JPH0330367B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides for operational steps when performing fluorescent fundus photography.
This invention relates to a fundus camera that has been improved to be easier to use.

Fluorescent fundus photography, which is known as a type of ophthalmologic imaging, illuminates the fundus with blue excitation light, timing the time when a fluorescent agent injected through the cubital vein reaches the intraocular circulation system, and then detects blood vessels. This is done by photographing the green-yellow fluorescence emitted by the fluorescent agent inside. At that time, the first
An exciter filter having wavelength versus light transmittance characteristics as shown in A in the figure is inserted into the illumination optical path,
It is necessary to insert a barrier filter having characteristics as shown in B in FIG. 1 into the photographing optical path. However, when both the exciter filter and the barrier filter are inserted, nothing can be seen in the fundus image seen through the finder until the fluorescence starts to appear, and even after the fluorescence begins to appear, the illuminance of the fluorescence image remains Since the ophthalmological camera and the fundus of the eye to be examined are difficult to align and focus, we first looked at the blue fundus with the exciter filter inserted into the illumination optical path for fundus observation. However, in the case of aligning the position with the fundus of the eye, adjusting the focus, inserting the barrier filter based on my experience and anticipating when fluorescence starts to come out from the fundus, and starting the photographing, or with automated barrier filter insertion,
The time until the barrier filter is inserted is set using a timer or the like, and after the set time has elapsed, the barrier filter is inserted and photography begins.
This is because, in fluorescence fundus photography, it is important to photograph the process in which the fluorescent agent begins to emerge from the fundus and spreads. However, the time it takes from the time the fluorescent agent is injected until it begins to come out of the fundus of the eye varies from person to person, and varies widely, ranging from about 6 to 13 seconds. In order to compensate for this variation, in the above method, for safety reasons, the barrier filter was inserted and photography started approximately 4 to 5 seconds later, so photography was started several seconds before the fluorescent agent started coming out from the fundus. For the reasons mentioned above, images of the fundus are often photographed in the dark, and not only is the film wasted, but the position and focus of the fundus and camera may be incorrect before the fluorescent agent begins to come out from the fundus. It had the disadvantage of shifting.

SUMMARY OF THE INVENTION An object of the present invention is to provide a camera that eliminates the above-mentioned drawbacks and enables fluorescence fundus photography that detects the amount of fluorescence before photographing the fundus without substantially restricting the field of view for fundus observation. .

The present invention will be explained in detail based on the embodiments shown in FIG. 2 and below.

FIG. 2 is a configuration diagram showing an example of the optical system of an ophthalmological camera, and 1 is an observation light source consisting of a tungsten lamp, etc.
The light emitted from the is incident on the mirror 4 via the condenser lens 2a, the photographing light source 3 consisting of a xenon discharge tube, etc., and the condenser lens 2b, where it is deflected and sequentially transmitted to the exciter filter 5, the ring slit plate 6, and the relay lens. It reaches the perforated mirror 8 via 7a and 7b.
Incidentally, reference numeral 9 denotes a reflecting mirror arranged behind the observation light source 1 to collect and reflect the light from this lamp. The light that enters the perforated mirror 8 from the above-mentioned illumination optical system is reflected by the perforated mirror 8 in the direction of the eye E to be examined, illuminates the fundus Ef of the examined eye E, passes through the original optical path, and then returns to the perforated mirror 8. and reaches the observation optical system. An objective lens 10 is arranged between the perforated mirror 8 and the subject's eye E, and behind the perforated mirror 8, along the optical axis, there are a barrier filter 11, a focusing lens 12, a photographing lens group 13, and a movable lens. Mirror 14, shutter 15, photographic film 1
6 are arranged in sequence. On the reflective side of the movable mirror 14, photographic films 16 are sequentially placed along the optical axis.
a field lens 17 placed in a conjugate position with
A mirror 18 and a finder 19 are arranged to change the optical path. Note that e is the examiner's eye.

Here, the exciter filter 5 is inserted into the illumination optical path by a solenoid 20 during fluorescence photography, and removed from the optical path during other photography, and its operation is confirmed by a micro switch (not shown). . Further, the barrier filter 11 is inserted into and removed from the photographing optical path by driving a solenoid 21.

