Ophthalmic device, control method, program and storage medium thereof

Abstract

An ophthalmic device, a control method thereof, and a storage medium. The ophthalmic device can measure the axial length of the eye with high reliability regardless of the movement of the eye to be inspected. The ophthalmic device of the exemplary embodiment performs a first optical coherence tomography scan of a first area including a first part of the eye to be inspected and a second optical coherence tomography scan of a second area including a second part. The ophthalmic device acquires first offset information of the eye to be inspected before the first optical coherence tomography scan and performs alignment, and acquires second offset information before the second optical coherence tomography scan and performs alignment. The ophthalmic device calculates the distance between the first part and the second part of the eye to be inspected based on the first data acquired through the first optical coherence tomography scan and the second data acquired through the second optical coherence tomography scan.

Description

[0001] This application is a divisional application with an application date of September 12, 2019, application number 201910866660.0, and invention name “Ophthalmic device, control method, program and storage medium thereof”. Technical Field

[0002] The present invention relates to an ophthalmic device and a control method, program and storage medium thereof. Background Art

[0003] Ophthalmic devices capable of measuring axial length of the eye are known. For example, Patent Document 1 discloses a technique for measuring axial length of the eye using optical coherence tomography (OCT). Axial length of the eye is defined as the distance between the corneal vertex and the macula (fovea), and is an intraocular parameter useful for selecting the power of an intraocular lens and confirming axial refractive error before cataract surgery.

[0004] As mentioned above, the axial length is defined as the distance between the corneal vertex and the macula, so to measure the axial length, it is necessary to know both the corneal position and the retinal position. In the invention disclosed in Patent Document 1, there is a time difference between the first measurement for determining the corneal position (OCT scan in anterior ocular mode) and the second measurement for determining the retinal position (OCT scan in posterior ocular mode). Therefore, when the eye under examination moves between the first measurement and the second measurement, there is a possibility that the axial length cannot be accurately measured. In particular, the movement of the eye under examination in a direction orthogonal to the longitudinal direction (depth direction) risks significantly reducing the reliability of the measured value of the axial length.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2016-19634 Summary of the invention

[0008] An object of the present invention is to provide a technique capable of performing highly reliable eye axial length measurement regardless of the movement of the eye to be examined.

[0009] A first aspect of an exemplary embodiment provides an ophthalmologic apparatus comprising: a scanning unit for applying optical coherence tomography (OCT) to an eye to be inspected; a scanning control unit that performs a first scanning control and a second scanning control, wherein the first scanning control causes the scanning unit to perform an optical coherence tomography scanning of a first area, the first area includes a first part of the eye to be inspected, and the second scanning control causes the scanning unit to perform an optical coherence tomography scanning of a second area, the second area includes a second part different from the first part; an alignment control unit that performs a first alignment control and a second alignment control, wherein the first alignment control controls the moving mechanism based on first offset information of the eye to be inspected acquired by the offset measuring unit before the first scanning control, and the second alignment control controls the moving mechanism based on second offset information of the eye to be inspected acquired by the offset measuring unit before the second scanning control; and a distance calculation unit that calculates the distance between the first part and the second part based on first data acquired by the scanning unit under the first scanning control and second data acquired by the scanning unit under the second scanning control.

[0010] A second mode of the exemplary embodiment is an ophthalmic device according to the first mode, wherein the scanning unit includes: an interference optical system, including a measuring arm that guides measurement light to the eye to be examined, and a reference arm that guides reference light; and an arm length changing unit, which is arranged on at least one of the measuring arm and the reference arm and changes the arm length under the control of the scanning control unit, and the distance calculating unit calculates the difference between the first arm length applicable under the first scanning control and the second arm length applicable under the second scanning control, and analyzes the first data to determine the first position corresponding to the first part, analyzes the second data to determine the second position corresponding to the second part, and calculates the distance based on the difference, the first position and the second position.

[0011] A third mode of an exemplary embodiment provides an ophthalmologic apparatus, comprising: a scanning unit that applies optical coherence tomography (OCT) scanning to an eye to be inspected; a deviation measuring unit that measures a deviation of the eye to be inspected from a predetermined reference position; a scanning control unit that performs a first scanning control and a second scanning control, wherein the first scanning control causes the scanning unit to perform an optical coherence tomography scanning of a first area, the first area including a first part of the eye to be inspected, and the second scanning control causes the scanning unit to perform an optical coherence tomography scanning of a second area, the second area including a second part different from the first part; and a distance calculating unit that calculates a distance between the first part and the second part based on at least one of first deviation information and second deviation information, first data, and second data, wherein the first deviation information is the deviation information of the eye to be inspected acquired by the deviation measuring unit corresponding to the first scanning control, the second deviation information is the deviation information of the eye to be inspected acquired by the deviation measuring unit corresponding to the second scanning control, the first data is the data acquired by the scanning unit under the first scanning control, and the second data is the data acquired by the scanning unit under the second scanning control.

[0012] A fourth embodiment of the exemplary implementation is an ophthalmic device according to the third embodiment, wherein the offset measuring unit obtains an offset information corresponding to one of the first scanning control and the second scanning control, and obtains another offset information before and after the other scanning control of the first scanning control and the second scanning control, and the ophthalmic device further includes: a moving mechanism that moves at least a portion of the scanning unit; and an alignment control unit that performs alignment control of the moving mechanism based on the other offset information before the other scanning control, and the distance calculation unit calculates the distance based on the offset information, the first data, and the second data.

[0013] The fifth mode of the exemplary embodiment is an ophthalmic device according to the third or fourth mode, wherein the scanning unit includes: an interference optical system, including a measuring arm that guides measurement light to the eye to be examined, and a reference arm that guides reference light; and an arm length changing unit, which is arranged on at least one of the measuring arm and the reference arm and changes the arm length under the control of the scanning control unit, and the distance calculation unit calculates the difference between the first arm length applicable under the first scanning control and the second arm length applicable under the second scanning control, and analyzes the first data to determine the first position corresponding to the first part, analyzes the second data to determine the second position corresponding to the second part, and calculates the distance based on the difference, the first position, the second position, and at least one offset information of the first offset information and the second offset information.

[0014] The sixth embodiment of the exemplary implementation is an ophthalmic device according to the fifth embodiment, wherein the distance calculation unit calculates a provisional distance between the first part and the second part based on the difference, the first position and the second position, and calculates the distance based on the provisional distance, at least one offset information of the first offset information and the second offset information, and a corneal curvature radius of the eye to be inspected acquired in advance.

[0015] The seventh embodiment of the exemplary implementation is an ophthalmic device according to the sixth embodiment, wherein, when the provisional distance is set to ALm, one of the first offset information and the second offset information is set to h, the corneal curvature radius is set to r, and the distance is set to AL, the distance calculation unit calculates the distance AL by the calculation formula AL=(rr×cos(arcsin(h / r)))+ALm×cos(arcsin(h / ALm)).

[0016] An eighth embodiment of an exemplary implementation is an ophthalmic device according to any one of the first to seventh embodiments, wherein the scanning control unit causes the scanning unit to perform multiple optical coherence tomography scans under at least one of the first scanning control and the second scanning control, and the distance calculation unit obtains single data from the data group obtained through the multiple optical coherence tomography scans, and uses the single data to calculate the distance.

[0017] A ninth aspect of the exemplary embodiment is the ophthalmologic apparatus according to the eighth aspect, wherein the distance calculation unit generates the single data by performing arithmetic averaging on the data group.

[0018] The tenth embodiment of the exemplary implementation is an ophthalmic device according to any one of the first to seventh embodiments, wherein the scanning control unit causes the scanning unit to perform an optical coherence tomography scan of a three-dimensional area of ​​the eye to be inspected under at least one of the first scanning control and the second scanning control, and the distance calculation unit analyzes data acquired through the optical coherence tomography scan of the three-dimensional area, determines a feature position corresponding to a feature point of the eye to be inspected, and calculates the distance as the length of a line segment having the feature position as one end.

[0019] The eleventh embodiment of the exemplary implementation is an ophthalmic device according to the tenth embodiment, wherein the scanning control unit, under the control of the first scanning, causes the scanning unit to perform an optical coherence tomography scan of a three-dimensional area including the corneal surface of the eye to be inspected, and the distance calculation unit analyzes the data acquired by the optical coherence tomography scan of the three-dimensional area to determine a characteristic position corresponding to the corneal vertex.

[0020] The twelfth mode of the exemplary implementation is an ophthalmic device according to the tenth or eleventh mode, wherein the scanning control unit, under the control of the second scanning, causes the scanning unit to perform an optical coherence tomography scan of a three-dimensional area including the retinal surface of the eye to be inspected, and the distance calculation unit analyzes the data acquired by the optical coherence tomography scan of the three-dimensional area to determine a characteristic position corresponding to the center of the macula.

[0021] The thirteenth embodiment of the exemplary implementation is an ophthalmic device according to any one of the first to twelfth embodiments, wherein the offset measuring unit includes: a projection system that projects a light beam to the anterior segment of the eye to be inspected; two or more photographing units that photograph the anterior segment of the eye to be inspected from different directions; and an offset calculating unit that calculates the offset of the eye to be inspected based on the positions of the light beam images respectively drawn in two or more anterior segment images obtained by the two or more photographing units.

[0022] The fourteenth embodiment of the exemplary implementation is an ophthalmic device according to any one of the first to twelfth embodiments, wherein the offset measuring unit includes: a projection system that projects a light beam from an oblique direction to the anterior ocular portion of the eye to be inspected; an image sensor that detects a reflected light beam of the light beam from the anterior ocular portion; and an offset calculating unit that calculates the offset of the eye to be inspected based on the detection position of the reflected light beam by the image sensor.

[0023] A fifteenth mode of an exemplary embodiment provides a control method for an ophthalmic device, the ophthalmic device comprising: a scanning unit for applying optical coherence tomography (OCT) scanning to an eye to be inspected; a moving mechanism for moving at least a portion of the scanning unit; and a displacement measuring unit for measuring the displacement of the eye to be inspected relative to a predetermined reference position, wherein the control method comprises: a first alignment control step for controlling the moving mechanism based on first displacement information of the eye to be inspected acquired by the displacement measuring unit; a first scanning control step for causing the scanning unit to perform optical coherence tomography scanning of a first area, the first area including a first part of the eye to be inspected; a second alignment control step for controlling the moving mechanism based on second displacement information of the eye to be inspected acquired by the displacement measuring unit; a second scanning control step for causing the scanning unit to perform optical coherence tomography scanning of a second area, the second area including a second part different from the first part; and a distance calculation step for calculating the distance between the first part and the second part based on first data acquired by the scanning unit in the first scanning control step and second data acquired by the scanning unit in the second scanning control step.

[0024] A sixteenth mode of an exemplary embodiment provides a control method for an ophthalmic device, the ophthalmic device comprising: a scanning unit for applying optical coherence tomography (OCT) scanning to an eye to be inspected; and a displacement measuring unit for measuring the displacement of the eye to be inspected from a predetermined reference position, wherein the control method comprises: a first scanning control step for causing the scanning unit to perform optical coherence tomography scanning on a first area, the first area including a first part of the eye to be inspected; a second scanning control step for causing the scanning unit to perform optical coherence tomography scanning on a second area, the second area including a second part different from the first part; a displacement measuring step for causing the displacement measuring unit to perform at least one of a step of acquiring first displacement information of the eye to be inspected corresponding to the first scanning control and a step of acquiring second displacement information of the eye to be inspected corresponding to the second scanning control; and a distance calculating step for calculating the distance between the first part and the second part based on at least one of the first displacement information and the second displacement information acquired by the displacement measuring step, first data acquired by the scanning unit in the first scanning control step, and second data acquired by the scanning unit in the second scanning control step.

[0025] A seventeenth aspect of the exemplary embodiment provides a program for causing a computer to execute the control method of the fifteenth or sixteenth aspect.

[0026] An eighteenth aspect of the exemplary embodiment provides a computer-readable nonvolatile storage medium storing the program of the seventeenth aspect.

[0027] According to the exemplary embodiment, it is possible to perform highly reliable eye axial length measurement regardless of the movement of the eye to be examined. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram showing an example of the structure of an ophthalmologic apparatus according to an exemplary embodiment.

[0029] Figure 2 This is a schematic diagram showing an example of the structure of an ophthalmologic apparatus according to an exemplary embodiment.

[0030] Figure 3A This is a schematic diagram showing an example of the structure of an ophthalmologic apparatus according to an exemplary embodiment.

[0031] Figure 3B This is a schematic diagram showing an example of the structure of an ophthalmologic apparatus according to an exemplary embodiment.

[0032] Figure 4A This is a schematic diagram showing an example of the structure of an ophthalmologic apparatus according to an exemplary embodiment.

[0033] Figure 4B This is a schematic diagram showing an example of the structure of an ophthalmologic apparatus according to an exemplary embodiment.

[0034] Figure 5 This is a schematic diagram showing an example of operations that can be performed by the ophthalmologic apparatus according to the exemplary embodiment.

[0035] Figure 6 This is a flowchart showing an example of operations that can be performed by the ophthalmologic apparatus according to the exemplary embodiment.

[0036] Figure 7 This is a schematic diagram showing an example of the structure of an ophthalmologic apparatus according to an exemplary embodiment.

[0037] Figure 8 This is a schematic diagram showing an example of operations that can be performed by the ophthalmologic apparatus according to the exemplary embodiment.

[0038] Fig. 9 This is a flowchart showing an example of operations that can be performed by the ophthalmologic apparatus according to the exemplary embodiment.

[0039] Fig.10 This is a flowchart showing an example of operations that can be performed by the ophthalmologic apparatus according to the exemplary embodiment.

[0040] Description of Reference Numerals

[0041] 1: ophthalmic device; 50: alignment optical system; 150: moving mechanism; 210, 210A: control unit; 300: anterior ocular camera; 410: scanning unit; 420: offset measuring unit; 430: offset calculating unit; 440, 440A: alignment control unit; 450, 450A: scanning control unit. DETAILED DESCRIPTION

[0042] The ophthalmic device of the embodiment and its control method, program and storage medium are described in detail with reference to the accompanying drawings. The ophthalmic device of the embodiment acquires data by applying optical coherence tomography (OCT) scanning to the eye to be inspected, thereby obtaining the distance between two different parts of the eye to be inspected. Typically, the ophthalmic device of the embodiment applies OCT scanning to the anterior and posterior parts of the eye to be inspected in sequence, and obtains the value of the axial length of the eye from the obtained data.

[0043] In the following exemplary disclosure, an ophthalmic device combining spectral domain OCT and a fundus camera is described, but the embodiments are not limited thereto. The type of OCT is not limited to spectral domain OCT, and may be, for example, swept source OCT.

[0044] Spectral domain OCT is a method that splits light from a low-coherence light source into measurement light and reference light, overlaps the return light of the measurement light from the object under test with the reference light to generate interference light, detects the spectral distribution of the interference light with a spectrometer, and forms an image by performing Fourier transform on the detected spectral distribution.

[0045] Swept light source OCT is a method in which light from a wavelength tunable light source is split into measurement light and reference light, the return light of the measurement light from the object being tested is superimposed on the reference light to generate interference light, the interference light is detected by a light detector such as a balanced photodiode, and the detection data collected by scanning the response wavelength and the measurement light are subjected to Fourier transform and the like to form an image.

[0046] Thus, spectral domain OCT is an OCT method that obtains spectral distribution by spatial segmentation, and swept source OCT is an OCT method that obtains spectral distribution by time segmentation. In addition, the OCT method that can be used in the embodiment is not limited to this, and an embodiment using any OCT method different from this (for example, time domain OCT) can also be used.

[0047] In this specification, unless otherwise specified, “image data” and “image” which is visualization information based thereon are not distinguished from each other. Also, unless otherwise specified, a part or tissue of an eye to be inspected and an image that visualizes the same are not distinguished from each other.

[0048] <First Embodiment>

[0049] The first embodiment performs an OCT scan of a first area of ​​the eye to be inspected (first OCT scan) after alignment of the eye to be inspected, and performs an OCT scan of a second area (second OCT scan) after alignment again, and calculates the distance between a first part included in the first area and a second part included in the second area based on first data obtained by the first OCT scan and second data obtained by the second OCT scan. Thus, both the first OCT scan and the second OCT scan can be performed in a well-aligned state, so that even if the eye to be inspected moves between the first OCT scan and the second OCT scan, the distance measurement can be performed with high reliability. An example of this embodiment is disclosed below.

