Ophthalmological imaging device

Abstract

To acquire a high-quality OCT image while performing a wide-angle OCT scan at a high speed.SOLUTION: An ophthalmological imaging device according to an embodiment applies a preparatory OCT scan to the subject's eye, which passes through both a central region and a peripheral region of the OCT scan application area, to acquire data. From this data, a preparatory image is constructed, and focus control parameters are set on the basis of the preparatory image. Thereafter, the ophthalmological imaging device performs an OCT scan according to a scan pattern including a continuous first partial pattern for the central region and a continuous second partial pattern for the peripheral region, while controlling the focal position in the optical path of measurement light according to the set focus control parameters.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] This invention relates to an ophthalmic imaging apparatus.

Background Art

[0002] In ophthalmic medical treatment, the importance of image diagnosis and image analysis has been increasing. In particular, the application of optical coherence tomography (OCT) to ophthalmology has been accelerating this trend. OCT enables three-dimensional imaging of the eye to be examined and three-dimensional structural analysis and functional analysis, and has demonstrated its effectiveness in obtaining, for example, the distribution of various measurement values.

[0003] In recent years, an expansion of the OCT scan range, that is, a widening of the OCT field of view, has been underway. For example, in order to scan a wide range from the center to the periphery of the fundus, devices have been developed in which the deflection angle of an optical scanner (such as a galvanometer mirror) is increased and the structure, control, and imaging are optimized accordingly (see, for example, Patent Documents 1 and 2).

[0004] When an OCT scan (generally a raster scan) is applied to a wide area of the fundus, the image quality deteriorates particularly at locations far from the center of the fundus (referred to as the peripheral part) due to the influence of the aberration of the eye's optical system. This is due to the fact that the aberration of the eye is larger in the peripheral part than in the central part of the fundus (see, for example, Non-Patent Document 1).

[0005] It is conceivable to perform focus control in order to eliminate such image quality deterioration. However, since the speed of focus control is considerably slower than the speed of the OCT scan (for example, the repetition rate of A scans), it is not realistic to perform focus control while applying a high-speed raster scan to a wide area of the fundus.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Non-Patent Document

[0007]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] An object of this invention is to acquire high-quality OCT images while performing wide-angle OCT scans at high speed.

Means for Solving the Problems

[0009] A first aspect of an exemplary embodiment includes a data collection unit that applies an optical coherence tomography (OCT) scan to an eye to be examined to collect data, an image construction unit that constructs an image from the data collected by the data collection unit, a focal position changing unit provided in an optical path of measurement light projected onto the eye to be examined by the data collection unit, a scan control unit that controls the data collection unit according to a scan pattern including a continuous first partial pattern for a central region of an OCT scan application area and a continuous second partial pattern for a peripheral region, and a focus control unit that controls the focal position changing unit to apply a first focal position in parallel with the application of an OCT scan to at least a part of the first partial pattern and to apply a second focal position different from the first focal position in parallel with the application of an OCT scan to at least a part of the second partial pattern. The ophthalmic imaging device is included.

[0010] A second aspect of the exemplary embodiment is the ophthalmic imaging device of the first aspect, wherein the scan pattern includes a curvilinear scan pattern defined in a polar coordinate system with the center of the OCT scan application area as the origin.

[0011] A third aspect of the exemplary embodiment is the ophthalmic imaging device of the second aspect, wherein the curvilinear scan pattern is either a spiral scan pattern from the center of the OCT scan application area toward the outer edge or a spiral scan pattern from the outer edge of the OCT scan application area toward the center.

[0012] A fourth aspect of the exemplary embodiment is the ophthalmic imaging device of the second or third aspect, wherein the image construction unit forms an image defined in the polar coordinate system from the data collected by the OCT scan applied to the eye to be examined according to the curvilinear scan pattern, and converts the image defined in the polar coordinate system into an image defined in a three-dimensional orthogonal coordinate system.

[0013] A fifth aspect of the exemplary embodiment is the ophthalmic imaging device of any one of the first to fourth aspects, wherein the first focal length corresponding to the first focal position is longer than the second focal length corresponding to the second focal position.

[0014] A sixth aspect of the exemplary embodiment is the ophthalmic imaging device of any one of the first to fifth aspects. Before the OCT scan according to the scan pattern, the data collection unit applies a preparatory OCT scan to the eye to be examined. The image construction unit constructs a preparatory image from the data collected by the preparatory OCT scan, and further includes a parameter setting unit that sets one or more focus control parameters based on the preparatory image constructed by the image construction unit. The focus control unit executes control of the focus position changing unit according to the one or more focus control parameters set by the parameter setting unit.

[0015] A seventh aspect of the exemplary embodiment is the ophthalmic imaging device of the sixth aspect, wherein the one or more focus control parameters include a focus position change range including the first focus position and the second focus position.

[0016] An eighth aspect of the exemplary embodiment is the ophthalmic imaging device of the sixth or seventh aspect, wherein the one or more focus control parameters include at least one of a moving speed and a moving acceleration of the focus position.

[0017] A ninth aspect of the exemplary embodiment is the ophthalmic imaging device according to any one of the first to eighth aspects, further including an imaging unit that repeatedly images the eye to be examined, and a movement detection unit that analyzes time-series images acquired by the imaging unit to detect movement of the eye to be examined, wherein the data collection unit includes an optical scanner that deflects light for OCT scanning, and the scan control unit controls the optical scanner based on an output from the movement detection unit while controlling the data collection unit according to the scan pattern.

[0018] A tenth aspect of the exemplary embodiment is a method for controlling an ophthalmic imaging device including a data collection unit that collects data by applying optical coherence tomography (OCT) scanning to an eye to be examined, an image construction unit that constructs an image from the data collected by the data collection unit, and a focus position changing unit provided in an optical path of measurement light projected onto the eye to be examined by the data collection unit, the method including a scan control step of controlling the data collection unit according to a scan pattern including a continuous first partial pattern for a central region of an OCT scan application area and a continuous second partial pattern for a peripheral region, and a focus control step of controlling the focus position changing unit to apply a first focus position in parallel with application of an OCT scan to at least a part of the first partial pattern and to apply a second focus position different from the first focus position in parallel with application of an OCT scan to at least a part of the second partial pattern.

[0019] An eleventh aspect of the exemplary embodiment is a program for causing a computer to execute the control method of the tenth aspect.

[0020] A twelfth aspect of the exemplary embodiment is a computer-readable non-transitory recording medium storing the program of the eleventh aspect.

Advantages of the Invention

[0021] According to the exemplary embodiment, it is possible to acquire high-quality OCT images while performing wide-angle OCT scans at high speed.

Brief Description of the Drawings

[0022]

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DETAILED DESCRIPTION OF THE INVENTION

[0023] An ophthalmic imaging apparatus, its control method, program, and recording medium according to an exemplary embodiment will be described in detail with reference to the drawings. It is possible to incorporate the disclosure content of the documents cited in this specification and any other known techniques into the embodiments. Also, unless otherwise specified, "image data" and the "image" based on it are not distinguished. Similarly, unless otherwise specified, the "part" of the eye to be examined and its "image" are not distinguished.

[0024] The ophthalmic imaging device according to an exemplary embodiment can measure the fundus of a living eye using Fourier domain OCT (for example, swept source OCT). The type of OCT applicable to the embodiment is not limited to swept source OCT, and may be, for example, spectral domain OCT or time domain OCT. Further, the application target of OCT is not limited to the fundus, and may be any part of the eye such as the anterior segment or the vitreous body.

[0025] An exemplary embodiment may be capable of processing an image acquired by a modality other than OCT. For example, an exemplary embodiment may be capable of processing an image acquired by any one of a fundus camera, SLO, slit lamp microscope, and operating microscope for ophthalmic surgery. The ophthalmic imaging device according to an exemplary embodiment may include any one of a fundus camera, SLO, slit lamp microscope, and operating microscope for ophthalmic surgery.

[0026] The image of the eye to be examined that can be processed according to an exemplary embodiment may include an image obtained by analyzing an image acquired by any modality. Examples of such analyzed images include pseudo-colorized images (such as segmented pseudo-color images), images consisting of only a part of the original image (such as segment images), images representing the thickness distribution of tissues obtained by analyzing OCT images (such as layer thickness maps, layer thickness graphs), images representing the shape of tissues (such as curvature maps), images representing the distribution of lesions (such as lesion maps), and the like.

[0027] <Configuration> The ophthalmic imaging device 1 of the exemplary embodiment shown in FIG. 1 includes a fundus camera unit 2, an OCT unit 100, and an arithmetic control unit 200. The fundus camera unit 2 is provided with an optical system and mechanism for acquiring a front image of the eye to be examined. The OCT unit 100 is provided with a part of the optical system and mechanism for executing OCT. The other part of the optical system and mechanism for executing OCT is provided in the fundus camera unit 2. The arithmetic control unit 200 includes one or more processors for executing various arithmetic operations and controls. In addition to these, optional elements and units such as a member for supporting the subject's face (e.g., a chin rest, a forehead rest, etc.) and a lens unit for switching the OCT target site (e.g., an attachment for anterior segment OCT) may be provided in the ophthalmic imaging device 1.

[0028] In this specification, "processor" means a circuit such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), or a programmable logic device (e.g., an SPLD (Simple Programmable Logic Device), a CPLD (Complex Programmable Logic Device), an FPGA (Field Programmable Gate Array)). The processor realizes the functions according to the embodiments by reading and executing a program stored in a storage circuit or a storage device, for example.

[0029] 〈Fundus Camera Unit 2〉 The fundus camera unit 2 is provided with an optical system for photographing the fundus Ef of the eye to be examined E. The acquired image of the fundus Ef (referred to as a fundus image, a fundus photograph, etc.) is a front image such as an observation image or a photographed image. The observation image is obtained, for example, by video shooting using near-infrared light and is used for alignment, focusing, tracking, etc. The photographed image is a still image using flash light in the visible region or the infrared region, for example.

[0030] The fundus camera unit 2 includes an illumination optical system 10 and a photographing optical system 30. The illumination optical system 10 irradiates the eye to be examined E with illumination light. The photographing optical system 30 detects the return light of the illumination light from the eye to be examined E. The measurement light from the OCT unit 100 is guided to the eye to be examined E through the optical path in the fundus camera unit 2, and the return light thereof is guided to the OCT unit 100 through the same optical path.

