JP6756873B2 - Ophthalmologic imaging equipment - Google Patents

Description

The present invention relates to an ophthalmologic imaging apparatus that acquires an image of an eye to be inspected using optical coherence tomography (OCT).

In recent years, OCT, which images the surface morphology and internal morphology of an object by utilizing the interference of light, has attracted attention. Since OCT is not invasive to the human body like X-ray CT, it is expected to be developed especially in the medical field and the biology field. For example, in the field of ophthalmology, devices for imaging the fundus and cornea have been put into practical use.

In an ophthalmologic imaging apparatus using OCT, various preliminary operations are generally performed before performing OCT measurement. Examples of such preliminary operations include alignment, optical path length difference adjustment, polarization adjustment, focus adjustment, and the like. In the alignment, the alignment of the optical system with respect to the eye to be inspected is performed. In the optical path length difference adjustment, the difference between the optical path length of the measurement light and the optical path length of the reference light is adjusted so that the target portion of the eye to be inspected is drawn at an appropriate position in the frame. In the polarization adjustment, the polarization state of the measurement light and / or the reference light is adjusted in order to increase the interference efficiency between the measurement light and the reference light. In the focus adjustment, focusing is performed so that the beam waist of the measurement light is located at or near the target site.

Japanese Unexamined Patent Publication No. 2014-13175

By the way, the object of imaging in the field of ophthalmology is the living eye. The living eye is constantly moving due to body movements, eye movements, and pulsations. Therefore, the eye to be inspected is moving during the preparatory movement and from the completion of the preparatory movement to the start of the OCT measurement. For example, when the eye to be inspected moves in the traveling direction of the measurement light (the depth direction of the eye to be inspected), the part of interest is drawn at the end of the imaging range (frame) by OCT measurement, or in some cases, the part of interest is out of the frame. I'm sorry. Then, there arises a problem that the preliminary operation after that cannot be appropriately executed or an image of the region of interest cannot be obtained.

An object of the present invention is to preferably perform a preliminary operation for OCT measurement of an eye to be inspected.

In order to achieve the above object, the invention according to claim 1 has a data acquisition unit that repeatedly acquires data by repeatedly scanning the eye to be inspected using optical coherence stromography, and the data acquisition unit that repeatedly acquires data. Based on the acquired data, the optical path length difference between the sample arm and the reference arm in the interference optics for optical coherence optics is adjusted so that the image of the eye to be inspected is placed at a reference position in the frame. The first control is executed, and the optical path length difference is changed so that the image of the eye to be inspected is arranged at a new reference position of the frame based on the data repeatedly acquired by the data acquisition unit. The control unit includes a control unit that executes the control of 2, and the control unit is repeatedly acquired by the data acquisition unit when one or more preliminary operations for performing optical coherence stromography of the eye to be inspected are executed. A determination unit that executes a process of determining whether or not to execute the second control based on the data is included, and the one or more preliminary operations are at least one of the polarization adjustment and the focus adjustment of the interference optical system. The determination unit defaults to a first distance calculation unit that calculates the distance between the image of a predetermined portion of the eye to be inspected and the upper end or the lower end of the frame, and a distance calculated by the first distance calculation unit. The control unit includes a first distance determination unit for determining whether or not the distance is equal to or less than the threshold value, and the control unit corresponds to the determination by the first distance determination unit that the distance is equal to or less than the threshold value. The second control is executed, the predetermined portion is the retinal surface of the eye to be inspected, and the first distance calculation unit calculates the distance between the image of the retinal surface and the upper end of the frame. The control unit is an ophthalmologic imaging apparatus characterized in that the second control is executed so as to set the new reference position on the upper end side of the frame with respect to the reference position.

According to the present invention, a preliminary operation for OCT measurement of the eye to be inspected can be preferably performed.

It is the schematic which shows an example of the structure of the ophthalmologic imaging apparatus which concerns on embodiment. It is the schematic which shows an example of the structure of the ophthalmologic imaging apparatus which concerns on embodiment. It is a schematic block diagram which shows an example of the structure of the ophthalmologic imaging apparatus which concerns on embodiment. It is a schematic block diagram which shows an example of the structure of the ophthalmologic imaging apparatus which concerns on embodiment. It is the schematic for demonstrating the process performed by the ophthalmologic imaging apparatus which concerns on embodiment. It is the schematic for demonstrating the process performed by the ophthalmologic imaging apparatus which concerns on embodiment. It is the schematic for demonstrating the process performed by the ophthalmologic imaging apparatus which concerns on embodiment. It is the schematic for demonstrating the process performed by the ophthalmologic imaging apparatus which concerns on embodiment. It is the schematic for demonstrating the process performed by the ophthalmologic imaging apparatus which concerns on embodiment. It is the schematic for demonstrating the process performed by the ophthalmologic imaging apparatus which concerns on embodiment. It is the schematic for demonstrating the process performed by the ophthalmologic imaging apparatus which concerns on embodiment. It is the schematic for demonstrating the process performed by the ophthalmologic imaging apparatus which concerns on embodiment. It is a flowchart which shows the operation example of the ophthalmologic imaging apparatus which concerns on embodiment.

Some typical embodiments of the present invention will be described in detail with reference to the drawings. The ophthalmologic imaging apparatus according to the embodiment uses OCT to form a tomographic image or a three-dimensional image of the eye to be inspected. In this specification, the images acquired by OCT may be collectively referred to as OCT images. Further, the measurement operation for forming an OCT image may be referred to as OCT measurement. In addition, the description content of the document described in this specification can be appropriately incorporated as the content of the following embodiment.

In this specification, an embodiment to which the Fourier domain type OCT is applied will be described in detail. In particular, the ophthalmologic imaging apparatus described below is configured to be able to acquire both an OCT image of the fundus and a fundus image by using the technique of spectral domain OCT, similarly to the apparatus disclosed in Patent Document 1. It is also possible to apply the configuration according to the present invention to a type other than the spectral domain, for example, an ophthalmologic imaging apparatus using the Swept Source OCT method. Further, in the following embodiment, a device combining an OCT device and a fundus camera will be described, but a fundus imaging device other than the fundus camera, for example, an SLO, a slit lamp, a microscope for ophthalmic surgery, or the like, is provided with a configuration according to this embodiment. It is also possible to combine the OCT devices having the same. Further, the configuration according to this embodiment can be incorporated into a single OCT device.

In the following, the case of acquiring an image of the fundus will be described in detail, but the part of the eye to be imaged is not limited to the fundus. For example, it is possible to apply the configuration according to this embodiment to a device for performing OCT measurement of the anterior segment of the eye such as the cornea. It is also possible to apply the configuration of this embodiment to a device capable of OCT measurement of both the fundus and the anterior segment of the eye. As an example in this case, it is possible to adopt a configuration in which an attachment for anterior segment imaging (objective lens, anterior lens, etc.) is added to the device for fundus photography described below.

[Constitution]
As shown in FIGS. 1 and 2, the ophthalmologic imaging apparatus 1 includes a fundus camera unit 2, an OCT unit 100, and an arithmetic control unit 200. The fundus camera unit 2 is provided with an optical system for photographing the fundus and acquiring a front image. The OCT unit 100 is provided with an optical system for acquiring an OCT image of the fundus. The arithmetic control unit 200 includes a computer that executes various arithmetic processes, control processes, and the like. The display device 3 displays various types of information. The display device 3 may be configured as a part of the ophthalmologic imaging device 1, or may be configured as an external device thereof.

[Fundus camera unit]
The fundus camera unit 2 shown in FIG. 1 is provided with an optical system for acquiring a two-dimensional image (fundus image) showing the surface morphology of the fundus Ef of the eye E to be inspected. The fundus image includes an observation image, a photographed image, and the like. The observation image is, for example, a monochrome moving image formed at a predetermined frame rate using near infrared light. The captured image may be, for example, a color image obtained by flashing visible light, or a monochrome still image using near-infrared light or visible light as illumination light. The fundus camera unit 2 may be configured to be capable of acquiring images other than these, such as a fluorescein fluorescence image, an indocyanine green fluorescence image, and a spontaneous fluorescence image.

The fundus camera unit 2 is provided with a chin rest and a forehead pad for supporting the face of the subject. Further, the fundus camera unit 2 is provided with an illumination optical system 10 and a photographing optical system 30. The illumination optical system 10 irradiates the fundus Ef with illumination light. The photographing optical system 30 guides the fundus reflected light of this illumination light to an imaging device (CCD image sensor (sometimes referred to simply as CCD) 35, 38). Further, the photographing optical system 30 guides the measurement light from the OCT unit 100 to the fundus Ef and guides the measurement light via the fundus Ef to the OCT unit 100.

