Ophthalmic imaging equipment

Abstract

To acquire a high-quality OCT image while performing a wide-angle OCT scan at a high speed.SOLUTION: An ophthalmology imaging apparatus according to an embodiment performs control of a focus position change part based on a focus control parameter while executing an OCT scan according to a spiral scan pattern to the outer edge of an OCT scan application area from the yellow spot center or a spiral scan pattern to the yellow spot center from the outer edge after setting a focus control parameter based on a preparatory image constructed by the preparatory OCT scan including two or more B-scans. This control is performed according to a smooth curved, stepped, or polygonal line-shaped pattern that connects the start point and the end point of the spiral scan pattern.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an ophthalmologic imaging apparatus. [Background technology]

[0002] The importance of diagnostic imaging and image analysis is increasing in ophthalmology. In particular, the application of optical coherence tomography (OCT) to ophthalmology has accelerated this trend. OCT enables three-dimensional imaging of the examined eye and three-dimensional structural and functional analysis, and is effective in obtaining the distribution of various measurement values, for example.

[0003] In recent years, efforts have been made to expand the OCT scan range, i.e., to widen the field of view of OCT. For example, in order to scan a wide range from the center to the periphery of the fundus, devices have been developed that expand the deflection angle of optical scanners (such as galvanometer mirrors) and optimize the structure, control, and imaging accordingly (see, for example, Patent Documents 1 and 2).

[0004] When OCT scans (generally raster scans) are applied to a wide area of ​​the fundus, image quality deteriorates due to the influence of aberrations in the ocular optical system, particularly in areas away from the center of the fundus (called the periphery). This is because the aberrations of the eye are greater in the periphery than in the center of the fundus (see, for example, Non-Patent Document 1).

[0005] Focus control can be considered to eliminate this degradation in image quality, but because the speed of focus control is significantly slower than the speed of OCT scanning (e.g., the repetition rate of A-scans), it is not practical to perform focus control while applying high-speed raster scanning to a wide area of ​​the fundus. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2017-086311 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-047113 [Non-patent literature]

[0007] [Non-Patent Document 1] JAMES POLANS, 4 others, "Wide-field optical model of the human eye with asymmetrically tilted and decentered lens that reproduces measured ocular aberrations", Optica, February 2015, Vol.2, No.2, p.124-134 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to obtain high-quality OCT images while performing wide-angle OCT scans at high speed. [Means for solving the problem]

[0009] A first aspect of an exemplary embodiment is an ophthalmic imaging device including a data collection unit that collects data by applying an optical coherence tomography (OCT) scan to a test eye, an image construction unit that constructs an image from the data collected by the data collection unit, a focus position change unit provided in an optical path of measurement light projected onto the test eye 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 focus position change unit to apply a first focus position in parallel with application of an OCT scan to at least a portion 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 portion of the second partial pattern.

[0010] A second aspect of the exemplary embodiment is an ophthalmic imaging device of the first aspect, wherein the scan pattern includes a curved 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 an ophthalmic imaging device of the second aspect, wherein the curved scan pattern is either a spiral scan pattern extending from the center of the OCT scan application area toward the outer edge, or a spiral scan pattern extending from the outer edge of the OCT scan application area toward the center.

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

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

[0014] A sixth aspect of an exemplary embodiment is an ophthalmic imaging device according to any one of the first to fifth aspects, wherein, before an OCT scan according to the scan pattern, the data collection unit applies a preparatory OCT scan to the test eye, the image construction unit constructs a preparatory image from 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, and the focus control unit controls 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 apparatus of the sixth aspect, wherein the one or more focus control parameters include a focus position change range that includes the first focus position and the second focus position.

[0016] An eighth aspect of the exemplary embodiment is the ophthalmologic imaging apparatus according to 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 a focus position.

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

[0018] A tenth aspect of an exemplary embodiment is a method for controlling an ophthalmic imaging device including a data collection unit that applies an optical coherence tomography (OCT) scan to a test eye to collect data, an image construction unit that constructs an image from the data collected by the data collection unit, and a focus position change unit provided in an optical path of measurement light projected onto the test eye by the data collection unit, the method including a scan control step of controlling the data collection unit according to a scan pattern that includes 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 change unit to apply a first focus position in parallel with application of an OCT scan to at least a portion 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 portion 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 having the program of the eleventh aspect recorded thereon. [Effects of the Invention]

[0021] According to an exemplary embodiment, it is possible to obtain high quality OCT images while performing wide-angle OCT scans at high speed. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a schematic diagram illustrating an example of the configuration of an ophthalmologic imaging apparatus according to an exemplary embodiment. [Figure 2] 1 is a schematic diagram illustrating an example of the configuration of an ophthalmologic imaging apparatus according to an exemplary embodiment. [Figure 3] 1 is a schematic diagram illustrating an example of the configuration of an ophthalmologic imaging apparatus according to an exemplary embodiment. [Figure 4] 1 is a schematic diagram illustrating an example of the configuration of an ophthalmologic imaging apparatus according to an exemplary embodiment. [Figure 5A] FIG. 2 is a schematic diagram for explaining an example of processing executed by an ophthalmologic imaging apparatus according to an exemplary embodiment. [Figure 5B] FIG. 2 is a schematic diagram for explaining an example of processing executed by an ophthalmologic imaging apparatus according to an exemplary embodiment. [Figure 6A] FIG. 2 is a schematic diagram for explaining an example of processing executed by an ophthalmologic imaging apparatus according to an exemplary embodiment. [Figure 6B] FIG. 2 is a schematic diagram for explaining an example of processing executed by an ophthalmologic imaging apparatus according to an exemplary embodiment. [Figure 6C] FIG. 2 is a schematic diagram for explaining an example of processing executed by an ophthalmologic imaging apparatus according to an exemplary embodiment. [Figure 7] FIG. 2 is a schematic diagram for explaining an example of processing executed by an ophthalmologic imaging apparatus according to an exemplary embodiment. [Figure 8A] FIG. 2 is a schematic diagram for explaining an example of processing executed by an ophthalmologic imaging apparatus according to an exemplary embodiment. [Figure 8B] FIG. 2 is a schematic diagram for explaining an example of processing executed by an ophthalmologic imaging apparatus according to an exemplary embodiment. [Figure 9A] FIG. 2 is a schematic diagram for explaining an example of processing executed by an ophthalmologic imaging apparatus according to an exemplary embodiment. [Figure 9B] FIG. 2 is a schematic diagram for explaining an example of processing executed by an ophthalmologic imaging apparatus according to an exemplary embodiment. [Figure 9C] FIG. 2 is a schematic diagram for explaining an example of processing executed by an ophthalmologic imaging apparatus according to an exemplary embodiment. [Figure 9D] FIG. 2 is a schematic diagram for explaining an example of processing executed by an ophthalmologic imaging apparatus according to an exemplary embodiment. [Figure 10] 10 is a flowchart illustrating an example of the operation of an ophthalmologic imaging apparatus according to an exemplary embodiment. [Figure 11] FIG. 10 is a schematic diagram for explaining an example of the operation of the ophthalmologic imaging apparatus according to the exemplary embodiment. [Figure 12] FIG. 10 is a schematic diagram for explaining an example of the operation of the ophthalmologic imaging apparatus according to the exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] An ophthalmic imaging apparatus, a control method thereof, a program, and a recording medium according to exemplary embodiments will be described in detail with reference to the drawings. The disclosures of the documents cited in this specification and any other known technologies may be incorporated into the embodiments. Furthermore, unless otherwise specified, no distinction is made between "image data" and an "image" based on the image data. Similarly, unless otherwise specified, no distinction is made between a "region" of the subject's eye and an "image" thereof.