[0050] <structure>

[0051] Figure 1The exemplary ophthalmic device 1 shown includes a fundus camera unit 2, an OCT unit 100, and an operation control unit 200. An optical system and a mechanism for acquiring a front image of the eye E to be inspected, and an optical system and a mechanism for performing OCT are provided in the fundus camera unit 2. An optical system and a mechanism for performing OCT are provided in the OCT unit 100. The operation control unit 200 includes one or more processors configured to perform various processes (operation, control, etc.). In addition, the ophthalmic device 1 is provided with two anterior ocular cameras 300 for photographing the anterior ocular segment from two different directions.

[0052] The fundus camera unit 2 is provided with a jaw support and a forehead pad for supporting the face of the subject. The jaw support and the forehead pad are equivalent to Figure 4A as well as Figure 4B The support part 340 shown in the figure. The driving mechanism and the operation control circuit are stored in the base 310. The optical system is stored in the housing 320 provided on the base 310. The objective lens 22 is stored in the lens storage part 330 provided protruding from the front of the housing 320.

[0053] Furthermore, the ophthalmologic apparatus 1 includes a lens unit for switching the site to which OCT is applied. Specifically, the ophthalmologic apparatus 1 includes an anterior segment OCT auxiliary lens 400 for applying OCT to the anterior segment. The anterior segment OCT auxiliary lens 400 may be configured similarly to the optical unit disclosed in Japanese Patent Application Laid-Open No. 2015-160103, for example.

[0054] like Figure 1 As shown, the auxiliary lens 400 for anterior segment OCT can be arranged between the objective lens 22 and the subject's eye E. When the auxiliary lens 400 for anterior segment OCT is arranged in the optical path, the ophthalmologic apparatus 1 can apply OCT scanning to the anterior segment. On the other hand, when the auxiliary lens 400 for anterior segment OCT is in a state of being withdrawn from the optical path, the ophthalmologic apparatus 1 can apply OCT scanning to the posterior segment. The movement of the auxiliary lens 400 for anterior segment OCT is performed manually or automatically.

[0055] In other embodiments, when the auxiliary lens is arranged in the optical path, OCT scanning can be applied to the posterior ocular part, and when the auxiliary lens is in a position to be withdrawn from the optical path, OCT scanning can be applied to the anterior ocular part. In addition, the measurement site switched by the auxiliary lens is not limited to the posterior ocular part and the anterior ocular part, but can be any part of the eye. In addition, the structure for switching the site for OCT scanning is not limited to such an auxiliary lens, and for example, a structure having a lens that can be moved along the optical path or a structure having a lens that can be inserted and removed relative to the optical path can also be adopted.

[0056] In this embodiment, the "processor" is, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), a programmable logic device (for example, SPLD (Simple Programmable Logic Device), CPLD (Complex Programmable Logic Device), FPGA (Field Programmable Gate Array)) and other circuits. The processor realizes the functions of the embodiment by, for example, reading and executing programs stored in a storage circuit or storage device.

[0057] 〈Fundus camera unit 2〉

[0058] An optical system for photographing the fundus Ef of the eye to be inspected E is provided in the fundus camera unit 2. The acquired digital image of the fundus Ef (referred to as a fundus image, fundus photograph, etc.) is generally a frontal image of an observed image, a photographed image, etc. The observed image is acquired by dynamic photographing using near-infrared light. The photographed image is a static image using a flash of a visible area.

[0059] The fundus camera unit 2 includes an illumination optical system 10 and a photographing optical system 30. The illumination optical system 10 irradiates illumination light to the eye E to be inspected. The photographing optical system 30 detects return light of the illumination light irradiated to the eye E to be inspected. The measurement light from the OCT unit 100 passes through an optical path in the fundus camera unit 2 and is guided to the eye E to be inspected. The return light of the measurement light projected to the eye E to be inspected (for example, the fundus Ef) passes through the same optical path in the fundus camera unit 2 and is guided to the OCT unit 100.

[0060] The light (observation illumination light) output from the observation light source 11 of the illumination optical system 10 is reflected by the concave mirror 12, passes through the condenser lens 13, and passes through the visible light cut filter 14 to become near infrared light. Then, the observation illumination light is temporarily condensed near the imaging light source 15, reflected by the reflector 16, and guided to the aperture reflector 21 via the relay lens system 17, the relay lens 18, the aperture 19, and the relay lens system 20. Then, the observation illumination light is reflected at the peripheral portion (surrounding area of ​​the aperture portion) of the aperture reflector 21, passes through the dichroic mirror 46, and is refracted by the objective lens 22 to illuminate the subject's eye E (fundus Ef). The return light of the observation illumination light from the subject's eye E is refracted by the objective lens 22, passes through the dichroic mirror 46, passes through the aperture portion formed in the central area of ​​the aperture reflector 21, passes through the dichroic mirror 55, passes through the imaging focusing lens 31, and is reflected by the reflector 32. Then, the return light passes through the semi-transparent mirror 33A, is reflected by the dichroic mirror 33, and is imaged on the light receiving surface of the image sensor 35 through the imaging lens 34. The image sensor 35 detects the return light at a predetermined frame rate. In addition, the focus of the photographing optical system 30 can be adjusted to coincide with the fundus Ef or its vicinity and can be adjusted to coincide with the anterior ocular segment or its vicinity.

[0061] The light (photographing illumination light) output from the photographing light source 15 passes through the same path as the observation illumination light and is irradiated toward the fundus Ef. The return light of the photographing illumination light from the subject's eye E passes through the same path as the return light of the observation illumination light and is guided to the dichroic mirror 33, passes through the dichroic mirror 33, is reflected by the reflection mirror 36, and is imaged on the light receiving surface of the image sensor 38 through the imaging lens 37.

[0062] The liquid crystal display (LCD) 39 displays a fixed sight mark (fixed sight mark image). A portion of the light beam output from the LCD 39 is reflected by the semi-transparent mirror 33A, reflected by the reflector 32, passes through the hole of the aperture reflector 21 via the photographing focusing lens 31 and the dichroic mirror 55. The light beam that has passed through the hole of the aperture reflector 21 passes through the dichroic mirror 46, is refracted by the objective lens 22, and is projected toward the fundus Ef. The fixed sight mark is typically used to guide and fix the line of sight. The direction in which the line of sight of the subject's eye E is guided (and fixed), that is, the direction in which the subject's eye E is prompted to fixate, is called the fixation position.

[0063] The fixation position can be changed by changing the display position of the fixed sight mark image on the screen of the LCD 39. Examples of the fixation position include a fixation position for acquiring an image centered on the macula, a fixation position for acquiring an image centered on the optic nerve head, a fixation position for acquiring an image centered on a position between the macula and the optic nerve head (center of the fundus), and a fixation position for acquiring an image of a portion away from the macula (peripheral portion of the fundus).

[0064] A graphical user interface (GUI) or the like for specifying at least one of the typical fixation positions may be provided. In addition, a GUI or the like for manually moving the fixation position (display position of the fixed sight mark) may be provided. In addition, a structure for automatically setting the fixation position may also be applied.

[0065] The structure for presenting a fixed sight mark capable of changing the fixation position to the subject's eye E is not limited to display devices such as LCDs. For example, an instrument (fixation matrix) in which a plurality of light-emitting parts (light-emitting diodes, etc.) are arranged in a matrix can be used instead of a display device. In this case, by selectively lighting up the plurality of light-emitting parts, the fixation position of the subject's eye E based on the fixed sight mark can be changed. As another example, a fixed sight mark capable of changing the fixation position can be generated by an instrument having one or more light-emitting parts that can be moved.

[0066] The alignment optical system 50 generates an alignment mark for aligning the optical system of the subject's eye E. The alignment light output from the light emitting diode (LED) 51 passes through the aperture 52, the aperture 53 and the relay lens 54, is reflected by the dichroic mirror 55, passes through the hole of the aperture reflector 21, passes through the dichroic mirror 46, and is projected to the subject's eye E through the objective lens 22. The return light from the subject's eye E of the alignment light passes through the same path as the return light of the observation illumination light and is guided to the image sensor 35. Manual alignment and automatic alignment can be performed based on its received light image (alignment mark image).

[0067] In addition, the alignment method applicable in the embodiment is not limited to the method using such an alignment mark, and may be any known method such as a method using an anterior ocular camera 300 (described later), a method using light cutting in a manner of projecting light onto the cornea from an oblique direction and detecting corneal reflected light in the opposite direction (described later), etc.

[0068] The focus optical system 60 generates a split mark for adjusting the focus of the subject's eye E. The focus optical system 60 moves along the optical path (illumination optical path) of the illumination optical system 10 in conjunction with the movement of the photographing focusing lens 31 along the optical path (photographing optical path) of the photographing optical system 30. The reflection rod 67 is inserted and removed relative to the illumination optical path. When the focus is adjusted, the reflection surface of the reflection rod 67 is arranged to be inclined relative to the illumination optical path. The focus light output from the LED 61 passes through the relay lens 62, is split into two light beams by the split mark plate 63, passes through the two-hole aperture 64, is reflected by the reflection mirror 65, and is temporarily imaged and reflected on the reflection surface of the reflection rod 67 by the condenser lens 66. In addition, the focus light is reflected by the aperture reflection mirror 21 via the relay lens 20, passes through the dichroic mirror 46, and is projected to the subject's eye E through the objective lens 22. The return light (fundus reflection light, etc.) of the focus light from the subject's eye E is guided to the image sensor 35 through the same path as the return light of the aiming light. Manual focus and automatic focus can be performed based on the received light image (segmentation mark image).

[0069] The power correction lens 70 and the power correction lens 71 can be selectively inserted into the shooting optical path between the aperture reflector 21 and the dichroic mirror 55. The power correction lens 70 is a positive lens (convex lens) for correcting large-degree hyperopia. The power correction lens 71 is a negative lens (concave lens) for correcting large-degree myopia.

[0070] The dichroic mirror 46 synthesizes the optical path for fundus imaging and the optical path for OCT (measurement arm). The dichroic mirror 46 reflects the wavelength band light used for OCT and transmits the light used for fundus imaging. On the measurement arm, a collimating lens unit 40, a Littrow mirror 41, a dispersion compensation member 42, an OCT focusing lens 43, an optical scanner 44, and a relay lens 45 are provided in order from the OCT unit 100 side.

[0071] The Littrow mirror 41 can be moved along the optical path of the incident measurement light LS, thereby changing the length of the measurement arm. The change in the length of the measurement arm is used, for example, for optical path length correction in response to the axial length of the eye, interference state adjustment, and the like.

[0072] The dispersion compensating member 42 plays a role in matching the dispersion characteristics of the measurement light LS and the dispersion characteristics of the reference light LR together with the dispersion compensating member 113 (described later) disposed on the reference arm.

[0073] The OCT focus lens 43 moves along the measurement arm to adjust the focus of the measurement arm. In addition, the movement of the imaging focus lens 31, the movement of the focus optical system 60, and the movement of the OCT focus lens 43 can be controlled in series.

[0074] The optical scanner 44 is substantially arranged at an optically conjugate position with the pupil of the eye E to be inspected. The optical scanner 44 deflects the measuring light LS guided by the measuring arm. The optical scanner 44 is, for example, a current scanner capable of two-dimensional scanning. Typically, the optical scanner 44 includes a one-dimensional scan (x-scan) for deflecting the measuring light in the ±x direction and a one-dimensional scan (y-scan) for deflecting the measuring light in the ±y direction. In this case, for example, any one of these one-dimensional scans is arranged at an optically conjugate position with the pupil, or a position optically conjugate with the pupil is arranged between these one-dimensional scans.

[0075] <OCT unit 100>

[0076] exist Figure 2The exemplary OCT unit 100 shown is provided with an optical system for performing spectral domain OCT. The optical system includes an interference optical system. The interference optical system divides the light from the wavelength tunable light source into measurement light and reference light, so that the return light of the measurement light projected to the eye E to be inspected and the reference light via the reference optical path overlap to generate interference light. The spectral distribution of the interference light generated by the interference optical system is detected by a spectrometer. The data (detection signal) obtained by detecting the spectral distribution of the interference light is sent to the operation control unit 200.

[0077] The light source unit 101 outputs low-coherence light L0 with a wide bandwidth. The low-coherence light L0 includes, for example, a band in the near-infrared region (about 800nm ​​to 900nm) and has a temporal coherence length of about tens of microns. In addition, the low-coherence light L0 can also be a band that cannot be recognized by the human eye, such as near-infrared light with a central wavelength of about 1040 to 1060nm. The light source unit 101 includes light output instruments such as superluminescent diodes (SLDs), LEDs, and semiconductor optical amplifiers (SOAs).

[0078] Furthermore, when swept-source OCT is employed, the light source unit includes a near-infrared wavelength tunable laser that changes the wavelength of emitted light at high speed.

[0079] The low coherence light L0 output from the light source unit 101 is guided to the polarization controller 103 by the optical fiber 102 to adjust its polarization state. The light L0 whose polarization state is adjusted is guided to the fiber coupler 105 by the optical fiber 104 to be split into the measurement light LS and the reference light LR. The optical path guiding the measurement light LS is called a sample arm, etc., and the optical path guiding the reference light LR is called a reference arm, etc.

[0080] The reference light LR generated by the fiber coupler 105 is guided by the optical fiber 110 to the collimator 111 and converted into a parallel light beam, and is guided to the Littrow reflector 114 via the optical path length correction component 112 and the dispersion compensation component 113. The optical path length correction component 112 plays a role in matching the optical path length of the reference light LR and the optical path length of the measurement light LS. The dispersion compensation component 113, together with the dispersion compensation component 42 configured on the measurement arm, plays a role in matching the dispersion characteristics between the reference light LR and the measurement light LS. The Littrow reflector 114 can move along the optical path of the reference light LR incident thereon, thereby changing the length of the reference arm. The change in the length of the reference arm is used, for example, for optical path length correction in response to the axial length of the eye, adjustment of the interference state, etc.

[0081] The reference light LR passing through the Littrow reflector 114 passes through the dispersion compensation component 113 and the optical path length correction component 112, is converted from a parallel beam into a convergent beam by the collimator 116, and is incident on the optical fiber 117. The reference light LR incident on the optical fiber 117 is guided by the polarization controller 118 and its polarization state is adjusted, passes through the optical fiber 119 and is guided to the attenuator 120 and its light amount is adjusted, and passes through the optical fiber 121 and is guided to the fiber coupler 122.

[0082] On the other hand, the measurement light LS generated by the fiber coupler 105 is guided to the collimating lens unit 40 through the optical fiber 127 and converted into a parallel beam, and is reflected by the dichroic mirror 46 via the Littrow mirror 41, the dispersion compensation member 42, the OCT focusing lens 43, the optical scanner 44, and the relay lens 45, and is refracted by the objective lens 22 to be projected toward the eye E to be inspected. The measurement light LS is scattered and reflected at various depth positions of the eye E to be inspected. The return light of the measurement light LS from the eye E to be inspected travels in the reverse direction of the measurement arm and is guided to the fiber coupler 105, and reaches the fiber coupler 122 via the optical fiber 128.

[0083] The fiber coupler 122 causes the measurement light LS incident via the optical fiber 128 and the reference light LR incident via the optical fiber 121 to overlap each other, thereby generating interference light LC.

[0084] The interference light LC generated by the fiber coupler 122 is guided to the optical splitter 130 through the optical fiber 129. The optical splitter 130 converts the incident interference light LC into a parallel beam through a collimating lens, decomposes the interference light LC converted into a parallel beam into spectral components through a diffraction grating, and projects the spectral components decomposed by the diffraction grating to the image sensor through the lens 114. The image sensor is, for example, a line sensor, and detects multiple spectral components of the interference light LC to generate an electrical signal (detection signal). The generated detection signal is transmitted to the operation control unit 200.

