JP2016144531A - Ophthalmologic apparatus, control method of the same, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mechanism capable of recognizing timing of blood flow information of a fundus of a subject eye in pulsation without requiring a sphygmograph.SOLUTION: An ophthalmologic apparatus comprises: an AO-SLO part 110 for scanning a fundus Er of a subject eye E using illumination light 106-1, and imaging a first area of the fundus Er while correcting aberration of the subject eye E; a WF-SLO part 120 for scanning the fundus Er of the subject eye E using measurement light 106-2, and imaging a second area of the fundus Er, which is wider than the first area; and a computer 125 for calculating first blood flow information in at least one position of the first area using the images obtained from the imaging by the AO-SLO part 110, calculating time fluctuation of second blood flow information based on Doppler signals obtained during the imaging by the WF-SLO part 120, and calculating timing of the first blood flow information in pulsation based on the time fluctuation of the second blood flow information.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ophthalmologic apparatus for imaging the fundus of a subject's eye, a control method therefor, and a program for causing a computer to execute the control method.

  A scanning laser opthalmoscope (SLO), which is an ophthalmologic apparatus that uses the principle of a confocal laser microscope, performs a raster scan on the fundus of the eye to be inspected, and performs an intensity scan of the returned light. It is a device that obtains a flat image from a high resolution and high speed. Hereinafter, an apparatus that captures such a planar image is referred to as an “SLO apparatus”.

  In recent years, it has become possible to acquire a planar image of the fundus with an improved resolution by increasing the beam diameter of the measurement light in the SLO apparatus to reduce the spot diameter with respect to the fundus. However, with the increase in the diameter of the measurement light beam, in the acquisition of a planar image of the fundus, the SN ratio and resolution of the planar image due to the aberration of the eye to be examined has become a problem.

  In order to solve this problem, an adaptive optics (AO) system in which the aberration of the eye to be examined is measured in real time by a wavefront sensor, and the aberration of the measurement light generated in the eye to be examined and its return light is corrected by a wavefront correction device. An adaptive optics SLO device having the following has been developed. Hereinafter, an adaptive optics SLO device having this adaptive optical system is referred to as an “AO-SLO device”.

  This AO-SLO device is capable of acquiring a high-resolution planar image, can observe the capillaries and photoreceptors in the fundus of the eye to be examined, and furthermore, by taking a video, the blood flow in the blood vessel can be observed. Dynamics can be observed. Non-Patent Document 1 discloses a technique for observing the movement of white blood cells in capillaries of the fundus and calculating the velocity thereof with an AO-SLO device. Since the blood flow velocity is calculated by observing the actual fundus blood flow in the capillaries of the fundus of the eye to be examined, the blood flow velocity can be calculated as an absolute value that can be displayed in physical units. By measuring the blood vessel diameter, an absolute blood flow rate can also be calculated.

  Here, it is known that the blood flow velocity changes with pulsation. At this time, if a change in blood flow velocity for one beat can be obtained by obtaining a plurality of blood flow velocities during one beat, the blood flow velocity obtained at a certain timing You can know if it is timing. Thereby, for example, normality / abnormality can be determined by comparing the blood flow velocity obtained at a certain timing with the reference value. However, since the AO-SLO device generally does not image a wide area of the fundus, the number of blood vessels contained in the imaging area is small, and thus blood is repeatedly generated during one beat. It is difficult to determine the flow velocity. Therefore, Patent Document 1 discloses that a pulse wave meter is attached to the earlobe of a subject in order to know the timing during pulsation when the velocity of white blood cells is similarly calculated by the AO-SLO device. Yes.

JP 2013-169308 A

J. et al. A. Martin and A.M. Roorda, "Direct and non-invasive assessment of paracapological capsule", Ophthalmology 112, 2219-2224 (2005).

  However, as in the technique described in Patent Document 1 described above, in the method of knowing the pulsation by attaching the sensor of the pulse wave meter to the earlobe or the fingertip or the like, the pulse separately from the SLO device. A wavemeter must be prepared, which makes the system expensive. Further, there is a problem that it is troublesome for the subject to wear the sensor unit of the pulse wave meter.

  The present invention has been made in view of such problems, and grasps the timing of blood flow information such as the blood flow velocity and blood flow of the fundus of the eye to be examined during pulsation without requiring a pulse wave meter. The purpose is to provide a mechanism that can do this.

The ophthalmologic apparatus according to the present invention includes a first imaging unit that scans the fundus of the eye to be examined using the first illumination light, corrects the aberration of the eye to be examined, and images the first area of the fundus. A second imaging unit that scans the fundus using the second illumination light to capture a second area of the fundus that is wider than the first area, and obtained by imaging by the first imaging unit. The first blood flow information at at least one position in the first area is calculated using an image, and is a signal obtained at the time of imaging by the second imaging means. The time variation of the second blood flow information is calculated based on the Doppler signal due to the return light from the fundus of the illumination light, and the first blood flow in pulsation is calculated based on the time variation of the second blood flow information. Calculating means for calculating the timing of information.
According to another aspect of the ophthalmologic apparatus of the present invention, the first imaging that scans the fundus of the subject's eye using the first illumination light and corrects the aberration of the subject's eye to capture the first area of the fundus. Means, a second imaging unit that scans the fundus using the second illumination light and images the second area of the fundus including the first area, and imaging by the first imaging unit The first blood flow information at the position of at least one of the first areas is calculated using the obtained image, and the second blood flow obtained at the time of imaging by the second imaging means Calculating means for calculating the timing of the first blood flow information in the pulsation based on the time variation of the information.
The present invention also includes a method for controlling the above-described ophthalmologic apparatus and a program for causing a computer to execute the control method.

  According to the present invention, it is possible to grasp the timing of blood flow information on the fundus of the eye to be examined during pulsation without the need for a pulse wave meter.