[0024] An ophthalmic imaging apparatus according to an exemplary embodiment is capable of measuring the fundus of a living eye using Fourier-domain OCT (e.g., 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. Furthermore, the target to which OCT is applied is not limited to the fundus, and may be any part of the eye, such as the anterior segment or the vitreous body.

[0025] Exemplary embodiments may be capable of processing images acquired by modalities other than OCT. For example, exemplary embodiments may be capable of processing images acquired by any of a fundus camera, SLO, slit lamp microscope, and ophthalmic surgical microscope. An ophthalmic imaging device according to exemplary embodiments may include any of a fundus camera, SLO, slit lamp microscope, and ophthalmic surgical microscope.

[0026] Images of the subject's eye that can be processed by exemplary embodiments may include images obtained by analyzing images acquired by any modality. Examples of such analyzed images include pseudocolored images (e.g., segmented pseudocolor images), images consisting of only a portion of the original image (e.g., segmented images), images obtained by analyzing OCT images that represent the distribution of tissue thickness (e.g., layer thickness maps, layer thickness graphs), images that represent the shape of tissue (e.g., curvature maps), and images that represent the distribution of lesions (e.g., lesion maps).

[0027] <composition> The ophthalmic imaging apparatus 1 of the exemplary embodiment shown in FIG. 1 includes a fundus camera unit 2, an OCT unit 100, and an arithmetic and control unit 200. The fundus camera unit 2 is provided with an optical system and mechanisms for acquiring a front image of the subject's eye. The OCT unit 100 is provided with a portion of the optical system and mechanisms for performing OCT. Other portions of the optical system and mechanisms for performing OCT are provided in the fundus camera unit 2. The arithmetic and control unit 200 includes one or more processors that perform various calculations and controls. In addition to these, the ophthalmic imaging apparatus 1 may be provided with optional elements or units such as members for supporting the subject's face (such as a chin rest or forehead rest) and a lens unit for switching the target region for OCT (for example, an attachment for anterior segment OCT).

[0028] In this specification, the term "processor" refers to 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), or an FPGA (Field Programmable Gate Array)). The processor realizes the functions according to the embodiment by, for example, reading and executing a program stored in a memory circuit or a storage device.

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

[0030] The fundus camera unit 2 includes an illumination optical system 10 and an imaging optical system 30. The illumination optical system 10 irradiates illumination light onto the subject's eye E. The imaging optical system 30 detects return light of the illumination light from the subject's eye E. The measurement light from the OCT unit 100 is guided to the subject's eye E through an optical path within the fundus camera unit 2, and the return light is guided to the OCT unit 100 through the same optical path.

[0031] Light (observation illumination light) output from an observation light source 11 of an illumination optical system 10 is reflected by a concave mirror 12, passes through a condenser lens 13, and is transmitted through a visible light cut filter 14 to become near-infrared light. The observation illumination light is then focused near an imaging light source 15, reflected by a mirror 16, and passes through a relay lens system 17, a relay lens 18, an aperture 19, and a relay lens system 20. The observation illumination light is then reflected by the peripheral portion (the area surrounding the hole) of a perforated mirror 21, passes through a dichroic mirror 46, and is refracted by an objective lens 22 to illuminate the subject's eye E (fundus oculi Ef). Return light of the observation illumination light from the subject's eye E is refracted by the objective lens 22, passes through the dichroic mirror 46, passes through a hole formed in the central region of the perforated mirror 21, passes through a dichroic mirror 55, passes through an imaging focusing lens 31, and is reflected by a mirror 32. Furthermore, this returned 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 returned light at a predetermined frame rate. The focus (focal position) of the photographing optical system 30 is adjusted to match the fundus Ef or the anterior segment of the eye.

[0032] Light (photography illumination light) output from the photography light source 15 is irradiated onto the fundus oculi Ef through the same path as the observation illumination light. Return light of the photography illumination light from the subject's eye 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 a mirror 36, and is imaged by an imaging lens 37 on the light-receiving surface of an image sensor 38.

[0033] A 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, reflected by the mirror 32, passes through the photographing focusing lens 31 and the dichroic mirror 55, and passes through the hole in the aperture mirror 21. The light beam that has passed through the hole in 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's eye E determined by the fixation target can be changed. Examples of fixation positions 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 region far removed from the macula (periphery of the fundus). A graphical user interface (GUI) or the like for specifying at least one of these 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's 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 elements (such as light-emitting diodes) are arranged in a matrix (array) can be used instead of a display device. In this case, the fixation position of the subject's eye E based on the fixation target can be changed by selectively turning on the plurality of light-emitting elements. As another example, a fixation target with a changeable fixation position can be generated using one or more movable light-emitting elements.

[0036] The alignment optical system 50 generates an alignment index used to align the optical system with respect to the subject's eye E. Alignment light output from a light-emitting diode (LED) 51 passes through an aperture 52, an aperture 53, and a relay lens 54, is reflected by a dichroic mirror 55, passes through the hole in the aperture mirror 21, transmits through the dichroic mirror 46, and is projected onto the subject's eye E via the objective lens 22. Return light of the alignment light from the subject's eye E (corneal reflected light, etc.) is guided to the image sensor 35 via the same path as the return light of the observation illumination light. Manual alignment or automatic alignment can be performed based on the received light image (alignment index image).

[0037] As in the conventional example, 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 subject's eye E and the optical system changes in the x and y directions, the two bright spot images displace together in the x and y directions. When the relative position between the subject's eye E 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 subject's eye E and the optical system in the z direction matches the predetermined working distance, the two bright spot images overlap. When the position of the subject's eye E matches the position of the optical system in the x and y directions, two bright spot images are presented within or near a specified alignment target. When the distance between the subject's eye E and the optical system in the z direction matches the working distance and the position of the subject's eye E matches the position of the optical system in the x and y directions, 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 displays the two bright spot images together with the observed image of the subject's eye E on the display unit 241, and the user operates the moving mechanism 150 using the operation unit 242 while referring to the two displayed bright spot images.

[0039] The focusing optical system 60 generates a split index used for focus adjustment of the subject's eye E. The focusing optical system 60 moves along the optical path (illumination optical path) of the illumination optical system 10 in conjunction with movement of the photographing focusing lens 31 along the optical path (photographing optical path) of the photographing optical system 30. The reflecting rod 67 is inserted into and removed from the illumination optical path. When performing focus adjustment, the reflecting surface of the reflecting rod 67 is tilted and positioned in the illumination optical path. Focusing light output from the LED 61 passes through the relay lens 62, is split into two beams by the split index plate 63, passes through the two-hole diaphragm 64, is reflected by the mirror 65, and is first imaged and reflected on the reflecting surface of the reflecting rod 67 by the condenser lens 66. The focusing light then passes through the relay lens 20, is reflected by the aperture mirror 21, passes through the dichroic mirror 46, and is projected onto the subject's eye E via the objective lens 22. The return light (fundus reflected light, etc.) of the focusing light from the subject's eye E passes through the same path as the return light of the alignment light and is guided to the image sensor 35. Manual focusing or autofocusing can be performed based on the received light image (split target image).