[0031] The light (observation illumination light) output from the observation light source 11 of the illumination optical system 10 is reflected by the concave mirror 12, passes through the condenser lens 13, passes through the visible cut filter 14, and becomes near-infrared light. Further, the observation illumination light is once focused in the vicinity of the photographing light source 15, reflected by the mirror 16, and passes through the relay lens system 17, relay lens 18, aperture 19, and relay lens system 20. Then, the observation illumination light is reflected at the peripheral portion (the region around the hole portion) of the aperture mirror 21, passes through the dichroic mirror 46, and is refracted by the objective lens 22 to illuminate the eye to be examined E (fundus Ef). The return light of the observation illumination light from the eye to be examined E is refracted by the objective lens 22, passes through the dichroic mirror 46, passes through the hole portion formed in the central region of the aperture mirror 21, passes through the dichroic mirror 55, passes through the photographing focusing lens 31, and is reflected by the mirror 32. Further, this return light passes through the half mirror 33A, is reflected by the dichroic mirror 33, and is imaged on the light receiving surface of the image sensor 35 by the imaging lens 34. The image sensor 35 detects the return light at a predetermined frame rate. Note that the focus (focal position) of the photographing optical system 30 is adjusted to match the fundus Ef or the anterior eye part.

[0032] The light (photographing illumination light) output from the photographing light source 15 is irradiated to the fundus Ef through the same path as the observation illumination light. The return light of the photographing illumination light from the eye to be examined E is guided to the dichroic mirror 33 through the same path as the return light of the observation illumination light, passes through the dichroic mirror 33, is reflected by the mirror 36, and is imaged on the light receiving surface of the image sensor 38 by the imaging lens 37.

[0033] The liquid crystal display (LCD) 39 displays a fixation target (fixation target image). A part of the light beam output from the LCD 39 is reflected by the half mirror 33A, then reflected by the mirror 32, passes through the hole of the aperture mirror 21 via the photographing focusing lens 31 and the dichroic mirror 55. The light beam that has passed through the hole of the aperture mirror 21 passes through the dichroic mirror 46, is refracted by the objective lens 22, and is projected onto the fundus Ef.

[0034] By changing the display position of the fixation target image on the screen of the LCD 39, the fixation position of the subject eye E by the fixation target can be changed. Examples of the fixation position include a fixation position for acquiring an image centered on the macula, a fixation position for acquiring an image centered on the optic disc, a fixation position for acquiring an image centered on a position between the macula and the optic disc, and a fixation position for acquiring an image of a site far from the macula (peripheral fundus). A graphical user interface (GUI) or the like for designating at least one of such typical fixation positions can be provided. Also, a GUI or the like for manually moving the fixation position (display position of the fixation target) can be provided.

[0035] The configuration for presenting a fixation target with a changeable fixation position to the subject eye E is not limited to a display device such as an LCD. For example, a fixation matrix in which a plurality of light emitting parts (light emitting diodes or the like) are arranged in a matrix (array) can be adopted instead of the display device. In this case, by selectively lighting the plurality of light emitting parts, the fixation position of the subject eye E by the fixation target can be changed. As another example, a fixation target with a changeable fixation position can be generated by one or more movable light emitting parts.

[0036] The alignment optical system 50 generates an alignment index for aligning the optical system with respect to the eye E to be examined. The alignment light output from the light-emitting diode (LED) 51 passes through the aperture 52, the aperture 53, and the relay lens 54, is reflected by the dichroic mirror 55, passes through the aperture of the aperture mirror 21, passes through the dichroic mirror 46, and is projected onto the eye E to be examined via the objective lens 22. The return light (such as corneal reflection light) of the alignment light from the eye E to be examined is guided to the image sensor 35 through the same path as the return light of the observation illumination light. Manual alignment or auto-alignment can be performed based on the received light image (alignment index image).

[0037] Similar to the conventional case, the alignment index image in this example consists of two bright spot images whose positions change depending on the alignment state. When the relative position between the eye E to be examined and the optical system changes in the xy direction, the two bright spot images are displaced integrally in the xy direction. When the relative position between the eye E to be examined and the optical system changes in the z direction, the relative position (distance) between the two bright spot images changes. When the distance between the eye E to be examined and the optical system in the z direction matches the predetermined working distance, the two bright spot images overlap. When the position of the eye E and the position of the optical system match in the xy direction, the two bright spot images are presented within or near a predetermined alignment target. When the distance between the eye E to be examined and the optical system in the z direction matches the working distance and the position of the eye E and the position of the optical system match in the xy direction, the two bright spot images overlap and are presented within the alignment target.

[0038] In auto-alignment, the data processing unit 230 detects the positions of the two bright spot images, and the main control unit 211 controls the moving mechanism 150 described later based on the positional relationship between the two bright spot images and the alignment target. In manual alignment, the main control unit 211 causes the display unit 241 to display the two bright spot images together with the observation image of the eye E to be examined, and the user operates the moving mechanism 150 using the operation unit 242 while referring to the displayed two bright spot images.

[0039] The focusing optical system 60 generates a split index used for focus adjustment for the eye E to be examined. In conjunction with the movement of the imaging focusing lens 31 along the optical path (imaging optical path) of the imaging optical system 30, the focusing optical system 60 is moved along the optical path (illumination optical path) of the illumination optical system 10. The reflecting rod 67 is inserted into and removed from the illumination optical path. When performing focus adjustment, the reflecting surface of the reflecting rod 67 is disposed obliquely to the illumination optical path. The focus light output from the LED 61 passes through the relay lens 62, is separated into two light beams by the split index plate 63, passes through the two-hole aperture stop 64, is reflected by the mirror 65, is once imaged on the reflecting surface of the reflecting rod 67 by the condenser lens 66, and is then reflected. Further, the focus light passes through the relay lens 20, is reflected by the aperture mirror 21, passes through the dichroic mirror 46, and is projected onto the eye E to be examined through the objective lens 22. The return light (such as fundus reflection light) of the focus light from the eye E to be examined is guided to the image sensor 35 through the same path as the return light of the alignment light. Manual focusing and autofocusing can be executed based on the received light image (split index image).

[0040] The diopter correction lenses 70 and 71 can be selectively inserted into the imaging optical path between the aperture mirror 21 and the dichroic mirror 55. The diopter correction lens 70 is a plus lens (convex lens) for correcting strong hyperopia. The diopter correction lens 71 is a minus lens (concave lens) for correcting strong myopia.

[0041] The dichroic mirror 46 combines the optical path for fundus imaging and the optical path for OCT (measurement arm). The dichroic mirror 46 reflects light in the wavelength band used for OCT and transmits light for fundus imaging. In the measurement arm, a collimator lens unit 40, a retroreflector 41, a dispersion compensation member 42, an OCT focusing lens 43, an optical scanner 44, and a relay lens 45 are provided in order from the OCT unit 100 side.

[0042] The retroreflector 41 is movable in the direction of the arrow shown in FIG. 1, whereby the length of the measurement arm is changed. The change in the measurement arm length is used, for example, for optical path length correction according to the axial length of the eye or adjustment of the interference state.

[0043] The dispersion compensation member 42 acts together with the dispersion compensation member 113 (described later) arranged in the reference arm to match the dispersion characteristics of the measurement light LS and the dispersion characteristics of the reference light LR.

[0044] The OCT focusing lens 43 is moved along the measurement arm to perform focusing adjustment of the measurement arm. The movement of the imaging focusing lens 31, the movement of the focusing optical system 60, and the movement of the OCT focusing lens 43 can be controlled in a coordinated manner.

[0045] The optical scanner 44 is disposed substantially at a position optically conjugate to the pupil of the eye E to be examined. The optical scanner 44 deflects the measurement light LS guided by the measurement arm. The optical scanner 44 is a galvanometer scanner capable of two-dimensional scanning, including, for example, a galvanometer mirror for performing scanning in the x direction and a galvanometer mirror for performing scanning in the y direction.

[0046] 〈OCT Unit 100〉 As illustrated in FIG. 2, the OCT unit 100 is provided with an optical system for applying swept-source OCT. This optical system includes an interference optical system. This interference optical system splits the light from a wavelength-variable light source (wavelength-sweeping light source) into measurement light and reference light, overlaps the return light of the measurement light from the eye E to be examined with the reference light that has passed through the reference optical path to generate interference light, and detects this interference light. The detection result (detection signal) obtained by the interference optical system is a signal representing the spectrum of the interference light and is sent to the arithmetic control unit 200.

[0047] The light source unit 101 includes, for example, a near-infrared wavelength-variable laser that rapidly changes the wavelength of the emitted light. The light L0 output from the light source unit 101 is guided by the optical fiber 102 to the polarization controller 103, and its polarization state is adjusted. Further, the light L0 is guided by the optical fiber 104 to the fiber coupler 105 and split into the measurement light LS and the reference light LR. The optical path of the measurement light LS is called a measurement arm or the like, and the optical path of the reference light LR is called a reference arm or the like.

[0048] The reference light LR is guided by the optical fiber 110 to the collimator 111, converted into a parallel light beam, and guided to the retroreflector 114 via the optical path length correction member 112 and the dispersion compensation member 113. The optical path length correction member 112 acts to make the optical path length of the reference light LR and the optical path length of the measurement light LS match. The dispersion compensation member 113 acts together with the dispersion compensation member 42 disposed in the measurement arm to make the dispersion characteristics between the reference light LR and the measurement light LS match. The retroreflector 114 is movable along the optical path of the reference light LR incident thereon, whereby the length of the reference arm is changed. The change in the reference arm length is used, for example, for optical path length correction according to the axial length of the eye or adjustment of the interference state.

[0049] The reference light LR that has passed through the retroreflector 114 is converted from a parallel light beam into a converging light beam by the collimator 116 via the dispersion compensation member 113 and the optical path length correction member 112, and enters the optical fiber 117. The reference light LR that has entered the optical fiber 117 is guided to the polarization controller 118, and its polarization state is adjusted, guided through the optical fiber 119 to the attenuator 120, and its light amount is adjusted, and guided through the optical fiber 121 to the fiber coupler 122.

[0050] On the one hand, the measurement light LS generated by the fiber coupler 105 is guided by the optical fiber 127, converted into a parallel light beam by the collimator lens unit 40, and reflected by the dichroic mirror 46 via the retroreflector 41, the dispersion compensation member 42, the OCT focusing lens 43, the optical scanner 44, and the relay lens 45, refracted by the objective lens 22, and projected onto the eye to be examined E. The measurement light LS is scattered and reflected at various depth positions of the eye to be examined E. The return light of the measurement light LS from the eye to be examined E travels in the reverse direction along the same path as the forward path, is guided to the fiber coupler 105, and reaches the fiber coupler 122 via the optical fiber 128.

