Ophthalmic device, control method for ophthalmic device, and program

Abstract

To provide an ophthalmic device which adjusts a polarization state of each of signal light and reference light in accordance with a scanning angle at which the signal light has been scanned.SOLUTION: An ophthalmic device 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 a scanning angle at which the subject's eye is scanned.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The technology of the present disclosure relates to an ophthalmic device, a control method for an ophthalmic device, and a program.

Background Art

[0002] Conventionally, an optical imaging measurement device that acquires a fundus tomogram based on signal light passing through an eye to be examined and interference light with the signal light is known. Conventionally, it has been required to adjust the polarization states of the signal light and the reference light (see, for example, Japanese Patent Application Laid-Open No. 2015-70919).

Summary of the Invention

[0003] An ophthalmic device according to a first aspect of the technology of the present disclosure an interference optical system that detects interference light between signal light obtained by scanning an eye to be examined with light from a light source and reference light obtained by splitting the light from the light source; an adjustment unit disposed in at least one of the optical paths of the signal light and the reference light and configured to adjust 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 are the same; a control unit that controls the adjustment unit according to a scanning angle at which the eye to be examined is scanned; and includes.

[0004] A control method for an ophthalmic device according to a second aspect of the technology of the present disclosure is a control method performed by a processor of the ophthalmic device, a step of obtaining an adjustment amount corresponding to a scanning angle of OCT signal light 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 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; a step of controlling the adjustment unit based on the adjustment amount; and includes.

[0005] A program according to a third aspect of the technology of the present disclosure causes a computer to A step of obtaining an adjustment amount corresponding to the scanning angle of the OCT signal light of an adjustment unit, which is arranged in the optical path of at least one 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. A step of controlling the adjustment unit based on the adjustment amount, Make it run. [Brief explanation of the drawing]

[0006] [Figure 1] This is a block diagram showing an example of the configuration of an ophthalmic system. [Figure 2] This is a schematic diagram showing an example of the overall configuration of an ophthalmic device. [Figure 3] This is a conceptual diagram showing an example of a general configuration of a wide-angle optical system included in ophthalmic equipment. [Figure 4] This is a block diagram showing an example of the function of an ophthalmic device. [Figure 5] This is a flowchart showing an example of the table creation process. [Figure 6] This is an image illustrating an example of the contents of a table. [Figure 7] This flowchart shows an example of the OCT imaging process. [Figure 8] This figure shows an example of a display screen that includes a tomographic image. [Figure 9] This is a flowchart showing an example of the table creation process. [Figure 10] This is an explanatory diagram illustrating an example of how to derive the optimal adjustment amount. [Figure 11] This is an image illustrating an example of the contents of a table. [Figure 12] An example of an OCT unit is a cylinder. [Modes for carrying out the invention]

[0007] Embodiments of the present invention will be described in detail below with reference to the drawings. For the sake of convenience, a scanning laser ophthalmoscope will be referred to as "SLO" below. Also, for the sake of convenience, an optical coherence tomography (OCT) will be referred to as "OCT" below.

[0008] [First Embodiment] Referring to Figure 1, an example of the configuration of the ophthalmic system 100 will be explained. As shown in Figure 1, the ophthalmology system 100 comprises an ophthalmology device 110, an axial length measuring device 120, a server device (hereinafter referred to as "server") 140, and an image display device (hereinafter referred to as "viewer") 150. The ophthalmology device 110 acquires fundus images and tomographic images. The axial length measuring device 120 measures the axial length of the subject's eye. The server 140 stores multiple fundus images and axial lengths obtained by capturing the fundus of multiple subjects by the ophthalmology device 110, corresponding to the subject's ID. The viewer 150 displays the fundus images acquired by the server 140 and data obtained by analyzing the fundus images. Fundus images include SLO fundus images taken with SLO and OCT images (also referred to as tomographic images) taken with OCT.

[0009] The ophthalmic device 110, the axial length measuring device 120, the server 140, and the viewer 150 are interconnected via the network 130.

[0010] Next, the configuration of the ophthalmic device 110 will be explained with reference to Figure 2. As shown in Figure 2, the ophthalmic apparatus 110 includes an imaging device 14 and a control device 16. The imaging device 14 images the fundus of the eye under examination. The control device 16 is implemented by a computer equipped with a CPU (Central Processing Unit) 16A, RAM (Random Access Memory) 16B, ROM (Read-Only memory) 16C, and input / output (I / O) ports 16D. Ophthalmic device 110 is an example of an ophthalmic device of the technology of this disclosure.

