JP6761519B2 - Ophthalmologic imaging equipment - Google Patents

Description

The present invention relates to an ophthalmologic imaging apparatus.

Optical coherence tomography (OCT) is used to form an image showing the surface morphology and internal morphology of an object to be measured. In the OCT image acquired by using OCT, artifacts due to reflection from an object other than the object to be measured or the coherence revival phenomenon may appear. These artifacts may appear overlapping the region of interest or may affect the results of image processing such as segmentation processing.

For example, an antireflection coating may be applied to an optical member constituting an interference optical system for acquiring an OCT image to remove artifacts caused by reflection from an object other than the object to be measured. Further, there is known a method of removing artifacts by performing phase modulation on light from a light source so as to suppress the occurrence of a coherence revival phenomenon (Patent Document 1).

U.S. Patent Application Publication No. 2014/0029015

However, even when the optical member is coated with a reduced reflection coating, it is difficult to completely suppress the reflection. Further, in the method disclosed in Patent Document 1, it is necessary to design according to the optical conditions such as the type and arrangement of the optical members constituting the optical system, which complicates the design of the optical system and the control system.

In general, the longer the coherence length, the more likely it is that artifacts due to reflections from objects other than the object under test will appear in the OCT image. In addition, the shorter the coherence revival interval, the more likely the artifacts caused by the coherence revival phenomenon will appear in the OCT image. Therefore, when a light source having a long coherence length or a light source having a short coherence revival interval is used, the image quality of the OCT image is likely to deteriorate, and a new technique for removing the above-mentioned artifacts is required.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a new technique for removing artifacts appearing in an image acquired by using an interference optical system. ..

The ophthalmologic imaging apparatus of the embodiment includes an objective lens, an interference optical system, an optical scanner, a fixation target projection system, and a control unit. The interference optical system divides the light from the light source into the measurement light and the reference light, causes the measurement light to enter the eye to be inspected through the objective lens, emits the light from the eye to be inspected, and is the return light of the measurement light that has passed through the objective lens. Detects interference light with reference light. The optical scanner deflects the measurement light. The fixation target projection system projects the fixation target onto the fundus of the eye to be inspected. The control unit controls the scanning position of the measurement light by controlling the optical scanner in the first coordinate system, and controls the position of the fixation target by controlling the fixation target projection system in the second coordinate system. The control unit changes at least one of the relative position of the first coordinate system with respect to the optical axis of the objective lens and the relative position of the second coordinate system with respect to the optical axis.

According to the present invention, it becomes possible to provide a new technique for removing artifacts appearing in an image acquired by using an interference optical system.

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 the schematic which shows an example of the structure of the ophthalmologic imaging apparatus which concerns on embodiment. It is a schematic diagram for demonstrating the operation of the ophthalmologic imaging apparatus which concerns on the comparative example of Embodiment. It is a schematic diagram for demonstrating the operation of the ophthalmologic imaging apparatus which concerns on the comparative example of Embodiment. It is the schematic for demonstrating the operation of the ophthalmologic imaging apparatus which concerns on embodiment. It is a flow chart which shows the flow of the operation example of the ophthalmologic imaging apparatus which concerns on embodiment. It is the schematic for demonstrating the operation of the ophthalmologic imaging apparatus which concerns on embodiment. It is the schematic for demonstrating the operation of the ophthalmologic imaging apparatus which concerns on the modification of embodiment. It is the schematic for demonstrating the ophthalmologic imaging apparatus which concerns on the modification of embodiment.

An example of an embodiment of the present invention will be described in detail with reference to the drawings. The ophthalmologic imaging apparatus according to the present invention has a function of an optical coherence tomography and performs OCT on the eye to be inspected. This OCT is performed on any part of the eye to be inspected, such as the fundus or anterior segment of the eye.

In this specification, the images acquired by OCT may be collectively referred to as OCT images. In addition, noise may be equated with an artifact. In addition, the contents of the documents cited in this specification can be incorporated as the contents of the following embodiments.

In the following embodiments, an ophthalmologic imaging apparatus capable of performing Fourier domain type OCT will be described. In particular, the ophthalmologic imaging apparatus according to the embodiment can apply the Swept source type OCT method. It is also possible to apply the configuration according to the present invention to an ophthalmologic imaging apparatus capable of performing OCT of a type other than the Swept source type, for example, a spectral domain type. Further, in the following embodiment, an apparatus in which an OCT apparatus and a fundus camera are combined will be described. However, it is also possible to combine a modality other than the fundus camera, for example, an SLO (Scanning Laser Ophthalmoscope), a slit lamp, a microscope for ophthalmic surgery, a photocoagulation device, and the like with an OCT device having the configuration according to the embodiment. It is also possible to incorporate the configuration according to the embodiment into a single OCT device.

[Constitution]
As shown in FIG. 1, 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 has an optical system substantially similar to that of a conventional fundus camera. The OCT unit 100 is provided with an optical system for executing OCT. The arithmetic control unit 200 includes a computer that executes various arithmetic processes, control processes, and the like.

