JP2007159740A - Laser treatment apparatus for ophthalmology - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser treatment apparatus for ophthalmology which reduces energy density at a translucent body and expands application range of a set spot size when using a wide field contact lens. <P>SOLUTION: The laser treatment apparatus for ophthalmology includes a fiber for introducing light from a laser source, and a parfocal light guiding optical system for irradiation with a laser beam emitted from the fiber onto the fundus and having a variable power optical system for changing the power of the spot size of the laser beam. The laser treatment apparatus for ophthalmology further includes an NA adjustable optical system which can adjust a fiber emission NA to an optical path located on the laser source side near an incident end surface of the fiber in at least two stages, an input means for inputting a signal for setting spot size whose power is changed by the variable power optical system, and a control means which controls driving of the NA adjustable optical system on the basis of the spot size setting signal and switches the fiber emission NA to a fiber emission NA that avoids eclipse of laser beam on the optical path of the light guiding optical system. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ophthalmic laser treatment apparatus for guiding and irradiating laser light to a patient's eye.

  It has a light guide optical system that guides the laser light from the laser light source through a fiber and guides the laser light emitted from the fiber to the fundus of the patient's eye through a variable magnification optical system (zoom optical system). 2. Description of the Related Art A laser treatment apparatus for photocoagulation using a perfocal (confocal) type that forms a fiber exit end face image on an affected part is known as an optical optical system. In this type of apparatus, the coagulation spot size of the laser beam by the variable magnification optical system is appropriately selected from 50 to 1000 μm to perform photocoagulation of the fundus. The coagulation spot size is set based on the air. For the spot size (beam diameter) on the fundus, a contact-type negative contact lens (for example, a Goldman-type three-mirror lens having a magnification of about 1.08) is generally used so as to cancel the refractive power of the eyeball. In this case, it is almost the same as the set spot size.

  When the spot size at the time of photocoagulation is small, a laser beam is sufficiently large in a translucent body such as a cornea or a crystalline lens, and an energy density in the translucent body is low. On the other hand, as the spot size is increased, the laser light flux on the transparent body is reduced, and the energy density is increased. As a method of reducing the energy density in the cornea, the crystalline lens, etc., an optical element having a focal length as short as possible is arranged in the light guiding optical system after the fiber exit end, and the near-field imaging position with respect to the fiber exit end is determined. A method of reducing the distance from the far field image forming position (hereinafter referred to as the Sp value) is known (for example, Patent Documents 1 and 2).

For fundus photocoagulation, in addition to a contact negative contact lens, a wide-field inverted image contact lens (contact positive contact lens) as shown in Non-Patent Document 1 below is used. In general, it is known that the beam diameter on the translucent body is preferably larger than the spot size on the fundus (for example, Non-Patent Document 2).
Masahiro Ikeda, “Retinal Photocoagulation Using Quadrashperic Lens”, Ophthalmic Practice 3 Practice of Laser Treatment, 1st Edition, January 1, 1993, Bunkodo, P55 David Dewy, Corneal and retinal energy density with various laser beam delibery systems and contact lenses, SPIE, Vol. 1423, Ophthalmic Technologies, 1991, P105-116 JP-A-6-294939 JP-A-9-145999

  By the way, as in Non-Patent Document 1, when a double-field wide-angle inverted image contact lens is used, the spot size on the fundus is about twice as large as the spot size set by the variable magnification optical system. When a large solidification size is used, the energy density in the translucent body becomes high due to the characteristics of the condensing system of the contact lens. This tendency becomes remarkable especially in the case of a perfocal type apparatus. For this reason, the set spot size is supposed to be about 200 μm (about 400 μm at the fundus), and the application range of the spot size when using a wide-field inverted image contact lens is limited.

  To solve this problem, a method of reducing the Sp value when a large spot size is used as described above and widening the beam diameter of the light transmitting body can be considered. There is a limit to making it smaller. In order to make the Sp value smaller, the focal length of the lens arranged in the light guide optical system after the emission from the fiber has to be shortened. For this purpose, it is necessary to use a lens having a very small lens diameter. It is difficult to manufacture a lens with a short focal length, and when a lens with a short focal length is used, it is more difficult to adjust the alignment of the light guide optical system. Further, when the Sp value is decreased, the irradiation spot is likely to be distorted due to the distortion of the optical system.