[0011] A storage device 17 is connected to the input / output (I / O) port 16D. Note that the storage device 17 is constituted by, for example, a non-volatile memory (Non-volatile memory (NVM)). Also, the input / output (I / O) port 16D is connected to a network 130 via a communication interface (I / F) 15.

[0012] Further, the control device 16 includes an input / output display device 16E connected to the CPU 16A via the I / O port 16D. The input / output display device 16E has a graphic user interface for displaying an image obtained by shooting and receiving various instructions including an instruction for shooting. As an example of the graphic user interface, a touch panel display can be mentioned.

[0013] A data processing program 17A is stored in the storage device 17. Here, the case where the data processing program 17A is stored in the storage device 17 is described, but 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 ophthalmic program of the technology of the present disclosure.

[0014] In the following description, when the ophthalmic device 110 is installed on a horizontal plane, the horizontal direction is defined as the "X direction", the direction perpendicular to the horizontal plane is defined as the "Y direction", and the direction connecting the center 27 of the pupil of the anterior eye part of the eye to be examined 12 and the center O of the eyeball is defined as the "Z direction". Therefore, the X direction, the Y direction, and the Z direction are perpendicular to each other.

[0015] Next, the imaging device 14 will be described. The imaging device 14 operates under the control of the control device 16. The imaging 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 composed of a polygon mirror or the like that deflects the light from the SLO unit 18 in the X direction (horizontal direction), a second scanner 24 composed of a galvanometer mirror or the like that deflects the light from the OCT unit 10 in the X direction (horizontal direction), a dichroic mirror 26, and a common optical system 28 including a third scanner 29 composed of a galvanometer mirror or the like that deflects the light in the Y direction (vertical direction). The dichroic mirror 26 combines the optical paths of the SLO light and the OCT light, and the SLO light and the OCT light are irradiated onto the imaging target area 12A of the fundus through the pupil of the subject eye 12 via the common optical system 28. The imaging target area 12A is within a range of approximately 200 degrees when converted to the 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 photograph the fundus of the subject eye 12. The light source 18A includes a light source for R light (red light), a light source for G light (green light), a light source for B light (blue light), and a light source for infrared rays (e.g., near-infrared light), and is configured to be switchable between a mode that emits R light, G light, or / and B light and a mode that emits infrared rays (e.g., near-infrared light).

[0017] The light from the light source 18A (hereinafter referred to as "SLO light") passes through the dichroic mirror 18C and travels toward 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, and the imaging target area 12A of the fundus is scanned. The reflected light from the fundus is reflected by the dichroic mirror 18C and received by the detection element 18B via the wide-angle optical system 19. The control device 16 generates an SLO fundus image (hereinafter referred to as "SLO image"), which is a frontal image of the fundus based on the detection signal from the detection element 18B.

[0018] The OCT unit 20 will be described as a Fourier domain type OCT as an example. In particular, the ophthalmic device 110 according to the technology of this disclosure has an 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-swept light source that emits light in the near-infrared wavelength region.

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

[0021] The signal light reflected from the fundus enters the fiber coupler 20D via the wide-angle optical system 19 and fiber coupler 20C. The other signal light, that is, the signal light that proceeds through the light source 20A, fiber coupler 20C, polarization adjustment unit 20F, and sensor 20B, is called the reference light (LR). The other reference light, which is branched at fiber coupler 20C, has its polarization adjusted by the polarization adjustment unit 20F and enters the fiber coupler 20D. At fiber coupler 20D, the polarized reference light and the signal light reflected from the fundus interfere, and this interfered light enters the sensor 20B. Sensor 20B detects the intensity of the interfered light for each wavelength and outputs it as a detection signal to the control device 16.

[0022] The control device 16 then performs processing such as a Fourier transform on the detection signal from the sensor 20B to generate an OCT image or tomographic image (hereinafter referred to as "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 from the fundus to the sensor 20B. The optical path length of the reference light is also controlled to be the same as that of the signal light.

