Oct device, and ophthalmic image processing program

Abstract

An Optical Coherence Tomography (OCT) device provided with an OCT optical system and an arithmetic controller is provided with a light-guiding optical system including, at least, an optical scanner which causes measuring light to scan over tissue of a subject eye, and an objective optical system which is arranged between the optical scanner and the subject eye, and which forms a turning point at which the measuring light that has passed through the optical scanner is turned, and an alignment adjusting unit which adjusts a three-dimensional position of the light-guiding optical system relative to the subject eye, wherein the arithmetic controller guides the three-dimensional position such that the turning point is arranged at a target position set between the subject eye and the objective optical system, and executes an OCT data acquisition operation at the target position.

Description

OCT device and ophthalmic image processing program

[0001] The present disclosure relates to an OCT apparatus and an ophthalmic image processing program.

[0002] In the field of ophthalmology, an optical coherence tomography (OCT) is known as a device for capturing a tomographic image of tissue in an eye to be examined.

[0003] In the field of OCT, various attempts have been made to improve the depth of penetration in OCT data (i.e., to expand the imaging range in the depth direction).

[0004] In recent years, it has been reported that improvements in light sources and the like have enabled significant improvements in the imaging range. For example, adopting a light source called a VCSEL, which emits light with a long coherence length, as an OCT light source is effective in improving depth of field. In high-depth OCT, it has also been proposed to image the depth region from the cornea to the fundus in a single A-scan (see Patent Document 1).

[0005] In addition, the retinal fovea is generally not on the ocular axis (or the optical axis of the eye) but is slightly decentered toward the temporal side. Therefore, even in a normal ocular optical system, there exists a so-called physiological strabismus angle. Various angles, such as the α angle, γ angle, κ angle, and λ angle, are known as tables of these angles. For example, these angles have recently been taken into consideration in situations such as prescribing premium IOLs (see Patent Document 1). For example, in Patent Document 1 and other documents, the κ angle is calculated based on information from a frontal image of the anterior segment.

[0006] Japanese Patent Application Laid-Open No. 2015-157182

[0007] Cecilio Velasco-Barona et al, “Personalized Optical Designsand Manipulating Optics: Applications on the Anterior Segment of the Eye” Journal of Ophthalmology ,27 Nov 2019(Published)

[0008] In an OCT device, an optical scanner is used to scan measurement light over the tissue of the subject's eye, thereby obtaining OCT data (B-scan data or volume data) corresponding to the trajectory of the measurement light. However, Patent Document 1 does not consider any scanning method that can easily scan both the anterior eye and the fundus over a wide area.

[0009] Furthermore, in the method for determining the physiological strabismus angle of the subject's eye, such as that employed in Patent Document 1, the actual position of the fovea is unknown. With a wide range of OCT data, it may be possible to more accurately determine the physiological strabismus angle of the subject's eye.

[0010] The present invention has been made in consideration of at least one of the above circumstances, and has as its technical object to properly determine the physiological strabismus angle of the subject's eye.

[0011] The ophthalmic image processing program according to the first aspect of the present disclosure is executed by a processor of an ophthalmic computer to cause the ophthalmic computer to perform an acquisition step of acquiring wide-area OCT data of the test eye, the wide-area OCT data including at least OCT data of the anterior segment and OCT data of the fundus acquired with the rotation point of the measurement light positioned closer to the test eye than the objective optical system, and an analysis step of determining the physiological strabismus angle of the test eye by analyzing the wide-area OCT data.

[0012] The OCT apparatus according to the second aspect of the present disclosure executes the above-described ophthalmologic image processing program.

[0013] The present disclosure facilitates extensive scanning of both the anterior eye and the fundus.

[0014] FIG. 1 is a diagram showing a schematic configuration of an OCT system according to an embodiment. FIG. 2 is a diagram showing an OCT optical system according to an embodiment. FIG. 3 is a flowchart explaining a photographing operation. FIG. 4 is a diagram showing the positional relationship between the device and the subject's eye E in fundus mode. FIG. 5 is a diagram showing fundus OCT data acquired in fundus mode. FIG. 6 is a diagram showing the positional relationship between the device and the subject's eye E in anterior segment mode. FIG. 7 is a diagram showing fundus OCT data acquired in anterior segment mode. FIG. 8 is a diagram showing the positional relationship between the device and the subject's eye E in whole eye mode. FIG. 9 is a diagram showing fundus OCT data acquired in whole eye mode. FIG. 10 is a diagram showing composite OCT data. FIG. 11 is a diagram for explaining analysis processing. FIG. 12 is a diagram showing a measurement method according to a modified example.

[0015] "Overview" An embodiment of the present disclosure will be described. Items grouped in < > below can be used independently or in conjunction with each other. The OCT device according to each embodiment is suitable for acquiring OCT data over a wide area.

[0016] First Embodiment An OCT apparatus according to a first embodiment includes at least an OCT optical system, a light-guiding optical system, an arithmetic and control unit, and an alignment adjustment unit.

[0017] <OCT optical system> The OCT optical system (see FIG. 2) is used to capture OCT data of the subject's eye. The OCT optical system includes at least a beam splitter and a detector. The beam splitter is used to split light from an OCT light source into measurement light and reference light. The detector detects a spectral interference signal between the measurement light and reference light guided to the subject's eye. The signal from the detector is processed by an arithmetic and control unit (described later) to acquire OCT data.

[0018] The OCT optical system may be suitable for acquiring OCT data with high depth of penetration (in other words, a wide range). For example, the OCT optical system according to the first embodiment may be a wavelength-swept OCT (SS-OCT) optical system. In this case, the OCT optical system includes a wavelength-swept light source (wavelength-scanning light source) as an OCT light source, which is a light source for measurement light and reference light. The wavelength-swept light source changes its emission wavelength at high speed over time. For example, a VCSEL-type wavelength-swept light source has a long coherence length, and when used as an OCT light source, it enables OCT data to be captured over a wide range in the depth direction. For example, an imaging range of approximately 10 mm or more can be achieved. This allows multiple tissues at different depths in the subject's eye to be imaged in a single image. As a specific example, both the fundus and the ocular tissue can be imaged in a single image. Furthermore, it is preferable that the wavelength-swept light source performs wavelength sweeping in the so-called 1 μm band (wavelength sweeping is performed around approximately 1050 nm). The so-called 1 μm band is known to have a greater penetration depth into the tissue of the subject's eye than other wavelength bands.

[0019] The sweep frequency of the wavelength swept light source may be variable between at least a first frequency and a second frequency, the second frequency being a value smaller than the first frequency. For example, the sweep frequency can be changed by changing either the speed of an optical element built into the light source that is driven to sweep the wavelength or the duty ratio in the sweep cycle.

