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

Abstract

A scan unit of an ophthalmic device according to an embodiment collects data by applying an OCT scan by a scan pattern without flyback to a fundus. A cross-sectional image generation unit generates a plurality of cross-sectional images respectively corresponding to a plurality of cross-sections of the fundus on the basis of the collected data. A blood vessel region identification unit identifies a plurality of blood vessel region groups respectively corresponding to the plurality of cross-sectional images, by detecting the blood vessel region groups from each of the generated cross-sectional images. A blood vessel region association unit performs association, among the plurality of blood vessel region groups identified from the plurality of cross-sectional images, between blood vessel regions that correspond to different cross-sections of the same blood vessel. A blood vessel map generation unit generates a blood vessel map on the basis of the result of the association of the blood vessel regions.

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 scanning unit, a cross-sectional image generating unit, a vascular region identifying unit, a vascular region matching unit, and a vascular map generating unit. The scanning unit is configured to collect data by applying an optical coherence tomography scan using a scan pattern without flyback to the fundus of the subject's eye. The cross-sectional image generating unit is configured to generate a plurality of cross-sectional images corresponding to a plurality of cross sections of the fundus based on the data collected by the scanning unit. The vascular region identifying unit is configured to identify a plurality of vascular region groups corresponding to the plurality of cross-sectional images by detecting a vascular region group from each of the generated cross-sectional images. The vascular region matching unit is configured to match vascular regions corresponding to different cross sections of the same blood vessel among the plurality of vascular region groups identified from the plurality of cross-sectional images. The vascular map generating unit is configured to generate a vascular map indicating the distribution of blood vessels based on the results of the vascular region matching.

[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 a configuration of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 6 is a schematic diagram showing a configuration of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 7 is a schematic diagram showing a configuration of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 8 is a schematic diagram showing a configuration of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 9 is a schematic diagram showing a configuration of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 10 is a schematic diagram showing a configuration of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 11 is a schematic diagram showing a configuration of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 12 is a schematic diagram showing a configuration of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 13 is a schematic diagram showing a configuration of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 14 is a schematic diagram showing a configuration of an ophthalmic apparatus according to a non-limiting embodiment. FIG. 1 is a schematic diagram showing the configuration of an ophthalmic apparatus according to a non-limiting embodiment; FIG. 2 is a flowchart showing the operation of an ophthalmic apparatus according to a non-limiting embodiment; FIG. 3 is a schematic diagram showing the configuration of an ophthalmic apparatus according to a non-limiting embodiment; FIG. 4 is a flowchart showing the operation of an ophthalmic apparatus according to a non-limiting embodiment; FIG. 5 is a schematic diagram showing the configuration of an ophthalmic apparatus according to a non-limiting embodiment; FIG. 6 is a flowchart showing 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 are intended to improve the quality of processes and tasks related to fundus hemodynamic measurements, including, but not limited to, alignment of device optics with the fundus, estimation of Doppler angles, and search for blood vessels to which measurements are applied.

[0014] Conventionally, alignment has been performed by referring to infrared observation images (real-time moving images) of the fundus. However, some embodiments provide a novel alignment method that uses the positions of fundus blood vessels obtained from OCT images.

[0015] In addition, in the past, users determined the blood vessels and cross sections to which blood flow measurement should be applied while referring to an infrared observation image of the fundus or a previously acquired fundus photograph. Some embodiments provide a novel method for generating orientation information (e.g., Doppler angle, its suitability) of fundus blood vessels. Furthermore, some embodiments provide a novel method for generating orientation information (e.g., Doppler angle, its suitability) of fundus blood vessels. Furthermore, some embodiments provide a novel method for generating orientation information (e.g., Doppler angle, cross section, etc.) to simplify and reduce the labor required for specifying blood flow measurement positions (e.g., blood vessels to be measured, cross sections to be measured, etc.). Furthermore, some embodiments provide a novel method for generating orientation information (e.g., Doppler angle, Doppler angle, and ... flow measurement positions, cross sections to be measured, etc.). Furthermore, some embodiments provide a novel method for generating orientation information (e.g., Doppler angle, Doppler angle, and cross section, etc.) to simplify and reduce the labor required for specifying blood flow measurement positions (e.g., blood flow measurement positions, cross sections to be measured, etc.). Furthermore, some embodiments provide a novel method for generating orientation information (e.g., Doppler angle, Doppler angle, and cross section, etc.) to simplify and reduce the labor required for specifying blood flow measurement positions (e.g., blood

[0016] 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.

[0017] 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.

[0018] <Embodiments of Ophthalmic Apparatus> Several non-limiting aspects of an ophthalmic apparatus according to an embodiment will be described. The ophthalmic apparatus according to an embodiment has a function of performing OCT blood flow measurement and a function of processing data obtained by the OCT blood flow measurement.

[0019] 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). However, some other embodiments of the ophthalmic device may not be capable of performing at least a part of the processing of OCT blood flow measurement.

[0020] 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.

[0021] 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.

[0022] 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).

[0023] 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.

[0024] 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.

[0025] 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).

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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).

[0032] 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 and autofocusing can be performed.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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).

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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 system.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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).

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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 in the cross section of interest C0. 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.

[0084] 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.

[0085] 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).

[0086] 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.

[0087] 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.

[0088] 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.).

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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).

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] <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.

[0103] 7 shows the configuration of an ophthalmic apparatus 1000 according to one non-limiting embodiment. The ophthalmic apparatus 1000 includes a scanning unit 1010, a cross-sectional image generating unit 1020, a vascular region identifying unit 1030, a vascular region associating unit 1040, and a vascular map generating unit 1050.

[0104] The scanning unit 1010 is configured to collect data by applying an OCT scan to the fundus Ef of the subject's eye E. The ophthalmologic apparatus 1 of a non-limiting aspect can realize the function of the scanning unit 1010 using the fundus camera unit 2 and the OCT unit 100.

[0105] The scanning unit 1010 can apply OCT scanning to the fundus Ef using a scan pattern that does not involve flyback. Flyback is an operation of moving the scan position to a predetermined initial position without collecting data. For example, in a raster scan consisting of multiple B-scans arranged parallel to each other and oriented in the same scan direction, flyback is an operation of moving the scan position (the projection target position of the measurement light LS) from the end position of one B-scan to the start position of the next B-scan. A scan pattern that involves flyback results in a long period of time during which data collection is stopped, making it relatively disadvantageous for processing or operations that require speed. Some embodiments have been achieved by focusing on this problem, and aim to improve the quality of Doppler angle estimation and alignment performed, for example, in the preparation stage for the main scan (repeated scan) of OCT blood flow measurement.

[0106] 8A to 8C show an example of a scan pattern without a flyback. The scan pattern in this example is a concentric pattern that is a combination of two circular patterns. The number of circular patterns included in the concentric pattern may be any number, and may be three or more.

[0107] 8A shows the fundus oculi Ef. Reference numeral 1200 denotes the optic disc, and reference numeral 1200a denotes the central position of the optic disc 1200 (optic disc center). Reference numerals 1201 and 1202 denote two circular patterns. The centers of the two circular patterns 1201 and 1202 are both the optic disc center 1200a.

[0108] 8B, the radius of the circular pattern 1201 is R1, and the radius of the circular pattern 1202 is R2. Here, the radius R2 is larger than the radius R1. The region of the fundus Ef to which the circular pattern 1201 is applied is a cylindrical side surface 1201b defined by a central axis 1201a passing through the optic optic center 1200a and a radius R1. Furthermore, the region of the fundus Ef to which the circular pattern 1202 is applied is a cylindrical side surface 1202b defined by a central axis 1202a passing through the optic optic center 1200a and a radius R2. The central axis 1202a coincides with the central axis 1201a.

[0109] 8C shows an example of an OCT scan using a scan pattern consisting of two circular patterns 1201 and 1202. In this example, a circle scan along the circular pattern 1201 is performed immediately after a circle scan along the circular pattern 1202. More specifically, in this example, a counterclockwise circle scan 1203a is started along the circular pattern 1201 from a position 1201c on the circular pattern 1201. This circle scan 1203a is performed one or more times. The circle scan 1203a along the circular pattern 1201 ends at a position 1201c. In this example, an operation 1203b (changing the orientation of the optical scanner 44) is performed to move the scan target position from a position 1201c on the circular pattern 1201 to a position 1202c on the circular pattern 1202 immediately after the circle scan 1203a. In the OCT scan of this example, immediately after this operation (scan target movement) 1203b, a counterclockwise circle scan 1203c is started along the circular pattern 1202 from a position 1202c on the circular pattern 1202. This circle scan 1203c is executed once or more than once. Note that data may be collected while the scan target movement 1203b is being performed. In other words, the scan target movement 1203b in some embodiments may be a scan (data collection).

[0110] 8A to 8C is one example of a scan pattern that includes multiple patterns (two circular patterns 1201 and 1202) that do not each include a flyback. Other scan patterns that have such features include a scan pattern that combines multiple closed curves having the same or different shapes, a scan pattern that combines multiple polygons having the same or different shapes, and a raster scan that combines multiple B-scans that are oriented alternately.

[0111] 8A to 8C is an example of a scan pattern including a concentric pattern, which is a combination of multiple concentrically arranged patterns. Other scan patterns having such an aspect include a scan pattern that combines multiple concentrically arranged closed curves having the same shape, and a scan pattern that combines multiple concentrically arranged polygons having the same shape. The multiple cross sections of the fundus Ef scanned by the scan pattern of this aspect include multiple concentric cross sections that respectively correspond to the multiple concentrically arranged patterns that make up the scan pattern. In the example shown in FIGS. 8A to 8C, two cylindrical side surfaces 1201b and 1202b correspond to such multiple concentric cross sections.

[0112] The scan pattern without flyback is not limited to the above examples and may be any pattern, such as a spiral scan pattern, a Lissajous curve scan pattern, or a similar scan pattern.

[0113] The cross-sectional image generating unit 1020 is configured to generate a plurality of cross-sectional images corresponding to a plurality of cross sections of the fundus Ef based on data collected from the fundus Ef by the scanning unit 1010. The cross-sectional image generating unit 1020 is realized by cooperation between hardware including circuits and cross-sectional image generating software. The ophthalmologic apparatus 1 of a non-limiting aspect can realize the function of the cross-sectional image generating unit 1020 using the data processing unit 230 (image generating unit 220).

[0114] When a scan pattern that is a combination of multiple patterns, each of which does not involve a flyback, is applied, the cross-sectional image generation unit 1020 generates a cross-sectional image corresponding to the cross section to which each of the multiple patterns that does not involve a flyback is applied.

[0115] When a scan pattern consisting of a plurality of concentric patterns each having no flyback is applied, the scan unit 1010 collects data from a plurality of concentric slices corresponding to the plurality of patterns, respectively. The cross-sectional image generating unit 1020 generates cross-sectional images corresponding to each concentric slice based on the data collected from the plurality of concentric slices.

