Fundus imaging apparatus and fundus imaging method

Abstract

To provide a fundus photographing device and a fundus photographing program capable of easily determining re-photographing of a panoramic image.SOLUTION: The fundus imaging apparatus includes an OCT optical system for acquiring an OCT signal of the fundus by utilizing interference between measurement light irradiated to the fundus of a subject's eye and reference light, and acquiring a plurality of OCT signals by controlling the OCT optical system to scan the measurement light at different timings at the same position of the fundus; And an output control unit that displays the enface motion contrast image on a display unit, in which the imaging control unit acquires a panoramic image which is the enface motion contrast image of the wide range by aligning the enface motion contrast images of the unit regions for a plurality of positions different from the same position, and the output control unit displays the panoramic image such that a state of the alignment is distinguishable.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a fundus imaging device and a fundus imaging program. [Background technology]

[0002] A fundus imaging device can be used to obtain motion contrast images that show tissue movement. In the cited document 1, in order to photograph a wide area of ​​the fundus, multiple frontal motion contrast data are obtained and then subjected to panoramic synthesis processing to obtain a panoramic image. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-47113 Summary of the Invention [Problem to be solved by the invention]

[0004] In some hospitals, motion contrast data captured by a fundus imaging device is transferred to a separate analyzer, which then processes and creates a panoramic image. In this case, the user cannot immediately check whether the panoramic image is appropriate after capturing the image of the subject's eye, making it difficult to decide whether to capture it again. In particular, when the fundus imaging device and the analyzer are in separate rooms, recapturing the image can be time-consuming, requiring the subject to return.

[0005] The present disclosure has been made in response to the above-described problems of the conventional technology, and has as its technical object to provide a fundus photography device and a fundus photography program that can easily determine whether a panoramic image needs to be re-photographed. [Means for solving the problem]

[0006] A fundus imaging device according to a first aspect of the present disclosure is a fundus imaging device for photographing the fundus of a test eye, and comprises: an OCT optical system for acquiring an OCT signal of the fundus by utilizing interference between measurement light and reference light irradiated onto the fundus of the test eye; an imaging control means for controlling the OCT optical system to scan the measurement light at different times at the same position on the fundus to acquire multiple OCT signals and acquire a front motion contrast image based on the multiple OCT signals; and an output control means for displaying the front motion contrast image on a display means, wherein the imaging control means aligns front motion contrast images of unit areas at multiple positions different from the same position to acquire a panoramic image which is a front motion contrast image of a wide area, and the output control means displays the panoramic image in a manner that allows the alignment state to be distinguished.

[0007] A fundus photography program according to a first aspect of the present disclosure is a fundus photography program executed by a fundus photography device that photographs the fundus of a test eye, and that includes an OCT optical system for acquiring an OCT signal of the fundus by utilizing interference between measurement light and reference light irradiated onto the fundus of the test eye. The fundus photography program causes the fundus photography device to execute an imaging control step of controlling the OCT optical system to scan the measurement light at different times at the same position on the fundus to acquire the multiple OCT signals and acquire a front motion contrast image based on the multiple OCT signals, and an output control step of displaying the motion contrast image on a display means. The imaging control step aligns front motion contrast images of unit areas at multiple positions different from the same position to acquire a panoramic image, which is a front motion contrast image of a wide area, and the output control step displays the panoramic image in a manner that allows the alignment state to be distinguished. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing the configuration of a fundus imaging device 1. FIG. [Figure 2] FIG. 1 is a diagram illustrating a configuration of an OCT optical system 100. [Figure 3] This is an example of a fixation lamp 82. [Figure 4] FIG. 2 is a diagram illustrating a unit area and a scanning line of a measurement light. [Figure 5] 10 is an example of a setting screen 40 displayed on the display unit 21. [Figure 6] 10 is an example of a confirmation screen 51 displayed on the display unit 21. [Figure 7] 10 is an example of a confirmation screen 52 displayed on the display unit 21. [Figure 8] This is an example of a state in which a displacement occurs in the panoramic image 132. [Figure 9] This is an example of a state in which a displacement occurs in the panoramic image 132. DETAILED DESCRIPTION OF THE INVENTION

[0009] [overview] An embodiment of a fundus imaging device according to the present disclosure will be described. Each embodiment may be applied to part or all of the other embodiments. For example, the items grouped in < > below may be used independently or in conjunction with each other.

[0010] The fundus imaging device of this embodiment has the configuration of a so-called optical coherence tomography (OCT). The fundus imaging device also functions as an information analysis device that analyzes and processes OCT data of tissue (for example, the fundus) photographed using an OCT optical system described below, and generates an OCT image (for example, a tomographic image, a motion contrast image, etc.) that is the analysis result of the OCT data and displays it on a display unit.

[0011] The fundus imaging device may have a configuration different from the optical coherence tomography device in addition to the configuration of the optical coherence tomography device. For example, it may have the configuration of a so-called scanning laser ophthalmoscope (SLO). For example, it may have the configuration of a so-called fundus camera.

[0012] The fundus imaging device may be an integrated device that incorporates an optical system and control means (for example, imaging control means and output control means) in the device main body and includes display means in the device main body. Further, the fundus imaging device may be a separable device including a device main body incorporating an optical system 100 and a personal computer (hereinafter referred to as a PC) connected to the device main body by wire or wirelessly. In this case, both the control means of the device main body and the control means of the PC may function as imaging control means and output control means. Also, in this case, the display means of the PC may be used as the display means of the device.

[0013] Of course, when the fundus imaging device is a separable device, the control means of the device main body may function independently as the control unit means of the PC. Also, when a commercially available PC is used as a part of the fundus imaging device 1, at least a part of an ophthalmic imaging program may be installed in the commercially available PC.

[0014] Note that in the fundus imaging device of the present embodiment, acquisition of motion contrast data of a unit area, panorama synthesis processing by alignment of the motion contrast data, and display of a panorama image are consistently performed (details of each will be described later). Therefore, the user of the fundus imaging device can easily determine the suitability of the motion contrast data in panorama imaging and, if necessary, can immediately re-image the motion contrast data of a predetermined unit area.

