JP6283992B2 - Laser surgical device - Google Patents

Description

  The present invention relates to a laser surgical apparatus that treats a patient's tissue (for example, a cornea of a patient's eye, a crystalline lens, etc.) using a nonlinear interaction by pulsed laser light.

  Conventionally, various techniques have been proposed to perform treatment (eg, cutting, crushing, etc.) of a patient's tissue with a laser beam. For example, an ophthalmic laser device disclosed in Patent Document 1 includes an fs laser. The fs laser emits pulsed laser light for forming a flap in the cornea by nonlinear interaction. In Patent Document 1, the wavelength of the pulse laser beam is a wavelength in the infrared region (1020 nanometers to 1070 nanometers), and the pulse width (pulse duration) is 100 femtoseconds to 800 femtoseconds.

  The apparatus disclosed in Patent Document 2 performs treatment using the principle of inducing plasma without plasma emission, unlike the principle of treatment using fs laser in Patent Document 1. In Patent Document 2, a single longitudinal mode pulse laser beam is used. The wavelength of the pulsed laser light is 300 nanometers to 1000 nanometers, and the pulse width is 300 picoseconds to 20 nanoseconds (for convenience, the treatment method exemplified in Patent Document 2 will be referred to as “subnanosecond laser below”. Treatment method ”).

Special table 2012-520695 gazette US Patent Publication No. 2010/0163540

  A conventional laser apparatus using an fs laser needs to emit an ultrashort pulse laser having a very high peak output. Therefore, it is difficult to simplify the configuration of the laser unit. On the other hand, in the treatment method using the sub-nanosecond laser, the peak output of the laser pulse is lower than the peak output of the laser pulse in the fs laser disclosed in Patent Document 1. However, the pulse width of each laser pulse is longer than the femtosecond order. Therefore, it has been difficult to reduce the total amount of energy of the pulse laser beam.

  A typical object of the present invention is to provide a laser surgical apparatus capable of efficiently treating a patient's tissue with a simple configuration.

The laser surgical apparatus of the present invention is a laser capable of treating a tissue by causing a nonlinear interaction to occur at a focused position of the pulsed laser beam in the tissue by focusing the pulsed laser beam on a patient's tissue. A surgical apparatus, a laser unit having an oscillator that oscillates pulsed laser light, scanning means for scanning the focused position of pulsed laser light emitted by the laser unit in the tissue, and controlling the scanning means Scanning control means for condensing a plurality of laser pulses in the pulse laser light emitted by the laser unit at each of the plurality of condensing positions, and the control means includes the scanning means Plurality of low output compared to femtosecond laser that induces plasma with plasma emission while scanning by By irradiating a laser pulse on one of the condensing positions, and performing a treatment by using the principle of inducing a plasma without plasma emission.

  The laser surgical apparatus of the present invention can efficiently treat a patient's tissue with a simple configuration.

1 is a diagram showing a schematic configuration of a laser surgical apparatus 1. FIG. 1 is a diagram showing a schematic configuration of a laser unit 10. FIG. 2 is a diagram illustrating a schematic configuration of an amplifying unit 110. FIG. It is a flowchart which shows the process which the laser surgery apparatus 1 performs. It is explanatory drawing for demonstrating an example of the irradiation aspect of the laser pulse to each of three condensing positions SP1-SP3.

  Hereinafter, one exemplary embodiment of the present invention will be described with reference to the drawings. First, a schematic configuration of the laser surgical apparatus 1 according to the present embodiment will be described with reference to FIG. In the following description, the axial direction of the patient's eye E is the Z direction, the horizontal direction is the X direction, and the vertical direction is the Y direction.

<Overall configuration>
The laser surgical apparatus 1 of this embodiment is used for treating a patient's transparent tissue. In the present embodiment, an ophthalmic laser surgical apparatus 1 capable of treating the cornea and the lens of the patient's eye E is illustrated. The laser surgical apparatus 1 according to the present embodiment includes a laser unit 10, an irradiation unit 30, a position detection unit 55, an observation / photographing unit 60, an operation unit 70, and a control unit 76.

<Laser unit>
The laser unit 10 emits pulsed laser light. In the present embodiment, the pulse laser beam emitted by the laser unit 10 is used to induce plasma in the tissue by nonlinear interaction. Non-linear interaction is one of the interactions caused by light and a substance, and is an effect in which a response that is not proportional to the intensity of light (that is, the density of photons) appears. The laser surgical apparatus 1 according to the present embodiment collects (focuss) pulsed laser light in the transparent tissue of the patient's eye E, thereby absorbing multiphotons at a condensing position (sometimes referred to as “laser spot”). Cause it to occur. The probability that multiphoton absorption occurs is not proportional to the intensity of light and is nonlinear. When an excited state is generated by multiphoton absorption, plasma is generated in the transparent tissue, and the tissue is cut and crushed. The above phenomenon is sometimes referred to as photodisruption. In optical breakdown due to nonlinear interaction, the influence of heat from laser light is unlikely to be applied around the condensing position. Therefore, a fine treatment is possible. As the pulse width of the pulsed laser beam is made as small as possible, photodestruction occurs efficiently with less energy. A detailed configuration of the laser unit 10 will be described later with reference to FIGS. 2 and 3.

<Irradiation unit>
The irradiation unit 30 guides the pulsed laser light emitted by the laser unit 10 to the patient's eye E and focuses it on a three-dimensional target position in the transparent tissue of the patient's eye E. The irradiation unit 30 of the present embodiment includes a mirror 31, a mirror 32, a hall mirror 33, a beam expander unit 34, a scanning unit 40, a lens 50, a lens 51, and a beam in order from the laser unit 10 side to the patient's eye E side. A combiner 52 and an objective lens 53 are provided.

