JP5807371B2 - Ophthalmic imaging equipment - Google Patents

Description

  The present invention relates to an ophthalmologic photographing apparatus for photographing an anterior tomographic image of a subject eye.

  As an ophthalmologic photographing apparatus, for example, a light beam emitted from a light source is divided into a measurement light beam and a reference light beam, the measurement light beam is guided to the anterior eye portion of the eye to be examined, the reference light beam is guided to the reference optical system, and then the front of the eye to be examined. An anterior ocular tomography device (Optical) that has an interference optical system that causes the light receiving element to receive the interference light obtained by combining the measurement light beam reflected by the eye and the reference light beam, and that takes a tomographic image of the anterior ocular segment to be examined Coherence Tomography (OCT) is known. In such an apparatus, by moving a predetermined optical path length changing member in the optical axis direction, the optical path difference between the measurement light and the reference light can be adjusted in accordance with the difference in the axial length of the eye to be examined. .

  By the way, in an apparatus as described above, an adapter having a lens system that moves the focal position of the measurement light from the fundus to the anterior ocular segment is attached to the examination window, so that an anterior ocular segment tomogram can be obtained. By adjusting the optical path difference of the reference light, an anterior segment tomogram was captured.

  An apparatus that acquires a front image based on an OCT interference signal is also known. For example, this apparatus scans the measurement light two-dimensionally, and obtains a front image by integrating the spectral intensity of the interference signal from the light receiving element for each XY point (see Patent Document 1).

US Patent Registration No. 7301644

  By the way, when adjusting imaging conditions without using an SLO optical system or an optical system dedicated to frontal imaging, such as an infrared camera, it is necessary to check the line of sight of the eye and perform tomographic imaging using the OCT optical system. There is.

  However, in the OCT optical system, the imaging range in the depth direction (Z direction) from which an interference signal can be acquired is limited, and when an anterior ocular segment front image is acquired, the anterior ocular segment front image is not displayed well. There is.

  For example, as shown in FIG. 3B, in the state where the corneal tomogram is observed, when a front image of the anterior segment is acquired from the interference signal in the depth direction, the pupil is included in the interference signal in the depth direction. Since information on the peripheral part (for example, iris etc.) is not included, it becomes impossible to acquire a front image of the anterior eye part including the pupil part.

  For this reason, in the state where the corneal tomographic image is observed, it is difficult to observe the pupil position, and it is difficult to confirm the line-of-sight direction.

  Then, photographing may be performed with the line-of-sight direction not facing the front. For this reason, imaging is performed in a state where the visual axis of the eye does not coincide with the imaging optical axis of the apparatus, and a corneal tomographic image may not be acquired well.

  In view of the above problems, an object of the present invention is to provide an ophthalmologic photographing apparatus that can suitably obtain a tomographic image of an eye without using an optical system dedicated to front anterior segment photographing.

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

(1) The ophthalmologic photographing apparatus according to the first aspect of the present disclosure divides a light beam emitted from a light source into measurement light and reference light, and an interference state between the measurement light reflected from the eye to be examined and the reference light An optical path difference changing means for changing the optical path length difference between the measurement light and the reference light in order to adjust the imaging position in the depth direction, and an optical scanner. controls the drive by scanning the measurement light on the subject's eye, an image acquisition unit configured to acquire a tomographic image of the eye based on an output signal from said detector, controls the driving of the optical scanner Image acquisition means for scanning the measurement light two-dimensionally on the eye and acquiring a front image corresponding to a predetermined depth region in the XY direction of the eye based on an output signal from the detector. An ophthalmologic photographic device that is adapted to the shooting position according to the iris. First adjustment operating the drive means in order to output a front image including an iris portion of the eye on the monitor, the rear first adjustment, front image including an iris portion of the eye to the monitor output in state, in response to the output of the trigger signal for starting photographing of images, and controls the drive of said drive means, imaging position adjusting means for performing a second adjustment for shifting the cornea imaging site from the iris, the The image acquisition means acquires a corneal tomographic image of the eye to be examined after the second adjustment by the imaging position adjustment means .

  A tomographic image of the eye can be suitably acquired without using an optical system dedicated to frontal anterior imaging.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an external view of an ophthalmologic photographing apparatus according to the present invention. This apparatus is provided with a base 2, a face support unit 4 attached to the base 2, a movable base 6 movably provided on the base 2, and a movable base 6, which will be described later. An imaging unit (device main body) 8 that houses the optical system is provided. The movable table 6 is moved on the base 2 in the left-right direction (X direction) and the front-rear direction (Z direction) by operating the joystick 12. The photographing unit 8 is moved in the vertical direction (Y direction) by the drive mechanism 17 including a motor or the like when the rotary knob 12a is rotated. In this apparatus, as an imaging unit moving mechanism, a driving mechanism (sliding mechanism) (not shown) that moves the main body 6 in the XZ direction with respect to the base 2 and an imaging unit 8 in the XYZ directions with respect to the main body 6 And a drive mechanism 17 to be driven. The drive mechanism 17 includes, for example, a combination of three motors corresponding to the XYZ directions and XYZ slide mechanisms driven by the motors, and has a mechanism for moving the photographing unit 8 in the three-dimensional direction. The moving table 6 is provided with a monitor 75 for outputting (displaying) various information such as an acquired eye image and measurement results, and a control unit 74 in which switches for performing various settings are arranged.