  The present invention can reduce the energy density in the cornea, the crystalline lens, and the like in view of the problems of the prior art, and can expand the application range of the spot size set when using a wide-field inverted image contact lens. An object of the present invention is to provide an ophthalmic laser treatment apparatus.

In order to solve the above problems, the present invention is characterized by having the following configuration.
(1) A fiber that guides laser light from a laser light source, and a perfocal light guide optical system that irradiates the fundus with laser light emitted from the fiber. In an ophthalmic laser treatment apparatus including a light guide optical system having a variable magnification optical system for changing magnification, an NA variable optical system that changes a fiber emission NA from an incident end of the fiber to an optical path on the laser light source side in at least two stages; Input means for inputting a setting signal for a spot size to be changed by the variable magnification optical system, and driving of the NA variable optical system based on the inputted setting signal for the spot size, Control means for switching to a fiber emission NA that avoids vignetting of the laser beam in the optical path.
(2) The control means of (1) increases the fiber emission NA based on the relationship between the scaling of the spot size and the range in which the vignetting of the laser light in the optical path of the light guide optical system is avoided. The NA variable optical system is driven and controlled.
(3) In the ophthalmic laser treatment apparatus according to (1) or (2), the variable magnification optical system is an optical system capable of changing a spot size by at least 50 to 500 μm, and the NA variable optical system is configured to change the spot size. It has an optical system capable of enlarging at least twice as much as the fiber emission NA applied when the thickness is 50 μm.

  ADVANTAGE OF THE INVENTION According to this invention, the energy density in a cornea, a crystalline lens, etc. can be reduced more, and the application range of the spot size set when using a wide field inverted image contact lens can be expanded.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an external view of an ophthalmic laser treatment apparatus that performs photocoagulation of a patient's eye. Reference numeral 1 denotes an apparatus main body, in which a therapeutic laser light source used for photocoagulation, a light source used for aiming light, and an optical system for causing the aiming light and therapeutic laser light to enter the optical fiber 2 are housed.

  Reference numeral 3 denotes a control unit that performs laser irradiation conditions such as laser output and irradiation time, and necessary settings of the apparatus. Reference numeral 4 denotes a slit lamp delivery for irradiating the affected part of the patient's eye with the laser light while observing the patient's eye, the laser irradiating part 5 for irradiating the laser light guided to the optical fiber 2, and the illuminating part for illuminating the patient's eye with a slit. 6. A binocular microscope unit 4a is provided. Reference numeral 8 denotes a foot switch for sending a laser irradiation trigger signal.

  The laser irradiation unit 5 is provided with a spot diameter adjusting knob 5a for changing the diameter (magnification) of a spot image of the laser light (image of the end face of the optical fiber) formed on the fundus of the patient's eye. By using the spot diameter adjusting knob 5a, the spot diameter of the laser beam can be changed from 50 μm to 1000 μm.

  FIG. 2 is a schematic diagram illustrating the optical system of the present embodiment. The laser light from the laser light source 10 is condensed on the incident end face of the fiber 2 by the condenser lens 12 and enters the fiber 2. A dichroic mirror 11 is disposed between the condenser lens 12 and the laser light source 10, and visible laser light emitted from the aiming light source 15 passes through the collimator lens 16 and is then emitted from the laser light source 10 by the dichroic mirror 11. It is made coaxial with the laser beam. Reference numeral 60 denotes a drive unit, and 61 denotes a glass plate (NA variable optical system) attached to the drive unit 60. A control unit 70 is connected to the control unit 3. The drive unit 60 is connected to the control unit 70 and operates the drive unit 60 based on a command signal from the control unit 70. At this time, the control unit 70 issues a command based on the setting in the control unit 3 or the spot size setting signal by the spot diameter adjusting knob 5a. The drive unit 60, the glass plate 61, and the control unit 70 constitute a control means for controlling the NA variable optical system. The drive unit 60 moves the glass plate 61 in the direction of the arrow to insert / remove the glass plate 61 between the laser light source 10 and the condenser lens 12 and vary the incident NA of the laser light to the fiber 2. When the glass plate 61 is inserted into the optical path, the fiber incident NA increases, and when the glass plate 61 is removed from the optical path, the fiber incident NA decreases (returns to the original). Details of these operations and principles will be described later. The treatment laser light source 10 used in the present embodiment uses an Nd: YAG laser that oscillates a fundamental wave of 1064 nm and obtains green light that is a double wave (532 nm linearly polarized light). The aiming light source 15 uses a semiconductor laser emitting red light of 635 nm.