[0116] 8A to 8C, the scanning unit 1010 collects data from a cylinder side surface 1201b corresponding to the circular pattern 1201, and collects data from a cylinder side surface 1202b corresponding to the circular pattern 1202. The cross-sectional image generating unit 1020 generates a cross-sectional image depicting the cylinder side surface 1201b based on the data collected from the cylinder side surface 1201b, and generates a cross-sectional image depicting the cylinder side surface 1202b based on the data collected from the cylinder side surface 1202b.

[0117] When the scanning unit 1010 applies OCT scans to the fundus oculi Ef multiple times using a scan pattern without flyback to collect multiple pieces of data, the cross-sectional image generating unit 1020 can generate multiple cross-sectional images corresponding to the multiple scans and synthesize these multiple cross-sectional images to generate a composite cross-sectional image. The synthesis of the multiple cross-sectional images is, for example, averaging. The averaging reduces random noise such as speckle noise.

[0118] 8A to 8C , the scanning unit 1010 performs a circle scan using a circular pattern 1201 multiple times to collect multiple pieces of data from the cylinder's side surface 1201b, and performs a circle scan using a circular pattern 1202 multiple times to collect multiple pieces of data from the cylinder's side surface 1202b. The cross-sectional image generating unit 1020 generates multiple cross-sectional images depicting the cylinder's side surface 1201b based on the multiple pieces of data collected from the cylinder's side surface 1201b, and generates multiple cross-sectional images depicting the cylinder's side surface 1202b based on the multiple pieces of data collected from the cylinder's side surface 1202b. Furthermore, the cross-sectional image generating unit 1020 combines the multiple cross-sectional images of the cylinder's side surface 1201b to generate a composite cross-sectional image, and combines the multiple cross-sectional images of the cylinder's side surface 1202b to generate a composite cross-sectional image.

[0119] When the scanning unit 1010 applies OCT scans to the fundus oculi Ef multiple times using a scan pattern without flyback to collect multiple data sets, and the cross-sectional image generating unit 1020 generates multiple cross-sectional images corresponding to the multiple scans, the ophthalmologic apparatus 1000 may select a cross-sectional image suitable for subsequent processing (e.g., identification of a vascular region) from among the multiple cross-sectional images generated. Here, evaluation of each cross-sectional image may be performed using any method. As a non-limiting example, Portilla-Simoncelli Statistics (PSS), an image texture feature based on human visual perception, may be used as an evaluation value. In this case, a cross-sectional image with a large PSS value is selected.

[0120] The vascular region specifying unit 1030 is configured to detect vascular region groups by analyzing each cross-sectional image generated by the cross-sectional image generating unit 1020. This specifies a plurality of vascular region groups corresponding to the plurality of cross-sectional images generated by the cross-sectional image generating unit 1020. A vascular region group includes one or more vascular regions. A vascular region is an image region corresponding to a cross section of a blood vessel.

[0121] Any image analysis method may be used to detect a vascular region from a cross-sectional image. For example, this image analysis may be any image segmentation method. The image segmentation method executed by the vascular region identifying 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.

[0122] Non-limiting examples of image segmentation methods applicable to the vascular region identification unit 1030 include thresholding-based methods, edge detection-based methods, region-based methods, clustering-based methods, convolutional neural network (CNN)-based methods, transformer-based methods, generative adversarial network (GAN)-based methods, self-supervised learning (SSL)-based methods, graph-based methods, etc. The image segmentation performed by the vascular region identification unit 1030 may be a combination of two or more methods.

[0123] In some embodiments, the vascular region identification unit 1030 applies projection (image integration) to each cross-sectional image generated by the cross-sectional image generation unit 1020 in the A-scan direction (z direction) of the OCT scan applied to the fundus Ef by the scan unit 1010. This generates multiple projection images corresponding to the multiple cross-sectional images generated by the cross-sectional image generation unit 1020. Furthermore, the vascular region identification unit 1030 detects vascular regions from the cross-sectional image (i.e., the cross-sectional image corresponding to the projection image) that is the original image of the projection image based on the brightness distribution in each generated projection image. Generally, the brightness of pixels corresponding to blood vessels is lower than the brightness of pixels corresponding to tissue other than blood vessels. The vascular region detection of this embodiment may include processing (e.g., threshold processing, binarization, etc.) to detect low-brightness regions in the projection image. Furthermore, this embodiment may combine a brightness-based image segmentation method with an image segmentation method based on an index other than brightness.

[0124] The vascular region specifying unit 1030 is realized by cooperation between hardware including a circuit and vascular region specifying software. The ophthalmologic apparatus 1 of a non-limiting aspect can perform analysis processing for detecting a vascular region from an OCT cross-sectional image by using a vascular region specifying function realized by using the data processing unit 230 (vascular region specifying unit 231).

[0125] The vascular region matching unit 1040 is configured to match vascular regions corresponding to different cross sections of the same blood vessel among a plurality of vascular region groups identified by the vascular region identifying unit 1030 from a plurality of cross-sectional images.

[0126] For the purpose of explaining the vascular region association process, two adjacent cross-sectional images will be referred to as a first cross-sectional image and a second cross-sectional image. Also, a cross-section of the fundus Ef corresponding to the first cross-sectional image will be referred to as a first cross-section, and a cross-section of the fundus Ef corresponding to the second cross-sectional image will be referred to as a second cross-section. Furthermore, a group of vascular regions identified from the first cross-sectional image will be referred to as a first group of vascular regions, and a group of vascular regions identified from the second cross-sectional image will be referred to as a second group of vascular regions.

[0127] When the distance between the first cross section and the second cross section is sufficiently small, the vascular region association unit 1040 in a non-limiting embodiment determines the position of each vascular region (referred to as a first vascular region) in the first cross-sectional image and the position of each vascular region (referred to as a second vascular region) in the second cross-sectional image. The position of a vascular region may be the position of a feature point in the vascular region (e.g., a center position, a center of gravity position, an upper end position, a lower end position, etc.). Furthermore, the position of a vascular region may be information indicating its position in the cross-sectional image where it was detected (i.e., coordinates in a two-dimensional coordinate system representing the pixel position of the cross-sectional image), information indicating its position in a three-dimensional image including both the first cross section and the second cross section (coordinates in a three-dimensional coordinate system representing the position in the three-dimensional region), or other information that can be used to define the position.

[0128] It is rare for the running state of blood vessels to change suddenly (discontinuously), especially in the relatively large blood vessels that are the subject of OCT blood flow measurement. Therefore, when the distance between the first cross section and the second cross section is sufficiently small, it can be considered that there will be no significant deviation between the position of the blood vessel region (first blood vessel region) in the first cross-sectional image and the position of the blood vessel region (second blood vessel region) in the second cross-sectional image for one blood vessel.

[0129] Under this assumption, the vascular region associating unit 1040 can identify pairs of first and second vascular regions corresponding to different cross sections of the same blood vessel by comparing the position of each vascular region in the first cross-sectional image with the position of each vascular region in the second cross-sectional image, and associate these with each other. For example, for any first vascular region belonging to a first vascular region group, the vascular region associating unit 1040 can compare the position of the first vascular region with the positions of each second vascular region belonging to a second vascular region group, identify the second vascular region having the smallest distance from the first vascular region, and associate the identified second vascular region with the first vascular region.

[0130] When the distance between the first cross section and the second cross section is sufficiently small, it is possible to assume that the positions of the first vascular region and the second vascular region corresponding to the same blood vessel are close to each other. Other assumptions can also be considered. For example, it can be assumed that the areas of the first vascular region and the second vascular region corresponding to the same blood vessel are substantially equal, or that the shapes of the first vascular region and the second vascular region corresponding to the same blood vessel are substantially equal. Furthermore, when the distance between the first cross section and the second cross section is sufficiently small, it can be assumed that no crossing of blood vessels occurs in the region between these cross sections. Therefore, it can be assumed that the spatial order (positional order) of the multiple blood vessels depicted on both cross sections is the same. The vascular region association unit 1040 may be configured to perform the vascular region association process taking such assumptions into account.

[0131] The criterion for whether the interval between the first cross section and the second cross section is sufficiently small may be determined arbitrarily, and may take into consideration, for example, the position of the region to which the OCT scan is applied on the fundus Ef, the state of the fundus blood vessels, etc. Furthermore, when OCT blood flow measurement is performed, for example, the distance between the two supplementary cross sections C1 and C2 shown in Fig. 5A (supplementary cross-sectional images G1 and G2 shown in Fig. 6A) is generally set to be sufficiently small, so in embodiments intended for similar applications, it can be assumed that the interval between the first cross section and the second cross section is sufficiently small.

[0132] On the other hand, when the distance between the first cross section and the second cross section is not sufficiently small, the vascular region associating unit 1040 in a non-limiting embodiment may be configured to, for example, grasp the positional relationship between the first cross section and the second cross section, or the positional relationship between each vascular region belonging to the first vascular region group and each vascular region belonging to the second vascular region group, by referring to a separately acquired image (a frontal fundus image and / or a three-dimensional fundus image). Furthermore, the vascular region associating unit 1040 may be configured to identify pairs of first and second vascular regions corresponding to different cross sections of the same blood vessel by referring to the obtained positional relationship, and associate these with each other.

[0133] The vascular region matching unit 1040 is realized by cooperation between hardware including a circuit and vascular region matching software. The ophthalmologic apparatus 1 of a non-limiting aspect can perform analysis processing for matching between vascular regions by the vascular region matching function realized by the data processing unit 230.

[0134] The vascular map generating unit 1050 is configured to generate information indicating the distribution of blood vessels (vascular map) based on the result of the vascular region association obtained by the vascular region associating unit 1040. The range of the vascular distribution represented by the vascular map includes at least a part of the region of the fundus Ef defined by the multiple cross sections corresponding to the multiple cross-sectional images generated by the cross-sectional image generating unit 1020.

[0135] The vascular map is information indicating at least the positions (coordinates) of blood vessels (the same blood vessels described above) corresponding to multiple vascular regions associated with each other by the vascular region associating unit 1040, and is information indicating the distribution state of blood vessels in the fundus Ef. The vascular map may be visual information obtained by visualizing the vascular positions, or may be unvisualized vascular position data. The visual information may be provided for image processing, image analysis, display, printing, etc. The vascular position data may be provided for data processing, data analysis, imaging (visualization), etc.

[0136] The vascular map generating unit 1050 is realized by cooperation between hardware including a circuit and vascular map generating software. The ophthalmologic apparatus 1 of a non-limiting aspect can perform processing for generating a vascular map by using a vascular map generating function realized by the data processing unit 230.

[0137] 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.

[0138] Figure 9 shows an example of one operation of the ophthalmic device 1000. As a non-limiting example, refer to Figures 8A to 8C.

