JPH0392135A - Apparatus and method for vep examination - Google Patents

Abstract

PURPOSE:To improve an efficiency of visually evoked potential(VEP) examination by constituting a display device for fixation position with a photo-display device and also by varying its displayed shape regularly and irregularly. CONSTITUTION:Electrodes (different electrode, indifferent electrode, earth electrode) 20 are fitted to respective set position of a subject, and a change-over cycle of pattern stimuli, a position of fixation mark 16, necessary examination conditions, etc., are set up by respective setting units. Under a condition that the subject is made to face a VEP stimulus display equipment 10 and watch the fixation mark 16, stimulation patterns and the fixation mark 16 are changed in respectively set cycles. The subject is made to operate a response instrument 34 for recognition of fixation mark change at every instant that the fixation mark 16 is changed into a specified displayed shape, and the VEP examination is continued while a cycle number of the recognized shape of fixation mark 16 is counted up by a counter circuit 32. It is possible, therefore, to improve an examination efficiency and accuracy.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a VEP testing device for performing a VEP test as a type of visual function test, and a VEP testing method using the same, and particularly relates to a method for improving the testing efficiency of a VEP testing device. The present invention relates to techniques for improving test accuracy and test accuracy, and techniques for objectively understanding the reliability of VEP test results.

(Background technology) VEP (visual evoked potential)
Potential) test detects brain waves emitted from the visual area of the brain when a stimulus applied to the retina is recognized by the visual area of the brain, and determines whether or not there is a disorder in the visual signal pathway from the retina to the visual area. This test is used to examine the brain waves from the detected waveforms of the brain waves, and is used to examine infants whose visual function is difficult to evaluate, other patients whose fundus cannot be seen through due to opacity of the anterior station or intermediate transmissive body, optic nerve diseases, and psychogenic diseases. It is generally used when evaluating the visual function of visually impaired people.

By the way, such VEP tests are roughly divided into pattern VEP tests and flash VEP tests, depending on how stimulation is applied to the eye of the subject. The former is achieved by changing the pattern displayed on a screen such as a CRT, generally by inverting the black and white checkerboard or grid pattern displayed on a screen such as a CRT at a predetermined frequency. It is said to provide stimulation for optometry and is said to reflect the central function of the retina more than the latter, while the latter uses flashing light to stimulate the eye being examined. , is said to cover a wider range of the retina than the former. In general, it can also be used in cases where the crystalline lens is clouded due to cataracts, etc.
Flash VEP testing is more commonly employed than pattern VEP testing.

In this type of VEP inspection, whether it is a pattern VEP inspection or a flash VEP inspection, in order to improve the inspection accuracy, it is necessary to set the position (gazing position) according to the purpose of the inspection. It is required to keep the subject's line of sight fixed.

Therefore, in pattern VEP inspection, a fixation mark such as a sticker is pasted at the gaze position, and a flash VEP
During the examination, a fixation light such as a red light emitting diode is placed at the fixation position, and the subject is made to gaze at the fixation mark or fixation light, thereby fixing the subject's line of sight at the desired gaze position. Efforts are being made to make this happen.

However, these pattern VEP inspections and flash VE
In VEP tests such as P tests, the detection potential of the fan wave from the visual area obtained as a result of these tests is extremely weak, and in the case of pattern VEP tests, pattern stimulation displayed on a screen such as a CRT is used. In addition, in the case of a flash VEP test, it is necessary to repeatedly apply a flash stimulus by flashing light dozens of times and add up the detection signals obtained for each stimulus, and the test requires at least 1 minute. Because it takes such a long time, it is extremely difficult to keep the examinee's line of sight, especially children and elderly people's lines, fixed on the same vision mark or fixation light during that time, which makes the test results reliable. V
There was a problem in that the EP test had to be repeated many times.

(Problem to be Solved) The present invention has been made against the background of the above, and its problem is to simply place a fixation mark or fixation mark at the gaze position where the examinee's line of sight is to be fixed. Compared to the case where only a visual position display means such as a sight lamp is provided, the subject's line of sight is better fixed at the gaze position, thereby improving VE.
It is an object of the present invention to provide an EP testing device that can improve the reliability and testing efficiency of P testing, and another object of the present invention is to provide a VEP testing device using such a VEP testing device. In this case, the object is to obtain the rate of gaze of the subject with respect to the visual position display means, so that the reliability of the VEP test result can be objectively grasped as a numerical value.

