JP2018102757A - Ophthalmologic analyzer, ophthalmologic oct, and ophthalmologic analysis program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ophthalmologic analyzer capable of acquiring information useful for diagnostic imaging of a corner, an ophthalmologic OCT, and ophthalmologic analysis program.SOLUTION: An OCT apparatus acquires, by an ophthalmologic analysis program performed by a processor (a control part 70), polarization characteristic data representing polarization characteristics in a corner of an anterior eye of a subject's eye, the polarization characteristic data on the basis of light with a first polarization component split from return light of the light applied to the corner, and light with a second polarization component similarly split from the return light and having different polarization from that of the light with the first polarization component, and detects a feature part at the corner on the basis of the polarization characteristic data.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to an ophthalmologic analyzer, an ophthalmologic OCT, and an ophthalmologic analysis program for analyzing an anterior segment of an eye to be examined.

  In glaucoma diagnosis, a corner examination is considered essential. Conventionally, the corner angle inspection is performed by an examiner visually observing the corner angle through a corner mirror. In recent years, various apparatuses for photographing corners have been proposed (see, for example, Patent Document 1).

  In the corner examination, the examiner finds the findings based on various features such as cornea, Schwalbe line, trabecular meshwork, Schlemm's canal, pigmented part, scleral cape, ciliary zone, iris, etc. obtain.

International Publication No. 2015/180923

  In the image diagnosis, the application method of the image in which the corner is photographed has not been sufficiently studied yet.

  Moreover, when the intensity | strength OCT image of the anterior eye part was obtained, there existed a problem that the information of at least one part feature was not included in the image.

  The present disclosure has been made in view of at least one of the problems of the prior art, and provides an ophthalmic analysis apparatus, an ophthalmic OCT, and an ophthalmic analysis program that can obtain useful information in diagnostic imaging of a corner. This is a technical issue.

  In order to solve the above problems, the present disclosure discloses at least the following aspects.

  (1) That is, the ophthalmologic analyzer according to the first aspect of the present disclosure is polarization characteristic data indicating a polarization characteristic at a corner angle of the anterior ocular segment to be examined, and is a return light of the light irradiated to the corner angle. Polarization characteristic data based on the light of the first polarization component divided from the light and the light of the second polarization component which is divided from the return light and has a polarization different from that of the light of the first polarization component. The acquisition means to acquire, and the detection means to detect the characteristic part in the said corner based on the said polarization | polarized-light characteristic data are provided.

  (2) An ophthalmologic OCT according to the second aspect of the present disclosure has at least the ophthalmologic analyzer of (1), an optical scanner for scanning the light on the corner of the eye to be examined, reference light, and the corner A splitting unit that splits the light combined with the return light from the corner into light of the first polarization component and light of the second polarization component; a detector that receives the split light; The acquisition unit generates and acquires the polarization characteristic data based on an output signal from a detection signal.

  (3) The ophthalmic analysis program according to the third aspect of the present disclosure is polarization characteristic data indicating a polarization characteristic at a corner of the anterior ocular segment to be examined by being executed by a processor of the ophthalmic analysis apparatus, The first polarization component light divided from the return light of the light irradiated to the corner and the second polarization component divided from the return light and having a polarization different from that of the first polarization component light The ophthalmologic analyzer is caused to execute an acquisition step of acquiring polarization characteristic data based on the light and a detection step of detecting a feature portion at the corner based on the polarization characteristic data.

  According to the present disclosure, it is possible to obtain useful information in corner image diagnosis.

  Hereinafter, exemplary embodiments of the present disclosure will be described.

"Overview"
The ophthalmologic analyzer according to the embodiment may be used to detect a corner feature by processing polarization characteristic data at the corner of the eye to be examined. The ophthalmological analysis apparatus may include a detection unit for detecting the characteristic part. Moreover, you may have an acquisition part for acquiring polarization characteristic data.

  The ophthalmic analysis apparatus may be an apparatus integrated with the apparatus main body of the ophthalmologic photographing apparatus, or may be separate from the apparatus main body. The ophthalmologic photographing apparatus referred to here may be provided with an optical system for obtaining polarization characteristic data. The apparatus main body may be provided with a processor for controlling light projection / reception of light from the optical system and obtaining polarization characteristic data based on the light reception result. When the ophthalmologic analyzer is separate from the main body of the ophthalmologic photographing apparatus, a general-purpose personal computer may be used as the ophthalmologic analyzer. For example, a processor such as a CPU may be used as the acquisition unit and the detection unit. When the ophthalmic analysis program stored in a non-volatile storage medium such as a flash memory is executed by the processor of the ophthalmic analysis apparatus, the ophthalmic analysis apparatus can execute the following operations.

<Polarization characteristics data>
The polarization characteristic data is data indicating the polarization characteristic for each position of the corner angle in the eye to be examined. The polarization characteristic data in the corner angle may be an analysis result on the polarization characteristic, for example, information on birefringence in the corner area (birefringence information), information on polarization uniformity in the corner area (DOPU), It may be at least one of information on polarization axis rotation (Axis-Orientation) in a corner area. In addition, about the calculation method of such information, since a technique well-known to those skilled in the art is employable, description is abbreviate | omitted.

  The range in which the polarization characteristic is indicated in the polarization characteristic data may be the entire corner, but is not necessarily limited thereto. The polarization characteristic data may indicate a polarization characteristic for a corner area including at least a feature (detection target by the detection unit), or may indicate a wide range of polarization characteristics of an anterior segment including a corner angle. Alternatively, the polarization characteristics of the whole eye may be shown. The polarization characteristic data indicates the distribution of the deflection characteristics in the corner area (in other words, the deflection characteristics for each position in the corner area). That is, for example, when the optical system for obtaining the polarization characteristic data is a camera-type device, for example, the polarization characteristic for each pixel may be indicated by the polarization characteristic data. Further, when the optical system for obtaining the polarization characteristic data is a scanning type device, even if the polarization characteristic data indicates the polarization characteristic for each scan position or for each pixel, for example, Good.

