JPS621724B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a non-mydriatic fundus camera for photographing the fundus of an examinee's eye in a semi-dark room, and the present invention is a non-mydriatic retinal camera for photographing the fundus of an examinee's eye in a semi-dark room. The present invention relates to a non-mydriatic fundus camera capable of fixing the line of sight of the eye to be examined during observation of the anterior segment of the eye to be examined.

Conventionally, non-mydriatic fundus cameras are known that present a fixation target to a subject during observation of the fundus of the subject's eye.

However, with conventional devices, when observing the anterior segment of the eye to perform rough alignment of the eye to be examined, the examinee does not know where to look in a semi-dark room and cannot fix the line of sight of the eye to be examined. It was not easy to align the eye to be examined. Furthermore, it takes time to observe the anterior segment of the eye, and it takes a considerable amount of time to complete alignment and take pictures.
Time was running out.

An object of the present invention is to provide a non-mydriatic fundus camera that eliminates the drawbacks of the conventional example.

An embodiment of the present invention is shown in FIG. 1 below.

In the figure, E is the subject's eye occupying a predetermined position, Ef is the fundus, and Ec is the cornea. 1 is an objective lens, 2 is an imaging lens, and 3 is a film. The objective lens 1 forms an image of the fundus Ef, and the imaging lens 2 forms an image of the fundus on the film 3. 4 is an incandescent light source, 5 is a condenser mirror, 6 is a condenser lens, 7 is an infrared filter that blocks the visible region and transmits the red light region, 8 is a strobe tube, 9 is a second condenser lens, 10
1 is an optical path refracting mirror; 11 is a slit plate having a ring-shaped aperture; the light beam emitted from the light source 4 and the strobe tube 8 is converged on the slit plate 11; 12 is a relay lens; 13 is a perforated mirror having a circular diaphragm hole; the mirror surface of the perforated mirror 13 is arranged to be conjugate with the slit plate 11 with respect to the relay lens 12; Further, the mirror surface of the perforated mirror 13 is set to be conjugate with the anterior part of the eye to be examined, for example, between the iris and the vertex of the cornea, with respect to the objective lens 1. Members 1 to 13 constitute a fundus illumination system. Reference numeral 14 denotes a flip-up mirror which is installed obliquely in the optical path when observing the fundus, and is removed out of the optical path when photographing the fundus. A field lens 15 is provided on the image plane of the imaging lens 2. 16 is an optical path refracting mirror, and 17 is an imaging lens. Reference numeral 18 denotes an image pickup tube that is sensitive to the infrared region. Further, the imaging lens 17 re-images the image formed by the imaging lens 2 on the light receiving surface of the imaging tube 18 . 19 is a monitor device, and 20 is a cathode ray tube. Monitor device 19
houses a circuit that processes a signal photoelectrically converted by the image pickup tube 18 and converts it into an image signal for a cathode ray tube.

The observation system for the fundus of the eye to be examined has been described above, and the observation system for the anterior segment of the eye to be examined will be described below.

In the figure, reference numeral 31 denotes a light guiding mirror that is inclined with respect to the optical axis and has a diameter smaller than the diameter of the photographing light beam, and is removed out of the optical path during photographing. Reference numeral 32 denotes an oblique semi-transparent mirror, 33 an imaging lens, and 34 another imaging tube.
and is conjugate with respect to the imaging lens 33. 35
36 is a monitor device, and 36 is a cathode ray tube. The monitor devices 19 and 35 are arranged adjacent to each other so that an image of the fundus of the eye and an image of the anterior segment of the eye can be observed at the same time.