(Solution Means) In order to solve this problem, in the device of the present invention, a fixation position display is arranged at a position where the subject should gaze and is used to fix the line of sight of the subject at the gaze position. In the VEP testing device, the cough fixation position display means is controlled by an optical display means, and an optical display form changing means is provided for regularly or irregularly changing the display form of the optical display means. The decision was made to establish one.

In addition, in the method of the present invention, during a VEP test using such a VEP test device, the fixation position display means is optically changed regularly or irregularly to detect the position that the subject is aware of. The ratio between the number of changes and the actual number of changes of the fixation position display means is determined, and the reliability of the VEP test results is determined from that ratio.

In addition, in the device of the present invention, various modes can be adopted as modes of changing the display mode of the optical display means by the optical display mode changing means, but in general, blinking, discoloration and shape change of the optical display means, and A combination thereof will be suitably employed.

The device of the present invention also includes an input means for sequentially inputting a change in the light display means each time the subject recognizes the change, and an input means for inputting the change in the light display means sequentially, and the number of changes in the light display means inputted by the human power means. Providing a counting means for counting is effective in further improving test efficiency and test accuracy, and in making it possible to objectively understand the reliability of test results to some extent.
preferable.

Furthermore, the apparatus of the present invention may be provided with gaze degree calculation means for calculating the ratio between the number of times the light display means is actually changed by the light display form changing means and the number of times the subject recognizes the change in the light display means. , is desirable for understanding the reliability of test results as an objective numerical value.

(Function) In the VEP testing device according to the present invention, since the subject looks at the optical display means whose display form changes regularly or irregularly as the fixation position display means, the fixation mark of the conventional device is Compared to gazing at a fixation position indicator that does not change in any way, such as a fixation lamp, the subject's attentiveness to the fixation position indicator increases, and the subject's line of sight changes to the fixation position. The display means facilitates good fixation,
Therefore, the inspection accuracy and inspection efficiency of the VEP inspection can be improved accordingly.

Then, during the VEP test using the device of the present invention, the degree of gaze (fixation rate) of the subject toward the fixation display device is determined according to the method of the present invention, and the reliability of the VEP test results is determined from the degree of gaze. By doing so, it is possible to numerically and objectively judge the reliability of VEP test results, and as a result,
It becomes possible to further improve the inspection efficiency of VEP inspection.

In addition, in the VEP testing device according to the present invention, if the above-mentioned input means is provided and the subject is made to input the information every time a change in the optical display means is recognized, it can be used as a fixation position display means. Compared to simply gazing at the light display means, the examinee will have a greater sense of purpose in gazing at the light display means, so the examinee's line of sight will be directed toward the light display means as a visual position display means. As a result, the inspection accuracy and efficiency of VEP inspection are further improved, and by providing a counting means as described above, it is possible to prevent changes in the optical display means inputted by manual means. By counting the number of recognitions by the examiner, it becomes possible to objectively understand the degree of gaze of the examinee toward the fixation position display means (light display means) from the counted value, and the test results It becomes possible to judge the reliability of the information objectively to some extent.

Furthermore, if the apparatus of the present invention is provided with a gaze degree calculation means as described above, it is possible to numerically and more accurately know the degree of gaze of the subject with respect to the optical display means as the fixation position display means from the calculation result. As a result, it becomes possible to objectively and extremely accurately grasp the reliability of the test results of the VEP test.

(Example) Hereinafter, in order to clarify the present invention more specifically,
The embodiment will be explained in detail based on the facts.

First, in No. 1-2, an example of a pattern VEP inspection apparatus according to the present invention is schematically shown in a block diagram. There, 10 is a V made of an image display device such as a CRT.
This is an EP stimulation display device, on whose screen a predetermined stimulation pattern is displayed by a pattern stimulation generation circuit 12, and the stimulation pattern is a predetermined stimulation pattern suitable for VEP testing. It is designed to be periodically switched at a frequency (usually a frequency of about several Hz). Here, a black and white checkered pattern consisting of light emitting parts (white) and non-light emitting parts (black) as shown in FIG. 2 is adopted as the stimulation pattern, and the stimulation pattern switching period setting device (not shown) The checkered pattern is reversed in black and white at the period set by , and pattern stimulation is repeatedly applied to the test subject's area.

