JP2011189202A - Opthalmologic imaging apparatus and opthalmologic imaging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ophthalmologic imaging apparatus and an ophthalmologic imaging method to acquire a fundus image having an image quality sufficient for diagnosis. <P>SOLUTION: First, an image of a first area having intensity not less than predetermined intensity and an image of a second area other than the first area are extracted from a first fundus image photographed with a first light quantity. Then, an image corresponding to the first area in a second fundus image photographed with a second light quantity based on the light quantity of the first area is extracted. Further, an image of an area corresponding to the second area from a third fundus image photographed with a third light quantity based on the light quantity of the second area is extracted. The extracted images are combined. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ophthalmic imaging apparatus and an ophthalmic imaging method for imaging the fundus of a subject's eye.

Japanese Patent Application Laid-Open No. 2004-133867 discloses a fundus camera that can appropriately capture bright and dark portions in the fundus imaging field of view and that can capture images even when exposure conditions are unknown. In the case of fluorescence imaging of the fundus oculi, the fluorescence intensity is significantly different between a thick blood vessel and a thin blood vessel.
Further, Patent Document 2 discloses a fundus camera capable of illuminating only the nipple portion with visible light in order to adjust the focus within the nipple without reducing the pupil of the subject's eye.

JP 2000-107133 A JP 2003-10134 A

However, Patent Document 1 does not disclose that the amount of light emission is adjusted depending on the imaging region when the imaging light source emits strong or weak light.
Further, in Patent Document 2, since the fundus image is not focused on both the nipple region and the region other than the nipple region, the image quality is insufficient as a diagnostic image.

  Here, a case is considered in which when the fundus is imaged, the nipple region and the macular region are imaged at once as a single fundus image. At this time, if the nipple portion is properly exposed, the macular portion is blackened. On the other hand, if the macular region is properly exposed, the nipple region will be whitened. This is because the nipple region is the brightest and the macular region is the darkest in the fundus imaging field of view, and the dynamic range of the image sensor is not sufficient to capture these simultaneously.

  Also, consider a case in which a papillary region is imaged with visible light, a macular region is imaged with infrared light, and a fundus image is obtained by simply synthesizing each other's images. At this time, since the two images are not images taken with the same light amount, the image quality is insufficient as a diagnostic image.

An ophthalmologic imaging apparatus according to the present invention includes:
An ophthalmic imaging apparatus for imaging the fundus of a subject's eye,
A first region image that is a predetermined intensity or higher and a second region image other than the first region are extracted from a first fundus image captured with the first light amount, respectively. Extraction means;
A second extraction means for extracting an image of a region corresponding to the first region out of a second fundus image captured with a second light amount based on the light amount of the first region;
A third extraction means for extracting an image of a region corresponding to the second region out of a third fundus image captured with a third light amount based on the light amount of the second region;
Image combining means for combining the images extracted by the second and third extracting means;
It is characterized by having.

Further, an ophthalmic imaging method according to the present invention includes:
An ophthalmic imaging method for imaging the fundus of a subject's eye,
A first region image that is a predetermined intensity or higher and a second region image other than the first region are extracted from a first fundus image captured with the first light amount, respectively. An extraction process;
A second extraction step of extracting an image of a region corresponding to the first region out of a second fundus image captured with a second light amount based on the light amount of the first region;
A third extraction step of extracting an image of a region corresponding to the second region out of a third fundus image captured with a third light amount based on the light amount of the second region;
An image synthesis step of synthesizing the images extracted by the second and third extraction steps;
It is characterized by including.

  By using the ophthalmologic imaging apparatus and the ophthalmologic imaging method according to the present invention, it is possible to photograph areas with different brightness of the fundus of the eye to be examined (mainly areas including the optic nerve head and other areas including the macula) with an appropriate amount of light. it can. Then, by combining these images, it is possible to acquire a fundus image having a sufficient image quality as a diagnostic image.

It is a block diagram of the fundus camera of the first embodiment. It is an enlarged side view of a focus index projection means. It is an enlarged front view of a focus index projection means. It is explanatory drawing of a focus parameter | index image on a fundus | bary with a mode that a focus parameter | index light beam reaches the fundus of the eye to be examined, and a focus index beam. It is explanatory drawing of the display screen of the display part of 1st Embodiment. It is an operation | movement flowchart figure of the calculating part of 1st Embodiment. It is explanatory drawing of the detection method and the synthetic | combination method of an image of the nipple part N of the fundus of 1st Embodiment. It is a histogram figure of a fundus image data. It is a block diagram of the fundus camera of the second embodiment. It is an operation | movement flowchart figure of the calculating part of 2nd Embodiment. It is explanatory drawing of the synthetic | combination method of the image of the fundus of 2nd Embodiment.