It is a figure which shows an example of schematic structure of the ophthalmologic apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the display surface of the fixation lamp shown in FIG. It is a figure which shows an example of an internal structure of the computer shown in FIG. FIG. 5 is a diagram illustrating an embodiment of the present invention and illustrating a method for acquiring a planar image (AO-SLO image) in an AO-SLO unit illustrated in FIG. It is a figure which shows an example of the positional relationship of the detector in the WF-SLO part shown in FIG. 6 is a flowchart illustrating an example of a control method according to a procedure for blood flow measurement in the fundus of the eye to be examined in the ophthalmologic apparatus according to the embodiment of the present invention. FIG. 6 is a flowchart illustrating an example of a control method according to a procedure for blood flow measurement in the fundus of the eye to be examined in the ophthalmologic apparatus according to the embodiment of the present invention, following FIG. It is a figure which shows embodiment of this invention and shows an example of the beat signal from the blood vessel obtained by the WF-SLO part shown in FIG. It is a figure which shows embodiment of this invention and shows an example of the time fluctuation of the sum Is of I, and the plot of Iv.

  Hereinafter, embodiments (embodiments) for carrying out the present invention will be described with reference to the drawings. In the embodiments of the present invention described below, an example in which the above-described SLO device is applied as an ophthalmologic apparatus according to the present invention will be described.

<Schematic configuration of ophthalmic apparatus>
FIG. 1 is a diagram illustrating an example of a schematic configuration of an ophthalmologic apparatus 100 according to an embodiment of the present invention.
As shown in FIG. 1, the ophthalmologic apparatus 100 includes an AO-SLO unit 110 and a WF-SLO unit 120.

  The AO-SLO unit 110 scans the fundus Er of the eye E using the measurement light 106-1 (first illumination light) and corrects the aberration of the eye E to image the first area of the fundus Er. It is the 1st imaging means to do. The AO-SLO unit 110 includes an adaptive optics system, and is for capturing a high-resolution planar image (AO-SLO image: first image) of the fundus oculi Er. In the present embodiment, the AO-SLO unit 110 can acquire an AO-SLO image by correcting the optical aberration of the eye E using the spatial light modulator 159, and the diopter and optical aberration of the eye E. Regardless of this, a good planar image can be obtained. Here, the AO-SLO unit 110 includes a compensation optical system in order to capture a high-resolution planar image. However, if the optical system has a configuration capable of realizing high resolution, the compensation optical system is not provided. Also good.

  The WF-SLO unit 120 scans the fundus Er of the eye E using the measurement light 106-2 (second illumination light) and captures a second area of the fundus Er that is wider than the first area. This is a second imaging means. The WF-SLO unit 120 is for capturing a wide-area (wide-angle) planar image (WF-SLO image: second image) of the fundus Er. Here, in this embodiment, the second area imaged by the WF-SLO unit 120 is an area larger than the first area imaged by the AO-SLO unit 110, but more preferably, the second area The area is an area including the first area.

<Overall of AO-SLO unit 110>
First, the entire AO-SLO unit 110 will be described.
The light emitted from the light source 101-1 is split into the reference light 105 and the measurement light 106-1 by the optical coupler 131. The measuring beam 106-1 is guided to the eye E to be inspected via the single mode optical fiber 130-4, the spatial light modulator 159, the XY scanner 119-1, the dichroic mirror 170-2, and the like. Further, the light beam 157 from the fixation lamp 156 has a role of promoting fixation of the eye E.

  The measurement light 106-1 becomes the return light 108 reflected or scattered by the eye E to be examined, travels backward in the optical path, and enters the detector 138-1 as a detector via the optical coupler 131. The detector 138-1 receives the return light 108 and converts the light intensity (light quantity) into a voltage signal. Using this voltage signal, an AO-SLO image that is a planar image of the eye E is generated in a personal computer (hereinafter simply referred to as “computer”) 125.

  In the present embodiment, the entire optical system is configured mainly using a refractive optical system using a lens, but it can also be configured by a reflective optical system using a spherical mirror instead of the lens. In this embodiment, the reflective spatial light modulator 159 is used as the aberration correction device. However, a transmissive spatial light modulator or a deformable mirror can also be used.

<Light source of AO-SLO unit 110>
Next, the periphery of the light source 101-1 will be described.
The light source 101-1 includes, for example, a super luminescent diode (SLD) that is a typical low-coherent light source. The wavelength of light from the light source 101-1 is about 830 nm, and the bandwidth is about 50 nm. In the present embodiment, a low coherent light source is used to obtain a planar image (AO-SLO image) with less speckle noise. In addition, although the SLD is used here as the light source 101-1, another type of light source may be used as long as low-coherent light can be emitted. For example, ASE (Amplified Spontaneous Emission) can be used.

  Moreover, since the light of the light source 101-1 measures the eye E, near infrared light is suitable. Furthermore, since the wavelength affects the resolution in the horizontal direction of the obtained planar image (AO-SLO image), it is desirable that the wavelength be as short as possible, and here it is about 830 nm. Other wavelengths may be selected depending on the measurement site to be inspected.

  The light emitted from the light source 101-1 is split into the reference light 105 and the measurement light 106-1 at a ratio of 96: 4, for example, via the single mode optical fiber 130-1 and the optical coupler 131. In addition, polarization controllers 153-1 to 153-4 are provided in the optical fibers 130-1 to 130-4, respectively.

<Optical Path of Reference Light 105 of AO-SLO Unit 110>
Next, the optical path of the reference beam 105 will be described.
The reference light 105 divided by the optical coupler 131 is incident on the light quantity measuring device 164 via the optical fiber 130-2. The light quantity measuring device 164 is used for the purpose of measuring the light quantity of the reference light 105 and monitoring the light quantity of the measurement light 106-1.

<Optical Path of Measuring Light 106-1 of AO-SLO Unit 110>
Next, the optical path of the measuring beam 106-1 will be described.
The measurement light 106-1 split by the optical coupler 131 is guided to the lens 135-4 via the single mode optical fiber 130-4 and adjusted to become parallel light having a beam diameter of about 4 mm.

  Then, the measurement light 106-1 passes through the beam splitter 158-1, passes through the lenses 135-5 to 135-6, and enters the spatial light modulator 159. The spatial light modulator 159 is controlled by the computer 125 via the spatial light modulator drive driver 181 in the driver unit 180.