Furthermore, as shown in FIG. 2, the fixation mark generation circuit 14 displays on the screen of the VEP stimulation display device 10,
A fixation mark 16 whose display form changes regularly or irregularly at a predetermined cycle or an average cycle is displayed in a state that can be easily distinguished from the stimulation pattern. This fixation mark 16 is used to clearly indicate the gaze position that the examinee should gaze upon during the VEP examination, and is used by the fixation mark display position setting device 8 to
The fixation mark 16 can be displayed at any position on the screen of the stimulus display device 10, and here, a circular area with a diameter of about 5 to 10++a is used as the display area of the fixation mark 16, and a fixation mark (not shown) is displayed. The average frequency set with the mark switching cycle setting device, which is usually about 10 to 20 times per minute, causes the entire circular area to regularly or irregularly flash ON/○FF (black and white inverted). (see FIG. 3), the display form of the fixation mark l6 is changed. As is clear from this, here, the fixation mark 16 functions as an optical display means as a fixation position display means, and the fixation mark 16 is not displayed on the screen of the VEP stimulus display device IO. The blinking fixation mark generation circuit 14 acts as an optical display form changing means.

On the other hand, in FIG. 1, 20 is attached to the subject,
These are electrodes for detecting brain waves generated from the visual area of the subject's brain, and are connected to an averaging circuit 24 via an amplifier 22. This average addition circuit 24 is for averaging the electroencephalogram potential signals as VEP detection signals extracted by the electrodes 20 in synchronization with the switching of stimulation patterns by the pattern stimulation generation circuit 12 in the same manner as in the past. The final addition result of the average addition circuit 24 is supplied to the VEP waveform recording device 26 as a VEP detection signal. Then, in the VEP waveform recording device 26, the VEP from the average addition circuit 24 is
The detection signal is displayed as a waveform in a predetermined format. Note that this VEP waveform recording device 26 may be a monitor device, a printer device such as an XY recorder, or the like.

By the way, each time the display form of the fixation mark 16 goes around, the fixation mark generation circuit 14 more specifically:
A fixation mark change signal is output each time the fixation mark 16 becomes a specific display format (for example, a lit display format; a white display format), and this fixation mark change signal is used as a fixation mark change signal. The signal is continuously supplied to the number counting circuit 28. The fixation mark change count circuit 28 counts the fixation mark change signals supplied during the test period from the start of the test to the end of the test, and supplies the counting result to the fixation rate calculation circuit 30. It has become. Note that the test start command may be issued when the subject first operates the fixation mark change recognition response device 34, which will be described later, or may be issued by operating a dedicated test start command switch. You can also do this. Further, the test end command may be issued when the number of changes in the visual mark 16 or the number of times the pattern stimulation is switched reaches a preset number, or may be issued by operating a dedicated test end command switch. You can also do this.

In addition, the fixation rate calculation circuit 30 to which the count value from the fixation mark change count circuit 28 is inputted, calculates the number of cycles of the display form of the fixation mark 16 recognized by the subject during the examination period. A fixation mark change recognition frequency counting circuit 32 is connected to count the number of times the fixation mark change is recognized.
From this fixation mark change recognition frequency counting circuit 32, the number of cycles of the display form of the fixation mark 16 recognized by the subject during the examination period is inputted.

That is, the fixation mark change recognition frequency counting circuit 32 has the following:
The fixation mark change recognition and response device 34, which is operated by the subject and consists of a push button as shown in FIG. Specifically, each time the subject recognizes that a predetermined specific display form, for example, a lighting state form, has newly appeared, and the fixation mark change recognition response device 34 is operated by the subject. , a fixation mark change recognition signal is input from the fixation mark change recognition response device 34. The fixation mark change recognition number counting circuit 32 counts the fixation mark change recognition signal supplied from the fixation mark change recognition response device 34 during the VEP test period, and after the test is finished, the counted value, i.e. The number of cycles of the display form of the fixation mark 16 recognized by the subject during the examination period is supplied to the fixation rate calculation circuit 30.

