JP2019130044A - Blood flow measurement device - Google Patents

Abstract

To shorten time for operation to optimize an offset position of incident light for acquiring an optimum Doppler signal in ocular fundus blood flow measurement.SOLUTION: A blood flow measurement device includes a blood flow measuring unit, a moving mechanism, a control unit, and a determination unit. The blood flow measuring unit includes an optical system for applying OCT scan to an ocular fundus and acquires blood flow information based on data collected by OCT scan. The moving mechanism moves the optical system. The control unit applies first moving control for moving the optical system in a first direction intersecting with an optical axis of the optical system by a predetermined distance from the optical axis, to the moving mechanism. The determination unit determines presence and absence of vignetting based on a result of detection of return light of light made incident on an eye to be examined through the optical system after the first moving control. The control unit applies second moving control for further moving the optical system based on a result of the determination acquired by the determination unit, to the moving mechanism.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a blood flow measurement device for measuring blood flow dynamics in the fundus.

  In the field of ophthalmology, development of a device for measuring blood flow dynamics of the fundus using optical coherence tomography (OCT) is in progress.

  In order to obtain an optimal Doppler signal in fundus blood flow measurement, it is necessary to make light incident obliquely with respect to the blood flow direction (blood vessel traveling direction). Therefore, the incident light may be offset with respect to the optical axis of the eye. As the amount of offset increases, light can be incident on the blood vessel more obliquely, while the possibility that the incident light or its return light will be vignetted at the pupil increases. Therefore, it is desirable to find a position where the maximum offset amount is obtained in a range where no vignetting occurs in the pupil. When performing this operation automatically, a method of gradually increasing the offset amount so that vignetting does not occur can be considered, but it takes a long time to achieve the optimal offset position, and it is difficult for the subject to It is assumed that a burden is applied.

JP 2017-42602 A

  An object of the present invention is to shorten the operation for optimizing the offset position of incident light for fundus blood flow measurement.

  The first aspect of the embodiment includes an optical system for applying an optical coherence tomography (OCT) scan to the fundus of a subject's eye, and blood that acquires blood flow information based on data collected by the OCT scan A flow measurement unit, a moving mechanism for moving the optical system, and a first movement control for moving the optical system by a predetermined distance from the optical axis in a first direction orthogonal to the optical axis of the optical system. A control unit applied to the moving mechanism; and a determination unit that determines the presence or absence of vignetting based on a detection result of return light of light incident on the eye to be examined via the optical system after the first movement control. In addition, the control unit is a blood flow measurement device that applies, to the moving mechanism, second movement control for further moving the optical system based on a determination result obtained by the determination unit.

  A second aspect of the embodiment is the blood flow measurement device according to the first aspect, and after the first movement control, the optical system applies an OCT scan to a cross section of the fundus along the target blood vessel. Cross section data is collected, and the determination unit determines the presence or absence of the vignetting based on the cross section data.

  A third aspect of the embodiment is the blood flow measurement device according to the second aspect, and further includes an inclination estimation unit that obtains an estimated value of the inclination of the blood vessel of interest based on the cross-sectional data.

  A fourth aspect of the embodiment is the blood flow measurement device according to the third aspect, in which the control unit includes an estimated value of the inclination obtained by the inclination estimation unit after the second movement control, and The set inclination target value is displayed on the display means.

  A fifth aspect of the embodiment is the blood flow measurement device according to the fourth aspect, further including an operation unit, and when the target value is changed using the operation unit, the control unit is configured to perform the first operation. Run the movement control again.

  A sixth aspect of the embodiment is the blood flow measurement device according to any one of the third to fifth aspects, wherein the estimated value of the inclination obtained by the inclination estimation unit after the second movement control is In the case where it substantially coincides with a preset target value of inclination, the control unit controls the blood flow measurement unit to acquire the blood flow information.

  A seventh aspect of the embodiment is the blood flow measurement device according to any one of the first to sixth aspects, and when the determination unit determines that there is no vignetting, the control unit includes the optical system. When the determination unit determines that the vignetting is present, the control unit is configured to move the optical system in a direction opposite to the first direction. The second movement control is executed so as to move.

  An eighth aspect of the embodiment is the blood flow measurement device according to the seventh aspect, wherein the control unit determines that the vignetting is absent by the determination unit, and the control unit immediately before the first movement control is performed. The second movement control is repeatedly executed until the optical system is arranged at a position where the displacement from the position of the optical axis is maximized.

  A ninth aspect of the embodiment is the blood flow measurement device according to any one of the first to sixth aspects, wherein an observation system for acquiring an infrared observation image of the fundus, and the infrared observation image The control unit further includes an evaluation unit to be evaluated, and the control unit executes the second movement control based on the determination result obtained by the determination unit and the evaluation result obtained by the evaluation unit.

  A tenth aspect of the embodiment is the blood flow measurement device according to the ninth aspect, wherein the determination unit determines that the vignetting is not present, and the evaluation unit determines that the infrared observation image is good. When evaluated, the control unit performs the second movement control to further move the optical system in the first direction, and when the determination unit determines that the vignetting is present, or When the evaluation unit evaluates that the infrared observation image is not good, the control unit executes the second movement control so as to move the optical system in a direction opposite to the first direction.

  An eleventh aspect of the embodiment is the blood flow measurement device according to the tenth aspect, wherein the control unit determines that the vignetting is absent by the determination unit, and the infrared observation image is favorable by the evaluation unit. The second movement control is repeatedly executed until the optical system is disposed at a position where the displacement from the position of the optical axis immediately before the first movement control is maximized.

  A twelfth aspect of the embodiment is the blood flow measurement device according to any one of the ninth to eleventh aspects, and further includes a motion detection unit that analyzes the infrared observation image and detects the movement of the fundus. The control unit applies tracking control for moving the optical system in accordance with the movement of the fundus detected by the motion detection unit to the moving mechanism.

  A thirteenth aspect of the embodiment is the blood flow measurement device according to any one of the first to twelfth aspects, in the first movement control depending on whether or not a mydriatic is applied to the eye to be examined. It further includes a first setting unit for setting the predetermined distance.

  A fourteenth aspect of the embodiment is the blood flow measurement device according to any one of the first to twelfth aspects, wherein a pupil diameter information acquisition unit that acquires a value of the pupil diameter of the eye to be examined, and the pupil diameter And a second setting unit that sets the predetermined distance in the first movement control based on a value.

  According to the embodiment, it is possible to shorten the operation for optimizing the offset position of incident light for fundus 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 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 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 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 the schematic for demonstrating an example of operation | movement of the blood-flow measuring device which concerns on 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.

  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 collects data of the fundus oculi using OCT and generates information (blood flow information) representing blood flow dynamics. Any known technique including the disclosure content of the documents cited in the present 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 (for example, 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.

<First Embodiment>
<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 (eg, 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).

  As in the prior art, the alignment index image of this example is composed of two bright spot images whose positions change depending on the alignment state. When the relative position between the eye E and the optical system changes in the xy direction, the two bright spot images are integrally displaced in the xy direction. When the relative position between the eye E and the optical system changes in the z direction, the relative position (distance) between the two bright spot images changes. When the distance between the eye E to be examined and the optical system in the z direction matches a predetermined working distance, the two bright spot images overlap. When the position of the eye E and the position of the optical system coincide with each other in the xy direction, two bright spot images are presented in or near a predetermined alignment target. When the distance between the eye E and the optical system in the z direction matches the working distance, and the position of the eye E and the position of the optical system in the xy direction match, the two bright spot images overlap and align. Presented in the target.