[0015] <OCT optical system> The fundus imaging device of this embodiment includes an OCT optical system (e.g., an OCT optical system 100). The OCT optical system is an optical system for acquiring an OCT signal of the fundus by utilizing interference between measurement light and reference light irradiated onto the subject's eye. For example, the OCT optical system may be basically configured as a time-domain OCT (TD-OCT). Alternatively, for example, the OCT optical system may be basically configured as a Fourier-domain OCT optical system. Examples of Fourier-domain OCT optical systems that can be used include spectral-domain OCT (SD-OCT) and swept-spectrum OCT (SS-OCT). In the case of SD-OCT, a low-coherence light source (broadband light source) is used as the measurement light source, and a spectroscopic optical system (spectrometer) that separates the interference light into individual frequency components (individual wavelength components) is provided near the light-receiving element in the optical path of the interference light. In the case of SS-OCT, a wavelength-scanning light source (tunable light source) that changes the emission wavelength at high speed over time is used as the measurement light source.

[0016] The technology of this embodiment can also be applied to intensity OCT for detecting the reflection intensity of the test eye, OCT angiography (e.g., Doppler OCT) for detecting motion contrast data of the test eye, polarization-sensitive OCT (PS-OCT), multifunction OCT that combines intensity OCT and PS-OCT, etc.

[0017] <Photographing optical system> The fundus imaging device of this embodiment includes an imaging optical system (e.g., a front observation optical system 200). The imaging optical system captures a front image of the fundus of the subject's eye. For example, the imaging optical system may be an SLO optical system having an SLO configuration. The SLO optical system may irradiate illumination light onto the fundus of the subject's eye and capture a front image of the fundus based on return light of the illumination light from the fundus. Also, for example, the imaging optical system may be a fundus camera optical system having a fundus camera configuration. The fundus camera optical system may form an irradiation area and a light-receiving area of ​​the imaging light on the pupil of the subject's eye, and capture a front image of the fundus by projecting and receiving the imaging light through the irradiation area and the light-receiving area. Also, for example, the imaging optical system may be an infrared imaging optical system. The infrared imaging optical system may collectively irradiate a two-dimensional imaging range in the tissue of the subject's eye E with infrared light and capture a front image of the fundus without scanning with measurement light.

[0018] <Fixation optical system> The fundus imaging device of this embodiment includes a fixation optical system (e.g., a fixation target presenting optical system 300). The fixation optical system projects a fixation target onto the subject's eye to change the line of sight of the subject's eye. The fixation optical system may be capable of switching the presentation position of the fixation target relative to the subject's eye.

[0019] The fixation optical system may include a visible light source (fixation light). For example, if the fixation optical system includes one fixation light, the fixation target presentation position can be switched by moving the fixation light. Also, for example, if the fixation optical system includes multiple fixation lights, the fixation target presentation position can be switched by controlling the lighting of the fixation lights. The fixation optical system may include a display means for displaying the fixation target. In this case, the fixation target presentation position can be switched by changing the display position of the fixation target.

[0020] <Photography control means> The fundus imaging device of this embodiment includes an imaging control means (e.g., a control unit 10). The imaging control means controls the OCT optical system to scan the measurement light at different times over the same position on the fundus, thereby acquiring multiple OCT signals and acquiring a front motion contrast image based on the multiple OCT signals. For example, the front motion contrast image is an image that shows tissue movement (e.g., blood flow through blood vessels in the tissue, lymph flow within the tissue, etc.).

[0021] The imaging control means acquires frontal motion contrast images of unit regions for a plurality of different positions on the fundus by processing the OCT signals from the respective units. For example, the imaging control means may acquire the frontal motion contrast images by applying a method of calculating a phase difference of complex OCT signals, a method of calculating a vector difference of complex OCT signals, a method of multiplying the phase difference and the vector difference of complex OCT signals, or the like.

[0022] The imaging control unit may acquire a front motion contrast image of the unit area by scanning the measurement light of the OCT optical system based on a front image of the fundus captured by the imaging optical system. In this case, the front motion contrast image can also be acquired by applying the various methods described above.

[0023] The imaging control means aligns the front motion contrast images of the unit area at a plurality of positions different from the same position described above, thereby obtaining a panoramic image, which is a front motion contrast image of a wide area. For example, the imaging control means may align the positions of the plurality of motion contrast data based on information on the position where the measurement light is scanned (i.e., information on the position of the unit area), tissue connections, matching processing with a predetermined reference image, etc.

[0024] The photographing control means may re-acquire the frontal motion contrast image of the selected unit area based on an operation instruction to select the frontal motion contrast image of the unit area from the panoramic image, thereby allowing the user to quickly re-photograph only the frontal motion contrast image of the specified unit area.

[0025] The imaging control means may control the fixation optical system and, based on the detection result of the detection means (described later), switch the presentation position of the fixation target around the imaging optical axis of the OCT optical system to reacquire a front motion contrast image of the unit area. For example, the imaging control means may switch the presentation position of the fixation target to adjust the front motion contrast image of a predetermined unit area so that it is acquired at the position of the imaging optical axis of the OCT optical system or at a position close to the imaging optical axis of the OCT optical system. More specifically, the imaging control means may adjust the center position of the predetermined unit area so that it is approximately located at the position of the imaging optical axis of the OCT optical system. This allows the unit area that needs to be re-imaged to be located at the position of the imaging optical axis or at a position close to the imaging optical axis, where the influence of distortion of the measurement light (e.g., the influence of optical errors due to changes in the incident angle of the measurement light) is smaller. Therefore, imaging can be performed satisfactorily.

[0026] <Output control means> The fundus imaging device of this embodiment includes output control means (e.g., control unit 10). The output control means displays the motion contrast image on display means (e.g., display unit 21). The output control means also displays a panoramic image of the motion contrast images of unit areas corresponding to a plurality of different positions on the fundus, allowing the user to distinguish the alignment state. This allows the user to easily determine whether the motion contrast data is suitable for panoramic imaging and quickly re-image the motion contrast data of a specified unit area.

[0027] The output control means may cause the output means to output notification information regarding misalignment, which is used to distinguish the alignment status of each motion contrast image. For example, the output means may be at least one of a display means, an audio generating means, a printing means, a storage means, etc., as appropriate. This allows the user to more easily determine whether the motion contrast data is suitable for panoramic photography using the notification information. Therefore, it is possible to efficiently determine whether to re-photograph the motion contrast data of a specified unit area.

[0028] For example, the output control means may output, as notification information, information for notifying the presence or absence of a misalignment in the alignment of the motion contrast image. In this case, the output control means may output notification information indicating that a misalignment exists or does not exist based on a result of detection of the misalignment by a detection means described below. In this case, the output control means may output notification information indicating that a misalignment exists or does not exist based on whether the result of detection of the misalignment by the detection means falls within a predetermined tolerance range.

