JP2010172614A - Function imaging ophthalmic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a function imaging ophthalmic apparatus of time-sequentially comparing comparison events and detecting the reaction of the respective parts of a fundus by stimulation. <P>SOLUTION: The function imaging ophthalmic apparatus 1 includes: an illumination optical system 10 for illuminating the fundus G of an eye E to be examined by the illumination luminous flux of a near-infrared region; a stimulating light irradiation optical system 40 for irradiating the measurement object region of the fundus F with the stimulating luminous flux of a visible region and stimulating it; a wavelength division part 28 for dividing a reflected luminous flux from the fundus F of the illumination luminous flux into the luminous fluxes of a plurality of wavelength regions of the near-infrared region; a light receiving part 30 for receiving the luminous fluxes of the plurality of wavelength regions divided by the wavelength division part 28 at the same timing before and after the stimulation by the stimulating luminous flux; a comparison part 70 provided with a first comparison part 70a for preparing comparison object images from photographed images in the plurality of wavelength regions photographed at the same timing in the light receiving part 30 and a second comparison part 70b for time-sequentially comparing the comparison object images prepared in the first comparison part 70a; and a display part 9 for displaying a compared result in the comparison part 70. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a functional imaging ophthalmic apparatus. In particular, the present invention relates to a functional imaging ophthalmologic apparatus that measures changes in spectral characteristics of an eye due to stimulation using captured images in a plurality of wavelength ranges.

  Needless to say, the importance of fundus observation in eye diagnosis is unquestionable. Currently, abnormal findings are found by diagnosing the fundus using color fundus images, fluorescence contrast images, etc. of the fundus camera. The functional imaging ophthalmologic apparatus is an apparatus that can detect the activity of the fundus and cells in the retina by analyzing image changes of the fundus when stimulated using a fundus camera. Until now, analysis has been performed based on changes in the intensity of fundus reflection as an attempt at functional imaging ophthalmologic apparatuses. For example, examples of performing functional imaging with flash stimulation using light and scleral single-point stimulation using electricity have been reported. It has also been found that when the nervous system is activated by stimulation, the concentrations of oxyhemoglobin and deoxyhemoglobin in blood, blood flow, and light scattering in the retina are changed. (See Non-Patent Documents 1 to 3)

  By the way, for example, if the photographing time is continued for about 20 seconds, the alignment between the eye and the apparatus changes during this time, so that there is a problem that the same imaged portion is displaced between the spectral images. Therefore, the inventors have proposed a spectral fundus image data measurement apparatus and a measurement method thereof that can eliminate the positional shift of the same portion between the spectral images even when the alignment between the eye and the apparatus changes with time. In addition, a spectroscopic fundus measuring device and a measuring method thereof that can easily and accurately specify each part from a spectroscopic fundus image based on spectral characteristics have been proposed. Furthermore, the inventors analyzed the oxygen saturation of the retina in these documents because the absorption sensitivity (absorbed light amount) of oxyhemoglobin and reduced hemoglobin has wavelength dependency. (See Patent Documents 1 and 2)

JP 2006-158547 A (paragraphs 0029 to 0082, FIGS. 1 to 21) JP 2007-330557 A (paragraphs 0024 to 0061, FIGS. 1 to 12)

Kazushige Tsunoda, Yoshihisa Oguchi, Gen Hanazono, and Manabu Tanifuji “Mapping Cone-and Rod-Induced Retinal Responses in Rinetin Reverbet. Ophthalmol. Vis. Sci. 2004 45: 3820-3826. Kazuhito Tsunoda “Review: Imaging of Retinal Nerve Activity Retinal Signal Measurement: Functional Retinography (FRG)” Science of Vision, Vol. 29, No. 1, 2008 Yoshitaka Okawa, Takashi Fujikado, Tomomitsu Miyoshi, Hajime Sawai, Shunji Kusaka, Toshifumi Mihashi, Yoko Hirohara, and Yasuo Tano "Optical Imaging to Evaluate Retinal Activation by Electrical Currents Using Suprachoroidal-Transretinal Stimulation" Invest. Ophthalmol. Vis. Sci. 2007 48: 4777-4784.

  However, only changes in the intensity of the fundus reflex and the static absolute value of oxygen saturation can be used to quantify temporal changes in response to stimulation of the oxygen saturation in the fundus and the amount of components in the retina. However, it was not sufficient for clinical use. That is, if these temporal changes can be measured quantitatively, the activity of the retinal details can be understood in more detail, and it is considered that it will be greatly useful clinically. In particular, it is possible to analyze the reaction of substances in the retina by light stimulation by measuring captured images in a plurality of wavelength ranges in time series, for example, by measuring the spectral distribution of oxygen saturation due to light stimulation in time series. In addition, if the spectral distribution is known, component analysis in the retina can be performed from the spectral image, which is likely to be useful for eye diagnosis. Accordingly, it is a first object of the present invention to provide a functional imaging ophthalmologic apparatus capable of comparing comparative events such as oxygen saturation in a time series and detecting the reaction of each part of the fundus due to stimulation. To do.

  In addition, the blood vessel portion in the fundus image is not so distinct from the surroundings, and a technique that can clearly extract these specific portions is required. Accordingly, it is a second object of the present invention to provide a functional imaging ophthalmologic apparatus that can extract a specific portion such as a blood vessel portion more clearly.

  In addition, since the alignment between the eye and the device changes with time, when measuring the temporal change of the fundus, it is difficult to efficiently extract the same part from captured images taken at different times. there were. Accordingly, it is a third object of the present invention to provide a functional imaging ophthalmologic apparatus that can efficiently extract the same portion from captured images taken at different times.

  In order to solve the above-described problem, the functional imaging ophthalmologic apparatus 1 according to the first aspect of the present invention illuminates the fundus F of the eye E with an illumination light beam in the near infrared region as shown in FIG. The system 10, the stimulation light irradiation optical system 40 for irradiating the measurement target region of the fundus F with the stimulation light beam in the visible region, and the reflected light beam from the fundus F of the illumination light beam in a plurality of wavelength regions in the near infrared region. The wavelength division unit 28 that divides the light beam, the light receiving unit 30 that receives the light beams in a plurality of wavelength regions divided by the wavelength division unit 28 at the same timing before and after the stimulation with the stimulation light beam, and the same timing in the light receiving unit 30 The first comparison unit 70a that creates a comparison target image from the captured images in a plurality of wavelength ranges photographed in Step 2 and the second comparison unit 70b that compares the comparison target image created by the first comparison unit 70a in time series. A comparison unit 70 having And a display unit 9 for displaying the comparison result in zero.

  Here, the light beams in a plurality of wavelength ranges may be light beams specified as a single wavelength, or may be light beams having a wavelength range. In addition, the detection result obtained from the captured image in the case of a light beam having a wavelength range is an average value with respect to the wavelength. Further, stimulation may include after stimulation (stimulation corresponds to after stimulation at the start). The comparison target image refers to an image that is worth comparing temporally, spatially, or spectroscopically by paying attention to specific physical properties such as an oxygen saturation image. A difference image between captured images having different wavelengths can also be a comparison target image because a portion that varies depending on the wavelength can be extracted. With this configuration, it is possible to compare comparative events such as oxygen saturation in time series, and provide a functional imaging ophthalmologic apparatus that can detect the reaction of each part of the fundus due to stimulation. The reaction here typically refers to a change in oxygen saturation, but also includes a change in blood flow, a change in light scattering in the retina, blinking, tearing, and the like.

  The functional imaging ophthalmologic apparatus 1 according to the second aspect of the present invention includes an illumination optical system 10 that illuminates the fundus F of the eye E with an illumination light beam in the near infrared region, as shown in FIG. Stimulation light irradiation optical system 40 for irradiating the measurement target area of the fundus F with a stimulation light beam and wavelength division for dividing the reflected light beam from the fundus F of the illumination light beam into light beams in a plurality of near-infrared wavelength regions A light receiving unit 30 that receives light beams in a plurality of wavelength regions divided by the wavelength division unit 28 at the same timing before and after stimulation with the stimulation light beam, and a plurality of images that are captured by the light receiving unit 30 at the same timing. A comparison unit 70 that creates a comparison target image from a captured image in the wavelength band and a display unit 9 that displays the comparison target image are provided.

  If comprised like this aspect, an oxygen saturation image etc. can be created as a comparison object image from the picked-up image in the several wavelength range image | photographed at the same timing. In addition, a blood vessel portion can be clearly extracted by creating a difference image between a wavelength with high sensitivity of oxyhemoglobin and a wavelength with high sensitivity of reduced hemoglobin as a comparison target image. That is, in the difference image, the part where the light absorption sensitivity varies depending on the wavelength can be selectively extracted, so that the blood vessel (artery, vein) part can be extracted with low background noise, for example.

The functional imaging ophthalmologic apparatus 1 according to the third aspect of the present invention includes an illumination optical system 10 that illuminates the fundus F of the eye E with an illumination light beam in the near infrared region, as shown in FIG. The stimulation light irradiation optical system 40 that irradiates and stimulates the measurement target region of the fundus F with the stimulation light beam, the light receiving unit 30 that receives the reflected light beam from the fundus F of the illumination light beam, and the light receiving unit 30 shoots at a plurality of times. A comparison unit 70 that compares the captured image or an image created based on the captured image in time series, and a display unit 9 that displays a comparison result of the comparison unit.
If comprised like this aspect, the reaction of each part in a fundus can be detected from the time-dependent change of the photographed image by light stimulation.

According to a fourth aspect of the present invention, in the functional imaging ophthalmologic apparatus according to the first aspect or the second aspect, the comparison target image is an oxygen saturation image created from captured images in a plurality of wavelength ranges. .
If comprised in this way, the analysis using oxygen saturation will be attained about the eye to be examined. Thereby, the active site | part of a retina and the disorder | damage | failure of the blood vessel by diabetic retinopathy can be specified.

