Abstract:
A perimeter has an image input for inputting eye fundus image data and a display device for displaying an eye fundus image in accordance with the eye fundus image data inputted by the image input. A prescribed area of the eye fundus image displayed on the display device is designated by a designating device. A field of vision of only the prescribed area of the eye fundus image designated by the designating device is then measured by a measurement device.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a perimeter, and more particularly to a perimeter that enables a field of vision measurement area to be designated from an eye fundus image. 
     2. Description of the Prior Art 
     Perimetry has long had a widely-recognized utility with respect to ailments in the eye fundus. Measurement comprises establishing whether or not the patient can perceive a visual sign displayed at a prescribed brightness within a prescribed field of vision (field of vision dome). There is a relationship between the field of vision and ailments in the eye fundus, so when the eye fundus is being examined by measuring the field of vision, the examiner proceeds by viewing a photograph of the patient&#39;s eye fundus, designating a measurement area on another screen, and measuring the field of vision accordingly. 
     A drawback of the conventional method is that since the examiner has to view a photograph of the eye fundus and then use another screen to designate the measurement area of the field of vision, the area designation is imprecise and efficiency is degraded during the designation. 
     In recent years, when a fundus camera is used to examine the eye fundus, images of the fundus are recorded on film, or the images are obtained using a video imaging means such as a CCD camera, converted into an electronic form and stored on floppy disk or other such external storage means, or is transferred to another computer via a LAN or the like. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a perimeter that is able to detect field of vision abnormalities accurately and efficiently. 
     In accordance with this invention, the above object is attained by providing a perimeter comprising means for inputting eye fundus electronic image data, display means for displaying the eye fundus image data thus input, means for designating a prescribed area of the eye fundus image displayed on the display means, and a measurement program for carrying out field of vision measurement of the area thus designated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and advantages of the invention will be more apparent from the following description and drawings, in which: 
     FIG. 1 is a block diagram of the general arrangement of a perimeter according to the present invention; and 
     FIGS. 2 a  to  2   d  are a diagram illustrating the process of measuring the field of vision. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Embodiments of the invention will now be described with reference to the attached drawings. 
     In FIG. 1, reference numeral  10  denotes an image input section. Eye fundus electronic image data are input to the image input section  10  from a removable disk such as a floppy disk  11 , or from a LAN or the like. An eye fundus video camera (not shown), such as a CCD camera, is used to obtain eye fundus images, which are then processed and stored on a floppy disk  11  or the like, or are received via a LAN or the like. The eye fundus images input to the image input section  10  are first stored in a memory  12 , and, via a CPU  14  operating in synchronism with a clock  13 , the images can be displayed on a display such as a monitor  15 . 
     A field of vision measurement program is stored in a memory  16 . When, as will be described later, a prescribed area of the eye fundus displayed on the monitor  15  is designated, the CPU  14  initiates to display a series of visual indicators, via a buffer  17 , on a field of vision dome  18 . The display of these visual indicators may be effected by projecting the indicators on the field of vision dome or by lighting a light source such as an LED or the like provided on the field of vision dome. The indicators are displayed on the field of vision dome in association with the designated area of the eye fundus, so that the visual indicators thus displayed form an image at the designated area of the eye fundus, assuming that the patients vision is fixed on the center of the field of vision dome. 
     When the patient can see a visual indicator displayed on the field of vision dome  18 , the patient responds with a response switch  20 . This signal is transferred to the CPU  14  via an I/O interface  19 . The CPU  14  can process the outcome of the field of vision measurement and display it on the monitor  15 . Also, the CPU  14  is constructed so that it processes and synthesizes the images in cooperation with an image synthesizer  21  and the thus synthesized images can be displayed on the monitor  15 . 
     The I/O interface  19  is connected to an operating panel  23  that is equipped with an LED or other such light source. This operating panel  23  can be used to implement the various operations such as image input, field of vision measurement, image synthesis and so forth. Operations thus initiated at the operating panel  23  are communicated to the CPU  14  via the I/O interface  19 . The results of measurements and images displayed on the monitor  15  can be output to a printer  22  via the I/O interface  19 . A light-pen  24  can be used to designate areas of images displayed on the monitor via the I/O interface  19 . Instead of using the light-pen a touch-panel  25  provided on the monitor  15  can be used for this purpose. 
     In operation, eye fundus image data input to the image input section  10  via a floppy disk  11 , a LAN or the like are once stored in the memory  12 , and then, via the CPU  14 , is displayed on the monitor  15 . This is illustrated by FIG. 2 a , showing eye fundus image  30  on monitor screen  15   a . In FIGS. 2 a  to  2   d , only the monitor screen  15   a  is shown; the monitor frame and touch-panel  25  are thus not shown. 
     Next, as shown in FIG. 2 b , a prescribed area  31  of the eye fundus image is designated, using the light-pen  24  or a finger. The area is designated so as to include at least a portion considered to be, for example, a diseased portion of the eye fundus. The designation of the area  31  is communicated to the CPU  14 , which executes the measurement program stored in the memory  16  to implement field of vision measurement of the designated portion. FIG. 2 c  shows this field of vision measurement on the monitor screen  15   a ; the contents of the measurement program thus implemented are shown in region  32 , and the results  34  of the field of vision measurement implemented on the field of vision dome image  33  are displayed. The solid black dots in the result field each denote a non-response by the patient to a visual indicator that was displayed on the field of vision dome, indicating a field of vision abnormality. 
     The results  34  are stored in the memory  12  as field of vision measurement data. The image synthesizer  21  can take the result data and overlay them on the eye fundus data displayed on the screen  15   a , as shown in FIG. 2 d . The field of vision measurement data can also be associated with the eye fundus image data and stored in the memory  12  or in an external memory that is not shown. If required, displayed images can be printed out. 
     As described in the foregoing, this invention allows an area of an eye fundus that is to be subjected to field of vision measurement to be designated using a screen on which the fundus image is displayed, thereby enabling field of vision abnormalities to be detected with good efficiency.