JP2008188139A - Retina function measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately detect an endogenous signal of a retina. <P>SOLUTION: This retina function measuring instrument is provided with an imaging optical system having an imaging element for acquiring a fundus oculi image, a stimulating light irradiation optical system irradiating a visible stimulating light and stimulating the retina, a storage part for storing the fundus oculi image acquired based on the imaging signal from the imaging element, and a change information acquisition means comparing the fundus oculi image before irradiating the stimulating light with the fundus oculi image after irradiating the stimulating light and acquiring change information of the fundus oculi images by computation. This instrument finds the distribution of luminous unevenness by an image processing using at least two fundus oculi images of a first fundus oculi image captured before irradiating the stimulating light to a subject eye and a second fundus oculi image whose photographing position is deflected from the first fundus oculi image by the computation, and performs shading correction to the fundus oculi images before and after irradiating the stimulating light respectively. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an apparatus for photographing the fundus and measuring the function of the retina.

2. Description of the Related Art Conventionally, devices that non-invasively image retinal functions are known. This device has illumination means for illuminating the retina and retinal stimulation illumination means for irradiating stimulation light that induces the functional response of the retina. An attempt is made to measure retinal function by obtaining an intrinsic signal (see Patent Document 1). Note that the apparatus disclosed in Patent Literature 1 aligns retinal images before and after stimulation light irradiation in advance, and detects changes in retinal function from the images after alignment, so that retinal images based on the movement of the eye to be inspected. The misalignment is corrected.
International Publication No. 2005-084526 Pamphlet

  By the way, when measuring the function of the retina as described above, since the light amount change of the retina image is obtained by the brightness ratio or difference of the photographed image before and after the irradiation of the stimulation light, the cornea, the crystalline lens, etc. Even if there is luminance unevenness caused by the intermediate light transmitting device or the optical system of the apparatus, it is possible to cancel the luminance unevenness if the photographing positions before and after the irradiation of the stimulation light are completely the same. However, if the position of the photographed image before and after the irradiation of the stimulation light has shifted, even if the positional shift is corrected, the luminance unevenness cannot be offset and the intrinsic signal cannot be acquired with high accuracy.

  In view of the above problems, an object of the present invention is to accurately detect an intrinsic signal of the retina.

  In order to solve the above problems, the present invention is characterized by having the following configuration.

(1)
An observation illumination optical system for illuminating the retina region of the eye to be examined;
An imaging optical system having an imaging device for receiving fundus images by receiving reflected light from the retinal region illuminated by the observation illumination optical system, and a stimulation light source, visible from the light source to the retinal region of the eye to be examined A stimulation light irradiation optical system that irradiates stimulation light by stimulating the retina, a storage unit that stores a fundus image acquired based on an imaging signal from the imaging device, and before the stimulation light irradiation stored in the storage unit In the retinal function measuring device, comprising: a change information acquisition unit that acquires change information of the fundus image by performing a calculation process by comparing the fundus image of the fundus image and the fundus image after irradiation with the stimulation light,
The change information acquisition means includes
Using at least two fundus images of a first fundus image captured before irradiation of the stimulation light with respect to the eye to be examined and a second fundus image whose imaging position is shifted with respect to the first fundus image. Misalignment information acquisition means for acquiring misalignment information of the second fundus image with respect to the first fundus image by image processing;
Based on the extracted image data at a predetermined position on the first fundus image, image data at a predetermined position on the second fundus image corresponding to the predetermined position, and the acquired positional deviation information, the first Brightness unevenness distribution acquisition means for obtaining brightness unevenness information on the predetermined position on the fundus image and obtaining a distribution of brightness unevenness on an axis in the positional deviation direction with the predetermined position as a reference;
Shading correction means for performing shading correction on the fundus images before and after the stimulation light irradiation based on the luminance unevenness distribution information obtained by the luminance unevenness distribution acquisition means,
The change information acquisition means acquires the change information of the fundus image by performing arithmetic processing in comparison with the fundus image before and after the stimulation light irradiation subjected to shading correction.
(2) In the retinal function measuring device of (1),
The positional deviation information acquisition means includes
The first fundus image is different from the first fundus image based on the fundus image stored in the storage unit before the stimulation light irradiation, and the second fundus is different from the first fundus image in the first direction. An image and a third fundus image in which the photographing position of the fundus image is different in a second direction different from the first direction with respect to the first fundus image, and the first and second fundus images And a positional shift amount of the first and third fundus images,
The luminance unevenness distribution acquisition means includes:
Luminance in the fundus image of the eye to be examined based on the positional deviation amounts of the first, second, and third fundus images, the first and second fundus images, and the positional deviation amounts of the first and third fundus images A retinal function measuring device characterized by obtaining uneven distribution.
(3) In the retinal function measuring device of (2), the image of the third fundus image obtained when the image data of the first fundus image is moved by Δx in the ₀ (x, y) and X (horizontal) directions. data 〇_Deruta _X (x, y), when the Y 〇_Deruta image data of the second fundus image obtained when moved to the (vertical) direction by [Delta] y _Y (x, y),
The luminance unevenness f (mΔx, nΔy) is

