JP2013116382A - Ophthalmologic imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ophthalmologic imaging apparatus capable of obtaining a desired tomographic image from an ocular fundus image.SOLUTION: The ophthalmologic imaging apparatus includes an interference optical system that has a light splitting means for splitting light from a light source to a measuring light path and a reference light path, a scanning unit for scanning the measuring light irradiated on the ocular fundus, and a light receiving element for detecting the composed light of fundus reflected light by the measuring light and light from the reference light path; an observation image acquiring means for controlling the scanning unit to two-dimensionally scan the measuring light, and acquiring an OCT front image which is the front image of the ocular fundus based on an output signal from the light receiving element; an acquiring position setting means for displaying the OCT front image on a display, and setting the acquiring position of the tomographic image of the ocular fundus on the OCT front image; and a tomographic image acquiring means for controlling the scanning unit based on the acquiring position set by the acquiring position setting means, and acquiring the tomographic image of the ocular fundus corresponding to the acquiring position based on the output signal from the light receiving element. The tomographic image and the OCT front image are acquired using the interference optical system.

Description

The present invention relates to an ophthalmologic imaging apparatus that can obtain a tomographic image of the fundus of a subject's eye non-invasively .

  An optical tomography (OCT) using low coherent light is known as an ophthalmologic imaging apparatus that can obtain a tomographic image of the fundus of the eye to be examined non-invasively. Such an ophthalmologic photographing apparatus can obtain a retinal tomographic image by changing the optical path length while one-dimensionally scanning the fundus with measurement light.

Further, in Patent Document 1, a combined ophthalmology in which an OCT optical system that acquires a tomographic image of the fundus of the subject's eye as described above and an optical system of a fundus camera that performs color imaging of the fundus of the subject's eye is combined. An imaging device has been proposed.
JP-A-10-33484

  In such a composite imaging apparatus in which an OCT optical system and a fundus camera optical system are combined, a frontal fundus image of the eye to be examined is acquired using a fundus camera optical system, and a cross-sectional image (tomographic image) of the fundus is obtained. ) Can be obtained using an OCT optical system. However, the images obtained by these optical systems are acquired independently, and it is difficult to determine which part of the color fundus image is taken by the cross-sectional image.

In view of the above problems, an object of the present invention is to provide an ophthalmologic photographing apparatus that can obtain a desired tomographic image from a fundus image .

  In order to solve the above problems, the present invention is characterized by having the following configuration.

(1)
Light splitting means for splitting light from the OCT light source into a measurement optical path and a reference optical path, a scanning unit for scanning measurement light irradiated on the fundus of the eye to be examined through the measurement optical path, and the measurement light from the measurement optical path A light receiving element for detecting the combined light of the fundus reflected light by the light and the light from the reference optical path, and an interference optical system,
An observation image acquiring means for controlling the scanning unit to scan the measurement light two-dimensionally and acquiring an OCT front image that is a front image of the fundus of the eye based on an output signal from the light receiving element;
An acquisition position setting means for displaying the OCT front image on a display and setting an acquisition position of a tomographic image of the fundus to be examined on the OCT front image;
Tomographic image acquisition that controls the scanning unit based on the acquisition position set by the acquisition position setting means and obtains a tomographic image of the fundus oculi corresponding to the acquisition position based on an output signal from the light receiving element. Means,
The tomographic image and the OCT front image are acquired using the interference optical system.
(2)
The interference optical system receives a spectrum of light obtained by combining the fundus reflection light by the measurement light and the light from the reference optical path, and performs a Fourier transform on the spectrum to obtain a tomographic image of the eye fundus to be examined. A spectrodomain OCT optical system for obtaining the ophthalmic imaging apparatus according to (1).
(3)
The ophthalmologic photographing apparatus according to any one of (1) to (2), further comprising visible fundus image acquisition means for obtaining a visible fundus image of the fundus to be examined by visible light.
(4)
The visible fundus image of the subject's fundus acquired by the visible fundus image acquisition unit and the tomographic image acquired by the tomographic image acquisition unit are displayed on the display, and the tomographic image in the visible fundus image (3) The ophthalmologic photographing apparatus according to (3), further comprising display control means for combining and displaying the acquired position on the visible fundus image.
(5)
The ophthalmic imaging apparatus according to any one of (3) to (4), further comprising an image processing unit that associates the OCT front image with the visible fundus image.

According to the present invention, a desired tomographic image can be obtained from a fundus image.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating an optical system and a control system of the ophthalmologic photographing apparatus according to the present embodiment. In this embodiment, the depth direction of the eye to be examined is the Z direction (optical axis L1 direction), the horizontal component on the plane perpendicular to the depth direction (the same plane as the face of the subject) is the X direction, and the vertical direction. The component is described as the Y direction.

