Ophthalmic device, control method therefor, program, and recording medium

Abstract

An ophthalmic device according to some embodiments is provided with a fundus image acquisition unit, a registration unit, a frontal blood vessel region detection unit, a three-dimensional blood vessel region identification unit, and an orientation information generation unit. The fundus image acquisition unit acquires a frontal fundus image and a three-dimensional fundus image of an eye to be examined. The registration unit executes registration between the frontal fundus image and the three-dimensional fundus image. The frontal blood vessel region detection unit analyzes the frontal fundus image to detect a frontal blood vessel region. The three-dimensional blood vessel region identification unit identifies a three-dimensional blood vessel region in the three-dimensional fundus image corresponding to the frontal blood vessel region in the frontal fundus image on the basis of the result of the registration. The orientation information generation unit generates orientation information of the three-dimensional blood vessel region on the basis of data of a common region between a predetermined partial region in the three-dimensional fundus image and the three-dimensional blood vessel region.

Description

Ophthalmic apparatus, its control method, program, and recording medium

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 557,720, entitled "OPHTHALMIC OPTICAL COHERENCE TOMOGRAPHY," filed February 26, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to an ophthalmic apparatus, a control method thereof, a program, and a recording medium.

[0003] Various imaging modalities are used in ophthalmology practice, including fundus cameras, scanning laser ophthalmoscopy (SLO), slit lamp microscopes, and optical coherence tomography (OCT). OCT can be used for both structural and functional imaging.

[0004] Structural imaging using OCT is a technique for representing the spatial distribution of OCT signal intensity, which varies depending on the structure of a test object, as an image. Images generated by this technique are called OCT intensity images or simply intensity images.

[0005] OCT blood flow measurement is one of the functional imaging techniques using OCT. OCT blood flow measurement is a Doppler measurement that uses OCT to determine blood flow dynamics, and is also called Doppler OCT. OCT blood flow measurement is a technique that repeatedly scans the cross section of a blood vessel with OCT measurement light to collect a data set, and then determines the Doppler signal due to blood flow from the difference in this data set. It also determines the angle (Doppler angle) between the blood vessel and the OCT measurement light, thereby determining the magnitude of retinal blood flow velocity. Furthermore, the blood flow volume can be calculated by multiplying the obtained blood flow velocity by the cross-sectional area of ​​the blood vessel. In the field of ophthalmology, OCT blood flow measurement is typically applied to blood vessels in the fundus, particularly retinal blood vessels. However, OCT blood flow measurement of choroidal blood vessels has also been reported.

[0006] U.S. Pat. No. 1,1980,419 U.S. Pat. No. 8,175,685 U.S. Pat. No. 1,1944,382

[0007] An object of the present disclosure is to improve fundus hemodynamic measurement using Doppler OCT.

[0008] An ophthalmologic apparatus according to some embodiments includes a fundus image acquisition unit, a registration unit, a frontal vascular region detection unit, a three-dimensional vascular region identification unit, and an orientation information generation unit. The fundus image acquisition unit acquires a frontal fundus image and a three-dimensional fundus image of a subject's eye. The registration unit performs registration between the frontal fundus image and the three-dimensional fundus image. The frontal vascular region detection unit analyzes the frontal fundus image to detect a frontal vascular region. The three-dimensional vascular region identification unit identifies a three-dimensional vascular region in the three-dimensional fundus image that corresponds to the frontal vascular region in the frontal fundus image based on a result of the registration. The orientation information generation unit generates orientation information of the three-dimensional vascular region based on data of an intersection between a predetermined partial region in the three-dimensional fundus image and the three-dimensional vascular region.

[0009] According to some embodiments, it is possible to improve fundus hemodynamic measurements using Doppler OCT.

[0010] FIG. 1 is a schematic diagram showing a configuration of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 2 is a schematic diagram showing a configuration of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 3 is a schematic diagram showing a configuration of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 4 is a schematic diagram showing a configuration of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 5 is a schematic diagram showing an operation of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 6 is a schematic diagram showing an operation of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 7 is a schematic diagram showing an operation of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 8 is a schematic diagram showing an operation of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 9 is a schematic diagram showing an operation of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 10 is a schematic diagram showing an operation of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 11 is a flowchart showing an operation of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 12 is a schematic diagram showing an operation of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 13 is a schematic diagram showing an operation of an ophthalmic apparatus according to a non-limiting embodiment. Fig. 1 is a flowchart showing the operation of an ophthalmic apparatus according to a non-limiting embodiment;Fig. 2 is a schematic diagram for explaining the operation of an ophthalmic apparatus according to a non-limiting embodiment;Fig. 3 is a schematic diagram for explaining the operation of an ophthalmic apparatus according to a non-limiting embodiment;Fig. 4 is a schematic diagram for explaining the operation of an ophthalmic apparatus according to a non-limiting embodiment.

[0011] Several non-limiting embodiments of the present disclosure will be described. In the present disclosure, embodiments of an ophthalmic device (e.g., an ophthalmic blood flow measuring device, an ophthalmic imaging device, etc.), embodiments of a method for controlling an ophthalmic device, embodiments of a program, and embodiments of a recording medium will be described. However, the categories of embodiments of the present disclosure are not limited to these.

[0012] The embodiments according to the present disclosure can be employed to solve problems that arise in measuring the dynamics of fundus hemodynamics using Doppler OCT. There are various problems in measuring the dynamics of fundus hemodynamics using Doppler OCT.

[0013] Some embodiments of the present disclosure address the problem of the complexity of determining the position (blood flow measurement position) where fundus hemodynamic measurement is to be applied. Conventionally, a user determines the blood vessel or cross-sectional position where blood flow measurement is to be applied by referring to an infrared observation image (real-time video image) of the fundus or a previously acquired fundus photograph. Some embodiments provide a novel method for generating orientation information of fundus blood vessels. Furthermore, some embodiments use the generated orientation information to facilitate and reduce the work of specifying the blood flow measurement position. Furthermore, some embodiments improve the precision and accuracy of the work of specifying the blood flow measurement position. Furthermore, some embodiments enable the blood flow measurement position to be predicted to some extent. This allows the measurement application area and analysis application area to be limited before actually applying fundus hemodynamic measurement, further facilitating and reducing the work of specifying the blood flow measurement position.

[0014] Some embodiments of the present disclosure also address the following problem: The phase signal obtained by fundus hemodynamic measurement has a good contrast mechanism. However, when measurement is performed during the diastolic phase, when pulsation is relatively weak, the detected signal strength may be low, resulting in poor measurement quality. When measurement is performed on veins, which have a weaker pulsation than arteries, or when measurement is performed at an unsuitable Doppler angle, the detected signal strength may also be reduced, resulting in poor measurement quality. Furthermore, fundus blood vessels are distributed in a complex three-dimensional manner. The actual vascular course can be determined by performing fundus imaging. Conventionally, this information has not been utilized. Some embodiments address this problem by generating a map of blood vessels suitable for fundus hemodynamic measurement.

[0015] It will be understood by those skilled in the art that the problems that can be addressed using the technology disclosed herein are not limited to the examples given above.

[0016] <Embodiments of Ophthalmic Apparatus> Several non-limiting aspects of an ophthalmic apparatus according to an embodiment will be described. The ophthalmic apparatus according to the embodiment has a function of performing OCT blood flow measurement and a function of processing data obtained by the OCT blood flow measurement.

[0017] The ophthalmic device according to the embodiment mainly described in the present disclosure functions as an OCT device capable of performing OCT blood flow measurement (OCT scan and image generation processing). In some other embodiments, the ophthalmic device may not be capable of performing at least a part of the processing of OCT blood flow measurement.

[0018] The OCT method may be any method, for example, spectral domain OCT or swept-source OCT. Spectral domain OCT is a method in which light from a low-coherence light source is split into measurement light and reference light, return light of the measurement light from the test object is superimposed on the reference light to generate interference light, the spectral distribution of the interference light is detected with a spectrometer, and the detected spectral distribution is subjected to processing such as Fourier transform to construct an image. Swept-source OCT is a method in which light from a tunable light source is split into measurement light and reference light, return light of the measurement light from the test object is superimposed on the reference light to generate interference light, the interference light is detected with a photodetector (such as a balanced photodiode), and detection data collected in response to wavelength sweeping and scanning of the measurement light is subjected to processing such as Fourier transform to construct an image. That is, spectral domain OCT is an OCT method that acquires a spectral distribution by spatial division, while swept-source OCT is an OCT method that acquires a spectral distribution by time division. It should be noted that other OCT methods, such as time domain OCT, may also be used.

[0019] The ophthalmic device according to the embodiment mainly described in the present disclosure has a function as a fundus camera capable of photographing the fundus of the eye. In some other embodiments, the ophthalmic device may have a function as any ophthalmic imaging modality, such as an SLO, a slit lamp microscope, or a surgical microscope, in addition to or instead of the function as a fundus camera.

[0020] In this disclosure, unless otherwise specified, no distinction is made between "image data" and "images" that are visual information based on the image data. Furthermore, unless otherwise specified, no distinction is made between a site or tissue of the subject's eye and its image (image data).

[0021] An ophthalmologic apparatus according to some exemplary embodiments may not have a fundus imaging function. Such an ophthalmologic apparatus may have a function of acquiring a front image of the fundus from a storage device or a recording medium. A typical example of a storage device is a medical image archiving system (medical image filing system). A typical example of a recording medium is a hard disk drive or an optical disk.

[0022] At least a portion of the functionality of elements of embodiments of the present disclosure is implemented using circuitry or processing circuitry. The circuitry or processing circuitry may be a general-purpose processor, a special-purpose processor, an integrated circuit, a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), an Application Specific Integrated Circuit (ASIC), a programmable logic device (e.g., a Simple Programmable Logic Device (SPLD), a Complex Programmable Logic Device (CPLD), a Field Programmable Gate Array (FPGA)), or a combination of these devices configured and / or programmed to perform at least some of the disclosed functions. Array), conventional circuitry, and any combination thereof. A processor is considered to be processing circuitry or circuitry, including transistors and / or other circuitry. In this disclosure, circuitry, unit, means, or similar terms refers to hardware that performs at least a portion of the disclosed functions or hardware that is programmed to perform at least a portion of the disclosed functions. The hardware may be hardware disclosed herein or known hardware that is programmed and / or configured to perform at least a portion of the described functions. In the case of a processor, where the hardware can be considered to be a type of circuitry, circuitry, unit, means, or similar terms refers to a combination of hardware and software, and the software is used to configure the hardware and / or processor.

[0023] The configuration of an exemplary ophthalmic apparatus is shown in Figures 1 to 4. The ophthalmic apparatus 1 of this example includes a fundus camera unit 2, an OCT unit 100, and an arithmetic and control unit 200. The fundus camera unit 2 is provided with elements of a fundus camera capable of photographing the fundus and the anterior segment, and elements of an OCT scanner. The OCT unit 100 is provided with elements of an OCT scanner. The arithmetic and control unit 200 includes one or more processors configured to perform various processes (such as calculation, analysis, and control).

[0024] The fundus camera unit 2 will now be described. The fundus camera unit 2 includes an optical system for photographing the fundus Ef (and the anterior segment) of the subject's eye E. The digital image acquired by the fundus camera unit 2 is typically a front image. The fundus camera unit 2 can acquire observation images by video capture using near-infrared fixed light as illumination light, and can acquire photographed images by capture using visible flash light as illumination light, for example.

[0025] The fundus camera unit 2 includes an illumination optical system 10 and an imaging optical system 30. The illumination optical system 10 irradiates illumination light onto the subject's eye E. The imaging optical system 30 detects return light of the illumination light irradiated onto the subject's eye E. In other words, the imaging optical system 30 photographs the subject's eye E illuminated by the illumination light. OCT measurement light provided from the OCT unit 100 is guided to the subject's eye E through an optical path within the fundus camera unit 2. Return light of the OCT measurement light applied to the subject's eye E is guided to the OCT unit 100 through an optical path within the fundus camera unit 2.

[0026] The observation illumination light output from the observation light source 11 of the illumination optical system 10 is reflected by the concave mirror 12, passes through the condenser lens 13, and passes through the visible cut filter 14 to become near-infrared light. It is then focused near the imaging light source 15, reflected by the mirror 16, and passed through the relay lens system 17, the relay lens 18, the aperture 19, and the relay lens system 20 to be guided to the perforated mirror 21. It is reflected by the mirror portion around the central hole of the perforated mirror 21, passes through the dichroic mirror 46, is refracted by the objective lens 22, and is projected onto the subject's eye E (fundus Ef). The return light of the observation illumination light projected onto the subject's eye E is refracted by the objective lens 22, passes through the dichroic mirror 46, passes through the central hole of the perforated mirror 21, passes through the dichroic mirror 55, passes through the photographing focusing lens 31, is reflected by the mirror 32, 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 imaging lens 34. The image sensor 35 detects the return light at regular time intervals (frame rate). The focus of the photographing optical system 30 is adjusted according to the photographing region.

[0027] The imaging illumination light output from the imaging light source 15 is projected onto the fundus oculi Ef along the same path as the observation illumination light. The return light of the imaging illumination light from the subject's eye E is guided to the dichroic mirror 33 along the same path as the return light of the observation illumination light, passes through the dichroic mirror 33, is reflected by a mirror 36, and is imaged by an imaging lens 37 on the light-receiving surface of an image sensor 38.

[0028] The liquid crystal display (LCD) 39 displays a fixation target (fixation target image) for guiding and fixing the line of sight. The light beam output from the liquid crystal display 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, passes through the central hole 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. This allows the subject to visually recognize the fixation target.

[0029] The alignment optical system 50 generates an alignment index for aligning the ophthalmic apparatus 1 with respect to the subject's eye E. Alignment light output from a light-emitting diode (LED) 51 passes through an aperture 52, an aperture 53, and a relay lens 54, is reflected by a dichroic mirror 55, passes through the central hole of the perforated mirror 21, transmits through the dichroic mirror 46, and is projected onto the subject's eye E via the objective lens 22. The return light of the alignment light from the subject's eye E is guided to the image sensor 35 via the same path as the return light of the observation illumination light. Manual alignment or automatic alignment can be performed by referring to the received light image (alignment index image).