[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 the illumination light to the image pickup apparatus (CCD image sensor (sometimes simply referred to as CCD) 35, 38). Further, the photographing optical system 30 guides the measurement light from the OCT unit 100 to the eye E to be inspected, and guides the measurement light passing through the eye E to be inspected to the OCT unit 100.

The observation light source 11 of the illumination optical system 10 is composed of, for example, a halogen lamp or an LED (Light Emitting Diode). 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.

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 33A, 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 or an LED. 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 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 inspected, 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 33A, 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 fixation position of the eye E to be inspected can be changed.

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 focusing (focusing) on the eye E to be inspected.

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 33A, 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 performs the alignment by performing the same operation as the conventional fundus camera. Further, the arithmetic control unit 200 may analyze the position of the alignment index and move the optical system to perform alignment (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 arithmetic control unit 200 analyzes the position of the split index and moves the focusing lens 31 and the focus optical system 60 to focus (autofocus function) as in the conventional case. Further, the focus may be manually performed while visually recognizing the split index.

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

The optical path length changing unit 41 is movable in the direction of the arrow shown in FIG. 1, and changes the optical path length of the optical path for OCT. This change in the optical path length 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 optical scanner 42 is arranged at a position optically conjugate with the pupil of the eye E to be inspected. The optical scanner 42 changes the traveling direction of the light (measurement light LS) passing through the optical path for OCT. Thereby, the eye E to be inspected can be scanned with the measurement light LS. The optical scanner 42 includes, for example, a galvano mirror that scans the measurement light LS in the x direction, a galvano mirror that scans the measurement light LS in the y direction, and a mechanism that independently drives them. Thereby, the measurement light LS can be scanned in any direction on the xy plane.

[OCT unit]
An example of the configuration of the OCT unit 100 is shown in FIG. The OCT unit 100 is provided with an optical system for acquiring an OCT image of the eye E to be inspected. This optical system has the same configuration as a conventional Swept source type OCT device. That is, this optical system divides the light from the wavelength sweep type (wavelength scanning type) light source into the measurement light and the reference light, and separates the return light of the measurement light from the eye E to be examined and the reference light via the reference optical path. It is an interference optical system that causes interference to generate interference light and detects this interference light. The detection result (detection signal) of the interference light by the interference optical system is a signal showing the spectrum of the interference light, and is sent to the arithmetic control unit 200.

The light source unit 101 is configured to include a wavelength sweep type (wavelength scanning type) light source capable of sweeping (scanning) the wavelength of the emitted light, similarly to a general Swept source type OCT device. The wavelength sweep type light source is configured to include a laser light source including a resonator. The light source unit 101 changes the output wavelength with time in a near-infrared wavelength band that is invisible to the human eye.

The light L0 output from the light source unit 101 is guided by the optical fiber 102 to the polarization controller 103, and its polarization state is adjusted. The polarization controller 103 adjusts the polarization state of the light L0 guided in the optical fiber 102 by, for example, applying stress from the outside to the looped optical fiber 102.

The light L0 whose polarization state is adjusted by the polarization controller 103 is guided by the optical fiber 104 to the fiber coupler 105 and divided into the measurement light LS and the reference light LR.

The reference light LR is guided by the optical fiber 110 to the collimator 111 to become a parallel luminous flux. The reference light LR that has become a parallel luminous flux is guided to the corner cube 114 via the optical path length correction member 112 and the dispersion compensation member 113. The optical path length correction member 112 acts as a delay means for matching the optical path length (optical distance) of the reference light LR with the optical path length of the measurement light LS. The dispersion compensating member 113 acts as a dispersion compensating means for matching the dispersion characteristics between the reference light LR and the measurement light LS.

The corner cube 114 turns back the traveling direction of the reference light LR, which has become a parallel luminous flux by the collimator 111, in the opposite direction. The optical path of the reference light LR incident on the corner cube 114 and the optical path of the reference light LR emitted from the corner cube 114 are parallel. Further, the corner cube 114 is movable in the direction along the incident optical path and the outgoing optical path of the reference light LR. This movement changes the length of the optical path of the reference light LR.

In the configurations shown in FIGS. 1 and 2, the optical path length changing unit 41 for changing the length of the optical path (measurement optical path, measurement arm) of the measurement light LS and the optical path of the reference light LR (reference optical path, reference). Both corner cubes 114 for changing the length of the arm) are provided, but one of them may be provided. It is also possible to change the difference between the measured optical path length and the reference optical path length by using an optical member other than these.

The reference light LR passing through the corner cube 114 is converted from a parallel luminous flux to a focused luminous flux by a collimator 116 via a dispersion compensating member 113 and an optical path length correcting member 112, is incident on the optical fiber 117, and is guided to the polarization controller 118. Then, the polarization state of the reference light LR is adjusted.