  The mirrors 31 and 32 guide the pulsed laser light emitted by the laser unit 10. The hall mirror 33 aligns the optical axis L1 of the pulsed laser light with the optical axis L2 of the position detection unit 55 (described later). The beam expander unit 34 moves the laser spot in the Z direction (direction along the optical axis L1). The scanning unit 40 moves the laser spot in the XY direction. The lenses 50 and 51 relay pulse laser light. The beam combiner 52 aligns the optical axis L1 of the pulsed laser light with the optical axis L3 of the observation / imaging unit 60 (described later). The objective lens 53 (condensing optical system) condenses the pulsed laser light on the tissue of the eye E.

  The beam expander unit 34 of this embodiment includes a concave lens 36, a convex lens 37, and a drive unit 38. The drive unit 38 moves the concave lens 36 along the optical axis L1. As the concave lens 36 moves, the divergence state of the beam that has passed through the concave lens 36 changes. As a result, the focused position (laser spot) of the pulse laser beam moves in the Z direction.

  The scanning unit 40 of the present embodiment includes an X scanner 41, a Y scanner 44, and lenses 47 and 48. The X scanner 41 scans the pulse laser beam in the X direction by swinging the galvanometer mirror 42 by the drive unit 43. The Y scanner 44 scans the pulse laser beam in the Y direction by swinging the galvanometer mirror 45 by the drive unit 46. The lenses 47 and 48 use two galvanometer mirrors 42 and 45 as pupil conjugates.

  In the present embodiment, the pulsed laser light that has passed through the objective lens 53 is focused on the transparent tissue of the patient's eye E via the eyeball fixing interface 54. Although not shown in detail, the eyeball fixing interface 54 has a suction ring and a cup. A negative pressure is applied to the suction ring by a suction pump or the like. As a result, the anterior segment of the patient's eye E is sucked and fixed by the suction ring. The cup covers the anterior eye area. During the operation, the cup is filled with a liquid having a refractive index similar to that of the tissue of the patient's eye E. Therefore, the refraction of the pulsed laser light by the patient's eye E is weakened, and the accuracy of the light collection position is improved. Needless to say, the configuration of the eyeball fixing interface 54 may be changed as appropriate. For example, a contact lens or the like may be attached to the patient's eye E instead of the liquid interface. Surgery with the laser surgical apparatus 1 can be performed without using the eyeball fixing interface 54.

  In addition, the structure of the irradiation unit 30 can also be changed suitably. For example, the laser surgical apparatus 1 may perform scanning in the X and Y directions of the pulse laser beam using an acousto-optic device (AOM, AOD) or the like that deflects the pulse laser beam instead of the galvanometer mirrors 42 and 45. Scanning in one direction may be performed by a plurality of elements. A resonant scanner, a polygon mirror, or the like may be used. Further, the laser surgical apparatus 1 may change the condensing position of the pulsed laser light in the XY direction by moving the patient's eye E (for example, a bed for supporting the patient) with respect to the laser unit 10. In this case, a configuration for moving the patient's eye E may be included in the irradiation unit 30. Moreover, the specific structure for moving a condensing position to a Z direction can also be changed. For example, the laser surgical apparatus 1 may perform scanning in the Z direction of the condensing position on the downstream side of the optical path from the scanning unit 40. A plurality of configurations for moving the condensing position in the Z direction may be provided.

<Position detection unit>
The position detection unit 55 is used for detecting the position of the patient's eye E with respect to the irradiation unit 30. Specifically, the laser surgical apparatus 1 according to this embodiment detects the position of the patient's eye E with respect to the irradiation unit 30 to associate the position where the pulsed laser light is collected with a tomographic image (details will be described later). By associating the condensing position with the tomographic image, data for controlling the irradiation unit 30 and the like can be set using the tomographic image.

  The position detection unit 55 of the present embodiment is a confocal optical system that shares part of the optical system with the irradiation unit 30. The position detection unit 55 includes a hall mirror 33, a condenser lens 56, an aperture plate 57, and a light receiving element 58. The hall mirror 33 transmits the light incident on the center and reflects the light reflected by the patient's eye E along the optical axis L2. The condensing lens 56 condenses the light reflected by the hall mirror 33 on the opening of the aperture plate 57. The aperture plate 57 is a confocal aperture plate having an aperture at the center. The aperture of the aperture plate 57 is arranged in a conjugate relationship with the focused position (laser spot position) of the pulsed laser light in the patient's eye E. The light receiving element 58 receives light that has passed through the opening of the opening plate 57. When detecting the position of the patient's eye E, the laser surgical apparatus 1 of the present embodiment adjusts the output of the laser light emitted from the laser unit 10 so that the laser light does not cause optical destruction at the condensing position. The laser surgical apparatus 1 receives the reflected light from the patient's eye E by the light receiving element 58 while moving the condensing position in the three-dimensional direction by the irradiation unit 30.

  As described above, the position detection unit 55 of the present embodiment can detect the condensing position of the pulse laser light with high accuracy by using the confocal relationship. In addition, the structure for detecting the position of the patient's eye E with respect to the irradiation unit 30 can be changed as appropriate. For example, the irradiation light and the reflected light may be separated using a polarization beam splitter instead of the hall mirror 33. Further, the laser surgical apparatus 1 may irradiate a sample material or the like with pulsed laser light, and detect an actual condensing position in the sample material or the like from a tomographic image (described later). In this case, the laser surgical apparatus 1 can detect the position of the patient's eye E with respect to the irradiation unit 30 without using the position detection unit 55.

