JP7096116B2 - Blood flow measuring device - Google Patents

Description

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

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

In order to obtain the optimum Doppler signal in fundus blood flow measurement, it is necessary to inject light at an appropriate angle with respect to the blood flow direction (traveling direction of blood vessels). Therefore, the incident light may be offset with respect to the optical axis of the eye. At this time, the angle of incidence on the blood vessel changes according to the direction and amount of the offset. Therefore, in order to realize a suitable incident angle, it is required to optimize the offset position.

Japanese Unexamined Patent Publication No. 2017-42602

An object of the present invention is to optimize the offset position of the incident light for measuring the blood flow in the fundus.

The blood flow measuring device according to the first aspect of the embodiment includes a scan optical system that applies an optical coherence stromography (OCT) scan to the fundus of the eye to be inspected, a moving mechanism for moving the scan optical system, and the scan. An image forming unit that forms an image from the first data collected by the optical system, a direction setting unit that analyzes the image and sets a first direction orthogonal to the optical axis of the scanning optical system, and the scanning optics. Blood flow information is obtained from the control unit that applies the first movement control for moving the system in the first direction to the movement mechanism and the second data collected by the scan optical system after the first movement control. Includes the blood flow information acquisition unit to be acquired.

The second aspect of the embodiment is the blood flow measuring device of the first aspect, in which the scan optical system applies an OCT scan to a cross section along a blood vessel of interest in the fundus to collect the first data. The direction setting unit analyzes the image of the cross section formed from the first data to set the first direction, and after the first movement control, the scan optical system attaches the scan optical system to the blood vessel of interest. An OCT scan is applied to collect the second data.

The third aspect of the embodiment is the blood flow measuring device of the second aspect, in which the direction setting unit analyzes an image of the cross section to obtain an estimated value of the inclination of the blood vessel of interest, and the inclination is the same. The first direction is set based on the estimated value.

A fourth aspect of the embodiment is the blood flow measuring device of the third aspect, wherein the direction setting unit analyzes an image of the cross section to identify an image region corresponding to the surface of the fundus, and the above-mentioned The estimated value of the inclination is obtained based on the image area.

A fifth aspect of the embodiment is the blood flow measuring device of the third aspect, wherein the direction setting unit analyzes an image of the cross section to identify an image region corresponding to the blood vessel of interest, and the image. The estimated value of the inclination is obtained based on the region.

The sixth aspect of the embodiment is the blood flow measuring device according to any one of the second to fifth aspects, and the direction setting unit includes the incident angle of the OCT scan light on the blood vessel of interest within a predetermined range. The first direction is set as described above.

A seventh aspect of the embodiment is the blood flow measuring device according to any one of the first to sixth aspects, wherein the control unit moves the scan optical system in the first direction by a preset distance. The first movement control is executed so as to cause the movement.

The eighth aspect of the embodiment is the blood flow measuring device of the seventh aspect, in which the pupil diameter information acquisition unit for acquiring the pupil diameter information of the subject to be inspected and the distance are set based on the pupil diameter information. Further includes a first setting unit to be used.

A ninth aspect of the embodiment is the blood flow measuring device of the seventh aspect, further including a second setting unit that sets the distance depending on whether or not the mydriatic agent is applied to the eye to be inspected. ..

A tenth aspect of the embodiment is the blood flow measuring device according to any one of the first to ninth aspects, in which light incident on the eye to be inspected via the scan optical system after the first movement control. A determination unit for determining the presence or absence of vignetting based on the detection result of the return light of the above is further included, and the control unit further moves the scan optical system according to the determination result obtained by the determination unit. 2 The movement control is applied to the movement mechanism.

The eleventh aspect of the embodiment is the blood flow measuring device of the tenth aspect, and when the determination unit determines that there is no vignetting, the scan optical system collects the second data. The OCT scan of is applied to the fundus.

The twelfth aspect of the embodiment is the blood flow measuring device of the tenth or eleventh aspect, and when the determination unit determines that the vignetting is present, the control unit is in the first movement control. A second movement control for moving the scan optical system in a second direction opposite to the first direction by a distance shorter than the movement distance of the above is applied to the movement mechanism.

According to the embodiment, it is possible to optimize the offset position of the incident light for measuring the blood flow in the fundus.

It is a schematic diagram which shows an example of the structure of the blood flow measuring apparatus which concerns on embodiment. It is a schematic diagram which shows an example of the structure of the blood flow measuring apparatus which concerns on embodiment. It is a schematic diagram which shows an example of the structure of the blood flow measuring apparatus which concerns on embodiment. It is a schematic diagram which shows an example of the structure of the blood flow measuring apparatus which concerns on embodiment. It is a schematic diagram for demonstrating an example of the operation of the blood flow measuring apparatus which concerns on embodiment. It is a schematic diagram for demonstrating an example of the operation of the blood flow measuring apparatus which concerns on embodiment. It is a schematic diagram for demonstrating an example of the operation of the blood flow measuring apparatus which concerns on embodiment. It is a schematic diagram for demonstrating an example of the operation of the blood flow measuring apparatus which concerns on embodiment. It is a schematic diagram for demonstrating an example of the operation of the blood flow measuring apparatus which concerns on embodiment. It is a schematic diagram for demonstrating an example of the operation of the blood flow measuring apparatus which concerns on embodiment. It is a schematic diagram for demonstrating an example of the operation of the blood flow measuring apparatus which concerns on embodiment. It is a schematic diagram for demonstrating an example of the operation of the blood flow measuring apparatus which concerns on embodiment. It is a flowchart which shows an example of the operation of the blood flow measuring apparatus which concerns on embodiment. It is a schematic diagram for demonstrating an example of the operation of the blood flow measuring apparatus which concerns on embodiment. It is a schematic diagram for demonstrating an example of the operation of the blood flow measuring apparatus which concerns on embodiment. It is a schematic diagram for demonstrating an example of the operation of the blood flow measuring apparatus which concerns on embodiment.

The blood flow measuring device according to the exemplary embodiment will be described in detail with reference to the drawings. The blood flow measuring device of the embodiment collects data on the fundus of the eye using OCT and generates information (blood flow information) representing blood flow dynamics. The disclosure content of the literature cited herein and any other known technique can be incorporated into embodiments.

In the following embodiment, a blood flow measuring device capable of measuring the fundus of a living eye using a Fourier domain OCT (for example, a swept source OCT) will be described. The type of OCT is not limited to swept source OCT and may be, for example, spectral domain OCT or time domain OCT. The blood flow measuring device of 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 fundus photography devices include scanning laser ophthalmoscopes (SLOs), slit lamp microscopes, ophthalmologic operating microscopes, and the like.

<Constitution>
As shown in FIG. 1, the blood flow measuring 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 inspected. The OCT unit 100 is provided with a part of an optical system and a mechanism for executing OCT. Other parts of the optical system and mechanism for performing OCT are provided in the fundus camera unit 2. The arithmetic and control unit 200 includes one or more processors that perform various arithmetic and control. In addition to these, any element such as a member for supporting the subject's face (chin rest, forehead pad, etc.) and a lens unit for switching the target part of OCT (for example, an attachment for anterior ocular segment OCT). Or unit may be provided in the blood flow measuring device 1.

In the present specification, the "processor" is, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), a programmable logic device (for example, a SPLD (SimpleProgram)). It means a circuit such as Programgable Logical Device), FPGA (Field Programgable Gate Array)). The processor realizes the function according to the embodiment by reading and executing a program stored in a storage circuit or a storage device, for example.

<Fundus camera unit 2>
The fundus camera unit 2 is provided with an optical system for photographing the fundus Ef of the eye to be inspected E. The acquired image of the fundus Ef (called a fundus image, a fundus photograph, etc.) is a front image such as an observation image, a photographed image, or the like. The observed image is obtained by taking a moving image using near-infrared light. The captured 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 to be inspected with illumination light. The photographing optical system 30 detects the return light of the illumination light from the eye E to be inspected. The measurement light from the OCT unit 100 is guided to the eye E to be inspected 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 output from the observation light source 11 of the illumination optical system 10 (observation illumination light) is reflected by the concave mirror 12, passes through the condenser lens 13, passes through the visible cut filter 14, and becomes near-infrared light. Further, the observation illumination light is once focused 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 diaphragm 19, and the relay lens system 20. Then, the observation illumination light is reflected at the peripheral portion of the perforated mirror 21 (the region around the perforated portion), passes through the dichroic mirror 46, is refracted by the objective lens 22, and illuminates the eye E (fundament Ef) to be inspected. do. The return light of the observation illumination light from the eye E to be inspected 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. , It is reflected by the mirror 32 via the photographing focusing lens 31. Further, this return light passes through the half mirror 33A, is reflected by the dichroic mirror 33, and is imaged on the light receiving surface of the image sensor 35 by the condenser lens 34. The image sensor 35 detects the return light at a predetermined frame rate. The focus of the photographing optical system 30 is adjusted so as to match the fundus Ef or the anterior eye portion.