The polarization controller 118 has, for example, the same configuration as the polarization controller 103. The reference light LR whose polarization state is adjusted by the polarization controller 118 is guided to the attenuator 120 by the optical fiber 119, and the amount of light is adjusted under the control of the arithmetic control unit 200. The reference light LR whose light amount is adjusted by the attenuator 120 is guided to the fiber coupler 122 by the optical fiber 121.

On the other hand, the measurement light LS generated by the fiber coupler 105 is guided by the optical fiber 127 and is converted into a parallel luminous flux by the collimator lens unit 40. The measurement light LS converted into a parallel luminous flux reaches the dichroic mirror 46 via the optical path length changing unit 41, the optical 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 eye E to be inspected. The measurement light LS is scattered (including reflection) at various depth positions of the eye E to be inspected. The return light of the measurement light LS including such backscattered light travels in the same path as the outward path in the opposite direction, is guided to the fiber coupler 105, and reaches the fiber coupler 122 via the optical fiber 128.

The fiber coupler 122 combines (interferes with) the measurement light LS incidented through the optical fiber 128 and the reference light LR incidented via the optical fiber 121 to generate interference light. The fiber coupler 122 generates a pair of interference light LCs by branching the interference light between the measurement light LS and the reference light LR at a predetermined branching ratio (for example, 1: 1). The pair of interference light LCs emitted from the fiber coupler 122 are guided to the detector 125 by the optical fibers 123 and 124, respectively.

The detector 125 is, for example, a balanced photodiode (Balanced Photo Diode) that has a pair of photodetectors that detect each pair of interference light LCs and outputs the difference between the detection results. The detector 125 sends the detection result (detection signal) to the DAQ (Data Acquisition System) 130. A clock KC is supplied to the DAQ 130 from the light source unit 101. The clock KC is generated in the light source unit 101 in synchronization with the output timing of each wavelength swept (scanned) within a predetermined wavelength range by the wavelength sweep type light source. The light source unit 101 optically delays one of the two branched lights obtained by branching the light L0 of each output wavelength, and then sets the clock KC based on the result of detecting the combined light. Generate. The DAQ130 samples the detection result of the detector 125 based on the clock KC. The DAQ 130 sends the detection result of the sampled detector 125 to the arithmetic control unit 200. The arithmetic control unit 200 obtains a reflection intensity profile in each A line by, for example, performing a Fourier transform or the like on the spectral distribution based on the detection result obtained by the detector 125 for each series of wavelength scans (for each A line). Form. Further, the arithmetic control unit 200 forms image data by imaging the reflection intensity profile of each A line.

[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 detector 125 to form an OCT image of the eye E to be inspected. The arithmetic processing for that purpose is the same as that of the conventional Swept source 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. For example, the arithmetic control unit 200 causes the display device 3 to display the OCT image of the eye E to be inspected.

The arithmetic control unit 200 includes, for example, a processor, a RAM (Random Access Memory), a ROM (Read Only Memory), a hard disk drive, a communication interface, and the like. 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 processor is, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), a programmable logic device (for example, a SPLD (Specle Program Programmable Cable)). (Field Programmable Gate Array)) and the like. 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 realizes the function according to the embodiment by reading and executing a program stored in a storage circuit or a storage device, for example.

[Control system]
The configuration of the control system of the ophthalmologic imaging apparatus 1 will be described with reference to FIG. In addition, in FIG. 3, some components of the ophthalmologic imaging apparatus 1 are omitted, and components particularly necessary for explaining this embodiment are selectively shown.

(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 processor, 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, as shown in FIG. 3, the main control unit 211 includes the imaging focusing drive unit 31A of the fundus camera unit 2, the CCD image sensors 35 and 38, the LCD 39, the optical path length changing unit 41, the optical scanner 42, and the OCT focusing drive. The unit 43A and the like are controlled. Further, the main control unit 211 controls the light source unit 101 of the OCT unit 100, the reference drive unit 114A, the detector 125, the DAQ 130, and the like.

The photographing focusing drive unit 31A moves the focusing lens 31 in the optical axis direction. As a result, the focusing position of the photographing optical system 30 is changed. The main control unit 211 can control an optical system drive unit (not shown) to move the optical system provided in the fundus camera unit 2 three-dimensionally. This control is used in alignment and tracking. Tracking is to move the optical system of the device according to the movement of the eye E to be inspected. When performing tracking, alignment and focusing are performed in advance. Tracking maintains a suitable positional relationship in which alignment and focus are achieved by moving the device optical system in real time according to the position and orientation of the eye E to be inspected based on an image obtained by capturing a moving image of the eye E to be inspected. It is a function.

The OCT focusing drive unit 43A moves the focusing lens 43 along the optical axis of the measurement optical path. 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 reference drive unit 114A moves the corner cube 114 provided in the reference optical path. As a result, the length of the reference optical path is changed. As described above, the configuration may be such that only one of the optical path length changing unit 41, the corner cube 114, and the reference driving unit 114A is provided.