[0139] First, in step S1, the scanning unit 1010 applies an OCT scan to the fundus Ef of the subject's eye E using a scan pattern that does not involve flyback, and collects data.

[0140] 8C , data is collected from the cylinder side surface 1201b along the circular pattern 1201, and data is collected from the cylinder side surface 1202b along the circular pattern 1202.

[0141] In step S2, the cross-sectional image generating part 1020 generates a plurality of cross-sectional images corresponding to the plurality of cross sections of the fundus oculi Ef, respectively, based on the data collected in step S1.

[0142] In a specific example of step S2, the cross-sectional image generating unit 1020 generates a cross-sectional image 1301 representing the cylinder side surface 1201b based on data collected from the cylinder side surface 1201b along the circular pattern 1201 in step S1 (see FIG. 10A). Furthermore, the cross-sectional image generating unit 1020 generates a cross-sectional image 1302 representing the cylinder side surface 1202b based on data collected from the cylinder side surface 1202b along the circular pattern 1202 in step S1 (see FIG. 10A).

[0143] In step S3, the vascular region specifying unit 1030 detects vascular region groups from each of the plurality of cross-sectional images generated in step S2, thereby specifying a plurality of vascular region groups corresponding to the plurality of cross-sectional images, respectively.

[0144] In a specific example of step S3, the vascular region specifying unit 1030 detects vascular region groups 1301a, 1301b, 1301c, and 1301d from the cross-sectional image 1301 generated in step S2 (see Fig. 10A). Furthermore, the vascular region specifying unit 1030 detects vascular region groups 1302a, 1302b, 1302c, and 1302d from the cross-sectional image 1302 generated in step S2 (see Fig. 10A).

[0145] In step S4, the vascular region associating unit 1040 associates vascular regions corresponding to different cross sections of the same blood vessel among the plurality of vascular region groups identified in step S4.

[0146] In a specific example of step S4, the vascular region association unit 1040 identifies pairs of vascular regions corresponding to different cross sections of the same blood vessel between the vascular region group 1301a, 1301b, 1301c, and 1301d corresponding to the cross-sectional image 1301 and the vascular region group 1302a, 1302b, 1302c, and 1302d corresponding to the cross-sectional image 1302. In this example, the following four vascular region pairs are identified: a first pair consisting of the vascular region 1301a and the vascular region 1302a corresponding to two cross sections of the first blood vessel; a second pair consisting of the vascular region 1301b and the vascular region 1302b corresponding to two cross sections of the second blood vessel; a third pair consisting of the vascular region 1301c and the vascular region 1302c corresponding to two cross sections of the third blood vessel; and a fourth pair consisting of the vascular region 1301d and the vascular region 1302d corresponding to two cross sections of the fourth blood vessel. The vascular region associating unit 1040 associates the two vascular regions belonging to each pair with each other, thereby obtaining a first pair association 1303a, a second pair association 1303b, a third pair association 1303c, and a fourth pair association 1303d.

[0147] In step S5, the vascular map generating unit 1050 generates a vascular map based on the result of the association of vascular regions obtained in step S4.

[0148] In a specific example of step S5, the vascular map generation unit 1050 determines a first connection region connecting the vascular regions 1301a and 1302a belonging to the first pair, a second connection region connecting the vascular regions 1301b and 1302b belonging to the second pair, a third connection region connecting the vascular regions 1301c and 1302c belonging to the third pair, and a fourth connection region connecting the vascular regions 1301d and 1302d belonging to the fourth pair.

[0149] In the first pair, the vascular region 1301a is a region on the cylindrical side surface 1201b along the circular pattern 1201, and the vascular region 1302a is a region on the cylindrical side surface 1202b along the circular pattern 1202. A first connection region connects the vascular region 1301a and the vascular region 1302a. The first connection region has two ends, the first end being located in the vascular region 1301a (the cylindrical side surface 1201b, the circular pattern 1201) and the second end being located in the vascular region 1302a (the cylindrical side surface 1202b, the circular pattern 1202). The same applies to the second connection region based on the second pair, the third connection region based on the third pair, and the fourth connection region based on the fourth pair.

[0150] Figures 10B and 10C show two non-limiting examples of vascular maps. The vascular map 1310 of Figure 10B represents two-dimensional vascularity when viewed from a frontal perspective. Objects shown in dashed lines are included for illustrative purposes and may not be visible in the vascular map 1310. At least the circular patterns 1201 and 1202 may be visible. Reference numeral 1311 denotes the optic disc. Reference numerals 1312a, 1312b, 1312c, and 1312d each denote a blood vessel.

[0151] Reference numeral 1313a denotes a first connection region connecting the two vascular regions 1301a and 1302a belonging to the first pair. The first connection region 1313a corresponds to a part of the blood vessel 1312a. Reference numeral 1313b denotes a second connection region connecting the two vascular regions 1301b and 1302b belonging to the second pair. The second connection region 1313b corresponds to a part of the blood vessel 1312b. Reference numeral 1313c denotes a third connection region connecting the two vascular regions 1301c and 1302c belonging to the third pair. The third connection region 1313c corresponds to a part of the blood vessel 1312c. Reference numeral 1313d denotes a fourth connection region connecting the two vascular regions 1301d and 1302d belonging to the fourth pair. The fourth connection region 1313d corresponds to a part of the blood vessel 1312d.

[0152] To visualize the optic disc 1311 and / or blood vessels 1312a-1312d, an en face fundus image can be used, which may be, for example, a fundus camera image, an SLO image, or an OCT en face image (projection image, an annular image, etc.).

[0153] The vascular map 1320 in FIG. 10C represents a three-dimensional vascular distribution. The vascular map 1320 may be three-dimensional data defined in a three-dimensional coordinate system, three-dimensional image data (volume data, stack data, etc.) obtained by visualizing this three-dimensional data, or a rendered image of this three-dimensional image data (volume rendering image, etc.). Objects indicated by dashed lines are shown for explanatory purposes and may not be visualized in the vascular map 1320. Note that the cylinder side surfaces 1201b and 1202b, as well as the circular patterns 1201 and 1202 (not shown), may be visualized. Reference numeral 1321 denotes the optic disc. Reference numerals 1322a, 1322b, 13222c, and 1322d each denote a blood vessel.

[0154] Reference numeral 1323a denotes a first connection region connecting the two vascular regions 1301a and 1302a belonging to the first pair. The first connection region 1323a corresponds to a part of the blood vessel 1322a. Reference numeral 1323b denotes a second connection region connecting the two vascular regions 1301b and 1302b belonging to the second pair. The second connection region 1323b corresponds to a part of the blood vessel 1322b. Reference numeral 1323c denotes a third connection region connecting the two vascular regions 1301c and 1302c belonging to the third pair. The third connection region 1323c corresponds to a part of the blood vessel 1322c. Reference numeral 1323d denotes a fourth connection region connecting the two vascular regions 1301d and 1302d belonging to the fourth pair. The fourth connection region 1323d corresponds to a part of the blood vessel 1322d.

[0155] An ophthalmic device 1000 capable of executing the processing procedures according to this operational example collects data from the fundus oculi Ef by OCT scanning using a scan pattern without a flyback, generates multiple cross-sectional images corresponding to multiple cross sections, identifies multiple groups of vascular regions corresponding to the multiple cross-sectional images, and generates a vascular map by associating vascular regions corresponding to different cross sections of the same blood vessel. One advantage of the ophthalmic device 1000 is that the vascular map can be generated quickly by using a scan pattern without a flyback. This makes it possible to use the vascular map in preparatory steps (e.g., Doppler angle estimation, alignment, search for blood vessels of interest, etc.) in OCT blood flow measurement (fundus hemodynamic measurement), thereby improving the quality of the OCT blood flow measurement.

[0156] 11 shows the configuration of an ophthalmic apparatus 1400 according to one non-limiting embodiment. Elements of the ophthalmic apparatus 1400 that have the same names and the same reference numerals as elements of the ophthalmic apparatus 1000 in FIG. 7 may have the same configurations and functions as the corresponding elements in the ophthalmic apparatus 1000, unless otherwise specified. However, this does not exclude the adoption of modified means, equivalent means, alternative means, etc. of the corresponding elements.

[0157] The ophthalmic apparatus 1400 includes the same elements as the ophthalmic apparatus 1000, namely, a scanning unit 1010, a cross-sectional image generating unit 1020, a vascular region identifying unit 1030, a vascular region associating unit 1040, and a vascular map generating unit 1050. In addition to these elements, the ophthalmic apparatus 1400 includes a scan control unit 1060, a blood vessel of interest designating unit 1070, a hemodynamic information generating unit 1080, a display control unit 1090, and a display device 1100.

[0158] The scan control unit 1060 is configured to control the scan unit 1010. For example, the scan control unit 1060 can control the scan unit 1010 so as to apply repeated scans of OCT blood flow measurement to a pre-specified blood vessel of interest in the fundus Ef. The designation of the blood vessel of interest may be performed automatically or manually. The automatic designation of the blood vessel of interest is performed, for example, by a blood vessel designation unit 1070 described below. The manual designation is performed, for example, by a combination of displaying an image of the fundus Ef using a user interface (the above-mentioned user interface 240) and performing a position designation operation on this displayed image.

[0159] The scan control unit 1060 is realized by cooperation between hardware including a circuit and scan control software. The ophthalmologic apparatus 1 of a non-limiting aspect can realize the function of the scan control unit 1060 by using the control unit 240 (main control unit 211).

[0160] The vessel of interest designation unit 1070 is configured to analyze the vessel map 1051 generated by the vessel map generation unit 1050 and designate a vessel of interest to which OCT blood flow measurement is to be applied. As described above, the vessel map 1051 generated by the vessel map generation unit 1050 visualizes the distribution state of multiple blood vessels in the fundus Ef. The vessel of interest designation unit 1070 may be configured to select a vessel of interest from the multiple blood vessels presented in the vessel map 1051. The number of vessels of interest selected may be any number equal to or greater than one. The vessel of interest designated by the vessel of interest designation unit 1070 is treated as, for example, a vessel of interest Db shown in FIG. 5A or 5B .

[0161] The vessel of interest designation unit 1070 selects a vessel of interest based on a preset criterion. This criterion is referred to as a selection criterion. The selection criterion may include an index related to the direction of the vessel. Examples of the vessel direction index include the magnitude of the Doppler angle in OCT blood flow measurement (Doppler angle) and the suitability of the Doppler angle in OCT blood flow measurement.

[0162] In some embodiments, the preferred value of 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. However, although measurements can be performed even when the Doppler angle is as small as 75 degrees, a problem occurs 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, when the Doppler angle is as large as 85 degrees, a problem occurs 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.