[0020] <Conversion Unit> When the optical system of the device is an SS-OCT optical system, the OCT device further includes a conversion unit. In the SS-OCT optical system, the detector detects a spectral interference signal as a beat signal as the wavelength is swept. The conversion unit samples the spectral interference signal output from the detector. The conversion unit also converts the spectral interference signal output from the detector from an analog signal to a digital signal. The conversion unit may be a digitizer with an adjustable sampling frequency.

[0021] <Light-guiding optical system> The light-guiding optical system forms at least a part of a measurement light path for guiding measurement light to the test eye. More specifically, the light-guiding optical system of this embodiment includes at least an optical scanner and an objective optical system. The optical scanner scans the measurement light on the tissue of the test eye. For example, the light-guiding optical system may be provided with two optical scanners with different scanning directions. Furthermore, the objective optical system is disposed between the optical scanner and the test eye. As a result, the objective optical system forms a rotation point for the measurement light. The measurement light that has passed through the optical scanner is rotated around the rotation point.

[0022] Here, the measurement light that has passed through the pivot point scans the tissue of the subject's eye along a plurality of predetermined scan lines. Accompanying the scanning, OCT data for each scan line is captured. The scan lines may be set at any positions based on instructions from the examiner. Alternatively, a scan line corresponding to one of a plurality of predetermined scan patterns may be selected. Various scan patterns are known, such as line, cross, multi, map, radial, and circle.

[0023] <Alignment Adjustment Unit> The alignment adjustment unit adjusts the three-dimensional position of the light-guiding optical system with respect to the subject's eye. In this embodiment, at least the front-to-back position of the light-guiding optical system with respect to the subject's eye is adjusted. The light-guiding optical system may be electrically moved by an actuator provided in the alignment adjustment unit. This is not a limitation, and the alignment adjustment unit may be a mechanical mechanism. Furthermore, the alignment adjustment unit may include a face support unit that can change the position of the subject's face. In other words, the three-dimensional position on the subject's eye side may be adjusted by moving the position of the subject's face.

[0024] The OCT apparatus of this embodiment may additionally include an alignment detection optical system. The alignment detection optical system is used to guide the light-guiding optical system to an appropriate working distance with respect to the subject's eye. The alignment detection optical system detects the alignment state of the light-guiding optical system with respect to the subject's eye at least in the Z direction. In this embodiment, the alignment detection optical system may include at least an observation optical system (preferably an anterior segment observation optical system). In this case, the alignment detection optical system may further include a light projection optical system that projects a target for detecting the working distance onto the anterior segment of the subject's eye. The working distance may be adjusted based on the position or imaging state of the target observed by the observation optical system. Furthermore, the OCT optical system may be used as the alignment detection optical system. In this case, the alignment state may be adjusted based on the OCT data so that an image of the anterior segment is captured at a predetermined position on the OCT data.

[0025] <Arithmetic and Controller> The arithmetic and controller acquires OCT data based on signals from the detector. More specifically, the spectral interference signals converted into digital signals by the converter are processed by the image processor. This allows OCT data of the subject's eye to be acquired. The arithmetic and controller also controls at least the OCT optical system to perform the OCT data acquisition operation.

[0026] <OCT Data> The OCT data may be signal data or visualized image data. For example, the OCT data may be at least one of tomographic image data indicating reflection intensity characteristics of the test eye, OCT angiographic data (e.g., OCT motion contrast data) of the test eye, Doppler OCT data indicating Doppler characteristics of the test eye, and polarization characteristic data indicating polarization characteristics of the test eye.

[0027] In addition, the OCT data may be at least one of B-scan data (e.g., B-scan tomographic image data, two-dimensional OCT angiographic data, etc.), en face data (e.g., OCT en face data, en face motion contrast data, etc.), three-dimensional data (e.g., three-dimensional tomographic image data, three-dimensional OCT angiographic data, etc.), etc.

[0028] <Application of Full-Range Technique> A full-ranging technique may be applied to the OCT data. Various techniques for removing virtual images from OCT data are called full-ranging techniques. In this embodiment, any of the full-ranging techniques may be applied, which may enable acquisition of OCT data with a wider range from which virtual images have been selectively removed.

[0029] Examples of full-range techniques include a technique for removing virtual images (also called mirror images) using additional hardware (see, for example, Non-Patent Document 1), and a technique for correcting virtual images using software without using additional hardware (see, for example, Patent Document 2). Wojtkowski, M. et al. (2002) Full range complex spectral optical coherence tomography technique in eye imaging, Optics Letters, 27(16), p. 1415. JP 2015-506772 A. Furthermore, in an application filed by the present applicant (Japanese Patent Application No. 2019-014771), another full-range technique is proposed in which, based on a plurality of OCT data sets having different optical path lengths when detecting spectral interference signals, at least an interpolation process is performed on an overlapping region between a real image and a virtual image in the OCT data, and OCT data subjected to the interpolation process is generated. This technique may be applied to the present embodiment.

[0030] <Position Guidance of Light-Guiding Optical System> For example, the arithmetic and control device guides the three-dimensional position of the light-guiding optical system with respect to the subject's eye so that the pivot point is located at a target position. When the pivot point reaches the target position as a result of the guidance, an operation of acquiring OCT data is executed.

[0031] The position guidance of the light-guiding optical system for positioning the pivot point at the target position may be so-called auto-alignment. That is, the alignment adjustment unit may be driven and controlled by an arithmetic controller to move the light-guiding optical system in a direction that reduces the deviation between the position of the pivot point and the target position. Furthermore, instead of or in addition to auto-alignment, guide information may be output to the examiner to assist in alignment so that the pivot point is positioned at the target position. The guide information may be graphical information (e.g., text information, graphic information, etc., details of which will be described later) displayed on a monitor, or audio information output from a speaker. For example, the guide information may be operation guidance for the examiner.

[0032] In this embodiment, the target position of the pivot point is set between the eye and the objective optical system, and may be set at a position a predetermined distance in the anterior-posterior direction from the corneal apex.

[0033] Because the target position is between the subject's eye and the objective optical system, the measurement light that is not parallel to the optical axis is incident on the cornea of ​​the subject's eye while moving away from the optical axis of the optical system. This measurement light is guided to the various tissues in the anterior segment and the fundus without intersecting with the optical axis again inside the eyeball. This allows the measurement light to be irradiated over a wider area of ​​the subject's eye.

[0034] Here, the difference in measurement range between this embodiment and two comparative examples (Comparative Examples 1 and 2) in which the measurement light is guided to the eye without a pivot point being formed between the eye and the objective optical system is shown.