  Polarization characteristic data can be obtained based on the result of receiving a plurality of divided lights by dividing a plurality of lights having different polarizations from the return light of the light irradiated to the corners. In the present embodiment, the plurality of lights divided from the return light may include at least the light of the first polarization component and the light of the second polarization component. The light of the first polarization component and the light of the second polarization component may have polarization components that are orthogonal to each other. In the present embodiment, the polarization characteristic data is generated based on the light of the first polarization component and the light of the second polarization component. For example, the polarization characteristic data may be generated by processing a first light reception signal based on the light of the first polarization component and a second light reception signal based on the light of the second polarization component.

  The polarization characteristic data may be data indicating the polarization characteristics of the cross section at the corner angle, or data indicating the polarization characteristics of the surface at the corner angle. Moreover, the data which show the polarization characteristic in the three-dimensional structure of a corner angle may be sufficient. When the polarization characteristics relating to the deeper part than the corner surface are required, the polarization OCT data may be used as the polarization characteristic data. Further, when the polarization characteristics regarding the surface of the corner angle are required, the polarization OCT data may be used as the polarization characteristic data, or the reflection image at the corner angle indicating the polarization characteristics may be used as the polarization characteristic data. Good.

  Note that the polarization OCT data may be acquired by PS-OCT. In this case, polarization characteristic data indicating a three-dimensional polarization characteristic at a corner angle can be obtained. For this reason, even if the characteristic portion exists in the tissue, detection can be performed based on the polarization characteristic data.

  In the present embodiment, when the return light from the corner is obtained, the light irradiated to the corner may be light having a known polarization.

<Obtaining polarization characteristics data>
The acquisition unit acquires the polarization characteristic data based on a corner imaging result obtained by the ophthalmologic imaging apparatus. When the ophthalmologic analyzer is the main body of the ophthalmologic imaging apparatus, the acquisition unit processes the light reception signal of the return light to generate polarization characteristic data and store (that is, acquire) the polarization characteristic data in the memory. The processing of the received light signal here may be processing of an analog signal output from the detector, or processing of data converted from the analog signal.

  When the ophthalmic analysis apparatus is separate from the apparatus main body of the ophthalmologic photographing apparatus, the acquisition unit stores polarization characteristic data generated in advance in the outside (for example, the apparatus main body of the ophthalmic photographing apparatus) in the memory of the ophthalmic analysis apparatus. By acquiring and storing, polarization characteristic data is acquired.

<Detection of features based on polarization characteristics data>
The detection unit detects a characteristic portion at the corner of the anterior eye based on the polarization characteristic data. In the following description, as an example, a case will be described in which a characteristic tissue included in the trabecular meshwork is detected as a characteristic portion based on polarization characteristic data.

  However, the tissue detected as the feature part does not necessarily need to be a tissue included in the trabecular meshwork, and a tissue other than the trabecular meshwork may be detected as the feature part at the corner. In this case, a tissue having a property different from that of the other part of the corner angle in one or more of various polarization characteristics such as refraction, polarization uniformity, polarization axis rotation, and the like can be detected as the characteristic portion. As a specific example of such a characteristic portion, a fibrous tissue at a corner may be used, or a tissue having a predetermined pigment at a corner may be used. Alternatively, a tissue having polarization characteristics may be excluded based on polarization characteristic data, and the remaining portion may be detected as a feature portion. For example, since Schlemm's tube is hollow, it is considered that a hollow portion having no polarization property can be detected by this method. Schlemm's tube can be detected, for example, based on polarized OCT data.

  Further, an artificial object existing in the eye to be examined may be detected as a characteristic object based on polarization characteristic data. The artificial object may be a living implant device such as a glaucoma implant.

  When a characteristic tissue contained in the trabecular meshwork is detected, the detection unit may detect using a difference in polarization delay amount from other tissues due to the birefringence of the trabecular meshwork. Good. In this case, the trabecular meshwork (fibrous tissue) is detected based on the polarization characteristic data including information on the polarization delay amount for each corner position.

  The characteristic tissue included in the trabecular meshwork detected as the feature does not necessarily need to be the trabecular meshwork itself (fibrous tissue itself). For example, a pigmentation part in the trabecular meshwork may be detected as a characteristic part. In the pigment deposition part, depolarization (polarization scramble) occurs. Thereby, the pigmentation part can be detected characteristically based on depolarization. Further, since depolarization has a correlation with polarization uniformity (DOPU), the pigmentation portion can be detected characteristically based on the polarization uniformity. Therefore, in the present embodiment, the detection unit may detect the pigment deposition unit based on polarization characteristic data including information related to depolarization or polarization uniformity for each corner position. Of course, the characteristic tissue contained in the trabecular meshwork may be a fibrous tissue in the trabecular meshwork and a tissue other than the pigmented portion.

  As described above, the detection unit can detect at least one or both of the fibrous tissue in the trabecular meshwork and the pigmentation portion based on the polarization characteristic data.

  The ophthalmic analysis apparatus may further include a detection region setting unit for setting a region (ROI) in which the characteristic portion is detected by the detection unit. In this case, the area setting unit sets a detection area in a part of the corner image captured in the imaging range corresponding to the polarization characteristic data.

  The detection area may be set manually based on the setting operation of the examiner. In this case, an instruction for specifying the detection area is input to the operation unit on the corner image displayed on the monitor. Thus, the characteristic portion is detected from the polarization characteristic data in the range corresponding to the detection region on the corner image.

<Dye detection based on spectral waveform of return light>
Note that the pigment deposit portion does not necessarily need to be detected based on the polarization characteristic data, and may be detected based on the spectrum waveform in the return light from the corner. The spectrum waveform may be acquired for each corner position. Note that the return light that is the basis of the polarization characteristic data may also be used in the case of obtaining a spectrum waveform.

  The detection unit detects the pigmentation part based on the spectral waveform in the return light in consideration of the absorption band in the pigmentation part. In the trabecular meshwork, the absorption characteristics at each position differ depending on the presence or absence of pigmentation. For this reason, it is considered that the spectrum waveform at each position differs depending on whether or not the dye is absorbed.

<Second detection unit>
The ophthalmic analysis apparatus may further include a second detection unit. A 2nd detection part detects the blood vessel (for example, new blood vessel) in a corner based on the return light from a corner. The return light used for blood vessel detection may be return light used for feature detection, or may be light received independently of the return light used for feature detection. It is known that when a new blood vessel that progresses from the pupil edge and the corner to the entire iris is formed, the corner is blocked and the intraocular pressure increases. For this reason, it is useful for early glaucoma treatment that a new blood vessel detects by a 2nd detection part.

