JP3778274B2 - Fundus camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fundus camera capable of photographing a fundus site to be photographed this time while accurately matching a fundus region photographed last time.
[0002]
[Prior art]
Conventionally, a fundus camera presents a fixation target to the eye to be examined, the working distance of the apparatus main body (the distance in the optical axis direction from the apex of the cornea to the objective lens of the apparatus main body) with respect to the eye to be examined, and the light of the apparatus main body with respect to the eye to be examined After alignment with the vertical and horizontal positions in the axial direction and positioning of the apparatus main body with respect to the eye to be examined, the line of sight of the eye to be examined is guided to the fundus site to be photographed, and the fundus site is photographed.
[0003]
[Problems to be solved by the invention]
However, using the same fundus camera, when it is desired to recapture a previously captured fundus region, even if the apparatus main body is positioned with respect to the eye to be examined in the same manner as previously photographed, and the direction of the line of sight of the eye to be examined is determined. Even if it is guided using a fixation target in the direction of the line of sight previously taken, due to subtle positional differences between the eye to be examined and the main body of the device, such as how to place the chin on the chin rest and how to place the forehead on the forehead rest The same part of the fundus as previously photographed cannot be photographed, and even when photographed at the same magnification, the thickness of the blood vessel differs between the fundus image photographed before and the fundus image photographed this time, etc. There is a problem that the fundus site to be imaged this time cannot be imaged accurately by matching the fundus site imaged last time.
[0004]
In particular, when photographing a fundus region that cannot be captured by eye gaze guidance, the same fundus region was positioned by eye while referring to the panoramic image obtained by panoramic imaging. It was difficult to accurately match the site.
[0005]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fundus photographing apparatus capable of photographing the fundus region to be photographed this time while accurately matching the fundus region photographed last time. Objective.
[0006]
[Means for Solving the Problems]
The fundus camera according to claim 1 is obtained by comparing the luminance of the fundus image captured last time with the luminance of the currently displayed fundus image for each pixel and dividing the number of matching pixels by the total number of pixels. Image matching processing means for calculating the matching rate, driving means for driving the apparatus main body incorporating the photographing optical system, and a matching rate reference value set in advance, and the matching rate exceeds the matching rate reference value Control means for automatically controlling the drive means in a direction in which the matching rate increases, the image comparison processing means calculates the matching rate in real time, and the control means has the matching rate maximized. At this point, the drive of the drive means is stopped .
The fundus camera according to claim 2, wherein the image comparison processing unit pays attention to the blood vessels of the fundus image captured last time and the fundus image captured this time before performing the calculation of the matching rate, and a direction extending with the thickness of the blood vessel. The angle of the blood vessel is determined, and the control unit controls the driving unit in a direction in which the fundus image captured this time coincides with the fundus image captured last time based on the determination result.
The fundus camera according to claim 3, wherein the photographing optical system includes a variable magnification lens, and the image comparison processing unit is currently displayed on a fundus image photographed last time before calculating the matching rate. The control means drives the variable magnification lens so that the magnification of the photographing optical system matches the magnification determined by the calculation, and the control means controls the magnification lens of the variable magnification lens. The driving means is controlled in a direction in which the fundus image captured this time after driving coincides with the fundus image captured last time.
The fundus camera according to claim 4 includes a storage unit that stores a fixation target position corresponding to a fundus site at the time of previous photographing and a position of the apparatus main body including the photographing optical system, and the control unit includes: Before the calculation of the matching rate, the driving unit is controlled in a direction in which the fundus site imaged this time coincides with the fundus site imaged last time based on the storage information of the storage unit.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
[0011]
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1
FIG. 1 shows an example of a fundus camera according to the present invention, in which a non-mydriatic type is shown.
<Configuration>
In FIG. 1, 1A is a base, 1B is a stand, 1C is an apparatus body, 2 is a chin rest, 3 is a forehead support, 4 is an external fixation lamp, 5A is a joystick, 5B is a shooting switch, and 6 is a TV camera. These configurations are known. Reference numeral 7 denotes a rear surface (surface on the examiner side) of the apparatus main body 1C, and reference numeral 8 denotes a liquid crystal display (display means) as a monitor provided on the rear surface 7. In FIG. 2, reference numeral 9 denotes a control device, and the apparatus main body 1C incorporates a pulse motor PM ′ as drive means driven by manual operation of the joystick 5A.