  In the auto alignment, the data processing unit 230 detects the positions of the two bright spot images, and the main control unit 211 controls a moving mechanism 150 described later based on the positional relationship between the two bright spot images and the alignment target. . In the manual alignment, the main control unit 211 causes the display unit 241 to display two bright spot images together with the observation image of the eye E, and the user uses the operation unit 242 while referring to the two bright spot images displayed. Then, the moving mechanism 150 is operated.

  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, a retroreflector 41, a dispersion compensation member 42, an OCT focusing lens 43, an optical scanner 44, and a relay lens 45 are provided in this order from the OCT unit 100 side.

  The retro-reflector 41 can be moved in the direction of the arrow shown in FIG. 1, thereby changing the length of the measurement arm. The change of the optical path length of the measurement arm is used, for example, for optical path length correction according to the eye axis length, adjustment of the interference state, or the like.

  The dispersion compensation member 42 works together with the dispersion compensation member 113 (described later) disposed on the reference arm so as to match the dispersion characteristics of the measurement light LS and the dispersion characteristics of the reference light LR.

  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.

  The optical scanner 44 is substantially disposed at a position optically conjugate with the pupil of the eye E. The optical scanner 44 deflects the measurement light LS guided by the measurement arm. The optical scanner 44 is, for example, a galvano scanner capable of two-dimensional scanning.

<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 to be converted into a parallel light beam, and is guided to the retro-reflector 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, together with the dispersion compensation member 42 disposed on the measurement arm, acts to match the dispersion characteristics between the reference light LR and the measurement light LS. The retro-reflector 114 is movable along the optical path of the reference light LR incident thereon, thereby changing the length of the reference arm. The change of the optical path length of the reference arm is used, for example, for optical path length correction according to the eye axis length, adjustment of the interference state, or the like.

  The reference light LR that has passed through the retroreflector 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 retroreflector 41, the dispersion compensation member 42, the OCT focusing lens 43, and the optical scanner 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 optical path length of the measurement arm (for example, the retroreflector 41) and an element for changing the optical path length of the reference arm (for example, the retroreflector 114 or the reference mirror) are provided. Although provided, only one element may be provided. Further, elements for changing the difference between the optical path length of the measurement arm and the optical path length of the reference arm (optical path length difference) are not limited to these, and may be arbitrary elements (optical member, mechanism, 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 arranged in the imaging optical path and the focus optical system 60 arranged in the illumination optical path are moved synchronously by an imaging focusing drive unit (not shown) under the control of the main control unit 211. The retro-reflector 41 provided in the measurement arm is moved by the retro-reflector (RR) drive unit 41A under the control of the main control unit 211. The OCT focusing lens 43 arranged on the measurement arm is moved by the OCT focusing driving unit 43A under the control of the main control unit 211. The optical scanner 44 provided in the measurement arm operates under the control of the main control unit 211. The retro-reflector 114 arranged on the reference arm is moved by the retro-reflector (RR) driving unit 114A under the control of the main control unit 211. Each of these drive units includes an actuator such as a pulse motor that operates under the control of the main control unit 211.

  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 of these moving mechanisms includes an actuator such as a pulse motor that operates under the control of the main control unit 211.

  The main control unit 211 controls the LCD 39. For example, the main controller 211 displays a fixation target at a preset position on the screen of the LCD 39. Further, the main control unit 211 can change the display position (fixation position) of the fixation target displayed on the LCD 39. The movement of the fixation target can be performed in any manner such as continuous movement, intermittent movement, and discrete movement. The movement mode of the fixation position in this embodiment will be described later.

  The 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 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.

<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.

<Image forming unit 220>
The image forming unit 220 forms OCT image data of the fundus oculi Ef based on a signal (sampling data) input from the data acquisition system 130. The image forming unit 220 can form B-scan image data (two-dimensional tomographic image data) of the fundus oculi Ef and phase image data. These OCT image data will be described later. The image forming unit 220 includes, for example, a circuit board and a microprocessor. In the present specification, unless otherwise specified, “image data” and “image” based thereon are not distinguished.

  In the blood flow measurement of the present embodiment, two types of scanning (main scanning and supplemental scanning) are performed on the fundus oculi Ef.

  In the main scanning, in order to acquire phase image data, a cross section (target cross section) intersecting the target blood vessel of the fundus oculi Ef is repeatedly scanned with the measurement light LS.

  In the supplemental scanning, a predetermined section (supplementary section) is scanned with the measurement light LS in order to estimate the inclination of the target blood vessel in the target section. The supplemental cross section may be, for example, a cross section that intersects the target blood vessel and is located in the vicinity of the target cross section (first supplemental cross section), or a cross section that intersects the target cross section and is along the target blood vessel (second supplemental cross section). .

  An example in which the first supplemental cross section is applied is shown in FIG. 5A. In this example, as shown in the fundus oculi image D, one attention section C0 located near the optic disc Da of the fundus oculi Ef and two supplementary sections C1 and C2 located near the intersection intersect the attention blood vessel Db. Set to do. One of the two supplementary cross sections C1 and C2 is positioned upstream of the target blood vessel Db with respect to the target cross section C0, and the other is positioned downstream. For example, the target cross section C0 and the supplementary cross sections C1 and C2 are oriented so as to be substantially orthogonal to the traveling direction of the target blood vessel Db.

  An example where the second supplemental cross section is applied is shown in FIG. 5B. In this example, the attention section C0 similar to the example shown in FIG. 5A is set so as to be substantially orthogonal to the attention blood vessel Db, and the supplementary section Cp is set so as to be substantially orthogonal to the attention section C0. The supplementary cross section Cp is set along the target blood vessel Db. As an example, the supplementary cross section Cp may be set so as to pass through the central axis of the target blood vessel Db at the position of the target cross section C0.

  In an exemplary blood flow measurement, the main scan is repeatedly performed over a period that includes at least one cardiac cycle of the patient's heart. Thereby, it becomes possible to obtain blood flow dynamics in all cardiac phases. The time for executing the main 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 44 (scanning time interval), response time of the detector 125 (scanning time interval), and the like.

  The image forming unit 220 includes a tomographic image forming unit 221 and a phase image forming unit 222.

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

  Further, the tomographic image forming unit 221 forms a tomographic image (supplemental tomographic image) representing the form of the supplemental cross section based on the sampling data obtained by the data acquisition system 130 in the supplementary scan for the supplemental cross section. The process for forming the supplemental tomographic image is executed in the same manner as the process for forming the main tomographic image. Here, the main tomographic image is a series of tomographic images along time series, but the supplementary tomographic image may be a single tomographic image. The supplemental tomographic image may be an image obtained by superimposing a plurality of tomographic images obtained by scanning the supplemental cross section a plurality of times to improve the image quality (addition averaging process of images).

  When the supplementary cross sections C1 and C2 illustrated in FIG. 5A are applied, the tomographic image forming unit 221 forms a supplemental tomographic image corresponding to the supplemental cross section C1 and a supplemental tomographic image corresponding to the supplementary cross section C2. When the supplementary cross section Cp illustrated in FIG. 5B is applied, the tomographic image forming unit 221 forms a supplemental tomographic image corresponding to the supplementary cross section Cp.

  The processing for forming the tomographic image as exemplified above 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 cross section of interest based on the sampling data obtained by the data acquisition system 130 in the main scanning. The sampling data used for forming the phase image is the same as the sampling data used for forming the main tomographic image by the tomographic image forming unit 221. Therefore, it is possible to align the main tomographic image and the phase image. That is, it is possible to set a natural correspondence between the pixels of the main 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 a time-series change in pixel values (luminance values) of the main tomographic image. For any pixel in the main 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 executes various data processing. For example, the data processing unit 230 performs various types of image processing and analysis processing on the image formed by the image forming unit 220. As a specific example, the data processing unit 230 executes various correction processes such as image brightness correction and dispersion correction. Furthermore, the data processing unit 230 can perform various types of image processing and analysis processing on images (fundus image, anterior eye image, etc.) obtained by the fundus camera unit 2 and images input from the outside. it can.

