JPH05317264A - Fundus camera - Google Patents

Abstract

PURPOSE:To prevent the contrast of a pattern from dropping due to light scattering of the retina at the time of measuring ruggedness of an eye ground by providing polarizing plates whose polarization directions are equal in a projection optical system and an image pickup optical system, respectively. CONSTITUTION:When a measurement switch is depressed after alignment focusing is completed, an electronic flash tube 35 emits light and a projection pattern 31 is projected onto an eye ground Ef. This pattern image is formed on CCD imager 39, but a scattered light in a reflected light by the surface layer of the eye ground Ef is shielded by an operation of polarizing plates 33, 37, and formed by only a regularly reflected luminous flux. Subsequently, a projection pattern image on the eye ground Ef photographed through the CCD imager 39 and a CCD camera 40 is stored temporarily in a frame memory 42. next, when light from an illuminating light source 20 is cut off by a shutter 21, and the electronic flash tube 35 is allowed to emit light by synchronizing with a timing of the CCD camera 40, a color eye ground image is photographed by the CCD camera 40, and stored temporarily in the frame memory 42.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus camera for photographing a fundus of an eye to be examined.

[0002]

2. Description of the Related Art It is useful for diagnosing glaucoma to measure unevenness of the fundus of the eye to be examined, particularly to measure the depressed state of the papilla. Conventionally, a special stereoscopic fundus camera is used for this purpose, but for quantitative evaluation, stereoscopic photography must be analyzed using photogrammetry. For the purpose of quantitative evaluation only, it is known that the lattice fringes are projected onto the fundus of the eye to be examined, the lattice fringes are photographed, the degree of bending of the lattice is measured, and the amount of depression is obtained.

Furthermore, the fixation state test is used, for example, to determine the distance between the fundus hemorrhage site and the fixation point, and to determine whether photocoagulation treatment is possible for this fundus hemorrhage.

FIG. 11 shows a fixation device of a conventional non-mydriasis type fundus camera. An optical path from an observation light source 1 made of a tungsten lamp to an eye E to be inspected is passed through a condenser lens 2 and visible light to transmit infrared rays. A dichroic mirror 3 that reflects light, a ring slit plate 4 having a ring-shaped opening 4a, a relay lens 5, a perforated mirror 6, and an objective lens 7 are arranged. A condenser lens 8 and a photographing light source 9 are arranged in the transmission direction of the dichroic mirror 3. In the transmission direction behind the perforated mirror 5, a taking lens 10, a flip-up mirror 11, and a film 12 are arranged. Further, a field lens 13, a half mirror 14, a relay lens 15, and an image pickup tube 16 are provided in the reflection direction of the flip-up mirror 11, and the output of the image pickup tube 16 is connected to a television monitor 17. Behind the half mirror 14, a minute LED 19 is provided at a position conjugate with the taking lens 18 and the film 12.

The light flux from the observation light source 1 is reflected by the condenser lens 2 and the dichroic mirror 3, passes through the ring slit plate 4, is focused through the relay lens 5 near the perforated mirror 6, and then is reflected. Then, the objective lens 7 re-images in the vicinity of the cornea of the eye E and illuminates the fundus Ef. Then, the reflected light from the fundus oculi Ef travels to the right and is imaged by the objective lens 7, then passes through the hole of the perforated mirror 6, passes through the taking lens 10 and the flip-up mirror 11, and is imaged near the field lens 13. , Half mirror 1
4, the image is formed on the image receiving surface of the image pickup tube 16 through the relay lens 15, and is displayed on the television monitor 17 as a fundus image Ea.

In the case of taking a picture, the photographing light source 9 emits light, and the luminous flux emitted from the photographing light source 9 passes through the condenser lens 8 and the dichroic mirror 3 and passes through the same optical path as the above observation light to be examined. Illuminate fundus Ef of E. Then, the reflected light from the fundus Ef passes through the objective lens 7 and the hole of the perforated mirror 6, and then is imaged and recorded on the film 12 by the taking lens 10. During this photographing, the flip-up mirror 11 jumps up in synchronization with a shutter (not shown) provided in front of the film 12 and retracts from the optical path.

Further, the luminous flux emitted from the LED 19 goes counter to the observation luminous flux and reaches the fundus Ef of the eye E to be examined. Also, LE
D19 is designed so that it can move freely on a plane perpendicular to the optical axis as shown by the arrow, and
By matching the line of sight with the light flux of the ED 19, the fundus Ef
You can shoot any position of. This is a so-called light-projecting type internal fixation device. The LED 19 is always focused on the fundus due to the focusing action of the photographing lens 10.
Since the image is formed on Ef, reliable fixation is possible.