The observation light source 11 of the illumination optical system 10 is composed of, for example, a halogen lamp. The light output from the observation light source 11 (observation illumination light) is reflected by the reflection mirror 12 having a curved reflecting surface, passes through the condenser lens 13, passes through the visible cut filter 14, and becomes near-infrared light. Become. Further, the observation illumination light is once focused in the vicinity of the photographing light source 15, reflected by the mirror 16, and passes through the relay lenses 17, 18, the diaphragm 19, and the relay lens 20. Then, the observation illumination light is reflected at the peripheral portion of the perforated mirror 21 (the region around the perforated portion), passes through the dichroic mirror 46, is refracted by the objective lens 22, and illuminates the fundus Ef. It is also possible to use an LED (Light Emitting Diode) as an observation light source.

The fundus reflected light of the observation illumination light is refracted by the objective lens 22, passes through the dichroic mirror 46, passes through the hole formed in the central region of the perforated mirror 21, passes through the dichroic mirror 55, and is a focusing lens. It is reflected by the mirror 32 via 31. Further, the fundus reflected light passes through the half mirror 39A, is reflected by the dichroic mirror 33, and is imaged on the light receiving surface of the CCD image sensor 35 by the condensing lens 34. The CCD image sensor 35 detects fundus reflected light at a predetermined frame rate, for example. An image (observation image) based on the fundus reflected light detected by the CCD image sensor 35 is displayed on the display device 3. When the photographing optical system 30 is focused on the anterior segment of the eye, an observation image of the anterior segment of the eye to be inspected E is displayed.

The photographing light source 15 is composed of, for example, a xenon lamp. The light output from the photographing light source 15 (photographing illumination light) is applied to the fundus Ef through the same path as the observation illumination light. The fundus reflected light of the photographing illumination light is guided to the dichroic mirror 33 through the same path as that of the observation illumination light, passes through the dichroic mirror 33, is reflected by the mirror 36, and is reflected by the condensing lens 37 of the CCD image sensor 38. An image is formed on the light receiving surface. An image (captured image) based on the fundus reflected light detected by the CCD image sensor 38 is displayed on the display device 3. The display device 3 for displaying the observed image and the display device 3 for displaying the captured image may be the same or different. Further, when the eye E to be inspected is illuminated with infrared light and the same imaging is performed, an infrared captured image is displayed. It is also possible to use an LED as a photographing light source.

The illumination optical system 10 has a small pupil diaphragm that can be inserted into and removed from the optical path. The small pupil diaphragm is inserted into the optical path when the eye E to be examined is a small pupil eye. The small pupil diaphragm is arranged in the optical path as, for example, a diaphragm 19. When the pupil diameter of the eye E to be inspected is normal, a diaphragm (normal pupil diaphragm) applied to photographing the eye E having a normal pupil diameter is arranged in the optical path as the diaphragm 19. That is, the diaphragm 19 includes a normal pupil diaphragm and a small pupil diaphragm that can be selectively arranged in the optical path.

The LCD (Liquid Crystal Display) 39 displays a fixation target and an index for measuring visual acuity. The fixation target is an index for fixing the eye E to be examined in a predetermined direction, and is used at the time of fundus photography, OCT measurement, and the like.

A part of the light output from the LCD 39 is reflected by the half mirror 39A, reflected by the mirror 32, passes through the focusing lens 31 and the dichroic mirror 55, passes through the hole of the perforated mirror 21, and is dichroic. It passes through the mirror 46, is refracted by the objective lens 22, and is projected onto the fundus Ef.

By changing the display position of the fixation target on the screen of the LCD 39, the direction (fixation position) at which the eye E to be inspected is fixed can be changed. The fixation position of the eye E to be inspected includes, for example, a position for acquiring an image centered on the macula of the fundus Ef and a position for acquiring an image centered on the optic nerve head, as in a conventional fundus camera. There is also a position for acquiring an image centered on the center of the fundus between the macula and the optic nerve head. It is also possible to arbitrarily change the display position of the fixation target.

Further, the fundus camera unit 2 is provided with an alignment optical system 50 and a focus optical system 60 as in the conventional fundus camera. The alignment optical system 50 generates an index (alignment index) for aligning the device optical system with respect to the eye E to be inspected (alignment). The focus optical system 60 generates an index (split index) for aligning the focal position of the photographing optical system 30 with the fundus Ef.

The light (alignment light) output from the LED 51 of the alignment optical system 50 is reflected by the dichroic mirror 55 via the diaphragms 52 and 53 and the relay lens 54, passes through the holes of the perforated mirror 21, and passes through the holes of the perforated mirror 21 to pass through the dichroic mirror 46. Is transmitted and projected onto the cornea of the eye E to be inspected by the objective lens 22.

The corneal reflected light of the alignment light passes through the objective lens 22, the dichroic mirror 46, and the above-mentioned hole, and a part of the light passes through the dichroic mirror 55, passes through the focusing lens 31, is reflected by the mirror 32, and is reflected by the mirror 32. It passes through 39A, is reflected by the dichroic mirror 33, and is projected onto the light receiving surface of the CCD image sensor 35 by the condenser lens 34. The received image (alignment index) by the CCD image sensor 35 is displayed on the display device 3 together with the observed image. The user can manually perform the alignment while visually recognizing the alignment index. Further, as will be described in detail later, the arithmetic control unit 200 can perform alignment by analyzing the position of the alignment index and moving the optical system (auto alignment function).

When adjusting the focus, the reflecting surface of the reflecting rod 67 is obliquely provided on the optical path of the illumination optical system 10. The light (focus light) output from the LED 61 of the focus optical system 60 passes through the relay lens 62, is separated into two light beams by the split index plate 63, passes through the two-hole diaphragm 64, and is reflected by the mirror 65. The condenser lens 66 once forms an image on the reflecting surface of the reflecting rod 67 and reflects the image. Further, the focus light passes through the relay lens 20, is reflected by the perforated mirror 21, passes through the dichroic mirror 46, is refracted by the objective lens 22, and is projected onto the fundus Ef.

The fundus reflected light of the focus light is detected by the CCD image sensor 35 through the same path as the corneal reflected light of the alignment light. The received image (split index) by the CCD image sensor 35 is displayed on the display device 3 together with the observed image. The user can manually adjust the focus while visually recognizing the split index, as in the conventional fundus camera. Further, although the details will be described later, the focus adjustment can be performed by the arithmetic control unit 200 analyzing the position of the split index and moving the focusing lens 31 and the focus optical system 60 (autofocus function).

The dichroic mirror 46 branches the optical path for OCT measurement from the optical path for fundus photography. The dichroic mirror 46 reflects light in the wavelength band used for OCT measurement and transmits light for fundus photography. The optical path for OCT measurement is provided with a collimator lens unit 40, an optical path length changing unit 41, a galvano scanner 42, a focusing lens 43, a mirror 44, and a relay lens 45 in order from the OCT unit 100 side. Has been done.

The optical path length changing unit 41 is movable in the optical axis direction (direction of the arrow shown in FIG. 1), and changes the optical path length of the optical path (sample arm) for OCT measurement. By changing the optical path length of the sample arm, the difference between the optical path length of the sample arm and the optical path length of the reference arm (optical path length difference) is changed. This change in the optical path length difference is used for correcting the optical path length according to the axial length of the eye E to be inspected, adjusting the interference state, and the like. The optical path length changing unit 41 includes, for example, a corner cube and a mechanism for moving the corner cube.

The configuration for changing the optical path length difference between the sample arm and the reference arm is not limited to this. For example, a reflection mirror (reference mirror) can be arranged on the reference arm, and the reference mirror can be configured to move in the traveling direction of the reference light. Thereby, the optical path length difference can be changed through the change of the optical path length of the reference arm. Further, the optical path length of the sample arm can be changed by moving the optical system itself that contributes to the OCT measurement with respect to the eye E to be inspected. In general, the optical path length difference changing unit has an arbitrary configuration in which the optical path length of the sample arm and / or the reference arm can be changed.

The galvano scanner 42 changes the traveling direction of the light (measurement light) passing through the optical path for OCT measurement. Thereby, the fundus Ef can be scanned with the measurement light. The galvano scanner 42 includes, for example, a galvano mirror that scans the measurement light in the x direction, a galvano mirror that scans the measurement light in the y direction, and a mechanism that independently drives them. Thereby, the measurement light can be scanned in any direction on the xy plane.