  In FIG. 1, the optical system uses an interference optical system (hereinafter referred to as an OCT optical system) 200 for non-invasively obtaining a tomographic image of the fundus of the eye to be examined using an optical interference technique, and infrared light. A scanning laser ophthalmoscope (SLO) optical system 300 that acquires a fundus SLO image for illuminating and observing the fundus of the subject's eye, and illumination optics for performing color imaging (for example, a non-mydriatic state) of the fundus of the subject's eye And a fundus camera optical system 100 that obtains a color fundus image using a system and a photographing optical system. In the present embodiment, the OCT optical system 200 is synchronized with the scanning unit that scans the measurement light two-dimensionally on the fundus and the scanning of the measurement light by the scanning unit to obtain an interference signal in the depth direction of the eye to be examined. And an optical path length changing unit that changes the optical path length of the reference light. The fundus camera optical system 100 includes an illumination optical system 100a and a photographing optical system 100b.

  The illumination optical system 100a includes a photographing light source 1 such as a flash lamp, a condenser lens 2, a ring slit 3 having a ring-shaped opening, a mirror 4, a relay lens 5, a black spot plate 6 having a black spot at the center, a relay lens 8, and a hole. A perforated mirror 9 and an objective lens 10 are provided. The ring slit 3 is disposed at a position conjugate with the pupil of the eye E to be examined, and illuminates the fundus of the eye to be examined by entering fundus illumination light from the periphery of the pupil. The black spot plate 6 removes the reflected light from the objective lens 10.

  The photographing optical system 100b includes an objective lens 10, a photographing aperture 12 located in the vicinity of the aperture of the perforated mirror 9, a focusing lens 13 movable in the optical axis direction, an imaging lens 14, and two for photographing having sensitivity in the visible range. A two-dimensional image sensor 16 is arranged. The imaging aperture 12 is disposed at a position substantially conjugate with the pupil of the eye E with respect to the objective lens 10.

  The luminous flux emitted from the photographing illumination light source 1 illuminates the ring slit 3 via the condenser lens 2. The light transmitted through the ring slit 3 reaches the perforated mirror 9 through the mirror 4, the lens 5, the black spot plate 6, and the lens 8. The light reflected by the perforated mirror 9 is once converged in the vicinity of the pupil of the eye E by the objective lens 10, and then diffused to illuminate the fundus of the eye to be examined.

  The reflected light from the fundus illuminated with the imaging illumination light forms an image on the image sensor 16 through the objective lens 10, the aperture of the perforated mirror 9, the imaging aperture 12, the focusing lens 13, and the imaging lens 14.

  An imaging signal output from the two-dimensional imaging device 16 is input to the control unit 70. Then, the control unit 70 stores the fundus image captured by the image sensor 16 in the memory 72. The control unit 70 is connected to the display monitor 75 and controls the display image. The control unit 70 is connected to a measurement start switch 74a, a measurement position setting switch 74b, a photographing start switch 74c, an autocoherence switch 74d, and the like.

  Further, between the objective lens 10 and the perforated mirror 9, a dichroic mirror 40 is disposed so that the optical axis L1 of the fundus camera optical system 100 and the optical axis L2 of the OCT optical system 200 are coaxial. . The dichroic mirror 40 has a characteristic of reflecting measurement light for tomographic acquisition used in the OCT optical system 200 (in this embodiment, a wavelength of 815 nm to 865 nm) and transmitting other light.

  The configuration of the OCT optical system 200 provided on the reflection side of the dichroic mirror 40 will be described below. Reference numeral 27 denotes an OCT light source that emits low-coherent light used as measurement light and reference light of the OCT optical system 200. For example, an SLD light source is used. For the OCT light source 27, for example, a light source having a center wavelength of 840 nm and a bandwidth of 50 nm is used. Reference numeral 26 denotes a fiber coupler that doubles as a light splitting member and a light coupling member. The light emitted from the OCT light source 27 is split into reference light and measurement light by the fiber coupler 26 via an optical fiber 38a as a light guide. Therefore, the measurement light is directed to the eye E through the optical fiber 38b, and the reference light is directed to the reference mirror unit 31 through the optical fiber 38c.