  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 rendering 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, a blood flow information generation unit 232, a cross-section setting unit 237, and an vignetting determination unit 238 as exemplary elements for obtaining blood flow information. The blood flow information generation unit 232 includes an inclination estimation unit 233, a blood flow velocity calculation unit 234, a blood vessel diameter calculation unit 235, and a blood flow rate calculation unit 236.

<Vessel region specifying unit 231>
The blood vessel region specifying unit 231 specifies a blood vessel region corresponding to the blood vessel Db of interest for each of the main tomographic image, the supplemental 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 main tomographic image and the supplemental 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 a blood vessel region included in the blood flow information 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 main 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 main tomographic image and the pixels of the phase image. For example, the blood vessel region specifying unit 231 obtains a blood vessel region by analyzing a main tomographic image, 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 image. Adopt as middle blood vessel region. 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 generates blood flow information related to the target blood vessel Db. As described above, the blood flow information generation unit 232 includes the inclination estimation unit 233, the blood flow velocity calculation unit 234, the blood vessel diameter calculation unit 235, and the blood flow rate calculation unit 236.

<Inclination estimation unit 233>
The inclination estimation unit 233 obtains an estimated value of the inclination of the blood vessel of interest based on supplementary cross-section data (cross-section data, supplemental tomographic image) collected by supplementary scanning. This estimated inclination value may be, for example, a measured value of the inclination of the target blood vessel in the target section or an approximate value thereof.

  An example of actually measuring the inclination value of the blood vessel of interest will be described (first example of inclination estimation). When the supplementary cross sections C1 and C2 shown in FIG. 5A are applied, the inclination estimation unit 233 specifies the positional relationship between the cross section of interest C0, the supplemental cross section C1, and the supplemental cross section C2, and specifies the blood vessel region by the blood vessel region specifying unit 231. Based on the result, the inclination of the target blood vessel Db in the target cross section C0 can be calculated.

  A method for calculating the inclination of the blood vessel Db will be described with reference to FIG. 6A. Reference numerals G0, G1, and G2 respectively indicate a main tomographic image at the target section C0, a supplementary tomographic image at the supplementary section C1, and a supplementary tomographic image at the supplementary section C2. Symbols V0, V1, and V2 indicate a blood vessel region in the main tomographic image G0, a blood vessel region in the supplemental tomographic image G1, and a blood vessel region in the supplemental tomographic image G2, respectively. The z coordinate axis shown in FIG. 6A substantially coincides with the incident direction of the measurement light LS. Further, the distance between the main tomographic image G0 (attention cross section C0) and the supplemental tomographic image G1 (supplementary cross section C1) is d, and the main tomographic image G0 (attention cross section C0) and the supplemental tomographic image G2 (supplementary cross section C2) The distance between is also d. The interval between adjacent tomographic images, that is, the interval between adjacent cross sections is referred to as an inter-section distance.

  The inclination estimation unit 233 can calculate the inclination A of the target blood vessel Db in the target 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 estimation 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 estimation 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 slope of the first line segment connecting the feature position of the cross section of interest C0 and the feature position of the supplementary cross section C1, and the first position connecting the feature position of the cross section of interest C0 and the feature position of the supplementary cross section C2. The inclination A can be calculated based on the inclination of the two line segments. 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 cross section of interest 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 be used as the slope A.

  An example of obtaining an approximate value of the inclination of the blood vessel of interest will be described (second example of inclination estimation). When the supplementary cross section Cp shown in FIG. 5B is applied, the inclination estimation unit 233 may analyze a supplemental tomographic image corresponding to the supplementary cross section Cp and calculate an approximate value of the inclination of the target blood vessel Db in the target cross section C0. it can.

  A method for approximating the inclination of the blood vessel Db will be described with reference to FIG. 6B. A symbol Gp indicates a supplemental tomographic image in the supplemental cross section Cp. The symbol A indicates the inclination of the target blood vessel Db as in the example shown in FIG. 6A.

  In this example, the inclination estimation unit 233 can analyze the supplemental tomographic image Gp and specify an image region corresponding to a predetermined tissue of the fundus oculi Ef. For example, the inclination estimation unit 233 can specify an image region (inner boundary membrane region) M corresponding to the inner boundary membrane (ILM) that is the surface tissue of the retina. For example, a known segmentation process is used to specify the image area.

It is known that the inner limiting membrane and the fundus blood vessel are substantially parallel to each other. The inclination estimation unit 233 calculates the inclination A _app of the inner boundary film region M in the attention cross section C0. The inclination A _app of the inner boundary membrane region M in the attention cross section C0 is used as an approximate value of the inclination A of the attention blood vessel Db in the attention cross section C0.

6A and 6B is a vector representing the direction of the target blood vessel Db, and the definition of the value may be arbitrary. As an example, the value of the inclination A can be defined as an angle formed by the inclination (vector) A and the z axis. Similarly, the slope A _app shown in FIG. 6B is a vector representing the direction of the inner boundary membrane region M, and the definition of the value may be arbitrary. For example, the value of the slope A _app can be defined as the angle formed by the slope (vector) A _app and the z-axis. Note that the direction of the z-axis is substantially the same as the incident direction of the measurement light LS.

  The processing executed by the inclination estimation unit 233 is not limited to the above example, and an estimated value of the inclination of the blood vessel Db (for example, the blood vessel of interest) based on the cross-sectional data collected by applying the OCT scan to the cross section of the fundus oculi Ef. It may be an arbitrary process capable of obtaining the slope value of Db itself, its approximate value, and the like.

<Blood velocity calculation unit 234>
The blood flow velocity calculation unit 234 calculates the blood flow velocity in the target cross section C0 of the blood flowing in the target 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 arbitrary part of the time when the target 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 (or the approximate value A _app ) of the target blood vessel Db in the target cross section C0 calculated by the inclination estimation unit 233 is taken into consideration. Specifically, the blood flow velocity calculation unit 234 can use 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 the present 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 its approximate value A _app ). Typically, θ is equal to the slope A (or its approximate value A _app ). 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 target 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 a part of the fundus oculi Ef including the position of the attention 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.

  Further, the blood vessel diameter calculating unit 235 calculates the diameter of the target blood vessel Db in the target cross section C0, that is, the diameter of the blood vessel region V0, based on the 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, a tomographic image at the cross section of interest C0 is typically used. This tomographic image may be a main 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, as shown in FIG. 5A or 5B, the target cross section C0 is scanned. The length of the cross section of interest 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 calculating unit 235 obtains an interval between adjacent pixels based on this length, and calculates the diameter of the target blood vessel Db in the target 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, and may be any one of an observation image, a captured image, a fluorescence image, an OCT angiography image, an OCT projection image, and an OCT shadowgram, for example.

  The user can designate one or more cross sections of interest for the displayed front image of the fundus oculi Ef by operating the operation unit 242. The cross section of interest is designated to intersect the blood vessel of interest. The cross-section setting unit 237 can set one or more supplemental cross-sections for each of the one or more attention sections based on the specified one or more attention sections and the front image of the fundus oculi Ef. Note that the supplementary cross section may be set manually.

  In another example, the cross-section setting unit 237 may be configured to identify one or more blood vessels of interest by analyzing a front image of the fundus oculi Ef. The target blood vessel is identified based on, for example, the thickness of the blood vessel, the positional relationship with respect to a predetermined part of the fundus (for example, the optic nerve head and the macula), the type of blood vessel (for example, artery, vein), and the like. Furthermore, the cross-section setting unit 237 can set one or more target cross sections and one or more supplemental cross sections for each of the specified one or more target blood vessels.

