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Claims  |
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We claim:
1. An ophthalmologic image compound apparatus, comprising:
first input means for introducing an eye fundus image photographed previous
to a view field measurement;
second input means for introducing data of the view field of an eye to be
examined by means of a view field measuring means;
correction means for correcting at least one of said eye fundus image and
said view field measuring data so that said eye fundus image and the view
field measuring data are in a one-to-one correspondence with each other;
and
compound means for compounding corrected eye fundus image and view field
measuring data corrected by said correction means.
2. An ophthalmologic image compound apparatus according to claim 1,
wherein:
said correction means includes means for correcting at least one of
magnification and distortion.
3. An ophthalmologic image compound apparatus according to claim 1,
wherein:
said compound means includes an optical system for optically compounding
said data.
4. An ophthalmologic image compound apparatus according to claim 1,
wherein:
said compound means includes a compound circuit for electrically
compounding said data.
5. An ophthalmologic image compound apparatus according to claim 1,
wherein:
said eye fundus image is a visible eye fundus image photographed under the
application of visible light.
6. An ophthalmologic image compound method, comprising:
an eye fundus image input step for introducing an eye fundus image
photographed previous to a view field measurement into an apparatus;
a view field data input step for introducing data of the view field on an
eye to be examined by means of a view field measuring means into the
apparatus;
a correction step for correcting at least one of said eye fundus image and
said eye field measuring data so that said eye fundus image and said view
field measuring data are in one-to-one correspondence with each other; and
a compound step for compounding corrected eye fundus image and view field
measuring data corrected by said correction means.
7. An ophthalmologic image compound method according to claim 6, wherein:
said correction step corrects at least one of magnification and distortion.
8. An ophthalmologic image compound method according to claim 6, wherein:
said compound step optically compounds said data.
9. An ophthalmologic image compound method according to claim 6, wherein:
said compound step electrically compounds said data.
10. An ophthalmologic image compound method according to claim 6, wherein:
said compound step is performed with a yellow spot of the eye fundus image
brought into coincidence with the center of the field of view of the view
field measuring data.
11. An ophthalmologic image compound method according to claim 6, wherein:
said compound step is performed with an optic disk of said eye fundus image
brought into coincidence with a blind spot of the view field measuring
data.
12. An ophthalmologic image compound method according to claim 6, wherein:
said compound step is performed with coordinates of a fixation target of
the view field measuring means made to correspond to a position of the
fixation target of an eye fundus photographing means.
13. An ophthalmologic image compound method according to claim 6, wherein:
said eye fundus image is a visible eye fundus image photographed under the
application of visible light.
14. An ophthalmologic image compound method according to claim 6, further
comprising:
a step for producing the eye fundus image with a wide view angle by
combining a plurality of eye fundus images.
15. An apparatus for performing an eye field measurement while outputting a
corresponding eye fundus image, comprising:
view field measuring means for measuring a view field of an eye to be
examined and producing view field measuring data;
eye fundus image input means for introducing an eye fundus image prepared
previous to a view field measuring operation;
correction means for correcting at least one of said eye fundus image and
said view field measuring data so that said eye fundus image and said view
field measuring data correspond to each other in a one-to-one
correspondence; and
output means for outputting a corresponding eye fundus image introduced by
said eye fundus image input means when the view field measuring operation
is being performed.
16. An apparatus for performing an eye field measurement according to claim
15, wherein:
said eye fundus image is a visible eye fundus image photographed under the
application of a visible light.
17. An apparatus for performing an eye field measurement according to claim
15, wherein:
said eye fundus image has a wide view angle produced by combining a
plurality of eye fundus images.
18. A method for performing an eye field measurement while outputting a
corresponding eye fundus image, comprising:
a view field measuring step for measuring a view field of an eye to be
examined and producing view field measuring data;
an eye fundus image input step for introducing an eye fundus image prepared
previous to a view field measuring operation;
a correction step for correcting at least one of said eye fundus image and
said view field measuring data so that said eye fundus image and said view
field measuring data correspond to each other in a one-to-one
correspondence; and
an output step for outputting a corresponding eye fundus image introduced
by said eye fundus image input step when the view field measuring
operation is being performed.
19. An ophthalmologic image compound method according to claim 18, wherein:
said correction step corrects at least one of magnification and distortion.
