JP2005296400A - Fundus spectral image photographing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fundus spectral image photographing device including a processing method of observational measurement data, for reducing a detection error in a lesion, while coping with various lesions of the fundus from its image, by acquiring clear spectral data over the whole fundus, by easily adjusting a device of examining the fundus. <P>SOLUTION: This fundus spectral image photographing device has a first optical system 2 for forming a fundus image of optometry, a slit 4 arranged in a fundus conjugate position of the first optical system 2, a second optical system 3 for forming a spectrum of making spectral diffraction of the fundus image formed by the first optical system 2 by a spectral element 6, a two-dimensional imaging element 7 arranged in an image forming position of the fundus spectral image formed by the second optical system 3, and a means for acquiring the fundus image by scanning one or more of the respective elements in the direction orthogonal to the longitudinal direction of a slit opening. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus that measures the blood flow state of the fundus by irradiating the fundus with light and performing spectrum analysis of the reflected light.

  Conventionally, as a method for inspecting the state of the retina of the fundus, a photograph is taken with a fundus camera, and the medical condition is judged from the photograph. (See, for example, Patent Document 1) At the time of taking a photograph, a drug was sometimes administered to open the pupil. In particular, in order to examine the blood flow state of the retina, a method called fluorescent fundus imaging is employed. In order to continuously observe the state of the fundus, it is common to take a picture with a video camera while keeping the pupil open and display it on a monitor. However, in this fluorescence fundus photography, there is a risk that unexpected damage may occur to the patient due to drug administration, and this is not necessarily the optimal examination method.

  On the other hand, although not the fundus, a method is disclosed in which the optical characteristics of the lens are examined to enable diagnosis of cataracts and the like. (For example, refer to Patent Document 2) In cataract, the lens is cloudy and the light transmittance is reduced, but the transmittance varies depending on the position of the lens and also on the wavelength of light. In order to inspect such a lens, a slit is placed at a nearly conjugate position through the lens and lens, and an image passing through the slit is passed through a spectrometer to obtain a spectral image. There is an apparatus having a structure for obtaining spectral data of the entire surface of a crystalline lens by scanning on a plane.

  In the examination of the fundus, it is important to observe the state of blood vessels and blood flow on the retina. Conventionally, as described above, a photograph is taken and the judgment is made based on the image and color. In such a method, since it is not clear whether there is a blood flow that can supply oxygen to the blood vessels on the retina, a misdiagnosis may occur.

In addition, when the image passing through the slit as described above is passed through a spectroscope to obtain a spectroscopic image and the slit and spectroscope are scanned to measure using a device that obtains spectroscopic data, the fundus Since it is spherical, there is a problem that the image is blurred in the periphery in the plane scanning as described above.
JP 2001-353128 A JP 2002-224041 A

  The object of the present invention is to solve the above problems, to easily adjust the apparatus for fundus examination, to acquire clear spectral data over the entire fundus, and to deal with various lesions of the fundus from the image. Furthermore, another object of the present invention is to provide a fundus spectroscopic imaging apparatus including an observation measurement data processing method that reduces lesion detection errors.

  The fundus spectral image capturing apparatus according to the present invention is arranged at the fundus conjugate position of the first optical system as means for forming a fundus image of the eye to be inspected and the first optical system. And a second optical system as means for imaging the spectrum of the fundus image light imaged by the first optical system after passing through the slit and spectrally separated by a spectroscopic element, A two-dimensional imaging device arranged at the imaging position of the fundus spectral image formed by the optical system and one or more of the above elements are scanned in a direction perpendicular to the longitudinal direction of the slit by a predetermined scanning means. Means for acquiring the fundus image.

  With such a configuration, the first optical system forms an image of the fundus position conjugate with the slit position as a fundus image at the slit position. Since light from the fundus always forms a sharp image of the fundus at the position of the slit, the fundus image at each position can pass through the slit by scanning one or more optical systems. Therefore, clear spectroscopic data can be acquired over the entire fundus, and there is an effect of reducing lesion detection errors.

  According to the fundus oculi spectroscopic imaging device of the second aspect, since the rotating mirror is provided near the pupil conjugate plane of the first optical system, it is substantially equivalent to scanning the inside of the eyeball from the position of the pupil with the rotating mirror. The effect of can be obtained. Therefore, it is possible to obtain clear spectral data over the entire fundus with a simple device.