[OCT unit]
An example of the configuration of the OCT unit 100 will be described with reference to FIG. The OCT unit 100 is provided with an optical system for acquiring an OCT image of the fundus Ef. This optical system has a configuration similar to that of a conventional spectral domain type OCT apparatus. That is, this optical system divides the low coherence light into reference light and measurement light, and causes the measurement light via the fundus Ef and the reference light via the reference arm to interfere with each other to generate interference light, and the interference light is generated. It is configured to detect spectral components. This detection result (detection signal) is sent to the arithmetic control unit 200.

In the case of a swept source type OCT device, a wavelength sweep light source is provided instead of a light source that outputs a low coherence light source, and an optical member that spectrally decomposes the interference light is not provided. In general, for the configuration of the OCT unit 100, known techniques depending on the type of optical coherence tomography can be arbitrarily applied.

The light source unit 101 outputs a wide band low coherence light L0. The low coherence light L0 includes, for example, a wavelength band in the near infrared region (about 800 nm to 900 nm) and has a temporal coherence length of about several tens of micrometers. Infrared light having a wavelength band invisible to the human eye, for example, a central wavelength of about 1040 to 1060 nm may be used as the low coherence light L0.

The light source unit 101 includes an optical output device such as a super luminescent diode (SLD), an LED, and an SOA (Semiconductor Optical Amplifier).

The low coherence light L0 output from the light source unit 101 is guided by the optical fiber 102 to the fiber coupler 103 and divided into the measurement light LS and the reference light LR.

The reference optical LR is guided by the optical fiber 104 and reaches the optical attenuator (attenuator) 105. The optical attenuator 105 automatically adjusts the amount of light of the reference light LR guided to the optical fiber 104 under the control of the arithmetic control unit 200 by using a known technique. The reference light LR whose light amount is adjusted by the optical attenuator 105 is guided by the optical fiber 104 and reaches the polarization regulator (polarization controller) 106.

The polarization regulator 106 is, for example, a device that adjusts the polarization state of the reference light LR guided in the optical fiber 104 by applying stress to the looped optical fiber 104 from the outside. The configuration of the polarization regulator 106 is not limited to this, and any known technique can be used. The reference light LR whose polarization state has been adjusted by the polarization regulator 106 reaches the fiber coupler 109.

In the configuration shown in FIG. 2, the polarization state of the reference light LR is adjusted, but the polarization state of the measurement light LS may be adjusted. In general, the polarization state of the measurement light LS and / or the reference light LR may be changed. As a result, it is possible to control so that the polarization state of the measurement light LS and the polarization state of the reference light LR match, and it is possible to improve the interference efficiency between the measurement light LS and the reference light LR.

The measurement light LS generated by the fiber coupler 103 is guided by the optical fiber 107 and is converted into a parallel luminous flux by the collimator lens unit 40. Further, the measurement light LS reaches the dichroic mirror 46 via the optical path length changing unit 41, the galvano scanner 42, the focusing lens 43, the mirror 44, and the relay lens 45. Then, the measurement light LS is reflected by the dichroic mirror 46, refracted by the objective lens 22, and irradiated to the fundus Ef. The measurement light LS is scattered (including reflection) at various depth positions of the fundus Ef. The backscattered light of the measurement light LS by the fundus Ef travels in the same direction as the outward path in the opposite direction, is guided to the fiber coupler 103, and reaches the fiber coupler 109 via the optical fiber 108.

The fiber coupler 109 interferes with the backscattered light of the measurement light LS and the reference light LR via the optical fiber 104. The interference light LC generated thereby is guided by the optical fiber 110 and emitted from the emission end 111. Further, the interference light LC is made into a parallel light flux by the collimator lens 112, is separated by the diffraction grating 113 (spectral decomposition), is condensed by the condenser lens 114, and is projected onto the light receiving surface of the CCD image sensor 115. Although the diffraction grating 113 shown in FIG. 2 is a transmission type, it is also possible to use a spectroscopic element of another form such as a reflection type diffraction grating.

The CCD image sensor 115 is, for example, a line sensor, which detects each spectral component of the dispersed interference light LC and converts it into an electric charge. The CCD image sensor 115 accumulates this electric charge, generates a detection signal, and sends this to the arithmetic control unit 200.

In this embodiment, a Michelson type interferometer is adopted, but any type of interferometer such as a Mach-Zehnder type can be appropriately adopted. Further, instead of the CCD image sensor, another form of image sensor, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor or the like can be used. Further, when the Swept source type OCT is applied, the diffraction grating 113 is unnecessary, and a balanced photodiode or the like is provided instead of the CCD image sensor 115.

[Calculation control unit]
The configuration of the arithmetic control unit 200 will be described. The arithmetic control unit 200 analyzes the detection signal input from the CCD image sensor 115 to form an OCT image of the fundus Ef. The arithmetic processing for that purpose is the same as that of the conventional spectral domain type OCT apparatus.

Further, the arithmetic control unit 200 controls each part of the fundus camera unit 2, the display device 3, and the OCT unit 100.

As the control of the fundus camera unit 2, the arithmetic control unit 200 controls the operation of the observation light source 11, the photographing light source 15 and the LEDs 51 and 61, the operation control of the LCD 39, the movement control of the focusing lenses 31 and 43, and the movement control of the reflection rod 67. , The movement control of the focus optical system 60, the movement control of the optical path length changing unit 41, the operation control of the galvano scanner 42, and the like.

As the control of the OCT unit 100, the arithmetic control unit 200 controls the operation of the light source unit 101, the operation control of the optical attenuator 105, the operation control of the polarization regulator 106, the operation control of the CCD image sensor 115, and the like.

The arithmetic control unit 200 includes, for example, a microprocessor, RAM, ROM, a hard disk drive, a communication interface, and the like, as in a conventional computer. A computer program for controlling the ophthalmologic imaging device 1 is stored in a storage device such as a hard disk drive. The arithmetic control unit 200 may include various circuit boards, for example, circuit boards for forming OCT images. Further, the arithmetic control unit 200 may include an operation device (input device) such as a keyboard and a mouse, and a display device such as an LCD.

The fundus camera unit 2, the display device 3, the OCT unit 100, and the arithmetic control unit 200 may be integrally configured (that is, in a single housing), or may be separately configured in two or more housings. You may be.

[Control system]
The configuration of the control system of the ophthalmologic imaging apparatus 1 will be described with reference to FIGS. 3 and 4.

(Control unit)
The control system of the ophthalmologic imaging apparatus 1 is mainly composed of the control unit 210. The control unit 210 includes, for example, the above-mentioned microprocessor, RAM, ROM, hard disk drive, communication interface, and the like. The control unit 210 is provided with a main control unit 211 and a storage unit 212.

(Main control unit)
The main control unit 211 performs the various controls described above. In particular, the main control unit 211 includes an optical path length changing unit 41 of the fundus camera unit 2, a galvano scanner 42, a focusing lens 31, a focus optical system 60 (shooting focusing drive unit 300), and a focusing lens 43 (OCT). The focusing drive unit 400) and the entire optical system (optical system drive unit 500) are controlled. Further, the main control unit 211 controls the light source unit 101 of the OCT unit 100, the optical attenuator 105, the polarization adjuster 106, and the like.

The photographing focusing drive unit 300 moves the focusing lens 31 in the optical axis direction of the photographing optical system 30 and the focus optical system 60 in the optical axis direction of the illumination optical system 10. As a result, the focusing position of the photographing optical system 300 is changed. The photographing focusing drive unit 300 may individually have a mechanism for moving the focusing lens 31 and a mechanism for moving the focus optical system 60. The shooting focusing drive unit 300 is controlled when performing focus adjustment or the like.

The OCT focusing drive unit 400 moves the focusing lens 43 in the optical axis direction of the sample arm. As a result, the focusing position of the measurement light LS is changed. The focusing position of the measurement light LS corresponds to the depth position (z position) of the beam waist of the measurement light LS.

The optical system drive unit 500 three-dimensionally moves the optical system provided in the fundus camera unit 2. This control is used in alignment and tracking. Tracking is to move the device optical system according to the eye movement of the eye E to be inspected. When performing tracking, alignment and focus adjustment are performed in advance. Tracking is a function of maintaining a suitable positional relationship in which alignment and focus are achieved by making the position of the optical system of the device follow the movement of the eyeball. Further, the optical system drive unit 500 may be controlled in order to change the optical path length of the sample arm (therefore, the optical path length difference between the sample arm and the reference arm).

The main control unit 211 performs a process of writing data to the storage unit 212 and a process of reading data from the storage unit 212.

The main control unit 211 executes a plurality of preliminary operations before performing the OCT measurement. Preliminary operations include alignment, coarse focus adjustment, optical path length difference adjustment, polarization adjustment, and fine focus adjustment. The plurality of preliminary operations are performed in a predetermined order. In this embodiment, it is assumed that the execution is performed in the above order.