20. An ophthalmologic image compound method according to claim 18 further
comprising the step of optically compounding said corrected eye fundus
image and said corrected view field measuring data.
21. An ophthalmologic image compound method according to claim 18, further
comprising the step of electrically compounding said corrected eye fundus
image and said corrected view field measuring data.
22. An ophthalmologic image compound method according to claim 18, further
comprising the step of compounding said corrected eye fundus image and
said corrected view field measuring data with a yellow spot of the eye
fundus image brought into coincidence with center of the field of view of
the view field output.
23. An ophthalmologic image compound method according to claim 18, further
comprising the step of compounding said corrected eye fundus image and
said corrected view field measuring data with an optic disk of said eye
fundus image brought into coincidence with a blind spot of the view field
output.
24. An ophthalmologic image compound method according to claim 18, further
comprising the step of compounding said corrected eye fundus image and
said corrected view field measuring data with coordinates of a fixation
target of a view field measuring means made to correspond to a position of
the fixation target of an eye fundus photographing means.
25. An ophthalmologic image compound method according to claim 18, wherein:
said eye fundus image is a visible eye fundus image photographed under the
application of a visible light
26. An ophthalmologic image compound method according to claim 18, wherein:
said eye fundus image has a wide view angle produced by combining a
plurality of eye fundus images.
27. An ophthalmologic measuring system, comprising:
eye fundus photographing means for photographing and recording an eye
fundus image of an eye to be examined previous to performing a view field
measurement;
view field measuring means for measuring a view field of the eye;
output means for outputting said recorded corresponding eye fundus image
when the view field measurement is being performed; and
correction and compound means for correcting at least one of said eye
fundus image and said view field measuring data so that said eye fundus
image and said view field measuring data correspond to each other in a
one-to-one correspondence and for compounding the corrected eye fundus
image and view field measuring data.
28. An apparatus according to claim 27, wherein:
said eye fundus image is a visible eye fundus image photographed under the
application of a visible light.
29. An ophthalmologic measuring method, comprising:
an eye fundus photographing step for photographing and recording an eye
fundus image of an eye to be examined previous to performing a view field
measurement;
a view field measuring step for measuring a view field of the eye;
an output step for outputting said recorded corresponding eye fundus image
when the view field measurement is being performed; and
a correction and compound step for correcting at least one of said eye
fundus image and said view field measuring data so that said eye fundus
image and said view field measuring data correspond to each other in a
one-to-one correspondence and for compounding said corrected eye fundus
image and a view field measuring data.
30. An ophthalmologic measuring method according to claim 29, wherein:
said eye fundus image is a visible eye fundus image photographed under the
application of a visible light.
31. An ophthalmologic digital image compound method comprising:
an eye fundus image input step for introducing an eye fundus image
photographed by an eye fundus photographing means;
an image storing step for storing said introduced eye fundus image in a
digital manner;
a view field input step for introducing view field measuring data by means
of a view field measuring means;
a correction step for correcting at least one of said digitalized eye
fundus image and said view field measuring data so that said stored
digital eye fundus image and said view field measuring data correspond to
each other in a one-to-one correspondence; and
a compound step for compounding said corrected digital eye fundus image and
said view field measuring data in a digital manner.
32. An ophthalmologic digital image compound method according to claim 31,
wherein:
said method further comprises a step for storing a plurality of said eye
fundus images and for producing a digital eye fundus image having a wide
view angle by combining said plurality of eye fundus images.
33. An ophthalmologic digital image compound method according to claim 31,
wherein:
said introduced eye fundus image is photographed previous to the view field
measurement.
34. An ophthalmologic digital image compound method according to claim 31,
wherein:
said correction step corrects at least one of magnification and distortion.
35. An ophthalmologic digital image compound method according to claim 31,
wherein:
said compound step is performed with a yellow spot of the eye fundus image
brought into coincidence with the center of the field of view of the view
field measuring data.
36. An ophthalmologic digital image compound method according to claim 31,
wherein:
said compound step is performed with an optic disk of said eye fundus image
brought into coincidence with a blind spot of the view field measuring
data.
37. An ophthalmologic digital image compound method according to claim 31,
wherein:
said compound step is performed with coordinates of a fixation target of a
view field measuring means made to correspond to a position of the
fixation target of an eye fundus photographing means.