  Next, the measurement light 106-1 is modulated by the spatial light modulator 159, passes through the lenses 135-7 to 135-8, and enters the mirror of the XY scanner 119-1. Here, for the sake of simplicity, the XY scanner 119-1 is illustrated as a single mirror, but in reality, two mirrors, an X scanner and a Y scanner, are arranged close to each other so as to move over the fundus Er. Raster scanning is performed in a direction perpendicular to the optical axis. Further, the center of the measuring beam 106-1 is adjusted to coincide with the rotation center of the mirror of the XY scanner 119-1.

  Here, the X scanner is a scanner that scans the measuring beam 106-1 in a direction parallel to the paper surface. For example, a resonance scanner is used here. The driving frequency of this X scanner is about 7.9 kHz. The Y scanner is a scanner that scans the measuring beam 106-1 in a direction perpendicular to the paper surface. Here, for example, a galvano scanner is used. The drive waveform of this Y scanner is a sawtooth wave, the drive frequency is about 64 Hz, and the duty ratio is about 81%. The drive frequency of the Y scanner is an important parameter that determines the frame rate for capturing an AO-SLO image. The XY scanner 119-1 is controlled by the computer 125 via the optical scanner driving driver 182 in the driver unit 180.

Here, the above-described duty ratio will be described.
In general, the duty ratio is a ratio of on time to one cycle time when switching between on and off periodically. In this embodiment, scanning is performed using two scanners, an X scanner and a Y scanner, in order to acquire a two-dimensional image by the SLO unit. In sub-scanning, for example, to acquire one two-dimensional image. The scanning from the top to the bottom (on) and the operation of quickly returning from the bottom to the top without acquiring a two-dimensional image after the scanning (off) are switched. At this time, the duty ratio in the present embodiment indicates the ratio of the time of scanning from the top to the bottom (on) with respect to the time of all scanning (on + off) that scans from top to bottom and returns to the top. Note that the larger the duty ratio, the shorter the time during which a two-dimensional image is not acquired for all scans. Therefore, when the scan time is the same, the number of frames per second increases.

  The lenses 135-9 to 135-10 are optical systems for scanning the fundus oculi Er, and have a role of scanning the fundus Er using the measuring beam 106-1 as a fulcrum in the vicinity of the cornea Ec. The beam diameter of the measurement light 106-1 is about 4 mm, but the beam diameter may be increased in order to obtain a higher resolution optical image. Further, the electric stage 117 can move in the direction shown by the arrow, and the position of the accompanying lens 135-10 can be adjusted. The electric stage 117 is controlled by the computer 125 via the electric stage driving driver 183 in the driver unit 180. By adjusting the position of the lens 135-10, the measurement light 106-1 can be focused on a predetermined layer of the fundus Er of the eye E to be observed. Moreover, it can respond also to the case where the eye E has a refractive error.

  Then, when the measurement light 106-1 is incident on the eye E, it becomes return light 108 due to reflection and scattering from the fundus Er, and is guided again to the optical coupler 131, via the single mode optical fiber 130-3, and the detector 138-1. To reach. As the detector 138-1, for example, an APD (Avalanche Photo Diode) or a PMT (Photomultiplier Tube) which is a high-speed and high-sensitivity optical sensor can be used. Here, it is assumed that APD is used as detector 138-1.

  Further, the return light 108 is modulated again by the spatial light modulator 159. Further, part of the return light 108 divided by the beam splitter 158-1 is incident on the wavefront sensor 155, and the aberration of the return light 108 generated by the eye E is measured. The wavefront sensor 155 is electrically connected to the computer 125. Here, the cornea Ec, the XY scanner 119-1, the wavefront sensor 155, and the spatial light modulator 159 are arranged with lenses 135-5 to 135-10 and the like so as to be optically conjugate. Therefore, the wavefront sensor 155 can measure the aberration of the eye E. The spatial light modulator 159 can correct the aberration of the eye E. Further, the computer 125 corrects the aberration generated in the eye E by controlling the spatial light modulator 159 in real time based on the aberration obtained from the measurement result of the wavefront sensor 155, and has a higher lateral resolution. A planar image (AO-SLO image) can be acquired.

  Although the lens 135-10 is a spherical lens, a cylindrical lens may be used instead of the spherical lens depending on the aberration (abnormal refraction) of the eye E. Further, a new lens may be added to the optical path of the measurement light 106-1.

  Here, the measurement light 106-1 is used to measure the aberration using the wavefront sensor 155, but another light source may be used to measure the aberration. Further, another optical path may be configured for measuring the aberration. For example, light for measuring aberration can be incident between the spherical lens 135-10 and the cornea Ec using a beam splitter.

  The fixation lamp 156 includes a light emitting display module, and has a display surface (□ 27 mm, 128 pixels × 128 pixels) on the YZ plane. Here, a liquid crystal, an organic EL, an LED array, or the like can be used. By causing the eye E to be inspected with the light beam 157 from the fixation lamp 156, fixation of the eye E is promoted.

FIG. 2 is a diagram showing an example of the display surface of the fixation lamp 156 shown in FIG.
For example, as shown in FIG. 2, a cross pattern 165 blinks and is displayed at an arbitrary lighting position on the display surface of the fixation lamp 156.

  A light beam 157 from the fixation lamp 156 is guided to the fundus Er via the lenses 135-13 to 135-14, the dichroic mirror 170-2, and the lens 135-10. The lenses 135-10, 135-13, and 135-14 are arranged so that the display surface of the fixation lamp 156 and the fundus Er are optically conjugate. The fixation lamp 156 is controlled by the computer 125 via the fixation lamp driving driver 184 in the driver unit 180.

<Internal configuration of computer 125>
Next, the internal configuration of the computer 125 will be described.
FIG. 3 is a diagram showing an example of the internal configuration of the computer 125 shown in FIG.
As shown in FIG. 3, the computer 125 includes a CPU 211, a RAM 212, a ROM 213, an external memory 214, an input device 215, a display unit 216, a communication interface (communication I / F) 217, and an AD board 176. ing. 3 are configured to be able to communicate with each other via a bus.

