Anterior eye segment analysis device, anterior eye segment analysis method, and program

Abstract

To appropriately execute segmentation for local irregularities of a layer constituting a cornea in a tomogram image of an anterior eye part.SOLUTION: An anterior eye part analysis device includes: an acquisition unit for acquiring a tomogram image of an anterior eye part including a cornea of an eye to be examined formed by OCT measurement; a detection unit for detecting a plurality of edges included in the tomogram image; a first connection unit for executing connection between the edges on the basis of a first connection condition for each of the plurality of edges; a selection unit for selecting a first edge and a second edge on the basis of the length out of the edges connected by the first connection unit; a second connection unit for executing connection between the edges on the basis of a second connection condition with the first edge and the second edge as references; and a determination unit for determining a border of a layer of the cornea in the tomogram image using the edges connected by the second connection unit.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an anterior eye segment analysis device, an anterior eye segment analysis method, and a program.

Background Art

[0002] In the field of ophthalmology, an ophthalmic device called OCT (Optical Coherence Tomography) is known. With OCT, it is possible to obtain tomographic images, frontal images, three-dimensional images, etc. of the fundus and anterior eye segment of the eye to be examined. Furthermore, the data obtained by OCT is used for analysis processing to grasp the state of the eye to be examined.

[0003] For example, Patent Document 1 describes a method of obtaining the shape of the tissue of the eye to be examined by performing segmentation processing on the tomographic image of the eye to be examined. In addition, Patent Document 2 describes a method of obtaining the internal surface shape of the eye assuming that the target eye moves or rotates. Furthermore, Patent Document 3 describes an ophthalmic information processing device that generates an analysis map of the thickness of the layer tissue of the eye.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] In OCT, it is conceivable to obtain tomographic images of the anterior segment and fundus of the eye to be examined. Among these, since the boundaries of the layers of the fundus can be imaged relatively clearly, segmentation, that is, separation into individual layers, can be easily performed from the captured images. On the other hand, for the anterior segment, due to the difficulty of obtaining clear images during the imaging operation, it is difficult to perform segmentation from the images.

[0006] For example, in a conventional method such as that of Patent Document 2, in the segmentation of the cornea located in the anterior segment, since the noise in the OCT image and the Bowman layer, which is an inter-tissue layer, have low contrast, the shape of the Bowman membrane is obtained by polynomial approximation. However, this method has a problem that it cannot appropriately segment the local uneven layers of the cornea of the diseased eye in the cornea located in the anterior segment.

[0007] In view of the above problems, an object of the present invention is to enable appropriate segmentation of the local unevenness of the layers constituting the cornea in the tomographic image of the anterior segment.

Means for Solving the Problems

[0008] In order to solve the above problems, one form of the present invention has the following configuration. That is, an anterior segment analysis device, an acquisition unit that acquires a tomographic image of the anterior segment of the eye to be examined including the cornea formed by OCT measurement; a detection unit that detects a plurality of edges included in the tomographic image; a first combining unit that combines edges based on a first combining condition for each of the plurality of edges; a selection unit that selects a first edge and a second edge based on length from among the edges combined by the first combining unit; a second combining unit that combines edges based on a second combining condition with each of the first edge and the second edge as a reference; a determination unit that determines the boundary of the cornea layer of the tomographic image using the edges combined by the second combining unit; and has.

[0009] Also, another aspect of the present invention has the following configuration. That is, an anterior segment analysis method comprising: an acquisition step of acquiring a tomographic image of the anterior segment including the cornea of the eye to be examined formed by OCT measurement; a detection step of detecting a plurality of edges included in the tomographic image; a first connection step of connecting edges based on a first connection condition for each of the plurality of edges; a selection step of selecting a first edge and a second edge based on length from among the edges connected in the first connection step; a second connection step of connecting edges based on a second connection condition with each of the first edge and the second edge as a reference; a determination step of determining the boundary of the corneal layer of the tomographic image using the edges connected in the second connection step; and having.

[0010] Also, another aspect of the present invention has the following configuration. That is, a program for causing a computer to perform an acquisition step of acquiring a tomographic image of the anterior segment including the cornea of the eye to be examined formed by OCT measurement, a detection step of detecting a plurality of edges included in the tomographic image, a first connection step of connecting edges based on a first connection condition for each of the plurality of edges, a selection step of selecting a first edge and a second edge based on length from among the edges connected in the first connection step, a second connection step of connecting edges based on a second connection condition with each of the first edge and the second edge as a reference, a determination step of determining the boundary of the corneal layer of the anterior segment using the edges connected in the second connection step, and causing it to execute.

Advantages of the Invention

[0011] According to the present invention, appropriate segmentation can be performed on local irregularities of the layers constituting the cornea in the anterior eye region.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0013] Examples of embodiments of the anterior eye segment analysis apparatus, anterior eye segment analysis method, and program according to the present invention will be described in detail with reference to the drawings. Note that the description contents of the documents cited in this specification and any known techniques can be incorporated into the following embodiments. The embodiments described below are one embodiment for explaining the present invention and are not intended to limit the interpretation of the present invention, and not all the configurations described in each embodiment are essential configurations for solving the problems of the present invention. Also, in each drawing, the same reference numerals are assigned to the same components to indicate the correspondence relationship.

[0014] As tissues in the eye to be examined, there are tissues in the anterior eye segment, tissues in the posterior eye segment, and the like. As tissues in the anterior eye segment, there are the cornea, iris, lens, ciliary body, zonular fibers, or angle. As tissues in the posterior eye segment, there is the fundus (a predetermined layer region in the fundus). The cornea located in the anterior eye segment that the present invention focuses on is formed by a plurality of layers. More specifically, from the front side of the cornea in order, it has a layer structure of corneal epithelial cells, Bowman's membrane, corneal stroma, Descemet's membrane, and corneal endothelial cells.

[0015] As described above, since the boundaries of the layers of the fundus can be imaged relatively clearly, separation into a single layer can be performed relatively easily from the captured image. On the other hand, for the anterior eye segment, due to the difficulty of obtaining a clear image in the imaging operation, it is difficult to separate the plurality of layers that make up the anterior eye segment as described above. Hereinafter, in the present embodiment, an anterior eye segment analysis method for more accurately detecting the layer structure of the anterior eye segment, particularly the cornea, will be described.

[0016] In the anterior eye segment analysis method according to an embodiment of the present invention, a tomographic image of the eye to be examined is acquired and used. The tomographic image can be obtained, for example, by performing optical coherence tomography (OCT) on the eye to be examined using an external ophthalmic system.

[0017] In this specification, the data acquired by OCT may be collectively referred to as OCT data. Also, the measurement operation for forming OCT data may be called OCT measurement, and the scan for performing OCT measurement may be called OCT scan.

[0018] <First Embodiment> Hereinafter, a case where an ophthalmic system according to an embodiment of the present invention includes an anterior eye segment analysis device will be described. The ophthalmic system includes an OCT device, and an OCT measurement is performed on an eye to be examined using the OCT device to acquire a tomographic image of the eye to be examined. However, the present invention is not limited to this configuration. For example, the anterior eye segment analysis device may be configured to include an interface for transmitting and receiving data from an external device or a recording medium via a network, and may be configured to acquire OCT data, tomographic images, etc. from an external ophthalmic system.