38. An ophthalmologic digital image compound method according to claim 31,
wherein:
said eye fundus image is a visible eye fundus image photographed under the
application of a visible light.
39. An ophthalmologic image compound apparatus, comprising:
means for introducing a plurality of eye fundus images thereinto;
means for combining said plurality of eye fundus images and making an eye
fundus image of a wide angle of view;
view field measuring means for measuring the field of view of an eye to be
examined;
means for superposing said eye fundus image of a wide angle of view and an
output of said view field measuring means, one upon the other, and
compounding said eye fundus image of a wide angle of view and the output
of said view field measuring means.
40. An ophthalmologic image compound apparatus according to claim 39,
further comprising:
means for correcting the distortion of said introduced eye fundus image.
41. An ophthalmologic image compound apparatus according to claim 39,
wherein:
said eye fundus image is a visible image obtained by applying visible light
to the eye fundus. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an ophthalmologic apparatus which can compound
the result of the measurement of the field of view of an eye to be
examined and relates a corresponding eye fundus image, and to a method of
compounding the image of the eye to be examined.
2. Related Background Art
Perimeters have heretofore been widely used to measure the fields of view
of examinees. The outline of such perimeters will hereinafter be described
with reference to FIG. 11 of the accompanying drawings. FIG. 11
illustrates a perimeter and its measuring state. The perimeter is fixedly
constructed on a table 1 so that the inner surface of a substantially
hemispherical dome 2 faces an examinee A and the outer surface of the dome
2 faces an examiner B. The examinee A has his face fixed by a fixing
member 3 provided on the inner surface of the dome. The examinee A
responds as to whether he could recognize an index presented successively
on the inner surface while watching a fixation target on the inner surface
of the dome 2. The examiner presents an index on the inner surface of the
dome 2 while monitoring the gazing point of the examinee A by means of a
loupe 4 provided on the outer surface side of the dome 2, and manually
records the result of the response on recording paper 5 disposed on the
table 1. FIG. 12 shows an example of the format of a view field chart on
the recording paper 5, and the result of the response is plotted by the
help of the view field chart printed on the recording paper 5, for
example, the view field chart C comprising a plurality of concentric
circles and four axes in directions to divide these concentric circles
into eight parts. Besides this method, use has been made of a method using
a TV monitor, instead of the recording paper 5, to plot measuring points
on a view field chart on the TV monitor.
Heretofore, when determining the correspondence between this output result
and the fundus of the eye to be examined, the examiner had to compare the
photograph of the eye fundus with view field data with his eyes on the
basis of the information of the center of the field of view and the blind
spot portion of the field of view this was inefficient.
On the other hand, there is also known an eye fundus perimeter in which the
view field measuring function is added to the eye fundus photographing
function and a photographing output having the result of view field
measurement imprinted on an eye fundus image is obtained. This perimeter
is such that infrared light is applied to an eye to be examined and the
examiner moves the index of visible light while observing the infrared eye
fundus image of the eye fundus image on a TV monitor, and plots by means
of a pen on a light-transmitting recording plate mounted in the apparatus
or plots by perforating recording paper, in accordance with the examinee's
response, and the plot image, together with the infrared eye fundus image,
is displayed on the TV monitor and simultaneously with the photographing
of the fundus of the eye, a final plot image is imprinted on the
photograph. This is described in detail, for example, in U.S. Pat. No.
4,279,478.
However, in this prior-art eye fundus perimeter, the eye fundus image
capable of being displayed is only the eye fundus image in real time
during the view field measurement, and the past eye fundus images or the
like cannot be displayed. That is, for example, even if there is a desire
to measure the field of view while observing the eye fundus image before a
disease has been cured, it is impossible with such a the prior-art type
device.
Also, the eye fundus image produced by infrared light is not clear and
further, infrared light penetrates more deeply into the interior of the
fundus of the eye than visible light and therefore, the resultant infrared
image is an image of the deeper portion of the fundus than the visible
image, and this has led to the problem that such image differs from the
outermost eye fundus image.
Also, during long-time view field measurement, it has been necessary to
apply infrared light to an eye to be examined.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an ophthalmologic
apparatus which can obtain a compound image of view field data and a
corresponding eye fundus image at any point in time differing from the
point in time of view field measurement.