[0040] Diopter correction lenses 70 and 71 can be selectively inserted into the photographing 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 severe hyperopia. The diopter correction lens 71 is a minus lens (concave lens) for correcting severe 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. The measurement arm is provided with, in order from the OCT unit 100 side, a collimator lens unit 40, a retroreflector 41, a dispersion compensation member 42, an OCT focusing lens 43, an optical scanner 44, and a relay lens 45.

[0042] The retroreflector 41 is movable in the direction of the arrow shown in Figure 1, thereby changing the length of the measurement arm. Changing the length of the measurement arm is used, for example, to correct the optical path length according to the axial length of the eye, adjust the interference state, and so on.

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

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

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

[0046] <OCT Unit 100> As shown 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 light from a wavelength-tunable light source (swept-wavelength light source) into measurement light and reference light, and generates interference light by superimposing the return light of the measurement light from the subject's eye E on the reference light that has passed through the reference light path, 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 and control unit 200.

[0047] Light source unit 101 includes, for example, a near-infrared wavelength-tunable laser that changes the wavelength of output light at high speed. Light L0 output from light source unit 101 is guided by optical fiber 102 to polarization controller 103, where its polarization state is adjusted. Light L0 is further guided by optical fiber 104 to fiber coupler 105, where it is split into measurement light LS and reference light LR. The optical path of measurement light LS is called a measurement arm, and the optical path of reference light LR is called a reference arm.

[0048] The reference light LR is guided by an optical fiber 110 to a collimator 111, where it is converted into a parallel beam, and then guided to a retroreflector 114 via an optical path length correction element 112 and a dispersion compensation element 113. The optical path length correction element 112 acts to match the optical path length of the reference light LR with that of the measurement light LS. The dispersion compensation element 113, together with a dispersion compensation element 42 arranged in the measurement arm, acts to match the dispersion characteristics between the reference light LR and the measurement light LS. The retroreflector 114 is movable along the optical path of the reference light LR incident thereon, thereby changing the length of the reference arm. Changing the reference arm length is used, for example, to correct the optical path length according to the axial length of the eye, adjust the interference state, and so on.

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

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

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

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

[0053] A clock KC is supplied to the data collection system 130 from the light source unit 101. The clock KC is generated in the light source unit 101 in synchronization with the output timing of each wavelength swept within a predetermined wavelength range by the 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 the branched lights, combines the branched lights, detects the resulting combined light, and generates the clock KC based on the detection result. The data collection system 130 samples the detection signal input from the detector 125 based on the clock KC. The data collection system 130 sends the sampling result to the arithmetic and control unit 200.

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

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

[0056] <Control unit 210> The control unit 210 executes various types of control. The control unit 210 includes a main control unit 211 and a storage unit 212. As shown in FIG. 4 , the control unit 210 of this embodiment also 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 (including the elements shown in FIGS. 1 to 4) of the ophthalmologic imaging apparatus 1. The main control unit 211 is realized by cooperation between hardware including the processor and control software.

[0058] The main controller 211 can operate the scan controller 213 and the focus controller 214 in a coordinated (synchronous) manner, thereby allowing the OCT scan and focus adjustment to be performed in a coordinated (synchronous) manner.

[0059] The imaging focusing driver 31A moves the imaging focusing 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 controller 211. The retroreflector (RR) driver 41A moves the retroreflector 41 provided in the measurement arm under the control of the main controller 211. The OCT focusing driver 43A moves the OCT focusing lens 43 arranged in the measurement arm under the control of the main controller 211. The optical scanner 44 provided in the measurement arm operates under the control of the main controller 211. The retroreflector (RR) driver 114A moves the retroreflector 114 arranged in the reference arm under the control of the main controller 211. Each of the above drivers includes an actuator such as a pulse motor that operates under the control of the main controller 211.

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

[0061] <Storage section 212> The storage unit 212 stores various types of data, such as OCT images, fundus images, information about the subject's eye, and control parameters.

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

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

[0064] The scan control parameters are parameters that indicate the content of control over the optical scanner 44. Examples of scan control parameters include a parameter that indicates a scan pattern, a parameter that indicates a scan speed, and a parameter that indicates a 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 that indicate the content of control over the OCT focusing drive unit 43A. Examples of focus control parameters include a parameter that indicates the focal position of the measurement arm, a parameter that indicates the moving speed of the focal position, and a parameter that indicates the moving acceleration of the focal position. The parameter that indicates the focal position is, for example, a parameter that indicates the position of the OCT focusing lens 43. The parameter that indicates the moving speed of the focal position is, for example, a parameter that indicates the moving speed of the OCT focusing lens 43. The parameter that indicates the moving acceleration of the focal position is, for example, a parameter that indicates the moving acceleration of the OCT focusing lens 43. The moving speed may 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 the scan control parameters. The scan control unit 213 may further control the light source unit 101. Details of the processing performed 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 cooperation between hardware including a processor and scan control software.

[0067] <Focus control unit 214> The focus control unit 214 controls the OCT focusing driver 43A based on the focus control parameters. The details of the processing performed 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 cooperation between hardware including a processor and focus control software.

[0068] <Image Construction Unit 220> The image constructing unit 220 includes a processor, and forms OCT image data of the fundus oculi Ef based on signals (sampling data) input from the data collecting 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, as in conventional Fourier-domain OCT, noise removal (noise reduction), filtering, fast Fourier transform (FFT), etc. In the case of other types of OCT devices, the image constructor 220 performs known processes according to the type.

[0070] The image constructing unit 220 forms three-dimensional data of the fundus oculi Ef based on the signal input from the data collecting system 130. This three-dimensional data is three-dimensional image data that expresses a three-dimensional region (volume) of the fundus oculi Ef. This three-dimensional image data means image data in which pixel positions are defined by a three-dimensional coordinate system. Examples of three-dimensional image data include stack data and volume data.

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

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

[0073] The image constructor 220 performs rendering on the 3D image data to form an image for display. Examples of applicable rendering methods include volume rendering, surface rendering, maximum intensity projection (MIP), minimum intensity projection (MIP), and multiplanar reconstruction (MPR).

[0074] The image constructing unit 220 can form an OCT en-face image based on the three-dimensional image data. For example, the image constructing unit 220 can construct projection data by projecting the three-dimensional image data in the z direction (A-line direction, depth direction). The image constructing unit 220 can also construct a shadowgram by projecting a portion of the three-dimensional image data in the z direction.

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

[0076] The ophthalmologic imaging device 1 may be capable of performing OCT angiography (OCT-angiography). OCT angiography is an imaging technique that constructs images in which retinal blood vessels and choroidal blood vessels are emphasized (see, for example, JP 2015-515894 A). Generally, fundus tissue (structure) does not change over time, but the blood flow portion inside the blood vessels changes over time. In OCT angiography, an image is generated by emphasizing the portion (blood flow signal) in which such temporal changes exist. Note that OCT angiography is also called OCT motion contrast imaging. Furthermore, images obtained by OCT angiography are called angiographic images, angiograms, motion contrast images, etc.

[0077] When OCT angiography is performed, the ophthalmologic imaging apparatus 1 repeatedly scans the same region of the fundus Ef a predetermined number of times. For example, the repeated scans can be performed along a trajectory between two points on a predetermined scan pattern (e.g., a spiral scan pattern). The image construction unit 220 can construct a motion contrast image from the data set collected by the data acquisition system 130 during the repeated scans. This motion contrast image is an angiography image that emphasizes the temporal change in interference signals caused by blood flow in the fundus Ef. Typically, OCT angiography is applied to a three-dimensional region of the fundus Ef, and an image showing the three-dimensional distribution of blood vessels in the fundus Ef is obtained.