  Laser light from the laser light source 10 is guided to the laser irradiation unit 5 by the optical fiber 2. The energy distribution of the laser light emitted from the emission end face 2 a of the optical fiber 2 is made substantially uniform by using the optical fiber 2. The laser irradiation unit 5 includes an irradiation optical system 20 for guiding the laser light emitted from the optical fiber 2 to a target (the fundus of the patient's eye E, iris, etc.). The irradiation optical system 20 includes a condenser lens 21, a lens 23, zoom lenses 22 and 24 as a variable power optical system, and a movable mirror 26 for changing the laser beam emission direction. The zoom lenses 22 and 24 are spot diameter adjusting knobs. By using 5a, it moves on the optical axis L and changes the imaging magnification (spot size) of the laser light. In the variable power optical system for photocoagulation, it is preferable that the spot size can be changed at least between 50 and 500 μm. The set value of the spot size by the spot diameter adjusting knob 5 a is detected by the potentiometer 25, and the spot size setting signal is input to the control unit 70. A series of input means is formed by the knob 5 a, the potentiometer 25, and the control unit 70. The control unit 70 and the control unit 3 also serve as input means. The laser beam reflected by the movable mirror 26 is applied to the fundus of the patient's eye E through the contact lens 35. Since the magnification of the fundus and the like varies depending on what is selected for the contact lens 35, the spot size on the fundus is obtained by multiplying the set spot size on the apparatus body 1 by the magnification of the contact lens 35. The movable mirror 26 is moved by a manipulator (not shown) to change the irradiation position of the laser beam.

  An illumination light source 40 is disposed in the illumination unit 6, and illumination light from the illumination light source 40 passes through the condenser lens 41, the slit 42, and the projection lens 43, and then is reflected by the split mirrors 45 a and 45 b to illuminate the patient's eye E. . A correction lens 44 corrects the optical path length of the illumination light reflected by the split mirror. The binocular microscope unit 4 a includes an objective lens 50, a variable magnification optical system 51, a protective filter 52, an erecting prism group 53, a field stop 54, and an eyepiece lens 55.

  The principle and operation of the laser treatment apparatus having the above configuration will be described. 3 and 4 are schematic diagrams (ray diagrams) of the light guide optical system disposed in the laser irradiation unit 5. FIG. The fiber output NA (numerical aperture) at this time is 0.08. FIG. 3 shows a case where the spot size is relatively small (50 μm), and FIG. 4 shows a case where the spot size is relatively large (200 μm). FIG. 3A is a diagram showing the on-axis light beam L1, and FIG. 3B is a diagram showing the off-axis light beam L2. FIG. 4A is a diagram illustrating the on-axis light beam L3, and FIG. 4B is a diagram illustrating the off-axis light beam L4. Each lens in FIG. 3 schematically shows the lens in FIG. 2, and the role thereof is the same. The size of the lens shown here is deformed for simplicity.

  The laser beam emitted from the emission end face 2 a of the fiber 2 is collected by the condenser lens 21 and passes through the zoom lens 22, the lens 23, and the zoom lens 24. The laser light is reflected by the movable mirror 26 and is irradiated onto the fundus through the contact lens 35 that is in contact with the patient's eye E. When the zoom lenses 22 and 24 move in conjunction with each other, the spot size of the laser beam is changed. In FIG. 3, for ease of explanation, the movable mirror 26 is indicated by a dotted line, and is a linear ray diagram without reflection by the mirror. Further, illustration and refraction of the contact lens 35 and the patient E are omitted. Here, an irradiation surface F corresponding to the fundus of the patient's eye E is used.

  In FIG. 3, the spot lens on the irradiation surface F is reduced by moving the smooth lens 22 toward the emission end surface 2 a and moving the zoom lens 24 toward the target surface F (fundus). The on-axis light beam L1 in FIG. 3A is emitted from the center of the optical axis of the emission end face 2a, and is guided to the irradiation surface F coaxially with the optical axis L of the light guide optical system. The axial light beam L1 is focused on the central portion S1 of the spot S on the irradiation surface F. The off-axis light beam L2 in FIG. 3B is emitted from the off-axis of the emission end face 2a and is guided to the irradiation surface F. The off-axis light beam L2 is condensed on the peripheral portion S2 of the spot S on the irradiation surface F. Since the emission end face 2a is conjugate with the irradiation face F, the light beam emitted from the emission end face 2a is condensed at a position corresponding to each of the emission faces F. In addition, a light beam emitted from the emission end face 2a in parallel to the optical axis of the light beam L2 (a central light beam of the light beam L2: a principal light beam) is projected on the far field imaging plane N away from the irradiation surface F by a distance Sp. Interact with. Similarly, the light beam emitted from the emission end face 2a in parallel with the optical axis is collected on the imaging plane N.