[0035] In Comparative Example 1, the pivot point is located within the eyeball of the subject's eye. In Comparative Example 1, it is difficult for the measurement light to irradiate and photograph areas of the subject's eye at depth positions near the pivot point. In contrast, in this embodiment, the pivot point is set between the subject's eye and the objective optical system, so the pivot point is not located within the eyeball of the subject's eye, and therefore it is easier to photograph tissues at each depth position than in Comparative Example 1.

[0036] In Comparative Example 2, measurement light is irradiated from the objective optical system to the subject's eye in a substantially telecentric manner. Because the telecentric light beam is refracted by the optically transparent body of the subject's eye, the measurement light reaching the fundus is concentrated approximately at the center of the fundus (near the fovea centralis). Therefore, in Comparative Example 2, it is difficult to ensure an imaging range on the fundus. In contrast, in this embodiment, the measurement light is incident on the cornea of ​​the subject's eye from a pivot point between the subject's eye and the objective optical system, moving away from the optical axis of the optical system. Therefore, even if the measurement light is refracted by the optically transparent body of the subject's eye, the measurement light is likely to be irradiated to positions away from the approximate center of the fundus (near the fovea centralis) (i.e., imaging is possible).

[0037] In the OCT apparatus according to this embodiment, the scanning amount of the measurement light may be set so that the measurement light is intentionally blocked by the iris at the target position. In this case, as a result of executing the OCT data acquisition operation at the target position, OCT data including at least the cornea, fundus, and iris can be acquired in one go (in other words, in one shot).

[0038] Since the OCT data acquired in one shot contains positional information of the cornea, iris, and fundus, the positional relationship between the fundus and the anterior segment can be appropriately identified. Furthermore, since the positional relationship between the fundus and the anterior segment can be appropriately identified, the OCT data can be appropriately combined (collaged) with local OCT data of the anterior segment or fundus.

[0039] <Adjustment of Measurement Range in Depth Direction> The OCT apparatus of this embodiment may include a second adjustment unit. The second adjustment unit may be controlled by an arithmetic and control device, thereby making the measurement range in the depth direction of the OCT data adjustable (changeable). For example, the measurement range in the depth direction may be switchable between at least a first measurement range and a second measurement range narrower than the first measurement range, based on control by the second adjustment unit.

[0040] For example, in the case of SS-OCT, one or both of the wavelength swept light source and the converter may be used as the second adjuster. In this case, the width of the measurement range in the depth direction of the OCT data is changed by changing one or both of the sweep frequency and the sampling period of the interference signal. In this embodiment, at least when the OCT data acquisition operation is performed at a target position set between the subject's eye and the objective optical system, the measurement range may be adjusted so that the measurement range includes the cornea to the fundus. More specifically, the width of the measurement range in the depth direction may be adjusted so that the measurement range is greater than the axial length of the subject's eye.

[0041] The second adjustment unit may also include an optical path length difference adjustment unit. The optical path length difference adjustment unit changes at least one of the optical path length of the measurement light and the optical path length of the reference light. In this way, the optical path length difference adjustment unit adjusts the optical path length difference between the measurement light and the reference light. The measurement range is displaced in the depth direction according to the optical path length difference. Note that the optical path length difference adjustment unit may be a device that changes the optical path length of at least one of the optical path of the light guide optical system on the upstream side (light source side) of the objective optical system and the optical path of the reference optical system.

[0042] The OCT apparatus of this embodiment may also include a focus adjustment unit that adjusts the focus position of the measurement light.

[0043] The arithmetic and control device may acquire a plurality of OCT data sets with different focus positions of the measurement light at a target position where a pivot point is disposed between the test eye and the objective optical system, and may synthesize the plurality of OCT data sets to acquire synthesized OCT data. This makes it easier to acquire OCT data with high overall brightness even when the depth of field of the OCT optical system is not sufficiently large compared to the axial length of the eye.

[0044] Second Embodiment Next, a second embodiment will be described. An ophthalmic image processing program according to the second embodiment is executed by a processor of an ophthalmic computer, causing the ophthalmic computer to execute an ophthalmic image processing method including the following steps. The ophthalmic computer may be integrated with or separate from the OCT device. If the ophthalmic computer and the ophthalmic imaging device are separate, they are connected by wire or wirelessly and can communicate with each other.

[0045] For convenience of explanation, unless otherwise specified, in the description of the embodiments and examples, the ophthalmologic computer will be described as being integrated with the OCT apparatus, in which case the ophthalmologic image processing program is executed by the arithmetic and control unit.

[0046] <Acquisition Step> In the second embodiment, the arithmetic and control device may acquire wide-field OCT data of the subject's eye. The wide-field OCT data includes at least OCT data of the anterior segment and OCT data of the fundus. The fundus OCT data is acquired in a state where the pivot point of the measurement light is positioned closer to the subject's eye than the objective optical system. As a result, the wide-field OCT data in this embodiment contains a sufficient amount of information to identify the optical characteristics of the subject's eye in the transverse direction of the fundus.

[0047] The wide-area OCT data may be captured in one shot using the imaging method described in the first embodiment. Alternatively, the wide-area OCT data may be captured in one shot with the pivot point positioned inside the eyeball of the subject's eye.

[0048] <Analysis step> The calculation controller may acquire information representing the tilt of the anterior segment relative to the fundus (hereinafter, for convenience, referred to as tilt information) by analyzing wide-area OCT data (for example, B-scan data acquired at the target position in the first embodiment).

[0049] For example, information indicating the tilt of the anterior segment relative to the fundus may be obtained by analyzing B-scan data including the cornea, iris, and fundus as wide-area OCT data. In this case, for example, the tilt information may be obtained based on the positional relationship between the pupil center and the fovea based on the fundus. The pupil center may be the center of the edge of the iris, or more preferably, the center of the outer edge of the iris (which may be the position of the iris angle).

[0050] For example, the line connecting the pupil center and the fovea may be acquired as tilt information. The line itself, or the amount of deviation between the line and the reference axis of the device or the subject's eye, may be acquired as tilt information.

[0051] The amount of deviation may be calculated as, for example, the angle between the line connecting the pupil center and the fovea and the optical axis of the OCT optical system. For example, it may be possible to propose a more appropriate IOL prescription based on the tilt information.

[0052] Furthermore, the physiological strabismus angle of the subject's eye may be calculated as the tilt information. Examples of physiological strabismus angles include α angle, γ angle, κ angle, and λ angle. Any of these physiological strabismus angles may be obtained by analyzing wide-area OCT data.

[0053] If the wide-area OCT data includes the cornea, the crystalline lens, and the fovea of ​​the fundus, the physiological angle of strabismus can be determined based on the wide-area OCT data, the cornea, the crystalline lens, and the fovea of ​​the fundus.