[0163] Considering these circumstances regarding the Doppler angle, a suitable range for the Doppler angle in OCT blood flow measurement is typically set to a range of 77 degrees to 83 degrees. This range is referred to as the acceptable Doppler angle range. The ophthalmic apparatus 1400 (e.g., any element among the vascular map generator 1050, the interested blood vessel designator 1070, and the hemodynamic information generator 1080) can estimate the Doppler angle of each blood vessel displayed on the vascular map 1051. For the calculation method, please refer to the Doppler angle calculator 233 of the ophthalmic apparatus 1 described above.

[0164] The vessel of interest designation unit 1070 compares the Doppler angle of each blood vessel displayed on the blood vessel map 1051 with the Doppler angle tolerance range. If the Doppler angle value of a certain blood vessel falls within the tolerance range, the vessel of interest designation unit 1070 determines that the Doppler angle of the certain blood vessel is good. If there are two or more blood vessels with good Doppler angles and only one blood vessel of interest is designated, the vessel of interest designation unit 1070 may be configured to select the blood vessel with the Doppler angle closest to the optimal value (typically 80 degrees). In some aspects, each blood vessel with a good Doppler angle may be designated as a blood vessel of interest. In some aspects, a predetermined number of blood vessels of interest may be selected from a plurality of blood vessels with good Doppler angles.

[0165] In addition to or instead of orientation information such as the Doppler angle or the favorability, 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, and position (e.g., position relative to the optic disc). The blood vessel of interest designation unit 1070 can select a blood vessel of interest by considering two or more types of indices in stages or in parallel.

[0166] In another non-limiting example, the vessel of interest designation unit 1070 may be configured to designate a vessel selected by the user from among a plurality of blood vessels presented in the vascular map 1051 as the vessel of interest. In this example, the ophthalmic apparatus 1400 (the display control unit 1090 and the display device 1100) displays the vascular map 1051 (a visualized image of the vascular map 1051). The user can select a vessel of interest by referring to the displayed vascular map 1051. The operation of inputting the selected vessel of interest is performed using a user interface (e.g., the user interface 240 of the ophthalmic apparatus 1) not shown.

[0167] The blood vessel of interest designation unit 1070 is realized by cooperation between hardware including a circuit and software for designating the blood vessel of interest. The ophthalmologic apparatus 1 of a non-limiting aspect can realize the function of the blood vessel of interest designation unit 1070 by using the data processing unit 230.

[0168] The hemodynamic information generation unit 1080 is configured to generate hemodynamic information in the blood vessel of interest specified by the blood vessel of interest designation unit 1070 based on data collected by the scanning unit 1010 when the scanning unit 1010 applies a scan for OCT blood flow measurement to the fundus Ef.

[0169] The hemodynamic information generating unit 1080 may have the same configuration as the data processing unit 230 of the ophthalmologic apparatus 1. Specifically, the hemodynamic information generating unit 1080 may include the image generating unit 220, the vascular region specifying unit 231, and the hemodynamic information generating unit 232 shown in FIG.

[0170] In this embodiment, the scan control unit 1060 controls the scan unit 1010 to apply repeated scans for hemodynamic measurement to the blood vessel of interest designated by the blood vessel of interest designation unit 1070. As shown in Figures 5A to 6B, the repeated scans are applied to a specific cross section (cross section of interest) of the blood vessel of interest. The cross section of interest in this embodiment may be set at any position in the blood vessel displayed on the blood vessel map 1051.

[0171] As a non-limiting example, when the blood vessel 1312a presented in the vascular map 1310 in Fig. 10B is designated as a blood vessel of interest, the scan control unit 1060 sets a cross section at an arbitrary position in the first connection region 1313a. For example, the cross section of interest may be set at a position equidistant from the two circular patterns 1201 and 1202 in the first connection region 1313a (i.e., a midpoint between the two vascular regions 1301a and 1302a connected by the first connection region 1313a). This cross section of interest corresponds to the cross section of interest C0 shown in Figs. 5A and 6A, and the two vascular regions 1301a and 1302a correspond to two supplemental cross sections C1 and C2 (two supplemental cross section images G1 and G2).

[0172] The data collected by the scanning unit 1010 through repeated scans of the cross section of interest of the blood vessel of interest is referred to as OCT blood flow measurement data 1075. The blood flow dynamics information generating unit 1080 generates blood flow dynamics information 1085 of the blood vessel of interest designated by the blood vessel of interest designating unit 1070 based on the OCT blood flow measurement data 1075.

[0173] The hemodynamic information generating unit 1080 is realized by cooperation between hardware including a circuit and hemodynamic information generating software. The ophthalmologic apparatus 1 of a non-limiting aspect can realize the function of the hemodynamic information generating unit 1080 by using the data processing unit 230.

[0174] The display device 1100 is any type of display. The display device 1100 may be the display unit 241 of the ophthalmic apparatus 1, for example, the display device 3. The display device 1100 of this embodiment is a component of the ophthalmic apparatus 1400. In another embodiment, the display device may be a peripheral device (external device) of the ophthalmic apparatus.

[0175] The display control unit 1090 is configured to control the display device 1100 to display information. The display control unit 1090 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 1090 using the control unit 240 (main control unit 211).

[0176] The display control unit 1090 causes the display device 1100 to display information generated by the ophthalmic apparatus 1400. Examples of information generated by the ophthalmic apparatus 1400 include an image of the subject's eye E, information on the direction of blood vessels in the fundus Ef (Doppler angle, evaluation information, etc.), a blood vessel map, and information obtained by processing (correcting, analyzing, evaluating, etc.) any of these. In addition, the display device 1100 causes the display device 1100 to display information (e.g., an image) acquired by the ophthalmic apparatus 1400 from an external source.

[0177] Evaluation information, which is a non-limiting example of the above-mentioned blood vessel direction information, will now be described. The evaluation information is information obtained by evaluating the Doppler angle of hemodynamic measurement. The hemodynamic information generation unit 1080 obtains information indicating the magnitude of the Doppler angle (Doppler angle information) using the above-mentioned method. Furthermore, the hemodynamic information generation unit 1080 applies a predetermined evaluation process to this Doppler angle information. This evaluation process evaluates, for example, the suitability of the magnitude of the Doppler angle in OCT blood flow measurement.

[0178] As described above, the preferred range (target range) of the Doppler angle in OCT blood flow measurement may be set to a range of 77 degrees to 83 degrees, and the most preferred value may be set to approximately 80 degrees. In the evaluation process, the hemodynamic information generating unit 1080 compares the Doppler angle value of the target blood vessel with the target range. If the Doppler angle value falls within the target range, the hemodynamic information generating unit 1080 determines that the Doppler angle of the blood vessel is preferred and generates evaluation information indicating this determination result. On the other hand, if the Doppler angle of the blood vessel does not fall within the target range, the hemodynamic information generating unit 1080 generates evaluation information indicating that the Doppler angle of the blood vessel is not preferred. In some embodiments, the target range may be divided into multiple sections to perform a more detailed evaluation of cases where the Doppler angle is preferred. Furthermore, the range outside the target range may be divided into multiple sections to perform a more detailed evaluation of cases where the Doppler angle is not preferred.

[0179] When the ophthalmic apparatus 1400 of this embodiment has a function of photographing the fundus from the front (for example, a function realized by a front photographing unit (not shown) corresponding to the fundus camera unit 2 of the ophthalmic apparatus 1) and / or a function of externally receiving a front fundus image generated by photographing the fundus Ef from the front (for example, a front image receiving unit (not shown) corresponding to the data input / output unit 290 of the ophthalmic apparatus 1), the display control unit 1090 can display the front fundus image and the blood vessel map 1051 on the display device 1100. For example, the display control unit 1090 displays the front fundus image on the display device 1100, and also displays the blood vessel map 1051 (an image obtained by visualizing the front fundus image) on the front fundus image.

[0180] When the blood vessel map 1051 is displayed on the frontal fundus image, it is necessary to perform registration between the frontal fundus image and the blood vessel map 1051. This registration may be performed, for example, by a registration unit (not shown) included in the hemodynamic information generating unit 1080 or the display control unit 1090. The registration unit 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 frontal fundus image and the blood vessel map 1051 by a registration function realized using the data processing unit 230. Some non-limiting examples of this registration are described below.

[0181] In a first non-limiting example, the registration unit is configured to perform registration between the vascular map 1051 and the frontal fundus image using the blood vessels displayed in the vascular map 1051 as landmarks. Each blood vessel displayed in the vascular map 1051 is located in the region between the circular pattern 1201 and the circular pattern 1202, and the two circular patterns 1201 and 1202 are centered on the optic disc center 1200a and have predetermined radii R1 and R2, respectively. By using this information, it is possible to limit the range of searching for portions in the frontal fundus image corresponding to the landmarks. If the vascular map 1051 is three-dimensional data such as the vascular map 1320 in FIG. 10C , projection may be applied to the vascular map 1051 to generate two-dimensional data (a frontal image such as the vascular map 1310 in FIG. 10B ), and registration between this two-dimensional data and the frontal fundus image may be performed.

[0182] In a non-limiting second example, the registration unit is configured to perform registration between the vascular map 1051 and the frontal fundus image using both ends of each of the multiple blood vessels displayed on the vascular map 1051 as multiple landmarks. The both ends of each blood vessel displayed on the vascular map 1051 are a first end located on the circular pattern 1201 and a second end located on the circular pattern 1202. In this example, as in the first example, the search range can be limited. The processing procedure when the vascular map 1051 is three-dimensional data may also be the same as in the first example.

[0183] In the first and second examples described above, registration is performed using objects in the vascular map 1051 as landmarks. In contrast, a non-limiting third example uses at least one cross-sectional image from among the multiple cross-sectional images used to generate the vascular map 1051. The registration unit in this example generates a circular image by applying projection to the cross-sectional image. The cross-sectional image is an OCT intensity image, in which blood vessels are depicted at low brightness. Even in the circular image generated as a projection of such a cross-sectional image, the brightness of pixels corresponding to blood vessels (vascular pixels) is lower than the brightness of pixels corresponding to other tissues. By using such multiple blood vessel pixels as multiple landmarks, registration between the circular image and the frontal fundus image can be performed. Using the registration results, registration can be performed between the cross-sectional image, which is the original image of the circular image, and the frontal fundus image. Furthermore, registration can be performed between the vascular map 1051 generated from this cross-sectional image and the frontal fundus image.

[0184] As described above, the ophthalmic device 1400 of this embodiment (e.g., any of the elements of the vascular map generation unit 1050, the vessel of interest designation unit 1070, and the hemodynamic information generation unit 1080) can estimate the Doppler angle of each blood vessel presented in the vascular map 1051. Furthermore, the ophthalmic device 1400 can generate a Doppler angle map by associating the position information of each blood vessel in the vascular map 1051 with the estimated value of the Doppler angle. Furthermore, the ophthalmic device 1400 can generate evaluation information by applying an evaluation process to the estimated value of the Doppler angle of each blood vessel in the vascular map 1051, and generate a Doppler angle evaluation map by associating the position information of each blood vessel with the evaluation information. The Doppler angle map and the Doppler angle evaluation map contain information indicating the distribution of blood vessel orientations. Visualization of such a map can generate visual information (orientation distribution image) that represents the distribution of blood vessel orientations. The display control unit 1090 can display the orientation distribution image on the display device 1100. The display control unit 1090 may also display the orientation distribution image on the frontal fundus image. Registration between the frontal fundus image and the orientation distribution image may be performed by the registration unit.

