U.S. patent application number 11/683632 was filed with the patent office on 2008-02-14 for perimeter.
This patent application is currently assigned to KOWA COMPANY, LTD.. Invention is credited to Satoshi Shimada.
Application Number | 20080036965 11/683632 |
Document ID | / |
Family ID | 38988761 |
Filed Date | 2008-02-14 |
United States Patent
Application |
20080036965 |
Kind Code |
A1 |
Shimada; Satoshi |
February 14, 2008 |
PERIMETER
Abstract
A perimeter is comprised of means for setting a second visual
field coordinate system on a fundus image displayed on a monitor
wherein an origin is a macula lutea, means for provisionally
determining a blind spot position on the second visual field
coordinate system, means for searching a coordinate position of a
blind spot on the first visual field coordinate system by
presenting a stimulus on the visual field dome, means for changing
a scale of the second visual field coordinate system so as to
correspond the coordinate value of the blind spot on the first
visual field coordinate system and the coordinate position of the
blind spot on the second visual field coordinate system with each
other, and means for conducting a perimetry by presenting the
stimulus at a position on the first visual field coordinate system
having the same coordinate value as one on the second coordinate
system of a predetermined test point.
Inventors: |
Shimada; Satoshi;
(Hamamatsu-shi, JP) |
Correspondence
Address: |
DUANE MORRIS, LLP;IP DEPARTMENT
30 SOUTH 17TH STREET
PHILADELPHIA
PA
19103-4196
US
|
Assignee: |
KOWA COMPANY, LTD.
NAGOYA-SHI
JP
|
Family ID: |
38988761 |
Appl. No.: |
11/683632 |
Filed: |
March 8, 2007 |
Current U.S.
Class: |
351/206 |
Current CPC
Class: |
A61B 3/12 20130101; A61B
3/024 20130101 |
Class at
Publication: |
351/206 |
International
Class: |
A61B 3/14 20060101
A61B003/14 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 9, 2006 |
JP |
2006-217452 |
Claims
1. Perimeter for perimetry on an eye to be examined by presenting a
stimulus at a predetermined coordinate position of a first visual
field coordinate system which is set on a visual field dome,
comprising: a memory for storing a fundus image of said eye to be
examined; means to control display for reading said fundus image
and displaying said fundus image on a monitor; means to set
coordinate for setting a second visual field coordinate system
wherein a macula lutea portion of said fundus image which is
displayed on said monitor is an origin on said fundus image
displayed on said monitor; means for provisionally determining
blind spot coordinate, for provisionally determining a blind spot
position on said fundus image on said second visual field
coordinate system; means to search blind spot for searching a
coordinate position of a blind spot of said eye to be examined on
said first visual field coordinate system by presenting said
stimulus to said eye to be examined on said visual field dome;
means to change scale for changing a scale of said second visual
field coordinate system so as to correspond said coordinate value
of said blind spot of said eye to be examined on said first visual
field coordinate system which is obtained by said blind spot search
means and said coordinate value of said blind spot of said fundus
image on said second visual field coordinate system with each
other; and means to conduct perimetry for conducting a perimetry on
said eye to be examined by presenting said stimulus on said visual
field dome at a position on said first visual field coordinate
system having the same coordinate value as one on said second
coordinate system of a predetermined test point on said fundus
image.
2. The perimeter according to claim 1, wherein further comprising a
memory for storing standard blind spot position coordinate data
showing positions where blind spots generally exist, and means to
control search for controlling said means to search blind spot to
read said standard blind spot position coordinate data from said
memory and to search said blind spot at a periphery of said
coordinate position which is shown in said standard blind spot
position coordinate data when said blind spot search means searches
said coordinate position of said blind spot on said first visual
field system.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a perimeter for designating a
perimetry point for an eye to be examined with a fundus image of
the eye which has already been photographed.
BACKGROUND ART
[0002] The technique of designating a perimetry point for an eye to
be examined with a fundus image of the eye which has already been
photographed in a perimetry is already known from a patent
application publication number of which is 2000-262472, for
instance.