[0054] Here, we will explain the case of measuring the κ angle, one of the physiological strabismus angles, using wide-area OCT data captured with the measurement light pivot point adjusted to the anterior segment of the eye. The κ angle is defined as the angle between the visual axis of the eye and the pupil centerline, and the visual axis is approximated by an A-scan passing through the retinal fovea. The optical axis of the eye is identified from information about the cornea and lens in the OCT data. For example, from shape information about the cornea and lens in the OCT data, an A-scan passing through the centers of curvature of the cornea and lens (more specifically, the centers of curvature of the anterior and posterior surfaces) is approximated as the optical axis of the eye. For example, see the method described in Non-Patent Document 1 below. Because the pupil centerline is also used as the optical axis of the eye (Gullstrand's optic axis), the κ angle can be easily estimated based at least on the displacement between two A-scans (details will be described later in the Examples). Since the α angle is the angle between the optical axis of the eye and the visual axis, the κ angle calculated as described above may be essentially the same as the α angle. Hyung-Jin Kim, et al. "Full ocular biometry through dual-depth whole-eye optical coherence tomography" Biomedical Optics Express Vol. 9, Issue 2, pp. 360-372 (2018) Here, if the cornea and lens in the wide-area OCT data include at least a corneal bright spot and a lens bright spot, a straight line passing through the corneal bright spot and the lens bright spot can be calculated as the optical axis of the eye (and the pupil centerline). This makes it possible to identify the optical axis of the eye (and the pupil centerline) even when it is difficult to detect the curves of the cornea and lens in the wide-area OCT data. Therefore, the optical axis of the eye (and the pupil centerline) itself, as well as tilt information based on these, can be easily obtained from one-shot wide-area OCT data captured with the focus on the fundus side.

[0055] If the curves of the cornea and lens can be detected in the wide-area OCT data, the centers of curvature of the cornea and lens can be determined based on their curve shapes, and the optical axis of the eye can also be determined based on the centers of curvature of the cornea and lens.

[0056] Furthermore, if the wide-area OCT data includes a wide range of anterior segment OCT, the pupil centerline can be determined more precisely anatomically as a straight line that passes through the center of the pupil and is perpendicular to the cornea by using information on the iris (more preferably the iris angle) and the cornea. The pupil centerline determined in this manner may be used in calculating the κ angle.

[0057] Furthermore, various reference axes of the eye or information based on the reference axes may be obtained by analyzing the wide-area OCT data. The reference axes may be, for example, any of the visual axis, gaze line, aiming line, pupil center line, and eye axis. Furthermore, it is considered that physiological strabismus angles other than the α angle and the κ angle can be determined by utilizing this information.

[0058] EXAMPLES An OCT system (optical coherence tomography system) shown in FIGS. 1 and 2 will be described below as an example.

[0059] The OCT system of this embodiment switches the measurement range in the subject's eye E. By switching the imaging mode, the fundus, the anterior segment, and the entire eyeball of the subject's eye are photographed in each imaging mode.

[0060] 1, the OCT system according to the embodiment includes at least an optical unit 10 and a control unit 50, which corresponds to the computer of the embodiment. In the embodiment, the optical unit 10 and the control unit 50 are integrated as an OCT device. The OCT system (OCT device) according to the embodiment has a basic configuration of swept-wavelength OCT (SS-OCT).

[0061] The optical unit 10 includes a light-guiding optical system 150. Furthermore, the optical unit 10 in this embodiment includes a fundus observation optical system 200 and an anterior eye observation optical system 300.

[0062] The optical unit 10 can be moved three-dimensionally by an XYZ moving unit 15. In this embodiment, the XYZ moving unit 15 is driven and controlled by an arithmetic controller 70. In this embodiment, the XYZ moving unit 15 moves the optical unit 10 three-dimensionally, thereby adjusting the three-dimensional position of the optical unit 10 with respect to the subject's eye E. This aligns the three-dimensional position of the optical unit 10 with respect to the subject's eye E. In addition, the subject's face is supported by a face support unit 17. The support position of the face by the face support unit 17 can be moved in the up and down directions.

[0063] The control unit 50 is a computer in this embodiment, and includes at least an arithmetic and control device (processor) 70 that controls the entire OCT system. The arithmetic and control device 70 is configured with, for example, a CPU, a memory, etc. As an example, in this embodiment, the arithmetic and control device 70 also serves as an image processor in the OCT system.

[0064] The OCT system may also be provided with a storage unit (memory) 72, an input interface (operation unit) 75, a monitor 80, etc. Each unit is connected to the arithmetic and control unit 70.

[0065] Various programs, initial values, and the like for controlling the operation of the OCT apparatus may be stored in the memory 72. For example, a hard disk drive, a flash ROM, or a USB memory that is detachably attached to the OCT apparatus may be used as the memory 72. Furthermore, the memory 72 may store various information related to imaging in addition to OCT images generated from OCT data. The monitor 80 may display the OCT data (OCT images).

[0066] <OCT optical system> Next, the OCT optical system 100 in this embodiment will be described with reference to Fig. 2. The OCT optical system 100 guides measurement light to the subject's eye E using a light-guiding optical system 150. The OCT optical system 100 guides reference light to a reference optical system 110. The OCT optical system 100 causes a detector (light-receiving element) 120 to receive spectral interference signal light obtained by interference between the measurement light reflected by the subject's eye E and the reference light.

[0067] In this embodiment, the SS-OCT system is used for the OCT optical system 100. In this case, the OCT optical system 100 has a wavelength swept light source as the OCT light source 102. The OCT optical system 100 also has a point detector as the detector 120.

[0068] The wavelength swept light source swept the emission wavelength over time. The OCT light source 102 may be a VCSEL-type swept light source. The VCSEL-type swept light source includes a VCSEL that performs laser oscillation and a MEMS that realizes high-speed scanning. In this embodiment, a device capable of changing the sweep frequency (scan rate) is used as the VCSEL-type swept light source. For example, the OCT light source 102 in this embodiment can change to a plurality of sweep frequencies in a range from at least 20 kHz (the second frequency in this embodiment) to 400 kHz (the first frequency in this embodiment).

[0069] In this embodiment, the detector 120 is a balanced detector that performs balanced detection using multiple (e.g., two) detectors. The arithmetic and control unit 70 samples the interference signal between the reference light and the returned light of the measurement light in response to changes in the wavelength emitted by the wavelength swept light source, and obtains OCT data of the subject's eye based on the interference signal at each wavelength obtained by sampling. In this embodiment, the sampling period is appropriately adjusted so that the measurement range in the depth direction is changed in response to the sweep frequency of the OCT light source 102.

