JP2008018043A - Eye fundus photographing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an eye fundus photographing system capable of focusing easily and consistently during the photographing operation of the fundus. <P>SOLUTION: The fundus of a test eye is photographed through a photographing aperture 28 having two openings 28a, 28b with CCD 40 as an electronic image. During observation, the two openings of the photographing aperture are released and focusing is operated from the image of the fundus obtained through the two openings. If the fundus is out of focus, the images of the fundus passed through the two openings are different and observed as double image, and the focus is adjusted to make them one image of the fundus. This configuration makes it easy to find defocus, and the focus mark and the projective mechanism of the focus mark are not needed, so that the device becomes easy optical configuration as a whole to keep the cost of manufacturing reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fundus photographing apparatus, and more particularly, to a fundus photographing apparatus that photographs a fundus as an electronic image through a two-aperture photographing aperture to stereoscopically view the fundus.

  Conventionally, in a fundus photographing apparatus such as a fundus camera, focusing is performed according to the eye diopter for obtaining a clear fundus image. There are roughly two types of focusing means for the fundus camera, and one of them is a method in which the examiner observes the fundus image with a viewfinder or a monitor and finds the most focused position. However, this method has a drawback in that it is difficult to know whether or not the subject is completely in focus, and the skill of the examiner is required.

  Therefore, as can be seen in Patent Document 1 below, a method is conceived in which focus index light is projected in advance from two directions onto the fundus and the focus is confirmed by a change in the shape of the index.

Furthermore, when the working distance is appropriate, an index light source is provided at a position where the light beam regularly reflected by the cornea of the eye to be examined is almost afocal (Patent Document 2).
JP-A-60-103932 Japanese Patent Publication No. 60-52820

  However, the focusing mechanism of Patent Document 1 and the like was convenient for a normal monaural fundus camera. For example, in order to stereoscopically view a fundus image, the fundus image is captured in stereo with parallax. In this case, since the two-hole aperture for stereo shooting collides with a mechanism for dividing the focus index in two directions, the index projection system must be retracted through the moving mechanism at the time of shooting. There was a problem of not becoming.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a fundus imaging apparatus that can easily and surely focus during fundus imaging.

The present invention
Imaging means for imaging the fundus of the eye to be examined as an electronic image via an imaging aperture having two or more apertures;
Switching means for switching opening and closing of the plurality of openings;
A focus adjustment mechanism for focusing according to the diopter of the eye to be examined,
Two of the apertures of the photographing diaphragm are opened during observation, and focusing is performed based on an image of the fundus of the eye to be examined obtained through the two apertures.

  In such a configuration, when the focus is not on the fundus, the fundus image that has passed through the two openings becomes a separate image and is observed as a double image, so it is easily determined that the image is defocused. In addition, since the focus index and the projection mechanism for the focus index are not required, the entire optical system is simple and the manufacturing cost can be reduced.

  Hereinafter, the present invention will be described in detail based on an embodiment in which the fundus photographing apparatus is a fundus camera.

  In the fundus camera 10 illustrated in FIG. 1 surrounded by a one-dot chain line, an observation lamp 11 that emits infrared light and visible illumination light is disposed at the center of curvature of the spherical mirror 12. The light from the mirror 12 is incident on the total reflection mirror 17 through a visible light cut infrared light transmission filter 13 that can be inserted into and removed from the optical path, a condenser lens 14, a strobe 15 that is a photographing light source, and a condenser lens 16.

  The illumination light reflected by the total reflection mirror 17 passes through the relay lens 22 through the illumination diaphragm 19 or 20, is reflected by the perforated total reflection mirror 23, passes through the objective lens 24, and is an anterior eye part (pupil) of the eye E to be examined. Incident on Ep. The illumination diaphragms 19 and 20 are disposed in the illumination optical system at a position substantially conjugate with the anterior segment Ep (pupil) of the eye to be examined, and the illumination diaphragm 19 is inserted into the optical path during observation and the illumination diaphragm 20 during imaging. Is done.

  An exciter filter 18 is inserted in the optical path of the illumination optical system at the time of fluorescent photographing.