It is another object of the present invention to provide an ophthalmologic
apparatus by which view field measurement is possible while the examiner
is watching an eye fundus image at any point in time differing from the
point in time the view field measurement (for example, an eye fundus image
in the past before a disease of the eye has been cured).
It is still another object of the present invention to provide an
ophthalmologic apparatus by which view field measurement is possible while
the examiner is watching an eye fundus photograph image by visible light.
It is yet still another object of the present invention to provide an
ophthalmologic apparatus by which view field measurement is possible
without the use of infrared light while the examiner is watching a
corresponding eye fundus image.
It is a further object of the present invention to provide an
ophthalmologic apparatus by which view field measurement is possible while
the examiner is watching a clear-cut corresponding eye fundus image.
It is still a further object of the present invention to provide an
ophthalmologic apparatus which can obtain a compound image of a
distortion-free eye fundus image of an eye to be examined and
corresponding view field data.
It is yet still a further object of the present invention to provide an
ophthalmologic apparatus which can obtain a compound image of a wide angle
of view.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the construction of a first embodiment of the present
invention.
FIG. 2 shows an example of the output of the first embodiment.
FIG. 3 shows the construction of a second embodiment of the present
invention.
FIG. 4 shows the construction of a third embodiment of the present
invention.
FIG. 5 shows an example of the output of the third embodiment.
FIG. 6 shows the construction of a fourth embodiment of the present
invention.
FIG. 7 illustrates the correction of the distortion of an eye fundus image.
FIG. 8 illustrates the making of a panorama eye fundus image.
FIG. 9 illustrates the compounding of an eye fundus image and a view field
chart.
FIG. 10 shows an example of an eye fundus image having a morbid part.
FIG. 11 shows the whole of a perimeter according to the prior art.
FIG. 12 shows an example of the format of the view field chart.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
(Embodiment 1)
FIG. 1 shows the construction of a first embodiment of the present
invention, and more particularly shows the perspective construction of the
recording table 10 of a view field meter. Incorporated in the table 10 is
an optical system for projecting onto recording paper an eye fundus image
photographed by the use of light from a photographing light source which
emits visible light. This optical system comprises, in succession from the
light source 11, a removably mounted slide film 12 upon which the eye
fundus image falls, a relay lens 13, a reflecting mirror 14, a
magnification changing lens 15, a projection lens 16 and a reflecting
mirror 17 disposed in the optical path. The table 10 has an upper portion
thereof formed of a light-transmitting member such as a glass plate, and
recording paper 18 is interchangeably placed on that portion.
The slide film 12 on which the eye fundus image of an eye to be examined
has been photographed in advance is illuminated by the light source 11.
This light enters the magnification changing lens 15 via the relay lens 13
and the reflecting mirror 14. The eye fundus image on the slide film 12 is
not limited to an image photographed by an ordinary eye fundus camera, but
may also be an image which has been distortion-corrected or an eye fundus
image of a wide angle of view, as will be described later with respect to
Embodiment 4. The slide film 12 is finely movable in vertical and
horizontal directions, and alignment is effected so that the projected eye
fundus image may coincide with a view field chart C printed on the
recording paper 18. The magnification changing lens 15 has its focal
length freely variable from the exterior, and is adjusted so as to form an
eye fundus image of an appropriate size on the recording paper 18 on the
table 10. The light which has left the magnification changing lens 15
projects, via the projection lens 16 and the reflecting mirror 17, the eye
fundus image from the back surface of the recording paper 18 having a
light-transmitting type screen characteristic.
Since the view field chart C is printed on the recording paper 18, there is
obtained a compound image in which the projected eye fundus image and the
field chart C overlap each other. The recording paper 18 is freely
replaceable and can always be set at the same position if it is in accord
with a predetermined format. Even when use is made of recording paper of
another different format, it can be freely changed in its position so as
to be aligned with the eye fundus image. Usually, the recording paper is
disposed so as to correspond to the index presentation position of a view
field measuring device in a 1:1 correspondence and therefore, it need not
always have a chart printed thereon, and the result view field measurement
may be plotted on only the projected eye fundus image.