[0085] In addition, in the case of using swept light source OCT, the interference light generated by the overlap of the measurement light and the reference light is branched at a predetermined branching ratio (for example, 1:1) to generate a pair of interference lights, and the generated pair of interference lights is guided to the light detector. The light detector includes, for example, a balanced photodiode. The balanced photodiode includes a pair of photodetectors that detect a pair of interference lights respectively, and outputs the difference of a pair of detection signals obtained therefrom. The light detector transmits the output (detection signal such as a difference signal) to the data collection system (DAQ). The clock is supplied from the light source unit to the data collection system. The clock is generated in the light source unit in synchronization with the output timing of each wavelength scanned by the wavelength tunable light source within a predetermined wavelength range. The light source unit, for example, branches the light of each output wavelength to generate two branch lights, causes one of these branch lights to produce an optical delay and synthesizes these branch lights, detects the obtained synthesized light, and generates a clock based on its detection signal. The data collection system performs sampling of the detection signal (difference signal) input from the light detector according to the clock. The data obtained by this sampling is used for processing such as image construction.

[0086] Figure 1 as well as Figure 2 The ophthalmic apparatus 1 shown is provided with both a component for changing the measurement arm length (e.g., the Littrow reflector 41) and a component for changing the reference arm length (e.g., the Littrow reflector 114 or the reference reflector), but only one of these components may be provided. The coherence gate position is changed by changing the difference (optical path length difference) between the measurement arm length and the reference arm length, but the component for changing the optical path length difference is not limited to the components exemplified in this embodiment, and any component (optical member, mechanism, etc.) may be used.

[0087] <Calculation control unit 200>

[0088] The calculation control unit 200 controls each part of the ophthalmic device 1. In addition, the calculation control unit 200 performs various calculation processes. For example, the calculation control unit 200 performs signal processing such as Fourier transform on the spectral distribution obtained by the spectrometer 130 to form the reflection intensity status in each A line. In addition, the calculation control unit 200 forms image data by imaging the reflection intensity status of each A line. The calculation process for this is the same as that of the conventional spectral domain OCT.

[0089] The operation control unit 200 includes, for example, a processor, a RAM (Random Access Memory), a ROM (Read Only Memory), a hard disk drive, a communication interface, etc. Various computer programs are stored in a storage device such as a hard disk drive. The operation control unit 200 may also include an operating instrument, an input instrument, a display instrument, etc.

[0090] <User Interface 240>

[0091] The user interface 240 includes a display unit 241 and an operation unit 242. The display unit 241 includes a display device 3. The operation unit 242 includes various operation instruments and input instruments. The user interface 240 may also include an instrument that integrates a display function and an operation function, such as a touch screen. An embodiment that does not include at least a part of the user interface 240 may also be constructed. For example, the display instrument may also be an external device connected to the ophthalmic imaging device.

[0092] 〈Anterior ocular camera 300〉

[0093] The anterior ocular camera 300 captures the anterior ocular segment of the eye E to be examined from two or more different directions. The anterior ocular camera 300 includes an imaging device such as a CCD image sensor or a CMOS image sensor. In this embodiment, two anterior ocular cameras 300 are provided on the surface of the subject side of the fundus camera unit 2 (see FIG. Figure 4A The anterior ocular camera 300A and the anterior ocular camera 300B are shown in FIG. Figure 1 as well as Figure 4A As shown, the anterior ocular camera 300A and the anterior ocular camera 300B are arranged at a position away from the optical path passing through the objective lens 22. Hereinafter, one or both of the anterior ocular camera 300A and the anterior ocular camera 300B are sometimes collectively represented by the reference numeral 300. In addition, an anterior ocular camera that can be used instead of the anterior ocular camera 300A and the anterior ocular camera 300B is sometimes represented by the reference numeral 300.

[0094] In this embodiment, two anterior ocular cameras 300A and anterior ocular cameras 300B are provided, but the number of anterior ocular cameras 300 may be any number of two or more. Considering the calculation processing described later, it is sufficient to be able to photograph the structure of the anterior ocular segment from two different directions (however, it is not limited to this). Alternatively, a movable anterior ocular camera 300 may be provided to sequentially photograph the anterior ocular segment from two or more different positions.

[0095] In the present embodiment, the anterior segment camera 300 is provided separately from the illumination optical system 10 and the photographing optical system 30, but for example, the photographing optical system 30 may be used to photograph the anterior segment. That is, one of the two or more anterior segment cameras 300 may be the photographing optical system 30. The anterior segment camera 300 of the present embodiment may be capable of photographing the anterior segment from two (or more) different directions.

[0096] A structure for illuminating the anterior ocular segment may also be provided. The anterior ocular segment illumination component may include, for example, one or more light sources. Typically, at least one light source (eg, an infrared light source) may be provided near each of the two or more anterior ocular segment cameras 300 .

[0097] When two or more anterior ocular cameras 300 are provided, the anterior ocular segment can be photographed from two or more different directions substantially at the same time. "Substantially at the same time" means that, in addition to the case where the shooting timing of the two or more anterior ocular cameras is the same, for example, the case where the left and right shooting timings are offset and the eye movement can be ignored is also allowed. By photographing at the same time, the two or more anterior ocular cameras can obtain images of the subject's eye E in substantially the same position and orientation.

[0098] The shooting by two or more anterior ocular cameras can be either dynamic shooting or static shooting. In the case of dynamic shooting, by controlling the shooting start timing, or controlling the frame rate, the shooting timing of each frame, it is possible to achieve substantially simultaneous anterior ocular shooting as described above. On the other hand, in the case of static shooting, by controlling the shooting timing, it is possible to achieve substantially simultaneous anterior ocular shooting.

[0099] 〈Control System〉

[0100] Figure 3A as well as Figure 3B 2 shows an example of the configuration of a control system (processing system) of the ophthalmologic apparatus 1 . The control unit 210 , the image forming unit 220 , and the data processing unit 230 are provided in the calculation control unit 200 , for example.

[0101] <Control Unit 210>

[0102] The control unit 210 includes a processor, and controls each unit of the ophthalmologic apparatus 1 . The control unit 210 includes a main control unit 211 and a storage unit 212 .

[0103] <Main Control Unit 211>

[0104] The main control unit 211 includes a processor, and controls various elements of the ophthalmic apparatus 1 (including Figure 1 to Figure 3B The main control unit 211 is implemented by the cooperation of hardware including circuits and control software.

[0105] The photographic focusing lens 31 arranged in the photographic optical path and the focus optical system 60 arranged in the illumination optical path are moved integrally or in association by a photographic focusing driving unit (not shown) under the control of the main control unit 211. The Littrow reflector 41 provided in the measuring arm is moved by a Littrow reflector (RR) driving unit 41A under the control of the main control unit 211. The OCT focusing lens 43 provided in the measuring arm is moved by an OCT focusing driving unit 43A under the control of the main control unit 211. In addition, the movement of the OCT focusing lens 43 can be performed in association with the movement of the photographic focusing lens 31 and the focus optical system 60. The Littrow reflector 114 provided in the reference arm is moved by a Littrow reflector (RR) driving unit 114A under the control of the main control unit 211. The mechanisms illustrated here typically include actuators such as pulse motors that operate under the control of the main control unit 211. The optical scanner 44 provided in the measuring arm operates under the control of the main control unit 211. Furthermore, the main control unit 211 can control any element included in the ophthalmic apparatus 1, such as the polarization controller 103, the polarization controller 118, the attenuator 120, various light sources, various optical elements, various instruments, and various mechanisms. In addition, the main control unit 211 can control any peripheral instrument (device, equipment, instrument, etc.) connected to the ophthalmic apparatus 1, and any device, equipment, instrument, etc. that can be accessed through the ophthalmic apparatus 1.

[0106] The moving mechanism 150 moves the fundus camera unit 2 at least three-dimensionally, for example. In a typical example, the moving mechanism 150 includes an x ​​stage that can move in the ±x direction (left-right direction), an x ​​moving mechanism that moves the x stage, a y stage that can move in the ±y direction (up-down direction), a y moving mechanism that moves the y stage, a z stage that can move in the ±z direction (depth direction), and a z moving mechanism that moves the z stage. These moving mechanisms each include an actuator such as a pulse motor that operates under the control of the main control unit 211.

[0107] <Storage Unit 212>

[0108] The storage unit 212 stores various data. The data stored in the storage unit 212 include, for example, image data of OCT images, image data of fundus images, information of the eye to be examined, etc. The information of the eye to be examined includes information of the subject such as the patient ID and name, identification information of the left eye / right eye, electronic medical record information, etc.

[0109] <Image Forming Unit 220>

[0110] The image forming unit 220 forms OCT image data based on the data acquired by the spectrometer 130. The image forming unit 220 includes a processor. The image forming unit 220 is implemented by the cooperation of hardware including a circuit and image forming software.

[0111] The image forming unit 220 forms cross-sectional image data based on the data acquired by the spectrometer 130. This image forming process includes signal processing such as sampling (A / D conversion), noise removal (noise reduction), filtering, and fast Fourier transform (FFT) as in conventional spectral domain OCT.

[0112] The image data formed by the image forming unit 220 is a data group including a set of image data (a set of A scan image data) formed by imaging the reflection intensity conditions in a plurality of A lines (scanning lines along the z direction) arranged in the region applicable to OCT scanning.

[0113] The image data formed by the image forming unit 220 is, for example, one or more B-scan image data, or a pile of data formed by embedding a plurality of B-scan image data into a single three-dimensional coordinate system. The image forming unit 220 may also perform voxelization processing on the pile data to construct volume data (voxel data). The pile data and the volume data are typical examples of three-dimensional image data expressed by a three-dimensional coordinate system.

[0114] The image forming unit 220 can process the three-dimensional image data. For example, the image forming unit 220 can apply rendering to the three-dimensional image data to construct new image data. As rendering methods, there are volume rendering, maximum projection (MIP), minimum projection (MinIP), surface rendering, multi-planar reconstruction (MPR), etc. In addition, the image forming unit 220 can project the three-dimensional image data in the z direction (A line direction, depth direction) to construct projection data. In addition, the image forming unit 220 can project a part of the three-dimensional image data (three-dimensional local image data) in the z direction to construct a shadow image. In addition, the three-dimensional local image data is set, for example, by applying segmentation to the three-dimensional image data.

[0115] <Data Processing Unit 230>

[0116] The data processing unit 230 performs various data processing. For example, the data processing unit 230 may apply image processing and analysis processing to OCT image data, and may apply image processing and analysis processing to observation image data or captured image data. The data processing unit 230 includes, for example, at least one of a processor and a dedicated circuit board. The data processing unit 230 is implemented by the cooperation of hardware including circuits and data processing software.

[0117] Next, the following describes Figure 1 to Figure 3A An example of the functional structure of the ophthalmologic apparatus 1 is shown in FIG. Figure 3B In addition, Figure 3B The requirements shown are Figure 3A The same elements are denoted by the same reference numerals.

[0118] <Scanning Unit 410>

[0119] The scanning unit 410 applies OCT scanning to the subject's eye E to acquire data. The data acquired by the scanning unit 410 may be, for example, any one of the first data acquired by the spectrometer 130, the second data (sampling data, reflection intensity status, image data, etc.) generated from the first data by the image forming unit 220, and the data (image data, etc.) generated from the second data by the data processing unit 230, etc. Thus, the scanning unit 410 includes at least the spectrometer 130, and may also include at least a part of the image forming unit 220, and may further include at least a part of the data processing unit 230.

[0120] The scanning unit 410 includes an interference optical system including the aforementioned measurement arm that guides the measurement light LS to the eye E and the aforementioned reference arm that guides the reference light LS. As described above, the measurement arm is provided with an OCT focusing lens 43, an optical scanner 44, etc., and the reference arm is provided with a polarization controller 118, an attenuator 120, etc. The interference optical system includes a spectrometer 130.

[0121] Furthermore, the scanning unit 410 includes an arm length changing unit provided on at least one of the measuring arm and the reference arm. The arm length changing unit includes any one or both of a combination of the Littrow reflector 41 and the Littrow reflector driving unit 41A, and a combination of the Littrow reflector 114 and the Littrow reflector driving unit 114A. The arm length changing unit changes the arm length under the control of the scanning control unit 450 described later. More specifically, when the arm length changing unit includes a combination of the Littrow reflector 41 and the Littrow reflector driving unit 41A, the arm length changing unit can change the measuring arm length. In addition, when the arm length changing unit includes a combination of the Littrow reflector 114 and the Littrow reflector driving unit 114A, the arm length changing unit can change the reference arm length.

[0122] <Offset Measuring Unit 420>

[0123] The deviation measuring unit 420 measures the deviation of the subject's eye E from a preset reference position. The alignment control unit 440 described later performs alignment control based on the deviation measurement result (deviation information) obtained by the deviation measuring unit 420. The alignment control includes control of the moving mechanism 150 based on the deviation information. For example, the alignment control is a process of moving the optical system (at least the measurement arm) in a manner that eliminates the deviation obtained by the deviation measuring unit 420.

[0124] The deviation of the subject's eye E from the reference position is a relative position with respect to the reference position, and is typically a vector (direction and magnitude).

[0125] The reference position is set based on the optical system of the ophthalmic device 1, for example. Typical reference positions include reference positions in the x direction, reference positions in the y direction, and reference positions in the z direction. That is, typical reference positions are three-dimensional positions. The reference position is not limited to a three-dimensional position, and may also be a two-dimensional position or a one-dimensional position.

[0126] As described above, the deviation of the subject's eye E from the reference position is a relative position, so when the reference position is set based on the optical system of the ophthalmologic apparatus 1, the deviation of the subject's eye E from the optical system of the ophthalmologic apparatus 1 is synonymous with the deviation of the optical system from the subject's eye E. Furthermore, when the reference position is not set based on the optical system of the ophthalmologic apparatus 1, the deviation of the subject's eye E from the optical system of the ophthalmologic apparatus 1 is also synonymous with the deviation of the optical system from the subject's eye E with respect to the reference position.

[0127] The reference position in the x direction and the reference position in the y direction (xy reference position) are, for example, the position (optical axis position) of the optical axis (optical axis of the objective lens 22) of the ophthalmologic apparatus 1. In this case, the deviation measuring unit 420 can obtain the deviation of the subject's eye E from the optical axis position on the xy plane (xy coordinate system).

[0128] On the other hand, the reference position in the z direction (z reference position) is, for example, a position spaced a predetermined distance in the +z direction from the optical system (the front face of the objective lens 22) of the ophthalmic apparatus 1. In this case, the deviation measuring unit 420 can obtain the deviation of the subject's eye E from the z reference position in the z direction (z coordinate).

[0129] The predetermined distance for defining the z reference position is, for example, a preset running distance or a distance obtained by adding a predetermined value to the running distance. Examples of the predetermined value include half the value of the corneal curvature radius and the value of the distance between the cornea and the pupil.

[0130] When alignment is performed based on the corneal surface, the running distance can be used as the predetermined distance. When alignment is performed based on the bright spot formed in the anterior ocular region (Purkinje phenomenon) as a reference, the distance obtained by adding half of the value of the corneal curvature radius to the running distance can be used as the predetermined distance. When alignment is performed based on the pupil as a reference, the distance obtained by adding the value of the corneal-pupillary distance to the running distance can be used as the predetermined distance. In addition, the corneal curvature radius and the corneal-pupillary distance can be values ​​obtained by actually measuring the eye E to be examined.

[0131] As an example of the three-dimensional reference position, there is a position separated from the front surface of the objective lens 22 by the above-mentioned predetermined distance in the +z direction on the optical axis of the ophthalmologic apparatus 1 .

[0132] In order to obtain the deviation of the subject's eye E from the reference position, it is necessary to define the position of the subject's eye E. The position of the subject's eye E is defined as, for example, the position of a bright spot formed in the anterior ocular segment, the position of the pupil center (pupil centroid), or the position of the corneal apex.

[0133] When the position of the eye E to be inspected is defined as the bright spot position, the offset measuring unit 420 can, for example, determine the bright spot position from two anterior ocular images acquired by two anterior ocular cameras 300 in accordance with the processing method disclosed by the applicant in Japanese Patent Gazette No. 2017-074115 and Japanese Patent Gazette No. 2017-225638, and calculate the offset of the eye E to be inspected relative to the reference position.