[0078] When OCT angiography is performed, the image constructing unit 220 can construct any two-dimensional angiography image data and / or any pseudo three-dimensional angiography image data from the three-dimensional angiography image data. For example, the image constructing unit 220 can construct two-dimensional angiography image data representing any cross section of the fundus Ef by applying multiplanar 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 types of data processing to the image of the subject's eye E. For example, the data processing unit 230 is realized by cooperation between hardware including a processor and data processing software.

[0081] The data processing unit 230 can perform registration between two images acquired of the fundus oculi Ef. For example, the data processing unit 230 can perform registration between three-dimensional image data acquired by OCT and a front image acquired by the fundus camera unit 2. The data processing unit 230 can also perform registration between two OCT images acquired by OCT. The data processing unit 230 can also perform registration between two front images acquired by the fundus camera unit 2. It is also possible to apply registration to the analysis results of the OCT images and the analysis results of the front images. Registration can be performed 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 this 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 a previously acquired OCT image of the fundus oculi Ef. This OCT image (preparatory image) is used to detect the rough shape of the application area of ​​the wide-angle OCT scan, and the focus control parameters are set based on the detected shape.

[0084] The ophthalmic imaging apparatus 1 can acquire OCT images used to set focus control parameters. For example, the ophthalmic imaging apparatus 1 can apply a preparatory OCT scan to the subject's eye E before applying a wide-angle OCT scan to the subject's eye E.

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

[0086] The pattern of the preparatory OCT scan may be a scan pattern containing a large number of scan points, such as a three-dimensional scan (raster scan). However, considering that the purpose of the preparatory OCT scan is to grasp the general shape of the area to which the wide-angle OCT scan will be applied, 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, which typically includes one or more B-scan images representing one or more cross sections of a central region and one or more cross sections of a peripheral region of the wide-angle OCT scan coverage area.

[0088] In the following examples, the outer edge of the central region and 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, either the outer edge of the central region or the outer and inner edges of the peripheral region may be rectangular, or may have any other shape. Furthermore, the outer and inner edge shapes of the peripheral region may be the same or different.

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

[0090] The example of a preparatory OCT scan shown in FIG. 5B is two B-scans 341 and 342, each passing through a central region 310 and a peripheral region 320. 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 was applied and a B-scan image representing a cross section to which the B-scan 342 was 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, the relative depth position relationship between the central region 310 and the peripheral region 320 is obtained for the direction in which the B-scan 341 was applied and the direction in which the B-scan 342 was applied, i.e., for two directions that are orthogonal to each other.

[0091] Although not shown, when a radial scan (multiple B-scans arranged at equal angular intervals) is applied as the preparatory OCT scan, the relative depth positional relationship between the central region and the peripheral region can be obtained for multiple directions arranged at equal angular intervals. Also, although not shown, when a three-dimensional scan (e.g., a raster scan) is applied as the preparatory OCT scan, the relative depth positional relationship between the central region and the peripheral region can be obtained for any direction in the xy plane. Even when other scan patterns are applied, the relative depth positional relationship between the central region and the peripheral region can be 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 (angle interval, etc.) of information acquired as a relative depth position relationship. Conversely, the pattern of the preparatory OCT scan can be determined depending on the content and amount of information desired to be acquired as a relative depth position relationship. The preparatory OCT scan pattern is determined, for example, in advance or for each examination.

[0093] The data collected by the preparatory OCT scan is sent to the image construction unit 220, which constructs a preliminary image. The parameter setting unit 231 sets one or more focus control parameters based on this preliminary image. As described above, the focus control parameters are parameters that indicate the content of control for the OCT focusing driver 43A, and examples of these parameters include a parameter that indicates the focal position of the measurement arm, a parameter that indicates the moving speed of the focal position, and a parameter that indicates the moving acceleration of the focal position.

[0094] An example of processing performed by the parameter setting unit 231 will be described. An example of a preparatory image is shown in FIG. 6A. Preparatory image G is an image constructed from data acquired, for example, by B-scan 330 shown in FIG. 5A (or B-scan 341 shown in FIG. 5B or a similar B-scan). The area outlined by a dotted line and labeled 310 corresponds to the intersection area (common area) of central region 310 and B-scan 330 shown in FIG. 5A. The area indicated by diagonal lines and labeled 320 corresponds to the intersection area (common area) of peripheral region 320 and B-scan 330 shown in FIG. 5A. Note that there are two peripheral regions 320 in preparatory image G. Furthermore, symbol Em denotes the image area of ​​the macula, and symbol Ed denotes the image area of ​​the optic disc.

[0095] The parameter setting unit 231 analyzes the central region 310 of the preliminary image G to detect the macular region Em and identify its depth position (z coordinate). To this end, the parameter setting unit 231 performs, for example, segmentation to identify the image region of the internal limiting membrane (ILM), shape analysis to detect the macular region Em from the shape (depression) of the identified ILM region, and processing to determine the z coordinate of a pixel at a representative point of the detected macular region Em. The representative point of the macular region Em may be, for example, the center of the macular (the fovea, the deepest part of the depression). The z coordinate of the macular center determined in this example is designated z1 (see FIG. 6B). Note that the location for which the z coordinate is identified is not limited to the center of the macular, and may be any representative point within the central region 310.

[0096] Furthermore, the parameter setting unit 231 analyzes the peripheral region 320 of the preparatory image G to detect an image region of a predetermined tissue (for example, the internal limiting membrane) and identify its depth position (z coordinate). To this end, the parameter setting unit 231 includes, for example, a segmentation process for identifying the image region of the predetermined tissue and a process for determining the z coordinate of a pixel at a representative point in the identified image region. The representative point of the image region of the predetermined tissue may be, for example, the center position of the peripheral region 320 in the B-scan direction or an end point of the peripheral region 320. When the respective center positions of the two peripheral regions 320 of the preparatory image G are representative points, the z coordinate of the internal limiting membrane determined by this example is defined as z 21 and z 22 (See Figure 6C).

[0097] Furthermore, the parameter setting unit 231 determines the z coordinate (z1) of the representative point of the central region 310 and the z coordinate (z 21 , z 22 ) and set focus control parameters based on the

[0098] For example, the parameter setting unit 231 determines the 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 , respectively) can be obtained. The position of the OCT focusing lens 43 corresponds to the focal position of the measurement arm. This example can be said to be processing for obtaining the absolute position of the OCT focusing lens 43. The processing in this example is performed, for example, based on the coherence gate positions (arm length, position of retroreflector 41, position of retroreflector 114) when the preliminary image G was acquired and the scale of the z-axis (for example, 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 in the central region 310 and the z coordinate (z 21 and z 22It is possible to obtain a difference between the position (focal position) of the OCT focusing lens 43 corresponding to each of the above (each of the above). In other words, this example can be said to be processing for obtaining the relative position of the OCT focusing lens 43. The processing in 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 A focus position change range can be obtained, including the positions (focus positions) of the OCT focusing lens 43 corresponding to the respective positions (focus positions) of the OCT focusing lens 43. The focus position change range is the range of focus positions changed by focus control, and is defined as, for example, the movement range of the OCT focusing lens 43. The processing in this example is performed based on, for example, the coherence gate position when the preliminary image G was acquired and the scale of the z-axis.