  In this way, the image of the emission end face 2a is formed on the irradiation surface F as a spot S having a small size. The irradiation surface F is a near-field imaging surface of the fiber exit end surface 2a. Further, the light rays emitted in parallel from the emission end face 2a are imaged on the imaging plane N which is a far field imaging plane.

  In FIG. 4, the spot size on the irradiation surface F is increased by moving the smooth lens 22 toward the irradiation surface F and moving the zoom lens 24 toward the emission end surface 2a. As in the case of FIG. 3, the irradiation light from the center of the emission end face 2 a becomes an axial light beam L <b> 3 and is guided to the center S <b> 1 of the spot S on the irradiation surface F. Further, the irradiation light from the off-axis of the emission end face 2a becomes an off-axis light beam L4 and is guided to the peripheral portion S2 of the spot S on the irradiation surface F.

  In this way, a large-sized spot S is formed on the irradiation surface F. The irradiation surface F is conjugate with the emission end surface 2a and is a near-field imaging surface of the fiber emission end surface 2a. The intersection of the principal ray of the off-axis light beam L4 and the optical axis L becomes the far-field imaging surface of the fiber exit end face 2a.

  M in FIG. 4B is a part of the principal ray of the outermost off-axis light beam when the lens 21 is assumed to be small in the optical system of FIG. The distance between the point where the principal ray M intersects the optical axis L and the center point of the irradiation surface F is the Sp value at this time, Sp2. As shown in the drawing, even when the spot S has the same size, when the off-axis principal ray is incident on the irradiation surface F from the outside with respect to the optical axis L, the beam diameter at the translucent body T increases. . Accordingly, the energy density of the laser light on the translucent body T is also reduced. Thus, when the spot size set with respect to the irradiation surface F is large, it turns out that the energy density in the transparent body T can be reduced if Sp value is made small. Therefore, when the spot size of the irradiation laser light is large, the light flux before the irradiation surface F (translucent body T) becomes thin, and therefore it is preferable that the Sp value is as small as possible. That is, it is preferable that the light flux in the transparent body T is wide. Such a tendency generally occurs in other than the illustrated optical system.

  Comparing the behavior of the light flux at each spot S formed in FIGS. 3 and 4, there is a difference in the light flux diameter on the near side from the irradiation surface F, that is, on the translucent body T such as the cornea and the crystalline lens. When the spot S on the fundus is small, the light flux on the translucent body T is thick, and when the spot S is large, the light flux on the translucent body T is thin. The energy density of the laser light in the translucent body T increases as it is thinner than when the luminous flux is thick. At this time, if there is any turbidity or the like in the translucent body T, the laser light is absorbed there, and there is a possibility that the translucent tissue is thermally damaged.

  Therefore, as a design of a light guide optical system in which the light beam diameter at the translucent body T does not become thin even if the spot size is large, a method for reducing the distance (Sp value) between the near-field imaging plane and the far-field imaging plane as much as possible. There is. In this case, the focal lengths of the condenser lens 21 and the zoom lens 22 are changed to short ones. However, if the focal length of the lens is shortened, the lens diameter itself becomes small, which causes manufacturing difficulties. Further, since the refractive index of the lenses 21 and 22 is increased, the laser light emitted from the fiber 2 is deviated from the optical axis only by a slight deviation of the central axis. For this reason, it takes time to perform the shaft alignment operation. In addition, since the lenses 21 and 22 become small, the energy density of the laser light on the lens and in the lens increases, and the possibility that the lenses 21 and 22 are damaged increases. As described above, the design for reducing the Sp value of the light guide optical system is not simple and has limitations.