[0019] Hereinafter, the left-right direction (horizontal direction) orthogonal to the optical axis (measurement optical axis, inspection optical axis) of the device optical system of the ophthalmic system will be referred to as the X direction, the up-down direction (vertical direction) orthogonal to the optical axis will be referred to as the Y direction, and the direction of the optical axis (depth direction, front-rear direction) will be referred to as the Z direction for explanation. Note that the correspondence between the three-dimensional coordinate system in the real space and the three-dimensional coordinate system inside the system or in the three-dimensional data is not particularly limited, but it is assumed that these are associated in advance.

[0020] [System Configuration] FIG. 1 shows a configuration example of an ophthalmic system 1 configured to include functions for executing the anterior eye segment analysis method according to the present embodiment. Here, although a part of the system to which the anterior eye segment analysis method according to the present invention is applicable is typically shown, the ophthalmic system 1 may further include a configuration other than that shown in FIG. 1.

[0021] The ophthalmic system 1 is an inspection device including an objective refractometer (refraction measurement unit) and an OCT device (OCT unit). The ophthalmic system 1 includes a measurement unit 10, a control processing unit 50, a movement mechanism 90, a photographing unit 100, and a UI (User Interface) unit 110. The measurement unit 10 includes a refraction measurement unit 20, an OCT unit 30, a light projection unit 40, a beam splitter BS1, and a beam splitter BS2. The control processing unit 50 includes an image formation unit 60, a data processing unit 70, and a control unit 80.

[0022] (Refraction measurement unit) The refraction measurement unit 20 receives a control instruction from the control unit 80 and objectively measures the refractive power of the subject eye E. The refraction measurement unit 20 includes an optical system provided with one or more optical members for performing objective refraction measurement. The refraction measurement unit 20 has, for example, the same configuration as a known refractometer. Although illustration is omitted, a typical refractometer includes a projection system and a light receiving system as disclosed in Japanese Patent Application Laid-Open No. 2016-077774.

[0023] The projection system of the refraction measurement unit 20 projects the light emitted from the light source onto the fundus Ef of the subject eye E. The projection system projects the light from the light source onto the fundus Ef through, for example, a collimator lens, a focusing lens, a relay lens, a pupil lens, a perforated prism, an eccentric prism, an objective lens, etc.

[0024] The light receiving system of the refraction measurement unit 20 projects the reflected light from the fundus Ef onto an image sensor (not shown) through an objective lens, an eccentric prism, a perforated prism, another pupil lens, another relay lens, another focusing lens, a conical prism, an imaging lens, etc. Thereby, a ring pattern image formed on the imaging surface of the image sensor is detected.

[0025] The refraction measurement unit 20 may be configured to project a ring-shaped light onto the fundus Ef and detect a ring pattern image formed by the reflected light from the fundus Ef. Further, the refraction measurement unit 20 may be configured to project a bright spot onto the fundus Ef, convert the reflected light from the fundus Ef into a ring-shaped light, and detect a ring pattern image formed by the converted ring-shaped light.

[0026] (OCT section) The OCT section 30 receives a control instruction from the control section 80, applies an OCT scan to the eye to be examined E, and acquires OCT data. The OCT data may be interference signal data, reflection intensity profile data obtained by applying a Fourier transform to the interference signal data, or image data obtained by imaging the reflection intensity profile data. In this embodiment, an example using image data (hereinafter referred to as an OCT image) will be described.

[0027] The OCT method that the OCT section 30 can implement is typically Fourier domain OCT, and it may be either spectral domain OCT or swept source OCT. In swept source OCT, light from a wavelength-variable light source is split into measurement light and reference light, and the return light of the measurement light projected onto the eye to be examined is overlapped with the reference light to generate interference light. Then, this interference light is detected by a photodetector, and Fourier transform or the like is applied to the detection data (interference signal data) collected according to the wavelength sweep and the scan of the measurement light to form reflection intensity profile data. On the other hand, in spectral domain OCT, light from a low-coherence light source (broadband light source) is split into measurement light and reference light, and the return light of the measurement light projected onto the eye to be examined is overlapped with the reference light to generate interference light. Then, the spectral distribution of this interference light is detected by a spectrometer, and Fourier transform or the like is applied to the detection data (interference signal data) by the spectrometer to form reflection intensity profile data. That is, swept source OCT is an OCT method that acquires the spectral distribution in a time-division manner, and spectral domain OCT is an OCT method that acquires the spectral distribution in a space-division manner.

[0028] The OCT section 30 includes an optical system provided with one or more optical members for performing OCT measurement. The OCT section 30 has, for example, the same configuration as a known OCT apparatus. Although illustration is omitted, a typical OCT apparatus includes a light source, an interference optical system, a scan system, and a detection system as disclosed in Japanese Patent Application Laid-Open No. 2016-077774.

[0029] The light output from the light source is split into measurement light and reference light by an interference optical system. The reference light is guided to the reference arm. The measurement light is projected onto the eye E to be examined (for example, the fundus Ef) through the measurement arm. A scanning system is provided in the measurement arm. The scanning system includes, for example, an optical scanner and is capable of deflecting the measurement light one-dimensionally or two-dimensionally. The optical scanner includes one or more galvanometer scanners. The scanning system deflects the measurement light according to a predetermined scanning mode.

[0030] The control unit 80 included in the control processing unit 50 can control the scanning system according to the scanning mode. The scanning modes include line scan, raster scan (3D scan), circle scan, concentric circle scan, radial scan, cross scan, multi-cross scan, spiral scan, etc. A line scan is a scanning pattern along a linear trajectory. A raster scan is a scanning pattern consisting of a plurality of line scans arranged parallel to each other. A circle scan is a scanning pattern along a circular trajectory. A concentric circle scan is a scanning pattern consisting of a plurality of circle scans arranged concentrically. A radial scan is a scanning pattern consisting of a plurality of line scans arranged radially. A cross scan is a scanning pattern consisting of two line scans arranged orthogonally to each other. A multi-cross scan is a scanning pattern consisting of two groups of line scans (for example, each group includes five lines parallel to each other) arranged orthogonally to each other. A spiral scan is a scanning pattern extending spirally from the center.

[0031] The measurement light projected onto the fundus Ef is reflected and scattered at various depth positions (such as layer boundaries) of the fundus Ef. The return light of the measurement light from the eye E to be examined is combined with the reference light by the interference optical system. The return light of the measurement light and the reference light generate interference light according to the principle of superposition. This interference light is detected by the detection system. The detection system typically includes a spectrometer in spectral domain OCT and a balanced photodiode and a data acquisition system (DAQ) in swept source OCT.

[0032] (Light projection unit) The light projection unit 40 projects light for aligning the eye under examination E with the measurement unit 10 (OCT unit 30, device optical system) onto the eye under examination E. The light projection unit 40 includes a light source and a collimator lens. The optical path of the light projection unit 40 is coupled to the optical path of the refractive measurement unit 20 by a beam splitter BS2. The light output from the light source passes through the collimator lens, is reflected by the beam splitter BS2, and is projected onto the eye under examination E through the optical path of the refractive measurement unit 20.

[0033] In some embodiments, as disclosed in Japanese Unexamined Patent Application Publication No. 2016-077774, the reflected light from the cornea Ec (anterior eye segment) of the eye under examination E is guided to the light receiving system of the refractive measurement unit 20 through the optical path of the refractive measurement unit 20.