  In the present embodiment, an anterior ocular segment tomographic imaging apparatus will be described as an example of an ophthalmic imaging apparatus. FIG. 2 is a diagram illustrating an optical system and a control system of the anterior segment tomography apparatus according to the present embodiment. In the following description, an anterior ocular segment tomographic imaging apparatus capable of capturing a fundus tomographic image will be described as an example. In this embodiment, the depth direction of the eye to be examined is described as the Z direction (optical axis L1 direction), the horizontal component on the plane perpendicular to the depth direction is defined as the X direction, and the vertical component is described as the Y direction. The following optical system is built in the photographing unit 8.

  In FIG. 2, the optical system divides the light beam emitted from the light source into measurement light and reference light, guides the measurement light to the eye to be examined (anterior eye part), guides the reference light to the reference optical system, An interference optical system (OCT optical system) 200 that detects an interference state between the measurement light reflected from the anterior optometry and the reference light by a detector, and a fixation target projection unit 300 are provided. The interference optical system 200 includes a measurement optical system 200a and a reference light optical system 200b. In addition, the interference optical system 200 splits the interference light generated by the reference light and the measurement light for each frequency (wavelength), and makes the light receiving means (in this embodiment, a one-dimensional light receiving element) receive the split interference light. An optical system 800 is included. Further, the dichroic mirror 40 has a characteristic of reflecting light having a wavelength component used as measurement light of the OCT optical system 200 and transmitting light having a wavelength component used for the fixation target projection unit 300.

  First, the configuration of the OCT optical system 200 provided on the reflection side of the dichroic mirror 40 will be described. 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. The measurement light goes to the eye E through the optical fiber 38b, and the reference light goes to the reference mirror 31 through the optical fiber 38c (polarizer (polarizing element) 33).

  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 collimating lens 22, the focusing optical member (focusing lens) 24, the scanning unit (optical scanner) 23, and A relay lens 95 is disposed. The dichroic mirror 40 and the objective lens 10 serve as a light guide optical system that guides the OCT measurement light from the OCT optical system 200 to the eye to be examined.

  The focusing lens 24 is movable in the optical axis direction by driving of the driving mechanism 24a, and is used for correcting the diopter for the subject's fundus.

  The scanning unit 23 is composed of a combination of two galvanometer mirrors. The galvanometer mirror and the scanning drive mechanism 51 are arranged in the optical path of the measurement light, and are used to scan the measurement light in a direction (XY direction) perpendicular to the optical axis of the interference optical system 200 on the eye to be examined. It is used as an optical scanner that changes the traveling direction of the light. The optical scanner uses an acousto-optic device (AOM) that changes the traveling (deflection) direction of light in addition to a mirror.

  The measurement light emitted from the end portion 39b of the optical fiber 38b is collimated by the collimating lens 22, and then reaches the scanning unit 23 via the focusing lens 24, and the reflection direction is changed by driving the two galvanometer mirrors. Then, the measurement light reflected by the scanning unit 23 is reflected by the dichroic mirror 40 via the relay lens 95 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 via the objective lens 10, travels toward the OCT optical system 200, relay lens 95, two galvanometer mirrors of the scanning unit 23, focusing lens 24, and collimator. The light enters the end 39b of the optical fiber 38b through the lens 22. The measurement light incident on the end 39b reaches the end 84a of the optical fiber 38d through the optical fiber 38b, the fiber coupler 26, and the optical fiber 38d.

  On the other hand, an optical fiber 38 c, an end portion 39 c of the optical fiber 38 c that emits the reference light, a collimator lens 29, and the reference mirror 31 are arranged in the optical path that emits the reference light toward the reference mirror 31. The optical fiber 38c is rotated by the drive mechanism 34 in order to change the polarization direction of the reference light. That is, the optical fiber 38c and the drive mechanism 34 are used as a polarizer 33 for adjusting the polarization direction.

  The drive mechanism 50 drives an optical member (for example, the reference mirror 31) disposed in the optical path of the reference light in order to adjust the optical path length difference between the measurement light and the reference light. The reference mirror 31 is moved in the optical axis direction by driving the drive mechanism 50 in order to change the optical path length of the reference light, and its movable range is set so as to cope with the difference in the axial length of each eye to be examined. Yes. In FIG. 2, the reference mirror 31 can move in a range from a movement limit position K1 in the direction in which the optical path length of the reference light is shortened to a movement limit position K2 in the direction in which the optical path length of the reference light is increased.

