JPH07163524A - Fundus camera - Google Patents

Abstract

PURPOSE:To realize the exact irradiation with a laser beam by selecting a blood vessel to be photographed while observing a fundus oculi image, irradiating the blood vessel with the laser beam to make previously injected fluorescent dyestuff to emit fluorescence and freely correcting the misalignment of the position to be irradiated with the laser according to the movement of the eyeball CONSTITUTION:After the fluorescent dyestuff enveloped by a liposome is intravenously injected into a testee, the fundus oculi Ea is illuminated with a light source 39 for irradiation in the state of retreating an exciting filter 37 from an optical path and the reflected light thereof is photodetected as a fundus oculi image and a blood vessel image by a television camera 18 and a one-dimensional CCD sensor 23. The eyeball motion is detected by the signal of the blood vessel image and a galvanomirror 8 is changed to automatically trace the fundus oculi. The fluorescent dyestuff in the blood vessel of the eyeball E is made to emit light by irradiation with the laser beam from a semiconductor laser beam source 19 in the state of putting the exciting filter 37 into the optical path. Only the fluorescent component among the reflected luminous fluxes of the fundus oculi Ea is received by the television camera 18 and the fluorescent blood vessel image is recorded 19. The misalignment of the position to be irradiated with the laser beam according to the movement of the eyeball is thus corrected.

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 irradiating a fundus of an eye to be examined with excitation light to excite a fluorescent dye and imaging fluorescence from the fundus.

[0002]

2. Description of the Related Art Fluorescent fundus photography is known as one of fundus photography, and is frequently used for diagnosis of retinal diseases.
To obtain a more detailed image of the fundus blood vessels, Ran C. Zeimer
Et al. "Feasibility of Blood Flow Measurement by Exte
rnally Controlled Dye Delivery (Investigative Opht
halmology & Visual Science, Vol.30, No.4, 1990.4, p
p660-667), a method for reducing background noise in a fluorescent image is proposed.

In this method, a fluorescent dye such as fluorescein to be injected into the body of a subject is enclosed in microspheres of artificial lipid membrane called liposome. Since this liposome contains phospholipids such as phosphatidylglycerol and phosphatidylcholine as its main components and does not dissolve in physiological saline and is turbid in saline solution, the fluorescent dye encapsulated in the liposome is caused by concentration quenching at room temperature. Even when irradiated with excitation light having an appropriate wavelength, it hardly emits fluorescence. However, when the temperature exceeds a certain temperature, the liposome is dissolved and the encapsulated fluorescent dye is released into the solution, so that it is excited by the excitation light and emits strong fluorescence.

At the time of fluorescence photography, first, a fluorescent dye encapsulated in liposomes is injected into the body through a vein of a subject. Then, after the dye reaches the intraocular circulatory system, the fundus camera observes the fundus of the subject to select blood vessels on the fundus to be photographed, and the luminous flux diameter of the laser light, the output, the pulse width, the wavelength, etc. Set the shooting conditions for. When the laser light is applied to the fundus blood vessel to be imaged, the liposomes in the bloodstream are heated and dissolved, and the encapsulated fluorescent dye is released into the bloodstream. After irradiating the laser light for a certain period of time, the fundus of the eye to be examined is illuminated with excitation light having a wavelength near blue. This excitation light excites the fluorescent dye released into the bloodstream to emit strong fluorescence. Of the light flux reflected from the fundus of the eye, only the fluorescence reaches the imaging optical system by using the filtration filter, and a fluorescent blood vessel image is recorded on the film or the like.

According to this method, the liposomes present in tissues other than the fundus blood vessels such as the choroid are not heated and the encapsulated fluorescent dye is not released, so that they cannot emit fluorescence even when irradiated with excitation light. It is possible to receive only fluorescence from blood vessels, and it is possible to capture a fundus blood vessel image with low background noise.

[0006]

However, in the above-mentioned conventional method, when the fundus blood vessel to be imaged is displaced in a short time due to the movement of the eyeball or the like, the laser light is accurately applied to the blood vessel to be imaged. In addition, not only a fundus blood vessel image of a desired site cannot be obtained, but also a site other than a blood vessel may be erroneously irradiated with laser light to damage the tissue.