  Here, for example, a blood vessel detection algorithm method based on OCT angiography may be applied to the second detection unit. In this case, the OCT data is acquired a plurality of times at different timings in the detection range of the characteristic portion, and the blood vessels in the detection range are detected based on the difference data between the OCT data obtained at different timings.

  In addition, the present invention is not necessarily limited to OCT angiography, and various blood vessel detection methods may be applied to the second detection unit. For example, a technique for detecting blood vessels may be applied by paying attention to the difference in luminance between the blood vessel portion and the other in the front image of the tissue of the eye to be examined. A 2nd detection part detects a blood vessel from the front image in the detection range of a characteristic part. In addition, since the blood vessel detection method at this time is well known to those skilled in the art, detailed description thereof is omitted.

  The OCT data or the front image used for blood vessel detection in the second detection unit may be acquired and photographed via an optical system for acquiring polarization characteristic data, or may be acquired by another optical system. It may be acquired and photographed.

<Display of detection results>
The ophthalmological analysis apparatus may further include a display control unit that causes the feature unit detected by the detection unit to be displayed on the monitor in association with the corner image together with the corner image. The corner image is taken by, for example, an ophthalmologic photographing apparatus. The corner image may be a front image showing the surface of the corner viewed from one direction, a tomographic image showing the cross-sectional shape of the corner, or the structure of the corner 3 A three-dimensional image shown in a dimension may be used. For example, the display control unit superimposes a graphic indicating the feature on a corner image and displays the graphic on the monitor. The examiner can grasp the state of the corner based on the corner angle image displayed on the monitor and the detection result of the characteristic portion. For example, when a trabecular meshwork is detected as a feature, the degree of occlusion of a corner can be grasped. Moreover, when the pigmentation part of the trabecular meshwork is detected, the degree of pigmentation can be grasped.

  In addition, when the position of the blood vessel is detected by the second detection unit, the display control unit may further display the blood vessel in association with the corner image.

  Note that the feature or blood vessel may be associated with the corner image by superimposing a graphic representing the feature or blood vessel on the corner image. The graphic representing the characteristic part or the blood vessel may be hatched or color-coded. In addition, when the polarization characteristic data can be expressed as an image different from the corner angle image, the feature portion is cut out from the image related to the polarization characteristic data and superimposed on the corner angle image, so that A feature portion may be associated with an image. Further, when an angiographic image is acquired, a blood vessel may be associated with the corner image by combining the angiographic image with the corner image.

  The ophthalmologic analyzer may have an image acquisition unit in order to acquire a corner image. The corner image acquired by the image acquisition unit may be an image captured in the imaging range corresponding to the polarization characteristic data. The corner image may be an image photographed through the optical system of the ophthalmologic photographing apparatus.

<Utilization of detection results other than display>
The ophthalmologic analyzer may measure the size or density of the detected feature based on the detection result of the feature. For example, when a trabecular meshwork is detected as a feature, the size of the trabecular meshwork may be measured. Further, the density of fibrous tissue in the trabecular meshwork may be measured. Further, the density and total amount of the dye may be measured based on the detection result. Each of these pieces of information is considered useful for evaluating the difficulty of draining aqueous humor in the trabecular meshwork.

  For example, when a Schlemm's tube is detected as a feature, at least whether or not the hollow portion of the Schlemm's tube is clogged may be detected based on the detection result of the feature. Each information may be displayed on a monitor. Moreover, based on at least a part of each information, an evaluation index for the difficulty of draining aqueous humor may be generated, and the evaluation index may be displayed on the monitor.

<Ophthalmologic imaging device>
Here, an ophthalmologic photographing apparatus having an optical system for obtaining polarization characteristic data will be described. The optical system of the ophthalmologic photographing apparatus irradiates light at the corner of the eye to be examined, and at least divides the return light from the corner into light of the first polarization component and light of the second polarization component. The detected light is received by a detector. In this case, the acquisition unit generates and acquires polarization characteristic data based on the light reception signal from the detector based on the light of the first polarization component and the light reception signal from the detector based on the light of the second polarization component. To do.

  The optical system for obtaining the polarization characteristic data may be a scanning optical system (scanning optical system). Further, it may be a camera type optical system. The scanning optical system scans light at corners by an optical scanner and receives return light from each position in the scanning range by a detector. On the other hand, a camera-type optical system has a two-dimensional light receiving element as a detector, irradiates light over the entire polarization characteristic data acquisition range, and receives the return light by the two-dimensional light receiving element. The light irradiated from the optical system for obtaining the polarization characteristic data to the eye to be examined may be light having a predetermined polarization component. In this case, the optical system for obtaining the polarization characteristic data may have a polarizer (polarizer) for setting the light irradiated to the eye to be examined to a predetermined polarization. The polarizer may be, for example, a polarizing filter, a pressurized fiber, or another member.

  When the ophthalmologic photographing apparatus includes a scanning optical system, the scanning optical system includes at least an optical scanner, a dividing unit, and a detector. The optical scanner is driven to scan light over the corner of the eye to be examined. The return light from the corner is divided by the dividing unit into a plurality of lights having different polarizations. The dividing unit may divide a plurality of lights having different polarizations from the combined light at the same time, or may divide the lights for each direction of polarization by shifting the time. In the case where a plurality of lights having different polarizations are simultaneously divided by the dividing unit, a number of detectors corresponding to each of the divided lights may be provided. On the other hand, when a plurality of lights having different polarizations from the combined light are divided at different times, the plurality of lights may be detected by one detector.

  The scanning optical system may be a PS-OCT scanning optical system. In this case, the return light is combined with the reference light and then divided by the dividing unit. That is, the return light is divided into a plurality of lights having different polarizations while interfering with the reference light.

  The ophthalmologic photographing apparatus may perform light projection and reception along an optical axis inclined with respect to the visual axis (fixation optical axis).

  When the polarization characteristic data is obtained through the scanning optical system, the scanning optical system may have the following objective optical system. That is, the objective optical system forms a turning point of light irradiated to the corner between the cornea of the eye to be examined and the scanning optical system. The turning point becomes the turning center when the light irradiated to the corner is turned along with the operation of the optical scanner. The objective optical system may be a reflective optical system that bends light to a turning point by reflection, or may be a refractive optical system that bends light to a turning point by refraction.