  Hereinafter, embodiments of an ophthalmic imaging apparatus and an ophthalmic imaging apparatus according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a configuration diagram of a fundus camera of the present embodiment. On the optical path O1 of the illumination optical system from the reflector 1 to the objective lens 2 positioned facing the eye E, an observation light source 3 composed of a halogen lamp, a condenser lens 4, a photographing light source 5 composed of a xenon tube, a mirror 6 are arranged. In the reflection direction of the mirror 6, a diaphragm 7 having a ring-shaped opening, a relay lens 8, a focus index projection means 9, a relay lens 10, and a perforated mirror 11 are sequentially arranged.

  On the optical path O2 of the observation photographing optical system behind the perforated mirror 11, the focusing lens 12, the photographing lens 13, the three-color wavelength resolving means 14a, and the imaging means 14 incorporating the imaging element 14b are sequentially arranged. . Further, the focus index projection means 9 and the focusing lens 12 are interlocked by a focus link mechanism 15.

  An output of the imaging means 14 is connected to a control unit 22 that controls a photographing operation and the like via an image signal processing unit 21, and an output of the image signal processing unit 21 is connected to a display unit 23 that displays an image. The output of the control unit 22 is connected to the observation light source 3, the imaging light source 5, and the focus index projection means 9 via the observation light source driving circuit 24, the imaging light source driving circuit 25, and the focus index control circuit 26, respectively. Yes. Further, an input unit 27 and a recording unit 28 are connected to the control unit 22.

  FIG. 2 is an enlarged side view of the focus index projection means 9, and FIG. 3 is an enlarged front view. The focus index projection means 9 includes a focus split prism having prism portions 9a, 9b and 9c, a focus index 9d having a rectangular opening, and a focus index light source 9e. The prism portions 9b, 9c have prism surfaces with symmetrical angles, and the focus index light source 9e is composed of an LED having a center wavelength for visible light.

  The focus index projection means 9 moves in the direction A shown in FIG. 1 in conjunction with the focusing lens 12 by the focus link mechanism 15, and the focus index 9 d of the focus index projection means 9 and the image sensor 14 b of the imaging means 14 are optical. It is made to become a conjugate relation. Further, the focus index projection means 9 rotates around the axis 9f during still image shooting, moves in the direction B shown in FIG. 1, and retracts from the optical path O1 of the illumination optical system.

  The light beam emitted from the observation light source 3 during fundus observation passes through the condenser lens 4, the mirror 6, the diaphragm 7, the relay lens 8, the focus index projection unit 9, and the relay lens 10, and is reflected around the perforated mirror 11. Further, the fundus Er is illuminated through the cornea Ec and the pupil Ep of the eye E through the objective lens 2. The control unit 22 controls the focus index control circuit 26 to turn on the focus index light source 9e of the focus index projection unit 9.

  As shown in FIG. 2, the light beam from the focus index light source 9e is deflected in the optical path O1 direction by the prism portion 9a of the focus split prism, reaches the prism portions 9b and 9c, and is branched in two directions. Further, the light beam passes through the rectangular opening of the focus index 9d, and becomes two focus index light beams Lb and Lc that are symmetrical with respect to the optical path O1, respectively. Reach E fundus Er.

  FIGS. 4A to 4C are explanatory diagrams showing how the focus index light beams Lb and Lc reach the fundus Er and the focus index images Fb and Fc on the fundus Er by the focus index light beams Lb and Lc. FIG. 4A shows a case where the fundus Er and the focus index 9d are in an optically conjugate positional relationship. Since the fundus oculi Er and the focus index 9d are optically conjugate, the focus index light beams Lb and Lc separated into two become the images Fb and Fc of the rectangular openings of the focus index 9d on the fundus Er and are aligned.

  FIG. 4B is an explanatory diagram showing a case in which the eye E is more nearsighted than FIG. Since the fundus Er and the focus index 9d are not optically conjugate, the focus index light beams Lb and Lc separated into two become the images Fb and Fc of the rectangular openings of the focus index 9d on the fundus Er and The image Fb is shifted upward and the image Fc is shifted downward.

  FIG. 4C is an explanatory view showing a case where the eye E is far-sighted than FIG. 4A. Since the fundus Er and the focus index 9d are not optically conjugate, the focus index light beams Lb and Lc separated into two become index images Fb and Fc of the rectangular openings of the focus index 9d on the fundus Er and The image Fb is shifted downward and the image Fc is shifted upward.