The type and order of the preliminary operations are not limited to this, and are arbitrary. For example, a preliminary operation (small pupil determination) for determining whether or not the eye E to be inspected is a small pupil eye can be added to the preliminary operation. The small pupil determination is performed, for example, between coarse focus adjustment and optical path length difference adjustment. The small pupil determination includes, for example, the following series of processes: the process of acquiring the front image (anterior segment image) of the eye E to be examined; the process of identifying the image region corresponding to the pupil; the size of the identified pupil region ( Process for determining (diameter, circumference, etc.); processing for determining whether or not the eye is a small pupil eye based on the obtained size (threshold processing); processing for controlling the aperture 19 when it is determined that the eye is a small pupil eye. Here, a process of approximating the pupil region to a circle or an ellipse may be further included in order to obtain the pupil size.

The coarse focus adjustment is a focus adjustment using the split index described above. The focus coarse adjustment is performed by determining the position of the focusing lens 31 based on the information relating the eye refractive power and the position of the focusing lens 31 acquired in advance and the measured value of the refractive power of the eye to be inspected. Can also be done.

On the other hand, the focus fine adjustment is performed based on the interference sensitivity of the OCT measurement. For example, by performing OCT measurement of the eye E to be inspected, acquiring an interference signal, and monitoring the interference intensity (interference sensitivity), the position of the focusing lens 43 that maximizes the interference intensity is obtained, and the position is adjusted to that position. By moving the focusing lens 43, the focus fine adjustment can be performed.

In the optical path length difference adjustment, the optical path length changing unit 41 is controlled so that the target portion of the eye E to be inspected is drawn at a predetermined z position in the frame of the OCT image. Thereby, the optical path length difference between the sample arm and the reference arm is adjusted. As a target portion for adjusting the optical path length difference, a portion exhibiting a characteristic brightness in the OCT image (or a portion exhibiting a characteristic reflection intensity in the reflection intensity profile) is set in advance. As a specific example, in the OCT measurement of the fundus, the retinal pigment epithelial layer can be set as a reference, and in the OCT measurement of the anterior segment, the corneal surface can be set as a reference. The automatic process of searching for a suitable optical path length difference in this way is called auto Z.

The optical path length difference adjustment is not limited to the auto Z. For example, it is possible to perform an automatic process that maintains a suitable image rendering position achieved by Auto Z. Such a process is called Z-lock. In the Z lock, for example, the optical path length changing unit 41 is controlled so that the state in which the target portion, which is the reference for adjusting the optical path length difference, is drawn at a predetermined z position in the frame is maintained.

In addition, Z lock may not be preferably performed due to body movement, eye movement, or pulsation. That is, the Z lock may fail due to a large deviation in the positional relationship between the optical system and the eye E to be inspected. It is possible to provide a preliminary operation to deal with such a situation. This process includes a process of changing the z position (the predetermined z position described above) which is a reference of the Z lock. A specific example of this Z lock position change process will be described later.

In the polarization adjustment, the polarization state of the reference light LR is adjusted in order to optimize the interference efficiency between the measurement light LS and the reference light LR.

(Memory)
The storage unit 212 stores various types of data. Examples of the data stored in the storage unit 212 include image data of an OCT image, image data of a fundus image, and eye examination information. The eye test information includes information about the subject such as the patient ID and name, and information about the test eye such as left eye / right eye identification information. Further, various programs and data for operating the ophthalmologic photographing apparatus 1 are stored in the storage unit 212.

(Image forming part)
The image forming unit 220 forms image data of a tomographic image of the fundus Ef based on the detection signal from the CCD image sensor 115. This process includes processing such as noise removal (noise reduction), filtering, dispersion compensation, and FFT (Fast Fourier Transform), as in the conventional spectral domain type optical coherence tomography. In the case of other types of OCT apparatus, the image forming unit 220 performs a known process according to the type.

The image forming unit 220 includes, for example, the circuit board described above. In this specification, "image data" and "image" based on the "image data" may be equated.

(Data processing unit)
The data processing unit 230 processes the data acquired by the imaging of the eye E to be inspected and the OCT measurement. For example, the data processing unit 230 performs various image processing and analysis processing on the image formed by the image forming unit 220. For example, the data processing unit 230 executes various correction processes such as image brightness correction. In addition, the data processing unit 230 performs various image processing and analysis processing on the images (fundus image, anterior ocular segment image, etc.) obtained by the fundus camera unit 2.

The data processing unit 230 executes known image processing such as interpolation processing for interpolating pixels between tomographic images to form image data of a three-dimensional image of the fundus Ef. The image data of the three-dimensional image means the image data in which the positions of the pixels are defined by the three-dimensional coordinate system. As the image data of the three-dimensional image, there is image data composed of voxels arranged three-dimensionally. This image data is called volume data or voxel data. When displaying an image based on volume data, the data processing unit 230 performs rendering processing (volume rendering, MIP (Maximum Industry Projection: maximum value projection), etc.) on the volume data to see from a specific line-of-sight direction. Form the image data of the pseudo three-dimensional image at the time. This pseudo three-dimensional image is displayed on a display device such as the display unit 241.

It is also possible to form stack data of a plurality of tomographic images as image data of a three-dimensional image. The stack data is image data obtained by three-dimensionally arranging a plurality of tomographic images obtained along a plurality of scanning lines based on the positional relationship of the scanning lines. That is, the stack data is image data obtained by expressing a plurality of tomographic images originally defined by individual two-dimensional coordinate systems by one three-dimensional coordinate system (that is, embedding them in one three-dimensional space). is there.

The data processing unit 230 includes an optical system movement amount acquisition unit 231, a photographing focusing lens movement amount acquisition unit 232, an optical path length difference change amount acquisition unit 233, a determination unit 234, and an image quality determination unit 235. The optical system movement amount acquisition unit 231 relates to alignment. The shooting focusing lens movement amount acquisition unit 232 relates to coarse focus adjustment. The optical path length difference change amount acquisition unit 233 relates to auto Z, Z lock, and Z lock position change processing. The determination unit 234 relates to the Z lock position change process. The image quality determination unit 235 relates to polarization adjustment and focus coarse adjustment. It is not necessary that all of these functional parts are provided in the data processing unit 230, and it is sufficient if the functional parts related to the preliminary operation to be executed of the processing according to the embodiment are provided. Further, when the process according to the embodiment is executed for the preliminary operation other than these, a functional part related to the preliminary operation is provided. In this embodiment, at least the Z lock and the Z lock position change process are executed, and at least functional parts related to these are provided.

(Optical system movement amount acquisition unit)
At the time of alignment, the ophthalmologic imaging apparatus 1 photographs the eye E (anterior eye portion) in a state where the alignment index is projected and acquires a front image. This front image is a moving image having a predetermined frame rate. The optical system movement amount acquisition unit 231 acquires the movement amount of the optical system required to achieve an appropriate alignment state by analyzing (the frame) of this front image.

The information acquired by the optical system movement amount acquisition unit 231 is not limited to the movement amount of the optical system itself. For example, the control content of the optical system drive unit 500 (number of transmission pulses, etc.) and information obtained during the process of acquiring this movement amount (alignment deviation amount, etc.) are substantially the same as the movement amount of the optical system. The information may be equivalent (equivalent) to.

An example of the process executed by the optical system movement amount acquisition unit 231 will be described. An alignment index is drawn on the front image input to the optical system movement amount acquisition unit 231. Examples of the drawing mode of the alignment index are shown in FIGS. 5A and 5B. In FIGS. 5A and 5B, the image of eye E to be inspected is omitted.

In the front image G1 of the eye E to be inspected shown in FIG. 5A, two images (alignment index images) A1 and A2 of the alignment index are drawn as bright spots. Further, the main control unit 211 superimposes and displays a parenthesis-shaped target image T indicating an alignment target position on the center position of the front image G1.

When the alignment in the xy direction with respect to the eye E to be examined is misaligned, the two alignment index images A1 and A2 are drawn at positions away from the target image T. Further, when the alignment in the z direction is deviated, the two alignment index images A1 and A2 are drawn at different positions from each other. When all the alignments in the xyz direction are correct, as shown in FIG. 5B, the two alignment index images A1 and A2 are drawn inside the target image T so as to overlap each other.

The displacements (displacement amount, displacement direction) of the two alignment index images A1 and A2 with respect to the target image T indicate the misalignment (displacement amount, displacement direction) in the xy direction. The displacements (displacement amount, displacement direction) of the two alignment index images A1 and A2 indicate the misalignment (displacement amount, displacement direction) in the z direction.

