JP2019054993A - Blood flow measurement device - Google Patents

Abstract

To provide a blood flow measurement device improved in reproducibility of a measurement position in eyeground blood flow measurement using an optical coherence tomography.SOLUTION: A blood flow measurement device includes a storage part, a fixation target projection part, and a control part 210. The storage part stores fixation location information showing a past fixation position applied in the past hemodynamics measurement to the eyeground of an eye to be inspected. The fixation target projection part projects a fixation target to the eyeground. The control part controls the fixation target projection part so as to move a fixation position by the fixation target from a prescribed initial fixation position to a past fixation position. The blood flow measurement device executes the hemodynamics measurement of the eyeground after the fixation position by the fixation target is moved to the past fixation position.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a blood flow measuring device.

  Optical coherence tomography (OCT) is used not only for measuring the form of an object but also for measuring its function. For example, an apparatus for measuring blood flow of a living body using OCT is known. OCT blood flow measurement is applied to measurement of blood flow dynamics in the fundus.

JP2013-184018A JP 2009-165710 A Special table 2010-523286

  In many clinical departments as well as ophthalmologists, follow-up observations and pre- and post-operative observations are performed. In follow-up observations and the like, it is desirable to acquire each time data under the same conditions. When using OCT blood flow measurement for follow-up observation or the like, it is desirable to repeatedly measure the same position of the same blood vessel.

  An object of the present invention is to improve the reproducibility of a measurement position in OCT blood flow measurement of the fundus.

  A first aspect of the embodiment is a blood flow measurement device that measures the blood flow dynamics of the fundus using optical coherence tomography, and is applied to past blood flow dynamics measurement on the fundus of the eye to be examined. A storage unit for storing fixation position information indicating a position, a fixation target projection unit for projecting a fixation target on the fundus, and a fixation position by the fixation target from a predetermined initial fixation position to the past A control unit that controls the fixation target projection unit to move to the fixation position, and after the fixation position by the fixation target is moved to the past fixation position, the blood flow dynamics measurement of the fundus Execute.

  A second aspect of the embodiment is the blood flow measurement device according to the first aspect, wherein the storage unit displays the fundus when the past fixation position is applied in the past blood flow dynamic measurement. Further storing a past front image acquired by photographing, and further including a fundus photographing unit that photographs the fundus and obtains a front image, and the control unit includes the front image obtained by the fundus photographing unit and the fundus photographing unit. Based on the past front image, movement control of the fixation position by the fixation target is performed, and the blood flow dynamic measurement is executed after the movement control.

  A third aspect of the embodiment is the blood flow measurement device according to the second aspect, wherein after the fixation position by the fixation target is moved to the past fixation position, the control unit The movement control is performed so that a front image substantially the same as an image is acquired by the fundus imaging unit.

  A fourth aspect of the embodiment is the blood flow measurement device according to the first aspect, wherein the storage unit displays the fundus when the past fixation position is applied in the past blood flow dynamic measurement. Further storing a past front image acquired by photographing, and further including a fundus photographing unit that photographs the fundus and obtains a front image, and the control unit includes the front image obtained by the fundus photographing unit and the fundus photographing unit. An operation unit for displaying a past front image on a display means and moving a fixation position by the fixation target; the fixation position by the fixation target is moved to the past fixation position; and The blood flow dynamics measurement is executed after the operation of moving the fixation position using the operation unit is performed.

  A fifth aspect of the embodiment is the blood flow measurement device according to any one of the first to fourth aspects, wherein the fixation target projection unit includes a display unit that displays a fixation target image, and the display unit. An optical system for guiding the fixation target image displayed on the eye to the eye to be examined, and the control unit fixes the fixation target by changing the display position of the fixation target image by the display unit The position is moved.

  A sixth aspect of the embodiment is the blood flow measurement device according to any one of the first to fourth aspects, wherein the fixation target projection unit includes a light source unit in which a plurality of light emitting units are arranged in a matrix. An optical system that guides the light output from the light source unit to the eye to be inspected, and the control unit moves the fixation position by the fixation target by selectively lighting the plurality of light emitting units. It is characterized by that.

  According to the embodiment, it is possible to improve the reproducibility of the measurement position in the fundus OCT blood flow measurement.

It is a schematic diagram showing an example of composition of a blood flow measuring device concerning an embodiment. It is a schematic diagram showing an example of composition of a blood flow measuring device concerning an embodiment. It is a schematic diagram showing an example of composition of a blood flow measuring device concerning an embodiment. It is a schematic diagram showing an example of composition of a blood flow measuring device concerning an embodiment. It is the schematic for demonstrating an example of operation | movement of the blood-flow measuring device which concerns on embodiment. It is the schematic for demonstrating an example of operation | movement of the blood-flow measuring device which concerns on embodiment. It is a flowchart showing an example of operation | movement of the blood-flow measuring device which concerns on embodiment. It is a flowchart showing an example of operation | movement of the blood-flow measuring device which concerns on embodiment. It is a flowchart showing an example of operation | movement of the blood-flow measuring device which concerns on embodiment.

  A blood flow measurement device according to an exemplary embodiment will be described in detail with reference to the drawings. The blood flow measurement device according to the embodiment forms a tomographic image or a three-dimensional image of a living body using OCT. The contents of the cited references described in this specification can be incorporated into the embodiments.

  In the following embodiments, a blood flow measurement device capable of measuring the fundus of a living eye using Fourier domain OCT (particularly, swept source OCT) will be described. The type of OCT is not limited to the swept source, and may be, for example, a spectral domain OCT or a time domain OCT. The blood flow measurement device according to the embodiment is a device in which an OCT device and a fundus camera are combined, but a fundus imaging device other than the fundus camera and an OCT device may be combined. Examples of such a fundus imaging apparatus include a scanning laser ophthalmoscope (SLO), a slit lamp microscope, and an ophthalmic surgical microscope.

<Constitution>
As shown in FIG. 1, the blood flow measurement device 1 includes a fundus camera unit 2, an OCT unit 100, and an arithmetic control unit 200. The fundus camera unit 2 is provided with an optical system and a mechanism for acquiring a front image of the eye to be examined. The OCT unit 100 is provided with a part of an optical system and a mechanism for performing OCT. Another part of the optical system and mechanism for performing OCT is provided in the fundus camera unit 2. The arithmetic control unit 200 includes one or more processors that execute various types of arithmetic operations and controls. In addition to these, optional elements such as a member for supporting the subject's face (chin rest, forehead rest, etc.) and a lens unit for switching the OCT target site (for example, anterior segment OCT attachment) Or a unit may be provided in the blood flow measurement device 1.

  In this specification, the “processor” is, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), or a programmable logic device (for example, SPLD (Simple ProLigL). It means a circuit such as Programmable Logic Device (FPGA) or Field Programmable Gate Array (FPGA). For example, the processor implements the functions according to the embodiment by reading and executing a program stored in a storage circuit or a storage device.

<Fundus camera unit 2>
The fundus camera unit 2 is provided with an optical system for photographing the fundus oculi Ef of the eye E to be examined. The acquired image of the fundus oculi Ef (referred to as a fundus oculi image, a fundus oculi photo or the like) is a front image such as an observation image or a captured image. The observation image is obtained by moving image shooting using near infrared light. The photographed image is a still image using flash light.