<Observation / Photographing Unit>
The observation / imaging unit 60 allows the operator to observe the patient's eye E and images the tissue to be treated. As an example, the observation / imaging unit 60 of this embodiment includes an OCT unit 61 and a front observation unit 65. The optical axis L3 of the observation / photographing unit 60 is made coaxial with the optical axis L1 of the pulse laser beam by the beam combiner 52. The optical axis L3 is branched by the beam combiner 63 into an optical axis L4 of the OCT unit 61 and an optical axis L5 of the front observation unit 65.

  The OCT unit 61 acquires a tomographic image of the tissue of the eye E using the technique of optical interference. Specifically, the OCT unit 61 of the present embodiment includes a light source, a light splitter, a reference optical system, a scanning unit, and a detector. The light source emits light for acquiring a tomographic image. The light splitter divides the light emitted from the light source into reference light and measurement light. The reference light enters the reference optical system, and the measurement light enters the scanning unit. The reference optical system has a configuration that changes the optical path length difference between the measurement light and the reference light. The scanning unit scans the measurement light in a two-dimensional direction on the tissue. The detector detects an interference state between the measurement light reflected by the tissue and the reference light that has passed through the reference optical system. The laser surgical apparatus 1 scans the measurement light and detects the interference state between the reflected measurement light and the interference light, thereby acquiring information in the depth direction of the tissue. A tomographic image of the tissue is acquired based on the acquired information in the depth direction. The laser surgical apparatus 1 according to the present embodiment associates the position where the pulsed laser beam is focused with a tomographic image of the patient's eye E taken before surgery. As a result, the laser surgical apparatus 1 can create data for controlling the operation of irradiating pulsed laser light (for example, the operation of the drive units 38, 43, and 46) using the tomographic image. Various configurations can be used for the OCT unit 61. For example, any of SS-OCT, SD-OCT, TD-OCT, etc. may be adopted as the OCT unit 61.

  The front observation unit 65 acquires a front image of the patient's eye E. The front observation unit 65 of the present embodiment images the patient's eye E illuminated with visible light or infrared light and displays it on a monitor 72 (described later). The surgeon can observe the patient's eye E from the front by looking at the monitor 72.

<Operation unit>
The operation unit 70 receives input of various operation instructions from the operator. As an example, the operation unit 70 of this embodiment includes an operation unit 71 having various operation buttons and a touch panel provided on the surface of the monitor 72. However, other configurations such as a joystick, a keyboard, and a mouse can be employed as the operation unit 70. The monitor 72 can display various images such as a front image of the patient's eye E, a tissue tomographic image, and various operation menus.

<Control unit>
The control unit 76 includes a CPU 77, a ROM 78, a RAM 79, a nonvolatile memory (not shown), and the like. The CPU 77 manages various controls of the laser surgical apparatus 1. The ROM 78 stores various programs for controlling the operation of the laser surgical apparatus 1, initial values, and the like. The RAM 79 temporarily stores various information. A nonvolatile memory is a non-transitory storage medium that can retain stored contents even when power supply is interrupted.

<Configuration of laser unit>
With reference to FIG. 2 and FIG. 3, the structure of the laser unit 10 in this embodiment is demonstrated in detail. As shown in FIG. 2, the laser unit 10 of this embodiment includes an oscillator 101, an amplification unit 110, a wavelength conversion unit 121, switching units 125 and 126, and a pulse selection unit 128.

  The oscillator 101 can oscillate laser light (including pulsed laser light irradiated with a plurality of laser pulses intermittently and repeatedly). Although details will be described later, in the present embodiment, a plurality of laser pulses in the pulsed laser light emitted by the laser unit are condensed at each of a plurality of condensing positions. Thereby, the laser surgery apparatus 1 can efficiently treat the tissue of the patient's eye E with a simple configuration.

  In this embodiment, an oscillator capable of oscillating pulsed laser light having a repetition frequency of 1 gigahertz or higher is employed. A more desirable repetition frequency range is 3 GHz or more (details will be described later). As an example, a semiconductor laser is employed for the oscillator 101 of the present embodiment. However, it is possible to employ an oscillator (solid laser or the like) other than the semiconductor laser.

  The pulse width (pulse duration) of the pulsed laser light to be oscillated by the oscillator 101 can also be set as appropriate. However, the shorter the pulse width, the easier it is to irradiate the tissue with a laser pulse with less energy and higher peak output. Therefore, the shorter the pulse width, the more efficiently the nonlinear interaction occurs at the condensing position. For example, the pulse width may be set within a range of 1 femtosecond to 100 picoseconds. A more desirable pulse width range is 100 femtoseconds to 100 picoseconds. If the pulse width is 100 femtoseconds or more, laser oscillation and control are easy.

  The wavelength of the pulse laser beam to be oscillated by the oscillator 101 can also be set as appropriate. However, the range of the wavelength of the pulsed laser light applied to the transparent tissue of the patient's eye E is desirably 300 nanometers or more and 2000 nanometers or less. If the wavelength is less than 300 nanometers, single-photon absorption rather than multiphoton absorption is likely to occur, and tissue treatment by nonlinear interaction becomes difficult. In this embodiment, since the pulse width of the pulse laser beam is shorter than that of the conventional treatment method using a sub-nanosecond laser, a pulse laser beam having a longer wavelength than the conventional method (for example, a pulse laser beam having a wavelength of 2000 nanometers). ) Can also cause non-linear interactions. Note that the wavelength of the pulsed laser light to be oscillated by the oscillator 101 is more preferably in the range of 1000 nanometers to 1600 nanometers in consideration of laser oscillation and ease of wavelength conversion. As an example, in this embodiment, the wavelength of the pulsed laser light oscillated by the oscillator 101 is 1064 nanometers.