To make the projected eye fundus image coincident with the view field
chart, the slide film 12 and the magnification changing lens 15 are
adjusted. As regards alignment, the slide film 12 is moved in vertical and
horizontal directions to bring the view field center of the view field
chart into coincidence with the yellow spot of the eye fundus image. When
there is a deviation between the blind spot of the view field chart found
in the course of measurement and the optic disk of the eye fundus image,
they are brought into coincidence with each other as required. Also, as
regards the adjustment of magnification, the inverse number of the
photographing magnification of the eye fundus image recorded on the slide
film 12 is set as the projection magnification.
FIG. 2 shows an example of a state in which the result of measurement is
being recorded. The view field chart C comprising a plurality of
concentric circles and radial straight lines equally dividing these
concentric circles and the projected eye fundus image D are compoundly
displayed in superposed relationship with each other on the recording
paper 18 placed on the table 10 in front of the examiner. The result of
the measurement of the view field is successively recorded as plots al-an
on the recording paper 18 by the examiner or is automatically recorded by
a machine.
(Embodiment 2)
FIG. 3 shows the construction of a second embodiment of the present
invention which is a modified form of the above-described embodiment. An
opaque material is used as recording paper 19, and an eye fundus image may
be projected from above the recording paper 19. A light source 21 is
installed above the recording paper 19 placed on a table 20, and a slide
film 22, a relay lens 23, a magnification changing lens 24 and a
projection lens 25 are disposed in succession on the optical path from the
light source 21 toward the table 20. The slide film 22 is finely movable
for alignment. These constituents have the same action as the previous
embodiment, that is, an eye fundus image can be formed on the recording
paper and the eye fundus image can be superposed on the view field chart C
on the recording paper 19.
In the constructions of the present and previous embodiments, it is also
possible to use the apparatus in such a manner that the view field chart
measured and recorded by an ordinary view field meter is mounted on the
apparatus of the present or previous embodiment and the examiner makes a
diagnosis while watching the compound image of the view field chart and
the eye fundus image.
(Embodiment 3)
Referring to FIG. 4 which shows a third embodiment of the present
invention. An illuminating system lens 32, an apertured mirror 33 and an
objective lens 34 are arranged in succession on an optical path passing
through a photographing light source 31 which is an eye fundus
photographing means and an eye E to be examined. The apertured mirror 33
is made conjugate with the pupil Ep of the eye E to be examined by the
objective lens 34. An imaging lens 35, a beam splitter member 36 and an
image pickup device 37 are arranged in succession rearwardly of the
apertured mirror 33 so that the eye fundus image may be formed on the
image pickup element of the image pickup device 37. The image pickup
element may preferably be an area sensor array such as a CCD which will
not engender distortion. The output of the image pickup device 37 is
connected to an image memorizing device 40, to which is also connected an
input device 30 for inputting an eye fundus image from the exterior. The
output of the image memorizing device 40 is connected to a display device
38 such as a liquid crystal TV, and a light pen 39 is connected to the
display device 38. The output of the image memorizing device 40 is also
connected to a video printer 41 and a stimulative light source driving
device 42. The stimulative light source driving device 42 is a moving
means for a stimulative light source 43, and a light beam from the
stimulative light source 43 is adapted to be directed into the optical
path to the eye fundus Er through the beam splitter member 36.
In the construction described above, the fundus of the eye to be examined
is first photographed before the field of view is measured. During the
photographing of the eye fundus, the photographing light source 31 flashes
and emits a visible light, which illuminating system lens 32, the
apertured mirror 33, the objective lens 34 and the pupil Ep. The eye
fundus image is formed on the image pickup element of the image pickup
device 37 via the pupil Ep, the objective lens 34, the apertured mirror
33, the imaging lens 35 and the beam splitter member 36 and is memorized
in the image memorizing device 40. The image memorizing device 40
memorizes a stationary video signal or digital signals. The content of the
image memorizing device 40 is displayed as a stationary eye fundus image
Er' on the display device 38.
If desired, photographing of the eye fundus may not be effected by the
apparatus of the present embodiment, but the eye fundus image photographed
by a discrete eye fundus photographing apparatus may be input from the
photographing angle of view, i.e., the magnification, and may be memorized
by the image memorizing device 40 and displayed on the display device 38.