[0024] Furthermore, among the signal light, the reflected light that enters the signal optical fiber coupler 20D after being reflected from the fundus of the eye is specifically called the backlight. The OCT unit 20 is an example of an interference optical system of the present disclosure. The polarization adjustment unit 20F is an example of an adjustment unit of the present disclosure.

[0025] In this embodiment, the polarization adjustment unit 20F is connected to the drive unit 20E and emits incident light after adjusting its polarization state according to the drive amount of the drive unit 20E. The polarization state is indicated including the azimuth angle. Alternatively, the polarization state may be indicated by the ratio of the amplitudes and the phase difference in orthogonal coordinates. In this embodiment, as an example of the polarization adjustment unit 20F, a half-wave plate that provides a phase difference (λ / 2) is used, and the incident linearly polarized light is rotated and emitted by the half-wave plate. A half-wave plate, which is an example of a polarization adjustment section 20F, is an example of an optical component of the technology of this disclosure.

[0026] In the following explanation, since both SLO light and signal light are light scanned two-dimensionally in the X and Y directions, when it is not necessary to distinguish between SLO light and signal light, SLO light and signal light will be collectively referred to as "scanning light."

[0027] Next, with reference to Figure 3, the configuration of the wide-angle optical system 19 included in the ophthalmic device 110 will be described. As shown in Figure 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, slit mirror 30, and elliptical mirror 32 are shown in side view end views. The common optical system 28 may also be configured using mirrors such as concave mirrors, parabolic mirrors, or free-form mirrors, or multiple lens groups, instead of the slit mirror 30 and elliptical mirror 32.

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

[0029] The slit mirror 30, elliptical mirror 32, and third optical scanner 29 are positioned such that the first focal point P3 and the second focal point P2 are in a common position on the third optical scanner 29. Furthermore, the slit mirror 30, elliptical mirror 32, and third optical scanner 29 are positioned such that the second focal point P4 is located in the center of the pupil of the eye under examination 12. Additionally, the first optical scanner 22, second optical scanner 24, and slit mirror 30 are positioned such that the first focal point P1 is located on the first optical scanner 22 and the second optical scanner 24.

[0030] In other words, the first optical scanner 22, the second optical scanner 24, and the third optical scanner 29 are positioned conjugate to the center of the pupil of the eye being examined 12.

[0031] In this embodiment, the wide-angle optical system 19 shown in Figure 3 provides a large field of view (FOV) of the fundus, allowing observation of a wide area of ​​the fundus. This wide area of ​​the fundus will be explained by distinguishing between the external illumination angle of the scanning light from the ophthalmic device 110 and the internal illumination angle, which is the illumination angle inside the eye being examined to which the scanning light is irradiated. For example, if the external illumination angle is 120 degrees, the internal illumination angle corresponds to approximately 160 degrees. In this embodiment, the internal illumination angle is set to 200 degrees.

[0032] The external illumination angle is the angle of light illumination from the ophthalmic device 110, that is, from outside the eye under examination 12. In other words, the external illumination angle is the angle at which the scanning light is directed toward the center 27 of the pupil of the eye under examination 12 (i.e., the center point of the pupil in orthogonal vision (see also Figure 2)) relative to the fundus of the eye under examination 12. This external illumination angle is also equal to the angle at which the light reflected from the fundus is emitted from the center 27 of the pupil toward the outside of the eye under examination 12 and toward the ophthalmic device 110.

[0033] On the other hand, the internal illumination angle refers to the light illumination angle that is effectively captureable when the fundus of the eye 12 is illuminated by scanning light, with the center O of the eyeball of the eye 12 as the reference position. The external illumination angle A and the internal illumination angle B are in a corresponding relationship, but in the following explanation, since it is an explanation of an ophthalmic device, the external illumination angle will be used as the illumination angle corresponding to the field of view of the fundus.

[0034] The ophthalmic device 110 captures images within the scannable area 12A (see also Figure 2), which is the fundus region of the eye under examination 12, using an external illumination angle. This scannable area 12A is, for example, the maximum scannable area of ​​the scanning light from the wide-angle optical system 19.

[0035] The SLO image obtained by the ophthalmic device 110 to capture the imageable area 12A of the eye under examination 12 is called a UWFSLO image. UWF stands 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 the area from the posterior pole to beyond the equator of the fundus of the eye under examination 12, and can capture structures present in the peripheral part of the fundus, such as vortex veins.

