Ophthalmic device, method for controlling ophthalmic device, and program

Abstract

An ophthalmic device according to the present invention comprises: an interference optical system that detects interference light between signal light obtained by scanning a subject's eye with light from a light source, and reference light in which light from the light source is divided; an adjustment unit that is disposed in at least one light path out of the signal light and the reference light and adjusts the polarization state of light propagated through the least one light path such that the polarization state of the signal light and the polarization state of the reference light become the same; and a control unit that controls the adjustment unit in accordance with the scanning angle at which the subject's eye is scanned.

Description

[Technical field]

[0001] The technology disclosed herein relates to an ophthalmic apparatus, a control method for an ophthalmic apparatus, and a program. [Background technology]

[0002] Conventionally, there is known an optical image measurement device that acquires a fundus tomographic image based on a signal light that has passed through a test eye and an interference light between the signal light and the reference light. Conventionally, there has been a demand for adjusting the polarization states of the signal light and the reference light (for example, see JP 2015-70919 A). Summary of the Invention

[0003] An ophthalmic apparatus according to a first aspect of the technology disclosed herein, an interference optical system that detects interference light between a signal light obtained by scanning the eye to be examined with light from a light source and a reference light obtained by splitting the light from the light source; an adjustment unit that is disposed in at least one of the optical paths of the signal light and the reference light, and adjusts the polarization state of light propagating through the at least one optical path so that the polarization state of the signal light and the polarization state of the reference light become the same; a control unit that controls the adjustment unit in accordance with a scanning angle at which the subject's eye is scanned; Equipped with.

[0004] A control method for an ophthalmic apparatus according to a second aspect of the technique disclosed herein includes: A control method performed by a processor of the ophthalmic apparatus, acquiring an adjustment amount of an adjustment unit that is disposed in at least one of the optical paths of the signal light and the reference light and adjusts the polarization state of the light propagating through the at least one optical path so that the polarization state of the signal light and the polarization state of the reference light are the same, the adjustment amount corresponding to a scanning angle of the signal light of the OCT; controlling the adjustment unit based on the adjustment amount; Includes.

[0005] The program according to the third aspect of the technology of the present disclosure includes: On the computer, acquiring an adjustment amount of an adjustment unit that is disposed in at least one of the optical paths of the signal light and the reference light and adjusts the polarization state of the light propagating through the at least one optical path so that the polarization state of the signal light and the polarization state of the reference light are the same, the adjustment amount corresponding to a scanning angle of the signal light of the OCT; controlling the adjustment unit based on the adjustment amount; Execute the command. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a block diagram showing an example of a configuration of an ophthalmologic system. [Diagram 2] 1 is a schematic diagram illustrating an example of an overall configuration of an ophthalmologic apparatus. [Diagram 3] 1 is a conceptual diagram illustrating an example of a schematic configuration of a wide-angle optical system included in an ophthalmic apparatus. [Figure 4] FIG. 2 is a block diagram showing an example of functions of the ophthalmologic apparatus. [Diagram 5] 13 is a flowchart showing an example of the flow of a table creation process. [Figure 6] FIG. 13 is an image diagram showing an example of the contents of a table. [Figure 7] 11 is a flowchart showing an example of a flow of imaging processing using OCT. [Figure 8] FIG. 13 is a diagram showing an example of a display screen including a tomographic image. [Figure 9] 13 is a flowchart showing an example of the flow of a table creation process. [Figure 10] FIG. 11 is an explanatory diagram of an example regarding derivation of an optimal adjustment amount. [Figure 11] FIG. 13 is an image diagram showing an example of the contents of a table. [Figure 12] FIG. 2 is a block diagram showing an example of an OCT unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. For convenience of explanation, a scanning laser ophthalmoscope will be referred to as "SLO" below. For convenience of explanation, an optical coherence tomography will be referred to as "OCT" below.

[0008] [First embodiment] An example of the configuration of an ophthalmologic system 100 will be described with reference to FIG. As shown in FIG. 1, the ophthalmologic system 100 includes an ophthalmologic apparatus 110, an axial length measuring apparatus 120, a server apparatus (hereinafter referred to as "server") 140, and an image display apparatus (hereinafter referred to as "viewer") 150. The ophthalmologic apparatus 110 acquires a fundus image and a tomographic image. The axial length measuring apparatus 120 measures the axial length of a subject. The server 140 stores a plurality of fundus images and axial lengths obtained by photographing the funduses of a plurality of subjects by the ophthalmologic apparatus 110 in association with the IDs of the subjects. The viewer 150 displays the fundus images acquired by the server 140 and data obtained by analyzing the fundus images. The fundus images include SLO fundus images photographed by SLO, OCT images (also referred to as tomographic images) photographed by OCT, and the like.

[0009] The ophthalmologic apparatus 110, the axial length measurement apparatus 120, the server 140, and the viewer 150 are connected to each other via a network 130.

[0010] Next, the configuration of the ophthalmic apparatus 110 will be described with reference to FIG. 2, the ophthalmologic apparatus 110 includes an imaging device 14 and a control device 16. The imaging device 14 captures an image of the fundus of the subject's eye. The control device 16 is realized by a computer including a central processing unit (CPU) 16A, a random access memory (RAM) 16B, a read-only memory (ROM) 16C, and an input / output (I / O) port 16D. The ophthalmic apparatus 110 is an example of an ophthalmic apparatus according to the technology of the present disclosure.