By doing so, it also becomes possible to accomplish the measurement of the
field of view chiefly about a morbid part while watching the past eye
fundus image in which, as shown, for example, in FIG. 10, the morbid part
(e designates a bleeding spot, and f denotes a white spot) was
photographed.
The examiner carries out the measurement of the field of view while
watching the stationary eye fundus image being thus displayed, and when
the examiner designates a desired view field measuring point on the eye
fundus screen of the display device 38 by means of the light pen 39, the
stimulative light source driving device 42 moves the stimulative light
source 43 in conformity with the coordinates on the screen read by the
light pen, i.e., the designated position of the eye fundus image, and a
stimulative light is emitted toward the designated measuring point of the
eye fundus Er. A stimulating method is, for example, static perimeter.
This method is such that the luminance of the stimulative light is
visually unrecognizably weak at the beginning and is gradually intensified
and at a point of time whereat the examinee visually recognizes the
stimulative light, the examinee responds by means of a switch or the like
and the then luminance of the stimulative light and the then position of
the measuring point are introduced as a measured value and memorized. At
this time, view field measurement data are image-compounded and displayed
on the display device 38. Various display methods such as displaying a
point of a color conforming to the luminance of the stimulative light, and
changing the size of the point in conformity with the luminance or the
size of the index are within contemplation. In this manner, measurement of
numerous positions is progressed, and the final result of the measurement
is output to the video printer 41 on the basis of the content of the image
memorizing device 40. Without the view field measurement data being
displayed on the display device 38, the compound result may be output only
to the video printer 41.
FIG. 5 shows an example of the output, and curves a and b are isopters
prepared by linking respective measuring points together. These isopters,
if classified by color, will become easy to see.
The means for designating the measuring point is not limited to the light
pen, but may be one of various well-known input means, and for example,
the index may be moved by the use of input means such as a mouth, a track
ball, a digitizer, a touch panel or a keyboard.
(Embodiment 4)
FIG. 6 shows the construction of portions for compounding the eye fundus
image and view field measurement data, as a fourth embodiment of the
present invention, and in this figure, the perimeter and the transfer of
the data obtained from the perimeter are omitted. In FIG. 6, the reference
numeral 60 designates an eye fundus image input portion for reading and
inputting an image in which the eye fundus image of the eye to be examined
is recorded, which eye fundus image input portion may, for example, be a
35 mm slide scanner for reading a 35 mm slide and inputting the eye fundus
image. The reference numeral 61 denotes a system operation portion for the
operator to input a command to the system, the reference numeral 62
designates a view field data input portion for inputting the output signal
of view field measuring means which measures the field of view of the eye
to be examined, the reference numeral 63 denotes an image operation means
for carrying out numerous operations such as image processing and control
of the system, the reference numeral 64 designates an image memorizing
portion for memorizing the image, the reference numeral 65 denotes a
correction function memory portion for memorizing the correction function
of the distortions of various eye fundus cameras, and the reference
numeral 66 designates an image output portion such as a printer for
outputting the compound image of the corrected eye fundus image and the
view field data. This image output portion 66 print-outputs the compound
image in a color or colors. The reference numeral 67 denotes an image
display portion such as a TV monitor for displaying the memorized image in
the image memorizing portion 64.
A specific method of carrying out the present embodiment will now be
described in detail. First, the eye fundus image recorded on a 35 mm slide
prepared in advance is read and input from the image input portion 60, and
thereafter is A/D converted and digitally stored into the image memorizing
portion 64. In the present embodiment, an example of the 35 mm slide
scanner is shown, whereas this is not restrictive, but the image input
portion may be, for example, an eye fundus photographing means such as an
eye fundus camera having an A/D converting interface, or a means which can
provide an eye fundus image, such as a still video camera.
Generally an image photographed by an eye fundus camera or the like has
distortion in the marginal portion thereof. So, the distortion of the
marginal portion of the input image memorized in the image memorizing
portion 64 is digitally corrected as indicated by 13 to 14 in FIG. 7, by
the use of the distortion correction function memorized in the correction
function memory portion 65, and the corrected image is again stored into
the image memorizing portion 64. As a specific example of the method
correcting the distortion of the marginal portion of the image, the image
is displaced by .DELTA..gamma. calculated from the correction function in
each meridian direction from the center of the image. More particularly,
each optic axis height, i.e., the displacement .DELTA..gamma. in the
meridian direction caused by distortion correspondingly to the position of
a radius .gamma. from the center of the image, is measured or calculated
in advance, and these are received as distortion data into a memory, and
during data processing, the position information of the digital image
signal is corrected by an amount corresponding to the displacement
.DELTA..gamma..