[0034] An image (bright spot image) based on the reflected light from the cornea Ec of the eye under examination E is included in the anterior eye segment image acquired by the imaging unit 100. For example, the control processing unit 50 causes the display unit (not shown) to display the anterior eye segment image including the bright spot image and the alignment mark on the display screen. When performing manual alignment in the XY directions (vertical and horizontal directions), the user can perform a moving operation of the optical system so as to guide the bright spot image into the alignment mark. When performing manual alignment in the Z direction (front-back direction), the user can perform a moving operation of the optical system while referring to the anterior eye segment image displayed on the display screen of the UI unit 110. When performing automatic alignment, the control unit 80 relatively moves the measurement unit 10 (optical system) with respect to the eye under examination E by controlling the moving mechanism 90 so that the displacement between the alignment mark and the position of the bright spot image is canceled. Further, the control unit 80 can relatively move the measurement unit 10 (optical system) with respect to the eye under examination E by controlling the moving mechanism 90 so as to satisfy a predetermined completion condition for alignment based on the position of a predetermined part (for example, the pupil center position) of the eye under examination E and the position of the bright spot image.

[0035] (Beam splitter) The beam splitter BS1 coaxially couples the optical path of the optical system (interference optical system, etc.) of the OCT unit 30 to the optical path of the optical system (projection system and light receiving system) of the refractive measurement unit 20. For example, a dichroic mirror is used as the beam splitter BS1. The beam splitter BS2 coaxially couples the optical path of the optical system of the light projection unit 40 to the optical path of the optical system (projection system and light receiving system) of the refractive measurement unit 20. For example, a half mirror is used as the beam splitter BS2.

[0036] The ophthalmic system 1 may have a function (fixation projection system) of presenting a fixation target for guiding the line of sight of the eye to be examined E to the eye to be examined E in response to a control instruction from the control unit 80. The fixation target may be an internal fixation target presented to the eye to be examined E or an external fixation target presented to the fellow eye. The optical path of the fixation projection system may be configured to be coaxially coupled to the optical path of the interference optical system of the OCT unit 30 by an optical path coupling member (for example, a beam splitter) disposed between the OCT unit 30 and the beam splitter BS1.

[0037] In response to a control instruction from the control unit 80, the projection position of the fixation target on the fundus Ef by the fixation projection system can be changed. The fixation target may be projected on the measurement optical axes of the optical systems of the refractive measurement unit 20 and the OCT unit 30 that are coaxially coupled. The fixation target may be projected at a position deviated from the measurement optical axis on the fundus Ef.

[0038] (Imaging unit) The imaging unit 100 includes one or more anterior segment cameras for imaging the anterior segment of the eye to be examined E. The imaging unit 100 acquires an anterior segment image that is a frontal image of the eye to be examined E. At least one anterior segment illumination light source (infrared light source, etc.) may be provided in the vicinity of the one or more anterior segment cameras. For example, for each anterior segment camera, an anterior segment illumination light source may be provided in the vicinity above and below it.

[0039] The ophthalmic system 1 can align the position of the measurement unit 10 (optical system) with respect to the eye E to be examined using the frontal image acquired by the imaging unit 100. The ophthalmic system 1 may identify the three-dimensional position of the eye E to be examined by analyzing the frontal image obtained by photographing the anterior segment of the eye E to be examined, and perform alignment by relatively moving the measurement unit 10 based on the identified three-dimensional position. The ophthalmic system 1 may perform alignment so that the displacement between the characteristic position of the eye E to be examined and the position of the image formed by the light projected by the light projection unit 40 is canceled.

[0040] The imaging unit 100 includes one or more anterior segment cameras. When the imaging unit 100 includes a single anterior segment camera, the ophthalmic system 1 analyzes the acquired frontal image to identify the two-dimensional position of the eye E to be examined in a plane orthogonal to the optical axis of the measurement unit 10 (a plane defined by the horizontal direction (X direction) and the vertical direction (Y direction)). In this case, the ophthalmic system 1 is provided with an optical system for identifying the position of the eye E to be examined in the direction of the optical axis of the measurement unit 10. Examples of such an optical system include the optical system of the optical lever method disclosed in Japanese Patent Application Laid-Open No. 2016-077774. The ophthalmic system 1 can identify the three-dimensional position of the eye E to be examined from the position of the eye E to be examined in the direction of the (measurement) optical axis of the measurement unit 10 and the above two-dimensional position using such an optical system.

[0041] When the imaging unit 100 includes two or more anterior segment cameras, the two or more anterior segment cameras photograph the anterior segment of the eye E to be examined from different directions. The two or more anterior segment cameras can photograph the anterior segment from two or more different directions substantially simultaneously. "Substantially simultaneously" means, for example, allowing a deviation in the imaging timing that is negligible for eye movement in the imaging by the two or more anterior segment cameras. Thereby, images when the eye E to be examined is substantially in the same position (orientation) can be acquired by the two or more anterior segment cameras. The ophthalmic system 1 identifies the characteristic position of the eye E to be examined by analyzing the acquired frontal image, and identifies the three-dimensional position of the eye E to be examined from the positions of the two or more anterior segment cameras and the identified characteristic position of the eye E to be examined, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2013-248376.

[0042] Shooting by two or more anterior eye cameras may be video shooting or still image shooting. In the case of video shooting, substantially simultaneous anterior eye shooting as described above can be achieved by controlling to match the shooting start timing, controlling the frame rate, or the shooting timing of each frame. On the other hand, in the case of still image shooting, this can be achieved by controlling to match the shooting timing.

[0043] (Control processing unit) The control processing unit 50 executes various calculations and various controls for operating the ophthalmic system 1. The control processing unit 50 includes one or more processors and one or more storage devices. Examples of the storage device include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), and SSD (Solid State Drive). Various computer programs are stored in the storage device, and based on these, the operations and controls according to this embodiment are realized by the operation of the processor.

[0044] In this embodiment, the control processing unit 50 realizes the functions of the image forming unit 60, the data processing unit 70, and the control unit 80 by the processor executing various programs. Note that the block configuration of the functions realized by the control processing unit 50 is an example, and it may be further divided in more detail corresponding to each of the above-described processes.

[0045] (Image forming unit) The imaging unit 60 forms an image (such as a tomographic image) of the eye to be examined E based on the OCT data obtained by performing OCT measurement on the eye to be examined E. The imaging unit 60 constructs OCT data (typically image data) based on the detection data by the detection system of the OCT unit 30. Similar to conventional OCT data processing, the imaging unit 60 applies filter processing, fast Fourier transform (FFT), etc. to the detection data to construct reflection intensity profile data for each A-line (the path of the measurement light in the eye to be examined E). Further, the imaging unit 60 constructs image data (A-scan data) for each A-line by applying imaging processing (image representation) to this reflection intensity profile data. Note that part of the functions of the imaging unit 60 may be provided in the OCT unit 30.

[0046] When the apparatus for executing the anterior eye segment analysis method according to the present embodiment is realized as a device separate from the measurement unit 10, the imaging unit 60 may be configured as an acquisition unit that acquires OCT data via a network (not shown).

[0047] (Data processing unit) The data processing unit 70 is capable of executing processing for aligning the position of the measurement unit 10 with respect to the eye to be examined E. Examples of the processing for alignment include analysis processing of the frontal image of the eye to be examined E acquired using the imaging unit 100, calculation processing of the position of the eye to be examined E, and calculation processing of the displacement of the measurement unit 10 with respect to the eye to be examined E.