  The objective optical system may be compatible with non-contact shooting or may be compatible with shooting in a compressed state. In the case of photographing in a compressed state, a contact portion for contacting the eye to be examined and pressing the eye to be examined is provided at the tip of the objective optical system.

  The light incident on the corner of the eye to be examined may be infrared light. Of these, light having a center wavelength λc of 1 μm or more is preferable. In this case, it has good permeability to water, which is the main scatterer in the anterior segment. The scanning optical system may include a light source having light having a center wavelength λc of 1 μm or more. However, the range of the center wavelength λc of the light emitted to the corner of the eye to be examined is not necessarily limited to those exemplified above, and other values may be applied.

  In addition, since ophthalmic OCT normally uses infrared light as measurement light, it is difficult to obtain information on pigments. However, when processing polarization characteristic data, the pigmentation part can be easily detected even when the return light of infrared light is obtained.

<Example>
Hereinafter, embodiments will be described with reference to the drawings. In the present embodiment, a case where an ophthalmic analysis apparatus is applied to the apparatus main body of the OCT apparatus 1 (ophthalmic imaging apparatus) will be described. The apparatus main body includes at least the control unit 70.

  The OCT apparatus 1 shown in FIG. 1 is PS-OCT, and acquires OCT image data indicating polarization characteristics. In FIG. 1, the test object is a corner of the eye.

  The OCT apparatus 1 includes a control unit 70, and further includes an interference optical system 100 as a scanning optical system. The control unit 70 is realized by, for example, a general CPU (Central Processing Unit) 71, a ROM 72, a RAM 73, and the like. The ROM 72 includes, for example, various programs such as a program for controlling the operation of the OCT apparatus 1 to obtain OCT image data, an analysis program for analyzing the OCT image data, and fixed value data such as various parameters. It may be stored. The RAM 73 temporarily stores various information, for example.

  As shown in FIG. 1, the OCT apparatus 1 further includes, for example, a storage unit (for example, a non-volatile memory) 74, a monitor 75, and the like, and each is electrically connected to the control unit 70. The storage unit 74 is, for example, a non-transitory storage medium that can retain stored contents even when power supply is interrupted. For example, a hard disk drive, flash ROM, removable USB memory, or the like can be used as the storage unit 74.

  The monitor 75 may be a display mounted on the main body of the apparatus 1 or a display connected to the main body. For example, a display of a personal computer (hereinafter referred to as “PC”) may be used. The monitor 75 displays, for example, the image data acquired by the OCT apparatus 1 or the processing result of the image data.

  The OCT apparatus 1 has a wavelength sweep type OCT (SS-OCT; Swept Source-OCT) as a basic configuration. That is, the OCT apparatus 1 further includes a wavelength tunable light source 102 (hereinafter simply referred to as “light source 102”). In addition, the OCT apparatus 1 is provided with a memory 72, a monitor 75, a front image observation system (not shown), a fixation target projection system, and the like. The variable wavelength light source 102 and the interference optical system 100 are connected to the control unit 70 and operate based on a control signal from the control unit 70.

  The light source 102 is a wavelength tunable light source (wavelength scanning light source) that changes the emission wavelength at high speed in time. The light source 102 includes, for example, a laser medium, a resonator, and a wavelength selection filter. Examples of the wavelength selection filter include a combination of a diffraction grating and a polygon mirror, and a filter using a Fabry-Perot etalon.

  In this embodiment, a TUNABLE LASER manufactured by AXUN is used as a light source having a short instantaneous emission line width and a short resonator length (for example, λc = 1060 nm, Δλ = 110 nm, δλ = 0.055 nm, resonator length to 14 mm). Such a wavelength tunable light source is described in, for example, US Publication No. 2009/0059971.

  The interference optical system 100 includes at least the optical scanner 108, a polarization splitting unit (hereinafter abbreviated as “dividing unit”) 360 and 365, and a detector 120 as a scanning optical system. The interference optical system 100 may include a coupler (splitter) 104, an optical delay path 300, a circulator 103, a measurement optical system 106, and a reference optical system 110. Further, fibers 105, 119 and the like may be provided as the light guide path of each part.

  The coupler (splitter) 104 is used as an optical splitter, and divides the light emitted from the light source 102 into measurement light (measurement light) and reference light. The circulator 103 guides the light from the coupler 104 to the optical fiber 105 and guides the light from the optical fiber 105 to the optical fiber 119. The circulator 103 may be a coupler.

  The interference optical system 100 guides the measurement light to the corner E of the eye E by the measurement optical system 106. The interference optical system 100 guides reference light to the reference optical system 110. The interference optical system 100 causes the detector (light receiving element) 120 to receive the interference signal light acquired by the interference between the measurement light reflected by the corner angle Ea and the reference light.

  In the measurement optical system 106, an optical delay path 300, an optical fiber 105, an optical scanner 108, and an objective optical system are sequentially provided.

  The optical delay path 300 includes a reference optical path 300a and a bypass optical path 300b, and is provided to generate at least two lights having optical path length differences. For example, when the optical delay path 300 is arranged in the measurement optical path, the measurement light is formed as at least two measurement lights having optical path length differences by the reference optical path 300a and the bypass optical path 300b formed in the optical delay path 300. The Since the bypass optical path 300b has a longer optical path length than the reference optical path 300a, the measurement light passing through the bypass optical path 300b has an optical delay (optical path length difference) with respect to the measurement light passing through the reference optical path. In this way, a plurality of measurement lights having optical path length differences are irradiated to the same position of the test object.

  The optical delay path 300 includes, for example, a first polarization beam splitter 302, a first light reflection member 304, a second light reflection member 306, and a second polarization beam splitter 308, and divides the measurement light into two optical paths, The optical path length of the other measurement light is delayed with respect to the measurement light. The first polarization beam splitter 302 divides the measurement light from the light source 102 into a reference optical path 300a (first measurement optical path) and a bypass optical path 300b (second measurement optical path). The second polarization beam splitter 308 combines the reference optical path 300a and the bypass optical path 300b.

  As the first light reflecting member 304 and the second reflecting member 306, for example, an optical member such as a total reflection mirror or a prism is used. The optical members forming the optical delay path 300 may be optical arrangements separated from each other as shown in FIG. 1, or may be an optical arrangement integrated by a prism or the like.