  The fundus camera unit 2 includes an illumination optical system 10 and a photographing optical system 30. The illumination optical system 10 irradiates the eye E with illumination light. The imaging optical system 30 detects the return light of the illumination light from the eye E. The measurement light from the OCT unit 100 is guided to the eye E through the optical path in the fundus camera unit 2, and the return light is guided to the OCT unit 100 through the same optical path.

  The light (observation illumination light) output from the observation light source 11 of the illumination optical system 10 is reflected by the concave mirror 12, passes through the condensing lens 13, passes through the visible cut filter 14, and becomes near infrared light. Further, the observation illumination light is once converged in the vicinity of the photographing light source 15, reflected by the mirror 16, and passes through the relay lens system 17, the relay lens 18, the stop 19, and the relay lens system 20. The observation illumination light is reflected by the peripheral part of the perforated mirror 21 (region around the hole part), passes through the dichroic mirror 46, and is refracted by the objective lens 22 to illuminate the eye E (fundus Ef). To do. The return light of the observation illumination light from the eye E is refracted by the objective lens 22, passes through the dichroic mirror 46, passes through the hole formed in the central region of the perforated mirror 21, and passes through the dichroic mirror 55. The light is reflected by the mirror 32 via the photographing focusing lens 31. Further, the return light passes through the half mirror 33A, is reflected by the dichroic mirror 33, and forms an image on the light receiving surface of the image sensor 35 by the condenser lens. The image sensor 35 detects return light at a predetermined frame rate. Note that the focus of the photographing optical system 30 is adjusted to match the fundus oculi Ef or the anterior eye segment.

  The light (imaging illumination light) output from the imaging light source 15 is applied to the fundus oculi Ef through the same path as the observation illumination light. The return light of the imaging illumination light from the eye E is guided to the dichroic mirror 33 through the same path as the return light of the observation illumination light, passes through the dichroic mirror 33, is reflected by the mirror 36, and is reflected by the condenser lens 37. An image is formed on the light receiving surface of the image sensor 38.

  A liquid crystal display (LCD) 39 displays a fixation target (fixation target image). A part of the light beam output from the LCD 39 is reflected by the half mirror 33 </ b> A, reflected by the mirror 32, passes through the hole of the perforated mirror 21 through the photographing focusing lens 31 and the dichroic mirror 55. The light beam that has passed through the aperture of the aperture mirror 21 passes through the dichroic mirror 46, is refracted by the objective lens 22, and is projected onto the fundus oculi Ef.

  By changing the display position of the fixation target image on the screen of the LCD 39, the fixation position of the eye E to be examined by the fixation target can be changed. Examples of fixation positions include a fixation position for acquiring an image centered on the macula, a fixation position for acquiring an image centered on the optic nerve head, and between the macula and the optic nerve head. There are a fixation position for acquiring an image centered on the center of the fundus, a fixation position for acquiring an image of a part (a fundus peripheral portion) far away from the macula, and the like. A graphical user interface (GUI) or the like for designating at least one of such typical fixation positions can be provided. Further, a GUI or the like for manually moving the fixation position (display position of the fixation target) can be provided.

  The configuration for presenting the fixation target that can change the fixation position to the eye E is not limited to a display device such as an LCD. For example, a fixation matrix in which a plurality of light emitting units (light emitting diodes or the like) are arranged in a matrix (array) can be used instead of the display device. In this case, the fixation position of the eye E by the fixation target can be changed by selectively turning on the plurality of light emitting units. As another example, a fixation target whose fixation position can be changed can be generated by one or more movable light emitting units.

  The alignment optical system 50 generates an alignment index used for alignment of the optical system with respect to the eye E. The alignment light output from the light emitting diode (LED) 51 passes through the diaphragm 52, the diaphragm 53, and the relay lens 54, is reflected by the dichroic mirror 55, passes through the hole of the perforated mirror 21, and passes through the dichroic mirror 46. The light passes through and is projected onto the eye E through the objective lens 22. Return light (corneal reflection light or the like) of the alignment light from the eye E is guided to the image sensor 35 through the same path as the return light of the observation illumination light. Manual alignment and auto-alignment can be executed based on the received light image (alignment index image).

  The focus optical system 60 generates a split index used for focus adjustment with respect to the eye E. The focus optical system 60 is moved along the optical path (illumination optical path) of the illumination optical system 10 in conjunction with the movement of the imaging focusing lens 31 along the optical path (imaging optical path) of the imaging optical system 30. The reflector 67 is inserted into and removed from the illumination optical path. When performing the focus adjustment, the reflecting surface of the reflecting bar 67 is inclinedly arranged in the illumination optical path. The focus light output from the LED 61 passes through the relay lens 62, is separated into two light beams by the split indicator plate 63, passes through the two-hole aperture 64, is reflected by the mirror 65, and is reflected by the condenser lens 66 as a reflecting rod 67. The light is once imaged and reflected on the reflection surface. Further, the focus light passes through the relay lens 20, is reflected by the perforated mirror 21, passes through the dichroic mirror 46, and is projected onto the eye E through the objective lens 22. The return light (fundus reflection light or the like) of the focus light from the eye E is guided to the image sensor 35 through the same path as the return light of the alignment light. Manual focusing and autofocusing can be executed based on the received light image (split index image).

  Diopter correction lenses 70 and 71 can be selectively inserted into the photographing optical path between the perforated mirror 21 and the dichroic mirror 55. The diopter correction lens 70 is a plus lens (convex lens) for correcting the intensity hyperopia. The diopter correction lens 71 is a minus lens (concave lens) for correcting intensity myopia.

  The dichroic mirror 46 combines the fundus imaging optical path and the OCT optical path (measurement arm). The dichroic mirror 46 reflects light in a wavelength band used for OCT and transmits light for fundus photographing. In the measurement arm, a collimator lens unit 40, an optical path length changing unit 41, an optical scanner 42, an OCT focusing lens 43, a mirror 44, and a relay lens 45 are provided in this order from the OCT unit 100 side.

  The optical path length changing unit 41 is movable in the direction of the arrow shown in FIG. 1 and changes the length of the measurement arm. The change of the measurement arm length is used, for example, for optical path length correction according to the axial length, adjustment of the interference state, or the like. The optical path length changing unit 41 includes, for example, a corner cube and a mechanism for moving the corner cube.

  The optical scanner 42 is substantially disposed at a position optically conjugate with the pupil of the eye E. The optical scanner 42 deflects the measurement light LS guided by the measurement arm. The optical scanner 42 is, for example, a galvano scanner capable of two-dimensional scanning.

  The OCT focusing lens 43 is moved along the measurement arm to adjust the focus of the measurement arm. The movement of the photographing focusing lens 31, the movement of the focus optical system 60, and the movement of the OCT focusing lens 43 can be controlled in a coordinated manner.