  In the optical path for emitting the measurement light toward the eye E, the end 39b of the optical fiber 38b for emitting the measurement light, the relay lens 24 movable in the optical axis direction according to the refractive error of the eye to be examined, and the galvano drive mechanism A relay unit 22 and a scanning unit 23 including a pair of galvanometer mirrors that can scan the measurement light in the XY directions on the fundus at high speed by driving 51 are disposed. Further, the dichroic mirror 40 and the objective lens 10 have a role as a light guide optical system that guides OCT measurement light from the OCT optical system 200 to the fundus of the eye to be examined. Note that the end 39b of the optical fiber 38b is disposed so as to be conjugate with the fundus of the eye to be examined. Further, the reflection surface of the galvanometer mirror of the scanning unit 23 is arranged at a position conjugate with the eye pupil to be examined (in this embodiment, the middle position of the pair of galvanometer mirrors and the eye pupil to be examined are arranged in a conjugate relationship). Have been).

  The measurement light emitted from the end 39b of the optical fiber 38b reaches the galvanometer mirror of the scanning unit 23 via the relay lens 24, and the reflection direction is changed by driving the pair of galvanometer mirrors. Then, the measurement light reflected by the galvanometer mirror is reflected by the dichroic mirror 40 via the relay lens 22 and then condensed on the fundus of the eye to be examined via the objective lens 10.

  Then, the measurement light reflected from the fundus is reflected by the dichroic mirror 40 through the objective lens 10, travels toward the OCT optical system 200, passes through the relay lens 22, the galvano mirror of the scanning unit 23, and the relay lens 24. The light enters the end portion 39b of the fiber 38b. The measurement light incident on the end 39b reaches the fiber coupler 34 via the optical fiber 38b, the fiber coupler 26, and the optical fiber 38d.

  On the other hand, the end 39c of the optical fiber 38c that emits the reference light, the collimator lens 29, the reference mirror unit 31, the condensing lens 32, and the reference light enter the optical path that emits the reference light toward the reference mirror unit 31. An end 39e of the optical fiber 38e is disposed. The reference mirror unit 31 is configured to be movable in the optical axis direction by the reference mirror driving mechanism 50 in order to change the optical path length of the reference light. The reference mirror unit 31 includes a mirror 31a and a mirror 31b.

  The reference light emitted from the end portion 39c of the optical fiber 38c is converted into a parallel light flux by the collimator lens 29, reflected by the mirror 31a and the mirror 31b constituting the reference mirror unit 31, and then condensed by the condenser lens 32. The light enters the end 39e of the fiber 38e. The reference light incident on the end 39e reaches the fiber coupler 34 via the optical fiber 38e.

  Here, the measurement light is reflected by each layer of the fundus oculi, becomes reflected measurement light having a time delay and a different intensity, and is merged with the reference light by the fiber coupler 34. By utilizing the interference phenomenon that occurs when the optical path lengths of the two lights become equal, the light-receiving element 35 detects the intensity of the reflected measurement light, and the reference mirror unit 31 is moved (scanned) in the optical axis direction. The reflection intensity distribution in the optical axis direction (depth direction of the eye to be examined) can be obtained (in this embodiment, the optical path length of the reference mirror unit is changed at one point on the fundus in the optical axis direction. A method for obtaining the reflection intensity distribution is called A-scan). Furthermore, a tomographic image on the XZ plane or YZ plane of the fundus of the eye to be examined can be acquired by scanning the measurement light on the fundus in the X direction or the Y direction by the scanning unit 23 (in this embodiment, in this way, (The B-scan is a method in which the measurement light is scanned one-dimensionally with respect to the fundus and the optical path length due to movement of the reference mirror unit in the optical axis direction is changed to obtain a retinal tomographic image). Furthermore, it is also possible to obtain a fundus image (XY plane) two-dimensionally by scanning the measurement light two-dimensionally in the XY direction with the reference mirror unit 31 fixed (in the present embodiment, (The C-scan is a method in which the measurement light is scanned two-dimensionally with respect to the fundus and an OCT image is obtained two-dimensionally by the interference signal obtained when the optical path of the reference mirror coincides with the coherence length). Furthermore, using these, it is possible to acquire three-dimensional OCT image information based on an interference signal obtained in synchronization with scanning of the measurement light by the scanning unit. In this case, three-dimensional OCT image information of the fundus can be acquired by moving the reference mirror unit 31 in the optical axis direction and scanning the measurement light two-dimensionally with respect to the fundus by the scanning unit 23.

  Note that the A-scan signal is measured from the front in the optical axis direction, and a position where a strong signal can be obtained first from a position where there is no signal is information on the fundus surface layer (retina surface). Therefore, the surface of the fundus is two-dimensionally connected by first connecting the reflection intensities of strong signals for the A scan signals at each measurement position (imaging position) on the fundus when the measurement light is scanned in two axes. The fundus surface OCT image (en-face image) expressed in In addition, since the tomographic image acquired by the B scan is constructed by uniaxial scanning of the A scan signal, a partial image signal of the fundus surface OCT image and the fundus surface layer part of the acquired tomographic image By obtaining the position to be compared with the image signal, it is possible to accurately detect the position of the tomographic image on the fundus surface OCT image.