The optical system movement amount acquisition unit 231 obtains an alignment deviation by analyzing the front image G1 and acquires an optical system movement amount that cancels the deviation. This process is executed, for example, as follows. First, the optical system movement amount acquisition unit 231 identifies an image region corresponding to the alignment index images A1 and A2 based on the pixel information (luminance value and the like) of the front image G1. Next, the optical system movement amount acquisition unit 231 specifies the feature positions (center, center of gravity, etc.) of each of the specified image regions. Subsequently, the optical system movement amount acquisition unit 231 obtains the displacement of the feature position of each image region with respect to the center position of the target image T. Then, the optical system movement amount acquisition unit 231 obtains the alignment deviation based on the obtained displacement, and acquires the movement amount of the optical system that cancels the alignment deviation. The optical system movement amount acquisition unit 231 stores in advance information that associates the displacement of the alignment index image defined in the coordinate system of the front image with the misalignment defined in the coordinate system of the real space. The alignment deviation can be obtained by referring to this correspondence information. The operation related to alignment is continued until the calculated alignment deviation amount becomes equal to or less than a predetermined threshold value.

(Shooting focus lens movement amount acquisition unit)
When performing coarse focus adjustment, the ophthalmologic imaging apparatus 1 photographs the fundus Ef in a state where the split index (focus index) is projected to acquire a front image. This front image is a moving image having a predetermined frame rate. The photographing focusing lens movement amount acquisition unit 232 acquires the movement amount of the focusing lens 31 necessary for achieving an appropriate focus state by analyzing this front image (frame).

The information acquired by the photographing focusing lens movement amount acquisition unit 232 is not limited to the movement amount itself of the focusing lens 31. For example, the amount of movement of the focusing lens 31 such as the control content (number of transmission pulses, etc.) of the shooting focusing drive unit 300 and the information (such as the amount of focus shift) obtained during the process of acquiring this movement amount. The information may be substantially equivalent to.

An example of the process executed by the photographing focusing lens movement amount acquisition unit 232 will be described. A split index is drawn on the front image input to the photographing focusing lens movement amount acquisition unit 232. Examples of the drawing mode of the split index are shown in FIGS. 6A and 6B. In FIGS. 6A and 6B, the image of fundus Ef is omitted.

The shadow of the reflection rod 67 is reflected in the front image G2 of the fundus Ef shown in FIG. 6A, and two images (split index images) B1 and B2 of the split index are drawn as bright lines in this shadow region. ..

When the focus position is deviated (in the z direction), the two split index images B1 and B2 are displaced laterally from each other. The displacement direction indicates the deviation direction of the focus position (+ z direction or −z direction), and the displacement amount indicates the magnitude of the deviation of the focus position. When the focus position is appropriate, as shown in FIG. 6B, the two split index images B1 and B2 are drawn at positions aligned in the vertical direction.

The photographing focusing lens movement amount acquisition unit 232 obtains the deviation of the focus position by analyzing the front image G2, and acquires the movement amount of the focusing lens 31 that cancels out the deviation. This process is executed, for example, as follows. First, the photographing focusing lens movement amount acquisition unit 232 identifies an image region corresponding to the split index images B1 and B2 based on the pixel information (luminance value, etc.) of the front image G2. Next, the photographing focusing lens movement amount acquisition unit 232 specifies the feature positions (center, center of gravity, axis, etc.) of each of the specified image regions. Subsequently, the photographing focusing lens movement amount acquisition unit 232 obtains the displacement in the lateral direction of the feature positions of the two image regions corresponding to the split index images B1 and B2. Then, the photographing focusing lens movement amount acquisition unit 232 obtains the deviation of the focus position based on the obtained displacement, and acquires the movement amount of the focusing lens 31 that cancels the deviation of the focus position. Here, the photographing focusing lens movement amount acquisition unit 232 provides information in which the displacement of the split index image defined in the coordinate system of the front image is associated with the deviation of the focus position defined in the coordinate system of the real space. It can be stored in advance and the amount of change in the focus position can be obtained by referring to this correspondence information.

Further, the photographing focusing lens movement amount acquisition unit 232 may be configured to acquire the movement amount of the focusing lens 43 of the sample arm. This process is performed, for example, by referring to the same correspondence information as described above, or by referring to the information that associates the focus position between the two focusing lenses 31 and 43. The focusing of the sample arm executed in this way is a rough adjustment, and the fine adjustment is executed in the subsequent processing. The operation related to the coarse focus adjustment is continued until the calculated shift amount of the focus position becomes equal to or less than a predetermined threshold value.

(Optical path length difference change amount acquisition unit, judgment unit)
When performing auto-Z, the ophthalmologic imaging apparatus 1 controls the optical system to perform OCT measurement of the fundus Ef. In this OCT measurement, for example, substantially the same cross section of the fundus Ef is repeatedly scanned at a predetermined frequency. That is, the OCT measurement with the same scan pattern is repeatedly executed for the eye E to which the fixation target is presented. The optical path length difference change amount acquisition unit 233 arranges the image of the fundus Ef at a specific position of the frame by analyzing the detection result (reflection intensity profile, OCT image, etc.) of the interference light LC repeatedly acquired by this OCT measurement. Obtain the amount of change in the optical path length difference for the purpose. The optical path length difference change amount acquisition unit 233 of the present embodiment acquires the change amount of the optical path length of the sample arm.

The information acquired by the optical path length difference change amount acquisition unit 233 is not limited to the optical path length difference (optical path length) change amount itself. For example, the control content of the optical path length changing unit 41 (the number of transmission pulses, etc.) and the information obtained in the middle of the process of acquiring this change amount (the amount of deviation of the position of the image in the z direction in the frame, etc.). The information may be substantially the same as the amount of change in the optical path length difference.

An example of the process executed by the optical path length difference change amount acquisition unit 233 for the auto Z will be described. When auto-Z is performed, the OCT image G3 as shown in FIG. 7A is displayed as a moving image. On the right side surface of the OCT image G3, a slider H that can be moved in the vertical direction is displayed. The position indicated by the slider H corresponds to the specific position which is the target position of the auto Z. The position of the slider H may be a default position, a position arbitrarily set by the user, or a position after being changed by the z-lock position change process.

In the initial stage of Auto Z, the image of the fundus Ef is generally not drawn in the OCT image, or the image of the fundus Ef is displayed at any position of the OCT image as a result of the above-mentioned coarse focus adjustment, for example. (See FIG. 7A). The OCT image G3 formed by the image forming unit 220 is input to the optical path length difference change amount acquisition unit 233. The optical path length difference change amount acquisition unit 233 identifies an image region R corresponding to a predetermined portion of the fundus Ef (for example, the retinal pigment epithelial layer) by analyzing the pixel information (luminance value, etc.) of the OCT image G3, and this The z coordinate of the image area R is obtained. This z-coordinate may be the z-coordinate of a feature position (for example, the center, the end, the lowermost end, the uppermost end) in the image area R, or is statistically calculated from the z-coordinates of two or more positions in the image area R. It may be a statistic (eg, mean, mode, median).

If the target image area R is not specified, that is, if the predetermined portion is not visualized in the OCT image G3, a signal indicating that is sent to the control unit 210, and the main control unit 211 that receives this signal , The optical path length changing unit 41 is controlled according to a predetermined algorithm, and the identification of the image area R is executed again. This series of processing is repeated until the image region R is specified.

When the image region R is specified and its z coordinate is obtained, the optical path length difference change amount acquisition unit 233 obtains the displacement of the z coordinate of the image region R with respect to the z coordinate (reference z position) indicated by the slider H, and this displacement is obtained. Acquires the amount of change in the optical path length difference that cancels. Here, the optical path length difference change amount acquisition unit 233 provides information in which the displacement in the z direction defined in the coordinate system of the OCT image G3 and the deviation of the optical path length difference defined in the real space coordinate system are associated with each other. It can be stored in advance and the amount of change in the optical path length difference can be obtained by referring to this corresponding information. FIG. 7B shows a state in which auto Z is successful based on the amount of change thus acquired. Auto Z is continued until the state shown in FIG. 7B is realized, that is, until the calculated displacement becomes equal to or less than a predetermined threshold value.

The Z lock will be described. In the Z lock, as in the case of the auto Z, substantially the same cross section of the fundus Ef is repeatedly scanned at a predetermined frequency. Further, the optical path length difference change amount acquisition unit 233 analyzes the detection result of the interference light LC repeatedly acquired by this OCT measurement, and thereby arranges the image region R at the reference z position indicated by the slider H. Get the amount of change in the difference. This process is executed in the same manner as in the case of Auto Z.