<OCT unit 100>
As illustrated in FIG. 2, the OCT unit 100 is provided with an optical system for executing the swept source OCT. This optical system includes an interference optical system. This interference optical system divides the light from the wavelength tunable light source (wavelength swept type light source) into measurement light and reference light, and interferes with the return light of the measurement light from the eye E and the reference light via the reference light path. Interference light is generated, and this interference light is detected. The detection result (detection signal) obtained by the interference optical system is a signal representing the spectrum of the interference light and is sent to the arithmetic control unit 200.

  The light source unit 101 includes, for example, a near-infrared wavelength tunable laser that changes the wavelength of emitted light at high speed. The light L0 output from the light source unit 101 is guided to the polarization controller 103 by the optical fiber 102 and its polarization state is adjusted. Further, the light L0 is guided to the fiber coupler 105 by the optical fiber 104 and is divided into the measurement light LS and the reference light LR. The optical path of the measurement light LS is called a measurement arm or the like, and the optical path of the reference light LR is called a reference arm or the like.

  The reference light LR is guided to the collimator 111 by the optical fiber 110 and converted into a parallel light beam, and is guided to the corner cube 114 via the optical path length correction member 112 and the dispersion compensation member 113. The optical path length correction member 112 acts to match the optical path length of the reference light LR and the optical path length of the measurement light LS. The dispersion compensation member 113 acts to match the dispersion characteristics between the reference light LR and the measurement light LS. The corner cube 114 is movable in the incident direction of the reference light LR, and thereby the optical path length of the reference light LR is changed.

  The reference light LR that has passed through the corner cube 114 passes through the dispersion compensation member 113 and the optical path length correction member 112, is converted from a parallel light beam to a focused light beam by the collimator 116, and enters the optical fiber 117. The reference light LR incident on the optical fiber 117 is guided to the polarization controller 118 and its polarization state is adjusted. The reference light LR is guided to the attenuator 120 through the optical fiber 119 and the amount of light is adjusted. Led.

  On the other hand, the measurement light LS generated by the fiber coupler 105 is guided by the optical fiber 127 and converted into a parallel light beam by the collimator lens unit 40, and the optical path length changing unit 41, the optical scanner 42, the OCT focusing lens 43, and the mirror 44. Then, the light is reflected by the dichroic mirror 46 via the relay lens 45, refracted by the objective lens 22, and projected onto the eye E. The measurement light LS is scattered and reflected at various depth positions of the eye E. The return light from the eye E to be measured LS travels in the opposite direction on the same path as the forward path, is guided to the fiber coupler 105, and reaches the fiber coupler 122 via the optical fiber 128.

  The fiber coupler 122 generates interference light by superimposing the measurement light LS incident through the optical fiber 128 and the reference light LR incident through the optical fiber 121. The fiber coupler 122 generates a pair of interference light LC by branching the generated interference light at a predetermined branching ratio (for example, 1: 1). The pair of interference lights LC are guided to the detector 125 through optical fibers 123 and 124, respectively.

  The detector 125 includes, for example, a balanced photodiode. The balanced photodiode has a pair of photodetectors that respectively detect the pair of interference lights LC, and outputs a difference between a pair of detection results obtained by these. The detector 125 sends this output (detection signal) to the data acquisition system (DAQ) 130.

  A clock KC is supplied from the light source unit 101 to the data collection system 130. The clock KC is generated in synchronization with the output timing of each wavelength that is swept within a predetermined wavelength range by the wavelength variable light source in the light source unit 101. For example, the light source unit 101 divides the light L0 of each output wavelength to generate two branched lights, optically delays one of the branched lights, synthesizes the branched lights, and combines the obtained synthesized lights. The clock KC is generated based on the detection result. The data acquisition system 130 performs sampling of the detection signal input from the detector 125 based on the clock KC. The data collection system 130 sends the sampling result to the arithmetic and control unit 200.

  In this example, both an element for changing the measurement arm length (such as the optical path length changing unit 41) and an element for changing the reference arm length (such as the corner cube 114) are provided. Only elements may be provided. In addition, elements for changing the difference (optical path length difference) between the measurement arm length and the reference arm length are not limited to these, and may be arbitrary elements (optical members, mechanisms, etc.).

<Control system>
A configuration example of the control system of the blood flow measuring device 1 is shown in FIGS. The control unit 210, the image forming unit 220, and the data processing unit 230 are provided in the arithmetic control unit 200.

<Control unit 210>
The control unit 210 executes various controls. The control unit 210 includes a main control unit 211 and a storage unit 212.

<Main control unit 211>
The main control unit 211 includes a processor and controls each unit (including the elements shown in FIGS. 1 to 4) of the blood flow measurement device 1. The imaging focusing lens 31 and the focus optical system 60 are moved by an imaging focusing drive unit (not shown), and the OCT focusing lens 43 is moved by an OCT focusing driving unit (not shown). Further, the reference driving unit 114 </ b> A provided in the OCT unit 100 moves the corner cube 114.

  For example, the moving mechanism 150 moves at least the fundus camera unit 2 in a three-dimensional manner. In a typical example, the moving mechanism 150 includes an x stage that can move in the ± x direction (left and right direction), an x moving mechanism that moves the x stage, and a y stage that can move in the ± y direction (up and down direction). , A y moving mechanism for moving the y stage, a z stage movable in the ± z direction (depth direction), and a z moving mechanism for moving the z stage. Each moving mechanism includes an actuator such as a pulse motor and is controlled by the main control unit 211.

  The main control unit 211 controls the LCD 39. For example, the main control unit 211 displays a fixation target at a preset position on the screen of the LCD 39. Further, the main control unit 211 can gradually change the display position of the fixation target displayed on the LCD 39. The movement control of the fixation position will be described later.

<Storage unit 212>
The storage unit 212 stores various data. Examples of data stored in the storage unit 212 include OCT images, fundus images, and eye information. The eye information includes subject information such as patient ID and name, left / right eye identification information, electronic medical record information, and the like.

  In the present embodiment, fixation position information indicating fixation positions (past fixation positions) applied in past OCT blood flow measurement (blood flow dynamic measurement) on the fundus oculi Ef of the eye E is stored in the storage unit 212. Is done. The past fixation position is expressed by, for example, the display position (pixel coordinates) of the fixation target image on the LCD 39. This coordinate is, for example, a coordinate represented by a two-dimensional coordinate system defined in advance on the display screen of the LCD 39. When a fixation matrix is used, the past fixation position is expressed by, for example, the position (coordinates) of the light emitting unit that is lit. This coordinate is, for example, a coordinate represented by a two-dimensional coordinate system defined in advance on the array surface of the plurality of light emitting units.

<Image forming unit 220>
The image forming unit 220 forms tomographic image data and phase image data of the fundus oculi Ef based on a signal (sampling data) input from the data acquisition system 130. These images will be described later. The image forming unit 220 includes, for example, the above-described circuit board and microprocessor. In this specification, “image data” and “image” based thereon may be identified. The image forming unit 220 includes a tomographic image forming unit 221 and a phase image forming unit 222.