The eye fundus image used in the present embodiment is not limited to a
photographed image of a narrow angle of view which can be photographed at
one time, but may also be a distortion-free panorama eye fundus image of a
wide angle of view obtained by combining a plurality of eye fundus images
obtained by photographing different regions, as shown in FIG. 8. Nowadays,
the angle of view covered by an eye fundus camera at one time is generally
of the order of 30.degree.-60.degree., but this problem can be solved by
using a panorama eye fundus image. In this case, a plurality of images are
input from the eye fundus image input portion 60 and memorized in the
image memorizing portion 64, and correction of distortion and combinating
of the images are effected in the image operation means. If correction of
distortion is effected before the eye fundus images a, b and c are
combined together as shown in FIG. 8, there will occur no deviation of the
images due to distortion in the connected portions of the images. The
combining of the images can be manually or automatically accomplished from
the pattern of blood vessels or the like by the use of a conventional
image recognition processing technique.
Thus, the image subjected to distortion correction for the input eye fundus
image, or the panorama eye fundus image obtained by combining the
plurality of images of displayed on the image display portion 67. The
examiner carried out the measurement of the field of view while watching
this displayed eye fundus image, and a specific method of compounding the
eye fundus image and the view field data will hereinafter be described.
As regards the view field data successively sent from the view field
measuring means during the measurement of the field of view, the data are
recorded at a corresponding position on the eye fundus image memorized in
the image memorizing portion, and are displayed on the image display
portion 67 successively, individually or in a postscript fashion.
Alternatively, the eye fundus image and all view field data may be
compounded at a time after the completion of the measurement.
In FIG. 9, the reference numeral 75 designates the eye fundus image after
the distortion of the eye fundus camera has been corrected, the reference
numeral 76 denotes the optic disk, and the reference numeral 77 designates
a yellow spot. The reference numeral 78 denotes the view field data of the
eye to be examined corresponding to the eye fundus image 75, the reference
numeral 79 designates the blind spot, and the reference numeral 80 denotes
the center of fixation. Here, in the eye fundus image 75 and the image of
the view field data 78, the optic disk 76 and the blind spot 79, and the
yellow spot 77 and the center of fixation 80, correspond to each other as
the same regions. In the image operation means 63, these two points are
extracted from the two images by the use of the image recognition
processing technique, and the process of adjusting the two images so as to
bring the two points into coincidence with each other and superposing the
two images one upon the other is carried out.
During the superposition, the eye fundus image 75 and the view field data
78 are in mirror image relationship and therefore, the mirror image
inverting process of the view field data 78 is first effected and then the
compounding of the images is effected. The mirror image inverting process
can be easily accomplished because the view field data 78 is digital data.
When the eye fundus image 75 and the image of the view field data 78 differ
in scale and the two points cannot be brought into coincidence with each
other at the same time, one of the two images is enlarged or reduced to
make the sizes of the two images equal to each other. In the example shown
in FIG. 9, the view field data 78 is enlarged. As an example of the
processing method in this case, the distance between the optic disk and
the yellow spot in the eye fundus image and the distance between the blind
spot and the center of the field of view in the view field meter output
image are measured, and the total sizes of one or both images are changed
so that these two distances may correspond with each other. After the
sizes of the both images have corresponded with each other, the respective
points are brought into coincidence with each other and the both images
are adjusted and compounded. As an alternative method, the centers of the
fields of view of the both images and an image of a predetermined angle of
view (e.g. 60.degree.) centered at the yellow spot may be extracted and
these extracted images may be magnification-changed and compounded so that
they may coincide with each other. During the enlargement, it will be more
preferable to carry out a picture element interpolation process. Thus,
there can be obtained a compound image 81 as shown in the lower portion of
FIG. 9 wherein the optic disk and the blind spot coincide with each other
at 82 and the yellow spot and the center of the field of view coincide
with each other at 83.
As the view field data display method, besides the display method using the
isopters of the embodiment, various forms of display such as density
display and display by color are possible.
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