[0134] When the position of the eye E to be examined is defined as the pupil center position, the offset measurement unit 420 can, for example, determine the pupil center position from two anterior ocular images acquired by two anterior ocular cameras 300 in accordance with the processing method disclosed by the applicant in Japanese Patent Gazette No. 2013-248376 and Japanese Patent Gazette No. 2017-225638, and calculate the offset of the eye E to be examined relative to the reference position.

[0135] When the position of the eye E to be inspected is defined as the corneal vertex position, the offset measurement unit 420 can, for example, determine the corneal vertex position from two anterior ocular images acquired by two anterior ocular cameras 300 in accordance with the processing method disclosed by the applicant in Japanese Patent Gazette No. 2017-225638, and calculate the offset of the eye E to be inspected relative to the reference position.

[0136] In addition, the definition of the reference position, the definition of the position of the subject's eye E, the processing method for determining the position of the subject's eye E, and the calculation method of the deviation of the subject's eye E from the reference position are not limited to the above examples, and can be arbitrary. For example, an alignment method based on the positional relationship between two bright spots or an alignment method using light sectioning can be applied.

[0137] Figure 3B The offset measuring unit 420 shown is an example that can be applied when the position of the subject's eye E is defined as a bright spot position. The offset measuring unit 420 of this example includes an alignment optical system 50, two anterior ocular cameras 300, and an offset calculating unit 430. The offset calculating unit 430 is included in the data processing unit 230 and is implemented by the cooperation of hardware including circuits and offset calculating software.

[0138] As described above, the alignment optical system 50 projects the alignment mark onto the anterior segment of the eye E. That is, the alignment optical system 50 corresponds to a projection system that projects a light beam onto the anterior segment of the eye E to be inspected.

[0139] When the light beam is projected by the alignment optical system 50, the two anterior ocular cameras 300 capture the anterior ocular segment of the subject's eye E from different directions. Thus, two anterior ocular segment images corresponding to different directions are obtained. In each of these anterior ocular segment images, an image of the light beam projected by the alignment optical system 50, that is, a bright spot used as an alignment mark, is drawn.

[0140] The deviation calculation section 430 calculates the deviation of the eye E to be inspected from a predetermined reference position based on the positions of two bright spots drawn in each of the two anterior segment images acquired by the two anterior segment cameras 300 .

[0141] Similar to the processing methods disclosed in Japanese Patent Application Laid-Open Nos. 2017-074115 and 2017-225638, the offset calculation unit 430 analyzes the two anterior segment images to detect bright spots, and determines the position of the eye E based on the two bright spots detected from the two anterior segment images.

[0142] For example, the offset calculation unit 430 can calculate the distance between the eye E to be inspected and the ophthalmologic apparatus 1 (objective lens 22) in the direction (z direction) along the optical axis of the ophthalmologic apparatus 1 based on the relative positions of the two bright spots detected from the two anterior ocular segment images. Based on this distance, the alignment control unit 440 can control the moving mechanism 150 so that the distance between the eye E to be inspected and the ophthalmologic apparatus 1 in the z direction coincides with the running distance.

[0143] Furthermore, the offset calculation unit 430 can calculate the offset between the subject's eye E and the ophthalmologic apparatus 1 in the direction (x direction, y direction) orthogonal to the z direction based on the positions of the two bright spots detected from the two anterior ocular images. Based on the offset, the alignment control unit 440 can control the moving mechanism 150 so that the optical axis of the ophthalmologic apparatus 1 and the axis of the subject's eye E coincide with each other.

[0144] Furthermore, when no bright spot can be detected from one or both of the two anterior ocular images, the method may be transferred to another alignment method (for example, alignment using the pupil center as a reference).

[0145] As described in detail below, the ophthalmic apparatus 1 performs a first OCT scan on a first area (e.g., anterior ocular area) including a first part (e.g., corneal surface) of the subject's eye E, and a second OCT scan on a second area (e.g., posterior ocular area) including a second part (e.g., retinal surface). The offset measurement unit 420 performs a first offset measurement before the first OCT scan to obtain first offset information, and performs a second offset measurement before the second OCT scan to obtain second offset information. Typically, the first offset measurement is performed immediately before the first OCT scan and the second offset measurement is performed immediately before the second OCT scan.

[0146] In addition, the execution order of the first OCT scan and the second OCT scan is arbitrary, and the second OCT scan may be executed after the first OCT scan, or the first OCT scan may be executed after the second OCT scan.

[0147] <Alignment Control Unit 440>

[0148] The alignment control unit 440 performs a first alignment control of controlling the moving mechanism 150 based on the first offset information acquired by the offset measurement unit 420 before the first OCT scan and a second alignment control of controlling the moving mechanism 150 based on the second offset information acquired by the offset measurement unit 420 before the second OCT scan.

[0149] For example, the alignment control unit 440 performs a first alignment control in a manner that eliminates the offset indicated by the first offset information and performs a second alignment control in a manner that eliminates the offset indicated by the second offset information in the same manner as the alignment method disclosed in Japanese Patent Laid-Open No. 2017-074115, Japanese Patent Laid-Open No. 2017-225638, or Japanese Patent Laid-Open No. 2013-248376.

[0150] The alignment control unit 440 is included in the control unit 210 and is implemented by cooperation between hardware including circuits and alignment control software.

[0151] <Scanning Control Unit 450>

[0152] The scanning control unit 450 performs control for the aforementioned first OCT scan and second OCT scan. That is, the scanning control unit 450 performs a first scanning control for causing the scanning unit 410 to perform a first OCT scan on a first area (e.g., anterior ocular area) including a first part (e.g., corneal surface) of the subject's eye E, and a second scanning control for causing the scanning unit 410 to perform a second OCT scan on a second area (e.g., posterior ocular area) including a second part (e.g., retinal surface).

[0153] The first scanning control and the second scanning control each include, for example, control of the arm length changing unit (one or both of the Littrow mirror driving unit 41A and the Littrow mirror driving unit 114A), control of the light source unit 101, and control of the light scanner 44. In addition, the first scanning control and the second scanning control each may also include control of the polarization controller 103, control of the polarization controller 118, control of the attenuator 120, control of the OCT focus driving unit 43A, etc. Examples of the first scanning control and the second scanning control will be described later.

[0154] The scan control unit 450 is included in the control unit 210 and is implemented by cooperation between hardware including circuits and scan control software.

[0155] <Distance calculation unit 460>

[0156] The distance calculation unit 460 calculates the distance between the first part included in the applicable range of the first OCT scan and the second part included in the applicable range of the second OCT scan based on the first data acquired by the first OCT scan and the second data acquired by the second OCT scan. That is, the distance calculation unit 460 calculates the distance between the first part and the second part of the eye E to be inspected based on the first data acquired by the scanning unit 410 under the first scanning control and the second data acquired by the scanning unit 410 under the second scanning control.

[0157] For example, when the first part is the corneal surface and the second part is the retinal surface, that is, when the first OCT scan is applied to the anterior ocular region including the corneal surface and the second OCT scan is applied to the posterior ocular region including the retinal surface, the distance calculation unit 460 can calculate the distance between the corneal surface and the retinal surface. Typically, the distance calculation unit 460 calculates the distance between the corneal vertex and the center of the macula (fovea), that is, the axial length of the eye.

[0158] For example, the distance calculation unit 460 performs distance calculation through a series of processes (first process to fourth process) shown below. Here, the execution order of the first process to the third process is arbitrary, and any two or more of them may be executed in parallel.

[0159] In the first process, the distance calculation unit 460 calculates the difference between the first arm length applicable under the first scanning control and the second arm length applicable under the second scanning control. The first arm length and the second arm length are acquired from, for example, the scanning control unit 450 that executes the first scanning control and the second scanning control. Alternatively, one or both of the first arm length and the second arm length may be detected by a member that detects the arm length, for example, a position sensor that detects the position of one or both of the Littrow reflector 41 and the Littrow reflector 114.

[0160] In the second process, the distance calculation unit 460 analyzes the first data acquired by the scanning unit 410 under the first scanning control, and determines the position (first position) in the first data corresponding to the first part of the subject's eye E. For example, when the first part is the corneal surface, the distance calculation unit 460 analyzes the first data acquired by the first OCT scanning of the anterior ocular region, and determines the first position corresponding to the corneal surface (typically, the corneal vertex) of the subject's eye E. Typically, the first position is a signal position in the reflection intensity condition generated from the detection signal acquired by the first OCT scanning, or a pixel position in the A-scan image data obtained by imaging the reflection intensity condition.

[0161] In the third process, the distance calculation unit 460 analyzes the second data acquired by the scanning unit 410 under the second scanning control, and determines the position (second position) in the second data corresponding to the second part of the subject's eye E. For example, in the case where the second part is the retinal surface, the distance calculation unit 460 analyzes the second data acquired from the second OCT scan of the posterior ocular region, and determines the second position corresponding to the retinal surface (typically, the center of the macula) of the subject's eye E. Typically, the second position is a signal position in the reflection intensity condition generated from the detection signal acquired by the second OCT scan, or a pixel position in the A-scan image data obtained by imaging the reflection intensity condition.

[0162] In the fourth process, the distance calculation unit 460 calculates the distance between the first part and the second part based on the arm length difference calculated in the first process, the first position determined in the second process, and the second position determined in the third process.

[0163] Typically, in the fourth process, the distance calculation unit 460 calculates the value of the axial length of the subject's eye E based on the arm length difference calculated in the first process, the corneal vertex position determined in the second process, and the macula center position determined in the third process. The brief description of this calculation process is as follows: Figure 5 Shown in.

[0164] The corneal vertex of the subject's eye E is denoted by reference symbol C, and the macula center is denoted by reference symbol M. Reference symbols A1 and A2 denote a first OCT scan and a second OCT scan, respectively. The first OCT scan A1 and the second OCT scan A2 in this example are each an A scan. Figure 5 This shows that the first OCT scan A1 and the second OCT scan A2 are each performed in a well-aligned state. That is, Figure 5 A case where a first OCT scan A1 is performed in such a manner as to pass through the corneal apex C and a second OCT scan A2 is performed in such a manner as to pass through the macula center M is shown.

[0165] The reflection intensity status obtained by the first OCT scan A1 is denoted by reference numeral P1, and the reflection intensity status obtained by the second OCT scan A2 is denoted by reference numeral P2. The z coordinate axis defining the first reflection intensity status P1 is denoted by "z1", and the z coordinate axis defining the second reflection intensity status P2 is denoted by "z2".

[0166] The first OCT scan A1 of the anterior ocular region is performed with a coherence gate configured at an arbitrary position in the anterior ocular region. For example, the coherence gate is configured at a position (bright spot formation position) that is half the distance from the corneal curvature radius in the +z direction from the corneal vertex C. Reference symbol z1(0) indicates the coherence gate position applied in the first OCT scan A1 of this example.

[0167] On the other hand, the second OCT scan A2 of the posterior ocular region is performed with the coherence gate configured at an arbitrary position in the posterior ocular region. For example, the coherence gate is configured at a position close to the retinal surface in the vitreous body. Reference symbol z2(0) indicates the coherence gate position applied in the second OCT scan A2 of this example.

[0168] The distance calculation unit 460 calculates the difference between the coherence gate position z1(0) applied in the first OCT scan A1 and the coherence gate position z2(0) applied in the second OCT scan A2. This difference is equivalent to Figure 5 The reference symbol Δz is shown 12 , which is equivalent to the arm length difference between the first OCT scan A1 and the second OCT scan A2. This process is an example of the first process described above.

[0169] The first reflection intensity condition P1 includes a peak corresponding to the corneal surface, a peak corresponding to the back of the cornea, a peak corresponding to the lens surface, a peak corresponding to the back of the lens, and the like. The distance calculation unit 460 determines the peak corresponding to the corneal surface from the plurality of peaks included in the first reflection intensity condition P1. The peak determination includes, for example, a process of determining a peak with the maximum intensity. Alternatively, the peak determination may also include a process of determining a peak with the smallest z1 coordinate value (a peak located on the most -z1 side) among the peaks with intensities exceeding a predetermined threshold. The z1 coordinate value of the peak corresponding to the corneal surface determined in this way is denoted by “z c " indicates that the z1 coordinate value in this example is z c Corresponds to the position of the corneal vertex C. Calculate the coordinate value z1 c This process is an example of the aforementioned second process.

[0170] The second reflection intensity status P2 includes, in addition to the peak corresponding to the retinal surface, a plurality of peaks corresponding to the inner layer of the retina, a peak corresponding to the choroid, and the like. The distance calculation unit 460 determines the peak corresponding to the retinal surface from the plurality of peaks included in the second reflection intensity status P2. The peak determination includes, for example, a process of determining a peak with the maximum intensity. Alternatively, the peak determination may also include a process of determining a peak with the smallest z2 coordinate value (a peak located on the -z2 side) among the peaks with intensities exceeding a predetermined threshold. The z2 coordinate value of the peak corresponding to the retinal surface determined in this way is denoted by “z M " indicates that the z2 coordinate value in this example is z M Corresponds to the position of the macular center M. Calculate the z2 coordinate value z M This process is an example of the aforementioned third process.

[0171] The distance calculation unit 460 calculates the arm length difference Δz in the first process. 12 , the corneal vertex position z determined in the second process c, the pupil center position z determined in the third process M , calculate the distance between the corneal vertex C and the macula center M (axial length). Figure 5 In the example shown, the axial length AL is calculated using the following formula: AL = Δz 12 +(z1(0)-z c )+(z M -z2(0)). In addition, the positive and negative of the reference numerals included on the right are determined by the setting of the coherence gate position, the setting of the first part, the setting of the second part, etc. The axial length AL is usually calculated using the following formula: AL = Δz 12 ±|z c -z1(0)|±|z M -z2(0)| This process for finding the distance equal to the axial length of the eye is an example of the fourth process.

[0172] <action>

[0173] An example of the operation of the ophthalmologic apparatus 1 according to the present embodiment will be described. Figure 6 In this operation example, a fixed sight mark for macula imaging is shown to the eye E to be inspected.

[0174] (S1: Perform alignment)

[0175] First, alignment of the ophthalmologic apparatus 1 with respect to the subject's eye E is performed.

[0176] In this example, first, the alignment control unit 440 turns on the light emitting diode 51 of the alignment optical system 50. As a result, a light beam is projected toward the anterior segment of the subject's eye E, forming a bright spot in the anterior segment. The two anterior segment cameras 300 capture the anterior segment to which the light beam is projected from different directions. As a result, a pair of anterior segment images with bright spots drawn in each are obtained.

[0177] The offset calculation unit 430 determines the bright spot position from each of the pair of anterior ocular segment images, and obtains the offset of the subject's eye E from a predetermined reference position. The alignment control unit 440 controls the moving mechanism 150 so as to cancel the offset calculated by the offset calculation unit 430 .

[0178] In this example, a series of processes including anterior ocular imaging by two anterior ocular cameras 300, offset calculation by offset calculation unit 430, and movement control by alignment control unit 440 are repeatedly performed at predetermined time intervals, so that the alignment state can be gradually improved and a good alignment state can be maintained. The latter is called tracking.

[0179] (S2: Change the arm length to get the signal from the cornea)

[0180] If a good alignment state is achieved in step S1, the scanning control unit 450 (and the data processing unit 230) changes one or both of the measurement arm length and the reference arm length to obtain a signal corresponding to the cornea of ​​the subject's eye E. The measurement arm length is changed by controlling the Littrow mirror driving unit 41A, and the reference arm length is changed by controlling the Littrow mirror driving unit 114A.

[0181] In addition, considering that the corneal position is determined according to the running distance, the Littrow mirror drive unit (either one or both of the Littrow mirror drive unit 41A and the Littrow mirror drive unit 114A) can also be controlled with a predetermined control amount to configure the Littrow reflector (either one or both of the Littrow reflector 41 and the Littrow reflector 114) at a position corresponding to the arm length (either one or both of the measurement arm length and the reference arm length) at which the following signal is detected, and the signal is a signal from the corneal position determined according to the predetermined running distance.

[0182] The processing of step S2 includes, for example, a processing called "Auto Z" disclosed by the present applicant in Japanese Patent Publication No. 2017-184874. Auto Z is an automatic process for searching for a good arm length (here, an arm length such as to obtain a signal of the cornea). In addition, the arm length adjustment of step S2 may also be performed by a process different from Auto Z. In addition to Auto Z, a process called "Z lock" disclosed in the document may also be performed. Z lock is an automatic process for maintaining the appropriate image drawing state achieved by Auto Z.