  In the present embodiment, two types of scanning (first scanning and second scanning) are performed on the fundus oculi Ef. In the first scan, the first cross section that intersects the target blood vessel of the fundus oculi Ef is repeatedly scanned with the measurement light LS. In the second scanning, the measurement light LS scans the second cross section that intersects the target blood vessel and is located in the vicinity of the first cross section. Here, the first cross section and the second cross section are oriented so as to be substantially orthogonal to the traveling direction of the blood vessel of interest, for example. In the present embodiment, for example, as shown in a fundus oculi image D of FIG. 5, one first cross section C0 and two second cross sections C1 and C2 located in the vicinity of the optic disc Da of the fundus oculi Ef are the target blood vessel Db. Is set to intersect. One of the two second cross sections C1 and C2 is located upstream of the target blood vessel Db with respect to the first cross section C0, and the other is located downstream.

  For example, the first scan is performed over at least one cardiac cycle of the patient's heart. Thereby, it becomes possible to grasp blood flow dynamics in all cardiac phases. The time for executing the first scan may be a predetermined time set in advance, or may be set for each patient or for each examination. In the former case, a time longer than the standard cardiac cycle is set (for example, 2 seconds). In the latter case, biometric data such as a patient's electrocardiogram can be referred to. Here, factors other than the cardiac cycle can be considered. Examples of this factor include time required for examination (a burden on the patient), response time of the optical scanner 42 (scan time interval), response time of the detector 125 (scan time interval), and the like.

<Tomographic image forming unit 221>
The tomographic image forming unit 221 forms a tomographic image (first tomographic image) representing a time-series change in form in the first cross section based on sampling data obtained from the data acquisition system 130 in the first scan. This process will be described in more detail. In the first scanning, the first cross section C0 is repeatedly scanned as described above. Sampling data is sequentially input from the data collection system 130 to the tomographic image forming unit 221 in accordance with this repeated scanning. The tomographic image forming unit 221 forms one tomographic image of the first cross section C0 based on sampling data corresponding to each scan of the first cross section C0. The tomographic image forming unit 221 forms a series of tomographic images along a time series by repeating this process as many times as the first scan is repeated. Here, these tomographic images may be divided into a plurality of groups, and the tomographic image groups included in each group may be superimposed to improve the image quality (image averaging process).

  In addition, the tomographic image forming unit 221 generates a tomographic image (second tomographic image) representing the form of the second cross section C1 based on the sampling data obtained by the data acquisition system 130 in the second scan for the second cross sections C1 and C2. And a tomographic image (second tomographic image) representing the form of the second cross section C2. The process for forming the second tomographic image is executed in the same manner as the process for forming the first tomographic image. Here, the first tomogram is a series of tomograms in time series, but the second tomogram may be a single tomogram. The second tomographic image may be an image obtained by superimposing a plurality of tomographic images obtained by scanning each of the second cross sections C1 and C2 a plurality of times to improve the image quality (addition average of images). processing).

  The processing for forming such a tomographic image includes noise removal (noise reduction), filter processing, fast Fourier transform (FFT), and the like, as in the conventional Fourier domain OCT. In the case of another type of OCT apparatus, the tomographic image forming unit 221 executes a known process corresponding to the type.

<Phase image forming unit 222>
The phase image forming unit 222 forms a phase image representing a time-series change of the phase difference in the first cross section based on the sampling data obtained by the data acquisition system 130 in the first scan. The sampling data used for forming the phase image is the same as the sampling data used for forming the first tomographic image by the tomographic image forming unit 221. Therefore, it is possible to perform alignment between the first tomographic image and the phase image. That is, it is possible to set a natural correspondence between the pixels of the first tomographic image and the pixels of the phase image.

  An example of a phase image forming method will be described. The phase image of this example is obtained by calculating the phase difference between adjacent A-line complex signals (that is, signals corresponding to adjacent scanning points). In other words, the phase image in this example is formed based on the time series change of the pixel value (luminance value) of the first tomographic image. For any pixel in the first tomographic image, the phase image forming unit 222 creates a graph of the time-series change in luminance value of the pixel. The phase image forming unit 222 obtains a phase difference Δφ between two time points t1 and t2 (t2 = t1 + Δt) separated by a predetermined time interval Δt in this graph. The phase difference Δφ is defined as the phase difference Δφ (t1) at the time point t1 (more generally, an arbitrary time point between the time point t1 and the time point t2). By executing this process for each of a number of preset time points, a time-series change in phase difference in the pixel can be obtained.

  The phase image represents the value of the phase difference at each time point of each pixel as an image. This imaging process can be realized, for example, by expressing the value of the phase difference with the display color or brightness. At this time, it is possible to change the display color (for example, red) when the phase increases along the time series and the display color (for example, blue) when it decreases. Further, the magnitude of the phase change amount can be expressed by the density of the display color. By adopting such an expression method, the direction and size of the blood flow can be clearly indicated by the display color. A phase image is formed by executing the above processing for each pixel.

  The time-series change of the phase difference is obtained by ensuring the phase correlation by sufficiently reducing the time interval Δt. At this time, oversampling in which the time interval Δt is set to a value less than the time corresponding to the resolution of the tomographic image in the scanning of the measurement light LS is executed.

<Data processing unit 230>
The data processing unit 230 performs various types of image processing and analysis processing on the image formed by the image forming unit 220. For example, the data processing unit 230 executes various correction processes such as image brightness correction and dispersion correction. Further, the data processing unit 230 performs various types of image processing and analysis processing on images (fundus image, anterior eye image, etc.) obtained by the fundus camera unit 2.

  The data processing unit 230 can form three-dimensional image data of the fundus oculi Ef. Three-dimensional image data means image data in which pixel positions are defined by a three-dimensional coordinate system. Examples of 3D image data include stack data and volume data.

  The stack data is image data obtained by three-dimensionally arranging a plurality of tomographic images obtained along a plurality of scanning lines based on the positional relationship of the scanning lines. That is, the stack data is an image obtained by expressing a plurality of tomographic images originally defined by individual two-dimensional coordinate systems using one three-dimensional coordinate system (that is, embedding in one three-dimensional space). It is data.

  Volume data is image data in which voxels arranged three-dimensionally are used as pixels, and is also called voxel data. Volume data is formed by applying interpolation processing, voxelization processing, or the like to stack data.

  The data processing unit 230 can form an image for display by performing rendering processing on the three-dimensional image data. Examples of applicable rendering methods include volume rendering, surface rendering, maximum value projection (MIP), minimum value projection (MinIP), and multi-section reconstruction (MPR).

  The data processing unit 230 includes a blood vessel region specifying unit 231 and a blood flow information generating unit 232. The blood flow information generation unit 232 includes an inclination calculation unit 233, a blood flow velocity calculation unit 234, a blood vessel diameter calculation unit 235, and a blood flow rate calculation unit 236. Further, the data processing unit 230 includes a cross-section setting unit 237.

<Vessel region specifying unit 231>
The blood vessel region specifying unit 231 specifies a blood vessel region corresponding to the target blood vessel Db for each of the first tomographic image, the second tomographic image, and the phase image. This processing can be executed by analyzing the pixel value of each image (for example, threshold processing).