The light output from the photographing light source 15 (photographing illumination light) is applied to the fundus Ef through the same path as the observation illumination light. The return light of the photographing illumination light from the eye E to be examined 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.

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

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

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

The alignment optical system 50 generates an alignment index used for alignment of the optical system with respect to the eye E to be inspected. 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 portion of the perforated mirror 21, and passes through the dichroic mirror 46. It is transmitted and projected onto the eye E to be inspected through the objective lens 22. The return light (corneal reflex light, etc.) of the alignment light from the eye E to be inspected 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 past, the alignment index image of this example consists of two bright spot images whose positions change depending on the alignment state. When the relative position between the eye E to be inspected 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 to be inspected 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 inspected and the optical system in the z direction matches the predetermined working distance, the two bright spot images overlap. When the position of the eye to be inspected E and the position of the optical system match in the xy direction, two bright spot images are presented in or near a predetermined alignment target. When the distance between the eye E to be inspected and the optical system in the z direction matches the working distance, and the position of the eye E to be inspected and the position of the optical system in the xy direction match, the two bright spot images overlap and align. Presented within 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 the movement 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 displays two bright spot images on the display unit 241 together with the observation image of the eye E to be inspected, and the user uses the operation unit 242 while referring to the two displayed bright spot images. To operate the moving mechanism 150.

The focus optical system 60 generates a split index used for focus adjustment with respect to the eye E to be inspected. 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 photographing focusing lens 31 along the optical path (optical path) of the photographing optical system 30. The reflection rod 67 is inserted and removed from the illumination optical path. When adjusting the focus, the reflecting surface of the reflecting rod 67 is inclined and 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 index plate 63, passes through the two-hole diaphragm 64, is reflected by the mirror 65, and is reflected by the condenser lens 66. It is once imaged on the reflecting surface of the lens and reflected. 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 to be inspected via the objective lens 22. The return light (reflected light from the fundus, etc.) of the focus light from the eye E to be inspected is guided to the image sensor 35 through the same path as the return light of the alignment light. Manual focusing or auto focusing can be executed based on the received light image (split index image).

The 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 high-intensity hyperopia. The diopter correction lens 71 is a minus lens (concave lens) for correcting high-intensity myopia.

The dichroic mirror 46 synthesizes a fundus photography optical path and an OCT optical path (measurement arm). The dichroic mirror 46 reflects light in the wavelength band used for OCT and transmits light for fundus photography. The measuring arm is provided with 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 in this order from the OCT unit 100 side.

The retroreflector 41 is movable in the direction of the arrow shown in FIG. 1, whereby the length of the measuring arm is changed. The change of the optical path length of the measuring arm is used, for example, for correcting the optical path length according to the axial length, adjusting the interference state, and the like.

The dispersion compensating member 42 acts together with the dispersion compensating member 113 (described later) arranged 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 measuring arm to adjust the focus of the measuring 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 located at a position optically conjugate with the pupil of the eye E to be inspected. 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 performing a swept source OCT. This optical system includes an interference optical system. This interference optical system divides the light from the variable wavelength light source (wavelength sweep type light source) into the measurement light and the reference light, and interferes with the return light of the measurement light from the eye E to be inspected and the reference light via the reference optical path. It generates interference light and detects this interference light. 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 optical L0 is guided by the optical fiber 104 to the fiber coupler 105 and divided into the measurement optical LS and the reference optical 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 optical LR is guided to the collimator 111 by the optical fiber 110 and converted into a parallel light flux, and is guided to the retroreflector 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 with the optical path length of the measured light LS. The dispersion compensating member 113 acts together with the dispersion compensating member 42 arranged on the measurement arm to match the dispersion characteristics between the reference light LR and the measurement light LS. The retroreflector 114 is movable along the optical path of the reference light LR incident on it, thereby changing the length of the reference arm. The change of the optical path length of the reference arm is used, for example, for correcting the optical path length according to the axial length, adjusting the interference state, and the like.

The reference optical LR via the retroreflector 114 is converted from a parallel luminous flux to a focused luminous flux by the collimator 116 via the dispersion compensating member 113 and the optical path length correction member 112, and is incident on the optical fiber 117. The reference light LR incident on the optical fiber 117 is guided to the polarization controller 118 to adjust its polarization state, is guided to the attenuator 120 through the optical fiber 119 to adjust the amount of light, and is guided to the fiber coupler 122 through the optical fiber 121. Be guided.

On the other hand, the measurement optical 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 is converted into a parallel light beam by the collimator lens unit 40, the retroreflector 41, the dispersion compensation member 42, the OCT focusing lens 43, and the optical scanner 44. 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 to be inspected. The measurement light LS is scattered and reflected at various depth positions of the eye E to be inspected. The return light from the eye E to be inspected of the measurement light LS travels in the same path as the outward path in the opposite direction, is guided to the fiber coupler 105, and reaches the fiber coupler 122 via the optical fiber 128.

The fiber coupler 122 superimposes the measurement light LS incidented via the optical fiber 128 and the reference light LR incident via the optical fiber 121 to generate interference light. The fiber coupler 122 generates a pair of interference light LCs by branching the generated interference light at a predetermined branching ratio (for example, 1: 1). The pair of interference light LCs 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 detect each pair of interference light LCs, and outputs the difference between the pair of detection results obtained by these. The detector 125 sends this output (detection signal) to the data collection system (DAT) 130.

A clock KC is supplied to the data collection system 130 from the light source unit 101. The clock KC is generated in the light source unit 101 in synchronization with the output timing of each wavelength swept within a predetermined wavelength range by the tunable light source. The light source unit 101, for example, branches the light L0 of each output wavelength to generate two branched lights, optically delays one of the branched lights, synthesizes the branched lights, and produces the obtained combined light. It is detected and a clock KC is generated based on the detection result. The data collection 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 result of this sampling to the arithmetic control unit 200.

In this example, both the element for changing the optical path length of the measuring arm (for example, the retroreflector 41) and the element for changing the optical path length of the reference arm (for example, the retroreflector 114 or the reference mirror) are used. Although it is provided, only one element may be provided. Further, the element for changing the difference (optical path length difference) between the optical path length of the measurement arm and the optical path length of the reference arm is not limited to these, and may be any element (optical member, mechanism, etc.). ..

<Processing system>
3 and 4 show configuration examples of the processing system (arithmetic control system) of the blood flow measuring device 1. 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 that can operate according to a control program, and controls each unit (including the elements shown in FIGS. 1 to 4) of the blood flow measuring device 1.

The photographing focusing lens 31 arranged in the photographing optical path and the focus optical system 60 arranged in the illumination optical path are synchronously moved by a photographing focusing drive unit (not shown) under the control of the main control unit 211. The retroreflector 41 provided in the measurement arm is moved by the retroreflector (RR) drive unit 41A under the control of the main control unit 211. The OCT focusing lens 43 arranged on the measuring arm is moved by the OCT focusing driving unit 43A under the control of the main control unit 211. The optical scanner 44 provided on the measurement arm operates under the control of the main control unit 211. The retroreflector 114 arranged on the reference arm is moved by the retroreflector (RR) drive 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.

The moving mechanism 150, for example, moves at least the fundus camera unit 2 three-dimensionally. In a typical example, the moving mechanism 150 includes an x stage that can move in the ± x direction (horizontal direction), an x moving mechanism that moves the x stage, and a y stage that can move in the ± y direction (vertical direction). , The y-moving mechanism that moves the y-stage, the z-stage that can move in the ± z direction (depth direction), and the z-moving mechanism that moves the z-stage are included. 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 control unit 211 displays the fixative 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 fixative target displayed on the LCD 39. The movement of the fixative can be performed in any manner such as continuous movement, intermittent movement, and discrete movement. The mode of movement of the fixative position in this embodiment will be described later.

The fixative position is represented by, for example, the display position (pixel coordinates) of the fixative target image on the LCD 39. These coordinates are, for example, coordinates represented by a predefined two-dimensional coordinate system on the display screen of the LCD 39. When a fixative matrix is used, the fixative position is represented, for example, by the position (coordinates) of the lit light emitting part. These coordinates are, for example, coordinates represented by a predefined two-dimensional coordinate system on the array plane of a plurality of light emitting units.