The main control unit 211 changes the display position of the fixation target on the screen of the LCD 39 by designating a desired position in the fixation target coordinate system and controlling the LCD 39. The fixation target coordinate system is a two-dimensional Cartesian coordinate system (xy coordinate system) associated with the coordinate system defined for the screen of the LCD 39. The main control unit 211 can change the relative position of the fixation target coordinate system with respect to the optical axis of the objective lens 22.

For example, the main control unit 211 controls the display position of the fixation target on the LCD 39 so that the desired position in the predetermined control coordinate system (device coordinate system) becomes the origin of the fixation target coordinate system, thereby controlling the objective lens. The relative position of the fixation target coordinate system with respect to the optical axis of 22 is changed. In this case, the storage unit 212 stores in advance the reference position information 212A for setting the origin of the fixation target coordinate system to the initial position (X0, Y0) in the control coordinate system. For example, the initial position (X0, Y0) is a position on the optical axis of the objective lens 22. Further, in the storage unit 212, adjustment information 212B including an offset amount (Δx0, Δy0) in both axial directions obtained by adjusting the origin position of the fixation target coordinate system performed in the shipping process or the maintenance process is ex post facto. It is saved in. The main control unit 211 reads the reference position information 212A and the adjustment information 212B from the storage unit 212, and fixes the LCD 39 so that the new position (X0 + Δx0, Y0 + Δy0) in the control coordinate system becomes the origin of the fixation target coordinate system. Control the display position of the mark. That is, the main control unit 211 can control the LCD 39 by changing the position deviated from the optical axis of the objective lens 22 to the fixation target coordinate system centered on the control center.

Further, the main control unit 211 changes the scan position and the scan range of the measurement optical LS by controlling the optical scanner 42 by designating a desired position in the scanner coordinate system. The scanner coordinate system is a two-dimensional Cartesian coordinate system (xy coordinate system) associated with the coordinate system defined for the measurement site of the eye E to be examined. The main control unit 211 can change the relative position of the scanner coordinate system with respect to the optical axis of the objective lens 22.

For example, the main control unit 211 controls the scan position with respect to the eye E to be inspected so that the desired position in the predetermined control coordinate system becomes the origin of the scanner coordinate system, so that the scanner coordinate system with respect to the optical axis of the objective lens 22 Change the relative position. In this case, the storage unit 212 stores in advance the reference position information 212A for setting the origin of the scanner coordinate system to the initial position (X1, Y1) in the control coordinate system. For example, the initial positions (X1, Y1) are positions on the optical axis of the objective lens 22 (X0 = X1 and Y0 = Y1). Further, the storage unit 212 stores the adjustment information 212B including the offset amount (Δx1, Δy1) in both axial directions obtained by adjusting the origin position of the scanner coordinate system performed in the shipping process and the maintenance process after the fact. Will be done. The main control unit 211 reads the reference position information 212A and the adjustment information 212B from the storage unit 212, and scans the scan position with respect to the eye E so that the new position (X1 + Δx1, Y1 + Δy1) in the control coordinate system becomes the origin of the scanner coordinate system. To control. That is, the main control unit 211 can control the optical scanner 42 so as to deflect the measurement light LS with the position deviated from the optical axis of the objective lens 22 as the control center.

The main control unit 211 can change the relative position of the fixation target coordinate system with respect to the optical axis of the objective lens 22 in conjunction with the above-mentioned change of the relative position of the scanner coordinate system. For example, the offset amount included in the adjustment information 212B is made the same (Δx0 = Δx1 and Δy0, Δy1), and the main control unit 211 changes the relative positions of both coordinate systems with respect to the optical axis of the objective lens 22. That is, the main control unit 211 can change the position of the fixation target coordinate system according to the displacement of the control center of the optical scanner 42 from the optical axis O of the objective lens 22. Further, for example, the initial positions of both coordinate systems included in the reference position information 212A are the same (X0 = X1 and Y0 = Y1), and the offset amount included in the adjustment information 212B is the same (Δx0 = Δx1, And it may be set to Δy0, Δy1). As a result, the main control unit 211 can change the relative positions of both coordinate systems with respect to the optical axis of the objective lens 22 in a state where the origin of the fixation target coordinate system and the origin of the scanner coordinate system coincide with each other. ..

Alternatively, the main control unit 211 may change the relative position of the fixation target coordinate system with respect to the optical axis of the objective lens 22 independently of the above-mentioned change of the relative position of the scanner coordinate system.