  According to the fundus spectral image capturing apparatus of the third aspect, since the means for simultaneously scanning the slit, the second optical system, and the two-dimensional imaging device is provided, the slit and the second optical system are arranged along the imaging position of the fundus image. The two optical systems and the two-dimensional image sensor can be scanned simultaneously. Therefore, there is an effect that clear spectral data can be acquired over the entire fundus.

  According to the fundus oculi spectroscopic imaging device according to the fourth aspect of the present invention, since the means for simultaneously rotating and scanning the first optical system, the slit, the second optical system, and the two-dimensional image sensor is provided, the pupil position of the eye to be examined The optical axis of the first optical system, the slit, and the second optical system can be rotationally scanned around the center, and the image of the fundus that is a spherical surface can be clearly obtained as a fundus image on the optical axis with little distortion. Can be imaged.

  According to the fundus oculi spectroscopic imaging device of the fifth aspect, the fundus oculi image formed by the first optical system is provided with a third optical system that re-images the image at a position other than the slit position. That is, a half mirror or a dichroic mirror (for example, visible light transmission, infrared light reflection) is installed in the optical path before entering the slit, and the fundus image re-formed by the third optical system is directly observed, or through a video camera. By observing with a monitor, it is possible to reliably perform alignment and focus adjustment with respect to the eye to be examined. By doing so, adjustment is easy, and clear spectral data can be acquired over the entire fundus.

  According to the fundus oculi spectroscopic imaging device of the sixth aspect, the spectroscopic element is a prism, a diffraction grating, or a combination of both. A prism is the simplest, but a diffraction grating is better for increasing the resolution. In particular, a transmissive diffraction grating is suitable for making the second optical system compact. In this way, the fundus image can be easily spectrumd, and clear spectral data can be acquired over the entire fundus by scanning the optical system.

  According to the fundus oculi spectroscopic imaging device according to claim 7, since the spectroscopic image of the two-dimensional image sensor is provided as one frame, and includes means for accumulating the spectroscopic image frame for each scanning step in synchronization with the rotational scanning. N frames of spectral images are obtained by scanning in N steps, and a spectral spectrum in the scanned region as a whole is obtained. Therefore, it is possible to observe the fundus region by focusing on the light having a wavelength specific to the lesion from the spectral spectrum, or to analyze it by an analysis method such as multivariate analysis, which can reduce the detection error of the lesion. .

  According to the fundus oculi spectroscopic imaging device according to the eighth aspect of the present invention, the fundus spectroscopic imaging apparatus includes means for setting the fundus range to be imaged in advance and means for instructing the start of imaging. When the determination is made and the start of imaging is instructed, fundus spectroscopic imaging of a desired region can be easily performed. Since the analysis result of the spectral image is obtained in real time, there is an effect that the detection of the lesion can be surely performed as compared with the conventional photography.

  According to the fundus spectral image capturing apparatus of the ninth aspect, the white plate or the artificial eye painted in white is placed at a position corresponding to the fundus of the eye to be examined, and the reference value of the spectral spectrum is calibrated. It is possible to easily correct fluctuations in luminance and emission spectrum, and to acquire more accurate data. As a result, the reliability of the analysis result of the spectral image is increased, and there is an effect that the lesion can be reliably detected.

  According to the fundus oculi spectroscopic imaging device according to claim 10, the means for plotting the absorbance data of the spectral spectrum in which the frames of the spectral image are accumulated in the spectral multidimensional space of light, and the spectral multidimensional space obtained from the plurality of positions Means for obtaining eigenvectors of at least the first, second, and third principal components by multivariate analysis of the data, and projecting the data at each position in the direction of each eigenvector, and displaying the magnitude in a two-dimensional manner Means for displaying on the screen in a gray scale or a color corresponding to the size. By such means, for example, it is possible to know the amount of oxygen bound to hemoglobin in the capillaries of the fundus, and there is an effect that various lesions can be reliably detected.

  According to the present invention, as described above, it is easy to adjust the apparatus for fundus examination, and it is possible to acquire clear spectral data over the entire fundus and deal with various lesions of the fundus from the image. This has the effect of reducing detection errors of lesions.