Or

It calculates | requires by performing arithmetic processing using.
(4) In the retinal function measuring device of (1), when the image data of the first fundus image is O ₀ (Δr, θΔ) and the shooting position is moved by (Δr, θΔ) with respect to the first fundus image. If the image data of the obtained second fundus image is OΔ (Δr, θΔ),
The luminance unevenness f (mΔr) is

It calculates | requires by performing arithmetic processing using.

  According to the present invention, an intrinsic signal of the retina can be detected with high accuracy.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an optical system of a retinal function measuring apparatus according to this embodiment.

  In FIG. 1, the optical system of the present apparatus receives an observation illumination optical system 10 that illuminates a retinal region of a subject's eye E, and reflected light from the retinal region illuminated by the observation illumination optical system 10 to receive a fundus image. An imaging optical system 20 having an imaging device for obtaining a light source, and a stimulation light irradiation optical system 30 for stimulating the retina by irradiating the retina region of the subject's eye with a stimulation light source and irradiating visible stimulation light from the light source And a fixation optical system 40 for fixing the subject's eyes.

  The observation illumination optical system 10 is an observation light source 11 such as a halogen lamp that emits infrared light, for example, an infrared filter 12 that transmits infrared light having a wavelength of 800 nm to 1000 nm, a condenser lens 13, and reflects infrared light to visible light. A dichroic mirror 14 having a characteristic of transmitting light, a ring slit 15 having a ring-shaped opening, a light projecting lens 16, a perforated mirror 17, and an objective lens 18. The ring slit 15 and the perforated mirror 17 are disposed at a position substantially conjugate with the pupil of the subject's eye E. The observation illumination light emitted from the observation light source 11 is converted into an infrared beam by the infrared filter 12, collected by the condenser lens 13, and then reflected by the dichroic mirror 14 to illuminate the ring slit 15. The light transmitted through the ring slit 15 reaches the perforated mirror 17 through the light projecting lens 16. The light reflected by the mirror portion of the perforated mirror 17 is once converged in the vicinity of the pupil of the eye E through the objective lens 18, and then diffused to continuously pass through a predetermined region of the retina of the eye E. Illuminate.

  The stimulation light irradiation optical system 30 includes a stimulation light source 31 that emits visible flash light for stimulating the retinal region, a condensing lens 33, and a ring slit 15 to an objective lens 18 that share an optical path with the observation illumination optical system 10. Including the optical system. The stimulation light source 31 can irradiate visible flash light in a single shot or in a flicker shape. Here, the visible flash light emitted from the stimulation light source 31 is applied to the retina region of the eye E through the condenser lens 33 and the dichroic mirror 14 through the same optical path as the observation illumination light.