The Z lock position change process related to the optical path length difference change amount acquisition unit 233 and the determination unit 234 will be described. The Z lock position change process is started, for example, in response to the completion of the auto Z, and is executed in parallel with the Z lock. The Z-lock position change process monitors the position of the image of the eye E to be inspected (image area R or other image area) in the frame of the OCT image G3 in the z direction, thereby moving to the upper end, the lower end, or the outside of the frame. It includes a process of detecting that the image of the eye E to be inspected has moved.

In the Z lock position change process, substantially the same cross section of the fundus Ef is repeatedly scanned at a predetermined frequency, as in the case of the auto Z and the Z lock.

The optical path length difference change amount acquisition unit 233 analyzes, for example, the detection result of the interference light LC repeatedly acquired by this OCT measurement to obtain an image of a predetermined portion of the eye E to be inspected and the upper end (or lower end) of the frame. Calculate the distance between. In the example shown in FIG. 8A, the distance Δz1 between the image region (surface region) R1 corresponding to the surface of the fundus Ef (the surface of the retina) and the upper end of the frame is calculated.

The determination unit 234 determines whether the distance Δz1 calculated by the optical path length difference change amount acquisition unit 233 is equal to or less than the threshold value. This threshold is preset. The threshold may be any value greater than or equal to zero. When the threshold value is zero, the determination process executed by the determination unit 234 corresponds to the process of determining whether or not the surface region R1 is in contact with the upper end of the frame. When the threshold value is a positive value, the determination process executed by the determination unit 234 corresponds to a process of determining whether or not the surface region R1 is close to the upper end of the frame by a distance equal to or less than the threshold value. It is also assumed that a part or all of the surface region R1 protrudes from the frame. The surface region R1 is generally in contact with both the left and right edges of the frame. Such a case corresponds to the case where the surface region R1 is not in contact with one or both of the left end and the right end, and the case where a part or all of the surface region R1 is not specified. In such a case, the determination unit 234 outputs the same determination result as in the case where the distance calculated by the optical path length difference change amount acquisition unit 233 is equal to or less than the threshold value.

Other processing examples will be described. The optical path length difference change amount acquisition unit 233 calculates the distance between the image of the predetermined portion of the eye E to be inspected and the reference z position by analyzing the detection result of the interference light LC repeatedly acquired by the OCT measurement. To do. In the example shown in FIG. 8B, the distance Δz2 between the image region R corresponding to the retinal pigment epithelial layer and the reference z position indicated by the slider H is calculated.

The determination unit 234 determines whether the distance Δz2 calculated by the optical path length difference change amount acquisition unit 233 is equal to or greater than the threshold value. This threshold is preset. It is also assumed that part or all of the image area R may extend beyond the frame. The image area R is generally in contact with both the left and right edges of the frame. Such a case corresponds to the case where the image area R does not touch one or both of the left end and the right end, or the case where a part or all of the image area R is not specified. In such a case, the determination unit 234 outputs the same determination result as in the case where the distance calculated by the optical path length difference change amount acquisition unit 233 is equal to or greater than the threshold value.

(Image quality judgment unit)
Polarization adjustment will be described. When adjusting the polarization state of the measurement light LS and / or the reference light LR, the ophthalmologic imaging apparatus 1 performs the same repetitive OCT measurement as described above while controlling the polarization adjuster 106 according to a predetermined algorithm. .. The image quality determination unit 235 calculates a predetermined evaluation value regarding the image quality of the OCT image by analyzing the detection result of the interference light LC repeatedly acquired by the OCT measurement. Further, the image quality determination unit 235 determines whether or not the calculated evaluation value is equal to or less than the threshold value. This threshold is preset. The polarization adjustment is continued until the calculated evaluation value becomes equal to or less than the threshold value.

The focus fine adjustment will be described. When finely adjusting the focus, the ophthalmologic imaging apparatus 1 performs the same repetitive OCT measurement as described above while controlling the OCT focusing drive unit 400 according to a predetermined algorithm. The image quality determination unit 235 calculates a predetermined evaluation value regarding the image quality of the OCT image by analyzing the detection result of the interference light LC repeatedly acquired by the OCT measurement. Further, the image quality determination unit 235 determines whether or not the calculated evaluation value is equal to or less than the threshold value. The focus fine adjustment is continued until the calculated evaluation value becomes equal to or less than the threshold value.

It should be noted that the focus fine adjustment can be executed by another method. For example, the intensity (interference intensity, interference sensitivity) of the interference signals acquired sequentially is monitored while acquiring the interference signal by performing the above-mentioned repetitive OCT measurement. Further, by moving the focusing lens 43 while performing this monitoring process, the position of the focusing lens 43 that maximizes the interference intensity is searched for. By such fine adjustment of the focus, the focusing lens 43 can be guided to a position where the interference intensity is optimized. Similarly, it is possible to monitor the interference intensity in the polarization adjustment. More generally, for processing for real-time optimization such as polarization adjustment and focus fine adjustment, it is possible to refer to an arbitrary evaluation value that changes with a change in the adjustment target.

The data processing unit 230 that functions as described above includes, for example, the above-mentioned microprocessor, RAM, ROM, hard disk drive, circuit board, and the like. A computer program that causes a microprocessor to execute the above functions is stored in a storage device such as a hard disk drive in advance.

(User interface)
The user interface 240 includes a display unit 241 and an operation unit 242. The display unit 241 includes the display device and the display device 3 of the arithmetic control unit 200 described above. The operation unit 242 includes the operation device of the arithmetic control unit 200 described above. The operation unit 242 may include various buttons and keys provided on the housing and the outside of the ophthalmologic imaging apparatus 1. For example, when the fundus camera unit 2 has a housing similar to that of a conventional fundus camera, the operation unit 242 may include a joystick, an operation panel, and the like provided on the housing. Further, the display unit 241 may include various display devices such as a touch panel provided on the housing of the fundus camera unit 2.

The display unit 241 and the operation unit 242 do not need to be configured as separate devices. For example, it is possible to use a device such as a touch panel in which a display function and an operation function are integrated. In that case, the operation unit 242 is configured to include the touch panel and a computer program. The operation content for the operation unit 242 is input to the control unit 210 as an electric signal. Further, the graphical user interface (GUI) displayed on the display unit 241 and the operation unit 242 may be used to perform operations and information input.

[Scanning of measurement light and OCT image]
Here, the scanning of the measurement light LS and the OCT image will be described.

Scanning modes of the measurement optical LS by the ophthalmologic imaging apparatus 1 include, for example, horizontal scan, vertical scan, cross scan, radiation scan, circular scan, concentric circular scan, spiral (spiral) scan, and the like. These scanning modes are appropriately and selectively used in consideration of the observation site of the fundus, the analysis target (net thickness, etc.), the time required for scanning, the precision of scanning, and the like.

The horizontal scan scans the measurement light LS in the horizontal direction (x direction). The horizontal scan also includes a mode in which the measurement light LS is scanned along a plurality of horizontally extending scanning lines arranged in the vertical direction (y direction). In this aspect, the spacing between the scanning lines can be set arbitrarily. Further, the above-mentioned three-dimensional image can be formed by sufficiently narrowing the interval between adjacent scanning lines (three-dimensional scanning). The same applies to vertical scans.

The cross scan scans the measurement light LS along a cross-shaped locus composed of two linear loci (straight loci) orthogonal to each other. The radial scan scans the measurement light LS along a radial locus composed of a plurality of linear trajectories arranged at a predetermined angle. The cross scan is an example of a radiation scan.

The circular scan scans the measurement light LS along a circular locus. In the concentric circle scan, the measurement light LS is scanned along a plurality of circular loci arranged concentrically around a predetermined center position. The circle scan is an example of a concentric circle scan. The spiral scan scans the measurement light LS along a spiral (spiral) trajectory while gradually reducing (or increasing) the radius of gyration.

Since the galvano scanner 42 is configured to scan the measurement light LS in the directions orthogonal to each other, the measurement light LS can be scanned independently in the x direction and the y direction, respectively. Further, by simultaneously controlling the orientations of the two galvano mirrors included in the galvano scanner 42, it is possible to scan the measurement light LS along an arbitrary locus on the xy plane. Thereby, various scanning modes as described above can be realized.

By scanning the measurement light LS in the above manner, it is possible to obtain a tomographic image on the plane stretched by the direction along the scanning line (scanning locus) and the fundus depth direction (z direction). Further, especially when the interval between scanning lines is narrow, the above-mentioned three-dimensional image can be acquired.