[0051] The fiber coupler 122 superimposes the measurement light LS incident via the optical fiber 128 and the reference light LR incident via the optical fiber 121 to generate interference light. The fiber coupler 122 generates a pair of interference lights LC by branching the generated interference light at a predetermined branching ratio (for example, 1:1). The pair of interference lights LC are respectively guided to the detector 125 through the optical fibers 123 and 124.

[0052] The detector 125 includes, for example, a balanced photodiode. The balanced photodiode has a pair of photodetectors that respectively detect the pair of interference lights LC, and outputs the difference between the pair of detection results obtained thereby. The detector 125 sends this output (detection signal) to the data acquisition system (DAQ) 130.

[0053] The data collection system 130 is supplied with a clock KC from the light source unit 101. The clock KC is generated in the light source unit 101 in synchronization with the output timing of each wavelength swept within a predetermined wavelength range by a wavelength tunable light source. The light source unit 101, for example, branches the light L0 of each output wavelength to generate two branched lights, optically delays one of these branched lights, combines these branched lights, detects the resulting combined light, and generates the clock KC based on the detection result. The data collection system 130 executes sampling of the detection signal input from the detector 125 based on the clock KC. The data collection system 130 sends the result of this sampling to the arithmetic control unit 200.

[0054] In this example, both an element for changing the measurement arm length (for example, the retroreflector 41) and an element for changing the reference arm length (for example, the retroreflector 114 or the reference mirror) are provided, but only one of these elements may be provided. Further, the element for changing the difference (optical path length difference) between the measurement arm length and the reference arm length is not limited to these and may be any element (optical member, mechanism, etc.).

[0055] <Control System and Processing System> Configuration examples of the control system and processing system of the ophthalmic imaging device 1 are shown in FIGS. 3 and 4. The control unit 210, the image construction unit 220, and the data processing unit 230 are provided, for example, in the arithmetic control unit 200. The ophthalmic imaging device 1 may include a communication device for performing data communication with an external device. The ophthalmic imaging device 1 may include a drive device (reader / writer) for performing processing for reading data from a recording medium and processing for writing data to a recording medium.

[0056] <Control Unit 210> The control unit 210 executes various controls. The control unit 210 includes a main control unit 211 and a storage unit 212. Also, as shown in FIG. 4, the control unit 210 of the present embodiment includes a scan control unit 213 and a focus control unit 214.

[0057] <Main Control Unit 211> The main control unit 211 includes a processor and controls each element of the ophthalmic imaging device 1 (including the elements shown in FIGS. 1 to 4). The main control unit 211 is realized by the cooperation of hardware including a processor and control software.

[0058] The main control unit 211 can operate the scan control unit 213 and the focus control unit 214 in a coordinated manner (synchronously). Thereby, the OCT scan and the focus adjustment are executed in a coordinated manner (synchronously).

[0059] The imaging focus drive unit 31A moves the imaging focus lens 31 arranged in the imaging optical path and the focus optical system 60 arranged in the illumination optical path under the control of the main control unit 211. The retroreflector (RR) drive unit 41A moves the retroreflector 41 provided on the measurement arm under the control of the main control unit 211. The OCT focus drive unit 43A moves the OCT focus lens 43 arranged on the measurement arm under the control of the main control unit 211. The optical scanner 44 provided on the measurement arm operates under the control of the main control unit 211. The retroreflector (RR) drive unit 114A moves the retroreflector 114 arranged on the reference arm under the control of the main control unit 211. Each of the above-described drive units includes an actuator such as a pulse motor that operates under the control of the main control unit 211.

[0060] The moving mechanism 150 moves at least the fundus camera unit 2 three-dimensionally, for example. In a typical example, the moving mechanism 150 includes an x-stage movable in the ±x direction (left-right direction), an x-moving mechanism for moving the x-stage, a y-stage movable in the ±y direction (up-down direction), a y-moving mechanism for moving the y-stage, a z-stage movable in the ±z direction (depth direction), and a z-moving mechanism for moving the z-stage. Each of these moving mechanisms includes an actuator such as a pulse motor that operates under the control of the main control unit 211.

[0061] 〈Memory unit 212〉 The storage unit 212 stores various types of data. Examples of the data stored in the storage unit 212 include OCT images, fundus images, subject eye information, control parameters, and the like.

[0062] The subject eye information includes subject information such as patient ID and name, left eye / right eye identification information, and electronic medical record information.

[0063] The control parameters include, for example, parameters used for controlling OCT scans (scan control parameters) and parameters used for controlling focus (focal position) (focus control parameters).

[0064] The scan control parameters are parameters indicating the content of control for the optical scanner 44. Examples of the scan control parameters include parameters indicating the scan pattern, parameters indicating the scan speed, and parameters indicating the scan interval. The scan speed is defined, for example, as the repetition rate of A-scans. The scan interval is defined, for example, as the interval between adjacent A-scans, that is, the array interval of scan points. The scan pattern will be described later.

[0065] The focus control parameters are parameters indicating the content of control for the OCT focusing drive unit 43A. Examples of the focus control parameters include parameters indicating the focal position of the measurement arm, parameters indicating the moving speed of the focal position, and parameters indicating the moving acceleration of the focal position. The parameter indicating the focal position is, for example, a parameter indicating the position of the OCT focusing lens 43. The parameter indicating the moving speed of the focal position is, for example, a parameter indicating the moving speed of the OCT focusing lens 43. The parameter indicating the moving acceleration of the focal position is, for example, a parameter indicating the moving acceleration of the OCT focusing lens 43. The moving speed may be constant or may not be constant. The same applies to the moving acceleration.

[0066] 〈Scan Control Unit 213〉 The scan control unit 213 controls the optical scanner 44 based on scan control parameters. The scan control unit 213 may further execute control of the light source unit 101. The content of the processing executed by the scan control unit 213 will be described later. The scan control unit 213 is included in the main control unit 211. The scan control unit 213 is realized by the cooperation of hardware including a processor and scan control software.

[0067] 〈Focus control unit 214〉 The focus control unit 214 controls the OCT focusing drive unit 43A based on focus control parameters. The content of the processing executed by the focus control unit 214 will be described later. The focus control unit 214 is included in the main control unit 211. The focus control unit 214 is realized by the cooperation of hardware including a processor and focus control software.

[0068] 〈Image construction unit 220〉 The image construction unit 220 includes a processor and forms OCT image data of the fundus Ef based on signals (sampling data) input from the data collection system 130. The OCT image data is, for example, B-scan image data (two-dimensional tomographic image data).

[0069] The process of forming the OCT image data includes noise removal (noise reduction), filtering, fast Fourier transform (FFT), etc., similar to conventional Fourier domain OCT. In the case of other types of OCT devices, the image construction unit 220 executes known processes according to the type.

[0070] The image construction unit 220 forms three-dimensional data of the fundus Ef based on the signals input from the data collection system 130. This three-dimensional data is three-dimensional image data representing a three-dimensional region (volume) of the fundus Ef. This three-dimensional image data means image data in which the positions of pixels are defined by a three-dimensional coordinate system. Examples of the three-dimensional image data include stack data and volume data.

[0071] Stack data is image data obtained by three-dimensionally arranging a plurality of tomographic images obtained along a plurality of scan lines based on the positional relationship of these scan lines. That is, stack data is image data obtained by expressing (i.e., embedding in one three-dimensional space) a plurality of tomographic images originally defined by individual two-dimensional coordinate systems using one three-dimensional coordinate system. Alternatively, stack data is image data obtained by three-dimensionally arranging a plurality of A-scan data respectively acquired for a plurality of two-dimensionally arranged scan points (scan point array) based on the positional relationship of these scan points.

[0072] Volume data is image data with voxels arranged three-dimensionally as pixels, and is also called voxel data. Volume data is formed by applying interpolation processing, voxelization processing, etc. to stack data.

[0073] The image construction unit 220 performs rendering on the three-dimensional image data to form a display image. Examples of applicable rendering methods include volume rendering, surface rendering, maximum intensity projection (MIP), minimum intensity projection (MinIP), multi-planar reformation (MPR), etc.

[0074] The image construction unit 220 can form an OCT en-face image based on the three-dimensional image data. For example, the image construction unit 220 can project the three-dimensional image data in the z direction (A-line direction, depth direction) to construct projection data. Also, the image construction unit 220 can project a part of the three-dimensional image data in the z direction to construct a shadowgram.

[0075] The partial three-dimensional image data projected to construct a shadowgram is set using, for example, segmentation. Segmentation is a process of identifying partial regions in an image. Typically, segmentation is used to identify an image region corresponding to a predetermined tissue of the fundus Ef. Segmentation is executed, for example, by the image construction unit 220 or the data processing unit 230.

[0076] The ophthalmic imaging apparatus 1 may be capable of performing OCT angiography. OCT angiography is an imaging technique for constructing an image in which retinal blood vessels and choroidal blood vessels are emphasized (see, for example, Japanese Patent Application Laid-Open No. 2015-515894). Generally, although the fundus tissue (structure) does not change over time, the blood flow portion inside the blood vessels changes over time. In OCT angiography, an image is generated by emphasizing such a portion (blood flow signal) where there is a temporal change. Note that OCT angiography is also called OCT motion contrast imaging or the like. Further, the image obtained by OCT angiography is called an angiogram image, an angiogram, a motion contrast image, or the like.

[0077] When OCT angiography is performed, the ophthalmic imaging apparatus 1 repeatedly scans the same region of the fundus Ef a predetermined number of times. For example, repeated scanning can be performed along a locus between two points on a predetermined scan pattern (for example, a spiral scan pattern). The image construction unit 220 can construct a motion contrast image from the data set collected by the data collection system 130 in the repeated scanning. This motion contrast image is an angiogram image obtained by imaging while emphasizing the temporal change of the interference signal caused by the blood flow in the fundus Ef. Typically, OCT angiography is applied to a three-dimensional region of the fundus Ef, and an image representing the three-dimensional distribution of the blood vessels in the fundus Ef is obtained.