The object of the present invention is to solve the above problems,
An object of the present invention is to provide a fundus camera capable of accurately irradiating a desired position with laser light when performing fluorescence imaging.

[0008]

Means for Solving the Problems A fundus camera according to the present invention for achieving the above object is different from an illuminating means for illuminating a fundus of an eye to be examined in a first wavelength band. An observation / photographing optical system for observing or photographing the fundus in the second wavelength band, and a laser for injecting a fluorescent dye in a state of suppressing the fluorescence emission reaction into the body of the subject to release the suppression of the fluorescence emission reaction. In a fundus camera capable of fluorescence imaging provided with irradiation means for irradiating light, the observation and photographing optical system includes a deflection optical system for deflecting the irradiation position of the laser light, and an eye movement detecting means for detecting eye movement of the eye to be examined. Has and
It is characterized in that the deflection optical system is driven to automatically track the fundus based on the information obtained by the eye movement detecting means.

[0009]

The fundus camera having the above-mentioned structure selects a blood vessel to be photographed while observing the fundus image, irradiates the blood vessel with laser light, and is capable of emitting fluorescence from the fluorescent dye injected in advance. To When the irradiation position of the laser light is determined, the movement of the eyeball is detected and the deviation of the irradiation position of the laser light due to the movement of the eyeball is corrected.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on the illustrated embodiments. FIG. 1 is a configuration diagram of the present embodiment. An image rotor 2, a perforated mirror 3, and an aperture 4 are arranged on the optical path behind the objective lens 1 facing the eye E to be inspected. An image stabilizer 5 is provided behind the aperture 4, and lenses 6 and 7, a galvanometric mirror 8, lenses 9, 10 and a galvanometric mirror 11 are arranged in order from the eye E side. In the image stabilizer 5, the galvanometric mirrors 8 and 11 are conjugated to the perforated mirror 3 by the lenses 6, 7, 9 and 10. The galvanometric mirror 8 has a rotation axis in a direction orthogonal to the paper surface, the galvanometric mirror 11 has a rotation axis parallel to the paper surface orthogonal to the rotation axis, and the galvanometric mirrors 8 and 11 are operation rods. It is connected to 12 and its rotation angle can be changed from the outside.

An observation optical system 13 is provided on the optical path in the reflecting direction of the galvanometric mirror 11, a focusing lens 14 and a dichroic mirror 15 which are movable along the optical path are sequentially arranged, and the reflecting direction of the dichroic mirror 15 is set. Dichroic mirror 1 on the optical path of
6, a lens 17 and a television camera 18 are arranged, and the output of the television camera 18 is connected to a monochrome television monitor 20 via a recording device 19.

On the optical path in the reflection direction of the dichroic mirror 16, a mirror 21, a lens 22, and a one-dimensional CCD sensor 23 with an image intensifier are arranged to form a blood vessel detection system 24. The output is connected to the tracking controller 25 and the galvanometric mirror 8 via a signal processing unit (not shown).

A lens 26, an aperture 27, a zoom lens 28a movable along the optical path, a lens 28b, and a semiconductor laser light source 29 are arranged on the optical path behind the dichroic mirror 15, and the semiconductor laser light source 29 is laser-driven. System controller 3 via circuit 30
1 output is connected to the system controller 31,
Output of tracking controller 25, recording device 19
And the inputs of the one-dimensional CCD sensor 23 are connected together.

On the optical path in the incident direction of the perforated mirror 3,
Relay lenses 32 and 33, ring slit 34, field lens 35, mirror 36, condenser lens 37,
An illumination light source 39 including an excitation filter 38, a halogen lamp, and the like is arranged to configure an illumination optical system.