  Hereinafter, the SLO optical system 300 will be described. In the present embodiment, the OCT light source 27 is also used as the light source of the SLO optical system, and a half mirror 60 is provided between the relay lens 24 and the end portion 39b of the optical fiber 38b, and the confocal optical system extends in the reflection direction of the half mirror 60. , A confocal aperture 62 conjugated to the fundus, and a light receiving element 63 for SLO are provided. In the SLO optical system 300, the optical path from the half mirror 60 to the eye E is shared with the OCT optical system 200. The galvanometer mirror is also used as the OCT optical system 200 in order to scan light used for the SLO optical system in the XY directions on the fundus. In this case, the fundus SLO image can be acquired by two-dimensionally scanning the measurement light in the XY directions by the scanning unit 23.

  The operation of the apparatus having the above configuration will be described. First, the examiner aligns the measurement optical axis at the center of the pupil on the screen imaged by the anterior eye observation camera (not shown), causes the subject to gaze at the movable fixation lamp (not shown), and Guide to the desired measurement site. FIG. 2 shows a fundus observation image acquired by the SLO optical system 300 displayed on the screen of the display monitor 75. When the examiner focuses on the fundus based on the SLO image on the display monitor 75 and then presses the autocoherence switch 74d, the reference mirror unit 31 is automatically moved until the OCT signal is detected.

  Next, the process proceeds to a step for acquiring a tomographic image. In the present embodiment, a case where a tomographic image of the XZ plane is acquired by B scan will be described.

  First, the examiner sets the position of the tomographic image that the examiner wants to photograph from the SLO image on the display monitor 75 observed in real time. The examiner operates the measurement position setting switch 74b to move the line L1 representing the measurement position (acquisition position) in the X direction electrically displayed on the SLO image on the screen with respect to the SLO fundus image. Then, the measurement position in the X direction is set. If the line L1 is set to be in the X direction, a tomographic image on the XZ plane is taken. If the line L1 is set to be in the Y direction, a tomographic image on the YZ plane is taken. It has become. Further, the line L1 may be set to an arbitrary shape (for example, an oblique direction or a circle).

  In addition, the examiner sets the measurement position in the Z direction as well as the measurement position in the XY direction on the fundus. In the Z direction, the scanning width (for example, 3 mm) of the measuring light in the Z direction and the number of scanning steps (the number of measured sheets in the Z direction) are set. For example, if the scanning width is 3 mm and the number of scanning steps is set to 10 μm, a tomographic image having a depth of 3 mm and a 10 μm step is obtained. Note that the longer the scanning width and the smaller the number of scanning steps, the longer the time required for taking a tomographic image.

  Thereafter, when the examiner inputs the measurement start switch 74a, the control unit 70 starts an XZ-plane tomographic image capturing operation by B-scan based on the set measurement position. That is, the control unit 70 drives the scanning unit 23 to measure the measurement light so that a tomographic image of the fundus at the position of the line L1 is obtained based on the display position of the line L1 set on the SLO image on the screen. To scan. Since the relationship between the display position of the line L1 (coordinate position on the monitor) and the scanning position of the measurement light by the scanning unit 23 is determined in advance, the control unit 70 performs scanning corresponding to the set display position of the line L1. The pair of galvanometer mirrors of the scanning unit 23 is appropriately driven and controlled so that the measurement light is scanned with respect to the range. Further, the control unit 70 stores the SLO image at the start of tomographic acquisition in the image memory 72.

  The control unit 70 drives the galvano drive mechanism 51 to control the reflection surface of the galvanometer mirror of the scanning unit 23 to scan the irradiation position of the measurement light in the X direction, and also drives the reference mirror drive mechanism 50 to obtain a predetermined value. The reference mirror unit 31 is moved in the optical axis direction so as to obtain an image with the number of scanning steps.

  In this way, the light receiving element 35 sequentially detects the interference light by combining the reference light and the reflected measurement light from the fundus, and the control unit 70 acquires the reflection intensity distribution in the X direction of the measurement light in the optical path length. To do. Furthermore, when the reference mirror unit 31 moves in the optical axis direction, the control unit 70 acquires a reflection intensity distribution in the XZ direction. In this way, the measurement ends when the optical path length of the reference light reaches the preset scanning width of the measuring light in the Z direction. Then, the control unit 70 constructs a tomographic image in the XZ direction by well-known image processing based on the obtained reflection intensity distribution in the XZ direction, and then displays the tomographic image on the XZ plane on the monitor 75. FIG. 3 is an example of a tomographic image displayed on the monitor 75.