[0011] The input / output (I / O) port 16D is connected to a storage device 17. The storage device 17 is configured, for example, by a non-volatile memory (NVM). The input / output (I / O) port 16D is also connected to a network 130 via a communication interface (I / F) 15.

[0012] The control device 16 also includes an input / display device 16E connected to the CPU 16A via an I / O port 16D. The input / display device 16E has a graphic user interface that displays captured images and receives various instructions including instructions for capturing images. An example of the graphic user interface is a touch panel display.

[0013] A data processing program 17A is stored in the storage device 17. Note that, although a case where the data processing program 17A is stored in the storage device 17 is described here, the technology of the present disclosure is not limited to this, and the data processing program 17A may be stored in the ROM 16C. The data processing program 17A is an example of an ophthalmology program of the technology of the present disclosure.

[0014] In the following description, the horizontal direction when the ophthalmic apparatus 110 is placed on a horizontal plane is referred to as the "X direction", the vertical direction to the horizontal plane is referred to as the "Y direction", and the direction connecting the center 27 of the pupil of the anterior part of the subject's eye 12 and the center O of the eyeball is referred to as the "Z direction". Therefore, the X direction, Y direction, and Z direction are perpendicular to each other.

[0015] Next, a description will be given of the image capturing device 14. The image capturing device 14 operates under the control of the control device 16. The image capturing device 14 includes an SLO unit 18, a wide-angle optical system 19, and an OCT unit 20. The wide-angle optical system 19 includes a first optical scanner 22, which is composed of a polygon mirror that deflects the light from the SLO unit 18 in the X direction (horizontal direction), and an OCT unit20 The optical system includes a second scanner 24 including a galvanometer mirror that deflects light from the first scanner 21 in the X direction (horizontal direction), a dichroic mirror 26, and a common optical system 28 including a third scanner 29 including a galvanometer mirror that deflects light in the Y direction (vertical direction). The optical paths of the SLO light and the OCT light are combined by the dichroic mirror 26, and the SLO light and the OCT light are irradiated onto an imageable area 12A of the fundus through the pupil of the subject's eye 12 via the common optical system 28. The imageable area 12A is within a range of approximately 200 degrees when converted into an internal irradiation angle from the center O of the eyeball.

[0016] The SLO unit 18 includes a light source 18A, a detection element 18B, a dichroic mirror 18C, etc., and is configured to capture an image of the fundus of the subject's eye 12. The light source 18A includes an R light (red light) light source, a G light (green light) light source, a B light (blue light) light source, and an infrared (e.g., near-infrared light) light source, and is configured to be switchable between a mode for emitting R light, G light, and / or B light, and a mode for emitting infrared (e.g., near-infrared light).

[0017] Light from the light source 18A (hereinafter referred to as "SLO light") passes through the dichroic mirror 18C and proceeds to the wide-angle optical system 19. The SLO light is deflected in the X direction (horizontal direction) by the first optical scanner 22, passes through the dichroic mirror 26, and is deflected in the Y direction (vertical direction) by the third optical scanner 29 of the common optical system 28. The first optical scanner 22 and the third optical scanner 29 are controlled by the control device 16 to scan the photographable area 12A of the fundus. The reflected light from the fundus passes through the wide-angle optical system 19, is reflected by the dichroic mirror 18C, and is received by the detection element 18B. The control device 16 generates an SLO fundus image (hereinafter referred to as "SLO image"), which is a front image of the fundus based on a detection signal from the detection element 18B.

[0018] A Fourier domain type OCT will be described as an example of the OCT unit 20. In particular, the ophthalmic apparatus 110 according to the technique of the present disclosure has the OCT unit 20 of a swept source type OCT (SS-OCT) using a wavelength swept light source.

[0019] The OCT unit 20 includes a light source 20A, a sensor 20B, fiber couplers 20C and 20D, and a reference optical system 20G including a polarization adjustment unit 20F. The light source 20A is a wavelength sweep type light source that emits light in the near-infrared wavelength region.

[0020] Light from a light source 20A of the OCT unit 20 (hereinafter referred to as signal light (LS)) is branched by a fiber coupler 20C, and one of the signal lights is deflected in the X direction (horizontal direction) by a second optical scanner 24 of the wide-angle optical system 19, reflected by a dichroic mirror 26, and deflected in the Y direction (vertical direction) by a third optical scanner 29 of the common optical system 28. 24 and the third optical scanner 29 are controlled by the control device 16 to scan the area in the fundus imageable area 12A where OCT imaging is to be performed. The area where OCT imaging is to be performed is specified by a user of the ophthalmologic apparatus 110 or the like. There are various scanning patterns for this scanning, such as an A-scan which is a scan of one point on the fundus, a linear B-scan for acquiring a tomographic image of the fundus, and a planar C-scan for acquiring OCT volume data.

[0021] The signal light reflected by the fundus enters the fiber coupler 20D via the wide-angle optical system 19 and the fiber coupler 20C. The other signal light, that is, the signal light proceeding to the light source 20A, the fiber coupler 20C, the polarization adjustment unit 20F, and the sensor 20B, is called the reference light (LR). The other reference light branched by the fiber coupler 20C has its polarization state adjusted by the polarization adjustment unit 20F and enters the fiber coupler 20D. In the fiber coupler 20D, the reference light with its polarization adjusted interferes with the signal light reflected by the fundus, and the interference light enters the sensor 20B. The sensor 20B detects the intensity of the interference light for each wavelength and outputs it to the control device 16 as a detection signal.