The region on the fundus Ef to be scanned by the measurement light LS as described above, that is, the region on the fundus Ef to be scanned by OCT measurement is called a scanning region. The scanning area in the three-dimensional scan is a rectangular area in which a plurality of horizontal scans are arranged. The scanning region in the concentric scan is a disk-shaped region surrounded by the locus of the circular scan having the maximum diameter. The scanning area in the radiation scan is a disk-shaped (or polygonal) area connecting both end positions of each scan line.

[motion]
The operation of the ophthalmologic imaging apparatus 1 will be described. FIG. 9 shows an example of the process executed by the ophthalmologic imaging apparatus 1 in the preliminary operation executed before the OCT measurement (and fundus photography). In this example, a case where the preliminary operation is executed in the order of alignment, coarse focus adjustment, auto Z, Z lock, Z lock position change processing, polarization adjustment, and fine focus adjustment will be described.

(S1: Acquisition of anterior segment image started)
First, in response to a predetermined operation for starting the preliminary operation, the main control unit 211 turns on the observation light source 11. As a result, acquisition of a frontal image (near infrared moving image) of the anterior segment of the eye E to be inspected is started. This front image is obtained in real time until the observation light source 11 is turned off. The main control unit 211 causes the display unit 241 to display the front image as a moving image in real time.

(S2: Alignment)
The main control unit 211 controls the alignment optical system 50 to project the alignment index on the eye E to be inspected. At this time, the fixation target by the LCD 39 is also projected on the eye E to be inspected. The optical system movement amount acquisition unit 231 analyzes the frames (for example, all frames) acquired at predetermined time intervals, and acquires the movement amount of the optical system. The main control unit 211 controls the optical system drive unit 500 and moves the optical system by the amount of movement. The main control unit 211 repeatedly executes this process.

(S3: coarse focus adjustment)
When the alignment is completed, the main control unit 211 starts the coarse focus adjustment. Specifically, the main control unit 211 starts acquiring the front image of the fundus Ef, controls the focus optical system 60, and projects the split index on the fundus Ef. The photographing focusing lens movement amount acquisition unit 232 analyzes the frames (for example, all frames) acquired at predetermined time intervals, and acquires the movement amount of the focusing lens 31. The main control unit 211 controls the photographing focusing drive unit 300 to move the focusing lens 31 by the moving amount. Here, when the photographing focusing lens movement amount acquisition unit 232 also acquires the movement amount of the focusing lens 43, the main control unit 211 controls the OCT focusing drive unit 400 to move the focusing lens 43 by the movement amount. Move. The main control unit 211 repeatedly executes this process.

When the small pupil determination described above is performed, the main control unit 211 receives the completion of the coarse focus adjustment and executes the determination.

(S4: Acquisition of OCT image started)
Upon receiving the completion of the coarse focus adjustment (or determination of the small pupil), or after the completion of the predetermined operation, the main control unit 211 starts the OCT measurement. In this OCT measurement, as described above, substantially the same cross section of the fundus Ef is repeatedly scanned at a predetermined frequency.

(S5: Auto Z)
The main control unit 211 executes the auto Z based on the OCT image (or the reflection intensity profile or the like) whose acquisition was started in step S4.

(S6: Start Z lock)
Following the success of Auto Z, the main control unit 211 initiates Z lock.

(S7: Start monitoring the image position)
With the start of the Z lock, the main control unit 211 starts a monitor for changing the Z lock position. In this monitoring process, as described above, the position of the image of the eye E to be inspected (image area R, surface area R1, etc.) in the frame of the OCT image in the z direction is monitored. In this example, the case where the distance Δz1 between the surface region R1 corresponding to the retina surface and the upper end of the frame is calculated will be described, but in other cases (for example, when the above distance Δz2 is calculated). Can also perform similar processing.

(S8: Distance Δz1 ≤ threshold value?)
As described above, the determination unit 234 determines whether the distance Δz1 is equal to or less than the threshold value. When the polarization adjustment (S10) is started without determining that the distance Δz1 is equal to or less than the threshold value (S8: No), the process continues as it is.

(S9: Change the reference z position)
On the other hand, when it is determined that the distance Δz1 is equal to or less than the threshold value before the polarization adjustment (S10) is started (S8: Yes), the main control unit 211 changes the current reference z position to a new reference z position. To do. This process corresponds to changing the position of the slider H shown in FIG. 7A and the like. The new reference z position is, for example, located on the upper end side of the frame with respect to the current reference z position. Further, the distance between the current reference z position and the new reference z position may be, for example, the same as the displacement amount of the image with respect to the current reference z position. This displacement amount is acquired, for example, as the displacement between the reference z position and the image region R. Step S7 and step S8 are continued even after the reference z position is changed, and when it is determined again as "Yes" in step S8, the reference z position is changed again.

(S10: Polarization adjustment started)
Upon receiving the trigger for shifting to the polarization adjustment, the main control unit 211 starts the polarization adjustment. Also in this stage, the monitor process started in step S7 is being executed in parallel.

(S11: Distance Δz1 ≤ threshold value?)
The determination unit 234 determines whether the distance Δz1 is equal to or less than the threshold value. When the polarization adjustment is completed without determining that the distance Δz1 is equal to or less than the threshold value (S11: No), the process proceeds to step S13.

(S12: Change the reference z position)
On the other hand, when it is determined that the distance Δz1 is equal to or less than the threshold value before the completion of the polarization adjustment (S11: Yes), the main control unit 211 changes the current reference z position to a new reference z position. This process may be the same as in step S9.

(S13: Start fine focus adjustment)
Upon receiving the trigger for shifting to the fine focus adjustment, the main control unit 211 starts the fine focus adjustment. Also in this stage, the monitor process started in step S7 is being executed in parallel.

(S14: Distance Δz1 ≦ threshold value?)
The determination unit 234 determines whether the distance Δz1 is equal to or less than the threshold value. When the fine focus adjustment is completed without determining that the distance Δz1 is equal to or less than the threshold value (S14: No, S16), the preliminary operation is completed, and the ophthalmologic imaging apparatus 1 performs OCT measurement (main measurement) of the fundus Ef. Move to a viable state.

(S15: Change the reference z position)
On the other hand, when it is determined that the distance Δz1 is equal to or less than the threshold value before the end of the fine focus adjustment (S14: Yes), the main control unit 211 changes the current reference z position to a new reference z position. This process may be the same as in step S9.

(S16: Fine focus adjustment is completed)
When the fine focus adjustment is completed, the preliminary measurement is completed, and the ophthalmologic imaging apparatus 1 shifts to a state in which the OCT measurement (main measurement) of the fundus Ef can be performed.

[effect]
The effect of the ophthalmologic imaging apparatus according to the embodiment will be described.

The ophthalmologic imaging apparatus according to the embodiment has a function of repeatedly acquiring data by repeatedly scanning the eye E to be inspected using OCT. This function includes an interferometric optical system for performing OCT. The interference optical system includes a light source unit (101), a sample arm that guides the measurement light (LS), a reference arm that guides the reference light (LR), and a detector (spectrometer) that detects the interference light (LC). It includes a balanced photodiode or the like) and components (image forming unit 220 or the like) that process the detection result of the interference light. These correspond to an example of the data acquisition unit.

Further, the ophthalmologic imaging apparatus according to the embodiment includes a control unit that executes the following first control and second control. In the first control, the control unit sets the sample arm and the reference arm so that the image of the eye to be inspected is arranged at the reference position (reference z position) in the frame based on the data repeatedly acquired by the data acquisition unit. Adjust the optical path length difference between them. The first control includes, for example, auto Z and Z lock. Further, in the second control, the control unit samples so that the image of the eye to be inspected is arranged at a new reference position (new reference z position) of the frame based on the data repeatedly acquired by the data acquisition unit. Change the optical path length difference between the arm and the reference arm. In the above embodiment, the control unit that executes these controls includes at least the control unit 210, and further includes a part of the data processing unit 230.

According to such an embodiment, even when the region of interest is drawn at the edge of the imaging range (frame) or deviates from the frame due to the movement of the eye to be inspected, the reference position is automatically changed to the region of interest. Can be visualized at a suitable position. In addition, the drawing position of the attention portion can be automatically corrected before the attention portion is actually drawn at an inappropriate position. Therefore, it is possible to preferably perform a preliminary operation for OCT measurement of the eye to be inspected, and to acquire an OCT image in which a region of interest is depicted at a suitable position in the frame.