As shown in FIG. 2, the dichroic mirror 15 has a wavelength division characteristic of transmitting light having a wavelength of 600 nm or more and reflecting light having a wavelength of less than that. On the other hand, the dichroic mirror 16 has a wavelength division characteristic as shown in FIG. It has a wavelength division characteristic of transmitting a light beam having a wavelength of 500 nm or more and reflecting a light beam having a wavelength of less than 500 nm. Further, as shown in FIG. 4, the excitation filter 38 has a characteristic of transmitting a light beam having a wavelength of 500 nm or less and blocking a light beam having a wavelength of more than 500 nm, and is inserted into the optical path of the illumination optical system under the control of the system controller 31. It is supposed to be removable.

At the time of fundus observation, the excitation filter 38 is retracted from the optical path to the position A, and the illumination light source 39 is turned on. Illumination light from the illumination light source 39 is imaged on the ring slit 34 via the condenser lens 37, the mirror 36, and the field lens 35. The light flux having the ring slit 34 as a secondary light source is once focused as a ring slit image on the perforated mirror 3 by the relay lenses 32 and 33, passes through the image rotator 2, and is focused on the pupil of the eye E by the objective lens 1. Is imaged again as a ring slit image on the eye E to illuminate the fundus Ea of the eye E substantially uniformly. In addition,
The field lens 35 has a function of efficiently guiding the light flux into the subject's eye.

The reflected light from the fundus Ea returns through the same optical path, passes through the central opening of the perforated mirror 3, the aperture 4, the image stabilizer 5, passes through the focusing lens 14 of the observation optical system 13, and is reflected by the dichroic mirror 15. Then, the dichroic mirror 16 divides it into two directions.
The light flux transmitted through the dichroic mirror 16 is reflected by the lens 1
The image is formed by the television camera 18 as a fundus image Ea ′ through 7.
It is displayed on the TV monitor 20. The inspector is a TV monitor 2
While observing 0, the alignment of the device and the selection of the imaging site are performed.

The reflected light beam from the dichroic mirror 16 is reflected by the mirror 21 and the lens 22 of the blood vessel detection system 24.
A blood vessel image Pv that is larger than the fundus image Ea ′ captured by the television camera 18 is formed on the one-dimensional CCD sensor 23 with an image intensifier.

On the other hand, the semiconductor laser light source 29 has a wavelength of 83
It emits 0 nm laser light, and this light flux
8b, 28a, an aperture 27, a lens 26, a dichroic mirror 15 of the observation optical system 13, and a focusing lens 14, an image stabilizer 5, an aperture 4, an opening of a perforated mirror 3, an image rotator 2, and an objective lens 1. As described above, the fundus Ea of the eye E to be inspected is irradiated in a spot-like manner as a spot image S through the pupil of the eye E to be inspected.

In order to minimize the damage to the fundus tissue, it is desirable that the spot image S formed by the laser light be approximately the same as the width of the fundus blood vessel Ev. Therefore, in this embodiment, the zoom lenses 28a and 28b are moved along the optical path according to the blood vessel diameter to change the diameter of the spot image S from 40 μm to 200 μm. In addition, since the shape of the spot image S on the fundus Ea is generally elliptical due to the light distribution characteristics of the semiconductor laser, the major axis of the ellipse of the spot image S is made to coincide with the blood flow direction, and the spot image S on the blood vessel Ev. The irradiation energy density is reduced to minimize the heat damage to the irradiated blood vessels Ev.

The reflected light flux at the fundus Ea due to the laser light is
Although incident on the observation optical system 13, due to the wavelength division characteristics of the dichroic mirrors 15 and 16, the excitation filter 37 is inserted into and removed from the optical path, and the semiconductor laser light source 29 is always reflected from the fundus Ea regardless of whether it is on or off. 500 nm of light
The following wavelengths reach the one-dimensional CCD sensor 23, and
Wavelengths from nm to 600 nm reach the TV camera 18. Therefore, the fundus Ea generated by the semiconductor laser light source 29
The reflected light flux at does not reach the television camera 18 and the one-dimensional CCD sensor 23. Therefore, one-dimensional CC
The D sensor 23 captures only the blood vessel image Ev ′ by the illumination light source 39, and the received light signal is the tracking controller 2
5, the amount of movement of the blood vessel image Ev ′ in the arrangement direction of the sensor elements is calculated, and the involuntary eye movement of the eye E to be examined in this direction is monitored.