[0003] In such a case, it is necessary to correctly correspond, a
coordinate on the image of the examined eye which is shown on the
fundus image, and an actual coordinate of the eye on which a
perimetry will be conducted from now on with each other. Generally,
a X-Y coordinate system is set for the fundus image provided that a
position of a blind spot on the fundus image is a predetermined
coordinate position with respect to a macula lutea (a central
portion of the visual field), X=-15.degree. and Y=-3.degree., for
instance. But, it is impossible to conduct the correct perimetry as
long as some coordinate correction is not executed since there is
an individual variation in the position of the blind spot with
respect to the macula lutea.
[0004] Then, the object of the invention is to provide a perimeter
for correctly conducting a perimetry by setting a coordinate system
on the fundus image so as to compensate the individual variation in
the position of the blind spot to the macula lutea in order to
solve the above-mentioned inconvenience.
SUMMARY OF THE INVENTION
[0005] One aspect of the invention is perimeter for perimetry on an
eye to be examined by presenting a stimulus at a predetermined
coordinate position of a first visual field coordinate system which
is set on a visual field dome, comprising: [0006] a memory for
storing a fundus image of said eye to be examined; [0007] means to
control display for reading said fundus image and displaying said
fundus image on a monitor; [0008] means to set coordinate for
setting a second visual field coordinate system wherein a macula
lutea portion of said fundus image which is displayed on said
monitor is an origin on said fundus image displayed on said
monitor; [0009] means for provisionally determining blind spot
coordinate, for provisionally determining a blind spot position on
said fundus image on said second visual field coordinate system;
[0010] means to search blind spot for searching a coordinate
position of a blind spot of said eye to be examined on said first
visual field coordinate system by presenting said stimulus to said
eye to be examined on said visual field dome; [0011] means to
change scale for changing a scale of said second visual field
coordinate system so as to correspond said coordinate value of said
blind spot of said eye to be examined on said first visual field
coordinate system which is obtained by said means to search blind
spot and said coordinate value of said blind spot of said fundus
image on said second visual field coordinate system with each
other; and [0012] means to conduct perimetry for conducting a
perimetry on said eye to be examined by presenting said stimulus on
said visual field dome at a position on said first visual field
coordinate system having the same coordinate value as one on said
second coordinate system of a predetermined test point on said
fundus image.
[0013] The other aspect of the invention is the perimeter, wherein
further comprising a memory for storing standard blind spot
position coordinate data showing positions where blind spots
generally exist, and means to control search for controlling said
means to search blind spot to read said standard blind spot
position coordinate data from said memory and to search said blind
spot at a periphery of said coordinate position which is shown in
said standard blind spot position coordinate data when said means
to search blind spot searches said coordinate position of said
blind spot on said first visual field system.
[0014] According to both aspects of the invention, the scale of the
second visual field coordinate system which is set on the fundus
image and the scale of the first visual field coordinate system
which is set on the visual field dome can be correctly corresponded
with each other so as to compensate an individual variation in the
position of the blind spot to the macula lutea, and the perimetry
on an eye to be examined can be correctly conducted by designating
the test point on the fundus image.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a block diagram showing an instance of a
perimeter.
[0016] FIG. 2 is a view showing an instance of a fundus image which
is displayed on a monitor of a perimeter for showing one of a
series of perimetry routines.
[0017] FIG. 3 is a view showing an instance of the fundus image
which is displayed on the monitor of the perimeter for showing one
of a series of perimetry routines.
[0018] FIG. 4 is a view showing an instance of the fundus image
which is displayed on the monitor of the perimeter for showing one
of a series of perimetry routines.
[0019] FIG. 5 is a view showing an instance of the fundus image
which is displayed on the monitor of the perimeter for showing one
of a series of perimetry routines.
[0020] FIG. 6 is a view showing an instance of the fundus image
which is displayed on the monitor of the perimeter for showing one
of a series of perimetry routines.