<Optical system>
Inside the apparatus main body 1C, as shown in FIG. 2A, an illumination optical system 10 that illuminates the fundus Er of the eye E, an imaging optical system 20 that images the fundus Er, an observation optical system 20 ′, and a fundus Er And an internal fixation target projection optical system 50 that projects the fixation target to fix the eye to be examined, and an alignment optical system (not shown) that aligns the apparatus main body 1C with the eye E to be examined.
[0012]
The illumination optical system 10 includes an objective lens 11, a perforated mirror 12, a relay lens 13, a reflection mirror 14, a relay lens 15, and a ring aperture plate 16 having a ring aperture 16A maintained in a conjugate relationship with the pupil Ea of the eye E to be examined. It has a dichroic mirror 17, condenser lenses 18a and 18b, a visible illumination light source 19a such as a halogen lamp or a xenon lamp, and an infrared illumination light source 19b such as an infrared laser diode.
[0013]
The illumination optical system 10 turns on the infrared illumination light source 19b during observation to illuminate the fundus with infrared light, and illuminates the fundus Er with visible light using the visible illumination light source 19a during imaging.
[0014]
That is, the visible light emitted from the visible illumination light source 19a at the time of photographing is the condenser lens 18a, the dichroic mirror 17, the ring aperture 16A of the ring aperture plate 16, the relay lens 15, the reflection mirror 14, the relay lens 13, and the perforated mirror 12. The eye E is guided through the objective lens 11 to illuminate the fundus Er of the eye E.
[0015]
Further, during observation, infrared light emitted from the infrared illumination light source 19b is transmitted through the condenser lens 18b, the dichroic mirror 17, the ring opening 16A of the ring opening plate 16, the relay lens 15, the reflection mirror 14, the relay lens 13, and the hole. The eye 12 is guided through the mirror 12 and the objective lens 11 to illuminate the fundus Er of the eye E.
[0016]
The photographing optical system 20 includes an objective lens 11, a variable magnification lens ML, a focusing lens 21, an imaging lens 22, and a reflection mirror 23, and the TV camera 6 includes an image sensor 6a. The TV camera 6 is optically connected to the photographing optical system 20 via a relay lens system 25A including a field lens 24, a reflection mirror 25, and a relay lens 26. The imaging element 6a is maintained in an optically conjugate relationship with the fundus Er. The zoom lens ML is driven and controlled by a pulse motor (drive means) PM (not shown).
[0017]
The observation optical system 20 ′ includes a dichroic mirror 23 ′, a reflection mirror 25 ′, a relay lens 26 ′, and a TV camera 6 ′, and the TV camera 6 ′ includes an image sensor 6a ′. The dichroic mirror 23 'has a characteristic of reflecting infrared light and transmitting visible light. The imaging element 6a ′ is maintained in an optically conjugate relationship with the fundus Er.
[0018]
As shown in FIG. 3, the internal fixation target projection optical system 50 includes a light emitting diode 51a disposed in the center, eight light emitting diodes 51b to 51i disposed in the circumferential direction around the light emitting diode 51a, 4 includes a mask plate 52 having pinholes 52a to 52i provided facing the respective light emitting diodes 51a to 51i, a half mirror 53, an imaging lens 22, a focusing lens 21, and an objective lens 11.
[0019]
The light from the light emitting diodes 51a to 51i is projected as a fixation target on the fundus Er via the pinholes 52a to 52i, the half mirror 53, the imaging lens 22, the focusing lens 21, and the objective lens 11, and pinholes to the fundus Er. An image is formed, and the subject visually recognizes the fixation target, thereby fixing the visual axis of the subject's eye. Depending on which of the pinholes 52a to 52i is lit, the optical axis O of the imaging optical system 20 is determined. The fixation direction of the subject with respect to is changed, and thereby the part of the fundus Er to be imaged is changed. For example, when each of the light emitting diodes 51a to 51i emits light, each fundus region Er1 to Er9 is photographed as shown in FIG.
<Control device>
The control device 9 is connected to the shooting switch 5B of the joystick 5A and the TV cameras 6 and 6 ′, and the on / off signal of the shooting switch 5B and the video signals of the TV cameras 6 and 6 ′ are input. The control device 9 is connected to an operation means 70 such as a mouse and a keyboard, a still video recorder 71 as an image recording / reproducing apparatus, a memory 72 as an information storage means, and a frame memory 73. The frame memory 73 stores a fundus image previously captured. In the memory 72, fixation position information and position information of the photographing apparatus main body are stored in association with images stored in the frame memory 73 serving as image storage means.
[0020]
In order to observe the eye to be examined in real time, the control device 9 is connected to a frame memory 74 that stores an image of the eye to be examined that is captured by the TV camera 6 ′. The control device 9 updates the fundus image data in the frame memory 74 in real time, outputs the updated image data to the monitor 8 via the image processing circuit 75, and displays the image captured by the TV camera 6 ′ on the screen. 8A is displayed in real time.