[0078] When OCT angiography is performed, the image construction unit 220 can construct arbitrary two-dimensional angiography image data and / or arbitrary pseudo three-dimensional angiography image data from the three-dimensional angiography image data. For example, the image construction unit 220 can construct two-dimensional angiography image data representing an arbitrary cross-section of the fundus Ef by applying multi-slice reconstruction to the three-dimensional angiography image data.

[0079] The image construction unit 220 is realized by the cooperation of hardware including a processor and image construction software.

[0080] 〈Data processing unit 230〉 The data processing unit 230 includes a processor and applies various data processes to the image of the eye E to be examined. For example, the data processing unit 230 is realized by the cooperation of hardware including a processor and data processing software.

[0081] The data processing unit 230 can perform registration between two images acquired for the fundus Ef. For example, the data processing unit 230 can perform registration between the three-dimensional image data acquired by OCT and the frontal image acquired by the fundus camera unit 2. Also, the data processing unit 230 can perform registration between two OCT images acquired by OCT. Also, the data processing unit 230 can perform registration between two frontal images acquired by the fundus camera unit 2. Also, it is possible to apply registration to the analysis result of the OCT image and the analysis result of the frontal image. Registration can be executed by a known method and includes, for example, feature point extraction and affine transformation.

[0082] As illustrated in FIG. 4, the data processing unit 230 of the present embodiment includes a parameter setting unit 231 and a movement detection unit 232.

[0083] 〈Parameter setting unit 231〉 The parameter setting unit 231 sets focus control parameters based on an OCT image of the fundus Ef acquired in advance. This OCT image (preparatory image) is used to detect the approximate shape of the application area of the wide-angle OCT scan, and the focus control parameters are set based on the shape detected thereby.

[0084] The ophthalmic imaging device 1 can acquire an OCT image used for setting focus control parameters. For example, the ophthalmic imaging device 1 can apply a preparatory OCT scan to the subject eye E before applying a wide-angle OCT scan to the subject eye E.

[0085] The preparatory OCT scan is executed so as to pass through both the central region and the peripheral region of the wide-angle OCT scan application area. For example, in the preparatory OCT scan for the wide-angle OCT scan of the fundus Ef, the macular region (and its vicinity) can be set as the central region of the fundus Ef, and a region separated from the macula by a predetermined distance or more can be set as the peripheral region. Also, in the preparatory OCT scan for the wide-angle OCT scan of the anterior segment of the eye, the corneal apex and its vicinity can be set as the central region of the anterior segment of the eye, and a region separated from the corneal apex by a predetermined distance or more can be set as the peripheral region. More generally, it is possible to set the optical axis of the subject eye E and its vicinity as the central region, and a region separated from the optical axis by a predetermined distance or more as the peripheral region.

[0086] The pattern of the preparatory OCT scan may be a scan pattern including a large number of scan points such as a three-dimensional scan (raster scan), but considering that the purpose of the preparatory OCT scan is to grasp the approximate shape of the wide-angle OCT scan application area, a relatively simple scan pattern such as a B-scan (line scan), cross scan, or radial scan is sufficient.

[0087] The image construction unit 220 constructs a preliminary image from the data collected by the preliminary OCT scan. The preliminary image typically includes one or more B-scan images representing one or more cross-sections of the central region and one or more cross-sections of the peripheral region of the wide-angle OCT scan application area.

[0088] In the following example, the outer edge of the central region, as well as the outer and inner edges of the peripheral region, are all circular, but the shapes of the central region and the peripheral region are not limited to these. For example, any one of the outer edge of the central region, the outer edge and the inner edge of the peripheral region may be rectangular, or may have an arbitrary shape. Also, the outer edge shape and the inner edge shape of the peripheral region may be the same or different from each other.

[0089] An example of the preliminary OCT scan shown in FIG. 5A is one B-scan 330 that passes through a central region 310 including the macula Em of the fundus Ef and a peripheral region 320 (the region shown by hatching) away from the macula Em. The reference sign Ed indicates the optic nerve head. In this example, one B-scan image representing the cross-section to which the B-scan 330 is applied is obtained. The B-scan image of this example represents the relative relationship between the depth position (z position) of the central region 310 and the depth position of the peripheral region 320. In this example, the relative depth position relationship between the central region 310 and the peripheral region 320 is obtained only for the direction in which the B-scan 330 is applied.

[0090] An example of a preparatory OCT scan shown in FIG. 5B is two B-scans 341 and 342 that pass through the central region 310 and the peripheral region 320, respectively. The two B-scans 341 and 342 are orthogonal to each other. That is, the preparatory OCT scan in this example is a cross scan. In this example, a B-scan image representing a cross section to which the B-scan 341 is applied and a B-scan image representing a cross section to which the B-scan 342 is applied are obtained. Each of the two B-scan images in this example represents the relative relationship between the depth position (z position) of the central region 310 and the depth position of the peripheral region 320. In this example, with respect to the direction in which the B-scan 341 is applied and the direction in which the B-scan 342 is applied, that is, for two directions orthogonal to each other, the relative depth position relationship between the central region 310 and the peripheral region 320 is obtained.

[0091] Although illustration is omitted, when a radial scan (a plurality of B-scans arranged at equal angular intervals) is applied as the preparatory OCT scan, the relative depth position relationship between the central region and the peripheral region is obtained for a plurality of directions arranged at equal angular intervals with respect to each other. Also, although illustration is omitted, when a three-dimensional scan (for example, a raster scan) is applied as the preparatory OCT scan, the relative depth position relationship between the central region and the peripheral region is obtained for any direction in the xy plane. Even when other scan patterns are applied, the relative depth position relationship between the central region and the peripheral region is obtained for one or more directions according to the scan pattern.

[0092] In this way, the pattern of the preparatory OCT scan determines the content (direction, etc.) and amount (angular interval, etc.) of the information acquired as the relative depth position relationship. Conversely, the pattern of the preparatory OCT scan can be determined according to the content and amount of the information to be acquired as the relative depth position relationship. The determination of the preparatory OCT scan pattern is performed, for example, in advance or for each inspection.

[0093] Data collected by a preparatory OCT scan is sent to the image construction unit 220, and a preparatory image is constructed. The parameter setting unit 231 sets one or more focus control parameters based on this preparatory image. As described above, the focus control parameter is a parameter indicating the content of control for the OCT focusing drive unit 43A. Examples thereof include a parameter indicating the focal position of the measurement arm, a parameter indicating the moving speed of the focal position, and a parameter indicating the moving acceleration of the focal position.

[0094] An example of the process executed by the parameter setting unit 231 will be described. An example of a preparatory image is shown in FIG. 6A. The preparatory image G is an image constructed from data collected by, for example, the B-scan 330 shown in FIG. 5A (or the B-scan 341 shown in FIG. 5B or a similar B-scan). The region outlined by the dotted line with reference numeral 310 corresponds to the intersection region (common region) of the central region 310 shown in FIG. 5A and the B-scan 330. The region indicated by the hatched line with reference numeral 320 corresponds to the intersection region (common region) of the peripheral region 320 shown in FIG. 5A and the B-scan 330. Note that there are two peripheral regions 320 in the preparatory image G. Also, the symbol Em is the image region of the macula, and the symbol Ed is the image region of the optic nerve head.

[0095] The parameter setting unit 231 analyzes the central region 310 of the preparatory image G to detect the macula region Em and specifies its depth position (z coordinate). For this purpose, the parameter setting unit 231 includes, for example, segmentation for specifying the image region of the inner limiting membrane (ILM), shape analysis for detecting the macula region Em from the shape (dip) of the specified inner limiting membrane region, and processing for obtaining the z coordinate of the pixel of the representative point of the detected macula region Em. The representative point of the macula region Em may be, for example, the center of the macula (fovea, deepest part of the dip). Let the z coordinate of the macula center obtained in this example be z1 (see FIG. 6B). Note that the site where the z coordinate is specified is not limited to the macula center and may be any representative point within the central region 310.

[0096] In addition, the parameter setting unit 231 analyzes the peripheral region 320 of the preparatory image G to detect the image region of a predetermined tissue (for example, the inner limiting membrane) and specifies its depth position (z coordinate). To this end, the parameter setting unit 231 includes, for example, segmentation for specifying the image region of the predetermined tissue and processing for obtaining the z coordinate of the pixel of the representative point of the specified image region. The representative point of the image region of the predetermined tissue may be, for example, the central position of the peripheral region 320 in the B-scan direction or the end point of the peripheral region 320. When the central positions of the two peripheral regions 320 of the preparatory image G are the representative points, the z coordinate of the inner limiting membrane obtained according to this example is z 21 and z 22 are defined as (see FIG. 6C).

[0097] Furthermore, the parameter setting unit 231 sets focus control parameters based on the z coordinate (z1) of the representative point of the central region 310 and the z coordinates (z 21 , z 22 ) of the representative points of the peripheral region 320.

[0098] For example, the parameter setting unit 231 can obtain the position of the OCT focusing lens 43 corresponding to the z coordinate (z1) of the representative point of the central region 310 and the positions of the OCT focusing lens 43 corresponding to the z coordinates (z 21 and z 22 ) of the representative points of the peripheral region 320, respectively. The position of the OCT focusing lens 43 corresponds to the focal position of the measurement arm. This example can be said to be the process of obtaining the absolute position of the OCT focusing lens 43. The process of this example is executed based on, for example, the coherence gate position (arm length, position of the retroreflector 41, position of the retroreflector 114) when the preparatory image G is acquired and the scale of the z axis (for example, the distance per pixel).

[0099] The parameter setting unit 231 determines the position (focal position) of the OCT focusing lens 43 corresponding to the z coordinate (z1) of the representative point of the central region 310 and the z coordinates (z 21 and z 22It is possible to obtain the difference from the position (focal position) of the OCT focusing lens 43 corresponding to each of )). In other words, this example can be said to be a process of obtaining the relative position of the OCT focusing lens 43. The process of this example is executed based on, for example, the scale of the z-axis.

[0100] The parameter setting unit 231 determines the position (focal position) of the OCT focusing lens 43 corresponding to the z-coordinate (z1) of the representative point in the central region 310 and the z-coordinate (z 21 and z 22 It is possible to obtain a focus position change range including the position (focal position) of the OCT focusing lens 43 corresponding to each of )). The focus position change range is the range of the focus position changed by the focus control, and is defined, for example, as the movement range of the OCT focusing lens 43. The process of this example is executed based on, for example, the coherence gate position when the preparatory image G is acquired and the scale of the z-axis.