[0183] After the arm length adjustment in step S2, alignment may be performed again in the same manner as in step S1.

[0184] Here, the OCT focusing lens 43 can also be moved to focus near the cornea. For example, since the position of the cornea is determined by the running distance as described above, the position of the OCT focusing lens 43 corresponding thereto can be predetermined and moved to that position. In addition, considering that the signal intensity from the front of the cornea is strong, the OCT focusing lens 43 can also be moved to focus on the retina at the moment of acquiring the signal from the cornea. In this case, the OCT focusing lens 43 can be moved in conjunction with the movement of the focus optical system 60, or the OCT focusing lens 43 can be moved by the amount of movement determined by the focus optical system 60.

[0185] (S3: OCT scanning is applicable to the anterior eye)

[0186] When the arm length adjustment in step S2 is completed, the scan control unit 450 performs control for applying OCT scanning to the anterior segment of the eye E. In this example, the scan control unit 450 performs first scan control for causing the scanner 410 to perform OCT scanning of the anterior segment region including the corneal surface of the eye E.

[0187] The OCT scan used here is, for example, an A scan. The case where other scan modes are used will be described later.

[0188] (S4: Generate reflection intensity status)

[0189] The scanning unit 410 (image forming unit 220) generates a reflection intensity profile from the data acquired by the OCT scan in step S3. The reflection intensity profile is data corresponding to the A line to which the A scan is applied in step S3.

[0190] (S5: Record the position and reflection intensity of the Littrow reflector)

[0191] The ophthalmologic apparatus 1 (for example, the distance calculation unit 460 ) records the position of the Littrow reflector when the OCT scan in step S3 is performed and the reflection intensity status generated in step S4 .

[0192] When the measurement arm length is changed in step S2, the position of the Littrow reflector 41 is recorded, and when the reference arm length is changed in step S2, the position of the Littrow reflector 114 is recorded. Here, the position of the Littrow reflector 41 is obtained, for example, based on the control content of the Littrow reflector driver 41A or by detecting the position of the Littrow reflector 41. Similarly, the position of the Littrow reflector 114 is obtained, for example, based on the control content of the Littrow reflector driver 114A or by detecting the position of the Littrow reflector 114.

[0193] (S6: Change arm length to get retinal signal)

[0194] Next, the scan control unit 450 (and the data processing unit 230 ) changes one or both of the measurement arm length and the reference arm length so as to obtain a signal corresponding to the retina of the eye to be inspected E. This process is performed in the same manner as step S2 .

[0195] (S7: Execute alignment)

[0196] When the arm length adjustment in step S6 is completed, the ophthalmologic apparatus 1 is aligned with the subject's eye E. The alignment is performed in the same manner as in step S1.

[0197] When the OCT focusing lens 43 is moved to focus near the cornea when acquiring a signal from the cornea (described above), the OCT focusing lens 43 can be moved to focus on the retina at this stage. At this time, the OCT focusing lens 43 can be moved in conjunction with the movement of the focus optical system 60, or the OCT focusing lens 43 can be moved by the movement amount determined by the focus optical system 60.

[0198] (S8: OCT scanning is applicable to the posterior ocular region)

[0199] When the alignment in step S7 is completed, the scan control unit 450 performs control for applying OCT scanning to the posterior segment of the eye E. In this example, the scan control unit 450 performs second scan control for causing the scanner 410 to perform OCT scanning of the posterior segment region including the retinal surface of the eye E.

[0200] The OCT scan used here is, for example, an A scan. The case where other scan modes are used will be described later.

[0201] (S9: Generate reflection intensity status)

[0202] The scanning unit 410 (image forming unit 220) generates a reflection intensity profile from the data acquired by the OCT scan in step S8. The reflection intensity profile is data corresponding to the A line to which the A scan is applied in step S8.

[0203] (S10: Record the position and reflection intensity of the Littrow reflector)

[0204] The ophthalmologic apparatus 1 (for example, the distance calculation unit 460 ) records the position of the Littrow reflector when the OCT scan in step S8 is performed and the reflection intensity status generated in step S9 . This process is performed in the same manner as step S5 .

[0205] (S11: Calculate the axial length of the eye)

[0206] The distance calculation unit 460 calculates the distance between the corneal surface and the retinal surface based on the position and reflection intensity of the Littrow reflector recorded in step S5 and the position and reflection intensity of the Littrow reflector recorded in step S10 .

[0207] In this example, the distance calculation unit 460 first calculates the difference between the first arm length and the second arm length based on the position of the Littrow reflector recorded in step 5 (i.e., the first arm length applicable to the anterior segment OCT scan) and the position of the Littrow reflector recorded in step 10 (i.e., the second arm length applicable to the posterior segment OCT scan). Furthermore, the distance calculation unit 460 analyzes the reflection intensity condition recorded in step 5 to determine the position corresponding to the corneal surface (first position) and analyzes the reflection intensity condition recorded in step S10 to determine the position corresponding to the retinal surface (second position). Furthermore, the distance calculation unit 460 calculates the axial length of the subject's eye E based on the difference in arm lengths, the first position, and the second position. The above completes the actions involved in this action example (end).

[0208] <Variation of the First Embodiment>

[0209] A modification description applicable to the ophthalmologic apparatus 1 of the first embodiment will be described. In addition, unless otherwise specified, the reference numerals used in the description of the ophthalmologic apparatus 1 will be used in the following description.

[0210] <First Modification>

[0211] For example, when the subject's eye suffers from floaters, the opacities moving in the vitreous body may adversely affect the posterior ocular OCT scan.

[0212] To address this problem, multiple OCT scans may be applied to the posterior ocular region. The repeated OCT scans are performed by the scanning unit 410 under the control of the scanning control unit 450. Each OCT scan is typically an A scan, but is not limited thereto and may be any scanning mode such as a B scan or a three-dimensional scan.

[0213] An example of an applicable repetitive OCT scan (multiple OCT scans) is described. The ophthalmic device of this example first performs an A scan. When the distance measurement cannot be properly performed even after repeating the A scan a predetermined number of times (for example, 10 times), the ophthalmic device of this example switches the scanning mode from the A scan to another scanning mode. The other scanning mode is, for example, a B scan. The determination of whether the distance measurement is properly performed includes, for example, a process of comparing the intensity of the interference signal obtained by the OCT scan (the A scan at this stage) with a predetermined threshold. When the interference signal intensity is above the threshold, it is determined that the distance measurement is properly performed, and when the interference signal intensity is less than the threshold, it is determined that the distance measurement is not properly performed. The scanning line length of the B scan of this example is arbitrary, and is typically shorter than the usual B scan (for example, a length of 1 mm). When the distance measurement cannot be properly performed even after repeating the B scan a predetermined number of times (for example, 10 times), the ophthalmic device of this example switches the scanning mode from the B scan to another scanning mode. The other scanning mode is, for example, a radar scan. The determination of whether the distance measurement using the B scan is properly performed is performed in the same manner as in the case of the A scan. The size of the radar scan in this example is arbitrary, and is typically smaller than that of a normal radar scan (for example, the length of each scan line is 1 mm). By switching the scan mode, a signal corresponding to the retina can be obtained at any stage.

[0214] More generally, the ophthalmic device of this example first applies the first scanning mode. The ophthalmic device of this example determines whether the data obtained by the OCT scanning of the first scanning mode meets the predetermined conditions. When the conditions cannot be met even if the OCT scanning of the first scanning mode is repeated a predetermined number of times, the ophthalmic device of this example switches from the first scanning mode to the second scanning mode. The ophthalmic device of this example determines whether the data obtained by the OCT scanning of the second scanning mode meets the predetermined conditions. When the conditions cannot be met even if the OCT scanning of the second scanning mode is repeated a predetermined number of times, the ophthalmic device of this example switches from the second scanning mode to the third scanning mode. In this way, the ophthalmic device of this example determines whether appropriate data is obtained by the OCT scanning of the qth scanning mode by considering the predetermined conditions, and when appropriate data cannot be obtained, switches from the qth scanning mode to the (q+1)th scanning mode to perform OCT scanning (q is an integer greater than 1). Here, at least two scanning modes are pre-set, and the scanning mode transfer conditions are also pre-set. In addition, the (q+1)th scanning mode is applicable, for example, at a different position from the qth scanning mode and / or in a wider range than the qth scanning mode. By gradually switching the scanning mode, even when floaters are present in the eye to be examined, it is possible to detect a signal corresponding to the retina at any stage.

[0215] During multiple OCT scans, the orientation of the optical scanner 44 may be constant or not. In the former case, other OCT scans may not be affected by the movement of opacities in the vitreous body, or even if an OCT scan is affected by opacities, other OCT scans may not be affected by it. In the latter case, the influence of opacities in the vitreous body can be actively avoided. However, in the latter case, it is preferable to limit the range of change in the orientation of the optical scanner 44 so that the object part of the distance measurement (such as the center of the macula) does not deviate from the applicable range of the OCT scan. In particular, when A scanning is applied, it is necessary to limit the change in the orientation of the optical scanner 44 to a small range. The range of change in the orientation of the optical scanner 44 is preset, for example, in response to the applicable scanning mode.

[0216] The scanning unit 410 generates reflection intensity information or image data from the detection signals obtained through the plurality of OCT scans, thereby obtaining a data set (a plurality of data) corresponding to the plurality of OCT scans.

[0217] The distance calculation unit 460 acquires single data from a data group acquired by a plurality of OCT scans, and can perform distance calculation using the single data.

[0218] For example, the distance calculation unit 460 can generate a single data by overlapping (i.e., arithmetically averaging) at least two of the plurality of data included in the data set. By arithmetically averaging two or more data obtained by two or more OCT scans applied to the (substantially) same part of the subject's eye E, noise caused by opacities in the vitreous body and the like can be reduced or removed.

[0219] In another example, the distance calculation unit 460 can select one data from a data set acquired by multiple OCT scans. In data selection, for example, a predetermined evaluation value (e.g., contrast) obtained from the data is referenced. Thus, even if one of the multiple data included in the data set is affected by the opacity in the vitreous body, etc., data that is not affected by it or data that is less affected by it can be selected.

[0220] Furthermore, when the single data obtained by the distance calculation section 460 does not satisfy a predetermined condition (eg, a contrast condition), the ophthalmologic apparatus 1 may display a message prompting to perform the posterior segment OCT scan again or perform the posterior segment OCT scan again.

[0221] <Second Modification>

[0222] In order to correctly measure the distance between two parts of the eye E to be inspected, it is necessary to correctly determine the two parts. For this purpose, OCT scanning can be applied to the three-dimensional area of ​​the eye E to be inspected. As examples of scanning modes used therefor, there are three-dimensional scanning, radar scanning, multi-line cross scanning, etc. Here, radar scanning is a scanning mode consisting of multiple line scans (multiple B scans) arranged radially, and multi-line cross scanning is a scanning mode consisting of two line scan groups orthogonal to each other.

[0223] The scan control unit 450 controls the scanner 410 to perform OCT scanning of a three-dimensional region of the eye E to be inspected, for example, in at least one of the anterior segment OCT scan and the posterior segment OCT scan.

[0224] Typically, the scan control unit 450 can cause the scanner 410 to perform OCT scanning of a three-dimensional region including the corneal surface of the subject's eye E during anterior segment OCT scanning. OCT scanning is applied to a three-dimensional region of the anterior segment including the corneal apex of the subject's eye E in a well-aligned state.

[0225] In the posterior segment OCT scan, the scan control unit 450 causes the scanner 410 to perform OCT scanning of a three-dimensional region including the retinal surface of the subject's eye E. The OCT scan is applied to a three-dimensional region of the posterior segment including the macula center of the subject's eye E in a well-aligned state.

[0226] The distance calculation section 460 analyzes data acquired by OCT scanning of a three-dimensional region of the eye E to be inspected, and can identify a characteristic position corresponding to a characteristic point of the eye E to be inspected.

[0227] Typically, the distance calculation unit 460 analyzes data acquired by OCT scanning of the three-dimensional region of the anterior ocular segment including the corneal vertex of the subject's eye E, thereby being able to determine the characteristic position corresponding to the corneal vertex. This processing includes, for example, a process of determining an image region corresponding to the corneal surface from the data of the three-dimensional region of the anterior ocular segment, and a process of determining a characteristic position (corneal vertex position) corresponding to the corneal vertex from the shape of the image region.

[0228] In addition, the distance calculation unit 460 analyzes the data obtained by OCT scanning of the three-dimensional area of ​​the posterior ocular region including the macula center of the subject's eye E, thereby being able to determine the characteristic position corresponding to the macula center. This processing includes, for example, a process of determining an image area corresponding to the retinal surface (inner limiting membrane, etc.) from the data of the three-dimensional area of ​​the posterior ocular region, and a process of determining a characteristic position (macula center position) corresponding to the macula center from the shape of the image area, the position of a predetermined tissue, and the position of a predetermined part. As an example of the predetermined tissue, there is a retinal accessory tissue (layer tissue), and as an example of the predetermined part, there is an optic nerve head.

[0229] The distance calculation unit 460 calculates the length of a line segment having the identified characteristic position as one end. The length of the line segment is the distance to the measurement target.

[0230] When the corneal vertex position is determined from the data acquired by the anterior segment OCT scan and the macula center position is determined from the data acquired by the posterior segment OCT scan, the distance calculator 460 calculates the distance of the line segment connecting the corneal vertex position and the macula center position.

[0231] <Effect>

[0232] Effects of the ophthalmologic apparatus 1 according to the first embodiment and its modified examples will be described.

[0233] The ophthalmologic apparatus 1 includes a scanning unit 410 , a moving mechanism 150 , a deviation measuring unit 420 , a scanning control unit 450 , an alignment control unit 440 , and a distance calculating unit 460 .

[0234] The scanning unit 410 is configured to apply OCT scanning to the subject's eye E. The moving mechanism 150 is configured to move at least a part of the scanning unit. The deviation measuring unit 420 measures the deviation of the subject's eye E from a predetermined reference position.

[0235] The scanning control unit 450 performs a first scanning control to cause the scanning unit 410 to perform an OCT scan of a first area (e.g., anterior ocular area) including a first part (e.g., corneal surface) of the subject's eye E, and a second scanning control to cause the scanning unit 410 to perform an OCT scan of a second area (e.g., posterior ocular area) including a second part (e.g., retinal surface) different from the first part. The OCT scan performed under the first scanning control is referred to as a first OCT scan, and the OCT scan performed under the second scanning control is referred to as a second OCT scan.

[0236] The alignment control unit 440 performs a first alignment control for controlling the moving mechanism 150 based on first displacement information of the subject's eye E acquired by the displacement measuring unit 420 before the first scanning control, and a second alignment control for controlling the moving mechanism 150 based on second displacement information of the subject's eye E acquired by the displacement measuring unit 420 before the second scanning control. In addition, the ophthalmologic apparatus 1 can perform alignment in the xy direction and alignment in the z direction.

[0237] The distance calculator 460 calculates the distance (eg, axial length) between the first portion and the second portion based on the first data acquired by the scanner 410 under the first scanning control and the second data acquired by the scanner 410 under the second scanning control.

[0238] According to the ophthalmic apparatus 1, since alignment is performed before each of the first OCT scan and the second OCT scan, the first OCT scan and the second OCT scan can be performed in a well-aligned state. Therefore, for example, when the second OCT scan is performed after the first OCT scan, even if the eye to be inspected moves between the first OCT scan and the second OCT scan, the second OCT scan is performed after alignment of the eye to be inspected after the movement, so the reliability of the distance measurement can be ensured.

[0239] As an optional structure, the scanning unit 410 of the ophthalmic apparatus 1 includes an interference optical system including a measurement arm that guides the measurement light LS to the subject's eye E and a reference arm that guides the reference light LR. Furthermore, as an optional structure, the scanning unit 410 is provided on at least one of the measurement arm and the reference arm, and includes an arm length changing unit that changes the arm length under the control of the scanning control unit 450. The Littrow reflector 41 and the Littrow reflector driving unit 41A are examples of an arm length changing unit provided on the measurement arm. The Littrow reflector 114 and the Littrow reflector driving unit 114A are examples of an arm length changing unit provided on the reference arm.