(Memory)
The storage unit 212 stores various types of data. The data stored in the storage unit 212 includes, for example, image data of an OCT image, image data of a fundus image, and eye information to be inspected, in addition to the above-mentioned reference position information 212A and adjustment information 212B. 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 cross-sectional image of the fundus Ef based on the detection signal from the detector 125 (DAQ130). That is, the image forming unit 220 forms the image data of the eye E to be inspected based on the detection result of the interference light LC by the interference optical system. This process includes processing such as filter processing and FFT (Fast Fourier Transform), as in the case of the conventional Swept source type OCT. The image data acquired in this way is a data set including a group of image data formed by imaging the reflection intensity profile in a plurality of A lines (paths of each measurement light LS in the eye E to be inspected). is there.

In order to improve the image quality, it is possible to superimpose (add and average) a plurality of data sets collected by repeating scanning with the same pattern a plurality of times.

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. In addition, the site of the eye E to be inspected and the image thereof may be equated.

(Data processing unit)
The data processing unit 230 performs various data processing (image processing) and analysis processing on the OCT image formed by the image forming unit 220. For example, the data processing unit 230 executes correction processing such as image brightness correction and dispersion 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 can form volume data (voxel data) of the eye E to be inspected by executing known image processing such as interpolation processing for interpolating pixels between cross-sectional images. When displaying an image based on volume data, the data processing unit 230 performs rendering processing on the volume data to form a pseudo three-dimensional image when viewed from a specific line-of-sight direction.

The data processing unit 230 can align the fundus image and the OCT image. When the fundus image and the OCT image are acquired in parallel, since both optical systems are coaxial, the fundus image and the OCT image acquired at (almost) simultaneously are taken as the optical axis of the photographing optical system 30. Can be aligned with reference to. Further, regardless of the acquisition timing of the fundus image and the OCT image, the alignment of the fundus image with the front image obtained by projecting at least a part of the image region corresponding to the fundus Ef of the OCT image onto the xy plane is performed. By doing so, it is also possible to align the OCT image and the fundus image. This alignment method can be applied even when the optical system for acquiring a fundus image and the optical system for OCT are not coaxial. Even if both optical systems are not coaxial, if the relative positional relationship between the two optical systems is known, the same alignment as in the case of coaxial is executed with reference to this relative positional relationship. It is possible.

The data processing unit 230 that functions as described above includes, for example, a processor, RAM, ROM, a hard disk drive, a circuit board, and the like. A computer program that causes the processor 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. 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.

The OCT unit 100, the collimator lens unit 40, the optical path length changing unit 41, the optical scanner 42, the focusing lens 43, the mirror 44, and the relay lens 45 are examples of the “interference optical system” according to this embodiment. The LCD 39, the half mirror 33A, the mirror 32, the focusing lens 31, the dichroic mirror 55, the perforated mirror 21, and the dichroic mirror 46 are examples of the “fixation target projection system” according to this embodiment. The LCD 39 is an example of the "light emitting unit whose light emitting position can be changed" according to this embodiment. The reference position information 212A is an example of "light emitting position information" according to this embodiment.

[Operation example]
The operation of the ophthalmologic imaging apparatus 1 will be described.

4A and 4B show explanatory views of comparative examples of the embodiments. FIG. 4A shows an explanatory diagram of the fixation target coordinate system and the scanner coordinate system in the comparative example. FIG. 4B schematically represents an OCT image obtained by the ophthalmologic imaging apparatus in the comparative example.

As shown in FIG. 4A, the origin of the scanner coordinate system SC is provided so as to coincide with the optical axis O of the objective lens 22. Such position adjustment is performed at the design stage, the shipping process, and the maintenance process. As a result, in the ophthalmologic imaging apparatus according to the comparative example, the alignment is performed so that the region of interest of the eye E to be inspected is arranged at the position of the optical axis O, and the frequency of imaging by scanning including the optical axis O increases.

However, in the OCT image IMG1 acquired by scanning including the optical axis O, as shown in FIG. 4B, the reflected light from the apex of the lens surface of the objective lens 22 may appear as artifact N1. For example, as shown in FIG. 4B, although the image was taken for the purpose of observing a tomographic image with the fovea CF as the site of interest, artifact N1 appeared near the site of interest, and observation near the site of interest in the image was observed. It gets harder. In this phenomenon, the longer the coherence length, the more likely the artifacts caused by the reflection from the optical system of the ophthalmologic imaging apparatus appear in the OCT image.

Therefore, in the embodiment, OCT is executed with the position deviated from the optical axis O of the objective lens 22 as the control center of the optical scanner 42.

FIG. 5 shows an explanatory diagram of the fixation target coordinate system and the scanner coordinate system in the embodiment. In FIG. 5, the same parts as those in FIG. 4A are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

As shown in FIG. 5, in the embodiment, the optical scanner 42 is controlled so that the position deviated from the optical axis O of the objective lens 22 is the origin of the scanner coordinate system SC. As a result, it becomes possible to acquire an OCT image in which no artifact appears in the vicinity of the region of interest. In particular, in an OCT image (OCT image acquired by scanning including the optical axis O) that is frequently photographed, detailed observation in the vicinity of the region of interest becomes possible.