  The reflected light from the fundus Er illuminated with the illumination light is transmitted through the objective lens 24, the aperture 23a of the perforated total reflection mirror 23, the aperture of the 2 aperture aperture stop (2 aperture aperture) 28, the focusing lens 35, and the imaging lens 36. Then, the light passes through the half mirror 37 and the variable magnification lens 38a (38b) and enters the return mirror 39. At the position where the return mirror 39 is shown, the reflected light from the fundus is incident on a CCD (imaging means) 40 at a position conjugate with the fundus sensitive to infrared light, the fundus is imaged by the CCD 40, and the return mirror 39 Is separated from the optical path, the reflected light from the fundus enters the CCD (imaging means) 41 conjugate with the fundus sensitive to visible light, and the fundus is photographed by the CCD 41.

  As shown in FIG. 2, two rectangular openings 28 a and 28 b are provided in the photographing aperture 28, and an optical fiber 33 (described later) is inserted and fixed at the center of the photographing aperture 28. The end face of the optical fiber 33 is positioned at the imaging or observation optical axis 26, and the imaging aperture 28 is arranged so that its apertures 28a and 28b are symmetrical with respect to the optical axis 26, and the anterior eye segment (pupil) of the eye to be examined. Are arranged so as to be substantially conjugate with each other. The positions and sizes of the openings 28a and 28b are set so that the opening 23a of the perforated total reflection mirror 23 includes the entire openings 28a and 28b.

  The apertures 28a and 28b of the photographing aperture 28 are opened or closed by shutter plates 29 and 30 that are moved along guides 28c and 28d, respectively. For this opening and closing, switching means comprising rotary solenoids 31 and 32 is provided. When the rotary solenoids 31 and 32 are not energized, the shutter plates 29 and 30 are at the position of FIG. , 28b are opened. On the other hand, when energized, the rods 31a, 32a of the rotary solenoids 31, 32 rotate, and the other ends of the rods 31a, 32a are engaged with pins 29a, 30a provided on the shutter plates 29, 30. As a result, the shutter plates 29 and 30 are moved inward to close the openings 28a and 28b.

  The fundus camera 10 is provided with an index light source 50 that emits infrared light or visible light. Light from the index light source 50 is guided to the center of the photographing aperture 28 via the lens 51 and the optical fiber 33. An index for working distance (hereinafter referred to as WD index) is formed by the tip of the optical fiber 33 on the eye side to be examined. This WD index is projected onto the cornea of the eye E by the objective lens 24, and when the working distance is appropriate, the position is set so that the light beam regularly reflected by the cornea of the eye to be examined becomes almost afocal. Is done.

  A barrier filter 34 is inserted on the eye side of the focusing lens 35 during fluorescence imaging.

  Further, in order to fix the eye to be examined with respect to the fundus camera, an internal fixation lamp 55 including a plurality of fixation lamps 55a to 55d is provided, and any one of the fixation lamps 55a to 55d is provided depending on imaging conditions. It is turned on and projected onto the eye to be examined through the lens 56. The patient can hold the eye to be examined in a predetermined position with respect to the fundus camera by fixing the internal fixation lamp. In the drawing, the fixation lamps 55a to 55d are illustrated as being juxtaposed on the paper surface, but actually, they are juxtaposed perpendicular to the paper surface.

  The CCD 40 images the fundus illuminated by the infrared light that has passed through the visible light cut infrared light transmission filter 13, and the image is input to a control calculation unit 60 configured by a CPU or the like. Displayed as a moving image. The examiner looks at the image displayed on the monitor 62 and can perform alignment and focus adjustment as will be described later. In addition, a stereo monitor 63 is provided as a stereoscopic display, and the examiner can observe the fundus in a stereoscopic manner by observing the left and right images through the stereo monitor 63.

  Further, the CCD 41 shoots the fundus illuminated by the strobe 15 as a still image when the shutter switch 66 is operated. This fundus image is temporarily stored in the high-speed memory 61 and recorded in a recording means realized by a low-speed hard disk (HDD) 64 as an external recording device via the control calculation unit 60, or the monitor 62, stereo monitor 63.

  Also, input means such as a keyboard 67 and a mouse 68 are provided, and various data can be input via these input means.

  Further, the fundus camera is provided with a control unit 65 composed of a CPU or the like. The control unit 65 is connected to the control calculation unit 60 and exchanges signals with each other. When the shutter switch 66 is operated, the control unit 65 returns. The mirror 39 is removed from the optical path, and the strobe 15 is caused to emit light with an appropriate amount of light. Further, the control unit 65 controls insertion / removal of the visible light cut infrared light transmission filter 13, exciter filter 18, barrier filter 34, and variable magnification lenses 38 a and 38 b into the optical path, and controls driving of the rotary solenoids 31 and 32. To do.