[0022] Then, the control device 16 performs processing such as Fourier transform on the detection signal of the sensor 20B to generate an OCT image or a tomographic image (hereinafter referred to as an "OCT image").

[0023] Here, the optical path length of the signal light (LS) is determined by the distance from the light source 20A to the fundus and the distance from the fundus to the sensor 20B. The optical path length of the reference light is also controlled to be the same as the optical path length of the signal light.

[0024] Of the signal light, the reflected light that is reflected from the fundus and enters the signal optical fiber coupler 20D is particularly called return light. The OCT unit 20 is an example of an interference optical system of the technology of the present disclosure. Also, the polarization adjuster 20F is an example of an adjuster of the technology of the present disclosure.

[0025] In this embodiment, the polarization adjuster 20F is connected to the driver 20E, and adjusts the polarization state of the incident light according to the driving amount of the driver 20E and emits the light. The polarization state is indicated including the azimuth angle. The polarization state may be indicated by the amplitude ratio and phase difference of the orthogonal coordinates. In this embodiment, a half-wave plate that imparts a phase difference (λ / 2) is used as an example of the polarization adjuster 20F, and the incident linearly polarized light is rotated and emitted by the half-wave plate. The half-wave plate, which is an example of the polarization adjuster 20F, is an example of the optical member of the technology of the present disclosure.

[0026] In the following description, since both the SLO light and the signal light are scanned two-dimensionally in the X and Y directions, when there is no need to distinguish between the SLO light and the signal light, the SLO light and the signal light will be collectively referred to as “scanning light.”

[0027] Next, the configuration of the wide-angle optical system 19 included in the ophthalmic apparatus 110 will be described with reference to FIG. 3, the common optical system 28 includes a slit mirror 30 and an elliptical mirror 32 in addition to the third optical scanner 29. The dichroic mirror 26, the slit mirror 30, and the elliptical mirror 32 are shown in a side end view. Instead of the slit mirror 30 and the elliptical mirror 32, the common optical system 28 may be configured using a mirror such as a concave mirror, a parabolic mirror, or a free-form mirror, or a group of multiple lenses.

[0028] The slit mirror 30 has an elliptical first reflecting surface 30A. The first reflecting surface 30A has a first focal point P1 and a second focal point P2. The elliptical mirror 32 also has an elliptical second reflecting surface 32A. The second reflecting surface 32A has a first focal point P3 and a second focal point P4.

[0029] The slit mirror 30, the elliptical mirror 32, and the third optical scanner 29 are arranged such that the first focal point P3 and the second focal point P2 are at a common position in the third optical scanner 29. In addition, the slit mirror 30, the elliptical mirror 32, and the third optical scanner 29 are arranged such that the second focal point P4 is located at the center of the pupil of the subject's eye 12. Furthermore, the first optical scanner 22, the second optical scanner 24, and the slit mirror 30 are arranged such that the first focal point P1 is located in the first optical scanner 22 and the second optical scanner 24.

[0030] That is, the first optical scanner 22 , the second optical scanner 24 , and the third optical scanner 29 are disposed at positions conjugate with the center of the pupil of the subject's eye 12 .

[0031] In this embodiment, the wide-angle optical system 19 shown in Fig. 3 allows the field of view (FOV) of the fundus to be large, allowing a wide range of fundus regions to be observed. The wide range of fundus regions will be described by distinguishing between an external irradiation angle of the scanning light from the outside by the ophthalmic device 110 and an internal irradiation angle as an irradiation angle inside the subject's eye irradiated with the scanning light. For example, when the external irradiation angle is 120 degrees, the internal irradiation angle corresponds to approximately 160 degrees. In this embodiment, the internal irradiation angle is set to 200 degrees.

[0032] The external irradiation angle is the angle of light irradiation from the ophthalmic device 110 side, that is, from outside the subject's eye 12. In other words, the external irradiation angle is the angle at which the scanning light is directed toward the center 27 of the pupil of the subject's eye 12 (that is, the center point of the pupil in frontal vision (see also FIG. 2)) with respect to the fundus of the subject's eye 12. This external irradiation angle is also equal to the angle of light reflected from the fundus, emitted from the center 27 of the pupil to the outside of the subject's eye 12, and directed toward the ophthalmic device 110.

[0033] On the other hand, the internal illumination angle refers to the light illumination angle at which the fundus of the subject's eye 12 can be substantially photographed by irradiating it with scanning light, with the center O of the eyeball of the subject's eye 12 being taken as the reference position. Although the external illumination angle A and the internal illumination angle B correspond to each other, the following description is of an ophthalmic device, so the external illumination angle is used as the illumination angle corresponding to the viewing angle of the fundus.

[0034] The ophthalmologic apparatus 110 captures an image of an imageable area 12A (see also FIG. 2) which is a fundus area of ​​the subject's eye 12 at an external irradiation angle. The imageable area 12A is, for example, the maximum area that can be scanned with a scanning light by a wide-angle optical system 19.