Further, in the embodiment, the LCD 39 is controlled so that the origin of the scanner coordinate system SC becomes the origin of the fixation target coordinate system FC. As a result, by changing the display position of the fixation target by the LCD 39 and guiding the fixation position of the eye E to be inspected, it is possible to acquire an artifact-free image by scanning including the fovea centralis, which is frequently performed.

In this embodiment, the main control unit 211 controls the LCD 39 or the optical scanner 42 with an arbitrary position in the control coordinate system as the control center by using the reference position information 212A and the adjustment information 212B described above. As a result, not only the artifacts caused by the reflected light of the objective lens 22 but also the artifacts caused by the coherence revival phenomenon generated depending on the state of the optical system can be removed. The origin of the scanner coordinate system SC and the origin of the fixation target coordinate system FC may be adjusted to be provided at positions deviating from the optical axis O of the objective lens 22 at the design stage.

In the following, it is assumed that the initial position and the offset amount of both coordinate systems included in the reference position information 212A are the same. That is, the main control unit 211 has the fixation target coordinates in the same direction and the same offset amount with respect to the optical axis O of the objective lens 22 in a state where the origin of the fixation target coordinate system and the origin of the scanner coordinate system match. The position of the origin of the system FC and the position of the origin of the scanner coordinate system SC shall be changed.

FIG. 6 shows a flow chart of an operation example of the ophthalmologic imaging apparatus 1. This operation example includes an image-based alignment process of the eye E to be inspected and the device optical system, and an image-based scan area setting process. The alignment process includes alignment (autoalignment), focusing (autofocus), and tracking (autotracking) for OCT measurement.

(S1)
First, the coordinate system is adjusted so that the origin of the fixation target coordinate system and the origin of the scanner coordinate system are located outside the optical axis O of the objective lens 22. In S1, the adjustment information 212B is determined and the determined adjustment information 212B is stored in the storage unit 212.

For example, the main control unit 211 controls the optical scanner 42 so that the position specified based on the reference position information 212A becomes the origin of the scanner coordinate system, and scans the fundus Ef with respect to a predetermined scan range. The image forming unit 220 forms an OCT image based on the collected data obtained by sampling the detection signal obtained by the detector 150. The formed OCT image is displayed on the display unit 241. The user changes the position of the origin of the scanner coordinate system by setting the offset amount (Δx, Δy) using the operation unit 242 while observing the OCT image displayed on the display unit 241. Next, the next OCT image is acquired in a state where the position of the origin of the scanner coordinate system is changed, the acquired OCT image is displayed on the display unit 241, and this is repeated. As a result, the user can determine the offset amount that is determined to be appropriate. The determined offset amount is stored in the storage unit 212 as the adjustment information 212B.

Alternatively, for example, the data processing unit 230 determines the presence or absence of an artifact by analyzing the acquired OCT image or the interference signal based on the interference light while increasing or decreasing the offset amount in a predetermined step, thereby determining the appropriateness. The amount of offset to be made may be determined.

In S1, the offset amount is preferably determined as follows.

FIG. 7 is an explanatory diagram of the offset amount according to the embodiment. FIG. 7 schematically represents a projection image of the eye E to be inspected. The artifact AF is depicted in the projection image IMG2. Assuming that the radius of the artifact AF is r, it is desirable that the offset amounts Δx and Δy are larger than the radius r (Δx> r and Δy> r). That is, the displacement amount of the control center of the optical scanner 42 with respect to the optical axis O of the objective lens 22 is set based on the size of the artifact in the deflection direction of the light LS measured by the optical scanner 42. In FIG. 7, the artifact AF appears in the tomographic image acquired at the scan line G1, but the artifact AF appears in the tomographic image acquired at the scan line G1'shifted by d (d> r) in the y direction. Does not appear.

(S2)
Next, acquisition of a near-infrared moving image of the fundus Ef is started by continuously illuminating the fundus Ef with the illumination light from the observation light source 11 (which becomes near-infrared light by the visible cut filter 14). This near-infrared moving image is obtained in real time until the end of continuous illumination. The image of each frame constituting this moving image is temporarily stored in the frame memory (storage unit 212) and sequentially sent to the data processing unit 230.

An alignment index by the alignment optical system 50 and a split index by the focus optical system 60 are projected on the eye E to be inspected. Therefore, the alignment index and the split index are drawn on the near-infrared moving image. Alignment and focusing can be performed using these indexes. In addition, a fixation target by LCD 39 is also projected on the eye E to be inspected. The subject is instructed to stare at this fixation target.

(S3)
The data processing unit 230 sequentially analyzes the frames obtained by photographing the eye E to be inspected as a moving image by the optical system, obtains the position of the alignment optotype, and calculates the movement amount of the optical system. The control unit 210 performs auto-alignment by controlling an optical system drive unit (not shown) based on the movement amount of the optical system calculated by the data processing unit 230.