  The amplifying unit 110 amplifies the output of the pulse laser beam oscillated by the oscillator 101. With reference to FIG. 3, the configuration of the amplifying unit 110 employed in the present embodiment will be described. The laser unit 10 of the present embodiment is a MOPA (Master Oscillator Power Amplifier) type laser unit. An amplification unit 110 illustrated in FIG. 3 is an example of an amplification unit used in the MOPA method. The amplifying unit 110 includes amplifiers 111A, 111B, and 111C, excitation light sources 112A, 112B, and 112C, and magnifying lenses 114A and 114B.

  Each of the amplifiers 111A, 111B, and 111C is a multipath amplifier. Each of the amplifiers 111A, 111B, and 111C includes an amplification medium. As the amplification medium, a medium that matches the wavelength of the seed light oscillated by the oscillator 101 may be used. The excitation light sources 112A, 112B, and 112C are provided corresponding to the amplifiers 111A, 111B, and 111C, respectively. The excitation light sources 112A, 112B, and 112C irradiate the amplification medium included in the corresponding amplifier with excitation light to excite the amplification medium. The amplification medium in the excited state amplifies and emits the incident pulse laser beam. The magnifying lens 114A is provided between the amplifier 111A and the amplifier 111B, and widens the diameter of the pulse laser beam emitted from the amplifier 111A. The magnifying lens 114B is provided between the amplifier 111B and the amplifier 111C, and widens the diameter of the pulse laser beam emitted from the amplifier 111B.

  The configuration of amplification by the MOPA method is simpler than the configuration of amplification used in conventional femtosecond lasers (for example, a configuration such as a chirp pulse amplification method (CPA method)). The reason why the laser surgical apparatus 1 of this embodiment can employ an amplification mechanism with a simple configuration will be described. In a conventional treatment method in which a laser pulse with a pulse width of the order of femtoseconds (hereinafter sometimes referred to as “femtosecond laser”) is irradiated to each condensing position once, a laser unit has a very high peak output. It is necessary to emit a pulse. That is, a conventional apparatus using a femtosecond laser amplifies the peak output of a laser pulse having a very small pulse width compared to an order of picosecond or microsecond to a very high value. In this case, when an amplification mechanism exemplified by MOPA is used, the light intensity may become excessively high due to self-convergence during amplification. As a result, the optical system of the amplifying unit may be damaged. Therefore, in a conventional apparatus using a femtosecond laser, it is necessary to use a more complicated amplification method (for example, CPA method) than an amplification method such as MOPA.

  On the other hand, the laser surgical apparatus 1 of this embodiment treats a tissue by irradiating each focused position with a laser pulse having a lower peak output than a conventional femtosecond laser multiple times. Will be described later). That is, the laser surgical apparatus 1 of this embodiment only needs to amplify the peak output of the pulsed laser light oscillated by the oscillator 101 to an output lower than the peak output of the femtosecond laser in the conventional apparatus. Therefore, the laser surgical apparatus 1 can also employ an amplification mechanism exemplified by MOPA.

  The configuration of the amplifying unit 110 can be changed as appropriate. For example, the amplification unit 110 that can be used in the laser surgical apparatus 1 may be a bulk type, but a plurality of optical fiber amplifiers may be used. The amplification stage may be set as appropriate. An amplification method other than the MOPA method may be used. Further, depending on the peak output required for the treatment, the amplification unit 110 itself can be omitted.

  Returning to the description of FIG. The wavelength converter 121 can convert the wavelength of the pulsed laser light oscillated by the oscillator 101. As an example, the wavelength converter 121 of the present embodiment changes the wavelength (1064 nanometers) of the pulsed laser light oscillated by the oscillator 101 to a wavelength in the range of 300 nanometers to 700 nanometers (354 nanometers in the present embodiment). ). Specifically, the wavelength conversion unit 121 of this embodiment includes a first wavelength conversion crystal 122 and a second wavelength conversion crystal 123. The first wavelength conversion crystal 122 receives a pulsed laser beam having a wavelength of 1064 nanometers and emits a second harmonic (wavelength of 532 nanometers). The second wavelength conversion crystal 123 enters the second harmonic and emits the third harmonic (wavelength 354 nanometers). For the wavelength conversion crystals 122 and 123, a bulk crystal (for example, LBO, BBO) or the like can be used.

  The configuration of the wavelength converter 121 can also be changed. The specific configuration of the wavelength conversion unit 121 may be determined as appropriate based on the wavelength of the pulsed laser light oscillated by the oscillator 101 and the wavelength of the pulsed laser light applied to the tissue of the patient's eye E. For example, the wavelength of the pulsed laser light oscillated by the oscillator 101 can be made shorter than that in the present embodiment, and the wavelength of the pulsed laser light can be converted to a longer wavelength by the wavelength conversion unit. The number of wavelength conversion crystals is not limited to two. Further, a QPM element or the like may be used instead of the bulk crystal. When using a QPM element, it is desirable to select the element in consideration of the spread of the pulse width due to dispersion.

  The switching units 125 and 126 switch whether to perform wavelength conversion of the pulsed laser light by the wavelength conversion unit 121. In other words, the switching units 125 and 126 switch whether to output the wavelength-converted pulsed laser light from the laser unit 10 or to output the wavelength-converted pulsed laser light from the laser unit 10. As an example, in the present embodiment, mirrors capable of inserting and extracting pulsed laser light into the optical path are used as the switching units 125 and 126. The switching units 125 and 126 are inserted into and extracted from the optical paths by an insertion / removal mechanism (not shown). The switching unit 125 is provided upstream of the wavelength conversion unit 121 in the optical path. The switching unit 126 is provided on the downstream side of the optical path from the wavelength conversion unit 121. When the switching units 125 and 126 are both extracted from the optical path, the pulsed laser light travels along the optical path L7. In this case, the pulse laser beam is wavelength-converted by the wavelength converter 121 and then enters the pulse selector 128. On the other hand, when the switching units 125 and 126 are both inserted into the optical path, the pulsed laser light travels along the optical path L8. In this case, the pulse laser beam enters the pulse selection unit 128 without passing through the wavelength conversion unit 121.