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

[0037] Furthermore, in this embodiment, as shown in Figure 2, the control device 16 of the ophthalmic device 110 is equipped with an input / display device 16E, but the technology of this disclosure is not limited thereto. For example, the control device 16 of the ophthalmic device 110 may not be equipped with an input / display device 16E, and may be equipped with a separate display device that is physically independent of the ophthalmic device 110. In this case, the display device may be equipped with 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 output instructed by the image display unit 214.

[0038] (1) Create a table showing the correspondence between polarization and scanning angle. First, before using the ophthalmic device 110 of the ophthalmic system 100, information is collected to adjust the polarization state used when acquiring OCT images. The collected information is stored as table TB and used when acquiring OCT images, as described later. The data in table TB (hereinafter referred to as table data) may be sent to server 140 and retrieved from server 140. Alternatively, the table data may be derived and stored during setup, such as when installing the device, or it may be stored in server 140 and retrieved from there. Table TB is an example of a table for the technology described herein.

[0039] As mentioned above, before the OCT imaging process is performed, information is collected to adjust the polarization state used when acquiring the OCT image. The information collected is described in detail below. The information for adjusting the polarization state indicates how to adjust the relationship between the polarization state of the signal light and the polarization state of the reference light in order to acquire the OCT image in a desirable state.

[0040] In OCT, tomography of interferential light is performed by interfering the reflected light obtained by irradiating the fundus of the eye 12 through the pupil with a reference light. Through this interferential light tomography, the tomographic region is captured, and the OCT image showing the tomographic region is acquired by the image acquisition unit 210.

[0041] For the reflected light and the reference light to interfere, it is ideal that the polarization state of the signal light and the polarization state of the reference light are the same. However, in OCT, the polarization state (e.g., the direction of polarization) of the measurement light and the reference light may not match. When the polarization states do not match, the interference effect is suppressed, resulting in a decrease in the contrast of the OCT image. For example, if a clockwise circularly polarized signal light is shone on the fundus of the eye under examination, and assuming that the eyeball does not have birefringence, the reflected light from the fundus of the eye under examination will be counterclockwise circularly polarized. Also, since the amount of change in polarization changes with the scanning angle corresponding to the external illumination angle, the amount of change in polarization changes depending on the imaging area of ​​the fundus. Furthermore, as shown in Figure 3, in a configuration using an elliptical mirror as the wide-angle optical system 19, the reflective surfaces 30A and 32A of the elliptical mirror may not be perfect ellipsoids due to the limits of manufacturing precision. Moreover, even within individual ophthalmic devices 110, variations in the shape of the elliptical surface of the elliptical mirror may occur even among multiple ophthalmic devices 110 due to errors during the manufacturing of the elliptical mirror. Due to variations in the shape of these elliptical mirrors during manufacturing, the polarization state will also differ in each ophthalmic device 110.

[0042] Therefore, if the polarization state of the reference light is maintained at a constant polarization state, the polarization state of the signal light (return light) changes, which suppresses interference between the signal light (return light) and the reference light, 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 according to the scanning angle in which the signal light is scanned. Furthermore, it is even more preferable to make the polarization states of the signal light and the reference light common according to the position of the fundus when the signal light is scanned (hereinafter referred to as the scanning position). This is because the fundus is spherical, and when the signal light is scanned through the center of the pupil, which is away from the center of the eyeball, it is possible to suppress the effects of the overall optical path length of the signal light and the return light changing according to 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, by adjusting the polarization state of the signal light and the reference light at each scanning angle based on the relationship between the scanning angle and the polarization state of the signal light at that scanning angle, the polarization states of the signal light and the reference light are made common. This relationship between the 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, we will explain an example of the process for creating table TB, referring to Figure 5. The table creation process shown in Figure 5 is realized when the CPU 16A of the control device 16 of the ophthalmic device 110 executes the table creation process included in the data processing program 17A.

[0045] The table creation process shown in Figure 5 is performed by the creation unit 200 of the CPU 16A. First, in step S100, the creation unit 200 confirms the placement of the model eye in the ophthalmic device 110. In this case, confirmation is made by the doctor or operator instructing the completion of the placement of the model eye by operating the input / display device 16E. In the next step, S102, the scanning range is set. The scanning range is the range in which the signal light is scanned when acquiring an OCT image in the ophthalmic device 110, i.e., the scanning angle range. Next, in step S104, the scanning angle is set to an initial value. The initial value is predetermined to be one of the scanning angles when scanning within the scanning range set in step S102. For example, the maximum scanning angle is set.