[0029] For example, the output control means may output, as notification information, information for notifying the degree of misalignment with respect to the alignment of the motion contrast image. In this case, the notification information may be output by indicating the amount of misalignment as a direct numerical value based on the result of detection of the misalignment by the detection means. Also, in this case, the notification information may be output by indicating the amount of misalignment as evaluation information that indirectly represents the amount of misalignment based on the result of detection of the misalignment by the detection means described below. As an example, the evaluation information may be information for dividing the amount of misalignment into stages based on a predetermined criterion.

[0030] The output control means may control the display means to display the notification information. The output control means may also control the sound generation means (for example, a speaker) to cause the sound generation means to generate the notification information by sound. The output control means may also control the printing means to cause the printing means to print the notification information. The output control means may also control the external storage means to transmit the notification information to the external storage means. Of course, the output control means may execute a combination of these controls, or may execute a different control from these controls.

[0031] <Detection method> The fundus imaging device of this embodiment includes a detection unit (e.g., a control unit 10). The detection unit detects the amount of deviation relative to the alignment of the motion contrast image of the unit area. For example, the detection unit may detect the amount of deviation by a comparison process (e.g., calculation of a difference) between information on the position of the unit area specified by the user and information on the position where the measurement light is actually scanned (information on the position of the unit area actually obtained). Also, for example, the detection unit may detect the amount of deviation by a comparison process (e.g., pattern matching) between a predetermined reference image and the motion contrast image of the unit area actually obtained.

[0032] The present disclosure is not limited to the devices described in the present embodiment. For example, terminal control software (programs) that perform the functions of the above embodiments may be supplied to a device or system via a network or various storage media, and a control device (e.g., a CPU) of the device or system may read and execute the program.

[0033] [Example] A typical embodiment of the present disclosure will be described below. In this example, a case where motion contrast data is acquired from the fundus tissue of a subject's eye in a fundus imaging device (optical coherence tomography device) 1 is illustrated. For example, motion contrast data can be acquired by acquiring multiple OCT signals at different times from the same position on the fundus tissue and processing the multiple OCT signals.

[0034] <Overall configuration of the device> 1 is a schematic diagram showing the configuration of a fundus imaging device 1. The fundus imaging device 1 of this embodiment includes a control unit 10, a display unit 21, an operation unit 22, an OCT optical system 100, a front observation optical system 200, and a fixation target presenting optical system 300. For example, the fundus imaging device 1 may be an integrated device in which these components and optical systems are provided in the device body.

[0035] The control unit 10 controls the operation of the fundus imaging device 1. The control unit 10 includes a CPU (processor) 11, a ROM 12, a RAM 13, and a non-volatile memory (NVM) 14. The CPU 11 controls each unit in the fundus imaging device 1. The ROM 12 stores various programs, initial values, etc. The RAM 13 temporarily stores various information. The non-volatile memory 14 is a non-transitory storage medium that can retain its contents even when the power supply is cut off. For example, the non-volatile memory 14 may be a hard disk drive, a flash ROM, a removable USB memory, etc.

[0036] In this embodiment, the CPU 11 acquires an OCT signal by controlling the OCT optical system 100. Further, the CPU 11 analyzes and processes the OCT signal to acquire OCT image data based on the OCT signal, and generates an OCT image (for example, a tomographic image, a motion contrast image, etc.) obtained by imaging the OCT image data. Further, the CPU 11 causes the display unit 21 to display the OCT image. In this embodiment, the CPU 11 acquires SLO frontal image data by controlling the frontal observation optical system 200, and generates an SLO frontal image obtained by imaging the SLO frontal image data. Further, the CPU 11 causes the display unit 21 to display the SLO frontal image. In this embodiment, the CPU 11 causes the fixation target presentation optical system 300 to present a fixation target to the subject eye E.

[0037] The display unit 21 is a display mounted on the apparatus main body. The display unit 21 may function as an operation unit 22. For example, the display unit 21 may also serve as the operation unit 22 by having a touch panel function.

[0038] The operation unit 22 outputs an operation signal corresponding to an operation instruction input via the operation unit 22 to the control unit 10. For example, at least one of a mouse, a joystick, a keyboard, a touch panel, etc. can be used for the operation unit 22. Note that, for example, a microphone or a camera can also be used for the operation unit 22. In this case, an operation signal may be output to the control unit 100 by detecting the examiner's voice or gesture, etc.

[0039] <OO00163><OCT optical system> FIG. 2 is a diagram showing the configuration of the OCT optical system 100. The OCT optical system 100 includes a measurement light source 102, a coupler (optical splitter) 104, a measurement optical system 106, a scanning unit (optical scanner) 108, a reference optical system 110, a light receiving element (detector) 120, etc. For example, the measurement light source 102, the measurement optical system 106, the reference optical system 130, and the light receiving element 120 are connected to the coupler 104 by optical fibers.

[0040] The OCT optical system 100 splits light emitted from a measurement light source 102 into measurement light (sample light) and reference light using a coupler 104. The OCT optical system 100 guides the measurement light to the tissue (here, the fundus Ef) of the subject's eye E using a measurement optical system 106, and guides the reference light to a reference optical system 110. The OCT optical system 100 causes a light receiving element 120 to receive interference light formed by combining the measurement light reflected by the tissue and the reference light.

[0041] The measurement light source 102 emits low-coherence light used as measurement light and reference light. The light emitted from the measurement light source 102 is split into measurement light and reference light by a coupler 104. The measurement light passes through an optical fiber and is then emitted into air. The measurement light emitted into air is focused on tissue via an optical scanner 108 or the like of the measurement optical system 106. The measurement light reflected by the tissue is returned to the optical fiber along the same optical path.

[0042] The optical scanner 108 scans the measurement light on the tissue in two dimensions (X and Y directions). For example, the optical scanner 108 is disposed at a position approximately conjugate with the pupil of the subject's eye E. As an example, the optical scanner 108 includes two galvanometer mirrors. The reflection angles of the galvanometer mirrors are arbitrarily adjusted by the driving mechanism 50. As a result, the reflection direction of the measurement light changes, and the measurement light is irradiated at any position on the tissue. In other words, the irradiation position of the measurement light on the tissue is changed by the optical scanner 108. It goes without saying that the configuration of the optical scanner 108 can be changed. For example, a polygon mirror, a resonant scanner, an acousto-optical device (AOM), etc. may be adopted as the optical scanner 108.