[0030] The focusing optical system 60 generates a split index used for focus adjustment of the subject's eye E. The focusing optical system 60 moves along the optical path (illumination optical path) of the illumination optical system 10 in conjunction with movement of the photographing focusing lens 31 along the optical path (photography optical path) of the photographing optical system 30. The reflecting rod 67 is inserted into and removed from the illumination optical path. When performing focus adjustment, the reflective surface of the reflecting rod 67 is tilted relative to the illumination optical path. The focusing light output from the LED 61 passes through the relay lens 62, is split into two beams by the split index plate 63, passes through the two-hole diaphragm 64, is reflected by the mirror 65, is once imaged and reflected by the condenser lens 66 on the reflective surface of the reflecting rod 67, passes through the relay lens 20, is reflected by the perforated mirror 21, passes through the dichroic mirror 46, and is projected onto the subject's eye E via the objective lens 22. The returning light of the focusing light from the subject's eye E is guided to the image sensor 35 along the same path as the returning light of the alignment light. By referring to the received light image (split target image), manual focusing or autofocusing can be performed.

[0031] If the subject's eye E is highly hyperopic, a diopter correction lens 70 (plus lens) is placed in the photographing optical path between the perforated mirror 21 and the dichroic mirror 55. On the other hand, if the subject's eye E is highly myopic, a diopter correction lens 71 (minus lens) is placed.

[0032] The dichroic mirror 46 combines the optical path for imaging by the fundus camera unit 2 with the optical path for OCT (measurement arm). The dichroic mirror 46 reflects light in the wavelength band for OCT and transmits light in the wavelength band for imaging by the fundus camera unit 2. The measurement arm is provided with, in order from the OCT unit 100 side, 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. The retroreflector 41 is movable along the optical path of the OCT measurement light incident thereon and is used to correct the optical path length according to the axial length and adjust the interference state. The dispersion compensation member 42 is used for dispersion compensation between the measurement arm and the reference arm. The OCT focusing lens 43 is movable along the measurement arm and is used to adjust the focus of the measurement arm. Focus adjustment of the ophthalmologic apparatus 1 is performed by coordination of movement of the imaging focusing lens 31, movement of the focusing optical system 60, and movement of the OCT focusing lens 43. The optical scanner 44 is positioned at a position substantially conjugate with the pupil of the subject's eye E through alignment, and changes the traveling direction of the OCT measurement light. The optical scanner 44 is, for example, a galvano scanner capable of two-dimensional scanning.

[0033] The OCT unit 100 will now be described. The OCT unit 100 shown in FIG. 2 is equipped with a spectral domain OCT optical system. This OCT optical system includes an interference optical system. This interference optical system splits light from a low-coherence light source (broadband light source) into measurement light LS (OCT measurement light) and reference light LR, and generates interference light LC by superimposing the return light of the measurement light LS projected onto the subject's eye E on the reference light LR. The generated interference light LC is detected by a spectroscope 130. This provides a signal indicating the spectral distribution of the interference light LC. This detection signal is sent to the arithmetic and control unit 200.

[0034] The light source unit 101 outputs broadband low-coherence light L0. The light source unit 101 includes an optical output device such as a superluminescent diode (SLD), an LED, or a semiconductor optical amplifier (SOA). The low-coherence light L0 output from the light source unit 101 is guided by an optical fiber 102 to a polarization controller 103 where its polarization state is adjusted, and then guided by an optical fiber 104 to a fiber coupler 105 where it is split into a measurement light LS and a reference light LR. The measurement light LS is guided by a measurement arm, and the reference light LR is guided by a reference arm.

[0035] The reference light LR is guided by an optical fiber 110 to a collimator 111 and converted into a parallel beam, passes through an optical path length correction member 112 for compensating for the optical distance between the measurement arm and the reference arm, passes through a dispersion compensation member 113 for compensating for dispersion between the measurement arm and the reference arm, and is then guided to a retroreflector 114. The retroreflector 114 is movable along the optical path of the reference light LR incident thereon and is used to correct the optical path length according to the axial length and adjust the interference state. The reference light LR that has passed through the retroreflector 114 passes through the dispersion compensation member 113 and the optical path length correction member 112 and is converted from a parallel beam into a focused beam by a collimator 116, is guided through an optical fiber 117 to a polarization controller 118 for adjusting its polarization state, is guided through an optical fiber 119 to an attenuator 120 for adjusting its light intensity, and reaches a fiber coupler 122 through an optical fiber 121.

[0036] On the other hand, the measurement light LS is guided through the optical fiber 127 to the collimator lens unit 40, where it is converted into a parallel beam, passes through the retroreflector 41, the dispersion compensation member 42, the OCT focusing lens 43, the optical scanner 44, and the relay lens 45, is reflected by the dichroic mirror 46, is refracted by the objective lens 22, and is projected onto the subject's eye E. The measurement light LS is scattered and reflected at various depth positions in the subject's eye E. Return light of the measurement light LS from the subject's eye E travels in the opposite direction through the measurement arm, is guided to the fiber coupler 105, and reaches the fiber coupler 122 via the optical fiber 128.

[0037] The fiber coupler 122 generates interference light LC by superimposing the measurement light LS incident via the optical fiber 128 and the reference light LR incident via the optical fiber 121. The generated interference light LC is guided to the spectrometer 130 via the optical fiber 129. In a non-limiting example, the spectrometer 130 converts the incident interference light LC into a parallel beam using a collimator lens, resolves the parallel beam of interference light LC into multiple spectral components using a diffraction grating, and projects the multiple spectral components generated by the diffraction grating onto an image sensor via a lens. This image sensor is, for example, a line sensor, and detects the multiple spectral components of the interference light LC to generate an electrical signal (detection signal). The generated detection signal contains information about the spectral distribution of the interference light LC and is sent to the arithmetic and control unit 200.

[0038] The OCT unit 100 in FIG. 2 described above employs a spectral domain OCT system. When swept-source OCT is used, the light source unit 101 includes a tunable light source (e.g., a near-infrared tunable laser) that rapidly changes the wavelength of emitted light. Furthermore, in the swept-source OCT optical system, interference light LC, generated by superimposing the measurement light LS and the reference light LR, is split at a predetermined splitting ratio (e.g., 1:1) to generate a pair of interference light beams, which are then detected by a photodetector. The photodetector includes a balanced photodiode. The balanced photodiode includes a pair of photodetectors that respectively detect the pair of interference light beams and outputs the difference between the pair of detection signals obtained by the pair of photodetectors. The photodetector sends this difference signal to a data acquisition system (DAQ). A clock is supplied to the data acquisition system from the light source unit 101. This clock 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. For example, the light source unit 101 splits light of each output wavelength to generate two split lights, optically delays one of the split lights, and then combines the two split lights, detects the resulting combined light, and generates a clock based on the detection signal. The data collection system samples the detection signal (differential signal) input from the photodetector using the clock provided by the light source unit 101. The data obtained by this sampling is provided for processing such as image generation.

[0039] In the examples shown in FIGS. 1 and 2 , optical path length changing elements (retroreflectors 41 and 114) are provided in both the measurement arm and the reference arm, but only one of them may be provided. Furthermore, the optical path length changing elements are not limited to retroreflectors. For example, the optical path length changing element in the reference arm may be a movable reflecting member (reference mirror). More generally, the ophthalmic device according to the present disclosure includes an element configured to relatively change the measurement arm length and the reference arm length (i.e., an element configured to change the optical path length difference between the measurement arm and the reference arm), and this element can be used to move the coherence gate position.

[0040] The arithmetic and control unit 200 will be described. The arithmetic and control unit 200 executes various processes, such as controlling each component of the ophthalmologic apparatus 1, various calculations, and various analyses. For example, the arithmetic and control unit 200 performs signal processing, such as Fourier transform, on the spectral distribution (interference signal, interferogram) acquired by the spectroscope 130 to calculate a reflection intensity profile of a line (A-line) extending in the depth direction (z direction) at each projection position of the measurement light LS. Furthermore, the arithmetic and control unit 200 generates image data by imaging the reflection intensity profile of each A-line. The arithmetic and control unit 200 may perform the same calculation process as image generation using conventional spectral domain OCT. The arithmetic and control unit 200 includes, for example, a processor, RAM, ROM, a hard disk drive, a communication interface, etc. Various computer programs are stored in the storage device, such as the hard disk drive. The arithmetic and control unit 200 may also include an operation device, an input device, a display device, etc.

[0041] The user interface 240 shown in FIG. 3 will be described. The user interface 240 has a display unit 241 and an operation unit 242. The display unit 241 includes, for example, the display device 3 of FIG. 1. The operation unit 242 includes various operation devices and input devices. The user interface 240 may include a touch panel. In some exemplary embodiments, at least a portion of the user interface is provided as a peripheral device connected to the ophthalmologic apparatus 1.

[0042] The moving mechanism 150 shown in Fig. 3 will be described. The moving mechanism 150 is configured to move the optical system of the ophthalmologic apparatus 1. The moving mechanism 150 moves, for example, at least the fundus camera unit 2 three-dimensionally.

[0043] The data input / output unit 290 shown in FIG. 3 will be described. The data input / output unit 290 inputs data to the ophthalmologic apparatus 1 and outputs data from the ophthalmologic apparatus 1. A non-limiting example of the data input / output unit 290 has a function for communicating with an external device (not shown). The communication unit 290 includes a communication interface according to the connection configuration with the external device. The external device may be, for example, any ophthalmologic apparatus. The external device may also be any information processing device, such as a Hospital Information System (HIS) server, a DICOM (Digital Imaging and Communication in Medicine) server, a doctor's terminal, a mobile terminal, a personal terminal, or a cloud server. Some exemplary examples of the data input / output unit 290 include a device (data reader) that reads information from a recording medium and a device (data writer) that writes information to the recording medium. The data input / output unit 290 may be, but is not limited to, the above.

[0044] The processing system (arithmetic and control system) of the ophthalmologic apparatus 1 will now be described. An example of the configuration of the processing system is shown in Figures 3 and 4. The control unit 210 and the data processing unit 230 are provided in the arithmetic and control unit 200.

[0045] The control unit 210 includes a processor and controls each unit of the ophthalmic apparatus 1. The control unit 210 includes a main control unit 211 and a memory unit 212. The main control unit 211 includes a processor and is configured to control each element of the ophthalmic apparatus 1 (including the elements shown in FIGS. 1 to 3). The main control unit 211 may also be configured to be able to control apparatuses, devices, and systems connected to the ophthalmic apparatus 1. The functions of the main control unit 211 are realized, for example, by cooperation between hardware including circuits and control software. The memory unit 212 stores various types of data. The memory unit 212 includes a storage device such as a hard disk drive or a solid state drive.

[0046] Several controls executed by the main controller 211 will be described. The main controller 211 controls an imaging focusing driver (not shown) to synchronously move the imaging focusing lens 31 and the focus optical system 60. The main controller 211 controls a retroreflector (RR) driver 41A to move the retroreflector 41 of the measurement arm. The main controller 211 controls an OCT focusing driver 43A to move the OCT focusing lens 43 of the measurement arm. The main controller 211 controls the optical scanner 44 to deflect the measurement light LS according to a preset scan pattern. The main controller 211 controls a retroreflector (RR) driver 114A to move the retroreflector 114 of the reference arm. The main controller 211 controls a moving mechanism 150 to move the optical system (e.g., the fundus camera unit 2 and the OCT unit 100).

[0047] The data processing unit 230 performs various types of data processing. For example, the data processing unit 230 applies various types of processing to images (fundus images, anterior segment images, etc.) acquired by the fundus camera unit 2. The data processing unit 230 also applies various types of processing to images acquired using OCT scanning (OCT images). The data processing unit 230 includes a processor. The data processing unit 230 is realized, for example, by cooperation between hardware including circuits and data processing software.

[0048] The data processing unit 230 includes an image generation unit 220. The image generation unit 220 processes data collected by applying an OCT scan to the fundus Ef of the subject's eye E to generate OCT image data. The image generation unit 220 includes a processor. The functions of the image generation unit 220 are realized, for example, by cooperation between hardware including circuits and image generation software.

[0049] The image generating unit 220 is configured to perform a process of generating an OCT intensity image that represents the intensity of the interference signal as visual information, and a process of generating a phase image that represents the phase information of the interference signal as visual information. A non-limiting example of the process of generating the intensity image will be described below. A non-limiting example of the process of generating the phase image will be described later, along with a description of the theoretical aspects of OCT blood flow measurement.

[0050] The image generator 220 generates an intensity image based on the data (interference signal) acquired by the spectrometer 130. Similar to conventional spectral-domain OCT, this intensity image generation process includes signal processing such as A / D conversion, denoising, filtering, and fast Fourier transform (FFT). The fast Fourier transform converts the interference signal acquired by the spectrometer 130 into an A-line profile (a reflection intensity profile along the z-direction). The A-line profile is visualized by applying imaging processing (a process of assigning pixel values ​​to reflection intensity values) to the A-line profile. This results in A-scan image data. By arranging multiple A-scan images according to a scan pattern, a cross-sectional image (e.g., B-scan image data, circle scan image data, etc.) corresponding to the scan pattern is constructed. When another OCT method is used, the cross-sectional image generator 221 performs known processing appropriate to the type of OCT method.

[0051] In some embodiments, the intensity image may be a dataset including a group of A-scan image data obtained by visualizing the reflection intensity profile of multiple A-lines arranged in the area where the OCT scan was performed. In other words, in some embodiments, the intensity image may be a dataset including a group of A-scan image data and their position information (coordinates). In another embodiment, the intensity image may be stack data constructed by embedding multiple B-scan images in a single three-dimensional coordinate system, i.e., a dataset including multiple B-scan images and their position information. In yet another embodiment, the intensity image may be volume data (voxel data) generated by applying a voxelization process to the stack data. Stack data and volume data are non-limiting examples of three-dimensional image data in which pixel coordinates are defined using a three-dimensional coordinate system. The process of generating the three-dimensional image data is performed by the image generation unit 220.

