JPS61185246A - Eyeground camera - 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 [Industrial Application Field] The present invention relates to a fundus camera that can be easily aligned with the anterior segment of an eye to be examined.

[Prior art] When using a fundus camera, it is necessary to align the optical axis of the objective lens with the center of the pupil of the eye to be examined and maintain an appropriate distance. The examiner watches from outside the camera to see what happens when the illumination light enters the eye through the objective lens and enters the eye. However, the examiner has to lean forward and look into the camera, which is inconvenient, and when the distance between the eye to be examined and the objective lens is short, it is extremely difficult to see through the camera.

As a solution to such inconveniences, the present applicant has already proposed the invention described in Japanese Patent Application Laid-Open No. 18534/1983. To explain this proposal according to FIG. 5, illumination light from an illumination system (not shown) is reflected by a perforated mirror l, travels to the left, and enters the eye E through the objective lens 2 facing the eye E. It looks like this. The light flux reflected by the fundus Ef of the eye E to be examined passes through the objective lens 2 to the right, passes through the perforated mirror 1, and passes through the relay lens 3 provided behind it.
It is configured so that the image is formed on the film surface 4 via the. A movable mirror 5 that can be raised and lowered is provided between the relay lens 3 and the film surface 4. When the movable mirror 5 is inserted into the optical path, the reflected light is reflected upward and the optical path deflection mirror 6 It reaches the finder eyepiece lens 7 via.

To explain in more detail the imaging relationship between the fundus Ef76 and the pupil Ep in this optical system for fundus observation/photography, Fig. 5(a)
, the illumination light from the illumination system forms an image of the light source on the center part 1a of the perforated nasal mirror 1, and then passes through the objective lens 2 to form an image on the pupil Ep plane of the eye E to be examined, illuminating the fundus Ef. do. When the device is in the proper position with respect to the eye E, the pupil Ep
is imaged by the objective lens 2 onto the center portion 1a of the perforated mirror 1. The examiner focuses the image of the fundus Ef formed at the rear focal plane position Pi of the objective lens 2 onto the film plane 4 using the relay lens 3. At that time, the movable mirror 5
is inserted into the optical path, the light beam that should be incident on the film surface 4 is reflected upward by the movable mirror 5, and after being further reflected by the mirror 6, a fundus image is formed at a position P2 equidistant from the film surface 4. This can be observed through the eyepiece 7.

An auxiliary lens 8 is placed between the objective lens 2 and the perforated mirror l.
The auxiliary lens 8 is removably installed in the optical path, and when observing the anterior segment of the eye, the auxiliary lens 8 can be inserted into the optical path as shown in FIG. 5(b). The image of the pupil Ep is formed at the same position PI' as the position P1 where the image of the fundus Ef is formed. The pupil image focused at position PI' is observed by the examiner through the eyepiece 7, as in the case in FIG. 5(a). Therefore, first insert the auxiliary lens 8 into the optical path, and then
Align the top, bottom, left and right of the pupil Ep, and then adjust the auxiliary lens 8.
is removed from the optical path, the fundus Ef is observed using the same eyepiece lens 7, and the movable mirror 5 is removed from the optical path to proceed to photographing on the film surface 4.

With the above procedure, it is easy to align the optical axis of the objective lens 2 vertically and horizontally, but sufficient information is needed to guide the device to the appropriate distance to the eye E, that is, to adjust the working distance. While observing the image of the fundus Ef, the examiner must move the device back and forth in order to search for an appropriate working distance that will not cause flare or the like to be mixed into the fundus image. This is because the pupil Ep is observed through a small opening at the center 1a of the perforated mirror 1, resulting in a deep depth of field, making it difficult to judge the appropriate working distance based on the degree of blur in the pupil image. be.

In addition, since the relay lens 3 has the function of focusing the fundus Ef on the film plane 4, which is the original purpose, there is no guarantee that the pupil Ep will be in focus at the appropriate working distance. In addition, ophthalmological devices such as fundus cameras usually use a single adjustable rod to adjust the front and back, up and down, and left and right directions. The alignment also became distorted, and I looked at the anterior segment of the eye again.
It has the disadvantage that seven alignment adjustments must be made on the bottom, left and right sides.

[Object of the Invention] An object of the present invention is to provide a fundus camera having an optical system for observing the anterior segment of the eye that can easily determine the appropriate working distance.

[Summary of the Invention] The gist of the present invention for achieving the above object is to include a first optical system for observing the anterior segment of the eye to be examined in order to align the eye to be examined; Sharing at least a part of the second optical system for observing or photographing the fundus of the eye for optometry,
The fundus camera is characterized in that an image splitting prism is provided in the optical path of the optical system and at a position independent of the second optical system.

[Embodiments of the Invention] The present invention will be described in detail based on embodiments illustrated in FIGS. 1 to 4.

In FIG. 1, the perforated mirror l, objective lens 2, relay lens 3, film surface 4, and movable mirror 5 are the constituent elements of the fundus camera shown in FIG. 5, and the auxiliary lens 8 is also shown in FIG. Similarly, the auxiliary lens 8 is provided so as to be freely inserted and removed in the optical path of the objective lens 2, and the function of this auxiliary lens 8 allows the examiner to observe the fundus Ef and pupil Ep of the eye E to be examined by switching between them. .