  The illuminated fundus image Er ′ and the index images Fb and Fc pass through the focusing lens 12 and the photographing lens 13 through the pupil Ep, the cornea Ec, the objective lens 2 and the hole of the perforated mirror 11, and the imaging unit 14 The light is received by the image sensor 14b through the three-color wavelength resolving means 14a and imaged.

  In the image sensor 14b, photoelectric conversion is performed on the fundus oculi image Er ′ and the focus index images Fb and Fc by the reflection image of the fundus oculi Er, and the image signal processing unit 21 reads out, amplifies, and A / D conversion is performed, and digital image data is generated. The generated digital image data is input to the control unit 22 and simultaneously displayed on the display unit 23 as a moving image as shown in FIG.

  The operator observes the index images Fb and Fc of the rectangular opening of the focus index 9d displayed on the display unit 23, and operates the focus knobs so that the index images Fb and Fc are aligned. That is, when the fundus Er and the focus index 9d are optically conjugate, the focus link mechanism 15 (the first moving means for moving the focus index projecting means and the second moving means for moving the focusing means are interlocked. The focus index 9d of the focus index projection means 9 and the image sensor 14b are optically conjugate. Therefore, by moving from the first conjugate position to the second conjugate position, the fundus Er and the image sensor 14b are optically conjugate, and the fundus Er can be focused.

  FIG. 6 shows a flowchart of the operation during fundus photography. While observing the image shown in FIG. 5 displayed on the display unit 23, the operator performs alignment and focusing, and when the alignment and focus are achieved, the photographing switch (input means for inputting the photographing signal) of the input unit 27 is obtained. At this time, the focus index projection means can be retracted out of the optical path in accordance with the photographing signal. (Thus, the first fundus image can be taken with the first light quantity.) The control unit 22 detects this in step S1, controls the focus index control circuit 26 in step S2, and projects the focus index. The means 9 is driven in the B direction and retracted out of the optical path O1. In step S3, the optic disc portion N (first region) of the fundus Er is extracted (executed by the first extracting means).

  In general, the nipple portion N is the brightest portion in the fundus image. Therefore, as shown in FIG. 7A, the maximum value is selected from digital image data obtained by the fundus image of the fundus Er obtained by the imaging means 14 and input to the control unit 22 through the image signal processing unit 21. For example, 70% of the maximum value Dmax (predetermined intensity) is set as the reference value (executed by the setting means). Then, binarization processing is performed using this reference value. FIG. 7B shows the result. Of the fundus image data Dij, those having Dmax · 0.7 or more (predetermined intensity or more) are the maximum values with 8 bits (0 to 255) of image data. 255, and the portion less than Dmax · 0.7 is 0 corresponding to a black signal. In this way, the nipple portion N is extracted.

  In step S4, the observation light source drive circuit 24 causes the nipple portion N in the image of FIG. 7B extracted in step S3 to have an appropriate light amount (second light amount based on the light amount of the first region). The light quantity of the observation light source 3 (the light source that generates the first and second light quantities) is changed by the observation light quantity control. In this embodiment, the case where the average value Dav = 120 of the image data Dij of the nipple portion N is set as an appropriate light amount. In step S 5, the image data of FIG. 7C (second fundus image taken with the second light quantity) in which the nipple portion N is properly exposed is recorded and stored in the recording unit 28.

  In step S6, a portion (second region other than the first region) excluding the nipple portion N of the fundus Er extracted in step S3 is extracted (executed by the first extracting means). In step S7, the imaging light source 5 (a light source that generates light of the third light quantity) is set so that parts other than the nipple part N have appropriate exposure (third light quantity based on the light quantity of the second region). The amount of luminescence is calculated. In step S8, the observation light source drive circuit 24 is controlled to turn off the observation light source 3. In step S9, it is confirmed whether or not the image pickup unit 14 is in a recordable state. If the image pickup unit 14 is in a recordable state, the process proceeds to step S10. The imaging light source 5 is caused to emit light in synchronization with the imaging means 14.

  In step S <b> 11, an image of the fundus Er where a portion other than the nipple portion N of the fundus Er is appropriately exposed is recorded (a third fundus image taken with a third light amount) and stored in the recording unit 28. FIG. 7D shows image data obtained at this time. In step S12, the nipple region N is extracted from the image of FIG. 7C recorded in step S5 (the image of the region corresponding to the first region is extracted from the second fundus image), and FIG. (E) is the image data obtained at this time (executed by the second extracting means). In step S13, a part other than the nipple part N is extracted from the image of FIG. 7D recorded in step S11 (an image of a region corresponding to the second region is extracted from the third fundus image). It is set as the image of FIG.7 (f) (executed by the 3rd extraction means).