[0052] The image generation unit 220 can process the three-dimensional image data. For example, the image generation unit 220 can generate new image data by applying rendering to the three-dimensional image data. Rendering techniques include volume rendering, surface rendering, multiplanar reconstruction (MPR), maximum intensity projection (MIP), minimum intensity projection (MinIP), and average intensity projection (AIP). The image generation unit 220 can construct projection data by integrating (projecting) the three-dimensional image data in the z direction. The image generation unit 220 can construct a shadowgram by integrating (projecting) a portion of the three-dimensional image data (three-dimensional partial image data) in the z direction. The three-dimensional partial image data is extracted from the three-dimensional image data using any image segmentation method.

[0053] The ophthalmologic apparatus 1 can apply OCT blood flow measurement to the fundus Ef. The theoretical aspects of OCT blood flow measurement will be described below, as well as some non-limiting aspects of OCT blood flow measurement.

[0054] In a non-limiting aspect, blood flow measurement applies two types of scans (main scan and supplemental scan) to the fundus Ef. In the main scan, a region of interest (cross section of interest) that intersects with a blood vessel of interest in the fundus Ef at a position of interest is repeatedly scanned with the measurement light LS to acquire phase image data. On the other hand, in the supplemental scan, a predetermined cross section (supplemental cross section) is scanned with the measurement light LS to estimate the inclination of the blood vessel of interest in the cross section of interest. In a non-limiting aspect, the supplemental cross section may be, for example, a cross section (first supplemental cross section) that intersects with the blood vessel of interest and is located near the cross section of interest. In another non-limiting aspect, the supplemental cross section may be a cross section (second supplemental cross section) that intersects with the cross section of interest and is aligned with the blood vessel of interest. The inclination of the blood vessel of interest is the angle between the measurement light LS projected onto the cross section of interest and the blood vessel of interest, which is the Doppler angle in Doppler OCT.

[0055] An example of the application of the first supplemental cross section is shown in FIG. 5A. In this example, as shown in a fundus image D, one cross section of interest C0 located near the optic disc Da of the fundus oculi Ef and two supplemental cross sections C1 and C2 located nearby are set to intersect with a blood vessel of interest Db. One of the two supplemental cross sections C1 and C2 is located upstream of the blood vessel of interest Db relative to the cross section of interest C0, and the other is located downstream. The cross section of interest C0 and the supplemental cross sections C1 and C2 are oriented, for example, approximately perpendicular to the running direction of the blood vessel of interest Db.

[0056] An example of a case where the second supplemental cross section is applied is shown in FIG. 5B. In this example, a cross section of interest C0 similar to the example shown in FIG. 5A is set so as to be approximately perpendicular to the blood vessel of interest Db, and a supplemental cross section Cp is set so as to be approximately perpendicular to the cross section of interest C0. The supplemental cross section Cp is set along the blood vessel of interest Db. As an example, the supplemental cross section Cp may be set so as to pass through the central axis of the blood vessel of interest Db at the position of the cross section of interest C0.

[0057] It is desirable for the main scan in OCT blood flow measurement to collect data over a period that includes at least one cardiac cycle of the subject's heart. This makes it possible to determine the hemodynamics of blood flow in all cardiac phases. The time period for performing the main scan may be a fixed period that is set in advance, or may be a period set for each subject or each examination. This fixed period has traditionally been set to a period (e.g., 2 seconds) that is sufficiently longer than a standard cardiac cycle. Furthermore, the period set for each subject or each examination has traditionally been determined by referring to data from a biosignal detector such as an electrocardiograph.

[0058] The image generating unit 220 includes a cross-sectional image generating unit 221 and a phase image generating unit 222. The cross-sectional image generating unit 221 includes a processor, and its functions are realized, for example, by cooperation between hardware including a circuit and cross-sectional image generating software. The phase image generating unit 222 includes a processor, and its functions are realized, for example, by cooperation between hardware including a circuit and phase image generating software.

[0059] The cross-sectional image generating unit 221 generates an intensity image based on data collected by an OCT scan of the fundus oculi Ef. The intensity image generating process may be the same as a conventional image generating method in the spectral domain OCT method.

[0060] The cross-sectional image generating unit 221 generates cross-sectional images (main cross-sectional images) representing time-series changes in the morphology of the cross-section of interest based on interference signals obtained by the spectroscope 130 during main scanning of the cross-section of interest of the fundus oculi Ef. As described above, during main scanning, the ophthalmologic apparatus 1 applies repeated scans to the cross-section of interest C0. These repeated scans include multiple B-scans for the cross-section of interest C0. The interference signals sequentially generated by the spectroscope 130 in the multiple B-scans are sequentially input to the cross-sectional image generating unit 221. The cross-sectional image generating unit 221 generates one main cross-sectional image corresponding to the cross-section of interest C0 based on the interference signals corresponding to each B-scan. The cross-sectional image generating unit 221 repeats this process the number of times the B-scan is repeated during main scanning, thereby generating a series of main cross-sectional images in time series. In this way, the cross-sectional image generating unit 221 generates multiple intensity images corresponding to the multiple B-scans based on the data set collected by the repeated scanning of the main scanning. In some exemplary embodiments, the image quality of the main cross-sectional images can be improved by dividing a series of main cross-sectional images obtained by main scanning into multiple groups, and applying image synthesis (e.g., averaging) to the main cross-sectional images included in each group to generate multiple composite images.

[0061] The cross-sectional image generating unit 221 generates a cross-sectional image (supplementary cross-sectional image) representing the morphology of the supplementary cross-section based on an interference signal obtained by the spectroscope 130 during supplementary scanning of the supplementary cross-section of the fundus oculi Ef. The process of generating the supplementary cross-sectional image is performed in the same manner as the process of generating the main cross-sectional image. The supplementary cross-sectional image may be one cross-sectional image or two or more cross-sectional images. In some exemplary embodiments, the image quality of the supplementary cross-sectional image can be improved by scanning the supplementary cross-section multiple times to generate multiple cross-sectional images and applying image synthesis to these cross-sectional images to generate a synthesized image. When the supplementary cross-sections C1 and C2 illustrated in FIG. 5A are applied, the cross-sectional image generating unit 221 generates a supplementary cross-sectional image corresponding to the supplementary cross-section C1 and a supplementary cross-sectional image corresponding to the supplementary cross-section C2. When the supplementary cross-section Cp illustrated in FIG. 5B is applied, the cross-sectional image generating unit 221 generates a supplementary cross-sectional image corresponding to the supplementary cross-section Cp.

[0062] The phase image generating unit 222 generates a phase image representing a time-series change in the phase difference in the cross section of interest based on the interference signal obtained by the spectroscope 130 during the main scan. The interference signal used to generate the phase image may be the same as the interference signal used to generate the principal cross section image by the cross section image generating unit 221. In this case, a natural positional correspondence is defined between the pixels of the principal cross section image and the pixels of the phase image, making it easy to align the principal cross section image and the phase image. In contrast, in some embodiments, the principal cross section image and the phase image may be generated from different interference signals. In this case, for example, a known image registration method can be used to align the principal cross section image and the phase image.

[0063] A non-limiting example of a process for generating a phase image will now be described. The phase image in this example is obtained by calculating the phase difference between adjacent A-line complex signals (i.e., signals corresponding to adjacent scanning points). In other words, the phase image in this example is generated based on the time-series changes in pixel values ​​(brightness values) of the principal cross-sectional image. For any pixel in the principal cross-sectional image, the phase image generating unit 222 creates a graph showing the time-series changes in the brightness value of that pixel. The phase image generating unit 222 calculates the phase difference Δφ between two time points t1 and t2 (t2 = t1 + Δt) that are separated by a predetermined time interval Δt in this graph. This phase difference Δφ is then defined as the phase difference Δφ(t1) at time point t1 (or more generally, any time point between time points t1 and t2). By performing this series of processes for each of a number of preset time points, the time-series changes in the phase difference at that pixel can be obtained. Note that the time-series changes in the phase difference can be obtained by making the time interval Δt sufficiently small to ensure phase correlation. For this reason, the scanning (main scanning) of the measuring light LS executes oversampling in which the time interval Δt is set to a value smaller than the time corresponding to the resolution of the cross-sectional image.

[0064] A phase image is an image obtained by visually representing the phase difference value of each pixel at each time point (imaging process). This imaging process includes, for example, a process of representing the phase difference value using predetermined display parameters (e.g., display color, brightness, etc.). Some imaging processes can use different display colors to indicate an increase in phase over time and a decrease in phase over time. For example, an increase in phase over time can be represented by red, and a decrease can be represented by blue. Furthermore, some imaging processes can represent the magnitude of phase change (phase change amount) as the intensity of the display color. Some imaging processes described herein enable visualization of the direction and magnitude of blood flow. A phase image is generated by performing such imaging process on each pixel.

[0065] The data processing unit 230 includes, as exemplary elements for obtaining hemodynamic information, a vascular region specifying unit 231 and a hemodynamic information generating unit 232. The hemodynamic information generating unit 232 may include a Doppler angle calculating unit 233, a blood flow velocity calculating unit 234, a vascular diameter calculating unit 235, and a blood flow amount calculating unit 236.

[0066] The vascular region specifying unit 231 includes, for example, a processor operable according to a vascular region specifying program. The hemodynamic information generating unit 232 includes, for example, a processor operable according to a hemodynamic information generating program. The Doppler angle calculating unit 233 includes, for example, a processor operable according to a Doppler angle calculation program. The blood flow velocity calculating unit 234 includes, for example, a processor operable according to a blood flow velocity calculation program. The blood vessel diameter calculating unit 235 includes, for example, a processor operable according to a blood vessel diameter calculation program. The blood flow volume calculating unit 236 includes, for example, a processor operable according to a blood flow volume calculation program.

[0067] The vascular region identifying unit 231 analyzes an OCT image of the fundus and identifies an image region (vascular region) corresponding to a blood vessel in the OCT image. The vascular region identifying unit 231 also analyzes a front image of the fundus (e.g., an observed image or a photographed image acquired by the fundus camera unit 2) and identifies an image region (vascular region) corresponding to a blood vessel in the front image. The vascular region identifying process performed by the vascular region identifying unit 231 may be image processing using any image segmentation, and is performed, for example, by analyzing pixel values ​​in the target image (e.g., threshold processing). In some embodiments, the vascular region identifying unit 231 identifies a vascular region corresponding to the blood vessel of interest Db from each of the principal cross-sectional image, the supplementary cross-sectional image, and the phase image.

[0068] In some cases, the principal and supplementary cross-sectional images have sufficient resolution to be analyzed in the vascular region identification process, while the phase images do not have sufficient resolution to identify the boundaries of the vascular regions. Even in such cases, since hemodynamic information is generated based on the phase images, it is necessary to identify the vascular regions in the phase images with high accuracy. For this purpose, for example, the following process can be adopted.

[0069] When the principal cross-sectional image and the phase image are generated based on the same interference signal, the natural positional correspondence relationship (described above) defined between the pixels of the principal cross-sectional image and the pixels of the phase image can be utilized. For example, the vascular region identifying unit 231 can perform a process of analyzing the principal cross-sectional image to identify a vascular region and a process of identifying an image region in the phase image corresponding to the vascular region in the principal cross-sectional image based on the positional correspondence relationship. The image region in the phase image is adopted as the vascular region in the phase image. This allows the vascular region in the phase image to be determined with high accuracy. When the principal cross-sectional image and the phase image are generated based on mutually different interference signals, the vascular region in the phase image can be determined by utilizing the result of image registration (described above) between the principal cross-sectional image and the phase image instead of the natural positional correspondence relationship.

[0070] The hemodynamic information generating unit 232 generates information indicating the hemodynamics of the blood flow in the fundus blood vessels (hemodynamic information). The hemodynamic information may be information on any parameter (hemodynamic parameter) indicating the fundus hemodynamics. Although the present disclosure describes blood velocity and blood volume, the hemodynamic parameters are not limited to these.

[0071] The hemodynamic information generator 232 generates hemodynamic information regarding the interested blood vessel Db. As described above, the hemodynamic information generator 232 in some embodiments includes a Doppler angle calculator 233, a blood flow velocity calculator 234, a blood vessel diameter calculator 235, and a blood flow amount calculator 236.

[0072] The Doppler angle calculation unit 233 calculates an estimated value of the tilt of the blood vessel of interest based on data of the supplementary cross section (cross-sectional data, supplementary cross-sectional image) collected by the supplementary scan. The calculated value may be, for example, a value based on a measurement value of the tilt of the blood vessel of interest on the cross section of interest, or an approximate value thereof. As described above, the tilt of the blood vessel of interest is a parameter equivalent to the Doppler angle in Doppler OCT. That is, the Doppler angle is the angle between the incident direction of the measurement light LS in the main scan on the cross section of interest and the direction of the axis of the blood vessel of interest (i.e., the tilt of the blood vessel of interest), and therefore the tilt of the blood vessel of interest is equivalent to the Doppler angle.

[0073] An example of actually measuring the gradient value of the blood vessel of interest will be described (first example of gradient estimation). When the supplementary cross sections C1 and C2 shown in Fig. 5A are applied, the Doppler angle calculation unit 233 can calculate the gradient of the blood vessel of interest Db on the cross section of interest C0 based on the positional relationship between the cross section of interest C0, the supplementary cross sections C1, and the supplementary cross sections C2, and the vascular region identification result obtained by the vascular region identification unit 231.

