JP3591947B2 - Fundus examination device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fundus examination device used when examining a fundus of a subject in an ophthalmic clinic.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a fundus camera, a method is known in which the amount of light reflected from an imaging medium is detected, and when the amount of exposure reaches a reference value, the strobe light emission is stopped to automatically adjust the amount of exposure. . In recent years, in addition to color photography and visible fluorescence photography, infrared fluorescence photography using infrared light has been performed. In particular, in this infrared fluorescence photography, the fluorescence intensity rapidly changes with the appearance of fluorescence. Requires that the exposure be adjusted automatically.
[0003]
[Problems to be solved by the invention]
However, in a conventional fundus camera, a color image appears on the entire screen, but a fluorescent image is displayed as a thin bright line in a black background. There is a difference. Therefore, when the automatic light control of the fluorescence imaging is performed with the same reference light amount as that of the color imaging, a problem occurs that the image is too bright. Further, when an image is taken using an electronic imaging medium, the signal is A / D converted, and the image data is handled as digital data, the resolution in the density direction is limited. Otherwise, information in the density direction is lost.
[0004]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a fundus inspection apparatus that can solve the above-described problems and can always perform imaging with an appropriate exposure amount according to an imaging mode.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a fundus examination apparatus according to the present application provides a fundus illuminating unit having a strobe light source and a detachable first bandpass filter, and a fundus imaging unit having a detachable second bandpass filter. Controlling the light emission of the strobe light source by detecting that the amount of light received by the photographing light amount detector by the light emission of the strobe light source has reached a reference value; And a reference value of the received light amount is changed by the light emission control means in accordance with insertion / removal of the first and / or second band pass filter.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will be described in detail based on the illustrated embodiment.
FIG. 1 shows a configuration diagram of a fundus camera according to an embodiment. On a light path from an observation alignment light source 1 such as a lamp to an objective lens 2, a condenser lens 3, a still image photographing light source 4 such as a strobe, and a ring-shaped aperture are provided. A diaphragm 5, an exciter filter 6 that can be inserted into and removed from the optical path, a relay lens 7, and a perforated mirror 8 are sequentially arranged. On the optical path behind the perforated mirror 8, a barrier filter 9 that can be inserted into and removed from the optical path, a photographic lens 10, a switching mirror 11, and a high-definition camera 12 for capturing a color still image or a monochrome still image are sequentially arranged. A high-sensitivity camera 13 for moving image observation is arranged in the reflection direction of the switching mirror 11. A lens 14 and a light amount sensor 15 are arranged below the front surface of the high-definition camera 12, and an exposure amount detecting unit that receives a part of the reflected light from the imaging surface of the high-definition camera 12 is formed.
[0007]
Further, a control unit 16 having an arithmetic unit, a storage unit, a digital signal and a video signal input / output unit, and the like is provided. The control unit 16 includes a high-definition camera 12, a high-sensitivity camera 13, a light amount sensor 15, Outputs of a selection switch 17, a photographing switch 18, and a mode selection switch 19 are connected, and an output of the control means 16 is connected to the still picture photographing power supply 4 via a power supply controller 20 having a charge storage means such as a capacitor. Further, it is connected to an image storage means 21 such as a hard disk and a television monitor 23 having a mouse 22. Note that a window on which the display position and the display magnification can be freely changed or deleted by the mouse 22 can be displayed on the television monitor 23. The photographing switch 18 includes a two-stage switch. In the fluorescence mode, the first-stage switch operation causes the barrier filter 9 to be inserted into the optical path.
[0008]
When performing color photographing, a high-definition camera 12 for color photographing having a color filter in front of an image sensor is used, a photographing mode selection switch 19 selects color photographing, and an exciter filter for fluorescence photographing. 6 and the barrier filter 9 are retracted outside the optical path. Then, the ISO sensitivity of the film in the high definition camera 12 is set by the sensitivity selection switch 17.
[0009]
The light beam emitted from the observation alignment light source 1 passes through the condenser lens 3, the strobe light source 4, the aperture 5, the relay lens 7, is reflected to the left by the mirror portion of the perforated mirror 8, passes through the objective lens 2, and passes through the eye to be examined. The fundus Er is illuminated through the pupil Ep of E. The reflected light from the fundus Er passes from the pupil Ep through the objective lens 2, the hole of the perforated mirror 8, the photographing lens 10, and forms an image on the imaging surface of the high-sensitivity camera 13 for moving image observation by the switching mirror 11, It is converted into an electric signal and input to the control means 16. This moving image is displayed on the television monitor 23 in one of the windows whose position and size are selected by the mouse 22.
[0010]
The examiner looks at the fundus image of the subject's eye E shown in this window, confirms that the imaging part, alignment, and focus state are good, and then operates the imaging switch 18. As a result, the switching mirror 11 retracts out of the optical path, the power supply controller 20 starts discharging, and the strobe light source 4 emits light. The light beam emitted from the strobe light source 4 illuminates the fundus Er through the same optical path as the light beam emitted from the observation alignment light source 1. The reflected light from the fundus Er also forms a fundus image on the imaging surface of the high-definition camera 12 for photographing a still image through the same optical path.