  The observation light source 3 composed of a halogen lamp generally has a color temperature of 3000 to 3400K, and the photographing light source 5 composed of a xenon tube generally has a color temperature of 5500 to 6000K. As described above, since the images recorded in steps S5 and S11 have different color temperatures of the light sources, if the images are combined as they are in step S15, an unnatural image is obtained. Accordingly, in step S14, the two images are corrected so that the image shown in FIG. 7E generated in step S12 is equivalent in color temperature to the image shown in FIG. I do.

  In step S15, the images whose color temperatures have been corrected in step S14 are combined to generate one fundus image. FIG. 7G shows the image data obtained at this time. The fundus image generated in this way is properly exposed in both the nipple region N and the region other than the nipple region N including the macular region M.

  FIG. 8 is a histogram of image data according to another embodiment of the image composition in step S15. 8A is a histogram of the image data obtained by extracting the fundus nipple portion N shown in FIG. 7E, and FIG. 8B is the image data obtained by extracting portions other than the nipple portion N generated in step 13. This is a histogram. The image data is 8 bits (0 to 255), white is the maximum value 255, and black is the minimum value 0. When image composition is performed in step S15, the image data may be expanded to 16 bits, and image composition may be performed by assigning parts other than the nipple part N to the lower 8 bits and nipple part N to the upper 8 bits. FIG. 8C is a histogram of the result of image synthesis in this way. Further, image synthesis may be performed such that blood vessels other than the nipple region N and blood vessels of the nipple region N have the same luminance.

  In the present embodiment, after image recording of the nipple region N using the observation light source 3 in steps S3 to S5, image recording of a region other than the nipple region N using the imaging light source 5 in steps S6 to S11. It is carried out. However, the order may be changed, and after executing step S2, steps S6 to S11 may be executed, then steps S3 to S5 may be executed, and the transition to step S12 may be executed sequentially.

(Second Embodiment)
FIG. 9 shows a configuration diagram of the fundus camera of the present embodiment. 9, the focus index projection unit 9, the relay lens 10, and the focus link mechanism 15 are removed from FIG. The output of the control unit 22 is connected to the focusing lens 12 via the drive circuit 31.

  FIG. 10 is a flowchart of the operation of the control unit 22 during fundus photographing. In FIG. 10, step S2 is deleted from FIG. 6, step S20 for performing focusing control is added between steps S4 and S5, and step S21 for moving the focusing lens is added between steps S7 and S8. Yes.

  Steps S1, S3, and S4 are the same as those in the first embodiment. In step S20, the driving circuit 31 is controlled to move the focusing lens 12 in the direction A in FIG. From the fundus image formed on the image sensor 14b input to the control unit 22 via the image signal processing unit 21, the nipple portion N is extracted in step S4, and the image where the contrast of the image of the nipple portion N is the highest is focused. Position detection is performed, and the focusing lens 12 is stopped at the in-focus position. In this way, the image of the fundus oculi Er recorded in step S5 is a fundus image that is exposed and focused on the nipple portion N as shown in FIG.

  Steps S5, S6, and S7 are the same as in the first embodiment. In step S21, the drive circuit 31 is controlled to move the focusing lens 12 by a predetermined amount. In the fundus image formed on the image sensor 14b input to the control unit 22 through the image signal processing unit 21, a part other than the nipple part N is extracted in step S6, and the contrast of the image of the part other than the nipple part N is extracted. The focusing lens 12 is stopped at a position where becomes the highest. That is, the focusing lens 12 is moved by a predetermined amount that is the difference between the focus position difference of the nipple part N and the focus position of the part excluding the nipple part N. In this way, the image of the fundus oculi Er recorded in step S11 is a fundus image that is exposed and focused on a portion other than the nipple portion N as shown in FIG.

  Steps S8 to S15 are the same as in the first embodiment. The image shown in FIG. 11C generated in step S13 and the image shown in FIG. 11D generated in step S14 are combined in step S15 to obtain one fundus image. As shown in FIG. 11 (e), this image is a fundus image that is exposed and focused on both the nipple portion N and the portion other than the nipple portion N including the macular portion M.