The image of the LED 19 is partially reflected by the dichroic film formed on one surface of the field lens 13, then reflected by the half mirror 14, and guided to the image pickup tube 16 by the relay lens 15. TV monitor 17
In the above, this light flux is observed as being combined with the fundus image Ea as the brightness Pa, and the state of fixation of the eye E can be recognized well.

Although the near infrared light is used as the illumination light in the above description, the internal fixation device in the non-mydriasis type fundus camera that illuminates the fundus Ef with visible light and directly observes is the illumination optical system in FIG. Usually, a method is adopted in which an opaque fixation target is placed on a plane conjugate with the fundus oculi Ef between the ring slit plate 4 and the relay lens 5 of the system, and the shadow thereof is projected onto the fundus oculi Ef of the eye E to be examined. Is.

Further, when the mydriasis type fundus camera is used, the dichroic mirror 3 shown in FIG. 11 is replaced with a half mirror, and the television observation system is replaced with a viewfinder. In this case, since the shadow of the fixation target is recorded so as to be superimposed on the captured fundus image, it is possible to confirm at which part on the fundus Ef the eye E is fixed.

[0011]

However, when a two-dimensional pattern such as a grid pattern is projected on the fundus using a fundus camera to measure the unevenness of the fundus, the retinal pattern such as a defect becomes noise, The degree of light scattering on the retina is strong and it is difficult to accurately extract a two-dimensional pattern. Regarding the removal of retinal pattern noise, JP-A-63-63
No. 24222 proposes a solution to the problem, but no effective means has been found for removing the influence of light scattering on the retina.

Further, when the fixation state inspection is performed by the fundus camera, (1) when the non-mydriasis type fundus camera is used, it is used only for guiding the internal fixation target eye and the fixation point cannot be recorded in the photograph. , (2) When using a mydriasis type fundus camera, the internal fixation target is recorded as a shadow in the photograph of the fundus image, so a complete fundus image cannot be obtained, and the fixation target is not visible. There is a problem that you have to shoot separately.

A first object of the present invention is to provide a fundus camera for measuring the unevenness of the fundus so as to prevent deterioration of the contrast of the pattern due to light scattering of the retina. A second object of the present invention is to provide a fundus camera capable of obtaining a clear fundus image in which a fixation point is recorded in a fixation state inspection.

[0014]

A fundus camera according to a first aspect of the invention for achieving the above object is a first fundus camera on a pupil of an eye to be examined.
A projection optical system for projecting a two-dimensional projection pattern onto the fundus of the eye to be inspected from the region, and an imaging optical system for capturing a reflection image of the projection pattern from the second region deviated from the first region. A fundus camera having a computing means for calculating a three-dimensional shape of the fundus from a projection pattern image taken by the imaging optical system, wherein the projection optical system and the imaging optical system are provided with polarizing plates having the same polarization direction. It is characterized by.

Further, a fundus camera according to a second aspect of the present invention is an illumination optical system for illuminating a fundus of an eye to be examined, an imaging optical system for imaging the illuminated fundus of the eye, and the fundus of the fundus imaged by the imaging optical system. In a fundus camera having a projection means for projecting a fixation target on the fundus for guiding the line of sight of the eye to select a region, the position of the fixation target on a plane perpendicular to the optical axis of the fixation target. Means for recording information together with the fundus image.

[0016]

The fundus camera according to the first aspect of the present invention having the above-described structure uses two polarizing plates when measuring the unevenness of the fundus.
Observe and record only the specular component of the reflected light at the fundus. Further, the fundus camera according to the second invention detects the position of the fixation target on the fundus when performing the fixation state inspection, and observes and records the fundus image together with the position information.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. 1 to 4 show a first embodiment,
FIG. 1 is a block diagram of a fundus camera for measuring unevenness of the fundus. On the optical path from the illumination light source 20 to the eye E to be inspected, a shutter 21, an infrared filter 22, a lens 23, a strobe tube 24, an eccentric diaphragm 25, a lens 2 which can be retracted from the optical path.
6, half mirror 27, lens 28, pupil division mirror 2
9. The objective lens 30 is sequentially arranged. On the reflection side of the half mirror 27, a projection pattern 31, which is composed of lattice stripes having a density of 1.0, a lens 32, a polarizing plate 33, a diaphragm 34,
Strobe tubes 35 are arranged. A CCD imager 3 including a decentering diaphragm 36, a polarizing plate 37, a lens 38, and a color image tube is provided on the optical path on the right side of the pupil division mirror 29.
9. A CCD camera 40 is arranged. Here, the eccentric diaphragms 25 and 36 are conjugate with the pupil Ep, and the projection pattern 31 is substantially conjugate with the fundus Er.