<Memory unit 212>
The storage unit 212 stores various data. The data stored in the storage unit 212 includes an OCT image, a fundus image, and eye information to be inspected. The eye test information includes subject information such as patient ID and name, left eye / 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 Ef based on the signal (sampling data) input from the data collection system 130. The image forming unit 220 can form B-scan image data (two-dimensional tomographic image data) of the fundus Ef and phase image data. These OCT image data will be described later. The image forming unit 220 includes, for example, a processor that can operate according to an image forming program. In this specification, unless otherwise specified, "image data" and "image" based on the "image data" are not distinguished.

In the blood flow measurement of the present embodiment, two types of scans (main scan and supplementary scan) are performed on the fundus Ef.

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

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

An example of the case where the first supplementary cross section is applied is shown in FIG. 5A. In this example, as shown in the fundus image D, one attention section C0 located in the vicinity of the optic disc Da of the fundus Ef and two supplementary cross sections C1 and C2 located in the vicinity thereof intersect with the attention vessel Db. Is set to. One of the two supplementary cross sections C1 and C2 is located on the upstream side of the blood vessel Db of interest with respect to the cross section of interest C0, and the other is located on the downstream side of the blood vessel Db of interest. The cross section C0 of interest and the supplementary cross sections C1 and C2 are oriented so as to be substantially orthogonal to the traveling direction of the blood vessel Db of interest, for example.

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

In an exemplary blood flow measurement, the main scan is repeated over a period of time including at least one cardiac cycle of the patient's heart. Thereby, it becomes possible to obtain the blood flow dynamics in all the cardiac time phases. The time for executing the main scan may be a predetermined fixed time, or may be a time set for each patient or each examination. In the former case, a longer time than the standard cardiac cycle is set (eg 2 seconds). In the latter case, biometric data such as the patient's electrocardiogram can be referred to. Here, it is also possible to consider factors other than the cardiac cycle. Examples of this factor include the time required for the examination (burden on the patient), the response time of the optical scanner 44 (scanning time interval), the 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 part 221>
The tomographic image forming unit 221 forms a tomographic image (main tomographic image) representing a time-series change in morphology in the section of interest based on the sampling data obtained from the data collection system 130 in the main scan. This process will be described in more detail. The main scan repeatedly scans the cross section C0 of interest as described above. Sampling data is sequentially input from the data collection system 130 to the tomographic image forming unit 221 in response to this repeated scanning. The tomographic image forming unit 221 forms one main tomographic image corresponding to the tomographic section C0 based on the sampling data corresponding to each scan of the tomographic section C0 of interest. The tomographic image forming unit 221 forms a series of main tomographic images along the time series by repeating this process for the number of repetitions of the main scan. 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 the image quality (additional averaging of images).

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

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

The process for forming a tomographic image as illustrated above includes noise reduction (noise reduction), filter processing, fast Fourier transform (FFT), and the like, as in the conventional Fourier domain OCT. The fast Fourier transform converts the sampling data (interference signal, interferogram) obtained by the data collection system 130 into an A-line profile (reflection intensity profile along the z direction). By imaging the A-line profile (that is, by assigning pixel values to the reflection intensity values), an A-scan image is obtained. By arranging a plurality of A scan images according to a scan pattern, a two-dimensional tomographic image such as a B scan image or a circle scan image can be obtained. In the case of other types of OCT devices, the tomographic image forming unit 221 performs a known process according to the type.

<Phase image forming unit 222>
The phase image forming unit 222 forms a phase image showing the 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 scan. 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 method for forming a phase image will be described. The phase image of this example is obtained by calculating the phase difference of adjacent A-line complex signals (that is, signals corresponding to adjacent scanning points). In other words, the phase image of this example is formed based on the time-series change of the pixel value (luminance value) of the main tomographic image. For any pixel of the main tomographic image, the phase image forming unit 222 creates a graph of the time-series change of the luminance value of the pixel. The phase image forming unit 222 obtains the phase difference Δφ between two time points t1 and t2 (t2 = t1 + Δt) separated by a predetermined time interval Δt in this graph. Then, this phase difference Δφ is defined as the phase difference Δφ (t1) at the time point t1 (more generally, any time point between the time point t1 and the time point t2). By executing this process for each of a large number of preset time points, a time-series change in the 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 by the display color or the brightness. At this time, the display color when the phase increases along the time series (for example, red) and the display color when the phase decreases (for example, blue) can be changed. Further, the magnitude of the amount of change in phase can be expressed by the density of the display color. By adopting such an expression method, it becomes possible to clearly indicate the direction and size of blood flow with a display color. A phase image is formed by executing the above processing for each pixel.

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

<Data processing unit 230>
The data processing unit 230 executes various data processing. For example, the data processing unit 230 performs various 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. Further, the data processing unit 230 may perform various image processing and analysis processing on the image obtained by the fundus camera unit 2 (the fundus image, the anterior eye portion image, etc.) and the image input from the outside. can.

The data processing unit 230 can form three-dimensional image data of the fundus Ef. The three-dimensional image data means image data in which the positions of pixels 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 by one three-dimensional coordinate system (that is, embedding them in one three-dimensional space). It is data.

Volume data is image data in which voxels arranged three-dimensionally are pixels, and is also called voxel data. Volume data is formed by applying interpolation processing, voxelization processing, etc. to the 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, and a cross-section setting unit 237 as exemplary elements for obtaining blood flow information. The blood flow information generation unit 232 includes a tilt estimation unit 233, a blood flow velocity calculation unit 234, a blood vessel diameter calculation unit 235, and a blood flow volume calculation unit 236.

<Blood vessel region identification part 231>
The blood vessel region specifying unit 231 identifies the blood vessel region corresponding to the blood vessel Db of interest for each of the main tomographic image, the supplementary tomographic image, and the phase image. This process can be executed by analyzing the pixel value of each image (for example, threshold value process).

The main tomographic image and the supplementary tomographic image have sufficient resolution for analysis processing, but the phase image may not have sufficient resolution to specify the boundary of the blood vessel region. However, since blood flow information is generated based on the phase image, it is necessary to specify the blood vessel region contained therein 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. The blood vessel region specifying unit 231 analyzes, for example, a main tomographic image to obtain a blood vessel region, identifies an image region in a phase image corresponding to this blood vessel region based on the corresponding relationship, and identifies the specified image region as a phase image. Adopted as a blood vessel area inside. Thereby, the blood vessel region of the phase image can be specified with high accuracy and high accuracy.

<Blood flow information generator 232>
The blood flow information generation unit 232 generates blood flow information regarding the blood vessel Db of interest. As described above, the blood flow information generation unit 232 includes a tilt estimation unit 233, a blood flow velocity calculation unit 234, a blood vessel diameter calculation unit 235, and a blood flow volume 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 the supplementary cross-section data (cross-section data, supplementary tomographic image) collected by the supplementary scan. This inclination estimation value may be, for example, a measured value of the inclination of the blood vessel of interest in the cross section of interest, or an approximate value thereof.

An example of actually measuring the value of the inclination 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 identifies the positional relationship between the attention cross section C0, the supplementary cross section C1 and the supplementary cross section C2, and the blood vessel region by the blood vessel region specifying portion 231. Based on the result, the inclination of the blood vessel Db of interest in the cross section of interest C0 can be calculated.

The method of calculating the inclination of the blood vessel Db of interest will be described with reference to FIG. 6A. Reference numerals G0, G1 and G2 indicate a main tomographic image in the cross section C0 of interest, a supplementary tomographic image in the supplementary cross section C1, and a supplementary tomographic image in the supplementary cross section C2, respectively. Further, the symbols V0, V1 and V2 indicate the blood vessel region in the main tomographic image G0, the blood vessel region in the supplementary tomographic image G1, and the blood vessel region in the supplementary tomographic image G2, respectively. The z-axis shown in FIG. 6A substantially coincides with the incident direction of the measurement light LS. Further, let d be the distance between the main tomographic image G0 (attention cross section C0) and the supplementary tomographic image G1 (supplementary cross section C1), and the main tomographic image G0 (attention cross section C0) and the supplementary tomographic image G2 (supplementary cross section C2). Let d be the distance between them. The distance between adjacent tomographic images, that is, the distance between adjacent cross sections is called the intersection distance.