  When a tomographic image of a desired measurement position is displayed on the monitor 75, the process proceeds to a step of acquiring a color fundus image by the fundus camera optical system 100. The examiner performs fine adjustment of alignment and focus so that the user can take a picture in a desired state while viewing the SLO image displayed on the monitor 75. When the examiner inputs the photographing start switch 73c, photographing is performed. The control unit 70 drives the insertion / removal mechanism 45 based on the trigger signal for starting shooting by the shooting start switch 73c, thereby detaching the dichroic mirror 40 from the optical path and causing the shooting light source 1 to emit light.

  The fundus is illuminated with visible light by the light emitted from the imaging light source 1, and the reflected light from the fundus occupies the objective lens 10, the aperture of the perforated mirror 9, the imaging aperture 12, the focusing lens 13, the imaging lens 14, and the dichroic mirror 15. Then, an image is formed on the two-dimensional image sensor 16. Then, the control unit 70 stores the fundus image (see FIG. 4) captured by the two-dimensional image sensor 16 in the image memory 72.

  When the acquisition of the color fundus image is completed, the control unit 70 obtains the feature points of the fundus SLO image stored in the image memory 72 at the start of tomographic acquisition and the color fundus image acquired thereafter by image processing. By performing matching processing for matching, the positional relationship between the fundus SLO image and the color fundus image is made to correspond (see FIG. 5). Then, using the result of the matching process, the control unit 70 associates the position coordinates of the predetermined part on the fundus SLO image with the position coordinates of the same predetermined part on the color fundus image. That is, it is obtained to which position on the color fundus image the predetermined position coordinate on the SLO image corresponds, and, for example, the predetermined part A on the SLO image is displayed on the color fundus image. You can see which position corresponds to above.

  When information regarding the correspondence between the fundus SLO image and the color fundus image is obtained in this way, the control unit 70 performs measurement on the SLO image based on the display position of the line L1 when the measurement position is set. The position (the part where the tomographic image is taken) is specified. Then, the control unit 70 specifies the measurement position on the color fundus image (the part where the tomographic image is captured) based on the information regarding the correspondence obtained as described above. Then, the control unit 70 displays a color fundus image on the display monitor 75 and electrically displays a line L2 indicating a measurement (acquisition) position at which the tomographic image is acquired on the color fundus image based on the specified measurement position information. Display (see FIG. 6).

  In this way, the examiner can confirm the measurement position on the fundus corresponding to the desired fundus tomographic image acquired by the B scan on the color fundus image. Therefore, the examiner can accurately grasp the correspondence between the color fundus image and the tomographic image, which is excellent in resolution and contrast and is suitable for finding the lesion from the entire fundus. Can be done.

  As a technique for performing matching processing by image processing, feature points of the entire image may be extracted as described above, or feature points such as blood vessel shape and optic disc in the fundus image are extracted, and these The matching processing of both images may be performed after extracting the feature points.

  In the above embodiment, line setting for tomographic image acquisition is performed from the fundus SLO image. However, the present invention is not limited to this, and observation for illuminating and observing the fundus of the eye to be examined using infrared light. What is necessary is just to perform based on the observation image obtained using the optical system. For example, an infrared fundus image obtained by illuminating the entire fundus of the subject's eye with infrared light and photographing reflected light from the fundus with a two-dimensional imaging device, or using the OCT optical system 200 and the observation optical system together. The fundus OCT image obtained as described above may be used as a fundus observation image.

  Hereinafter, a case where the measurement position that the examiner wants to acquire is set from the color fundus image using the correspondence relationship that can be obtained as described above will be described. In this case, a color fundus image is acquired in the previous stage of acquiring a tomographic image. Then, in order to display the tomographic image at the desired fundus position on the display monitor 75, the control unit 70 displays the color fundus image on the display monitor 75 and obtains the tomographic image on the color fundus image (acquisition). The line L3 for setting the position is electrically displayed (see FIG. 7).

  Next, the examiner sets the position of the tomographic image that the examiner wants to acquire from the acquired color fundus image. For example, the examiner operates the measurement position setting switch 74b to move the line L3 representing the measurement (acquisition) position in the X direction displayed on the color fundus image on the screen with respect to the color fundus image. The measurement position in the X direction is set (see FIG. 7). At this time, the control unit 70 acquires the fundus SLO image in real time and displays the SLO image as a moving image on the display monitor 75.

  Here, when the examiner inputs the measurement start switch 74a, the control unit 70 obtains a correspondence relationship between the fundus SLO image acquired by the SLO optical system 300 and the color fundus image. Then, the control unit 70 specifies the measurement position on the fundus SLO image based on the display position of the line L3 when the measurement position is set and the information regarding the obtained correspondence relationship. And the control part 70 starts the drive of the galvanometer mirror of the scanning part 23 so that measurement light may be irradiated to the specified measurement position. Thus, the XZ plane tomographic image acquisition operation by the B scan is performed based on the measurement position set on the color fundus image. Please refer to the above description for the operation when acquiring tomographic images.