  The reference light emitted from the end 39c of the optical fiber 38c is converted into a parallel light beam by the collimator lens 29, reflected by the reference mirror 31, collected by the collimator lens 29, and incident on the end 39c of the optical fiber 38c. The reference light incident on the end 39c reaches the fiber coupler 26 via the optical fiber 38c and the optical fiber 38c (polarizer 33).

  Then, the reference light generated as described above by the light emitted from the light source 27 and the fundus reflection light by the measurement light irradiated on the eye fundus to be examined are combined by the fiber coupler 26 to be interference light, The light is emitted from the end portion 84a through the fiber 38d. A spectroscopic optical system 800 (spectrometer unit) that separates interference light into frequency components to obtain an interference signal for each frequency includes a collimator lens 80, a grating mirror (diffraction grating) 81, a condensing lens 82, and a light receiving element 83. . The light receiving element 83 is a one-dimensional element (line sensor) having sensitivity in the infrared region.

  Here, the interference light emitted from the end portion 84 a is converted into parallel light by the collimator lens 80, and then split into frequency components by the grating 81. Then, the interference light split into frequency components is condensed on the light receiving surface of the detector (light receiving element) 83 via the condenser lens 82. Thereby, spectrum information of interference fringes is recorded on the light receiving element 83. Then, a tomographic image of the eye is captured based on the output signal from the light receiving element 83. That is, the spectrum information is input to the control unit 70 and analyzed using Fourier transform, whereby information in the depth direction of the subject's eye can be measured.

  Here, the control unit 70 controls the driving of the scanning unit 23 to scan the measurement light on the eye to be examined (for example, the anterior eye part), and acquires the tomographic image of the eye to be examined based on the output signal from the light receiving element 83. it can. For example, by scanning in the X direction or the Y direction, a tomographic image (for example, an anterior ocular segment tomographic image) on the XZ plane or the YZ plane of the eye to be examined can be acquired (in this embodiment, the measurement light is used in this way. Is a one-dimensional scan with respect to the eye to obtain a tomographic image as a B-scan). The acquired tomogram is stored in the memory 72 connected to the control unit 70. Furthermore, by controlling the driving of the scanning unit 23 and scanning the measurement light in the XY direction two-dimensionally, based on the output signal from the light receiving element 83, the two-dimensional moving image or the subject in the XY direction of the subject's eye is detected. It is also possible to acquire a three-dimensional image of the optometry.

  When a front image is obtained by the OCT optical system 200, the control unit 70 controls the driving of the scanning unit 23 to scan the measurement light in the XY directions on the eye E two-dimensionally, and the light receiving element 83 for each XY point. A front image corresponding to a predetermined depth region with respect to the XY direction of the eye is acquired based on the output signal from. For example, the control unit 70 forms a front image by integrating the spectral intensities of the interference signals output from the light receiving element 83 for each XY point. Of course, the method of acquiring the front image is not limited to this. For example, the number of zero cross points of the interference signal acquired for each XY point may be converted into a luminance value.

  In the above configuration, the optical path length of the reference light is changed to adjust the optical path difference between the measurement light and the reference light. However, the present invention is not limited to this, and the optical path length of the optical path length of the measurement light is changed. You may make it do. For example, the end portions of the collimator lens 22 and the optical fiber 39b may be moved in the optical axis direction.

  Note that this apparatus has an optical path difference changing unit that changes the optical path difference between the measurement light and the reference light in order to adjust the imaging position in the depth direction. For example, at least of the optical members disposed in the interference optical system 200 The optical path difference is adjusted by moving a part. In this apparatus, the drive mechanism 50 adjusts the optical path difference by driving the reference mirror 31, for example. The drive mechanism 50 may be configured to move a part of the optical member arranged in the interference optical system 200, and even if the optical member (for example, the collimator lens 22 and the optical fiber 39b) in the measurement optical path is moved. Good. Further, the sliding mechanism and the driving mechanism 17 adjust the optical path difference by moving the photographing unit 8 including the interference optical system 200 in the front-rear direction.

  In addition, the optical path difference may be adjusted by using a drive unit that moves the eye E in the front-rear direction with respect to the imaging unit 8. For example, the chin rest provided in the face support unit 4 is driven in the front-rear direction with respect to the photographing unit 8.

  Next, the fixation target projection unit 300 will be described. The fixation target projecting unit 300 includes an optical system for guiding the line-of-sight direction of the eye E. The fixation projection unit 300 has a fixation target presented to the eye E, and can guide the eye E in a plurality of directions.