[0240] In addition to the above, as an arbitrary structure, the distance calculation unit 460 is capable of performing the following series of processing: (1) a process of calculating the difference (arm length difference) between the first arm length applicable under the first scanning control (first OCT scan) and the second arm length applicable under the second scanning control (second OCT scan); (2) a process of analyzing the first data obtained by the first OCT scan to determine the first position corresponding to the first part of the eye E to be inspected (for example, the signal position corresponding to the corneal surface); (3) a process of analyzing the second data obtained by the second OCT scan to determine the second position corresponding to the second part of the eye E to be inspected (for example, the signal position corresponding to the retinal surface); (4) a process of calculating the distance between the first part and the second part (for example, the axial length of the eye) based on the arm length difference calculated in (1), the first position determined in (2), and the second position determined in (3).

[0241] According to this optional configuration, specific processing for calculating the distance between the first part and the second part of the eye E to be inspected can be provided.

[0242] As an arbitrary structure, the scanning control unit 450 can make the scanning unit 410 perform multiple OCT scans under at least one of the first scanning control (first OCT scan) and the second scanning control (second OCT scan). In this case, the distance calculation unit 460 can obtain single data from the data group obtained by the multiple OCT scans. Here, the distance calculation unit 460 performs arithmetic averaging on the data group obtained by the multiple OCT scans, thereby generating single data. Moreover, the distance calculation unit 460 can calculate the distance between the first part and the second part using the obtained single data.

[0243] According to this arbitrary structure, even if the opacities moving in the vitreous body have an adverse effect on the posterior ocular OCT scan, the reliability of distance measurement can be improved because the noise caused by the opacities can be reduced and removed, and data that is not affected by the opacities or data that is less affected by them can be selected.

[0244] As an arbitrary structure, the scanning control unit 450 can make the scanning unit 410 perform OCT scanning of the three-dimensional area of ​​the subject's eye E under at least one of the first scanning control (first OCT scanning) and the second scanning control (second OCT scanning). In this case, the distance calculation unit 460 can determine the characteristic position corresponding to the characteristic point of the subject's eye E by analyzing the data obtained by the OCT scanning of the three-dimensional area. In addition, the distance calculation unit 460 can calculate the distance between the first part and the second part with the length of the line segment with the characteristic position as one end.

[0245] As a first typical example, the scanning control unit 450 can cause the scanning unit 410 to perform an OCT scan of a three-dimensional region including the corneal surface of the subject's eye E under the first scanning control (first OCT scan). Furthermore, the distance calculation unit 460 can determine a characteristic position corresponding to the corneal vertex of the subject's eye E by analyzing data acquired through the OCT scan of the three-dimensional region. In this case, the distance calculation unit 460 can calculate the distance between the first part and the second part as the length of a line segment having the corneal vertex as one end.

[0246] As a second typical example, the scanning control unit 450 can cause the scanning unit to perform an OCT scan of a three-dimensional area including the retinal surface of the subject's eye E under the second scanning control (second OCT scan). Furthermore, the distance calculation unit 460 can determine a characteristic position corresponding to the macula center of the subject's eye E by analyzing data acquired through the OCT scan of the three-dimensional area. In this case, the distance calculation unit 460 can calculate the distance between the first portion and the second portion as the length of a line segment having the macula center as one end.

[0247] By combining the first typical example and the second typical example, the length of the line segment having the corneal apex as one end and the macula center as the other end, that is, the axial length of the eye E to be examined can be obtained.

[0248] As an arbitrary structure, the displacement measuring unit 420 includes an alignment optical system 50 (projection system), two (or more) anterior segment cameras 300 (or more imaging units), and a displacement calculating unit 430. The alignment optical system 50 projects a light beam to the anterior segment of the subject's eye E. The two (or more) anterior segment cameras 300 capture the anterior segment of the subject's eye E from different directions. The displacement calculating unit 430 calculates the displacement of the subject's eye E from a predetermined reference position based on the positions of the light beam images (bright spots) respectively drawn in the two (or more) anterior segment images acquired by the two (or more) anterior segment cameras 300.

[0249] According to this optional configuration, a specific configuration and process for measuring the deviation of the subject's eye E from a predetermined reference position can be provided.

[0250] In addition, any matters (structure, elements, processing, operation, action, function, etc.) described in the first embodiment and any known matters can be combined with the ophthalmic device described in the effect column.

[0251] The first embodiment provides a control method of an ophthalmologic apparatus including a scanning unit 410 for applying OCT scanning to a subject's eye E, a moving mechanism 150 for moving at least a part of the scanning unit 410 , and a deviation measuring unit 420 for measuring deviation of the subject's eye E from a predetermined reference position.

[0252] The control method includes a first alignment control step, a first scanning control step, a second alignment control step, a second scanning control step, and a distance calculation step.

[0253] The first alignment control step controls the moving mechanism 150 based on the first deviation information of the eye E acquired by the deviation measuring unit 420. The first scanning control step causes the scanning unit 410 to perform an OCT scan of a first region including a first part of the eye E. This OCT scan is referred to as a first OCT scan.

[0254] The second alignment control step controls the moving mechanism 150 based on the second deviation information of the eye E acquired by the deviation measuring unit 420. The second scanning control step causes the scanning unit 410 to perform OCT scanning of a second region including a second portion different from the first portion of the eye E. This OCT scanning is referred to as a second OCT scanning.

[0255] The distance calculation step calculates the distance between the first portion and the second portion based on the first data acquired by the scanning unit 410 in the first scanning control step and the second data acquired by the scanning unit 410 in the second scanning control step.

[0256] According to this method of controlling an ophthalmologic apparatus, since alignment is performed before each of the first OCT scan and the second OCT scan, both the first OCT scan and the second OCT scan can be performed in a well-aligned state, thereby ensuring the reliability of distance measurement.

[0257] Furthermore, any matters (structure, elements, processing, operation, action, function, etc.) described in the first embodiment and any known matters can be combined with this control method.

[0258] A program that causes a computer to execute such a control method may be configured. For example, the program may include any of the above-mentioned programs for operating the ophthalmologic apparatus 1 of the first embodiment or its modified example.

[0259] In addition, a computer-readable nonvolatile storage medium storing such a program may be provided. The nonvolatile storage medium may be in any form, and examples thereof include a magnetic disk, an optical disk, a magneto-optical disk, and a semiconductor memory.

[0260] <Second Embodiment>

[0261] As described above, the first embodiment improves the reliability of distance measurement of the subject's eye by performing alignment before each of the first OCT scan and the second OCT scan. In other words, the first embodiment improves the reliability of distance measurement by improving the reliability of the first OCT scan and the second OCT scan.

[0262] In contrast, the second embodiment improves the reliability of distance measurement by correcting the alignment error existing in OCT scanning during data processing.

[0263] In the following, unless otherwise specifically mentioned, the description of the same matters as those in the first embodiment is omitted. In addition, the same reference numerals as those of the corresponding components in the first embodiment are given to the same components included in the second embodiment. In addition, in the following description, reference is made to the components of the first embodiment as needed.

[0264] <structure>

[0265] An example of the structure of the ophthalmic device of this embodiment is Figure 7 The ophthalmologic apparatus 1A has the same hardware configuration as the ophthalmologic apparatus 1 of the first embodiment (see Figure 1 , Figure 2 , Figure 3A , Figure 4A as well as Figure 4B ). Instead of the first embodiment Figure 3B The structure shown is applicable Figure 7 The structure shown.

[0266] In the ophthalmologic apparatus 1A, the scanning unit 410 , the displacement measuring unit 420 , and the moving mechanism 150 respectively have the same configuration, function, and action as those of the first embodiment.

[0267] The scanning unit 410 acquires data by applying OCT scanning to the eye E. As in the first embodiment, the scanning unit 410 includes an interference optical system including a measurement arm that guides measurement light LS to the eye E and a reference arm that guides reference light LS. Furthermore, as in the first embodiment, the scanning unit 410 includes an arm length changing unit provided on at least one of the measurement arm and the reference arm.

[0268] The deviation measuring unit 420 measures the deviation of the subject's eye E from a preset reference position. Similar to the first embodiment, the deviation measuring unit 420 may include an alignment optical system 50 , an anterior ocular segment camera 300 , and a deviation calculating unit 430 . Figure 7 The displacement measuring unit 420 shown is an example applicable to the case where the position of the subject's eye E is defined as a bright spot position. When other definitions (for example, pupil center position, corneal vertex position, etc.) are used, a configuration corresponding thereto is applied.

[0269] The alignment control section 440A described later can perform alignment control based on the deviation measurement result (deviation information) acquired by the deviation measurement section 420. In addition, the distance calculation section 460A described later can calculate a predetermined distance in the eye E in consideration of the deviation information acquired by the deviation measurement section 420.

[0270] As described in detail below, the ophthalmologic apparatus 1A performs a first OCT scan of a first region (e.g., anterior ocular region) including a first portion (e.g., corneal surface) of the subject's eye E, and a second OCT scan of a second region (e.g., posterior ocular region) including a second portion (e.g., retinal surface) of the subject's eye E. The order in which the first OCT scan and the second OCT scan are performed is arbitrary.

[0271] The shift measurement unit 420 can perform a first shift measurement corresponding to the first OCT scan to obtain first shift information, and can perform a second shift measurement corresponding to the second OCT scan to obtain second shift information.

[0272] The first offset measurement is performed at any time before, during, or after the first OCT scan is performed. Similarly, the second offset measurement is performed at any time before, during, or after the second OCT scan is performed. Typically, the first offset measurement is performed at any time immediately before, during, or after the first OCT scan is performed, and the second offset measurement is performed at any time immediately before, during, or after the second OCT scan is performed.

[0273] The distance calculation unit 460A described later can calculate the predetermined distance in the eye E to be inspected by taking into account either or both of the first offset information and the second offset information acquired by the offset measurement unit 420. In addition, the alignment control unit 440A described later can perform alignment control based on either the first offset information or the second offset information acquired by the offset measurement unit 420. In addition, the configuration in which alignment control is performed based on the first offset information (first alignment control) and alignment control is performed based on the second offset information (second alignment control) is equivalent to the first embodiment.

[0274] The moving mechanism 150 can move the scanning unit 410 (especially, the measuring arm of the interference optical system) relative to the eye E to be inspected, similarly to the first embodiment.

[0275] The alignment control unit 440A and the scanning control unit 450A are provided in the control unit 210A. The control unit 210A is provided instead of the control unit 210 of the first embodiment. The control unit 210A includes a processor and controls each part of the ophthalmic apparatus 1A. The control unit 210A includes a main control unit and a storage unit (not shown). The control unit 210A is implemented by the cooperation of hardware including circuits and control software.

[0276] Similar to the first embodiment, the alignment control unit 440A performs alignment control for controlling the moving mechanism 150 based on the offset information acquired by the offset measurement unit 420 .

[0277] The scanning control unit 450A performs a first scanning control to cause the scanning unit 410 to perform an OCT scan of a first area (e.g., anterior ocular area) including a first part (e.g., corneal surface) of the subject's eye E, and a second scanning control to cause the scanning unit 410 to perform an OCT scan of a second area (e.g., posterior ocular area) including a second part (e.g., retinal surface) different from the first part. The first scanning control and the second scanning control are performed in the same manner as the scanning control unit 450 of the first embodiment. The OCT scan performed by the first scanning control is referred to as a first OCT scan, and the OCT scan performed by the second scanning control is referred to as a second OCT scan.

[0278] As described above, the deviation measuring unit 420 measures the deviation of the eye E to obtain first deviation information before, during or after the first scanning control is executed, and measures the deviation of the eye E to obtain second deviation information before, during or after the second scanning control is executed.

[0279] The distance calculation unit 460A calculates the distance (e.g., axial length) between a first part (e.g., corneal surface) and a second part (e.g., retinal surface) of the eye E to be inspected based on either or both of the first offset information and the second offset information, the first data obtained by the first OCT scan, and the second data obtained by the second OCT scan.

[0280] In other words, the distance calculation unit 460A performs distance calculation in consideration of one or both of the alignment error during the first OCT scan (first offset information) and the alignment error during the second OCT scan (second offset information).

[0281] The distance calculation unit 460A performs, for example, the following series of processes. First, the distance calculation unit 460A calculates the difference (arm length difference) between the first arm length applied in the first OCT scan and the second arm length applied in the second OCT scan. Second, the distance calculation unit 460A analyzes the first data acquired through the first OCT scan to determine the first position corresponding to the first part of the eye E to be inspected (for example, the signal position on the corneal surface). Third, the distance calculation unit 460A analyzes the second data acquired through the second OCT scan to determine the second position corresponding to the second part of the eye E to be inspected (for example, the signal position on the retinal surface). The first to third processes are respectively performed in the same manner as the first embodiment. Fourth, the distance calculation unit 460A calculates the distance between the first part and the second part based on the arm length difference calculated in the first process, the first position determined in the second process, the second position determined in the third process, and the offset information (at least one of the first offset information and the second offset information) acquired by the offset measurement unit 420.

[0282] Reference Figure 8An example of such arithmetic processing will be described below. Figure 5 Similarly, reference symbol C denotes the corneal vertex of the subject's eye E, and reference symbol M denotes the macula center. A straight line Ax passing through the corneal vertex C and the macula center M denotes the ocular axis of the subject's eye E.

[0283] Reference symbol K represents the center of curvature of the corneal surface at the corneal apex C. The center of curvature K is the center of the circle of curvature (contact circle) at the corneal apex C. The radius of the circle of curvature, that is, the radius of curvature of the corneal surface at the corneal apex C is r.

[0284] Reference symbol G denotes a path (incident path) of the measurement light LS projected toward the macula center M. Reference symbol H denotes an intersection of the incident path G and the corneal surface of the eye E to be inspected, that is, an incident position of the measurement light LS on the eye E to be inspected.

[0285] The deviation (height) of the incident path G from the eye axis Ax is taken as h. If it is assumed that the shape of the corneal surface is substantially spherical, or if it is assumed that the height h is sufficiently small (that is, if it is assumed that the alignment error is sufficiently small), it can be considered that the distance between the incident position H and the center of curvature K is equal to the radius of curvature r in the corneal vertex C.

[0286] The angle formed by the line segment connecting the incident position H and the curvature center K with respect to the eye axis Ax is θ. Also, the angle formed by the line segment connecting the incident position H and the macula center M with respect to the eye axis Ax is φ.

[0287] The length of the line segment connecting the incident position H and the macular center M is ALm. This length ALm corresponds to the measured value of the axial length of the subject's eye E obtained from data acquired by OCT scanning using the measurement light LS projected to the macular center M through the incident path G.

[0288] The axial length (true value) of the eye E to be inspected is set to AL. In addition, the distance between the corneal vertex C and the incident position H in the direction of the eye axis Ax, that is, the size of the eye axis (Ax) direction component of the vector with the corneal vertex C as the starting point and the incident position H as the end point is set to AL1. In addition, the distance between the incident position H and the macula center M in the direction of the eye axis Ax, that is, the size of the eye axis (Ax) direction component of the vector with the macula center M as the starting point and the incident position H as the end point is set to AL2.

[0289] from Figure 8 It can be seen that the axial length AL is expressed by the following formula: AL=AL1+AL2=(rr×cosθ)+ALm×cosφ=(rr×cos(arcsin(h / r)))+ALm×cos(arcsin(h / ALm)).

[0290] Here, the corneal curvature radius r is obtained in advance by a corneal shape measuring device such as a keratometer. In addition, the height h is the alignment error in the xy direction measured by the offset measuring unit 420, and is included in the offset information. In addition, the axial length measurement value ALm is a value of the axial length obtained by the ophthalmologic apparatus 1A in the same manner as in the first embodiment. The axial length AL is obtained by substituting these values ​​r, h, and ALm into the above formula.

[0291] The distance calculation unit 460A stores in advance, for example, the above formula and the value (r) of the corneal curvature radius of the subject's eye E. The distance calculation unit 460A calculates the value (AL) of the axial length of the subject's eye E by substituting the value (r) of the corneal curvature radius, the offset (h) in the xy direction included in the offset information acquired by the offset measurement unit 420, and the value (ALm) of the axial length measured by OCT scanning into the above formula.