[0021] FIG. 7 is a view showing an instance of the fundus image
which is displayed on the monitor of the perimeter for showing one
of a series of perimetry routines.
[0022] FIG. 8 is a view showing an instance of the fundus image
which is displayed on the monitor of the perimeter for showing one
of a series of perimetry routines.
[0023] FIG. 9 is a view showing an instance of the fundus image
which is displayed on the monitor of the perimeter for showing one
of a series of perimetry routines.
[0024] FIG. 10 is a view showing an input screen to be used when
instructing an area on which perimetry is conducted and a set
area.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] An embodiment of the invention will now be explained,
referring to appended figures.
[0026] FIG. 1 is a block diagram showing an instance of a
perimeter, FIGS. 2 through 9 are views respectively showing an
instance of a fundus image which is displayed on a monitor of a
perimeter showing a series of perimetry routines, and FIG. 10 is a
view showing an input screen to be used when instructing an area on
which perimetry is conducted and an instance of a set area.
[0027] A reference numeral 10 of FIG. 1 denotes an image input
portion, into which electrically imaged fundus data is inputted
through a removable disc, such as a floppy disc 11 or a CD, or from
a LAN. A fundus image is stored in the floppy disc 11 or is
transmitted through a LAN after taking by a fundus camera (not
shown) through a television camera (a CCD camera) and executing
image processing thereon. The fundus image which is inputted into
the image input portion 10 can be displayed on a display portion,
such as a monitor 15, through a CPU 14 operating so as to
synchronize with a clock 13 after storing in a memory 12.
[0028] And, a program for perimetry is stored in a memory 16, and
as mentioned hereinafter, the CPU 14 displays stimuli in order on a
visual field dome 18 through a buffer 17 when designating a
predetermined area of a fundus which is displayed on the monitor
15. On this occasion, the stimuli are displayed by projecting on
the visual field dome or lighting a light source which is located
on the visual field dome, such as a LED. The stimuli are displayed
in connection with the designated fundus area, and the displayed
stimulus is formed at the designated area on the fundus when an
examinee fixates a center of the visual field dome.
[0029] An Examinee responds through a response switch 20 when
perceiving the stimulus displayed on the visual field dome 18, and
this response is transmitted to the CPU 14 through an I/O interface
19. The CPU 14 can display on the monitor 15 an image on which the
image processed by the CPU 14 is synthesized through an image
composer 21.
[0030] And, an operation panel 23 having a light source, such as a
LED, is connected with the I/O interface 19, and through the
operation panel 23, various kinds of operations, such as image
input, perimetry and image synthesis, can be designated, and these
operations can be transmitted to the CPU 14 through the I/O
interface 19. Besides, a measurement result or the image displayed
on the monitor 15 can be outputted to a printer 22 through the I/O
interface 19. It is possible to set or designate the area of the
image displayed on the monitor 15 with a light pen 24 through a
touch panel 25 which is located on the monitor 15.
[0031] Subsequently, the fundus image data is inputted into the
image input portion 10 through the floppy disc or the LAN, and is
stored in the memory 12, and thereafter, the fundus image is
displayed on the monitor 15 through the CPU 14 in such a structure.
This state is shown in FIG. 2, which shows that a fundus image 30
is displayed on a screen 15a of the monitor.
[0032] An examinee is invited to fixate the stimulus projected on a
projection plane inside the visual field dome 18, and responds to
an examiner through an appropriate method, such as operation of the
response switch 20 and response by voice when perceiving the
stimulus.
[0033] As shown in FIG. 2, the fundus image 30 is displayed on the
monitor 15. The fundus image 30 is displayed reversely in an
up/down direction so as to match with perimetry in comparison with
normal display of a fundus image. In the above-mentioned state, the
examiner designates a center of a macula lutea position K which is
a center of a macula lutea portion 31 as a center of the visual
field (origin ZP) on the fundus image 30 displayed on the monitor
15 with the light pen 24 as shown in FIG. 3, and furthermore
designates a central position of a blind spot (optic disc) 32 as a
blind spot position M1.