Then, after the VEP test is completed, the fixation rate calculation circuit 30
The count from the fixation mark change count circuit 28 and the count from the fixation mark change recognition count circuit 32 {1! !
: Percentage of P: (P/T) It has become.

As is clear from the above description, here, the fixation mark change recognition response device 34 serves as an input means for manually indicating that the subject has recognized a change in the optical display means, and The fixation mark change recognition number counting circuit 32 that counts the fixation mark change recognition signal from the fixation mark change recognition response device 34 has a counting means that counts the number of changes in the optical display means manually inputted by the input means. In addition, the fixation rate calculation circuit 30 calculates the degree of gaze (
This constitutes a gaze degree calculation means for calculating the fixation rate).

Note that each circuit in the device of this embodiment and the calculation or control function section of the device are usually configured by a microcomputer.

Next, the operation when performing a pattern VEP inspection using such a system will be described.

That is, when performing a pattern VEP test using the apparatus of this embodiment, first, as shown in FIG. At the same time, necessary test conditions such as pattern stimulation switching cycle setting, fixation mark l6 display position setting, switching cycle setting, etc. are set using the corresponding setting devices. Then, with the subject directly facing the VEP stimulation display device 10 and gazing at the fixation mark 16, a test start command is issued, and the stimulation pattern and fixation mark 16 are changed at respective set cycles. The subject operates the fixation mark change recognition response device 34 each time the fixation mark l6 changes to a predetermined specific display form, and the number of cycles of the display form of the fixation mark 16 recognized by the subject is determined. The VEP test is continued while being counted by the fixation mark change recognition frequency counting circuit 32 until a test end command is issued.

In addition, if the fixation mark change recognition number counting circuit 32 is provided with a function that limits the counting function of the fixation mark change recognition signal only during the examination period, the fixation mark change recognition by the subject The response device 34 may be operated before and after the test period.

In addition, such a VEP test is normally performed with the fixation mark l6 displayed at the center of the screen, but depending on the purpose of the test, the fixation mark may be fixed at a position a predetermined distance above or below the center. This may be done by displaying a mark. In short, the fixation mark 16 may be displayed at a position depending on the purpose of the examination.

When the test is finished by the test end command, a VEP detection signal similar to the conventional one detected by the electrode 20 and averaged by the averaging circuit 24 is sent to the VEP waveform recording device 2.
6, and the potential waveform of the VEP detection signal is recorded as a waveform by a VEP waveform recording device 26.

Separately, a circuit for counting the number of times the visual mark changes 28
The number of cycles of the display form of the fixation mark 16 counted during the VEP test period is supplied to the fixation rate calculation circuit 30, while the fixation mark recognized by the subject during the VEP test is supplied to the fixation rate calculation circuit 30. The count value P of the fixation mark change recognition count circuit 32, which is the number of cycles of the 16 display formats, is supplied to the fixation rate calculation circuit 30, and the ratio thereof, that is, VE
The fixation rate (gazing degree) of the subject for the fixation mark 16 during the P test period is percentage: (P/T)XIOO
(%).The calculation result is then supplied to the fixation rate display device 36, where it is displayed numerically.

Therefore, according to the device of this embodiment, the degree to which the subject was gazing at the fixation mark 16 during the VEP test period (fixation degree;
This makes it possible to determine the reliability of the VEP detection waveform displayed by the VEP waveform recording device 26 objectively and extremely accurately. In other words, if the reliability of the VEP test result is determined from the value of the fixation rate (gazing degree) displayed on the fixation rate display device 36,
The reliability of VEP test results can be objectively and extremely accurately judged, and as a result, a significant improvement in the test efficiency of VEP tests can be expected.

Note that here, a standard fixation rate is set in advance as a standard for determining whether or not the VEP test result is reliable, and the actual fixation rate calculated by the fixation rate calculation circuit 30 is set as the standard. When the measured fixation rate exceeds the standard fixation rate compared to the fixation rate, the fixation rate display device 36 displays this in a predetermined display format.
etc., so that it can be immediately recognized from the display whether the VEP test result is reliable or not. In this way, it is possible to immediately determine whether or not the VEP test results are reliable.
The P inspection work becomes easier, and the inspection efficiency of the VEP inspection is further improved.