[0043] The reference optical system 110 generates reference light to be combined with the measurement light reflected by the tissue. The reference optical system 110 may be a Michelson type or a Mach-Zehnder type. The reference optical system 110 reflects the light incident from the coupler 104 using a reflective optical system (e.g., a reference mirror) to return the light to the coupler 104 and guide it to the light-receiving element 120. As another example, the reference optical system 130 may transmit the light incident from the coupler 104 without reflecting it, and guide it to the light-receiving element 120.

[0044] The reference optical system 110 can change the optical path length difference between the measurement light and the reference light by moving optical components in the optical path. In this embodiment, the optical path length difference is changed by moving the reference mirror in the optical axis direction. A configuration for changing the optical path length difference may be provided in the optical path of the measurement optical system 106.

[0045] The light receiving element 120 detects an interference signal resulting from the combination of the measurement light and the reference light. For example, the light receiving element 120 has a spectroscopic optical system (spectrometer) that separates the interference signal into individual wavelength components (individual frequency components). For example, the spectrometer is made up of a diffraction grating and a line sensor. The interference signal detected by the light receiving element 120 is output to the control unit 10.

[0046] For example, in Fourier domain OCT, the spectral intensity (spectral interference signal) of the interference light is detected by the light receiving element 120, and a complex OCT signal is acquired by Fourier transforming the spectral intensity data. A depth profile (A-scan signal) within a predetermined range is acquired by calculating the absolute value of the amplitude of the complex OCT signal. A B-scan signal is acquired by arranging depth profiles at each measurement point scanned with the measurement light by the optical scanner 108. For example, OCT image data (tomographic image data) is acquired based on the B-scan signal. Three-dimensional OCT image data (three-dimensional tomographic image data) may be acquired by scanning the tissue with the measurement light in two dimensions and arranging the B-scan signals for each scan line. Enface OCT image data, in which the tissue is viewed from the front direction along the optical axis of the measurement light, may be acquired from the three-dimensional OCT image data.

[0047] Furthermore, motion contrast data is acquired from two or more OCT signals acquired at different times (different times) from the same region of tissue. That is, motion contrast data is acquired by performing analysis processing on multiple complex OCT signals. For example, two-dimensional motion contrast data is acquired by scanning the measurement light along one scanning line and arranging the motion contrast data at each scanning position. Also, three-dimensional motion contrast data may be acquired by scanning the measurement light in two-dimensional directions (i.e., XY directions along the optical axis of the measurement light). Furthermore, enface motion contrast data when the tissue is viewed from the front may be acquired from the three-dimensional motion contrast data.

[0048] In this embodiment, the measurement light is scanned multiple times along multiple scan lines within a predetermined unit area to acquire three-dimensional motion contrast data for the unit area. In other words, the unit area is the unit for acquiring three-dimensional motion contrast data. For example, the unit area may be an area of ​​3 mm x 3 mm, 4.5 mm x 4.5 mm, etc. Furthermore, three-dimensional motion contrast data from multiple unit areas is acquired so that they overlap or are adjacent to each other, and these data are combined to acquire three-dimensional motion contrast data for a wide area. For example, the wide area may be an area of ​​6 mm x 6 mm, 9 mm x 9 mm, 12 mm x 9 mm, etc. Details of how motion contrast data is acquired for unit areas and wide areas will be described later.

[0049] <Front observation optical system> The front observation optical system 200 acquires front image data of the tissue of the subject's eye. As an example, the front observation optical system 200 of this embodiment includes an optical scanner that scans measurement light (e.g., infrared light) emitted from a light source on the tissue in two-dimensional directions (X and Y directions), and a light-receiving element that receives reflected light through a confocal aperture located at a position approximately conjugate with the tissue. In other words, the front observation optical system 200 of this embodiment has the configuration of a so-called ophthalmic scanning laser ophthalmoscope (SLO) to acquire SLO front image data.

[0050] <Fixation target presentation optical system> The fixation target presenting optical system 300 presents a fixation target to the subject's eye E and guides the line of sight of the subject's eye E. For example, the fixation target projection optical system 300 has a fixation lamp 82. For example, the fixation lamp 82 is a visible light source that emits visible light. Note that visible light is light that is visible to the subject's eye, and includes light in a wavelength band that is visible to the subject's eye in the infrared range, such as light with a wavelength of 800 nm to 850 nm.

[0051] 3 shows an example of the fixation lamp 82. In this embodiment, a plurality of fixation lamps 82a to 82u are arranged as the fixation lamp 82. The fixation lamp 82a is arranged on the optical axis L. The fixation lamps 82b to 82e are arranged around the fixation lamp 82a and close to the optical axis L. The fixation lamps 82f to 82u are arranged around the fixation lamps 82b to 82e and far from the optical axis L. By changing the presentation position of the fixation target (fixation lamp) with respect to the subject's eye E, the line of sight of the subject's eye E is changed, and the photographing position of the fundus is changed.

[0052] <Method for obtaining motion contrast data in a unit area> A method for acquiring motion contrast data of a unit region will be described. In this embodiment, the control unit 10 (CPU 11) sets an arbitrary unit region 5 for the tissue based on operation instructions from the operation unit 22, etc. The control unit 10 also acquires OCT signals (interference signals) of at least two frames with different measurement times by scanning the measurement light of the OCT optical system 100 multiple times at the same position within the unit region 5 of the tissue. The control unit 10 also performs arithmetic processing on the acquired OCT signals to acquire motion contrast data.

[0053] Note that the arithmetic processing of OCT signals includes a method of calculating the phase difference of complex OCT signals, a method of calculating the vector difference of complex OCT signals, and a method of multiplying the phase difference of complex OCT signals by the vector difference, etc. Here, we will use as an example a method of performing processing related to the Doppler phase difference method and processing related to the vector difference method, and then multiplying the phase difference by the vector difference.

[0054] FIG. 4 is a diagram illustrating a unit area and a scanning line of the measurement light. In this embodiment, as shown in FIG. 4, a unit area 5 is set as a unit for acquiring motion contrast data. The unit area 5 illustrated in FIG. 4 is a two-dimensional area that is a square when viewed from the Z direction (front direction). However, the shape of the unit area 5 can be changed. For example, the shape of the unit area 5 may be rectangular, circular, elliptical, or other shapes. When three-dimensional motion contrast data or front motion contrast data is acquired from the unit area 5, the unit area 5 becomes a two-dimensional area.