[0034] The CPU 14 detects and computes coordinate positions of the
macula lutea position K and the blind spot position M1 on the
monitor 15 which are shown with the light pen 24 on the basis of
perimetry program stored in the memory 16, and sets a X-Y
coordinate system which origin is the macula lutea portion 31, as
shown in FIG. 4. Subsequently, the CPU 14 provisionally determines
the blind spot position M1 which has been designated by the
examinee on the monitor as X=-15.degree. and Y=-3.degree. on the
basis of standard blind spot position coordinate data (which are
detailedly mentioned hereinafter) which is generally
(statistically) considered to be the blind spot position coordinate
on the macula lutea portion 31 as shown in FIG. 5 according to the
perimetry program, and a scale of the X-Y coordinate is
corresponded to the blind spot position M1, and is displayed on the
fundus image.
[0035] Subsequently, the CPU 14 displays a measurement point which
is set in advance, that is, a test point IP on the monitor as shown
in FIG. 6 according to the perimetry program. The test points IP
displayed in FIG. 6 are set with visual field angles .alpha. and
.beta. in the X-axis and Y-axis directions. Concretely speaking,
the test points IP are equally allotted at intervals of .alpha.,
.beta. in the X-axis and Y-axis directions in such a way that the
points are distributed respectively separated from the X- and
Y-coordinate axes by .alpha./2 and .beta./2. Although the set
angles of .alpha. and .beta. are optional, the set angles are
4.degree. through 5.degree., for instance.
[0036] When using an insertion lens for an eyepiece (not shown)
into which an examinee for perimetry looks for the reason of a
visual acuity grade, an examiner inputs a correcting value of the
insertion lens through the operation panel 23, and the CPU 14
adjusts the scale of the X-Y coordinate on the fundus image 30
according to the inputted correcting value of the insertion lens in
order to correct the coordinate axis. If the insertion lens is
inserted, the position on the visual field dome 18 at which an
examinee perceives may shift 20 percent due to prism effect of the
insertion lens, for instance. In such a case, the scale of the X-Y
coordinate on the fundus image 30 is corrected according to the
shift amount.
[0037] When instructing the coordinate position on the fundus image
30 in the above-mentioned state, it is possible to correspond to an
examined eye 33 which looks onto the corresponding visual field
dome 18 to the visual field coordinate on the visual field dome 18
to each other in appearance. If the position of the stimulus to be
presented (corresponding to the test point IP) is displayed on the
visual field dome 18, designating the visual angle of the X-Y
coordinate on the basis of the scale which is set on the X-Y
coordinate on the fundus image 30 displayed on the monitor 15, but,
an error occurs between the position of the stimulus on the fundus
image 30 (corresponding to the test point IP) and the actual
position of the stimulus which is presented to the examined eye in
the visual field dome 18 since a positional relation between the
macula lutea position K and the blind spot position M1 is actually
different due to individual variation.
[0038] On the other hand, an examiner designates a point on which
perimetry is executed for the examined eye 33 from now on, on the
screen of the monitor 15 with the light pen 24 or the like on the
basis of the fundus image 30 and the image of the test points IP
which are displayed on the monitor 15 by individually designating
the image of the test point IP (the test point IP shown with a
black spot of FIG. 7, for instance) or designating an area AR
including two or more test points IP to be examined. The test
point(s) IP to be examined can be designated, directly confirming
the fundus image 30 of the examined eye 33 on the monitor 15,
thereby easily selecting the test point(s) IP which is proper for
the state of the examined eye 33.
[0039] Various methods are considered in order to designate the
test point(s) IP. For instance, the CPU 14 may read an area
selection map MAP having two or more divided areas AR which should
be designated for perimetry on the fundus image 30 from the memory
16 according to the perimetry program as shown in FIG. 10(a) and
the area may be displayed on the monitor 15, and the examiner may
be invited to select the area AR with the light pen 24 or the
like.