  As described above, the attention cross section and the supplemental cross section illustrated in FIG. 5A or 5B are set for the fundus oculi Ef by the cross section setting section 237 or by the user and the cross section setting section 237 in cooperation with the user. The

<Vignetting determination unit 238>
The vignetting determination unit 238 determines the presence or absence of vignetting based on the detection result of the return light of the light incident on the eye E via the optical system mounted on the blood flow measurement device 1.

  The type, application, and intensity (light quantity) of light incident on the eye E for vignetting determination may be arbitrary. The type of incident light may be, for example, infrared light or visible light. The use of incident light may be, for example, imaging, inspection or measurement.

  Incident light that can be used in the present embodiment may be, for example, OCT measurement light LS, fundus imaging observation illumination light, imaging illumination light, or excitation light. The detection result of the incident light return light may be, for example, an OCT image, an observation image, a captured image, or a fluorescence image.

  “Vignetting” in the present embodiment includes vignetting (decrease in brightness) that occurs when incident light for fundus blood flow measurement or part or all of its return light is blocked by the pupil. Further, the “presence / absence of vignetting” in the present embodiment includes any of the following: whether or not vignetting has occurred; whether or not the degree of vignetting exceeds a predetermined level.

  An example of processing executed by the vignetting determination unit 238 will be described. Hereinafter, although the 1st example regarding a vignetting determination method and a 2nd example are demonstrated, a method is not limited to these.

  In the first example, the incident light for vignetting determination is the measurement light LS, and a predetermined OCT scan is applied. The aspect of the OCT scan in this example may be, for example, an OCT scan for the cross section of interest C0 (or supplementary cross section C1 and / or C2) shown in FIG. 5A or an OCT scan for the supplementary cross section Cp shown in FIG. 5B. The OCT scan in this example is a repeated scan with respect to the same cross section, for example.

  When repetitive scanning is applied to the supplemental section Cp (or supplementary sections C1 and / or C2), it is possible to estimate the inclination of the blood vessel Db in parallel with the vignetting determination, or from the vignetting determination to the blood vessel of interest. A smooth transition to Db slope estimation is possible.

  When the supplementary cross section Cp is applied and there is no vignetting, a tomographic image Gp1 (cross section data) representing the form of the supplemental cross section Cp is obtained as shown in FIG. 7A. On the other hand, when there is vignetting, a tomographic image Gp2 (cross-sectional data) in which the form of the supplementary cross-section Cp is not depicted is obtained as shown in FIG. 7B. Note that, in a state where the alignment is suitable, the optical scanner 44 is disposed at a position substantially conjugate with the pupil of the eye E, so that the deflection center of the measurement light LS substantially coincides with the pupil. Therefore, when the measurement light LS is vignetted in the pupil, a tomographic image Gp2 (cross-section data) in which the shape of the supplementary cross-section Cp is not drawn is obtained.

  The vignetting determination unit 238 analyzes the tomographic image obtained by the OCT scan with respect to the supplementary cross section Cp, and determines whether the form of the supplemental cross section Cp is drawn. For example, the vignetting determination unit 238 may be configured to determine whether or not the inner boundary membrane region (M) is depicted in the tomographic image. The determination result that “the inner boundary membrane region is depicted in the tomographic image” corresponds to the determination result that “there is no vignetting”. Conversely, the determination result that “the inner boundary membrane region is not depicted in the tomographic image” corresponds to the determination result that “there is vignetting”.

  A second example of processing executed by the vignetting determination unit 238 will be described. In this example, the incident light for vignetting determination is illumination light for fundus photographing, and may be observation illumination light or photographing illumination light. The vignetting determination unit 238 analyzes the fundus image and determines whether or not a light amount decrease due to the vignetting has occurred. For example, the vignetting determination unit 238 determines whether there is a difference between the brightness of the center portion of the fundus image and the brightness of the peripheral portion (that is, whether the peripheral light amount has decreased). This determination is performed with reference to the values (typically luminance distribution) of the pixels constituting the fundus image, and includes image processing such as threshold processing and labeling, for example.

  According to the second example, the degree of vignetting can be easily determined. The degree of vignetting is evaluated based on, for example, the characteristics of an image area where the peripheral light amount is reduced in the fundus image. The vignetting determination unit 238 can calculate the evaluation value (for example, the size (area) of the peripheral light amount reduction region) in this way, and can determine the presence or absence of vignetting based on the size of the evaluation value. The “presence / absence of vignetting” in this example corresponds to, for example, whether or not the degree of vignetting exceeds a predetermined level. Typically, the vignetting determination unit 238 compares the calculated evaluation value with a threshold value, determines that “there is vignetting” when the evaluation value exceeds the threshold value, and when the evaluation value is equal to or less than the threshold value. It is determined that “no vignetting”.

  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. An example of the operation of the blood flow measuring device 1 is shown in FIG. It is assumed that preparatory processing such as patient ID input has already been performed.

(S1: Auto alignment started)
First, auto alignment is executed. The auto alignment is executed using an alignment index as described above, for example. Alternatively, as disclosed in Japanese Patent Application Laid-Open No. 2013-248376, it is also possible to execute auto alignment using two or more anterior segment cameras. The method of auto alignment is not limited to these.

(S2: Auto alignment completed)
When the relative position between the eye E and the optical system matches in all of the x direction, the y direction, and the z direction, the auto alignment is completed.

(S3: Start tracking)
When auto-alignment is completed, the blood flow measurement device 1 starts tracking for moving the optical system in accordance with the movement of the eye E (fundus Ef). Tracking includes, for example, an operation of acquiring an observation image of the fundus oculi Ef using infrared light, an operation of analyzing the observation image to detect the movement of the fundus oculi Ef, and an optical system in accordance with the detected movement of the fundus oculi Ef. This is realized by a combination with the movement of moving.

  Here, setting of fundus imaging conditions such as focus adjustment for the fundus oculi Ef, setting of OCT measurement conditions such as optical path length adjustment, and the like can be executed. In addition, selection of a target blood vessel, setting of a target cross section, setting of a supplemental cross section, and the like can be performed at this stage or at any other timing. In this operation example, it is assumed that the target blood vessel Db, the target cross section C0, and the supplementary cross section Cp shown in FIG. 5B are set.

(S4: Move the optical system by a predetermined distance)
At this stage, the apex of the cornea (or the center of the pupil) and the optical axis of the optical system substantially coincide with each other in the xy direction, and the distance between the eye E and the optical system (objective lens 22) in the z direction becomes a working distance. It almost matches.

  The main control unit 211 controls the moving mechanism 150 to move the optical system by a predetermined distance in a predetermined direction on the xy plane. In other words, the main control unit 211 applies the first movement control for moving the optical system by a predetermined distance from the optical axis of the optical system to the moving mechanism 150 in a predetermined direction orthogonal to the optical axis of the optical system. Thereby, the optical axis of the optical system is moved from a position H0 substantially coincident with the corneal apex (or pupil center) in the xy direction to a position H1 that is separated by a predetermined distance in the upper left direction.

  The movement direction (initial movement direction) of the optical system in the first movement control may be arbitrary and is set in advance. The movement distance (initial movement amount) of the optical system in the first movement control may be arbitrary, for example, may be a default distance. Although details will be described later, the initial movement amount may be, for example, a distance set according to the presence or absence of mydriasis, or a distance set according to the pupil diameter of the eye E to be examined. Also good.