[0101] The parameter setting unit 231 can set the speed at which the focus position of the measurement arm moves. The process of this example is executed based on, for example, the absolute position or relative position of the OCT focusing lens 43 described above, or based on the movement range of the OCT focusing lens 43.

[0102] The parameter setting unit 231 can set the acceleration at which the focus position of the measurement arm moves. The process of this example is executed based on, for example, the absolute position or relative position of the OCT focusing lens 43, or based on the movement range of the OCT focusing lens 43, or based on the movement speed of the OCT focusing lens 43.

[0103] When the preparatory image G is obtained, for example, as shown in FIG. 7, the parameter setting unit 231 sets the focus control parameters so that the focus position moves in the +z direction as it goes from the left peripheral region 320 side to the central region 310 side, and the focus position moves in the -z direction as it goes from the central region 310 side to the right peripheral region 320 side.

[0104] The parameter setting unit 231 can set information representing the relationship between the scan control parameter and the focus control parameter based on, for example, any of the above-described examples of the focus control parameter.

[0105] On this premise, a scan pattern for wide-angle OCT scan is set. The wide-angle OCT scan pattern is set, for example, in advance or for each inspection.

[0106] In the present embodiment, the wide-angle OCT scan pattern includes a scan pattern including a continuous first partial pattern for the central region of the wide-angle OCT scan application area and a continuous second partial pattern for the peripheral region. The first partial pattern is a pattern for continuously scanning at least a part of the central region, and the second partial pattern is a pattern for continuously scanning at least a part of the peripheral region. Here, "continuously scanning" means, for example, sequentially scanning a plurality of scan points arranged in a predetermined pattern in accordance with the arrangement order.

[0107] The wide-angle OCT scan pattern may include a curved scan pattern defined in a polar coordinate system with the center of the wide-angle OCT scan application area as the origin. The center of the wide-angle OCT scan application area may be, for example, the center of the macula, or may be other parts of the fundus. In this way, the center of the wide-angle OCT scan application area may be defined based on the part or tissue of the eye to be examined, but it is also possible to define this based on the ophthalmic imaging device 1. For example, the center of the wide-angle OCT scan application area may be defined as the neutral position (neutral direction) of the direction variable mirror (galvano mirror, etc.) of the optical scanner 44, or may be defined as the position of the optical axis of the measurement arm (optical axis of the objective lens 22). Examples of the curved wide-angle OCT scan pattern defined in a polar coordinate system with the center of the wide-angle OCT scan application area as the origin include a spiral pattern and a concentric circle pattern.

[0108] When the wide-angle OCT scan pattern is the above-described curvilinear scan pattern, this wide-angle OCT scan pattern may be a spiral scan pattern that goes from the center to the outer edge of the wide-angle OCT scan application area (see the spiral scan pattern 510 shown in FIG. 8A), or a spiral scan pattern that goes from the outer edge to the center of the wide-angle OCT scan application area (see the spiral scan pattern 520 shown in FIG. 8B).

[0109] The spiral scan pattern 510 shown in FIG. 8A uses the fovea center in the central region (not shown) as the scan start point, and passes through the peripheral region (not shown) while increasing the radius vector with the change of the declination angle, and reaches the scan end point near the outer edge.

[0110] The spiral scan pattern 520 shown in FIG. 8B uses the outer edge (nearby) as the scan start point, and passes through the peripheral region (not shown) while decreasing the radius vector with the change of the declination angle, and reaches the scan end point set at the fovea center in the central region (not shown).

[0111] In each of the spiral scan patterns 510 and 520, for illustration purposes, the intervals of the spirals are drawn coarser than the actual ones. In reality, for example, the intervals of the spirals may be dense enough to construct three-dimensional image data.

[0112] Some examples of the focus control parameters that can be set by the parameter setting unit 231 when the wide-angle OCT scan pattern is the aforementioned curvilinear scan pattern (for example, the spiral scan pattern) will be described with reference to FIGS. 9A to 9D.

[0113] Note that the focus control parameters that can be set by the parameter setting unit 231 are not limited to these examples, and may be any focus control parameters that satisfy the conditions required in this embodiment.

[0114] In the example shown in FIG. 9A, the horizontal axis of the coordinate system indicates the scan position, and the vertical axis indicates the focal position. The scan position on the horizontal axis is defined as the number n (n = 0, 1, 2, ···, N - 1) of N scan points ordered according to the applied scan pattern. Also, the focal position on the vertical axis is defined as the z coordinate. The focus control parameter in FIG. 9A is applicable when an involute scan pattern that goes from the center to the outer edge of the wide-angle OCT scan application area, such as the involute scan pattern 510 shown in FIG. 8A, is adopted. Hereinafter, as an example, it will be described together with the involute scan pattern 510.

[0115] The first scan position n = 0 in FIG. 9A corresponds to the scan start point (macular center) in the involute scan pattern 510, and the last scan position n = N - 1 corresponds to the scan end point (a position on the outer edge or a position near the outer edge) in the involute scan pattern 510.

[0116] The focal position ζ assigned to the scan start position n = 0 11 is set based on, for example, the z coordinate z1 of the central region 310 (e.g., macular center) shown in FIG. 6B. For example, ζ 11 is set equal to z1, or ζ 11 is set to a value approximately equal to z1.

[0117] The focal position ζ assigned to the scan end position n = N - 1 12 is set based on at least one of, for example, the z coordinates z 21 and z 22 of the peripheral region 320 shown in FIG. 6C. For example, ζ 12 is set equal to z 21 , or ζ 12 is set to a value approximately equal to z 21 , or ζ 12 is set equal to z 22 , or ζ 12 is set equal to z 22 to a value approximately equal to z, or, ζ 12 is z 21 and z 22is set to the values obtained from both sides. z 21 and z 22 ζ from both sides 12 As an example of the case of obtaining ζ, z 21 and z 22 It is possible to use any statistical process such as calculating the average of and z 21 and z 22 or calculating the weighted average of and z 21 and z 22 selecting the larger or smaller value of.

[0118] The focus control parameter shown in FIG. 9A is the coordinate (0, ζ corresponding to the scan start point in the two-dimensional coordinate system (n, z) 11 ) and the coordinate (N - 1, ζ corresponding to the scan end point 12 ) can be set as a smooth curve (for example, a spline curve, a Bézier curve) connecting them.

[0119] The two-dimensional coordinate system (n, z) in the example shown in FIG. 9B is the same as that in the example shown in FIG. 9A. The focus control parameter in FIG. 9B is applicable when a spiral scan pattern from the outer edge to the center of the wide-angle OCT scan application area is adopted, such as the spiral scan pattern 520 shown in FIG. 8B. Hereinafter, as an example, it will be described together with the spiral scan pattern 520.

[0120] The first scan position n = 0 in FIG. 9B corresponds to the scan start point (a position on the outer edge or a position near the outer edge) in the spiral scan pattern 520, and the last scan position n = N - 1 corresponds to the scan end point (the center of the macula) in the spiral scan pattern 520.

[0121] The focal position ζ assigned to the scan start position n = 0 21 can be set in the same manner as, for example, the focal position ζ in FIG. 9A 12 . Also, the focal position ζ assigned to the scan end position n = N - 1 22 can be set in the same manner as, for example, the focal position ζ in FIG. 9A 11 .

[0122] The focus control parameter shown in FIG. 9B is a smooth curve (e.g., a spline curve, a Bézier curve) that connects the coordinates (0, ζ 21 ) corresponding to the scan start point and the coordinates (N - 1, ζ 22 ) corresponding to the scan end point in the two-dimensional coordinate system (n, z). It can be set as such.

[0123] The two-dimensional coordinate system (n, z) in the example shown in FIG. 9C is the same as that in the example shown in FIG. 9A. The focus control parameter in FIG. 9C is applicable when an involute scan pattern is adopted from the center to the outer edge of the wide-angle OCT scan application area, such as the involute scan pattern 510 shown in FIG. 8A. Hereinafter, it will be described as an example together with the involute scan pattern 510.

[0124] The first scan position n = 0 in FIG. 9C corresponds to the scan start point (macular center) in the involute scan pattern 510, and the last scan position n = N - 1 corresponds to the scan end point (a position on the outer edge or a position near the outer edge) in the involute scan pattern 510.

[0125] The focal position ζ 31 assigned to the scan position interval n = [0, n 31 can be set in the same manner as, for example, the focal position ζ 11 in FIG. 9A. Also, the focal position ζ 32 assigned to the scan position interval n = [n 33 , N - 1] can be set in the same manner as, for example, the focal position ζ 12 in FIG. 9A. Further, the focal position ζ 31 assigned to the scan position interval n = (n 32 ), n 31 + 1, n 32 - 1] = [n 32 + 1, n 31 - 1] can be set based on, for example, the focal positions ζ 33 and ζ 32is obtained, for example, by any statistical process. Examples of the statistical values to be obtained include ζ 31 and ζ 33 and the average of ζ 31 and ζ 33 and the weighted average of ζ 31 and ζ 33 and the larger value of ζ 31 and ζ 33 and the smaller value of ζ, etc.

[0126] Similar to the relationship between the focus control parameter shown in FIG. 9A and the focus control parameter shown in FIG. 9B, the stepped focus control parameter shown in FIG. 9C can be inverted. The focus control parameter obtained by the inversion can be applied, for example, when a spiral scan pattern from the outer edge to the center of the wide-angle OCT scan application area is adopted, such as the spiral scan pattern 520 shown in FIG. 8B.

[0127] In addition, it is possible to modify the focus control parameter shown in FIG. 9C. For example, in the scan position interval n = [0, n 31 , a smooth curve (for example, a spline curve, a Bézier curve) connecting the coordinates (0, ζ 31 ) and the coordinates (n 31 , ζ 32 ) can be assigned. Also, in the scan position interval n = [n 32 , N - 1], a smooth curve (for example, a spline curve, a Bézier curve) connecting the coordinates (n 32 , ζ 32 ) and the coordinates (N - 1, ζ 33 ) can be assigned. For example, when a spiral scan pattern from the outer edge to the center of the wide-angle OCT scan application area is adopted, such as the spiral scan pattern 520 shown in FIG. 8B, it is possible to invert the focus control parameter partially replaced by a curve in this way.