  The imaging optical system 20 includes an objective lens 18, a focusing lens 21 movable in the optical axis direction, an imaging lens 22, and a two-dimensional imaging element 23 (for example, a two-dimensional CCD sensor). The focusing lens 21 moves in the optical axis direction by driving the drive mechanism 50. The reflected light from the retinal region illuminated by the observation light source 11 is once condensed in front of the perforated mirror 17 via the objective lens 18 and then passes through the opening of the perforated mirror 17. Then, the reflected light that has passed through the aperture (hole portion) of the perforated mirror 17 is condensed by the imaging lens 22 via the focusing lens 21 and then imaged on the two-dimensional image sensor 23. Note that pixels are two-dimensionally arranged in the horizontal (X) direction and the vertical (Y) direction on the imaging surface of the two-dimensional imaging element 23.

  The fixation optical system 40 includes a fixation light source 41 that emits visible light, a pinhole (or a fixation chart) 42, and a dichroic mirror 29 that reflects visible light and transmits infrared light. The optical path from 29 to the objective lens 18 is shared with the imaging optical system 20. The pinhole 42 is arranged at a position substantially conjugate with the observation point (imaging point) of the retina of the subject's eye E. The light emitted from the fixation light source 41 passes through the pinhole 42, is reflected by the dichroic mirror 29, and then passes through the optical path in the direction opposite to the reflected light from the retina (imaging lens 22 to objective lens 18). An image is formed on the retina of the examiner's eye.

  FIG. 2 is a block diagram showing a control system of the retinal function measuring apparatus in the present embodiment. A control unit 70 controls the entire apparatus. The control unit 70 includes an observation light source 11, a stimulus light source 31, a fixation light source 41, a focus drive mechanism 50, a storage unit 72, a control unit 74, and an image formation and retinal function of the subject's eye fundus. An image processing unit 71 and the like are connected. Reference numeral 75 denotes a monitor on which the fundus image formed by the image processing unit 71 is displayed. The storage unit 72 is for storing various information. The control unit 74 is for performing various input operations. In the above configuration, the storage unit 72 has a role of storing a fundus image acquired based on an imaging signal from the imaging element 23. Further, the storage unit 72 acquires fundus image change information by comparing the fundus image before stimulating light irradiation with the fundus image after stimulating light irradiation, acquires positional deviation information between fundus images, and acquires luminance unevenness distribution information. The arithmetic processing program for performing, etc. is stored. Then, the control unit 70 performs calculations based on the calculation processing program stored in the storage unit 72.

  The operation of the retinal function measuring device having the above configuration will be described. The examiner moves the apparatus with respect to the eye to be examined using a joystick (not shown), and the alignment is performed so that the fundus of the eye E is irradiated with illumination light and a desired fundus image is displayed on the monitor 75. I do. Then, the focus adjustment of the image is performed by driving the drive mechanism 50 using a focus adjustment switch provided in the control unit 74.

  When measuring the retinal function, a photographing button (not shown) of the control unit 74 is pressed in a state where a fundus image at a desired position is displayed on the monitor 75. When the photographing button is pressed, the control unit 70 acquires the fundus image received by the two-dimensional imaging device 23 using the photographing optical system 20, and stores the fundus image before the stimulation light emission in the storage unit 72 as a reference retinal image. At the same time, a visible flash light (single stimulation light or flicker-like stimulation light) is emitted toward the fundus of the eye E using a stimulation light source.

  When the irradiation of the stimulation light to the retinal region is completed, the control unit 70 further acquires the fundus image after the flash light irradiation operation is completed using the photographing optical system in the same manner as described above, and the image is stored in the storage unit 72. Remember me. Not only one fundus image is taken after the flash light irradiation, but the fundus image may be stored continuously or over time after the flash light irradiation so that a change in the retinal function can be seen. In this case, data used for analysis may be extracted from a plurality of stored images.