  The specific configuration of the switching units 125 and 126 can also be changed. For example, the laser surgical apparatus 1 switches whether or not to perform wavelength conversion by switching the optical path of the pulsed laser light using another configuration (for example, an acoustooptic element, a prism, a MEMS, a semiconductor gate, etc.). Also good. The switching unit may switch whether or not to perform wavelength conversion by switching insertion and extraction of the wavelength conversion unit 121 itself in the optical path of the pulsed laser light. Contrary to this embodiment, the arrangement of the optical system may be designed so that wavelength conversion is performed when the switching units 125 and 126 are inserted in the optical path. In addition, the laser surgical apparatus 1 may use a plurality of wavelength conversion units. Three or more types of laser beams having different wavelengths may be selectively emitted.

  The pulse selection unit 128 selectively distributes a plurality of intermittently incident laser pulses into a laser pulse that causes optical destruction in the tissue and a laser pulse that does not cause optical destruction in the tissue. As an example, the pulse selection unit 128 of the present embodiment includes an acousto-optic element (AOM) and a beam dump. The acousto-optic element can deflect the laser pulse. The pulse selection unit 128 deflects a laser pulse that does not cause optical destruction in the tissue by an acousto-optic element, and enters the beam dump. That is, the pulse selection unit 128 picks a laser pulse that is not used for tissue treatment. The pulse selection unit 128 emits a laser pulse that causes optical destruction in the tissue as it is without being deflected.

  In this embodiment, pulsed laser light is oscillated at a higher repetition frequency than that of a conventional femtosecond laser. Therefore, it is desirable for the laser surgical apparatus 1 to reduce the possibility of light destruction, thermal denaturation, and the like occurring at unscheduled positions while the condensing position is switched to the next target position by the irradiation unit 30. In the laser surgical apparatus 1 according to the present embodiment, a laser pulse that is oscillated while the condensing position is switched is changed by the pulse selection unit 128 to at least a laser pulse that does not cause optical destruction. Specifically, the laser surgical apparatus 1 according to the present embodiment prevents the tissue from being irradiated with the laser pulse while the condensing position is switched to the next target position by the irradiation unit 30 by the acoustooptic device. Thus, the possibility of photodestruction or thermal denaturation at unscheduled positions is further reduced.

  Note that the configuration of the pulse selector 128 can be changed as appropriate. For example, the arrangement position of the pulse selection unit 128 may be changed. Therefore, the pulse selection unit 128 may be disposed outside the laser unit 10. The pulse selection unit 128 may be arranged on the upstream side of the optical path from the wavelength conversion unit 121 (in this case, the position of the pulse selection unit 128 may be on the upstream side or the downstream side of the amplification unit 110). Further, instead of the acoustooptic device, an electrooptic modulator (EOM), an optical fiber switching device, a chopper foil, or the like may be used. In addition, the pulse selection unit 128 exemplified in this embodiment selectively picks a laser pulse. However, the method for obtaining a laser pulse that does not cause optical destruction is not limited to the method of picking a laser pulse. For example, the pulse selection unit 128 may change at least one of parameters (for example, pulse energy) of a laser pulse that is not used for tissue treatment to a value that does not cause photodestruction. In addition, when the energy of each laser pulse is low, the apparatus configuration can be simplified by omitting the pulse selection unit 128 itself.

<Processing during surgery>
With reference to FIG. 4 and FIG. 5, the process at the time of the surgery which the laser surgery apparatus 1 of this embodiment performs is demonstrated. The processing at the time of surgery illustrated in FIG. 4 is executed by the CPU 77 of the control unit 76 when an instruction to perform surgery using pulsed laser light is input via the operation unit 71 or the like. The CPU 77 executes the process shown in FIG. 4 according to the control program stored in the ROM 78 or the nonvolatile memory.

  First, a treatment mode selection instruction is accepted (S1). The treatment mode is a mode for determining the mode of treatment (surgery) of the patient's eye E by the laser surgical apparatus 1. In the present embodiment, two treatment modes (first mode and second mode) are provided. The first mode is a mode for performing a treatment on the first part of the patient's eye E. The second mode is a mode for performing a treatment on a second part of the patient's eye E that is located behind the first part (back side of the eye). As an example, in the present embodiment, the first part is the cornea and the second part is the lens.

  The surgeon inputs an instruction for selecting a desired treatment mode using the operation unit 71 or the like. For example, the CPU 77 may accept a treatment mode selection instruction by displaying buttons such as “corneal treatment mode” and “crystal lens treatment mode” on the monitor 72 and allowing the operator to select a desired button using a touch panel or the like. . Further, the CPU 77 may display the wavelength of the pulsed laser beam in each mode on the monitor 72 as an option.

  The type of treatment mode may be changed. For example, three or more treatment modes may be provided. Other modes such as a treatment mode for performing CCC (Continuous Circular Capsule Hexis) for incising the front surface of the lens capsule and a treatment mode for forming a corneal port may be provided. In the present embodiment, the laser surgical apparatus 1 can perform both CCC and lens nucleus crushing in the second mode. Further, the laser surgical apparatus 1 may be configured to treat only one part in the patient's eye E. In this case, the treatment mode is not necessary.

  Next, it is determined whether or not the selected treatment mode is the first mode (S2). If it is the first mode (S2: YES), the condensing position of the pulse laser light in the cornea of the patient's eye E (in this case, the target position for condensing the pulse laser light) is set (S4). As described above, in the present embodiment, the CPU 77 associates the light collection position with the tomographic image based on the position detected by the position detection unit 55. Therefore, the CPU 77 can set the condensing position by the tomographic image. However, you may change the setting method of a condensing position.