  For example, the fixation target projection unit 300 has a visible light source that emits visible light, and changes the presentation position of the target two-dimensionally. Thereby, the line-of-sight direction is changed, and as a result, the imaging region is changed. For example, when the fixation target is presented from the same direction as the imaging optical axis, the center of the fundus is set as the imaging site. When the fixation target is presented upward with respect to the imaging optical axis, the upper part of the fundus is set as the imaging region. That is, the imaging region is changed according to the position of the target with respect to the imaging optical axis.

  As the fixation target projection unit 300, for example, a configuration in which the fixation position is adjusted by the lighting positions of LEDs arranged in a matrix, light from a light source is scanned using an optical scanner, and fixation is performed by lighting control of the light source. Various configurations such as a configuration for adjusting the position are conceivable. The fixation target projection unit 300 may be an internal fixation lamp type or an external fixation lamp type.

  Further, a display monitor 75, a memory 72, a control unit 74, a drive mechanism 50, a drive mechanism 24a, a drive mechanism 34, and the like are connected to the control unit 70. In the present embodiment, the memory 72 uses a fundus photographing mode for capturing a tomographic image and a front image of the fundus of the eye without using the anterior eye adapter 500 (hereinafter referred to as an adapter), and the adapter 500. An anterior ocular segment imaging mode for capturing a tomographic image and a front image of the anterior segment of the eye to be examined is prepared. When the mode switching signal is output, the control unit 70 switches the optical arrangement of the apparatus, the display screen of the monitor, and the like according to the shooting mode.

  In the fundus photographing mode, for example, photographing is performed as follows. The control unit 70 processes the spectrum data detected by the light receiving element 83 and forms a fundus front image by image processing. When the fundus front image is displayed on the monitor 75, an OCT image is acquired by the OCT optical system 200 based on a preset scanning pattern and displayed on the monitor 75. Here, when a predetermined trigger signal is output, the control unit 70 acquires a fundus tomographic image and a fundus front image based on the set scanning position / pattern, and stores the acquired image data in the memory 72. . The control unit 70 controls the drive of the drive mechanism 50 based on the light reception signal output from the light receiving element 83, and adjusts the optical path difference between the measurement light and the reference light so that a fundus tomographic image is acquired. In this case, the reference mirror 31 is moved within a predetermined movement range corresponding to the difference in the axial length of the eye to be examined. As described above, photographing is performed in the fundus photographing mode.

  Hereinafter, the anterior segment imaging mode will be described.

  The control unit 70 adjusts the position of each optical member so that the OCT optical system 200 has a predetermined optical arrangement corresponding to the anterior segment imaging mode. In some cases, it may be necessary to secure a working distance between the device and the eye E so that the anterior eye portion is in focus (for example, a treatment such as increasing the thickness of a forehead provided in the device).

  Then, the control unit 70 controls the drive of the scanning unit 23 to scan the measurement light on the anterior segment, and acquires an anterior segment tomographic image based on the output signal from the light receiving element 83. That is, the anterior segment tomogram and the anterior segment front image are acquired by the OCT optical system 200 based on a preset scanning pattern by the controller 70 and displayed on the monitor 75 as a moving image. While observing the monitor 75, the examiner uses the joystick 12 to display the desired tomographic image and the desired front image of the anterior segment in the display area (imaging range) on the monitor 75. Align the part. At this time, the imaging region on the eye E is changed by the alignment, the tomographic image displayed in the display area of the monitor 75 is changed, and the front image of the anterior segment displayed on the monitor 75 is also changed. This is because both the tomographic image and the anterior eye front image are acquired by the OCT optical system 200.

  Here, when capturing an anterior ocular segment tomographic image, it is necessary to confirm the eye gaze direction and acquire the anterior ocular segment tomographic image. For example, when a corneal tomographic image at the center of the cornea is to be acquired satisfactorily, it is necessary to shoot with the visual axis of the eye coincident with the imaging optical axis of the apparatus and the center of the cornea is disposed on the imaging optical axis. There is. In this case, the examiner confirms the position of the pupil in the front image of the anterior eye part, confirms the line-of-sight direction of the eye to be examined, confirms that the line-of-sight direction is facing the front direction, and performs imaging. At this time, for example, when the line-of-sight direction is deviated from the front direction, the corneal tomographic image may be displayed tilted or the tomographic image at the center of the cornea may not be displayed. As a result, the thickness of the cornea cannot be detected with high accuracy.

  For this reason, it is necessary to confirm the line-of-sight direction of the front image of the anterior eye part, confirm that the line-of-sight direction is facing the front direction, match the visual axis of the eye with the imaging optical axis of the device, and perform image acquisition. is there. Confirmation of the line-of-sight direction is performed by confirming the pupil part of the front image of the anterior segment. At this time, as a method for correcting the gaze direction, for example, the gaze direction of the subject may be guided using a fixation lamp.