[0128] Alternatively, in the scan position interval n = [0, n 31 , the coordinates (0, ζ 31 ) and the coordinates (n 31 , ζ 32A straight line (diagonal line) connecting the two can be assigned. Also, in the interval n = [n 32 , N - 1] of the scan position, a straight line (diagonal line) connecting the coordinate (n 32 , ζ 32 ) and the coordinate (N - 1, ζ 33 ) can be assigned. For example, when a spiral scan pattern 520 as shown in FIG. 8B is adopted, that is, when a spiral scan pattern from the outer edge to the center of the wide-angle OCT scan application area is adopted, it is possible to invert the focus control parameter partially replaced with a diagonal line in this way.

[0129] The two-dimensional coordinate system (n, z) in the example shown in FIG. 9D is the same as that in the example shown in FIG. 9A. The focus control parameter in FIG. 9D is applicable when a spiral scan pattern from the center to the outer edge of the wide-angle OCT scan application area is adopted, for example, like the spiral scan pattern 510 shown in FIG. 8A. Hereinafter, it will be described as an example together with the spiral scan pattern 510.

[0130] The first scan position n = 0 in FIG. 9D corresponds to the scan start point (macular center) in the spiral scan pattern 510, and the last scan position n = N - 1 corresponds to the scan end point (position on the outer edge or position near the outer edge) in the spiral scan pattern 510.

[0131] The focal position ζ 41 assigned to the interval n = [0, n 41 of the scan position can be set in the same manner as, for example, the focal position ζ 11 in FIG. 9A. Also, the focal position ζ 42 assigned to the interval n = [n 42 N - 1] of the scan position can be set in the same manner as, for example, the focal position ζ 12 in FIG. 9A. Further, in the interval n = (n 41 , n 42 ) = [n 41 + 1, n 42 - 1], between the coordinate (n 41 , ζ 41 ) and the coordinate (n 42, ζ 42 A straight line connecting them is assigned.

[0132] Similar to the relationship between the focus control parameters shown in FIG. 9A and the focus control parameters shown in FIG. 9B, the focus control parameters shown in FIG. 9D can be inverted. The focus control parameters obtained by inversion are applicable when an involute scan pattern that goes from the outer edge to the center of the wide-angle OCT scan application area is adopted, such as the involute scan pattern 520 shown in FIG. 8B.

[0133] Also, it is possible to modify the focus control parameters shown in FIG. 9D. For example, for the section of the scan position n=(n 41 , n 42 ) = [n 41 +1, n 42 -1], a smooth curve (for example, a spline curve, a Bézier curve) connecting the coordinates (n 41 , ζ 41 ) and the coordinates (n 42 , ζ 42 ) can be assigned. For example, when an involute scan pattern that goes from the outer edge to the center of the wide-angle OCT scan application area is adopted, such as the involute scan pattern 520 shown in FIG. 8B, it is possible to invert the focus control parameters in which a part is replaced with a curve in this way.

[0134] Examples of the processing executed by the parameter setting unit 231 and examples of the focus control parameters created thereby have been described above, but these are not intended to be limiting, and various modifications are allowed.

[0135] For example, in the example shown in FIG. 6B, the depth position (z coordinate) of one representative point (the center of the macula) within the central region 310 is obtained and used as the depth position of the central region 310. On the other hand, it is possible to obtain the respective depth positions of two or more points within the central region and determine the depth position of the central region from the two or more obtained depth positions. For example, statistical processing can be applied to the two or more depth positions to determine the depth position of the central region. The statistical value obtained from the two or more depth positions may be, for example, any of an average value, a weighted average value, a median value, a mode value, a maximum value, and a minimum value. The same processing can be applied when determining the depth position of the peripheral region.

[0136] When obtaining two or more depth positions within the central region, instead of calculating a single statistical value from these depth positions as described above and using this as the depth position of the central region, information representing the change in the depth position within the central region can be obtained from these depth positions. For example, based on these depth positions, a graph (focus control parameter) representing a curvilinear, linear, or stepped change in the depth position within the central region can be obtained. FIGS. 9A and 9B are examples of curvilinear changes. Although not shown, as an example of a linear change in the depth position within the central region, in the two-dimensional coordinate system shown in FIG. 9C, it is possible to obtain a straight line connecting the coordinates (0, ζ 31 ) and the coordinates (n 31 , ζ 32 ). Also, although not shown, as an example of a stepped change in the depth position within the central region, in the two-dimensional coordinate system shown in FIG. 9C, for the scan position interval n = [0, n 31 , it is possible to set a focus control parameter in which the value of the focal position changes stepwise from ζ 31 to ζ 32 . The same processing can be applied when obtaining the focus control parameter of the peripheral region.

[0137] As described above, the process of obtaining two or more depth positions within the central region and setting the focus control parameters is considered effective, for example, when the width of the central region (the length in the direction orthogonal to the z direction) is relatively wide, or when the change in the depth position within the central region is large (for example, when the difference between the maximum depth position and the minimum depth position within the central region is large). The parameter setting unit 231 may be configured to determine the number (and positions) of points within the central region for which the depth region is obtained according to the size of the width of the central region and / or according to the size of the change in the depth position within the central region. The same process can be applied even when obtaining the focus control parameters for the peripheral region.

[0138] In the example described above, the central region (310) and the peripheral region (320) are separated from each other. In other words, in the example described above, an annular intermediate region exists between the outer edge of the central region and the inner edge of the peripheral region. In other examples, the outer edge of the central region and the inner edge of the peripheral region may coincide.

[0139] More generally, in the present embodiment, the central region and the peripheral region can be arbitrarily defined. For example, the central region and the peripheral region may be defined according to the site of the fundus. As a specific example, a region centered on a predetermined site of the fundus (for example, the center of the macula) and within a predetermined first distance from this center can be set as the central region. Further, a region at a predetermined second distance (a distance greater than or equal to the first distance) or more from this center can be set as the peripheral region. Here, a third distance representing the outer edge of the peripheral region may be further set, or the outer edge of the wide-angle OCT scan application area may be set as the outer edge of the peripheral region. The distance in this example may be the distance in the fundus, an optically calculated distance, or a standard distance obtained from a model eye or clinical data.

[0140] As another definition of the central region and the peripheral region, there is a definition according to the OCT scan. For example, it is possible to set a predetermined first region in the wide-angle OCT scan application area as the central region, and set a predetermined second region different from the second region as the peripheral region. Typically, the first region including the center of the wide-angle OCT scan application area is set as the central region, and the second region located outside this first region is set as the peripheral region.

[0141] In the examples described above, the scan pattern consisting of curves such as the spiral scan pattern has been particularly described, but it is also possible to adopt a scan pattern at least partially consisting of straight lines. For example, by alternately combining the line scan in the x direction and the line scan in the y direction, a spiral scan pattern consisting of a plurality of straight lines can be applied.

[0142] The settings of the wide-angle OCT scan pattern and the focus control parameters (and the scan speed) exemplified above include the setting of the moving speed and / or the moving acceleration of the focal position. For example, in the focus control parameters exemplified in each of FIGS. 9A to 9D, the slope of the graph showing the focus control parameters corresponds to the moving speed, and the change rate of the slope of the graph corresponds to the moving acceleration. Conversely, it is possible to set the focus control parameters through the setting of the moving speed and / or the moving acceleration of the focal position.

[0143] In the focus control parameters exemplified in each of FIGS. 9A to 9D, the focal position (first focal position) applied to the central region is located on the +z side rather than the focal position (second focal position) applied to the peripheral region. That is, the focal length (first focal length) corresponding to the first focal position is set longer than the focal length (second focal length) corresponding to the second focal position. This is according to the shape of the eye to be examined (fundus). However, it is not necessary for the first focal length to be longer than the second focal length.

[0144] The parameter setting unit 231 capable of executing the above-described processing is realized by the cooperation of hardware including a processor and parameter setting software.

[0145] 〈Movement detection unit 232〉 The ophthalmic imaging device 1 includes a fundus camera unit 2 that repeatedly images the eye E to be examined to acquire time-series images. The time-series images acquired by the fundus camera unit 2 are, for example, the observation images described above.

[0146] The movement detection unit 232 analyzes the observation images acquired by the fundus camera unit 2 to detect the movement of the eye E to be examined. For example, the movement detection unit 232 analyzes each image included in the observation images to detect feature points, and obtains the time-series change in the positions of the feature points. The feature points may be, for example, the center, centroid, and contour of the pupil, the center, centroid, and contour of the iris, and the like.

[0147] The scan control unit 213 can control the optical scanner 44 based on the output from the movement detection unit 213 while controlling the optical scanner 44 and the OCT unit 100 according to the wide-angle OCT scan pattern. The control of the optical scanner 44 based on the output from the movement detection unit 213 is so-called tracking control.

[0148] Tracking is executed, for example, by the following series of processes disclosed in Japanese Patent Application Laid-Open No. 2017-153543. First, the movement detection unit 232 registers any frame (front image) of the observation images acquired by the fundus camera unit 2 as a reference image.

[0149] Furthermore, the movement detection unit 232 obtains the change in the position of the feature points in other frames with respect to the position of the feature points in the reference image. This corresponds to obtaining the temporal change in the position of the feature points, that is, obtaining the displacement between the reference image and other frames. If the displacement exceeds the threshold due to blinking or fixation deviation, or if displacement detection becomes impossible, the movement detection unit 232 can register the subsequently acquired frame as a new reference image. Also, the method for obtaining the temporal change in the position of the feature points is not limited to this, and for example, the displacement of the feature points between two consecutive frames may be sequentially obtained.

[0150] Each time the temporal change in the position of the feature points is obtained, the movement detection unit 232 sends control information for canceling this temporal change to the scan control unit 213. The scan control unit 213 corrects the orientation of the optical scanner 44 based on the sequentially input control information.

[0151] The movement detection unit 232 is realized by the cooperation of hardware including a processor and movement detection software.

[0152] 〈User Interface 240〉 The user interface 240 includes a display unit 241 and an operation unit 242. The display unit 241 includes the display device 3. The operation unit 242 includes various operation devices and input devices. The user interface 240 may include a device in which the display function and the operation function are integrated, such as a touch panel. It is also possible to construct an embodiment that does not include at least a part of the user interface 240. For example, the display device may be an external device connected to the ophthalmic imaging device.

[0153] 〈Operation〉 The operation of the ophthalmic imaging device 1 will be described. It is assumed that preparatory processes similar to those in the past, such as input of the patient ID, presentation of the fixation target, adjustment of the fixation position, alignment, focus adjustment, and OCT optical path length adjustment, have already been performed.

[0154] An example of the operation of the ophthalmic imaging device 1 will be described with reference to FIG. 10.