[0035] The SLO image obtained by the ophthalmic apparatus 110 capturing an image of the imageable area 12A of the subject's eye 12 is referred to as a UWF SLO image. UWF is an abbreviation for Ultra-Widefield. The wide-angle optical system 30, which sets the field of view (FOV) of the fundus to an ultra-wide angle, can capture an image of the area from the posterior pole of the fundus of the subject's eye 12 beyond the equator, and can capture images of structures present in the peripheral area of ​​the fundus, such as vortex veins.

[0036] Next, an example of various functions realized by the CPU 16A of the control device 16 of the ophthalmic apparatus 110 executing the data processing program 17A will be described with reference to FIG. The data processing program 17A has a setting function, an SLO image acquisition function, an OCT image acquisition function (image acquisition function, image processing function, image display function), and a transmission function. When the CPU 16A executes the data processing program 17A having each of these functions, the CPU 16A Figure 4 2, it functions as a setting unit 202, an SLO image acquisition unit 204, an OCT image acquisition unit 206 (an image acquisition unit 210, an image processing unit 212, and an image display unit 214), and a transmission unit 208.

[0037] 2, the control device 16 of the ophthalmic apparatus 110 includes the input / display device 16E, but the technology of the present disclosure is not limited thereto. For example, the control device 16 of the ophthalmic apparatus 110 may not include the input / display device 16E, but may include a separate display device that is physically independent from the ophthalmic apparatus 110. In this case, the display device may include an image processing processor unit that operates under the control of the CPU 16A of the control device 16, and the image processing processor unit may display an SLO image or the like based on an image signal that the image display unit 214 instructs to output.

[0038] (1) Creating a table showing the relationship between polarization and scanning angle First, before using the ophthalmic apparatus 110 of the ophthalmic system 100, information is collected to adjust the polarization state used when acquiring an OCT image. The collected information is stored as a table TB and used when acquiring an OCT image, which will be described later. The data of the table TB (hereinafter referred to as table data) may be transmitted to the server 140 and acquired from the server 140. The table data may be derived and stored during setup, such as when the apparatus is installed, or may be stored in the server 140 and acquired. Note that table TB is an example of a table of the technology of the present disclosure.

[0039] As described above, before the OCT imaging process is performed, information for adjusting the polarization state used when acquiring an OCT image is collected. The collected information will now be described in detail. The information for adjusting the polarization state is information that indicates the adjustment of the relationship between the polarization state of the signal light and the polarization state of the reference light when acquiring an OCT image in a preferable state.

[0040] In OCT, tomography of interference light is performed by interfering the reference light with each return light obtained by irradiating the fundus with the signal light from the pupil of the subject's eye 12. By performing the tomography of the interference light in this manner, a tomographic region is photographed, and an OCT image showing the tomographic region is acquired by the image acquisition unit 210.

[0041] For the return light and the reference light to interfere with each other, it is ideal that the polarization state of the signal light and the polarization state of the reference light are equal. However, in OCT, the polarization state (e.g., the direction of polarization) of the measurement light and the reference light may not match, and when the polarization states do not match, the interference action is suppressed, resulting in a decrease in the contrast of the OCT image. For example, when right-handed circularly polarized signal light is irradiated onto the fundus of the subject's eye, assuming that the eyeball does not have birefringence, the return light reflected by the fundus of the subject's eye becomes left-handed circularly polarized light. In addition, since the amount of change in polarization changes depending on the scanning angle corresponding to the external irradiation angle, the amount of change in polarization changes depending on the photographed area of ​​the fundus. In addition, in a configuration using an elliptical mirror as the wide-angle optical system 19 as shown in FIG. 3, the reflecting surfaces 30A and 32A of the elliptical mirror may not be perfect ellipses due to the limits of accuracy during manufacturing. Furthermore, even in each ophthalmic device 110, the shape of the elliptical surface of the elliptical mirror may vary even among multiple ophthalmic devices 110 due to errors during manufacturing the elliptical mirror. Variations in the shapes of these elliptical mirrors during manufacture result in different polarization states for each ophthalmic apparatus 110 .

[0042] Therefore, when the polarization state of the reference light is maintained at a constant polarization state, the polarization state of the signal light (return light) changes, suppressing interference between the signal light (return light) and the reference light, and degrading the image quality of the OCT image captured by OCT. For this reason, it is preferable to make the polarization states of the signal light and the reference light common depending on the scanning angle at which the signal light is scanned. It is even more preferable to make the polarization states of the signal light and the reference light common depending on the fundus position (hereinafter referred to as the scanning position) when the signal light is scanned. This is because the fundus is spherical, and when the signal light is scanned through the center of the pupil away from the center of the eyeball, it is possible to suppress the influence of the change in the overall optical path length of the signal light and the return light depending on the scanning position.

[0043] The relationship between the scanning angle and the polarization state of the signal light at that scanning angle can be derived in advance. Therefore, based on the relationship between the scanning angle and the polarization state of the signal light at that scanning angle, adjustments are made to suppress changes in the polarization state of the signal light and the polarization state of the reference light at each scanning angle, thereby making the polarization states of the signal light and the reference light common to each other. The relationship between this scanning angle and the polarization state of the signal light at that scanning angle is created in advance as a table, and the polarization state is adjusted according to the scanning angle when acquiring an OCT image.

[0044] Next, an example of the process of creating the table TB will be described with reference to FIG. The CPU 16A of the control device 16 of the ophthalmic apparatus 110 executes a table creation process included in the data processing program 17A, thereby implementing the table creation process shown in FIG.