  As a countermeasure for this, a method of widening the output NA of the fiber 2 is conceivable in order to increase the diameter of the light flux in the translucent body T. For example, when the emission NA at the emission end face 2a is changed from 0.08 to 0.16, the laser beam such as an on-axis beam or an off-axis beam is approximately doubled. FIG. 5 is a ray diagram when NA is 0.16 with respect to FIG. 4 (spot size = 200 μm). As shown in the drawing, the NA of the outgoing end face 2a of the on-axis light beam L3 and the off-axis light beam L4 is widened. The light beam diameter at the translucent body T is also wider than NA 0.08 (in the case of FIG. 3). For this reason, the energy density in the translucent body T is reduced. At this time, the Sp values shown in FIGS. 4B and 5B are not changed. That is, the energy density in the transparent body T is reduced without changing the Sp value.

  However, if the enlargement of the fiber emission NA is fixed even when the spot size is small, the laser beam becomes thick, and the laser beam is vignetted by the mirror 26 and the lenses 23 and 24 so that an efficient laser beam is applied to the patient's eye. I can't irradiate. FIG. 6 is a ray diagram when NA is set to 0.16 with respect to the case where the spot size of FIG. 3 is small. As shown in the figure, the NA of the outgoing end face 2a of the on-axis light beam L1 and the off-axis light beam L2 is widened. At this time, in the lens 23, the zoom lens 24, and the movable mirror 26, the laser light emitted from the emission end face 2a is vignetted, and the irradiation surface F is not irradiated with laser light having sufficient energy intensity. As described above, when the output NA of the fiber 2 is widened, when the spot size is large, the energy density in the translucent body T is reduced, but when the spot size is small, vignetting occurs in the light guide optical system. . In order to eliminate this vignetting, it is necessary to enlarge the lens 23, the zoom lens 24, and the movable mirror 26. However, if the lenses 23 and 24 are enlarged, the slit lamp delivery itself is increased. Further, when the movable mirror 26 is enlarged, the visual field of the operator is narrowed. This is a portion where the observation optical system and the light guide optical system in FIG. 1 are coaxial, and the movable mirror 26 is placed between the right eye and the left eye of the binocular observation optical system. by. Therefore, it is not easy to make the movable mirror 26 larger than a certain size.

  Therefore, when the spot size that can be changed by the variable magnification optical system is a small spot, the outgoing NA of the fiber 2 is reduced to eliminate the vignetting of the light beam from the fiber 2 by the light guide optical system later. On the other hand, when the spot is changed to a large spot, the output NA of the fiber 2 is widened, and the energy density in the translucent body T is reduced.

  FIG. 7 is a diagram for explaining means for varying the NA of the laser beam before entering the fiber 2. FIG. 7A shows the case where the incident NA is 0.08, and FIG. 7B shows the case where the incident NA is 0.16. In FIG. 7A, the laser light emitted from the laser light source 10 is collected by the condenser lens 12 and is incident on the fiber 2. In FIG. 7B, the control unit 70 that has received the NA change signal by setting the spot size operates the drive unit 60 and inserts the glass plate 61 between the laser light source 10 and the condenser lens 12. Since the glass plate 61 is inclined with respect to the central optical axis of the laser light emitted from the laser light source 10, the laser light transmitted through the glass plate 61 is refracted (lateral deviation occurs). Further, since the glass plate 61 has a thickness enough to decenter the laser beam from the central optical axis, here 1.6 mm, the laser beam incident on the condenser lens 12 with respect to the case of FIG. The optical axis can be shifted. The laser beam shifted laterally with respect to the optical axis by the glass plate 61 is incident on the fiber 2 by the condenser lens 12. At this time, since the laser light incident on the fiber 2 passes through the peripheral side of the condenser lens 12, the incident angle (incident NA) on the fiber 2 becomes larger than when the glass plate 61 is not provided. As a result, the exit angle (exit NA) at the exit end face 2a of the fiber 2 also increases. The outgoing NA at this time corresponds to the incoming NA. In other words, when the incident NA is 0.08, the output NA is approximately 0.08, and when the incident NA is 0.16, the output NA is approximately 0.16. In this manner, the output NA of the fiber can be switched by operating the control unit 3. When switching the fiber incident NA (fiber exit NA) in two steps as in the example of FIG. 7, it is preferable to switch the incident NA with a spot size that does not cause vignetting of the laser beam. For example, the incident NA is widened with a spot size of 100 μm or more.