  Note that the first tomographic image and the second tomographic image have sufficient resolution as an object of analysis processing, but the phase image may not have enough resolution to identify the boundary of the blood vessel region. However, as long as blood flow information is generated based on the phase image, it is necessary to specify the blood vessel region with high accuracy and high accuracy. Therefore, for example, by performing the following processing, the blood vessel region in the phase image can be specified more accurately.

  As described above, since the first tomographic image and the phase image are formed based on the same sampling data, it is possible to define a natural correspondence between the pixels of the first tomographic image and the pixels of the phase image. is there. For example, the blood vessel region specifying unit 231 obtains a blood vessel region by analyzing the first tomogram, specifies an image region in a phase image corresponding to the blood vessel region based on the correspondence, and specifies the specified image region as a phase. Adopt as a blood vessel region in the image. Thereby, the blood vessel region of the phase image can be specified with high accuracy and high accuracy.

<Blood flow information generation unit 232>
The blood flow information generation unit 232 determines the blood flow related to the target blood vessel Db based on the distance between the first cross section and the second cross section, the result of specifying the blood vessel region, and the time series change of the phase difference in the blood vessel region of the phase image. Generate information. Here, the distance between the first cross section and the second cross section (inter-section distance) is determined in advance. One example will be described later in the description of the cross-section setting unit 237. The blood vessel region is specified by the blood vessel region specifying unit 231. The time series change of the phase difference in the blood vessel region of the phase image is obtained as the time series change of the phase difference for the pixels in the blood vessel region of the phase image. Hereinafter, an example of a configuration for executing this process will be described. As described above, the blood flow information generation unit 232 includes an inclination calculation unit 233, a blood flow velocity calculation unit 234, a blood vessel diameter calculation unit 235, and a blood flow rate calculation unit 236.

<Inclination calculation unit 233>
The inclination calculation unit 233 calculates the inclination of the target blood vessel Db in the first cross section based on the distance between cross sections and the result of specifying the blood vessel region. A method of calculating the inclination of the target blood vessel Db will be described with reference to FIG. Reference numerals G0, G1, and G2 respectively indicate a first tomographic image at the first cross section C0, a second tomographic image at the second cross section C1, and a second tomographic image at the second cross section C2. Reference numerals V0, V1, and V2 denote a blood vessel region of the first tomographic image G0, a blood vessel region of the second tomographic image G1, and a blood vessel region of the second tomographic image G2, respectively. The z coordinate axis shown in FIG. 6 substantially coincides with the projection direction of the measurement light LS. In addition, the interval (inter-section distance) between adjacent tomographic images is d.

  The inclination calculating unit 233 calculates the inclination A of the target blood vessel Db in the first cross section C0 based on the positional relationship between the three blood vessel regions V0, V1, and V2. This positional relationship is obtained, for example, by connecting three blood vessel regions V0, V1, and V2. As a specific example, the inclination calculation unit 233 can identify the feature positions of the three blood vessel regions V0, V1, and V2, and connect these feature positions. Examples of the characteristic position include a center position, a center of gravity position, an uppermost portion (a position having the smallest z coordinate value), and a lowermost portion (a position having the largest z coordinate value). Further, as connection methods of these feature positions, there are a method of connecting with line segments, a method of connecting with approximate curves (spline curve, Bezier curve, etc.), and the like.

  Furthermore, the inclination calculation unit 233 calculates the inclination A based on a line connecting the characteristic positions specified from the three blood vessel regions V0, V1, and V2. When connecting with a line segment, for example, the inclination of the first line segment connecting the characteristic position of the first cross section C0 and the characteristic position of the second cross section C1, the characteristic position of the first cross section C0, and the characteristic position of the second cross section C2 The slope A can be calculated based on the slope of the second line segment connecting the two. As an example of this calculation process, it is possible to obtain the average value of the slopes of two line segments. Further, as an example of connecting with an approximate curve, the slope of the approximate curve at a position where the approximate curve intersects the first cross section C0 can be obtained. The cross-sectional distance d is used, for example, when embedding the tomographic images G0 to G2 in the xyz coordinate system in the process of obtaining a line segment or approximate curve.

  In this example, the blood vessel region in the three cross sections is considered, but it is also possible to obtain the inclination in consideration of the two cross sections. As a specific example, the inclination of the first line segment or the second line segment can be set as a target inclination. In this example, one inclination is obtained, but the inclination may be obtained for each of two or more positions (or areas) in the blood vessel region V0. In this case, two or more obtained slope values can be used separately, or values obtained by statistically processing these slope values (for example, average value, maximum value, minimum value, intermediate value) , Mode value, etc.) can also be used as the slope A.

<Blood velocity calculation unit 234>
The blood flow velocity calculation unit 234 calculates the blood flow velocity in the first cross section C0 of the blood flowing in the blood vessel Db based on the time series change of the phase difference obtained as the phase image. This calculation target may be a blood flow velocity at a certain point in time, or a time-series change (blood flow velocity change information) of this blood flow velocity. In the former case, for example, it is possible to selectively acquire the blood flow velocity in a predetermined time phase of the electrocardiogram (for example, the time phase of the R wave). The time range in the latter is the entire time or a part of the time when the first cross section C0 is scanned.

  When the blood flow velocity change information is obtained, the blood flow velocity calculator 234 can calculate the statistical value of the blood flow velocity in the measurement period. Examples of the statistical value include an average value, standard deviation, variance, median value, mode value, maximum value, minimum value, maximum value, and minimum value. It is also possible to create a histogram relating to the blood flow velocity value.

  The blood flow velocity calculation unit 234 calculates the blood flow velocity using the Doppler OCT method. At this time, the inclination A of the target blood vessel Db in the first cross section C0 calculated by the inclination calculation unit 233 is considered. Specifically, the inclination calculation unit 233 uses the following equation.

here:
Δf represents the Doppler shift received by the scattered light of the measurement light LS;
n represents the refractive index of the medium;
v represents the flow velocity (blood flow velocity) of the medium;
θ represents the angle formed by the irradiation direction of the measurement light LS and the flow vector of the medium;
λ represents the center wavelength of the measurement light LS.

  In this embodiment, n and λ are known, Δf is obtained from the time-series change of the phase difference, and θ is obtained from the slope A (or θ is obtained as the slope A). By substituting these values into the above formula, the blood flow velocity v is calculated.

<Blood vessel diameter calculator 235>
The blood vessel diameter calculation unit 235 calculates the diameter of the target blood vessel Db in the first cross section C0. Examples of this calculation method include a first calculation method using a fundus image (front image) and a second calculation method using a tomographic image.

  When the first calculation method is applied, imaging of the part of the fundus oculi Ef including the position of the first cross section C0 is performed in advance. The fundus image obtained thereby may be an observation image (frame) or a captured image. When the captured image is a color image, an image constituting the image (for example, a red free image) may be used. The captured image may be a fluorescent image obtained by fundus fluorescence contrast imaging (fluorescein fluorescence contrast imaging, etc.), or a blood vessel enhanced image (angiogram, motion contrast image) obtained by OCT angiography (OCT angiography). But you can.