The projection pattern 31 is mechanically linked to the CCD imager 39, and the output of the CCD imager 39 is output to the controller 4 via the output section of the CCD camera 40.
It is connected to 1. The controller 41 is also connected to the frame memory 42, the television monitor 43, and the image processing circuit 44. Openings 25a, 3 of the eccentric diaphragms 25, 36
As shown in FIG. 2, 6a is arranged at a position on the pupil Ep of the eye E to be eccentric so that the openings 25a and 35a are separated by a predetermined distance. Further, the eccentric diaphragm 36 is provided on the optical axis of the front focus position of the lens 38, and the imaging optical system constitutes a so-called telecentric system, and at the same time, the aperture diaphragm 3 is provided.
Reference numeral 4 is arranged at the focal position on the rear side of the lens 32 and is a telecentric system with respect to the projection pattern 31.

When viewed from the direction C in FIG. 1, the lenses 38 and 28 are respectively provided with eccentric diaphragms 36 and 28, as shown in FIG.
An optical axis is provided on the center of 25 to make the telecentric system strict. The polarization directions of the polarization plates 33 and 37 are the same, for example, the directions shown by the arrows in FIG.

Light emitted from the illumination light source 20 is converted into near-infrared light by an infrared filter 22 that transmits only near-infrared light, and then passes through a lens 23, a strobe tube 24, and an eccentric diaphragm 25 to divide a pupil. Fundus via mirror 29 and objective lens 30
Illuminate Er. The reflected light from the fundus Er is the objective lens 3
0, the pupil division mirror 29, the eccentric diaphragm 36, and the lens 3
A fundus image is formed on a CCD imager 39 which is also sensitive to near infrared light by means of 8. This fundus image is captured by the CCD camera 40 and becomes an electronic image on the television monitor 43 via the controller 41. The examiner aligns and focuses the device while observing this image. C
Since the CD imager 39 is moved back and forth to perform focusing, in this apparatus having a telecentric system, the size of the fundus image formed on the CCD imager 39 does not change even if focusing is performed.

After the alignment focusing is completed, when the examiner presses a measurement switch (not shown), the strobe tube 35 emits light and the projection pattern 31 is projected on the fundus Er. Although this pattern image is formed on the CCD imager 39, the scattered light of the reflected light on the surface layer of the fundus Er is blocked by the action of the polarizing plates 33 and 37, and is formed by only the specularly reflected light flux. Therefore, the pattern image on the CCD imager 39 has a higher contrast than before. CC
The projection pattern image on the fundus Er captured by the D imager 39 and the CCD camera 40 is temporarily stored in the frame memory 42.

Next, the light from the illumination light source 20 is irradiated with light from the shutter 2.
When the flash tube 35 is turned off in synchronization with the timing of the CCD camera 40, the CCD camera 4
A color fundus image is captured at 0 and temporarily stored in the frame memory 42. That is, the pattern image on the fundus Er and the color fundus image are stored substantially simultaneously in the frame memory 42 by one measurement operation.

The position of each grid of the projection pattern 31 is shown in FIG.
Due to the action of the eccentric diaphragms 25 and 36 shown in FIG. Therefore, it is possible to calculate the amount of unevenness at that point by detecting the interval of each grid by using the means of Japanese Patent Laid-Open No. 63-22222. The image processing circuit 44 performs this processing on the grid of the projection pattern 31 stored in the frame memory 42 and calculates the three-dimensional shape of the fundus Er.
Further, since which part of the color fundus image corresponds to these grids can be managed by the address of the frame memory 42, the controller 41 assigns the grids after the completion of this image processing, and then, as shown in FIG. The two-dimensional fundus image having the contour line h shown in a) or the three-dimensional image of the fundus Er shown in FIG. 4B is output to the television monitor 43.

In this embodiment, the lattice spacing is measured only from the lattice image, but as described above, in order to reduce the noise due to the retinal pattern of blood vessels, etc.
You may use together the method of 3-24222. Also,
A method of performing inter-image calculation such as subtraction of the lattice image and the fundus image is also effective. Furthermore, the pattern to be projected is not limited to the lattice fringe, and a two-dimensional pattern composed of a plurality of discrete points can be used.