Further, according to a fifth aspect of the present invention, in the functional imaging ophthalmologic apparatus according to the first aspect or the second aspect, the comparison target image is a difference image between captured images in two wavelength regions among a plurality of wavelength regions. is there.
With this configuration, by creating a difference image, it is possible to obtain an image in which a part where the light absorption sensitivity does not change depending on the wavelength is obtained. Therefore, a portion where the light absorption sensitivity changes depending on the wavelength, for example, blood vessels (arteries, veins) is low-backed. Can be extracted with ground noise.

In addition, according to a sixth aspect of the present invention, in the functional imaging ophthalmologic apparatus according to the first aspect or the third aspect, an image for analyzing a reaction of the eye E by stimulation with a stimulation light beam from a comparison result in the comparison unit 70 An analysis unit 75 is provided.
Here, the reaction analyzed by the image analysis unit 75 includes, for example, activation of a ganglion cell and a dynamic reaction to a blood vessel disorder due to diabetic retinopathy. If comprised in this way, the reaction of the eye to be examined by light stimulation can be analyzed, and there is a possibility that it can be applied to the treatment of the eye to be examined.

According to a seventh aspect of the present invention, in the functional imaging ophthalmic apparatus according to the first aspect or the second aspect, the first wavelength region and the second wavelength region of the plurality of wavelength regions are blood oxidations. It is set across the intersection of the spectral density characteristics of hemoglobin and reduced hemoglobin.
With this configuration, since the wavelength range sensitive to oxyhemoglobin (second wavelength range) and the wavelength range sensitive to reduced hemoglobin (first wavelength range) are used, arteries and veins can be clearly detected from the comparison data. Can also be segmented. In addition, it is preferable to use three or more wavelength regions including the two wavelength regions because an oxygen saturation image that well reflects the absorbed light amount pattern can be created.

According to an eighth aspect of the present invention, in the functional imaging ophthalmologic apparatus according to the seventh aspect, the first wavelength range is 730 to 780 nm, and the second wavelength range is 820 to 880 nm.
Such a configuration is preferable because the difference in the amount of absorbed light between oxyhemoglobin and reduced hemoglobin in the first wavelength region and the second wavelength region is large. If the first wavelength range is 750 to 770 nm and the second wavelength range is 850 to 870 nm, the difference in absorbed light amount is further increased, which is more preferable.

The ninth aspect of the present invention is the functional imaging ophthalmologic apparatus according to any one of the first to eighth aspects. For example, as shown in FIG. Is done.
With this configuration, a specific region of the fundus can be analyzed.

Further, the eye function image analysis method according to the tenth aspect of the present invention includes an illumination step (S100) for illuminating the fundus F of the eye E with an illumination light beam in the near infrared region, for example, as shown in FIG. A stimulating light irradiation step (S110) for irradiating the measurement target area of the fundus F with a stimulating luminous flux in a region, and a reflected luminous flux from the fundus F of the illuminating luminous flux is divided into luminous fluxes in a plurality of wavelength regions in the near infrared region. A wavelength splitting step (S120), and a light receiving step (S130) for receiving light beams in a plurality of wavelength regions split in the wavelength splitting step (S120) at the same timing before and after stimulation in the stimulation light irradiation step (S110). The comparison object created in the first comparison process (S150) and the first comparison process (S150) for creating the comparison object image from the photographed images in the plurality of wavelength regions photographed at the same timing in the light receiving process (S130) Time series To comprise a second comparison step of comparing (S170), and a display step of displaying the comparison result (S175) in the second comparison step (S170).
With this configuration, it is possible to compare comparative events such as oxygen saturation in a time series, and provide an ophthalmic function image analysis method that can detect the reaction of each part of the fundus due to stimulation.

According to one aspect of the present invention, a comparison event is created in a time series by creating a comparison target image from captured images in a plurality of wavelength ranges taken at the same timing, and comparing them in a time series. It is possible to provide a functional imaging ophthalmologic apparatus that can detect the reaction of each part of the fundus caused by stimulation.
Further, according to another aspect of the present invention, it is possible to provide a functional imaging ophthalmologic apparatus that can clearly extract a specific portion such as a blood vessel portion using a plurality of captured images having different wavelength ranges.
According to still another aspect of the present invention, it is possible to provide a functional imaging ophthalmologic apparatus that can efficiently extract the same portion by forming a mask that efficiently extracts the same portion from captured images taken at different times. .

1 is a diagram illustrating a configuration example of a functional imaging ophthalmologic apparatus in Embodiment 1. FIG. It is a figure which shows the example of a processing flow of the eye function image analysis method using the functional imaging ophthalmologic apparatus in Example 1. FIG. It is a figure which shows the example of the absorbed light quantity of oxidation and reduction | restoration hemoglobin. It is a figure which illustrates in detail the processing flow of the image acquisition in an image process part. It is a figure which shows the example of the analysis flow of the time-dependent change of the hemoglobin density | concentration of a fundus image. It is a figure which shows the example of the time change of the oxygen saturation image produced from the picked-up image image | photographed with the 1st CCD camera and the 2nd CCD camera. It is a figure which shows the example of a processing flow of mask formation. It is a figure which shows side by side the picked-up image P1 image | photographed at time t1, and the picked-up image P2 image | photographed at time t2. It is a figure which shows the reference | standard mask for extracting a measurement object area | region from the picked-up image P1 image | photographed at time t1. It is a figure which shows the extraction mask for extracting a measurement object area | region from the picked-up image P2. It is a figure which shows the example of the extracted reference | standard mask area | region. It is a figure which shows the example of the flow of a process. It is a figure which shows the example of the processing flow of conversion parameter calculation and extraction mask formation. FIG. 10 is a diagram illustrating a processing flow example of an eye function image analysis method using the functional imaging ophthalmologic apparatus according to the fourth embodiment. FIG. 10 is a diagram illustrating a processing flow example of an eye function image analysis method using the functional imaging ophthalmologic apparatus according to the fifth embodiment. FIG. 20 is a diagram illustrating a configuration example of an image processing unit according to a ninth embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In the first embodiment, an example will be described in which visible light is irradiated to the fundus to give a light stimulus, the reflected light beam is divided into two wavelength regions and received, and the first comparison mode and the second comparison mode are executed. In addition, in the first comparison mode, an example in which an oxygen saturation image is created from a captured image is formed by extracting a mask in order to extract a measurement target region of the fundus by image processing in the second comparison mode. An example in which the oxygen saturation images of the measurement target regions are compared in time series will be described.

[Device configuration]
In FIG. 1, the structural example of the functional imaging ophthalmic apparatus 1 in a present Example is shown. In FIG. 1, the functional imaging ophthalmologic apparatus 1 is roughly divided into a fundus camera unit 2, a top housing unit 3, a storage unit 6, an image processing unit 7, a control unit 8, and a display unit 9. The fundus camera unit 2 mainly receives an illumination optical system 10 for illuminating the fundus F of the eye E, and receives light reflected from the fundus F to form a fundus image on the light receiving surface of the light receiving unit (imaging camera) 30. The front stage of the optical system 20, the light source 51 of the alignment optical system 50 for aligning the irradiation position of the irradiation light to the fundus F when the examiner observes the fundus F, and the finder optical for the examiner to observe the eye E A system 60 and the like are provided. The top housing portion 3 mainly includes a light stimulation optical system 40 for irradiating the fundus F of the eye E to be examined, and light receiving optics for receiving a reflected light beam from the fundus F and forming a fundus image on the light receiving surface of the imaging camera. The rear stage part of the system 20 and the light receiving part of the alignment optical system 50 are provided. The rear stage of the light receiving optical system 20 receives the reflected light flux into a plurality of wavelength regions divided by the wavelength dividing unit 28 and the wavelength dividing unit 28 at the same timing. It has the light-receiving part 30 to do. In this embodiment, the wavelength dividing unit 28 is divided into two wavelength regions, and the light receiving optical system 20 receives the first light receiving optical system 20A that receives the light beam in the first wavelength region and images it, and the second wavelength region. It has the 2nd light reception optical system 20B which light-receives and images. The light receiving unit 30 includes a first CCD camera 31 as a first light receiving unit that images a light beam in the first wavelength region, and a second CCD camera 32 as a second light receiving unit that images a light beam in the second wavelength region. Have. The light receiving unit of the alignment optical system 50 includes a third CCD camera 54. An imaging camera other than a CCD camera can be used as the light receiving unit. In FIG. 1, c1 to c3 indicate control signal connections, and d1 to d3 indicate connection of captured image signals.

The illumination optical system 10 illuminates the fundus F of the eye E with an illumination light beam in the near infrared region. In the fundus camera unit 2, a halogen lamp 11 as an illumination light source, a condenser lens 12, a spectral characteristic correction filter 13, a diaphragm plate 14, a reflecting mirror 15, a relay lens 16, a beam splitter 17, and an objective lens 18 are sequentially arranged on the irradiation optical axis. Arranged. Here, the halogen lamp 11 is disposed near the front focal position of the condenser lens 12. The halogen lamp 11 continuously covers the wavelength range of the irradiation light from the visible light to the infrared region, and can be continuously lit for about 30 seconds to perform photographing in time series. Progress has made it possible to acquire images without using a flash. Moreover, the spectral characteristic correction filter 13 limits the illumination light beam to a near-infrared range (for example, a wavelength of 730 nm to 1 μm). Note that the light transmittance may be corrected so as to obtain a photographed image that is as homogeneous as possible in consideration of wavelength dependency such as the brightness of the light source and the sensitivity of the imaging camera. The diaphragm plate 14 is disposed so as to be conjugate with the beam splitter 17.
The illumination optical system 10 further illuminates the fundus F of the eye E through the objective lens 18 with the reflected light beam from the beam splitter 17. The beam splitter 17 reflects near-infrared light and transmits visible light. Between the beam splitter 17 and the eye E to be examined, a common optical system of the illumination optical system 10 and the light receiving optical system 20 is formed.