By the way, in the device of this embodiment, as mentioned above, V
During the EP test period, the fixation mark 16 that the subject is gazing at is blinked at a predetermined cycle, and the subject's focus on the fixation mark 16 is higher than when the subject is gazing at a fixation mark whose display form does not change at all. Since the subject's attention is better aroused, the subject's line of sight is fixed on the fixation mark 16.
This facilitates better fixation, making it easier for the subject's line of sight to be maintained at the gaze position. Therefore, to the extent that the subject's line of sight is easily maintained at the gaze position, the VEP
The inspection accuracy and efficiency of inspection will be improved compared to conventional devices.

In addition, in the present embodiment device, as described above, the fixation mark change recognition response device 34 is provided, and during the VEP test period, when the fixation mark l6 of a predetermined specific display form is recognized, The fixation mark change recognition response device 34
Since the examinee is made to operate the fixation mark 16, the examinee will have a greater sense of purpose in gazing at the fixation mark 16 than when simply gazing at the fixation mark 16. The examiner's line of sight can be better fixed on the same vision mark l6. In other words, the response device W3
By the operation in step 4, the inspection accuracy and inspection efficiency of the VEP inspection are further improved.

The embodiments of the present invention have been described in detail above, but the present invention
Of course, it is possible to implement the present invention in a manner other than that illustrated.

For example, in the embodiment described above, the display form of the fixation mark 16 as a light display means serving as a fixation position display means is changed by blinking in a certain area, but the display form of the fixation mark 216 is changed by blinking a certain area. may also be changed in a manner other than that illustrated. FIGS. 5 to 7 show examples of other preferable display forms of the fixation mark 16.

In other words, in the fifth example, a certain area is changed from white → red → black → white →...
6 shows a mode in which the display form of the fixation mark 16 is changed by regularly or irregularly changing the color between a plurality of colors, and FIG. , stars and black dots) are repeatedly displayed to change the display form of the fixation mark 16.
Furthermore, FIG. 7 shows a mode in which the display form of the fixation mark 16 is changed by changing the shape of the display area itself of the fixation mark 16 into mutually different shapes (here, a circle and a square). Of course, it is also possible to adopt changes in the display form of the fixation mark 16 by appropriately combining these forms.

In addition, when calculating the fixation rate (gazing degree) of the fixation mark l6 during the examination period by counting the number of times the change in the fixation mark l6 is recognized, which of the changes in the display form of the fixation mark l6 is calculated? Regardless of whether this mode is adopted, the subject may be asked to count specific display formats determined in advance.

Furthermore, the fixation mark 16 is required to have a size that allows good discrimination of changes in the display form of the fixation mark 16 without being confused with the stimulus pattern.
If the size is too large, changes in the stimulation pattern cannot be recognized well, so the fixation mark l6 is usually about 30 squares or less in size, preferably 5 in size as in the above embodiment.
The size will be approximately 10 meters square.

Further, in the embodiment, the same viewing rate calculation circuit 30 is provided as a gaze degree calculation means, and the fixation rate (gazing degree) of the fixation mark 16 during the examination period is calculated and displayed. However, it is also possible to display the count value of the fixation mark change recognition count circuit 32 as a counting means as it is, and to judge the reliability of the VEP test result from the count value. Change recognition response device 34
In place of the fixation mark change recognition frequency counting circuit 32, an input device capable of inputting the fixation mark change recognition frequency value is connected to the fixation rate calculation circuit 30, and a dedicated counting device such as a counter is used, or After the end of the VEP test, input the number of times of recognition of changes in the fixation mark 16 during the VEP test period, which was counted by the subject without using it, into the fixation rate calculation circuit 30 from the human-powered device, It is also possible to calculate and display the fixation rate during the VEP test period based on the input value. Note that even if the fixation mark change recognition response device 34, the fixation mark change recognition frequency counting circuit 32, and the fixation rate calculation circuit 30 are all omitted, the effects of the present invention can still be achieved.

Furthermore, in the above description, only an example in which the present invention is applied to pattern VEP inspection has been described, but it is also possible to apply the present invention to flash VEP inspection. That is, in the device of the embodiment, a flash stimulus generation circuit is provided in place of the pattern stimulus generation circuit 12, and the VB
By generating a flash stimulus at a predetermined period on a predetermined screen area of the P stimulus display device 210, a flash VEP test can be performed while ensuring the same effect as in the embodiment described above.