[0070] The coupler (splitter) 104 is used as a first optical splitter and splits the light emitted from the light source 102 into a measurement optical path and a reference optical path. The coupler 104, for example, guides the light from the light source 102 to an optical fiber 152 on the measurement optical path side and also guides the light to the reference optical system 110 on the reference optical path side.

[0071] <Light Guiding Optical System> The light guiding optical system 150 is provided to guide the measurement light to the eye E. The light guiding optical system 150 may be provided, for example, with an optical fiber 152, a collimator lens 153, a focusing lens 155, an optical scanner 156, and an objective lens system 158 (the objective optical system in this embodiment) in that order. In this case, the measurement light is emitted from the exit end of the optical fiber 152 and converted into a parallel beam by the collimator lens 153. The measurement light then travels toward the optical scanner 156 via the focusing lens 155. The focusing lens 155 is displaceable along the optical axis by a drive unit (not shown) and is used to adjust the focusing state. The light that has passed through the optical scanner 156 is irradiated onto the eye E via the objective lens system 158. In this embodiment, a pivot point P is formed at a position conjugate with the optical scanner 156 with respect to the objective lens system 158 (provided in the device main body). In this embodiment, as described below, the position of the pivot point P relative to at least one of the subject's eye E and the optical system of the device is changed depending on the measurement range in the depth direction of the subject's eye E (in other words, the photographed area).

[0072] The optical scanner 156 may scan the measurement light in the X and Y directions (transverse directions) on the tissue of the subject's eye E. In this embodiment, the optical scanner 156 is, for example, two galvanometer mirrors, the reflection angle of which is arbitrarily adjusted by a drive mechanism. The light beam emitted from the light source 102 has its reflection (propagation) direction changed, and is scanned in an arbitrary direction on the tissue of the subject's eye E. As the optical scanner 156, for example, a reflection mirror (galvanometer mirror, polygon mirror, resonant scanner), or an acousto-optical element (AOM) that changes the propagation (deflection) direction of light may be used.

[0073] The scattered light (reflected light) from the eye E due to the measurement light travels back along the path taken when the light was projected, enters the optical fiber 152, and reaches the coupler 104. The coupler 104 guides the light from the optical fiber 152 to an optical path leading to the detector 120.

[0074] <Reference Optical System> The reference optical system 110 generates reference light. The reference light is combined with the measurement light reflected from the subject's eye E. The reference light that has passed through the reference optical system 110 is combined with light from the measurement optical path by a coupler 148 and interferes with the light. The reference optical system 110 may be a Michelson type or a Mach-Zehnder type.

[0075] 2 is formed by a transmission optical system, for example. In this case, the reference optical system 110 transmits the light from the coupler 104 without returning it, thereby guiding it to the detector 120. However, the reference optical system 110 may be formed by a reflection optical system, for example, and may guide the light from the coupler 104 to the detector 120 by reflecting it using the reflection optical system. In this embodiment, an optical path length difference adjustment unit 145 and a polarization adjustment unit 147 are arranged on the optical path from the coupler 104 to the detector 120.

[0076] The optical path length difference adjustment unit 145 is used to adjust the optical path length difference between the measurement light and the reference light. When acquiring OCT data, it is necessary to adjust the optical path length difference between the measurement light and the reference light in advance, at least according to the depth position of the imaging target (a region of the test eye E). In this embodiment, a mirror 145a having two orthogonal surfaces is provided on the reference light path. The optical path length of the reference light path can be increased or decreased by moving this mirror 145a in the direction of the arrow by an actuator 145b. Of course, the configuration for adjusting the optical path length difference between the measurement light and the reference light is not limited to this. For example, in the light-guiding optical system 150, the collimator lens 153 and the coupler may be moved integrally to adjust the optical path length of the measurement light, thereby adjusting the optical path length difference between the measurement light and the reference light.

[0077] In this embodiment, the polarization adjuster 147 adjusts the polarization of the reference light. The polarization adjuster may be disposed on the measurement light path.

[0078] <Acquisition of Depth Information> The arithmetic and control unit 70 processes (Fourier analysis) the spectral signal detected by the detector 120 to obtain OCT data of the subject's eye.

[0079] The spectral signal (spectral data) may be rewritten as a function of wavelength λ and converted into a function I(k) equally spaced with respect to wavenumber k (=2π / λ). Alternatively, the spectral signal may be acquired from the beginning as a function I(k) equally spaced with respect to wavenumber k (K-CLOCK technique). The arithmetic and control unit may obtain OCT data in the depth (Z) domain by Fourier transforming the spectral signal in the wavenumber k space.

[0080] Furthermore, the information after the Fourier transform may be represented as a signal including real and imaginary components in Z-space. The arithmetic and control unit 70 may obtain the OCT data by calculating the absolute values ​​of the real and imaginary components of the signal in Z-space.

[0081] <Explanation of Operation> Next, the operation of the OCT apparatus according to the embodiment will be described based on a flowchart.

[0082] First, the flow up to the photographing will be described with reference to the flowchart of FIG.

[0083] <S1, S2: Setting of Photography Mode> In this embodiment, the photography mode is set in advance based on a selection operation (S1, S2). Here, one of three photography modes corresponding to the measurement range of the subject's eye E is set based on the selection operation. As the photography mode, a fundus mode, an anterior segment mode, and a whole eye mode can be set. The photography mode selection operation may be input via a setting screen. In addition, a scan pattern, photography type, etc. may also be set at this time.

[0084] <Fundus Mode> When the fundus of the subject's eye is to be the measurement range, the fundus mode is selected (S2: Fundus Mode). As shown in FIG. 4A, in the fundus mode, the measurement range is approximately several millimeters around the fundus. In this case, the control unit 70 sets the sweep frequency of the OCT light source 110 to a first frequency (400 kHz in this embodiment) (S3). This adjusts the measurement range in the depth direction to approximately several millimeters.

[0085] In this embodiment, the alignment state and the state of each part of the OCT optical system 100 are adjusted according to the measurement range (S4, S5).

[0086] First, the three-dimensional position of the optical unit 10 is guided relative to the subject's eye E to a position suitable for fundus photography (S4). That is, as shown in FIG. 5A , the three-dimensional position is guided so that the pivot point P is located at the anterior segment of the subject's eye (more specifically, the center of the pupil). By locating the pivot point P at the anterior segment of the subject's eye, the measurement light reaches the fundus without being vignetted by the iris. In response to the operation of the optical scanner 156, the measurement light is scanned around the pivot point P. At this time, the position of the pivot point P substantially coincides with the position of the principal point in the ocular optical system, and therefore is less susceptible to refraction due to the optically transparent body of the subject's eye E. Therefore, in the fundus mode, a wide range of the fundus can be photographed.