  The light receiving optical system 20 includes a wavelength division unit 28 that divides the reflected light beam from the fundus F of the illumination light beam into a light beam in the first wavelength region in the near infrared region and a light beam in the second wavelength region, and before and after stimulation with the stimulation light beam. The first light receiving unit 20A that receives the light beam in the first wavelength region divided by the wavelength division unit 28 and the second light receiving unit 20B that receives the light beam in the second wavelength region. In the fundus camera unit 2, the objective lens 18, the beam splitter 17, the iris diaphragm plate 21, the focusing lens 22, the imaging lens 23, the reflecting mirror 24, and the switching mirror 25 are sequentially arranged on the reflected optical axis passing through the eye E to be examined. The light receiving optical system of the top housing part 3 is connected. The iris diaphragm plate 21 is disposed at a position conjugate with the pupil of the eye E to be examined. The switching mirror 25 is normally arranged outside the optical path of the light receiving optical system 20, but when the observer wants to observe the eye E, for example, the switching mirror 25 is inserted into the optical path of the light receiving optical system 20 using a solenoid, for example. The optical path is switched to the finder system 60 to enable visual alignment.

In the light receiving optical system 20, a field lens 26 and a dichroic mirror 27 are arranged on the optical axis reflected from the eye E in the top housing portion 3, and the dichroic mirror 27 is light in the visible range of the photostimulation optical system 40 (for example, 400 nm to 720 nm) and long-wavelength near-infrared light (for example, 920 nm to 1 μm), and light in the near-infrared range from the first wavelength range (for example, 730 nm to 780 nm) to the second wavelength range (for example, 820 nm to 880 nm). To reflect. A dichroic mirror 28 serving as a wavelength division unit is further arranged on the optical axis of the reflected light beam from the dichroic mirror 27, and the dichroic mirror 28 transmits a light beam in a first wavelength region (for example, 730 nm to 780 nm) and transmits a second wavelength region ( For example, the light beam of 820 nm to 880 nm is reflected. As will be described later, the first wavelength region and the second wavelength region are set across an intersection of spectral density characteristics of blood oxygenated hemoglobin HbO ₂ and reduced hemoglobin Hb (see FIG. 3). A filter 34, an imaging lens 35, and a first CCD camera 31 as a first imaging unit are disposed on the optical axis of the light beam in the first wavelength range that has passed through the dichroic mirror 28. A filter 36, an imaging lens 37, and a second CCD camera 32 as a second imaging unit are arranged on the optical axis of the light beam in the second wavelength region reflected from the dichroic mirror 28. The light receiving surfaces of the first CCD camera 31 and the second CCD camera 32 are arranged so as to be conjugate with the fundus F of the eye E so that a fundus image is formed. The CCD cameras 31 and 32 are sensitive to a wide range of wavelengths from visible light to the near-infrared region. For example, high-definition images of 1.3 million pixels (1344 × 1024) can be obtained, high speed (about 8 frames / second), and low noise. Reading is possible. The filter 34 selectively transmits a light beam in a first wavelength region (for example, 730 nm to 780 nm), and the filter 36 selectively transmits a light beam in a second wavelength region (for example, 820 nm to 880 nm). The imaging lenses 35 and 37 are lenses for relaying light emitted from the filters 34 and 36 to the CCD cameras 31 and 32, respectively. With this configuration, the light receiving optical system 20 divides and receives the reflected light beam from the illuminated fundus F into a divided light beam in the first wavelength region and a divided light beam in the second wavelength region, and obtains spectral fundus images having different wavelength regions. Can be imaged.

  The photostimulation optical system 40 irradiates the measurement target region of the fundus F of the eye E with visible light (for example, 400 nm to 720 nm) and stimulates it. In the top housing portion 3, a condenser lens 42, a reflecting mirror 43, a dichroic mirror 44, and a dichroic mirror 27 are disposed on the optical axis of the stimulation light beam emitted from the stimulation light source 41. As the stimulus light source 41, a light source having a diaphragm arranged in front of the light source, a liquid crystal panel, an organic EL (electroluminescence), or the like can be used. The diaphragm is a diaphragm for limiting and irradiating a part of the fundus F with stimulation light, and an arbitrary size and shape can be selected. The liquid crystal panel and the organic EL can display a color pattern of any color and shape on the panel by selecting whether or not each pixel of the liquid crystal and the organic EL is optically displayed. For example, by using a slit pattern, it is possible to irradiate stimulation light to the linear region in the vertical direction of the fundus, and the color can be freely selected such as red, green, and blue. The dichroic mirror 44 transmits stimulation light in the visible range and reflects light in the near infrared range for alignment (for example, 920 nm to 1 μm). The dichroic mirror 27 transmits light in the visible range (for example, 400 nm to 720 nm) and long-wavelength near-infrared light (for example, 920 nm to 1 μm) of the photostimulation optical system 40, and the first wavelength range (for example, 730 nm to 780 nm). To near-infrared light over a second wavelength range (for example, 820 nm to 880 nm). With this configuration, the stimulation light emitted from the stimulation light source 41 passes through the dichroic mirror 44 and the dichroic mirror 27. The optical axis of the light stimulation optical system 40 after passing through the dichroic mirror 27 coincides with the optical axis of the light receiving optical system 20 and reaches the fundus F of the eye E to be examined in the fundus camera unit 2.

  The alignment optical system 50 is for aligning the irradiation position of the irradiation light onto the fundus F. In the fundus camera unit 2, irradiation light of a long wavelength (for example, 920 nm to 1 μm) in the near infrared region from the alignment light source 51 passes through the beam splitter 17 and the objective lens 18 and is reflected by the cornea of the eye E to be examined. The optical axis of the alignment optical system 50 reflected by the cornea and transmitted through the objective lens 18 and the beam splitter 17 coincides with the optical axis of the photostimulation optical system 40 up to the dichroic mirror 44. The dichroic mirror 44 transmits stimulation light in the visible range and reflects near-infrared light for alignment. On the optical axis of the alignment light reflected by the dichroic mirror 44, an imaging lens 53 and a third CCD camera 54 as a third imaging unit are arranged. The third CCD camera 54 captures reflected light when the light from the alignment light source 51 is projected onto the cornea of the eye E to be examined. By setting the wavelength of the alignment light source 51 to near infrared (for example, 940 nm), alignment can be performed even during acquisition of a spectral image without affecting the spectral image in the visible region.

  The viewfinder optical system 60 is used by the eye examiner to observe the fundus F with the naked eye. The switching mirror 25 is inserted into the optical path of the light receiving optical system 20, and the optical path is switched to the finder system 60 for observation.

  The storage unit 6 stores captured images, comparison target images, and the like. Further, the conversion parameter relating to mask formation specifies and stores the comparison target image or the elapsed time from the start of measurement. Data such as optical density of arteries and veins is stored.

  The image processing unit 7 includes a comparison unit 70 that compares a captured image and a comparison target image created based on the captured image. The comparison unit 70 compares the captured images in a plurality of wavelength regions captured at the same timing, and creates a comparison target image from these captured images, and the first comparison unit 70a creates the comparison target image. And a second comparison unit 70b that compares the comparison target images in time series. The comparison target image is an image created from captured images in a plurality of wavelength regions captured at the same timing by the light receiving unit 30 and is an image that is compared in time series. In this embodiment, the oxygen saturation image obtained from the image taken by the first light receiving unit 31 and the image taken by the second light receiving unit 32 is used. A difference image from the captured image at 32 may be used, or another image created by comparing the captured image at the first light receiving unit 31 with the captured image at the second light receiving unit 32 may be used. The image processing unit 7 also includes a captured image acquisition unit 71 that acquires captured images captured by the CCD cameras 31 and 32, and between captured images that are captured under different conditions (such as capturing time and wavelength) with respect to the same measurement target region. Using a positioning unit 72 for performing positioning, a mask forming unit 73 for forming a mask for extracting a measurement target region from a photographed image at the light receiving unit 30, and a mask formed by the mask forming unit 73, a measurement target from the photographed image. An image extraction unit 74 that extracts a region, and an image analysis unit 75 that analyzes a reaction of the eye E by stimulation with a stimulation light beam from a comparison result in the comparison unit 70 are provided. Further, the mask forming unit 73 obtains a conversion parameter calculating unit 76 that obtains a conversion parameter for aligning the position of each feature point with respect to captured images having different imaging times. From the captured image captured at the first time t1, blood vessels on the fundus image ( The contrast between the brightness of the measurement target region such as an artery and vein) and the brightness of the background thereof is calculated, and the reference mask region extraction unit 77 for extracting the measurement target region and the measurement target region extracted by the reference mask region extraction unit 77 The fundus image is subjected to processing such as filter processing, labeling processing, dilatation thinning processing, and the like. The processing unit 78 forms the reference mask M1, and the second light receiving unit 32 using the conversion parameters based on the reference mask M1. An extraction mask creating unit 79 for forming an extraction mask M2 for extracting the measurement target region from the captured image. The image extraction unit 74 extracts a measurement target region from the photographed image P1 photographed at the first time t1 using the extraction mask M1 and the photographed image P2 photographed at the second time t2 using the extraction mask M2.

  The display unit 9 displays a captured image of the eye E to be compared by the first comparison unit 70a and a comparison target image to be compared by the second comparison unit 70b. In this embodiment, an oxygen saturation image created from the image taken by the first light receiving unit 31 and the image taken by the second light receiving unit 32 is displayed as a comparison target image. A difference image between the image captured by the light receiving unit 31 and the image captured by the second light receiving unit 32 is displayed. The comparison target images are displayed in time series. In addition, the extracted measurement target region, various data accumulated in the storage unit 6, the analysis result in the analysis unit 75, and the like are displayed.