[0185] A non-limiting example of the operation of the ophthalmic apparatus 1400 will now be described. Fig. 12 shows one example of the operation of the ophthalmic apparatus 1400. Steps S11 to S15 may be performed in the same manner as steps S1 to S5 in Fig. 9, respectively.

[0186] In step S16, the interested blood vessel designation unit 1070 generates direction information (Doppler angle, suitability, etc.) for each blood vessel presented in the blood vessel map 1051 generated in step S15.

[0187] In step S17, the vessel of interest designation unit 1070 designates a vessel of interest from among the plurality of blood vessels presented in the vessel map 1051, based on the orientation information of each blood vessel generated in step S16. Note that the vessel of interest may be designated with reference to another selection criterion in addition to or instead of the orientation information. Information on the designated vessel of interest is sent to the scan control unit 1060.

[0188] In step S18, the scan control unit 1060 controls the scan unit 1010 to apply repeated scans for hemodynamic measurement (OCT blood flow measurement) to the blood vessel of interest designated in step S17.

[0189] The blood vessels of the fundus Ef corresponding to the designated blood vessels of interest are searched for and identified, for example, by referring to an infrared observation image (real-time moving image) of the fundus Ef. At this time, alignment between the infrared observation image and the blood vessel map 1051 may be performed by a process similar to the registration described above.

[0190] In step S18, the scan control unit 1060 may control the scan unit 1010 to execute a scan for newly determining a Doppler angle (the aforementioned supplemental scan), in addition to controlling the scan unit 1010 to execute a repetitive scan (the aforementioned main scan) on the blood vessel of interest. The OCT blood flow measurement data 1075 collected by the repetitive scan (and data collected by the supplemental scan) are sent to the hemodynamic information generation unit 1080.

[0191] In step S19, the hemodynamic information generation unit 1080 generates hemodynamic information 1085 in the blood vessel of interest specified by the blood vessel of interest designation unit 1070 based on the OCT blood flow measurement data 1075 collected by the repeated scan in step S17 (and data collected by the supplementary scan).

[0192] In some aspects, the hemodynamic information generation unit 1080 calculates the blood flow velocity in the vessel of interest based on the OCT blood flow measurement data 1075 collected from the vessel of interest in step S17 and the orientation information (Doppler angle) of the vessel of interest calculated in step S16.

[0193] In some other aspects, the blood flow dynamics information generation unit 1080 calculates the Doppler angle of the blood vessel of interest based on the data collected in the supplementary scan of step S17, and calculates the blood flow velocity in the blood vessel of interest based on this Doppler angle and the OCT blood flow measurement data 1075 collected in the main scan of step S17.

[0194] Furthermore, the hemodynamic information generating unit 1080 may execute a process of calculating the diameter of the blood vessel of interest and a process of calculating the blood flow volume based on the diameter and the blood flow velocity.

[0195] In step S20, the display control unit 1090 causes the display device 1100 to display the hemodynamic information (blood flow velocity, blood flow volume, blood vessel diameter, Doppler angle, etc.) generated in step S19. The display control unit 1090 may cause the display device 1100 to display any information (images, calculation results, analysis results, etc.) obtained in this operation example. For example, the hemodynamic information generation unit 1080 may apply evaluation processing to the Doppler angle to generate evaluation information, and the display control unit 1090 may further cause the display device 1100 to display this evaluation information.

[0196] The ophthalmic apparatus 1400 according to this embodiment has the following functions and effects in addition to the functions and effects of the ophthalmic apparatus 1000.

[0197] The ophthalmic apparatus 1400 can perform hemodynamic measurements of the fundus. Furthermore, the ophthalmic apparatus 1400 can automatically designate a blood vessel of interest based on a vascular map, or can assist in the task of designating a blood vessel of interest based on a vascular map. Additionally, the ophthalmic apparatus 1400 can automatically perform hemodynamic measurements of a designated blood vessel of interest using a vascular map. This facilitates and reduces the labor required to designate a position where hemodynamic measurements are to be applied, thereby improving the accuracy and precision of the task. Therefore, the ophthalmic apparatus 1400 of this embodiment facilitates easier, more labor-saving, and faster examinations, contributing to improved examination quality.

[0198] The ophthalmic device 1400 provides a novel method for generating fundus blood vessel orientation information by acquiring information on blood vessel course from an image obtained by fundus imaging. The orientation information generated by the ophthalmic device 1400 contributes to simplification and labor savings in the task of specifying a blood flow measurement position, and contributes to improved precision and accuracy of the task. Furthermore, the orientation information generated by the ophthalmic device 1400 provides the magnitude of the Doppler angle and its evaluation results, making it possible to predict an optimal blood flow measurement position.

[0199] The ophthalmologic apparatus 1400 can provide visual information showing various types of information such as a blood vessel map, an image of the fundus, a Doppler angle, and evaluation information, thereby allowing the user to grasp information about the subject's eye (fundus).

[0200] Fig. 13 shows the configuration of an ophthalmic apparatus 1500 according to one non-limiting embodiment. Elements of the ophthalmic apparatus 1500 that have the same names and the same reference numerals as elements of the ophthalmic apparatus 1400 in Fig. 11 may have the same configurations and functions as the corresponding elements of the ophthalmic apparatus 1400, unless otherwise specified. However, this does not exclude the adoption of modified means, equivalent means, or alternative means for the corresponding elements.

[0201] The ophthalmic apparatus 1500 includes the same elements as the ophthalmic apparatus 1400, such as a scanning unit 1010, a cross-sectional image generating unit 1020, a vascular region identifying unit 1030, a vascular region associating unit 1040, a vascular map generating unit 1050, a scan control unit 1060, and a blood flow dynamics information generating unit 1080. In addition to these, the ophthalmic apparatus 1500 also includes an observation image generating unit 1110, a movement control unit 1120, and a movement mechanism 1130.

[0202] The observation image generating unit 1110 is configured to generate an infrared observation image (real-time moving image) of the fundus oculi Ef. The ophthalmologic apparatus 1 of a non-limiting aspect can realize the function of the observation image generating unit 1110 using the fundus camera unit 2.

[0203] The moving mechanism 1130 is configured to move the scanning unit 1010. The ophthalmologic apparatus 1 of a non-limiting aspect can achieve the function of the moving mechanism 1130 by using the moving mechanism 150.

[0204] The movement control unit 1120 is configured to control the movement mechanism 1130. The movement control unit 1120 is realized by cooperation between hardware including circuits and movement control software. The ophthalmologic apparatus 1 of a non-limiting aspect can realize the function of the movement control unit 1120 using the control unit 210 (main control unit 211) and the data processing unit 230.

[0205] The vascular map 1051 generated by the vascular map generation unit 1050 is input to the movement control unit 1120. The infrared observation image generated by the observation image generation unit 1110 is input to the movement control unit 1120 in real time. The movement control unit 1120 compares the vascular map 1051 with the infrared observation image (a frame of a real-time moving image), calculates the deviation between the vascular map 1051 and the infrared observation image, and controls the movement mechanism 1130 based on this deviation. The calculation of the deviation between the vascular map 1051 and the infrared observation image may be performed, for example, using a method similar to the registration described above. The movement control unit 1120 controls the movement mechanism 1130 to cancel the calculated deviation. Specifically, the movement control unit 1120 calculates the deviation of each frame of the infrared observation image (or each frame obtained through thinning processing) relative to the vascular map 1051, and compares each sequentially calculated deviation with a predetermined threshold. The movement control unit 1120 repeats this series of processes until the deviation becomes smaller than the threshold value. This achieves alignment of the infrared observation image with the vascular map 1051, and realizes new alignment using the vascular map 1051. Note that, in parallel with the series of processes described here, alignment may be performed using the vascular map 1051, which is updated in real time, and the infrared observation image (real-time moving image), by repeatedly executing OCT scans and data processing for generating the vascular map 1051.

[0206] A non-limiting example of the operation of the ophthalmic apparatus 1500 will now be described. Fig. 14 shows one example of the operation of the ophthalmic apparatus 1500. Steps S31 to S35 may be executed in the same manner as steps S1 to S5 in Fig. 9, respectively.

[0207] In step S36, the ophthalmologic apparatus 1500 starts alignment. Specifically, the ophthalmologic apparatus 1500 starts generating an infrared observation image of the fundus oculi Ef by the observation image generating unit 1110, and starts the operation of the movement control unit 1120 and the movement mechanism 1130.

[0208] In step S37, the movement control unit 1120 calculates the displacement of the infrared observation image relative to the blood vessel map 1051 generated in step S35 and compares the calculated displacement with a threshold. This process is repeated until the displacement becomes smaller than the threshold (step S38: No). When the displacement of the infrared observation image relative to the blood vessel map 1051 becomes smaller than the threshold (step S38: Yes), the process proceeds to step S39.

[0209] In step S39, the scan control unit 1060 controls the scan unit 1010 to apply repeated scans for hemodynamic measurement (OCT blood flow measurement) to a blood vessel of interest in the fundus oculi Ef. The blood vessel of interest may be designated in the same manner as in the ophthalmologic apparatus 1400 (blood vessel of interest designation unit 1070) described above.

[0210] In step S40, the hemodynamic information generating unit 1080 generates hemodynamic information in the blood vessel of interest based on the OCT blood flow measurement data 1075 collected by the repeated scan in step S39.

[0211] In addition to the functions and effects of the ophthalmic device 1400, the ophthalmic device 1500 according to this embodiment can provide a novel alignment method that utilizes a vascular map that indicates the position of the fundus blood vessels obtained from an OCT image.

[0212] Fig. 15 shows the configuration of an ophthalmic apparatus 1600 according to one non-limiting embodiment. Elements of the ophthalmic apparatus 1600 that have the same names and symbols as elements of the ophthalmic apparatus 1400 in Fig. 11 may have the same configurations and functions as the corresponding elements of the ophthalmic apparatus 1400, unless otherwise specified. However, this does not exclude the adoption of modified, equivalent, or alternative means for the corresponding elements.

[0213] The ophthalmic apparatus 1600 includes the same elements as the ophthalmic apparatus 1400, such as a scanning unit 1010, a cross-sectional image generating unit 1020, a vascular region identifying unit 1030, a vascular region associating unit 1040, a vascular map generating unit 1050, a scan control unit 1060, and a blood flow dynamics information generating unit 1080. In addition to these elements, the ophthalmic apparatus 1500 includes a moving mechanism 1130, a moving control unit 1140, and a projection image generating unit 1150. The moving mechanism 1130 has the same configuration and function as the moving mechanism 1130 of the ophthalmic apparatus 1500 in FIG. 13 .