  Such switching of NA will be described below. The surgeon adjusts the spot diameter adjusting knob 5a to select a desired spot size. The zoom lenses 22 and 24 are moved according to the selected spot size. At this time, a spot size setting signal is input from the potentiometer 25 to the controller 70. The controller 70 determines whether or not to insert the glass plate 61 into the optical path in accordance with the spot size setting signal. For example, when the spot size is less than 100 μm, the glass plate 61 is left removed from the optical path. When the spot size is 100 μm or more, the glass plate 61 is inserted into the optical path and the fiber output NA is changed to 0.16. Thereby, laser irradiation with reduced energy density in the cornea and the crystalline lens can be performed without changing the light guide optical system (particularly the Sp value) and avoiding vignetting of the laser light in the light guide optical system.

  In the embodiment described above, the tilted glass plate 61 is driven so as to cross the optical path, and is inserted / removed. However, the present invention is not limited to this. A method using rotational driving may be used. For example, it is good also as a structure which makes a perforated part two places in a disk etc. made from metal, attaches a glass plate only to one side, and makes it rotate with an angle with respect to an optical axis. Moreover, it is good also as a structure which opens a hole in a glass plate and rotates a glass plate situation.

  In FIG. 7, the fiber output NA is switched in two stages. However, in order to reduce the energy density in the cornea or the like when the spot is large, the structure can be switched in more stages (for example, the glass plate 61). Prepare a material with a different thickness, change the angle of the glass plate, etc.), and the larger the spot, the larger the fiber exit NA. More preferably, it may be continuously variable. A modification example of the NA variable optical system will be described with reference to FIG.

  As shown in FIG. 8A, the lens unit may be inserted into and removed from the optical path. For example, a unit in which the concave lens 80 and the convex lens 81 are combined so as to be coaxial may be formed between the laser light source 10 and the condenser lens 12, and may be inserted and removed. In this case, the light beam may be expanded by the concave lens 80 and the light beam up to the condenser lens 12 by the convex lens 81 may be a substantially parallel light beam. Further, the fiber incident NA may be changed by moving either the condenser lens 12 or the lenses 80 and 81 inserted on the optical path in the optical axis direction. In this way, the fiber incident NA can be continuously changed.

  Moreover, as shown in FIG.8 (b), the structure which makes the unit which combined the convex lenses 82 and 83, and inserts / removes may be sufficient. In this case, the convex lenses 82 and 83 may be driven separately to control the cases of passing through the central axis and the periphery of the convex lenses 82 and 83 so that the fiber incident angle is variable.

  Moreover, the method using only a glass plate or a lens may not be used. For example, as shown in FIG. 8C, a half-wave plate 84 is placed on the laser light source side, a PBS 85 is placed on the condenser lens side, and light is emitted to the peripheral side of the condenser lens 12 depending on the polarization direction of the laser light. It is good also as a structure which guides. The PBS 85 is an abbreviation for a polarization beam splitter, and has a property of allowing P-polarized light to pass through but reflecting S-polarized light. The PBS 85 is configured by bonding a mirror to a beam splitter having different reflection characteristics depending on the polarization direction. The half-wave plate 84 is driven and controlled, and the polarization direction of the laser light guided to the PBS 85 is switched. If the laser light incident on the PBS 85 is P-polarized light, it is passed and guided to the condenser lens 12 on the optical axis. If the laser light incident on the PBS 85 is S-polarized light, it is guided to the periphery of the condenser lens 12. In this manner, the incident NA may be switched by switching the polarization direction of the laser light by controlling the half-wave plate.

  Further, for example, as shown in FIG. 8D, the rhomboid prism 86 may be moved on the optical path of the laser light source 10 and the condenser lens 12. Since the prism 85 can move the optical axis in parallel by passing incident light as it is at the center and reflecting it at the periphery, the optical axis of the laser light can be shifted as the prism 86 moves. it can. Therefore, the incident NA to the fiber 2 can be changed by moving the rhomboid prism 86.