[0101] The parameter setting unit 231 can set the speed at which the focal position of the measurement arm is moved. The processing in 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 for moving the focal position of the measurement arm. The processing in this example is executed based on, for example, the absolute position or relative position of the OCT focusing lens 43, the movement range of the OCT focusing lens 43, or the movement speed of the OCT focusing lens 43.

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

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

[0105] As a prerequisite, a scan pattern for a wide-angle OCT scan is set, for example, in advance or for each examination.

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

[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 another location on the fundus. While the center of the wide-angle OCT scan application area may be defined based on a location or tissue of the subject's eye, it may also be defined based on the ophthalmologic imaging device 1. For example, the center of the wide-angle OCT scan application area may be defined as the neutral position (neutral orientation) of the variable-direction mirror (e.g., galvanometer mirror) of the optical scanner 44, or as the position of the optical axis of the measurement arm (optical axis of the objective lens 22). Examples of curved wide-angle OCT scan patterns 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 pattern.

[0108] When the wide-angle OCT scan pattern is the above-mentioned curved scan pattern, the wide-angle OCT scan pattern may be a spiral scan pattern extending from the center of the wide-angle OCT scan application area toward the outer edge (see spiral scan pattern 510 shown in FIG. 8A ), or a spiral scan pattern extending from the outer edge of the wide-angle OCT scan application area toward the center (see spiral scan pattern 520 shown in FIG. 8B ).

[0109] The spiral scan pattern 510 shown in FIG. 8A starts scanning at the center of the macula in the central region (not shown), and passes through the peripheral region (not shown) while increasing the radius as the deflection angle changes, to reach the scan end point at (near) the outer edge.

[0110] The spiral scan pattern 520 shown in FIG. 8B starts scanning at (or near) the outer edge, and passes through the peripheral region (not shown) while decreasing the radius as the deflection angle changes, to reach the scan end point set at the center of the macula in the central region (not shown).

[0111] For the sake of illustration, the spirals in each of the spiral scan patterns 510 and 520 are drawn with a coarser spacing than in reality. In reality, the spirals may be spaced closely together to the extent that three-dimensional image data can be constructed, for example.

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

[0113] It should be noted 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 scan pattern to be applied. The focal position on the vertical axis is defined as the z-coordinate. The focus control parameters in FIG. 9A are applicable when a spiral scan pattern is adopted that extends from the center to the outer edge of the wide-angle OCT scan application area, such as the spiral scan pattern 510 shown in FIG. 8A . Hereinafter, the spiral scan pattern 510 will be described as an example.

[0115] The first scan position n=0 in FIG. 9A corresponds to the scan start point (the center of the macula) in the spiral 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 spiral scan pattern 510.

[0116] The focal position ζ assigned to the scan start position n=0 11 is set based on the z-coordinate z1 of the central region 310 (for example, the center of the macula) shown in FIG. 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 the z-coordinate z of the peripheral region 320 shown in FIG. 6C, for example. 21 and z 22 For example, ζ 12 is z 21 or ζ 12 is z 21 or set to a value approximately equal to ζ 12 is z 22 or ζ 12 is z 22 or set to a value approximately equal to ζ 12 is z 21 and z 22z 21 and z 22 From both sides, ζ 12 For example, if you want to find z 21 and z 22 Calculating the average of and z 21 and z 22 Calculating the weighted average of z 21 and z 22 Any statistical process can be used, such as selecting the larger or smaller value of (a) and (b).

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

[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 parameters in Fig. 9B are applicable when a spiral scan pattern is adopted that moves from the outer edge of the wide-angle OCT scan application area toward the center, such as the spiral scan pattern 520 shown in Fig. 8B. Hereinafter, the spiral scan pattern 520 will be described as an example.

[0120] The first scan position n=0 in FIG. 9B corresponds to the scan start point (a position on or 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 is, for example, the focal position ζ in FIG. 12 The focal position ζ assigned to the scan end position n=N-1 can be set in the same manner as 22 is, for example, the focal position ζ in FIG. 11 It can be set in the same way.

[0122] The focus control parameters shown in FIG. 9B are the coordinates (0, ζ) corresponding to the scan start point in the two-dimensional coordinate system (n, z). 21 ) and the coordinates (N-1,ζ 22 ) can be set as a smooth curve (for example, a spline curve or a Bezier curve) connecting the

[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 parameters in Fig. 9C are applicable when a spiral scan pattern is adopted that extends from the center to the outer edge of the wide-angle OCT scan application area, such as the spiral scan pattern 510 shown in Fig. 8A. Hereinafter, the spiral scan pattern 510 will be described as an example.

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

[0125] Scan position interval n=[0,n 31 ] is assigned to the focal position ζ 31 is, for example, the focal position ζ in FIG. 11 It can be set in the same way as the scan position interval n=[n 32 ,N-1]. 33 is, for example, the focal position ζ in FIG. 12 Furthermore, the scan position interval n = (n 31 ,n 32 )=[n 31 +1,n 32 -1] is assigned to the focal position ζ 32 is, for example, the focal position ζ 31 and ζ 33 Typically, the focal position ζ 32can be obtained by any statistical processing, for example. 31 and ζ 33 and the average, ζ 31 and ζ 33 Weighted average of 31 and ζ 33 The larger of these, ζ 31 and ζ 33 The smaller of these values ​​is used.

[0126] Similar to the relationship between the focus control parameters shown in Figure 9A and those shown in Figure 9B, the stepped focus control parameters shown in Figure 9C can be inverted. The focus control parameters obtained by inversion are applicable when a spiral scan pattern is employed that moves from the outer edge to the center of the wide-angle OCT scan application area, such as spiral scan pattern 520 shown in Figure 8B.

[0127] 9C. For example, in the scan position range n=[0, n 31 ], and the coordinates (0,ζ 31 ) and coordinates (n 31 ,ζ 32 ) and a smooth curve (e.g., a spline curve, a Bezier curve) can be assigned to connect them. 32 ,N-1], coordinates (n 32 ,ζ 32 ) and coordinates (N-1,ζ 33 ) can be assigned a smooth curve (for example, a spline curve or a Bezier curve) connecting the two. For example, when a spiral scan pattern is adopted that moves from the outer edge of the wide-angle OCT scan application area to the center, as in the spiral scan pattern 520 shown in FIG. 8B, it is possible to invert the focus control parameters that have been partially replaced with curves in this way.

[0128] Alternatively, the scan position interval n=[0,n 31 ], and the coordinates (0,ζ 31 ) and coordinates (n 31 ,ζ 32) and a straight line (diagonal line) can be assigned to connect the scan position interval n=[n 32 ,N-1], coordinates (n 32 ,ζ 32 ) and coordinates (N-1,ζ 33 ) can be assigned a straight line (diagonal line) connecting the two points. For example, when a spiral scan pattern is adopted that moves from the outer edge of the wide-angle OCT scan application area to the center, as in the spiral scan pattern 520 shown in FIG. 8B, it is possible to invert the focus control parameters that have been partially replaced with diagonal lines 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 parameters in Fig. 9D are applicable when a spiral scan pattern is adopted that extends from the center to the outer edge of the wide-angle OCT scan application area, such as the spiral scan pattern 510 shown in Fig. 8A. Hereinafter, the spiral scan pattern 510 will be described as an example.