  The control unit 8 functions the functional imaging ophthalmologic apparatus 1 such as the fundus camera unit 2, the top housing unit 3, the storage unit 6, the image processing unit 7, the operation of the display unit 9, the flow of data and signals, etc. The entire ophthalmic apparatus 1 is controlled. Further, a control program for controlling the irradiation of the stimulating light beam (aperture, light quantity, time) and the photographing (exposure, time) of the CCD camera 30 is stored. The condition setting unit 80 sets measurement conditions such as stimulation and imaging conditions and the number of repetitions. The elapsed time determination unit 81 determines an elapsed time from the start of measurement, and determines which course is measured before, during, or after the next measurement. The number-of-repetitions determination unit 82 determines whether or not the number of repetitions of measurement has reached a preset number. The image processing unit 7 and the control unit 8 can be realized by a normal personal computer.

[Processing flow]
FIG. 2 shows a processing flow example of an eye function image analysis method using the functional imaging ophthalmologic apparatus 1 in the present embodiment.
First, preparation for measurement is performed (preparation / condition setting step: S000). That is, the functional imaging ophthalmologic apparatus 1 is prepared and set on the eye E to be examined. Further, measurement conditions are set, and control is performed so as to satisfy the conditions by the program of the control unit 8. The measurement conditions will be described later, but mainly the conditions for stimulation and imaging, including the number of repetitions. Next, the fundus F of the eye E is illuminated with a near-infrared illumination light beam from the illumination light source 11 (illumination process: S100). Then, eye alignment is performed with respect to the illumination light beam. Next, the measurement target region of the fundus F is irradiated with stimulation light in the visible range to stimulate (stimulus light irradiation step: S110), and the response to the stimulus of the eye E is measured. Shooting is repeated for the set number of times during and after stimulation. The control unit 8 determines in the shooting time determination unit 81 whether the next shooting is shooting before stimulation, during stimulation, or after stimulation (course determination step before and after stimulation: S105). During stimulation, images are repeatedly taken for the number of times set for each course after stimulation, and the next course (before stimulation → during stimulation, during stimulation → after stimulation) is sequentially performed. Which course is measured is determined by the elapsed time from the start of measurement in the condition setting. The number of times of photographing in each course is set to a value obtained by dividing the pre-stimulus time, the mid-stimulus time, and the post-stimulus time by the photographing interval. The stimulation light beam is irradiated in the course during stimulation, but the stimulation light beam is not irradiated in the course before and after stimulation. Further, when the shooting is repeated for the set number of times in all the courses before, during, and after the stimulation, the stimulation providing course is repeated for the set number of repetitions. In the measurement, the reflected light beam from the fundus of the illumination light beam is guided to the light receiving optical system 20, and the reflected light beam is dichroic mirror 28 serving as a wavelength division unit and the light beam in the first wavelength region (730 nm to 780 nm) in the near infrared region and the second light beam. It divides | segments into the light beam (820 nm-880 nm) of a wavelength range (wavelength division | segmentation process: S120).

  The light beam divided into a plurality of wavelength ranges is received at the same timing and photographed before, during and after the stimulation in the stimulation light irradiation step (S110) (light reception step: S130). In this embodiment, it is assumed that the light is divided into two wavelength regions, the first wavelength region light beam divided by the first CCD camera 31 is received and photographed, and the second wavelength divided by the second CCD camera 32 is taken. Taking a picture of the luminous flux in the area. Next, in the image processing unit 7, the first comparison unit 70a of the comparison unit compares the captured image of the first wavelength range and the captured image of the second wavelength range acquired at the same timing (first comparison step: first comparison step: S140), based on the fact that the difference between these images is based on the difference in the amount of absorbed light between oxyhemoglobin and reduced hemoglobin in the first wavelength region and the second wavelength region, between the captured image in the first wavelength region and the second wavelength region. An oxygen saturation image as a comparison target image is created from the captured images (comparison target image creation step: S150). Next, the comparison target image is displayed on the display unit 9 (first display step: S155). Next, the control unit 8 determines whether or not the number of times of photographing and the number of repetitions of stimulus application in each course have reached a preset number in the repetition number determination unit 82 (repetition number determination step: S160). The measurement is repeated until the number of times of shooting and the number of times of stimulus application in each course reach a preset number of times. The number of times of shooting and the number of repetitions of stimulus application in each course are determined in advance in the preparation / condition setting step (S000). When the number of stimulation repetitions reaches a preset number, the oxygen saturation images as the comparison target images created in the comparison target image creation step (S150) are compared in time series (second comparison step: S170). ). It is possible to detect the reaction state of each part in the fundus F from the temporal change of the oxygen saturation image by light stimulation. Next, the comparison result in the second comparison step (S170) is displayed on the display unit 9 (second display step: S175). The comparison result in the second comparison step (S170) may be, for example, a comparison of the entire comparison target screen such as an oxygen saturation image, or may be a comparison of extracted measurement target regions. The oxygen saturation may be shown in a tabular form. Note that the first comparison step (S140) to the first display step (S155) may not be performed in a short time, and therefore may be performed after the repetition number determination step (S160). The first display step (S155) can be omitted when the comparison target images are displayed in time series in the second display step (S175). Here, for convenience of explanation, the first comparison process (S140) to the first display process (S155) are performed in the first comparison mode, and the second comparison process (S170) and the second display process (S175) are performed in the second comparison mode. It shall be called.

FIG. 3 shows an example of the amount of absorbed light (unit: cm ⁻¹ / moles / liter) of oxidized and reduced hemoglobin. FIG. 3A shows the amount of absorbed light in the approximately visible region, and FIG. 3B shows the amount of absorbed light in the approximately near infrared region. Oxygenated hemoglobin is indicated by HbO ₂ , and reduced hemoglobin is indicated by Hb. The retina oxygen saturation analysis utilizes the fact that the amount of light absorbed by oxidized / reduced hemoglobin varies depending on the wavelength of the stimulating light flux. By analyzing how much of this spectral characteristic pattern is included in the spectral characteristics in each measurement target region, it is possible to determine the proportion of oxygenated / reduced hemoglobin contained in the measurement target region, and further, the proportion of oxidized hemoglobin There is a possibility that oxygen saturation can be obtained from In the near infrared region, the amount of absorbed light is reversed at about 800 nm. In the first wavelength region (730 nm to 780 nm), the oxidized hemoglobin HbO ₂ is larger, and in the second wavelength region (820 nm to 880 nm), the reduced hemoglobin Hb is more. There is a big difference. As will be described later, the difference between these images is based on the difference in the amount of absorbed light between oxyhemoglobin and deoxyhemoglobin in the first wavelength region and the second wavelength region, and the captured image and the second wavelength in the first wavelength region. An oxygen saturation image as a comparison target image can be created from the captured image in the region (see FIG. 5). An increase in the wavelength range is preferable because it matches the absorbed light amount pattern and can create an oxygen saturation image with high accuracy.

  FIG. 4 illustrates in detail the processing flow of image acquisition in the image processing unit 7. In the comparison unit 70, in the first comparison mode (processed by the first comparison unit 70a), the captured image of the first light receiving unit 31 and the captured image of the second light receiving unit 32 acquired at the same timing are compared, An oxygen saturation image as a comparison target image is created from these captured images. In the second comparison mode (processed by the second comparison unit 70b), the oxygen saturation images created by the first comparison unit 70a are compared in time series. For this reason, the image taken by the first light receiving unit 31 and the image taken by the second light receiving unit 32 are taken in time series at the same timing. These captured images are acquired by the image processing unit 7 by the captured image acquisition unit 71.

  First, the condition setting unit 80 of the control unit 8 sets the conditions for applying the light stimulus and the imaging conditions for the CCD cameras (the first CCD camera 31 and the second CCD camera 32) (condition setting step: S201). For light stimulation, the type of stimulation and the number of repeated stimulations are set. The types of stimulation include light stimulation, transcorneal stimulation, scleral single point stimulation, visual crossing retrograde stimulation, and the like. In this embodiment, light stimulation is adopted. In light stimulation, the light wavelength, light intensity, stimulation area (aperture, slit), and stimulation time are set. In addition, the number of times of stimulus application is set to 10 times, for example. Further, as the imaging conditions (image acquisition conditions), for example, the exposure time is set to 20 ms, the imaging time is set to 2 seconds before stimulation, 4 seconds during stimulation, and 20 seconds after stimulation, and the imaging interval is set to 25 ms. Note that the combination of the exposure time, the shooting time, and the shooting interval may be changed, or a plurality of combinations may be set in the set number of repetitions. Next, eye alignment is performed using the alignment optical system 50 (alignment step: S202). Using the irradiation light of the long wavelength (for example, 920 nm or more) in the near infrared region from the alignment light source 51, the reflected light from the cornea of the eye E is adjusted so as to come to the center of the imaging surface (that is, the center of the captured image). The image is taken and monitored by the third CCD camera 54. Thereby, the position of the eye E is aligned.