FIGS. 5 to 9 show the second embodiment, and FIG. 5 is a configuration diagram when applied to a non-mydriasis type fundus camera. The same members as those of the fundus camera of FIG. 11 described in the related art are designated by the same reference numerals. The condenser lens 2, the dichroic mirror 3, the ring slit plate 4, the relay lens 5, the perforated mirror 6, and the objective lens 7 are arranged on the optical path from the observation light source 1 to the eye E to be examined. On the optical axis behind, the taking lens 10, the mirror 50,
The lens 51, the flip-up mirror 11, and the film 12 are arranged. The positions of the mirror 50 and the lens 51 are provided at positions decentered from the optical axis as shown in FIG. Reference numeral 12a is an aperture mask provided on the front surface of the film 12 for area separation.

A field lens 13, a half mirror 14, a relay lens 15, an image pickup tube 16 and a television monitor 17 are arranged on the optical path in the reflection direction of the flip-up mirror 11, and a projection lens 18 is provided behind the half mirror 14. The fixation mechanism 52 is arranged. Further, the electrical output of the fixation mechanism 52 is connected to a data display 54 composed of display LEDs via the control circuit 53, and the display of the display 54 is displayed on the mirror 5.
0, and is projected onto the film 12 via the lens 51.

As shown in FIG. 7, the fixation mechanism 52 comprises a surface emitting LED 55 and a liquid crystal display plate 56, which is connected to a liquid crystal driver 57 and a liquid crystal driver 57.
A control circuit 58 and an optotype switch 59 are connected to the.

The transmissive region T of the liquid crystal display plate 56 is a small circular region which is two-dimensionally prepared on the liquid crystal display plate 56 as shown in FIG. 8, and each small circular transmissive region T is a fixation lamp. It corresponds to the bright spot of. The liquid crystal driver 57 moves on the transmissive area T of the liquid crystal display board 56 by inputting the optotype switch 59, and leaves one small circular area in the area T and shields the other. Therefore, the examiner can operate the optotype switch 59 to move the position of the fixation lamp.

Since the two-dimensional position of the fixation lamp by the fixation mechanism 52 thus formed corresponds to the position of the liquid crystal driver 57, the output of the liquid crystal driver 57 is controlled by the control circuit 5.
3, the position of the fixation lamp on the surface of the film 12 is converted into the actual size, and the result is displayed on the data display 54.
The image on the data display 54 is recorded on the film 12 via the mirror 50 and the lens 51. Therefore, in synchronization with the photographing of the fundus Er of the eye E to be inspected, the display 54 and the liquid crystal display board 56 are synchronized.
When is emitted, the position of the fixation lamp is simultaneously recorded on the surface of the film 12 together with the fundus image.

Since the mirror 50 and the lens 51, which are the recording optical system of the display 54, form an optical axis a decentered from the optical axis a of the photographing optical system on the paper surface as shown in FIG. Axis a and b are the fundus image recording area A and the data recording area B.
Are formed on the surface of the film 12 as shown in FIG. The fundus image Ea is recorded in the recording area A portion of the fundus image, and the deviation from the center position of the fundus image of the fixation lamp is recorded as a number in the data recording area B. The shadow M is a portion that remains black due to the aperture mask 12a. In order to specify the center position of the fundus image Ea on the aperture mask 12a, the small protrusions Ma, Mb, M
c, Md are prepared, the intersection of these shadows is taken as the origin, and the point deviated from this origin by the value recorded in the data area is
Point Pa where the fixation light was presented at the time of shooting, that is, eye E
Will be the fixation point.

In the second embodiment, the fixation point detects the position of the selected small circular transmission region T of the liquid crystal display plate 56, but a single LED is mechanically moved as in the conventional device. In this case, the position of the LED may be directly detected or may be optically detected by utilizing the light emission of the LED. The latter most effective means may be a method of detecting the position of the fixation lamp image Pa on the television monitor 17 using a video signal. Since the fixation lamp image Pa has a higher contrast than the video signal of the fundus image displayed on the television monitor 17, its detection can use reflected light that is relatively easy. That is, the light flux from the liquid crystal display plate 56 passes through the lens 13 and is reflected by the mirror 11 to form an image in the reflected space.
If an optical position detector such as a two-dimensional PSD is provided here, the position information of the fixation lamp can be obtained.

The second embodiment of FIG. 5 is an example applied to a non-mydriasis type fundus camera, but the following method can be considered to apply this to a mydriasis type fundus camera. That is, the liquid crystal display plate 56 shown in FIG. 5 is provided in the illumination optical system at a position conjugate with the fundus Er of the eye to be inspected, and the liquid crystal liquid crystal driver 57 shields one small circular transmission region. As a result, the selected small circular shield is projected as a shadow on the fundus Er by the observation illumination light. The examiner has the eye examiner fixate this shadow. Then, at the time of photographing, the liquid crystal display board 56 may be retracted from the optical path of the illumination optical system.