  For example, the CPU 211 performs overall control of the operation of the computer 125 using programs and data stored in the ROM 213 or the external memory 214. The RAM 212 includes an area for temporarily storing programs and data loaded from the ROM 213 or the external memory 214, and a work area required for the CPU 211 to perform various processes. The ROM 213 stores information such as programs that do not need to be changed and various parameters. The external memory 214 stores, for example, an operating system (OS), a program executed by the CPU 211, and information known in the description of the present embodiment. In the present embodiment, the program for executing the processing according to the embodiment of the present invention is stored in the external memory 214. However, for example, the program stored in the ROM 213 is also applicable. Is possible. The input device 215 includes, for example, switches (including a power switch), buttons, a mouse, a keyboard, and the like provided in the computer 125. The display unit 216 displays various images and information based on the control of the CPU 211. The communication I / F 217 controls transmission / reception of various information and the like performed between the computer 125 and the external device G (in this example, each component configured in the ophthalmologic apparatus 100). The AD board 176 converts the voltage signal obtained by the detector 138-1 or the detector 138-2 into a digital value based on the control of the CPU 211.

<Configuration of measurement system of AO-SLO unit 110>
Next, the configuration of the measurement system of the AO-SLO unit 110 will be described.
The AO-SLO unit 110 can acquire a planar image (AO-SLO image) composed of the light intensity (light quantity) of the return light 108 from the fundus Er. The return light 108 that is reflected or scattered by the fundus Er is incident on the detector 138-1 via the lenses 135-4 to 135-10, the spatial light modulator 159, the optical coupler 131, and the like. It is converted into a voltage signal based on the light intensity (light quantity).

  The voltage signal obtained by the detector 138-1 is converted into a digital value by the AD board 176 in the computer 125. Then, the computer 125 performs data processing on the digital value converted by the AD board 176 in synchronization with the operation and driving frequency of the XY scanner 119-1 to generate a planar image (AO-SLO image). Here, the capturing speed of the AD board 176 is about 15 MHz.

  Further, a part of the return light 108 split by the beam splitter 158-1 is incident on the wavefront sensor 155, and the aberration of the return light 108 is measured. The wavefront sensor 155 is, for example, a Shack-Hartmann wavefront sensor, and has a measurement range of −1D to + 1D, which has a narrow measurement range and high measurement accuracy. The aberration obtained by the wavefront sensor 155 is expressed using a Zernike polynomial, which indicates the aberration of the eye E. The Zernike polynomial includes a tilt term, a defocus term, an stigma (astigmatism) term, a coma term, a trifoil term, and the like.

<Acquisition method of AO-SLO image>
Next, a method for acquiring a planar image (AO-SLO image) will be described.
FIG. 4 shows an embodiment of the present invention, and is a diagram for explaining a method of acquiring a planar image (AO-SLO image) in the AO-SLO unit 110 shown in FIG. Here, in FIG. 4, the same code | symbol is attached | subjected about the structure similar to the structure shown in FIG.

  The AO-SLO unit 110 controls the XY scanner 119-1 based on the control of the computer 125, and acquires the light intensity (light quantity) of the return light 108 with the detector 138-1, whereby the planar image (AO- SLO image) can be acquired. Here, a method of acquiring a planar image of the fundus oculi Er (AO-SLO image related to a plane perpendicular to the optical axis) will be described.

  FIG. 4A is a schematic diagram of the measurement light 106-1 and the eye E to be examined, and shows a state being observed by the ophthalmologic apparatus 100. FIG. As shown in FIG. 4A, when the measurement light 106-1 is incident on the fundus Er through the cornea Ec of the eye E, the measurement light 106-1 becomes return light 108 due to reflection and scattering at various positions, and the detector 138-1 in FIG. To reach.

  Furthermore, as shown in FIG. 4B, if the light intensity of the return light 108 is detected while driving the XY scanner 119-1 in the X direction, information for each position of each X axis can be obtained.

  Further, as shown in FIG. 4C, the X-axis and Y-axis of the XY scanner 119-1 are simultaneously driven, and the measurement light 106-1 is shown as a locus 193 with respect to the imaging range 192 having the fundus Er. During the raster scan, the light intensity of the return light 108 is detected. Then, a two-dimensional distribution of the light intensity of the return light 108 is obtained, that is, a planar image (AO-SLO image) 177 shown in FIG.

  The measurement light 106-1 is scanned from the upper left point S shown in FIG. 4C toward the lower right point E, and the light intensity of the return light 108 in the meantime generates a planar image (AO-SLO image) 177. Used for. A trajectory 193 from the point E to the point S is a preparation for imaging the next plane image (AO-SLO image) 177. Here, the time required for scanning is about 81% for point S → point E and about 19% for point E → point S with respect to the locus 193 in FIG. This is based on the duty ratio of the driving waveform of the scanner. Further, in FIG. 4C, for the sake of simplicity, the number of scans in the X direction on the trajectory 193 is described slightly.

  Here, the planar image (AO-SLO image) 177 shown in FIG. 4D has a size of 700 μm × 350 μm, and the time required for acquisition is about 15.6 ms. This time is based on the drive frequency of the Y scanner. Further, in the planar image (AO-SLO image) 177 shown in FIG. 4D, the photoreceptor cell group 179 having a relatively large light intensity of the return light 108 is bright and the blood vessel having a relatively small light intensity of the return light 108. 178 is rendered dark. Further, white blood cells (not shown) are brightly depicted in the blood vessel 178.

<Whole WF-SLO unit 120>
Next, the entire WF-SLO unit 120 will be described.
The WF-SLO unit 120 has basically the same configuration as the AO-SLO unit 110 except that it does not include an adaptive optics and a reference optical path. For this reason, the description of the portions overlapping with the AO-SLO unit 110 is omitted here.

  The measurement light 106-2, which is light emitted from the light source 101-2, is to be inspected via the lenses 135-11 to 135-12, 135-2 and 135-1, the XY scanner 119-2, the dichroic mirror 170, and the like. To the eye E to be examined.