[0048] Further, the data processing unit 70 can specify the surface shape of the cornea Ec of the eye to be examined E from the tomographic image of the eye to be examined E obtained by performing OCT measurement after alignment, and further generate shape data representing the structure of the cornea Ec. For example, the shape data can be obtained by performing segmentation processing on the tomographic image as an OCT image. In the present embodiment, analysis processing including segmentation processing for the cornea Ec included in the anterior eye segment is performed, and display processing based on the analysis result and the like is performed. Details will be described later.

[0049] (Control Unit) The control unit 80 controls each part of the ophthalmic system 1. The control unit 80 includes a storage device (not shown) as described above and can store various types of information. The information stored in the storage device includes, but is not particularly limited to, programs for controlling each part of the ophthalmic system 1, subject information, information on the eye to be examined, measurement data obtained by the measurement unit 10, processing results by the data processing unit 70, and the like.

[0050] The control unit 80 can control the UI unit 110. The UI unit 110 functions as part of the user interface, functions as a display device that receives a control instruction from the control unit 80 and displays information and display screens, or functions as an operating device that receives operations from the user. To function as a display device, the UI unit 110 may include, for example, a liquid crystal display (LCD) or an organic light-emitting diode (OLED) display.

[0051] The control unit 80 can control the ophthalmic system 1 according to a signal input via the UI unit 110. To function as an operating device, the UI unit 110 may include various hardware keys (such as a joystick, buttons, switches, etc.) provided on the ophthalmic system 1. Also, the UI unit 110 may include various peripheral devices (such as a keyboard, mouse, joystick, operation panel, etc.) connected to the ophthalmic system 1. Further, the UI unit 110 may include various software keys (such as buttons, icons, menus, etc.) displayed on a touch panel.

[0052] (Moving Mechanism) The moving mechanism 90 is a mechanism for moving the measurement unit 10 in which optical systems (apparatus optical systems) such as the refractive power measurement unit 20, the OCT unit 30, the light projection unit 40, and the beam splitters BS1 and BS2 are housed in the vertical, horizontal, and front-back directions. The moving mechanism 90 can receive a control instruction from the control unit 80 and relatively move the measurement unit 10 with respect to the eye to be examined E. For example, the moving mechanism 90 is provided with an actuator (not shown) that generates a driving force for moving the measurement unit 10 and a transmission mechanism (not shown) that transmits this driving force. The actuator is constituted by, for example, a pulse motor. The transmission mechanism is constituted by, for example, a combination of gears or a rack and pinion. The control unit 80 controls the moving mechanism 90 by sending a control signal to the actuator.

[0053] The control of the moving mechanism 90 is used in alignment. For example, the control unit 80 acquires the current position of the measurement unit 10 (apparatus optical system). The control unit 80 receives information representing the content of the movement control of the moving mechanism 90 and acquires the current position of the measurement unit 10. In this case, the control unit 80 controls the moving mechanism 90 at a predetermined timing (such as at the time of apparatus startup or patient information input) to move the measurement unit 10 to a predetermined initial position. After that, each time the control unit 80 controls the moving mechanism 90, it records the control content. Thereby, a history of the control content is obtained. The control unit 80 refers to this history as an optical system position acquisition unit to acquire the control content up to the present, and obtains the current position of the measurement unit 10 based on this control content.

[0054] The control of the moving mechanism 90 may be used in tracking. Tracking is to move the apparatus optical system in accordance with the eye movement of the eye to be examined E. When performing tracking, alignment and focus adjustment are executed in advance. Tracking is a function of maintaining a suitable positional relationship with the correct position and focus by causing the position of the apparatus optical system to follow the eye movement.

[0055] [Layers of the cornea] As described above, the corneal Ec located in the anterior eye part has a layered structure and includes corneal epithelial cells, Bowman's membrane, corneal stroma, Descemet's membrane, and corneal endothelial cells. FIG. 2 is a diagram for explaining a detection example of the boundary of each layer of the conventional cornea. The image 200 shows a part of the cornea, and here, detection examples of the boundary 201 on the front side of the corneal epithelium, the boundary 202 between the corneal epithelium and Bowman's membrane, and the boundary 203 on the fundus side of the corneal endothelium are shown. The thickness of the cornea is about 0.5 mm. Among them, Bowman's membrane has a thickness of about 8 to 14 μm and is a thinner layer compared to other components such as corneal epithelial cells and corneal stroma.

[0056] In the conventional method, when detecting the boundary 202 between Bowman's membrane and the corneal epithelium, for example, as described in Japanese Patent Application Laid-Open No. 2020-48857, the detection was performed using an approximation curve. When detecting the boundary using an approximation curve, for example, the curve 205 is obtained as the boundary. When such a detection method is used, as shown in the region 204, the unevenness generated in Bowman's membrane and the like cannot be accurately detected.

[0057] In the anterior eye part analysis method according to the present embodiment, it is possible to detect the unevenness generated inside the cornea as described above, and to achieve more accurate detection.

[0058] [Processing Flow] Hereinafter, the processing of the anterior eye part analysis method according to an embodiment of the present invention will be described. This processing is realized, for example, by a control processing unit 50 operating by a processor provided in the ophthalmic system 1 reading and executing various programs stored in a storage device.

[0059] In step S101, the image forming unit 60 acquires OCT data of the eye to be examined that is the processing target. Under the control of the control unit 80, the measurement unit 10 and the moving mechanism 90 may be operated to photograph the eye to be examined to newly acquire OCT data, or OCT data held in a storage device or the like may be acquired. Here, the OCT data to be acquired may be specified by the user. At this time, as preprocessing for the OCT data, tone conversion processing, image enhancement processing, threshold processing, contrast conversion processing, binarization processing, edge detection processing, image averaging processing, image smoothing processing, filter processing, region extraction processing, alignment processing, etc. may be performed. Note that the preprocessing is not limited to the above, and other processing may be performed in consideration of each subsequent process.

[0060] In step S102, the data processing unit 70 performs edge detection processing on the OCT data acquired in step S101 to detect the boundary on the front side of the corneal epithelium. The boundary detected here corresponds to the boundary 201 shown in FIG. 2. That is, it corresponds to the edge located on the very front side of the cornea. Examples of the edge detection method include, but are not particularly limited to, the well-known Canny Edge method. Further, the data processing unit 70 detects the boundary on the front side of the corneal epithelium by an approximate curve based on the detected edge.

[0061] In step S103, the data processing unit 70 performs alignment processing of the original OCT image so that the detected boundary becomes a straight line based on the position of the boundary detected in step S102. That is, the pixels constituting the detected boundary are arranged so as to be linear, and further, pixel position conversion is performed while maintaining the positional relationship in a predetermined direction between the pixels constituting the boundary and other pixels. Therefore, the positional relationship (distance) in the thickness direction between the pixels of the boundary and the surrounding pixels does not change from the original image. By performing such alignment processing, it becomes possible to identify fine structures even in a process that requires an accuracy of several μm such as detecting each layer constituting the cornea.

[0062] In step S104, the data processing unit 70 extracts a region of a predetermined size based on the boundary from the image after the alignment process obtained in step S103. As a result, a corneal image 401 on a rectangle as shown in FIG. 4(a) is obtained. The predetermined size of the region to be extracted is not particularly limited. For example, it may be 50 pixels in the direction orthogonal to the boundary and 1024 pixels in the direction parallel to the boundary. Also, the upper end in the vertical direction corresponds to the straight line obtained at the boundary detected in step S102.