[0055] The control unit 10 scans the measurement light multiple times along each of the multiple scanning lines S (S1 to Sn) in the unit region 5. As a result, the same number of OCT signals as the number of scans are acquired from the same position where each scanning line S is arranged. Each scanning line S illustrated in FIG. 4 is linear extending in the X direction, and multiple scanning lines S of equal length are arranged in the Y direction, so that the measurement light scans the entire unit region 5. However, the shape and arrangement of the scanning lines S can also be changed. For example, the linear scanning line S may extend in the Y direction or may extend in an oblique direction. The lengths of the individual scanning lines S may be different. Multiple scanning lines S may intersect. Non-linear scanning lines (e.g., circular, curved, bent, etc.) may also be used.

[0056] The OCT signals are acquired from each of a plurality of measurement points P on each scanning line S. For example, when the scanning speed of the measurement light on the scanning line S is constant and the light receiving element 120 (see FIG. 2) of the OCT optical system 100 detects received light signals at constant intervals, the intervals between the measurement points P on the scanning line S are constant, as shown in FIG. 4. Note that the measurement points P shown in FIG. 4 are schematic, and the size, intervals, number, etc. of the measurement points P in FIG. 4 differ from the actual ones.

[0057] Increasing the number of measurement points P on the scanning line S increases the number of pixels in the motion contrast image (image generated from motion contrast data) acquired from the unit area 5. However, to acquire good motion contrast data, it is desirable to scan the same position with the measurement light multiple times at appropriate time intervals (e.g., every 2.5 ms to 5 ms). Furthermore, the speed at which the light receiving element 120 can detect the received light signal (i.e., the number of times the light receiving signal can be detected per unit time) is limited for each light receiving element 120. Furthermore, the performance and memory capacity of the optical scanner 108 may limit the number of measurement points P on the scanning line S. In this embodiment, due to the influence of these various factors, an upper limit is set for the number of measurement points P on the scanning line S. As an example, in this embodiment, the upper limit for the number of measurement points P on the scanning line S is 256. When the unit area 5 is a square, for example, if the number of measurement points P on the scanning line S is 256 and the 256 scanning lines S are arranged in a direction intersecting the scanning direction within the unit area 5, motion contrast data can be obtained at each of the "256 vertical × 256 horizontal" measurement points. The upper limit number may be set appropriately depending on the speed at which the light receiving element 120 can detect the light receiving signal, etc.

[0058] It is also possible to set the number of measurement points P on the scanning line S to be less than the upper limit. For example, in this embodiment, the number of measurement points P on the scanning line S can be set to 128. In this case, the control unit 10 can acquire OCT signals from each of the two scanning lines S at appropriate time intervals by scanning the measurement light once on each of the two scanning lines S, and then scanning the measurement light on these two scanning lines S again.

[0059] The control unit 10 performs a Fourier transform on the OCT signal acquired by the OCT optical system 100. As a result, a complex OCT signal is obtained. The complex OCT signal includes a real component and an imaginary component. Next, the control unit 10 calculates a phase difference from multiple complex OCT signals acquired at different times for the same position. The control unit 10 removes random phase differences that exist in areas with a low S / N ratio (signal-to-noise ratio). As a result, reflected signals from highly reflective areas are removed, making it easier to distinguish between signals from highly reflective areas and signals from blood vessels, etc. In this embodiment, one frame from which the phase difference is calculated is acquired. Note that if there are multiple frames from which the phase difference is calculated, the control unit 10 may perform averaging processing on the signals from the multiple frames to reduce noise.

[0060] Next, the control unit 10 calculates the vector difference of the complex OCT signals. For example, the complex OCT signal can be expressed as a vector on a complex plane. By calculating the vector difference of multiple signals acquired at the same position at different times, contrast image data of the subject's eye E is generated. When imaging the vector difference, imaging may be performed based on, for example, phase information in addition to the magnitude of the difference. In this embodiment, one frame in which the vector difference is calculated is acquired. If there are multiple frames in which the vector difference is calculated, the control unit may perform averaging processing on the signals of the multiple frames.

[0061] In this embodiment, the control unit 10 uses the calculation result of the phase difference as a filter for the calculation result of the vector difference. "Using as a filter" means, for example, weighting a certain numerical value. For example, the control unit 10 weights the calculation result of the vector difference by multiplying the calculation result of the phase difference. As a result, the vector difference in the portion with a small phase difference is weakened, and the vector difference in the portion with a large phase difference is strengthened. By multiplying the calculation result of the vector difference by the calculation result of the phase difference, the effects of the disadvantages of each calculation method are reduced, and better motion contrast data is obtained.

[0062] The control unit 10 can acquire three-dimensional motion contrast data by performing the above-described arithmetic processing on the OCT signals acquired from each of the multiple scan lines S. The control unit 10 can also acquire frontal motion contrast data from the three-dimensional motion contrast data. The frontal motion contrast data may be used, for example, as a pseudo-angiographic image. The motion contrast data may be data of a completed image, or may be values ​​used to calculate the brightness of each pixel of the image.

[0063] <Method for acquiring wide-area motion contrast data> A method for acquiring wide-area motion contrast data will be described with reference to Figures 5 to 7. Wide-area motion contrast data can also be called panoramic motion contrast data.

[0064] When an operation instruction to start the panoramic mode is input from the operation unit 22, the control unit 10 (CPU 11) of this embodiment executes panoramic mode processing in accordance with the fundus photography program. The control unit 10 controls the front observation optical system 200 to acquire SLO front image data of the fundus Ef. The control unit 10 also controls the display unit 21 to display a setting screen 40 for setting the wide area 6 and unit area 5 in the motion contrast data of the fundus Ef.

[0065] FIG. 5 shows an example of a setting screen 40 displayed on the display unit 21. The setting screen 40 includes a front image display unit 8, a wide area designation unit 66, and a unit area designation unit 55. The front image display unit 8 displays an SLO front image 7 generated from the SLO front image data. The control unit 10 displays the SLO front image 7 as a still image, but it may also display it as a moving image. The wide area designation unit 66 displays multiple sizes of the wide area 6 as selection candidates. The unit area designation unit 55 displays multiple sizes of the unit area 5 as selection candidates. Note that the size candidates for the wide area 6 and the unit area 5 are predetermined. For example, the size candidates for the wide area 6 are three types: "6 mm x 6 mm," "9 mm x 9 mm," and "12 mm x 9 mm." For example, the size candidates for the unit area 5 are two types: "3 mm x 3 mm" and "4.5 mm x 4.5 mm."