  The measurement light 106-2 becomes the return light 108 reflected or scattered by the eye E, travels backward in the optical path, and enters the detector 138-2 that is a detector via the beam splitter 158-2 and the like. The detector 138-2 receives the return light 108 and converts the light intensity (light quantity) into a voltage signal. Using this voltage signal, the computer 125 generates a WF-SLO image that is a wide-area planar image of the eye E.

<Light source of WF-SLO unit 120>
Next, the periphery of the light source 101-2 will be described.
The light source 101-2 is configured by an SLD, for example, similarly to the light source 101-1. The wavelength of light of the light source 101-2 is about 910 nm, and the bandwidth is about 10 nm. In the present embodiment, in order to separate the optical path of the AO-SLO unit 110 and the optical path of the WF-SLO unit 120 using the dichroic mirror 170, the wavelengths of the respective light sources are made different.

<Optical Path of Measuring Beam 106-2 of WF-SLO Unit 120>
Next, the optical path of the measuring beam 106-2 will be described.
The measurement light 106-2 emitted from the light source 101-2 is guided to the eye E to be examined through the lens 135-2, the XY scanner 119-2, the dichroic mirror 170-1, and the like.

  Here, the X scanner, which is a component of the XY scanner 119-2, is a scanner that scans the measurement light 106-2 in a direction parallel to the paper surface. Here, for example, a resonant scanner is used. The driving frequency of this X scanner is about 3.9 kHz. The Y scanner, which is a component of the XY scanner 119-2, is a scanner that scans the measuring beam 106-2 in a direction perpendicular to the paper surface. For example, a galvano scanner is used here. The drive waveform of this Y scanner is a sawtooth wave, the drive frequency is about 32 Hz, and the duty ratio is about 81%. The drive frequency of the Y scanner is an important parameter that determines the frame rate for capturing a WF-SLO image. The XY scanner 119-2 is controlled by the computer 125.

  The beam diameter of the measuring beam 106-2 is about 1 mm, but the beam diameter may be increased in order to obtain a higher resolution optical image.

  When the measurement light 106-2 is incident on the eye E, it becomes return light 108 due to reflection or scattering from the fundus Er, and the dichroic mirror 170-1, lens 135-1, XY scanner 119-2, beam splitter 158-2, etc. To the detector 138-2.

  FIG. 5 is a diagram showing an example of the positional relationship of the detector 138-2 in the WF-SLO unit 120 shown in FIG. Specifically, FIG. 5 shows an example of a substantial positional relationship among the incident measurement light 106-2, the fundus oculi Er, and the detector 138-2.

  In FIG. 5, a surface perpendicular to the fundus oculi Er is shown. As shown in FIG. 5, the detector 138-2 has an optical axis for receiving light (an optical axis for receiving the return light 108) tilted with respect to the optical axis of the measuring light 106-2 incident on the fundus Er. Placed in position. This is because the blood vessel of the fundus Er has many blood vessels along the fundus oculi, and when the measurement light 106-2 is perpendicularly incident on the fundus Er, the optical axis of the light received by the detector 138-2 is that of the measurement light 106-2. This is because if it coincides with the optical axis, the Doppler signal based on the return light 108 from the fundus Er of the measurement light 106-2 due to the blood flow of the blood vessel cannot be received. As described above, even if the detector 138-2 is arranged at a position where the optical axis of the received light is inclined with respect to the optical axis of the measurement light 106-2 incident on the fundus Er, the Doppler signal cannot be received depending on the direction of the blood vessel. However, it is sufficient if reception is possible in many cases. Further, the inclination angle may be any angle as long as the angle is known and does not deviate from the light receiving system.

<Acquisition method of WF-SLO image>
Next, a method for acquiring a wide area planar image (WF-SLO image) will be described.
The WF-SLO unit 120 controls the XY scanner 119-2 based on the control of the computer 125, and acquires the light intensity (light quantity) of the return light 108 with the detector 138-2, thereby obtaining a planar image of a wide area of the fundus Er ( WF-SLO image) can be acquired. Here, the method for acquiring a wide area planar image of the fundus oculi Er (WF-SLO image relating to a plane perpendicular to the optical axis) is the same as the method for acquiring the AO-SLO image described above, and thus the description thereof is omitted. .

<AO-SLO image acquisition procedure>
Here, a procedure for acquiring a planar image (AO-SLO image) using the AO-SLO unit 110 will be described.
First, the ophthalmic apparatus 100 (computer 125) uses the WF-SLO unit 120 to focus the measurement light 106-2 on the fundus Er and capture a WF-SLO image. The ophthalmologic apparatus 100 (computer 125) calculates the diopter of the eye E from the position of the electric stage 117 when focused. Further, when the examiner specifies a position where the AO-SLO image is desired to be acquired in the WF-SLO image, the ophthalmologic apparatus 100 (computer 125) displays the display position of the fixation lamp 156 based on the diopter of the eye E to be acquired. Is calculated and displayed, and an AO-SLO image at a desired position is acquired.

<Procedure for blood flow measurement>
Next, a control method according to the procedure of blood flow measurement in the fundus Er of the eye E to be examined by the ophthalmologic apparatus 100 will be described.

  6A and 6B are flowcharts illustrating an example of a control method related to a blood flow measurement procedure in the fundus Er of the eye E in the ophthalmologic apparatus 100 according to the embodiment of the present invention. The flowcharts illustrated in FIGS. 6A and 6B are performed by, for example, the CPU 211 in the computer 125 executing a program stored in the external memory 214, for example.

  When the examiner designates an imaging position in the AO-SLO unit 110 and inputs blood flow measurement start via the input device 215 of the computer 125, first, the CPU 211 of the computer 125 detects this. To do. In step S <b> 101 of FIG. 6A, the CPU 211 of the computer 125 starts scanning the WF-SLO unit 120 and the AO-SLO unit 110.