[0040] In such a case, the sizes of the respective areas AR in the
area selection map MAP may be set so as to match with a case of
disease on the examined eye 33 or the state of the fundus image 30
in such a way that two or more parameters which can be set by the
examiner, such as "diameter of macula lutea (m)(.degree.)",
"diameter of optic disc(d)(.degree.)", "Y-axis coordinate 1
(Y1)(.degree.)" and "Y-axis coordinate 2 (Y2) (.degree.)" are set
as shown in FIG. 10(a), and the examiner can properly input these
parameter values PM through the operation panel 23. When thus
inputting various kinds of parameters, the CPU 14 transforms the
respective areas AR in the area selection map MAP so as to
correspond to the inputted parameter values PM, and displays the
areas as shown in FIG. 10(b), for instance. In case of FIG. 10(b),
the area selection map MAP is formed in an elliptic shape as a
whole by designating the parameter values PM, and the test points
IP belonging to the area are displayed on the area ARS which is
selected by the examiner. Besides, two or more kinds of
distribution patterns of the test points IP can be stored in the
memory 16 for the test points IP which are arranged on each area
ARS so as to select by the examiner. In such a case, the examiner
may select the distribution pattern of the test point IP, matching
with the case of disease.
[0041] When thus selecting the test point IP to be measured, the
examiner inputs a measurement start instruction to the CPU 14
through the operation of the operation panel 23. Receiving this
instruction, the CPU 14 corrects the scale which is set on the X-Y
coordinate displayed on the monitor 15, that is, corrects the
coordinate of the blind spot position M1 according to the perimetry
program.
[0042] Firstly, the CPU 14 starts a processing for searching a
blind spot position, for obtaining the actual blind spot position
of the examined eye on the X-Y coordinate (first visual field
coordinate system) which is set on the visual field dome 18
according to the perimetry program. In this processing for
searching a blind spot position, the CPU 14 reads a standard blind
spot position coordinate, X=-15.degree. and Y=-3.degree., which is
stored in the memory 16 as the standard blind spot position
coordinate data showing a position where the blind spot generally
exists. The CPU 14 sets two or more search points SP (a location
density of which is higher than one of the test points IP) near the
coordinate X=-15.degree., Y=-3.degree. as shown in FIG. 8(a) on the
basis of the read standard blind spot position coordinate
X=-15.degree. and Y=-3.degree. on the X-Y coordinate which is set
on the visual field dome 18, and presents these set search points
SP to the examined eye 33 in order, collects the response states,
stores the collected in the memory 16, and displays on the monitor
15.
[0043] If the search points SP to which a response of informing of
perception of the stimulus is given from the examinee are shown
with white spots, and the search points SP to which no response is
given from the examinee are shown with black spots as shown in FIG.
8(a), the examinee does not respond to the blind spot portion
without the perception of the stimulus. Then, one or more black
spots of the blind spot portion, that is, the portions to which no
response is give from the examinee, are registered, as shown in
FIG. 8(b).
[0044] The CPU 14 judges the area where the search points SP
receiving no response are arranged to be the actual blind spot of
the examined eye 33, and obtains a blind spot position M2 on the
X-Y coordinate which is set on the visual field dome 18 by
computing a center of gravity or a coordinate average between two
or more search points SP receiving no response. If there is only
one search point SP to which no response is given, the search point
SP is determined as the blind spot position M2. In such a search of
the blind spot position, the CPU 14 reads the standard blind spot
position coordinate data which is stored in the memory 16 according
to the perimetry program, and the search is conducted at a
periphery of the coordinate position on the basis of the read
standard blind spot position coordinate data, thereby searching the
blind spot position in a time much shorter than the random search
of the blind spot position on the visual field coordinate system in
the visual field dome.