  Next, the setting of the spot size of the irradiation laser beam when a wide-field inverted image lens is used as the contact lens 35 will be described. FIG. 9 is a schematic diagram showing a state where the wide-field inverted image lens 100 is applied to the patient's eye E. 110 indicates the fundus of the patient's eye, 111 is the cornea, and 112 is the crystalline lens. Reference numeral 113 denotes an iris. Reference numeral 101 denotes a cover for the wide-field inverted image lens 100, and lenses 102 and 103 are attached to the cover 100. With these lenses 102 and 103, the fundus 110 is magnified about twice. The surgeon holds the lens 100 and presses the cornea 111 of the patient's eye E to hold the patient's eye E and irradiate the laser beam. The lens 100 has a structure in which the luminous flux of the incident laser light becomes the smallest around the iris 113 in order to widely observe and illuminate the fundus 110. For this reason, the spot size in a translucent body such as the cornea 111 and the crystalline lens 112 becomes small, and the spot size of the laser light irradiated to the fundus cannot be made too large.

  Therefore, to what extent the spot size of the irradiation laser beam can be enlarged during the photocoagulation using the wide-field inverted image lens 100 in the above-described embodiment of the present invention will be described. First, the change in the beam diameter at the translucent material when the fiber output NA is changed will be described with reference to FIG. FIG. 10 shows the result of calculating the beam diameter on the transparent body when the NA of the irradiation laser light is changed in five stages. Here, the beam diameter when the wide-field inverted image lens 100 is used is calculated. In FIG. 10, NA is changed by 0.08 from NA 0.08 to NA 0.4. 10A and 10B, the horizontal axis represents the spot size of the irradiated laser beam on the fundus. Here, since the wide field inverted image lens 100 of about twice is used, the spot size on the fundus is about twice the spot size set in the apparatus main body 1. The vertical axis in FIGS. 10A and 10B represents the beam diameter on each light transmitting body. 10A is a graph of the beam diameter on the cornea, and FIG. 10B is a graph of the beam diameter on the crystalline lens.

  As shown in FIGS. 10 (a) and 10 (b), it can be seen that as the spot size of the irradiated laser beam increases, the beam diameter of each light transmitting body tends to decrease. The lines “on the cornea = on the retina” and “on the lens = on the retina” in the figure indicate the part where the beam diameter on the translucent body is the same as the spot size on the fundus. This line is a standard that is generally said, and is also described in Japanese Patent Document 2 mentioned above. As shown in the figure, as the NA increases, the light flux (beam diameter) in each light transmitting body tends to increase. As the beam diameter increases, the energy density on the translucent body decreases. That is, in the case of NA 0.08, the applicable spot size on the fundus was up to about 400 μm (at most 500 μm, and the set spot size is 200 to 250 μm), but in the case of a double NA of 0.16, 600 μm ( It can be applied up to 300 μm at the set spot size, and can be applied up to about 700 μm (350 μm at the set spot size) when NA is 0.24. Further, when the NA is 4 times as large as 0.32, it can be applied up to 800 μm (400 μm at the set spot size), and when NA is 0.4 times as large as 900 μm (450 μm at the set spot size).

  However, there is a limit in increasing NA due to the size problem of the movable mirror 26 of the light guide optical system. FIG. 11 is a diagram showing the relationship between the spot size of the irradiated laser beam and the beam diameter at the position of the movable mirror 26 when the NA is changed. The vertical axis in FIG. 11 represents the beam diameter of the irradiation laser beam, and the horizontal axis represents the radius of the light beam at the position of the movable mirror 26. Also in FIG. 11, the NA is changed in five steps as in FIG. A horizontal line on the horizontal axis in FIG. 11 indicates the limit size of the movable mirror 26. For example, if the limit size of the movable mirror 26 is 20 mm, the line indicating this limit is 10 mm. If this line is exceeded, the laser beam will be vignetted. As shown in the figure, the set spot size that can be applied increases as the NA increases. That is, in the case of NA 0.08, the minimum 50 μm (100 μm at the fundus) can be covered, but at a double NA0.16, 100 μm (200 μm at the fundus) can be applied, and NA0.24 is 150 μm (fundus) 300 μm) or more is applicable, NA0.32 is applicable to 200 μm (400 μm at the fundus), and NA0.4 is 250 μm (500 μm at the fundus) or more. The correspondence between the NA and the spot size described here relates to the optical system of the present embodiment, and the correspondence between the NA and the spot size is somewhat different in other optical systems.