[0011]
At this time, a part of the light beam is reflected on the imaging surface, passes through the lens 14 and enters the light amount sensor 15 and is photoelectrically converted. This signal is input to the control means 16 and integrated, and its value is compared with a reference value. The integral value increases with time. When the integrated value exceeds the reference value, a light emission stop signal is output, the power supply controller 20 stops discharging, and the strobe light source 4 stops emitting light.
[0012]
This reference value is stored in advance in the memory of the control means 16 for each film ISO sensitivity of the camera to be set, and is read out and used according to the ISO sensitivity setting of the film to be used. Therefore, an appropriate reference value is automatically set in accordance with the photographing sensitivity selected by the photographer according to the purpose, so that an image with an appropriate exposure can always be obtained.
[0013]
The image captured by the high-definition camera 12 is converted into an electric signal, converted into a digital signal, transferred to a memory in the control unit 16, stored in the image storage unit 18, and stored in the window of the television monitor 23. Are displayed in one. In this manner, a predetermined portion on the fundus Er is photographed, and the color photographing is completed.
[0014]
When performing infrared fluorescence imaging, the high-definition camera 12 is replaced with a monochrome imaging camera having sensitivity to infrared light, and the ICG imaging mode is selected by the imaging mode selection switch 19. Is inserted into the optical path. Then, the examiner selects the ISO sensitivity of the film of the high-definition camera 12 using the sensitivity selection switch 17 according to the amount of the fluorescent agent, the intravenous injection speed, and the like.
[0015]
When the observation alignment light source 1 is turned on, the light beam passes through a condenser lens 3, a strobe light source 4, an aperture 5, an exciter filter 6, and a relay lens 7, is reflected to the left by a mirror portion of a perforated mirror 8, and an objective lens 2 Illuminates the fundus Er from the pupil Ep of the eye E to be examined. The reflected light from the fundus Er passes from the pupil Ep through the objective lens 2, the hole of the perforated mirror 8, the photographing lens 10, and is imaged on the imaging surface of the high-sensitivity camera 13 by the switching mirror 11, and is converted into an electric signal. Then, it is input to the control means 16.
[0016]
This moving image is displayed on the television monitor 23 in one of the windows whose position and size are selected by the mouse 22. The examiner looks at the fundus image of the eye E illuminated by the excitation light reflected in this window. After confirming the imaging part, alignment, and focus state, and confirming that these are good, a fluorescent agent is intravenously injected into the subject, and at the same time, the first step of the imaging switch 18 is pressed to release the bi-layer. The filter 9 is inserted in the optical path. After that, the appearance of the fluorescent image is confirmed on the observation screen of the window on the television monitor 22, and the second step of the photographing switch 18 is pressed.
[0017]
As a result, the switching mirror 11 is retracted out of the optical path, and at the same time, the power supply controller 20 starts discharging and the strobe light source 4 emits light. The light beam emitted from the strobe light source 4 illuminates the fundus Er of the eye E through the same light path as the light beam from the observation alignment light source 1. At this time, the fundus Er illuminated by the excitation light emits fluorescence, and this fluorescence passes through the objective lens 2, the hole of the perforated mirror 8, the barrier filter 9, and the photographing lens 10 from the pupil Ep, and is imaged by the high-definition camera 12. Image on the surface.
[0018]
At this time, a part of the light beam reflected by the imaging surface enters the light amount sensor 15 through the lens 14, is photoelectrically converted, input to the control means 16, and integrated. The integrated value is compared with the reference value, and when the value exceeds the reference value, a light emission stop signal is output, the power supply controller 20 stops discharging, and the strobe light source 4 stops emitting light. This reference value is stored in advance in a memory in the control means 16 in accordance with the film sensitivity and the photographing mode of the camera to be set, and is read out and used according to the film sensitivity setting and the photographing mode. In this manner, since the appropriate reference value is automatically set according to the photographing sensitivity selected by the examiner for the purpose, it is possible to always obtain a photograph with an appropriate exposure.
[0019]
FIG. 2 shows a color fundus image Er ′, and FIG. 3 shows a density distribution on the line segment A. In a color image, since a light beam is reflected from the entire fundus Er, the entire image has a density and performs proper exposure. For this purpose, it is necessary to control the light emission time of the strobe light source 4 so that both the bright part at the center of the image and the dark part at the periphery are within the allowable value. Since the light amount sensor 15 detects the amount of reflected light from the entire image, it is necessary to set a reference value such that the entire image can be detected at an appropriate density as shown in FIG.