In this embodiment, instead of the eyepiece lens 7 on the reflective side of the movable mirror 5, a field lens 9, a relay lens 10. It has a television viewing optical system consisting of a television camera 11 and a television monitor 12. A field lens 8a having an image splitting prism 8b as shown in FIG. It can be inserted and removed into the optical path.

When the auxiliary lens 8 is inserted into the optical path and the anterior segment of the eye is observed, if the device is at an appropriate working distance, the image of the pupil Ep will match on the image split prism 8b, and the image on the television monitor 12 will be visible. As shown in FIG. 3(a), the pupil Ep
and the iris Ea appears undivided. Next, if the working distance is not appropriate, the above-mentioned conjugate relationship collapses, and the image of the pupil Ep is formed either before or after the image splitting prism 8b, which on the television monitor 12 is shown in FIG. 3(b). As shown, the pupil Ep and iris Ea are observed in a divided state.

That is, it is understood that in order to obtain a proper working distance, the adjustment should be made from the state shown in FIG. 3(b) to the state shown in FIG. 3(a). Also, at this time, the center of the pupil Ep should be placed on the TV monitor 12.
Needless to say, if the alignment is made to coincide with the center of , seven alignments below, left and right can be performed at the same time.

By the way, the relay lens 3 has a function of adjusting the focus of the fundus image Ef on the film surface 4 according to the power of refractive error of the eye E to be examined, as described above. However, the image split prism 8b is more important than the objective lens 2 than the relay lens 3.
Since it is placed on the side, the working distance can be detected independently without being affected by the vEp division state. Furthermore, the anterior segment observation optical system can be used in common for fundus observation or photographing, which has the advantage that the entire apparatus can be made compact. When observing the fundus Ef, the image split prism 8b is arranged independently from the optical system for fundus observation so that it retreats from the optical path together with the auxiliary lens 8. 8b has no negative effect.

In the example shown in FIG. Alternatively, the target image projected toward the eye E may be used by changing its position. FIG. 4 is an example in which an image of a target image having three optical images provided for illuminating the anterior segment of the eye reflected by the cornea of the eye E to be examined is used. In this case, it goes without saying that the position of the image splitting prism 8b in FIG. 1 should be selected to be conjugate with the above-mentioned reflected image when the device is at a proper working distance. FIG. 4(a) shows the device at the proper working distance, and the three light images represent an equilateral triangle. FIG. 4(b) shows a case where the working distance is inappropriate, and the three optical images are distorted triangles.

The optotype projected towards the eye E to be examined may have any shape, but it is desirable to have a shape that makes it easy to distinguish -L downward and left/right positional deviations.

[Effects of the Invention] As explained above, the fundus camera according to the present invention has a simple structure in which an image splitting prism is arranged in the optical path of the optical system for observing the anterior segment of the eye, so that the position of the eye to be examined can be adjusted vertically and horizontally. Not only this, but also the working distance, which is the longitudinal direction, can be easily determined. In addition, by locating the image split prism independently of the optical system for fundus observation or photography, it is possible to avoid any negative effects during fundus observation, and it is also closer to the objective lens than the optical system that focuses the eye image. By arranging an image split prism, the working distance can be determined without depending on the state of focus adjustment, and the anterior segment observation optical system and the fundus observation or photography optical system share a considerable amount of optical system parts. becomes possible.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the fundus camera according to the present invention, in which FIG. 1 is an optical configuration diagram of the fundus camera, FIG. 2 is a perspective view of an image split prism, and FIG. FIG. 4 is an explanatory diagram of the operation of the embodiment shown in the figure, FIG. 4 is an explanatory diagram of the operation of another embodiment, and FIG. 5 is an optical configuration diagram of a conventional fundus camera. Symbol l is a mirror with a hole, 2 is an objective lens, 3 is a relay lens, 4 is a film surface, 5 is a movable mirror, 8 is an auxiliary lens, 8a is a field lens, 8b is an image split prism, 11 is a television camera, 12 is a It's a TV monitor.

Claims (1)

[Claims] 1. A first optical system for observing the anterior segment of the eye to be examined in order to align the eye to be examined, and a second optical system for observing or photographing the fundus of the eye to be examined. A fundus camera, characterized in that at least a part of the optical system is shared, and an image splitting prism is provided at a position in the optical path of the first optical system and independent of the second optical system. 2. The fundus camera according to claim 1, wherein the image splitting prism is in a position conjugate with the pupil of the eye to be examined when the device is in an appropriate position relative to the eye to be examined. 3. Claim 1, wherein when the device is at an appropriate position with respect to the eye to be examined, the image splitting prism is at a position conjugate with the corneal reflected image of the optotype projected onto the eye to be examined. The fundus camera described in . 4. The second optical system consists of an objective lens facing the eye to be examined, and a relay lens that re-images the image of the eye to be examined by the objective lens, and the relay lens adjusts the focus of the fundus image of the eye to be examined. The first optical system shares the objective lens and the relay lens with the second optical system, and when the first optical system is operated, the The fundus camera according to claim 1, wherein an image splitting prism is inserted.