JPS6290133A - Eyeground camera having fixed sight target - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fundus camera having a fixation target for guiding the line of sight of an eye to be examined.

When observing and photographing the fundus of the subject's eye, it is not possible to observe and photograph the entire area of the fundus at once, so the necessary part of the fundus must be selected. To do this, a fixation target must be set and the eye must be photographed. By guiding the line of sight, the direction of the visual field is changed and the required part of the fundus is selected. Conventionally, as a means for this, a freely movable miniature lamp was provided on the subject's forehead rest of the LFF+ bottom camera, and the examiner moved this miniature lamp to change the subject's line of sight. In this way, when the fixation target is provided outside the fundus camera device and is located near the forehead rest, operations are complicated and observation and photography become difficult. In addition, the examinee must view this fixation target with the eye opposite to the eye being examined, so if the examinee is strabismus, the observer must rely entirely on intuition, making it extremely difficult to use. It is. Furthermore, since the fixation target is provided near the subject's eye, there are drawbacks such as the inability to accurately determine the line of sight when photographing the dominant eye.

The purpose of the present invention is to provide a fundus camera that has improved the above-mentioned drawbacks. A visual goal is set. This fixation target is made up of a plurality of objects and is used in a fixed state 7 (2).In the present invention, the fixation target can be observed by the examiner, who is the observer, so that the observer can It is possible to directly confirm the fixation position of the eye to be examined.The present invention will be described in detail below.

FIG. 1 is a schematic diagram showing an embodiment of the optical system of the fundus camera according to the present invention, and is a so-called non-mydriatic type fundus camera that uses infrared light to observe the eye to be examined and uses visible light to photograph the eye. It shows. In FIG. 1, a light beam emitted from a light source l such as a tungsten lamp, including a portion of the light beam reflected by a reflecting mirror 2, passes through a filter 3 and is imaged onto a strobe tube 5 by a condenser lens 4. The filter 3 is a filter that allows light in the infrared region to pass through and reflects light in other regions.
The light beam that passes through and is imaged on the strobe tube 5 is an infrared light beam. The infrared light beam is imaged onto the ring slit 7 by the condenser lens 6, and the image of the ring slit 7 is formed near the perforated mirror 9 by the relay lens 8. The infrared light beam reflected by the perforated mirror 9 forms a ring slit image again near the cornea 11a of the eye 11 to be examined by the objective lens 10, and illuminates the fundus Ef of the eye to be examined. On the other hand, the light emitted from the fundus once forms an intermediate image of the fundus Ef with the objective lens 10, passes through the hole 9a of the perforated mirror 9, and is transferred to the reversing mirror 13 by the photographing lens 12 so that it is almost optically aligned with the film surface 14. A fundus image is formed on a field lens 15 provided at a conjugate position. The infrared light flux from the field lens 15 is reflected by a filter 16 that reflects the light flux in the infrared region and transmits the light flux in the visible region, and is imaged on the imaging tube 18 by the relay lens 17. Furthermore, image pickup tube 1
The fundus image projected onto 8 is monitored using visual conversion means. On the other hand, a fixation chart 20 is provided at a position where the infrared light beam would be imaged by the relay lens 19 if the filter 16 was not provided.

Therefore, the fixation chart 20 and the imaging surface of the imaging tube 18 are located at optically conjugate positions with respect to the filter 16. A light source 21 such as a light emitting diode is provided behind the fixation chart 20, and the light source 21 illuminates the fixation chart. Since this fixation chart 20 is located at a position conjugate with the fundus position with respect to the entire optical system, the light flux from the fixation chart 20 is transmitted through the relay lens 19, filter 16,
Field lens 15, reversing mirror 13, photographing lens 1
2. An image is formed on the fundus of the eye to be examined via the perforated mirror 9 and the objective lens 10. Therefore, the subject can clearly fixate the image of this chart. FIG. 2 shows an example of the fixation chart 20. In fundus photography, which is usually carried out in group medical examinations, the part of the fundus to be photographed is almost determined in advance, so the corresponding fixation target 23 is placed on the opaque plate 2.
A plurality of them are provided on 2. For example, for the right eye and left eye, the left and right fixation targets 23 are used, and in order to widen the fundus imaging field, four fixation targets 23 can be used sequentially. After making the selection, the strobe tube 5 is turned on and at the same time the reversing mirror 13 is flipped up to photograph the fundus of the eye.

In the embodiment shown in FIG. 1, if the positions of the monitor system and the fixation chart imaging system are interchanged with respect to the filter 16, the filter 16 may include a filter that transmits infrared light flux and reflects visible light flux. Use. Moreover, it is also possible to use a half mirror in place of the filter 16.

