JP2002051985A - Fundus camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fundus camera whereby reliable fundus oculi images are obtained even if a mydriasis condition is poor, and pupil diameters are small. SOLUTION: Fundus oculi images illuminated through ring slit 6 are observed through an ocular lens 18; the images are also photographed using a film 15 or a CCD camera 22. When a mydriasis of an examinee is not in a good condition, a ring slit 6' with a small inside diameter is used; lighting quantity is increased by the ring slit, and a good lighting is obtained in spite of a small pupil diameter. A flare or ghost arising at a periphery of the fundus oculi images is removed using small aperture diaphragms 20'. The fundus oculi images are edited so as not to display the peripheries by an image editing-recording device 23. Thus, reliable fundus oculi images are obtained even if the pupil diameters of the examinee are small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus camera, and more particularly to a fundus camera for observing or photographing a fundus illuminated via an illumination optical system via a photographing optical system.

[0002]

2. Description of the Related Art In a fundus camera of this type, the fundus is illuminated from the periphery of the pupil through a ring slit image formed in the pupil of the eye to be examined, while reflected light from the fundus is extracted from the central area of the pupil, and illumination light and reflected light are extracted. Is separated, so that the flare due to the corneal reflected light can be prevented from being observed or photographed.

As described above, when observing or imaging the fundus of a subject illuminated through the ring slit, if the mydriatic state of the subject is not sufficient, it is possible to sufficiently illuminate the imaging range with illumination light. Cannot be used, and the reflected light from the fundus cannot be used efficiently. Therefore, when the subject's mydriasis is not enough, or when the subject is a small pupil, such as a child, the light irradiates the fundus. The inner diameter of a ring slit that is formed in an annular shape is made small, so that a large amount of illumination light is incident (Japanese Patent Laid-Open No. 1-58238).

Further, when the inner diameter of the ring slit is reduced, the periphery of the illumination field is affected by flare or ghost. Therefore, the aperture of the illumination field is narrowed in conjunction with the inner diameter of the ring slit to prevent flare or ghost. The best illumination light incidence and reflected light extraction are achieved (Japanese Patent Laid-Open No. 3-128038).

[0005]

However, since the human eye has a complicated structure, even if the mydriasis of the eye to be examined is not sufficient even in the above-described method, the peripheral portion in the fundus image may come from the lens or the cornea. Harmful flares enter, making it difficult to see the fundus image and deteriorating the quality of the captured fundus image.

Accordingly, the present invention has been made to solve such a problem, and a reliable fundus image can be obtained even when the eye to be inspected has a poor mydriatic state and the pupil diameter of the eye to be inspected is small. It is an object to provide a fundus camera.

[0007]

According to the present invention, there is provided a fundus camera for observing or photographing a fundus illuminated through an illumination optical system through a photographing optical system. And a ring slit arranged in the illumination optical system to form an annular illumination light beam at a substantially conjugate position,
An aperture stop which is disposed at a position substantially conjugate with the fundus of the eye to be examined in the photographing optical system in order to reduce the reflected light from the eye to be examined, means for varying the inside diameter of the ring slit, and a change in the inside diameter of the ring slit And means for varying the aperture diameter of the aperture stop according to the conditions.

Further, according to the present invention, in a fundus camera for observing or photographing a fundus illuminated via an illumination optical system via a photographing optical system, an annular illumination light beam is formed at a position substantially conjugate with a pupil of the eye to be examined. A ring slit arranged in the illumination optical system, means for changing the inner diameter of the ring slit, means for observing or imaging the fundus, and displaying or observing or displaying according to a change in the inner diameter of the ring slit And means for limiting the display area of the fundus image to be displayed.

In such a configuration, when the mydriatic state of the subject is not good, that is, when the subject has a small pupil, the inner diameter of the ring slit is changed to a smaller diameter, whereby the amount of illumination light by the ring slit is increased, and Good illumination is obtained despite the pupil. Harmful flares or ghosts from the lens or cornea generated around the fundus image may be cut by narrowing the aperture stop or by not displaying the periphery of the fundus image. And a reliable fundus image can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 shows the overall configuration of a fundus camera according to the present invention. In the figure, light emitted from a lamp 1 which is a light source for observation is a condenser lens 2,
The light is reflected by a total reflection mirror 5 through a strobe light 3 as a light source for photography and a condenser lens 4 to illuminate a ring slit 6. The ring slit 6 has a predetermined outer diameter and inner diameter, and forms an annular illumination light beam at a position substantially conjugate with the pupil Ep of the eye E to be inspected.