[0074] A method for calculating the gradient of the blood vessel of interest Db will be described with reference to FIG. 6A . The symbols G0, G1, and G2 respectively denote the principal cross-sectional image at the cross-section of interest C0, the supplementary cross-section image at the supplementary cross-section C1, and the supplementary cross-section image at the supplementary cross-section C2. The symbols V0, V1, and V2 respectively denote the vascular region in the principal cross-sectional image G0, the vascular region in the supplementary cross-section image G1, and the vascular region in the supplementary cross-section image G2. The z-coordinate axis shown in FIG. 6A substantially coincides with the incident direction of the measurement light LS. The distance between the principal cross-sectional image G0 (cross-section of interest C0) and the supplementary cross-sectional image G1 (supplementary cross-section C1) is denoted by d, and the distance between the principal cross-sectional image G0 (cross-section of interest C0) and the supplementary cross-sectional image G2 (supplementary cross-section C2) is also denoted by d. The distance between adjacent cross-sectional images, i.e., the distance between adjacent cross-sections, is called the inter-section distance.

[0075] The Doppler angle calculation unit 233 can calculate the gradient A of the blood vessel of interest Db in the cross section of interest C0 based on the positional relationship between the three vascular regions V0, V1, and V2. This positional relationship can be determined, for example, by connecting the three vascular regions V0, V1, and V2. As a specific example, the Doppler angle calculation unit 233 can identify the characteristic positions of each of the three vascular regions V0, V1, and V2 and connect these characteristic positions. This characteristic position may be, for example, one of the center position, the center of gravity position, the top (the position with the smallest z-coordinate value), and the bottom (the position with the largest z-coordinate value). The characteristic positions may be connected by any method, such as connecting them with a line segment or an approximation curve (such as a spline curve or a Bezier curve).

[0076] Furthermore, the Doppler angle calculation unit 233 calculates the gradient A of the blood vessel of interest Db in the cross section of interest C0 based on a connecting line connecting the characteristic positions identified from the three vascular regions V0, V1, and V2. If the connecting line is a line segment, the Doppler angle calculation unit 233 can calculate the gradient A based on the gradient of a first line segment connecting the characteristic position of the cross section of interest C0 to the characteristic position of the supplementary cross section C1 and the gradient of a second line segment connecting the characteristic position of the cross section of interest C0 to the characteristic position of the supplementary cross section C2. A non-limiting example of this calculation process may be calculating the average gradient of the two line segments. If the connecting line is an approximated curve, the Doppler angle calculation unit 233 can calculate the gradient A as the gradient of the approximated curve at the position where the approximated curve intersects with the cross section of interest C0. In the Doppler angle calculation process, the inter-section distance d is used, for example, when embedding the cross-sectional images G0 to G2 in an xyz coordinate system to calculate the connecting line.

[0077] In the above example, the vascular region in three cross sections is considered. In some embodiments, the gradient may be calculated by considering two cross sections. As a non-limiting example, the gradient A of the blood vessel Db of interest in the cross section C0 of interest may be calculated as the gradient of the first line segment or the gradient of the second line segment. Alternatively, the gradient A of the blood vessel Db of interest in the cross section C0 of interest may be calculated based on two supplementary cross-sectional images G1 and G2.

[0078] An example of calculating an approximate value of the gradient of the blood vessel of interest (second example of gradient estimation) will be described below. When the supplementary cross section Cp shown in FIG. 5B is applied, the Doppler angle calculation unit 233 can analyze the supplementary cross section image corresponding to the supplementary cross section Cp to calculate an approximate value of the gradient of the blood vessel of interest Db on the cross section C0 of interest.

[0079] A method for approximating the gradient of the blood vessel of interest Db will be described with reference to Fig. 6B. The symbol Gp denotes a supplemental cross-sectional image at the supplemental cross-section Cp. The symbol A denotes the gradient of the blood vessel of interest Db at the cross-section of interest C0, similar to the example shown in Fig. 6A.

[0080] In this example, the Doppler angle calculation unit 233 can analyze the supplemental cross-sectional image Gp to identify an image region corresponding to a predetermined tissue of the fundus oculi Ef. For example, the Doppler angle calculation unit 233 can identify an image region (internal limiting membrane region) M corresponding to the internal limiting membrane (ILM), which is a superficial tissue of the retina. To identify the image region, for example, a known image segmentation method is used.

[0081] It is known that the internal limiting membrane and the fundus blood vessels are approximately parallel to each other. The Doppler angle calculation unit 233 calculates the gradient A of the internal limiting membrane region M on the cross section C0 of interest. ａｐｐ The gradient A of the inner limiting membrane region M in the cross section C0 of interest is calculated. ａｐｐ is used as an approximation of the gradient A of the blood vessel Db of interest in the cross section C0 of interest.

[0082] 6A and 6B is a vector representing the direction of the blood vessel of interest Db, and its value may be defined arbitrarily. In some non-limiting examples, the value of the gradient A can be defined as the angle (Doppler angle) formed by the gradient (vector) A and the z-axis. Similarly, the gradient A shown in FIG. ａｐｐ is a vector representing the direction of the inner limiting membrane region M, and its value may be defined arbitrarily. For example, the gradient (vector) A ａｐｐ The angle between the z-axis and the Doppler angle is the gradient A. ａｐｐ Here, the orientation of the z-axis substantially coincides with the incident direction of the measurement light LS.

[0083] As a third example of estimating the gradient of the blood vessel of interest, the Doppler angle calculation unit 233 can analyze the supplementary cross-sectional image Gp shown in FIG. 6B to identify an image region corresponding to the blood vessel of interest Db and determine the gradient of the image region at a position corresponding to the cross section of interest C0. In this case, the Doppler angle calculation unit 233 can, for example, perform a curve approximation on the boundary or central axis of the image region corresponding to the blood vessel of interest Db and determine the gradient of the approximated curve at a position corresponding to the cross section of interest C0. It is also possible to apply a similar curve approximation to an image region corresponding to a specific tissue of the fundus oculi Ef described above (for example, the internal limiting membrane region M).

[0084] The processing performed by the Doppler angle calculation unit 233 is not limited to the above example, and may be any processing that can obtain an estimated value of the inclination of the blood vessel Db of interest (e.g., the inclination value of the blood vessel Db itself, its approximate value, etc.) based on cross-sectional data collected by applying an OCT scan to a cross section of the fundus Ef.

[0085] The blood flow velocity calculation unit 234 calculates the blood flow velocity of blood flowing through the blood vessel Db at the cross section C0 of interest based on information on the time-series change in phase difference obtained as a phase image. The calculated information may be the value of the blood flow velocity at a specific time point (blood flow velocity value) or the time-series change in the blood flow velocity value (blood flow velocity change information). The blood flow velocity value may be a value at a specific cardiac phase selected from the cardiac cycle (e.g., the R-wave phase). The period for which the blood flow velocity change information is defined may be the entire period during which the main scan is applied to the cross section C0 of interest, or may be a selected portion of that period.

[0086] When the blood flow velocity change information is obtained, the blood flow velocity calculation unit 234 may calculate a statistical value of the blood flow velocity during the measurement period. This statistical value may be, for example, any of the mean value, standard deviation, variance, median, mode, maximum value, minimum value, local maximum value, and local minimum value. However, it is not limited to these. Furthermore, when the blood flow velocity change information is obtained, the change in the blood flow velocity can be visualized to generate visual information (e.g., a graph, a histogram, etc.).

[0087] The blood flow velocity calculation unit 234 calculates the blood flow velocity using the Doppler OCT technique. At this time, the gradient A (or its approximate value A) of the blood vessel Db of interest in the cross section C0 calculated by the Doppler angle calculation unit 233 is used. ａｐｐ Specifically, the blood flow velocity calculation unit 234 can use the following formula: Δf=[2nv cos θ] / λ.

[0088] Here, Δf indicates the Doppler shift experienced by the scattered light of the measurement light LS; n indicates the refractive index of the medium; v indicates the flow velocity (blood flow velocity) of the medium; θ indicates the angle between the incident direction of the measurement light LS and the flow vector of the medium; and λ indicates the central wavelength of the measurement light LS.

[0089] In some embodiments, n and λ are known, Δf is obtained from the time series of the phase difference, and θ is the Doppler angle (slope A or approximate value A ａｐｐ The blood flow velocity calculation unit 234 calculates the blood flow velocity v by substituting the medium refractive index n, the central wavelength λ of the measurement light LS, the Doppler shift Δf, and the Doppler angle θ into the above equation: v = [λΔf] / [2n cos θ]. Note that the method for calculating the blood flow velocity is not limited to the method described here, and any method that can be employed in Doppler OCT may be used.

[0090] The blood vessel diameter calculation unit 235 calculates the diameter of the blood vessel Db of interest in the cross section C0 of interest. Examples of this calculation method include a first calculation method using a frontal fundus image and a second calculation method using a cross section image.

[0091] When the first calculation method is applied, an image of the area of ​​the fundus Ef including the position of the cross section of interest C0 is captured in advance. The resulting frontal fundus image may be, for example, a frame of an observed image, a captured image (color image, fluorescent contrast image), or an OCT angiography image (motion contrast image).

[0092] The blood vessel diameter calculation unit 235 sets the scale of the front fundus image based on various factors that determine the relationship between the scale in the image and the scale in real space, such as the imaging angle of view (imaging magnification, scan dimension), working distance, information on the ocular optical system, etc. This scale, for example, corresponds the interval between adjacent pixels (pixel pitch) to the scale in real space (e.g., pixel pitch = 10 micrometers). The blood vessel diameter calculation unit 235 can calculate the diameter of the blood vessel Db of interest in the cross section C0 of interest, i.e., the diameter of the blood vessel region V0, based on the scale set for the front fundus image and the pixels in the blood vessel region V0.

[0093] The second calculation method will be described. In the second calculation method, a cross-sectional image of the cross-section of interest C0 is typically used. This cross-sectional image may be a principal cross-sectional image or another cross-sectional image. The scale of the cross-sectional image is determined based on the measurement conditions of the OCT, etc. In some embodiments, the cross-section of interest C0 is scanned as shown in FIG. 5A or 5B. The length of the cross-section of interest C0 is determined based on various factors that determine the relationship between the scale on the image and the scale in real space, such as the scan dimension, working distance, and information about the ocular optical system. The blood vessel diameter calculation unit 235 can calculate the diameter of the blood vessel of interest Db in the cross-section of interest C0 by performing a process of calculating the pixel pitch based on the length of the cross-section of interest C0 and a process similar to that of the first calculation method.

[0094] The blood flow rate calculation unit 236 calculates the blood flow rate in the blood vessel of interest Db based on the blood flow velocity calculated by the blood flow velocity calculation unit 234 and the blood vessel diameter calculated by the blood vessel diameter calculation unit 235. An example of this process will be described below. It is assumed that the blood flow in the blood vessel is a Hagen-Poiseuille flow. Furthermore, the blood vessel diameter is represented by w, and the maximum value of the blood flow velocity is represented by Vm. In this case, the blood flow rate Q is expressed by the following equation: Q = [πw ２ Vm] / 8.

[0095] The blood flow calculation unit 236 calculates the blood flow Q by substituting the blood vessel diameter value w calculated by the blood vessel diameter calculation unit 235 and the maximum value Vm based on the blood flow velocity value calculated by the blood flow velocity calculation unit 234 into this formula.

[0096] The types of parameters calculated by the hemodynamic information generating unit 232 are not limited to the several parameters described above. For example, the hemodynamic information generating unit 232 can calculate parameters obtained by relative measurement in addition to or instead of parameters obtained by absolute measurement, such as blood flow velocity and blood flow rate. Some non-limiting examples of hemodynamic parameters that can be used in this embodiment will be described below.

[0097] Even when an inaccurate Doppler angle value is obtained, it is possible to extract and analyze a profile from an image showing the inside of a blood vessel, or to extract the shape of a pulse wave curve (a waveform derived from the heartbeat) from the time course of an image showing the inside of a blood vessel. Several studies have demonstrated the usefulness of the relative values ​​obtained in this way. It is also possible to extract specific characteristic parameters from the waveform of a pulse wave curve. The extracted characteristic parameters can be used for hemodynamic evaluation, disease assessment, etc.

[0098] The flow of blood within a blood vessel can be considered essentially laminar, with the flow velocity decreasing as the blood approaches the vessel wall due to the frictional drag from the vessel wall, and reaching its maximum at the center of the vessel. Laminar flow is a parabolic flow, and the diastolic and systolic waveforms in the cardiac cycle can be read from the pulse wave. Therefore, the characteristics of these waveforms can be determined. For example, parameters relating to deviations from a specific waveform (such as the presence, degree, and frequency of deviations) can be determined.

[0099] The blood flow velocity in veins is not always constant, but exhibits slight variations (pulsations). Parameters that indicate these minute pulsations (absolute velocity parameters, relative velocity parameters, etc.) can be calculated.

[0100] <Non-limiting aspects of the ophthalmic device> Several non-limiting aspects realized by applying the ophthalmic device 1 having the hardware aspects, software aspects, and functional aspects described above will be described. In the following description, matters related to the ophthalmic device 1 will be referenced and used as appropriate. Any matter related to the ophthalmic device 1 can be at least partially combined with each aspect. Two or more aspects can be at least partially combined.

[0101] 7 shows the configuration of an ophthalmologic apparatus 1000 according to one non-limiting embodiment. The ophthalmologic apparatus 1000 includes a fundus image acquisition unit 1010, a registration unit 1020, a frontal vascular region detection unit 1030, a three-dimensional vascular region identification unit 1040, and a direction information generation unit 1050.

[0102] The fundus image acquisition unit 1010 is configured to acquire a front fundus image and a three-dimensional fundus image of the subject's eye E.

[0103] A frontal fundus image is an image obtained by photographing the fundus Ef from a direction in front of the subject's eye E. In other words, a frontal fundus image is an image obtained by visualizing the fundus Ef from a viewpoint located in front of the subject's eye E. Examples of ophthalmic imaging modalities that can be used to acquire frontal fundus images include a fundus camera, an SLO image, a slit lamp microscope, and a surgical microscope. In addition, a frontal fundus image can be generated from a three-dimensional OCT image (e.g., stack data or volume data) acquired using an OCT device. The ophthalmic apparatus 1 of a non-limiting aspect can acquire a frontal fundus image of the fundus Ef by a frontal fundus imaging function realized using the fundus camera unit 2.