Here, in the figure, 22 is a beam splitter, 23
24 is a wavelength selection filter that has the same characteristics as the barrier filter 11 and selects the wavelength of fluorescent light; 25 is a light receiving element for detecting fluorescent light;
5 is arranged in a conjugate relationship with the photographic film 16.

Note that the light receiving range of the light receiving element 25 includes the fundus photographing range. That is, in this embodiment, full-plane photometry is performed.

This ophthalmological camera has an illumination light source 1 and a photographing light source 3.
is substantially conjugate with respect to the condenser lens 2a, the observation light source 1 is turned on during observation, and the photographing light source 3 is turned on instantaneously during photography. The light source image is once formed near the ring slit plate 6 by another condenser lens 2b, and then an image of the annular opening of the ring slit plate 6 is formed near the perforated mirror 8 by relay lenses 7a and 7b. The illumination light is reflected and travels to the left. Then, after forming an image of the annular aperture near the crystalline lens E1 of the eye E to be examined using the objective lens 10, the fundus Ef is illuminated.

The reflected light from the fundus Ef travels to the right and is once formed into an image by the crystalline lens E1 and the objective lens 10, then passes through the perforated mirror 8 and the photographic diaphragm (not shown), and is focused by the focusing lens 12 and photographic lens group 13. The image will be focused. During observation, the fundus image is guided upward by the movable mirror 14 located at the solid line position, and is observed by the examiner's eye e through the finder 19. At the same time, the fundus image is guided by the beam splitter 22 for fluorescence detection. A focused image is also formed on the light receiving element 25 of.

When taking a photograph, the movable mirror 14 is rotated to the dotted position, and the fundus image is formed on a photographic film 16 via a shutter 15 which is released.

FIG. 3 shows a control block circuit according to an embodiment of the present invention, in which 31 is an amplification/detection output control circuit for the light receiving element 25, and 32 is a power supply/trigger circuit for causing the photographing light source 3 to emit light. S1 is a micro switch that detects when the exciter filter 5 enters the illumination optical path, and S2 is a micro switch that detects when the exciter filter 5 enters the illumination optical path.
1 is a micro-switch that detects entering the photographing optical path, and S3 is a photographing switch. 3
3 is an AND circuit.

When performing fluorescence fundus photography, first a fluorescent agent is injected into the subject, the exciter filter 5 is inserted, and the fundus Ef is illuminated with illumination light for fundus observation shown in characteristic A in FIG. At this time, the microswitch S1 for detecting insertion into the optical path of the exciter filter 5 becomes conductive, and the amplification/detection output control circuit 31 starts operating in response to the signal, and starts detecting fluorescence emitted from the fundus of the eye. The examiner presses the photographing switch S3 to make it conductive, and waits while aligning and focusing the fundus of the eye to be examined and the camera.

After a few seconds, when the fluorescent agent begins to come out from the fundus, the fluorescent light is detected by the light receiving element 25, and its output signal is amplified by the amplification/detection output control circuit 31, drives the solenoid 21, and activates the barrier. At the same time as the filter 11 is inserted into the photographing optical path, a signal is also sent to the AND circuit 33. When the barrier filter enters the photographing optical path, the confirmation microswitch S2 becomes conductive, and the AND circuit 33 applies an output signal to the power supply/trigger circuit 32 of the photographing light source, causing the photographing light source 3 to emit light. This allows you to photograph the beginning of the fluorescent agent coming out from the fundus of the eye. Here, to explain the role of the filter 24 installed in front of the light receiving element 25, the fluorescence from the fundus illuminated with blue light by the exciter filter 5 is very weak compared to the background light, that is, the blue light. If fluorescent light is detected with blue light directly applied to the light-receiving element, the detection accuracy will deteriorate due to the difference in intensity. Therefore, in front of the light receiving element,
By inserting a filter 24 having the characteristics shown in FIG. 1B, it becomes possible to cut out background light.
Fluorescence can be detected with high precision.