In the embodiment, the control unit may include a determination unit. The determination unit determines whether or not to execute the second control based on the data repeatedly acquired by the data acquisition unit when one or more preliminary operations for performing the OCT measurement of the eye to be inspected are being executed. To do. In the above embodiment, a part of the data processing unit 230 corresponds to the determination unit. Further, examples of the preliminary operation include polarization adjustment for adjusting the polarization state of the measurement light and / or reference light, and focus fine adjustment for adjusting the focus of the sample arm.

According to such an embodiment, the reference position can be automatically adjusted in parallel with the preliminary operation executed before the OCT measurement (main measurement).

In the embodiment, the determination unit is calculated as a first distance calculation unit (optical path length difference change amount acquisition unit 233) for calculating the distance between the image of the predetermined portion of the eye to be inspected and the upper end or the lower end of the frame. It may include a first distance determination unit (determination unit 234) for determining whether the distance is equal to or less than a predetermined threshold value. In this case, the control unit is configured to execute the second control in response to the determination that the distance is equal to or less than the threshold value.

As a specific example of such an embodiment, the threshold value may be zero. As another specific example, the predetermined portion may be the surface of the retina, and the first distance calculation unit may be configured to calculate the distance between the image of the surface of the retina and the upper end of the frame. Further, the control unit may be configured to perform a second control so as to set a new reference position on the upper end side of the frame with respect to the current reference position.

In the embodiment, the determination unit defaults to a second distance calculation unit (optical path length difference change amount acquisition unit 233) for calculating the distance between the image of the predetermined portion of the eye to be inspected and the reference position, and the calculated distance. It may include a second distance determination unit (determination unit 234) for determining whether or not the distance is equal to or greater than the threshold value of. In this case, the control unit is configured to execute the second control in response to the determination that the distance is equal to or greater than the threshold value.

As a specific example of such an embodiment, the control unit is configured to execute a second control so as to set a new reference position on the side of the image in the predetermined portion in the displacement direction with respect to the current reference position. You can. As another specific example, the predetermined site may be a predetermined layer tissue (for example, retinal pigment epithelial layer) of the retina of the eye to be examined.

[Modification example]
The configuration described above is only an example for preferably carrying out the present invention. Therefore, any modification (omission, substitution, addition, etc.) within the scope of the gist of the present invention can be appropriately applied.

In the above embodiment, the reference z position is changed so that the site of interest such as the retinal pigment epithelial layer is arranged at a suitable position in the frame, but the present invention is not limited thereto. For example, it is possible to change the reference z position so as to move an image of a portion that does not need to be observed or an image that interferes with observation to the end of the frame or to the outside. Such processing includes, for example, a process of specifying a predetermined image area by analyzing an OCT image or a reflection intensity profile, and a process of moving the specified image area to the end of a frame or to the outside of a reference z position. It includes a process of obtaining a movement amount and a process of changing the optical path length difference between the sample arm and the reference arm based on the obtained movement amount.

As a specific example, a case where a mirror image (mirror image) is mixed in the OCT image will be described while applying the configuration of the above embodiment mutatis mutandis. In this example, the iterative OCT measurement described in the above embodiment is performed. The data processing unit 230 (mirror image specifying unit) identifies an image region (mirror image region) corresponding to the mirror image by analyzing frames that are sequentially input. Further, the data processing unit 230 calculates the distance between a predetermined end region (a one-dimensional, two-dimensional or three-dimensional region including at least the upper end or the lower end of the frame) in the frame and a mirror image region. This distance includes at least the distance in the z direction. Further, an arbitrary position in the mirror image region can be obtained as the position of the mirror image region. For example, when moving the mirror image region to the upper end side of the frame, the position of the lower end of the mirror image region can be adopted (in this case, the entire mirror image region can be moved to the end region). The main control unit 211 moves the reference z position by the required distance. As a result, the second control can be executed so that the mirror image region is arranged at a new reference position located near the edge of the frame or outside the frame, and the situation where the mirror image region interferes with the observation is avoided. It becomes possible to do.

In addition, it is assumed that it is difficult to achieve both the second control according to the above embodiment and the second control according to the present modification. For example, it is conceivable that a mirror image is generated at the site of interest. In such a case, which second control is prioritized is arbitrary. For example, it is possible to preferentially execute the second control according to the above embodiment, and further execute other processing for removing, thinning, or moving the mirror image.

A computer program for realizing the above embodiment can be stored in any computer-readable recording medium. Examples of the recording medium include semiconductor memory, optical disk, magneto-optical disk (CD-ROM / DVD-RAM / DVD-ROM / MO, etc.), magnetic storage medium (hard disk / floppy (registered trademark) disk / ZIP, etc.) and the like. Can be used.

It is also possible to send and receive this program through a network such as the Internet or LAN.

1 Ophthalmic imaging device 2 Fundus camera unit 10 Illumination optical system 30 Imaging optical system 31 Focusing lens 41 Optical path length change unit 42 Galvano scanner 50 Alignment optical system 60 Focus optical system 100 OCT unit 101 Light source unit 105 Light attenuator 106 Polarization adjustment Instrument 115 CCD image sensor 200 Calculation control unit 210 Control unit 211 Main control unit 212 Storage unit 220 Image formation unit 230 Data processing unit 231 Optical system movement amount acquisition unit 232 Photographing focusing lens movement amount acquisition unit 233 Optical path length difference change amount acquisition Unit 234 Judgment unit 235 Image quality judgment unit 241 Display unit 242 Operation unit 300 Shooting focusing drive unit 400 OCT Focusing drive unit 500 Optical system drive unit E Eye to be inspected Ef Funds LS Measurement light LR Reference light LC Interference light

Claims (4)

A data acquisition unit that repeatedly acquires data by repeatedly scanning the eye to be inspected using optical coherence tomography.
Based on the data repeatedly acquired by the data acquisition unit, between the sample arm and the reference arm in the interference optical system for optical coherence stromography so that the image of the eye to be inspected is placed at a reference position in the frame. The optical path is executed so that the first control for adjusting the optical path length difference is executed, and the image of the eye to be inspected is arranged at a new reference position of the frame based on the data repeatedly acquired by the data acquisition unit. It is equipped with a control unit that executes a second control that changes the length difference.
The control unit executes the second control based on the data repeatedly acquired by the data acquisition unit when one or more preliminary operations for performing optical coherence tomography of the eye to be inspected are being executed. Includes a determination unit that executes processing to determine whether or not to do
The one or more preliminary operations are at least one of the polarization adjustment and the focus adjustment of the interference optical system.
The determination unit
A first distance calculation unit that calculates the distance between the image of a predetermined portion of the eye to be inspected and the upper end or the lower end of the frame, and
A first distance determination unit that determines whether the distance calculated by the first distance calculation unit is equal to or less than a predetermined threshold value, and
Including
The control unit executes the second control in response to the determination by the first distance determination unit that the distance is equal to or less than the threshold value.
The predetermined site is the surface of the retina of the eye to be inspected.
The first distance calculation unit calculates the distance between the image of the retinal surface and the upper end of the frame.
The ophthalmologic imaging apparatus, characterized in that the control unit executes the second control so as to set the new reference position on the upper end side of the frame with respect to the reference position. A data acquisition unit that repeatedly acquires data by repeatedly scanning the eye to be inspected using optical coherence tomography.
Based on the data repeatedly acquired by the data acquisition unit, between the sample arm and the reference arm in the interference optical system for optical coherence stromography so that the image of the eye to be inspected is placed at a reference position in the frame. The optical path is executed so that the first control for adjusting the optical path length difference is executed, and the image of the eye to be inspected is arranged at a new reference position of the frame based on the data repeatedly acquired by the data acquisition unit. It is equipped with a control unit that executes a second control that changes the length difference.
The control unit executes the second control based on the data repeatedly acquired by the data acquisition unit when one or more preliminary operations for performing optical coherence tomography of the eye to be inspected are being executed. Includes a determination unit that executes processing to determine whether or not to do
The one or more preliminary operations are at least one of the polarization adjustment and the focus adjustment of the interference optical system.
The determination unit
A second distance calculation unit that calculates the distance between the image of the predetermined portion of the eye to be inspected and the reference position, and
A second distance determination unit that determines whether the distance calculated by the second distance calculation unit is equal to or greater than a predetermined threshold value, and
Including
The ophthalmologic imaging apparatus, characterized in that the control unit executes the second control in response to the determination by the second distance determination unit that the distance is equal to or greater than the threshold value. The second aspect of claim 2, wherein the control unit executes the second control so as to set the new reference position on the side of the reference position in the displacement direction of the image of the predetermined portion. Ophthalmic imaging device. The ophthalmologic imaging apparatus according to claim 2 or 3, wherein the predetermined site is a predetermined layer tissue of the retina of the eye to be inspected.

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