Next, repeated shooting is performed under the shooting conditions set in the condition setting step (S201) (repeated shooting step). The control unit 8 automatically controls the stimulation light source 41 and the CCD cameras (the first CCD camera 31 and the second CCD camera 32) according to the set photographing conditions. The contents of the repeated photographing process are as follows. First, in a state where no stimulation light is irradiated (pre-stimulation course), a photograph is taken with a CCD camera to obtain a photographed image (S203). The first CCD camera 31 and the second CCD camera 32 are photographed simultaneously, and the photographing interval is 25 ms. The shooting time determination unit 81 of the control unit 8 determines whether or not the shooting time has passed 2 seconds (S204). If 2 seconds have not passed, the shooting before stimulation is continued (return to S203), and 2 seconds have passed. Then, stimulation is started (S205). For example, stationary light or 4 Hz flicker light can be used as the stimulation light. In addition, the stimulation light may be limited to a part of the fundus F using a slit or a diaphragm, and the steady light or flicker light may be irradiated. In a state where stimulation light is irradiated (course during stimulation), the CCD camera captures an image and acquires a photographed image (S206). The first CCD camera 31 and the second CCD camera 32 are photographed simultaneously, and the photographing interval is 25 ms. The shooting time determination unit 81 of the control unit 8 determines whether or not the shooting time has passed 4 seconds (S207). If 4 seconds have not passed, the shooting during stimulation is continued (return to S206), and 4 seconds have passed. Then, the stimulation is finished (S208). Next, in a state where no stimulation light is irradiated (post-stimulation course), an image is taken with a CCD camera and a captured image is acquired (S209). The first CCD camera 31 and the second CCD camera 32 are photographed simultaneously, and the photographing interval is 25 ms. The shooting time determination unit 81 of the control unit 8 determines whether or not the shooting time has passed 20 seconds (S210). If 20 seconds have not passed, the shooting after stimulation is continued (return to S209), and 20 seconds have passed. Then, the repetition number determination unit 82 of the control unit 8 compares the number of repetitions n with the set number of repetitions n ₀ = 10 (S211). The number of repetition n is stored in the counter of the number of repetitions determining unit 82, it is compared with the set number of repetition n _0. If n <n ₀ = 10, the counter repeat count n is incremented by 1 (S212), and the counter data storage time is set to the time until the determination by the next repeat count determining unit 82 (26 in this embodiment). (Seconds) is secured (S213). In addition, it is desirable to take a long time (for example, 30% or more of the time until the determination) with a margin time. Until the number of repetition n reaches the set number of repetition n _0, prior to stimulation, during stimulation, the course of the post-stimulation was adopted again (return to S203), the light stimulus and imaging is repeated. If n ≧ n ₀ = 10, shooting is terminated and the shot images are compared and analyzed (S214).

  The comparison / analysis (S214) of the captured image is performed by the image processing unit 7. The image processing unit 7 acquires a captured image from the light receiving unit 30 in the captured image acquisition unit 71, and the comparison unit 70 acquires the first image acquired at the same timing in the first comparison mode (processed by the first comparison unit 70a). The captured image of the CCD camera 31 and the captured image of the second CCD camera 32 are compared, and an oxygen saturation image is created from these captured images. In the case where the alignment is shifted between the first and second CCD cameras, the alignment unit 72 performs alignment processing based on either (for example, the first CCD camera 31) as a reference and an image captured by the reference camera. I do. In the second comparison mode (processed by the second comparison unit 70b), a plurality of oxygen saturation images respectively created based on captured images captured at different imaging times are compared in time series. Further, the image analysis unit 75 analyzes the reaction of the eye E by stimulation with the stimulation light beam from the comparison result in the comparison unit 70. Analysis such as difference analysis and principal component analysis is performed as necessary. Next, the comparison result is displayed on the display unit 9 (S215). The comparison result may be, for example, a comparison of the entire comparison target screen such as an oxygen saturation image, or may be a comparison of a local portion of the image, for example, a measurement target region such as an artery, vein, macula, or optic disc. The oxygen saturation of the local portion and the average received light intensity for the number of repetitions may be shown in a graph, or may be shown in a tabular form. In addition, the oxygen saturation analysis may be performed using the average received light intensity (in this example, the average received light intensity of 10 times) of the captured image after the same time has elapsed from the start of each repeated image. Other analysis results are also displayed as needed. The display is preferably displayed in time series, and the reaction of the eye to be examined due to light stimulation is detected.

[Analysis of hemoglobin concentration]
Next, a method for analyzing the hemoglobin concentration in blood will be described. The analysis of the hemoglobin concentration is mainly performed by the first comparison unit 70a of the comparison unit 70. A blood vessel portion is extracted from the photographed image, and the concentration of redox hemoglobin is calculated using the Beer-Lambert law. According to Beer-Lambert's law, the light intensity before entering the medium is I ₀ , and the light intensity when moving through the medium by the distance L is I ₁ .

log ₁₀ (I ₁ / I ₀ ) = − αL = −εcL (Expression 1)

Where α is the absorption coefficient, ε is the molar extinction coefficient, and c is the molar concentration of the medium.
Therefore, the hemoglobin concentration in the blood vessel can be evaluated by measuring the ratio of the intensity of the reflected light to the incident light, where c is the hemoglobin concentration in the blood vessel and L is the distance traveled by the light in the blood vessel.

FIG. 5 shows an example of an analysis flow of the temporal change in the hemoglobin concentration of the fundus image. The analysis flow algorithm is as follows.
(A) The eye E and the fundus camera unit 2 are aligned. The alignment light is turned on, and alignment (positioning) is performed while viewing the image acquired by the third CCD camera 54 (S301).
(B) The fundus image is acquired by the captured image acquisition unit 71 of the image processing unit 7. Focus adjustment is performed, and fundus images are sequentially acquired in order of shooting time (elapsed time from the start of shooting) (S302).
(C) From the acquired image, a captured image captured at one wavelength is used as a reference image, and a captured image captured at another wavelength is used as an uncorrected image. For example, affine transformation is performed on the uncorrected image, and image distortion is determined as a reference. Correction is performed according to the image (S303). It should be noted that Helmat transform may be used. The correction is performed by the alignment unit 72.

(D) Next, the first comparison unit 70a creates an oxygen saturation image as a comparison target image. First, the average intensity of each artery, vein, and background at wavelength λ
Is calculated (S304).

(E) The optical density (( _ODartery ) ' _λ , ( _ODvein )' _λ ) of the artery and vein at the wavelength λ is calculated (S305).

(F) The thickness of the artery and vein ( _tartery , _tvein ) at the position where the average intensity is measured is measured, and the optical density of the artery and vein (( _ODartery ) _λ , ( _ODvein ) _λ ) is corrected ( S306).

(G) The local intensity corresponding to each coordinate (x, y) such as a feature point on the retina is measured, and the optical density ((OD _{x, y} ) of the artery and vein at each position ( _{x, y} ) _λ ) is calculated (S307).

(H) The optical density of the artery and vein at each position (x, y) on the retina ((OD) with the optical density of the artery and vein (( _ODartery ) _λ , ( _ODvein ) _λ ) at the _{wavelength λ} as an element. A factor analysis of _{x, y} ) _λ ) is performed (S308). By performing factor analysis, the ratio of arterial blood and venous blood at each position (x, y) on the retina is calculated, and the oxygenated hemoglobin concentration C (HbO ₂ ) and the reduced hemoglobin concentration C (Hb) can be obtained. . The first comparison unit 70a performs factor analysis to obtain the oxygenated hemoglobin concentration C (HbO ₂ ), the reduced hemoglobin concentration C (Hb), and the oxygen saturation. The ratio of oxygenated hemoglobin is roughly expressed as C (HbO ₂ ) / (C (HbO ₂ ) + C (Hb)), and the oxygen saturation is expressed as the ratio of oxygenated hemoglobin × 100 (%).
(I) The ratio of oxyhemoglobin is converted into a color code map (S309).

In the above, when calculating the optical density OD, the average intensity of the arteries and veins or the ratio of the average intensity of each position and the average intensity of the background is taken and the logarithm is multiplied by minus. AD) may be used, and the average intensity of the arteries and veins or the average intensity of each position may be subtracted from the average intensity of the background and the value divided by the average intensity of the background. Here, the absorbance density (AD) at an arbitrary point is represented by the following equation.

  This spectral retinal image analysis flow can be controlled by a program. The program is stored in the image processing unit 7, and the ratio of oxyhemoglobin and the like are mapped as a comparison result in the first comparison unit 70a.

FIG. 6 shows an example of temporal change in the oxygen saturation created from the captured images taken by the first CCD camera 34 and the second CCD camera 37. The oxygen saturation is obtained from the analysis of the hemoglobin concentration described above. In the example of FIG. 6, the fundus is irradiated with stimulation light in a slit shape. (A) Retina photographed image, (b) 0.2 seconds before starting stimulation, (c) 0.5 seconds after starting stimulation, (d) 2 seconds after starting stimulation, (e) 0.2 seconds after finishing stimulation (F) 0.5 seconds after the end of the stimulus, (g) 1 second after the end of the stimulus, (h) 2 seconds after the end of the stimulus, (i) 4 seconds after the end of the stimulus, (j) 6 seconds after the end of the stimulus, (k The photographed image is 8 seconds after the end of the stimulus and (l) 10 seconds after the end of the stimulus. A slit-like portion where the image is slightly bright after the start of stimulation and after the end of stimulation is the portion irradiated with the stimulation light. The lower left round part is a nipple, and the part extending from the nipple in a pulse shape is a blood vessel. Among the blood vessels, the portion where oxyhemoglobin HbO ₂ is larger corresponds to the artery, and for example, a blood vessel extending from the optic nerve head to the middle upward corresponds. Further, the portion where the reduced hemoglobin Hb is larger corresponds to the vein, for example, a blood vessel extending from the optic nerve head to the upper left. It can be seen that both of them begin to darken after the start of stimulation, become clear 0.2 seconds after the end of stimulation, become maximum after 1 to 2 seconds, and then gradually fade.

[Mask formation]
Next, a method for extracting and comparing the same portion from images having different times when observing a change in a captured image with time will be described. In the present embodiment, a method using a mask when extracting the same portion from images having different times will be described. As described in the ninth embodiment, it is also possible to sequentially perform alignment using the alignment unit 72.
In this embodiment, the image processing unit 7 uses a mask forming unit 73 that forms a mask for extracting a measurement target region from a captured image obtained by the light receiving unit 30 and a mask formed by the mask forming unit 73. The display unit 9 displays a photographed image of the measurement target region extracted by the image extraction unit 74.