  Next, the CPU 77 sets the output of the pulse laser beam emitted from the laser unit 10 (S5). In the present embodiment, the output p set in S5 is smaller than the output P (described later) set in the second mode. However, the output p does not have to be a fixed value, and may be changed by an operator or the like. Even in this embodiment, at least the initial value of the output p is smaller than the initial value of the output P described later, but the operator can change the output p.

  Next, the CPU 77 sets the wavelength of the pulse laser beam emitted from the laser unit 10 to the first wavelength for treating the cornea (S6). The laser surgical apparatus 1 according to the present embodiment performs wavelength conversion by the wavelength conversion unit 121, thereby setting the wavelength of the pulsed laser light emitted to the tissue to the first wavelength (354 nanometers in the present embodiment).

  If the selected treatment mode is the second mode (S2: NO), the condensing position of the pulsed laser light in the crystalline lens of the patient's eye E (for example, at least one of the lens capsule and the lens nucleus) is set (S8). ). The output of the pulse laser beam is set (S9). The initial value of the output P set in S9 is larger than the initial value of the output p set in the first mode. Note that the output P may be changed by the operator in the same manner as the output p described above. Next, the CPU 77 sets the wavelength of the pulse laser beam emitted from the laser unit 10 to the second wavelength for treating the crystalline lens (S10). The laser unit 10 of the present embodiment emits pulsed laser light without performing wavelength conversion by the wavelength conversion unit 121, thereby setting the wavelength of the pulsed laser light to the second wavelength (1064 nanometers in the present embodiment). .

  Next, it is determined whether or not a pulse laser light irradiation start instruction has been input (S12). When the irradiation start instruction is input by the operation unit 71 or the like (S12: YES), the CPU 77 starts the oscillation of the pulse laser beam by the oscillator 101, and the beam expander unit 34 and the scanning unit according to the set condensing position. 40 (see FIG. 1) is started (S13). That is, the CPU 77 controls the irradiation unit 30 so that the pulse laser beam is condensed at each of the set plurality of condensing positions. Further, the CPU 77 drives the pulse selection unit 128 until the condensing position is switched to the next target position. As a result, the laser pulse oscillated from the oscillator 101 is picked, so that the tissue is not irradiated with the laser pulse. That is, the laser pulse is changed to a laser pulse that does not cause optical destruction in the tissue by the pulse selection unit 128 (S15).

  It is determined whether or not the condensing position has been switched to the next target position by the irradiation unit 30 (S16). If switching has not been completed (S16: NO), pulse picking (S15) is continuously executed. When the switching is completed (S16: YES), the CPU 77 ends the picking and irradiates a single condensing position with a plurality of laser pulses while stopping the scanning. Although details will be described later, in the present embodiment, a time period from the start of irradiation of a laser pulse to one condensing position (target position) to the end of irradiation of a plurality of laser pulses to the condensing position (hereinafter referred to as the following) , Referred to as “total irradiation time”). In the present embodiment, irradiation of a plurality of laser pulses to one condensing position is continuously performed until the total irradiation time has elapsed. Although the total irradiation time can be set as appropriate, it is desirable that the total irradiation time be 300 picoseconds or longer. If the total irradiation time is 300 picoseconds or more, sufficient energy is supplied to the condensing position to generate plasma.

  If the irradiation interval of two laser pulses irradiated continuously and the total irradiation time are found, the number of laser pulses irradiated to one condensing position (hereinafter referred to as “specified number”) is determined. Therefore, the CPU 77 may end the irradiation of the laser pulse to the condensing position on condition that the irradiation of the specified number of laser pulses to one condensing position is completed.

  When irradiation of a plurality of laser pulses to one condensing position is completed (S17), it is determined whether or not irradiation of laser pulses to all target positions is completed (S19). If not completed (S19: NO), the process returns to S15. In this case, the light collection position is switched to the next target position by the irradiation unit 30. During this period, pulse picking (S15) is performed. When the switching of the focusing position is completed (S16: YES), a plurality of laser pulses are irradiated to the switched focusing position (S17). When irradiation of laser pulses to all target positions is completed (S19: YES), the process ends.

  FIG. 5 is a diagram for explaining an example of a mode of laser pulse irradiation to each of the three condensing positions S1, S2, and S3. The laser surgical apparatus 1 of this embodiment irradiates a plurality of laser pulses to each of the condensing positions S1 to S3. The peak output of each laser pulse is a lower peak output than the conventional treatment method using a femtosecond laser (treatment method in which a laser pulse having a pulse width of the order of femtoseconds is irradiated to each condensing position once). .

  For example, if the repetition frequency is 50 gigahertz, the repetition period of the plurality of laser pulses is 20 picoseconds. When this laser pulse is emitted to each of the condensing positions S1 to S3, the laser pulse is continuously irradiated to one condensing position over a total irradiation time of 300 picoseconds. As a result, a treatment method using a sub-nanosecond laser (for example, a laser pulse having a pulse width of 300 picoseconds to 20 nanoseconds is irradiated once on each condensing position with a peak output lower than that of a conventional femtosecond laser. Non-linear interaction similar to treatment method) occurs at the collection position and the tissue is treated.

  In the conventional treatment with the femtosecond laser, it is necessary to amplify the pulsed laser light oscillated by the oscillator 101 in order to obtain a high peak output. When the femtosecond laser is amplified to a high peak output by an amplification mechanism exemplified by MOPA (for example, the amplification unit 110 of the present embodiment), the pulse width of the pulse laser beam is small, and therefore due to self-convergence during amplification, Damage to the optics of the amplification mechanism can occur. Therefore, in the treatment with the conventional femtosecond laser, it is necessary to use an amplification method (for example, CPA method) more complicated than the amplification method such as MOPA. On the other hand, the laser surgical apparatus 1 according to the present embodiment only needs to emit a femtosecond laser having a lower peak output than conventional ones, and thus can amplify the pulsed laser light by a simple amplification method. Depending on various conditions, the amplification mechanism itself may be omitted. There is a possibility that the types of laser light sources that can be employed are increased.