On the other hand, the television camera 18 has a light source 3 for illumination.
Only the fundus image Ea ′ by 9 is captured, and the television monitor 20
Is projected on. While observing the television monitor 20, the examiner moves the focusing lens 14 along the optical path to focus the fundus image Ea ′. At this time, the laser light is focused as a spot image S on the surface F of the aperture 27 conjugate with the fundus Ea by the zoom lenses 28a and 28b,
The conjugate relationship is adjusted via the lens 26. Therefore,
When the examiner moves the focusing lens 14 in the direction of the arrow, the image pickup surface of the television camera 18, the one-dimensional CCD sensor 2
Since the image pickup plane of 3 and the focal planes F of the zoom lenses 28a and 28b are simultaneously conjugated with the fundus Ea, the spot image S on the fundus Ea, the fundus image Ea 'of the television camera 18, and the one-dimensional CCD.
The blood vessel image Ev ′ received by the sensor 23 is focused at the same time.

First, the examiner injects the liposome encapsulating the fluorescent dye into the body from the vein blood vessel of the subject. The fluorescent dye used here emits green fluorescence having a peak near 520 nm when excited by blue light such as fluorescein. While waiting for the photopigment to reach the circulatory system in the subject's eye, the fundus image Ea ′ by the illumination light source 39 is observed to align the device, and then the blood vessel Ev to be imaged.
Select.

FIG. 5 shows an observation visual field of the examiner, and a reticle R showing the irradiation site by the spot image S can be confirmed at the center of the visual field. In the visual field of the examiner, the reticle R is fixed at the center of the visual field, and the fundus image Ea ′ is recognized as moving. When the operating rod 12 is operated to rotate the galvanometric mirrors 8 and 11, the observation region of the fundus image Ea ′ moves. The examiner matches the blood vessel Ev to be imaged with the reticle R. Then
When the image rotator 2 is rotated, the fundus image Ea 'is rotated in the direction of arrow E about the reticle R that is the center of the visual field. The examiner may match the traveling direction of the blood vessel Ev to be imaged with the direction of the axis C. In this way, when the laser light irradiation site is selected by the reticle R, the one-dimensional CCD sensor 23 of the blood vessel detection system 24 magnifies and images the rod-shaped region I in the axis D direction orthogonal to the C axis. is doing.

Even if the eyeball moves in the direction of the axis C during photographing, there is no problem in photographing because the blood vessel Ev is almost parallel to the direction of the axis C and the fluorescent dye flows downstream. However, when moving in the direction of the axis D, the laser light deviates from the blood vessel Ev to be imaged, and a fluorescent image of a desired site cannot be obtained. In this embodiment, the blood vessel detection system 24 and the image stabilizer 5 work together to perform one-dimensional tracking in the axis D direction.

After selecting the blood vessel Ev to be imaged by the reticle R, the examiner inputs a tracking start signal to the system controller 31. The system controller 31 outputs a synchronization signal S1 to the one-dimensional CCD sensor 23, and a light reception signal from the one-dimensional CCD sensor 23 is output to the tracking controller 25 via a signal processing unit (not shown) in synchronization with the synchronization signal S1. A drive signal S2 for the galvanometric mirror 8 is created based on this signal.

FIG. 6 is a block circuit diagram of the control unit of the galvanometric mirror 8. The received light signal of the one-dimensional sensor 23 consisting of 256 pixels is amplified by the amplifier 41 and then the A / D converter 42. Is converted into a digital signal by. In the adder 43, one of the one-dimensional sensors 23
The outputs from the 128th pixel and the outputs from the 129th to 256th pixels are added together, and the comparator 44
In the one-dimensional CCD sensor 2 by comparing the two outputs in
The moving direction of the blood vessel image Ev ′ of 3 is detected. Further, the amount of movement is obtained by multiplying the signal indicating the moving direction by a predetermined step size. The calculation result of the comparator 44 is the amplifier 45.
After being amplified by, the signal is converted into an analog signal by the D / A converter 46. The tracking controller 25 is a blood vessel image
The drive signal S2 of the galvanometric mirror 8 is created based on the moving amount and moving direction of Ev ', and the position of the blood vessel image Ev' of the one-dimensional CCD sensor 23 is controlled to be constant. In actual shooting, this tracking is repeated at a frequency of 1 kHz to keep the relationship between the position of the blood vessel Ev, which is the shooting target that moves with the eye movement, the irradiation position of the laser light and the imaging area of the television camera 18, constant. ing.