  Subsequently, in step S <b> 102 of FIG. 6A, the CPU 211 of the computer 125 controls the WF-SLO unit 120. Specifically, the CPU 211 of the computer 125 causes the detector 138-2 to receive the light reflected by the dichroic mirror 170-1 in the return light 108. Thereafter, the CPU 211 of the computer 125 generates a WF-SLO image for one frame based on the received light signal indicating the light amount acquired by the detector 138-2. Then, the CPU 211 of the computer 125 displays the generated WF-SLO image for one frame on the display unit 216 and stores the image data in, for example, the external memory 214.

  Subsequently, in step S <b> 103 of FIG. 6A, the CPU 211 of the computer 125 controls the AO-SLO unit 110. Specifically, the CPU 211 of the computer 125 causes the detector 138-1 to receive the light transmitted through the dichroic mirror 170-1 in the return light 108. Thereafter, the CPU 211 of the computer 125 generates an AO-SLO image for one frame based on the received light signal indicating the amount of light acquired by the detector 138-1. Then, the CPU 211 of the computer 125 displays the generated AO-SLO image for one frame on the display unit 216 and stores the image data in, for example, the external memory 214. In the present embodiment, the frame rates of the WF-SLO image and the AO-SLO image are about 26 and about 52, respectively. For this reason, in this embodiment, two frames of AO-SLO images can be acquired while one frame of WF-SLO images is acquired. Therefore, in this step, AO-SLO images of two frames are generated. Display and save.

  Subsequently, in step S104 of FIG. 6A, the CPU 211 of the computer 125 determines whether or not acquisition of an image for a predetermined frame is completed. Here, in the present embodiment, the WF-SLO image and the AO-SLO image are set to acquire images of 52 frames and 104 frames for 2 seconds of imaging, respectively. Note that other frame rates may be used as long as the scanning position for both times can be specified.

  As a result of the determination in step S104 in FIG. 6A, when the image acquisition for the specified frame has not been completed yet (S104 / NO), the process returns to step S102 in FIG. 6-1, and again in steps S102 and S103. Process.

On the other hand, as a result of the determination in step S104 in FIG. 6A, if the image acquisition for the specified frame is completed (S104 / YES), the process proceeds to step S105 in FIG.
When the process proceeds to step S105 in FIG. 6A, the CPU 211 of the computer 125 performs FFT (Fast Fourier Transform) processing of the received light signal at the detector 138-2 in each pixel for each frame of the WF-SLO image. Do. As a result of the FFT processing, a relationship between the spectrum S (f) with respect to the frequency f, that is, the amount of light is obtained. Then, from the pixel where the blood vessel of the fundus Er of the eye E has a beat signal of the Doppler signal based on the scattered light (return light 108) from the red blood cells in the flowing blood and the scattered light from the blood vessel wall. Appears in the lower part of the frequency.

  FIG. 7 is a diagram showing an example of a beat signal from a blood vessel obtained by the WF-SLO unit 120 shown in FIG. 1 according to the embodiment of the present invention. Here, when the blood flow velocity is high, the beat signal has a high frequency. The beat signal changes in the direction of the arrow in FIG. 7 according to the blood flow velocity.

  Subsequently, in step S106 of FIG. 6A, the CPU 211 of the computer 125 performs integration on the FFT signal at the target pixel at the frequency f represented by the following equation (1).

  In the formula (1), P is the total light amount received by the corresponding detector 138-2. As shown in the equation (1), by dividing by the total light amount P, the influence of the light intensity of the measurement light 106-2 or the return light 108 can be eliminated. Here, in this embodiment, the integration range is 100 Hz to 60 kHz. Since the influence of noise is large at a frequency close to 0 Hz, the minimum frequency is set to 100 Hz. Moreover, what is necessary is just to select sufficient frequency as a maximum frequency according to the blood flow velocity assumed and the angle of the inclination from the irradiation optical axis of the detector 138-2.

  Subsequently, in step S107 of FIG. 6A, the CPU 211 of the computer 125 sums up I of each pixel calculated in step S106 of FIG. Here, some I of each pixel have no blood vessel and no Doppler signal, and there are some that do not have a Doppler signal due to the balance between the direction of irradiation, the direction of light reception, and the direction of the blood vessel. You can add up to

  Subsequently, in step S108 of FIG. 6A, the CPU 211 of the computer 125 determines whether or not the above processing steps have been completed for all the pixels of the target frame. If the result of this determination is that the above processing steps have not been completed for all the pixels of the target frame (S108 / NO), the process returns to step S105 in FIG. 1 and subsequent steps S105 are performed.

On the other hand, when the above processing steps are completed for all the pixels of the target frame (S108 / YES), the process proceeds to step S109 in FIG.
When the process proceeds to step S109 in FIG. 6A, the CPU 211 of the computer 125 plots and displays the total Is of I with respect to the average time from the start of scanning to the target frame scanning.

  Subsequently, in step S110 of FIG. 6A, the CPU 211 of the computer 125 determines whether or not the processing has been completed for all the frames. If the result of this determination is that processing has not yet been completed for all frames (S110 / NO), processing returns to step S105 in FIG. 6-1, and processing for step S105 and subsequent steps in FIG. Process.

  On the other hand, as a result of the determination in step S110 in FIG. 6A, if the processing is completed for all frames (S110 / YES), the process proceeds to step S111 in FIG. At this time, the plot of 2 seconds is completed for the total Is of I, and the time variation of the total Is of I can be calculated as a time variation graph.

  FIG. 8 is a diagram illustrating an example of the present invention and an example of a time variation of I total Is and a plot of Iv. Here, as shown in FIG. 8A, a time variation graph is obtained by plotting the total Is of I for 2 seconds and connecting them with a line.

  When proceeding to step S111 in FIG. 6B, the CPU 211 of the computer 125 designates an AO-SLO image for a certain time and a place on a blood vessel (for example, a capillary) (here, a capillary) via the input device 215. , At least one location (position)) is determined. If the result of this determination is that the examiner has not specified an AO-SLO image for a certain period of time or a location on the blood vessel (S111 / NO), step S111 in FIG. Wait at.