  Further, in the present embodiment, unlike the conventional treatment method using a sub-nanosecond laser, during the period from the start to the end of the irradiation of the laser pulse at one condensing position (that is, during the total irradiation time), Laser light is not always irradiated. As the pulse width of the laser pulse is shortened, a laser pulse having a high peak output is generated with a small amount of energy, and a nonlinear interaction is efficiently generated by the plurality of generated laser pulses. As described above, the laser surgical apparatus 1 according to the present embodiment can efficiently treat a patient's tissue with a simple configuration.

  The laser unit 10 of the present embodiment can emit pulsed laser light whose wavelength is converted by the wavelength converter 121. Therefore, the laser surgical apparatus 1 can irradiate the tissue with pulsed laser light having a wavelength suitable for treatment. Furthermore, the laser surgical apparatus 1 of the present embodiment can selectively emit a plurality of types of pulsed laser beams having different wavelengths to a tissue by controlling the execution of wavelength conversion according to the site to be treated. Therefore, the laser surgical apparatus 1 can perform an appropriate treatment according to the characteristics of the pulsed laser light due to the difference in wavelength.

  Specifically, pulse laser light having a short wavelength (pulse laser light having the first wavelength in this embodiment) is easily absorbed by the transparent tissue, but pulse laser light having a long wavelength (pulse laser having the second wavelength in this embodiment) is used. Compared to light), it is easy to perform fine treatment. On the other hand, pulsed laser light having a long wavelength is difficult to be absorbed by the transparent tissue. The laser surgical apparatus 1 according to the present embodiment treats a laser beam when treating a first part (for example, the cornea) located in front of a second part (for example, a crystalline lens) as compared with treating a second part. Since there is little need to consider absorption, a fine treatment is performed using a pulsed laser beam of the first wavelength. When treating a second part (for example, a crystalline lens), pulse laser light having a second wavelength that is difficult to be absorbed by the tissue is used. Therefore, the laser surgical apparatus 1 can perform an appropriate treatment according to the site of the patient's eye E.

  In the present embodiment, pulsed laser light is oscillated at a higher pulse repetition frequency than in the prior art. When the repetition frequency is high, there is a possibility that photodestruction, thermal denaturation, etc. may occur at an unscheduled position while the irradiation unit 30 switches the light collection position to the next target position. However, the laser surgical apparatus 1 of the present embodiment uses a laser pulse that is oscillated during the switching of the focusing position as a laser pulse that does not cause at least light destruction in the tissue. Specifically, the laser surgical apparatus 1 according to the present embodiment prevents the pulse selection unit 128 from irradiating the tissue with the laser pulse during the switching of the focusing position. Thus, the possibility of photodestruction or thermal denaturation at unscheduled positions is reduced.

  The laser unit 10 of this embodiment can emit pulsed laser light having a wavelength of 300 nanometers or more and 2000 nanometers or less. If the wavelength is less than 300 nanometers, single-photon absorption rather than multiphoton absorption is likely to occur, and tissue treatment by nonlinear interaction becomes difficult. In this embodiment, since the pulse width of the pulse laser beam is shorter than that of the conventional treatment method using a sub-nanosecond laser, a pulse laser beam having a longer wavelength than the conventional method (for example, a pulse laser beam having a wavelength of 2000 nanometers). ) Can also cause non-linear interactions. Therefore, the laser surgical apparatus 1 can appropriately treat the tissue by using pulsed laser light having a wavelength of 300 nanometers or more and 2000 nanometers or less.

  The laser unit 10 emits pulsed laser light having a repetition frequency of 1 gigahertz or higher. It is more desirable to be able to emit pulsed laser light having a repetition frequency of 3 GHz or higher. In this case, even if the total irradiation time is as short as 300 picoseconds, a plurality of laser pulses are irradiated to one condensing position.

  It is desired to treat the cornea as finely as possible. Since the lens nucleus is removed after crushing, it is desirable to crush it efficiently. The laser surgical apparatus 1 according to the present embodiment makes the output of the pulse laser beam for treating the cornea smaller than the output of the pulse laser beam for treating the crystalline lens. As a result, the cornea is finely treated with a small output, and the lens is efficiently treated with a large output.

  Of course, the present invention is not limited to the above-described embodiments, and various modifications are possible. For example, in the above embodiment, the pulse laser beam oscillated by the oscillator 101 is amplified by the MOPA amplification unit 110. That is, the laser surgical apparatus 1 of the above embodiment can amplify the pulse laser beam with a simple configuration. However, it is also possible to use other types of amplifying units. In addition, according to the technique of the present disclosure (a technique of irradiating each focusing position with a laser pulse having a short pulse width a plurality of times), treatment can be performed with pulsed laser light having a lower peak output than conventional femtosecond laser treatment. Done. Therefore, depending on various conditions, the amplification unit itself may be omitted.

  The laser surgical apparatus 1 of the above embodiment can irradiate the tissue with a pulsed laser beam suitable for treatment by mounting the wavelength conversion unit 121. Specifically, the laser surgical apparatus 1 converts the wavelength of the pulsed laser light oscillated by the oscillator 101 into a short wavelength by the wavelength conversion unit 121, so that the pulsed laser light has a wavelength that is easily absorbed by the tissue. However, according to the technique of the present disclosure, multiphoton absorption by a laser pulse occurs efficiently. Therefore, the wavelength conversion unit 121 may be omitted depending on various conditions.