  When the measurement is completed as described above, a tomographic image is displayed on the monitor 75. In this way, the tomographic image acquisition position can be set based on a color fundus image that has excellent resolution and contrast and is suitable for finding a lesion from the entire fundus, which is useful for the subject. It is possible to make a simple diagnosis.

  Hereinafter, as a second embodiment, an example in which an optical system for infrared fundus observation is provided in the fundus camera optical system 100 and line setting is directly performed on an infrared fundus image captured using observation illumination light will be described. explain. FIG. 8 is a diagram illustrating an optical system and a control system of the ophthalmologic photographing apparatus according to the second embodiment. Unless otherwise specified, the components with the same numbers as those in FIG. 1 are assumed to have the same configuration. In FIG. 8, the fundus camera optical system 100 includes an illumination optical system for photographing fundus and a photographing optical system in addition to an illumination optical system and photographing optical system for photographing the fundus in color. The observation illumination optical system includes a light source 11 such as a halogen lamp, an infrared filter 12 having a characteristic of cutting light having a wavelength of 815 nm to 865 nm and transmitting only light having a wavelength of 700 to 815 nm and a wavelength longer than 865 nm, and a condenser lens. 13. An optical system from condenser lens 2 to objective lens 10 is provided. The observation imaging optical system shares the objective lens 10 to the imaging lens 14 with the color imaging imaging optical system, reflects a part of infrared light and visible light, and transmits most of the visible light. And an observation two-dimensional imaging element 17 having sensitivity in the infrared region in the optical path in the reflection direction of the dichroic mirror 15. Further, the optical path correction glass 41 is disposed on the image pickup device 16 side of the dichroic mirror 40 so that the optical path correction glass 41 can be flipped up by driving the insertion / removal mechanism 45. When the optical path is inserted, the position of the optical axis L1 shifted by the dichroic mirror 40 It has a role to correct.

The light beam emitted from the light source 11 is converted into an infrared light beam by the infrared filter 12 and illuminates the ring slit 3 through the lens 13 and the condenser lens 2. Thereafter, the fundus of the eye to be examined is illuminated through the same optical path as that of the imaging illumination light beam. Reflected light from the fundus illuminated by the illumination light for observation is the objective lens 10, the dichroic mirror 40, the correction glass 41, the aperture of the perforated mirror 9, the photographing aperture 12, the focusing lens 13, the imaging lens 14, and the dichroic mirror. The image is formed on the observation two-dimensional image sensor 17 via 15. The infrared image picked up by the image pickup device 17 is displayed on the display monitor 75 through the control unit 70 in the same manner as the aforementioned SLO image. The reflected light from the fundus illuminated by the imaging illumination light source 1 passes through the dichroic mirror 15 through the optical path from the objective lens 10 to the imaging lens 14 in the same manner as the observation illumination light beam, and then the image sensor 16. To form an image.

  In the second embodiment, the dichroic mirror 40 has a characteristic of reflecting most of the OCT measurement light and transmitting a part of the OCT measurement light, and a part of the OCT measurement light is incident on the observation imaging device 17. ing. Accordingly, the examiner can visually confirm the measurement light line scanned on the fundus from the infrared fundus image displayed on the display monitor 75. Here, for example, the control unit 70 operates the reflection surface of the galvanometer mirror for scanning the measurement light in the X direction, and fixes the angle of the reflection surface of the other galvanometer mirror so that the examiner can The measurement light that scans the fundus in the X direction can be visually observed.

  Here, when the examiner focuses on the fundus based on the infrared fundus image on the display monitor 75 and then presses the autocoherence switch 74d, the reference mirror unit 31 is automatically moved until the OCT signal is detected. Moved.

  Next, the examiner sets the measurement position by moving the measurement light scanned in the X direction up and down with respect to the infrared fundus image by operating the measurement position setting switch 74b while viewing the display monitor 75. At this time, the control unit 70 operates the reflecting surface of the galvanometer mirror for scanning the measurement light in the Y direction based on the operation signal from the measurement (acquisition) position setting switch 74b to measure the measurement light on the eye fundus. The scanning position is moved up and down. That is, when the measurement position is set, the measurement light that scans the fundus is visually observed to have the same role as the line L1 in the first embodiment.