[0063] In step S105, the data processing unit 70 performs a process of specifying the boundary of the Bowman's membrane using the corneal image obtained in step S104. The details of this step will be described in detail with reference to FIG. 5.

[0064] In step S106, the data processing unit 70 performs a display process based on the boundary of the Bowman's membrane specified in step S105. An example of the configuration of the screen to be displayed on the UI unit 110 in the display process will be described later. Then, this processing flow ends.

[0065] (Process of specifying the boundary of the Bowman's membrane) FIG. 6 is a flowchart showing the details of the process of step S105 in FIG. 3.

[0066] In step S201, the data processing unit 70 performs edge detection processing on the corneal image. Examples of the edge detection method include, but are not particularly limited to, the well-known Canny Edge method. For example, as a result of performing edge detection processing on the corneal image 401 shown in FIG. 4(a), a corneal image 402 including a plurality of edges as shown in FIG. 4(b) is obtained.

[0067] In step S202, the data processing unit 70 performs region division on the corneal image obtained in step S201. In the present embodiment, the corneal image is divided into a first region on the central side (inner side) of the cornea and a second region on the scleral side (outer side) of the cornea. FIG. 6 shows an example of dividing the corneal image 402 shown in FIG. 4(b) into a first region and a second region. Here, based on the left end of the corneal image, in the horizontal direction, the ranges of 0 to 200 and 800 to 1024 pixels are regarded as the second region, and the range of 201 to 799 pixels is regarded as the first region. The division method here is an example and is not limited thereto. For example, the range may be changed according to the size of the image. Also, although an example of dividing into two regions is shown here, it may be divided into more regions.

[0068] In step S203, the data processing unit 70 performs edge connection processing on various edges included in the first region. FIG. 7 is a diagram for explaining the conditions at the time of edge connection. Here, the vertical direction (i.e., corresponding to the thickness direction of the cornea) is defined as the x direction, and the horizontal direction (i.e., corresponding to the width direction of the cornea) is defined as the y direction for explanation. FIG. 7(a) shows that if the distance dx in the x direction between the closer endpoints of two edges is greater than or equal to a predetermined value, connection is not performed. That is, if the distance dx between two edges is less than the predetermined value, the endpoints between the two edges are connected by a straight line. Similarly, FIG. 7(b) shows that if the distance dy in the y direction between the closer endpoints of two edges is greater than or equal to a predetermined value, connection is not performed. That is, if the distance dy between two edges is less than the predetermined value, the endpoints between the edges are connected by a straight line. FIG. 7(c) shows that if the overlapping length dl is greater than or equal to a predetermined value when two edges overlap in the x direction, connection is not performed. That is, if the overlapping length dl of two edges is less than the predetermined value, the endpoints between the edges are connected by a straight line. At this time, smoothing processing may be performed during connection or other connection processing may be performed. Also, when connecting edges that partially overlap in the vertical direction, the upper edge (i.e., the front side of the cornea) may be preferentially connected at the overlapping portion.

[0069] In the above example, a method of combining using three conditions is shown. However, any of these may be used for combination, or combination may be performed using other conditions. Also, among the three conditions, there is no particular limitation on which condition is to be preferentially applied. Here, the process is repeated by focusing on the two edges whose endpoints are closest to each other. For convenience, the threshold values of the respective conditions used in step S203 are represented as Th dx1 , Th dy1 , Th dl1 .

[0070] In step S204, the data processing unit 70 removes edges based on length and intensity in the first region after the processing of step S203. Among the edges included in the first region, edges with a length of threshold Th l1 or less are removed. Also, among the edges included in the first region, edges with a maximum intensity of the pixels constituting the edge of threshold Th d1 or less are removed. The threshold Th l1 and the threshold Th d1 used here are predefined and held in the storage device. Here, the length may be defined for each of the vertical and horizontal directions, or may be defined by the number of pixels. Also, the intensity here may be defined by the pixel value (for example, luminance value). In this step, edge removal is performed based on both length and intensity, but edge removal may be performed based on either one of them. By performing such edge removal, edges that are clearly not boundaries (edges with low accuracy as boundaries) are removed, improving the detection accuracy and enabling the efficiency of the subsequent edge combination process to be improved.

[0071] In step S205, the data processing unit 70 performs edge combination processing again in the first region where edge removal was performed in step S204, in the same manner as in step S203. The difference from step S203 is that the threshold values used as combination conditions are made different. The threshold values of the respective conditions used in step S205 are represented as Th dx2 , Th dy2 , Th dl2is shown as. In this case, Th dx2 > Th dx1 、Th dy2 > Th dy1 、Th dl2 > Th dl1 is set. That is, even edges that are farther away in step S205 are treated as connection targets.

[0072] In step S206, the data processing unit 70 designates the longest edge among the edges included in the first region after the processing of step S205 as the first edge, and the second longest edge as the second edge. The length here may be specified by the number of pixels, or may be specified based on the horizontal length in the image.

[0073] In step S207, the data processing unit 70 performs edge connection processing in the first region after the processing of step S205, with each of the first edge and the second edge as a reference. The connection conditions here may be the same as in step S203, but the threshold values for connection are made different. Let the threshold values for each condition used in step S207 be Th dx3 、Th dy3 、Th dl3 is shown as. In this case, Th dx3 > Th dx2 > Th dx1 、Th dy3 > Th dy2 > Th dy1 、Th dl3 > Th dl2 > Th dl1 is set. That is, in step S207, even edges that are farther away with respect to the endpoints of the first edge and the second edge are treated as connection targets. As a result of this processing, it is possible that the first edge and the second edge are connected.

[0074] In step S208, the data processing unit 70 determines whether the first edge and the second edge are combined in the process of step S207. If the first and second edges are combined (YES in step S208), the process of the data processing unit 70 proceeds to step S210. On the other hand, if the first and second edges are not combined (NO in step S208), the process of the data processing unit 70 proceeds to step S209.

[0075] In step S209, the data processing unit 70 performs noise determination processing on the shorter of the two uncombined edges based on the first edge and the second edge. That is, of the two edges, the longer one is regarded as the boundary and the more reliable edge is handled. The noise determination processing here is determined based on the vertical distance between the two edges. If the vertical distance is smaller than a predetermined threshold Th dx4 the data processing unit 70 determines that the shorter edge is noise. The threshold Th dx4 is defined in advance and stored in the storage device.

[0076] In step S210, the data processing unit 70 identifies one or two reference edges. More specifically, when the first edge and the second edge are combined or when one of them is determined to be noise, the longer one of the edges is identified as the reference edge. On the other hand, when the first edge and the second edge are not combined and neither of them is determined to be noise, the two edges are identified as the reference edges.