(S5: Determine the presence or absence of vignetting)
After step S4, the main control unit 211 performs an OCT scan for vignetting determination.
The scanning of the supplementary cross section Cp shown in FIG. 5B is started. The vignetting determination unit 238 determines the presence or absence of vignetting based on the cross-sectional data acquired by the OCT scan. For example, the image forming unit 220 (tomographic image forming unit 221) forms a tomographic image of the supplementary cross section Cp from the data acquired by this OCT scan, and the vignetting determination unit 238 has the form of the supplemental cross section Cp in the tomographic image. The presence or absence of vignetting is determined by determining whether or not the image is drawn.

(S6: Movement complete?)
If the predetermined condition (movement completion condition) is satisfied, it is determined that the movement of the optical system is completed (S6: Yes), and the process proceeds to step S8. If the movement completion condition is not satisfied (S6: No), the process proceeds to step S7. The movement completion condition will be described later.

(S7: Fine movement of the optical system)
When it is determined in step S6 that the movement completion condition is not satisfied (S6: No), the main control unit 211 finely adjusts the position of the optical system based on the determination result obtained in step S5. The second movement control is applied to the movement mechanism 150.

  As an example, when it is determined in step S5 that no vignetting has occurred, the main control unit 211 executes the second movement control so as to further move the optical system in the initial movement direction. For example, as shown in FIG. 9B, when the optical axis position H1 after the first movement control is inside the pupil Ep, the OCT scan of the supplementary section Cp is preferably executed, and the supplementary section Cp is shown in FIG. 7A. A tomographic image in which the form of the image is depicted is obtained. As a result, the vignetting determination unit 238 determines that vignetting has not occurred. As indicated by reference numeral J1 in FIG. 9B, the main control unit 211 controls the moving mechanism 150 to move the optical system by a predetermined distance (predetermined fine movement amount) in the initial movement direction. As described above, when it is determined in step S5 that no vignetting has occurred, the optical axis of the optical system is in the direction toward the outer edge of the pupil Ep (that is, in the direction away from the optical axis position H0 immediately after auto-alignment). Is moved.

  Conversely, when it is determined in step S5 that vignetting has occurred, the main control unit 211 executes second movement control so as to move the optical system in a direction opposite to the initial movement direction. For example, as shown in FIG. 9C, when the optical axis position H1 after the first movement control is outside the pupil Ep, the measurement light LS is blocked by the glow or the like, and the form of the supplementary cross section Cp as shown in FIG. 7B. A tomographic image in which is not drawn is obtained. As a result, the vignetting determination unit 238 determines that vignetting has occurred. As indicated by reference numeral J2 in FIG. 9C, the main control unit 211 controls the moving mechanism 150 so as to move the optical system by a predetermined distance (predetermined fine movement amount) in the direction opposite to the initial movement direction. Thus, if it is determined in step S5 that vignetting has occurred, the optical axis of the optical system is moved in the direction toward the optical axis position H0 immediately after auto-alignment.

  After the optical system is finely moved, the process returns to step S5. Steps S5 to S7 are repeated until “Yes” is determined in step S6. Note that it is possible to output an error determination when steps S5 to S7 are repeated a predetermined number of times, or when steps S5 to S7 are repeated for a predetermined time.

  The movement completion conditions in step S6 will be described. For example, the movement completion condition is a state in which vignetting has not occurred and the optical system is disposed at a position where the displacement from the position of the optical axis immediately before the first movement control is maximized. In this case, the main control unit 211 determines that the vignetting determination unit 238 determines that there is no vignetting, and the optical system is arranged at a position where the displacement from the position of the optical axis immediately before the first movement control is maximized. Steps S5 to S7 (second movement control) are repeatedly executed.

  As an example, when it is determined that there is vignetting after fine movement in the initial movement direction, the movement completion condition of this example is satisfied by returning the optical system to the optical axis position before this fine movement. As another example, when it is determined that there is no vignetting after fine movement in the direction opposite to the initial movement direction, the position of the optical system after this fine movement satisfies the movement completion condition of this example.

  Note that the determination of whether or not the movement completion condition of this example is satisfied is not limited to these examples. Further, the movement completion condition is not limited to that in this example.

(S8: Estimate the inclination of the blood vessel of interest)
If it is determined in step S6 that the movement of the optical system has been completed (S6: Yes), the blood flow measuring device 1 estimates the inclination of the blood vessel Db of interest. For example, the cross-sectional data of the supplemental cross-section Cp is used for the inclination estimation in this example, as in the vignetting determination.

(S9: Execute blood flow measurement)
When the estimated value of the inclination of the blood vessel Db of interest is obtained in step S8, the blood flow measurement device 1 performs blood flow measurement of the cross section of interest C0 as described above, and generates blood flow information.

  A modification of the operation described above will be described. As described above, in fundus blood flow measurement using OCT, it is important that an angle (measurement angle) formed by the direction of the target blood vessel Db and the incident direction of the measurement light LS is suitable.

  Therefore, the display unit 241 displays the measurement angle value (estimated value) obtained by the inclination estimation unit 233 and a preset suitable measurement angle (target angle) value, thereby allowing the measurement angle and the target value to be displayed. It is possible to present the angle to the user. This display control is executed by the main control unit 211.

  For example, the target angle is set in a range of 78 degrees to 85 degrees, and more preferably in a range of 80 degrees to 85 degrees. The target angle may be a single value or a range defined by an upper limit and / or a lower limit. The target angle is, for example, a default value, a default range, a value or range set by a user or another person (for example, a maintenance service person), a blood flow measurement device 1 or another device (for example, a medical institution server, and It may be either a value or a range set by the device that monitors the operation of the blood flow measuring device 1. As an example when the blood flow measurement device 1 or the like is set, a target angle previously applied to the eye E is set again, a target angle is set according to the attributes of the subject, The target angle can be set according to the attribute of the eye E.

  In this example, the main control unit 211 can cause the display unit 241 to display the measurement angle obtained by the inclination estimation unit 233 together with the target angle at an arbitrary timing after the first movement control. Typically, the main control unit 211 causes the display unit 241 to display the measurement angle obtained by the tilt estimation unit 233 together with the target angle after the first movement control, or the tilt estimation unit 233 after the second movement control. The measurement angle obtained by the above can be displayed on the display unit 241 together with the target angle.

  The user can input an instruction with reference to the measurement value of the measurement angle and the value of the target angle. For example, when a measurement angle that is (substantially) coincident with the target angle is obtained, the user can input a blood flow measurement start instruction using the operation unit 242. Further, the main control unit 211 compares the measurement value of the measurement angle with the target angle, executes blood flow measurement start control when they are (almost) coincident, and if they do not coincide with each other, further control is performed. Two movement control may be performed.

  Even if the second movement control is repeatedly performed, a suitable measurement angle may not be obtained. In this case, the user can change the target angle using the operation unit 242. In addition, the blood flow measurement device 1 can change the target angle. For example, when the second movement control is repeated a predetermined number of times, or when the second movement control is executed for a predetermined time, the main control unit 211 can change the target angle. A range in which the target angle can be changed may be set in advance.

  When the target angle is changed, the main control unit 211 can execute the first movement control again. For example, in response to the change of the target angle, the main control unit 211 can re-execute step S4 of the operation shown in FIG. 8 and re-execute the processes after step S5.

  When the value of the measurement angle obtained by the inclination estimation unit 233 matches (almost) the target angle, the main control unit 211 can start blood flow measurement and acquire blood flow information. Typically, when the value of the measurement angle obtained by the inclination estimation unit 233 after the second movement control matches (almost) the target angle, the main control unit 211 can start blood flow measurement. .