[0104] A three-dimensional fundus image is an image obtained by visualizing a three-dimensional region of the fundus oculi Ef. An example of an ophthalmic imaging modality that can be used to acquire a three-dimensional fundus image is an OCT device. The ophthalmic device 1 of a non-limiting aspect can acquire a three-dimensional fundus image of the fundus oculi Ef by a three-dimensional fundus imaging function realized using the fundus camera unit 2 and the OCT unit 100.

[0105] The non-limiting aspects of the fundus image acquisition unit 1010 described above are all realized by a fundus imaging function. However, the fundus image acquisition unit 1010 is not limited thereto. In one non-limiting aspect, the fundus image acquisition unit 1010 may be configured to externally receive at least one of a frontal fundus image and a three-dimensional fundus image. In this case, an image of the fundus Ef of the subject's eye E (a fundus image that is at least one of a frontal fundus image and a three-dimensional fundus image) is generated in advance. This fundus image is generated by the ophthalmologic device 1000 or another ophthalmologic imaging device. In some aspects, the generated fundus image is stored in a storage device (e.g., a medical image archiving system). The fundus image acquisition unit 1010 receives the fundus image, for example, from a device that generated the fundus image or a device that stores the fundus image via a communication line or a recording medium. The non-limiting aspect of the ophthalmologic apparatus 1 can acquire a frontal fundus image and / or a three-dimensional fundus image of the fundus oculi Ef from the outside by means of a fundus image reception function realized using the data input / output unit 290.

[0106] The front fundus image and the three-dimensional fundus image acquired by the fundus image acquisition unit 1010 are denoted by reference numerals 1011 and 1012, respectively. The front fundus image 1011 and the three-dimensional fundus image 1012 are provided to a registration unit 1020. The front fundus image 1011 is provided to a front vascular region detection unit 1030, and the three-dimensional fundus image 1012 is provided to a three-dimensional vascular region identification unit 1040.

[0107] The registration unit 1020 is configured to perform registration between the frontal fundus image 1011 and the three-dimensional fundus image 1012 .

[0108] Registration is an image processing technique for aligning images, and various image registration methods are known. A typical image registration involves comparing two images, determining pixel correspondences between the images, and expressing the images in a common coordinate system using the pixel correspondences. The registration method performed by the registration unit 1020 may be, for example, either an image registration method using a machine learning algorithm (machine learning model) or an image registration method using a non-machine learning algorithm, or both.

[0109] In a non-limiting example, the registration unit 1020 applies registration to a frontal fundus image 1011 defined in an xy coordinate system and a three-dimensional fundus image 1012 defined in an xyz coordinate system. First, the registration unit 1020 integrates (projects) the three-dimensional fundus image 1012 in the z direction to generate a projection image defined in the xy coordinate system. Next, the registration unit 1020 analyzes the frontal fundus image 1011 to detect landmarks, and also analyzes the projection image to detect landmarks. The landmarks may be any site present on the fundus Ef, such as tissue of the fundus Ef (optic disc, macula, blood vessels, etc.), lesions, treatment scars, etc. The registration unit 1020 detects landmarks of specific sites on the fundus Ef from both the frontal fundus image 1011 and the three-dimensional fundus image 1012, for example. Next, the registration unit 1020 calculates the deviation between the frontal fundus image 1011 and the projection image by referring to both landmarks. For example, the registration unit 1020 determines the x- and y-coordinates (x1, y1) of a landmark in the frontal fundus image 1011 that corresponds to a specific part of the fundus Ef, determines the x- and y-coordinates (x2, y2) of a landmark in the three-dimensional fundus image 1012 that corresponds to the same part, and calculates the difference in x- and y-coordinates (x1-x2, y1-y2) between these two landmarks. By using this coordinate difference, it is possible to obtain the correspondence between the x- and y-coordinates of pixels in the frontal fundus image 1011 and the x- and y-coordinates of pixels in the three-dimensional fundus image 1012, and thereby achieve registration between these images.

[0110] The registration unit 1020 is realized by cooperation between hardware including a circuit and registration software. The ophthalmologic apparatus 1 of a non-limiting aspect can perform registration between the front fundus image 1011 and the three-dimensional fundus image 1012 by the registration function realized by the data processing unit 230.

[0111] The frontal vascular region detection unit 1030 is configured to detect the frontal vascular region by analyzing the frontal fundus image 1010. The frontal vascular region is an image of blood vessels depicted in the frontal fundus image 1010.

[0112] Any image analysis method may be used to detect the frontal vascular region from the frontal fundus image 1011. For example, this image analysis may be any image segmentation method. The image segmentation method executed by the frontal vascular region detection unit 1030 may be, for example, either or both of an image segmentation method using a machine learning algorithm (machine learning model) and an image segmentation method using a non-machine learning algorithm.

[0113] The frontal vascular region detection unit 1030 is realized by cooperation between hardware including a circuit and frontal vascular region detection software. The ophthalmologic apparatus 1 of a non-limiting aspect can perform analysis processing of the frontal fundus image 1011 to detect the frontal vascular region by a frontal vascular region detection function realized by using the data processing unit 230 (e.g., the vascular region identification unit 231).

[0114] The three-dimensional vascular region identification unit 1040 is configured to identify an image region (referred to as a three-dimensional vascular region) in the three-dimensional fundus image 1012 corresponding to the frontal vascular region detected from the frontal fundus image 1011 by the frontal vascular region detection unit 1030 based on the result of the registration between the frontal fundus image 1011 and the three-dimensional fundus image 1012 performed by the registration unit 1020.

[0115] As described above, the registration unit 1020 determines the correspondence between the pixels of the front fundus image 1011 and the pixels of the three-dimensional fundus image 1012, and expresses the front fundus image 1011 and the three-dimensional fundus image 1012 in a common coordinate system. The three-dimensional vascular region specifying unit 1040 uses the registration result to specify pixels in the three-dimensional fundus image 1012 that correspond to each pixel of the front vascular region in the front fundus image 1011. This specifies the image of the blood vessels depicted in the three-dimensional fundus image 1012 (three-dimensional vascular region).

[0116] The three-dimensional vascular region specifying unit 1040 is realized by cooperation between hardware including a circuit and three-dimensional vascular region specifying software. The ophthalmologic apparatus 1 of a non-limiting aspect can perform processing for specifying a three-dimensional vascular region by a three-dimensional vascular region specifying function realized by using the data processing unit 230 (e.g., the vascular region specifying unit 231).

[0117] The orientation information generating unit 1050 is configured to generate orientation information of the three-dimensional blood vessel region in a predetermined partial region based on data of the common region between the three-dimensional blood vessel region and the predetermined partial region in the three-dimensional fundus image 1012.

[0118] A predetermined partial region in the three-dimensional fundus image 1012 is a region that satisfies predetermined conditions. This partial region may be a region to which a predetermined analysis process is applied. For example, the partial region is a region surrounding the optic disc of the fundus oculi Ef and may include one or more cylinder side surfaces. The cylinder side surface may be the side surface of any cylinder, for example, the side surface of a circular cylinder or the side surface of an elliptical cylinder. The central axis of the cylinder may be positioned at any position, for example, it may be positioned so as to pass through the center of the optic disc. Furthermore, the radius of the cylinder may be set to any value. The central axis of the elliptical cylinder may be positioned at any position, for example, it may be positioned so as to pass through the center of the optic disc. Furthermore, the major axis and minor axis of the elliptical cylinder may be set to any value.

[0119] Fig. 8A shows an example of a cylinder side surface set in a three-dimensional fundus image 1012. Reference numeral 1013 indicates the optic disc, and reference numeral 1014 indicates the central position of the optic disc 1013 (optic disc center). Reference numeral 1015 indicates a cylinder defined by a central axis 1015a passing through the disc center 1014 and a radius R1. Reference numeral 1015b indicates a side surface of the cylinder 1015 (cylinder side surface). In the example of Fig. 8A, the partial region of the three-dimensional fundus image 1012 includes the cylinder side surface 1015b.

[0120] FIG. 8B will be described with reference to FIG. 8A . Note that the optic disc 1013 and other components have been omitted to make the drawing easier to understand. FIG. 8B shows an example of two cylinder side surfaces set in a 3D fundus image 1012. The cylinder 1015, central axis 1015a, radius R1, and cylinder side surface 1015b in FIG. 8B correspond to the cylinder 1015, central axis 1015a, radius R1, and cylinder side surface 1015b in FIG. 8A , respectively. In the description of FIG. 8B , the cylinder 1015 will be referred to as the first cylinder 1015, the radius R1 will be referred to as the first radius R1, and the cylinder side surface 1015b will be referred to as the first cylinder side surface 1015b (first cylinder side surface).

[0121] The example of FIG. 8B further shows a second cylinder 1016. The second cylinder 1016 is arranged concentrically with the first cylinder 1015. That is, the central axis 1016a of the second cylinder 1016 coincides with the central axis 1015a of the first cylinder 1015. The radius (second radius) R2 of the second cylinder 1016 is larger than the radius (first radius) R1 of the first cylinder 1015. Therefore, the side surface (second cylinder side surface, second columnar body side surface) 1016b of the second cylinder 1016 is located outside the first cylinder side surface 1015b. In other words, the second cylinder side surface 1016b is arranged to surround the first cylinder side surface 1015b.

[0122] In the example of FIG. 8B , the partial region of the 3D fundus image 1012 includes a first cylinder side surface 1015b and a second cylinder side surface 1016b. In a non-limiting embodiment, the partial region of the 3D fundus image 1012 may include the first cylinder side surface 1015b, the second cylinder side surface 1016b, and a third cylinder side surface (not shown) concentrically disposed within the region between the first cylinder side surface 1015b and the second cylinder side surface 1016b. Two or more cylinder side surfaces may also be disposed within the region. In another non-limiting embodiment, the partial region of the 3D fundus image 1012 may be the entire or a portion of the annulus defined by the first cylinder side surface 1015b and the second cylinder side surface 1016b. This annulus pillar is a pillar-shaped region having the first cylindrical side surface 1015 b as an inner surface and the second cylindrical side surface 1016 b as an outer surface. In other words, this annulus pillar is a pillar-shaped region whose cross section along any plane perpendicular to the central axis 1015 a (1016 a) forms an annulus (ring) with an inner radius R1 and an outer radius R2.

[0123] FIG. 8C will be described with reference to FIGS. 8A and 8B. For clarity, the optic disc 1013 and other components are omitted. FIG. 8C shows an example of the side surfaces of two cylinders set in a three-dimensional fundus image 1012. FIG. 8C shows two concentric elliptical cylinders 1017 and 1018. The elliptical cylinder 1017 is referred to as the first elliptical cylinder 1017, and the elliptical cylinder 1018 is referred to as the second elliptical cylinder 1018. The central axis 1017a of the first elliptical cylinder 1017 and the central axis 1018a of the second elliptical cylinder 1018 coincide with each other and are arranged to pass through the optic disc center 1014 (not shown) (see FIG. 8A).

[0124] The first elliptical cylinder 1017 is defined by a central axis 1017a, a first major axis A1, and a first minor axis B1. The side surface of the first elliptical cylinder 1017 is referred to as the first elliptical cylinder side surface 1017b (first cylinder side surface). Similarly, the second elliptical cylinder 1018 is defined by a central axis 1018a, a second major axis A2, and a second minor axis B2. The side surface of the second elliptical cylinder 1018 is referred to as the second elliptical cylinder side surface 1018b (second cylinder side surface). The second major axis A2 is larger than the first major axis A1, and the second minor axis B2 is larger than the first minor axis B1. Therefore, the second elliptical cylinder side surface 1018b is located outside the first elliptical cylinder side surface 1017b. In other words, the second elliptical cylindrical side surface 1018b is disposed so as to surround the first elliptical cylindrical side surface 1017b.

[0125] In the example of Figure 8C, the partial region of the 3D fundus image 1012 includes a first elliptical cylindrical side surface 1017b and a second elliptical cylindrical side surface 1018b. In a non-limiting embodiment, the partial region of the 3D fundus image 1012 may include the first elliptical cylindrical side surface 1017b, the second elliptical cylindrical side surface 1018b, and a third elliptical cylindrical side surface (not shown) arranged concentrically within the region between the first elliptical cylindrical side surface 1017b and the second elliptical cylindrical side surface 1018b. Two or more elliptical cylindrical side surfaces may also be arranged within the region. In another non-limiting embodiment, the partial region of the 3D fundus image 1012 may be the entire or a portion of an elliptical annulus defined by the first elliptical cylindrical side surface 1017b and the second elliptical cylindrical side surface 1018b. The elliptical annulus cylinder is a cylindrical region having a first elliptical cylindrical side surface 1017 b as an inner surface and a second elliptical cylindrical side surface 1018 b as an outer surface. In other words, the elliptical annulus cylinder is a cylindrical region whose cross section along any plane perpendicular to the central axis 1017 a (1018 a) is an elliptical annulus having a first ellipse defined by a first major radius A1 and a first minor radius B1 as an inner boundary and a second ellipse defined by a second major radius A2 and a second minor radius B2 as an outer boundary.

[0126] 8C may be applied in cases where the optic disc of the subject's eye E has a specific shape. For example, when the subject's eye E is highly myopic and the optic disc is significantly tilted (called a tilted optic disc), the orientation information generating unit 1050 calculates an ellipticity ε = (minor radius) / (major radius) according to the state of optic disc tilt (the direction and angle of tilt, etc.) so that the partial region of the 3D fundus image 1012 substantially has a cylindrical side shape in the actual fundus Ef, and determines a combination of the major radius A1 and the minor radius B1 and a combination of the major radius A2 and the minor radius B2 so as to achieve the ellipticity ε, thereby setting the first elliptical cylindrical side surface 1017b and the second elliptical cylindrical side surface 1018b.

[0127] The above describes several aspects of the partial region of the three-dimensional fundus image 1012. These are non-limiting examples, and other aspects of the partial region may also be adopted.