[0155] (S1: Apply a preparatory OCT scan to the fundus to obtain a preparatory image) First, the ophthalmic imaging device 1 applies a preparatory OCT scan to the fundus Ef using the optical scanner 44 and the OCT unit 100. The image construction unit 220 constructs a preparatory image from the data collected by the preparatory OCT scan. The preparatory image is sent to the parameter setting unit 231.

[0156] (S2: Set control parameters) The parameter setting unit 231 sets focus control parameters based on the preparatory image obtained in step S1. The set control parameters are stored, for example, in the storage unit 212.

[0157] In step S2 or at a stage before that, the ophthalmic imaging device 1 may perform settings such as setting the wide-angle OCT scan application area, setting the central area, setting the peripheral area, and setting the scan control parameters. Note that any of these conditions may be fixed conditions, conditions selected from a plurality of options, or conditions manually set by the user. The parameter setting unit 231 may execute the setting of the focus control parameters based on the results of these settings and the preparatory image.

[0158] In this example, it is assumed that the central area 310 and the peripheral area 320 shown in FIG. 5A, the spiral scan pattern 510 shown in FIG. 8A, and the focus control parameters shown in FIG. 9A are applied. Also, it is assumed that the outer edge of the peripheral area 320 defines the outer edge of the wide-angle OCT scan application area.

[0159] (S3: Control the optical scanner based on the scan start position) The scan control unit 213 identifies the scan start position based on the scan control parameters set in step S2 or at an earlier stage, and controls the optical scanner 44 based on this scan start position. As a result, each galvanometer mirror included in the optical scanner 44 is arranged in the orientation corresponding to the scan start position.

[0160] In this example, typically, a fixation mark corresponding to the fixation position for acquiring an image centered on the macula is displayed on the LCD 39, and the center of the wide-angle OCT scan application area is set to the center of the macula. Assuming that the alignment state and fixation state of the eye E to be examined are suitable, the center of the macula is arranged on the optical axis of the measurement arm. Therefore, in this example, each galvanometer mirror of the optical scanner 44 is arranged at the neutral position.

[0161] (S4: Move the OCT focusing lens based on the initial focus position) The focus control unit 214 identifies the initial focus position in focus control based on the focus control parameters set in step S2, and controls the OCT focusing drive unit 43A based on this initial focus position to move the OCT focusing lens 43.

[0162] In this example, the focal position ζ corresponding to the scan start position n = 0 shown in FIG. 9A 11 is identified as the initial focus position, and the control of the OCT focusing drive unit 43A is executed so that the OCT focusing lens 43 is arranged at the position corresponding to this initial focus position ζ. 11

[0163] Note that the control according to step S4 may be executed before the control according to step S3. Also, the control according to step S3 and the control according to step S4 may be performed in parallel.

[0164] (S5: Instruction to start wide-angle OCT scan) After the control according to step S3 and the control according to step S4 are completed, an instruction to start the wide-angle OCT scan is input to the scan control unit 213 and the focus control unit 214. This instruction may be manually given by the user, or may be automatically given by the main control unit 211 in response to satisfaction of a predetermined condition (for example, completion of the control according to step S3 and the control according to step S4).

[0165] (S6: Start the coordinated execution of scan control and focus control) Upon receiving the start instruction for step S5, the scan control unit 213 and the focus control unit 214 start coordinated control, thereby starting the wide-angle OCT scan.

[0166] In this example, based on the focus control parameter (a graph representing the relationship between the scan position n and the focal position z) shown in FIG. 9A, the scan control by the scan control unit 213 and the focus control by the focus control unit 214 are executed.

[0167] More specifically, the scan control unit 213 controls the optical scanner 44 and the OCT unit 100 so as to sequentially apply A-scans to a plurality of scan points (scan positions n = 0 to N-1 shown in FIG. 9A) arranged along the spiral scan pattern 510 shown in FIG. 8A.

[0168] In parallel, when an A-scan is applied to each scan position n shown in FIG. 9A, the focus control unit 214 controls the OCT focusing drive unit 43A so that the OCT focusing lens 43 is arranged at a position corresponding to the focal position z = ζ(n) corresponding to this scan position n.

[0169] Thereby, while moving the focal position according to the focus control parameter shown in FIG. 9A, the fundus Ef can be scanned according to the spiral scan pattern 510 shown in FIG. 8A.

[0170] (S7: Start tracking) In response to the start of the associated control in step S6, or at any timing before the start of this associated control, tracking for correcting the projection position (the application position of the A-scan) of the measurement light LS in accordance with the movement of the eye E to be examined is started. The tracking is executed in the manner described above by the fundus camera unit 2, the movement detection unit 232, the scan control unit 213, and the like. As a result, even when the eye E to be examined moves during the execution of the wide-angle OCT scan, it is possible to apply the spiral scan pattern 510 shown in FIG. 8A.

[0171] (S8: End of wide-angle OCT scan) The wide-angle OCT scan started in step S6 ends in response to, for example, an OCT scan being performed along the spiral scan pattern 510 shown in FIG. 8A.

[0172] Note that the OCT scan along the wide-angle OCT scan pattern is executed a predetermined number of times or more. For example, the OCT scan along the spiral scan pattern 510 can be executed two or more times. In this case, in the next step S9, two or more OCT images can be constructed from two or more data sets collected by these two or more OCT scans, and these two or more OCT images can be synthesized (added and averaged).

[0173] (S9: Construct OCT images according to the wide-angle OCT scan pattern) The image construction unit 220 constructs an OCT image from the data collected by the wide-angle OCT scan executed in steps S6 to S8.

[0174] The spiral scan pattern 510 shown in FIG. 8A is typically defined using a two-dimensional polar coordinate system (r, θ). When using the two-dimensional polar coordinate system (r, θ), the spiral scan pattern 510 is defined, for example, by the following equations: x = cosθ - θ × sinθ, y = sinθ + θ × cosθ.

[0175] In this case, the OCT image constructed in step S9 is also defined using the two-dimensional polar coordinate system (r, θ). That is, the positions of the plurality of A-scan images that make up the OCT image constructed in step S9 are defined using the two-dimensional polar coordinate system (r, θ).

[0176] In this example, since the positions of the plurality of A-scans that make up the spiral scan pattern 510 shown in FIG. 8A respectively correspond to the plurality of scan positions n = 0 to N - 1 shown in FIG. 9A, the positions of the plurality of A-scan images constructed in step S9 also respectively correspond to the plurality of scan positions n = 0 to N - 1. For example, by step S9, the OCT image H1 shown in FIG. 11 is constructed. The OCT image H1 is composed of the A-scan image A(n p ) assigned to each scan position n = n p . Note that each scan position n = n p is defined using the two-dimensional polar coordinate system (r, θ).

[0177] Note that the definition formula of the spiral scan pattern is not limited to this example, and the coordinate system for defining the wide-angle OCT scan pattern and the OCT image is not limited to the two-dimensional polar coordinate system.

[0178] (S10: Apply coordinate transformation to the OCT image) The image construction unit 220 applies a coordinate transformation to the OCT image constructed in step S9.

[0179] For example, when a wide-angle OCT scan pattern including a curved scan pattern defined in a polar coordinate system with the center of the OCT scan application area as the origin is applied, the image construction unit 220 forms an OCT image defined in the polar coordinate system from the data collected by the OCT scan applied to the eye to be examined E according to this curved scan pattern (S9), and converts this OCT image into an image defined in the three-dimensional orthogonal coordinate system (S10).

[0180] When the OCT image H1 shown in FIG. 11 is constructed in step S9, the image construction unit 220, according to the coordinate conversion formula between the two-dimensional polar coordinate system (r, θ) and the two-dimensional orthogonal coordinate system (x, y), for each scan position n=n defined in the two-dimensional polar coordinate system (r, θ) p converts the coordinates to the coordinates defined in the two-dimensional orthogonal coordinate system (x, y). This coordinate conversion formula is, for example, the aforementioned (x = cosθ - θ×sinθ, y = sinθ + θ×cosθ).

[0181] By such coordinate conversion, for example, a group of OCT images H2(m) (m = 1, 2, ···, M) shown in FIG. 12 are obtained. Each OCT image H2(m) is a B-scan image along the x direction and is defined using the two-dimensional orthogonal coordinate system (x, z). Further, the M OCT images H2(1) to H2(M) are arranged along the y direction. Thus, the M OCT images H2(1) to H2(M) are defined using the three-dimensional orthogonal coordinate system (x, y, z).

[0182] (S11: Construct a 3D image from the coordinate-converted OCT image) The image construction unit 220 can construct a 3D image from the OCT image after coordinate conversion obtained in step S10.

[0183] In this example, in step S10, for example, M OCT images H2(1) to H2(M) which are stack data are obtained. The image construction unit 220 can voxelize the M OCT images H2(1) to H2(M) to construct volume data.

[0184] (S12: Display the rendered image of the 3D image) The image construction unit 220 can render the 3D image constructed in step S11. The main control unit 211 can cause the display unit 241 to display the rendered image thus obtained.

[0185] 〈Operation and Effect〉 The operation and effect of the exemplary embodiment will be described.

[0186] The ophthalmic imaging apparatus (1) according to an exemplary embodiment includes a data collection unit, an image construction unit, a focal position changing unit, a scan control unit, and a focus control unit.

[0187] The data collection unit applies an OCT scan to the eye to be examined (E) to collect data. In the above example, the data collection unit includes an OCT unit 100 and elements (a retroreflector 41, an OCT focusing lens 43, an optical scanner 44, an objective lens 22, etc.) in the fundus camera unit 2 that constitutes the measurement arm.

[0188] The image construction unit constructs an image from the data collected by the data collection unit. In the above example, the image construction unit includes an image construction unit 220.

[0189] The focal position changing unit is provided in the optical path (measurement arm) of the measurement light projected onto the eye to be examined (E) by the data collection unit, and changes the position of the focus of the measurement arm. In the above example, the focal position changing unit includes an OCT focusing lens 43 and an OCT focusing drive unit 43A.

[0190] The scan control unit controls the data collection unit according to a scan pattern (wide-angle OCT scan pattern) including a continuous first partial pattern for the central region (310) of the OCT scan application area (wide-angle OCT scan application area) and a continuous second partial pattern for the peripheral region (320). In the above example, the scan control unit includes a scan control unit 213.