  FIG. 3 is a diagram illustrating an example of a front image and a tomographic image acquired (formed) by the OCT optical system 200. FIG. 3A shows a tomographic image (left diagram) and an anterior eye front image (right diagram) when an iris is included in the imaging range. FIG. 3B shows a tomographic image (left diagram) and an anterior ocular segment front image (right diagram) when the cornea is included in the imaging range.

  The alignment is performed by moving the apparatus main body with respect to the eye E by the operator operating the joystick 12 or the like. The examiner performs alignment and positions the depth position where the optical path lengths of the measurement light and the reference light coincide with each other in the vicinity of the iris. That is, the examiner performs alignment so that the observation screen on the monitor 75 becomes a screen as shown in FIG.

  In this case, the control unit 70 processes the spectral data detected by the light receiving element 83, forms an iris tomographic image and an anterior ocular segment front image by image processing, and displays them on the monitor 75. A pupil portion is displayed on the monitor 75 (see FIG. 3A).

  FIG. 3B is a diagram when a corneal tomographic image is acquired. Based on the output signal from the light receiving element 83, the control unit 70 forms a corneal tomogram and an anterior ocular segment front image and displays them on the monitor 75. In this case, the pupil portion is not displayed on the monitor 75 (see FIG. 3B).

  This is because when the front image of the anterior segment is acquired using the OCT optical system 200, the range that can be acquired is limited in acquiring the interference signal in the depth direction. That is, when the imaging range is positioned in the vicinity of the cornea, it is not possible to acquire an interference signal in the periphery of the pupil (for example, the iris). For this reason, no pupil is displayed in the front image of the anterior segment. Therefore, when the examiner performs alignment straight to the cornea, it is difficult to confirm the line of sight.

  As described above, when an optical system dedicated to frontal imaging such as an SLO optical system or an anterior ocular imaging optical system is not used, the OCT optical system can be obtained by aligning the imaging range straight in the vicinity of the cornea to obtain a corneal tomographic image. The pupil portion is not displayed in the front image of the anterior segment acquired by the system 200. Therefore, the direction of the line of sight cannot be confirmed in the front image of the anterior segment.

  The imaging region (imaging position) can be changed by moving the reference mirror 31 or the apparatus main body. For example, when the reference mirror 31 is stopped at a predetermined position, the imaging region is adjusted by an alignment operation by moving the apparatus main body. Further, in a state where the alignment operation is not performed, the imaging region is adjusted by moving the reference mirror 31.

  FIG. 4 is a diagram illustrating a flowchart for describing a photographing procedure in the anterior segment photographing mode according to the present embodiment. When switching to the anterior segment imaging mode is performed, the control unit 70 automatically adjusts the position of each optical member so that the OCT optical system 200 has a predetermined optical arrangement corresponding to the anterior segment imaging mode. To do.

  In this embodiment, when an anterior ocular segment tomographic image is captured in the anterior ocular segment imaging mode, the focusing lens 24 is moved to a predetermined position (for example, + 5D position) in the plus diopter direction, and the OCT optical system is used. The focus position of the measurement light by the system 200 is moved to the apparatus side. That is, the apparatus is in a state in which the measurement light can be focused on the anterior segment by attaching the adapter 500 and adjusting the position of the focusing lens 24 to the plus side.

  When executing the anterior segment imaging mode, the examiner attaches the adapter 500 to the examination window (not shown). When attached, the control unit 70 issues a switching signal for switching from the fundus imaging mode to the anterior segment imaging mode. In this case, a sensor for detecting the wearing state is provided.

  Hereinafter, adjustment of the position of each optical member will be described.

<Optical path length adjustment>
The control unit 70 controls the drive of the drive mechanism 50 based on the mode switching signal, and positions the reference mirror 31 at a predetermined position corresponding to the anterior segment imaging mode. Note that after the movement of the reference mirror 31 is completed, the movement of the reference mirror 31 may be prohibited or the movement range may be limited to a predetermined range.

  The predetermined position of the reference mirror 31 is stored in the memory 72 in advance. Here, the position of the reference mirror 31 is a position where the tomographic image of the iris can be acquired when the focus position of the measurement light is arranged in the vicinity of the anterior eye segment (for example, the iris or cornea) by the examiner's alignment operation. It is preferably set.

  For example, the position of the reference mirror 31 is adjusted so that the iris (see iris C1 in FIG. 3) is acquired at a predetermined depth position in a state where the working distance is properly adjusted by the examiner's alignment, The position at that time is stored in the memory 72. These are obtained by simulation or experiment.