[0128] Furthermore, the orientation information generating unit 1050 obtains a common area between the partial area in the three-dimensional fundus image 1012 and the three-dimensional vascular area identified from the three-dimensional fundus image 1012 by the three-dimensional vascular area identifying unit 1040. In other words, the orientation information generating unit 1050 identifies pixels that belong to both the partial area and the three-dimensional vascular area, which are two areas in the three-dimensional fundus image 1012. As a result, the vascular area in the partial area is identified as the common area.

[0129] Furthermore, the orientation information generating unit 1050 generates orientation information of the three-dimensional vascular region in the partial region of the three-dimensional fundus image 1012 based on data of the vascular region in the partial region of the three-dimensional fundus image 1012 (i.e., a group of pixels constituting the common region of the three-dimensional fundus image 1012). The orientation information may be any type of information regarding the orientation of the fundus blood vessels. Some non-limiting examples of orientation information are described below.

[0130] In some aspects, the orientation information may include information indicating the Doppler angle of hemodynamic measurement (Doppler angle information). The orientation information generating unit 1050 can generate Doppler angle information indicating the magnitude of the Doppler angle for blood vessels in the fundus Ef that may be targets or candidates for hemodynamic measurement, based on data from the common region of the three-dimensional fundus image 1012. In other words, the orientation information generating unit 1050 can generate Doppler angle information indicating the magnitude of the Doppler angle in OCT blood flow measurement for blood vessels in the fundus Ef that correspond to the three-dimensional vascular region in the three-dimensional fundus image 1012 (the partial image), based on data from the common region of the three-dimensional fundus image 1012. Any processing method may be used to calculate the Doppler angle. For example, the method may be the same as any processing method that can be executed by the Doppler angle calculating unit 233 of the ophthalmologic apparatus 1.

[0131] In some embodiments, the orientation information may include information (evaluation information) obtained by evaluating the Doppler angle of hemodynamic measurement. The orientation information generating unit 1050 obtains the magnitude of the Doppler angle (Doppler angle information) using the above-described method. Furthermore, the orientation information generating unit 1050 applies a predetermined evaluation process to the magnitude of the Doppler angle. This evaluation process evaluates, for example, the suitability of the magnitude of the Doppler angle in OCT blood flow measurement.

[0132] In some embodiments, the preferred value for the Doppler angle in OCT blood flow measurement is approximately 80 degrees, and in actual measurements, the search for the blood vessel and cross section of interest is performed with a target range of 77 degrees to 83 degrees. While measurements can be performed with a Doppler angle of approximately 75 degrees, a problem arises in that phase wrapping is more likely to occur, so it is considered desirable to set the lower limit of the target range to approximately 77 degrees. Furthermore, a Doppler angle of approximately 85 degrees presents a problem in that the strength of the detected Doppler signal decreases, so it is considered desirable to set the upper limit of the target range to approximately 83 degrees. Note that this target range is a non-limiting example, and other target ranges may be used.

[0133] In the evaluation process, the orientation information generating unit 1050 can compare the magnitude of the Doppler angle of the target three-dimensional vascular region with a target range. If the magnitude of the Doppler angle falls within the target range, the orientation information generating unit 1050 generates evaluation information indicating that the magnitude of the Doppler angle is suitable. If the magnitude of the Doppler angle does not fall within the target range, the orientation information generating unit 1050 generates evaluation information indicating that the magnitude of the Doppler angle is not suitable.

[0134] By dividing the target range into multiple sections, it is possible to perform a more detailed evaluation when the magnitude of the Doppler angle is favorable, and by dividing the range outside the target range into multiple sections, it is possible to perform a more detailed evaluation when the magnitude of the Doppler angle is unfavorable.

[0135] The orientation information generating unit 1050 can obtain orientation distribution information indicating the distribution of orientations of blood vessel regions in the three-dimensional fundus image 1012. The orientation distribution information is information indicating the distribution of blood vessel regions in the partial region of the three-dimensional fundus image 1012, and includes position information and orientation information of the blood vessel regions.

[0136] In an aspect in which orientation distribution information is generated, the frontal vascular region detection unit 1030 detects multiple frontal vascular regions by analyzing the frontal fundus image 1011. The frontal vascular region detection unit 1030 detects multiple vascular images (multiple frontal vascular regions) from the frontal fundus image 1011 in which a large number of vascular images are depicted. Examples of the detected frontal vascular region include, but are not limited to, a vascular image having a width (vascular diameter) equal to or greater than a predetermined value, a vascular image depicted with a contrast equal to or greater than a predetermined value, a vascular image depicted with a brightness equal to or greater than a predetermined value, and a vascular image located within a predetermined range (for example, around the optic disc).

[0137] Next, the three-dimensional vascular region specifying unit 1040 specifies an image region (three-dimensional vascular region) in the three-dimensional fundus image 1012 corresponding to each frontal vascular region detected by the frontal vascular region detecting unit 1030. As a result, a plurality of three-dimensional vascular regions corresponding to the plurality of frontal vascular regions detected by the frontal vascular region detecting unit 1030 are specified.

[0138] Next, the orientation information generating unit 1050 obtains position information and orientation information of each three-dimensional vascular region in the partial region based on data of the common region between each three-dimensional vascular region identified from the three-dimensional fundus image 1012 by the three-dimensional vascular region identifying unit 1040 and the partial region in the three-dimensional fundus image 1012. This allows the orientation information generating unit 1050 to generate orientation distribution information of the multiple three-dimensional vascular regions in the partial region based on data of the common region between the partial region and the multiple three-dimensional vascular regions in the three-dimensional fundus image 1012.

[0139] A non-limiting example of a processing method for generating orientation distribution information will be described. In this example, the example shown in FIG. 8B is used as the partial region of the three-dimensional fundus image 1012. A similar processing method can be used when a different partial region is used.

[0140] The orientation information generating unit 1050 in this example first identifies a common area between each three-dimensional vascular region identified from the three-dimensional fundus image 1012 by the three-dimensional vascular region identifying unit 1040 and the first cylinder side surface 1015b (first cylinder side surface) shown in FIG. 8B . This common area corresponds to a cross section of the three-dimensional vascular region on the first cylinder side surface 1015b (referred to as a first vascular cross section). The orientation information generating unit 1050 generates position information (first position information) indicating the position of the first vascular cross section. The first position information may be any type of information indicating the position of the first vascular cross section, and may indicate, for example, a predetermined position on the first vascular cross section (e.g., a center position, a center of gravity position, an upper end position, a lower end position, etc.). When the Doppler angle is taken into consideration in subsequent processing, the first position information includes at least information indicating a position in a direction along the central axis 1015a (typically, position information (z coordinate) in the depth direction of the fundus Ef).

[0141] The orientation information generator 1050 also identifies a common area with the second cylinder side surface 1016b (second cylinder side surface) shown in FIG. 8B. This common area corresponds to a cross section of the three-dimensional vascular region on the second cylinder side surface 1016b (referred to as a second vascular cross section). The orientation information generator 1050 generates position information (second position information) indicating the position of the second vascular cross section. The second position information is the same type of information as the first position information described above.

[0142] Furthermore, for each three-dimensional vascular region identified from the three-dimensional fundus image 1012 by the three-dimensional vascular region identifying unit 1040, the orientation information generating unit 1050 generates orientation information indicating the orientation of the three-dimensional vascular region based on first position information indicating the cross-sectional position of the three-dimensional vascular region on the first cylinder side surface 1015b and second position information indicating the cross-sectional position of the three-dimensional vascular region on the second cylinder side surface 1016b. By applying such processing to each of the multiple three-dimensional vascular regions identified from the three-dimensional fundus image 1012 by the three-dimensional vascular region identifying unit 1040, the orientation information generating unit 1050 generates orientation distribution information indicating the distribution of orientation information of these multiple three-dimensional vascular regions.

[0143] The orientation information generating unit 1050 is realized by cooperation between hardware including a circuit and orientation information generating software. The ophthalmologic apparatus 1 of a non-limiting aspect can perform processing for generating orientation information by an orientation information generating function realized by the data processing unit 230.

[0144] Several operation examples of the ophthalmologic apparatus 1000 will be described. The processing contents of the steps in each operation example are not limited and may be modified as desired. Furthermore, the order of the steps in each operation example is not limited and may be modified as desired.

[0145] 9 shows an example of an operation of the ophthalmologic apparatus 1000. First, in step S1, the fundus image acquisition unit 1010 acquires a front fundus image 1110 and a three-dimensional fundus image 1120 of the fundus Ef of the subject's eye E (see FIGS. 10A and 10B).

[0146] In step S2, the registration unit 1020 performs registration between the frontal fundus image 1110 and the three-dimensional fundus image 1120. As a result, a correspondence relationship between the coordinates (x and y coordinates) of pixels in the frontal fundus image 1110 and the coordinates (x and y coordinates) of pixels in the three-dimensional fundus image 1120 is obtained.

[0147] In step S3, the frontal vascular region detection unit 1030 detects the frontal vascular region by analyzing the frontal fundus image 1110. In the example of Fig. 10A, four frontal vascular regions 1112a, 1112b, 1112c, and 1112d are detected. Note that reference numeral 1111 denotes the optic disc, and reference numeral 1111a denotes the center of the optic disc.

[0148] In step S4, the three-dimensional vascular region identifying unit 1040 identifies a three-dimensional vascular region in the three-dimensional fundus image 1120 that corresponds to the frontal vascular region detected from the frontal fundus image 1110, based on the correspondence between pixel positions between the frontal fundus image 1110 and the three-dimensional fundus image 1120 obtained in the image registration in step S2. In the example of Figures 10A and 10B, four three-dimensional vascular regions 1122a, 1122b, 1122c, and 1122d are identified in the three-dimensional fundus image 1120, corresponding to the four frontal vascular regions 1112a, 1112b, 1112c, and 1112d in the frontal fundus image 1110, respectively. Note that reference numeral 1121 denotes the optic disc, and reference numeral 1121a denotes the center of the optic disc.

[0149] In step S5, the orientation information generating unit 1050 generates orientation information of the three-dimensional vascular region based on data of the common region between the partial region in the three-dimensional fundus image 1120 and the three-dimensional vascular region identified in step S4. A non-limiting example of the processing performed in this step is described below.

[0150] First, the orientation information generating unit 1050 sets a first cylinder side surface 1123 and a second cylinder side surface 1124 shown in Fig. 10B as partial regions in the three-dimensional fundus image 1120. The first cylinder side surface 1123 and the second cylinder side surface 1124 have a common central axis passing through the optic disc center 1121a and are arranged concentrically.

[0151] Next, the orientation information generator 1050 identifies a common area between the first cylinder side surface 1123 and the four three-dimensional vascular regions 1122a, 1122b, 1122c, and 1122d identified in step S4. This common area is a cross section of the four three-dimensional vascular regions 1122a, 1122b, 1122c, and 1122d on the first cylinder side surface 1123, and corresponds to the four vascular cross sections 1123a, 1123b, 1123c, and 1123d shown in Figure 10C. Here, the four vascular cross sections 1123a, 1123b, 1123c, and 1123d correspond to the four three-dimensional vascular regions 1122a, 1122b, 1122c, and 1122d, respectively.

[0152] Furthermore, the orientation information generator 1050 identifies a common area between the second cylinder side surface 1124 and the four three-dimensional vascular regions 1122a, 1122b, 1122c, and 1122d. This common area is a cross section of the four three-dimensional vascular regions 1122a, 1122b, 1122c, and 1122d on the second cylinder side surface 1124, and corresponds to the four vascular cross sections 1124a, 1124b, 1124c, and 1124d shown in Figure 10C. Here, the four vascular cross sections 1124a, 1124b, 1124c, and 1124d correspond to the four three-dimensional vascular regions 1122a, 1122b, 1122c, and 1122d, respectively.

[0153] Next, the orientation information generator 1050 determines the orientation of each of the four three-dimensional vascular regions 1122a, 1122b, 1122c, and 1122d. The determined orientations include at least the orientation (tilt) in the z direction corresponding to the Doppler angle. Alternatively, the orientations may be expressed in an xy coordinate system.

[0154] To determine the orientation in the z direction, the orientation information generator 1050 determines the z coordinates of each of the four vascular cross sections 1123a, 1123b, 1123c, and 1123d on the first cylindrical side surface 1123. For example, the orientation information generator 1050 determines a figure (e.g., an approximate circle or an approximate ellipse) that approximates the outer edge shape of the vascular cross section 1123a, and determines the z coordinate za1 of the center of this approximate figure. This z coordinate za1 is used as the z coordinate of the vascular cross section 1123a. By similar processing, the z coordinate zb1 of the vascular cross section 1123b, the z coordinate zc1 of the vascular cross section 1123c, and the z coordinate zd1 of the vascular cross section 1123d are determined.

[0155] Furthermore, by similar processing, the orientation information generating unit 1050 obtains the z coordinates of the four blood vessel cross sections 1124a, 1124b, 1124c, and 1124d on the second cylinder side surface 1124. This obtains the z coordinate za2 of the blood vessel cross section 1124a, the z coordinate zb2 of the blood vessel cross section 1124b, the z coordinate zc2 of the blood vessel cross section 1124c, and the z coordinate zd2 of the blood vessel cross section 1124d.

[0156] Furthermore, the orientation information generating unit 1050 calculates the difference in z coordinates between corresponding vascular cross sections between the first cylinder side surface 1123 and the second cylinder side surface 1124. That is, the orientation information generating unit 1050 calculates the difference Δza = za1 - za2 (or Δza = za2 - za1) between the z coordinate za1 of the vascular cross section 1123a on the first cylinder side surface 1123 and the z coordinate za2 of the vascular cross section 1124a on the second cylinder side surface 1124. Furthermore, the orientation information generating unit 1050 calculates the gradient Aa of the three-dimensional vascular region 1122a in the z direction by dividing this difference Δza by the distance between the first cylinder side surface 1123 and the second cylinder side surface 1124 (that is, the absolute value of the difference between the radius of the first cylinder side surface 1123 and the radius of the second cylinder side surface 1124). By similar calculations, the gradient Ab of the three-dimensional vascular region 1122b, the gradient Ac of the three-dimensional vascular region 1122c, and the gradient Ad of the three-dimensional vascular region 1122d are also calculated.