  The blood vessel diameter calculation unit 235 determines the relationship between the scale on the image and the scale in the real space, such as the shooting angle of view (shooting magnification), working distance, and information on the eyeball optical system. Set the scale. This scale represents the length in real space. As a specific example, this scale associates an interval between adjacent pixels with a scale in real space (for example, an interval between pixels = 10 μm). It is also possible to calculate in advance the relationship between various values of the above factor and the scale in the real space, and store information expressing this relationship in a table format or a graph format. In this case, the blood vessel diameter calculation unit 235 selectively applies a scale corresponding to the factor.

  Furthermore, the blood vessel diameter calculation unit 235 calculates the diameter of the target blood vessel Db in the first cross section C0, that is, the diameter of the blood vessel region V0, based on this scale and the pixels included in the blood vessel region V0. As a specific example, the blood vessel diameter calculation unit 235 obtains the maximum value and the average value of the diameters of the blood vessel region V0 in various directions. In addition, the blood vessel region 235 can approximate the outline of the blood vessel region V0 in a circle or an ellipse, and obtain the diameter of the circle or the ellipse. If the blood vessel diameter is determined, the area of the blood vessel region V0 can be (substantially) determined (that is, the two can be substantially associated one-to-one). You may make it calculate.

  A second calculation method will be described. In the second calculation method, typically, a tomographic image at the first cross section C0 is used. This tomographic image may be a first tomographic image or may be obtained separately.

  The scale in this tomographic image is determined based on OCT measurement conditions and the like. In the present embodiment, the first cross section C0 is scanned as shown in FIG. The length of the first cross section C0 is determined based on various factors that determine the relationship between the scale on the image and the scale in the real space, such as working distance and information on the eyeball optical system. For example, the blood vessel diameter calculation unit 235 obtains an interval between adjacent pixels based on this length, and calculates the diameter of the target blood vessel Db in the first cross section C0 in the same manner as in the first calculation method.

<Blood flow rate calculation unit 236>
The blood flow rate calculation unit 236 calculates the flow rate of the blood flowing in the target blood vessel Db based on the blood flow velocity calculation result and the blood vessel diameter calculation result. An example of this process will be described below.

  It is assumed that the blood flow in the blood vessel is a Hagen-Poiseille flow. Further, when the blood vessel diameter is w and the maximum value of the blood flow velocity is Vm, the blood flow rate Q is expressed by the following equation.

  The blood flow rate calculation unit 236 substitutes the calculation result w of the blood vessel diameter by the blood vessel diameter calculation unit 235 and the maximum value Vm based on the calculation result of the blood flow velocity by the blood flow velocity calculation unit 234 into this equation. A target blood flow rate Q is calculated.

<Cross-section setting unit 237>
The main control unit 211 causes the display unit 241 to display a front image of the fundus oculi Ef. This front image may be an arbitrary type of image, for example, an observation image, a captured image, an OCT angiogram, an OCT projection image, or an OCT shadowgram.

  For example, the user operates the operation unit 242 to designate the first cross section C0 for the displayed front image. The cross section setting unit 237 can set the second cross sections C1 and C2 based on the designated first cross section C0 and the front image. As described above, the first cross section CO is designated so as to cross the desired blood vessel Db.

  In another example, the cross section setting unit 237 analyzes the front image of the fundus oculi Ef to identify one or more target blood vessels, and sets one or more first cross sections and one or more second cross sections for each target blood vessel. can do. Here, the target blood vessel is identified based on, for example, the thickness of the blood vessel, the position relative to the optic nerve head, the type of blood vessel (for example, an artery), and the like.

  The data processing unit 230 that functions as described above includes, for example, a processor, a RAM, a ROM, a hard disk drive, and the like. A storage device such as a hard disk drive stores in advance a computer program that causes the processor to execute the above functions.

<User interface 240>
The user interface (UI) 240 includes a display unit 241 and an operation unit 242. The display unit 241 includes the display device 3 shown in FIG. 1 and other display devices. The operation unit 242 includes an arbitrary operation device. The user interface 240 may include a device having both a display function and an operation function, such as a touch panel.

<Operation>
An example of the operation of the blood flow measuring device 1 will be described.

  FIG. 7 shows an example of the first measurement in the repeated measurement performed for follow-up observation and pre- and post-operative observation. It is assumed that preliminary processes such as patient ID input, alignment, and focus adjustment have already been performed. Furthermore, tracking may be started after alignment and focus adjustment. Also, OCT measurement condition setting such as optical path length adjustment is performed at an appropriate timing, for example, as in the prior art.

(S1: Set blood flow measurement conditions (including fixation position))
For example, a user (doctor, comedy, etc.) searches for a blood vessel of interest while referring to an observation image of the fundus oculi Ef. At this time, the user moves the fixation position using the operation unit 242 to guide the blood flow measurement target position (the first cross section C0 described above, referred to as the target cross section) into the OCT applicable range.

(S2: Set blood flow measurement position)
Next, the user uses the operation unit 242 to set a target cross section that is a target of OCT blood flow measurement.

(S3: OCT blood flow measurement)
Subsequently, the blood flow measurement device 1 performs OCT blood flow measurement at the cross section of interest set in step S2.

(S4: Obtain fundus front image)
At this stage, the fixation position set by the user in step S1, which is suitable for the OCT blood flow measurement of the cross section of interest, is applied. In this fixation state, the blood flow measurement device 1 acquires a front image of the fundus oculi Ef.

  The fundus front image may be a frame of an observation image acquired at this stage, a captured image acquired by imaging at this stage, or an OCT image acquired at this stage.

  The timing for acquiring the fundus front image need not be after the OCT blood flow measurement, but may be before or during the OCT blood flow measurement. In general, it is possible to acquire a fundus front image at an arbitrary timing in a period in which a fixation position suitable for OCT blood flow measurement of the cross section of interest is applied.

(S5: Save measurement conditions, fundus front image, blood flow information)
The main control unit 211 acquires the measurement conditions set in Step S1 (including at least the fixation position set by the user), blood flow information acquired in the OCT blood flow measurement in Step S3, and Step S4. The fundus front image is associated with the patient ID. Then, the main control unit 211 stores the measurement condition, blood flow information, and fundus front image associated with the patient ID in the storage unit 212 or another storage device. This completes the initial measurement.

  FIG. 8 shows an example of the second and subsequent measurements in repeated measurement.

(S11: Enter patient ID)
First, a patient ID is input. Examples of the patient ID input method include manual input using the operation unit 242 and reading of a patient card. In addition, biometric authentication such as fingerprint authentication or iris pattern authentication can be applied.

(S12: Read past fixation position and past front image)
The main control unit 211 reads information associated with the patient ID input in step S1 from the storage unit 212 or another storage device. The information associated with the patient ID includes the measurement condition (including at least the past fixation position) stored in step S5 and the fundus front image (referred to as the past front image). Moreover, you may further read the past blood flow information used by below-mentioned step S20.

(S13: Fundus observation started)
The main control unit 211 controls the fundus camera unit 2 to start acquiring an observation image of the fundus oculi Ef and causes the display unit 241 to display the observation image.