[0045] The table creation process shown in FIG. 5 is carried out by the creation section 200 of the CPU 16A. First, in step S100, the creation unit 200 confirms the installation of the model eye in the ophthalmic device 110. In this case, the doctor or operator operates the input / display device 16E to instruct completion of the installation of the model eye, thereby confirming it. In the next step S102, a scanning range is set. The scanning range is the range in which the signal light is scanned when an OCT image is acquired in the ophthalmic device 110, that is, the range of the scanning angle. Next, in step S104, the scanning angle is set to an initial value. As the initial value, any scanning angle when scanning within the scanning range set in step S102 is predefined. For example, the maximum scanning angle is set.

[0046] Steps SIn step S106, the model eye is scanned at a set scanning angle, and the polarization state of the signal light obtained by scanning is acquired and stored in step S108. Specifically, the polarization state of the signal light is measured and stored. To measure the polarization state, a polarization measuring device such as a polarization camera is used. The polarization measuring device is preferably installed in the sensor 20B of the OCT unit 20. Note that the sensor 20B of the OCT unit 20 according to this embodiment has a polarization measuring function and can operate as a polarization measuring device. A polarization camera, which is an example of a polarization measuring device, is equipped with polarizers with different azimuth angles for each pixel on the light incident side of the line sensor and the two-dimensional sensor, and can measure the azimuth angle (polarization direction) as the polarization state of the incident light by transmitting only light polarized at a predetermined azimuth angle. In addition, a polarimeter can also be used as another example of a polarization measuring device. That is, the polarization state of the light is measured by transmitting light through a polarizer and rotating the polarizer.

[0047] In addition, the table TBw is set for each ophthalmic apparatus 110 based on a standardized model eye. This makes it possible to eliminate the influence of changes in the polarization state caused by shape variations during the manufacture of the elliptical mirror. Therefore, regardless of which ophthalmic apparatus 110 is used, the influence of variations in the polarization state in the optical system, such as the subject's eye and the elliptical mirror, can be eliminated, allowing stable OCT imaging to be performed.

[0048] In step S110, the adjustment amount of the polarization adjuster 20F corresponding to the polarization state stored in step S108 is derived. Specifically, the polarization adjuster 20F is adjusted to a polarization state according to the drive amount of the driver 20E. The relationship between the drive amount of the driver 20E and the azimuth angle of the polarization is known, and the drive amount of the polarization adjuster 20F corresponding to the polarization state is derived as the adjustment amount. For example, the scan angle in the direction along the optical axis passing through the center of the pupil and the center of the eyeball is used as a reference, and the drive amount from the polarization state of the signal light at that reference is used as the adjustment amount. Then, in step S112, the scan angle, the polarization state, and the adjustment amount are stored in association with each other.

[0049] In step S114, it is determined whether scanning of the scanning angle covering the scanning range is completed, and if the determination is affirmative, the process proceeds to step S118, and if the determination is negative, the process proceeds to step S116. In step S116, the scanning angle is updated, and the process returns to step S106. In step S118, the scanning angle, polarization state, and adjustment amount associated with each other in step S112 are created as a table TB and stored.

[0050] Table TBw is shown in Fig. 6 as an example of table TB. In the example table TBw shown in Fig. 6, a scanning angle θ that determines a scanning position, a polarization state PZ corresponding to the scanning angle, and an adjustment amount W of the polarization adjustment unit 20F are associated with each other. Table TBw is stored in the storage device 17 of the control device 16 as table TB. Figure 6 The example table TBw shown in FIG. 1 corresponds to the polarization state PZ of the signal light when the scanning angle θ in the direction along the optical axis passing through the center of the pupil and the center of the eyeball is increased or decreased by 10 degrees, and the adjustment amount W, which is the driving amount for driving the polarization adjustment unit 20F, is associated with the scanning angle θ of 0 degrees.

[0051] In the example shown in Fig. 6, the table TB shows a range of scanning angles of ±70 degrees, but the range of scanning angles is not limited to that shown in Fig. 6. For example, a predetermined range may be set such as a range of scanning angles of ±75 degrees and ±80 degrees. eye The scanning angle range may be set to within a range of ±100 degrees corresponding to the field of view of the target object. The scanning angle range is not limited to being set uniformly from the reference (0 degrees), and for example, the scanning angle of the maximum value on the positive side or the minimum value on the negative side may be made different, or, for example, a part of the scanning angle range of ±100 degrees may be set.

[0052] 6 shows an example of table TB in which the scanning angle θ at every 10 degrees, the polarization state PZ of the signal light, and the adjustment amount W are associated with each other, but table TB is not limited to the correspondence relationship between the scanning angle θ at every 10 degrees, the polarization state PZ of the signal light, and the adjustment amount W. For example, the correspondence may be less than 10 degrees or more than 10 degrees.

[0053] The created table TB may be transmitted to the server 140 and acquired from the server 140. The table data may be derived and stored at the time of setup such as when the device is installed, or may be stored in the server 140 and acquired.

[0054] (2) OCT imaging using polarization information from the table Next, the photographing process using the OCT by the ophthalmic apparatus 110 will be described. The CPU 16A of the control device 16 of the ophthalmic apparatus 110 executes the OCT imaging process included in the data processing program 17A, thereby realizing the OCT imaging process shown in FIG.