  Here, the principle for measuring the retinal function will be briefly described. That is, when stimulation light such as flash light is irradiated to the fundus of the subject's eye E and the cells constituting the retina are stimulated, the neuronal activity changes with the stimulation, and this neural activity occurs. The intensity (reflectance) of the reflected light at the part changes. For this reason, by reading the change in the brightness of the fundus image (the reflectance of the retinal area with respect to the observation light) before and after the flash light irradiation, an intrinsic signal change resulting from the change in the activity of the nerve cell can be obtained. . Therefore, the retinal function of the subject's eye can be measured.

  For example, when measuring the retinal function based on the fundus images before and after the flash light irradiation, the control unit 70 first stores the fundus image before the flash light irradiation (reference fundus) stored in the storage unit 72 when measuring the retinal function. Image) and the fundus image after flash light irradiation are aligned. For alignment, feature points (eg, blood vessel shape, nipple, macula, etc.) are extracted by image processing from the fundus image before irradiation (reference fundus image) and the fundus image after irradiation, and both images are moved relatively. The position where the feature points of both images most closely match is obtained by arithmetic processing, such as enlarging or reducing. The alignment method is not limited to this, and a well-known image processing technique may be used.

  After aligning the fundus image before and after such flash light irradiation, the control unit 70 obtains, for each pixel, a change in the brightness of the fundus image after irradiation with respect to the brightness of the fundus image before irradiation. The change in brightness can be obtained by obtaining a difference, a ratio, or the like. The image processing unit 71 displays the brightness change information obtained by the control unit 70 on the monitor 75 in association with each pixel. As brightness change information, a method of displaying brightness change information as an image according to shading and height, numerical information of differences and ratios, and numerical processing of this numerical information by a predetermined analysis program for evaluating retinal function Can be represented by the information etc.

  In the retinal function measurement as described above, in the present embodiment, luminance unevenness information of the fundus image acquired by the present apparatus is detected, and the function measurement acquired before and after the stimulation light irradiation using the detected luminance unevenness information. Shading correction is performed on the fundus image.

Expression 1 is an expression representing image data O (x, y) in consideration of luminance unevenness in the present apparatus. Here, T ₀ is a theoretical value of the sensitivity of the image sensor and varies depending on the photoelectric conversion efficiency t (x, y). L _S0 is a theoretical value of the light source output, and varies depending on the light emission efficiency l _s (x, y). Note that in the case of an ideal device in which uneven brightness does not occur, image data O _R (x, y) is as follows when a fundus image is captured. Here, the ideal device is the photoelectric conversion efficiency t (x, y), the light emission efficiency l _s (x, y), the light reception efficiency l ₂ (x, y), and the light projection efficiency l ₁ (x, y). ) Represents a state of 1.

Expression 3 is obtained by extracting an element f (x, y) that is generated as luminance unevenness of an image from Expression 1.

If 0 <f (x, y) ≦ 1, from Equations 1, 2, and 3

That is, luminance unevenness is corrected by dividing each pixel of the image obtained by the above system by f (x, y). In the following description, it is assumed that the intersection point between the imaging optical axis of the imaging optical system 20 and the imaging surface of the imaging element 23 is the origin, and f (0, 0) = 1. That is, since it is only necessary to correct relatively, it is considered that O _R (0,0) = O (0,0).

  Note that the luminance unevenness distribution f (x, y) is detected before the stimulation light irradiation. That is, the control unit 70 stores the fundus image captured by the image sensor 23 in the storage unit 72 as needed before the stimulation light irradiation. Then, the control unit 70 first extracts one correction reference image from the fundus image for each frame stored in the storage unit 72. In the following description, the correction reference image is described as the first fundus image. FIG. 3A shows an example of a reference image for correction.