[0077] In step S211, the data processing unit 70 performs edge removal processing in the second region with reference to the positions of the one or two reference edges identified in step S210. Here, based on the position of the reference edge, edges with a predetermined threshold or more are removed based on the horizontal and vertical distances and the degree of overlap. Also, in the second region, edges with a length of threshold Th l2 or less are removed. Also, in the second region, the maximum intensity of the pixels constituting the edge is the threshold Th d2The following edges are removed. The threshold Th used here l2 and the threshold Th d2 are predefined and stored in the storage device. The length here may be defined for each of the vertical and horizontal directions, or may be defined by the number of pixels. Also, the intensity here may be defined by the pixel value (e.g., luminance value). Note that the threshold Th l2 and the threshold Th d2 may be the same values as the threshold Th l1 and the threshold Th d1 used for edge removal in the first region in step S204, or may be different values. Note that in this step, edge removal is performed based on both length and intensity, but edge removal may also be performed based on either one of them. By using the position of the reference edge as a reference, it becomes possible to efficiently remove edges with low boundary accuracy, reduce the processing load of subsequent edge connection, or shorten the processing time.

[0078] In step S212, the data processing unit 70 performs an edge connection process in the second region after the edge removal process is performed in step S211, with the one or two reference edges specified in step S210 as a reference. The connection conditions here may be the same as in step S203 and step S205.

[0079] In step S213, the data processing unit 70 specifies one edge from among the edges after the edge connection process in step S212. In this state, in the corneal image, one or two edges based on one or two reference edges are included. When only one edge can be specified at this time, that edge is specified. On the other hand, when two edges are included and they overlap in the vertical direction, the edge located on the upper side, i.e., the front part side of the cornea, is specified. When they do not overlap in the vertical direction, the nearer endpoints of each edge are connected by a straight line to form one edge, and then that edge is specified.

[0080] In step S214, the data processing unit 70 performs a smoothing process on the edge identified in step S213. The smoothing process may use a known method and is not particularly limited, but it is adjusted so that uneven portions such as those shown in region 204 of FIG. 2 are not overly corrected.

[0081] In step S215, the data processing unit 70 identifies the edge on which the smoothing process was performed in step S214 as the boundary of the Bowman's membrane. FIG. 4(c) is a corneal image 420 showing the boundary of the Bowman's membrane identified by the processing so far.

[0082] In step S216, the data processing unit 70 associates the position (coordinates) of the boundary identified in step S215 within the corneal image with the original OCT data. At this time, the association of coordinates and the like is performed based on the processing parameters of the boundary detection (step S102), alignment processing (step S103), and boundary extraction (step S104) of the corneal epithelium in FIG. 3 respectively. Then, this processing flow is terminated, and the process proceeds to step S106 in FIG. 4.

[0083] [Improvement of Artifacts] FIG. 8 is a diagram for explaining artifacts that occur during OCT measurement. As a result of performing OCT measurement on the eye to be examined, a corneal image 800 as shown in FIG. 8(a) may be obtained. At this time, as shown in region 801, vertical line - strong artifacts may occur at a position corresponding to the corneal apex. Such artifacts can be caused by reflections from locations perpendicular to the incident light during OCT measurement. When proceeding with the analysis process of an image containing artifacts, as in the corneal image 810 shown in FIG. 8(b), the edges of the region 811 where the artifacts are located cannot be properly detected. As a result, the distance between the edges to be detected becomes separated. This distance varies depending on the imaging conditions. Therefore, it is difficult to stipulate correction parameters and the like in advance considering all imaging conditions. Also, if appropriate condition settings are not made, excessive noise and the like are included, and the detection accuracy decreases.

[0084] However, in the anterior eye segment analysis method according to the present invention, as described above, two edges (the first edge and the second edge) having a long length are specified, and the boundary is detected based on these. Therefore, for example, even when an artifact is included as in the corneal image 800 of FIG. 8(a), as shown in FIG. 8(c), edge connection can be appropriately performed in the region 821 where the artifact is located, and one edge can be specified.

[0085] [Display screen] An example of a display screen based on the analysis result obtained by the anterior eye segment analysis method according to the present embodiment will be described. The display screen shown below is displayed, for example, on the UI unit 110.

[0086] FIG. 9 shows an example of a display screen in which the detected boundary is superimposed on OCT data. FIG. 9(a) shows an example of OCT data 900 obtained as a result of performing OCT measurement on the cornea. FIG. 9(b) is an example of a display image 910 in which each boundary is detected by applying the anterior eye segment analysis method according to the present embodiment to the OCT data 900 and the superimposed display is performed. In the display image 910, three boundaries are shown, which are, in order from the top, the boundary on the front side of the corneal epithelium, the boundary between the corneal epithelium and Bowman's membrane, and the boundary on the fundus side of the corneal endothelium.

[0087] In the display screen, the OCT data as shown in FIG. 9(a) and the display screen as shown in FIG. 9(b) may be configured to be switchable, or both may be displayed side by side. Further, the display method of the detected boundary is not particularly limited, and for example, the line type and the color of the line may be configured to be switchable.

[0088] FIG. 10 shows an example of a display screen 1000 for showing the thickness of the membrane derived based on the boundary obtained by the anterior eye segment analysis process according to the present invention. Here, for the eye to be examined, boundary is specified by performing the anterior eye segment analysis process on each of a plurality of OCT data obtained by performing a plurality of OCT scans, and the thickness of the corneal epithelium throughout the cornea is derived. The thickness of the corneal epithelium corresponds to, for example, the distance from the boundary on the front side of the corneal epithelium to the boundary between the corneal epithelium and Bowman's membrane. The thickness may be specified based on the length per pixel in the OCT data. When deriving a thickness map showing the thickness of the entire cornea, thickness is derived from the boundaries obtained from each of a plurality of OCT data (for example, 12 OCT data obtained by radial scan) to generate a sparse thickness map. Further, a dense thickness map may be generated by linear interpolation or the like from the thickness at each position in the cornea corresponding to each of the plurality of OCT data. Note that the interpolation method is not limited to linear interpolation, and other methods may be used.

[0089] In addition, in a plurality of OCT measurements when measuring the cornea, the number of measurements, the direction of measurement, etc. are not particularly limited. For example, while rotating at predetermined angles around the center of the cornea as the rotation axis, radial scan may be performed to acquire OCT data. Alternatively, a plurality of raster scans may be performed in parallel in a predetermined direction (for example, the vertical direction) to acquire OCT data. In addition, OCT data may be acquired based on various scan patterns as described above.

[0090] The thickness map 1001 shows the entire area of the cornea and shows the thickness of the corneal epithelium in the cornea in gradation. Here, an example in which the cornea is divided into 25 regions is shown, but the number of divided regions is not particularly limited. The numerical value shown in each region indicates the average value of the thickness in that region. "N" shown on the left of the thickness map 1001 indicates the nasal side of the eye to be examined, and "T" shown on the right side of the thickness map 1001 indicates the temporal side of the eye to be examined.

[0091] The scale 1002 indicates the thickness value for the gradation shown in the thickness map 1001. Here, it represents that the thickness is shown in the range of 20 to 80 [μm]. The scale 1002 indicates the horizontal length of the thickness map 1001, and the range from -4.5 to 4.5 [mm] is shown with the center of the cornea being 0. The parameter group 1004 indicates the values of various parameters corresponding to the thickness map 1001. Here, it shows the minimum value (Min) of the thickness, the maximum value (Max) of the thickness, the overall average value (Avg) of the thickness, the difference (S-I) between the average values of the thicknesses of the upper region and the lower region, and the difference (ST-IN) between the average values of the thicknesses of the region above T (ear) and the region below N (nose). Note that the icon 〇 corresponding to the minimum value of the thickness and the icon △ corresponding to the maximum value are shown in the thickness map 1001, indicating their respective detection positions.

