JP5015292B2 - Fundus camera - Google Patents

Description

  The present invention relates to a fundus camera. More specifically, the present invention is capable of irradiating light from an observation light source to a fundus of an eye to be examined through an illumination system, and taking a picture of the irradiated fundus through a photographing optical system. The present invention relates to a fundus camera having both pupil type and non-mydriatic type functions.

  Generally, a mydriatic type fundus camera and a non-mydriatic type fundus camera are known as cameras for imaging a fundus image by forming an image of reflected light from the fundus illuminated by light from a light source. The mydriatic fundus camera mainly uses a light source of visible light, can capture a wide angle of view, and has a tilt mechanism of the camera itself, so that the entire fundus can be photographed. A drawback of this type of fundus camera is that the subject's eye needs to be mydriatic and places a great burden on the subject. On the other hand, the non-mydriatic fundus camera uses infrared light as the light source, so it is not necessary to make the subject's eye mydriatic, but the angle of view is not as wide as the mydriatic and can be taken around the fundus macular area. Done.

  In recent years, mydriatic and non-mydriatic integrated fundus cameras that have these mydriatic and non-mydriatic functions have been realized.

  In such a fundus camera, an aperture stop is disposed in the photographing optical path in order to remove the reflected light of the illumination light. This aperture stop removes the reflected light from the lens, cornea, and iris, and also guides as much reflected light from the fundus through the pupil to the imaging optical system. It is best to decide. On the other hand, with regard to the aperture stop position, it is optimal that the aperture stop comes to the front of the crystalline lens when the pupil is dilated, but when the pupil is non-mydriatic, the pupil diameter is small, so that it is optimal to be at a position substantially conjugate with the inside of the crystalline lens ( Patent Document 1) below.

Japanese Patent Laid-Open No. 62-179431

  Because of this situation, the optimal aperture stop diameter and aperture stop position differ between mydriatic and non-mydriatic shooting, so if the aperture stop position or diameter is fixed, The best fundus image could not be taken for both pupils.

  The present invention has been made to solve such a problem, and it is an object of the present invention to provide a fundus camera capable of photographing the best fundus image regardless of mydriatic or non-mydriatic photographing. And

The present invention
In a fundus camera that irradiates the fundus of an eye to be examined with light from an observation light source through an illumination system, and images an image of the irradiated fundus through an imaging optical system,
Means for switching the wavelength of the observation light source;
An aperture stop disposed between the objective lens and the focusing lens of the photographing optical system;
A mask for determining an imaging range arranged at a fundus conjugate position in the imaging optical system,
The aperture diameter of the aperture stop is switched according to the switching of the wavelength of the observation light source, and photographing is performed by changing the shape of the mask.

  In the present invention, the diameter of the aperture stop arranged in the imaging optical system is switched according to the switching of the wavelength of the observation light source, and the shape of the mask that determines the imaging range is changed according to the switching. The best fundus image can be taken with no photography or non-mydriatic photography.

1 is an optical diagram showing the overall configuration of a fundus camera of the present invention. It is an optical diagram which shows the relationship between the position of the image of an aperture stop, and illumination light.

  Hereinafter, the present invention will be described in detail according to embodiments shown in the drawings.

  FIG. 1 shows a fundus camera according to the present invention. A lamp LA, which is an observation light source, is disposed at the center of the mirror M1, and light emitted from the lamp LA includes wavelengths in the visible light and infrared light bands, the condenser lens 1, and a strobe light (photographing light source). Flash lamp) SR, the condenser lens 2 and then reflected by the total reflection mirror M2, followed by the lens 3, the ring slit 4 for forming the ring-shaped illumination, the relay lens 5, and the black spot for reflecting the objective lens After being reflected by the plate 6, the relay lens 7, and the perforated total reflection mirror M <b> 3 having a hole in the center, the light passes through the objective lens 8 and enters the fundus Er from the pupil Ep of the eye E to be examined. Filter F is a visible light cut filter that is inserted into the optical path when the fundus camera is used as a non-mydriatic type, so that the wavelength of light from the light source LA is almost the wavelength of infrared light, while it is used as a mydriatic type. In this case, as shown in the figure, the optical path is separated.