  Next, from the fundus image for each frame stored in the storage unit 72, the control unit 70 sets one fundus image whose shooting position is different from the above-described correction reference image in the vertical direction as a second fundus image. Then, one fundus image having a different shooting position in the left-right direction with respect to the reference image for correction is extracted as a third fundus image. In this case, feature points (for example, blood vessel shape, nipple, macula, etc.) between each fundus image and the first fundus image stored in the storage unit 72 are extracted, and a relative positional shift amount between the fundus images is captured. What is necessary is just to extract the fundus image which detects in the pixel unit of the element 23 and has a desired positional shift amount with respect to the first fundus image as the second fundus image and the third fundus image. That is, image processing is performed using at least two fundus images of the first fundus image captured before the irradiation of the stimulation light and the second fundus image whose imaging position is shifted with respect to the first fundus image. The positional deviation information of the second fundus image with respect to the first fundus image is acquired, and the fundus image having the desired positional deviation amount with respect to the first fundus image is extracted as the second fundus image and the third fundus image. .

  FIG. 3B is an example of the second fundus image, and FIG. 3C is an example of the third fundus image. In this case, by automatically or manually moving the pinhole 42 in the vertical (left / right) direction to move the fixation position of the eye to be examined, the photographing position of the fundus image on the imaging surface of the imaging element 23 is set to Y (X). A second fundus image (third fundus image) may be obtained from the fundus image captured in a state shifted in the direction. In addition, since the photographing position of the fundus image on the imaging surface of the imaging device 23 is shifted due to fixation micromotion of the subject's eye that occurs without the subject's awareness, the fundus image stored in the storage unit 72 with time can be used by using this. A second fundus image (third fundus image) may be obtained. Moreover, you may make it move the whole apparatus to a predetermined direction using a joystick.

Here, the image data of the first fundus image is O ₀ (x, y), and the image data of the third fundus image obtained by moving Δx in the X direction is ΔΔ _X (x, y), Y direction. If the image data of the second fundus image obtained when moving to Δy is ΔΔ _Y (x, y),
First, a discrete luminance distribution on the Y axis is obtained by the following equation. In the following formula, m and n are positive integers. Here, when Δx> 0 and Δy> 0, the luminance unevenness when x ≧ 0 and y ≧ 0 is

Here, when obtaining f (0, Δy) (n = 1), the luminance value ◯ Δ _Y (0, Δy) at the pixel position (0, Δy) in the second fundus image is the pixel position in the first fundus image. Divided by the luminance value 0 ₀ (0, 0) at (0, 0) (see FIG. 4A). In this case, the measurement position on the fundus corresponding to ◯ Δ _Y (0, Δy) is obtained by adding the positional deviation amount Δy to the pixel position (0, 0), and corresponds to ◯ ₀ (0, 0). It coincides with the measurement position on the fundus. Therefore, the reflectance R from the eye fundus is considered to be the same value. Therefore, by comparing the luminance values at the same measurement site between fundus images with different imaging positions, the luminance of the pixel position (0, Δy) with respect to the reference position (0, 0) is not affected by the reflectance. Change (intensity unevenness) can be detected.

Further, when obtaining f (0, 2Δy) (n = 2), the luminance value ◯ Δ _Y (0, 2Δy) at the pixel position (0, 2Δy) in the second fundus image to compare the luminance values at the same measurement site. ) Is divided by the luminance value 0 ₀ (0, Δy) at the pixel position (0, Δy) in the first fundus image, and f (0, Δy) is added to the value after the division (see FIG. 4B). ). That is, the control unit 70 reads the image data at the predetermined position on the extracted first fundus image, the image data at the predetermined position on the second fundus image corresponding to the predetermined position, and the acquired positional deviation information. The luminance unevenness information on the predetermined position on the first fundus image is obtained based on the above, and the distribution of the luminance unevenness on the axis in the misregistration direction with the predetermined position (0, 0) as a reference is obtained by the arithmetic processing.