[0055] 7, first, in step S200, the setting unit 202 performs initial settings. Specifically, the initial settings refer to processes such as adjusting the optical system for focus, alignment, and the like in the ophthalmic device 110, controlling eye tracking that follows eye movements, and receiving input of identification information of the subject. In step S200, the above-mentioned table TB is also read.

[0056] In the next step S202, the SLO image acquisition unit 204 acquires an SLO image by performing shooting using SLO, and then the process proceeds to step S208. The process of step S202 is executed by the SLO image acquisition unit 204, whereby a live SLO image is displayed on the input / display device 16E. The SLO image is displayed as a live view image on the input / display device 16E.

[0057] In steps S206 to S224, the OCT image acquiring unit 206 acquires an OCT image. In detail, first, in step S206, the image acquiring unit 210 accepts the designation of a scanning range, which is an OCT imaging range. Specifically, the operator looks at the live SLO image displayed as a live view image on the input / display device 16E, and confirms the location where OCT imaging is to be performed based on the data indicating the instruction sheet. The operator sets the ophthalmic apparatus 110 so that the confirmed location is imaged by OCT. Specifically, for example, the operator operates the mouse to designate a scanning range 872, which is an OCT imaging range. That is, in step S206, the image acquiring unit 210 accepts the designation of the scanning range 872. A line of a B-scan is designated as the scanning range 872. Note that a rectangular range of a C-scan may be designated as the OCT imaging range.

[0058] Then, in steps S208 to S220, OCT imaging is performed on the scanning range 872 with the polarization states of the signal light and the reference light being common. Specifically, in step S208, the image acquisition unit 210 sets the scanning angle to an initial value. For example, the maximum or minimum value of the scanning angle within the scanning range is set as the initial value of the scanning angle. Next, in step S210, the table TB is referenced to acquire the amount of adjustment of the polarization corresponding to the scanning angle, and in step S214, the subject's eye is scanned in a state in which the polarization state of the reference light and the polarization state of the signal light are adjusted in common for the set scanning angle.

[0059] In the next step S216, the image acquisition unit 210 determines whether or not scanning of the scanning range has been completed. If the determination in step S216 is negative, the scanning angle is incremented or decremented in step S218, and the process returns to step S210, and the above process is repeated. If scanning of the scanning range is completed and the determination in step S216 is positive, the process proceeds to step S220. In step S220, the image acquisition unit 210 outputs a detection signal of the interference light obtained by scanning the scanning range to the image processing unit 212.

[0060] In step S222, the image processor 212 performs signal processing such as Fourier transform on the detection signal of the interference light to generate OCT data consisting of multiple A-scan data. Then, the image processor 212 performs image processing such as averaging and eyeball shape correction on the OCT data to generate a tomographic image. After generating the tomographic image, the process proceeds to step S224. In step S224, the image display unit 214 displays the tomographic image obtained by performing the image processing in step S222 on the input / display device 16E, and then the process proceeds to step S226.

[0061] 8 shows a tomographic image displayed on the input / display device 16E. A display screen 800 includes a tomographic image 810 and a navigation image in which an arrow 830 indicating the positional information of the tomographic image is superimposed on a reduced SLO image 820 as positional information relating to the position where the OCT data was acquired.

[0062] In step S226, the transmitting unit 208 transmits image data indicating the tomographic image obtained by performing the process of step S222 and the subject's identification information to the server 140, and then ends this data processing. Note that OCT data may be sent to the server 140 together with the image data. The control content of step S212 described above is an example of the control content by the control unit of the technique of the present disclosure.

[0063] On the other hand, the server 140 transmits image data and the like to the viewer 150 based on a request from the viewer 150. The viewer 150 displays an SLO image or an OCT image, which is an image of the subject's eye, on a display 156 based on the image data. A user can diagnose the subject's eye 12 while viewing the SLO image or the OCT image displayed on the display 156.

[0064] As described above, in the technology disclosed herein, the signal light is scanned, and the return light reflected by the retina of the fundus of the subject's eye and the reference light branched from the signal light are made to interfere with each other to capture a tomographic region of the retina in the depth direction at each scanning position, and the polarization state of the reference light is adjusted according to the scanning angle so that interference occurs. As a result, in the technology disclosed herein, when the tomographic region of the retina is captured while scanning the signal light, the polarization state of the return light reflected by the retina and the reference light can be maintained constant regardless of the scanning angle. Therefore, the influence of polarization that differs depending on the scanning angle can be removed from the interference light obtained by the return light reflected by the retina and the reference light. As a result, when OCT imaging is performed at a wide angle, the influence of polarization that differs depending on the scanning angle can be removed, and a high-resolution tomographic image can be obtained.

[0065] [Second embodiment] Next, a second embodiment will be described. Note that since the second embodiment has a similar configuration to the first embodiment, the same parts are denoted by the same reference numerals and detailed description thereof will be omitted. In the first embodiment, the polarization state of the polarization adjuster 20F is measured, and the adjustment amount of the polarization adjuster 20F is derived from the measurement result and stored as a table. In the second embodiment, the adjustment amount of the polarization adjuster 20F that optimizes the polarization state is experimentally obtained and stored as a table.