[0092] Note that the content and configuration displayed on the display screen 1000 are just examples, and other configurations may be used. For example, in the parameter group 1004, five parameters are shown, but the parameters to be displayed may be configured to be specifiable by the user. Also, the presence or absence of the numerical values displayed on the thickness map 1001 may be configured to be switchable. Further, in FIG. 10, the thickness map 1001 corresponding to one eye under examination is displayed, but both eyes or comparison targets (e.g., past measurement results) may be arranged and displayed side by side.

[0093] As described above, according to this embodiment, appropriate segmentation is possible for the local unevenness of the layers constituting the cornea in the anterior segment of the eye. In particular, compared with the method using curve approximation, it can capture the unevenness occurring at the boundary of Bowman's membrane, etc., and even when the imaging accuracy in OCT measurement of the anterior segment of the eye is low, it is possible to accurately identify the boundary.

[0094] <Other Embodiments> In the present invention, a program or an application for realizing the functions of the above-described one or more embodiments can also be realized by supplying it to a system or a device using a network or a storage medium or the like, and causing one or more processors in a computer of the system or the device to read and execute the program.

[0095] Note that in this specification, the “processor” means, for example, a general-purpose or dedicated circuit such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), or a programmable logic device (for example, an SPLD (Simple Programmable Logic Device), a CPLD (Complex Programmable Logic Device), an FPGA (Field Programmable Gate Array)).

[0096] In addition, a program for causing a computer to execute a control method for controlling the above-described device is provided, not limited to the method shown as an example above. Such a program can be stored in any recording medium readable by a computer. As this recording medium, for example, a semiconductor memory, an optical disk, a magneto-optical disk (CD-ROM / DVD-RAM / DVD-ROM / MO, etc.), a magnetic storage medium (hard disk / floppy (registered trademark) disk / ZIP, etc.) can be used. Also, it is possible to transmit and receive this program through a network such as the Internet or a LAN. Similarly, a configuration may be adopted in which the operation of the device is controlled based on the processing result executed by a processing unit arranged on the network or a control instruction.

[0097] Thus, the present invention is not limited to the above-described embodiments, and it is also contemplated by the present invention that those skilled in the art can make any changes, applications, omissions, and additions based on the combination of each configuration of the embodiments, the description in the specification, and well-known techniques, and they are included in the scope for which protection is sought.

[0098] As described above, the following matters are disclosed in this specification. (1) An acquisition unit (for example, the image formation unit 60) that acquires a tomographic image of the anterior eye part including the cornea of the eye to be examined formed by OCT measurement, a detection unit (for example, the data processing unit 70) that detects a plurality of edges included in the tomographic image, a first combining unit (for example, the data processing unit 70) that combines the edges based on a first combining condition for each of the plurality of edges, a selection unit (for example, the data processing unit 70) that selects a first edge and a second edge based on the length from among the edges combined by the first combining unit, a second combining unit (for example, the data processing unit 70) that combines the edges based on a second combining condition with respect to each of the first edge and the second edge, a determination unit (for example, the data processing unit 70) that determines the boundary of the corneal layer of the tomographic image using the edges combined by the second combining unit, An anterior eye part analysis apparatus (for example, the ophthalmic system 1, the control processing unit 50) characterized by having the above. According to this configuration, appropriate segmentation can be performed on the local unevenness of the layers constituting the cornea in the anterior eye part. In particular, even when the imaging of the anterior eye part is unclear in OCT measurement, the uneven shape of Bowman's membrane can also be accurately detected.

[0099] (2) The detection unit identifies the front side boundary of the corneal epithelium in the tomographic image, and detects the plurality of edges for a predetermined range from the identified front side boundary, The anterior eye part analysis apparatus according to (1), characterized by the above. According to this configuration, by performing detection within a range defined in advance for the plurality of layers constituting the cornea, the processing load related to boundary detection can be reduced, and it becomes possible to efficiently detect the boundary.

[0100] (3) The tomographic image is divided into a first region that is a region on the corneal apex side of the eye to be examined and a second region that is a region on the scleral side of the cornea of the eye to be examined, The first joint part performs processing on the first region, The second joint part performs processing on the first region and the second region. The anterior eye segment analysis device according to (1) or (2), characterized in that. According to this configuration, a more accurate detection process is performed on the apex side of the cornea, and based on the result, the outer detection is performed. Thereby, without reducing the detection accuracy in the entire region where the boundary is detected, the processing load related to the detection of the boundary can be reduced, and the boundary can be detected efficiently.

[0101] (4) The second joint part makes the joint condition when joining the edges in the first region different from the joint condition when joining the edges in the second region. The anterior eye segment analysis device according to (3), characterized in that. According to this configuration, without reducing the detection accuracy in the entire region where the boundary is detected, the processing load related to the detection of the boundary can be reduced, and the boundary can be detected efficiently. In particular, it becomes possible to detect edges more efficiently in the second region.

[0102] (5) In the first region, when the first edge and the second edge overlap by a predetermined length or more in the width direction of the cornea, the second joint part determines the longer one of the first edge and the second edge as the boundary of the corneal layer. The anterior eye segment analysis device according to (3) or (4), characterized in that. According to this configuration, it becomes possible to efficiently specify an edge with a higher degree of certainty as the boundary based on the length.

[0103] (6) When the first edge and the second edge do not overlap in the width direction of the cornea in the first region, the second coupling portion couples the first edge and the second edge to determine it as the boundary of the layer of the cornea. The anterior eye analysis device according to any one of (3) to (5), characterized in that. According to this configuration, even when there is a break in the width direction between the edges included in the OCT image, it is possible to appropriately connect the edges and specify the boundary by interpolating between them.

[0104] (7) When the first edge and the second edge do not overlap in the width direction of the cornea within a range defined based on the imaging conditions of the OCT measurement in the first region, the second coupling portion couples the first edge and the second edge to determine it as the boundary of the layer of the cornea. The anterior eye analysis device according to (6), characterized in that. According to this configuration, even in the case where an artifact is included at a position such as the corneal apex in the OCT image and the edge cannot be extracted by the artifact, it is possible to interpolate the edge and accurately specify the boundary.

[0105] (8) The first coupling condition and the second coupling condition are different in at least one of the distance in the thickness direction of the cornea, the distance in the width direction of the cornea, the degree of overlap in the width direction of the cornea, and the edge strength when coupling the edges. The anterior eye analysis device according to any one of (1) to (7), characterized in that. According to this configuration, it is possible to appropriately connect the edges and specify the boundary by performing a connection process on a plurality of edges included in the OCT image using a plurality of connection conditions.

[0106] (9) The second coupling portion further performs a smoothing process on the coupled edges. The anterior eye analysis device according to any one of (1) to (8), characterized in that. According to this configuration, even when unevenness such as steps occurs during the edge connection process, by performing smoothing processing, it becomes possible to adjust so as to approach the actual boundary.

[0107] (10) Further comprising a display control unit (for example, data processing unit 70) that superimposes and displays the boundary of the corneal layer determined by the determination unit on the tomographic image in an identifiable manner. The anterior eye analysis apparatus according to any one of (1) to (9), characterized in that. According to this configuration, the detected corneal layer structure can be easily grasped by the user of the ophthalmic system, and it becomes possible to promote the efficiency in diagnosis and the like.