Further, when obtaining f (0, 3Δy) (n = 3), the luminance value ◯ Δ _Y (0, 3Δy) at the pixel position (0, 3Δy) in the second fundus image is compared to compare the luminance values at the same measurement site. ) Is divided by the luminance value 0 ₀ ( _0, 2Δy) at the pixel position ( _0, 2Δy) in the first fundus image, and f (0, 2Δy) is added to the value after the division.

As described above, the integration process is repeated in order to obtain the luminance unevenness at each point of f (0, nΔy). FIG. 5 is a diagram illustrating a luminance unevenness distribution at each point of f (0, nΔy). Then, an approximate curve FΔ _Y (0, y) is obtained from the data. More specifically, the luminance unevenness information between pixels for which data is obtained corresponds to the pixel position on the imaging surface of the image sensor 23, and each pixel is subjected to curve interpolation to approximate the approximate curve FΔ _Y (0, y) can be determined. Thereby, the luminance distribution on x = 0 can be obtained.

Similarly, the image data 〇 ₀ of the first fundus image (x, y) using the image data 〇_Deruta _X (x, y) of the third fundus image, consider the luminance distribution in the X direction for the upper y = 0 And the following.

Here, when generalizing Equation 6 obtained as described above with reference to the Y axis,

Then, when Expression 5 is substituted into Expression 7, Expression 8 is obtained.

Then, the approximate curve FΔ _Y Δ _X (x, y) can be obtained from the discrete luminance distribution obtained from Expression 8.

  Similarly, considering the luminance unevenness distribution where x ≧ 0 and y ≦ 0,

Here, when obtaining f (0, −Δy) (n = 1), the luminance value 0 ₀ (0, −Δy) at the pixel position (0, −Δy) in the first fundus image is determined in the second fundus image. Divided by the luminance value ◯ Δ _Y (0, 0) at the pixel position (0, 0). In this case, the measurement position on the fundus corresponding to ◯ Δ _Y (0,0) is obtained by adding the positional deviation amount Δy to the pixel position (0, −Δy), and ◯ ₀ (0, −Δy). It corresponds to the corresponding measurement position on the fundus (see FIG. 6A). Therefore, the reflectance R from the eye fundus is considered to be the same value. Therefore, by comparing the luminance values at the same measurement site between fundus images with different imaging positions, the pixel position (0, −Δy) with respect to the reference position (0, 0) is not affected by the reflectance. Changes in brightness (brightness unevenness) can be detected.

Further, when obtaining f (0, −2Δy) (n = 2), the luminance value O ₀ (0, 0, ₀ ) at the pixel position (0, −2Δy) in the first fundus image is compared with the luminance value at the same measurement site. −2Δy) is divided by the luminance value ◯ Δ _Y (0, −Δy) at the pixel position (0, −Δy) in the second fundus image, and f (0, −Δy) is added to the value after the division ( (Refer FIG.6 (b)). That is, the control unit 70 reads the image data at the predetermined position on the extracted first fundus image, the image data at the predetermined position on the second fundus image corresponding to the predetermined position, and the acquired positional deviation information. The luminance unevenness information on the predetermined position on the first fundus image is obtained based on the above, and the distribution of the luminance unevenness on the axis in the misregistration direction with the predetermined position (0, 0) as a reference is obtained by the arithmetic processing.

  Similarly, considering the luminance unevenness distribution when x ≦ 0 and y ≧ 0,

Similarly, when considering the luminance unevenness distribution in x ≦ 0 and y ≦ 0,

Then, it is possible to obtain an approximate of discrete luminance distribution obtained from Equation 9 Equation 11 curves _{FΔ Y Δ X (x, y} ). Thereby, luminance unevenness distribution in all quadrants is obtained.

When the luminance unevenness distribution FΔ _Y Δ _X (x, y) in all quadrants is obtained as described above, the actual fundus image data O (x, y) stored in the storage unit 72 is used as the luminance unevenness distribution FΔ. By dividing by _Y Δ _X (x, y), it is possible to obtain a fundus image in which shading correction is performed and luminance unevenness due to an intermediate translucent body or the like is corrected.