The inclination estimation unit 233 can calculate the inclination A of the blood vessel Db of interest in the cross section C0 of interest based on the positional relationship between the three blood vessel regions V0, V1 and V2. This positional relationship is determined, for example, by connecting three vascular regions V0, V1 and V2. As a specific example, the inclination estimation unit 233 can specify the feature positions of the three blood vessel regions V0, V1 and V2, and connect these feature positions. The feature positions include a center position, a center of gravity position, a top portion (a position where the z coordinate value is the minimum), and a bottom portion (a position where the z coordinate value is the maximum). Of these feature positions, identifying the top is considered to be the simplest process. Further, as a method of connecting feature positions, there are a method of connecting with a line segment, a method of connecting with an approximate curve (spline curve, Bezier curve, etc.) and the like.

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

In the above example, the blood vessel region in the three cross sections is considered, but it is also possible to consider the two cross sections to obtain the inclination. As a specific example, the inclination of the first line segment or the second line segment can be set as the target inclination. Further, the slope A of the blood vessel Db of interest in the cross section of interest C0 can be calculated based on the two supplementary tomographic images G1 and G2.

In the above example, one inclination is obtained, but the inclination may be obtained for each of two or more positions (or regions) in the blood vessel region V0. In this case, the obtained two or more slope values can be used separately, or the values obtained by statistically processing these slope values (for example, mean value, maximum value, minimum value, and intermediate value). , Moden, etc.) can also 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 can analyze the supplementary tomographic image corresponding to the supplementary cross section Cp and calculate an approximate value of the inclination of the blood vessel Db of interest in the cross section C0 of interest. can.

The method of approximating the slope of the blood vessel Db of interest will be described with reference to FIG. 6B. The reference numeral Gp indicates a supplementary tomographic image in the supplementary cross section Cp. Reference numeral A indicates the inclination of the blood vessel Db of interest in the cross section of interest C0, as in the example shown in FIG. 6A.

In this example, the inclination estimation unit 233 can analyze the supplementary tomographic image Gp to identify an image region corresponding to a predetermined tissue of the fundus Ef. For example, the tilt estimation unit 233 can identify an image region (internal limiting membrane region) M corresponding to the internal limiting membrane (ILM), which is the surface tissue of the retina. For example, a known segmentation process is used to specify the image region.

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

The slope A shown in FIGS. 6A and 6B is a vector representing the direction of the blood vessel Db of interest, and the definition of the value thereof may be arbitrary. As an example, it is possible to define the value of the slope A as the angle formed by the slope (vector) A and the z-axis. Similarly, the slope A _app shown in FIG. 6B is a vector representing the orientation of the internal limiting membrane region M, and the definition of its value may be arbitrary. For example, it is possible to define the value of the slope A _app as the angle formed by the slope (vector) A _app and the z-axis. The direction of the z-axis is substantially the same as the incident direction of the measurement light LS.

As a third example of tilt estimation of the blood vessel of interest, the tilt estimation unit 233 analyzes the supplementary tomographic image Gp shown in FIG. 6B, identifies an image region corresponding to the blood vessel Db of interest, and positions a position corresponding to the cross section of interest C0. The inclination of the image area in the above can be obtained. At this time, the inclination estimation unit 233 can, for example, approximate the boundary or the central axis of the image region corresponding to the attention vessel Db by a curve, and obtain the inclination of the approximate curve at the position corresponding to the attention cross section C0. May be good. It is also possible to apply a similar curve approximation to the image region (eg, the internal limiting membrane region M) corresponding to the predetermined tissue of the fundus Ef described above.

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

<Blood flow velocity calculation unit 234>
The blood flow velocity calculation unit 234 calculates the blood flow velocity in the attention section C0 of the blood flowing in the blood vessel Db of interest based on the time-series change of the phase difference obtained as the phase image. The calculation target may be the blood flow velocity at a certain point in time, or may be a time-series change (blood flow velocity change information) of the 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 an electrocardiogram (for example, the time phase of an R wave). Further, the time range in the latter is the whole or any part of the time when the cross section C0 of interest is scanned.

When the blood flow velocity change information is obtained, the blood flow velocity calculation unit 234 can calculate the statistical value of the blood flow velocity during the measurement period. The statistical values include mean 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 for the value of blood flow velocity.

The blood flow velocity calculation unit 234 calculates the blood flow velocity by using the method of Doppler OCT. At this time, the inclination A (or its approximate value A _app ) of the blood vessel Db of interest in the cross section of interest 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 this embodiment, n and λ are known, Δf is obtained from the time series change of the phase difference, and θ is obtained from the slope A (or its approximate value A _app ). Typically, θ is equal to the slope A (or its approximation A _app ). By substituting these values into the above equation, the blood flow velocity v is calculated.

<Blood vessel diameter calculation unit 235>
The blood vessel diameter calculation unit 235 calculates the diameter of the blood vessel Db of interest in the cross section C0 of interest. As an example of this calculation method, there are a first calculation method using a fundus image (frontal image) and a second calculation method using a tomographic image.

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

The blood vessel diameter calculation unit 235 is based on various factors that determine 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, in the fundus image. Set the scale. This scale represents the length in real space. As a specific example, this scale associates the spacing between adjacent pixels with the scale in real space (for example, the spacing between pixels = 10 μm). It is also possible to calculate in advance the relationship between various values of the above factors and the scale in 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 the scale corresponding to the above factor.

Further, the blood vessel diameter calculation unit 235 calculates the diameter of the blood vessel Db of interest in the cross section C0 of interest, that is, the diameter of the blood vessel region V0, based on this scale and the pixels included in the blood vessel region V0. As a specific example, the blood vessel diameter calculation unit 235 obtains the maximum value and the average value of the diameters of the blood vessel region V0 in various directions. Further, in the blood vessel region 235, the contour of the blood vessel region V0 can be approximated by a circle or an ellipse, and the diameter of the circle or the ellipse can be obtained. Since the area of the blood vessel region V0 can be determined (substantially) once the blood vessel diameter is determined (that is, both can be associated with each other substantially one-to-one), instead of obtaining the blood vessel diameter, the area is used. It may be calculated.

The second calculation method will be described. In the second calculation method, a tomographic image in the cross section of interest C0 is typically used. This tomographic image may be a main tomographic image or may be acquired separately.

The scale of this tomographic image is determined based on the measurement conditions of OCT and the like. In this embodiment, the section of interest C0 is scanned as shown in FIG. 5A or FIG. 5B. The length of the section of interest C0 is determined based on various factors that determine the relationship between the scale on the image and the scale in real space, such as working distance and information on the eyeball optical system. The blood vessel diameter calculation unit 235 obtains, for example, the spacing between adjacent pixels based on this length, and calculates the diameter of the blood vessel Db of interest in the cross section of interest 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 blood flowing in the blood vessel Db of interest based on the calculation result of the blood flow velocity and the calculation result of the blood vessel diameter. An example of this process will be described below.

It is assumed that the blood flow in the blood vessel is Hagen-Poiseuille flow. Further, assuming that 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 volume calculation unit 236 substitutes the blood vessel diameter calculation result w by the blood vessel diameter calculation unit 235 and the maximum value Vm based on the blood flow velocity calculation result by the blood flow velocity calculation unit 234 into this formula. Calculate the target blood flow Q.

<Cross section setting unit 237>
The main control unit 211 causes the display unit 241 to display a front image of the fundus Ef. The front image may be any type of image, and may be, for example, any of an observation image, a photographed image, a fluorescence image, an OCT angiography image, an OCT projection image, and an OCT shadowgram.

By operating the operation unit 242, the user can specify one or more cross sections of interest with respect to the displayed front image of the fundus Ef. The section of interest is designated to intersect the vessel of interest. The cross-section setting unit 237 can set one or more supplementary cross-sections for each of the one or more notable cross-sections based on the designated one or more notable cross-sections and the front image of the fundus Ef. The supplementary cross section may be set manually.

In another example, the cross-section setting unit 237 may be configured to analyze the frontal image of the fundus Ef to identify one or more blood vessels of interest. The identification of the blood vessel of interest is performed based on, for example, the thickness of the blood vessel, the positional relationship of the fundus with respect to a predetermined site (eg, optic disc, macula), the type of blood vessel (eg, artery, vein), and the like. Further, the cross-section setting unit 237 can set one or more notable cross-sections and one or more supplementary cross-sections for each of the one or more identified blood vessels of interest.

In this way, the cross-section of interest and the supplementary cross-section as exemplified in FIG. 5A or FIG. 5B are set for the fundus Ef by the user, by the cross-section setting unit 237, or by the collaboration between the user and the cross-section setting unit 237. To.