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

[0131] Scan position interval n=[0,n 41 ] is assigned to the focal position ζ 41 is, for example, the focal position ζ in FIG. 11 It can be set in the same way as the scan position interval n=[n 42 ,N-1]. 42 is, for example, the focal position ζ in FIG. 12 Furthermore, the scan position interval n = (n 41 ,n 42 )=[n 41 +1,n 42 -1] has the coordinate (n 41 ,ζ 41 ) and coordinates (n 42,ζ 42 ) is assigned a line connecting them.

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

[0133] It is also possible to modify the focus control parameters shown in FIG. 9D. For example, the scan position interval n=(n 41 ,n 42 )=[n 41 +1,n 42 -1], and the coordinate (n 41 ,ζ 41 ) and coordinates (n 42 ,ζ 42 ) can be assigned a smooth curve (for example, a spline curve or a Bezier curve) connecting the two. For example, when a spiral scan pattern is adopted that moves from the outer edge of the wide-angle OCT scan application area to the center, as in the spiral scan pattern 520 shown in FIG. 8B, it is possible to invert the focus control parameters that have been partially replaced with curves in this way.

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

[0135] For example, in the example shown in FIG. 6B , the depth position (z coordinate) of one representative point (the center of the macula) in the central region 310 is determined, and this is used as the depth position of the central region 310. Meanwhile, it is also possible to determine the depth positions of two or more points in the central region and then determine the depth position of the central region from the determined two or more depth positions. For example, the depth position of the central region can be determined by applying statistical processing to two or more depth positions. The statistical value obtained from two or more depth positions may be, for example, any of the average, weighted average, median, mode, maximum, and minimum values. Similar processing can also be applied when determining the depth position of the peripheral region.

[0136] When two or more depth positions within the central region are obtained, instead of calculating a single statistical value from these depth positions and using it as the depth position of the central region as described above, information representing the change in 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 curved, linear, or stepwise change in depth position in the central region can be obtained. FIGS. 9A and 9B show examples of curved changes. Although not shown, an example of a linear change in depth position in the central region can be obtained by plotting coordinates (0, ζ) in the two-dimensional coordinate system shown in FIG. 9C. 31 ) and coordinates (n 31 ,ζ 32 ) can be obtained. Although not shown, as an example of a stepwise change in depth position in the central region, in the two-dimensional coordinate system shown in FIG. 9C, a line connecting the scan position interval n=[0,n 31 ], and the value of the focal position is ζ 31 From ζ 32 It is possible to set a focus control parameter that changes stepwise from 0 to 1. The same process can be applied to determining the focus control parameter for the peripheral area.

[0137] As described above, the process of determining two or more depth positions within the central region and setting focus control parameters is considered effective, for example, when the width (length in the direction perpendicular to the z direction) of the central region is relatively wide or when the change in 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 from which depth positions are determined, depending on the width of the central region and / or the magnitude of the change in depth position within the central region. Similar processes can also be applied when determining focus control parameters for peripheral regions.

[0138] In the examples described above, the central region (310) and the peripheral region (320) are spaced apart. In other words, in the examples 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 this embodiment, the central region and the peripheral region can be defined arbitrarily. For example, the central region and the peripheral region can be defined according to the location of the fundus. As a specific example, the central region can be set to a region centered on a specific location of the fundus (e.g., the center of the macula) and within a predetermined first distance from this center. Furthermore, the peripheral region can be set to a region that is a predetermined second distance (greater than or equal to the first distance) from this center. Here, a third distance representing the outer edge of the peripheral region may be further set, or the outer edge of the area used for wide-angle OCT scanning may be set to the outer edge of the peripheral region. The distance in this example may be a distance at the fundus, an optically calculated distance, or a standard distance obtained from a model eye or clinical data.

[0140] Other definitions of the central region and the peripheral region may be based on the OCT scan. For example, a predetermined first region in the wide-angle OCT scan application area may be set as the central region, and a predetermined second region different from the second region may be set 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 the first region is set as the peripheral region.

[0141] Although the above examples have focused on scan patterns consisting of curves, such as spiral scan patterns, it is also possible to adopt scan patterns consisting of at least some straight lines. For example, by alternately combining line scans in the x direction and line scans in the y direction, a spiral scan pattern consisting of multiple straight lines can be applied.

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

[0143] 9A to 9D, the focal position (first focal position) applied to the central region is located on the +z side of 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 in accordance with the shape of the subject's eye (fundus). However, the first focal length does not need to be longer than the second focal length.

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

[0145] <Movement detection unit 232> The ophthalmologic photographing apparatus 1 includes a fundus camera unit 2 that repeatedly photographs the subject's eye E 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 detects movement of the subject's eye E by analyzing the observation image acquired by the fundus camera unit 2. For example, the movement detection unit 232 analyzes each image included in the observation image to detect feature points and obtains time-series changes in the positions of the feature points. The feature points may be, for example, the center, center of gravity, and contour of the pupil, or the center, center of gravity, and contour of the iris.

[0147] The scan control unit 213 can control the optical scanner 44 and the OCT unit 100 according to the wide-angle OCT scan pattern, and can also control the optical scanner 44 based on the output from the movement detection unit 213. 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 performed by the following series of processes disclosed in, for example, Japanese Patent Application Laid-Open No. 2017-153543: First, the movement detection unit 232 registers any frame (front image) of the observation image acquired by the fundus camera unit 2 as a reference image.

[0149] Furthermore, the movement detection unit 232 determines changes in the positions of feature points in other frames relative to the positions of feature points in the reference image. This corresponds to determining time-series changes in the positions of feature points, that is, determining the displacement between the reference image and other frames. Note that if the displacement exceeds a threshold due to blinking or fixation misalignment or if it becomes impossible to detect the displacement, the movement detection unit 232 can register a frame acquired thereafter as a new reference image. Note that the method for determining time-series changes in the positions of feature points is not limited to this; for example, the displacement of feature points between two consecutive frames may be determined sequentially.

[0150] Every time a time-series change in the position of a feature point is determined, the movement detection unit 232 sends control information for canceling this time-series change to the scan control unit 213. The scan control unit 213 corrects the orientation of the optical scanner 44 based on the control information that is sequentially input.

[0151] The movement detection unit 232 is realized by cooperation between 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 that combines a display function and an operation function, 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 apparatus.

[0153] <Operation> The following describes the operation of the ophthalmologic imaging apparatus 1. It is assumed that preparatory processing, such as input of a patient ID, presentation of a fixation target, adjustment of the fixation position, alignment, focus adjustment, and OCT optical path length adjustment, has already been performed, similar to conventional methods.

[0154] An example of the operation of the ophthalmologic photographing apparatus 1 will be described with reference to FIG.

[0155] (S1: A preliminary OCT scan is applied to the fundus to obtain a preliminary image) First, the ophthalmologic imaging apparatus 1 applies a preparatory OCT scan to the fundus oculi Ef using the optical scanner 44 and the OCT unit 100. The image construction unit 220 constructs a preparatory image from 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 in the storage unit 212, for example.

[0157] In step S2 or an earlier stage, the ophthalmologic imaging apparatus 1 may set a wide-angle OCT scan application area, a central region, a peripheral region, scan control parameters, etc. Any of these conditions may be fixed, selected from multiple options, or manually set by the user. The parameter setting unit 231 may set focus control parameters based on the results of these settings and the preparatory image.