[0020]
On the other hand, FIG. 4 shows the fluorescence fundus image Er ″, and FIG. 5 shows the density distribution on the line segment A. Since the fluorescence image receives only the fluorescence from the blood vessel and a part of the fluorescence leakage site, the image of the other portion is Therefore, in order to perform the proper exposure in this case, the light emission time of the strobe light source 4 must be set so that both the fluorescence from the blood vessel and the weak fluorescence from the leak site are within the allowable values. For this purpose, the reference value for fluorescence must be smaller than the reference value for color.
[0021]
By performing display using the multi-window as described above, the display screen can be set to an arbitrary position and size, so that it is necessary to separately view the alignment moving image and the photographing still image. There is no need to provide a TV monitor or switch between screens with a single TV monitor, and observation can be performed simultaneously on a single screen, so that a large arrangement space is not required and work efficiency is improved. Further, by setting a different reference value for each of the photographing modes of the color photographing and the fluorescent photographing, an image can always be photographed with an appropriate exposure amount, which is extremely effective for precise inspection diagnosis.
[0022]
Furthermore, if a camera for color photographing and a camera for fluorescent photographing are mounted on the fundus camera in advance and automatically switched according to the photographing mode, the efficiency is further improved.
[0023]
Further, in the case of fluorescent imaging using infrared light, the intensity of the amount of fluorescent light changes greatly over time, so it cannot be adjusted only by changing the light emission amount of the strobe light source 4, and the film sensitivity setting is not changed during shooting. Need to be adjusted many times. Therefore, for example, when the exposure amount to the image pickup means does not reach the reference value even when all the energy stored in the capacitor is released, the film sensitivity is automatically set to a high value, and the strobe light source 4 is turned on in the shortest time. If the reference value is exceeded even after the light emission is stopped, a means for automatically lowering the film sensitivity is provided to extend the automatic adjustment range of the exposure amount. At this time, if the reference value is automatically reset according to the change in the setting of the film sensitivity, an image with an appropriate exposure amount can be obtained without performing a complicated operation.
[0024]
In addition, the present invention can be applied not only to infrared fluorescent imaging but also to fluorescent imaging using visible light. In this case, the reduction in peripheral light amount and the appearance of fluorescent light differ between infrared fluorescent light and visible fluorescent light. If different reference values are provided according to the shooting mode, an image with a more appropriate exposure amount can be obtained. For example, for a low-sensitivity setting equivalent to ISO100, ISO200, or ISO400, a reference value based on color imaging is set, and for a high-sensitivity setting equivalent to ISO800, ISO1600, fluorescence imaging is assumed. The set reference value may be set.
[0025]
Also, instead of detecting the reflected light from the imaging means, a light separating means for separating a part of the light flux is provided in the optical path on the way to the imaging means of the photographing optical system, and the separated light flux is detected and exposed. The amount may be set. Further, means for arranging density filters having different densities in front of the light amount sensor 15 according to the shooting mode may be provided.
[0026]
【The invention's effect】
As described above, the fundus inspection apparatus according to the present invention can always obtain an image with an appropriate exposure amount in both color imaging and fluorescence imaging, and perform efficient inspection with less imaging failure. Further, by receiving light with an appropriate exposure amount, it is possible to perform imaging with a fine resolution in the density direction, so that much information can be obtained and more precise diagnosis can be performed. Furthermore, since the exposure operation is not required when the photographing mode is changed, the photographing mode can be easily changed and the apparatus can be operated efficiently.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an embodiment.
FIG. 2 is an explanatory diagram of a fundus image during color photographing.
FIG. 3 is a graph showing a density distribution during color photographing.
FIG. 4 is an explanatory diagram of a fundus image during fluorescence imaging.
FIG. 5 is a graph showing a density distribution during fluorescence imaging.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Observation / alignment light source 4 Still image photographing light source 5 Ring aperture stop 6 Exciter filter 9 Barrier filter 12 High definition camera 13 High sensitivity camera 15 Light quantity sensor 16 Control means 17 Sensitivity selection switch 18 Photographing switch 19 Mode selection switch 20 Power supply Controller 21 Image storage means 23 TV monitor

Claims (3)

Fundus illumination means having a strobe light source and a removable first bandpass filter, fundus imaging means having a removable second bandpass filter, and a photographing light amount for receiving a part of reflected light from the fundus Detecting means for detecting that the amount of light received by the photographing light amount detecting means by the light emission of the strobe light source has reached a reference value, and controlling light emission of the strobe light source. A fundus examination apparatus characterized by changing the reference value of the amount of received light according to insertion / removal of the first and / or second band pass filters. 2. The fundus examination apparatus according to claim 1, further comprising at least two types of bandpass filters having different characteristics in the fundus illumination unit and the fundus imaging unit, and changing the reference value according to the type of the bandpass filter. 2. The fundus examination apparatus according to claim 1, further comprising a switching unit that automatically switches a camera sensitivity and the reference value when the amount of received light exceeds the reference value or does not reach the reference value. 3.

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