[0066] Next, the process of creating the table TB according to this embodiment will be described with reference to FIG. The table creation process shown in Fig. 9 is obtained by replacing the processes of steps S106 to S112 in the table creation process shown in Fig. 5 with processes of steps S120 to S132. The table creation process shown in Fig. 9 is performed by creation unit 200.

[0067] First, in the processes from step S100 to step S104, the creation unit 200 sets the scanning range and sets the scanning angle to an initial value.

[0068] Next, in step S120, the adjustment amount of the polarization adjustment unit 20F is set to an initial value. One example of the initial value is to set the azimuth angle of polarization to 0 degrees. In the next step S122, similar to step S106 in FIG. 5, the model eye is scanned at the scanning angle set in step S104. In step S124, the image contrast of the signal light obtained by scanning is acquired and stored as the polarization state of the signal light. Next, in step S126, it is determined whether or not the processing of steps S122 and S124 has been completed for the range in which the polarization state of the polarization adjustment unit 20F can be adjusted. If the determination in step S126 is negative, in step S128, the adjustment amount is updated by driving the polarization adjustment unit 20F by a predetermined adjustment amount. Specifically, the polarization state is adjusted to the updated adjustment amount by setting the drive amount of the drive unit 20E to a predetermined drive amount. On the other hand, if the determination in step S126 is positive, in step S130, an optimal adjustment amount is derived. 10, the maximum image contrast adjustment amount (shown as an optimal value in FIG. 10) among the multiple image contrasts stored in step S124 is derived as the adjustment amount of the polarization adjuster 20F at the set scan angle. Then, in step S132, the image contrast adjustment amount derived in step S130 and the scan angle are stored in association with each other.

[0069] Then, in steps S114 to S118, a correspondence relationship between the scanning angle and the adjustment amount that covers the entire scanning range is created and stored as a table TB.

[0070] Table TBv is shown in Fig. 11 as an example of table TB. In the example table TBv shown in Fig. 11, the scanning angle θ that determines the scanning position is associated with an adjustment amount V of the adjustment unit 20F that corresponds to the scanning angle. Table TBv is stored as table TB in the storage device 17 of the control device 16. In the example table TBv shown in Fig. 11, the scanning angle θ in the direction along the optical axis passing through the center of the pupil and the center of the eyeball is set as a reference (0 degrees) and the adjustment amount V that is the drive amount for driving the polarization adjustment unit 20F is increased or decreased by 10 degrees.

[0071] In the example shown in FIG. 11, similarly to the example shown in FIG. 6, the range of the scanning angle of the table TB is not limited to ±70 degrees.

[0072] As described above, in the technique of the present disclosure, the adjustment amount that maximizes contrast is derived based on the image contrast obtained by driving the polarization adjuster 20F, so that the polarization state is adjusted in accordance with the actual device.

[0073] [First Modification] In the above, as an example of the OCT unit 20, a case where the reference optical system 20G including the polarization adjustment unit 20F such as a 1 / 2 wavelength plate is provided has been described. The technology of the present disclosure is not limited to this. In the first modification, instead of the polarization adjustment unit 20F such as a 1 / 2 wavelength plate, a depolarizer that outputs light incident in a certain polarization state as unpolarized light is provided in the reference optical system 20G.

[0074] Next, a first modified example will be described with reference to FIG. As shown in FIG. 12, the modified example is an example of an OCT unit 20 in which a mirror-type depolarizer 20M is provided in a reference optical system 20G instead of the polarization adjuster 20F such as the half-wave plate shown in FIG. The other signal light branched by fiber coupler 20C has its polarization state adjusted by reflection at mirror-type depolarizer 20M and enters sensor 20B via fiber coupler 20D. As described above, depolarizer 20M is connected to driver 20E, and adjusts the polarization state of the incident light according to the drive amount of driver 20E before outputting it.

[0075] [Second modified example] In the above, as an example of the OCT unit 20, a case where the polarization adjustment unit 20F such as a half-wave plate is provided in the reference optical system 20G in the optical path of the other light split by the fiber coupler 20C has been described. The technology disclosed herein is not limited to providing the polarization adjustment unit 20F only in the reference optical system 20G. For example, the polarization adjustment unit 20F may be provided between the fiber coupler 20C and the fiber coupler 20D, which are the optical path of the return light of the signal light, specifically, the optical path of the return light toward the sensor 20B. In addition, the polarization adjustment unit 20F may be provided in both the optical path of the other light split by the fiber coupler 20C and the optical path of the return light toward the sensor 20B.

[0076] [Third Variation] The above describes an example of using an SLO image (UWFSLO image) to determine the OCT shooting position, but it goes without saying that the present invention can also be applied to fundus images taken with a fundus camera, or fundus images taken with various ophthalmic devices, such as an SLO ophthalmic device or fundus camera with a relatively small angle of view (for example, an internal irradiation angle of 100° or less).

[0077] [Fourth Variation] In the above, the case where at least one of the polarization states of the signal light and the polarization state of the reference light is adjusted so that the polarization states of the signal light and the reference light are common according to the scanning angle has been described. The technology of the present disclosure is not limited to adjusting the polarization state according to the scanning angle, and may adjust the polarization state so that the polarization states of the signal light and the reference light are common, for example, according to the scanning position of the fundus of the subject's eye. For example, at least one of the polarization states of the signal light and the polarization state of the reference light may be adjusted in A-scan units so that the polarization states of the signal light and the reference light are common.