  Therefore, the control unit 70 performs shading correction on the image data of the fundus image used for the retinal function and obtained before the stimulation light irradiation, using the luminance unevenness information F (x, y), and stores the corrected image data in the storage unit. 72 is stored. Further, shading correction is performed on the image data of the fundus image used for the retinal function and obtained after the stimulation light irradiation, using the luminance unevenness information F (x, y), and the corrected image data is stored in the storage unit 72. Then, the change information of the retinal image is acquired by comparing the fundus images before and after the stimulation light irradiation each subjected to shading correction and performing arithmetic processing.

  With the configuration as described above, since the luminance unevenness distribution due to the subject eye transparent body can be detected, it is possible to correct the luminance unevenness due to the subject eye transparent body in addition to the luminance unevenness due to the optical system. A few fundus images for measurement can be obtained. As a result, the retinal function of the eye to be examined can be accurately obtained.

  In the above description, the luminance unevenness distribution f (x, y) can be obtained without using the approximation process by setting the positional deviation amounts Δx and Δy for one pixel of the image sensor 23. In this case, the luminance unevenness when x> 0 and y> 0 is as follows. In addition, about the formula regarding another quadrant, since it can obtain | require with the same method, it abbreviate | omits.

In the above description, f (0, nΔy) is obtained first. However, the present invention is not limited to this, and f (mΔx, 0) may be obtained first. In this case, the luminance unevenness when x> 0 and y> 0 is as follows. In addition, about the formula regarding another quadrant, since it can obtain | require with the same method, it abbreviate | omits.

In the above description, the intersection position between the imaging optical axis of the imaging optical system 20 and the imaging surface of the imaging device 23 is set as the origin, and f (0, 0) = 1. The position is not limited to this as long as the fundus image is received on the imaging surface. For example, a point A located at the lower left of the imaging surface as shown in FIG. 7 may be set as the origin (0, 0). In this way, if it is within rectangle B,

Etc., it is possible to obtain the luminance unevenness distribution, so that it is not necessary to use the equation for each quadrant as described above.

  In the above description, the second fundus image in which the photographing position of the fundus image differs in the vertical direction with respect to the first fundus image, and the photographing position of the fundus image in the horizontal direction with respect to the first fundus image. Although the configuration is such that different third fundus images are extracted, the present invention is not limited to this, and the second fundus image shooting position differs in a predetermined direction (first direction) with respect to the first fundus image. The luminance unevenness distribution is calculated in the same manner by extracting the fundus image and the third fundus image having a different shooting position in the second direction different from the first direction with respect to the first fundus image. Is possible. In this case, the luminance unevenness distribution can be obtained based on the positional deviation information in the first direction and the positional deviation information in the second direction.

  If it is assumed that the luminance unevenness distribution is symmetric with respect to the imaging optical axis L1, it is also possible to obtain luminance unevenness information from two fundus images. In the following description, polar coordinates are used. In this case, the second fundus image is acquired in a state where the shooting position is shifted by (Δr, θΔ) with respect to the first fundus image (reference image for correction).

In this case, assuming that the image data in the first image is O ₀ (Δr, θΔ) and the image data in the second image is OΔ (Δr, θΔ), as described above, the luminance unevenness distribution is on the optical axis. On the other hand, in the case of symmetry, since it does not depend on the declination, the distribution can be obtained discretely by the following equation (14).

Then, the luminance distribution of each pixel can be obtained by obtaining an approximate curve from the data obtained by Expression 14. By converting the obtained result into XY coordinates by a well-known method, luminance unevenness information f (x, y) in the XY direction can be detected.