  The first polarization beam splitter 302 has a characteristic of dividing light from the light source 102 into a vertical polarization component and a horizontal polarization component, transmitting light of one polarization component, and reflecting light of the other polarization component. The first light reflecting member 304 and the second reflecting member 306 reflect one of the lights divided by the first polarization beam splitter 302 and return it to the light coupling member 308. The second polarization beam splitter 308 has a characteristic of combining light split into vertical polarization and horizontal polarization. After being combined by the second polarizing beam splitter 308, as a result, two measurement lights whose polarization components are orthogonal to each other are irradiated to the eye to be examined (both polarization components are changed by the influence of the optical fiber 105 and the like). However, the relationship that the polarization components are orthogonal to each other does not change).

  As described above, the optical delay path 300 generates two measurement lights whose polarization components are orthogonal to each other and have an optical path length difference. The two measurement lights are directed to the optical scanner 108 via the circulator 103 and the optical fiber 105. The reflection directions of the two measurement lights are changed by the optical scanner 108. The light deflected by the optical scanner 108 becomes a parallel beam by the objective lens system, enters the eye E, and enters the corner Ea. The two measurement lights are irradiated to the same position on the corner angle Ea.

  The optical scanner 108 scans the measurement light in the XY direction (transverse direction) on the corner angle Ea. The optical scanner 108 is arranged at a position substantially conjugate with the pupil. The optical scanner 108 is, for example, two galvanometer mirrors, and the reflection angle thereof is arbitrarily adjusted by a driving mechanism.

  The reflection (advance) direction of the light beam emitted from the light source 102 is changed and scanned in an arbitrary direction on the corner. As the optical scanner 108, a reflection mirror (galvano mirror, polygon mirror, resonant scanner), an acousto-optic element (AOM) that changes the traveling (deflection) direction of light, or the like is used.

  The control unit 70 controls the driving of the optical scanner 108 to scan the measurement light in a direction (transverse direction) perpendicular to the depth direction of the corner angle Ea. Backscattered light (reflected light) from the corner angle Ea of each measurement light reaches the beam splitter 350 through the objective lens system, the optical scanner 108, the optical fiber 105, the circulator 103, and the optical fiber 119. Then, the backscattered light is combined with the reference light by the beam splitter 350 and interferes therewith.

  The reference optical system 110 generates reference light that is combined with reflected light acquired by reflection of measurement light at the corner angle Ea. The reference optical system 110 may be a Michelson type or a Mach-Zehnder type. The reference optical system 110 is formed by a transmission optical system (for example, an optical fiber), and guides the light from the coupler 104 to the detector 120 by transmitting the light without returning. The reference optical system 110 may be formed by, for example, a reflection optical system (for example, a reference mirror), and may be returned to the coupler 104 by reflecting light from the coupler 104 by the reflection optical system and guided to the detector 120.

  This apparatus moves at least a part of the optical member arranged in the interference optical system 100 in the optical axis direction in order to adjust the optical path length difference between the measurement light and the reference light. For example, the reference optical system 110 has a configuration that adjusts the optical path length difference between the measurement light and the reference light by moving an optical member in the reference light path. A configuration for changing the optical path length difference may be arranged in the measurement optical path. An optical member (for example, an end of an optical fiber) disposed in the measurement optical path is moved in the optical axis direction.

  The beam splitter 350 splits the interference signal light into two. A polarizing beam splitter 360 is disposed on one of the optical paths divided by the beam splitter 350, and a polarizing beam splitter 365 is disposed on the other. The polarization beam splitters 360 and 365 divide the incident interference signal light into polarization components (vertical polarization component and horizontal polarization component) orthogonal to each other. That is, in the present embodiment, the polarization beam splitters 360 and 365 are used as a splitting unit that splits the return light from the corner into the light of the first polarization component and the light of the second polarization component.

  The detector 120 has a vertical polarization detector 120V and a horizontal polarization detector 120H. Thereby, the vertical polarization component and the horizontal polarization component in the spectrum signal can be detected separately.

  Each of the vertical polarization detector 120V and the horizontal polarization detector 120H includes a balanced detector including a first light receiving element (120Va, 120Ha) and a second light receiving element (120Vb, 120Hb). It is advantageous. The detector 120 (balanced detector) obtains the difference between the interference signal from the first light receiving element and the interference signal from the second light receiving element, and reduces unnecessary noise included in the interference signal. Each light receiving element is a point sensor having only one light receiving portion, and for example, an avalanche photodiode is used.

  The vertical polarization detector 120V performs balanced detection of the vertical polarization components divided by the polarization beam splitters 360 and 365 using the first light receiving element 120Va and the second light receiving element 120Vb. The horizontal polarization detector 120H performs balanced detection on the horizontal polarization components divided by the polarization beam splitters 360 and 365 by the first light receiving element 120Ha and the second light receiving element 120Hb.

  The interference signal light received by the vertical polarization detector 120V and the horizontal polarization detector 120H includes interference signal light corresponding to two measurement lights whose polarization components are orthogonal to each other and have optical path length differences.

  When the emission wavelength is changed by the light source 102, the corresponding interference signal light is received by the detector 120, and as a result, detected by the detector 120 as a spectrum signal. The control unit 70 obtains a trigger signal from the light source 102 and controls the spectrum signal to be acquired and the optical scanner 108.

  Each spectrum signal detected by the vertical polarization detector 120V and the horizontal polarization detector 120H is a first spectrum formed based on the measurement light having the vertical polarization component of the two measurement lights irradiated on the test object. And a second spectrum signal formed based on the measurement light having a horizontal polarization component. Since the first spectrum signal and the second spectrum signal have an optical path length difference, the density of interference fringes formed by the spectrum differs.

  The control unit 70 processes two spectrum signals having different polarization components, and obtains depth information DV and DH regarding the polarization components orthogonal to each other.

  The controller 70 obtains the vertical depth information DV by processing the spectrum signal having the vertical polarization component detected by the vertical polarization detector 120V. The vertical depth information DV includes first vertical depth information DV1 corresponding to the first spectrum signal and second vertical depth information DV2 corresponding to the second spectrum signal. The first vertical depth information DV1 is depth information formed based on one measurement light in the measurement light in which the polarization components are orthogonal to each other, and the second vertical depth information DV2 is a measurement in which the polarization components are orthogonal to each other. It is depth information formed based on the other measurement light in the light.