  According to such a modification, the blood flow measuring device 1 can be used as follows. Assume that the initial value of the target angle is set to 80 degrees. If the measurement angle of 80 degrees is not achieved even when the second movement control is repeatedly performed, the user changes the target angle to 78 degrees, for example. The blood flow measurement device 1 performs the first movement control again (S4), and further performs vignetting determination (S5), the second movement control, and the like. The user checks the value of the measurement angle obtained after the second movement control on the display unit 241 and inputs a blood flow measurement start instruction when the measurement angle of 78 degrees is achieved. If the measurement angle of 78 degrees is not achieved even after repeating the second movement control, for example, the user can select one of re-change of the target angle, re-measurement, and cancellation of 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 (1) of the embodiment includes a blood flow measurement unit, a moving mechanism, a control unit, and a determination unit.

  The blood flow measurement unit includes an optical system for applying an optical coherence tomography (OCT) scan, and acquires blood flow information based on data collected by the OCT scan. In the above embodiment, the optical system of the blood flow measurement unit includes the measurement arm shown in FIG. 1 and the optical system shown in FIG. Furthermore, the blood flow measuring unit includes an image forming unit 220 and a data processing unit 230 (blood flow information generating unit 232).

  The moving mechanism has a configuration for moving the optical system of the blood flow measurement unit. In the above embodiment, the moving mechanism includes the moving mechanism 150.

  The control unit applies a first movement control for moving the optical system by a predetermined distance from the optical axis in a first direction orthogonal to the optical axis of the optical system of the blood flow measurement unit to the moving mechanism. In the above embodiment, the control unit includes the main control unit 211. As illustrated in FIG. 9A, the main control unit 211 performs first movement control for moving the measurement arm (its optical axis) to a position H1 that is a predetermined distance away from the optical axis position H0 immediately after auto-alignment in the upper left direction. Is applied to the moving mechanism 150.

  A determination part determines the presence or absence of vignetting based on the detection result of the return light of the light incident on the eye to be examined via the optical system of the blood flow measurement part after the first movement control. In the above embodiment, the determination unit includes the vignetting determination unit 238.

  The light incident on the subject's eye for vignetting determination may be light for OCT scanning (for example, measurement light LS) or light for fundus imaging (for example, observation illumination light or imaging illumination light). In addition, light dedicated to vignetting determination may be used, or any other light may be used.

  The light incident on the subject's eye for vignetting determination may typically be light for blood flow measurement (light for OCT scanning) or light incident coaxially thereto.

  When light for blood flow measurement and light incident non-coaxially are used for vignetting determination, the light for blood flow measurement and the light for vignetting determination pass through substantially the same position at or near the pupil. Thus, the optical system can be configured.

  Alternatively, when light for non-coaxial incidence with light for blood flow measurement is used for vignetting determination, the light path for blood flow measurement and the light path for vignetting determination should be known or recognizable. For example, it is possible to perform light vignetting determination for blood flow measurement based on the relative positional relationship of these paths and the light vignetting state for vignetting determination.

  The control unit applies the second movement control for further moving the optical system of the blood flow measurement unit to the movement mechanism based on the determination result obtained by the determination unit.

  According to such an embodiment, in the offset operation of the measurement arm for obtaining an optimal Doppler signal in fundus blood flow measurement, the vignetting determination is performed after the measurement arm is offset by a predetermined distance by the first movement control. The position of the measurement arm can be adjusted by performing the second movement control according to the result. Therefore, compared with the method of gradually increasing the amount of offset of the measurement arm with respect to the optical axis of the eye to avoid vignetting due to the pupil, it is possible to shorten the time until the optimum offset position is achieved. it can. As a result, the burden on the subject can be reduced.

  In the embodiment, after the first movement control, the optical system of the blood flow measurement unit may collect cross-sectional data by applying an OCT scan to a cross-section along the blood vessel of interest in the fundus. Furthermore, the determination unit may determine the presence or absence of vignetting based on the cross-sectional data. In the above embodiment, the OCT scan is applied to the supplementary cross section Cp shown in FIG. 5B to acquire cross section data (supplemental tomographic image), and the presence or absence of vignetting can be determined based on this cross section data (FIG. 7A, FIG. 7B).

  In the embodiment, the estimated value of the inclination of the target blood vessel may be obtained based on the cross-sectional data collected by applying the OCT scan to the cross section of the fundus along the target blood vessel (inclination estimation unit). In the above embodiment, the inclination estimation unit 233 can obtain the inclination of the blood vessel Db itself or the inclination of the inner boundary membrane that approximates the inclination.

  According to such a configuration, the OCT scan is applied to the cross section of the fundus at the fundus of interest in both the OCT scan for vignetting determination and the OCT scan for blood vessel inclination estimation. Therefore, blood vessel inclination estimation can be performed, and a smooth transition from vignetting determination to blood vessel inclination estimation is possible. Thereby, the measurement time can be shortened, and the burden on the subject can be reduced.

  In the embodiment, the control unit causes the display unit to display an estimated value of the inclination of the target blood vessel obtained by the inclination estimation unit after the second movement control and a preset target value of the inclination. In the above embodiment, the main control unit 211 estimates the inclination of the target blood vessel Db obtained by the inclination estimation unit 233 at any timing after the first movement control (for example, after the second movement control) ( Measurement angle) and a target value (target angle) set in advance can be displayed on the display unit 241.

  According to such a configuration, the user can recognize the measurement angle of the target blood vessel, and can further compare the measurement angle with the target angle. Thereby, it is possible to arbitrarily input an instruction to start or stop blood flow measurement.

  In the embodiment, the user can change the target angle by using the operation unit (242). When the target angle is changed, the control unit can execute the first movement control again.

  According to such a configuration, first, the user can arbitrarily change the target angle. Furthermore, in response to the change of the target angle, the offset operation of the measurement arm for obtaining an optimal Doppler signal in fundus blood flow measurement can be performed again. As a result, when a suitable offset state cannot be obtained even by repeating the second movement control, it is possible to reset the target angle and search for a suitable offset position again.

  In the embodiment, when the estimated value of the inclination of the blood vessel of interest obtained by the inclination estimation unit after the second movement control substantially matches a preset target value of the inclination, the control unit controls the blood flow measurement unit. Blood flow information can be acquired. In the above-described embodiment, the main control unit 211 can start blood flow measurement in response to the measurement angle (almost) coincident with the target angle.

  According to such a configuration, blood flow measurement can be automatically started in response to obtaining a suitable measurement angle. Thereby, the timing at which a suitable measurement angle is obtained is not missed, and the measurement time can be shortened.

  In the embodiment, when the determination unit determines that there is no vignetting, the control unit performs the second movement so as to further move the optical system of the blood flow measurement unit in the same first direction as the movement direction in the first movement control. Control can be performed. Conversely, when the determination unit determines that there is vignetting, the control unit can execute the second movement control so as to move the optical system of the blood flow measurement unit in the direction opposite to the first direction.

  If it is determined that there is no vignetting, the optical axis of the measurement arm is considered to be located inside the pupil of the eye to be examined. is there. Therefore, in the embodiment, the optical system of the blood flow measurement unit is further moved in the same first direction as the movement direction in the first movement control to search for a more suitable offset position.

  On the other hand, if it is determined that there is vignetting, the optical axis of the measurement arm is considered to be located outside the pupil of the eye to be inspected, so that the blood flow measurement unit has a direction opposite to the movement direction in the first movement control. The offset position is adjusted so that the optical axis of the measurement arm passes through the inside of the pupil by moving the optical system.

  According to such a configuration, the offset amount of the measurement arm can be maximized in a range where vignetting does not occur.

  In the embodiment, the control unit determines that there is no vignetting by the determination unit, and continues until the optical system is arranged at a position where the displacement from the position of the optical axis immediately before the first movement control is maximized. The movement control can be repeatedly executed.