When the tracking is normally performed, the tracking controller 25 operates as the system controller 31.
Then, the system controller 31 outputs the preparation signal S3 for urging the user to take a picture, and displays that the system controller 31 is in a standby state in which laser light irradiation is possible.

After confirming this display, the examiner inputs a photographing start signal from the system controller 31. Before taking a picture, the system controller 31
The output of the laser light, the diameter of the light beam, the pulse width, the irradiation time interval, the photographing timing, etc. are set or changed.

When a photographing start signal is input to the system controller 31, the excitation filter 38 is inserted at the position B in the optical path, and the laser drive circuit 30 applies a preset voltage to the semiconductor laser light source 29. The laser light from the semiconductor laser light source 29 irradiates the fundus blood vessel Ev designated by the reticle R in a dot shape as shown in FIG. The liposomes in the bloodstream are melted by the heat energy of the laser light,
The fluorescent dye is released into the bloodstream within the blood vessel Ev. During this period, the luminous flux from the illumination light source 39 is transmitted by the excitation filter 38 to 50
The blue excitation light having a wavelength of 0 nm or less is used to illuminate the fundus Ea. The blue excitation light excites the fluorescent dye melted from the liporim to emit fluorescence. The reflected light flux from the fundus Ea returns through the same optical path, and the central opening of the perforated mirror 3
500 nm to 600 nm by the dichroic mirrors 15 and 16 through the aperture 4, the image stabilizer 5 and the focusing lens 14 of the observation optical system 13.
Only the light flux in the wavelength band of is passed through the lens 17, is captured by the television camera 18 as a fluorescent image, and is displayed on the television monitor 20 via the recording device 19.

A timer is provided inside the system controller 31, and this timer is started at the same time as the irradiation of the laser beam to measure the elapsed time. When the examiner reaches the preset photographing time, the system controller 31 outputs the recording / reading signal S4 to the recording device 19, and the recording device 19 records the image signal from the television camera 18 together with the photographing time.

A film camera may be used in place of the television camera 18 for fluorescent photography. A finder optical system may be used instead of the television monitor 20 when observing the fundus image Ea '.

In this embodiment, since fluorescence is not emitted from the blood vessel Ev which is not irradiated with the laser light, it is possible to obtain a fine blood vessel image Ev 'with high contrast. Also the fundus
Even when conditions such as the blood vessel diameter of Ea and the blood flow state of the fundus Ea change, the irradiation time of the laser light and the fluorescence image capturing are independently set at any time so that the optimum fluorescence image can be obtained. It can be set. For example, when laser light is continuously irradiated, the laser light is automatically irradiated for a preset irradiation time. At this time, fluorescent blood vessel images Ev ′ can be continuously captured in the downstream direction from the spot image S as shown in FIG. 7. In addition, a method of recording a plurality of fluorescent images with pulsed laser light and adding and displaying the fluorescent images obtained for each pulse is also used to display a series of fluorescent blood vessel images Ev ′ as described above.
Can be obtained. Regarding the alignment at the time of superimposing images, this fundus camera always tracks from the start to the end in the direction of the axis D perpendicular to the blood flow, and records all fluorescence images with the desired fundus blood vessel Ev as the center. Cage,
Since it is sufficient to perform the alignment only in the same axis C direction as the blood flow, the operation is extremely simple.