[0087] During alignment adjustment, for example, the subject is first asked to gaze at a fixation target, and then the control unit 70 drives and controls the XYZ moving unit 15 based on an anterior eye segment observation image acquired via the anterior eye segment observation optical system 300, thereby adjusting the positional relationship between the subject's eye and the optical unit 10. When alignment adjustment is completed, a front image of the fundus is acquired as an observation image by the observation optical system 200.

[0088] After the alignment is complete, the acquisition of an observation image via the observation optical system 200 and the display of the observation image on the monitor 80 are started. At the same time, the arithmetic and control unit 70 acquires OCT images of the fundus via the OCT optical system 100 as needed.

[0089] Next, optimization control of the imaging conditions is performed (S5). The state of each component of the OCT optical system 100 (i.e., the imaging conditions) is adjusted to match the fundus region that is the measurement range. As a result, the fundus region can be observed with high sensitivity and high resolution by the OCT optical system 100. In this embodiment, optical path length adjustment, focus adjustment, and polarization state adjustment (polarizer adjustment) are performed as examples of optimization control of the OCT optical system 100. In this embodiment, the polarizer adjustment is performed by driving and controlling the polarizer 147 based on the output signal output from the light receiving element 120 so that the polarization states of the measurement light and the reference light match (here, so that a stronger interference signal is obtained) (this also applies to the anterior segment mode and the whole eye mode).

[0090] For example, the optimization control is started by operating an optimization start button (Optimize button) not shown. This adjusts the optical path length difference so that the fundus image is detected within a predetermined interval from the zero delay position in the OCT data. After adjusting the optical path length difference, the focusing lens is driven to adjust the focus position according to the position where the fundus image is detected in the OCT data. However, instead of or in addition to using the OCT data to detect the optimal focus position, focus adjustment in the OCT optical system 100 may be performed in conjunction with focus adjustment in the observation optical system 200 using the observation image.

[0091] In this embodiment, after optimization is complete, the examiner presses a photographing switch (not shown) to photograph (capture) OCT data of the fundus via the OCT optical system 100. At this time, the OCT data may be photographed using any of a plurality of predetermined scan patterns. While FIG. 4B illustrates a B-scan image of the fundus as an example of the OCT data of the fundus obtained by photographing, this is not limiting, and volume data may also be photographed. The photographed OCT data may be stored (saved) in the memory of the device in association with identification information indicating the scan position and the photographing date and time. The photographed OCT data is then acquired as a photographed image by the arithmetic and control unit 70.

[0092] In the fundus mode, OCT data of the peripheral part of the fundus may be captured. In this case, the fixation position is changed from when capturing an image of the central part of the fundus, and optimization control is performed on the peripheral part of the fundus before capturing the OCT data.

[0093] <Anterior Eye Segment Mode> When the anterior eye segment of the subject's eye is to be the measurement range, the anterior eye segment mode is selected (S2: anterior eye segment mode). As shown in FIG. 5A , in the anterior eye segment mode, the measurement range is approximately several millimeters of the anterior eye segment. In this case, the control unit 70 sets the sweep frequency of the OCT light source 110 to a first frequency (400 kHz in this embodiment) (S11). This adjusts the measurement range in the depth direction to approximately several millimeters. As described above, in this embodiment, the sweep frequency is the same between the fundus mode and the anterior eye segment mode, but the sweep frequencies in each mode may be different.

[0094] In this embodiment, in the anterior segment mode, the anterior segment adapter 500 is attached to the device (S12). By attaching the anterior segment adapter 500, the adapter lens 500a is inserted between the objective lens system 158 of the device body and the subject's eye E (in this embodiment, between the pivot point P and the subject's eye E). This causes the pivot point P to approximately coincide with the focal position of the adapter lens 500a. As a result, the measurement light is emitted approximately parallel to the optical axis via the adapter lens 500a. In other words, the objective lens system 158 of the device body and the adapter lens 500a form an optical system that is telecentric on the object side as the objective optical system in the anterior segment mode.

[0095] This reduces the change in magnification of the captured image due to changes in the position of the subject's eye E, making it easier to accurately measure the intraocular distance based on the captured tomographic image of the anterior segment. Furthermore, because the measurement light is telecentrically irradiated on the object side, distortion of the tomographic image due to misalignment of the subject's eye E in the working distance direction is less likely to occur. Furthermore, being telecentric on the object side makes it easier for the measurement light to be irradiated to areas of the subject's eye E that are far from the visual axis, and improves the recovery efficiency of returned light (reflected light or backscattered light) from the anterior segment, thereby suppressing a decrease in brightness in the peripheral areas of the image.

[0096] Next, alignment adjustment is performed (S13). At this time, for example, alignment adjustment between the subject's eye E and the optical unit 10 may be performed based on an observation image acquired by the observation optical system 200.

[0097] Next, optimization control of the imaging conditions is performed (S14). The state of each part of the OCT optical system 100 is adjusted to match the anterior segment, which is the measurement range. As a result, the anterior segment can be observed with high sensitivity and high resolution by the OCT optical system 100. When imaging the anterior segment, individual differences in the subject's eye E are not as important as when imaging the fundus. Therefore, for example, the optical path length, focus position, etc. may be adjusted to approximately constant values ​​regardless of the subject's eye E.

[0098] Next, when the examiner presses a photographing switch (not shown), OCT data of the anterior segment (see FIG. 5B) is photographed (captured) via the OCT optical system 100 and stored (saved) in the memory of the device.

[0099] In the anterior segment mode, OCT data of the anterior segment, including the iridocorneal angle and the sclera, may be captured. In this case, the image capturing may be performed after shifting the alignment position in the X and Y directions relative to the visual axis. Furthermore, OCT data of the anterior segment, including the anterior and posterior surfaces of the crystalline lens, may be captured.

[0100] <Whole Eye Mode> When the entire eyeball (here, the anterior segment and the fundus) of the subject's eye is to be the measurement range, the whole eyeball mode is selected (S2: Whole Eye Mode). In this embodiment, as shown in FIG. 6A , in the whole eyeball mode, the entire eyeball, including the anterior segment and the fundus, is the measurement range. In this case, the control unit 70 sets the sweep frequency of the OCT light source 110 to a second frequency (20 kHz in this embodiment) (S21). This adjusts the measurement range in the depth direction to approximately 30 mm.

[0101] In this embodiment, the alignment state and the state of each part of the OCT optical system 100 are adjusted according to the measurement range (S22, S23).