Note that both the pattern stimulus generation circuit 12 and the flash VEP stimulus generation circuit are provided so that they can be selectively activated, so that both the pattern VEP test and the flash VEP test can be performed with a common device. It is also possible.

Further, the present invention can also be applied to a flash VEP inspection device having a structure similar to the conventional one, in which a fixation light such as a red light emitting diode is arranged in the center of a U-shaped xenon lamp. In this case, it is desirable to blink the fixation lamp as the optical display means, which is the fixation position display means, to change the display form of the optical display means.

In addition, although it is omitted to list specific examples one by one, the present invention can be carried out in various forms with various changes, modifications, improvements, etc. based on the knowledge of those skilled in the art without departing from the spirit thereof. It goes without saying that it can be done.

(Effects of the Invention) As is clear from the above description, according to the VEP testing device according to the present invention, the subject's line of sight is more likely to be fixed on the fixation position display means than in the conventional device.
The inspection efficiency and inspection accuracy of the inspection will be improved accordingly compared to the conventional device, and according to the present invention, the V
If the reliability of EP test results is determined, VEP
It becomes possible to determine the reliability of test results extremely objectively, and as a result, it becomes possible to significantly improve the test efficiency of VEP tests.

In the apparatus of the present invention, an input means is provided that allows the subject to input the information every time a change in the light display means is recognized, and the test subject recognizes the change in the light display means inputted by the input means. By providing a counting means for counting the number of times, attention to the optical display means can be effectively improved, and VEP
It becomes possible to further improve the inspection efficiency and accuracy of the inspection, and it also becomes possible to objectively understand the reliability of the test results to some extent from the counting results of the counting means, and also to improve the gaze level calculation means. If the degree of gaze of the subject to the fixation position display means is determined during the test period, the reliability of the test results can be determined objectively and extremely accurately based on numerical values. be.

[Brief explanation of drawings]

FIG. 1 is a block diagram schematically showing an example of a pattern VEP testing device according to the present invention, and FIG. 2 shows a stimulus pattern and a fixation mark on the screen of the VEP stimulation display device in the device of FIG. FIG. 3 is a diagram showing a display example; FIG. 3 is a diagram for explaining how the display form of the fixation mark changes in the device shown in FIG. 1; and FIG. 4 is a diagram showing how the device in FIG. 1 is used. It is an explanatory diagram for explaining. Fifth
6 and 7 respectively correspond to FIG. 3 of another embodiment of the present invention. 1 0: VEP stimulus display device 12: Pattern stimulus generation circuit 4: Same vision mark generation circuit 16: Fixation mark 26/VEP waveform recording device 30: Fixation rate calculation circuit 32: Fixation mark change recognition count circuit 34: Fixation mark change recognition response device 36: fixation rate display device

Claims (7)

[Claims] (1) In a VEP inspection device equipped with a fixation position display means arranged at a position to be gazed and used to fix the subject's line of sight at the gaze position, the fixation position display means is displayed optically. What is claimed is: 1. A VEP inspection device comprising: an optical display mode changing device for regularly or irregularly changing the display mode of the optical display device. (2) The VEP inspection apparatus according to claim 1, wherein the optical display form changing means causes the optical display means to blink. (3) The VEP inspection apparatus according to claim 1 or 2, wherein the optical display form changing means changes the color of the optical display means. (4) The VEP inspection apparatus according to any one of claims (1) to (3), wherein the optical display form changing means changes the shape of the optical display means. (5) An input means for sequentially inputting the change each time the subject recognizes a change in the light display means, and counting the number of changes in the light display means inputted by the input means. 4. The VEP testing device according to claim 1, further comprising a counting means. (6) It is characterized by including a gaze degree calculation means for calculating the ratio between the number of times the light display means is actually changed by the light display form changing means and the number of times the subject recognizes the change in the light display means. The VEP inspection device according to any one of claims (1) to (5). (7) During the VEP test, the fixation position display means is optically changed regularly or irregularly, and the number of changes perceived by the subject and the actual number of changes of the fixation position display means are calculated. VE according to claim (1), characterized in that the reliability of the VEP test result is determined from the ratio.
A VEP inspection method using a P inspection device.