[0214] In this example, the vascular map 1051 is three-dimensional data such as the vascular map 1320 in Fig. 10C. The projection image generation unit 1150 generates a projection image by applying a projection in the A-scan direction (z direction) of an OCT scan of the fundus Ef to the vascular map 1051. The projection of this vascular map 1051 is not limited to a projection onto the vascular map 1051, but may also be a projection onto multiple cross-sectional images 1021 that are the original images of the vascular map 1051.

[0215] 10B , there is no need to provide the projection image generator 1150. Alternatively, there may be provided a projection image generator 1150 that is configured to operate when the vascular map 1051 is three-dimensional data and not operate when the vascular map 1051 is two-dimensional data.

[0216] The projection image generation unit 1150 is realized by cooperation between hardware including a circuit and projection image generation software. The ophthalmologic apparatus 1 of a non-limiting aspect can realize the function of the projection image generation unit 1150 using the data processing unit 230.

[0217] The movement control unit 1140 is configured to control the movement mechanism 1130. The movement control unit 1120 is realized by cooperation between hardware including circuits and movement control software. The ophthalmologic apparatus 1 of a non-limiting aspect can realize the function of the movement control unit 1120 using the control unit 210 (main control unit 211) and the data processing unit 230.

[0218] The projection image generated from the vascular map 1051 by the projection image generation unit 1150 is input to the movement control unit 1140. In this embodiment, the vascular map 1051 is repeatedly generated, and a projection image is generated from each vascular map 1051 (or each vascular map 1051 obtained through a thinning process).

[0219] A non-limiting example of the operation of the ophthalmic apparatus 1600 will be described. Fig. 16 shows one example of the operation of the ophthalmic apparatus 1600. Steps S51 to S55 may be executed in the same manner as steps S1 to S5 in Fig. 9, respectively. Steps S51 to S55 are executed repeatedly. As a result, a blood vessel map 1051 is sequentially generated. The time interval for generating the blood vessel map 1051, that is, the time interval for applying a scan to the fundus Ef, may be constant. The sequentially generated blood vessel maps 1051 are sequentially input to the projection image generation unit 1150.

[0220] In step S56, the projection image generation unit 1150 generates a projection image by applying projection to the sequentially input vascular map 1051. The projection images sequentially generated in response to the input vascular map 1051 are sequentially input to the movement control unit 1140.

[0221] In step S57, the movement control unit 1140 compares the two input projection images, calculates the deviation between these projection images, and compares the calculated deviation with a threshold. This process is repeated until the deviation becomes smaller than the threshold (step S58: No). When the deviation becomes smaller than the threshold (step S58: Yes), the processing procedure proceeds to step S59. The deviation becoming smaller than the threshold means that the movement of the subject's eye E is sufficiently small and the position of the subject's eye E is stable.

[0222] The processing in step S57 includes, for example, a step of detecting a connection area corresponding to a blood vessel from two consecutive projection images, a step of using the detected connection area as a landmark to calculate the position error between the two projection images, and a step of comparing this position error (deviation) with a threshold value.

[0223] In addition to evaluating the deviation between the projection images, alignment evaluation may be performed based on the distribution of landmarks in a single projection image. For example, the positions of feature points of the fundus oculi Ef can be estimated based on the distribution of landmarks in a single projection image. The scan in step S51 is a circle scan centered on the optic optic nerve center, and the landmarks in a single projection image are arranged on a circle. Therefore, the center of the circle formed by connecting these landmarks corresponds to the optic optic nerve center. The movement control unit 1140 can control the movement mechanism 1130 so that the center of the circle detected in this manner is located at the center position of the projection image. More generally, the movement control unit 1140 can control the movement mechanism 1130 so that the center of the detected circle is located at a predetermined position in the projection image.

[0224] In step S59, the scan control unit 1060 controls the scan unit 1010 to apply repeated scans for hemodynamic measurement (OCT blood flow measurement) to a blood vessel of interest in the fundus oculi Ef. The blood vessel of interest may be designated in the same manner as in the ophthalmologic apparatus 1400 (blood vessel of interest designation unit 1070) described above.

[0225] In step S60, the hemodynamic information generating unit 1080 generates hemodynamic information in the blood vessel of interest based on the OCT blood flow measurement data 1075 collected by the repeated scan in step S59.

[0226] In addition to the functions and effects of the ophthalmic device 1400, the ophthalmic device 1600 according to this embodiment can provide a novel alignment method that utilizes a vascular map that indicates the position of the fundus blood vessels obtained from an OCT image.

[0227] 17 shows the configuration of an ophthalmic apparatus 2000 according to one non-limiting embodiment. The ophthalmic apparatus 2000 includes a scanning unit 2010, a three-dimensional image generating unit 2020, a cross-sectional image extracting unit 2030, a vascular region identifying unit 2040, a vascular region associating unit 2050, and a vascular map generating unit 2060.

[0228] Any of the matters described or suggested in this disclosure, such as matters relating to the ophthalmic device 1000 in Figure 7, matters relating to the ophthalmic device 1400 in Figure 11, matters relating to the ophthalmic device 1500 in Figure 13, and matters relating to the ophthalmic device 1400 in Figure 15, can be combined with the ophthalmic device 2000 of this embodiment.

[0229] The scan unit 2010 is configured to collect data by applying an OCT scan to the fundus Ef of the subject's eye E, similar to the scan unit 1010 of the ophthalmic apparatus 1000 described above. In particular, the scan unit 2010 collects data by applying an OCT scan to a three-dimensional region of the fundus Ef. Non-limiting examples of this OCT scan include a raster scan and a Lissajous scan. The ophthalmic apparatus 1 of a non-limiting aspect can realize the function of the scan unit 2010 using the fundus camera unit 2 and the OCT unit 100.

[0230] The three-dimensional image generating unit 2020 is configured to generate a three-dimensional image of the fundus oculi Ef based on data collected from a three-dimensional region of the fundus oculi Ef by the scanning unit 2010. The generated three-dimensional image may be, for example, stack data or volume data. The three-dimensional image generating unit 2020 is realized by cooperation between hardware including a circuit and three-dimensional image generating software. The ophthalmologic apparatus 1 of a non-limiting aspect can realize the function of the three-dimensional image generating unit 2020 using the data processing unit 230 (image generating unit 220).

[0231] The cross-sectional image extraction unit 2030 extracts cross-sectional images from the three-dimensional image generated by the three-dimensional image generation unit 2020. In particular, the cross-sectional image extraction unit 2030 extracts multiple cross-sectional images corresponding to multiple cross sections of the fundus oculi Ef from the three-dimensional image. The multiple cross sections correspond to a scan pattern without a flyback. The scan pattern without a flyback may be, for example, any of the scan patterns described above regarding the scan unit 1010 of the ophthalmic apparatus 1000, such as the concentric circular scan shown in FIGS. 8A to 8C. The cross-sectional image extraction unit 2030 is realized by cooperation between hardware including a circuit and cross-sectional image extraction software. The ophthalmic apparatus 1 of a non-limiting aspect can realize the function of the cross-sectional image extraction unit 2030 using the data processing unit 230.

[0232] The vascular region identifying unit 2040 is configured to identify a plurality of vascular region groups corresponding to the plurality of cross-sectional images extracted from the three-dimensional image by the cross-sectional image extracting unit 2030 by detecting the vascular region groups from each of the plurality of cross-sectional images. The vascular region identifying unit 2040 has the same function as the vascular region identifying unit 1030 of the ophthalmic apparatus 1000 described above. The vascular region identifying unit 2040 is realized by cooperation between hardware including a circuit and vascular region identifying software. The ophthalmic apparatus 1 of a non-limiting aspect can realize the function of the vascular region identifying unit 2040 using the data processing unit 230 (vascular region identifying unit 231).

[0233] The vascular region associating unit 2050 is configured to associate vascular regions corresponding to different cross sections of the same blood vessel among a plurality of vascular region groups identified from a plurality of cross-sectional images by the vascular region identifying unit 2040. The vascular region associating unit 2050 has the same function as the vascular region associating unit 1040 of the ophthalmic apparatus 1000 described above. The vascular region associating unit 2050 is realized by cooperation between hardware including a circuit and vascular region associating software. The ophthalmic apparatus 1 of a non-limiting aspect can realize the function of the vascular region associating unit 2050 using the data processing unit 230.

[0234] The vascular map generating unit 2060 is configured to generate a vascular map showing the distribution of blood vessels based on the vascular region association result obtained by the vascular region associating unit 2050. The vascular map generating unit 2060 has the same functions as the vascular map generating unit 1050 of the ophthalmic apparatus 1000 described above. The vascular map generating unit 2060 is realized by cooperation between hardware including a circuit and vascular map generation software. The ophthalmic apparatus 1 of a non-limiting aspect can realize the functions of the vascular map generating unit 2060 using the data processing unit 230.

[0235] FIG. 18 shows an example of the operation of the ophthalmic apparatus 2000.

[0236] First, in step S71, the scanning unit 2010 applies OCT scanning to a three-dimensional region of the fundus oculi Ef of the subject's eye E to collect data. The collected data is sent to the three-dimensional image generating unit 2020.

[0237] In step S72, the three-dimensional image generating unit 2020 generates a three-dimensional image of the fundus oculi Ef based on the data collected from the three-dimensional region of the fundus oculi Ef in step S71. The generated three-dimensional image is sent to the cross-sectional image extracting unit 2030.

[0238] In step S73, the cross-sectional image extraction unit 2030 extracts, from the three-dimensional image generated in step S72, a plurality of cross-sectional images corresponding to a plurality of cross sections of the fundus oculi Ef corresponding to a scan pattern without flyback. For example, the cross-sectional image extraction unit 2030 extracts, from the three-dimensional image generated in step S72, two cross-sectional images corresponding to two concentric circle scans (concentric circle scans). The extracted cross-sectional images are sent to the vascular region identification unit 2040.

[0239] In step S74, the vascular region specifying unit 2040 detects vascular region groups from each of the multiple cross-sectional images extracted from the three-dimensional image in step S73. This specifies multiple vascular region groups corresponding to the multiple cross-sectional images, respectively. The specified multiple vascular region groups are sent to the vascular region associating unit 2050.

[0240] In step S75, the vascular region associating unit 2050 associates vascular regions corresponding to different cross sections of the same blood vessel among the plurality of vascular region groups identified in step S74. The result of this vascular region associating process is sent to the vascular region associating unit 2050.

[0241] In step S76, the vascular map generating unit 2060 generates a vascular map based on the vascular region association result obtained in step S75.