  FIG. 7 shows a processing flow example of mask formation. First, the image processing unit 7 uses the captured image acquisition unit 71 to acquire a captured image P1 captured at time t1 and a captured image P2 captured at time t2 (S351). In this embodiment, instead of these captured images, the comparison target image created from the captured image at the first light receiving unit 31 and the captured image at the second light receiving unit 32 at time t1 and the first received light at time t2. The mask formation is applied to the comparison target image created from the captured image of the unit 31 and the captured image of the second light receiving unit 32. Here, for the sake of simplicity of explanation, the mask formation is applied to the captured image P1 and the captured image P2. An example will be described. The captured image includes an image obtained by processing the captured image.

  FIG. 8 shows the photographed image P1 photographed at time t1 and the photographed image P2 photographed at time t2. FIG. 8A shows the captured image P1, and FIG. 8B shows the captured image P2. When eye movement occurs between time t1 and time t2, a difference occurs between the captured image P1 and the captured image P2. That is, the position of the target portion to be compared differs between the captured image P1 and the captured image P2. Next, the measurement target region is extracted from the captured image P1 by the reference mask region extraction unit 77 (S352).

  FIG. 9 shows a reference mask M1 for extracting a measurement target region from the captured image P1 captured at time t1. In this example, a part of the artery is extracted as the measurement target region. In order to extract the measurement target region to be compared from the photographed image P1, for example, an appropriate algorithm is used such as extracting a portion where the brightness is darker than the surroundings and the contrast is high. The algorithm will be described later. The extracted portion is binarized as white (extracted region) and the other portion is black (excluded region) to be a reference mask region (S353). In addition, the reference mask region is processed in the processing unit 78 to improve the completeness and form the reference mask M1. The algorithm will be described later. It is also possible to omit the processing of the processing unit 78 and use the reference mask region as it is as the reference mask M1.

  Next, a conversion parameter for aligning the captured image P1 and the captured image P2 is obtained (S354). A reference window region including a reference mask region (for example, a quadrangle including a convex hull of the measurement target region, a convex hull being a convex polygon surrounding the measurement target region) A1 is defined in the captured image P1. . The reference window area A1 may be expanded to include many feature points that can be used for conversion. Further, an extraction window area A2 corresponding to the reference window area A1 is determined in the captured image P2. Since there is a possibility that the position of the reference window area A1 in the photographic image P1 and the extraction window area A2 in the photographic image P2 may be different, the mask forming unit 73 uses the conversion parameter calculation unit 76 to perform the reference window area A1 and the extraction window area. A plurality of common feature points are extracted from A2, and a conversion parameter for aligning the reference window area A1 and the extraction window area A2, that is, the captured image P1 and the captured image P2, is obtained. The transformation includes movement, rotation, reduction / enlargement, and for example, affine transformation is used. It should be noted that Helmat transform may be used. Details of the conversion will be described later. Rather than converting the entire captured image, conversion is performed including the step of obtaining a conversion parameter by converting only the periphery of the reference mask region, that is, the region to be measured (S354), and the step of forming an extraction mask (S355) described later. Processing time can be shortened. The conversion parameter specifies the comparison target image or the elapsed time and stores it in the storage unit 6.

  FIG. 10 shows an extraction mask M2 that is a mask for extracting a measurement target region from the captured image P2 captured at time t2. Further, the extraction window area A2 is shown in the figure. The extraction mask M2 is obtained by performing conversion processing (movement, rotation, reduction / enlargement, etc.) of the reference mask M1 in the extraction mask creation unit 79 using the conversion parameters stored in the storage unit 6 (S355). For the conversion, the same conversion as when the conversion parameter is obtained, for example, affine conversion is used. In FIG. 10, the reference mask M1 is shown in black and the extraction mask M2 is shown in gray. The image extraction unit 74 extracts a measurement target region from the captured image P2 using the extraction mask M2 (S356). Since the change between the retina captured images can be approximated by such simple conversion as movement, rotation, reduction / enlargement, etc., the extraction mask M2 formed by such conversion processing is sufficiently practical.

  Here, the first time t1 and the second time t2 can be arbitrarily selected as long as they are different times. For example, the imaging time at the start of measurement can be adopted as the first time t1, and the subsequent imaging time can be adopted as the second time t2. According to this method, it is possible to form extraction masks from a plurality of subsequent captured images using the same reference mask, so that it can be said that the reference is stable.

  Next, the measurement target region extraction algorithm will be described. In the mask formation unit 73, the reference mask region extraction unit 77 calculates the contrast between the luminance of the measurement target region (blood vessel, retinal arteriovenous, optic nerve head, etc.) and the luminance of the background based on the fundus image, and the high-contrast portion Are extracted as a reference mask region.

As an example of the reference mask area extracted in FIG. 11, an example of an extracted image of the retinal arteriovenous vein and the optic disc is shown. The black portion in the figure is the reference mask area. Among these, the very bright oval part on the left side from the center corresponds to the optic nerve head (the inside of the ellipse may be included in the reference mask area), and the elongated linear part extending radially from that part is the retina. Corresponds to arteriovenous. The reference mask M1 can be formed from the reference mask region extracted in this way. However, instead of taking a large reference mask area as in the example of FIG. 11, as described in the processing flow of FIG. 7, the conversion parameter is obtained only in a local area, thereby reducing the time required for the conversion process. Can be shortened.
The reference mask region can be detected by using the characteristics of the measurement target region as a clue. For example, the retinal arteriovenous blood vessel is linear and has low luminance, the optic nerve head is elliptical, and the choroidal blood vessel is linear and high in luminance. These features can be extracted based on these features.

  FIG. 12 shows an example of the processing flow. Here, a processing algorithm will be described. In the processing process, the processing unit 78 performs processing such as noise removal on the reference mask region extracted by the reference mask region extraction unit 77. First, an average value filter is applied (S501), and then a Laplacian Gaussian filter is applied (S502). The average value filter is an operator that averages the surrounding pixels and removes noise, and the Laplacian Gaussian filter is an operator that removes noise by extracting edges with sharp contrast and applying a Gaussian function to smooth it. is there. Next, one number is assigned and identified by the labeling process having the same characteristic (S503), the point is expanded by the expansion process (S504), and the line is thinned by the thinning process to remove noise. (S505). Next, labeling, that is, assigning attributes to the numbered parts, for example, color display (S506). Next, the line width of the retinal artery and vein is measured (S507). Line width is used as a measure of health status or medical condition. In this way, processing is performed on a measurement target region such as a blood vessel (artery or vein), and a clear measurement target region from which noise is removed is extracted. The formed reference mask M1 is stored in the storage unit 6 under the control of the control unit 8, and is used as the reference mask M1 for extracting the measurement target region from the captured image P1 acquired at the first time t1. .

  In the extraction mask creating unit 79, a conversion process such as affine transformation is performed on the reference mask M1 using the conversion parameter stored in the storage unit 6 to form an extraction mask M2. The mask formed by such image processing can form a reference mask and an extraction mask of a measurement target region suitable for each image without creating a hard mask for any two images having different shooting times, and is flexible. Therefore, it can be used as an extraction mask that is convenient.

  FIG. 13 shows an example of a processing flow for conversion parameter calculation and extraction mask formation. In the image processing unit 7, the captured image acquisition unit 71 reads two captured images P1 and P2 captured at different times by the CCD camera of the light receiving unit 30 (S401). In this embodiment, the comparison target image created from the captured image at the first light receiving unit 31 and the captured image at the second light receiving unit 32 at time t1 instead of the captured images P1 and P2 and the first at time t2. The conversion parameter calculation and extraction mask formation processing is applied to the comparison target image created from the image captured by the light receiving unit 31 and the image captured by the second light receiving unit 32. An example applied to the image P1 and the captured image P2 will be described. Next, the conversion parameter calculation unit 76 selects a plurality of feature points (points that have features and high discriminability, which may be linear) as matching points for image matching from two images (S402). Next, the conversion parameter calculation unit 76 searches for the position of the corresponding matching point (S403). For example, a least square method (LSM) is used for the search.

  In the least square method, the position and shape of the template are fixed, and matching is performed by changing the position and shape of the matching window so that the sum of squares of the difference in density between the matching window and the template is minimized. ) Method. In order to change the position and shape of the matching window, an affine transformation or a Helmat transformation can be selected. For these, the conversion parameter (conversion coefficient) is changed to calculate the difference in shading to obtain the most appropriate conversion parameter (conversion coefficient) (S404). The conversion parameters are stored in the storage unit 6 under the control of the control unit 8. Next, the extraction mask creating unit 79 performs image conversion on the reference mask M1 formed in the reference mask region extracting unit 77 and the processing unit 78 using the obtained conversion parameter (conversion coefficient). An extraction mask M2 is formed (S405). In this case, a linear interpolation method or a bicubic interpolation method can be selected.

  The bicubic method (bicubic method) is an image interpolation method called a cubic interpolation method. In general scanners, there are many models that use the linear interpolation method (calculated by referring to pixels on a straight line passing through two points) and the nearest neighbor method (nearest neighbor method), but the bicubic method uses information. Loss is the least, and a smooth and natural image can be obtained in a photo. However, it takes a long time to perform a complicated operation. In addition, the linear interpolation method is a method in which the value is determined from only the surrounding four pixels while the nearest neighbor method determines the value from only one surrounding pixel. Interpolation accuracy is high.

  Next, the extraction mask M2 converted from the reference mask M1 is stored in the storage unit 6 under the control of the control unit 8 (S406). The formed extraction mask M2 is stored in the storage unit 6 under the control of the control unit 8, and is used as an extraction mask M2 for extracting the measurement target region from the captured image P2 acquired at the second time t2. . For example, a BMP format or a JPG format can be used as the storage format, and it may be output as raw data. The images of the measurement target area extracted by the reference mask M1 and the extraction mask M2 can be compared in time series. In this embodiment, instead of the captured images P1 and P2, the comparison target image created from the captured image at the first light receiving unit 31 and the captured image at the second light receiving unit 32 at the time t1 and the first light receiving unit at the time t2. The reference mask M1 and the extraction mask M2 are formed by applying mask formation to the comparison target image created from the photographed image at 31 and the photographed image at the second light receiving unit 32, and extracted by the reference mask M1 and the extraction mask M2. The aspect of the reaction of each part of the fundus caused by light stimulation is analyzed by comparing the images of the measured area in time series.

