JPH11267101A - Visual field measuring method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable measurement of a reliable flicker perimetry without making a subsect feel uneasy. SOLUTION: First and second targets 30 and 30' the same in size are so formed that a background 31 of a specified color C is formed and colors A and B differ from each other while presenting the same color as that of the background with the same brightness when overlapped. The first and second targets are displayed being alternately overlapped at a specified position of the background by varying the cycle N thereof. When the cycle is short, the targets present the same color and brightness as those of the background, eventually causing no flickering, which will not allow a subject to recognize the existence of the targets and as a result, he can hold fixation without instability the while. A longer cycle causes a flickering in the targets permitting the examinee to easily respond to it. This enables accurate determination of a flicker perimetry based on the cycle and the frequency of the flickering.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual field measuring method and apparatus, and more particularly, to a visual field measuring method and apparatus for measuring a flicker visual field of a subject based on flicker of a formed visual target.

[0002]

2. Description of the Related Art Conventionally, perimetry has been widely used for ophthalmic diagnosis or intracranial disease, and measurement has been carried out. This conventionally performed visual field inspection is called a lightness discrimination visual field inspection, and inspects whether or not the subject can recognize an optotype displayed at a predetermined brightness in a predetermined visual field. In recent years, flicker perimetry has been attracting attention as a method for early detection of glaucomatous visual field change. This method not only displays an optotype with a predetermined brightness in the visual field, but also makes the display flicker, and changes the flicker speed (frequency) to test the ability of the subject to recognize the flicker. How to

[0003]

Until now, flicker visual field measurement has required complicated understanding and training of the subject due to the complicated inspection. In other words, in the brightness discrimination visual field test, the subject fixed his eye on the vicinity of the center of the visual field, and if he felt light somewhere in the visual field, he had to send a cue to the examiner. Since it is necessary to recognize the flickering of the light while staring at the vicinity, the fixation tends to be unstable, and it takes a long time for the measurement, and the reliability of the measurement result is also a problem. Further, there is a problem that the subject suffers a great deal of mental and physical pain and places a great burden on the subject.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a visual field measurement method and apparatus which can perform a reliable flicker visual field measurement without making a subject unstable. Make it an issue.

[0005]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention forms a background of a predetermined color and has the same size as the background and the same color and the same brightness when the colors are overlapped and superimposed. When the first and second optotypes are formed, and the first and second optotypes are alternately superimposed and displayed at predetermined positions on the background by changing the cycle, and the cycle is lengthened. The cycle in which the subject responds to the flicker of the optotype occurring in the above is obtained, and the flicker visual field is measured based on the obtained cycle.

According to the present invention, an optotype is formed at a predetermined position on a background of a predetermined color, and two light sources which emit light having the same color and the same brightness as the background when the colors are different from each other and are superimposed. The target is illuminated alternately without changing the period by changing the period, a period when the subject responds to the flicker of the target generated when the period is lengthened is determined, and the flicker visual field is determined based on the determined period. A configuration for measuring is also adopted.

According to the present invention, the background of a predetermined color is formed, and the cycle of the light from two light sources that generate light having different colors from each other and having the same brightness as the background when superimposed is changed. And alternately overlap and project onto the predetermined position of the background so as to have the same size, and determine the cycle when the subject responds to the flicker of the optotype that occurs when the cycle is lengthened. A configuration in which the flicker visual field is measured based on the obtained cycle is also adopted.

Further, according to the present invention, there is provided a means for forming a background of a predetermined color, and first and second optotypes of the same size which are different from each other and have the same brightness and the same color as the background when superimposed. Means for alternately displaying the first and second optotypes without overlapping at predetermined positions on the background, and means for changing the display cycle of the first and second optotypes. And a means for calculating a cycle when the subject responds to the flicker of the optotype generated when the cycle is lengthened, and a means for calculating a flicker visual field based on the obtained cycle. .