[0157] The orientation information generating unit 1050 generates orientation information based on the gradients Aa, Ab, Ac, and Ad obtained as described above. This orientation information may include Doppler angle information indicating the magnitude of the Doppler angle, or may be evaluation information related to the magnitude of the Doppler angle. Furthermore, the orientation information generating unit 1050 may generate orientation distribution information based on the gradients Aa, Ab, Ac, and Ad.

[0158] The ophthalmologic apparatus 1000 capable of executing the processing procedure according to this operational example provides a novel technique for acquiring information on the course of blood vessels from an image obtained by fundus imaging and generating orientation information of fundus blood vessels. The orientation information generated in this operational example contributes to simplification and labor savings in the task of specifying a blood flow measurement position, and contributes to improving the precision and accuracy of the task. Furthermore, the orientation information generated in this operational example provides the magnitude of the Doppler angle and its evaluation results, making it possible to predict a suitable blood flow measurement position.

[0159] 11 shows the configuration of an ophthalmic apparatus 1200 according to one non-limiting embodiment. Elements of the ophthalmic apparatus 1200 that have the same names and symbols as elements of the ophthalmic apparatus 1000 in FIG. 7 may have the same configurations and functions as the corresponding elements of the ophthalmic apparatus 1000, unless otherwise specified. However, this does not exclude the adoption of modified, equivalent, or alternative means for the corresponding elements.

[0160] The ophthalmic apparatus 1200 includes the same elements as the ophthalmic apparatus 1000, such as a fundus image acquisition unit 1010, a registration unit 1020, a frontal vascular region detection unit 1030, a three-dimensional vascular region identification unit 1040, and an orientation information generation unit 1050. In addition to these elements, the ophthalmic apparatus 1200 also includes a display control unit 1060 and a display device 1065.

[0161] The display device 1065 is any type of display. The display device 1065 may be the display unit 241 of the ophthalmic apparatus 1, for example, the display device 3. The display device 1065 of this embodiment is a component of the ophthalmic apparatus 1200. In another embodiment, the display device may be a peripheral device (external device) of the ophthalmic apparatus.

[0162] The display control unit 1060 is configured to control the display device 1065 to display information. The display control unit 1060 causes the display device 1065 to display information (e.g., images, orientation information, etc.) generated by the ophthalmic apparatus 1200. The display device 1065 causes the display device 1065 to display information (e.g., images) acquired by the ophthalmic apparatus 1200 from an external source.

[0163] The display control unit 1060 can display the front fundus image 1011 acquired by the fundus image acquisition unit 1010 and the orientation information generated by the orientation information generation unit 1050 on the display device 1065. The display control unit 1060 can display the front fundus image 1011 on the display device 1065, and can also display an orientation distribution image based on orientation distribution information indicating the orientations of multiple blood vessels in the fundus Ef on the front fundus image 1011. The orientation distribution image is generated by visualizing the position information and orientation information of each of the multiple blood vessels. The position information of the blood vessels in the orientation distribution image may be represented using an image indicating their positions in the front fundus image 1011. The orientation information of the blood vessels may be represented using, for example, a numerical value indicating the Doppler angle, a numerical value indicating the suitability of the Doppler angle in OCT blood flow measurement, or an image indicating the suitability.

[0164] The display control unit 1060 may cause the display device 1065 to display an image based on the three-dimensional fundus image 1012 acquired by the fundus image acquisition unit 1010. The display control unit 1060 can cause the display device 1065 to display a rendering image of the three-dimensional fundus image 1012. For example, the display control unit 1060 can cause the display device 1065 to display a frontal fundus image generated by rendering the three-dimensional fundus image 1012, and can also display an orientation distribution image on this frontal fundus image.

[0165] The display control unit 1060 is realized by cooperation between hardware including circuits and display control software. The ophthalmologic apparatus 1 of a non-limiting aspect can realize the functions of the display control unit 1060 using the control unit 240 (main control unit 211).

[0166] The ophthalmic device 1200 according to this aspect can provide an image of the fundus Ef and blood vessel direction information as visual information, in addition to the actions and effects of the ophthalmic device 1000. For example, the ophthalmic device 1200 can provide the distribution state of blood vessels in the fundus Ef in a visually recognizable manner by displaying position information and direction information of a plurality of blood vessels in the fundus Ef together with a front image of the fundus Ef. This can facilitate and reduce the labor required for specifying the blood flow measurement position, and can also improve the precision and accuracy of the operation.

[0167] 12 shows the configuration of an ophthalmic apparatus 1300 according to one non-limiting embodiment. Elements of the ophthalmic apparatus 1300 that have the same names and symbols as elements of the ophthalmic apparatus 1000 in FIG. 7 may have the same configurations and functions as the corresponding elements of the ophthalmic apparatus 1000, unless otherwise specified. However, this does not exclude the adoption of modified, equivalent, or alternative means for the corresponding elements.

[0168] The ophthalmic apparatus 1300 includes similar elements to the ophthalmic apparatus 1000, such as a fundus image acquisition unit 1010, a registration unit 1020, a frontal vascular region detection unit 1030, a three-dimensional vascular region identification unit 1040, and an orientation information generation unit 1050. However, the fundus image acquisition unit 1010 of this embodiment includes a scan unit 1010a and a scan control unit 1010b. The ophthalmic apparatus 1300 also includes a vascular region of interest designation unit 1070 and a data processing unit 1080.

[0169] The scanning unit 1010a is configured to perform an OCT scan. The ophthalmologic apparatus 1 of a non-limiting aspect can realize the function of the scanning unit 1010a using the fundus camera unit 2 and the OCT unit 100.

[0170] The scan control unit 1010b is configured to control the scan unit 1010a. The scan control unit 1010b is realized by cooperation between hardware including circuits and scan control software. The ophthalmologic apparatus 1 of a non-limiting aspect can realize the function of the scan control unit 1010b using the control unit 240 (main control unit 211).

[0171] The vascular region of interest designation unit 1070 is configured to designate one or more three-dimensional vascular regions from among the multiple three-dimensional vascular regions identified by the three-dimensional vascular region designation unit 1040. The designated blood vessel is referred to as a vascular region of interest. The vascular region of interest is an image of the blood vessel of interest that is the target of hemodynamic measurement. In other words, the vascular region of interest designation unit 1070 is configured to designate a blood vessel to be treated as the blood vessel of interest Db shown in Figures 5A and 5B from among the multiple three-dimensional vascular regions identified from the three-dimensional fundus image 1012.

[0172] In a non-limiting example, the vascular region of interest designation unit 1070 may be configured to execute a process of selecting a vascular region of interest from a plurality of projection images. That is, the vascular region of interest designation unit 1070 of this example automatically selects and designates a vascular region of interest. The index (selection criterion) referenced as a criterion for selecting a vascular region of interest may be determined arbitrarily.

[0173] The selection criteria include at least orientation information (e.g., Doppler angle information, evaluation information). As described above, the preferred range of the Doppler angle in OCT blood flow measurement is typically 77 degrees to 83 degrees. The vascular region of interest designation unit 1070 can select a three-dimensional vascular region whose Doppler angle falls within this range. When two or more such three-dimensional vascular regions are selected, the vascular region of interest designation unit 1070 may be configured to select the three-dimensional vascular region whose Doppler angle is closest to the optimal value (typically 80 degrees).

[0174] In addition to the orientation information, the selection criteria may include other indices. Examples of other indices include the type of blood vessel (e.g., artery, vein), size (blood vessel diameter), tortuosity, position (e.g., position relative to the optic disc), etc. The blood vessel region of interest designation unit 1070 can select a blood vessel region of interest by considering two or more types of indices in stages or in parallel.

[0175] In another non-limiting example, the vascular region of interest designation unit 1070 may be configured to designate a 3D vascular region selected by a user from among a plurality of 3D vascular regions as the vascular region of interest. In this example, the ophthalmic device 1300 displays an orientation distribution image as in the ophthalmic device 1200 of FIG. 11 . The user can select the vascular region of interest by referring to the displayed orientation distribution image. The input operation of the selected vascular region of interest is performed using a user interface (e.g., the user interface 240 of the ophthalmic device 1) not shown.

[0176] The data processing unit 1080 is configured to process data collected from the fundus oculi Ef by the scanning unit 1010a. The data processing unit 1080 is realized by the cooperation of hardware including circuits and data processing software.

[0177] The data processing unit 1080 may have a configuration similar to that of the data processing unit 230 of the ophthalmologic apparatus 1. Specifically, the data processing unit 1080 may include the image generation unit 220, vascular region identification unit 231, and hemodynamic information generation unit 232 shown in FIG. 4. In this example, the scan control unit 1010b controls the scanning unit 1010a to apply repeated scans for hemodynamic measurement to a cross section of the fundus Ef corresponding to a cross section of a vascular region of interest located near a partial region in the 3D fundus image 1012. Here, the "nearby" of a partial region may be a position within the partial region or a position outside the partial region. The cross section of the fundus Ef corresponding to this vicinity corresponds, for example, to the cross section of interest C0 shown in FIGS. 5A and 5B. The data collected by the scanning unit 1010a through this repeated scan is referred to as OCT blood flow measurement data 1075. The data processing unit 1080 generates hemodynamic information 1085 in the blood vessels (vessels of interest) of the fundus Ef corresponding to the vascular region of interest designated by the vascular region of interest designation unit 1070 based on the OCT blood flow measurement data 1075 .

[0178] A non-limiting example of the operation of the ophthalmic apparatus 1300 will be described. Fig. 13 shows one example of the operation of the ophthalmic apparatus 1300. First, in step S11, the fundus image acquisition unit 1010 applies frontal fundus photography to the fundus Ef and also applies 3D OCT scanning to a region of the fundus Ef including the optic disc (peripapillary 3D OCT scanning). The frontal fundus photography is performed using the fundus camera unit 2 described above. The peripapillary 3D OCT scanning is performed by the scanning unit 1010a under the control of the scan control unit 1010b. The frontal fundus photography generates a frontal fundus image 1011, and the peripapillary 3D OCT scanning generates a 3D fundus image 1012.

[0179] In step S12, the frontal vascular region detection unit 1030 detects a plurality of frontal vascular regions from the frontal fundus image 1011. Information on the detected plurality of frontal vascular regions is input to the registration unit 1020.

[0180] In step S13, the registration unit 1020 generates a projection image by integrating (projecting) the three-dimensional fundus image 1012 in the z direction. Furthermore, the registration unit 1020 performs registration between the projection image of the three-dimensional fundus image 1012 and the multiple frontal vascular regions detected in step S12.

[0181] In some of the above-described embodiments, registration is performed between the frontal fundus image 1011 and the three-dimensional fundus image 1012 (its projection image). In contrast, in this operation example, registration is performed between the frontal blood vessel region detected from the frontal fundus image 1011 and the three-dimensional fundus image 1012 (its projection image). The only difference between the two processing procedures is the order of the steps, and both processing procedures can be considered to be substantially the same.

[0182] In step S14, the three-dimensional vascular region identifying unit 1040 sets multiple circle scan sections around the image of the optic disc of the fundus oculi Ef. The multiple circle scan sections in this example are two sections corresponding to two concentric circle scans, corresponding to the first cylindrical side surface 1015b and the second cylindrical side surface 1016b in FIG. 8B described above. Reference numerals 1321 and 1322 in FIG. 14A indicate the two circle scans of the multiple circle scan sections set in the three-dimensional fundus image 1012. Reference numeral 1310 indicates a projection image of the three-dimensional fundus image 1012. Note that, because registration is performed between the three-dimensional fundus image 1012 and the frontal fundus image 1011 (frontal vascular region), the image indicated by reference numeral 1310 can also be considered the frontal fundus image 1011.

[0183] Furthermore, the three-dimensional vascular region specifying unit 1040 specifies multiple vascular regions (multiple three-dimensional vascular regions) passing through the multiple circle scan sections 1321 and 1322, and assigns an identifier to each of the specified vascular regions. In Fig. 14B, circled numbers 1 to 10 indicate ten identifiers assigned to the ten specified vascular regions, respectively.

[0184] In step S15, the orientation information generating unit 1050 extracts data (cross-sectional images) of the circle scan section 1321 and data (cross-sectional images) of the circle scan section 1322 from the 3D fundus image 1012. The two extracted cross-sectional images are similar to the pair of cross-sectional images representing the first cylinder side surface 1123 and the second cylinder side surface 1124 shown in FIG. 10C described above.

[0185] In step S16, the orientation information generating unit 1050 analyzes the cross-sectional image of the circle scan cross section 1321 to identify the cross section (vascular cross section) of each vascular region to which an identifier has been assigned, and identifies the center position of each identified vascular cross section. Similarly, the orientation information generating unit 1050 analyzes the cross-sectional image of the circle scan cross section 1322 to identify the cross section (vascular cross section) of each vascular region to which an identifier has been assigned, and identifies the center position of each identified vascular cross section. As a result, the vascular cross section center in the circle scan cross section 1321 and the vascular cross section center in the circle scan cross section 1322 are obtained for each vascular region to which an identifier has been assigned.

[0186] In step S17, the orientation information generating unit 1050 calculates the magnitude of the Doppler angle (Doppler angle) for each vascular region to which an identifier has been assigned, based on the vascular cross-sectional center on the circle scan section 1321 and the vascular cross-sectional center on the circle scan section 1322. This calculation is similar to the method shown in Fig. 6A described above. In Fig. 14C, the numbers enclosed in squares indicate the Doppler angles of the corresponding vascular regions.

[0187] In step S18, the vascular region of interest designation unit 1070 designates a blood vessel of interest. In one example, the ophthalmologic apparatus 1300 displays the information shown in FIG. 14C . The user selects a desired blood vessel region by referring to the displayed information. The vascular region of interest designation unit 1070 designates a blood vessel corresponding to the selected blood vessel region as a blood vessel of interest. In another example, the vascular region of interest designation unit 1070 designates a blood vessel of interest based on the Doppler angle (and another selection criterion) of each blood vessel region obtained in step S17.