(S4)
The data processing unit 230 sequentially analyzes the frames obtained by photographing the eye E to be inspected as a moving image by the optical system, obtains the position of the split optotype, and calculates the amount of movement of the focusing lens 31. The control unit 210 performs autofocus by controlling the photographing focusing drive unit 31A based on the movement amount of the focusing lens 31 calculated by the data processing unit 230.

(S5)
Subsequently, the control unit 210 starts auto-tracking. Specifically, the data processing unit 230 monitors the movement (change in position) of the eye E to be inspected by analyzing the frames sequentially obtained by photographing the eye E to be inspected as a moving image in real time by the optical system. The control unit 210 controls an optical system drive unit (not shown) so as to move the optical system according to the position of the eye E to be inspected, which is sequentially acquired. As a result, the optical system can be made to follow the movement of the eye E to be inspected in real time, and it is possible to maintain a suitable positional relationship in which alignment and focus are in focus.

(S6)
The control unit 210 causes the display unit 241 to display a near-infrared moving image in real time. The user sets a scan region on this near-infrared moving image by using the operation unit 242. The scan area to be set may be a one-dimensional area or a two-dimensional area.

When the scan mode of the measurement light LS and the region of interest (optic disc, macula, lesion, etc.) are preset, the control unit 210 sets the scan region based on these settings. It is also possible to configure. Specifically, the region of interest is specified by image analysis by the data processing unit 230, and the region of a predetermined pattern is set so that the control unit 210 includes the region of interest (for example, the region of interest is located at the center). Set.

(S7)
The control unit 210 controls the light source unit 101 and the optical path length changing unit 41, and controls the optical scanner 42 based on the scan area set in S5 to perform OCT measurement of the fundus Ef.

The image forming unit 220 forms a tomographic image (image) of the A line based on the collected data obtained by sampling the detection signal obtained by the detector 150 based on the clock KC as described above. To do. When the scanning mode is a three-dimensional scan, the data processing unit 230 forms a three-dimensional image of the fundus Ef based on a plurality of tomographic images formed by the image forming unit 220. This is the end of this operation example (end).

[Modification example]
(First modification)
In the above-described embodiment, the case where the origin of the fixation target coordinate system FC and the origin of the scanner coordinate system SC are changed to a position deviated from the optical axis O of the objective lens 22 has been described, but the ophthalmologic imaging apparatus according to the embodiment has been described. The configuration is not limited to this. For example, only the origin of the scanner coordinate system SC may be changed to a position deviated from the optical axis O of the objective lens 22.

FIG. 8 shows an explanatory diagram of the fixation target coordinate system and the scanner coordinate system in the first modification of the embodiment. In FIG. 8, the same parts as those in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

As shown in FIG. 8, in the first modification, the LCD 39 is controlled so that the position of the objective lens 22 on the optical axis O is the origin of the fixation target coordinate system FC, and the position deviated from the optical axis O is the scanner. The optical scanner 42 is controlled so as to be the origin of the coordinate system SC. According to the first modification, it is possible to acquire an OCT image in which no artifact appears in the vicinity of the region of interest, as in the above-described embodiment.

(Second modification)
FIG. 9 shows a main part of the configuration of the ophthalmologic imaging apparatus in the second modification of the embodiment. In FIG. 9, only the space between the eye E to be inspected and the objective lens 22 in FIG. 1 is shown.

The ophthalmologic imaging apparatus according to the second modification includes a front lens 23 that can be arranged between the objective lens 22 and the eye E to be inspected. The front lens 23 can be manually or automatically arranged between the objective lens 22 and the eye E to be inspected. When the front lens 23 is arranged between the objective lens 22 and the eye E to be inspected, the present invention is applied by replacing the "objective lens" in the above-described embodiment with the "front lens" regarding the control of the coordinate system. Is possible. For example, when the front lens 23 is arranged between the objective lens 22 and the eye E to be inspected, the main control unit emits light so as to deflect the measurement light around a position deviated from the optical axis of the front lens 23. It is possible to control the scanner 42. Similarly, the main control unit can control the LCD 39 so that the position deviated from the optical axis of the front lens 23 becomes the origin of the fixation target coordinate system.

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

The ophthalmologic imaging apparatus (ophthalmic imaging apparatus 1) according to the embodiment includes an objective lens (objective lens 22), an interference optical system (optical system from the OCT unit 100 to the relay lens 45), and an optical scanner (optical scanner 42). , A control unit (control unit 210, main control unit 211) and an image forming unit (image forming unit 220) are included. The interference optical system divides the light (light L0) from the light source (light source unit 101) into the measurement light (measurement light LS) and the reference light (reference light LR), and the measurement light is passed through the objective lens to the eye to be inspected (light L0). Interference light (interference light LC) between the return light of the measurement light emitted from the eye to be inspected and passed through the objective lens and the reference light is detected. The optical scanner deflects the measurement light. The control unit controls the optical scanner so as to deflect the measurement light around a position deviated from the optical axis (optical axis O) of the objective lens. The image forming unit forms an image of the eye to be inspected based on the detection result of the interference light by the interference optical system.