[0046] In step S106, the model eye is scanned at a set scanning angle, and the polarization state of the signal light obtained from the scan is acquired and stored in step S108. Specifically, the polarization state of the signal light is measured and stored. For measuring the polarization state, a polarization measuring device such as a polarization camera is used. It is preferable to install the polarization measuring device on the sensor 20B of the OCT unit 20. In this embodiment, the sensor 20B of the OCT unit 20 has a polarization measuring function and is capable of operating as a polarization measuring device. A polarization camera, which is an example of a polarization measuring device, has polarizers with different azimuth angles attached to the light incident side of the line sensor and 2D sensor, and by transmitting only light with a predetermined azimuth angle polarization state, it is possible to measure the azimuth angle (direction of polarization) as the polarization state of the incident light. Another example of a polarization measuring device is a polarimeter. That is, light is transmitted through a polarizer, and the polarization state of the light is measured by rotating the polarizer.

[0047] Furthermore, a standardized model eye is used as the reference to set the table TBw for each ophthalmic device 110. This eliminates the influence of changes in polarization state caused by variations in shape during the manufacturing of the elliptical mirror. Therefore, regardless of which ophthalmic device 110 is used, the influence of variations in the polarization state of the eye under examination and the optical system such as the elliptical mirror can be eliminated, enabling stable OCT imaging.

[0048] In step S110, the adjustment amount of the polarization adjustment unit 20F corresponding to the polarization state stored in step S108 is derived. Specifically, the polarization adjustment unit 20F is adjusted to a polarization state according to the drive amount of the drive unit 20E. The relationship between the drive amount of the drive unit 20E and the polarization azimuth angle is known, and the drive amount of the polarization adjustment unit 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, polarization state, and adjustment amount are stored in association with each other.

[0049] In step S114, it is determined whether scanning has been completed for the scanning angle that covers the scanning range. If the determination is positive, the process moves to step S118; if the determination is negative, the process moves 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 in step S112 are created as a table TB and stored.

[0050] Figure 6 shows table TBw as an example of table TB. In the example table TBw shown in Figure 6, the scanning angle θ that determines the scanning position, the polarization state PZ corresponding to the scanning angle, and the adjustment amount W of the polarization adjustment unit 20F are associated. Table TBw is stored as table TB in the storage device 17 of the control device 16. In the example table TBw shown in Figure 6, 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 used as the reference (0 degrees), and the polarization state PZ of the signal light and the adjustment amount W, which is the drive amount that drives the polarization adjustment unit 20F, are associated when the scanning angle θ is increased or decreased by 10 degrees.

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

[0052] Furthermore, Figure 6 shows an example of a table TB that associates scanning angles θ in 10-degree increments with the polarization state PZ of the signal light and the adjustment amount W. However, the table TB is not limited to the correspondence between scanning angles θ, the polarization state PZ of the signal light, and the adjustment amount W in 10-degree increments. For example, the increments may be less than 10 degrees or greater than 10 degrees.

[0053] The created table TB may be sent to server 140 and retrieved from server 140. Alternatively, the table data may be derived and stored during setup, such as when the device is installed, or it may be stored on server 140 and retrieved from there.

[0054] (2) OCT imaging using polarization information from the table Next, we will explain the imaging process using OCT with the ophthalmic device 110. The OCT imaging process shown in Figure 7 is realized when the CPU 16A of the control device 16 of the ophthalmic device 110 executes the OCT imaging process included in the data processing program 17A.

[0055] In the OCT imaging process shown in Figure 7, first, in step S200, the setting unit 202 performs initial settings. Specifically, initial settings refer to processes such as adjusting the optical system for focus and alignment in the ophthalmic device 110, controlling eye tracking to follow eye movements, and receiving input of the patient's identification information. Also in step S200, the aforementioned table TB reading process is performed.