  In the above embodiment, the main control unit 211 determines that the vignetting determination unit 238 determines that there is no vignetting, and the position where the offset amount from the position H0 of the optical axis of the measurement arm immediately before the first movement control is maximized. The second movement control can be repeatedly executed until the optical axis of the measurement arm is arranged. Furthermore, when the offset amount of the measurement arm is maximized in a range where vignetting does not occur, the main control unit 211 can start blood flow measurement.

<Second Embodiment>
As described in the operation example of the first embodiment, tracking for moving the optical system in accordance with the movement of the eye to be examined (fundus) may be applied to fundus blood flow measurement. In the fundus blood flow measurement, an OCT scan is performed for about several seconds, so that tracking is generally applied to reduce the influence of eye movement.

  As described above, tracking typically includes an operation of acquiring an infrared observation image of the fundus, an operation of analyzing the infrared observation image to detect the movement of the fundus, and a detected movement of the fundus. In addition, this is realized by a combination with an operation for controlling the moving mechanism (that is, an operation for causing the optical system to follow the movement of the fundus).

  An example of the configuration of the blood flow measurement device according to the present embodiment will be described with reference to FIG. The data processing unit 230A is applied instead of the data processing unit 230 (FIGS. 3 and 4) of the first embodiment. Any element other than the data processing unit 230 among the elements of the blood flow measurement device 1 according to the first embodiment can be applied to the present embodiment. Hereinafter, the elements in the first embodiment will be applied mutatis mutandis as necessary.

  The data processing unit 230A includes a motion detection unit 251 and an image evaluation unit 252 in addition to the element group in the data processing unit 230 shown in FIG.

  The blood flow measurement device according to the present embodiment can acquire an infrared observation image of the fundus oculi Ef using an observation system (the illumination optical system 10 and the photographing optical system 30). The infrared observation image includes a time-series image group (frame group) acquired at a predetermined time interval.

  The motion detection unit 251 detects the motion of the fundus oculi Ef by analyzing the frame acquired by the observation system. This motion detection may be applied to all the frames acquired by the observation system, or may be applied to only a part of them.

  The motion detection unit 251 includes, for example, a first process for identifying an image region (feature region) corresponding to a feature part of the fundus oculi Ef (for example, an optic disc, macular, blood vessel, lesion, laser treatment mark, etc.) from the frame; A second process is performed for obtaining a time-series change in the positions of the plurality of feature regions specified from the plurality of frames (a time-series change in the rendering positions of the feature regions in the time-series image group).

  In one example, the first process and the second process are executed in real time in parallel with the acquisition of an infrared observation image by the observation system. The first process is executed so as to identify the feature region by sequentially analyzing the frames sequentially acquired by the observation system. Further, the second process is executed so as to sequentially calculate the displacement of the rendering position of the feature region between two temporally adjacent frames.

  The main control unit 211 applies, to the movement mechanism 150, control for moving the optical system (including at least the measurement arm) in accordance with the movement of the fundus oculi Ef detected by the movement detection unit 251. Thereby, tracking is realized.

  The image evaluation unit 252 evaluates the infrared observation image (time series image group, frame group) acquired by the observation system. This evaluation may be an evaluation of whether or not the infrared observation image is suitable for tracking, and is typically light for acquiring the infrared observation image (eg, observation illumination light and / or its return) Including determination of the presence or absence of vignetting. When vignetting is present, a decrease in the amount of peripheral light in the infrared observation image is detected. The evaluation of the infrared observation image in the present embodiment may be executed, for example, in the same manner as the “second example of processing executed by the vignetting determination unit 238” described in the first embodiment.

  The main control unit 211 can execute the second movement control similar to the first embodiment based on the determination result obtained by the vignetting determination unit 238 and the evaluation result obtained by the image evaluation unit 252. . Also in this embodiment, the main control unit 211 applies the first movement control for moving the measurement arm by a predetermined distance from the optical axis to the movement mechanism 150 in the first direction orthogonal to the optical axis of the measurement arm. Second movement control for further moving the measurement arm based on the determination result obtained by the vignetting determination unit 238 is applied to the moving mechanism 150.

  In other words, in the present embodiment, the second movement control is executed in consideration of vignetting determination and infrared observation image evaluation. An example of such processing will be described below.

  When the vignetting determination unit 238 determines that there is no vignetting, and the image evaluation unit 252 evaluates that the infrared observation image is good, the main control unit 211 performs optical in the same first direction as the first movement control. The second movement control can be executed so as to further move the system (measurement arm).

  Conversely, when the vignetting determination unit 238 determines that there is vignetting, or when the image evaluation unit 252 evaluates that the infrared observation image is not good, the main control unit 211 performs a direction opposite to the first direction. The second movement control can be executed so as to move the optical system (measurement arm).

  Further, the main control unit 211 determines that there is no vignetting by the vignetting determination unit 238, the image evaluation unit 252 evaluates that the infrared observation image is good, and the position of the optical axis immediately before the first movement control. It is possible to repeatedly execute the second movement control until the optical system (the objective lens 22 of the measurement arm) is disposed at a position where the displacement from (H0) is maximized.

  According to the present embodiment, it is possible to execute the offset operation of the measurement arm to obtain an optimal Doppler signal in fundus blood flow measurement while performing tracking appropriately. Therefore, it is possible to avoid an error in the offset operation due to the tracking failure and to further reduce the burden on the subject.

<Third Embodiment>
The blood flow measurement device according to the present embodiment can set an initial movement amount (for example, a distance between the position H0 and the position H1 in FIG. 9A) that is the movement distance of the optical system in the first movement control. is there.

  An example of the configuration of the blood flow measurement device according to the present embodiment will be described with reference to FIG. The control unit 210A is applied instead of the control unit 210 (FIGS. 3 and 4) of the first embodiment. Note that any element other than the control unit 210 among the elements of the blood flow measurement device 1 according to the first embodiment can be applied to the present embodiment. Hereinafter, the elements in the first embodiment will be applied mutatis mutandis as necessary. Note that the blood flow measurement device according to the present embodiment may include one of the data processing unit 230 and the data processing unit 230A.

  210 A of control parts contain the movement distance setting part 213 in addition to the element group in the control part 210 shown in FIG.

  When the eye E is a small pupil eye or a cataract eye, or when the blood vessel of interest is located in the periphery of the fundus oculi Ef, a drug (mydriatic agent) for dilating the pupil is used as the eye E. May apply. The movement distance setting unit 213 is configured to set an initial movement amount depending on whether or not a mydriatic is applied to the eye E. The movement distance setting unit 213 is an example of a first setting unit.

  An example of the movement distance setting unit 213 will be described. The exemplary movement distance setting unit 213 calculates an initial movement amount (first initial movement amount) when the mydriatic agent is not applied and a movement distance (second initial movement amount) when the mydriatic agent is applied. Pre-stored. The first initial movement amount is set to, for example, a half value of a standard pupil diameter (a radius of a standard size pupil). The second initial movement amount is set to a value that is half the diameter of the dilated pupil when a mydriatic agent is applied to an eye with a standard pupil diameter. In addition, you may make it memorize | store in advance the initial movement amount according to the attribute (age, sex, etc.) of a subject, and the initial movement amount according to the attribute of the eye to be examined.

  For example, the user inputs whether or not the mydriatic is applied to the eye E using the operation unit 242. Or you may make it determine whether a mydriatic agent was applied with reference to a test subject's electronic medical record etc. FIG.

  The movement distance setting unit 213 selects one of the plurality of stored initial movement amounts based on information indicating whether or not a mydriatic is applied to the eye E. The main control unit 211 executes the first movement control by applying the initial movement amount selected by the movement distance setting unit 213.