  In addition, the fundus camera is provided with an operation unit (operation panel) 69, and the operation unit 69 can select a photographing mode. Further, a left / right eye detection unit 70 that detects whether the subject eye to be photographed is the left eye or the right eye is provided, and information on whether the detected left eye or right eye is detected is input to the control unit 65.

  Next, a flow of acquiring a stereoscopic fundus image in such a configuration will be described.

  First, at the time of observation, the observation lamp 11 and the index light source 50 are turned on, and the illumination stop 19 is inserted into the optical path. The rotary solenoids 31 and 32 are driven to the positions as shown in FIG. 2A, whereby the two openings 28a and 28b of the photographing aperture 28 are in the open positions. As shown in FIG. 3A, since the openings 28a and 28b lead to the opening 23a of the perforated total reflection mirror 23, the reflected light from the optometry fundus irradiated with the infrared light through the illumination diaphragm 19 is The image is received by the observation CCD 40 through the openings 28 a and 28 b of the photographing aperture 28, and the fundus image and the index image are displayed on the monitor 62.

  FIGS. 4 and 5 schematically show the optical arrangement of the fundus camera when performing alignment including focusing (focus adjustment) and adjustment of the working distance, and the parts corresponding to FIG. 1 are the same. The code | symbol is attached | subjected. The optical system from the photographing aperture 28 to the CCD 40 in FIG. 1 is collectively shown as an imaging lens 80 in FIGS. 4 and 5, and focus adjustment is performed by moving the imaging lens 80 along the optical path. The ability to do this is indicated by a double arrow line. Further, although the photographing aperture 28 is illustrated in such a manner that the openings 28a and 28b are positioned in the vertical direction, in reality, it is positioned in the horizontal direction (direction perpendicular to the paper surface in the drawing).

  During fundus observation, the fundus Er of the subject eye E is once imaged by the objective lens 24, then passes through the apertures 28a and 28b of the imaging aperture 28 conjugate with the anterior eye pupil, and is imaged on the CCD 40 by the imaging lens 80. Therefore, as shown in FIG. 4A, when the focus is not on the fundus, the fundus image 91 by the objective lens 24 is positioned away from the image receiving surface of the CCD 40 by the imaging lens 80. Re-imaged. Accordingly, two fundus images that have passed through the optical paths of the photographing apertures 28a and 28b are separated and received by the CCD 40, and as shown on the right side of FIG. The images are displayed partially overlapping.

  Therefore, the examiner moves the imaging lens 80 (the focusing lens 35 in FIG. 1) according to the diopter of the eye to be examined, and performs focus adjustment. When the focus is on the fundus, the fundus image 92 re-imaged by the imaging lens 80 comes to the image receiving surface of the CCD 40, as shown in FIG. The fundus images will overlap. If they are completely overlapped, it is a so-called “Jaspin” state. Therefore, if the fundus image is separated and looks double, it is determined that the image is out of focus, and focus adjustment is performed so that the images are completely overlapped.

  As described above, since focusing can be performed based on the fundus image obtained through the aperture of the photographing aperture, it is possible to easily determine the focus state and to eliminate the need for a separate focus index projection system, so that the photographing apparatus can be configured at low cost. It can be.

  On the other hand, alignment adjustment is performed by observing an image of a WD index formed on the end face of the optical fiber 33. When the working distance is in an appropriate position, as shown in FIG. 5 (a), the WD index is incident through the objective lens 24 toward the center of the curvature radius of the cornea of the eye E and the midpoint of the cornea surface. As a result, the light beam projected onto the cornea and specularly reflected by the eye cornea as a result becomes a substantially afocal light beam 90 (see Patent Document 2). Accordingly, this light beam is once condensed on the fundus imaging surface 91, passes through the openings 28 a and 28 b of the photographing aperture 28, and is re-imaged on the fundus imaging surface 92 by the imaging lens 80. Accordingly, on the monitor 62, as shown on the right side of FIG. 5A, the WD index is displayed as one index image 33a in the fundus image. As a result, alignment in the direction (X, Y direction) perpendicular to the optical axis can be performed.

  On the other hand, when the working distance is not appropriate and the eye to be inspected is a little closer to the imaging device as shown by the solid line in FIG. The image formation position is also a position 91 ′ that deviates from the image formation position (fundus image formation position) when the working distance is an appropriate position, and the WD index is separated into two index images 33b and 33c at the fundus image 92. To form an image.