(S14: Display a fixation target image corresponding to the initial fixation position)
The main control unit 211 causes the LCD 39 to display a fixation target image corresponding to a predetermined initial fixation position. The initial fixation position is, for example, a fixation position for acquiring an image centered on the macular portion. This initial fixation position is, for example, a position where the optical axes of the imaging optical system 30 intersect on the display screen of the LCD 39 (typically, the center position of the display screen). Note that the initial fixation position is set in advance, and the display position of the fixation target image is stored as, for example, coordinates of the display screen of the LCD 39.

(S15: The fixation position is moved from the initial fixation position to the past fixation position)
Based on the past fixation position read out in step S12, the main control unit 211 controls the LCD 39 to move the fixation position based on the fixation target from a predetermined initial fixation position to the past fixation position.

  In this control, for example, the display position of the fixation target image is moved at a predetermined speed along a line segment connecting the coordinates of the LCD 39 corresponding to the initial fixation position and the coordinates corresponding to the past fixation position. To be executed. The moving speed of the fixation target image is set in advance, for example, at a speed that allows the subject to follow the moving fixation target with a margin. Further, the movement trajectory of the fixation target image is not limited to a linear trajectory, and may be a trajectory having an arbitrary shape such as a curved trajectory or a broken line trajectory.

(S16: Obtain fundus front image)
After the fixation position by the fixation target is moved to the past fixation position, the blood flow measurement device 1 acquires a fundus front image. At this stage, the fixation position applied in the first measurement is reproduced.

  The acquired fundus front image may be a frame of an observation image acquired at this stage, may be a captured image acquired at this stage, or may be an OCT image acquired at this stage.

(S17: The fixation position is adjusted based on the fundus front image and the past front image)
The main control unit 211 performs movement control of the fixation position by the fixation target based on the fundus front image acquired in step S16 and the past front image read in step S12.

  The fundus front image and the past front image are front images acquired in a state where the same fixation position is applied. Therefore, ideally, the fundus front image and the past front image are the same image. However, in practice, it is considered extremely rare that they become the same image due to various conditions. In step S <b> 17, the fixation position is adjusted so as to cancel the shift between the fundus front image and the past front image.

  An example of the process executed in step S17 will be described. After the fixation position based on the fixation target is moved to the past fixation position in step S15, the main control unit 211 determines that the front image substantially the same as the past front image read in step S12 is the blood flow measurement device 1 ( For example, the movement control of the fixation position by the fixation target is performed as acquired by the fundus camera unit 2).

  This movement control is executed, for example, while acquiring an observation image of the fundus oculi Ef. For example, the main control unit 211 (and the data processing unit 230) specifies the displacement (displacement direction and displacement amount) between the sequentially acquired frame and the past front image by image processing such as feature extraction or image correlation. The processing, the processing for obtaining the moving direction and moving amount of the fixation target image that cancels the identified displacement, and the processing for controlling the LCD 39 based on the obtained moving direction and moving amount are repeatedly executed. For example, when the amount of displacement between the frame and the past front image becomes equal to or less than a predetermined threshold, the main control unit 211 ends this series of processes (the process of step S17).

(S18: Blood flow measurement position is set)
Next, the user or the blood flow measuring device 1 sets an attention cross section that is a target of the current OCT blood flow measurement.

  An example in which the user sets an attention cross section will be described. The main control unit 211 causes the display unit 241 to display a past front image and an observation image that are displayed together with an image indicating a cross section of interest in the initial measurement. The user can set a cross section of interest for the observed image while comparing both images.

  An example in which the blood flow measuring device 1 sets a cross section of interest will be described. The data processing unit 230 compares the fundus front image acquired after step S17 with the past front image, and specifies the position in the fundus front image corresponding to the attention cross section of the first measurement in the past front image. The main control unit 211 can set a cross section of interest at the position of the fundus front image specified by the data processing unit 230. Here, the user can manually adjust the attention section set automatically.

(S19: OCT blood flow measurement)
Subsequently, the blood flow measuring device 1 performs OCT blood flow measurement on the cross section of interest set in step S18. The current OCT blood flow measurement is executed, for example, under the measurement conditions applied in the first measurement.

(S20: Comparative display of blood flow information)
The main control unit 211 causes the display unit 241 to display the blood flow information acquired in step S19 and the past blood flow information read at an arbitrary timing in step S12 or later in a manner that can be compared with each other. . The past blood flow information includes at least one blood flow information among one or more blood flow information obtained by one or more measurements performed before the current measurement.

  For example, the main control unit 211 displays the measurement value acquired in step S19 and the past measurement value side by side, or displays the blood flow graph acquired in step S19 and the past blood flow graph side by side. be able to. The blood flow graph represents, for example, a time-series change in blood flow velocity or blood flow volume.

(S21: Save blood flow information)
The main control unit 211 associates blood flow information acquired by the OCT blood flow measurement in step S19 with the patient ID. Then, the main control unit 211 stores blood flow information associated with the patient ID in the storage unit 212 or another storage device.

  In addition to the blood flow information acquired by the OCT blood flow measurement in step S19, the main control unit 211 performs measurement conditions (for example, including a fixation position) applied in the OCT blood flow measurement, and an arbitrary The fundus front image acquired at the timing may be associated with the patient ID and stored. This is the end of the current measurement.

  FIG. 9 shows another example of the second and subsequent measurements in repeated measurement. In the example shown in FIG. 8, the fixation position is automatically adjusted. In this example, the user manually adjusts the fixation position.

(S31: Enter patient ID)
As in step S11, the patient ID is input.

(S32: Read past fixation position and past front image)
As in step S12, the past fixation position, the past front image, the past blood flow information, and the like are read out.

(S33: Fundus observation started)
As in step S13, fundus observation is started.

(S34: Display past front image and observation image)
The main control unit 211 causes the display unit 241 to display the past front image read in step S32 and the observation image acquired in step S33 side by side.

(S35: Display a fixation target image corresponding to the initial fixation position)
Similar to step S <b> 14, a fixation target image corresponding to the initial fixation position is displayed on the LCD 39.

(S36: The fixation position is moved from the initial fixation position to the past fixation position)
Similar to step S15, the fixation position by the fixation target is moved from the initial fixation position to the past fixation position.

(S37: The user adjusts the fixation position)
After the fixation position by the fixation target is moved to the past fixation position in step S36, the user uses the operation unit 242 while referring to the past front image and the observation image started to be displayed in step S34. Adjust the fixation position. The user manually moves the fixation position of the fixation target so that an observation image substantially the same as the past front image is acquired by the blood flow measurement device 1 (fundus camera unit 2).

(S38: Set blood flow measurement position)
Similar to step S18, a blood flow measurement position (intersection of interest) is set.

(S39: OCT blood flow measurement)
Similar to step S19, OCT blood flow measurement is performed.

(S40: Comparative display of blood flow information)
Similar to step S20, comparative display of blood flow information is executed.

(S41: Save blood flow information)
Similar to step S21, blood flow information and the like are stored. This is the end of the current measurement.

<Action and effect>
The operation and effect of the blood flow measurement device according to the embodiment will be described.