  As described above, according to the present embodiment, first, by including a comparison unit 70 that creates a comparison target image from captured images in a plurality of wavelength regions captured at the same timing, and compares them in time series. It is possible to provide a functional imaging ophthalmologic apparatus that can compare comparative events in time series and can detect the reaction of each part of the fundus due to stimulation. Secondly, it is possible to provide a functional imaging ophthalmologic apparatus that can clearly extract a specific portion such as a blood vessel using a comparison target image created from a plurality of captured images having different wavelength ranges. Thirdly, by forming a mask that efficiently extracts the same part from captured images taken at different times, a functional imaging ophthalmologic apparatus that can efficiently extract the same part can be provided.

In the first embodiment, an example in which the reflected light beam is divided into two wavelength regions and received is described. In the second embodiment, an example in which the reflected light beam is divided into three or more wavelength regions and received is described. According to FIG. 3, the amount of absorbed light of oxygenated hemoglobin HbO ₂ and reduced hemoglobin Hb varies greatly depending on the wavelength. Therefore, it is more than determining the oxidized hemoglobin concentration C (HbO ₂ ) and the reduced hemoglobin concentration C (Hb) from the measured values of the optical densities (OD _{x, y} ) _λ1 and (OD _{x, y} ) _{λ2 in} the two wavelength regions. By using the measured values in the wavelength region of, the oxygenated hemoglobin concentration C (HbO ₂ ) and the reduced hemoglobin concentration C (Hb) can be obtained with higher accuracy so as to better match the absorbed light amount pattern. For example, if a two-stage dichroic mirror is used instead of the one dichroic mirror 28 (see FIG. 1) in the first embodiment, the wavelength region can be divided into four. Further, the wavelength region may be divided into four by using a four-dividing prism as the wavelength dividing unit. The light receiving optical system 20 can be configured by receiving the four divided light beams with a CCD camera through a filter and an imaging lens. In addition, images are taken with four CCD cameras at the same timing. By using the measured values of the optical density in the four wavelength regions of the four captured images taken at the same timing, the oxidized hemoglobin concentration C (HbO ₂ ) and the reduced hemoglobin concentration C (Hb) can be obtained with high accuracy. . Moreover, although it is the same as that of Example 1, the time-sequential change of each picked-up image and measurement value in these several wavelength ranges can be compared, and the time-sequential change of the measurement value in each local position is graphed. It is also possible to do. Thereby, it is also possible to directly examine the change at each wavelength. Other apparatus configurations and processing flows are the same as those in the first embodiment.

  In Example 1, an example in which an oxygen saturation image is created as a comparison target image has been described. In Example 3, a difference image between a captured image in the first wavelength region and a captured image in the second wavelength region is used as a comparison target image. An example of creation will be described. In this embodiment, in the first comparison step (S140) of FIG. 2, the captured image in the first wavelength range is compared with the captured image in the second wavelength range, and the difference image is compared in the comparison target image creation step (S150). Create FIG. 3 shows that the absorption sensitivities of oxyhemoglobin and reduced hemoglobin have wavelength dependence, and the absorption sensitivities of both are reversed at a specific wavelength. Therefore, if a difference image between a wavelength with high sensitivity of oxyhemoglobin and a wavelength with high sensitivity of deoxyhemoglobin is created, the blood vessel portion can be extracted more clearly. Further, when the difference image is created, an image is obtained by removing a portion where the light absorption sensitivity does not change depending on the wavelength, so that a portion where the light absorption sensitivity changes depending on the wavelength, for example, blood vessels (arteries, veins) can be extracted with low background noise. In the present embodiment, in this way, in the first comparison mode, the comparison unit 70 creates a difference image between the captured image in the first wavelength region and the captured image in the second wavelength region as the comparison target image, and the blood vessel (artery) Extract veins). In the second comparison mode, the extracted blood vessels (arteries and veins) are compared in time series, and the reaction of the blood vessels (arteries and veins) due to the stimulation is detected. As a time-series comparison, the average intensity of the local portion may be calculated from the difference image and graphed. Accordingly, the image analysis unit 75 can perform analysis specified for the blood vessel (artery, vein) portion. Other apparatus configurations and processing flows are the same as those in the first embodiment. According to the present embodiment, it is possible to provide a functional imaging ophthalmologic apparatus that can clearly extract a specific portion such as a blood vessel portion by using a difference image of captured images having different wavelength ranges.

  In the first embodiment, an example in which both the first comparison mode and the second comparison mode are executed and both results are displayed has been described. However, in the fourth embodiment, only the second comparison mode is executed and the comparison result is displayed. An example will be described. Differences from the first embodiment will be mainly described.

  FIG. 14 shows an example of the processing flow of the eye function image analysis method in the present embodiment. Compared to FIG. 2, there is no wavelength division step (S120), first comparison step (S140) to first display step (S155), and instead of the light receiving step (S130) in a plurality of wavelength regions at the same timing, 1 in total. There are two light receiving steps (S135). In the second comparison step (S170), the captured images before and after stimulation or images processed based on the captured images are compared in time series. In the apparatus configuration, in FIG. 1, the wavelength division unit 28 is eliminated, and the light receiving optical system 20 and the light receiving unit 30 become one. With this configuration, quantitative changes such as oxygen saturation in the blood vessel cannot be detected, but changes in the amount of absorbed blood in the blood vessel can be detected due to changes in the oxygen concentration. Is possible. If a wavelength tunable filter is inserted in front of the light receiving unit 30, it is possible to receive light in a plurality of wavelength regions although the time is different. Other apparatus configurations and processing flows are the same as those in the first embodiment.

  In the first embodiment, an example in which both the first comparison mode and the second comparison mode are executed and both results are displayed has been described. In the fifth embodiment, only the first comparison mode is executed and the second comparison mode is executed. An example of not performing will be described. Differences from the first embodiment will be mainly described.

  FIG. 15 shows a processing flow example of the eye function image analysis method. Compared to FIG. 2, the pre-stimulus middle and post course determination step (S105), the repetition number determination step (S160), the second comparison step (S170), and the second display step (S175) are deleted. That is, the measurement may be performed once during stimulation or once after stimulation. Other steps are the same as those in the first embodiment. That is, the captured image in the first wavelength region and the captured image in the second wavelength region in the light receiving step (S130) are compared (first comparison step: S140), and a comparison target image is created (comparison target image creation step: S150). When a difference image between the image captured by the first light receiving unit 31 and the image captured by the second light receiving unit 32 is created as a comparison target image, an image in which a portion where the light absorption sensitivity does not change depending on the wavelength is obtained. Thus, a portion where the light absorption sensitivity changes, for example, blood vessels (arteries, veins) can be extracted with low background noise. Further, an oxygen saturation image may be created as a comparison target image. The optical system configuration is represented in FIG.

  In the first embodiment, an example in which both the first comparison mode and the second comparison mode are executed and both results are displayed has been described. However, in the sixth embodiment, the display of the first comparison mode is omitted and the second comparison mode is displayed. An example of mode display will be described. Differences from the first embodiment will be mainly described. In the processing flow of the eye function image analysis method using the functional imaging ophthalmologic apparatus, only the first display step S155 is omitted from FIG. Nevertheless, if the comparison target image is displayed in time series in the second display step (S175), it is included in the display. The optical system configuration is represented in FIG. Therefore, the same effects as those of the first embodiment are obtained.

  In the first embodiment, in the case where light stimulation is applied and repeated measurement is performed, the imaging time at the start of measurement is used as the first time t1, and the subsequent imaging time is used as the second time t2. Other choices are possible. In Example 4, the imaging time at the start of measurement is the first time t1, the reference mask M1 is formed based on the first captured image P1 at the first time t1, and the second imaging time is set to the second time. After forming the mask M2 for extracting the measurement target region from the second captured image P2 at the time t2 of 2 using the reference mask M1 and the conversion parameter, the second imaging time is the first time t1, The photographed image is used as the first photographed image P1, the extraction mask formed at that time is used as a new reference mask M1, the third photographed time is the second time t2, and the photographed image at that time is the second photographed image. Let P2 be a new extraction mask M2 which is a mask formed to extract the measurement target region from the second captured image P2 at that time. In this way, it is also possible to sequentially form a new extraction mask M2 with a new reference mask M1. According to this method, since the interval between the first time t1 and the second time t2 can be shortened, the degree of conversion is always reduced, and an extraction mask M2 with less errors can be obtained. Other optical system configurations and processing flows are the same as those of the first embodiment, and the same effects as those of the first embodiment are obtained.

  In Example 1, when repeated measurement is performed with light stimulation, the imaging time at the start of measurement in each repetition is used as the first time t1, and the subsequent imaging time is used as the second time t2. While described, other options are possible. In the eighth embodiment, the first time t1 is an imaging time during which the measurement target region is most clearly imaged by a reaction caused by light stimulation. This makes it easy to obtain a clear reference mask and facilitates the formation of the reference mask M1. Also, conversion processing can be performed by setting the first time t1 as the first time t1 and the other time t2 as the second time t2 of all the captured images. By doing this, the amount of change in the overall position can be suppressed, and a stable converted image can be obtained. Other optical system configurations and processing flows are the same as those of the first embodiment, and the same effects as those of the first embodiment are obtained.

  In the first embodiment, in the second comparison mode, an example has been described in which a mask is formed to extract a fundus measurement target region by image processing, and the measurement target regions extracted by the mask are compared in time series. In the ninth embodiment, an example will be described in which alignment between images is performed and measurement target regions are compared in time series. Differences from the first embodiment will be mainly described. In this embodiment, the comparison target image created from the captured image at the first light receiving unit 31 and the captured image at the second light receiving unit 32 at time t1 instead of the captured images P1 and P2 and the first at time t2. The alignment between the images is applied to the comparison target image created from the photographed image at the light receiving unit 31 and the photographed image at the second light receiving unit 32. Here, for simplicity of explanation, the photographed image P1 and the photographed image are captured. An example applied to the image P2 will be described. The captured image includes an image obtained by processing the captured image.