  The controller 70 processes the spectrum signal having the horizontal polarization component detected by the horizontal polarization detector 120H to obtain horizontal depth information DH. The horizontal depth information DH includes first horizontal depth information DH1 corresponding to the first spectrum signal and second horizontal depth information DH2 corresponding to the second spectrum signal. The first horizontal depth information DH1 is depth information formed based on one measurement light in the measurement light in which the polarization components are orthogonal to each other, and the second horizontal depth information DH2 is a measurement in which the polarization components are orthogonal to each other. It is depth information formed based on the other measurement light in the light.

<Acquisition of tomographic images>
The control unit 70 controls the driving of the optical scanner 108 and scans the measurement light in the transverse direction on the corner angle Ea. The control unit 70 forms a corner tomographic image (B scan) by sequentially arranging the depth information at each scanning position.

  The control unit 70 obtains tomographic image data TV and TH related to the orthogonal polarization components by arranging the depth information DV and DH related to the orthogonal polarization components in the scanning direction. The tomographic image data TV, TH includes a plurality of tomographic images having corner angles Ea separated in the depth direction. The tomographic image data is formed by obtaining the absolute value of the real / imaginary component in each depth information. Each tomographic image is a tomographic image acquired with respect to the same scanning position on the corner angle Ea.

  The tomographic image data TV includes a first vertical tomographic image TV1 based on the first vertical depth information DV1 and a second vertical tomographic image TV2 based on the second vertical depth information DV2. The tomographic image data TH includes a first horizontal tomographic image TH1 based on the first horizontal depth information DH1 and a second horizontal tomographic image TH2 based on the second horizontal depth information DH2.

  The control unit 70 selects any one of the first vertical tomographic image TV1, the second vertical tomographic image TV2, the first horizontal tomographic image TH1, and the second horizontal tomographic image TH2 from the tomographic image data TV and TH acquired as described above. Extraction is performed, and a tomographic image is displayed on the screen of the monitor 75. The control unit 70 may continuously acquire the tomographic image data TV and TH and display a moving image tomographic image.

<Polarization detection>
The controller 70 obtains the birefringence characteristic of the corner angle Ea using the vertical depth information DV and the horizontal depth information DH. Real part information and imaginary part information in each depth information after Fourier analysis of the spectrum signal is used.

  The control unit 70 obtains the first vertical depth information DV1 from the vertical depth information DV, and obtains the first horizontal depth information DH1 from the horizontal depth information DH. The controller 70 obtains the first polarization state based on the first vertical depth information DV1 and the first horizontal depth information DH1 whose polarization components are orthogonal to each other.

  The control unit 70 obtains the second vertical depth information DV2 from the vertical depth information DV and obtains the second horizontal depth information DH2 from the horizontal depth information DH. The controller 70 obtains the second polarization state based on the second vertical depth information DV2 and the second horizontal depth information DH2 whose polarization components are orthogonal to each other.

  Based on the first polarization state and the second polarization state, the control unit 70 obtains the birefringence characteristic at a position where the corner angle Ea is present with reference to the surface of the corner angle Ea. The control unit 70 obtains the polarization depth information indicating the birefringence characteristic distribution of the corner angle Ea with respect to the depth direction by obtaining the birefringence characteristic with respect to the depth direction.

  The control unit 70 obtains a birefringence distribution (for example, a polarization depth information image) of the corner angle Ea at a certain cut surface by arranging the polarization depth information at each position with respect to the scanning direction. The control unit 70 may display the obtained birefringence distribution on the monitor 75.

  The control unit 70 may obtain three-dimensional OCT data by controlling the driving of the optical scanner 108 and scanning the measurement light two-dimensionally at the corner Ea. The controller 70 obtains a map indicating a two-dimensional birefringence distribution on the corner angle Ea by obtaining the polarization depth information at each position. The control unit 70 may display the obtained map on the monitor 75. For a specific method for obtaining the polarization characteristics, refer to, for example, Japanese Patent Application Laid-Open No. 2013-148482.

  Hereinafter, an example of the polarization characteristic data acquisition method described in the above embodiment will be described.

  Assume that PS-OCT data is obtained. This is, for example, four three-dimensional OCT tomograms corresponding to two types of polarized light irradiated to the eye to be examined and two polarized lights when scattered back from the eye to be examined (for example, the first vertical tomographic image TV1 described above). 3D tomogram, 3D tomogram of the second vertical tomogram TV2, 3D tomogram of the first horizontal tomogram TH1, 3D tomogram of the second horizontal tomogram TH2). These are called Jones matrix OCT tomograms. Note that an intensity OCT tomogram (see FIG. 3) may be acquired by performing a conversion process from a Jones matrix OCT tomogram to an intensity OCT image.

  From the four Jones matrix OCT tomograms, for example, intensity OCT tomogram, polarization uniformity (DOPU) tomogram, birefringence (Retardation or Birefringence) tomogram, polarization axis rotation (Axis-Orientation) tomogram A quantity such as an image is required. Further, depolarization may be detected by Mueller matrix conversion. That is, a depolarization tomographic image may be acquired based on PS-OCT data.

  By analyzing the Jones matrix OCT tomogram, the feature at the corner is identified. This can be done by the following method.

  First, segmentation by image processing is performed on the Jones matrix OCT tomogram, and each tissue is separated. In the segmentation, various signal distributions obtained from the above-described Jones matrix OCT tomogram may be used.

  Here, for example, the trabecular meshwork is a fibrous tissue and has a relatively large birefringence. More specifically, the trabecular meshwork has a large birefringence relative to the cornea, also known as a birefringent tissue. Therefore, it is considered that the trabecular meshwork is characteristically detected by processing the birefringence tomographic image. For example, the trabecular meshwork can be specified by performing binarization processing on each pixel of the birefringent tomographic image (see FIG. 4). The binarization threshold at this time is desirably a value that distinguishes the cornea from the trabecular meshwork.

  As shown in FIG. 4, in the birefringent tomographic image, an artifact occurs in the iris Ei. However, this artifact is clearly different in position from the trabecular meshwork, for example, and can be easily distinguished.