[0021]
The control device 9 is connected to an image comparison processing unit 100 that compares the fundus image captured last time with the fundus image captured this time. When it is desired to match the fundus region photographed last time with the fundus region photographed this time, the fundus image ErK corresponding to the fundus region photographed last time is displayed on the screen 8A of the liquid crystal display 8 by the operation means 70 as shown in FIG. Let When photographing this time, the fundus image ErG projected by the photographing optical system 20 is displayed on the screen 8A adjacent to the previously photographed fundus image ErK. The photographer moves the apparatus main body 1C by manual operation of the joystick 5A while viewing the fundus image ErG currently projected by the photographing optical system 20 and the previously photographed fundus image ErK when photographing this time.
[0022]
The image comparison processing means 100 obtains a matching rate between the fundus image ErG currently projected by the photographing optical system 20 during the movement and the fundus image Erk photographed last time. Here, the matching rate is, for example, comparing the luminance of the fundus image ErK captured last time for each pixel with the luminance of the currently displayed fundus image ErG, and dividing the number of matching pixels by the total number of pixels. Value.
[0023]
The control device 9 has a preset matching rate reference value, and when the matching rate obtained by the calculation exceeds the matching rate reference value, the pulse motor PM ′ as a driving unit automatically increases in the direction in which the matching rate increases. To control. As a result, the apparatus main body 1C is driven, and during that time, the image comparison processing means 100 obtains the matching rate in real time, and when the matching rate reaches the maximum value, the control device 9 stops driving the pulse motor PM ′. .
[0024]
Then, by operating the photographing switch 5B, it is possible to photograph the fundus region to be photographed this time, with the fundus region accurately photographed last time.
[0025]
Second Embodiment of the Invention
Here, as shown in FIG. 7, the image comparison processing unit 100 pays attention to the blood vessel 101 between the fundus image ErK captured last time and the fundus image ErG currently displayed by the imaging optical system 20, and determines the thickness of the blood vessel 101. The extending direction and the angle of the junction 102 of the blood vessel 101 are obtained for the fundus image ErK captured last time and the fundus image ErG currently displayed by the imaging optical system.
[0026]
Then, the virtual position of the nipple 103 is obtained, and the virtual nipple position 104 of the fundus image ErK captured last time is matched with the virtual nipple position 105 of the fundus image ErG currently displayed by the imaging optical system 20. The control device 9 automatically drives the pulse motor PM ′ based on the processing result of the image comparison processing means 100.
[0027]
If the virtual nipple position 104 of the fundus image ErK photographed last time and the virtual nipple position 105 of the fundus image ErG currently projected by the photographing optical system 20 approximately coincide with each other, the last photographed fundus image ErK and the photographing optical system 20 are displayed. The matching rate with the currently projected fundus image ErG is obtained, and the control device 9 drives and controls the pulse motor PM ′ in a direction in which the matching rate increases. Meanwhile, the image comparison processing unit 100 obtains the matching rate in real time, and when the matching rate reaches the maximum value, the control device 9 stops driving the pulse motor PM ′.
[0028]
Next, by operating the photographing switch 5B, it is possible to photograph the fundus region to be photographed this time while accurately matching the fundus region photographed last time.
[0029]
Embodiment 3 of the Invention
Here, the control device 9 moves the variable magnification lens ML so that the photographing magnification is set to the low magnification side which is the default value. As shown in FIG. 8, the control device 9 displays the fundus image ErG currently being displayed by the photographing optical system 20 on the screen 8 </ b> A. At the same time, the fundus image ErK taken last time is displayed in parallel on the screen 8A of the TV monitor. Then, the portion indicated by the broken line HA of the fundus oculi image ErG is copied and enlarged, and the enlarged image ErG ′ is displayed on the screen 8A.
[0030]
The photographer manually operates the joystick 5A and moves the apparatus main body 1c while comparing the magnified image ErG ′ with the previously photographed fundus image ErK on the screen 8A. Then, when a portion similar to the enlarged image ErG ′ and the fundus image ErK captured last time is found on the screen 8A, the manual operation is stopped.
[0031]
Next, the image comparison processing means 100 determines the thickness of the blood vessel 101 in the vicinity of the branch 102 of the blood vessel 101 taken last time and the thickness of the blood vessel 101 in the vicinity of the corresponding branch 102 that is currently displayed by the imaging optical system 20, and The magnification of the fundus image ErK taken last time with respect to the fundus image ErG currently displayed is obtained.