  Hereinafter, preferred embodiments of the present invention will be described. FIG. 1 shows a schematic view of a fundus spectral image capturing apparatus according to the present invention. In FIG. 1, 1 is the fundus of the eye to be examined, 2 is a first optical system, 3 is a second optical system, 4 is a slit, 5 is a third optical system, 6 is a spectroscopic element, and 7 is a two-dimensional image sensor. It is.

  The first optical system 2 includes optical components such as an objective lens 21, a perforated mirror 22, a diaphragm 23, an illumination optical system lens 24, a relay lens 25, a focus lens 26, and an imaging lens 27. The fundus is illuminated by the light from the light source (not shown) through the illumination optical system lens 24, reflected by the perforated mirror 22, and through the objective lens 21.

  The reflected light from the fundus passes through the holes of the objective lens 21 and the perforated mirror 22, passes through the aperture 23 placed at a conjugate position with the pupil, and then reaches the fundus image with the relay lens 25, the focus lens 26, and the imaging lens 27. Is imaged.

  The third optical system 5 includes a mirror 13 and a camera 14. The mirror 13 is a half mirror or a dichroic mirror (for example, visible light reflection, infrared light transmission).

  In the case of a half mirror, a part of the light from the eyeball is bent by 90 degrees and reflected, and an image of the fundus can be taken by the camera 14 and directly observed on the monitor 15. The other part of the light from the eyeball passes through the half mirror, passes through the slit 4, is split by the spectroscopic element 6, forms an image on the two-dimensional image sensor 7, and is stored in the means 8 for storing the spectroscopic image. . The storage means 8 may be any commonly used semiconductor memory, magnetic recording device, optical memory, or the like. When the mirror is a dichroic mirror (for example, visible light reflection, infrared light transmission), the visible light is refracted and reflected by 90 degrees, and the image can be observed on the monitor 15 as described above. Further, infrared light is transmitted and the spectral image is accumulated.

  Reference numeral 9 denotes a device that scans the first optical system, the second optical system, the slit, the spectroscopic element, the two-dimensional image sensor, and the like, and is controlled by the control device 10 in conjunction with the storage means 8. Reference numeral 11 denotes a device for analyzing the accumulated spectral image, and the result is displayed on the monitor 12.

  The slit is a linear opening, and an image of one line in the fundus corresponding to the slit is split in a direction perpendicular to the slit to form an image on one frame of the two-dimensional image sensor. That is, assuming that the slit direction is the X-axis direction of the two-dimensional image sensor, the X-axis direction corresponds to one line in the fundus, and the incident light at each point on the one line is dispersed in the Y-axis direction. The light intensity in the spectrum corresponds.

  When an image of a line in the fundus is sequentially scanned in a direction orthogonal to the slit and imaged by a two-dimensional image sensor, an N-step two-dimensional spectral image can be obtained by performing N-step scanning.

  Next, the scanning means will be described. FIG. 2 shows an outline of a scanning method using a mirror as the first embodiment. Corresponding to FIG. 1, parts having the same functions and configurations are denoted by the same reference numerals. In FIG. 2, 20 is a mirror for scanning. The mirror 20 is installed in the vicinity of the pupil conjugate plane of the first optical system, and rotates about a line passing through the optical axis of the first optical system and orthogonal thereto. The optical axis of the first optical system is bent at a substantially right angle by the mirror 20, and a slit 4, a second optical system, a two-dimensional image sensor, and the like are disposed at the tip.

  Since the mirror 20 is installed in the vicinity of the pupil conjugate plane of the first optical system, the effect of rotating the mirror 20 is substantially equivalent to scanning the inside of the eyeball from the position of the pupil with the rotating mirror. Can be obtained. Thereby, it is possible to clearly form a fundus image that is a curved surface and obtain a clear fundus spectral image.

  FIG. 3 shows a second embodiment relating to the scanning means. As shown in FIG. 3, the scanning means regards the slit 4, the second optical system 3, and the two-dimensional imaging device 7 as an integrated body 30, and scans integrally. That is, since the fundus image is formed at the position of the slit 4, if the slit 4, the second optical system 3, and the two-dimensional image sensor 7 are scanned together, a clear fundus image can be obtained.