<Movement condition setting unit 260>
As described above, in order to obtain the optimum Doppler signal in the fundus blood flow measurement, it is necessary to inject the measurement optical axis at an angle suitable for the traveling direction (blood flow direction) of the blood vessel of interest, and this embodiment Then, this is realized by offsetting the optical axis of the optical system (the optical axis of the objective lens 22) with respect to the optical axis of the eye E to be inspected. The movement condition setting unit 260 sets the movement condition of the optical system with respect to the optical axis of the eye E to be inspected. The movement condition setting unit 260 includes a direction setting unit 261 and a distance setting unit 262.

<Direction setting unit 261>
The direction setting unit 261 analyzes the OCT image of the fundus Ef and sets the moving direction of the optical system. As will be described below, the direction setting unit 261 can execute the same processing as other elements (blood vessel region specifying unit 231, inclination estimation unit 233, etc.). In that case, the direction setting unit 261 may have the function separately from the corresponding element, may use the result of the processing executed by the corresponding element, or may use the processing in the corresponding element. May be requested, or the corresponding element may be included. Further, among the processes that can be executed by the direction setting unit 261, the same processes as those of other elements will not be described in detail again.

The moving direction set by the direction setting unit 261 is a direction orthogonal to the optical axis of the optical system (the optical axis of the measuring arm, the optical axis of the objective lens 22). In other words, the moving direction set by the direction setting unit 261 is a direction defined in the xy plane, and has only one or both of the x-direction component and the y-direction component. That is, the moving direction set by the direction setting unit 261 does not have a z-direction component.

Typically, the moving direction set by the direction setting unit 261 is a moving direction (initial moving direction) applied to the first movement of the optical system. The direction setting unit 261 may be able to set the movement direction applied to the second (or third and subsequent) movements of the optical system.

The OCT image analyzed by the direction setting unit 261 may be any OCT image. For example, the direction setting unit 261 can set the initial movement direction by analyzing at least two tomographic images of the main tomographic image G0, the supplementary tomographic image G1 and the supplementary tomographic image G2 shown in FIG. 6A. More generally, the direction setting unit 261 can set the initial movement direction by analyzing two or more tomographic images constructed by applying an OCT scan to each of two or more cross sections intersecting the cross section of interest.

As another example, the direction setting unit 261 can set the initial movement direction by analyzing the supplementary tomographic image Gp shown in FIG. 6B. More generally, the direction setting unit 261 can set the initial movement direction by analyzing the tomographic image constructed by applying the OCT scan to the cross section along the cross section of interest. The OCT image analyzed in the setting of the initial moving direction is not limited to these examples.

As a first example, in order to set the initial movement direction of the optical system, at least two tomographic images of the main tomographic image G0, the supplementary tomographic image G1 and the supplementary tomographic image G2 shown in FIG. 6A are analyzed. explain. In this example, the supplementary tomographic images G1 and G2 are analyzed, but the same analysis can be performed when other combinations are adopted.

In this example, the direction setting unit 261 analyzes the supplementary tomographic image G1 to specify the blood vessel region V1 and analyzes the supplementary tomographic image G2 to specify the blood vessel region V2. Next, the direction setting unit 261 identifies a feature position from each of the two specified blood vessel regions V1 and V2, and estimates the inclination of the blood vessel Db of interest from the difference between the z-coordinate values of the two specified feature positions. Ask for. The direction setting unit 261 can set the initial moving direction of the optical system based on the estimated value of the inclination of the blood vessel Db of interest.

In the modification of the first example, the direction setting unit 261 can also set the initial movement direction of the optical system based on the difference between the z-coordinate values of the two feature positions specified from the two blood vessel regions V1 and V2. Is.

In another variant of the first example, the orientation setting unit 261 analyzes the complementary tomographic image G1 to identify the internal limiting membrane region and analyzes the complementary tomographic image G2 to identify the internal limiting membrane region. Next, the direction setting unit 261 identifies a characteristic position (for example, a position directly above the blood vessel Db of interest) from each of the two specified internal limiting membrane regions. The direction setting unit 261 sets the initial movement direction of the optical system based on the difference between the z-coordinate values of the two specified feature positions (or the estimated value of the inclination of the blood vessel Db of interest calculated from this difference). Can be done.

As a second example, a case where the supplementary tomographic image Gp shown in FIG. 6B is analyzed in order to set the moving direction of the optical system will be described.

In this example, the direction setting unit 261 analyzes the supplementary tomographic image Gp to specify the internal limiting membrane region M. Next, the direction setting unit 261 obtains an estimated value of the inclination of the blood vessel Db of interest based on the specified internal limiting membrane region M. The direction setting unit 261 can set the initial moving direction of the optical system based on the estimated value of the inclination of the blood vessel Db of interest.

In the modification of the second example, the direction setting unit 261 analyzes the supplementary tomographic image Gp to identify the blood vessel region corresponding to the blood vessel Db of interest. Next, the direction setting unit 261 obtains an estimated value of the inclination of the blood vessel Db of interest based on the specified blood vessel region. The direction setting unit 261 can set the initial moving direction of the optical system based on the estimated value of the inclination of the blood vessel Db of interest.

The process of setting the initial movement direction based on the inclination of the blood vessel Db of interest will be described. The same treatment can be applied to a parameter having the same value as the slope of the blood vessel Db of interest. Examples of such parameters are the slope of the internal limiting membrane region M, the difference in the z-coordinate values of the vessel region in two or more cross sections of the vessel Db of interest, and the z-coordinate of the internal limiting membrane region in two or more cross sections of the vessel Db of interest. There is a difference in values. Hereinafter, reference is made to FIGS. 7A and 7B.

In the supplementary tomographic image Gp shown in FIG. 7A, the blood vessel Db of interest and the internal limiting membrane (internal limiting membrane region M) are depicted. The reference numeral Ma indicates the intersection position of the internal limiting membrane region M and the cross section of interest C0 (see FIG. 6B, etc.), and is set at the calculation position of the inclination of the internal limiting membrane region M (the calculation position of the inclination estimation value of the blood vessel Db of interest). Equivalent to. The straight line indicated by the reference numeral Mh is a line (inclination line) indicating the inclination direction of the internal limiting membrane region M at the inclination calculation position Ma. The straight line indicated by the reference numeral Mn is a line (inclination normal line) indicating the normal direction of the inclination line Mh at the inclination calculation position Ma.

The straight line indicated by the reference numeral P0 is the path (scan position) of the measurement light LS before the movement (initial position) of the optical system. The initial position of the optical system is, for example, a state in which the alignment is aligned with the center of the pupil of the eye E to be inspected, that is, a state in which the optical axis of the optical system (the optical axis of the objective lens 22) is the center of the pupil of the eye E to be inspected. Equivalent to. In this example, the measurement path P0 passes through the inclination calculation position Ma and is parallel to the z direction. The straight line indicated by the reference numeral P0n is a line (measurement normal line) indicating the normal direction of the measurement path P0 at the slope calculation position Ma.

The angle between the measurement path P0 and the slope normal Mn is indicated by α0. The angle α0 is the angle of incidence of the measured light LS on the internal limiting membrane of the eye E to be inspected when the optical system is arranged at the initial position. That is, the angle α0 is used as the incident angle of the measured light LS with respect to the blood vessel Db of interest when the optical system is arranged at the initial position. Further, the angle of the angle formed by the measurement normal line P0n and the inclined line Mh is also α0.

The inclination of the blood vessel Db of interest may be defined by the angle "α" formed by the measurement path and the inclined normal line, or may be defined by the angle "α" formed by the measurement normal line and the inclined line. Alternatively, the inclination of the blood vessel Db of interest may be defined by the angle "90 degrees-α" between the measurement path and the inclination line, or the angle "90 degrees-α" between the measurement normal and the inclination normal. May be defined by. The range of angles suitable for blood flow measurement (target angle range) is set to, for example, "α = 5 degrees to 10 degrees", that is, "90 degrees-α = 80 degrees to 85 degrees". Here, the angle α is the incident angle of the measured light LS with respect to the internal limiting membrane (attention blood vessel Db). Further, the margin angle 90 degrees −α of the angle α is represented by “β”.

The direction setting unit 261 sets the moving direction of the optical system so that the incident angle α is included in the target angle range (for example, α = 5 degrees to 10 degrees). As a condition equivalent to this, the direction setting unit 261 sets the moving direction of the optical system so that the margin angle β is included in the target angle range (for example, β = 80 degrees to 85 degrees).