[0188] In step S19, the scan control unit 1010b controls the scan unit 1010a to apply repeated scans for hemodynamic measurement to the blood vessel of interest designated in step S18, thereby collecting OCT blood flow measurement data 1075.

[0189] In step S20, the data processing unit 1080 generates hemodynamic information 1085 based on the OCT blood flow measurement data 1075 acquired in step S19.

[0190] In addition to the functions and effects of the ophthalmic apparatus 1000, the ophthalmic apparatus 1300 according to this embodiment can automatically designate a blood vessel of interest based on blood vessel orientation information, or can assist in the task of designating a blood vessel of interest based on blood vessel orientation information. Furthermore, the ophthalmic apparatus 1300 can automatically perform hemodynamic measurement of a designated blood vessel of interest using blood vessel orientation information. This facilitates and reduces the labor required to designate a position where hemodynamic measurement is to be applied, thereby improving the accuracy and precision of the task. Furthermore, automation of hemodynamic measurement can facilitate, reduce labor, and speed up examinations.

[0191] Other Embodiments It will be understood by those skilled in the art that the present disclosure also provides embodiments in categories other than ophthalmic devices. For example, the present disclosure may provide an embodiment of a method for controlling an ophthalmic device, an embodiment of a method for controlling an ophthalmic information processing device, an embodiment of a program for causing a computer to execute each step of any of the methods, and an embodiment of a computer-readable non-transitory recording medium on which any of the programs is recorded. The recording medium may take any form. For example, the recording medium may be any of a magnetic disk, an optical disk, a magneto-optical disk, and a semiconductor memory.

[0192] Some embodiments are a method for controlling an ophthalmic device having a processor. The method causes the processor of the ophthalmic device to perform a fundus image acquisition process, a registration process, a frontal vascular region detection process, a three-dimensional vascular region identification process, and an orientation information generation process. The fundus image acquisition process acquires a frontal fundus image and a three-dimensional fundus image of the subject's eye. The registration process aligns the frontal fundus image and the three-dimensional fundus image. The frontal vascular image detection process analyzes the frontal fundus image to detect the frontal vascular region. The three-dimensional vascular region identification process identifies a three-dimensional vascular region in the three-dimensional fundus image corresponding to the frontal vascular region in the frontal fundus image based on the registration result. The orientation information generation process generates orientation information of the three-dimensional vascular region based on data of an intersection between a predetermined partial region in the three-dimensional fundus image and the three-dimensional vascular region. This method enables the ophthalmic device to perform the procedures shown in FIG. 9 .

[0193] It is possible to create a program that causes an ophthalmic device including a computer to execute this method. It is also possible to create a computer-readable non-transitory recording medium that records such a program. This non-transitory recording medium may be in any form, such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory.

[0194] Any of the items described in this disclosure may be combined with the methods, programs, and recording media described herein.

[0195] Although several embodiments according to the present disclosure have been described above with reference to the drawings, these are non-limiting examples, and various configurations other than those described above may also be adopted.

[0196] In addition, in the flowcharts used in the above description, multiple steps (processes) are described in order. However, the order of the steps performed in each embodiment is not limited to the order described. In each embodiment, the order of the steps shown in the drawings can be changed to the extent that the content is not affected. Furthermore, the above embodiments can be at least partially combined to the extent that the content is not contradictory.

[0197] Some or all of the above embodiments can be described as follows: However, the embodiments according to the present disclosure are not limited to the following supplementary notes.

[0198] [1] An ophthalmologic device comprising: a fundus image acquisition unit that acquires a frontal fundus image and a three-dimensional fundus image of a subject's eye; a registration unit that performs registration between the frontal fundus image and the three-dimensional fundus image; a frontal vascular region detection unit that analyzes the frontal fundus image to detect a frontal vascular region; a three-dimensional vascular region identification unit that identifies a three-dimensional vascular region in the three-dimensional fundus image that corresponds to the frontal vascular region in the frontal fundus image based on the result of the registration; and an orientation information generation unit that generates orientation information of the three-dimensional vascular region based on data on a common region between a predetermined partial region in the three-dimensional fundus image and the three-dimensional vascular region.

[0199] [2] The ophthalmologic device of claim 1, wherein the orientation information generating unit generates Doppler angle information indicating the magnitude of the Doppler angle in optical coherence tomography blood flow measurement for the blood vessels of the fundus corresponding to the three-dimensional vascular region based on the data of the common region, and the orientation information includes the Doppler angle information.

[0200] [3] The ophthalmologic device of claim 1, wherein the orientation information generating unit determines the magnitude of the Doppler angle in optical coherence tomography blood flow measurement for the blood vessels of the fundus corresponding to the three-dimensional vascular region based on the data of the common region, and generates evaluation information by applying an evaluation process to the magnitude of the Doppler angle, and the orientation information includes the evaluation information.

[0201] [4] The ophthalmologic device according to claim 2 or 3, wherein the front vascular region detection unit detects a plurality of front vascular regions, the three-dimensional vascular region identification unit identifies a plurality of three-dimensional vascular regions respectively corresponding to the plurality of front vascular regions, and the orientation information generation unit generates orientation distribution information indicating a distribution of orientation information of the plurality of three-dimensional vascular regions based on data of a common region between the partial region and the plurality of three-dimensional vascular regions.

[0202] [5] The ophthalmologic apparatus according to the above item 4, wherein the partial region is a region surrounding the optic disc of the subject's eye and includes a first cylinder side surface and a second cylinder side surface.

[0203] [6] The ophthalmologic device of above 5, wherein the orientation information generating unit analyzes at least one of the frontal fundus image and the three-dimensional fundus image to identify the center position of the optic disc, sets the side of a first cylinder having a central axis passing through the center position and a first radius as the side of the first cylinder, and sets the side of a second cylinder having the central axis and a second radius larger than the first radius as the side of the second cylinder.

[0204] [7] The ophthalmologic device of above 5, wherein the orientation information generating unit analyzes at least one of the frontal fundus image and the three-dimensional fundus image to identify the center position of the optic disc and generate morphological information; determines a first dimension that is the dimension of the side surface of the first cylinder and a second dimension that is the dimension of the side surface of the second cylinder and is larger than the first dimension based on the morphological information; sets the side surface of a first elliptical cylinder having a central axis passing through the center position and a first major radius and a first minor radius based on the first dimension as the side surface of the first cylinder; and sets the side surface of a second elliptical cylinder having the central axis and a second major radius and a second minor radius based on the second dimension as the side surface of the second cylinder.

[0205] [8] The ophthalmologic device of any one of 4 to 7 above, wherein the orientation information generating unit generates first position information indicating the position of an intersection area between the plurality of three-dimensional vascular regions and the first cylinder side surface, generates second position information indicating the position of an intersection area between the plurality of three-dimensional vascular regions and the second cylinder side surface, and generates the orientation distribution information based on the first position information and the second position information.

[0206] [9] The ophthalmologic apparatus according to any one of the above items 4 to 8, further comprising a display control unit that displays the frontal fundus image on a display device and displays an orientation distribution image based on the orientation distribution information on the frontal fundus image.

[0207]

[10] The ophthalmologic device of any of claims 4 to 9, wherein the fundus image acquisition unit includes a scanning unit that applies an optical coherence tomography scan to the fundus, and a scan control unit that controls the scanning unit, and further includes a data processing unit that processes data collected from the fundus by the optical coherence tomography scan, and a vascular region of interest designation unit that designates a vascular region of interest from among the plurality of three-dimensional vascular regions, wherein the scan control unit controls the scanning unit to apply repeated scans to a cross section of the fundus corresponding to a cross section of the vascular region of interest located near the partial region, and the data processing unit generates hemodynamic information in the blood vessel of interest corresponding to the vascular region of interest based on the data collected by the repeated scans.

[0208]

[11] A method for controlling an ophthalmologic device having a processor, the method causing the processor to perform the following: a fundus image acquisition process for acquiring a frontal fundus image and a three-dimensional fundus image of a subject's eye; registration between the frontal fundus image and the three-dimensional fundus image; a frontal vascular region detection process for analyzing the frontal fundus image to detect a frontal vascular region; a three-dimensional vascular region identification process for identifying a three-dimensional vascular region in the three-dimensional fundus image corresponding to the frontal vascular region in the frontal fundus image based on the result of the registration; and an orientation information generation process for generating orientation information of the three-dimensional vascular region based on data of a common region between a predetermined partial region in the three-dimensional fundus image and the three-dimensional vascular region.

[0209]

[12] A program for causing a computer to execute the method of 11 above.

[0210]

[13] A computer-readable non-transitory recording medium on which the program of 12 above is recorded.

[0211] The present disclosure is merely an example of how to implement the present invention, and those who intend to implement the present invention can make any modifications (omissions, substitutions, additions, etc.) within the scope of the gist of the present invention.

[0212] 1000 Ophthalmic apparatus 1010 Fundus image acquisition unit 1020 Registration unit 1030 Frontal blood vessel region detection unit 1040 Three-dimensional blood vessel region identification unit 1050 Orientation information generation unit

Claims

1. An ophthalmologic device comprising: a fundus image acquisition unit that acquires a frontal fundus image and a three-dimensional fundus image of a subject's eye; a registration unit that performs registration between the frontal fundus image and the three-dimensional fundus image; a frontal vascular region detection unit that analyzes the frontal fundus image to detect a frontal vascular region; a three-dimensional vascular region identification unit that identifies a three-dimensional vascular region in the three-dimensional fundus image that corresponds to the frontal vascular region in the frontal fundus image based on the result of the registration; and an orientation information generation unit that generates orientation information of the three-dimensional vascular region based on data on a common region between a predetermined partial region in the three-dimensional fundus image and the three-dimensional vascular region.

2. The ophthalmologic device of claim 1, wherein the orientation information generating unit generates Doppler angle information indicating the magnitude of the Doppler angle in optical coherence tomography blood flow measurement for the blood vessels of the fundus corresponding to the three-dimensional vascular region based on the data of the common region, and the orientation information includes the Doppler angle information.

3. The ophthalmic device of claim 1, wherein the orientation information generating unit determines the magnitude of the Doppler angle in optical coherence tomography blood flow measurement for the blood vessels in the fundus corresponding to the three-dimensional vascular region based on the data of the common region, and generates evaluation information by applying an evaluation process to the magnitude of the Doppler angle, and the orientation information includes the evaluation information.

4. An ophthalmologic device according to claim 2 or 3, wherein the front vascular region detection unit detects a plurality of front vascular regions, the three-dimensional vascular region identification unit identifies a plurality of three-dimensional vascular regions respectively corresponding to the plurality of front vascular regions, and the orientation information generation unit generates orientation distribution information indicating the distribution of orientation information of the plurality of three-dimensional vascular regions based on data of an area common to the partial region and the plurality of three-dimensional vascular regions.

5. The ophthalmic device according to claim 4, wherein the partial region is a region surrounding the optic disc of the subject's eye and includes a first cylinder side surface and a second cylinder side surface.

6. The ophthalmologic device of claim 5, wherein the orientation information generating unit analyzes at least one of the frontal fundus image and the three-dimensional fundus image to identify the center position of the optic disc, sets the side of a first cylinder having a central axis passing through the center position and a first radius as the side of the first cylinder, and sets the side of a second cylinder having the central axis and a second radius larger than the first radius as the side of the second cylinder.

7. The ophthalmologic device of claim 5, wherein the orientation information generation unit analyzes at least one of the frontal fundus image and the three-dimensional fundus image to identify the center position of the optic disc and generate morphological information; determines a first dimension that is the dimension of the side surface of the first cylinder and a second dimension that is the dimension of the side surface of the second cylinder and is larger than the first dimension based on the morphological information; sets the side surface of a first elliptical cylinder having a central axis passing through the center position and a first major radius and a first minor radius based on the first dimension as the side surface of the first cylinder; and sets the side surface of a second elliptical cylinder having the central axis and a second major radius and a second minor radius based on the second dimension as the side surface of the second cylinder.

8. An ophthalmic device according to any one of claims 4 to 7, wherein the orientation information generating unit generates first position information indicating the position of an intersection between the plurality of three-dimensional vascular regions and the side surface of the first cylinder, generates second position information indicating the position of an intersection between the plurality of three-dimensional vascular regions and the side surface of the second cylinder, and generates the orientation distribution information based on the first position information and the second position information.

9. An ophthalmologic device according to any one of claims 4 to 8, further comprising a display control unit that displays the frontal fundus image on a display device and displays an orientation distribution image based on the orientation distribution information on the frontal fundus image.

10. An ophthalmologic device according to any one of claims 4 to 9, wherein the fundus image acquisition unit includes a scanning unit that applies an optical coherence tomography scan to the fundus, and a scan control unit that controls the scanning unit, and further includes a data processing unit that processes data collected from the fundus by the optical coherence tomography scan, and a vascular region of interest designation unit that designates a vascular region of interest from among the plurality of three-dimensional vascular regions, wherein the scan control unit controls the scanning unit to apply repeated scans to a cross section of the fundus corresponding to a cross section of the vascular region of interest located near the partial region, and the data processing unit generates hemodynamic information in the blood vessel of interest corresponding to the vascular region of interest based on the data collected by the repeated scans.

11. A method for controlling an ophthalmologic device having a processor, comprising causing the processor to perform the following: a fundus image acquisition process for acquiring a frontal fundus image and a three-dimensional fundus image of a subject's eye; registration between the frontal fundus image and the three-dimensional fundus image; a frontal vascular region detection process for analyzing the frontal fundus image to detect a frontal vascular region; a three-dimensional vascular region identification process for identifying a three-dimensional vascular region in the three-dimensional fundus image corresponding to the frontal vascular region in the frontal fundus image based on the result of the registration; and an orientation information generation process for generating orientation information of the three-dimensional vascular region based on data on a common region between a predetermined partial region in the three-dimensional fundus image and the three-dimensional vascular region.

12. A program for causing a computer to execute the method of claim 11.

13. A computer-readable non-transitory recording medium on which the program of claim 12 is recorded.

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