  Further, as indicated by the dotted line, when the subject's eye moves away from the imaging device from the proper position, the light beam regularly reflected by the subject's eye cornea is collected in front of the subject's eye (not shown), and similarly, An index image is formed. Further, as indicated by the alternate long and short dash line, when the subject's eye moves further away, the light beam regularly reflected by the subject's eye cornea diverges too much to form an image as shown by 94, and the index image does not appear on the monitor. .

  In this way, by adjusting the WD index image to be one image, the alignment (working distance) in the optical axis direction is adjusted, and the index image that becomes one is positioned at the substantially center position of the fundus image. Thus, alignment in the direction (X, Y direction) perpendicular to the optical axis is performed to complete the alignment.

  When the fundus image is displayed twice during the alignment adjustment, the focus is not in focus, so the focus is readjusted.

  When the focus and alignment are completed in this way, the shutter switch 66 is pressed. In response to the pressing, the control unit 65 drives the rotary solenoid 31 to move the shutter plate 29 to the right, and closes the opening 28a on the left side of the photographing aperture 28 as shown in FIG. The strobe 15 emits light in synchronization with the operation of the shutter switch 66, and the return mirror 39 leaves the optical path, so that the light flux from the fundus illuminated by the strobe passes through the opening 28b of the photographing aperture 28 that is open. The light enters the image receiving surface of the CCD 41, and the first fundus image for stereoscopic viewing is captured as a still image by the CCD 41 and stored in the memory 61.

  Subsequently, when the rotary solenoids 31 and 32 are controlled and the shutter plates 29 and 30 are moved leftward as shown in FIG. 3C, the opening 28a is opened and the opening 28b is closed. 15 is made to emit light again. At this time, the second fundus image for stereoscopic viewing that has passed through the opening 28 a is captured as a still image by the CCD 41 and stored in the memory 61.

  In this way, the two right and left fundus images for stereoscopic viewing, which are continuously photographed by a single shutter operation, include information such as the opening position, left position, and right position of the open photographing aperture. In addition, it is stored in the HDD 64 from the memory 61. The two fundus images stored in this way are read from the HDD 64 and displayed using the stereo monitor 63, and the examiner observes one corresponding fundus image with the left and right eyes. The fundus can be viewed stereoscopically.

  In the above-described embodiment, the photographic diaphragm 28 is provided with only two openings. However, a larger opening is provided, and two of the plurality of openings are opened. Focusing may be performed based on a fundus image obtained through two openings.

  As described above, when the focus is not on the fundus, the fundus image that has passed through the two apertures of the photographing aperture becomes a separate image and is separated and observed as a double image, so defocusing is easy. In addition, when the alignment is adjusted, the index image is divided into two if the working distance is not appropriate, so that it is easy to determine that the working distance is not appropriate. Further, since the focus index and the projection mechanism for the focus index are not necessary, the optical system has a simple configuration as a whole, and the manufacturing cost can be reduced. Further, since the same photographing aperture is used for observation and photographing, only the shutter plate moves at the time of transition from observation to photographing, so that the moving mechanism can be simplified.

It is the block diagram which showed the optical system of the fundus imaging apparatus of this invention. (A) is a front view when the photographing aperture is viewed from the photographing side, and (b) is a cross-sectional view taken along X-X ′ of (a). It is explanatory drawing when switching opening and closing of the opening of a photographic aperture. It is explanatory drawing explaining focus adjustment. It is explanatory drawing explaining alignment adjustment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fundus camera 24 Objective lens 28 Imaging stop 28a, 28b Aperture 29, 30 Shutter plate 31, 32 Rotary solenoid

Claims (4)

Imaging means for imaging the fundus of the eye to be examined as an electronic image via an imaging aperture having two or more apertures;
Switching means for switching opening and closing of the plurality of openings;
A focus adjustment mechanism for focusing according to the diopter of the eye to be examined,
A fundus photographing apparatus characterized in that two of the photographing diaphragm apertures are opened during observation, and focusing is performed based on an image of the fundus of the eye to be examined obtained through the two openings.   The fundus imaging apparatus according to claim 1, wherein an index is projected toward a subject's eye cornea from between two apertures of the imaging diaphragm, and alignment with the subject's eye is performed.   3. The fundus imaging apparatus according to claim 1, wherein at the time of imaging, one opening of the imaging aperture is opened to image the fundus of the eye to be examined.   The fundus photographing according to claim 3, wherein two apertures of the photographing aperture are opened one by one by one shutter operation, and two fundus oculi images are photographed through the opened apertures. apparatus.

Images