[0078] [Other variations] In the above embodiment, the ophthalmic system 100 including the ophthalmic device 110, the axial length measurement device 120, the server 140, and the viewer 150 has been described as an example, but the technology of the present disclosure is not limited to this. For example, as a first example, the axial length measurement device 120 may be omitted. As a second example, the ophthalmic apparatus 110 may further have at least one of the functions of the server 140 and the viewer 150. This makes it possible to omit at least one of the devices of the server 140 and the viewer 150 corresponding to the function of the ophthalmic apparatus 110. Furthermore, the server 140 may be omitted and the viewer 150 may perform the functions of the server 140 .

[0079] Note that, although the ophthalmic apparatus 110 relating to the technology disclosed herein has been described as an OCT unit using swept-source type OCT (SS-OCT), it is also possible to apply the present invention to ophthalmic apparatuses using types other than the swept-source type, for example, spectral domain OCT (SD-OCT). In addition, in the technology disclosed herein, an ophthalmic apparatus 110 having an SLO imaging system function and an OCT imaging system function has been described, but it is also possible to combine an OCT unit having a configuration related to the technology disclosed herein with a fundus imaging device such as a fundus camera, a slit lamp, an ophthalmic surgical microscope, etc. The technology disclosed herein may also be applied to a stand-alone OCT device that includes a control device, an OCT unit, and a wide-angle optical system. A stand-alone OCT device is an ophthalmic device that is specialized for acquiring OCT images of a subject's eye. In a stand-alone OCT device, a front image generated from OCT volume data is used instead of an SLO image to determine the OCT shooting position.

[0080] The data processing described in the above embodiment is merely an example. Therefore, it goes without saying that unnecessary steps may be deleted, new steps may be added, or the processing order may be changed without departing from the spirit of the invention. In addition, in the above embodiment, a CPU has been used as an example of a general-purpose processor; however, in the above, the term processor refers to a processor in a broad sense, and includes general-purpose processors (e.g., CPU: Central Processing Unit, etc.) and dedicated processors (e.g., GPU (Graphics Processing Unit), ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), programmable logic devices, etc.). Furthermore, the operations of the processors in the above-described embodiments may not only be performed by a single processor, but may also be performed by multiple processors working together, or may be performed by multiple processors located at physically separate locations working together.

[0081] In the above embodiment, the data processing is realized by a software configuration using a computer, but the technology of the present disclosure is not limited to this. For example, instead of a software configuration using a computer, the data processing may be performed only by a hardware configuration such as an FPGA or an ASIC. A part of the data processing may be performed by a software configuration, and the remaining processing may be performed by a hardware configuration. Furthermore, in order to cause a computer to execute the processing in the above-described embodiment, a program describing the above-described processing in code that can be processed by a computer may be stored on a storage medium such as an optical disk and distributed.

[0082] All publications, patent applications, and standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or standard was specifically and individually indicated to be incorporated by reference.

Claims

1. an interference optical system that detects interference light between a signal light obtained by scanning the eye to be examined with light from a light source and a reference light obtained by splitting the light from the light source; an adjustment unit that is disposed in at least one of the optical paths of the signal light and the reference light, and adjusts the polarization state of light propagating through the at least one optical path so that the polarization state of the signal light and the polarization state of the reference light become the same; a control unit that controls the adjustment unit based on a scanning angle at which the subject's eye is scanned; An ophthalmic device comprising:

2. The control unit performs control to adjust the polarization state of the at least one optical path based on a position at which the eye is scanned, the position corresponding to a scanning angle at which the eye is scanned. The ophthalmic device according to claim 1 .

3. The adjustment unit includes an optical member that adjusts the azimuth angle of the polarized light. The ophthalmic device according to claim 1 .

4. The optical member includes a half-wave plate, and the azimuth angle of the polarized light is adjusted by rotating the half-wave plate. An ophthalmic apparatus according to claim 3.

5. The optical member includes a depolarizer, and adjusts the azimuth angle of polarization by emitting unpolarized light from the depolarizer. An ophthalmic apparatus according to claim 3.

6. The control unit is Detecting a scanning angle for scanning the subject's eye; Calculating an adjustment based on the detected scan angle; 2. An ophthalmic apparatus according to claim 1.

7. The adjustment unit derives the adjustment amount based on a table in which a scanning angle at which the eye is scanned and an adjustment amount for adjusting the polarization state are associated with each other and stored in advance. An ophthalmic apparatus according to claim 6.

8. A control method performed by a processor of the ophthalmic apparatus of claim 1, comprising: acquiring an adjustment amount of an adjustment unit that is disposed in at least one of the optical paths of the signal light and the reference light and adjusts the polarization state of the light propagating through the at least one optical path so that the polarization state of the signal light and the polarization state of the reference light are the same, the adjustment amount corresponding to a scanning angle of the signal light of the OCT; controlling the adjustment unit based on the adjustment amount; A method for controlling an ophthalmic apparatus comprising:

9. On the computer, acquiring an adjustment amount of an adjustment unit that is disposed in at least one of the optical paths of the signal light and the reference light and adjusts the polarization state of the light propagating through the at least one optical path so that the polarization state of the signal light and the polarization state of the reference light are the same, the adjustment amount corresponding to a scanning angle of the signal light of the OCT; controlling the adjustment unit based on the adjustment amount; A program that executes the following.

Images