[0102] First, the three-dimensional position of the optical unit 10 is guided relative to the subject's eye E to a position suitable for whole-eye imaging (S22). That is, as shown in FIG. 6A , the three-dimensional position is guided so that the pivot point P is located between the subject's eye and the objective lens system 158. By locating the pivot point P between the subject's eye and the objective lens system 158, the measurement light can be irradiated onto the cornea, fundus, and part of the iris. Therefore, in the whole-eye mode of this embodiment, OCT data including at least the cornea, fundus, and part of the iris can be acquired in one shot. From such whole-eye OCT data, the positional relationship between the fundus and the anterior segment can be appropriately determined.

[0103] In the whole eye mode of this embodiment, alignment adjustment in at least the X and Y directions is performed based on an anterior eye observation image acquired via the anterior eye observation optical system 300. Alignment adjustment in the Z direction may be performed based on an alignment target image projected onto the cornea of ​​the subject's eye from an alignment projection optical system (not shown). Alternatively, alignment may be performed based on OCT data acquired by the OCT optical system 100. Alignment may be automatically adjusted by the control unit 70.

[0104] After the alignment is complete, the acquisition of an observation image via the observation optical system 200 and the display of the observation image on the monitor 80 are started. At the same time, the arithmetic and control unit 70 acquires whole-eye OCT images as needed via the OCT optical system 100.

[0105] In the optimization control of the imaging conditions in the whole eye mode (S23), the state of each part of the OCT optical system 100 (i.e., the imaging conditions) is adjusted to match the measurement range. The optical path length difference is adjusted so that images of the anterior eye segment and the fundus are detected within a predetermined interval from the zero delay position in the OCT data. Furthermore, the focusing lens may be driven to adjust the focus position depending on the position at which the images of the anterior eye segment and the fundus are detected in the OCT data. The focus position may be adjusted to be near either the image position of the anterior eye segment or the fundus, or may be adjusted to be midway between the anterior eye segment and the fundus.

[0106] In this embodiment, after optimization is completed, when the examiner presses a photographing switch (not shown), OCT data of the entire eye (see FIG. 6B) is photographed (captured) via the OCT optical system 100 and saved.

[0107] <Curvature Correction> Note that, in each of the OCT data shown in Figures 4B, 5B, and 6B, images are formed by arranging A-scan data parallel to the scanning direction (linear direction) of the measurement light. The fundus OCT data and whole-eye OCT data are expressed on polar coordinates centered on the pivot point P, thereby correcting the image curvature resulting from scanning centered on the pivot point P. The corrected OCT data is expressed as an image that is more accurate with respect to the actual shape of the subject's eye. When converting the fundus OCT data and whole-eye OCT data to polar coordinates, the curvature of the image of the tissue within the eye may be corrected taking into account the refraction of the measurement light by the optic body of the subject's eye. In this case, the curvature may be corrected by ray tracing, for example.

[0108] Furthermore, for anterior segment OCT data, if the measurement light is not perfectly parallel to the optical axis, the image curvature may be corrected according to the inclination of the light beam relative to the optical axis of the OCT optical system 100 during each A-scan.

[0109] <Collage> Whole-eye OCT data captures a wide area of ​​the subject's eye in the depth direction, but anterior-eye OCT data and fundus OCT data can capture each part more widely in the transverse direction. Therefore, an OCT image with a wider area is generated by combining the anterior-eye OCT data and fundus OCT data with the whole-eye OCT data. Curvature correction may be performed on each of the combined OCT data. A wide-area OCT image may be generated by aligning the images with respect to feature portions contained in each image and combining them. The alignment between the images may be rigid registration or non-rigid registration.

[0110] Since the positional relationship between the fundus and the anterior segment can be appropriately identified in the whole-eye OCT data, local OCT data of the anterior segment or the fundus can be appropriately combined (collaged) with the whole-eye OCT data. In other words, a wide-area OCT image that reflects the actual positional relationship between the fundus and the anterior segment can be generated.

[0111] For example, to obtain the OCT image shown in Fig. 7 , multiple OCT data sets for the anterior segment and the fundus may be combined with the OCT data for the whole eye. More specifically, with regard to the anterior segment, OCT data for the anterior segment including the angle to the sclera and OCT data for the anterior segment including the anterior and posterior surfaces of the crystalline lens may each be combined with the OCT data for the whole eye. Furthermore, with regard to the fundus, for example, OCT data for the fundus captured by aligning the optical axis of the OCT optical system 100 with the fixation optical axis and OCT data for the fundus captured by tilting the fixation optical axis with respect to the optical axis of the OCT optical system 100 may each be combined with the OCT data for the whole eye.

[0112] <Analysis Processing> Various analysis processing may be performed on the whole-eye OCT data (or the above-described composite image based on the whole-eye OCT data). For example, analysis processing related to eye dimension information may be performed. The analysis processing may determine any of various eye dimension information such as corneal thickness, anterior chamber depth, axial length, and anterior chamber angle.

[0113] Furthermore, information regarding the positional relationship of each part may be obtained based on the whole-eye OCT data (or the above-described composite image based on the whole-eye OCT data). In particular, information indicating the inclination of the anterior eye segment with respect to the fundus may be obtained.

[0114] As shown in FIG. 8 , in this embodiment, a line connecting the fundus fovea and the pupil center is detected as an axis L1 based on the whole-eye OCT image (or the above-described composite image based on the whole-eye OCT data). The tilt angle of the axis L1 relative to the optical axis of the OCT optical system 100 is further derived. The position information of the axis L1 itself and the tilt angle of the axis L1 relative to the optical axis of the OCT optical system 100 are obtained as information representing the tilt of the anterior segment relative to the fundus. In this way, the whole-eye OCT data includes position information of the cornea, iris, and fundus, making it possible to appropriately identify the positional relationship between the fundus and the anterior segment. As a result, for example, it may be possible to more appropriately position the IOL when prescribing an IOL.

[0115] "Modifications" The above description has been given based on the embodiments and examples, but the present disclosure is not necessarily limited to these and various modifications are possible.

[0116] For example, the OCT device in the above embodiment could be switched between fundus mode, anterior segment mode, and whole eye mode by changing the sweep frequency, but this is not necessarily limited to this, and the OCT device may be capable of capturing images at least in whole eye mode.

[0117] Furthermore, for example, the OCT apparatus does not need to include two or more optical scanners, and the OCT apparatus may be capable of scanning the measurement light in only one direction using only one optical scanner.