  The reflected light from the fundus Er is again received from the pupil Ep via the objective lens 8, passes through the hole of the perforated total reflection mirror M3, is narrowed down by the aperture stop 31, and is further focused on the focusing lens 9 and the imaging lens. 10 and enters the return mirror M4. The aperture stop 31 is disposed at a position where an image is formed on the front surface of the crystalline lens of the eye E through the objective lens 8. An aperture stop 30 having a diameter smaller than that of the aperture stop 31 is disposed between the aperture stop 31 and the holed total reflection mirror M3 so as to be inserted into and removed from the optical path. The aperture stop 30 is separated from the optical path as shown when the fundus camera is used as a mydriatic type, and is inserted into the optical path when used as a non-mydriatic type. This insertion position is set at a position where the aperture stop 30 is imaged inside the crystalline lens of the eye E to be examined (substantially in the center) via the objective lens 8.

  The light incident on the return mirror M4 is reflected by the return mirror M4 and the mirror M5 at the time of observation, and is observed by the examiner S through the field stop 12 and the field lens 13 by the eyepiece 14. The return mirror M4 is removed from the optical path when shooting on the film 11.

  In addition, the fundus camera is configured to be able to shoot with a CCD camera instead of a film. When shooting with a CCD camera, the mirrors M5 and M6 are detached from the optical path and a fundus image is taken through the lens 23. To the CCD camera 24. Further, when the fundus camera is used with a non-mydriatic type, since observation is performed with infrared light, an observation CCD 26 having sensitivity to infrared rays is provided instead of observation through the eyepiece 14. At the time of observation with infrared light, the light beam reflected by the return mirror M4 after the mirror M5 leaves the optical path is reflected by the mirror M6 and enters the observation CCD camera 26 via the filter 21 and the lens 25.

  In addition, a mask 32 is provided between the mirrors M5 and M6, which is arranged at the fundus conjugate position and determines an imaging range. This mask 32 is replaced with a mask 33 when the fundus camera is used as a non-mydriatic type. The mask 33 has a substantially circular shape, and the mask 32 has an oval shape in which the upper and lower portions are cut and the left and right directions are stretched, and the area of the transmission portion is larger than that of the mask 33.

  In FIG. 1, a filter F1 is an exciter filter that is inserted into the optical path of the illumination system during fluorescence imaging, and a filter F2 is a barrier filter that is inserted into the optical path of the imaging system during fluorescence imaging.

  In such a configuration, when the subject's eye is mydriatic and the fundus camera is used as a mydriatic type, as shown in the figure, the filter F and the aperture stop 30 are separated from the optical path, and the mask 32 is the imaging optical path. Has been inserted. The examiner observes the image from the fundus illuminated with visible light through the eyepiece 14 because the mirror M5 is at the position shown in the figure. In this case, the aperture stop of the photographing optical system is the aperture stop 31. The aperture stop 31 is disposed at a position where the image is formed on the front surface of the crystalline lens of the eye E via the objective lens 8, and the image of the aperture stop 31 has a large diameter in accordance with the diameter of the pupil Ep that is enlarged due to mydriasis. Therefore, a lot of reflected light can be guided from the fundus through the pupil, and harmful reflected light can be cut at the same time.

  When the fundus image is shot and recorded on the film 11, when the shutter is pressed, the mirror M4 jumps up and is fixed at a position where the light is transmitted, and the strobe SR emits light during that time and shooting is performed. When shooting and recording with the CCD camera 24, when the shutter is pressed, the mirrors M5 and M6 move in the direction of transmitting light to the CCD camera 24, and the reflected light from the fundus Er reaches the CCD camera 24 via the mask 32. A fundus image is taken by the CCD camera 24.

  On the other hand, when the eye to be examined is switched to the non-mydriatic type in which the image is taken in the non-mydriatic state, the filter F is inserted into the optical path, thereby cutting the visible light from the observation light source LA, so that the luminous flux emitted from the light source LA is reduced. The wavelength characteristic is switched from visible light to infrared light. When switched to the non-mydriatic type, the aperture stop 30 is inserted into the optical path and the mask is switched to the non-mydriatic photographing mask 33.