  In addition, in the pigmented part of the trabecular meshwork, the polarization state is scrambled by the pigment (mainly melanin). For this reason, it is considered that the pigmentation part in the trabecular meshwork is characteristically detected by processing the depolarized tomogram or the DOPU tomogram. For example, the pigmentation part can be specified by performing binarization processing on each pixel of the depolarized tomographic image.

  In addition, the pigmentation part does not necessarily need to be detected based on the Jones matrix OCT tomogram. For example, the control unit 70 may detect the pigment deposition unit based on the spectrum waveform in the return light from the corner of the measurement light in consideration of the absorption band in the pigment deposition unit. The return light at this time may be light combined with the reference light, and is further divided from the combined light (specifically, the light of the first polarization component or the first light 2 light components). The control unit 70 can detect the pigmentation portion based on the spectrum signal output from the detector 120. As shown in FIG. 2, for example, in the wavelength region of 1 μm or more, absorption by melanin, which is the main pigment in the pigment deposition portion, decreases toward the longer wavelength side, whereas protein absorption is substantially flat. For this reason, it is considered that in the region where absorption by melanin is confirmed, a spectrum waveform having a lower intensity on the longer wavelength side is confirmed compared to other regions.

  Here, a desired region in the OCT tomogram can be extracted by so-called band-pass filter processing, and information on the spectrum waveform due to reflection / scattering from the extracted region can be obtained. Thereby, for example, information on the spectral waveform at each position in the trabecular meshwork detected based on the birefringence tomographic image may be obtained. The spectrum waveform may be acquired for each position of the corner angle Ea as an envelope of the spectrum signal output from the detector. The envelope may be obtained as an absolute value of a complex OCT signal obtained by Fourier analysis of the spectrum signal.

  The control unit 70 obtains, for each position, the amplitude change rate in the wavelength region corresponding to the pigment deposition unit and the wavelength region before and after the spectral waveform, and when the amplitude change rate exceeding the threshold is confirmed. Alternatively, it may be estimated that a pigmentation portion exists at a position corresponding to the spectrum waveform. Further, the region where the pigmentation portion is detected is divided into a plurality of small regions, and for each divided region, the dispersion of the spectrum waveform (for example, the dispersion of the evaluation value of the spectrum waveform) is obtained, and the pigmentation portion is You may detect based on dispersion | distribution. That is, it is considered that as the pigmentation increases, the variation in the spectrum waveform increases. In addition, dispersion | distribution may be compared with an envelope and may be compared for every wavelength.

  The control unit 70 may further acquire blood vessel information indicating the blood vessel position in the imaging range corresponding to the polarization characteristic data. In order to obtain blood vessel information, the control unit 70 may generate an angiographic image based on OCT data in the imaging range corresponding to the polarization characteristic data. The OCT data at this time may be converted from PS-OCT data. The angiographic image may be an image obtained by contrasting the blood vessel position obtained by detecting the movement of blood. The angiographic image may be acquired by processing at least two OCT data in an imaging range corresponding to the polarization characteristic data. Here, at least two OCT data are acquired at different timings. For example, an angiographic image is generated based on the phase difference between the complex OCT signals in the two OCT data, the vector difference between the complex OCT signals, the information obtained by multiplying the phase difference between the complex OCT signals and the vector difference, and the like. In the present embodiment, the control unit 70 only needs to obtain information indicating the blood vessel position in the imaging range corresponding to the polarization characteristic data, and does not necessarily generate an angiographic image.

  The control unit 70 displays the detected characteristic portion on the monitor 75 in association with the corner image together with the corner image. The corner image may be, for example, an intensity OCT image obtained based on polarization OCT data. The intensity OCT image may be a tomographic image at a corner, or may be a three-dimensional tomographic image formed by arranging cross-sectional images obtained by different scanning lines in the sub-scanning direction. The tomographic image may be an En-face image visualized in the front direction.

  First, a display example of a tomographic image using an intensity OCT image will be described with reference to FIGS. In the tomographic image, as shown in FIG. 3, tissues such as cornea Ec, sclera Es, corner angle Ea, and iris Ei can be depicted. There is tissue such as trabecular meshwork near the boundary of the sclera with the cornea. For example, whether or not a corner blockage has progressed to this point is one measure for obtaining a corner finding. It becomes. However, in the intensity OCT image, the trabecular meshwork is hard to be distinguished from other tissues.

  Therefore, for example, the control unit 70 combines the binarized birefringence tomographic image (see FIG. 4) with the intensity OCT image, thereby converting the graphic representing the trabecular meshwork Gt into the tomographic image based on the intensity OCT image. You may superimpose on it. Then, as shown in FIG. 5, the composite image may be displayed on the monitor 75. Alternatively, a binarized DOPU tomogram (not shown) may be combined with an OCT image so that a graphic representing the pigmented portion Gc may be superimposed on the tomographic image based on the intensity OCT image. By displaying the composite image, the examiner can easily grasp whether or not the blockage has advanced to the trabecular meshwork Gt. Furthermore, the degree of pigmentation that makes it difficult to obtain information because the measurement light has an infrared wavelength can be confirmed by superimposing the pigment deposition part Gc. Further, the angle of the corner can be grasped based on the tomographic image. That is, it is possible to grasp the state of the corner blockage. Note that the control unit 70 may display information indicating the angle of the corner on the monitor 75.

  Next, a display example of an En-face image using an intensity OCT image will be described with reference to FIG. FIG. 6 is an En-face image when the corner is viewed from the direction of arrow I in FIG. In such an En-face image, the corner angle can be observed at an angle closer to the visual observation with a corner mirror. Also in this case, by displaying the graphic representing the trabecular meshwork Gt and the pigment deposition part Gc in a superimposed manner, it is possible to observe a characteristic part that is difficult to describe in the En-face image based on the intensity OCT image.

  Furthermore, if the position of the blood vessel is detected, the control unit 70 may display the blood vessel superimposed on these corner images. Thereby, the examiner can be made aware of whether or not there is a new blood vessel at the corner.

Here, the intensity OCT image has been described as being displayed as a corner image, but polarized OCT such as a birefringence OCT image and a DOPUOCT image may be displayed on the monitor 75. In this case, on the polarization OCT, there is a contrast between the feature portion and the other portions, and it may be possible to confirm the feature portion. However, by further highlighting the feature portion, the distribution of the feature portion at the corners is increased. It may be expressed clearly. Although the present disclosure has been described based on the embodiments, the present disclosure is not limited to the above-described embodiments, and various modifications can be made.