  When the predetermined position of the reference mirror 31 is moved, a sensor (an encoder, a potentiometer, or the like) that detects the position of the reference mirror 31 is provided, and the reference mirror is stored at a predetermined position stored in the memory 72 based on a detection signal from the sensor. 31 is moved. In addition, a sensor (for example, a photo sensor) is provided at a position corresponding to a predetermined position within the moving range of the reference mirror 31, and when the sensor detects that the reference mirror 31 is positioned at the predetermined position, The movement may be stopped.

<Focus adjustment>
In the OCT optical system 200, the control unit 70 controls driving of the drive mechanism 24a, and positions the focusing lens 24 at a predetermined position corresponding to the anterior segment imaging mode. When the focusing lens 24 reaches a predetermined position, the control unit 70 prohibits driving of the drive mechanism 24a.

  The predetermined position of the focusing lens 24 is stored in the memory 72 in advance. The position of the focusing lens 24 is such that the measurement light is focused on the anterior ocular segment (for example, the cornea) and the principal ray of the measurement light toward the cornea and the optical axis L1 are parallel at a predetermined predetermined working distance. It is preferable that it is the position which becomes. The position is stored in the memory 72. These are obtained by simulation or experiment.

<Control action>
As described above, the position of each optical member is automatically adjusted so that the OCT optical system 200 has a predetermined optical arrangement corresponding to the anterior ocular segment imaging mode.

  In general, as a position adjustment for obtaining a corneal tomographic image, a driving unit (for example, a sliding mechanism) of the optical path difference changing unit is operated in order to output an iris image to be inspected to the monitor 75 in accordance with an imaging position. And adjusting the drive of the optical path difference changing unit drive unit (for example, the drive mechanism 50) in response to the drive command signal issued after the first adjustment and shifting the imaging part from the iris to the predetermined part. Make adjustments. The first adjustment drive unit and the second adjustment drive unit may be the same drive unit or different drive units. This will be described more specifically. The control unit 70 displays a front image generated by the OCT optical system 200 on the monitor 75. After instructing the subject to gaze at the fixation target of the fixation target projection unit 300, the examiner observes the anterior ocular segment observation image (see FIG. 3) on the monitor 75 while focusing on the pupil center of the subject eye. An alignment operation in the XY directions is performed using the joystick 12 so that the photographing optical axis comes. The examiner uses the joystick 12 to perform an alignment operation in the Z direction while checking the monitor 75.

  Here, the examiner operates the joystick 12 while viewing the front image of the anterior segment on the monitor 75 to move the imaging range to a position near the iris and adjust the working distance. As a result, as shown in FIG. 3A, an anterior eye front image in which the iris is included in the imaging range and the pupil can be observed is displayed.

  The examiner may adjust the working distance so that the tomographic image is correctly displayed. When alignment with the anterior segment is completed, the controller 70 acquires a tomographic image and a front image (anterior segment front image) by the OCT optical system 200 based on a preset scanning pattern, and the acquired front image. And the tomographic image is displayed as a moving image on the monitor 75. At this time, a front image including an iris portion is displayed as the front image.

  Then, the examiner confirms the line-of-sight direction from the anterior segment front image or the anterior segment cross-sectional image displayed on the monitor 75. Then, the examiner confirms that the line-of-sight direction is the front direction. Thereafter, when a desired scanning position / pattern is set and a predetermined trigger signal is output, the control unit 70 acquires a front image of the anterior segment and stores the acquired image data (for example, as a still image) in the memory. 72.

  When the trigger signal is output, the control unit 70 controls the drive of the drive mechanism 50 to move the reference mirror 31 in the optical axis direction. At this time, an output signal output from the light receiving element 83 is acquired at each position, and the presence or absence of a signal corresponding to the cornea is determined with respect to the acquired output signal. Then, the reference mirror 31 is positioned at a position where it is determined that there is a cornea.

  For example, when a trigger signal is output, the control unit 70 moves the reference mirror 31 to the movement limit position K1. Then, the movement of the reference mirror 31 is started from the movement limit position K1 toward the reverse movement limit position K2. At this time, the control unit 70 controls the drive of the drive mechanism 50 to move the reference mirror 31 and, based on the output signals output from the light receiving element 83 at each position of the reference mirror 31, The reference mirror 31 is moved to the acquired position.

  Here, the control unit 70 moves the reference mirror 31 in a predetermined step (for example, 1 mm step as an imaging range), and obtains an output signal from the light receiving element 83 at each movement position. And the depth profile in each movement position is acquired, and the position where the cornea is acquired is searched.

  For example, the control unit 70 acquires a tomographic image at each movement position of the reference mirror 31. Then, for example, as shown in FIG. 5, a luminance distribution is obtained when the center of the tomographic image is scanned in the Z-axis direction. Of course, a plurality of scans may be performed, and an average luminance distribution as a result may be acquired.