  At this time, since the observation light is transmitted through the filter F and the visible light is cut off, the visible light is not irradiated to the eye to be examined, and the eye to be examined does not have a miosis, thus allowing observation. However, since observation is performed with infrared light, observation with the naked eye is not possible, and thus the mirror M5 is removed from the optical path and observation is performed with the observation CCD camera 26. In this case, the inserted aperture stop 30 is effective as the aperture stop of the photographing optical system, and the aperture stop 31 is sufficiently larger than the effective diameter of the light beam so that the optical system is not affected.

  As shown in FIG. 2, the aperture stop 30 is arranged at a position where an image is formed inside the crystalline lens Ec of the eye E by the objective lens 8 and an image 30 ′ of the opening is formed there. The diameter of the aperture stop 30 is smaller than the diameter of the aperture stop 31, and the diameter of the image 30 ′ of the opening of the aperture stop 30 is almost the same as the small pupil diameter when irradiated with infrared light. Yes. Accordingly, since the aperture stop diameter corresponds to the pupil diameter, a large amount of reflected light from the fundus can be guided to the photographing optical system. Further, as is apparent from the figure, the fundus illumination angle φ1 (shown by a solid line) when the image of the aperture stop 30 is formed inside the crystalline lens is that the image of the aperture stop 30 is the front surface of the crystalline lens (corresponding to the position of the pupil). Can be set smaller than the fundus illumination angle φ2 (illustrated by a one-dot chain line) in the case of forming the eyelid, so that the amount of light at the center of the fundus can be relatively increased. Therefore, a lot of reflected light can be guided from the fundus through the pupil, and good observation and photographing can be performed.

  When the fundus image is photographed on the film 11 after observation, when the shutter is pressed, the mirror M4 is removed from the optical path. When the CCD camera 24 is photographed, the mirror M6 is removed from the optical path, and the strobe SR is emitted during that time. Thus, the reflected light from the fundus reaches the film 11 or the photographing CCD camera 24, and the fundus image is photographed on the film 11 or the CCD camera 24, respectively.

  In the above-described embodiment, the aperture stop 31 is fixed regardless of the switching between the mydriatic and the non-mydriatic, but when switched to the non-mydriatic type, the aperture stop 31 may be separated from the optical path.

LA illumination light source SR strobe F visible light cut filter Er fundus Ep pupil 24 CCD camera for photographing 26 CCD camera for observation 30, 31 Aperture stop 32, 33 Mask

Claims (5)

In a fundus camera that irradiates the fundus of an eye to be examined with light from an observation light source through an illumination system, and images an image of the irradiated fundus through an imaging optical system,
Means for switching the wavelength of the observation light source;
An aperture stop disposed between the objective lens and the focusing lens of the photographing optical system;
A mask for determining an imaging range arranged at a fundus conjugate position in the imaging optical system,
A fundus camera, wherein the aperture diameter of the aperture stop is switched in accordance with the switching of the wavelength of the observation light source, and photographing is performed by changing the shape of the mask.   The fundus camera according to claim 1, wherein the position of the aperture stop is switched according to switching of the wavelength of the observation light source.   When the wavelength of the observation light source is switched to visible light or infrared light, and the wavelength of the observation light source is switched to infrared light, the diameter of the aperture stop is the same as that of the aperture stop when the observation light source is visible light. The fundus camera according to claim 1, wherein the fundus camera is smaller than the diameter.   When the wavelength of the observation light source is visible light, the aperture stop is disposed at a position substantially conjugate with the front surface of the lens, and when the wavelength is switched to infrared light, the position of the aperture stop is substantially conjugate with the inside of the lens. The fundus camera according to claim 2, wherein the fundus camera is disposed on the fundus.   The fundus camera according to any one of claims 1 to 4, wherein the observation means is switched according to switching of the wavelength of the observation light source.

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