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

[0057] In steps S206 to S224, the OCT image acquisition unit 206 acquires an OCT image. Specifically, in step S206, the image acquisition unit 210 accepts the specification of the scanning range, which is the 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 areas where OCT imaging will be performed based on the data indicated in the instruction sheet. The operator sets the ophthalmic device 110 so that OCT imaging will be performed on the confirmed areas. Specifically, for example, the operator uses the mouse to specify the scanning range 872, which is the OCT imaging range. That is, in step S206, the image acquisition unit 210 accepts the specification of the scanning range 872. The scanning range 872 is specified as a B-scan line. Note that the OCT imaging range may also be specified as a C-scan rectangular area.

[0058] Then, in steps S208 to S220, OCT imaging is performed over the scanning range 872 with the polarization states of the signal light and the reference light being the same. Specifically, in step S208, the image acquisition unit 210 sets the scanning angle to an initial value. The initial value of the scanning angle is, for example, set to the maximum or minimum value of the scanning angle within the scanning range. Next, in step S210, the adjustment amount of polarization corresponding to the scanning angle is obtained by referring to table TB, and in step S214, the eye under examination is scanned with the polarization state of the reference light adjusted to be the same as the polarization state of the signal light 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 moves to step S220. In step S220, the image acquisition unit 210 outputs the detection signal of the interference light obtained by scanning the scanning range to the image processing unit 212.

[0060] In step S222, the image processing unit 212 performs signal processing such as Fourier transform on the interference light detection signal to generate OCT data consisting of multiple A-scan data. Then, it performs image processing such as additive averaging and eye 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 image processing through the execution of the process in step S222 on the input / display unit 16E, and then the process proceeds to step S226.

[0061] Figure 8 shows the tomographic image displayed on the input / display device 16E. The display screen 800 includes the tomographic image 810 and a navigation image in which an arrow 830 indicating the position information of the tomographic image is superimposed on a scaled-down SLO image 820, which represents position information related to the location where the OCT data was acquired.

[0062] In step S226, the transmission unit 208 transmits image data showing the tomographic image obtained by image processing through the execution of the process in step S222, along with the subject's identification information, to the server 140, and then terminates this data processing. Alternatively, OCT data may be sent to the server 140 along with the image data. The control content described in step S212 above is an example of the control content by the control unit of the technology disclosed herein.

[0063] Meanwhile, the server 140 sends image data and other data to the viewer 150 based on a request from the viewer 150. The viewer 150 displays the SLO image and OCT image of the eye under examination on the display 156 based on the image data. The user can diagnose the eye under examination 12 while viewing the SLO image and OCT image displayed on the display 156.

[0064] As described above, in the technology of this disclosure, the signal light is scanned, and the polarization state of the reference light is adjusted according to the scanning angle so that interference occurs when the reflected light from the retina of the fundus of the eye under examination interferes with the reference light branched from the signal light, thereby capturing a tomographic region in the depth direction of the retina at each scanning position. As a result, in the technology of this disclosure, when the tomographic region of the retina is captured while scanning the signal light, the polarization state of the reflected light from the retina and the reference light can be kept constant regardless of the scanning angle. Therefore, the effect of different polarizations depending on the scanning angle can be removed from the interference light obtained from the reflected light from the retina and the reference light. For these reasons, when performing OCT imaging at a wide angle, the effect of different polarizations 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. Since the second embodiment has the same configuration as the first embodiment, the same reference numerals are used for the same parts, and detailed descriptions will be omitted. In the first embodiment, the polarization state of the polarization adjustment unit 20F was measured, and the adjustment amount of the polarization adjustment unit 20F was derived from the measurement results and stored as a table. In the second embodiment, the adjustment amount of the polarization adjustment unit 20F that optimizes the polarization state is experimentally determined and stored as a table.

[0066] Next, with reference to Figure 9, the process for creating table TB according to this embodiment will be described. The table creation process shown in Figure 9 is the same as the table creation process shown in Figure 5, but with steps S106 to S112 replaced by steps S120 to S132. The table creation process shown in Figure 9 is performed by the creation unit 200.

[0067] First, in the process 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. An example of an initial value is setting the polarization azimuth angle to 0 degrees. In the next step S122, the model eye is scanned at the scanning angle set in step S104, similar to step S106 in Figure 5. In step S124, the image contrast obtained by the scanned signal light is acquired and stored as the polarization state of the signal light. Next, in step S126, it is determined whether the processing in steps S122 and S124 has been completed for the adjustable range of the polarization state of the polarization adjustment unit 20F. 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, the optimal adjustment amount is derived. Specifically, as shown in Figure 10, the adjustment amount for the maximum image contrast (shown as the optimal value in Figure 10) among the multiple image contrasts stored in step S124 is derived as the adjustment amount for the polarization adjustment unit 20F at the set scanning angle. Then, in step S132, the image contrast adjustment amount derived in step S130 and the scanning angle are stored in association.