  The laser surgical apparatus 1 of the above embodiment can perform appropriate treatment according to the site by controlling the execution of wavelength conversion according to the site to be treated. However, the laser surgical apparatus 1 can also treat different parts at one wavelength without switching whether or not to perform wavelength conversion. Conversely, three or more types of pulsed laser light may be selectively emitted. Further, the laser surgical apparatus 1 may selectively emit a plurality of pulsed laser beams to a tissue by properly using a plurality of oscillators that can emit different pulsed laser beams.

  In the said embodiment, the case where the cornea and the lens were treated was illustrated and demonstrated. However, it goes without saying that the site to be treated can be appropriately changed. For example, when treating only the cornea, treating only the lens nucleus, treating only the lens capsule, or forming a corneal port around the cornea, at least one of the techniques exemplified in the above embodiment Part can be applied. When treating tissues other than the eyes, the technique exemplified in the above embodiment may be applied.

  At least a part of the technique exemplified in the above embodiment can also be used for retinal photocoagulation treatment, selective laser trabeculoplasty (SLT), and the like. For example, the configuration of the wavelength converter 121 (see FIG. 2) in the above embodiment is changed, and the wavelength (1064 nanometer) of the pulsed laser light oscillated by the oscillator 101 is changed to the second harmonic (wavelength 532 nanometer). By converting, the second harmonic may be used for photocoagulation treatment and SLT. In this case, various parameters such as the output of the laser beam may be appropriately set according to the treatment site, the content of treatment, and the like (not a pulsed laser beam but a continuous wave). Furthermore, the apparatus may be configured such that two or more of a plurality of treatments such as corneal treatment, lens treatment, photocoagulation therapy, and SLT can be performed by one device. For example, a lens treatment mode that uses pulse laser light oscillated by the oscillator 101 without wavelength conversion, a photocoagulation treatment mode that uses a second harmonic, an SLT mode, and a corneal treatment mode that uses a third harmonic Two or more may be selectively performed in one laser treatment apparatus.

  The laser surgical apparatus 1 of the above embodiment changes the output of the pulsed laser light according to the site to be treated. However, it is also possible to perform treatment without changing the output. Further, the laser surgical apparatus 1 may attenuate the output of the pulsed laser light by a filter or the like without changing the output of the oscillator 101 itself. Moreover, the laser surgical apparatus 1 of the said embodiment reduces the possibility that the unintended optical destruction etc. will arise during switching of a condensing position by performing the pulse picking by an acousto-optic device (AOM). However, it is also possible to suppress unintended light destruction and the like by using a configuration other than AOM. For example, the laser surgical apparatus 1 may suppress unintended light destruction and the like by reducing the energy of the pulsed laser light oscillated from the oscillator 101 during the switching of the condensing position. In addition, when the influence of unintended light destruction and thermal denaturation is small, the pulse selection unit 128 can be omitted.

  In the above embodiment, the peak output of the plurality of laser pulses irradiated to the respective condensing positions is substantially constant. As a result, the waveform of the laser beam irradiated to each condensing position (the overall waveform of a plurality of laser pulses) is a rectangular wave. However, the intensity of the laser pulse irradiated to each condensing position can be changed. For example, the intensity may be adjusted so that the peak outputs of the plurality of laser pulses gradually increase or decrease gradually. The intensity may be changed so that the overall waveform of the plurality of laser pulses has a mountain shape. The intensity of the laser beam may be changed in accordance with the characteristics of the tissue irradiated with the laser beam.

DESCRIPTION OF SYMBOLS 1 Laser surgery apparatus 10 Laser unit 30 Irradiation unit 76 Control unit 77 CPU
78 ROM
79 RAM
101 Oscillator 110 Amplifier 121 Wavelength converter 128 Pulse selector

Claims (5)

A laser surgical apparatus capable of treating a tissue by causing a nonlinear interaction to occur at a focused position of the pulsed laser beam in the tissue by focusing the pulsed laser beam on a patient's tissue,
A laser unit having an oscillator for oscillating pulsed laser light;
Scanning means for causing the tissue to scan the condensing position of the pulsed laser light emitted by the laser unit;
Scanning control means for condensing a plurality of laser pulses in the pulsed laser light emitted by the laser unit for each of the plurality of condensing positions by controlling the scanning means ,
The control means irradiates a single converging position with a plurality of laser pulses having a lower output than a femtosecond laser that induces plasma accompanied by plasma emission while stopping scanning by the scanning means. A laser surgical apparatus which performs treatment using a principle of inducing plasma without light emission . The laser surgical apparatus according to claim 1,
The laser unit is
A laser surgical apparatus, which is a MOPA (Master Oscillator Power Amplifier) type laser unit including an amplifying unit for amplifying pulsed laser light oscillated by the oscillator. The laser surgical apparatus according to claim 1 or 2,
The laser unit is
A laser surgical apparatus comprising wavelength conversion means for converting the wavelength of pulsed laser light oscillated by the oscillator. The laser surgical apparatus according to claim 3,
The laser unit is
Further comprising switching means for switching whether to perform wavelength conversion of the pulsed laser light by the wavelength conversion means,
The laser surgical device comprises:
A laser surgical apparatus further comprising control means for controlling execution of wavelength conversion by the switching means in accordance with a part to be treated with pulsed laser light. The laser surgical apparatus according to any one of claims 1 to 4,
A laser pulse oscillated by the oscillator during the time when the position of condensing the laser pulse is switched to another target position by the scanning means after the condensing of the plurality of laser pulses to one condensing position is completed. Further comprising pulse selection means for making a laser pulse that does not cause optical destruction in the tissue.