4 and 5 show another embodiment of the invention. The same reference numerals indicate the same members as in FIG. 26 is a beam splitter, 27 is a mirror, and 29 is a transparent glass plate as shown in FIG. 5 with a mark C on it.
and are connected to each other by an interlocking mechanism 28 that can move within the same plane perpendicular to the optical axis.

Note that the light receiving element 25 and the glass plate 29 are placed at a position conjugate with the surface of the photographic film. This embodiment will be explained below. It is known that intravenously injected fluorescent agents generally begin to exit from the papilla of the fundus of the eye. Therefore, by aligning the light receiving range of the light receiving element 25 with the papilla of the fundus of the eye, it is possible to detect the start of fluorescence with even greater precision. According to this method, the examiner looks at the subject's fundus Ef through the finder 19 and moves the glass plate 29 so that the mark C coincides with the papilla, and the light receiving element 25
can be easily matched with the papilla.

In addition, in the control block diagram of FIG. 3, if the camera is on standby without pressing the photographing switch S3 and fluorescence is emitted from the fundus, only the barrier filter 11 can be driven by the signal output from the light receiving element 25.
In this case, the examiner can take a photograph at any time while observing the fluorescent image. In addition, by inserting the barrier filter 11 in the front into the photographing optical path and pressing the photographing switch S3, the examiner does not have to concentrate on the viewfinder, but the fluorescent light starts to appear and the image is automatically detected. It is also possible to take pictures.

Note that it is preferable to limit the operation of the fluorescence detection system to the case where the exciter filter is in the illumination optical path.

In other words, the fluorescence detection system may be operated by the drive signal of the solenoid 20.

As described above, the fundus camera of the present invention can detect the amount of fluorescent light before photographing the fundus without substantially restricting the fundus observation field. In the above embodiment, by providing a fluorescence detection element,
The timing of inserting the barrier filter is automated, making it possible to photograph the beginning of fluorescence from the fundus at the optimal timing, regardless of the examiner's experience or individual differences between the examinees, allowing the examiner to insert the barrier filter. Since the device is automated, you can focus on aligning it with the subject's fundus and focusing until it is inserted, making it possible to take better images of the fundus using fluorescent light.

[Brief explanation of drawings]

FIG. 1 is a characteristic diagram of an exciter filter and a barrier filter, FIG. 2 is a configuration diagram of a fundus camera according to the present invention, FIG. 3 is a block diagram of an operating circuit, and FIGS. A configuration diagram of the embodiment, in which 1 is an observation light source, 3 is a photographic light source, 5 is an exciter filter, 8 is a perforated mirror, 10 is an objective lens, 11 is a barrier filter, 14 is a movable mirror, 16 is a photographic film, 19 20 and 21 are solenoids, 24 is a filter, 25 is a light receiving element, and S1, S2, and S3 are switches.

Claims (1)

[Scope of Claims] 1. A fundus camera capable of photographing a fluorescent fundus and having a fundus observation system capable of observing the fundus of the subject's eye illuminated with excitation light before photographing the fundus; A wavelength selection filter that selects the wavelength of fluorescent light from the fundus of the subject's eye that is provided and illuminated with excitation light, and a photodetector that detects the amount of fluorescent light before photographing the fundus through the wavelength selection filter. fundus camera. 2. The fundus camera according to claim 1, wherein a filter for fluorescent fundus photography is inserted into the photographing optical path based on the output of the photodetector. 3. The fundus camera according to claim 1, wherein excitation light for fluorescent fundus photography is generated by the output of the photodetector. 4. The fundus camera according to claim 1, wherein the light receiving range of the photodetector is a part of the fundus field, and the photodetector is movable in a plane perpendicular to the optical axis. 5. The fundus camera according to claim 4, wherein the light receiving range of the photodetector corresponds to the papilla. 6. The fundus camera according to claim 1, wherein the light receiving range of the photodetector includes a fundus photographing range. 7. The fundus camera according to claim 1, wherein the photodetector is activated substantially in response to insertion of a filter into the illumination optical path that generates excitation light for fundus illumination.