As is clear from FIG. 7 and the like in JP-A-2017-4-2602 (Patent Document 1), when the incident angle α = α0 shown in FIG. 7A is smaller than the target angle range, the direction setting unit 261 has an incident angle α. The moving direction of the optical system is set so as to be included in the target angle range (that is, so that the incident angle α becomes large). The moving direction at this time is the left direction in FIG. 7A. Thereby, for example, as shown in FIG. 7B, the cross section C0 of interest can be scanned by the measurement light LS passing through the measurement path P1 at which the incident angle α = α1 (α1> α0). Here, the straight line indicated by the reference numeral P1n is a line (measurement normal line) indicating the normal direction of the measurement path P1 at the slope calculation position Ma.

On the contrary, when the incident angle α = α0 is larger than the target angle range, the direction setting unit 261 sets the optical system so that the incident angle α is included in the target angle range (that is, the incident angle α becomes smaller). Set the movement direction of. The moving direction at this time is the right direction in FIG. 7A. Although not shown, the movement of the optical system makes it possible to scan the cross section of interest C0 by the measurement light LS passing through the measurement path P2 at which the incident angle α = α2 (α2 <α0).

<Distance setting unit 262>
As described above, the optical system is moved in the initial movement direction set by the direction setting unit 261. The movement distance (initial movement amount) at this time may be set in advance. In the present embodiment, the initial movement amount is set by the distance setting unit 262. The distance setting unit 262 may be able to set the amount of movement applied to the second (or third or later) movement of the optical system.

A first example of processing that can be executed by the distance setting unit 262 will be described. The distance setting unit 262 of this example can set the initial movement amount according to the actual pupil diameter of the eye E to be inspected.

Information indicating the pupil diameter of the eye E to be inspected (pupil diameter information) is acquired by the pupil diameter information acquisition unit. For example, the pupil diameter information acquisition unit includes an element for measuring the pupil diameter of the eye E to be inspected. As a specific example, the pupil diameter information acquisition unit uses a processor that analyzes the anterior eye portion image of the eye E to be inspected acquired by the illumination optical system 10 and the photographing optical system 30, identifies the pupil region, and calculates the diameter thereof. May include. The identification of the pupil region may include processing such as threshold processing and edge detection. Further, the calculation of the diameter of the pupil region may include processing such as ellipse approximation and circle approximation.

The pupil diameter information acquisition unit may be configured to acquire the measured value of the pupil diameter of the eye E to be examined acquired in the past from an electronic medical record or the like of the subject. The pupil diameter information acquisition unit of this example includes a communication device (data input / output unit 290) for accessing a device in which an electronic medical record or the like is stored.

The distance setting unit 262 can set the initial movement amount based on the value of the pupil diameter acquired by the pupil diameter information acquisition unit. For example, the distance setting unit 262 can set a value that is half of the value of the pupil diameter acquired by the pupil diameter information acquisition unit as the initial movement amount. This initial movement amount corresponds to the value of the radius of the pupil of the eye E to be inspected or an approximate value thereof.

According to this example, since the initial movement amount can be set based on the actual measured value of the pupil diameter of the eye E to be inspected, the optimum offset in the offset operation of the measurement arm for obtaining the optimum Doppler signal in the fundus blood flow measurement. It is possible to shorten the time required to achieve the position. As a result, the burden on the subject can be reduced.

A second example of processing that can be executed by the distance setting unit 262 will be described. When the eye to be inspected E is a small pupil eye, a cataract eye, or when the blood vessel of interest is located in the peripheral part of the fundus Ef, a drug (mydriatic agent) for dilating the pupil is applied to the eye to be inspected. May apply to E. The distance setting unit 262 of this example can set the initial movement amount depending on whether or not the mydriatic agent is applied to the eye E to be inspected.

The distance setting unit 262 of this example preliminarily sets the initial movement amount (first initial movement amount) when the mydriatic agent is not applied and the movement distance (second initial movement amount) when the mydriatic agent is applied. I remember. The first initial movement amount is set to, for example, half the standard pupil diameter (radius of a standard sized pupil). The second initial movement amount is set to half the diameter of the dilated pupil when the mydriatic agent is applied to an eye with a standard pupil diameter. The initial movement amount according to the attributes of the subject (age, gender, etc.) and the initial movement amount according to the attributes of the eye to be examined may be stored in advance.

Whether or not the mydriatic agent has been applied to the eye E to be inspected is input by the user using, for example, the operation unit 242. Alternatively, it may be determined whether or not the mydriatic agent has been applied to the eye E to be inspected by referring to the electronic medical record or the like of the subject via the data input / output unit 290.

The distance setting unit 262 can select one of the plurality of stored initial movement amounts based on the information indicating whether or not the mydriatic agent has been applied to the eye E to be inspected.

According to this example, the initial movement amount can be set according to the pupil size of the eye E to be inspected (particularly, the pupil diameter depending on the application of the mydriatic agent), so that the optimum Doppler signal for fundus blood flow measurement can be obtained. In the offset operation of the measuring arm for obtaining, it is possible to shorten the time until the optimum offset position is achieved. As a result, the burden on the subject can be reduced.

<Vignetting judgment unit 270>
The vignetting determination unit 270 determines the presence or absence of vignetting based on the detection result of the return light of the light incident on the eye E to be inspected via the optical system mounted on the blood flow measuring device 1.

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

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

The "vignetting" in the present embodiment includes vignetting (decrease in brightness) generated by blocking a part or all of the incident light for measuring the blood flow in the fundus or the return light thereof by the pupil. In addition, "presence or absence of vignetting" in the present embodiment includes any of the following: whether or not vignetting has occurred; and whether or not the degree of vignetting exceeds a predetermined degree.

An example of the process executed by the vignetting determination unit 270 will be described. Hereinafter, the first example and the second example relating to the vignetting determination method will be described, but the method is not limited thereto.

In the first example, the incident light for vignetting determination is the measurement light LS, and a predetermined OCT scan is applied. The mode of the OCT scan in this example may be, for example, an OCT scan for the attention section C0 (or the 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, for example, a repeated scan for the same cross section.

When repeated scanning for the supplementary cross section Cp (or supplementary cross section C1 and / or C2) is applied, it is possible to estimate the inclination of the blood vessel Db of interest in parallel with the vignetting determination, or the blood vessel of interest can be estimated from the vignetting determination. A smooth transition to the slope estimation of Db is possible. Further, the movement condition setting (movement direction setting, movement distance setting) may be performed in parallel with the vignetting determination.

When the supplementary cross-section Cp is applied and there is no vignetting, a tomographic image Gp1 (cross-section data) representing the morphology of the supplementary cross-section Cp is obtained as shown in FIG. 8A. On the other hand, when vignetting is present, as shown in FIG. 8B, a tomographic image Gp2 (cross-section data) in which the morphology of the supplementary cross-section Cp is not depicted can be obtained. Since the optical scanner 44 is arranged at a position substantially conjugate with the pupil of the eye E to be inspected in a state where the alignment is suitable, the deflection center of the measurement light LS substantially coincides with the pupil. Therefore, when the measurement light LS is vignetting in the pupil, a tomographic image Gp2 (cross-section data) in which the morphology of the supplementary cross-section Cp is not depicted can be obtained.

The vignetting determination unit 270 analyzes the tomographic image obtained by the OCT scan for the supplementary cross-section Cp, and determines whether or not the morphology of the supplementary cross-section Cp is visualized. For example, the vignetting determination unit 270 may be configured to determine whether or not the internal limiting membrane region (M) is visualized in the tomographic image. The determination result that "the internal limiting membrane region is visualized in the tomographic image" corresponds to the determination result that "there is no vignetting". On the contrary, the determination result that "the internal limiting membrane region is not visualized in the tomographic image" corresponds to the determination result that "vignetting is present".

A second example of the process executed by the vignetting determination unit 270 will be described. In this example, the incident light for vignetting determination is the illumination light for fundus photography, and may be observation illumination light or photography illumination light. The vignetting determination unit 270 analyzes the fundus image and determines whether or not a decrease in the amount of light, which is an effect of vignetting, has occurred. For example, the vignetting determination unit 270 determines whether there is a difference between the brightness of the central portion and the brightness of the peripheral portion of the fundus image (that is, whether the peripheral light amount is reduced). This determination is performed with reference to the values of the pixels constituting the fundus image (typically, the luminance distribution), and includes image processing such as threshold processing and labeling.

According to the second example, the degree of vignetting can be easily determined. The degree of vignetting is evaluated, for example, based on the characteristics of the image region in which the peripheral illumination is reduced in the fundus image. The vignetting determination unit 270 can calculate an evaluation value (for example, the size (area) of the peripheral illumination reduction region) in this way, and determine the presence or absence of vignetting based on the magnitude of the evaluation value. The "presence or absence of vignetting" in this example corresponds to, for example, whether or not the degree of vignetting exceeds a predetermined degree. Typically, the vignetting determination unit 270 compares the calculated evaluation value with the threshold value, determines that "vignetting exists" when the evaluation value exceeds the threshold value, and determines that "vignetting exists" when the evaluation value is equal to or less than the threshold value. Judged as "no vignetting".