[0032]
The control device 9 drives the variable magnification optical system ML so that the magnification of the photographing optical system 20 matches the magnification obtained by the calculation. Next, the image processing unit 100 obtains a matching rate between the fundus image ErK captured last time and the fundus image ErG currently displayed by the imaging optical system 20.
[0033]
When this matching rate exceeds the matching rate reference value, shooting is performed by operating the shooting switch 5B.
[0034]
Embodiment 4 of the Invention
When the operation unit 70 shown in FIG. 2 is operated and the previously-captured fundus image ErK stored in the frame memory 73 is read out to the image processing device 75, the control device 9 is stored in the memory 72 and read out. The fixation position information corresponding to the fundus image ErK and the position information of the apparatus main body 1C are read.
[0035]
Based on the fixation position information, the control device 9 moves the external fixation lamp 4 or lights any one of the internal fixation lamps 51a to 51i, and thereby the fundus in which the line of sight was previously captured. You are guided to show the part.
[0036]
Next, the control device 9 drives the drive means PM ′ based on the position information of the photographing apparatus main body 1C, and sets the apparatus main body 1C at the position of the apparatus main body 1C when the previous photographing was performed.
[0037]
The image comparison processing unit 100 obtains a matching rate between the fundus image ErK photographed last time and the fundus image ErG currently projected by the photographing optical system 20, and when the matching rate exceeds the matching rate reference value, the photographing switch When 5B is operated, shooting is performed.
[0038]
【The invention's effect】
According to the present invention, there is an effect that it is possible to photograph the fundus region to be photographed this time while accurately matching the fundus region photographed last time.
[Brief description of the drawings]
FIG. 1 is an external view of a fundus camera according to the present invention.
FIG. 2 is a diagram showing a main configuration of a fundus camera according to the present invention.
FIG. 3 is a diagram showing an arrangement of light emitting diodes shown in FIG. 2;
4 is a diagram showing an example of a mask plate shown in FIG. 2. FIG.
FIG. 5 is an explanatory diagram of a fundus site imaged by an imaging optical system.
FIG. 6 is a diagram illustrating an example for obtaining a matching rate based on a fundus image captured last time and a fundus image currently displayed by the imaging optical system.
FIG. 7 is an explanatory diagram for matching the fundus region by focusing on the blood vessel of the fundus image captured last time and the blood vessel of the fundus image currently displayed by the imaging optical system.
FIG. 8 is a diagram illustrating a state in which a fundus image currently projected by a photographing optical system and a previously captured fundus image are displayed in parallel on the screen.
[Explanation of symbols]
20 ... Shooting optical system 100 ... Image comparison processing means 1C ... Main body ErK ... Fundus image ErG taken last time ... Fundus image currently displayed by the shooting optical system

Claims (4)

Image comparison processing means for calculating the matching rate obtained by comparing the brightness of the fundus image captured last time and the brightness of the currently displayed fundus image for each pixel and dividing the number of matching pixels by the total number of pixels And a driving means for driving the apparatus main body incorporating the photographing optical system, and having a preset matching rate reference value and automatically increasing the matching rate when the matching rate exceeds the matching rate reference value. Control means for controlling the driving means, wherein the image comparison processing means calculates the matching rate in real time, and the control means drives the driving means when the matching rate becomes maximum. A fundus camera characterized by being stopped . The image comparison processing means determines the width of the blood vessel and the direction in which the blood vessel extends and the angle at which the blood vessel splits by paying attention to the blood vessel between the fundus image taken last time and the fundus image taken this time before calculating the matching rate. , the control means fundus camera according to claim 1, characterized in that for controlling the drive means in the direction corresponding to the fundus image fundus image photographing time based on the judgment result is the last shot. The photographing optical system has a variable magnification lens, and the image comparison processing means obtains a magnification of a fundus image currently being displayed with respect to a fundus image captured last time by calculation before calculating the matching rate, The control means drives the zoom lens so that the magnification of the photographing optical system matches the magnification obtained by the calculation, and the control means takes a previous image of the fundus image to be taken this time after driving the zoom lens. The fundus camera according to claim 1 , wherein the driving unit is controlled in a direction coinciding with the fundus image . A storage unit that stores a fixation target position corresponding to a fundus region at the time of previous imaging and a position of the apparatus main body including the imaging optical system; and the control unit performs the calculation of the matching rate before calculating the matching rate 2. The fundus camera according to claim 1, wherein the driving unit is controlled in a direction in which a fundus region imaged this time coincides with a fundus region imaged last time based on information stored in a storage unit .

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