Further, various methods are conceivable for the method of recording the fixation position, and it is possible to use a known method for recording the data of the fundus camera. FIG. 10 is an example of a fundus photograph by a method of recording the fixation position directly from the back surface of the film 12. Recording area A of fundus image
On the right side and the lower side of the LCD, LEDs are prepared by the number of vertical and horizontal transmissions of the small circular transmission of the liquid crystal display panel, and the LEDs are turned on so as to indicate the selected area, and the bright spot L is formed on the surface of the film 12. This is a method of imprinting. The intersection Pa of these two bright points L becomes the position of the fixation lamp, and it becomes possible to more directly indicate the fixation position.

Further, although all the above examples have been described by taking the apparatus in which the fundus image is recorded on the film surface as an example, when the recently developed electronic image recording method is used, the coordinate position is TEXT d.
It is possible to record and reproduce the ata together with the fundus image, and synthesize an optotype indicating the coordinates as needed.

It should be noted that in the fundus camera having a fixed fixation target for each of the left and right eyes, it is simply shown in FIG.
, (B), the position may be fixedly shown. In FIG. 12, P1 and P2 are fixation targets.

[0036]

As described above, the fundus camera according to the first invention can detect the two-dimensional pattern projected by the effect of the polarizing plate with better contrast. Further, the fundus camera according to the second aspect of the invention can fix the fixation position in the fixation state inspection, and can record all the necessary information in one shooting.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment.

FIG. 2 is an explanatory diagram of a position of an eccentric diaphragm and a polarization direction of a polarizing plate.

FIG. 3 is a layout view of a part of an optical system.

FIG. 4 is an explanatory diagram of an output example of the device.

FIG. 5 is a configuration diagram of a second embodiment.

FIG. 6 is a layout diagram of a data photographing system.

FIG. 7 is a configuration diagram of a fixation device.

FIG. 8 is an explanatory diagram of an equivalent area of a liquid crystal display panel.

FIG. 9 is an explanatory diagram of a recording state on a film.

FIG. 10 is an explanatory diagram of a recording state on a film.

FIG. 11 is a conventional example of a fixation device using a non-mydriasis fundus camera.

FIG. 12 is an explanatory diagram of a recording state on a film.

[Explanation of symbols]

 7, 30 Objective lens 6 Perforated mirror 1, 20 Illumination light source 9, 24, 35 Strobe tube 12 Film 16 Imaging tube 17, 43 TV monitor 19 LED 25, 36 Eccentric diaphragm 29 Pupil splitting mirror 33, 37 Polarizing plate 40 CCD camera 41 controller 42 frame memory 44 image processing circuit 52 fixation mechanism 53 control circuit 54 display 56 liquid crystal display board 57 liquid crystal driver

Claims (8)

[Claims] 1. A projection optical system for projecting a two-dimensional projection pattern onto a fundus of a subject's eye from a first region on a pupil of the subject's eye, and a second region deviated from the first region. A fundus camera having an imaging optical system that captures a reflection image of the projection pattern, and a calculation unit that calculates a three-dimensional shape of the fundus from the projection pattern image captured by the imaging optical system,
A fundus camera, wherein polarizing plates having the same polarization direction are provided in the projection optical system and the imaging optical system. 2. An illumination optical system for illuminating a fundus of an eye to be inspected,
An imaging optical system for imaging the illuminated fundus, and projection means for projecting a fixation target on the fundus for guiding the line of sight of the eye to be selected in order to select a region of the fundus imaged by the imaging optical system. A fundus camera having: a means for recording position information of the fixation target on a plane perpendicular to the optical axis of the fixation target together with the fundus image. 3. The fundus camera according to claim 2, wherein the position information is recorded outside a fundus image recording area. 4. The fundus camera according to claim 2, wherein the fixation target moves in a plane perpendicular to the optical axis. 5. The fundus camera according to claim 2, wherein the fixation target is of a self-luminous type and projects onto the fundus of the eye to be examined through an optical system. 6. The fundus camera according to claim 2, wherein the illumination optical system emits invisible light. 7. The fundus camera according to claim 2, wherein the fixation target is opaque and projects onto the fundus of the eye to be inspected through the illumination optical system. 8. The illumination optical system includes an observation light source for irradiating the fundus for projecting observation light composed of visible light, and the fixation target is illuminated by the illumination optical system when a fundus image is captured. The fundus camera according to claim 4, further comprising means for retracting the optical path out of the optical path.