With such a configuration, it is possible to acquire an image of the eye to be inspected in which no artifact appears in the vicinity of the region of interest. In particular, in an image with a high frequency of imaging that includes the optical axis of the objective lens, detailed observation of the vicinity of the region of interest becomes possible. Further, it is possible to remove not only the artifacts caused by the reflected light of the objective lens but also the artifacts caused by the coherence revival phenomenon generated depending on the state of the optical system.

Further, the ophthalmologic imaging apparatus according to the embodiment includes a fixation target projection system (optical system from LCD 39 to the dichroic mirror 46) that projects the fixation target onto the fundus (fundus Ef) of the eye to be inspected, and the control unit is an optical system. The fixation target projection system may be controlled together with the control of the scanner.

According to such a configuration, by moving the fixation position of the eye to be inspected, detailed observation in the vicinity of the region of interest becomes possible at a position away from the appearance position of the artifact caused by the reflected light of the objective lens.

Further, in the ophthalmologic imaging apparatus according to the embodiment, the fixation target projection system includes a light emitting unit (LCD 39) whose light emitting position can be changed, projects light from the light emitting unit onto the fundus of the eye to be inspected, and emits light by the light emitting unit. A storage unit (storage unit 212) that stores light emission position information (reference position information 212A) indicating a position in advance may be included, and the control unit may change the light emission position information to control the fixation target projection system.

According to such a configuration, the display position of the fixation target can be changed according to the control of the optical scanner with a simple configuration and control.

Further, in the ophthalmologic imaging apparatus according to the embodiment, the control unit may change the light emitting position information according to the displacement of the control center of the optical scanner from the optical axis of the objective lens.

According to such a configuration, by changing the display position of the fixation target to guide the fixation position of the eye to be inspected, it is possible to acquire an artifact-free image by scanning including the fovea centralis, which is frequently performed.

Further, in the ophthalmologic imaging apparatus according to the embodiment, the displacement amount (Δx or Δy) of the control center of the optical scanner with respect to the optical axis of the objective lens is based on the size (radius r) of the artifact in the deflection direction of the light measured by the optical scanner. May be set.

With such a configuration, it is possible to acquire an image in which no artifact is drawn with high accuracy.

Further, the ophthalmologic photographing apparatus according to the embodiment includes a front lens that can be arranged between the objective lens and the eye to be inspected, and when the front lens is arranged between the objective lens and the eye to be inspected, the control unit. May control the optical scanner to deflect the measurement light around a position off the optical axis of the front lens.

With such a configuration, it is possible to observe the vicinity of the region of interest in detail in an image that is frequently photographed and includes the optical axis of the front lens. Further, it is possible to remove not only the artifacts caused by the reflected light of the front lens but also the artifacts caused by the coherence revival phenomenon generated depending on the state of the optical system.

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. The configuration to be applied is selected, for example, according to the purpose. In addition, depending on the configuration to be applied, the effects that are obvious to those skilled in the art and the effects described in the present specification can be obtained.

1 Ophthalmology imaging device 2 Fundus camera unit 22 Objective lens 23 Front lens 42 Optical scanner 100 OCT unit 200 Calculation control unit 210 Control unit 211 Main control unit 212 Storage unit 220 Image formation unit 230 Data processing unit E Eye to be inspected

Claims (4)

With the objective lens
The light from the light source is divided into a measurement light and a reference light, the measurement light is incident on the eye to be inspected through the objective lens, and the return light of the measurement light emitted from the eye to be inspected and passed through the objective lens. An interference optical system that detects interference light with the reference light,
An optical scanner that deflects the measurement light,
The fixation target projection system that projects the fixation target onto the fundus of the eye to be inspected,
Control to control the scan position of the measurement light by controlling the optical scanner in the first coordinate system, and control the position of the fixation target by controlling the fixation target projection system in the second coordinate system. Department and
Including
The control unit is an ophthalmologic imaging apparatus that changes at least one of the relative position of the first coordinate system with respect to the optical axis of the objective lens and the relative position of the second coordinate system with respect to the optical axis. Claim 1 is characterized in that the control unit changes the relative position of the first coordinate system with respect to the optical axis by controlling the scan position so that a predetermined position in the third coordinate system becomes a reference. The ophthalmologic imaging apparatus described in. The control unit is characterized in that the relative position of the second coordinate system with respect to the optical axis is changed by controlling the position of the fixation target so that a predetermined position in the third coordinate system becomes a reference. The ophthalmologic imaging apparatus according to claim 1 or 2. The control unit has at least a relative position of the first coordinate system with respect to the optical axis and a relative position of the second coordinate system with respect to the optical axis, based on the size of the artifact in the deflection direction of the measured light by the optical scanner. The ophthalmologic imaging apparatus according to any one of claims 1 to 3, wherein one of them is changed.

Images