(Other embodiments)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

DESCRIPTION OF SYMBOLS 3 Light source for observation 4 Light source for imaging | photography 9 Focus index projection means 9e Focus index light source 9d Focus index 14 Imaging means 14a Three-color wavelength decomposition means 14b Imaging element 21 Image signal processing part 22 Control part 23 Display part 27 Input part 28 Recording part Fb , Fc Focus index image M Macular site N Nipple site

Claims (13)

An ophthalmic imaging apparatus for imaging the fundus of a subject's eye,
A first region image that is a predetermined intensity or higher and a second region image other than the first region are extracted from a first fundus image captured with the first light amount, respectively. Extraction means;
A second extraction means for extracting an image of a region corresponding to the first region out of a second fundus image captured with a second light amount based on the light amount of the first region;
A third extraction means for extracting an image of a region corresponding to the second region out of a third fundus image captured with a third light amount based on the light amount of the second region;
Image combining means for combining the images extracted by the second and third extracting means;
An ophthalmic imaging apparatus characterized by comprising: The first fundus image is an image including the optic disc and macula of the fundus;
The ophthalmologic imaging apparatus according to claim 1, further comprising setting means for setting the predetermined intensity so that the first area is an area corresponding to the optic nerve head of the fundus. An observation light source for generating the first and second light amounts;
A light source for photographing that generates the third amount of light;
Calculating means for calculating the second light amount so that the light amount of the first region becomes an appropriate light amount, and calculating the third light amount so that the light amount of the second region becomes an appropriate light amount;
Control means for controlling the observation light source and the imaging light source according to the calculation result of the calculation means;
The ophthalmic imaging apparatus according to claim 1, wherein the ophthalmic imaging apparatus is provided.   The ophthalmic imaging apparatus according to claim 3, wherein the synthesis of the images is performed between images in which a difference between a color temperature of the observation light source and a color temperature of the imaging light source is corrected. Focusing means for focusing the return light from the fundus on the imaging means;
Moving means for moving the focusing means to a position where the fundus and the imaging means are substantially conjugate,
The second fundus image including the optic nerve head of the fundus and the third fundus image including the macula of the fundus are photographed at different positions. The ophthalmic imaging apparatus described. An ophthalmic imaging apparatus for imaging a subject's eye,
An illumination optical system for illuminating the eye to be examined;
An imaging optical system including focusing means for focusing the return light from the eye to be imaged on the imaging means;
A focus index projecting unit provided in the illumination optical system and projecting a focus index onto the eye to be examined;
First moving means for moving the focus index projection means to a position substantially conjugate with the eye to be examined;
A second moving means for moving the focusing means to a position where the focus index projecting means and the imaging means are substantially conjugate;
An ophthalmic imaging apparatus characterized by comprising:   The ophthalmic imaging apparatus according to claim 6, wherein the first and second moving units are focus link mechanisms that move the focus index projecting unit and the focusing unit in conjunction with each other. The focus index projecting means;
A focus index light source provided outside the optical path of the illumination optical system;
A prism portion for deflecting a light beam from the focus index light source;
An opening that projects the deflected light flux on the fundus of the eye as the focus index;
The ophthalmic imaging apparatus according to claim 6 or 7, characterized by comprising: An input means for inputting a photographing signal;
Control means for controlling the first moving means and retracting the focus index projection means out of the optical path in accordance with the photographing signal;
The ophthalmic imaging apparatus according to claim 6, wherein the ophthalmic imaging apparatus is provided. An ophthalmic imaging apparatus for imaging the fundus of a subject's eye,
An observation light source for generating observation light for illuminating the eye to be examined via an illumination optical system;
A focus index projecting unit that is provided in the illumination optical system and projects a focus index on the fundus of the eye to be examined;
An input means for inputting a photographing signal;
Moving means for moving the focus index projection means out of the optical path in response to the photographing signal;
Extraction means for extracting an area corresponding to the optic nerve head of the fundus from the fundus image of the fundus based on the observation light according to the movement of the focus index projection means outside the optical path;
An ophthalmic imaging apparatus characterized by comprising: An ophthalmic imaging method for imaging the fundus of a subject's eye,
A first region image that is a predetermined intensity or higher and a second region image other than the first region are extracted from a first fundus image captured with the first light amount, respectively. An extraction process;
A second extraction step of extracting an image of a region corresponding to the first region out of a second fundus image captured with a second light amount based on the light amount of the first region;
A third extraction step of extracting an image of a region corresponding to the second region out of a third fundus image captured with a third light amount based on the light amount of the second region;
An image synthesis step of synthesizing the images extracted by the second and third extraction steps;
An ophthalmologic imaging method comprising: The second extraction step includes a first conjugation step in which the fundus and the imaging unit are substantially conjugated before photographing the second fundus image including the optic disc of the fundus;
11. The ophthalmic imaging according to claim 10, wherein the third extraction step includes a second conjugation step for making the substantially conjugate state before photographing a third fundus image including the macular of the fundus. 11. apparatus.   A program for executing the ophthalmic imaging method according to claim 11 or 12 on a computer.