In such a configuration, when the target is formed or projected at a high speed (with a short cycle), no flicker occurs as a result of the same color and the same brightness as the background. The target and the background cannot be distinguished, and the presence of the target is not recognized. As a result, the subject can keep his fixation without becoming unstable during that time. In addition, when the cycle is long, the optotype flickers, so that the subject can distinguish the optotype from the background, and can easily respond to the flicker. This makes it possible to accurately determine the flicker visual field based on the period or frequency at which flicker is recognized.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

[0011] Since a human suffers from the afterglow phenomenon, when the lights A and B from the two types of light sources are alternately viewed at high speed, the lights A and B from the two light sources appear to be combined light. Therefore, the light obtained by combining the lights A and B from both light sources is used as background light, and the target is illuminated and projected using A and B alternately to perform a visual field inspection. When performing the visual field examination in this way, if the cycle in which A and B are alternately used is gradually reduced, the subject recognizes the presence of the flickering target only at a certain cycle. When the subject is sent a signal when the target is recognized, and the cycle value at that time is measured, the ability to identify flicker can be measured for each point in the visual field. That is, flicker visual field measurement can be performed. In this method, since the subject only needs to be aware of the recognition of the optotype, the burden of the examination is the same as that of the conventional brightness discrimination visual field examination, and the subject does not require any skill or the like.

FIG. 1 shows the appearance of a visual field measuring apparatus utilizing this principle, and FIG. 2 shows the internal configuration thereof. The subject sits down with his left eye 10a and right eye 10b touching the eyepiece 1, and observes an image of the CRT 12 disposed inside. As shown in FIG. 2, the image of the CRT 12 is guided to the half mirror 16 via the magnification lens 13, the relay lens 14, and the focusing lens 15, and the image passing through the half mirror 16 is opened when the shutter 11a is opened. When the shutter 11b is opened, the image observed by the left eye 10a through the protective glass 1a and reflected by the half mirror 16 is reflected by the right eye 10b through the mirror 17 and the protective glass 1b.
Observed in. The image on the CRT 12 can be clearly observed by the subject by adjusting the adjustment knob 2 and moving the focusing lens 15.

Also, the visual field measuring device has a clock 2 inside.
1, the CPU 20 operates in synchronization with each other, and the CPU 20 performs various controls according to an instruction input through an instruction panel 3 arranged on a side portion. By the indication panel 3, CR
The position and color of the target 30 displayed on the display surface 12a (FIG. 2B) at T12 can be specified, and the color of the background 31 on the display surface can also be specified. Target 3
As the colors 0 and 30 ', for example, at least two colors A and B can be designated with C as the background color.

When the positions of optotypes 30, 30 'of the same size and their colors A, B, and background color C are designated on the instruction panel 3, the CPU 20 activates the character generator 22.
And a pattern 32 for fixation of a predetermined color and a fixation pattern of a predetermined color are generated through the, and according to each designated color, the position of the target 30, 30 ′ and the position of the fixation pattern (substantially at the center) The drawing pattern is written in the VRAM 23. The pattern written in the VRAM 23 is the display circuit 2
4 is displayed on the CRT 12. The subject is a CRT
When flicker occurs in the optotypes 30 and 30 ′ displayed on the display 12, the response switch 25 responds, a flicker optotype is calculated based on the flicker frequency at that time, and the result is displayed on the display unit 4. . Further, the angle of view can be changed via the instruction panel 3. When the user wants to change the field of view, the CPU 20 changes the magnification lens 13 to another magnification lens 13 ′ via the angle-of-view conversion unit 26. Can be changed.

In such a configuration, the flow of the visual field measurement will be described with reference to FIG. First, in step S1, the colors A and B of the targets 30, 30 'and the color C of the background 31 are specified, and in step S2, the positions of the targets on the CRT display surface 12a are specified. In this case, a target 3 of the same size
0 and 30 'are displayed in the same position without being shifted. Also, in step S3, the variable n is set to 1, and
In step S4, the timer t is set to 0.