  According to the present embodiment, the initial movement amount in the first movement control can be set according to the size of the pupil of the eye E (particularly, the pupil diameter depending on whether or not a mydriatic agent is applied). In the offset operation of the measurement arm for obtaining the optimal Doppler signal in blood flow measurement, it is possible to further shorten the time until the optimal offset position is achieved. Thereby, it is possible to further reduce the burden on the subject.

<Fourth Embodiment>
The blood flow measurement device according to the present embodiment can set an initial movement amount (for example, a distance between the position H0 and the position H1 in FIG. 9A) that is the movement distance of the optical system in the first movement control. is there. In the third embodiment, the initial movement amount is set according to whether or not the mydriatic is applied, but in this embodiment, the initial movement amount is set according to the actual pupil diameter of the eye E.

  An example of the configuration of the blood flow measurement device according to the present embodiment will be described with reference to FIG. The blood flow measurement device according to the present embodiment includes a pupil diameter information acquisition unit 260. Further, the control unit 210B is applied instead of the control unit 210 (FIGS. 3 and 4) of the first embodiment. Note that any element other than the control unit 210 among the elements of the blood flow measurement device 1 according to the first embodiment can be applied to the present embodiment. Hereinafter, the elements in the first embodiment will be applied mutatis mutandis as necessary. Note that the blood flow measurement device according to the present embodiment may include one of the data processing unit 230 and the data processing unit 230A.

  The pupil diameter information acquisition unit 260 acquires the value of the pupil diameter of the eye E to be examined. For example, the pupil diameter information acquisition unit 260 includes an element for measuring the pupil diameter of the eye E. As a specific example, the pupil diameter information acquisition unit 260 analyzes the anterior segment image of the eye E acquired by the illumination optical system 10 and the imaging optical system 30, identifies the pupil region, and calculates the diameter thereof. May be included. The specification of the pupil region may include processing such as threshold processing and edge detection. The calculation of the diameter of the pupil region may include processing such as elliptical approximation and circular approximation.

  In another example, the pupil diameter information acquisition unit 260 acquires the measured value of the pupil diameter of the eye E acquired in the past from the electronic medical record of the subject. The pupil diameter information acquisition unit 260 of this example includes a communication device for accessing an apparatus in which an electronic medical record or the like is stored.

  Control unit 210B includes a movement distance setting unit 214 in addition to the element group in control unit 210 shown in FIG. The movement distance setting unit 214 can set the initial movement amount in the first movement control based on the pupil diameter value acquired by the pupil diameter information acquisition unit 260. The movement distance setting unit 214 can set, for example, a half value of the pupil diameter value acquired by the pupil diameter information acquisition unit 260 as the initial movement amount. This initial movement amount corresponds to the value of the radius of the pupil of the eye E or the approximate value thereof. The movement distance setting unit 214 is an example of a second setting unit.

  The main control unit 211 executes the first movement control by applying the initial movement amount selected by the movement distance setting unit 214.

  According to this embodiment, since the initial movement amount in the first movement control can be set based on the actual measurement value of the pupil diameter of the eye E, in order to obtain an optimal Doppler signal in fundus blood flow measurement. In the offset operation of the measurement arm, it is possible to further shorten the time until the optimum offset position is achieved. Thereby, it is possible to further reduce the burden on the subject.

  The embodiments described above are merely exemplary aspects of the 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 210 Control part 211 Main control part 210A Control part 213 Movement distance setting part 210B Control part 214 Movement distance setting part 220 Image formation part 230 Data processing part 232 Blood flow information generation part 233 Inclination estimation part 238 Errection determination part 230A Data processing unit 251 Motion detection unit 252 Image evaluation unit 260 Pupil diameter information acquisition unit

Claims (14)

A blood flow measurement unit that includes an optical system for applying an optical coherence tomography (OCT) scan to the fundus of the subject's eye, and acquires blood flow information based on data collected by the OCT scan;
A moving mechanism for moving the optical system;
A controller that applies, to the moving mechanism, first movement control for moving the optical system by a predetermined distance from the optical axis in a first direction orthogonal to the optical axis of the optical system;
A determination unit that determines the presence or absence of vignetting based on the detection result of the return light of the light incident on the eye to be examined via the optical system after the first movement control;
The control unit applies second movement control for further moving the optical system to the moving mechanism based on a determination result obtained by the determination unit;
Blood flow measuring device. After the first movement control, the optical system collects cross-sectional data by applying an OCT scan to a cross-section along the blood vessel of interest in the fundus,
The blood flow measuring device according to claim 1, wherein the determination unit determines the presence or absence of the vignetting based on the cross-sectional data. The blood flow measurement device according to claim 2, further comprising an inclination estimation unit that obtains an estimated value of the inclination of the blood vessel of interest based on the cross-sectional data. The said control part displays the estimated value of the said inclination calculated | required by the said inclination estimation part after the said 2nd movement control, and the preset target value of an inclination on a display means. The blood flow measuring device according to 1. Further including an operation unit;
The blood flow measurement device according to claim 4, wherein when the target value is changed using the operation unit, the control unit executes the first movement control again. When the estimated value of the inclination obtained by the inclination estimation unit after the second movement control substantially matches a preset inclination target value, the control unit controls the blood flow measurement unit. The blood flow measurement device according to any one of claims 3 to 5, wherein the blood flow information is acquired. When the determination unit determines that there is no vignetting, the control unit executes the second movement control to further move the optical system in the first direction,
The said control part performs the said 2nd movement control so that the said optical system may be moved to the opposite direction of the said 1st direction, when the said determination part determines with the said vignetting. The blood flow measuring device according to any one of 1 to 6. The control unit determines that there is no vignetting by the determination unit, and until the optical system is disposed at a position where the displacement from the position of the optical axis immediately before the first movement control is maximized. The blood flow measuring device according to claim 7, wherein the second movement control is repeatedly executed. An observation system for acquiring an infrared observation image of the fundus;
And an evaluation unit for evaluating the infrared observation image,
The said control part performs said 2nd movement control based on the determination result obtained by the said determination part, and the evaluation result obtained by the said evaluation part. The any one of Claims 1-6 characterized by the above-mentioned. The blood flow measuring device described. When the determination unit determines that there is no vignetting and the evaluation unit evaluates that the infrared observation image is good, the control unit further moves the optical system in the first direction. The second movement control is executed as follows:
When the determination unit determines that the vignetting is present, or when the evaluation unit evaluates that the infrared observation image is not good, the control unit performs the optical system in a direction opposite to the first direction. The blood flow measurement device according to claim 9, wherein the second movement control is executed so as to move the blood flow. The controller determines that the vignetting is absent by the determination unit, evaluates that the infrared observation image is good by the evaluation unit, and determines the position of the optical axis immediately before the first movement control. The blood flow measurement device according to claim 10, wherein the second movement control is repeatedly executed until the optical system is arranged at a position where the displacement is maximum. A motion detection unit that analyzes the infrared observation image and detects the movement of the fundus;
The said control part applies the tracking control for moving the said optical system according to the motion of the said fundus detected by the said motion detection part to the said movement mechanism. The any one of Claims 9-11 characterized by the above-mentioned. The blood flow measuring device according to 1. The first setting unit that sets the predetermined distance in the first movement control according to whether or not a mydriatic agent is applied to the eye to be examined is further included. Blood flow measuring device. Pupil diameter information acquisition unit for acquiring the value of the pupil diameter of the eye to be examined;
The blood flow measuring device according to any one of claims 1 to 12, further comprising: a second setting unit that sets the predetermined distance in the first movement control based on a value of the pupil diameter.

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