[0292] In addition, this example illustrates the case where there is an alignment error in the xy direction during posterior ocular OCT scanning, but it is obvious to those skilled in the art that the same operation is performed when there is an alignment error in the xy direction during anterior ocular OCT scanning, and when there is an alignment error in both anterior ocular OCT scanning and posterior ocular OCT scanning.

[0293] In this example, only the refraction of the measurement light LS on the corneal surface is considered, but other refractive index boundaries may be considered, for example, the refraction of the measurement light LS on the corneal back surface, the lens surface, the lens back surface, etc. may be considered.

[0294] In addition to the alignment error in the xy direction, the alignment error in the z direction may also be considered. As in the first embodiment, the alignment error in the z direction is obtained by the offset measurement unit 420 .

[0295] <action>

[0296] Hereinafter, a first operation example of calculating the distance in consideration of both the first offset information and the second offset information and a second operation example of calculating the distance in consideration of the second offset information while using the first offset information for alignment will be described.

[0297] 〈First Action Example〉

[0298] The first operation example of the ophthalmologic apparatus 1A is Fig. 9 In this operation example, for example, a fixed sight mark for macula imaging is presented to the subject's eye E. In addition, preliminary alignment may be performed before step S21.

[0299] (S21: Change the arm length to get the signal from the cornea)

[0300] In the same manner as step S2 in the first embodiment, the scan control unit 450A (and the data processing unit 230 ) changes one or both of the measurement arm length and the reference arm length so as to obtain a signal corresponding to the cornea of ​​the eye E to be inspected.

[0301] (S22: Obtaining first offset information)

[0302] When the arm length change in step S21 is completed, the offset measurement unit 420 performs the first offset measurement corresponding to the first OCT scan (anterior ocular segment OCT scan) to acquire the first offset information.

[0303] (S23: OCT scan applied to the anterior eye)

[0304] When the acquisition of the offset information in step S22 is completed, the scanning control unit 450A performs control for applying the OCT scan to the anterior segment of the subject's eye E. In this example, the scanning control unit 450A performs a first scanning control for causing the scanning unit 410 to perform the OCT scan of the anterior segment region including the corneal surface of the subject's eye E. Step S23 is performed in the same manner as step S3 in the first embodiment.

[0305] (S24: Generate reflection intensity status)

[0306] The scanning unit 410 (image forming unit 220) generates a reflection intensity profile from the data acquired by the OCT scan in step S23. The reflection intensity profile is, for example, data corresponding to the A line to which the A scan is applied in step S23.

[0307] (S25: Recording the position, reflection intensity and first offset information of the Littrow reflector)

[0308] The ophthalmologic apparatus 1 (e.g., the distance calculation unit 460A) records the position of the Littrow reflector when performing the OCT scan in step S23 and the reflection intensity status generated in step S24 in the same manner as step S5 in the first embodiment. Furthermore, the ophthalmologic apparatus 1 (e.g., the distance calculation unit 460A) records the first offset information acquired in step S22.

[0309] (S26: Change arm length to get retinal signals)

[0310] Next, the scan control unit 450A (and the data processing unit 230 ) changes one or both of the measurement arm length and the reference arm length so as to obtain a signal corresponding to the retina of the eye E to be inspected.

[0311] (S27: Obtaining Second Offset Information)

[0312] When the arm length adjustment of step S26 is completed, the offset measuring unit 420 performs a second offset measurement corresponding to the second OCT scan (posterior segment OCT scan) to acquire second offset information. This process is performed in the same manner as step S22.

[0313] (S28: OCT scanning is applicable to the posterior ocular region)

[0314] When the acquisition of the offset information in step S27 is completed, the scan control unit 450A executes control for applying OCT scanning to the posterior segment of the eye E. In this example, the scan control unit 450A executes second scan control for causing the scanner 410 to execute OCT scanning of the posterior segment region including the retinal surface of the eye E.

[0315] (S29: Generate reflection intensity status)

[0316] The scanning unit 410 (image forming unit 220) generates a reflection intensity profile from the data acquired by the OCT scan in step S28. The reflection intensity profile is, for example, data corresponding to the A line to which the A scan is applied in step S28.

[0317] (S30: Recording the position, reflection intensity and second offset information of the Littrow reflector)

[0318] The ophthalmologic apparatus 1 (eg, the distance calculation unit 460A) records the position of the Littrow reflector when performing the OCT scan in step S28 , the reflection intensity status generated in step S29 , and the second offset information acquired in step S27 in the same manner as in step S25 .

[0319] (S31: Calculate the axial length of the eye)

[0320] The distance calculation unit 460A calculates the distance between the corneal surface and the retinal surface based on the position, reflection intensity and first offset information of the Littrow reflector recorded in step S25 and the position, reflection intensity and second offset information of the Littrow reflector recorded in step S30.

[0321] In this example, the distance calculation unit 460A first calculates the difference between the first arm length and the second arm length (arm length difference) based on the position of the Littrow reflector recorded in step 25 (i.e., the first arm length applicable to anterior ocular OCT scanning) and the position of the Littrow reflector recorded in step 30 (i.e., the second arm length applicable to posterior ocular OCT scanning). Furthermore, the distance calculation unit 460A analyzes the reflection intensity condition recorded in step 25 to determine the position corresponding to the corneal surface (first position), and analyzes the reflection intensity condition recorded in step S30 to determine the position corresponding to the retinal surface (second position). Furthermore, in addition to the arm length difference, the first position, and the second position, the distance calculation unit 460A calculates the axial length of the eye E to be inspected based on the first offset information recorded in step S25 and the second offset information recorded in step S30. This calculation is performed, for example, according to Figure 8 The method described together is executed. In this example, both alignment errors in the anterior segment OCT scan and alignment errors in the posterior segment OCT scan are considered. The above completes the operation of this operation example (end).

[0322] 〈Second Action Example〉

[0323] The second operation example of the ophthalmologic apparatus 1A is Fig.10 In this operation example, for example, a fixed sight mark for macula imaging is presented to the subject's eye E. In addition, a preliminary alignment may be performed before step S41.

[0324] (S41: Change the arm length to obtain the signal of the cornea)

[0325] The scan control unit 450A (and the data processing unit 230 ) changes one or both of the measurement arm length and the reference arm length so as to obtain a signal corresponding to the cornea of ​​the eye E to be inspected.

[0326] (S42: Acquiring first offset information and performing alignment)

[0327] When the arm length change in step S41 is completed, the offset measurement unit 420 performs a first offset measurement corresponding to the first OCT scan (anterior ocular segment OCT scan) to obtain first offset information. The alignment control unit 440A performs alignment control to control the moving mechanism 150 based on the obtained first offset information. The alignment control is performed in the same manner as in the first embodiment.

[0328] (S43: OCT scan applied to the anterior eye)

[0329] When the alignment of step S42 is completed, the scan control unit 450A performs control for applying OCT scanning to the anterior segment of the subject's eye E. In this example, the scan control unit 450A performs a first scan control for causing the scanner 410 to perform OCT scanning of the anterior segment region including the corneal surface of the subject's eye E. This anterior segment OCT scanning can be assumed to be performed in a well-aligned state.

[0330] (S44: Generate reflection intensity status)

[0331] The scanning unit 410 (image forming unit 220) generates a reflection intensity profile from the data acquired by the OCT scan in step S43. The reflection intensity profile is, for example, data corresponding to the A line to which the A scan is applied in step S43.

[0332] (S45: Record the position and reflection intensity of the Littrow reflector)

[0333] The ophthalmologic apparatus 1 (for example, the distance calculation unit 460A) records the position of the Littrow reflector when the OCT scan in step S43 is performed and the reflection intensity status generated in step S44 .

[0334] (S46: Change arm length to get retinal signal)

[0335] Next, the scan control unit 450A (and the data processing unit 230 ) changes one or both of the measurement arm length and the reference arm length so as to obtain a signal corresponding to the retina of the eye E to be inspected.

[0336] (S47: Obtaining Second Offset Information)

[0337] When the arm length adjustment of step S46 is completed, the offset measuring unit 420 performs a second offset measurement corresponding to the second OCT scan (posterior segment OCT scan) to obtain second offset information. Unlike the anterior segment OCT scan, which is assumed to be performed in a good alignment state, a good alignment state cannot be ensured in the posterior segment alignment, so only the second offset information is considered in the distance calculation (step S51 described later).

[0338] (S48: OCT scanning is applied to the posterior ocular region)

[0339] When the acquisition of the offset information in step S47 is completed, the scan control unit 450A executes control for applying OCT scanning to the posterior segment of the eye E. In this example, the scan control unit 450A executes second scan control for causing the scanner 410 to execute OCT scanning of the posterior segment region including the retinal surface of the eye E.

[0340] (S49: Generate reflection intensity status)

[0341] The scanning unit 410 (image forming unit 220) generates a reflection intensity profile from the data acquired by the OCT scan in step S48. The reflection intensity profile is, for example, data corresponding to the A line to which the A scan is applied in step S48.

[0342] (S50: Recording the position, reflection intensity and second offset information of the Littrow reflector)

[0343] The ophthalmologic apparatus 1 (eg, the distance calculation unit 460A) records the position of the Littrow reflector when the OCT scan in step S48 is performed, the reflection intensity status generated in step S49 , and the second offset information acquired in step S47 .

[0344] (S51: Calculate the axial length of the eye)

[0345] The distance calculation unit 460A calculates the distance between the corneal surface and the retinal surface based on the position and reflection intensity of the Littrow reflector recorded in step S45 and the position, reflection intensity and second offset information of the Littrow reflector recorded in step S50.

[0346] In this example, the distance calculation unit 460A first calculates the difference between the first arm length and the second arm length (arm length difference) based on the position of the Littrow reflector recorded in step 45 (i.e., the first arm length applicable to anterior ocular OCT scanning) and the position of the Littrow reflector recorded in step 50 (i.e., the second arm length applicable to posterior ocular OCT scanning). Furthermore, the distance calculation unit 460A analyzes the reflection intensity condition recorded in step 45 to determine the position corresponding to the corneal surface (first position), and analyzes the reflection intensity condition recorded in step S50 to determine the position corresponding to the retinal surface (second position). Furthermore, in addition to the arm length difference, the first position, and the second position, the distance calculation unit 460A calculates the axial length of the eye E to be examined based on the second offset information recorded in step S50. This calculation is performed, for example, according to Figure 8 The method described together is executed. The above completes the operation of this operation example (end).

[0347] <Variation of the Second Embodiment>

[0348] A modification applicable to the ophthalmologic apparatus 1A of the second embodiment will be described. In addition, unless otherwise specified, the reference numerals used in the description of the ophthalmologic apparatus 1 and / or the ophthalmologic apparatus 1A will be used in the following description.

[0349] <First Modification>

[0350] Similar to the first modification of the first embodiment, in order to deal with the adverse effects of the opacities moving in the vitreous body on the posterior segment OCT scanning, the posterior segment may be subjected to OCT scanning multiple times. The repeated OCT scanning is performed by the scanning unit 410 under the control of the scanning control unit 450A.

[0351] The scanning unit 410 generates reflection intensity status or image data from the detection signals respectively obtained by the multiple OCT scans. Thus, a data group (multiple data) corresponding to the multiple OCT scans is obtained. The distance calculation unit 460A obtains a single data from the data group obtained by the multiple OCT scans, and can use the single data to perform distance calculation.

[0352] <Second Modification>

[0353] Similar to the second modification of the first embodiment, in order to accurately identify two parts of the subject's eye E, OCT scanning may be applied to the three-dimensional region of the subject's eye E. The scanning control unit 450A causes the scanning unit 410 to perform OCT scanning of the three-dimensional region of the subject's eye E, for example, in at least one of the anterior segment OCT scanning and the posterior segment OCT scanning.

[0354] The distance calculator 460A analyzes data acquired by OCT scanning of a three-dimensional region of the eye E to identify a characteristic position corresponding to a characteristic point of the eye E and calculates the length of a line segment having the identified characteristic position as one end. The line segment length is the distance to be measured.

[0355] <Effect>

[0356] Effects of the ophthalmologic apparatus 1A according to the second embodiment and its modified examples will be described.

[0357] The ophthalmologic apparatus 1A includes a scanning unit 410 , a displacement measuring unit 420 , a scanning control unit 450A, and a distance calculating unit 460A.

[0358] The scanning unit 410 applies OCT scanning to the subject's eye E. The deviation measuring unit 420 measures the deviation of the subject's eye E from a predetermined reference position.

[0359] The scanning control unit 450A executes a first scanning control to cause the scanning unit 410 to perform an OCT scan of a first area (e.g., anterior ocular area) including a first part (e.g., a corneal surface) of the subject's eye E, and a second scanning control to cause the scanning unit 410 to perform an OCT scan of a second area (e.g., posterior ocular area) including a second part (e.g., a retinal surface) different from the first part.

[0360] The distance calculation unit 460A calculates the distance (for example, the axial length of the eye) between a first part and a second part of the eye E to be inspected based on at least one of the first offset information of the eye E to be inspected obtained by the offset measurement unit 420 corresponding to the first scanning control and the second offset information of the eye E to be inspected obtained by the offset measurement unit 420 corresponding to the second scanning control, the first data obtained by the scanning unit 410 under the first scanning control, and the second data obtained by the scanning unit 410 under the second scanning control.

[0361] According to the ophthalmologic apparatus 1A, the alignment error (offset information) in one or both of the first OCT scan and the second OCT scan is acquired, and the distance calculation can be performed in consideration of the alignment error. Therefore, for example, when the second OCT scan is performed after the first OCT scan, even if the eye to be inspected moves between the first OCT scan and the second OCT scan, the reliability of the distance measurement can be ensured.

[0362] As an arbitrary structure, the offset measuring unit 420 may obtain offset information corresponding to the scanning control of one of the first scanning control and the second scanning control, and obtain the other offset information before the other scanning control. In addition, the ophthalmologic apparatus 1A may include a moving mechanism 150 and an alignment control unit 440A. The moving mechanism 150 moves at least a part of the scanning unit 410. The alignment control unit 440A performs alignment control of the moving mechanism 150 based on the other offset information before the other scanning control. The distance calculating unit 460A can perform distance calculation based on the offset information, the first data, and the second data.

[0363] For example, in Fig.10 In the second operation example shown, the deviation measuring unit 420 acquires first deviation information before the first scanning control to perform alignment, and calculates the distance based on the second deviation information acquired corresponding to the second scanning control, the first data, and the second data.

[0364] According to this optional configuration, one of the first OCT scan and the second OCT scan can be performed after alignment, while the distance calculation can be performed in consideration of the alignment error in the other, and the distance measurement can be performed with high reliability.

[0365] As an optional structure, the scanning unit 410 may include an interference optical system and an arm length changing unit. The interference optical system includes a measurement arm that guides the measurement light LS to the eye E to be examined and a reference arm that guides the reference light LR. The arm length changing unit is provided on at least one of the measurement arm and the reference arm, and changes the arm length under the control of the scanning control unit 450A. The Littrow reflector 41 and the Littrow reflector drive unit 41A are examples of an arm length changing unit provided on the measurement arm. The Littrow reflector 114 and the Littrow reflector drive unit 114A are examples of an arm length changing unit provided on the reference arm.

[0366] In addition to the above, as an arbitrary structure, the distance calculation unit 460A is capable of performing the following series of processing: (1) calculating the difference (arm length difference) between the first arm length applicable under the first scanning control (first OCT scan) and the second arm length applicable under the second scanning control (second OCT scan); (2) analyzing the first data obtained by the first OCT scan to determine the first position corresponding to the first part of the eye E to be inspected (for example, the signal position on the corneal surface); (3) analyzing the second data obtained by the second OCT scan to determine the second position corresponding to the second part of the eye E to be inspected (for example, the signal position on the retinal surface); (4) calculating the distance between the first part and the second part (for example, the axial length) based on at least one of the arm length difference calculated in (1), the first position determined in (2), the second position determined in (3), the first offset information and the second offset information obtained by the offset measurement unit 420.