As described above, in this embodiment, the one-dimensional tracking in the direction of the axis D is performed.
By using a two-dimensional CCD sensor instead of 3, the two-dimensional movement amount of the blood vessel image Ev 'is calculated, and the directions of the two galvanometric mirrors 8 and 11 are changed at the same time based on the movement amount, so that the two-dimensional direction is changed. It is also possible to perform tracking. By performing two-dimensional tracking, it is possible to record the fluorescent blood vessel image Ev 'of the same region without depending on the movement of the eyeball, so that it is possible to easily and accurately add and display a plurality of fluorescent blood vessel images Ev'. .

In the present embodiment, the photographing is started after a predetermined elapsed time which has been set in advance from the irradiation of the laser light from the semiconductor laser light source 29. However, it may take time to fluoresce after being irradiated with laser light, and if the set imaging start time is too short, the desired fluorescent blood vessel image Ev '
There are cases where you cannot get a profit. Therefore, as shown in FIG. 8, a brightness signal monitor 51 may be further connected to the output of the television camera 18 to monitor whether or not the fluorescence from the fundus Ea reaches the television camera 18. Semiconductor laser light source 2
When the laser light is emitted from 9, the brightness signal monitor 51
Extracts an image signal in the vicinity of the center of the image pickup element of the television camera 18 from the image signal of the television camera 18, and outputs it as a luminance signal S5 to the system controller 31.

The system controller 31 calculates the average value or the maximum value of the luminance signal S5, and when this value exceeds a preset value, the timer inside the television camera 18 is started and the photographing time preset by the examiner. After the elapse, the fluorescent image is recorded in the recording device 19. Since the center of the image pickup element of the television camera 18 receives the fundus reflected light flux having high brightness due to the spot image S, by monitoring the image signal of the center of the image pickup element of the television camera 18, fluorescence is emitted from the fundus Ea. Since it is possible to accurately grasp the timing to be applied, regardless of the irradiation conditions of the laser light, the state of the blood vessels Ev of the fundus Ea, etc.
It is possible to always take a fluorescence image at a fixed timing.

[0037]

As described above, since the fundus camera of the present invention can accurately irradiate only the blood vessel to be photographed with the laser beam, it does not emit fluorescence from other parts, and thus is desirable. It is possible to reliably capture a detailed fluorescence image of the fundus oculi blood vessels.

[Brief description of drawings]

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

FIG. 2 is a wavelength spectral distribution diagram of a dichroic mirror.

FIG. 3 is a wavelength spectral distribution diagram of a dichroic mirror.

FIG. 4 is a wavelength spectral distribution diagram of an excitation filter.

FIG. 5 is an explanatory diagram of an observation fundus image.

FIG. 6 is a block circuit configuration diagram of a galvanometric mirror control unit.

FIG. 7 is an explanatory diagram of a fluorescence image of a fundus blood vessel.

FIG. 8 is a configuration diagram of a luminance signal processing unit.

[Explanation of symbols]

 2 image rotator 5 image stabilizer 8 and 11 galvanometric mirror 14 observation optical system 18 TV camera 20 TV monitor 23 one-dimensional CCD sensor 24 blood vessel detection system 25 tracking controller 29 laser light source 31 system controller 38 exciter filter 39 illumination light source

Claims (2)

[Claims] 1. An illuminating means for illuminating the fundus of an eye to be examined in a first wavelength band, an observation and photographing optical system for observing or photographing the fundus in a second wavelength band different from the first wavelength band, and a subject to be examined. In a fluoresceinable fundus camera provided with an irradiation means for injecting a fluorescent dye in a state in which the fluorescence emission reaction is suppressed and irradiating laser light for releasing the suppression of the fluorescence emission reaction, The imaging optical system has a deflection optical system for deflecting the irradiation position of the laser light and an eye movement detecting means for detecting the eye movement of the eye to be inspected, and based on the information obtained by the eye movement detecting means, the deflection is performed. A fundus camera characterized by automatically tracking the fundus by driving an optical system. 2. The fundus camera according to claim 1, wherein the eye movement detecting means detects the eye movement by detecting the position of the fundus blood vessel.