The luminous flux from the ring slit 6 passes through a relay lens 7, an illumination field stop 8, and a relay lens 9, is reflected by a perforated total reflection mirror 10 having a hole at the center, and then passes through an objective lens 11. After an image is formed on the pupil Ep of the eye E, the light enters the fundus Er and illuminates the fundus almost uniformly. The illumination field stop 8 is arranged at a position substantially conjugate with the fundus Er of the eye E to be examined, and narrows down the illumination light beam.

The reflected light from the fundus Er illuminated by the light beam from the ring slit 6 formed in the region of the substantially pupil Ep of the subject's eye E passes through the center of the pupil Ep again and passes through the objective lens 11. Through a hole of a perforated total reflection mirror 10, passing through a focusing lens 12 and an imaging lens 13 arranged in an optical path for photography, and returning to a return mirror 14.
Incident on.

The light beam from the fundus reflected by the return mirror 14 is stopped down by an aperture stop 20 arranged at a position substantially conjugate with the fundus Er of the eye to be examined, passes through a lens 16 and is reflected by a return mirror 17. Reaches the examiner S via the eyepiece 18. The return mirror 17 can be moved to the position shown by the dotted line. In this case, the light beam that has passed through the lens 16 is condensed on the CCD camera 22 by the imaging lens 21 and the fundus image is captured by the CCD camera 22. The fundus image captured by the CCD camera 22 is edited and recorded by an image editing and recording device 23, and the edited or recorded fundus image can be observed on a monitor 24 connected to the image editing and recording device 23.

A film 15 is disposed behind the return mirror 14, and when the return mirror 14 moves to a position indicated by a dotted line, light reflected from the fundus is transmitted to the film 15.
And a fundus image is captured on film.

The inner diameter of the ring slit can be made variable, and one embodiment is shown in FIG. In the figure, two ring slits 6, 6 'are 2
It is formed on a plate 30 movable along a rail 31 by a drive source (not shown). The ring slits 6 and 6 'have the same outer diameter D, but the inner diameter d1 of the ring slit 6 is larger than the inner diameter d2 of the ring slit 6'. Therefore, when the ring slit 6 'is inserted into the optical path, the amount of illumination light becomes larger than when the ring slit 6 is inserted.

Similarly, the diameters of the illumination field stop and the aperture stop can also be changed. The illumination field stop 8 has a slightly larger aperture diameter than the illumination field stop 8 '.
0 indicates that the aperture diameter is slightly larger than that of the aperture stop 20 '. Each illumination field stop 8, 8 'and aperture stop 20, 20'
Can be formed on plates movable by a driving source along two rails, similarly to the ring slit shown in FIG.

The CPU 25 can control the movement of the ring slit, the illumination field stop, and the aperture stop. When the ring slit 6 having a large inner diameter is inserted into the optical path, the illumination field stop 8 having a large diameter is similarly controlled. Aperture stop 20 with large diameter
Is inserted into the optical path, and when the small-diameter ring slit 6 ′ is inserted into the optical path, the small-diameter illumination field stop 8 ′ and similarly the small-diameter aperture stop 20 ′ are inserted into the optical path. Switching is performed as described above.

The CPU 25 causes the strobe 3 to emit light in accordance with the operation of the shutter 26 and controls the return mirrors 14 and 17 to jump up. Further, the CPU 25 controls the editing and recording functions of the image editing and recording device 23.

In such a configuration, when the mydriatic state is relatively good, as shown in FIG. 1, the ring slit 6 having a large inner diameter, the illumination field stop 8 having a large diameter, and the aperture stop 20 having a large diameter are used. Are inserted in the optical path.
The ring slit 6 is illuminated by the lamp 1 through the condenser lenses 2 and 4 and the mirror 5, and the ring-shaped illumination light beam passing between the outer diameter and the inner diameter of the ring slit passes through the relay lens 7 and the illumination field stop 8. After passing through the relay lens 9 and being reflected by the perforated total reflection mirror 10, it is condensed on the pupil Ep by the objective lens 11,
r is illuminated almost uniformly.

The reflected light from the fundus Er passes through the center of the pupil Ep, is separated from the illumination light flux, passes through the objective lens 11 and the hole of the perforated total reflection mirror 10, and forms the focusing lens 12 and the image. After being reflected by the return mirror 14 via the lens 13, it is stopped down by the aperture stop 20, reaches the examiner S via the lens 16, the return mirror 17, and the eyepiece 18, and a fundus image is observed by the examiner.

When the alignment is achieved, the shutter 26 is pressed, the strobe 3 emits light, and the return mirror 1
4 retreats to the position shown by the dotted line, so that the fundus image is recorded on the film 15. When it is desired to take an image with the CCD camera 22, the return mirror 17 is moved to the position shown by the dotted line instead of the return mirror 14, whereby the fundus image is taken with the CCD camera 22. The photographed fundus image can be edited and recorded by the image editing and recording device 23, and can be displayed on the monitor 24.