  Thereafter, the control unit 70 performs edge detection from the luminance distribution. For the first time, a position where the luminance value of the detected edge rises above the reference value is determined as the corneal position. The reference value is set in advance as a reference value, for example, by a predetermined amount smaller than the average cornea luminance value on the tomogram by simulation or experiment.

  As described above, the tomogram is analyzed for each position of the acquired reference mirror 31, and the position where the cornea is detected for the first time is searched. Then, the position of the reference mirror 31 corresponding to the position where the corneal position is detected for the first time is stored in the memory 75.

  At this time, the control unit 70 calculates the movement amount of the reference mirror 31 that makes the deviation amount from the predetermined depth position P to the image detection position P1 (corneal position) zero, and further calculates the reference mirror for the calculated movement amount. 31 is moved. As a result, a corneal tomogram is obtained at a predetermined depth position P. Thereby, the control unit 70 can move the reference mirror 31 so that the amount of deviation from the optical path length coincidence position S (position corresponding to the optical path length of the reference light) to the cornea becomes a predetermined amount of deviation. Thus, the corneal tomogram can be displayed at a predetermined display position.

  The control unit 70 acquires a tomographic image after the reference mirror 31 is moved. Thereby, a corneal tomogram can be acquired.

  By doing so, it is possible to confirm the eye line-of-sight direction without using an optical system dedicated to frontal imaging, and it is possible to satisfactorily acquire a corneal tomogram at the center of the cornea.

  When the adapter 500 is removed, the control unit 70 outputs a signal for switching to the fundus photographing mode. When the switching signal is issued, the control unit 70 controls driving of the driving mechanism 50 and the driving mechanism 24a so that the OCT optical system 200 has an optical arrangement corresponding to the fundus photographing mode, and automatically positions the optical members. Adjust to. In this case, the reference mirror 31 and each focusing lens 24 are moved to a predetermined origin position. Further, when the switching signal described above is issued, the control unit 70 controls the display on the monitor 75 and changes the display screen from imaging for the anterior segment to imaging for the fundus.

  In addition, when performing the switching control corresponding to the anterior ocular segment imaging mode based on the detection signal generated when the adapter 500 is attached, the present invention is not limited to the above method. For example, the control unit 70 displays on the monitor 75 a message that prompts the user to switch to the anterior ocular segment imaging mode (for example, asks whether or not to shift to the anterior ocular segment imaging mode). The above-described change control may be performed based on the selection signal. Further, the mode may be switched based on a scanning signal from a predetermined mode switch provided in the control unit 74.

  In the present embodiment, as a method of adjusting the position of the reference mirror 31 so that a corneal tomogram is acquired, a method of detecting a position where the cornea can be acquired is not limited to this.

  For example, the average anterior chamber depth of the eye to be examined is calculated in advance through experiments and simulations, and the offset amount is set based on the calculated depth. In this case, the control unit 70 moves the reference mirror 31 by the set offset amount when changing the imaging range from the iris vicinity position to the cornea vicinity position. At this time, the cornea may be detected after the offset amount is moved, and the reference mirror 31 may be moved again.

  In the present embodiment, the corneal position is detected using a preset reference luminance value, but the present invention is not limited to this. For example, when the reference mirror 31 is moved, the rising edge and the falling edge in the luminance are detected, and the interval between the edges is compared with a predetermined reference interval value to determine the position where the cornea is acquired. You may search. In this case, the average corneal thickness of the eye is calculated in advance, and a predetermined reference interval value is set. That is, any configuration that determines the presence or absence of the cornea by using reflection information from the cornea may be used.

  In the present embodiment, the cornea is detected from the movement limit position K1 and the reference mirror 31 is moved. However, the present invention is not limited to this. For example, the reference mirror 31 may be moved from the position near the iris toward the cornea to detect the position at which the corneal tomographic image is acquired. That is, the detection start position of the cornea can be set between the movement limit position K1 and the movement limit position K2.

  In the present embodiment, the reference mirror 31 is moved when acquiring a corneal tomographic image through adjustment after confirming the line-of-sight direction. However, the present invention is not limited to this.

  The optical path difference may be adjusted by driving a driving unit that moves the entire optical member (the entire interference optical system 200) arranged in the interference optical system 200 in the optical axis direction. In this case, as shown in FIG. 3A, after the alignment is adjusted and the line-of-sight direction is confirmed, when a predetermined trigger signal is issued, the control unit 70 drives the drive unit (for example, a motor). Then, the apparatus main body (imaging unit 8) is moved so that the cornea is included in the imaging range. For example, the movement amount of the apparatus main body may be obtained in advance by simulation or experiment so that the alignment range including the iris in the imaging range shifts to the alignment position including the cornea. The amount of movement may be obtained based on the average anterior chamber depth of the eye. As a result, the distance between the eye E and the apparatus main body is adjusted so that the cornea is included in the imaging range, and a corneal tomogram can be acquired (see FIG. 3B).