On the other hand, as a result of the determination in step S111 of FIG. 6-2, if the examiner designates an AO-SLO image for a certain period of time and a place on the blood vessel (S111 / YES), FIG. Proceed to step S112.
When the process proceeds to step S112 in FIG. 6-2, the CPU 211 of the computer 125 uses the designated AO-SLO image and the preceding or succeeding AO-SLO image to determine the blood flow velocity at the location on the designated blood vessel. V is calculated by image processing that tracks white blood cells.

  Subsequently, in step S <b> 113 of FIG. 6B, the CPU 211 of the computer 125 determines whether or not the blood flow velocity calculation end is input from the examiner via the input device 215. If the result of this determination is that there is no input for the end of blood flow velocity calculation from the examiner (S113 / NO), processing returns to step S111 in FIG. 6-2, and processing from step S111 onward in FIG. 6-2 is performed.

On the other hand, as a result of the determination in step S113 in FIG. 6-2, if the examiner inputs the end of blood flow velocity calculation (S113 / YES), the process proceeds to step S114 in FIG.
When the processing proceeds to step S114 in FIG. 6B, the CPU 211 of the computer 125 calculates a ratio R between the total I of the corresponding times and the blood flow velocity V using the following equation (2). At this time, if there are a plurality of calculated ratios R, the average value Ra is further calculated. In addition, when the calculated ratio R is one, the ratio R is set as the average value Ra. Each corresponding time may be a time from the start of scanning to an intermediate point in time of scanning of the two AO-SLO image frames used for calculating the blood flow velocity V.

  Subsequently, in step S115 of FIG. 6-2, the CPU 211 of the computer 125 first calculates Iv by multiplying the blood flow velocity V by the average value Ra for each corresponding time using the following equation (3). To do. Next, the CPU 211 of the computer 125 plots the calculated Iv on the time variation graph of the total I of I plotted in step S109 of FIG. FIG. 8B shows an example in which two Ivs are plotted on the time variation graph of the total I of I shown in FIG.

  Subsequently, in step S116 of FIG. 6-2, the CPU 211 of the computer 125 detects pulsations from the time variation graph of the total I of I, obtains a range of integer pulsations, and in the range of the integer pulsations. The average value Isa of the total Is of I is calculated. Here, in the time fluctuation graph of the total I of I shown in FIG. 8B, two beats can be detected, and the range is shown by an arrow in FIG. 8C. In FIG. 8C, the minimum value in the time variation of the total I of Is is obtained for two beats. However, an integer number of beats such as a maximum value or an intermediate value between the maximum value and the minimum value are captured. Anything can be used.

  Subsequently, in step S117 of FIG. 6-2, the CPU 211 of the computer 125 calculates the average value Va of the blood flow velocity V in the integer pulsation range (within the integer pulsation) using the following equation (4). . In this step, for example, the average value Va of the blood flow velocity V for one beat including the timing of the blood flow velocity V (first blood flow information) in the time variation of the total I (second blood flow information) of I. Is calculated.

In the ophthalmologic apparatus 100 according to the present embodiment, the computer 125 (specifically, the CPU 211) uses the AO-SLO image obtained by the imaging by the AO-SLO unit 110 (first imaging means) and uses the AO-SLO image. A blood flow velocity V (first blood flow information) at at least one position in one area is calculated and a signal obtained at the time of imaging by the WF-SLO unit 120 (second imaging means). Then, based on the Doppler signal by the return light 108 from the fundus Er of the measurement light 106-2 (second illumination light), the time variation of the total Is (second blood flow information) of I is calculated. The timing Iv of the blood flow velocity V in the pulsation is calculated based on the time variation of the total Is. At this time, blood flow velocity V (first blood flow information) and I total Is (second blood flow information) are acquired at the same time.
According to such a configuration, it is possible to grasp the timing of blood flow information on the fundus Er of the eye E during pulsation without requiring a pulse wave meter. This makes it possible to determine normality / abnormality based on the obtained blood flow information while reducing the burden on the subject at low cost.

  In the present embodiment, the second area imaged by the WF-SLO unit 120 is larger than the first area imaged by the AO-SLO unit 110, but more preferably the second area. Is an area including the first area. This is because the first blood flow information and the second blood flow information are closer to each other in the second area including the first area than in the second area not including the first area. This is because the position accuracy information improves the calculation accuracy of the timing of the first blood flow information in the pulsation.

  Further, for example, in the method of attaching a pulse wave sensor to the earlobe or fingertip to know the pulsation, the distance from the heart is different from the fundus Er. The timing differs depending on the movement. For example, in the case of a fingertip, a difference of several tens of milliseconds may occur depending on the subject and the state of the subject. This difference may be as much as 10% in a steep portion of blood flow velocity fluctuation. In this regard, in this embodiment, since the pulsation in the fundus Er is used, there is no timing difference.

  In this embodiment, the average value Va of the blood flow velocity V in the integer pulsation range is calculated. However, the maximum value Vmax or the minimum value Vmin () of the blood flow velocity V in the integer pulsation range is calculated as necessary. For example, a form of calculating the maximum value Vmax or the minimum value Vmin of the blood flow velocity V for one beat, the difference between these, or the ratio thereof is also applicable to the present invention. Further, in step S115 of FIG. 6-2, the timing Iv is plotted on the Is time variation graph, and only the timing in the beat, such as whether the beat is at the maximum, minimum, or near the middle, is known. May be sufficient.

  In this embodiment, the integral value I is calculated for all the pixels of the entire WF-SLO image, and the total is performed. However, in order to simplify the calculation, a part of the WF-SLO image, for example, You may target the center part with high possibility that the blood vessel exists. Alternatively, the integral value I may not be calculated for all the pixels by thinning out all the pixels of the WF-SLO image, or extracting only that portion after recognizing the blood vessel by image processing.

In addition, as a method for recognizing a blood vessel, the following is also possible.
First, the blood flow fluctuation of each blood vessel is obtained, and if the magnitude of the fluctuation (for example, the ratio between the maximum value and the minimum value) is not less than a threshold value, it is determined as an artery, and if it is less than that, it is determined as a vein. Next, the target capillary is traced from the capillary to the determined artery or vein to determine whether it is an artery-side capillary or a vein-side capillary, and the corresponding blood vessel Use blood flow fluctuations. Thereby, it is possible to refer to a change in blood flow that is closer to a change in blood flow velocity of the target capillary.