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

[0070] Figure 11 shows table TBv as an example of table TB. In the example table TBv shown in Figure 11, the scanning angle θ that determines the scanning position is associated with the 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 Figure 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 used as the reference (0 degrees), and the adjustment amount V, which is the drive amount that drives the polarization adjustment unit 20F when the scanning angle θ is increased or decreased by 10 degrees, is associated with this.

[0071] Note that, as with the example shown in Figure 6, the table TB is not limited to a scanning angle range of ±70 degrees in the example shown in Figure 11.

[0072] As explained above, in the technology of this disclosure, the adjustment amount that results in maximum contrast is derived based on the image contrast obtained by driving the polarization adjustment unit 20F, so that the polarization state is adjusted in accordance with the actual device.

[0073] [First variation] In the above, an example of the OCT unit 20 was described in which a reference optical system 20G including a polarization adjustment unit 20F such as a half-wave plate was included. The technology of this disclosure is not limited thereto. The first modification is to replace the polarization adjustment unit 20F such as a half-wave plate with a depolarizer in the reference optical system 20G that emits light incident in a certain polarization state as unpolarized light.

[0074] Next, the first modified example will be described with reference to Figure 12. As shown in Figure 12, a modified example of the OCT unit 20 is one in which a mirror-type depolarizer 20M is provided in the reference optical system 20G, instead of the polarization adjustment unit 20F such as the half-wave plate shown in Figure 2. The signal light from the other side, branched by the fiber coupler 20C, has its polarization adjusted by reflection in the mirror-type depolarizer 20M and is incident on the sensor 20B via the fiber coupler 20D. As described above, the depolarizer 20M is connected to the drive unit 20E and emits the incident light after adjusting its polarization state according to the drive amount of the drive unit 20E.

[0075] [Second variation] In the above, as an example of the OCT unit 20, a case was described in which a 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 divided by the fiber coupler 20C. The technology of this disclosure 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 paths of the return light of the signal light, specifically the optical path through which the return light is directed toward the sensor 20B. Alternatively, the polarization adjustment unit 20F may be provided in both the optical path of the other light divided by the fiber coupler 20C and the optical path through which the return light is directed toward the sensor 20B.

[0076] [Third variation] The above example describes the use of SLO images (UWFSLO images) to determine the OCT imaging position, but it goes without saying that fundus images taken with a fundus camera, or fundus images taken with various ophthalmic devices such as SLO ophthalmic devices or fundus cameras with a relatively small field of view (for example, an internal illumination angle of 100° or less), can also be used.

[0077] [Fourth variation] The above describes a case in which the polarization state of the signal light and at least one of the polarization states of the reference light are adjusted so that their respective polarization states are common according to the scanning angle. The technology of this disclosure is not limited to adjusting the polarization state according to the scanning angle, but may also be adjusted so that the polarization states of the signal light and the reference light are common according to, for example, the scanning position of the fundus of the eye under examination. For example, the polarization state of the signal light and at least one of the polarization states of the reference light may be adjusted in A-Scan units so that their respective polarization states are common.

[0078] [Other variations] In the above embodiment, an ophthalmic system 100 comprising an ophthalmic device 110, an axial length measuring device 120, a server 140, and a viewer 150 was described as an example, but the technology of this disclosure is not limited thereto. For example, in the first example, the axial length measuring device 120 may be omitted. As a second example, the ophthalmic device 110 may further have at least one of the functions of a server 140 and a viewer 150. This makes it possible to omit at least one of the server 140 and viewer 150 that corresponds to the functions of the ophthalmic device 110. Furthermore, the server 140 may be omitted, and the viewer 150 may perform the functions of the server 140.