[0108] (11) A derivation unit (for example, data processing unit 70) that derives the thickness of the corneal epithelium of the eye to be examined based on the boundary determined by the determination unit, A generation unit (for example, data processing unit 70) that generates a thickness map of the corneal epithelium of the eye to be examined using the thickness derived by the derivation unit, The anterior eye analysis apparatus according to any one of (1) to (9), further comprising: and characterized in that. According to this configuration, the thickness with respect to the detected corneal layer structure can be more visually expressed, and it becomes possible to improve the convenience for the user of the ophthalmic system.

[0109] (12) An acquisition step (for example, step S101) of acquiring a tomographic image of the anterior eye including the cornea of the eye to be examined formed by OCT measurement, A detection step (for example, step S201) of detecting a plurality of edges included in the tomographic image, A first connection step (for example, steps S203 and S205) of connecting edges based on a first connection condition for each of the plurality of edges, A selection step (for example, step S206) of selecting a first edge and a second edge based on the length from among the edges connected in the first connection step, A second bonding step (for example, step S212) of bonding between edges based on a second bonding condition with respect to each of the first edge and the second edge; A determination step (for example, step S213, step S215) of determining a boundary of a corneal layer of the tomographic image using the edges bonded in the second bonding step; An anterior segment analysis method, characterized by comprising: According to this configuration, appropriate segmentation can be performed on local unevenness of the layers constituting the cornea in the anterior segment. In particular, even when imaging of the anterior segment is unclear in OCT measurement, the uneven shape of Bowman's membrane can be accurately detected.

[0110] (13) A computer (for example, ophthalmic system 1) is caused to perform an acquisition step (for example, step S101) of acquiring a tomographic image of an anterior segment including a cornea of an eye to be examined formed by OCT measurement, a detection step (for example, step S201) of detecting a plurality of edges included in the tomographic image, a first bonding step (for example, step S203, step S205) of bonding between edges based on a first bonding condition for each of the plurality of edges, a selection step (for example, step S206) of selecting a first edge and a second edge based on length from among the edges bonded in the first bonding step, a second bonding step (for example, step S212) of bonding between edges based on a second bonding condition with respect to each of the first edge and the second edge, a determination step (for example, step S213, step S215) of determining a boundary of a corneal layer of the anterior segment using the edges bonded in the second bonding step, A program for causing the above to be executed. According to this configuration, appropriate segmentation can be performed on local unevenness of the layers constituting the cornea in the anterior segment. In particular, even when imaging of the anterior segment is unclear in OCT measurement, the uneven shape of Bowman's membrane can be accurately detected.

Explanation of Symbols

[0111] 1…Ophthalmic system 10…Measurement unit 20…Refraction measurement unit 30…OCT (Optical Coherence Tomography) unit 40…Light projection unit 50…Control processing unit 60…Image formation unit 70…Data processing unit 80…Control unit 90…Moving mechanism 100…Imaging unit 110…UI (User Interface) unit BS1, BS2…Beam splitter E…Eye to be examined Ef…Fundus Ec…Cornea

Claims

1. An acquisition unit that acquires a tomographic image of the anterior eye part including the cornea of the eye to be examined formed by OCT measurement; A detection unit that detects a plurality of edges included in the tomographic image; A first combining unit that combines edges based on a first combining condition for each of the plurality of edges; A selection unit that selects a first edge and a second edge based on length from among the edges combined by the first combining unit; A second combining unit that combines edges based on a second combining condition with each of the first edge and the second edge as a reference; A determination unit that determines the boundary of the corneal layer of the tomographic image using the edges combined by the second combining unit; An anterior eye part analysis device, characterized by comprising the above.

2. The detection unit: Identifies the anterior surface side boundary of the corneal epithelium in the tomographic image, And detects the plurality of edges for a predetermined range from the identified anterior surface side boundary. The anterior eye part analysis device according to claim 1, characterized by the above.

3. The tomographic image is divided into a first region that is a region on the corneal apex side of the eye to be examined and a second region that is a region on the scleral side of the cornea of the eye to be examined, The first combining unit performs processing on the first region, The second combining unit performs processing on the first region and the second region. The anterior eye part analysis device according to claim 1 or 2, characterized by the above.

4. The second combining unit makes the combining condition for combining edges in the first region different from the combining condition for combining edges in the second region. The anterior eye part analysis device according to claim 3, characterized by the above.

5. In the first region, when the first edge and the second edge overlap by a predetermined length or more in the width direction of the cornea, the second combining unit determines the longer one of the first edge and the second edge as the boundary of the corneal layer. The anterior eye part analysis device according to claim 3 or 4, characterized by the above.

6. In the first region, when the first edge and the second edge do not overlap in the width direction of the cornea, the second combining unit combines the first edge and the second edge and determines it as the boundary of the corneal layer. The anterior eye part analysis device according to any one of claims 3 to 5, characterized by the above.

7. When the first edge and the second edge do not overlap in the width direction of the cornea within a range defined based on the imaging conditions of the OCT measurement in the first region, the second coupling portion couples the first edge and the second edge to determine it as the boundary of the layers of the cornea. The anterior eye segment analysis apparatus according to claim 6, characterized in that.

8. The first coupling condition and the second coupling condition are different in at least one of the distance in the thickness direction of the cornea, the distance in the width direction of the cornea, the degree of overlap in the width direction of the cornea, and the edge strength when coupling the edges. The anterior eye segment analysis apparatus according to any one of claims 1 to 7, characterized in that.

9. The second coupling portion further performs a smoothing process on the coupled edges. The anterior eye segment analysis apparatus according to any one of claims 1 to 8, characterized in that.

10. The apparatus further includes a display control unit that superimposes and displays the boundary of the layers of the cornea determined by the determination unit on the tomographic image in an identifiable manner. The anterior eye segment analysis apparatus according to any one of claims 1 to 9, characterized in that.

11. A derivation unit that derives the thickness of the corneal epithelium of the eye to be examined based on the boundary determined by the determination unit, A generation unit that generates a thickness map of the corneal epithelium of the eye to be examined using the thickness derived by the derivation unit. The anterior eye segment analysis apparatus according to any one of claims 1 to 9, further comprising: and characterized in that.

12. An acquisition step of acquiring a tomographic image of the anterior eye segment including the cornea of the eye to be examined formed by OCT measurement, A detection step of detecting a plurality of edges included in the tomographic image, A first coupling step of coupling between the edges based on a first coupling condition for each of the plurality of edges, A selection step of selecting a first edge and a second edge based on the length from among the edges coupled in the first coupling step, A second coupling step of coupling between the edges based on a second coupling condition with each of the first edge and the second edge as a reference, A determination step of determining the boundary of the layers of the cornea of the tomographic image using the edges coupled in the second coupling step. An anterior eye segment analysis method, characterized by comprising:

13. In a computer, An acquisition step of acquiring a tomographic image of the anterior eye segment including the cornea of the eye to be examined formed by OCT measurement, A detection step of detecting a plurality of edges included in the tomographic image, For each of the plurality of edges, a first bonding step of bonding between the edges based on a first bonding condition; A selection step of selecting a first edge and a second edge based on the length from among the edges bonded in the first bonding step; A second bonding step of bonding between the edges based on a second bonding condition with each of the first edge and the second edge as a reference; A determination step of determining the boundary of the layer of the cornea of the anterior eye part using the edges bonded in the second bonding step; A program for causing the above to be executed.

Images