[0118] <Measurement Method Advantageous for Obtaining Physiological Strabismus Angle> In the above embodiment, in the whole eye mode, the three-dimensional position is guided so that the pivot point P is located within the eyeball of the subject's eye, as shown in FIG. 6A . In this state, the three-dimensional position may be further guided so that the corneal bright spot, the lens bright spot, and the fundus central fovea are included in the tomographic image, and wide-area OCT data may be acquired after the three-dimensional position is guided. For example, while the three-dimensional position is being guided, the presence or absence of a corneal bright spot and a lens bright spot may be detected in tomographic images acquired at any time, and the OCT data may be automatically guided to a position where the corneal bright spot and the lens bright spot are detected. Furthermore, while the three-dimensional position is being guided, tomographic images acquired at any time may be displayed, and the examiner may manually adjust the three-dimensional position.

[0119] An example of the OCT data acquired at this time is shown as a tomographic image in Fig. 9. Note that the tomographic image shown in Fig. 9 may be one that has undergone full-range processing.

[0120] As a result of the rotation point of the measurement light being positioned closer to the test eye (preferably the anterior segment) than the objective lens, a wide area of ​​the fundus is scanned, and as shown in the tomographic image of Figure 9, it can be seen that there is sufficient information in the transverse direction of the fundus to identify the optical characteristics of the test eye.

[0121] Furthermore, bright spots appear in the cornea and crystalline lens in the tomographic image shown in Fig. 9. The bright spots are thought to appear at the center of the optical axis of the subject's eye, as shown in the schematic diagram.

[0122] The κ angle, which is an example of a physiological strabismus angle, is defined as the angle between the visual axis of the test eye and the pupil centerline, where the visual axis is an A-scan passing through the fovea of ​​the retina. Furthermore, the A-scan corresponding to the optical axis of the eye is identified from information on the cornea and lens in the OCT data. By regarding the optical axis of the eye and the pupil centerline as the A-scan, the κ angle can be estimated based at least on the displacement between the two A-scans.

[0123] That is, since the number of A-scans that occupy the angle of view is generally known, the approximate value of the κ angle can be obtained by converting the displacement amount of two A-scans into the angle of view.

[0124] In this case, since the scanning direction of the wide-area OCT data is reversed between the front and back sides of the rotation point of the measurement light, the κ angle may be calculated as described above after correcting the scanning direction on the image or in calculations.

[0125] 9, OCT data covering the cornea and fundus can be used to obtain eye dimension information such as corneal thickness, anterior chamber depth, and axial length. The κ angle is used as an indicator of whether a toric IOL prescription is appropriate for the subject's eye, and eye dimension information is used in IOL calculations. Therefore, since information used in IOL prescriptions can be obtained appropriately, it is possible to prescribe a more appropriate IOL.

[0126] The OCT device according to the present disclosure can also be expressed as follows.

[0127] For example, the first ophthalmic image processing program is executed by a processor of an ophthalmic computer to cause the ophthalmic computer to perform an acquisition step of acquiring wide-area OCT data of the test eye, the wide-area OCT data including at least OCT data of the anterior segment and OCT data of the fundus acquired when the rotation point of the measurement light is positioned closer to the test eye than the objective optical system, and an analysis step of determining the physiological strabismus angle of the test eye by analyzing the wide-area OCT data.

[0128] The second ophthalmologic image processing program is the same as the first ophthalmologic image processing program, except that the wide-area OCT data includes OCT data of the anterior segment and OCT data of the fundus captured in one shot.

[0129] A third ophthalmologic image processing program is the second ophthalmologic image processing program, wherein the wide-area OCT data is captured with the turning point of the measurement light adjusted to the anterior segment of the subject's eye.

[0130] The fourth ophthalmologic image processing program is the third ophthalmologic image processing program, wherein the wide-area OCT data includes the cornea, the lens, and the fovea of ​​the fundus, and in the analysis processing step, the physiological strabismus angle is calculated based at least on the positional relationship between the cornea, the lens, and the fovea of ​​the fundus in the OCT data.

[0131] The fifth ophthalmic image processing program is the fourth ophthalmic image processing program, wherein the cornea and lens in the wide-area OCT data include at least corneal bright spots and lens bright spots, and in the analysis processing step, the physiological strabismus angle is calculated based at least on the positional relationship between the corneal bright spots, the lens bright spots, and the fovea centralis of the fundus in the OCT data.

[0132] The sixth OCT apparatus executes the ophthalmologic image processing program according to any one of the first to fifth OCT apparatuses.

[0133] The sixth OCT device aligns the OCT optical system for acquiring the wide-area OCT with respect to the subject's eye so that the wide-area OCT data includes the corneal bright spot and the lens bright spot.

Claims

1. an OCT optical system including a light splitter for splitting light from an OCT light source into a measurement light and a reference light, and a detector for detecting a spectral interference signal between the measurement light and the reference light guided to a subject's eye; An arithmetic and control device that acquires OCT data based on a signal from the detector and at least controls the OCT optical system to perform an operation of acquiring the OCT data, a light guiding optical system including at least an optical scanner that scans the measurement light on tissue of the subject's eye, and an objective optical system that is disposed between the optical scanner and the subject's eye and forms a rotation point around which the measurement light that has passed through the optical scanner is rotated; an alignment adjustment unit that adjusts a three-dimensional position of the light-guiding optical system with respect to the subject's eye, An OCT apparatus, wherein the arithmetic controller guides the three-dimensional position so that the pivot point is positioned at a target position set between the test eye and the objective optical system, and further performs an operation of acquiring the OCT data at the target position.

2. A second adjustment unit that adjusts a measurement range in a depth direction in the OCT data, The OCT apparatus according to claim 1 , wherein the arithmetic and control unit controls the second adjustment unit so that the measurement range includes an area from the cornea to the fundus when performing an operation of acquiring the OCT data at the target position.

3. Further, the OCT light source includes a wavelength swept light source, A converter for sampling the spectral interference signal output from the detector and converting the signal from an analog signal to a digital signal, The second adjustment unit is at least one of the wavelength swept light source and the conversion unit, 3. The OCT apparatus according to claim 2, wherein the arithmetic controller controls either a sweep frequency of the wavelength swept light source or a sampling rate of the spectral interference signal in the conversion unit so that the measurement range is greater than the axial length of the test eye.

4. Further, a focus adjustment unit is provided for adjusting a focus position of the measurement light, 4. The OCT device according to claim 1, wherein the arithmetic controller adjusts a focus position of the measurement light to a first focus position at the target position to acquire first OCT data, further adjusts the focus position to a second focus position different from the first focus position to acquire second OCT data, and synthesizes the first OCT data and the second OCT data to acquire synthetic OCT data.

5. 5. The OCT device according to claim 1, wherein the arithmetic controller executes the operation of acquiring the OCT data at the target position so that the B-scan data of the OCT data includes the cornea, iris, and fundus of the test eye.

6. The OCT apparatus according to claim 5 , wherein the arithmetic and control unit acquires information indicating an inclination of the anterior segment with respect to the fundus by analyzing the B-scan data.