  Thereafter, when the examiner inputs the measurement start switch 74a, the control unit 70 starts an operation of acquiring a tomographic image of the XZ plane by the B scan based on the scanning position of the measurement light at the input time of the start switch 74a. To do. In this case, since the OCT measurement light has already started scanning in the X direction, the optical path length may be changed by moving the reference mirror unit 31 in the optical axis direction. At this time, the control unit 70 stores the infrared fundus image at the start of tomographic acquisition in the image memory 72. In this way, when acquisition of the tomographic image is completed, a color fundus image is acquired as described above.

  When the acquisition of the tomographic image and the acquisition of the color fundus image is completed in this way, the control unit 70 displays the infrared fundus image stored in the image memory 72 at the start of the tomographic acquisition and the color fundus acquired thereafter. By performing a matching process for matching the feature points of the image with the image, the positional relationship between the infrared fundus image and the color fundus image is made to correspond. Then, using the result of the matching process, the control unit 70 associates the position coordinates of the predetermined portion on the fundus infrared image with the position coordinates of the same predetermined portion on the color fundus image.

  Next, the control unit 70 extracts an image signal of the measurement light portion that scans the infrared fundus image by image processing (for example, a linear image signal having a luminance level within a certain range is extracted from the entire fundus image. This may be extracted) and synthesized at a coordinate position corresponding to the same position on the color fundus image. Then, the control unit 70 displays the tomographic image and the color fundus image acquired on the display monitor 75, and synthesizes the image of the OCT measurement light portion extracted from the infrared fundus image as described above on the color fundus image. Display (see FIG. 9). In this way, the examiner can confirm the measurement position corresponding to the acquired fundus tomographic image based on the position of the measurement light synthesized and displayed on the color fundus image. In this case, the coordinate position of the image signal of the measurement light portion that scans the infrared fundus image is specified, and a line indicating the measurement (acquisition) position at which the tomographic image is acquired based on the specified coordinate position is electrically displayed. You may make it make it.

  In the above description, TD-OCT (time domain OCT) having a configuration for acquiring an optical coherence tomographic image by moving the reference mirror unit 31 on the optical axis and changing the optical path length is used. The present invention is not limited to this, and a tomographic image may be acquired by other measurement principles. For example, SD-OCT (spectral domain OCT) using Fourier transform may be used. The configuration of SD-OCT will be briefly described with reference to FIG. Since the configuration other than the portion described below can be the same as the configuration of the OCT optical system 200 shown in FIG. In this case, the control unit 70 moves the reference mirror unit 31 in the optical axis direction at the time of alignment for detecting the OCT signal, but the reference mirror unit 31 is fixed at the time of tomographic image acquisition. To do. Then, the control unit 70 converts the interference signal obtained by the fiber coupler 34 into parallel light by the collimator lens 80, separates it into light beams for each wavelength by the diffraction grating 81, and condenses the light on the one-dimensional light receiving element 83 by the condenser lens 82. Let Thereby, a spectrum interference fringe (power spectrum) is recorded on the one-dimensional light receiving element 83. A Fourier transform relationship exists between the power spectrum and the correlation function. Therefore, the spectral interference fringe measured by the one-dimensional light receiving element 83 is Fourier-transformed to obtain a cross-correlation function between the measurement light and the reference light, which becomes an OCT signal. As a result, the shape of the measured object in the depth direction can be measured.

  In the above description, the position of a desired tomographic image is set from the fundus image, and the OCT optical system 200 is operated based on the set position to capture a tomographic image. is not. That is, the three-dimensional OCT image information acquired in advance by the OCT optical system 200 may be associated with the color fundus image. In this case, the control unit 70 performs processing for acquiring a tomographic image corresponding to the set measurement position from the three-dimensional OCT image information. That is, in the present embodiment, tomographic image acquisition means tomographic image acquisition after acquisition position setting and to acquire a predetermined tomographic image from previously acquired three-dimensional OCT image information.

  Here, in order to confirm the acquisition position of the tomographic image acquired by setting the measurement position on the fundus observation image on the color fundus image, for example, the control unit 70 acquires a three-dimensional OCT image acquired in advance. An image signal used as an OCT observation image is acquired from the information, and the acquired image signal is displayed on the OCT observation image together with a measurement position setting line for the examiner to set a measurement position. Thereby, the examiner can set the measurement position from the OCT observation image. When the measurement position is set, the control unit 70 acquires a tomographic image corresponding to the set measurement position from the three-dimensional OCT image and displays it on the display monitor 75. In addition, the control unit 70 obtains a correspondence between the above-described OCT observation image and the color fundus image, and relates to the display position of the line on the OCT observation image when the measurement position is set and the obtained correspondence. A line indicating the acquisition position of the tomographic image is displayed on the color fundus image based on the information.