On the other hand, if the mydriatic state of the eye to be examined is poor, or if the subject is a child, the pupil diameter of the eye to be examined becomes small. Insert the slit 6 'into the optical path. In conjunction with this, an illumination field stop 8 ′ having a small diameter is inserted into the optical path instead of the illumination field stop 8, and an aperture stop 20 ′ having a small diameter is inserted into the optical path instead of the aperture stop 20.

The use of the ring slit 6 'increases the amount of illumination from the ring slit, so that good fundus illumination can be obtained even when the mydriatic state is poor. Further, since the illumination field stop is slightly stopped down, the illumination field of the fundus is restricted, and the occurrence of flare or ghost in the peripheral portion can be prevented. Even in such a state, when the pupil diameter is small,
The peripheral portion of the fundus image to be observed or photographed still has a flare or ghost, resulting in a poor image and unreliability. However, since the aperture stop 20 'having a small diameter is used, as shown in FIG. 3A, the periphery of the fundus image 40 in a normal state (when the mydriatic state is good and the pupil diameter is large) is cut. A fundus image 41 is obtained,
A good image in which flare or ghost in the peripheral portion has been cut can be obtained.

Further, the same effect can be obtained by using the editing function of the image editing and recording device 23 without using the aperture stop 20 'and using the aperture stop 20 as it is. That is, as shown in FIG. 3B, the dotted line 42 can be inserted by using the superimpose function to display that the peripheral portion is not reliable. Alternatively, as shown in FIG. 3C, the image is edited so that the peripheral portion 43 is slightly darker than the dotted line 42,
The same image as the fundus image 41 shown in (A) can be obtained.

If an aperture stop 20 'is used in addition to such image editing, a good-quality fundus image from which flare or ghost in the peripheral portion has been cut can be reliably obtained.

The ring slit, the illumination field stop, and the aperture stop are prepared in two different diameters, and are not replaced by a slide type. A structure with a variable diameter may be used.

[0028]

As described above, according to the present invention, a fundus image of a highly reliable portion can be displayed at the time of observation and photographing at the time of a small pupil, so that the reliability of the fundus image is increased and an effective ophthalmologic diagnosis is made. A fundus camera can be provided.

[Brief description of the drawings]

FIG. 1 is an optical diagram showing an entire configuration of a fundus camera according to the present invention.

FIG. 2 is a perspective view showing a configuration of a ring slit.

FIG. 3 is an explanatory diagram showing a fundus image in a normal state and a small pupil.

[Explanation of symbols]

 6, 6 'ring slit 8, 8' illumination field stop 15 film 20, 20 'aperture stop 22 CCD camera

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroki Imamura 1-3-1 Shintoda, Hamamatsu-shi, Shizuoka Prefecture Inside the Hamamatsu Plant, Electrical Optics Division, Kowa Co., Ltd. (72) Koji Kobayashi 1-1-1, Shintoda, Hamamatsu-shi, Shizuoka Prefecture 3-1 Kowa Co., Ltd. Electro-Optics Division Hamamatsu Factory

Claims (5)

[Claims] 1. A fundus camera for observing or photographing a fundus illuminated via an illumination optical system via a photographing optical system, wherein an illumination optical system forms an annular illumination light beam at a position substantially conjugate with a pupil of an eye to be examined. A ring slit arranged in the system, an aperture stop arranged in the imaging optical system at a position substantially conjugate with the fundus of the eye to be examined in order to reduce reflected light from the eye to be examined, and an inner diameter of the ring slit is made variable. A fundus camera, comprising: means for changing the aperture diameter of the aperture stop according to a change in the inner diameter of the ring slit. 2. A fundus camera for observing or photographing a fundus illuminated via an illumination optical system via a photographing optical system, wherein an illumination optical system forms an annular illumination light beam at a position substantially conjugate with a pupil of an eye to be examined. A ring slit disposed in the system; a unit for varying the inner diameter of the ring slit; a unit for observing or imaging the fundus; and a fundus image observed or displayed according to a change in the inner diameter of the ring slit Means for restricting a display area of the fundus camera. 3. The illumination optical system according to claim 1, wherein an illumination field stop is disposed at a position substantially conjugate with the fundus in the illumination optical system, and the diameter of the illumination field stop is changed according to a change in the inner diameter of the ring slit. Or the fundus camera according to 2. 4. The fundus camera according to claim 1, wherein the aperture diameter of the aperture stop is reduced when the inner diameter of the ring slit is reduced. 5. The fundus camera according to claim 2, wherein when the inner diameter of the ring slit is reduced, the display area of the fundus image is limited so that the peripheral portion of the fundus image is not displayed.