[0066] In this embodiment, a case is illustrated in which a large area 6 of "6 mm x 6 mm" and unit areas 5A to 5D of "3 mm x 3 mm" are specified via the operation unit 22. For example, the sizes of unit areas 5 that can be specified are predetermined depending on the size of the large area 6, and when a large area 6 of "6 mm x 6 mm" is specified, only a unit area 5A of "3 mm x 3 mm" can be specified. Based on an operation instruction from the operation unit 22, the control unit 10 arranges the four unit areas 5A to 5D within the large area 6 so that the edges of adjacent unit areas coincide with each other.

[0067] The control unit 10 can move the positions of the wide area 6 and the multiple unit areas 5 on the SLO front image 7 in accordance with an operation instruction input via the operation unit 22. In this embodiment, the user can move the wide area 6 and the multiple unit areas 5 arranged within the wide area 6 to desired positions on the SLO front image 7 by operating the operation unit 22. In this embodiment, four unit areas 5 are arranged without any gaps throughout the entire range of the wide area 6.

[0068] After completing the setting of the unit region 5 and the wide region 6, the control unit 10 fixes the position of the fixation target relative to the subject's eye E. For example, the control unit 10 turns on the fixation light 82a (see FIG. 3). This can reduce the influence of distortion of the measurement light, etc., compared to changing the position of the fixation target to acquire OCT signals for multiple unit regions 5. Furthermore, the control unit 10 acquires motion contrast data for the wide region 6 by sequentially acquiring motion contrast data for the unit regions 5A to 5D as described above.

[0069] First, the control unit 10 starts tracking of the unit region 5 using the SLO en face image data. The control unit 10 repeatedly acquires SLO en face image data over a range wider than the region selected as the wide region 6. The control unit 10 tracks the position of the unit region 5 on the fundus oculi Ef (i.e., the position where the measurement light is scanned) by using the SLO en face image data. Specifically, the control unit 10 uses SLO en face image data acquired before starting to acquire motion contrast data as a reference and compares it with the SLO en face image data acquired in real time. The control unit 10 then detects a positional deviation from the two SLO en face image data by image processing or the like, thereby detecting a change in the relative position between the OCT optical system 100 and the fundus oculi Ef. The control unit 10 performs tracking of the unit region 5 by controlling the scanning position of the measurement light by the optical scanner 108 so that the detected positional change is canceled out. Note that the control unit 10 performs tracking processing of the SLO en face image data both while scanning the measurement light within each unit region 5 and while changing the unit region 5 where the measurement light is scanned. Therefore, the measurement light is scanned appropriately over each of the four unit areas 5A to 5D.

[0070] The control unit 10 controls the optical scanner 108 to scan the unit area 5A to be imaged first with the measurement light, thereby acquiring multiple OCT signals for the unit area 5A. The control unit 10 also acquires motion contrast data for the unit area 5A by performing arithmetic processing on the multiple OCT signals acquired from the unit area 5A. The control unit 10 then generates at least one of a front motion contrast image and a three-dimensional motion contrast image from the acquired motion contrast data, and displays the image on the display unit 21. In this embodiment, the control unit 10 generates a front motion contrast image and displays it on the display unit 21.

[0071] FIG. 6 shows an example of a confirmation screen 51 displayed on the display unit 21. The confirmation screen 51 includes a motion contrast image display area 71, an “OK” button 31, and a “RETRY” button 32. The motion contrast image display area 71 displays a motion contrast image (here, a frontal motion contrast image 131) generated from the motion contrast data. The user checks the frontal motion contrast image 131 and operates either the “OK” button 31 or the “RETRY” button 32 depending on whether or not the frontal motion contrast image 131 is acceptable. For example, when the “OK” button 31 is operated, the control unit 10, in response to an operation instruction from the “OK” button 31, advances the panorama mode processing to capturing the second unit area 5B. For example, when the “RETRY” button 32 is operated, the control unit 10, in response to an operation instruction from the “RETRY” button 32, re-captures the unit area 5A and regenerates the frontal motion contrast image 131, displaying it on the display unit 21.

[0072] In this embodiment, the above process is repeated to acquire motion contrast data and front motion contrast images 131 for the four unit regions 5A to 5D captured first to fourth. The user can acquire the front motion contrast images 131 for each of the unit regions 5A to 5D while appropriately checking that the front motion contrast images 131 for the unit regions 5A to 5D are appropriate. The CPU 11 may interrupt the data acquisition process for the unit regions 5 in response to a specific operation instruction from the user. The CPU 11 may also skip the data acquisition process for some of the unit regions 5 in response to a specific operation instruction from the user.

[0073] When the control unit 10 has completed capturing images of all the unit regions 5, it panorama-composes the motion contrast data of the unit regions 5A to 5D. For example, the control unit 10 may panorama-compose multiple pieces of motion contrast data according to information on the position where the measurement light was scanned (i.e., information on the position of the unit region 5). Alternatively, for example, the control unit 10 may perform image processing on each motion contrast image and panorama-compose multiple pieces of motion contrast data based on tissue connections (e.g., blood vessel connections). Alternatively, for example, the control unit 10 may match each motion contrast image with a reference image (e.g., the SLO front image 7 captured by the front observation optical system 200) and panorama-compose multiple pieces of motion contrast data based on the matching results. Of course, the control unit 10 may use various methods to panorama-compose multiple pieces of motion contrast data. As a result, motion contrast data wider than each unit region 5 (here, front motion contrast data corresponding to the wide region 6) is acquired. The control unit 10 generates a front motion contrast image from the acquired front motion contrast data corresponding to the wide region 6 and displays the image on the display unit 21.

[0074] FIG. 7 shows an example of a confirmation screen 52 displayed on the display unit 21. The confirmation screen 51 has a motion contrast image display area 72, an "OK" button 33, and a "RETRY" button 34. A front motion contrast image (hereinafter, "panoramic image") 132 corresponding to the wide area 6 is displayed on the motion contrast image display area 72 as a result of panoramic composition. The user checks the panoramic image 132 and operates either the "OK" button 33 or the "RETRY" button 34 depending on whether or not to accept the panoramic image 132. For example, when the "OK" button 33 is operated, the control unit 10 ends the panoramic mode process in response to an operation instruction from the "OK" button 33. For example, when the "RETRY" button 34 is operated, the control unit 10 may re-image a specific unit area 5 in response to an operation instruction from the "RETRY" button 34.