In the above-mentioned fundus camera having a fixation target, the observer cannot directly confirm the position of the fixation target. FIG. 3 shows an example in which the observer can also monitor the position of the fixation target at the same time. This is a partial schematic diagram of the finder system of the fundus camera. Hereinafter, in the embodiments of this specification, members denoted by the same numbers as in the optical system shown in FIG. 1 represent the same members. In FIG. 3, the image pickup tube 18
A position where the imaging surface is conjugate with respect to the relay lens 17 is found behind the filter 16, and a fixation chart 24 and a light source 25 are provided at that position. a conjugate position that the fixation chart 20 makes with respect to the filter 16 on the imaging surface of the imaging tube 18;
Set each chart 20.24 so that the conjugate positions formed by the fixation chart 24 on the imaging surface of the image pickup tube 18 with respect to the relay lens 17 correspond.2 When moving the fixation chart, the fixation chart 20 and the fixation chart are always set. The charts 20 and 24 are moved in conjunction so that the conjugate positions of the charts 24 correspond. In the deceptive configuration, the position of the fixation chart 24 can be photographed with an imaging tube, making it possible to directly grasp the fixation position of the eye to be examined.

FIG. 4 is a partial schematic diagram of an optical system of a fundus camera showing another embodiment. A fixation target plate 26 having a fixation target 27 is located at a position where a fundus image of the subject's eye is formed within the finder optical system by a photographing lens, that is, a film 1 with respect to the reversing mirror 13.
Provided at a position conjugate with 4. This fixation target board 26 is, for example, as shown in FIG. 5, on which a plurality of fixation targets 27 made of light sources such as light emitting diodes are attached to a transparent glass plate, and is lit by an external power source through a lead wire 28. It is. Note that since a transparent electrode can be used for the lead &128, nothing other than the fixation target 27 of the fixation target plate 26 will interfere with observation.

When the fixation target is installed in the observation optical system in this way, the target position is shown on the monitor at the same time as the fundus image of the eye to be examined, using the shadow of the fixation target or the bright spot of the fixation target. The viewing direction can be grasped directly.

In the embodiments described so far, the fixation target is directly or indirectly incorporated into the finder optical path of the tHt sensing optical system, that is, the optical path between the reversing mirror 13 and the image pickup tube 18. It is possible to provide it indirectly in the optical path between the mirror and the reversing mirror 13. FIG. 6 shows a partial schematic diagram of an embodiment in which the lens is indirectly incorporated into the optical path between the photographing lens 12 and the reversing mirror 13. 29 in FIG. It is a reflective filter or a simple half mirror, and as described above, the fixation chart 20 is located at a position optically conjugate with the fundus of the eye to be examined.

In addition, in order to prevent the light beam for photographing from being kicked or reduced during imaging, the fixation target or the reflective member that guides the fixation target into the observation optical system is used in a fixed state. The target may be provided in the finder optical path between the reversing mirror 13 and the image pickup tube 18.

As described above, in the fundus camera of the present invention, a plurality of fixation targets are provided at positions optically conjugate with the fundus of the subject's eye, and the direction of the subject's line of sight is guided by the fixation targets. It is possible to accurately guide the line of sight of the eye to be examined, can be compactly incorporated into the optical system of the fundus camera, and is easy to operate.Also, since the fixation target is not within the optical path of the illumination optical system that illuminates the eye to be examined, When the fixation target moves, the eye moves and the iris reflects the ring illumination light flux, so the brightness of the fixation target projected together with the ring illumination light flux does not change, and furthermore, the fixation target is photographed together with the fundus of the examined eye. Of the fundus image information,
It is possible to prevent omissions in the portion where the fixation target is imaged, and has superior effects compared to conventional fundus cameras. Furthermore, it is also possible for the observer to directly confirm the fixation position of the subject's eye, and this is highly likely.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an optical system of a fundus camera showing an embodiment of the present invention, and FIG. 2 is a diagram showing a fixation chart according to the present invention.
3 and 4 are partial schematic diagrams of an optical system of a fundus camera showing another embodiment of the present invention, and FIG. 5 is a partial schematic diagram of an optical system of a fundus camera according to another embodiment of the present invention. FIG. 2 is a partial schematic diagram of an optical system of a fundus camera showing another embodiment of the present invention. 18... Image pickup tube, 20.24... Fixation chart, 21.25... Light emitting diode, 2
2...Translucent plate, 23.27...Fixation target, 26...Fixation target board. Patent applicant: Canon Co., Ltd. (and 1 other person) C-ream Figure 3

Claims (1)

[Claims] 1. An illumination optical system equipped with invisible light illumination means for observing the fundus of the eye to be examined, a photographing optical system for photographing the fundus of the eye to be examined, and an observation optical system for allowing an observer to observe the fundus. The fundus camera is characterized by comprising a plurality of fixation targets for guiding the line of sight of the eye to be examined at positions that are outside the optical path of the illumination optical system and are approximately optically conjugate with the fundus of the eye to be examined. Fundus camera with fixation target.