For example, the color A of the target 30 is set to blue, the color B of the target 30 'is set to red, and the color C of the background 31 is set to magenta via the instruction panel 3, and the targets 30 and 30' are designated. Are designated as the same position, the CPU 20 reads the patterns and fixation patterns of the targets 30 and 30 ′ via the character generator 22 and generates patterns X and Y determined by the designated positions and colors, respectively. The data is written in the VRAM 23 and drawn alternately at the flicker cycle N = F * n (F is the field cycle = 1/60 second) (step S).
5).

The pattern X is, as shown in FIG.
This is a pattern in which a rectangular optotype 30 of a color A as a background color C is located at a designated position with a circular fixation pattern 32 (color is green, for example) at the center. In the pattern X, for example, in the m lines after the horizontal synchronizing signal 33 passing through the optotype, at a distance L0 to the optotype, the R component and the B component have luminance I1, and the G component has luminance 0. Therefore, when the magenta background is drawn on the CRT 12 and reaches the optotype 30, the R component and the G component are 0, and the B component is the luminance I2.
Since (= I1), the blue target is displayed, and after passing through the target, it becomes the same as when reaching the target. In this case, since I1 = I2, the background 31 and the optotype 30 have different colors, but have the same brightness.

In the pattern Y, a magenta background is drawn on the CRT 12 at a distance L0 up to the m-line target, similarly to the pattern X, and when the target reaches the target 30 ', the G component, B The component is 0 and the R component is luminance I2 (=
I1), the red target is displayed, and when passing through the target, it becomes the same as before reaching the target. In this case, since I1 = I2, the background 31 and the target 30 'have different colors but the same brightness. The target 30 'is the target 3
It is a position that has the same shape as 0 and overlaps each other without displacement.

If the speed at which the patterns X and Y are alternately displayed is high, the afterimage phenomenon occurs in the human eye, so that the targets A and B of the color A (blue) and the color B (red) are combined. As a result, the same color (magenta) is obtained with the same brightness as the background, and the optotypes 30 and 30 ′ are overlapped without any deviation. Therefore, the optotypes are assimilated with the background, and the optotype cannot be identified.
Now, as shown in FIG. 4B, the patterns X and Y
= (1/60 seconds) * 1 Since the display is alternately performed at a period of 1/60 seconds, a normal subject cannot identify the optotype 30 (30 ′). Therefore, since there is no response in step S6, a timer is added (step S7). Predetermined time t0
If there is no response even after elapse (step S8), n is incremented by one in step S9, and the display cycle is lengthened.

If n does not exceed the predetermined value n0 (step S10), the flow returns to step S5, where N = (1/60).
Seconds) The patterns X and Y are displayed alternately in a cycle of 2 = 1/30 seconds (FIG. 4C). If there is no response yet,
Increment n by +1 and N = (1/60 sec) * 3 = 1/20
Patterns X and Y are displayed alternately in a cycle of seconds (FIG. 4).
(C)).

As described above, when the switching cycle of the patterns X and Y becomes longer, the optotypes 30 and 30 'of the patterns X and Y become longer.
Is separated and flickers, and the subject recognizes the flicker of the target, and responds with the response switch 25. Therefore, the CPU 20 determines in step S11 the flicker visual field (for example, flicker frequency 1) at the target position.
/ N) is calculated and displayed on the display unit 4.

If all of the predetermined target positions have not been specified (step S12), the process returns to step S2 to perform the same processing, and performs the visual field measurement at another position. When the measurement at all the target positions has been completed, it is determined in step S13 whether to change the visual field range. When the measurement is performed by changing the field of view, the same measurement is repeated by changing the angle of view by changing the zoom lens 13 in step S14. If the field of view is not to be changed, the process ends. The process is also terminated when n becomes larger than the predetermined value n0 in step S10.

The above processing is performed with a single eye or both eyes, and when measuring the visual field of the left eye 10a or the right eye 10b, the shutter 11a or 11b is opened.
When measuring the visual field with both eyes, both shutters are opened.