[0075] In the above example, the motion contrast data of the four unit regions 5A to 5D are appropriately acquired and combined to display a panoramic image 132 of the wide region 6 in which the unit regions 5 are arranged without gaps, as illustrated in FIG. 6 . However, the tracking process may be delayed due to the subject's eye movement, and motion contrast data may be acquired while the scanning position of the measurement light remains displaced relative to the unit region 5. That is, motion contrast data of a region other than the unit region 5 specified by the user may be acquired. Furthermore, when the shape of the subject's eye or the like causes distortion in the measurement light, motion contrast data of a region other than the unit region 5 specified by the user may be acquired. In such a case, for example, a misalignment may occur in at least a part of the panoramic image 132 of the wide region 6.

[0076] 8 and 9 show examples of a state in which a misalignment occurs in the panoramic image 132. For example, if the control unit 10 acquires motion contrast data for a unit region 5A as motion contrast data for a region 5A' different from the unit region 5A, the edges of the motion contrast image for the unit region 5A' in the motion contrast image display unit 72 will not coincide with the edges of the other motion contrast images, as illustrated in FIG. 8. For example, if the background of the motion contrast image display unit 72 is gray, the panoramic image 132 will be superimposed on the motion contrast image display unit 72, causing gray to appear in the gap between the motion contrast image for the unit region 5A' and the other motion contrast images. The user can easily determine whether a misalignment occurs in the panoramic image 132 based on the presence or absence of such a gap. Furthermore, by acquiring and displaying the panoramic image 132 based on the unit region 5, the user can immediately determine whether the panoramic image 132 is appropriate and immediately recapture it if necessary. Therefore, re-imaging can be performed more smoothly than, for example, transmitting the motion contrast data of the unit area 5 to a PC in a separate room equipped with analysis software and converting it into a panoramic image and displaying it on the PC.

[0077] Furthermore, the control unit 10 can display the gap between the motion contrast image of the unit region 5A' and other motion contrast images in a color different from the background to more clearly indicate whether there is a misalignment. For example, the control unit 10 can detect the amount of misalignment using position information for each unit region and convert the amount of misalignment into the number of pixels, thereby displaying the gap between the motion contrast image of the unit region 5A' and other motion contrast images in red, for example, as illustrated in FIG. 9. Note that although the motion contrast image of the unit region 5A' is separated from the other motion contrast images in FIG. 9, at least a portion of the motion contrast images may overlap. In this case, the control unit 10 can display the overlapping area between the motion contrast image of the unit region 5A' and other motion contrast images in red, for example, based on the amount of misalignment of the unit region. This makes it easier for the user to notice whether there is a misalignment, even if the gap or overlap between the motion contrast images is slight.

[0078] If the user decides to re-photograph the unit area 5A', the user touches (i.e., selects) the front motion contrast image of the unit area 5A' from the panoramic image 132. Based on an operational instruction from the display unit 21, the control unit 10 highlights the image so that it is recognizable that the motion contrast image of the unit area 5A' has been selected. As an example, only the front motion contrast image of the unit area 5A' may be surrounded by an outer frame, or the front motion contrast image of the unit area 5A' may be made to blink. Furthermore, the user confirms the selection of the motion contrast image of the unit area 5A' and operates the "RETRY" button 34. The control unit 10 starts re-photographing the unit area 5A in response to the operational instruction from the "RETRY" button 34.

[0079] As described above, the fundus imaging device of this embodiment acquires multiple OCT signals and front motion contrast images based on the multiple OCT signals by scanning the same position on the fundus of the subject's eye with measurement light at different times. Furthermore, by aligning front motion contrast images of unit areas at multiple positions different from the same position, a panoramic image, which is a front motion contrast image of a wide area, is acquired and displayed so that the alignment status can be distinguished. This allows the user to easily determine the appropriateness of panoramic capture of the front motion contrast image based on the alignment status. As a result, a front motion contrast image of a specified unit area can be immediately recaptured. In other words, a recapture step can be incorporated before the panoramic mode processing for the subject's eye is completed, allowing for smooth recapture.

[0080] The fundus imaging device of this embodiment also outputs notification information regarding misalignment, which is used to distinguish the alignment status of the frontal motion contrast image of the unit area. This allows the user to more easily determine whether the frontal motion contrast data is suitable for panoramic imaging using the notification information. Therefore, the user can efficiently determine whether to re-capture the frontal motion contrast data of a specific unit area.

[0081] Furthermore, the fundus imaging device of this embodiment reacquires a frontal motion contrast image of the selected unit area based on an operation instruction to select the frontal motion contrast image of the selected unit area from the panoramic image, thereby allowing the user to quickly recapture only the frontal motion contrast image of the specified unit area.

[0082] <Example of transformation> The technology disclosed in this embodiment is merely an example, and therefore, it is possible to change at least a part of the technology exemplified in this embodiment.

[0083] In this embodiment, OCT front image data and OCT front images are acquired for multiple unit areas, and a wide-area OCT front image is generated by panoramic synthesis of the individual OCT front images, and the wide-area OCT front image may be displayed on the display unit 21.

[0084] In this embodiment, the multiple unit regions 5A to 5D do not completely overlap, and therefore the state of the measurement light, etc., may change for each unit region 5A to 5D, and the brightness, etc., of each motion contrast image may differ for each unit region 5. Therefore, the control unit 10 may adjust the gradation value, etc., of each motion contrast image to reduce the difference in brightness.

[0085] In this embodiment, a front motion contrast image (panoramic image 132) for a specific layer position may be displayed. For example, in this case, preset buttons for selecting a specific layer position (for example, inner layer, outer layer, choroid, etc.) may be provided in advance on the confirmation screen 51. The control unit 10 may switch to the panoramic image 132 of the layer selected by the user in response to an operation instruction from the preset button. Also, for example, in this case, an OCT image (here, a tomographic image) and a layer boundary based on segmentation processing of the OCT image may be displayed on the confirmation screen 51. The user may then be able to move the layer boundary by a drag operation or the like. The control unit 10 may display the panoramic image 132 corresponding to the position of the layer boundary.

[0086] In this embodiment, the user checks the panoramic image 132 and, if necessary, operates the "RETRY" button 34 to re-photograph the predetermined unit area 5. The control unit 10 starts acquiring motion contrast data for the predetermined unit area 5 in response to an operation instruction from the "RETRY" button 34. At this time, the presentation position of the fixation target presented to the subject's eye may be changed between when the motion contrast data for each unit area is first captured and when only the motion contrast data for the predetermined unit area is subsequently re-photographed. Note that the control unit 10 can change the presentation position of the fixation target based on an operation instruction from the user, or can automatically change the presentation position of the fixation target based on the motion contrast data before the predetermined unit area 5 is re-photographed.