On the other hand, 37 is a converging lens, and 38 is a light emitting diode that emits weak light for an index, which functions as a so-called fixation target. This light emitting diode 38 can freely move within a plane perpendicular to the optical axis. Further, in this embodiment, the focus of the fundus of the subject's eye is adjusted by moving the imaging lens 2, and the converging lens 37 and the imaging lens 2 are linked to
and the fundus Ef and film surface 3 regarding the imaging lens 2
The relationship is maintained to be equal to the relationship between the fundus Ef and the light emitting diode 38 with respect to the objective lens 1 and the converging lens 37. That is, the light emitting diode 38 is in a conjugate position with the fundus Ef. Therefore, when the fundus camera is focused on the fundus, the subject clearly sees the light emitting diode 38.

With the above configuration, when the light source 4 is turned on, an image of the fundus of the eye is reflected on the cathode ray tube 20, and an image of the anterior segment of the eye is reflected on the cathode ray tube 36. The operator observes the image of the anterior segment of the eye and roughly aligns the working distance and the objective lens with the eye to be examined. Furthermore, the fundus image is observed to perform focus adjustment and fine positioning to prevent flare. Note that the photographic field of view can be determined by setting the light emitting diode 38 at an appropriate position and guiding the line of sight of the eye to be examined. Then, after confirming that the focus adjustment and positioning adjustment are good, a photograph is taken by firing the strobe tube.

Here, the light guide mirror 31 is removed out of the optical path when photographing the fundus, but it remains within the optical path before photographing, and when observing the anterior segment of the eye, the light emitting diode 38 can be viewed by the subject's eye while observing the anterior segment of the eye. Furthermore, since the diameter of the light guiding line 31 is smaller than the diameter of the photographing light beam, the light guiding mirror 31 allows the light emitting diode 38 to be seen by the subject's eye during fundus observation.
The fundus can be observed using the light beam that passes through the periphery.

Note that since the examiner generally observes a monitor, the light emitting diode 38 is not visible to the examiner but only to the subject. Note that the light emitting diode is not visible to the examiner through the oblique semi-transparent mirror 32.

By the way, in the above configuration, the infrared filter 7 is removed and the light intensity of the light source 4 is reduced to such an extent that the light from this light source does not contract the pupil of the subject's eye, that is, it becomes substantially invisible light, and the image pickup tube 18 is It may be replaced with an ultra-high sensitivity image pickup tube that combines an image intensity fire and a vidicon.

As described above, according to the present invention, it is possible to fix the line of sight of the eye to be examined during observation of the anterior segment of the eye to be examined, thereby facilitating rough alignment before fine alignment of the eye to be examined. As a result, it is possible to shorten the time required to complete fine alignment with the eye to be examined and to take an image.

In addition, when observing the anterior segment of the eye, the fixation target inside the device is presented not to the eye opposite to the eye to be examined, but to the eye to be examined, as is the case when observing the fundus. In contrast, even if the subject has strabismus, the line of sight of the subject's eye can be quickly determined. Furthermore, when determining the line of sight during anterior segment observation, the fixation target becomes a hindrance to the examiner because it is not visible to the examiner who is observing the image of the subject's eye, but is visible only to the examinee. There is no such thing.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention. In the figure, 1 is an objective lens, 2 is an imaging lens, 3 is a film, 7 is an infrared filter, 18 is an imaging tube,
31 is a light guide, 34 is an imaging tube, 37 is a converging lens, and 38 is a light emitting diode.

Claims (1)

[Scope of Claims] 1. A fixation target provided inside the device is presented to the eye to be examined, the line of sight is fixed, and the fundus is observed using invisible light, and fine positioning with the eye to be examined and focus adjustment by a focus adjustment system are performed. In a non-mydriatic retinal camera that photographs the fundus after the eye is photographed, there is an anterior segment observation system installed inside the device for rough alignment with the eye to be examined; A non-mydriatic fundus camera comprising a fixation target projection system that projects a fixation target provided at a substantially conjugate position with the fundus of the eye to be examined only onto the fundus of the eye to be examined in an optical path branched from the eye. 2. The non-mydriatic fundus camera according to claim 1, wherein the fixation target provided in the optical path of the anterior segment observation system is movable in a direction perpendicular to the optical axis.