  In order to set the measurement position that the examiner wants to obtain from the color fundus image, for example, the control unit 70 obtains a correspondence between the color fundus image and the three-dimensional OCT image information, and sets the measurement position. The measurement position on the OCT image is specified based on the display position of the line L3 on the color fundus image and the information regarding the obtained correspondence. Then, the control unit 70 acquires a tomographic image corresponding to the measurement (acquisition) position specified as described above from the three-dimensional OCT image information, and displays this on the display monitor 75.

  In addition, as described above, as an OCT image acquired from a three-dimensional OCT image in order to obtain a correspondence relationship with a color fundus image, for example, a retinal surface OCT image or a C scan at a certain depth position. An acquired two-dimensional OCT image or the like can be considered. Further, interference signals having different depths may be added at each measurement position in the XY directions.

  Further, when a color fundus image is photographed using fundus illumination light specified to a predetermined wavelength, the OCT image signal in a portion corresponding to the fundus tissue photographed by using the predetermined wavelength is obtained as three-dimensional OCT image information. You may make it acquire from. For example, when performing fundus imaging using blue illumination light, mainly the vicinity of the nerve fiber layer of the fundus is imaged, so the OCT image signal of the portion corresponding to the nerve fiber layer is acquired from the three-dimensional OCT image information, Based on this, the correspondence with the color fundus image is obtained. In the case of red illumination light, the tissue in the deep fundus is mainly imaged. Therefore, the OCT image signal corresponding to the deep tissue in the fundus may be acquired from the three-dimensional OCT image information.

It is a figure which shows the optical system and control system of the ophthalmologic imaging device of this embodiment. The fundus image acquired by the SLO optical system is displayed on the screen of the display monitor. It is an example of the tomographic image displayed on the monitor. It is an example of a fundus image photographed with a two-dimensional image sensor for color photography. It is a figure explaining the case where a matching process is performed so that the positional relationship of two different images may be matched by image processing between the fundus SLO image and the color fundus image acquired thereafter. It is a figure at the time of displaying electrically the line L2 which shows a measurement position on the color fundus image displayed on the display monitor. It is a figure at the time of displaying the line L3 showing the measurement position of the X direction electrically displayed on the color fundus image displayed on the display monitor. It is a figure which shows the optical system and control system of the ophthalmologic imaging device of 2nd Embodiment. The image of the OCT measurement light portion extracted from the infrared fundus image is synthesized and displayed on the color fundus image displayed on the display monitor. It is a figure explaining the structure of SD-OCT.

DESCRIPTION OF SYMBOLS 11 Observation light source 17 Two-dimensional image sensor 23 Scan part 31 Reference mirror unit 50 Reference mirror drive mechanism 70 Control part 74b Measurement position setting switch 75 Display monitor 100 Fundus camera optical system 100a Illumination optical system 100b Imaging optical system 200 Interference optical system (OCT) Optical system)
300 SLO optical system

Claims (5)

Light splitting means for splitting light from the OCT light source into a measurement optical path and a reference optical path, a scanning unit for scanning measurement light irradiated on the fundus of the eye to be examined through the measurement optical path, and the measurement light from the measurement optical path A light receiving element for detecting the combined light of the fundus reflected light by the light and the light from the reference optical path, and an interference optical system,
An observation image acquiring means for controlling the scanning unit to scan the measurement light two-dimensionally and acquiring an OCT front image that is a front image of the fundus of the eye based on an output signal from the light receiving element;
An acquisition position setting means for displaying the OCT front image on a display and setting an acquisition position of a tomographic image of the fundus to be examined on the OCT front image;
Tomographic image acquisition that controls the scanning unit based on the acquisition position set by the acquisition position setting means and obtains a tomographic image of the fundus oculi corresponding to the acquisition position based on an output signal from the light receiving element. Means,
And obtaining the tomographic image and the OCT front image using the interference optical system. The interference optical system receives a spectrum of light obtained by combining the fundus reflection light by the measurement light and the light from the reference optical path, and performs a Fourier transform on the spectrum to obtain a tomographic image of the eye fundus to be examined. The ophthalmic imaging apparatus according to claim 1, which is a spectral domain OCT optical system for obtaining. The ophthalmologic photographing apparatus according to claim 1, further comprising a visible fundus image acquisition unit that obtains a visible fundus image of the fundus of the subject's eye by visible light. The visible fundus image of the subject's fundus acquired by the visible fundus image acquisition unit and the tomographic image acquired by the tomographic image acquisition unit are displayed on the display, and the tomographic image in the visible fundus image The ophthalmologic photographing apparatus according to claim 3, further comprising display control means for combining and displaying the acquired position on the visible fundus image. The ophthalmologic imaging apparatus according to claim 3, further comprising an image processing unit that associates the OCT front image with the visible fundus image.

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