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

<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 any operation device. The user interface 240 may include a device having both a display function and an operation function, such as a touch panel.

<Data input / output unit 290>
The data input / output unit 290 outputs data from the blood flow measuring device 1 and inputs data to the blood flow measuring device 1.

The data input / output unit 290 has, for example, a function for communicating with an external device (not shown). The communication unit 290 includes a communication interface according to the connection form with the external device. The external device is, for example, any ophthalmic device. Further, the external device may be any information processing device such as a hospital information system (HIS) server, a DICOM (Digital Imaging and Communication in Medicine) server, a doctor terminal, a mobile terminal, a personal terminal, and a cloud server.

The data input / output unit 290 may include a device (data reader) for reading information from the recording medium, a device for writing information to the recording medium (data writer), and the like.

<motion>
An example of the operation of the blood flow measuring device 1 will be described. FIG. 9 shows an example of the operation of the blood flow measuring device 1. It is assumed that preparatory processing such as input of the patient ID has already been performed.

(S1: Start of auto alignment)
First, perform auto-alignment. Auto-alignment is performed, for example, using the alignment index as described above. Alternatively, as disclosed in Japanese Patent Application Laid-Open No. 2013-248376, it is also possible to perform auto-alignment using two or more front eye cameras. The auto-alignment method is not limited to these.

(S2: Auto alignment completed)
When the relative positions between the eye E to be inspected and the optical system match in all of the x-direction, y-direction, and z-direction, the auto-alignment is completed.

(S3: Acquire pupil diameter information)
The blood flow measuring device 1 acquires the pupil diameter information of the eye E to be inspected by the above-mentioned pupil diameter information acquisition unit.

(S4: Tracking started)
After the completion of the auto-alignment, the blood flow measuring device 1 starts tracking for moving the optical system according to the movement of the eye E (fundus Ef) to be inspected. Tracking includes, for example, an operation of acquiring an observation image of the fundus Ef using infrared light, an operation of analyzing the observation image to detect the movement of the fundus Ef, and an optical system according to the detected movement of the fundus Ef. It is realized by the combination with the movement of moving. Further, the tracking may include an operation of controlling the optical scanner 44 according to the movement of the fundus Ef.

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

(S5: Set the moving direction)
The blood flow measuring device 1 applies an OCT scan to the supplementary cross section Cp. The direction setting unit 261 analyzes the supplementary tomographic image Gp representing the supplementary cross section Cp and sets the movement direction (initial movement direction) of the optical system (at least the measurement arm).

(S6: Set the moving distance)
The distance setting unit 262 sets the movement distance (initial movement amount) of the optical system based on the pupil diameter information acquired in step S3. It is also possible to set the moving distance depending on whether or not the mydriatic agent is applied.

(S7: Move the optical system)
At this stage, typically, the center of the pupil (or the apex of the cornea) and the optical axis of the optical system are substantially aligned in the xy direction, and the eye E to be inspected and the optical system (objective lens 22) are located in the z direction. The distance is almost the same as the working distance.

The main control unit 211 controls the movement mechanism 150 so as to move the optical system in the initial movement direction set in step S5 by the initial movement amount set in step S6. In other words, the main control unit 211 applies the first movement control for moving the optical system from the optical axis by the initial movement amount in the initial movement direction orthogonal to the optical axis of the optical system to the movement mechanism 150.

By the first movement control, for example, as shown in FIG. 10A, the optical axis of the optical system is moved from the position H0 substantially coincided with the center of the pupil (or the apex of the cornea) in the xy direction to the position H1 separated by a predetermined distance in the upper left direction. Is moved.

In the present embodiment, the moving direction (initial moving direction) of the optical system in the first movement control is set based on the OCT image of the fundus Ef. On the other hand, the movement distance (initial movement amount) of the optical system in the first movement control may be arbitrary, and may be, for example, a distance set based on the pupil diameter information and / or the application of the mydriatic agent. However, the distance may be set by default.

(S8: Determine the presence or absence of vignetting)
After the first movement control (first movement of the optical system) in step S7, the main control unit 211 starts scanning the supplementary cross section Cp shown in FIG. 5B as an OCT scan for vignetting determination. The vignetting determination unit 270 determines the presence or absence of vignetting based on the cross-sectional data acquired by this OCT scan.

For example, in this step, the image forming unit 220 (tomographic image forming unit 221) forms a tomographic image from the data acquired by the OCT scan for the supplementary cross section Cp, and the vignetting determination unit 270 forms the supplementary cross section Cp on this tomographic image. The presence or absence of vignetting is determined by determining whether or not the form of is depicted.

(S9: Is there vignetting?)
If it is determined by the vignetting determination in step S8 that there is vignetting (S9: Yes), the operation proceeds to step S10. On the other hand, when it is determined that there is no vignetting (S9: No), the operation proceeds to step S11.

(S10: Fine movement of the optical system)
When it is determined in step S9 that there is vignetting (S9: Yes), the main control unit 211 applies the second movement control for finely adjusting the position of the optical system to the movement mechanism 150.

Typically, the movement distance in the second movement control is shorter than the movement distance (initial movement amount) in the first movement control in step S7. Further, the movement direction in the second movement control is the direction opposite to the initial movement direction in the first movement control in step S7. Here, the moving distance in the second movement control may be, for example, a distance set by default or a distance set by the distance setting unit 262.

When it is determined in step S9 that vignetting has occurred, for example, as shown in FIG. 10B, when the optical axis position H1 after the first movement control is outside the pupil Ep, the measurement light LS is glowing. As shown in FIG. 8B, a tomographic image is obtained in which the morphology of the supplementary cross section Cp is not depicted. As a result, the vignetting determination unit 270 obtains a determination result that vignetting has occurred. As shown by reference numeral J in FIG. 10B, the main control unit 211 moves so as to move the optical system by a predetermined distance (a predetermined amount of fine movement) in the direction opposite to the initial movement direction (direction from position H0 to position H1). It controls the mechanism 150. In this way, when it is determined in step S9 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 S8. Steps S8 to S10 are repeated until "Yes" is determined in step S9. It is possible to output an error determination when steps S8 to S10 are repeated a predetermined number of times, or when steps S8 to S10 are repeated for a predetermined time.

(S11: Estimate the inclination of the blood vessel of interest)
When it is determined in step S9 that there is no vignetting (S9: No), the blood flow measuring device 1 estimates the inclination of the blood vessel Db of interest in the manner described above. For the inclination estimation of this example, for example, the cross-section data of the supplementary cross-section Cp is used as in the case of vignetting determination.

If it is determined in step S9 that vignetting has not occurred, the optical axis position H1 after the first movement control is inside the pupil Ep, for example, as shown in FIG. 10C.

(S12: Perform blood flow measurement)
When the estimated value of the inclination of the blood vessel Db of interest is obtained in step S11, the blood flow measuring device 1 executes the blood flow measurement of the cross section of interest C0 in the manner described above, and generates blood flow information (end).

A modified example of the operation described above will be described. The main control unit 211 can display the information indicating the initial movement direction set in step S5 on the display unit 241. Further, the main control unit 211 can display the information indicating the initial movement amount set in step S6 on the display unit 241. Further, the main control unit 211 causes the display unit 241 to display information indicating the inclination estimation value obtained by the inclination estimation unit 233, and displays information indicating the difference between the inclination estimation value and the target angle range. It can be displayed on 241.

As described above, the target angle range is set to, for example, the range of 80 degrees to 85 degrees. The target angle range may be a single value or a range defined by the upper and / or lower limits. The target angle range is, for example, a default value, a default range, a value or range set by a user or another person (eg, a maintenance serviceman), a blood flow measuring device 1 or another device (eg, a server in a medical institution, and a server in a medical institution). , A device that monitors the operation of the blood flow measuring device 1) may be either a value or a range set. As an example of setting by the blood flow measuring device 1 or the like, setting the target angle range applied in the past to the eye E to be examined is set again, or setting the target angle range according to the attribute of the subject. Alternatively, it is possible to set the target angle range according to the attributes of the eye E to be inspected.

The user can input an instruction regarding the moving direction and an instruction regarding the moving distance by referring to the displayed information. These instructions are given, for example, when a suitable measurement angle cannot be obtained even if the second movement control is repeatedly performed.

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

The blood flow measuring device (1) of the exemplary embodiment includes a scan optical system, a moving mechanism, an image forming unit, a direction setting unit, a control unit, and a blood flow information acquisition unit.