In the above method, the visual field is generated using a pattern generator (character generator). However, a visual target is formed at a predetermined position on a background of a predetermined color (for example, magenta), and the visual fields are compared with each other. The two light sources, which emit light that is the same color and brightness as the background when they are different and overlapped, are illuminated alternately without any shift by changing the period, and suffer from optotype flicker that occurs when the period is lengthened. A cycle when the examiner responds may be obtained, and the flicker visual field may be measured based on the cycle.

Also, instead of first making the field of view with the field of view as the background, it may be made using two light sources. That is, a background of a predetermined color is formed, and light from two light sources that generate light having the same color and the same brightness as the background when the colors are different from each other and are superimposed is alternately changed by changing the period. The projection is superimposed on each of the predetermined positions, and the cycle when the subject responds to the flicker of the optotype generated when the cycle is lengthened is determined, and the flicker visual field is measured based on the determined cycle. Is also good.

[0026]

As described above, according to the present invention, when a target is formed or projected at a high speed (with a short period), the same color as the background and the same brightness do not occur, resulting in no flickering. In addition, the subject cannot distinguish between the target and the background, and does not recognize the presence of the target. As a result, the subject can keep his fixation without becoming unstable during that time. In addition, when the cycle is long, the optotype flickers, so that the subject can distinguish the optotype from the background,
Can easily respond to flicker. This makes it possible to accurately determine the flicker visual field based on the period or frequency at which flicker is recognized.

[Brief description of the drawings]

FIG. 1A is a front view of a visual field measuring device, and FIG. 1B is a side view thereof.

FIG. 2A is a block diagram showing an internal configuration of a visual field measuring device, and FIG. 2B is an explanatory diagram showing a display surface of a cathode ray tube (CRT).

FIG. 3 is a flowchart showing a flow of measuring a flicker visual field.

FIG. 4A is an explanatory diagram showing a state in which a pattern is drawn, and FIGS. 4B to 4D are diagrams showing a state in which the pattern is alternately displayed while changing the period.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Eyepiece part 3 Instruction panel 4 Display part 10a Left eye 10b Right eye 12 CRT 13 Magnification lens 15 Focusing lens

Claims (5)

[Claims] 1. A first target and a second target having the same size and having the same color and the same brightness as the background when the colors are different from each other and are superimposed are formed. When the subject responds to the flicker of the optotype generated when the period is lengthened, the first and second optotypes are alternately superimposed and displayed at a predetermined position on the background with a change in the cycle. A visual field measurement method, comprising: determining a period; and measuring a flicker visual field based on the determined period. 2. An optotype is formed at a predetermined position on a background of a predetermined color, and the optotype is formed by two light sources that generate light having the same color and the same brightness as the background when the colors are different from each other and are superimposed. By illuminating alternately and alternately by changing the period, determining the period when the subject responds to the flicker of the optotype that occurs when the period is lengthened, measuring the flicker visual field based on the determined period. Characteristic visual field measurement method. 3. A light source from two light sources, which form a background of a predetermined color and emit light having the same color and the same brightness as the background when the colors are different from each other and are superimposed, alternately by changing the period. The projected image is superimposed and projected on the predetermined position of the background so as to have the same size, and the period when the subject responds to the flicker of the optotype generated when the period is lengthened is determined. A visual field measuring method, comprising measuring a flicker visual field based on the flicker visual field. 4. A means for forming a background of a predetermined color, and means for forming first and second optotypes of the same size which are different from each other and have the same brightness and the same color as the background when superimposed. Means for alternately displaying the first and second optotypes at a predetermined position on the background without displacement, and means for changing the display cycle of the first and second optotypes. A field-of-view measuring apparatus comprising: means for calculating a cycle when the subject responds to the flicker of the optotype generated when the length is increased; and means for calculating a flicker visual field based on the calculated cycle. 5. The visual field measuring device according to claim 4, wherein the background and the visual field are formed on a CRT via a character generator.