  A third embodiment relating to the scanning means is shown in FIG. In the third embodiment, the first optical system, the slit 4, the second optical system 3, and the two-dimensional image pickup device 7 that are regarded as one unit are rotated and scanned around the position of the pupil. . Further, the third optical system 5 may be included in the above-described one 40. In this embodiment, since the first optical system, the slit 4, the second optical system 3, and the two-dimensional image sensor 7 are integrated and rotationally scanned around the position of the pupil, the fundus image is obtained by the two-dimensional image sensor. 7 always forms a clear image.

  The scanning in these embodiments is performed by the control device 10 by the scanning device 9 and the spectral image is accumulated in the accumulating device 8 at the same time.

  The spectroscopic element 6 in the second optical system 3 is basically a prism, but a transmission type diffraction grating is used in order to increase the resolution of the spectrum. Alternatively, a combination of a prism and a diffraction grating may be used.

  Next, processing of the spectral image stored in the storage device 8 will be described. First, in order to normalize the spectral sensitivity, a white plate or a pseudo eye painted in white is placed at a position corresponding to the fundus of the subject's eye, and the reference value of the spectral spectrum is calibrated. Analysis is performed based on the spectral image thus obtained.

  The light used for the optometry may be visible light, but it will cause the pupil to contract, so generally a drug is administered to open the pupil. However, only a short test is possible because it causes pain to the subject. Therefore, light in the infrared region that is not felt by the eyes is used. The wavelength of light in the infrared region is 700 nm to 1000 nm.

  As an example of spectral image analysis, a spectral image at a wavelength of 720 nm is imaged. As a specific method, data of a portion corresponding to a wavelength of 720 nm is extracted from the spectral images from the first frame to the Nth frame stored in the storage device 8 and sequentially displayed on one screen. By arranging them side by side, a fundus image observed at a wavelength of 720 nm can be obtained. An example of the pseudo fundus image obtained by such a procedure is shown in FIG. When observing at a wavelength of 720 nm, the pseudo blood vessels appear as bright streaks in FIG. 5, and thus the blood vessels of the pseudo fundus can be observed clearly.

  In general, when observing with light of a specific wavelength, a filter is often used. However, in order to use a filter, not only the installation space is required, but if the observation is performed at a different wavelength, it is necessary to replace the filter, which takes extra time. In this apparatus, data at all wavelengths from 700 nm to 1000 nm are accumulated, so that observation results at the required wavelength can be obtained immediately by operating the analysis apparatus.

  As a second embodiment of spectral image analysis, multivariate analysis in a wavelength space is performed. As a specific method, the spectrum data obtained at each position is plotted in a spectrum multidimensional space. For example, if there is a specific absorption band due to oxyhemoglobin in the blood between 700 nm and 800 nm, the data from 700 nm to 800 nm is acquired, and this is divided by the minimum resolution of 5 nm. The absorbance (arbitrary unit) is obtained and plotted as one point per position in the divided 20-dimensional space.

  For example, if the sample size is 3 mm square and the minute area to be detected is 0.03 mm square, spectral data from 10,000 minute areas can be obtained. For example, for the purpose of improving the S / N ratio, if the data of four minute regions is averaged to be one data, the data finally obtained is 2,500. The 2500 spectral data are plotted in the 20-dimensional spectral space.

  Next, a multivariate analysis method such as principal component analysis is used to determine the direction in which the variance of 2,500 points is maximized as the first principal component in the 20-dimensional spectrum space. The direction is the eigenvector of the first principal component. Further, each plot point is projected onto a space orthogonal to the first eigenvector to obtain a second principal component, which is used as the second principal component eigenvector. Further, eigenvectors of the third,... N principal components and the third,.

  In this way, the eigenvectors of the first principal component, the eigenvectors of the second principal component, and the eigenvectors of the third principal component are determined, and the 2,500 plotted data are projected onto the respective eigenvectors. That is, the component in each eigenvector direction is obtained. Although the magnitude of this component is called a score, the score for each eigenvector direction is plotted at each position of the sample with a gray scale or a color corresponding to the value of the score to perform two-dimensional display.