[0242] The ophthalmic apparatus 2000 capable of executing the processing procedure according to this operational example generates a 3D OCT image of the fundus of the subject's eye, extracts from the 3D OCT image multiple cross-sectional images corresponding to multiple cross sections corresponding to a scan pattern without flyback, identifies multiple vascular regions corresponding to the multiple cross-sectional images, and generates a vascular map by associating vascular regions corresponding to different cross sections of the same blood vessel. This vascular map can be used in preparatory steps (e.g., Doppler angle estimation, alignment, search for blood vessels of interest, etc.) in OCT blood flow measurement (fundus hemodynamic measurement). Therefore, the ophthalmic apparatus 2000 according to this embodiment contributes to improving the quality of OCT blood flow measurement.

[0243] As described above, various features can be combined with the ophthalmic apparatus 2000 of this embodiment. In particular, the features related to the ophthalmic apparatus 1000 in FIG. 7 , the features related to the ophthalmic apparatus 1400 in FIG. 11 , the features related to the ophthalmic apparatus 1500 in FIG. 13 , and the features related to the ophthalmic apparatus 1400 in FIG. 15 can be combined with the ophthalmic apparatus 2000. An ophthalmic apparatus obtained by such a combination exhibits the functions and effects of the combined features, and further exhibits synergistic functions and effects between the combined features and the ophthalmic apparatus 2000. Furthermore, an ophthalmic apparatus obtained by combining multiple features with the ophthalmic apparatus 2000 exhibits synergistic functions and effects between two or more of the multiple features, and synergistic functions and effects between two or more of the multiple features and the ophthalmic procedure 2000. Those skilled in the art will be able to understand these functions and effects from the present disclosure.

[0244] 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.

[0245] Some embodiments are methods for controlling an ophthalmic apparatus having a scanning unit and a processor that performs OCT scans. The method according to the present embodiment causes the processor to perform scan control, cross-sectional image generation processing, vascular region identification processing, vascular region association processing, and vascular map generation processing. The scan control controls the scanning unit to collect data by applying an OCT scan using a scan pattern without flyback to the fundus of the subject's eye. The cross-sectional image generation processing generates multiple cross-sectional images corresponding to multiple cross sections of the fundus based on data collected from the fundus under the scan control. The vascular region identification processing identifies multiple vascular region groups corresponding to the multiple cross-sectional images by detecting vascular region groups from each of the multiple cross-sectional images. The vascular region association processing associates vascular regions corresponding to different cross sections of the same blood vessel among multiple vascular region groups corresponding to the multiple cross sections. The vascular map generation processing generates a vascular map showing the distribution of blood vessels based on the results of the vascular region association processing. The method according to the present embodiment enables the ophthalmic apparatus to execute the procedures shown in FIG. 9 .

[0246] It is possible to configure a program that causes an ophthalmic device including a computer to execute the method according to this embodiment. It is also possible to create a computer-readable non-transitory recording medium on which such a program is recorded. 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. Any of the features described in this disclosure may be combined with the method, program, and recording medium according to this embodiment.

[0247] Some embodiments are methods for controlling an ophthalmic apparatus having a scanning unit and a processor that performs OCT scanning. The method according to the present embodiment causes the processor to perform scan control, a 3D image generation process, a cross-sectional image extraction process, a vascular region identification process, a vascular region correspondence process, and a vascular map generation process. The scan control controls the scanning unit to collect data by applying an OCT scan to a 3D region of the fundus of a subject's eye. The 3D image generation process generates a 3D image of the fundus based on data collected from the 3D region of the fundus under the scan control. The cross-sectional image extraction process extracts, from the 3D image generated by the 3D image generation process, multiple cross-sectional images corresponding to multiple cross sections of the fundus corresponding to a scan pattern without flyback. The vascular region identification process identifies multiple vascular region groups corresponding to the multiple cross-sectional images by detecting vascular region groups from each of the multiple cross-sectional images extracted from the 3D image. The vascular region correspondence process associates vascular regions corresponding to different cross sections of the same blood vessel among multiple vascular region groups corresponding to the multiple cross sections. The vascular map generation process generates a vascular map showing the distribution of blood vessels based on the results of the vascular region association process. The method according to this embodiment enables the ophthalmologic apparatus to execute the process steps shown in FIG. 18 described above.

[0248] It is possible to configure a program that causes an ophthalmic device including a computer to execute the method according to this embodiment. It is also possible to create a computer-readable non-transitory recording medium on which such a program is recorded. The method, program, and recording medium according to this embodiment can be combined with any of the features described in this disclosure.

[0249] 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.

[0250] 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.

[0251] 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.

[0252] [1] An ophthalmologic device comprising: a scanning unit that applies an optical coherence tomography scan using a scan pattern that does not involve flyback to the fundus of a subject's eye to collect data; a cross-sectional image generating unit that generates a plurality of cross-sectional images corresponding to a plurality of cross sections of the fundus based on the data collected by the scanning unit; a vascular region identifying unit that identifies a plurality of vascular region groups corresponding to the plurality of cross-sectional images by detecting a vascular region group from each of the plurality of cross-sectional images; a vascular region matching unit that matches vascular regions corresponding to different cross sections of the same blood vessel among the plurality of vascular region groups; and a vascular map generating unit that generates a vascular map showing the distribution of blood vessels based on the results of the matching.

[0253] [2] The ophthalmic apparatus according to the above item 1, wherein the scan pattern includes a plurality of patterns each of which does not involve flyback.

[0254] [3] The ophthalmologic device of claim 2, wherein the scan pattern includes a concentric pattern that is a combination of the plurality of patterns arranged concentrically, the plurality of cross sections of the fundus include a plurality of concentric cross sections that respectively correspond to the plurality of patterns, the scanning unit applies an optical coherence tomography scan using the concentric pattern to the fundus to collect data, and the cross-sectional image generating unit generates the plurality of cross-sectional images that respectively correspond to the plurality of concentric cross sections based on the data collected by the optical coherence tomography scan using the concentric pattern.

[0255] [4] The ophthalmologic device of claim 3, wherein the concentric pattern includes a concentric circular pattern that is a combination of a plurality of concentrically arranged circular patterns, the plurality of concentric cross sections include a plurality of concentrically arranged cylindrical side surfaces that respectively correspond to the plurality of circular patterns, the scanning unit applies an optical coherence tomography scan using the concentric circular pattern to the fundus to collect data, and the cross-sectional image generating unit generates the plurality of cross-sectional images that respectively correspond to the plurality of cylindrical side surfaces based on the data collected by the optical coherence tomography scan using the concentric circular pattern.

[0256] [5] An ophthalmologic device comprising: a scanning unit that applies optical coherence tomography scanning to a three-dimensional region of the fundus of a subject's eye to collect data; a three-dimensional image generating unit that generates a three-dimensional image of the fundus based on the data collected by the scanning unit; a cross-sectional image extracting unit that extracts from the three-dimensional image a plurality of cross-sectional images corresponding to a plurality of cross sections of the fundus corresponding to a scan pattern without flyback; a vascular region identifying unit that identifies a plurality of vascular region groups corresponding to the plurality of cross-sectional images by detecting a vascular region group from each of the plurality of cross-sectional images; a vascular region matching unit that matches vascular regions corresponding to different cross sections of the same blood vessel among the plurality of vascular region groups; and a vascular map generating unit that generates a vascular map showing the distribution of blood vessels based on the results of the matching.

[0257] [6] The ophthalmic apparatus according to the above item 5, wherein the scan pattern includes a plurality of patterns each of which does not involve flyback.

[0258] [7] The ophthalmologic device of claim 6, wherein the scan pattern includes a concentric pattern that is a combination of the plurality of patterns arranged concentrically, the plurality of cross sections of the fundus include a plurality of concentric cross sections that respectively correspond to the plurality of patterns, and the cross-sectional image extraction unit extracts the plurality of cross-sectional images that respectively correspond to the plurality of concentric cross sections from the three-dimensional image.

[0259] [8] The ophthalmologic device of claim 7, wherein the concentric pattern includes a concentric circular pattern that is a combination of a plurality of concentrically arranged circular patterns, the plurality of concentric cross sections include a plurality of concentrically arranged cylindrical side surfaces that respectively correspond to the plurality of circular patterns, and the cross-sectional image extraction unit extracts the plurality of cross-sectional images that respectively correspond to the plurality of cylindrical side surfaces from the three-dimensional image.

[0260] [9] The ophthalmologic device according to any one of 1 to 8 above, wherein the vascular region specifying unit generates a plurality of projection images corresponding to the plurality of cross-sectional images by applying a projection in the A-scan direction of the optical coherence tomography scan to each of the plurality of cross-sectional images, and detects a vascular region group from the corresponding cross-sectional image for each of the plurality of projection images based on a luminance distribution in the projection image.

[0261]

[10] Any of the ophthalmologic devices described above in 1 to 9, further comprising: a scan control unit that controls the scanning unit to apply repeated scans to a pre-specified blood vessel of interest in the fundus; and a blood flow dynamics information generating unit that generates blood flow dynamics information in the blood vessel of interest based on data collected by the repeated scans.

[0262]

[11] The ophthalmologic apparatus according to the above item 10, further comprising a blood vessel of interest designation unit that analyzes the blood vessel map and designates the blood vessel of interest.

[0263]

[12] The ophthalmologic device according to claim 10 or 11, wherein the plurality of cross-sectional images include a first cross-sectional image and a second cross-sectional image, the vascular region identification unit detects a first vascular region from the first cross-sectional image, and detects a second vascular region from the second cross-sectional image, the vascular region correspondence unit associates the first vascular region and the second vascular region with each other as different cross-sections of the blood vessel of interest, and the blood flow dynamics information generation unit generates first position information indicating the position of the first vascular region, and generates second position information indicating the position of the second vascular region, and generates Doppler angle information indicating the magnitude of the Doppler angle in optical coherence tomography blood flow measurement for the blood vessel of interest based on the first position information and the second position information.

[0264]

[13] The ophthalmologic apparatus according to the above item 12, wherein the blood flow dynamics information generating unit generates the blood flow dynamics information in the blood vessel of interest based on the data collected by the repeated scans and the Doppler angle information.

[0265]

[14] The ophthalmologic apparatus according to claim 12 or 13, wherein the blood flow dynamics information generating unit generates evaluation information by applying an evaluation process to the magnitude of the Doppler angle, and further comprises a display control unit that displays the evaluation information on a display device.

[0266]

[15] Any of the ophthalmologic devices of claims 10 to 14, further comprising: an observation image generating unit that generates an infrared observation image of the fundus; a movement mechanism that moves the scan unit; and a movement control unit that controls the movement mechanism based on a deviation of the infrared observation image relative to the vascular map, wherein the scan control unit executes the control of the scan unit when the deviation becomes smaller than a preset threshold value.