The scan optical system applies an OCT scan to the fundus of the eye to be inspected. In the present embodiment, the optical system including the OCT unit 100 and the measurement arm in the fundus camera unit 2 is an example of this scan optical system.

The moving mechanism moves the scanning optical system. The moving mechanism 150 of the present embodiment is an example of this moving mechanism.

The image forming unit forms an image from the first data collected by the scanning optical system. The image formed from the first data may be a reflection intensity profile or an image (image data) generated from the image. The image forming unit 220 of the present embodiment is an example of this image forming unit.

The direction setting unit analyzes the image formed by the image forming unit and sets a first direction (initial moving direction) orthogonal to the optical axis of the scan optical system. The direction setting unit 261 of the present embodiment is an example of this direction setting unit.

The control unit applies the first movement control for moving the scan optical system in the first direction to the movement mechanism. The control unit 210 (main control unit 211) of the present embodiment is an example of this control unit.

The blood flow information acquisition unit acquires blood flow information from the second data collected by the scan optical system after the first movement control. The image forming unit 220 and the data processing unit 230 (blood vessel region specifying unit 231 and blood flow information generating unit 232) of the present embodiment are examples of this blood flow information acquisition unit.

In an exemplary embodiment, the scan optics may be configured to collect first data by applying an OCT scan to a cross section along a blood vessel of interest in the fundus. Further, the direction setting unit may be configured to set the first direction by analyzing the image of the cross section formed from the first data. After the first movement control, the scan optics can apply an OCT scan to the vessel of interest to collect the second data.

In an exemplary embodiment, the orientation setting unit is configured to obtain an estimated value of the inclination of the blood vessel of interest by analyzing an image of a cross section along the blood vessel of interest, and to set a first direction based on the estimated inclination. You may be.

In an exemplary embodiment, the orientation setting unit analyzes an image of a cross section along a blood vessel of interest to identify an image region (internal limiting membrane region) corresponding to the fundus surface, and obtains a tilt estimation value based on this image region. It may be configured as follows.

In an exemplary embodiment, the orientation setting unit is configured to analyze an image of a cross section along a blood vessel of interest to identify an image region corresponding to the blood vessel of interest and to obtain an estimated tilt value based on this image region. good.

In an exemplary embodiment, the orientation setting unit may be configured to set the first direction so that the angle of incidence of the OCT scan light on the blood vessel of interest is within a predetermined range.

In an exemplary embodiment, the control unit may be configured to perform first movement control so as to move the scan optical system in the first direction by a preset distance (initial movement amount).

The blood flow measuring device according to the exemplary embodiment further includes a pupil diameter information acquisition unit that acquires pupil diameter information of the eye to be inspected, and a first setting unit that sets an initial movement amount based on the acquired pupil diameter information. May include. In the present embodiment, the illumination optical system 10, the photographing optical system 30, and the processor are one example of the pupil diameter information acquisition unit. Further, in the present embodiment, the data input / output unit 290 is another example of the pupil diameter information acquisition unit. Further, the distance setting unit 262 of the present embodiment is an example of this first setting unit.

The blood flow measuring device according to the exemplary embodiment may further include a second setting unit that sets the initial movement amount depending on whether or not the mydriatic agent is applied to the eye to be inspected. The distance setting unit 262 of the present embodiment is an example of this second setting unit.

The blood flow measuring device according to the exemplary embodiment has a determination unit for determining the presence or absence of vignetting based on the detection result of the return light of the light incident on the eye to be inspected via the scan optical system after the first movement control. Further may be included. Further, the control unit may be configured to apply a second movement control for further moving the scan optical system to the movement mechanism according to the determination result obtained by the determination unit. The vignetting determination unit 270 of the present embodiment is an example of this determination unit.

In an exemplary embodiment, the scan optical system may be configured to apply an OCT scan to collect second data to the fundus when the determination unit determines that there is no vignetting. That is, the scan optical system is configured to apply an OCT scan for collecting second data to the fundus when it is determined by the determination unit that there is no vignetting without further movement control. good.

In an exemplary embodiment, when the determination unit determines that vignetting is present, the control unit is in the first direction (initial movement direction) by a distance shorter than the movement distance (initial movement amount) in the first movement control. The second movement control for moving the scan optical system in the opposite second direction may be applied to the movement mechanism.

According to such an embodiment, in the offset operation of the optical system (measurement arm) for obtaining the optimum Doppler signal in the fundus blood flow measurement, the measurement arm is offset in the direction set based on the OCT image and then blood. Flow measurement can be performed. Therefore, the offset direction of the measurement arm with respect to the optical axis of the eye to be inspected can be suitably set, and the offset position of the incident light for measuring the blood flow in the fundus can be optimized.

According to this embodiment, it is possible to automatically optimize the offset position of the incident light for measuring the blood flow in the fundus.

According to the present embodiment, it is possible to present information for assisting the user when a part of the operation of optimizing the offset position of the incident light for measuring the blood flow in the fundus is manually performed.

The embodiments described above are merely exemplary embodiments of the invention. Therefore, it is possible to make arbitrary modifications (omission, substitution, addition, etc.) within the scope of the gist of the present invention.

1 Blood flow measurement device 100 OCT unit 150 Movement mechanism 210 Control unit 211 Main control unit 220 Image formation unit 230 Data processing unit 232 Blood flow information generation unit 233 Tilt estimation unit 260 Movement condition setting unit 261 Direction setting unit 262 Distance setting unit 270 Erase judgment unit 290 Data input / output unit

Claims (12)

A scan optical system that applies an optical coherence tomography (OCT) scan to the fundus of the eye to be inspected,
A moving mechanism for moving the scan optical system and
An image forming unit that forms an image from the first data collected by the scanning optical system, and an image forming unit.
A direction setting unit that analyzes the image and sets a first direction orthogonal to the optical axis of the scan optical system.
A control unit that applies a first movement control for moving the scan optical system in the first direction to the movement mechanism, and a control unit.
A blood flow measuring device including a blood flow information acquisition unit that acquires blood flow information from the second data collected by the scan optical system after the first movement control. The scan optical system applies an OCT scan to a cross section along a blood vessel of interest in the fundus to collect the first data.
The direction setting unit analyzes the image of the cross section formed from the first data and sets the first direction.
The blood flow measuring device according to claim 1, wherein the scan optical system applies an OCT scan to the blood vessel of interest to collect the second data after the first movement control. The direction setting unit is
The image of the cross section was analyzed to obtain an estimated value of the inclination of the blood vessel of interest.
The blood flow measuring device according to claim 2, wherein the first direction is set based on the estimated value of the inclination. The direction setting unit is
The image of the cross section is analyzed to identify the image region corresponding to the surface of the fundus, and the image is identified.
The blood flow measuring device according to claim 3, wherein the estimated value of the inclination is obtained based on the image region. The direction setting unit is
The image of the cross section is analyzed to identify the image region corresponding to the blood vessel of interest.
The blood flow measuring device according to claim 3, wherein the estimated value of the inclination is obtained based on the image region. The blood flow measuring device according to any one of claims 2 to 5, wherein the direction setting unit sets the first direction so that the incident angle of the OCT scan light with respect to the blood vessel of interest is included in a predetermined range. .. The blood flow according to any one of claims 1 to 6, wherein the control unit executes the first movement control so as to move the scan optical system in the first direction by a preset distance. Measuring device. The pupil diameter information acquisition unit that acquires the pupil diameter information of the eye to be inspected, and the pupil diameter information acquisition unit.
The blood flow measuring device according to claim 7, further comprising a first setting unit for setting the distance based on the pupil diameter information. The blood flow measuring device according to claim 7, further comprising a second setting unit for setting the distance depending on whether or not the mydriatic agent is applied to the eye to be inspected. After the first movement control, a determination unit for determining the presence or absence of vignetting based on the detection result of the return light of the light incident on the eye to be inspected via the scan optical system is further included.
The control unit is characterized in that, according to the determination result obtained by the determination unit, the second movement control for further moving the scan optical system is applied to the movement mechanism, claims 1 to 9. One of the blood flow measuring devices. The blood flow measurement according to claim 10, wherein when the determination unit determines that there is no vignetting, the scan optical system applies an OCT scan for collecting the second data to the fundus. Device. When the determination unit determines that vignetting is present, the control unit sets the scan optical system in the second direction opposite to the first direction by a distance shorter than the movement distance in the first movement control. The blood flow measuring device according to claim 10 or 11, wherein a second movement control for moving is applied to the movement mechanism.

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