[0079] Although the ophthalmic device 110 relating to the technology disclosed herein has been described as an OCT unit using a swept-source type OCT (SS-OCT), it is also possible to apply it to ophthalmic devices using types other than the swept-source type, such as spectral-domain OCT (SD-OCT). Furthermore, although the technology disclosed herein describes an ophthalmic device 110 having SLO imaging function and OCT imaging function, it is also possible to combine an OCT unit having the configuration of the technology disclosed herein with a fundus imaging device such as a fundus camera, a slit lamp, an ophthalmic surgical microscope, etc. Furthermore, the technology disclosed herein can also be applied to a standalone OCT device comprising a control device, an OCT unit, and a wide-angle optical system. A standalone OCT device is an ophthalmic device specifically designed for acquiring OCT images of the eye under examination. In a standalone OCT device, a frontal image generated from OCT volume data is used instead of an SLO image to determine the OCT imaging 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 added, or the processing order rearranged, as long as it does not deviate from the main purpose. Furthermore, although the above embodiment used a CPU as an example of a general-purpose processor, the term "processor" in the above context refers to a broad type of processor, including 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 device, etc.). Furthermore, the operation of the processor in the above-described embodiment may not be performed by a single processor, but may be performed by multiple processors working together, or by multiple processors located in physically separate locations working together.

[0081] The above embodiment illustrates a case where data processing is realized by a software configuration using a computer, but the technology of this disclosure is not limited thereto. For example, instead of a software configuration using a computer, data processing may be performed solely by a hardware configuration such as an FPGA or ASIC. Alternatively, some 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 have a computer execute the processing described in the above-described embodiment, a program in which the above-described processing is written in code that can be processed by a computer may be stored on a storage medium such as an optical disc and distributed.

[0082] All documents, patent applications, and technical standards described herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

Claims

1. An interference optical system for detecting interference light between signal light obtained by scanning the eye under examination with light from a light source and reference light obtained by splitting the light from the light source, An adjustment unit is provided in the optical path of at least one of the signal light and the reference light, and adjusts the polarization state of the light propagating through the at least one optical path. A control unit controls the adjustment unit to suppress the difference between the polarization state of the signal light and the polarization state of the reference light based on the scanning angle for scanning the eye under examination, Equipped with, The control unit adjusts the adjustment unit by referring to a table created based on the polarization state of the interference light for each scanning angle obtained by the interference optical system scanning a model eye in advance, which associates the scanning angle with the adjustment amount of the adjustment unit. Ophthalmology equipment.

2. The control unit performs control to adjust the polarization state of at least one of the optical paths based on the scanning position of the eye being scanned, which corresponds to the scanning angle of the eye being scanned. The ophthalmic apparatus according to claim 1.

3. The adjustment unit includes an optical element that adjusts the azimuth angle of polarization. The ophthalmic apparatus according to claim 1.

4. The optical component includes a half-wave plate, and the polarization azimuth angle is adjusted by rotating the half-wave plate. The ophthalmic apparatus according to claim 3.

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

6. The control unit, The scanning angle for scanning the eye under examination is detected, The adjustment amount is calculated based on the detected scanning angle. The ophthalmic device according to feature 1.

7. An interference optical system for detecting interference light between signal light obtained by scanning the eye under examination with light from a light source and reference light obtained by splitting the light from the light source, An adjustment unit is provided in the optical path of at least one of the signal light and the reference light, and adjusts the polarization state of the light propagating through the at least one optical path. A control unit controls the adjustment unit based on the scanning angle used to scan the eye under examination, A control method performed by a processor of an ophthalmic device equipped with the following: The steps include referring to a table created based on the polarization state of the interference light for each scanning angle obtained by scanning a model eye in advance, which associates the scanning angle with the adjustment amount of the adjustment unit, A step of controlling the adjustment unit to suppress the difference between the polarization state of the signal light and the polarization state of the reference light, based on the scanning angle for scanning the eye under examination and the table, A method for controlling ophthalmic devices, including those mentioned above.

8. On the computer, A step of obtaining an adjustment amount for an adjustment unit, which is arranged in the optical path of at least one 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 as to suppress the difference between the polarization state of the signal light and the polarization state of the reference light, corresponding to the scanning angle of the OCT signal light, The steps include scanning the eye under examination by controlling the adjustment unit based on the adjustment amount, A program that executes, The step of scanning the eye to be examined involves referring to a table created based on the polarization state of interference light for each scanning angle obtained by scanning a model eye in advance, which associates the scanning angle with the adjustment amount of the adjustment unit, and controlling the adjustment unit to scan the eye to be examined based on the scanning angle and the table. program.

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