[0087] The user may grasp the degree and direction of the deviation from the motion contrast image of the predetermined unit region 5 before re-capturing, and manually change the fixation light by operating the operation unit 22. For example, as shown in FIGS. 8 and 9, if the motion contrast image of the unit region 5A' is significantly deviated to the upper left relative to the other motion contrast images in the panoramic image 132 captured by the control unit 10 with the fixation light 82a turned on, the user changes the fixation light to 82k. In this case, the control unit 10 acquires motion contrast data of the unit region 5 again with the fixation light 82k turned on for the subject's eye E.

[0088] When the control unit 10 automatically changes the fixation light, the control unit 10 may use information on the positions of the unit region 5A' and the unit regions 5B to 5D to detect the direction and amount of displacement of the unit region 5A', and select a predetermined fixation light based on the direction and amount of displacement. Then, the control unit 10 again acquires motion contrast data of the unit region 5 with the predetermined fixation light turned on for the subject's eye E.

[0089] The fundus imaging device of this embodiment acquires a front motion contrast image of the unit area again by switching the presentation position of the fixation target based on the amount of misalignment in the front motion contrast image of the unit area. More specifically, the front motion contrast image of the unit area is acquired again by switching the presentation position of the fixation target around the imaging optical axis of the OCT optical system. This allows the unit area that needs to be re-imaged to be located at the position of the imaging optical axis or a position close to the imaging optical axis, where the influence of distortion of the measurement light (e.g., the influence of optical errors due to changes in the incident angle of the measurement light) is smaller. Therefore, imaging can be performed satisfactorily.

[0090] In this embodiment, the gap between the motion contrast image of the unit area 5A' and another motion contrast image is displayed in a color different from the background to notify the user that a misalignment has occurred in the panoramic image 132. However, it is also possible to notify the user of the presence or absence of a misalignment using a method different from that of this embodiment.

[0091] For example, the control unit 10 may notify the user that the motion contrast data of the unit region 5A' is misaligned by displaying the amount of misalignment calculated using the position information of the unit region 5A' and the unit regions 5B to 5D as a numerical value on the confirmation screen 52. Furthermore, for example, the control unit 10 may notify the user that the motion contrast data of the unit region 5A' is misaligned by displaying a pop-up message or the like. Furthermore, for example, the control unit 10 may notify the user that the motion contrast data of the unit region 5A' is misaligned by highlighting the motion contrast image of the unit region 5A', for example by surrounding it.

[0092] Furthermore, the control unit 10 may acquire evaluation information based on a preset evaluation level for the deviation of the motion contrast data of the unit region 5A' and display the evaluation information on the display unit 21. For example, the evaluation level may be indicated by a symbol or a numerical value. For example, the evaluation information may indicate the reliability of the panoramic image 132. As an example, the control unit 10 may divide the amount of deviation into three levels: less than 1 pixel, 1 pixel or more but less than 3 pixels, and 3 pixels or more, and evaluate each case with an evaluation symbol "A," "B," or "C." The evaluation symbol "A" may be defined as a range in which deviation is acceptable without requiring the panoramic image 132 to be recaptured (in other words, usable for diagnosis). The evaluation symbol "B" may be defined as a range in which recapture of the panoramic image 132 is recommended. The evaluation symbol "C" may be defined as a range in which recapture of the panoramic image 132 is recommended. In this way, the display of the evaluation information may assist the user in determining whether or not to recapture the panoramic image 132. [Explanation of symbols]

[0093] 1 Fundus photography device 5 unit area 6. Wide range of areas 10 Control Unit 11 CPU 14 Non-volatile memory 21 Display section 22 Control section 100 OCT optics 102 Measurement light source 108 Optical Scanner 120 Photodetector 200 Front observation optical system 300 Fixation target presentation optical system

Claims

1. A fundus photographing device for photographing the fundus of a subject's eye, an OCT optical system for acquiring an OCT signal of the fundus by utilizing interference between a measurement light and a reference light irradiated onto the fundus of the subject's eye; an imaging control means for controlling the OCT optical system to scan the measurement light at different timings at the same position on the fundus to acquire a plurality of OCT signals and to acquire a front motion contrast image based on the plurality of OCT signals; an output control means for displaying the front motion contrast image on a display means; Equipped with the imaging control means aligns frontal motion contrast images of unit areas at a plurality of positions different from the same position to obtain a panoramic image which is a frontal motion contrast image of a wide area; the output control means displays the panoramic image in a manner that enables the alignment state to be distinguished; A fundus photographing device characterized by:

2. The fundus photographing apparatus according to claim 1, The fundus photographing apparatus is characterized in that the output control means controls the output means to output notification information for distinguishing the alignment state, the notification information relating to a deviation in the alignment.

3. The fundus photography device is characterized in that the photography control means re-acquires a frontal motion contrast image of the selected unit area based on an operational instruction to select a frontal motion contrast image of the unit area from the panoramic image.

4. In the fundus photographing apparatus according to any one of claims 1 to 3, a fixation optical system capable of switching the presentation position of a fixation target for changing the line of sight of the subject's eye; a detection means for detecting the amount of misalignment of the alignment; Equipped with The fundus photography device is characterized in that the photography control means controls the fixation optical system and, based on the detection result of the detection means, switches the presentation position of the fixation target around the photography optical axis of the OCT optical system, thereby re-acquiring a front motion contrast image of the unit area.

5. In the fundus photographing apparatus according to any one of claims 1 to 4, an imaging optical system that captures a front image of the fundus of the subject's eye, The fundus imaging device is characterized in that the imaging control means acquires a front motion contrast image of the unit area by scanning the measurement light of the OCT optical system based on the front image of the fundus captured by the imaging optical system.

6. A fundus photography program executed by a fundus photography device that photographs the fundus of a subject's eye, the fundus photography program comprising an OCT optical system for acquiring an OCT signal of the fundus by utilizing interference between measurement light and reference light irradiated onto the fundus of the subject's eye, the fundus photography program comprising: an imaging control step of controlling the OCT optical system to scan the measurement light at different timings at the same position on the fundus to acquire the plurality of OCT signals and acquire a front motion contrast image based on the plurality of OCT signals; an output control step of displaying the motion contrast image on a display means; causing the fundus photographing device to execute the above; the photographing control step includes aligning frontal motion contrast images of unit areas at a plurality of positions different from the same position to obtain a panoramic image that is a frontal motion contrast image of a wide area; the output control step displays the panoramic image in a manner that allows the alignment state to be distinguished. A fundus photography program characterized by:

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