorded via the distal end of the probe switches off the laser radiation used for the treatment by means of the control device.

In this connection, the invention includes a method in which the Schlemm'sche canal is filled preoperatively with a biocompatible fluorochrome retrograd. The biocompatible fluorochrome acts as a potentially fluorescent substance and can be, for example, sodium fluorescein or 5-ALA. However, any other biocompatible fluorochrome can also be used according to the invention.

The treatment beam used for the treatment preferably has a wavelength in the middle infrared range between 1 and 5 μm, while the fluorescence-stimulating pilot beam can be in a different wavelength range, for example between 400 nm and 1 μm, the specific wavelength range being selected such that the fluorochrome used in each case is excited to fluorescence. In a preferred embodiment variant, a pilot laser wavelength of approximately 530 nm used to excite the fluorochrome 5-ALA to fluorescence, which, as soon as it is detected via the real light waveguide, is used as a switch-off criterion for the active radiation. At the same time, the use of 5-ALA has the advantage that 5-ALA penetrates as a photosensitizer into the cell ensemble surrounding the puncture channel of the goniopuncture and, through the pilot radiation, stimulates these cells to atraumatic cell necrosis via the mechanism of the generation of oxygen radicals, with the result that the Scarring stimulus is further reduced.

A preferred embodiment of the device according to the invention is explained in more detail below with reference to FIGS. 1 and 2.

It shows:

FIG. 1 shows the block diagram of a laser system according to the invention,

Figure 2 is a schematic diagram of a device similar to Figure 1 supplemented by a pilot beam device.

An erbium laser, which can be designed according to the invention both as a YAG, YSGG or as a CTE laser 1, is guided via an optical waveguide 4, which according to the invention can be designed both as a solid core fiber and as a hollow fiber, to a handpiece 5 with an application tip 6 as a probe , The laser 1, in turn, is supplied by a power supply unit 2 and a controller 3 and is controlled according to the invention in its process parameters. For this purpose, the controller 3 has a program or control parameter memory in which the essential control parameters, namely pulse duration, pulse energy and number of pulses, are stored in a pulse train. The value for the pulse duration is of the order of 50 ns, the pulse energy is between 1 and 3 mJ and the value for the number of pulses is between 3 and 5 pulses per pulse train. The program memory is part of the controller 3 and can have any known form, for example as RAM, ROM or as magnetic memory, for example as a floppy disk. In the parameter values stored in it can be permanently predefined or exchangeable.

Figure 2 shows a device similar to Figure 1. In addition to the device from FIG. 1, the device from FIG. 2 has a second erbium laser 7, which is used to emit a pilot radiation, and two beam splitters 8 and 9, of which the beam splitter 8 is used to combine the active radiation of the erbium laser 1 with the pilot radiation of the second erbium laser 7 into the optical waveguide 4. The second beam splitter 9 is used to couple fluorescent radiation recorded with the distal end of the application tip 6, which is guided back via the optical waveguide 4 from the distal end of the application tip 6 to the proximal end of the device, from the light source guide 4 and to supply it to a control radiation detector 10. The control radiation detector 10 is connected to the controller 3, so that the controller 3 can interrupt the delivery of active radiation via the application tip 6 as soon as the control radiation detector 10 detects control radiation. In this way, the device from FIG. 2 enables the combined coupling of active radiation and pilot radiation for simultaneous detection of fluorescence in the region of the distal end of the application tip 6 as a switch-off criterion.

When using the device from FIG. 2, the active radiation from the first laser 1 and the pilot radiation from the second laser 7 are jointly coupled into the waveguide 4 via the first beam splitter 8 and emitted as a probe to the tissue to be treated via the distal end of the application tip 6. As soon as a channel has been created in this way up to a fluorochrome previously introduced into the tissue, the fluorochrome is excited by the pilot radiation of the second laser 7 to fluoresce. The fluorescence radiation enters the application tip 6 at the distal end and is guided back via the waveguide 4 to the second beam splitter 9, where at least a part of the returned fluorescence radiation is directed as control radiation to the control radiation detector 10. Depending on a specified switch-off criterion, the Control 3 interrupt the delivery of active radiation. The control criterion can be the occurrence of fluorescence radiation itself, a specific fluorescence radiation from intensity or a fluorescence radiation duration or energy.

Claims

claims

1 . Device, in particular for goniopuncture, with a pulsed laser (1), which is connected to a probe (6) and to a control device (3), the probe (6) being designed, pulsed laser radiation at a distal end of the probe (6 ) and to emit control radiation in the vicinity of the distal end of the probe (6) and to guide it to the control device (3).

2. Device according to claim 1, characterized in that the probe (6) has at least one optical waveguide (4) for the laser radiation and the control radiation.

3. Device according to claim 1, characterized in that the control device (3) with a control radiation detector (1 0) is connected and designed to interrupt the delivery of pulsed laser radiation from the laser to the distal end of the probe (6) as soon as the control radiation detector ( 1 0) Control radiation detected.

4. The device according to claim 3, characterized in that the control radiation detector (10) is designed to be wavelength-selective in such a way that it responds to fluorescent radiation as control radiation of a predetermined wavelength.

5. The device according to claim 3, characterized in that the control device (3) is designed to interrupt the delivery of pulsed laser radiation from the laser (1) to the distal end of the probe (6) after a predetermined period of time after the control radiation detector (1 0 ) Has recorded tax radiation.

6. The device according to claim 3, characterized in that the control device (3) is designed to interrupt the delivery of pulsed laser radiation from the laser (1) to the distal end of the probe (6) as soon as the control radiation detector (10) a predetermined amount of Control radiation energy has detected.

7. The device according to claim 1, characterized in that the device is designed to emit pilot radiation at the distal end of the probe (6), which is suitable to excite a potentially fluorescent substance for fluorescence.

8. The device, in particular according to claim 1, with a pulsed laser (1), which is connected to a probe (6) and to a control device (3), the probe (6) being designed, pulsed laser radiation at a distal end of the To deliver the probe (6), the pulsed laser radiation being characterized by a wavelength, a pulse duration and a pulse energy of a laser pulse and by a number of pulses within a sequence of pulses, characterized in that the control device (3) and / or the laser (1) are designed to deliver laser pulses with a duration of less than 200 ns.

9. The device according to claim 8, characterized in that the control device (3) is designed to emit the laser (1) for emitting laser pulses with a pulse duration of the order of 50 ns.

10. The device according to claim 8, characterized in that the control device (3) is designed to emit the laser (1) for emitting laser pulses with an energy between 1 and 3 mJ.

1 1. Device according to claim 8, characterized in that the control device (3) is designed to control the laser (1) to emit a sequence with a number of pulses of 3 to 5 pulses.

1 2. Device according to claim 8, characterized in that the control device (3) comprises a control parameter memory in which at least one value for the pulse duration, the pulse energy or the number of pulses is stored in a pulse train.

13. The apparatus of claim 1 or 8, characterized in that the laser (1) is designed to emit laser radiation with a wavelength between 1 and 5 microns.

14. The device according to claim 1 or 8, characterized in that the laser (1) is a Q-switched Erbium-YAG laser.

1 5. Device according to claim 1 or 8, characterized in that the laser (1) is a Q-switched Erbium-YSGG laser.

1 6. Device according to claim 1 or 8, characterized in that the laser (1) is a CTE-YSGG laser.

17. Control parameter memory for a control device (3) according to claim 15, characterized in that the control parameter memory contains values for the pulse duration, the pulse energy and the number of pulses, of which the values for the pulse duration in the order of 50 ns, the values for the pulse energy between 1 and 3 mJ and the values for the number of pulses are between 3 and 5.