[0158] In this example, the central region 310 and peripheral region 320 shown in Fig. 5A, the spiral scan pattern 510 shown in Fig. 8A, and the focus control parameters shown in Fig. 9A are assumed to be applied. Also, the outer edge of the peripheral region 320 is assumed to define 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 an earlier stage, and controls the optical scanner 44 based on this scan start position, thereby disposing each galvanometer mirror included in the optical scanner 44 in a direction corresponding to the scan start position.

[0160] In this example, a fixation target corresponding to the fixation position for acquiring an image centered on the macula is typically 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 and fixation states of the subject's eye E are favorable, the center of the macula is positioned on the optical axis of the measurement arm. Therefore, in this example, each galvanometer mirror of the optical scanner 44 is positioned in a neutral position.

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

[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 this initial focus position ζ 11 The OCT focusing driver 43A controls the OCT focusing lens 43 to be positioned at a position corresponding to the OCT focusing lens 43A.

[0163] The control relating to step S4 may be executed before the control relating to step S3, or the control relating to step S3 and the control relating to step S4 may be executed in parallel.

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

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

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

[0167] More specifically, the scan control unit 213 controls the optical scanner 44 and the OCT unit 100 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 with this, the focus control unit 214 controls the OCT focusing drive unit 43A so that when an A scan is applied to each scan position n shown in Figure 9A, the OCT focusing lens 43 is positioned at a position corresponding to the focal position z = ζ(n) corresponding to this scan position n.

[0169] This makes it possible to scan the fundus oculi Ef according to the spiral scan pattern 510 shown in FIG. 8A while moving the focal position according to the focus control parameters shown in FIG. 9A.

[0170] (S7: Start tracking) In response to the start of the coordinated control in step S6, or at any timing before the start of the coordinated control, tracking is started to correct the projection position of the measurement light LS (the application position of the A-scan) in accordance with the movement of the subject's eye E. The tracking is performed by the fundus camera unit 2, the movement detection unit 232, the scan control unit 213, etc. in the manner described above. This makes it possible to apply the spiral scan pattern 510 shown in Fig. 8A even if the subject's eye E moves during the execution of the wide-angle OCT scan.

[0171] (S8: Wide-angle OCT scan completed) The wide-angle OCT scan started in step S6 ends after an OCT scan is performed along the spiral scan pattern 510 shown in FIG. 8A, for example.

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

[0173] (S9: Constructing an OCT image according to the wide-angle OCT scan pattern) The image constructing unit 220 constructs an OCT image from the data collected by the wide-angle OCT scans performed in steps S6 to S8.

[0174] 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 = cos θ - θ × sin θ, y = sin θ + θ × cos θ.

[0175] In this case, the OCT image constructed in step S9 is also defined using a two-dimensional polar coordinate system (r, θ). That is, the positions of the multiple 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, the positions of the multiple A-scans that make up the spiral scan pattern 510 shown in FIG. 8A correspond to the multiple scan positions n=0 to N-1 shown in FIG. 9A, so the positions of the multiple A-scan images constructed in step S9 also correspond to the multiple scan positions n=0 to N-1, respectively. For example, step S9 constructs an OCT image H1 shown in FIG. 11. The OCT image H1 is constructed at each scan position n=n p A-scan image A(n p ) where each scan position n = n p is defined using the two-dimensional polar coordinate system (r,θ).

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

[0178] (S10: Apply coordinate transformation to OCT image) The image constructing unit 220 applies 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 a polar coordinate system from data collected by the OCT scan applied to the subject's eye E according to this curved scan pattern (S9), and converts this OCT image into an image defined in a three-dimensional Cartesian coordinate system (S10).

[0180] When the OCT image H1 shown in FIG. 11 is constructed in step S9, the image constructing unit 220 converts the OCT image H1 at each scan position n=n defined in the two-dimensional polar coordinate system (r, θ) according to a coordinate conversion formula between the two-dimensional polar coordinate system (r, θ) and the two-dimensional Cartesian coordinate system (x, y). p The coordinates are converted into coordinates defined in a two-dimensional Cartesian coordinate system (x, y). The coordinate conversion formula is, for example, the above-mentioned (x=cosθ-θ×sinθ, y=sinθ+θ×cosθ).

[0181] By such coordinate transformation, for example, a group of OCT images H2(m) (m=1, 2, . . . , M) shown in FIG. 12 can be obtained. Each OCT image H2(m) is a B-scan image along the x direction and is defined using a two-dimensional Cartesian coordinate system (x, z). Furthermore, M OCT images H2(1) to H2(M) are arranged along the y direction. In this way, M OCT images H2(1) to H2(M) are defined using a three-dimensional Cartesian coordinate system (x, y, z).

[0182] (S11: Construct a 3D image from the coordinate-transformed OCT image) The image constructing unit 220 can construct a three-dimensional image from the OCT image after the coordinate transformation obtained in step S10.

[0183] In this example, step S10 obtains, for example, M OCT images H2(1) to H2(M) that are stack data. The image constructing unit 220 can construct volume data by voxelizing the M OCT images H2(1) to H2(M).

[0184] (S12: Displaying a 3D rendering image) The image constructing unit 220 can render the three-dimensional image constructed in step S11. The main control unit 211 can cause the display unit 241 to display the resulting rendered image.

[0185] <Actions and Effects> The functions and effects of the exemplary embodiment will be described.

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

[0187] The data collection unit collects data by applying an OCT scan to the subject's eye (E). In the above example, the data collection unit includes the OCT unit 100 and elements in the fundus camera unit 2 that constitute the measurement arm (such as the retroreflector 41, the OCT focusing lens 43, the optical scanner 44, and the objective lens 22).

[0188] The image constructor constructs an image from the data collected by the data collector. In the above example, the image constructor includes image constructor 220.

[0189] The focal position changing unit is provided in the optical path (measurement arm) of the measurement light projected onto the subject's eye (E) by the data collecting unit, and changes the focal position of the measurement arm. In the above example, the focal position changing unit includes an OCT focusing lens 43 and an OCT focusing driver 43A.

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

[0191] The focus control unit controls the focus position changing unit to apply a first focus position in parallel with application of an OCT scan to at least a portion of the first partial pattern. Furthermore, 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 application of an OCT scan to at least a portion 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 portion of the first partial pattern corresponds to at least a portion of the central region 310, and the first focus position is, for example, a z coordinate ζ in FIG. 9A . 11 Furthermore, in the above example, at least a portion of the second partial pattern corresponds to at least a portion of the peripheral region 320, and the second focal position corresponds to, for example, the z coordinate ζ in FIG. 12 Corresponds to.

[0192] According to this 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 positioned relatively deep in the eyeball, and the peripheral region is positioned relatively shallow. Therefore, the focal position suitable for the central region differs from the focal position suitable for the peripheral region. In addition to scan control according to the above scan pattern, this embodiment can apply a first focal position to the central region (first partial pattern) and a second focal position to the peripheral region (second partial pattern). This enables wide-angle OCT scanning while moving the focal position at a practical speed. Therefore, according to this embodiment, high-quality OCT images can be acquired while performing wide-angle OCT scanning at high speed.

[0193] When raster scanning is applied to a conventional wide-angle OCT scan, several B-scans pass through both the central and peripheral regions, and it is practically impossible to switch between two or more focal positions, including the first and second focal positions, 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 origin at the center of the OCT scan application area.

[0195] The curved scan pattern can be set by taking into consideration, for example, the structural characteristics and control characteristics of the optical scanner (44), the required scan speed, the required scan density, and the like.