It is a figure which shows an example of the OCT apparatus 1 which concerns on an Example. It is the figure which showed the absorption coefficient of melanin and protein. It is a figure which shows an example of an intensity | strength OCT tomogram. It is a figure which shows an example of a birefringent OCT tomogram. It is a figure which shows an example of the synthesized image which synthesize | combined at least the intensity | strength OCT tomogram and the birefringent OCT tomogram. It is a figure which shows an example of an En-face image.

1 OCT apparatus 70 Control unit 75 Monitor

Claims (18)

Polarization characteristic data indicating polarization characteristics at a corner angle of the anterior segment of the eye to be inspected, the first polarization component light divided from the return light of the light irradiated to the corner angle and the return light. And an acquisition means for acquiring polarization characteristic data based on the light of the second polarization component different in polarization from the light of the first polarization component;
An ophthalmologic analyzer comprising: detecting means for detecting a characteristic portion at the corner based on the polarization characteristic data.   The ophthalmic analysis apparatus according to claim 1, wherein the detection unit detects a characteristic tissue included in the trabecular meshwork as the characteristic portion based on the polarization characteristic data. The image acquisition means further acquires an image of the corner shot in the shooting range corresponding to the polarization characteristic data,
The ophthalmic analysis apparatus according to claim 1, further comprising display control means for displaying the corner image on a monitor and displaying the detected characteristic portion in association with the corner image. The image acquisition means further acquires an image of the corner shot in the shooting range corresponding to the polarization characteristic data,
A detection area setting means for setting a detection area where the characteristic part is detected to a part of the image of the corner;
The ophthalmic analysis apparatus according to claim 1, wherein the detection unit detects the characteristic portion in the detection region based on the polarization characteristic data corresponding to the detection region.   The detection area setting means displays the corner image on a monitor and determines the detection area based on an operator's operation for designating the detection area with respect to the corner image on the monitor. The ophthalmic analysis apparatus according to claim 4, wherein The polarization characteristic data includes information on a polarization delay between the light of the first polarization component and the light of the second polarization component at the corner,
The ophthalmologic analyzer according to claim 1, wherein the detection unit detects a trabecular meshwork as the feature based on the polarization characteristic data.   The ophthalmic analysis apparatus according to claim 6, wherein the detection unit further detects a pigmentation portion from a trabecular meshwork region detected by the detection unit based on the return light. The polarization characteristic data further includes depolarization degree or polarization uniformity of the return light with respect to the light irradiated to the corner angle, and further includes information on the depolarization degree or polarization uniformity of the corner angle. ,
The ophthalmologic analysis apparatus according to claim 7, wherein the detection unit detects a pigmentation portion in the trabecular meshwork based on the polarization characteristic data.   The said detection means acquires the information which shows the spectrum waveform in return light, and detects the pigmentation part in a trabecular meshwork based on the said spectrum waveform in consideration of the absorption band in the said pigmentation part. Ophthalmic analysis device.   The detection means further detects a Schlemm's canal from a region having a small polarization delay with respect to the trabecular meshwork in the vicinity of the region detected as the trabecular meshwork based on the polarization characteristic data. The ophthalmologic analyzer according to any one of 6 to 9. The polarization characteristic data includes depolarization degree or polarization uniformity of the return light with respect to the light irradiated to the corner angle, and includes information on depolarization or polarization uniformity at the corner angle,
The ophthalmologic analyzer according to claim 1, wherein the detection unit detects a pigmentation portion as the feature portion based on the polarization characteristic data. Image acquisition means for acquiring an image of the corner imaged in an imaging range corresponding to the polarization characteristic data;
Blood vessel information acquisition means for acquiring blood vessel position information at a corner in the imaging range;
The display control means for displaying the corner image on a monitor and displaying the detected feature and the blood vessel in association with the corner image. An ophthalmologic analysis device according to claim 1. An ophthalmic OCT having the ophthalmic analysis apparatus according to claim 1,
An optical scanner for scanning the light on the corner of the eye to be examined, a light obtained by combining the reference light and the return light from the corner, the light of the first polarization component and the second polarization An interference optical system including a splitting unit that splits at least into component light and a detector that receives the split light;
The ophthalmic OCT in which the acquisition unit generates and acquires the polarization characteristic data based on an output signal from a detection signal. The acquisition means acquires, as the polarization characteristic data, three-dimensional polarization OCT data at a corner angle or an En-face image in which the three-dimensional polarization OCT data is visualized with respect to a front direction,
Further, a three-dimensional image based on the three-dimensional polarization OCT data or the En-face image is displayed on a monitor as a corner angle image, and the feature detected by the detection means is displayed on the corner. The ophthalmic analysis apparatus according to claim 13, further comprising display control means for displaying in correspondence with an image of a corner.   The interference optical system includes an objective optical system that forms a turning point of the light between the cornea of the eye to be examined and the interference optical system by bending the light through the optical scanner. Or ophthalmic OCT of 14.   The ophthalmic OCT according to claim 13, wherein the interference optical system further includes a light source that emits measurement light having a center wavelength λ of 1.0 μm or more. An ophthalmic analysis program,
By being executed by the processor of the ophthalmic analyzer,
Polarization characteristic data indicating polarization characteristics at a corner angle of the anterior segment of the eye to be inspected, the first polarization component light divided from the return light of the light irradiated to the corner angle and the return light. And obtaining the polarization characteristic data based on the light of the second polarization component having a polarization different from that of the light of the first polarization component;
An ophthalmologic analysis program that causes the ophthalmologic analyzer to execute a detection step of detecting a characteristic portion at the corner based on the polarization characteristic data. In the acquisition step, the three-dimensional polarization OCT data of the corner angle or the En-face image in which the three-dimensional polarization OCT data is visualized with respect to the front direction is acquired as the polarization characteristic data,
In the detection step, the feature is detected by processing the polarization OCT data;
Further, a three-dimensional image based on the three-dimensional polarization OCT data or the En-face image is displayed as a corner image on a monitor, and the feature detected by the detection step is displayed on the corner. The ophthalmologic analysis program according to claim 17, wherein the ophthalmologic analyzer performs a display control step of displaying in association with a corner image.