[0267]

[16] The ophthalmologic device of any of claims 10 to 14, further comprising: a vascular map generating unit that generates a new vascular map based on new data newly collected from the fundus by the scanning unit; a projection image generating unit that applies a projection in the A-scan direction of the optical coherence tomography scan to the vascular map to generate a first projection image, and applies the projection to the new vascular map to generate a second projection image; a movement mechanism that moves the scanning unit; and a movement control unit that controls the movement mechanism based on the deviation between the first projection image and the second projection image.

[0268]

[17] A method for controlling an ophthalmologic apparatus having a scanning unit that performs an optical coherence tomography scan and a processor, comprising causing the processor to perform the following: scan control that controls the scanning unit to apply an optical coherence tomography scan using a scan pattern that does not involve flyback to the fundus of the subject's eye to collect data; cross-sectional image generation processing that generates a plurality of cross-sectional images corresponding to a plurality of cross sections of the fundus based on the data; vascular region identification processing that identifies a plurality of vascular region groups corresponding to the plurality of cross-sectional images by detecting vascular region groups from each of the plurality of cross-sectional images; vascular region correspondence processing that associates vascular regions corresponding to different cross sections of the same blood vessel among the plurality of vascular region groups; and vascular map generation processing that generates a vascular map showing the distribution of blood vessels based on the results of the correspondence.

[0269]

[18] A method for controlling an ophthalmologic apparatus having a scanning unit that performs an optical coherence tomography scan and a processor, comprising causing the processor to perform the following: scan control that controls the scanning unit to apply an optical coherence tomography scan to a three-dimensional region of the fundus of a subject's eye to collect data; a three-dimensional image generation process that generates a three-dimensional image of the fundus based on the data; a cross-sectional image extraction process that extracts from the three-dimensional image a plurality of cross-sectional images that respectively correspond to a plurality of cross-sections of the fundus corresponding to a scan pattern that does not involve flyback; a vascular region identification process that identifies a plurality of vascular region groups that respectively correspond to the plurality of cross-sectional images by detecting a vascular region group from each of the plurality of cross-sectional images; a vascular region correspondence process that associates vascular regions that correspond to different cross-sections of the same blood vessel among the plurality of vascular region groups; and a vascular map generation process that generates a vascular map showing the distribution of blood vessels based on the results of the correspondence.

[0270]

[19] A program for causing a computer to execute the method of 17 or 18 above.

[0271]

[20] A computer-readable non-transitory recording medium on which the program of 19 above is recorded.

[0272] 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.

[0273] 1000 Ophthalmic apparatus 1010 Scan unit 1020 Cross-sectional image generating unit 1030 Blood vessel region identifying unit 1040 Blood vessel region matching unit 1050 Blood vessel map generating unit

Claims

1. An ophthalmic device comprising: a scanning unit that applies an optical coherence tomography scan using a scan pattern without flyback to the fundus of a subject's eye to collect data; a cross-sectional image generating unit that generates a plurality of cross-sectional images corresponding to a plurality of cross sections of the fundus based on the data collected by the scanning unit; a vascular region identifying unit that identifies a plurality of vascular region groups corresponding to the plurality of cross-sectional images by detecting vascular region groups from each of the plurality of cross-sectional images; a vascular region matching unit that matches vascular regions corresponding to different cross sections of the same blood vessel among the plurality of vascular region groups; and a vascular map generating unit that generates a vascular map showing the distribution of blood vessels based on the results of the matching.

2. The ophthalmic device according to claim 1, wherein the scan pattern includes a plurality of patterns each of which does not involve a flyback.

3. The ophthalmologic device of claim 2, wherein the scan pattern includes a concentric pattern that is a combination of the plurality of patterns arranged concentrically, the plurality of cross sections of the fundus include a plurality of concentric cross sections that respectively correspond to the plurality of patterns, the scanning unit applies an optical coherence tomography scan using the concentric pattern to the fundus to collect data, and the cross-sectional image generating unit generates the plurality of cross-sectional images that respectively correspond to the plurality of concentric cross sections based on the data collected by the optical coherence tomography scan using the concentric pattern.

4. The ophthalmologic device of claim 3, wherein the concentric pattern includes a concentric circular pattern which is a combination of a plurality of concentrically arranged circular patterns, the plurality of concentric cross sections include a plurality of concentrically arranged cylindrical side surfaces which respectively correspond to the plurality of circular patterns, the scanning unit applies an optical coherence tomography scan using the concentric circular pattern to the fundus to collect data, and the cross-sectional image generating unit generates the plurality of cross-sectional images which respectively correspond to the plurality of cylindrical side surfaces based on the data collected by the optical coherence tomography scan using the concentric circular pattern.

5. An ophthalmologic device comprising: a scanning unit that applies optical coherence tomography scanning to collect data on a three-dimensional region of the fundus of the subject's eye; a three-dimensional image generating unit that generates a three-dimensional image of the fundus based on the data collected by the scanning unit; a cross-sectional image extracting unit that extracts from the three-dimensional image a plurality of cross-sectional images corresponding to a plurality of cross sections of the fundus corresponding to a scan pattern without flyback; a vascular region identifying unit that identifies a plurality of vascular region groups corresponding to each of the plurality of cross-sectional images by detecting a vascular region group from each of the plurality of cross-sectional images; a vascular region matching unit that matches vascular regions corresponding to different cross sections of the same blood vessel among the plurality of vascular region groups; and a vascular map generating unit that generates a vascular map showing the distribution of blood vessels based on the results of the matching.

6. The ophthalmic device according to claim 5, wherein the scan pattern includes a plurality of patterns each of which does not involve a flyback.

7. The ophthalmologic device of claim 6, wherein the scan pattern includes a concentric pattern that is a combination of the plurality of patterns arranged concentrically, the plurality of cross sections of the fundus include a plurality of concentric cross sections that respectively correspond to the plurality of patterns, and the cross section image extraction unit extracts the plurality of cross section images that respectively correspond to the plurality of concentric cross sections from the three-dimensional image.

8. The ophthalmologic device of claim 7, wherein the concentric pattern includes a concentric circular pattern that is a combination of a plurality of concentrically arranged circular patterns, the plurality of concentric cross sections include a plurality of concentrically arranged cylindrical side surfaces that respectively correspond to the plurality of circular patterns, and the cross-sectional image extraction unit extracts the plurality of cross-sectional images that respectively correspond to the plurality of cylindrical side surfaces from the three-dimensional image.

9. An ophthalmic device according to any one of claims 1 to 8, wherein the vascular region identification unit generates a plurality of projection images corresponding to the plurality of cross-sectional images by applying a projection in the A-scan direction of the optical coherence tomography scan to each of the plurality of cross-sectional images, and detects a group of vascular regions from the corresponding cross-sectional image for each of the plurality of projection images based on the luminance distribution in the projection image.

10. An ophthalmologic device according to any one of claims 1 to 9, further comprising: a scan control unit that controls the scanning unit to apply repeated scans to a pre-specified blood vessel of interest in the fundus; and a blood flow dynamics information generating unit that generates blood flow dynamics information in the blood vessel of interest based on data collected by the repeated scans.

11. The ophthalmologic apparatus according to claim 10, further comprising a blood vessel of interest designation unit that analyzes the blood vessel map and designates the blood vessel of interest.

12. An ophthalmologic device according to claim 10 or 11, wherein the plurality of cross-sectional images include a first cross-sectional image and a second cross-sectional image, the vascular region identification unit detects a first vascular region from the first cross-sectional image and detects a second vascular region from the second cross-sectional image, the vascular region correspondence unit associates the first vascular region and the second vascular region with each other as different cross-sections of the blood vessel of interest, and the blood flow dynamics information generation unit generates first position information indicating the position of the first vascular region and generates second position information indicating the position of the second vascular region, and generates Doppler angle information indicating the magnitude of the Doppler angle in optical coherence tomography blood flow measurement for the blood vessel of interest based on the first position information and the second position information.

13. The ophthalmologic apparatus according to claim 12, wherein the blood flow dynamics information generating unit generates the blood flow dynamics information in the blood vessel of interest based on the data collected by the repeated scans and the Doppler angle information.

14. An ophthalmologic apparatus according to claim 12 or 13, wherein the blood flow dynamics information generating unit generates evaluation information by applying evaluation processing to the magnitude of the Doppler angle, and further comprises a display control unit that displays the evaluation information on a display device.

15. An ophthalmologic device according to any one of claims 10 to 14, further comprising: an observation image generating unit that generates an infrared observation image of the fundus; a movement mechanism that moves the scanning unit; and a movement control unit that controls the movement mechanism based on a deviation of the infrared observation image relative to the vascular map, wherein the scanning control unit executes the control of the scanning unit when the deviation becomes smaller than a preset threshold value.

16. The ophthalmologic device of any one of claims 10 to 14, further comprising: a vascular map generation unit that generates a new vascular map based on new data newly collected from the fundus by the scanning unit; a projection image generation unit that applies a projection in the A-scan direction of the optical coherence tomography scan to the vascular map to generate a first projection image, and applies the projection to the new vascular map to generate a second projection image; a movement mechanism that moves the scanning unit; and a movement control unit that controls the movement mechanism based on the deviation between the first projection image and the second projection image.

17. A method for controlling an ophthalmic apparatus having a scanning unit that performs an optical coherence tomography scan and a processor, comprising causing the processor to perform the following: scan control that controls the scanning unit to apply an optical coherence tomography scan using a scan pattern that does not involve flyback to the fundus of the subject's eye to collect data; cross-sectional image generation processing that generates a plurality of cross-sectional images corresponding to a plurality of cross sections of the fundus based on the data; vascular region identification processing that identifies a plurality of vascular region groups corresponding to the plurality of cross-sectional images by detecting vascular region groups from each of the plurality of cross-sectional images; vascular region correspondence processing that associates vascular regions corresponding to different cross sections of the same blood vessel among the plurality of vascular region groups; and vascular map generation processing that generates a vascular map showing the distribution of blood vessels based on the results of the correspondence.

18. A method for controlling an ophthalmologic apparatus having a scanning unit that performs optical coherence tomography scanning and a processor, comprising causing the processor to perform the following: scan control for controlling the scanning unit to apply optical coherence tomography scanning to a three-dimensional region of the fundus of a subject's eye to collect data; three-dimensional image generation processing for generating a three-dimensional image of the fundus based on the data; cross-sectional image extraction processing for extracting from the three-dimensional image a plurality of cross-sectional images corresponding to a plurality of cross sections of the fundus corresponding to a scan pattern without flyback; vascular region identification processing for detecting a vascular region group from each of the plurality of cross-sectional images and identifying a plurality of vascular region groups corresponding to the plurality of cross-sectional images; vascular region correspondence processing for matching vascular regions corresponding to different cross sections of the same blood vessel among the plurality of vascular region groups; and vascular map generation processing for generating a vascular map showing the distribution of blood vessels based on the results of the correspondence.

19. A program for causing a computer to execute the method of claim 17 or 18.

20. A computer-readable non-transitory recording medium on which the program of claim 19 is recorded.

Images