  The blood flow measurement device according to the embodiment measures the blood flow dynamics of the fundus using optical coherence tomography (OCT). Furthermore, the blood flow measurement device of the embodiment includes a storage unit (212), a fixation target projection unit (LCD 39, a part of the imaging optical system 30), a control unit (main control unit 211, data processing unit 230), including.

  The storage unit stores fixation position information indicating past fixation positions applied in past blood flow dynamics measurement (OCT blood flow measurement) with respect to the fundus of the eye to be examined. The fixation target projection unit projects the fixation target on the fundus. The control unit controls the fixation target projection unit to move the fixation position by the fixation target from a predetermined initial fixation position to a past fixation position.

  Furthermore, the blood flow measurement device according to the embodiment performs blood flow dynamics measurement of the fundus after the fixation position by the fixation target is moved to the past fixation position. That is, the blood flow measurement device according to the embodiment applies the OCT blood flow measurement to the attention cross section set after the fixation position by the fixation target is moved to the past fixation position.

  According to such an embodiment, first, a fixation target corresponding to a preset initial fixation position is presented. Typically, the initial fixation position is set to a position where the subject can easily recognize, such as a fixation position for macular measurement or a position on the optical axis. Thereafter, the fixation position is moved to the past fixation position applied in the past OCT blood flow measurement. Then, after the fixation position is moved to the past fixation position, the current OCT blood flow measurement is executed.

  Thus, by adopting a configuration in which the fixation target is moved so as to guide from the initial fixation position to the past fixation position, the fixation state of the subject is applied to the fixed fixation applied in the past OCT blood flow measurement. It is possible to guide to the visual state relatively reliably. Therefore, the reproducibility of the measurement position in the fundus OCT blood flow measurement can be improved, and follow-up observation and pre-operative observation can be suitably performed.

  In the embodiment, the storage unit may further store a past front image acquired by photographing the fundus when a past fixation position is applied in past blood flow dynamics measurement. In addition, the blood flow measurement device of the embodiment may further include a fundus imaging unit that captures the fundus and acquires a front image. In addition, the control unit may be configured to perform movement control of the fixation position by the fixation target based on the front image acquired by the fundus imaging unit and the past front image. The blood flow measurement device according to the embodiment performs blood flow dynamics measurement after this movement control.

  According to such a configuration, the fixation position can be automatically adjusted using the front image of the fundus.

  Further, in the embodiment, after the fixation position by the fixation target is moved to the past fixation position, the control unit fixes the fixation so that a front image substantially the same as the past front image is acquired by the fundus imaging unit. You may comprise so that movement control of the fixation position by a mark may be performed.

  According to such a configuration, it is possible to automatically correct the deviation after the fixation state of the eye to be examined is guided to the past fixation position.

  In the embodiment, the storage unit may further store a past front image acquired by photographing the fundus when a past fixation position is applied in past blood flow dynamics measurement. In addition, the blood flow measurement device of the embodiment may further include a fundus imaging unit that captures the fundus and acquires a front image. In addition, the control unit may be configured to cause the display unit (display unit 241) to display the front image and the past front image acquired by the fundus imaging unit. In addition, the blood flow measurement device of the embodiment may further include an operation unit for moving the fixation position by the fixation target. Furthermore, the blood flow measurement device according to the embodiment performs blood flow dynamic measurement after the fixation position by the fixation target is moved to the past fixation position and the fixation position moving operation using the operation unit is performed. Execute.

  According to such a configuration, the fixation position can be manually adjusted using the front image of the fundus.

  The display means may be an element of the blood flow measurement device of the embodiment, or an external display device connected to the blood flow measurement device of the embodiment.

  In the embodiment, the fixation target projection unit includes a display unit (LCD 39) that displays a fixation target image, and an optical system (from the LCD 39 to the objective lens 22) that guides the fixation target image displayed on the display unit to the eye to be examined. An optical member group forming an optical path). Further, the control unit may be configured to move the fixation position by the fixation target by changing the display position of the fixation target image by the display unit.

  In the embodiment, the fixation target projection unit includes a light source unit (fixation matrix) in which a plurality of light emitting units are arranged in a matrix, and an optical system that guides light output from the light source unit to the eye to be examined. Good. Further, the control unit may be configured to move the fixation position based on the fixation target by selectively lighting a plurality of light emitting units.

  The configuration of the fixation target projection unit is not limited to these. In addition, the other elements of the blood flow measurement device according to the embodiment are not limited to the configuration described in the present embodiment.

  The configuration described above is merely an example of an embodiment of the present invention. Therefore, arbitrary modifications (omitted, replacement, addition, etc.) within the scope of the present invention can be made.

DESCRIPTION OF SYMBOLS 1 Blood flow measuring device 2 Fundus camera unit 39 Liquid crystal display 100 OCT unit 210 Control part 211 Main control part 212 Storage part 220 Image formation part 230 Data processing part

Claims (6)

A blood flow measurement device that measures blood flow dynamics of the fundus using optical coherence tomography,
A storage unit that stores fixation position information indicating a past fixation position applied in past blood flow dynamics measurement on the fundus of the eye to be examined;
A fixation target projection unit for projecting the fixation target on the fundus;
A control unit that controls the fixation target projection unit to move the fixation position by the fixation target from a predetermined initial fixation position to the past fixation position, and
After the fixation position by the fixation target is moved to the past fixation position, the blood flow dynamic measurement of the fundus is performed.
Blood flow measuring device. The storage unit further stores a past front image obtained by photographing the fundus when the past fixation position is applied in the past blood flow dynamic measurement,
A fundus photographing unit for photographing the fundus and obtaining a front image;
The control unit performs movement control of a fixation position by the fixation target based on the front image and the past front image acquired by the fundus photographing unit,
The blood flow measurement device according to claim 1, wherein the blood flow dynamics measurement is executed after the movement control. After the fixation position by the fixation target is moved to the past fixation position, the control unit performs the movement control so that a front image substantially the same as the past front image is acquired by the fundus imaging unit. The blood flow measurement device according to claim 2, wherein the blood flow measurement device is performed. The storage unit further stores a past front image obtained by photographing the fundus when the past fixation position is applied in the past blood flow dynamic measurement,
A fundus photographing unit for photographing the fundus and obtaining a front image;
The control unit causes the display unit to display the front image and the past front image acquired by the fundus photographing unit,
An operation unit for moving a fixation position by the fixation target;
The blood flow dynamics measurement is executed after the fixation position by the fixation target is moved to the past fixation position and the fixation position moving operation using the operation unit is performed. The blood flow measurement device according to claim 1. The fixation target projection unit includes:
A display unit for displaying a fixation target image;
An optical system for guiding the fixation target image displayed on the display unit to the eye to be examined,
The blood according to claim 1, wherein the control unit moves a fixation position of the fixation target by changing a display position of the fixation target image by the display unit. Flow measuring device. The fixation target projection unit includes:
A light source unit in which a plurality of light emitting units are arranged in a matrix;
An optical system that guides the light output from the light source unit to the eye to be examined,
The blood flow measuring device according to claim 1, wherein the control unit moves a fixation position based on the fixation target by selectively turning on the plurality of light emitting units.

Images