[0367] Here, the distance calculation unit 460A may be configured as follows. First, the distance calculation unit 460A calculates a provisional distance between the first part and the second part based on the arm length difference, the first position, and the second position. Furthermore, the distance calculation unit 460A calculates the distance between the first part and the second part based on the provisional distance, at least one of the first offset information and the second offset information, and the corneal curvature radius of the subject's eye E acquired in advance.

[0368] As a specific example of such distance calculation, when the provisional distance between the first part and the second part is set to ALm, one of the first offset information and the second offset information is set to h, the corneal curvature radius is set to r, and the distance between the first part and the second part (true value) is set to AL, the distance calculation unit 460A can calculate the distance AL through the calculation formula AL=(rr×cos(arcsin(h / r)))+ALm×cos(arcsin(h / ALm)).

[0369] According to these arbitrary structures, specific processing for calculating the distance between the first part and the second part of the eye E to be inspected can be provided.

[0370] As an arbitrary structure, the scanning control unit 450A can cause the scanning unit 410 to perform multiple OCT scans under at least one of the first scanning control (first OCT scan) and the second scanning control (second OCT scan). In this case, the distance calculation unit 460A can obtain single data from the data group obtained by the multiple OCT scans. Here, the distance calculation unit 460A can generate single data by performing arithmetic averaging on the data group obtained by the multiple OCT scans. Moreover, the distance calculation unit 460A can calculate the distance between the first part and the second part (for example, the aforementioned provisional distance) using the obtained single data.

[0371] According to this arbitrary structure, even if opacities moving in the vitreous body have an adverse effect on the posterior ocular OCT scan, the reliability of distance measurement can be improved because the noise caused by the opacities can be reduced and removed, and data that is not affected by the opacities or is less affected by them can be selected.

[0372] As an arbitrary structure, the scanning control unit 450A can cause the scanning unit 410 to perform an OCT scan of a three-dimensional region of the subject's eye E under at least one of the first scanning control (first OCT scan) and the second scanning control (second OCT scan). In this case, the distance calculation unit 460A can determine a characteristic position corresponding to a characteristic point of the subject's eye E by analyzing data acquired through the OCT scan of the three-dimensional region. Furthermore, the distance calculation unit 460A can calculate the distance between the first part and the second part (for example, the aforementioned provisional distance) with the length of a line segment having the characteristic position as one end.

[0373] As a first typical example, the scanning control unit 450A can cause the scanning unit 410 to perform an OCT scan of a three-dimensional region including the corneal surface of the subject's eye E under the first scanning control (first OCT scan). Furthermore, the distance calculation unit 460A can determine a characteristic position corresponding to the corneal vertex of the subject's eye E by analyzing data acquired through the OCT scan of the three-dimensional region. In this case, the distance calculation unit 460A can calculate the distance between the first part and the second part (for example, the aforementioned provisional distance) as the length of a line segment having the corneal vertex as one end.

[0374] As a second typical example, the scanning control unit 450A can cause the scanning unit to perform an OCT scan of a three-dimensional area including the retinal surface of the subject's eye E under the second scanning control (second OCT scan). Furthermore, the distance calculation unit 460A can determine a characteristic position corresponding to the macula center of the subject's eye E by analyzing data acquired through the OCT scan of the three-dimensional area. In this case, the distance calculation unit 460A can calculate the distance between the first part and the second part (for example, the aforementioned provisional distance) as the length of a line segment having the macula center as one end.

[0375] By combining the first typical example and the second typical example, the length of the line segment having the corneal apex as one end and the macula center as the other end, that is, the axial length of the eye E to be examined can be obtained.

[0376] As an arbitrary structure, the displacement measuring unit 420 includes an alignment optical system 50 (projection system), two (or more) anterior segment cameras 300 (or more imaging units), and a displacement calculating unit 430. The alignment optical system 50 projects a light beam to the anterior segment of the subject's eye E. The two (or more) anterior segment cameras 300 capture the anterior segment of the subject's eye E from different directions. The displacement calculating unit 430 calculates the displacement of the subject's eye E from a predetermined reference position based on the positions of the light beam images (bright spots) respectively drawn in the two (or more) anterior segment images acquired by the two (or more) anterior segment cameras 300.

[0377] According to this optional configuration, a specific configuration and process for measuring the deviation of the subject's eye E from a predetermined reference position can be provided.

[0378] In addition, any matters (structure, elements, processing, actions, effects, functions, etc.) and any known matters described in the second embodiment can be combined with the ophthalmic device recorded in this effect column. In addition, any matters (structure, elements, processing, actions, effects, functions, etc.) described in the first embodiment can be combined with the ophthalmic device recorded in this effect column.

[0379] The second embodiment provides a control method of an ophthalmologic apparatus including a scanning unit 410 for applying OCT scanning to an eye E to be inspected, and a deviation measuring unit 420 for measuring deviation of the eye E to be inspected from a predetermined reference position.

[0380] The control method includes a first scanning control step, a second scanning control step, an offset measuring step, and a distance calculating step.

[0381] The first scanning control step causes the scanning unit 410 to perform an OCT scan of a first region including a first portion of the subject's eye E. This OCT scan is referred to as a first OCT scan. In addition, the second scanning control step causes the scanning unit 410 to perform an OCT scan of a second region including a second portion different from the first portion of the subject's eye E. This OCT scan is referred to as a second OCT scan.

[0382] The deviation measuring step causes the deviation measuring section 420 to execute at least one of a step of acquiring first deviation information of the subject's eye E in accordance with the first scanning control and a step of acquiring second deviation information of the subject's eye E in accordance with the second scanning control.

[0383] The distance calculation step calculates the distance between the first part and the second part of the eye E to be inspected based on at least one of the first offset information and the second offset information obtained in the offset measurement step, the first data obtained by the scanning unit 410 in the first scanning control step, and the second data obtained by the scanning unit 410 in the second scanning control step.

[0384] According to this method of controlling an ophthalmologic apparatus, the alignment error (offset information) in one or both of the first OCT scan and the second OCT scan is acquired, and the distance calculation can be performed in consideration of the alignment error. Therefore, the reliability of the distance measurement can be ensured.

[0385] In addition, any matter (structure, requirements, processing, action, effect, function, etc.) described in the first embodiment, any matter (structure, requirements, processing, action, effect, function, etc.) described in the second embodiment, and any publicly known matter can be combined into the control method.

[0386] A program that causes a computer to execute such a control method may be configured. For example, the program may include any of the above-mentioned programs for operating the ophthalmologic apparatus 1A of the second embodiment or its modified example.

[0387] In addition, a computer-readable nonvolatile storage medium storing such a program may be provided. The nonvolatile storage medium may be in any form, and examples thereof include a magnetic disk, an optical disk, a magneto-optical disk, and a semiconductor memory.

[0388] 〈Other matters〉

[0389] The above-described embodiments are merely examples of the present invention, and those who wish to implement the present invention can implement any modifications (such as omissions, substitutions, and additions) within the scope of the gist of the present invention.

[0390] For example, an ophthalmic device of an embodiment may have a structure for measuring the characteristics of an eye to be inspected. As a specific example, an ophthalmic device of an embodiment may have a structure for measuring the corneal curvature radius of the eye to be inspected. The structure for measuring the corneal curvature radius may include an optical system, a computing system, and a control system that are the same as those of a conventional corneal shape measuring device. As an example of a structure for measuring the corneal curvature radius, there is a structure using a corneal disc (corneal ring) or a Placido disc (Placido ring) disclosed by the present applicant in Japanese Patent Gazette No. 2017-063978. In addition, the corneal curvature radius can also be measured by an anterior ocular OCT scan. In addition, the structure for measuring the corneal curvature radius is not limited to these examples, and may be a structure using any known technology.

[0391] The characteristics of the eye to be examined that can be measured by the ophthalmic device of the embodiment are not limited to the corneal curvature radius. For example, the ophthalmic device of the embodiment may have a structure for measuring the refractive power (spherical degree, astigmatism degree, astigmatism axis angle, etc.) of the eye to be examined. The structure for measuring the refractive power of the eye to be examined may include the same optical system, computing system, and control system as the previous refractive power measuring device (refractometer). As an example of a structure for measuring refractive power, there is a structure disclosed by the applicant in Japanese Patent Gazette No. 2017-063978.

[0392] When the ophthalmologic apparatus of the embodiment has an eye refractive power measurement function, the ophthalmologic apparatus can use the eye refractive power measurement function to determine the focal position instead of using the focus optical system 60 as in the aforementioned disclosure, and move the OCT focus lens 43 to focus at the position.

[0393] In the above disclosure, as applicable alignment methods, a method using an alignment mark and a method using an anterior ocular camera are described, but other alignment methods may also be used. As an example of other alignment methods, there is a method using light cutting. In addition, an alignment method of an ophthalmic device using light cutting is disclosed in, for example, Japanese Patent Publication No. 2012-148032 and Japanese Patent Publication No. 2018-050922.

[0394] The displacement measuring unit of the ophthalmic apparatus of this example measures the displacement of the subject's eye from a predetermined reference position by using light section. The predetermined reference position is, for example, a position corresponding to the running distance, that is, a position away from the subject's eye in the z direction by the predetermined running distance, and the measured displacement is typically the displacement in the z direction.

[0395] The deviation measuring unit of this example includes a projection system that projects a light beam obliquely toward the anterior segment of the eye to be examined, and an image sensor that detects a reflected light beam from the anterior segment of the projected light beam. The structure and arrangement of the projection system and the image sensor may be the same as those of the conventional light-section type alignment component.

[0396] A typical projection system includes a light source and a lens. The optical axis of the typical projection system is tilted at a first angle in a first direction relative to the optical axis of the measuring arm (the optical axis of the objective lens). A typical image sensor is a CCD image sensor or a CMOS image sensor, and is a line sensor or an area sensor. Typically, an imaging lens is arranged between the image sensor and the eye E to be inspected. The optical axis of the detection system including the image sensor and the imaging lens is tilted at a second angle equal to the first angle in a second direction opposite to the first direction relative to the optical axis of the measuring arm.

[0397] With this structure and configuration, when the projection system and the detection system are located within a predetermined range relative to the eye to be inspected, the image sensor can detect the reflected light beam. In addition, if the relative position between the projection system and the detection system and the eye to be inspected changes, the detection position of the reflected light beam by the image sensor changes. That is, in response to the relative position between the projection system and the detection system and the eye to be inspected, the projection position of the reflected light beam on the light receiving area (light receiving device array) of the image sensor changes.

[0398] The offset measuring unit of this example includes an offset calculating unit that calculates the offset of the eye to be inspected based on the detection position of the reflected light beam by the image sensor. The calculation performed by the offset calculating unit of this example is the same as the calculation performed by the conventional light-cutting type alignment component, typically calculating the offset in the z direction. The offset calculating unit of this example is implemented by the cooperation of hardware including circuits and offset calculating software.

[0399] According to this example, it is possible to provide a specific configuration and process for measuring the deviation of the eye to be inspected from a predetermined reference position in the same manner as in the case of using an alignment mark or in the case of using two or more anterior ocular segment cameras.

Claims

1. An ophthalmic device comprising: A scanning unit, applying optical coherence tomography to the eye to be examined; A moving mechanism for moving at least a portion of the scanning unit; a deviation measuring unit for measuring a deviation of the eye to be inspected from a predetermined reference position; a scanning control unit that performs a first scanning control and a second scanning control, wherein the first scanning control causes the scanning unit to perform an optical coherence tomography scanning on a first area, the first area including a first part of the eye to be inspected, and the second scanning control causes the scanning unit to perform an optical coherence tomography scanning on a second area, the second area including a second part different from the first part; an alignment control section that performs a first alignment control for controlling the moving mechanism based on first displacement information of the eye to be inspected acquired by the displacement measuring section before the first scanning control, and a second alignment control for controlling the moving mechanism based on second displacement information of the eye to be inspected acquired by the displacement measuring section before the second scanning control; as well as a distance calculation unit that calculates the distance between the first part and the second part based on the first data acquired by the scanning unit under the first scanning control and the second data acquired by the scanning unit under the second scanning control, The offset measuring unit includes: A projection system projects a light beam toward the anterior part of the eye to be inspected; Two or more imaging units for imaging the anterior segment of the eye to be inspected from different directions; as well as The displacement calculation unit calculates the displacement of the eye to be inspected based on the positions of the light beam images respectively drawn in the two or more anterior ocular segment images acquired by the two or more imaging units.

2. The ophthalmic device according to claim 1, wherein: The scanning unit comprises: an interference optical system including a measurement arm for guiding measurement light to the eye to be inspected and a reference arm for guiding reference light; and an arm length changing unit, which is provided on at least one of the measuring arm and the reference arm and changes the arm length under the control of the scanning control unit, The distance calculation unit calculates the difference between a first arm length applicable under the first scanning control and a second arm length applicable under the second scanning control, analyzes the first data to determine a first position corresponding to the first part, analyzes the second data to determine a second position corresponding to the second part, and calculates the distance based on the difference, the first position, and the second position.

3. The ophthalmic device according to claim 1, wherein: The scanning control unit causes the scanning unit to perform a plurality of optical coherence tomography scans under at least one of the first scanning control and the second scanning control, The distance calculation unit acquires single data from a data group acquired by the plurality of optical coherence tomography scans, and calculates the distance using the single data.

4. The ophthalmic device according to claim 3, wherein: The distance calculation unit generates the single data by performing arithmetic averaging on the data group.

5. The ophthalmic device according to claim 1, wherein: The scanning control unit causes the scanning unit to perform optical coherence tomography scanning of a three-dimensional region of the eye to be inspected under at least one of the first scanning control and the second scanning control, The distance calculation unit analyzes data acquired by optical coherence tomography of the three-dimensional region, identifies a characteristic position corresponding to a characteristic point of the eye to be inspected, and calculates the distance as a length of a line segment having the characteristic position as one end.

6. The ophthalmic device according to claim 5, wherein: The scanning control unit causes the scanning unit to perform optical coherence tomography scanning of a three-dimensional region including a corneal surface of the eye to be inspected under the first scanning control, The distance calculation unit analyzes data acquired by optical coherence tomography of the three-dimensional area to determine a characteristic position corresponding to the corneal vertex.

7. The ophthalmic device according to claim 5, wherein: the scanning control section causes the scanning section to perform optical coherence tomography scanning of a three-dimensional region including a retinal surface of the eye to be inspected under the second scanning control, The distance calculation unit analyzes data acquired by optical coherence tomography of the three-dimensional area to determine a characteristic position corresponding to the center of the macula.

8. The ophthalmic device according to any one of claims 1 to 7, wherein: The offset measuring unit includes: A projection system projects a light beam from an oblique direction toward the anterior part of the eye to be inspected; an image sensor that detects a reflected light beam of the light beam from the anterior ocular portion; and The displacement calculation unit calculates the displacement of the eye to be inspected based on a detection position of the reflected light beam by the image sensor.

9. A method for controlling an ophthalmic device, the ophthalmic device comprising: A scanning unit, applying optical coherence tomography to the eye to be examined; A moving mechanism for moving at least a portion of the scanning unit; and a deviation measuring unit for measuring the deviation of the eye to be inspected from a predetermined reference position, wherein the control method comprises: a first alignment control step of controlling the moving mechanism based on first deviation information of the eye to be inspected acquired by the deviation measuring section; a first scanning control step of causing the scanning unit to perform optical coherence tomography scanning on a first area, the first area including a first part of the eye to be inspected; a second alignment control step of controlling the moving mechanism based on second deviation information of the eye to be inspected acquired by the deviation measuring section; a second scanning control step of causing the scanning unit to perform optical coherence tomography scanning on a second region, the second region including a second portion different from the first portion; and a distance calculation step of calculating the distance between the first part and the second part based on the first data acquired by the scanning unit in the first scanning control step and the second data acquired by the scanning unit in the second scanning control step, The offset measuring unit includes: A projection system projects a light beam toward the anterior part of the eye to be inspected; Two or more imaging units that image the anterior segment of the eye to be inspected from different directions; and The displacement calculation unit calculates the displacement of the eye to be inspected based on the positions of the light beam images respectively drawn in the two or more anterior ocular segment images acquired by the two or more imaging units. 10 . A computer-readable nonvolatile storage medium storing a program for causing a computer to execute the control method according to claim 9 .

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