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

[0197] Another example of a curved scan pattern is a concentric scan pattern.

[0198] In this embodiment, the image constructing unit 220 can form an image (OCT image H1) defined in a polar coordinate system from data collected by an OCT scan applied to the subject's eye E according to a curved scan pattern. Furthermore, the image constructing 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 Cartesian coordinate system.

[0199] With this configuration, it is possible to construct an OCT image defined in a three-dimensional Cartesian coordinate system from an OCT image obtained using a curved scan pattern, which allows for easy image processing and analysis.

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

[0201] With this configuration, wide-angle OCT scanning can be performed at high speed while changing the focal position in accordance with the shape of the eyeball, making it possible to acquire high-quality OCT images.

[0202] The ophthalmic imaging apparatus (1) according to this embodiment may apply a preparatory OCT scan to the subject's eye (E) using a data collection unit before a wide-angle OCT scan according to a wide-angle OCT scan pattern. When the preparatory OCT scan is performed, the image construction unit (220) can construct a preliminary image (G) from data collected by the preparatory OCT scan. Furthermore, the parameter setting unit (231) of the ophthalmic imaging apparatus (1) according to this embodiment can set one or more focus control parameters based on the preliminary image (G) constructed by the image construction unit (220). In addition, the focus control unit (214) can control the focus position changing unit according to the 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 a numerical value greater than or equal to 1. As an example of the latter, a numerical value indicating the focal position (for example, z coordinate ζ 11 and ζ 12 ) may be.

[0204] With this configuration, it is possible to set focus control parameters based on the actual shape of the subject's eye (for example, the fundus), thereby further improving the quality of the acquired OCT image.

[0205] In this embodiment, the one or more focus control parameters established by the preliminary images may include a focus position change range that includes the first focus position and the second focus position. In the above example, for example, the focus control parameters in FIG. 9A may include a focus position change range [ζ 12 ,ζ 11 ] is included as information.

[0206] According to this configuration, the range in which the focal position is changed can be set based on the preparatory image (that is, based on the actual shape of the eye to be inspected).

[0207] In this embodiment, the one or more focus control parameters established using the preliminary images may include at least one of the moving speed and the moving acceleration of the focus position. In the above example, the focus control parameter represented by the smooth curve shown in FIG. 9A includes information on the moving speed and the moving acceleration of the focus position of the measuring arm.

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

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

[0210] With this configuration, it is possible to perform a wide-angle OCT scan while performing tracking to correct the projection position of the measurement light in accordance with the movement of the subject's eye. This allows for suitable scanning according to the wide-angle OCT scan pattern even if the subject's eye moves during the wide-angle OCT scan. Furthermore, it is possible to avoid interrupting or redoing the scan.

[0211] Although the above example describes the application of OCT scanning to the fundus (Ef), it is possible to configure an embodiment that can achieve similar effects and benefits for the anterior segment of the eye (cornea, lens, iris, angle, etc.) The focus control parameters are set according to the shape of the area to be scanned by OCT.

[0212] An exemplary embodiment provides a method for controlling an ophthalmic imaging apparatus, the ophthalmic imaging apparatus including a data acquisition unit that applies an OCT scan to an eye to be examined to acquire data, an image construction unit that constructs an image from the acquired data, and a focus position changing unit that is provided in an optical path of measurement light projected onto the eye by the data acquisition unit.

[0213] The control method includes a scan control step and a focus control step. The scan control step controls a data acquisition 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. The focus control step controls a focus position changing unit to apply a first focal position in parallel with application of an OCT scan to at least a portion of the first partial pattern, and to apply a second focal position different from the first focal position in parallel with application of an OCT scan to at least a portion of the second partial pattern.

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

[0215] The exemplary embodiment provides a program for causing an ophthalmic imaging apparatus to execute such a control method. Any of the features described in the exemplary embodiment can be combined with this program.

[0216] It is also possible to create a computer-readable non-transitory recording medium that records such a program. Any of the items described in the exemplary embodiments can be combined with this recording medium. This non-transitory recording medium may be in any form, including, for example, a magnetic disk, an optical disk, a magneto-optical disk, and a semiconductor memory.

[0217] According to the method, program, or recording medium of the exemplary embodiment, it is possible to acquire high-quality OCT images while performing wide-angle OCT scans at high speed, and the effects and advantages of the items combined with the method, program, or recording medium of the exemplary embodiment are also achieved.

[0218] The configurations described above are merely examples of embodiments of the present invention, and any modifications (omissions, substitutions, additions, etc.) can be made within the scope of the gist of the present invention. [Explanation of symbols]

[0219] 1. Ophthalmic imaging equipment 100 OCT units 210 Control Unit 211 Main control unit 212 Storage section 213 Scan control section 214 Focus control section 220 Image Construction Department 230 Data Processing Unit 231 Parameter setting section 232 Movement detection unit 240 User Interface 241 Display section 242 Operation section

Claims

1. a data collection unit that collects data by applying an optical coherence tomography (OCT) scan to the subject's eye; an image constructing unit that constructs an image from the data collected by the data collecting unit; a focal position changing unit provided in an optical path of measurement light projected onto the subject's eye by the data collecting unit; a scan control unit that controls the data acquisition unit according to a scan pattern including a first continuous partial pattern for a central region of an OCT scan application area and a second continuous partial pattern for a peripheral region of the OCT scan application area; a focus control unit that controls the focus position changing unit to apply a first focus position in parallel with application of an OCT scan to at least a portion 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 portion of the second partial pattern; a parameter setting unit that sets focus control parameters to be provided to the focus control unit; Including, Prior to the OCT scan according to the scan pattern, the data acquisition unit applies a preparatory OCT scan including two or more B-scans to the subject's eye; the image constructor constructs a preliminary image from data collected by the preliminary OCT scan; the parameter setting unit sets one or more focus control parameters based on the preliminary image constructed by the image construction unit; After the parameter setting unit sets the one or more focus control parameters, the scan control unit causes the data acquisition unit to execute, as the OCT scan according to the scan pattern, one of an OCT scan according to a spiral scan pattern that starts from the center of the macula in the central region as a scan start point, passes through the peripheral region while increasing a moving radius as the deflection angle changes, and reaches a scan end point that is set at the center of the macula in the central region, and an OCT scan according to a spiral scan pattern that starts from the outer edge of the OCT scan application area as a scan start point, passes through the peripheral region while decreasing a moving radius as the deflection angle changes, and reaches a scan end point that is set at the center of the macula in the central region, In parallel with the OCT scan according to the scan pattern, the focus control unit controls the focal position changing unit according to any one of a smooth curved, stepped, and broken line pattern that connects the scan start point and the scan end point based on the one or more focus control parameters set by the parameter setting unit; The preliminary OCT scan includes a B-scan that passes through both the central region and the peripheral region. An ophthalmic photographing apparatus characterized by the above.

2. The preliminary OCT scan includes two orthogonal B-scans.

2. An ophthalmologic photographing apparatus according to claim 1.

3. The one or more focus control parameters include a focus position change range that includes the first focus position and the second focus position.

3. An ophthalmologic photographing apparatus according to claim 1 or 2.

4. The one or more focus control parameters include at least one of a moving speed and a moving acceleration of the focus position.

4. An ophthalmologic photographing apparatus according to claim 1, wherein the ophthalmologic photographing apparatus is a holographic photographing apparatus.

Images