  FIG. 16 shows a configuration example of the image processing unit 7 in the ninth embodiment. Other configurations are the same as those of the first embodiment (see FIG. 1). The image processing unit 7 does not have the mask forming unit 73, and instead of this, the registration unit 72 performs alignment between captured images acquired at different times. The processing flow of registration between images performed by the registration unit 72 is similar to the processing flow of FIG. That is, the alignment unit 72 performs the steps from selection of matching points for image matching (S402) to image conversion (S405), but the image to be converted here is not a mask but is taken at the first time t1. The captured image P1 (reference image) and the captured image P2 (pre-correction image) captured at the second time t2. Then, the converted corrected image is used as a new reference image, and the captured image taken at the next time is used as a new pre-correction image, so that image matching matching point selection (S402) to image conversion (S405) are sequentially performed. Is done. Further, the image extraction unit 74 extracts the measurement target region from the image aligned by the alignment unit 72. For this extraction, for example, an extraction algorithm in the reference mask region extraction unit 77 in the first embodiment can be applied. Other processing flows are the same as those described in the first embodiment with reference to FIG.

  In this embodiment, instead of the captured images P1 and P2, the comparison target image created from the captured image at the first light receiving unit 31 and the captured image at the second light receiving unit 32 at the time t1 and the first light receiving unit at the time t2. By applying the alignment between the images to the comparison target image created from the captured image at 31 and the captured image at the second light receiving unit 32, the images in the measurement target region are compared in time series in the second comparison mode. Thus, the reaction of each part of the fundus by light stimulation is analyzed. In this way, if alignment between images is performed, a time-series comparison without using a mask is also possible.

  In Example 1, although the example which uses a light stimulus as a kind of irritation | stimulation was demonstrated, in Example 10, the example which uses transcorneal electrical stimulation is demonstrated. Transcorneal electrical stimulation is, for example, electrical stimulation of the retina transcorneally using a contact lens type electrode, and neuroprotective treatment is expected. A pulse power source for electrically stimulating the retina transcorneally by eliminating the stimulation light source 41, the condenser lens 42, and the reflecting mirror 43 that are the irradiation system of the optical stimulation optical system 40 in the optical configuration of the first embodiment. If a lead wire or contact lens type electrode is added, the optical configuration of FIG. 1 can be used. The processing flow of the eye function image analysis method using the functional imaging ophthalmologic apparatus uses electrical stimulation instead of light stimulation. Other configurations and processing flow are the same as those in the first embodiment. Thereby, the reaction of the eye to be examined due to electrical stimulation can be detected. Note that as the electrical stimulation, scleral single-point stimulation that applies electrical stimulation to a local portion on the sclera may be used.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it is obvious that various modifications can be made to the embodiments without departing from the spirit of the present invention. .

  For example, the illumination light source is not limited to a halogen lamp as long as it can emit a light beam in the near infrared region of about 700 nm to 900 nm, and laser light may be used. Further, the wavelength division unit is not limited to the dichroic mirror, and other beam splitters may be used. Also, the image processing flow can be changed. For example, the processing step may be omitted from the reference mask formation step, or the reference window region determined when obtaining the conversion parameter may be used to obtain the reference mask region. good. Further, for example, a measurement target region may be extracted from a photographed image at a wavelength at which the sharpest image can be obtained using a characteristic such as a blood vessel, and a reference mask may be formed. In the above embodiment, an example in which the amount of absorbed light of hemoglobin is compared and analyzed has been described. However, it is also possible to measure the spectral distribution of components other than hemoglobin. Further, by accumulating the light reception signal intensity data of the blood vessel as the measurement target region in the storage unit, it is possible to use the accumulated blood vessel data for diagnosis or the like. In addition, the stimulus application conditions, the wavelength range, the imaging conditions, and the like can be changed as appropriate.

  The present invention can be used for a functional imaging ophthalmic apparatus. In particular, it can be used in a functional imaging ophthalmologic apparatus that measures changes in spectral characteristics of an eye due to stimulation using captured images in a plurality of wavelength ranges.

DESCRIPTION OF SYMBOLS 1 Functional imaging ophthalmologic apparatus 2 Fundus camera part 3 Top housing part 7 Image processing fixed part 6 Memory | storage part 8 Control part 9 Display part 10 Illumination optical system 11 Halogen lamp 12 Condenser lens 13 Spectral characteristic correction filter 14 Diaphragm plate 15 Reflecting mirror 16 Relay Lens 17 Beam splitter 18 Objective lens 20 Light receiving optical system 20A First light receiving optical system 20B Second light receiving optical system 21 Iris diaphragm plate 22 Focusing lens 23 Imaging lens 24 Reflecting mirror 25 Switching mirror 26 Field lens 27 Dichroic mirror 28 Dichroic mirror (wavelength division unit)
30 Light-receiving unit 31 First CCD camera (first light-receiving unit)
32 2nd CCD camera (2nd light-receiving part)
34 Filter 35 Imaging lens 36 Filter 37 Imaging lens 40 Stimulating optical system 41 Stimulating light source 42 Condenser lens 43 Reflecting mirror 44 Dichroic mirror 50 Alignment optical system 51 Alignment light source 53 Imaging lens 54 Third CCD camera 60 Viewfinder optics System 70 Comparison unit 70a First comparison unit 70b Second comparison unit 71 Captured image acquisition unit 72 Position adjustment unit 73 Mask formation unit 74 Image extraction unit 75 Image analysis unit 76 Conversion parameter calculation unit 77 Reference mask region extraction unit 78 Processing unit 79 Extraction mask creation unit 80 Condition setting unit 81 Elapsed time determination unit 82 Repeat count determination unit A1 Reference window region A2 Extraction window region E Eye fundus M1 Reference mask M2 Extraction mask P1 First captured image P2 Second imaging Image t1 first time t2 second time

Claims (10)

An illumination optical system that illuminates the fundus of the subject's eye with a near-infrared illumination beam;
A stimulating light irradiation optical system for irradiating the measurement target region of the fundus with a stimulating light beam in a visible range;
A wavelength division unit that divides the reflected light beam from the fundus of the illumination light beam into light beams in a plurality of near-infrared wavelength regions;
A light receiving unit that receives light beams in a plurality of wavelength regions divided by the wavelength division unit at the same timing before and after stimulation with the stimulation light beam;
A first comparison unit that creates a comparison target image from a plurality of captured images in a plurality of wavelength ranges captured at the same timing by the light receiving unit, and a comparison target image created by the first comparison unit are compared in time series. A comparison unit having a second comparison unit;
A display unit for displaying a comparison result in the comparison unit;
Functional imaging ophthalmic device. An illumination optical system that illuminates the fundus of the subject's eye with a near-infrared illumination beam;
A stimulating light irradiation optical system for irradiating the measurement target region of the fundus with a stimulating light beam in a visible range;
A wavelength division unit that divides the reflected light beam from the fundus of the illumination light beam into light beams in a plurality of near-infrared wavelength regions;
A light receiving unit that receives light beams in a plurality of wavelength regions divided by the wavelength division unit at the same timing before and after stimulation with the stimulation light beam;
A comparison unit that creates a comparison target image from captured images in a plurality of wavelength ranges captured at the same timing by the light receiving unit;
A display unit for displaying the comparison target image;
Functional imaging ophthalmic device. An illumination optical system that illuminates the fundus of the subject's eye with a near-infrared illumination beam;
A stimulating light irradiation optical system for irradiating the measurement target region of the fundus with a stimulating light beam in a visible range;
A light receiving unit that receives a reflected light beam from the fundus of the illumination light beam;
A comparison unit that chronologically compares a captured image captured at a plurality of times by the light receiving unit or an image created based on the captured image;
A display unit for displaying a comparison result in the comparison unit;
Functional imaging ophthalmic device. The comparison target image is an oxygen saturation image created from the captured images in the plurality of wavelength ranges;
The functional imaging ophthalmic apparatus according to claim 1 or 2. The comparison target image is a difference image between captured images in two wavelength regions of the plurality of wavelength regions;
The functional imaging ophthalmic apparatus according to claim 1 or 2. An image analysis unit that analyzes a reaction of the eye to be examined by stimulation with the stimulation light beam from a comparison result in the comparison unit;
The functional imaging ophthalmic apparatus according to claim 1 or 3. Of the plurality of wavelength ranges, the first wavelength range and the second wavelength range are set across an intersection of spectral density characteristics of oxyhemoglobin and reduced hemoglobin of blood;
The functional imaging ophthalmic apparatus according to claim 1 or 2. The first wavelength range is 730 to 780 nm, and the second wavelength range is 820 to 880 nm;
The functional imaging ophthalmic apparatus according to claim 7. The stimulation light beam is irradiated to the measurement target region by a diaphragm or a slit;
The functional imaging ophthalmic apparatus according to any one of claims 1 to 8. An illumination process for illuminating the fundus of the subject's eye with a near-infrared illumination beam;
A stimulating light irradiation step of stimulating by irradiating the measurement target area of the fundus with a stimulating light beam in a visible range;
A wavelength division step of dividing the reflected light beam from the fundus of the illumination light beam into light beams in a plurality of near-infrared wavelength regions;
A light receiving step of receiving light beams in a plurality of wavelength regions divided by the wavelength division unit at the same timing before and after stimulation in the stimulation light irradiation step;
A first comparison step of creating a comparison target image from a plurality of captured images in a plurality of wavelength ranges that are captured at the same timing in the light receiving step;
A second comparison step of comparing the comparison target images created in the first comparison step in time series;
A display step of displaying a comparison result in the second comparison step;
Eye function image analysis method.