  In the present embodiment, the first blood flow information calculated from the AO-SLO image is only the blood flow velocity V. However, in the present invention, the first blood flow information is not limited to this form. A form in which the blood flow volume is calculated by measuring (inner diameter of the blood vessel) is also included in the present invention.

  In addition, the number of cases where the Doppler signal cannot be received increases and the amount of data decreases, and the accuracy of blood flow fluctuations deteriorates. However, it is possible to adopt a normal arrangement in which the detector 138-2 is not inclined.

(Other embodiments)
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.
This program and a computer-readable storage medium storing the program are included in the present invention.

  Note that the above-described embodiments of the present invention are merely examples of implementation in practicing the present invention, and the technical scope of the present invention should not be construed as being limited thereto. It is. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

DESCRIPTION OF SYMBOLS 100 Ophthalmology apparatus, 101 Light source, 105 Reference light, 106 Measurement light, 108 Return light, 110 AO-SLO part, 117 Electric stage, 119 XY scanner, 120 WF-SLO part, 125 Computer, 130 Optical fiber, 131 Optical coupler, 135 Lens, 138 detector, 153 polarization controller, 155 wavefront sensor, 156 fixation lamp, 157 light beam, 158 beam splitter, 159 spatial light modulator, 164 light quantity measuring device, 170 dichroic mirror, 176 AD board, 180 driver unit, 181 space Optical modulator driver, 182 Optical scanner driver, 183 Motorized stage driver, 184 Fixation lamp driver, E Eye to be examined, Er fundus, Ec cornea

Claims (15)

First imaging means for scanning the fundus of the eye to be examined using the first illumination light and correcting the aberration of the eye to image the first area of the fundus;
Second imaging means for scanning the fundus using a second illumination light and imaging a second area of the fundus wider than the first area;
The first blood flow information at at least one position in the first area is calculated using an image obtained by imaging by the first imaging unit, and at the time of imaging by the second imaging unit The time fluctuation of the second blood flow information is calculated based on the Doppler signal obtained by the return light from the fundus of the second illumination light, and the time fluctuation of the second blood flow information. Calculating means for calculating the timing of the first blood flow information in a pulsation based on:
An ophthalmologic apparatus comprising:   The ophthalmologic apparatus according to claim 1, wherein the second area is an area including the first area.   The calculating means further calculates an average value of the first blood flow information of one beat including the timing of the first blood flow information in the time variation of the second blood flow information. The ophthalmic apparatus according to claim 1 or 2.   The calculating means further calculates the maximum value or the minimum value of the first blood flow information of one beat including the timing of the first blood flow information in the time variation of the second blood flow information. The ophthalmologic apparatus according to claim 1 or 2.   The ophthalmologic apparatus according to claim 1, wherein the first blood flow information and the second blood flow information are acquired at the same time.   The second imaging means includes a detector disposed at a position where an optical axis of light reception is inclined with respect to an optical axis of the second illumination light incident on the fundus. The ophthalmologic apparatus according to any one of claims 1 to 5. First imaging means for scanning the fundus of the eye to be examined using the first illumination light and correcting the aberration of the eye to image the first area of the fundus;
Second imaging means for imaging the second area of the fundus including the first area by scanning the fundus using second illumination light;
The first blood flow information at at least one position in the first area is calculated using an image obtained by imaging by the first imaging unit, and at the time of imaging by the second imaging unit Calculating means for calculating the timing of the first blood flow information in the pulsation based on the time variation of the second blood flow information obtained in
An ophthalmologic apparatus comprising: A method for controlling an ophthalmologic apparatus for imaging the fundus of a subject eye,
A first imaging step of scanning the fundus using the first illumination light and correcting the aberration of the eye to be examined and imaging the first area of the fundus using a first imaging unit;
A second imaging step of scanning the fundus using second illumination light and imaging a second area of the fundus wider than the first area using a second imaging unit;
The first blood flow information at at least one position in the first area is calculated using the image obtained by the imaging in the first imaging step, and at the time of imaging in the second imaging step The time fluctuation of the second blood flow information is calculated based on the Doppler signal obtained by the return light from the fundus of the second illumination light, and the time fluctuation of the second blood flow information. A calculation step of calculating the timing of the first blood flow information in a pulsation based on
A method for controlling an ophthalmic apparatus, comprising:   9. The method of controlling an ophthalmologic apparatus according to claim 8, wherein the second area is an area including the first area.   The calculating step further includes calculating an average value of the first blood flow information for one beat including the timing of the first blood flow information in the time variation of the second blood flow information. The control method of the ophthalmologic apparatus according to claim 8 or 9.   In the calculating step, the maximum value or the minimum value of the first blood flow information of one beat including the timing of the first blood flow information in the time variation of the second blood flow information is further calculated. 10. The method for controlling an ophthalmic apparatus according to claim 8 or 9.   The method for controlling an ophthalmologic apparatus according to any one of claims 8 to 11, wherein the first blood flow information and the second blood flow information are acquired at the same time. .   The second imaging means includes a detector disposed at a position where an optical axis of light reception is inclined with respect to an optical axis of the second illumination light incident on the fundus. The method for controlling an ophthalmologic apparatus according to any one of claims 8 to 12. A method for controlling an ophthalmologic apparatus for imaging the fundus of a subject eye,
A first imaging step of scanning the fundus using the first illumination light and correcting the aberration of the eye to be examined and imaging the first area of the fundus using a first imaging unit;
A second imaging step of scanning the fundus using second illumination light and imaging a second area of the fundus including the first area using a second imaging unit;
The first blood flow information at at least one position in the first area is calculated using the image obtained by the imaging in the first imaging step, and at the time of imaging in the second imaging step Calculating the timing of the first blood flow information in the pulsation based on the time variation of the second blood flow information obtained in the step,
A method for controlling an ophthalmic apparatus, comprising:   The program for making a computer perform each step in the control method of the ophthalmologic apparatus of any one of Claims 8 thru | or 14.

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