  In general, since the score of the first principal component is an average value, a unique phenomenon is difficult to appear, but a phenomenon that is unique to the scores of the second principal component and the third principal component often appears. In this example, a phenomenon appears in which the score value of the portion where the reduced hemoglobin in the blood is large becomes high. By detecting such a singular point, it is possible to find a lesion and its precursor.

  As described above, the fundus spectral imaging apparatus according to the present invention acquires clear spectral data over the entire fundus, can handle various lesions of the fundus from the image, and can further reduce lesion detection errors. The effect is obtained.

  Note that the present invention is not limited to the above-described embodiments, and some changes and replacements by those skilled in the art based on the spirit and idea of the present invention belong to the scope of the claims of the present invention.

1 is a schematic view of a fundus spectral image capturing apparatus according to the present invention. Schematic explaining the 1st Example regarding the scanning method in the fundus | tracheal spectroscopic imaging device by this invention. Schematic explaining the 2nd Example regarding the scanning method in the fundus | tracheal spectroscopic imaging device by this invention. Schematic explaining the 3rd Example regarding the rotational scanning method in the fundus | tracheal spectroscopic imaging device by this invention. Spectral image of pseudo fundus obtained by photographing with fundus spectral image photographing apparatus according to the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fundus 2 1st optical system 3 2nd optical system 4 Slit 5 3rd optical system 6 Spectroscopic element 7 Two-dimensional image sensor 8 Accumulation means 9 Scanning device
10 Control unit
11 Analyzer
12 Monitor
13 Mirror
14 Camera
15 Monitor
20 mirror
21 Objective lens
22 perforated mirror
23 Aperture
24 Illumination optics lens
25 Relay lens
26 Focus lens
27 Imaging lens

Claims (10)

A first optical system as means for forming a fundus image of the eye to be inspected, a slit disposed at a fundus conjugate position of the first optical system, and fundus image light imaged by the first optical system A second optical system as means for forming an image of a spectrum that passes through the slit and then spectrally separated by a spectroscopic element, and two-dimensionally arranged at an imaging position of a fundus spectral image formed by the second optical system An eye fundus comprising: an imaging element; and means for acquiring one or more of the above-described elements by scanning with a predetermined scanning means in a direction orthogonal to the longitudinal direction of the slit. Spectral image imaging device. The fundus spectral image capturing apparatus according to claim 1, wherein a rotating mirror is provided near the pupil conjugate plane of the first optical system as the scanning unit. The fundus spectral image capturing apparatus according to claim 1, wherein the scanning unit is configured to simultaneously scan the slit, the second optical system, and the two-dimensional image sensor. The scanning means is configured to rotate and scan the first optical system, the slit, the second optical system, and the two-dimensional imaging device simultaneously around the pupil position of the eye to be examined. The fundus oculi spectral image capturing device according to 1. 5. The apparatus according to claim 1, further comprising a third optical system as means for re-imaging a fundus image formed by the first optical system at a position other than the slit position. The fundus spectral image capturing apparatus according to claim 1. The fundus spectral image capturing apparatus according to claim 1, wherein the spectroscopic element is a prism, a diffraction grating, or a combination of both. 7. The apparatus according to claim 1, further comprising means for accumulating the spectral image frame for each scanning step in synchronism with the scanning with the spectral image of the two-dimensional imaging device as one frame. The fundus spectral imaging apparatus according to one of the above. 8. The fundus spectral image capturing apparatus according to claim 7, further comprising means for setting a fundus range to be photographed in advance and means for instructing start of photographing. 9. The fundus spectrum according to claim 1, wherein the reference value of the spectral spectrum is calibrated by placing a white plate or a false eye painted in white at a position corresponding to the fundus of the eye to be examined. Image pickup device. Means for plotting the absorbance data of the spectral spectrum in which the frames of the spectral image are accumulated in a spectral multidimensional space of light; and multivariate analysis of spectral multidimensional space data obtained from the plurality of positions, so that at least Means for obtaining eigenvectors of the first, second, and third principal components, and projecting the data of each position in the direction of each eigenvector, and the size of the two-dimensional display screen in a color corresponding to gray scale or size The fundus spectral image capturing apparatus according to claim 7, further comprising a display unit.