It is a schematic block diagram which shows the optical system of the retinal function measuring apparatus which concerns on this embodiment. It is the block diagram which showed the control system of the retinal function measuring device in this embodiment. It is a figure explaining a 1st, 2nd, 3rd fundus image. It is a figure explaining the detection method of the brightness nonuniformity which concerns on this embodiment. It is a figure which shows the brightness | luminance nonuniformity distribution in each point of f (0, n (DELTA) y). It is a figure explaining the detection method of the brightness nonuniformity which concerns on this embodiment. It is a figure which shows the example at the time of changing an origin position.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Observation illumination optical system 10 Observation illumination optical system 20 Imaging optical system 23 Imaging element 30 Stimulation light irradiation optical system 31 Stimulation light source 70 Control part 72 Storage part

Claims (4)

An observation illumination optical system for illuminating the retina region of the eye to be examined;
An imaging optical system having an imaging device for receiving fundus images by receiving reflected light from the retinal region illuminated by the observation illumination optical system, and a stimulation light source, visible from the light source to the retinal region of the eye to be examined A stimulation light irradiation optical system that irradiates stimulation light by stimulating the retina, a storage unit that stores a fundus image acquired based on an imaging signal from the imaging device, and before the stimulation light irradiation stored in the storage unit In the retinal function measuring device, comprising: a change information acquisition unit that acquires change information of the fundus image by performing a calculation process by comparing the fundus image of the fundus image and the fundus image after irradiation with the stimulation light,
The change information acquisition means includes
Using at least two fundus images of a first fundus image captured before irradiation of the stimulation light with respect to the eye to be examined and a second fundus image whose imaging position is shifted with respect to the first fundus image. Misalignment information acquisition means for acquiring misalignment information of the second fundus image with respect to the first fundus image by image processing;
Based on the extracted image data at a predetermined position on the first fundus image, image data at a predetermined position on the second fundus image corresponding to the predetermined position, and the acquired positional deviation information, the first Brightness unevenness distribution acquisition means for obtaining brightness unevenness information on the predetermined position on the fundus image and obtaining a distribution of brightness unevenness on an axis in the positional deviation direction with the predetermined position as a reference;
Shading correction means for performing shading correction on the fundus images before and after the stimulation light irradiation based on the luminance unevenness distribution information obtained by the luminance unevenness distribution acquisition means,
And the change information acquisition means acquires change information of the fundus image by performing arithmetic processing in comparison with the fundus image before and after the stimulation light irradiation subjected to the shading correction. . In the retinal function measuring device according to claim 1,
The positional deviation information acquisition means includes
The first fundus image is different from the first fundus image based on the fundus image stored in the storage unit before the stimulation light irradiation, and the second fundus is different from the first fundus image in the first direction. An image and a third fundus image in which the photographing position of the fundus image is different in a second direction different from the first direction with respect to the first fundus image, and the first and second fundus images And a positional shift amount of the first and third fundus images,
The luminance unevenness distribution acquisition means includes:
Luminance in the fundus image of the eye to be examined based on the positional deviation amounts of the first, second, and third fundus images, the first and second fundus images, and the positional deviation amounts of the first and third fundus images A retinal function measuring device characterized by obtaining uneven distribution. 3. The retinal function measuring device according to claim 2, wherein the image data of the first fundus image is ₀ (x, y), and the image data of the third fundus image obtained by moving Δx in the X (horizontal) direction is 0. Δ _X (x, y), when the Y 〇_Deruta image data of the second fundus image obtained when moved to the (vertical) direction by [delta] y _Y (x, y),
The luminance unevenness f (mΔx, nΔy) is
Or
A retinal function measuring device characterized in that it is obtained by performing arithmetic processing using a synthesizer. In the retinal function measuring device according to claim 1, obtained when the image data of the first fundus image is O ₀ (Δr, θΔ) and the photographing position is moved by (Δr, θΔ) with respect to the first fundus image. If the image data of the second fundus image is OΔ (Δr, θΔ),
The luminance unevenness f (mΔr) is
A retinal function measuring device characterized in that it is obtained by performing arithmetic processing using a synthesizer.