[0191] The focus control unit controls the focus position changing unit to apply the first focus position in parallel with the application of the OCT scan to at least a part of the first partial pattern. Further, the focus control unit controls the focus position changing unit to apply a second focus position different from the first focus position in parallel with the application of the OCT scan to at least a part of the second partial pattern. In the above example, the focus control unit includes the focus control unit 214. Also, in the above example, at least a part of the first partial pattern corresponds to at least a part of the central region 310, and the first focus position corresponds to, for example, the z coordinate ζ in FIG. 9A. 11 Corresponds to. Further, in the above example, at least a part of the second partial pattern corresponds to at least a part of the peripheral region 320, and the second focus position corresponds to, for example, the z coordinate ζ in FIG. 9A. 12 Corresponds to.

[0192] According to such an embodiment, a scan pattern including a continuous first partial pattern for the central region and a continuous second partial pattern for the peripheral region can be applied. Considering the shape of the eyeball (the concave curved shape of the fundus), the central region is disposed at a relatively deep position of the eyeball, and the peripheral region is disposed at a relatively shallow position. Therefore, the focal position suitable for the central region and the focal position suitable for the peripheral region are different. In addition to the scan control according to the above scan pattern, this embodiment can apply the first focus position to the central region (first partial pattern) and the second focus position to the peripheral region (second partial pattern). This makes it possible to perform a wide-angle OCT scan while moving the focus position at a practical speed. Therefore, according to this embodiment, it is possible to acquire a high-quality OCT image while performing a wide-angle OCT scan at high speed.

[0193] When a raster scan is applied to a wide-angle OCT scan as in the conventional case, several B scans pass through both the central region and the peripheral region. It is practically impossible to switch and apply two or more focal positions including the first focal position and the second focal position while performing such B scans at high speed.

[0194] In this embodiment, the scan pattern may include a curved scan pattern defined in a polar coordinate system with the center of the OCT scan application area as the origin.

[0195] For setting the curved scan pattern, for example, the structural characteristics and control characteristics of the optical scanner (44), the required scan speed, the required scan density, etc. can be considered.

[0196] In this embodiment, the curved scan pattern may be a spiral scan pattern (510) from the center to the outer edge of the OCT scan application area. Alternatively, the curved scan pattern may be a spiral scan pattern (520) from the outer edge to the center of the OCT scan application area.

[0197] As another example of the curved scan pattern, there is a concentric circle scan pattern.

[0198] In this embodiment, the image construction unit (220) can form an image (OCT image H1) defined in a polar coordinate system from the data collected by the OCT scan applied to the eye to be examined (E) according to the curved scan pattern. Further, the image construction unit (220) can convert this image (OCT image H1) defined in the polar coordinate system into an image (OCT image H2(m)) defined in a three-dimensional orthogonal coordinate system.

[0199] According to such a configuration, it is possible to construct an OCT image defined in a three-dimensional orthogonal coordinate system in which image processing and analysis can be easily performed from the OCT image obtained using the curved scan pattern.

[0200] In this embodiment, the first focal distance corresponding to the first focal position applied to the central region (first partial pattern) may be set to be longer than the second focal distance corresponding to the second focal position applied to the peripheral region (second partial pattern).

[0201] According to such a configuration, it is possible to perform a wide-angle OCT scan at high speed while changing the focal position according to the shape of the eyeball, and it is possible to acquire high-quality OCT images.

[0202] In the ophthalmic imaging apparatus (1) according to the present embodiment, prior to the wide-angle OCT scan according to the wide-angle OCT scan pattern, a preparatory OCT scan may be applied to the eye to be examined (E) by the data collection unit. When the preparatory OCT scan is performed, the image construction unit (220) can construct a preparatory image (G) from the data collected by the preparatory OCT scan. Further, the parameter setting unit (231) of the ophthalmic imaging apparatus (1) according to the present embodiment can set one or more focus control parameters based on the preparatory image (G) constructed by the image construction unit (220). In addition, the focus control unit (214) can execute the control of the focal position changing unit according to one or more focus control parameters set by the parameter setting unit (231).

[0203] Here, the focus control parameter may be, for example, a graph as shown in FIG. 9A, or may be one or more numerical values. As an example of the latter, a numerical value indicating the focal position (for example, the z coordinate ζ 11 and ζ 12 ) may be used.

[0204] According to such a configuration, the focus control parameter can be set based on the actual shape of the eye to be examined (for example, the fundus). Thereby, it is possible to further improve the quality of the acquired OCT image.

[0205] In the present embodiment, the one or more focus control parameters constructed from the preparatory image may include a focal position change range including a first focal position and a second focal position. In the above example, for example, the focus control parameter in FIG. 9A includes the focal position change range [ζ 12 , ζ 11 as information.

[0206] According to such a configuration, it is possible to set the range for changing the focal position based on a preparatory image (that is, based on the actual shape of the eye to be examined).

[0207] In the present embodiment, one or more focus control parameters constructed from the preparatory image may include at least one of the moving speed and moving acceleration of the focal position. In the above example, for example, the focus control parameter consisting of a smooth curve shown in FIG. 9A includes the moving speed and moving acceleration of the focal position of the measurement arm as information.

[0208] According to such a configuration, it is possible to set the moving speed and moving acceleration of the focal position based on a preparatory image (that is, based on the actual shape of the eye to be examined).

[0209] The ophthalmic imaging apparatus (1) according to the present embodiment may further include an imaging unit (fundus camera unit 2) that repeatedly images the eye to be examined (E), and a movement detection unit (232) that analyzes the time-series images acquired by the imaging unit to detect the movement of the eye to be examined. Further, the data collection unit may include an optical scanner (44) that deflects light for OCT scanning. Furthermore, the scan control unit (213) can control the optical scanner (44) based on the output from the movement detection unit (232) while controlling the data collection unit according to a wide-angle OCT scan pattern.

[0210] According to such a configuration, it is possible to perform a wide-angle OCT scan while performing tracking for correcting the projection position of the measurement light in accordance with the movement of the eye to be examined. Thereby, even if the eye to be examined moves during the wide-angle OCT scan, it is possible to suitably perform a scan according to the wide-angle OCT scan pattern. Also, it is possible to avoid interruption and redoing of the scan.

[0211] Although the above example describes the case where an OCT scan is applied to the fundus (Ef), embodiments can be configured that can achieve the same actions and effects on the anterior eye segment (cornea, lens, iris, angle, etc.). The focus control parameter is set according to the shape of the site to be subjected to the OCT scan.

[0212] Exemplary embodiments provide a method for controlling an ophthalmic imaging device. The ophthalmic imaging device to which this control method is applied includes a data collection unit that applies an OCT scan to an eye to be examined to collect data, an image construction unit that constructs an image from the collected data, and a focus position changing unit provided in the optical path of the measurement light projected onto the eye to be examined by the data collection unit.

[0213] This control method includes a scan control step and a focus control step. The scan control step controls the data collection unit according to a scan pattern including a continuous first partial pattern for the central region of the OCT scan application area and a continuous second partial pattern for the peripheral region. The focus control step controls the focus position changing unit to apply a first focus position in parallel with the application of the OCT scan to at least a part of the first partial pattern, and to apply a second focus position different from the first focus position in parallel with the application of the OCT scan to at least a part of the second partial pattern.

[0214] For such a control method of an ophthalmic imaging device, any of the matters described in the exemplary embodiments can be combined.

[0215] Exemplary embodiments provide a program that causes such a control method to be executed by an ophthalmic imaging device. For this program, any of the matters described in the exemplary embodiments can be combined.

[0216] In addition, it is possible to create a computer-readable non-transitory recording medium storing such a program. It is possible to combine any of the matters described in the exemplary embodiments with this recording medium. Further, this non-transitory recording medium may be in any form, and examples thereof include magnetic disks, optical disks, magneto-optical disks, semiconductor memories, and the like.

[0217] According to the method, program, or recording medium according to the exemplary embodiments, it is possible to acquire a high-quality OCT image while performing a wide-angle OCT scan at high speed. Further, operations and effects according to the matters combined with the method, program, or recording medium according to the exemplary embodiments are achieved.

[0218] The configurations described above are merely examples of embodiments of the present invention. Therefore, it is possible to perform any modifications (omission, substitution, addition, etc.) within the scope of the gist of the present invention.

Description of Reference Numerals

[0219] 1 Ophthalmic imaging device 100 OCT unit 210 Control unit 211 Main control unit 212 Storage unit 213 Scan control unit 214 Focus control unit 220 Image construction unit 230 Data processing unit 231 Parameter setting unit 232 Movement detection unit 240 User interface 241 Display unit 242 Operation unit

Claims

1. A data collection unit that applies an optical coherence tomography (OCT) scan to an eye to be examined to collect data; An image construction unit that constructs an image from the data collected by the data collection unit; A focal position changing unit provided in the optical path of the measurement light projected onto the eye to be examined by the data collection unit; A scan control unit that controls the data collection unit according to a scan pattern including a continuous first partial pattern for a central region of an OCT scan application area and a continuous second partial pattern for a peripheral region; A focus control unit that controls the focal position changing unit to apply a first focal position in parallel with the application of an OCT scan to at least a part of the first partial pattern and to apply a second focal position different from the first focal position in parallel with the application of an OCT scan to at least a part of the second partial pattern; A parameter setting unit that sets focus control parameters provided to the focus control unit; comprising; Before the OCT scan according to the scan pattern, the data collection unit applies a preparatory OCT scan passing through both the central region and the peripheral region to the eye to be examined; The image construction unit constructs a preparatory image from the data collected by the preparatory OCT scan; The parameter setting unit sets one or more focus control parameters based on the preparatory image constructed by the image construction unit; After the setting of the one or more focus control parameters by the parameter setting unit, the scan control unit causes the data collection unit to execute the OCT scan according to the scan pattern; In parallel with the OCT scan according to the scan pattern, the focus control unit executes control of the focal position changing unit according to the one or more focus control parameters set by the parameter setting unit. An ophthalmic imaging device characterized by the above.

2. The preparatory OCT scan includes two B scans orthogonal to each other. The ophthalmic imaging device according to claim 1, characterized by the above.

3. The one or more focus control parameters include a focal position change range including the first focal position and the second focal position. The ophthalmic imaging device according to claim 1 or 2, characterized by the above.

4. The one or more focus control parameters include at least one of a moving speed and a moving acceleration of the focal position. The ophthalmic imaging apparatus according to any one of claims 1 to 3, characterized in that...

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