[0045] If the coordinate of the blind spot position M2 of the
examined eye 33 which was searched on the visual field dome 18 is
X=-13.degree. and Y=-4.degree., for instance, this coordinate value
is the correct blind spot position M2 of the examined eye 33. Then,
the CPU 14 corrects the scale of the X-Y coordinate (the second
visual field coordinate system) set on the fundus image 30 so that
the blind spot position M1 (coordinate X=-15.degree. and
Y=-3.degree.) on the X-Y coordinate which is the second visual
field coordinate system provisionally set on the fundus image 30
can be the coordinate X=-13.degree. and Y=-4.degree. even in the
X-Y coordinate on the fundus image 30.
[0046] In such a case where the blind spot position M1 on the
fundus image 30 which is provisionally set is the coordinate (A,B)
(in the last instance (X=-15.degree. Y=-3.degree.) and the blind
spot position M2 of the examined eye 33 which has been actually
measured is the coordinate (a, b) (in the last instance
(X=-13.degree., Y=-4.degree.), this correction is executed in such
a way that the CPU 14 obtains both correction factors, a correction
factor for X-axis P.sub.X and a correction factor for Y-axis
P.sub.Y from both expressions P.sub.X=a/A and P.sub.Y=b/B, and the
scale of the X-Y coordinate which is set on the fundus image 30 is
multiplied by both correction factors, as shown in FIG. 9. In case
of FIG. 9, the blind spot position of the fundus image is changed
from M1 (X=-15.degree., Y=-3.degree.) into M2 (X=-13.degree.
Y=-4.degree.) since P.sub.X=-13.degree./-15.degree.=0.867 and
P.sub.Y=-4.degree./-3.degree.=1.33.
[0047] Thereafter, the coordinate IP.sub.n (c.sub.n, d.sub.n) of
each search point IP which is displayed on the fundus image 30 is
changed into IP.sub.n (e.sub.n, f.sub.n) wherein
e.sub.n=P.sub.X.times.c.sub.n and f.sub.n=P.sub.Y.times.d.sub.n.
Then, each position (x, y) on the X-Y coordinate (the second visual
field coordinate system) which is set on the fundus image 30
correctly corresponds to the same coordinate value (x, y) on the
X-Y coordinate (the first visual field coordinate system) which is
set on the visual field dome 18 with one-to-one-correspondence so
as to correspond both coordinate values with each other.
[0048] After thus correcting the scale of the X-Y coordinate system
on the fundus image 30 by the CPU 14, that is, converting the
second visual field coordinate system (the X-Y coordinate system)
which is set on the fundus image 30 into the first visual field
coordinate system (the X-Y coordinate system) which is set on the
visual field dome 18, the examiner executes perimetry on the
examined eye 33 with the fundus image as a guide.
[0049] That is, the test is conducted on the test point IP which is
already designated by the examiner by presenting the stimulus
having a predetermined luminance at the coordinate position of the
visual field dome 18 having the coordinate value the same as one of
the test point IP. Since the CPU 14 properly corrected the scale
between the second visual field coordinate system which is set on
the fundus image 30 and the first visual field coordinate system
which is set on the visual field dome 18 as already mentioned, the
predetermined test point IP on the fundus image 30 is presented to
the examined eye 33 so that the stimulus can be positioned so as to
have the positional relation the same as the relative position of
the test point IP with respect to the fundus image 30 even in the
visual field dome 18. Then, it is possible to correctly present the
stimulus to the examined eye 33 which looks into the visual field
dome 18 through the fundus image 30.
[0050] The invention can be utilized as a perimeter for perimetry
by designating the predetermined test point IP with the fundus
image and presenting the stimulus at the corresponding position on
the visual field dome.
[0051] The present invention has been explained on the basis of the
example embodiment discussed. Although some variations have been
mentioned, the embodiments which are described in the specification
are illustrative and not limiting. The scope of the invention is
designated by the accompanying claims and is not restricted by the
descriptions of the specific embodiments. Accordingly, all the
transformations and changes within the scope of the claims are to
be construed as included in the scope of the present invention.
* * * * *