  As described above, the fiber emission NA needs to be changed in relation to the light guiding optical system after the fiber, in particular, the range in which the laser beam is prevented from being vignetted by the movable mirror 26. As shown in FIG. 7, in a two-stage switching configuration of NA 0.8 and NA 0.16, NA is set to NA 0.08 up to a set spot size of 50 μm to 100 μm (100 to 200 μm on the fundus), and 100 μm (fundus) At 200 μm or more, switch to NA 0.16. Further, in a three-stage switching configuration in which NA 0.24 is added, when the set spot size is 150 μm (300 μm at the fundus) or more, switching is performed to NA 0.32. Similarly, in a four-step switching configuration in which NA 0.32 is further added, switching to NA 0.24 is performed when the set spot size is 200 μm or more (400 μm at the fundus). Further, in the five-stage switching configuration in which NA 0.4 is added, when the set spot size is 250 μm (500 μm at the fundus) or more, the switching is performed to NA 0.4. In the configuration in which the NA is continuously variable, the switching step can be further reduced. The relationship between the change in the spot size and the range in which the vignetting of the laser light in the optical path of the light guide optical system is avoided may be stored in advance in a memory included in the control unit 70.

  Based on the correspondence between the spot size and the NA, when the operator selects a desired spot size with the spot diameter adjusting knob 5a as in the above-described embodiment, the setting signal is input to the control unit 70. A suitable NA is switched accordingly. The definition of the relationship between the spot size and the NA here depends on the size of the movable mirror 26, the design of delivery, and the like.

  In the above embodiment, the spot size setting signal is automatically input to the control unit 70 by the operation of the spot diameter adjusting knob 5a. However, the spot size selection signal is output by the switch provided on the operation panel 3. An input configuration may be used. In this case, the potentiometer 25 and its communication cable arranged on the laser irradiation unit 5 side can be omitted.

It is an external view of the ophthalmic laser treatment apparatus. It is a schematic diagram explaining the optical system of this embodiment. It is a schematic diagram (light ray diagram) of the light guide optical system arrange | positioned at the laser irradiation part 5 in case a spot size is comparatively small. It is a schematic diagram (light ray diagram) of the light guide optical system arrange | positioned at the laser irradiation part 5 in case a spot size is comparatively large. FIG. 5 is a ray diagram when NA is 0.16 with respect to FIG. 4 (spot size = 200 μm). FIG. 4 is a ray diagram when NA is 0.16 with respect to the small spot size of FIG. 3. It is a figure explaining the means to vary NA of a laser beam before incidence of fiber 2. FIG. It is a figure explaining the modification example of NA variable optical system. 4 is a schematic diagram showing a state where the wide-field inverted image lens 100 is applied to a patient's eye E. FIG. It is the figure which showed the result of having calculated the beam diameter on the translucent body at the time of changing NA of irradiation laser light in five steps. It is a figure which shows the relationship between the spot size of the irradiation laser beam when NA is changed, and the light beam diameter in the movable mirror 26 position.

Explanation of symbols

2 Optical fiber 2a Fiber exit end surface 3 Control unit 4 Slit lamp delivery 5a Spot diameter adjustment knob 10 Laser light source 12 Condensing lens 20 Irradiation optical system 25 Potentiometer 26 Movable mirror 60 Drive unit 61 Glass plate 100 Wide field inversion image lens

Claims (3)

A fiber that guides laser light from a laser light source and a perfocal light guide optical system that irradiates the fundus with laser light emitted from the fiber, and changes the spot size of the laser light irradiated to the affected area. In an ophthalmic laser treatment apparatus including a light guide optical system having a variable power optical system, an NA variable optical system that changes a fiber emission NA from an incident end of the fiber to an optical path on the laser light source side in at least two stages, and the variable power An input means for inputting a setting signal for a spot size to be scaled by the optical system, and driving of the NA variable optical system based on the inputted setting signal for the spot size, and controlling the optical path of the light guiding optical system An ophthalmic laser treatment apparatus comprising: control means for switching to a fiber emission NA that avoids vignetting of laser light. According to a first aspect of the present invention, the control means may change the NA so as to increase the fiber emission NA based on the relationship between the scaling of the spot size and the range in which the vignetting of the laser light in the optical path of the light guide optical system is avoided. An ophthalmic laser treatment apparatus characterized by drivingly controlling an optical system. 3. The ophthalmic laser treatment apparatus according to claim 1, wherein the variable magnification optical system is an optical system capable of changing a spot size at least from 50 to 500 μm, and the NA variable optical system is configured to have a spot size of 50 μm. An ophthalmic laser treatment apparatus having an optical system that can expand at least twice as much as a fiber emission NA to be applied.

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