  In addition, with regard to the automatic adjustment of the optical arrangement at the time of switching the mode, the focal position of the measurement light is determined by inserting / removing the lens system inside the device, not by a device that obtains a tomographic image of the fundus and anterior segment by attaching an adapter The present invention can also be applied to an apparatus having a configuration that switches between a part and a fundus. Of course, the present invention can also be applied to a dedicated apparatus for photographing an anterior segment tomogram.

  In the above description, each imaging condition is adjusted based on the depth profile after Fourier transform, but the present invention is not limited to this. That is, each imaging condition may be adjusted based on the output signal output from the detector. For example, spectral data before Fourier transform may be used.

  In the above description, the spectrum domain OCT using a spectrum meter has been described as an example, but the present invention is not limited to this. For example, SS-OCT (Swept source OCT) provided with a wavelength variable light source may be used.

  In the present embodiment, the controller 70 is configured to acquire a corneal tomographic image of the subject's eye by performing a second adjustment that shifts the imaging region from the iris to the cornea with the predetermined region as the cornea. However, the present invention is not limited to this. For example, the present invention can be applied to a case where a fundus tomographic image is taken from a position near the iris with a predetermined site as the fundus.

In this case, as the position adjustment for obtaining the fundus tomographic image, in order to output the iris image to be examined to the monitor 75 in accordance with the imaging position, the first adjustment for operating the optical path difference changing unit, and after the first adjustment. In response to the issued drive command signal, the drive unit of the optical path difference changing unit is controlled to perform a second adjustment for shifting the imaging region from the iris to a predetermined region.

It is a figure which shows the external appearance of the ophthalmologic apparatus which concerns on this invention. It is a figure which shows the optical system and control system of the anterior ocular segment tomography apparatus which concern on this embodiment. It is a figure which shows an example of the front image and tomographic image which are acquired by the OCT optical system. It is a flowchart explaining the procedure of imaging | photography in the anterior ocular segment imaging | photography mode which concerns on this embodiment. It is a figure which shows the change of the luminance distribution in the depth direction of an image.

8 Shooting Unit 12 Joystick 23 Scanning Unit 24 Focusing Lens 24a Drive Mechanism 31 Reference Mirror (Optical Path Length Variable Member)
DESCRIPTION OF SYMBOLS 50 Drive mechanism 70 Control part 72 Memory 74 Control part 75 Monitor 83 Light receiving element 200 Interference optical system (OCT optical system)
300 Fixation target projection unit 500 Anterior eye adapter

Claims (4)

An interference optical system that divides a light beam emitted from a light source into measurement light and reference light, and detects an interference state between the measurement light reflected from the eye to be examined and the reference light by a detector;
An optical path difference changing unit that has a driving unit and changes an optical path length difference between the measurement light and the reference light in order to adjust a photographing position in the depth direction;
And controls the driving of the optical scanner to scan the measurement light on the eye to be examined, on the basis of the output signal from the detector an image acquisition unit configured to acquire a tomographic image of the eye, controls the driving of the optical scanner Image measuring means for two-dimensionally scanning the measurement light on the eye to be examined, and obtaining a front image corresponding to a predetermined depth region with respect to the XY direction of the eye to be examined based on an output signal from the detector; An ophthalmologic photographing apparatus comprising:
First adjustment operating the drive means in order to output the combined imaging position in the iris of the front image including an iris portion of the eye on the monitor, the first after adjustment, the iris of the eye on the monitor In a state where a front image including a portion is output, in response to the output of a trigger signal for starting image capturing, the driving unit is controlled to shift the imaging region from the iris to the cornea. shooting position adjustment means for performing,
With
The ophthalmic imaging apparatus , wherein the image acquisition means acquires a corneal tomographic image of the eye to be examined after the second adjustment by the imaging position adjustment means . The ophthalmologic photographing apparatus according to claim 1 .
The ophthalmologic photographing apparatus according to claim 1, wherein the driving unit is a driving unit that moves at least a part of an optical member arranged in the interference optical system in an optical axis direction. In the ophthalmologic photographing apparatus according to claim 1 or 2 ,
The control means controls the drive of the drive means to move at least a part of the optical member arranged in the interference optical system in the optical axis direction,
Obtain the output signal output from the detector at each position, determine the presence or absence of a signal corresponding to the cornea for the acquired output signal,
An ophthalmologic photographing apparatus, wherein at least a part of the optical member is positioned at a position determined to have a cornea. In the ophthalmologic photographing apparatus according to any one of claims 1 to 3,
In response to the output of the trigger signal for starting image capturing, a front image including the iris portion of the eye to be examined is acquired, and the second adjustment by the imaging position adjusting means is performed, and after the second adjustment An ophthalmologic photographing apparatus characterized by acquiring a corneal tomographic image of an eye to be examined .