JP4892742B2 - Perimeter and visual field measurement method - Google Patents

Description

  The present invention relates to an apparatus and method for measuring a visual field of a subject.

  The visual field inspection includes a “subjective inspection method” performed based on the subjective reaction of the subject and an “objective inspection method” that objectively measures the physiological index of the subject. In many visual field inspections, a subjective inspection method is used in which a reaction is made when a target (target) is seen. However, the subjective examination method cannot be used for subjects who cannot properly express a response (for example, children and children with intellectual disabilities).

As an objective examination method, there are the following methods.
1. Visual field inspection by ERG (electroretinogram):
In this method, local ERGs in a plurality of parts of the retina are recorded one after another, and an objective visual map of the retina is created using the amplitude. In recent years, a technique (multi-input technique) has been developed that simultaneously stimulates multiple parts of the retina using fast random stimulation, and it has become possible to simultaneously record more than 100 local ERGs. In this method, a monochrome pattern using a large number of hexagons is displayed on a monitor. This pattern is randomly changed at a fast frequency, and the electrical response obtained from the cornea is mathematically analyzed to simultaneously record the local ERG of each part. The response obtained by local ERG is thought to reflect mainly the activity of the retinal cone pathway. Therefore, it is useful when the retinal function and the optic nerve or central function are separately measured.
2. Field examination by pupil movement (pupil perimetry):
The pupil perimeter measures the sensitivity of the retina at a certain place on the visual field from the magnitude of the light response by recording the pupil response (light reflection) caused by the presentation of the target. In principle, the retinal sensitivity at the visual field position can be measured with a single stimulus presentation. As an apparatus, an infrared electronic pupillometer is incorporated into a normal automatic perimeter.
3. Blink perimetry by eye movement (fixation movement):
When a visual target enters the visual field, an eye movement (fixation movement) that tries to glance by moving the eye toward the visual target usually occurs. An objective examination method that measures the visual field using the occurrence of fixation movement is visual examination by fixation movement, which is called blink perimetry. It is a method used for visual field inspection of children who have difficulty in fixing the fixation point.
4. Visual field examination by nystagmus:
When the target of the black and white vertical stripe is reciprocated, nystagmus is induced. Measuring the visual field based on the presence or absence of nystagmus is a visual field inspection using nystagmus. A method is adopted in which only the visual field position to be measured is visible and the presence or absence of nystagmus is confirmed.

  As shown in 3 above, there has been an objective visual field evaluation method using eye movements (ie, visual field measurement). However, in the visual field evaluation, the subject's reaction itself is objective, but it is the subjective judgment by the measurer who is looking at the movement of the eye that can be obtained. The result is not objective. Moreover, in order to improve the reliability of the evaluation, the ability and proficiency of the measurer are required.

On the other hand, in the following Non-Patent Document 1, objective visual field measurement using eye movement is performed for children with intellectual disabilities. However, in this method, the target presentation time is 1 second. The presentation time of 1 second is considered to be a very long presentation time when considering visual field measurement. The human fixation point naturally fluctuates in a considerable range when there is a time of about 1 second. Therefore, the fact that there is a presentation time of 1 second makes it unclear whether the target was discovered due to the saccade or the movement of the fixation point itself. That is, in the technique of Non-Patent Document 1, it is quite doubtful whether the visual field obtained by this accurately reflects the visual field of the subject.
Nakajima Kazuo, Katagiri Kazuo, Matsuno Yutaka, 1977, Reflexive eye movement and objective visual field measurement in children with intellectual disabilities, Special Education Studies, 15, 1, 14-21

  The present invention has been made in view of the above situation, and an object of the present invention is to provide an apparatus and method that can objectively and accurately measure the visual field.

The perimeter according to the present invention includes an eye movement measurement unit, a control unit, and an output unit. The eye movement measurement unit is configured to objectively measure eye movement. The output unit is configured to present the visual target for a time equal to or shorter than the saccade latency in a range that is visible to the subject. The control unit is configured to determine the occurrence of a saccade based on the presentation of the target based on the eye movement measured by the eye movement measurement unit after the target is presented in the output unit. Yes.
The control unit may determine whether the saccade is generated when the eyeball position measured by the eyeball movement measurement unit is substantially equal to the presentation position of the target.

  The output unit may present a fixation point before presenting the target and present the target immediately after deleting the fixation point.

  The output unit may be configured to present the visual target in an area other than the area that the subject is viewing. In this case, presentation of the fixation point can be omitted.

  The output unit may be configured to present a reinforcer that can be perceived by a target person after the control unit determines that the eyeball position and the presentation position of the visual target are substantially equal.

  The control unit may determine whether the saccade is generated when a moving direction of the eyeball position measured by the eyeball movement measuring unit is a direction toward the presentation position of the visual target.

  The control unit may determine whether the saccade has occurred due to an increase in the amount of movement of the eyeball position measured by the eye movement measurement unit.

The visual field measuring method according to the present invention comprises the following steps:
(1) A step of presenting a visual target in a range that can be visually recognized by the subject;
(2) Thereafter, the step of erasing the target within a time equal to or less than the saccade latency;
(3) After that, the generation | occurrence | production of the saccade based on the presentation of the said target is determined based on the eye movement of the said subject.

  The determination of the occurrence of the saccade in the step (3) can be performed, for example, when the eyeball position of the subject and the presentation position of the visual target are substantially equal.

  The determination of the occurrence of the saccade in the step (3) can also be performed when the moving direction of the eyeball position of the subject is the direction toward the presentation position of the visual target.

  The determination of the occurrence of the saccade in the step (3) can also be performed by an increase in the movement amount of the eyeball position of the subject.

  According to the perimeter and the visual field measurement method of the present invention, the visual field can be objectively and accurately measured.

(Configuration of the first embodiment)
First, the perimeter according to the first embodiment of the present invention will be described with reference to FIG.

  This perimeter includes an eye movement measurement unit 1, a control unit 2, an output unit 3, and a storage unit 4.

  The eye movement measuring unit 1 is configured to objectively measure the eye movement. As such a measurement unit 1, for example, an existing eye movement measurement device using an infrared sensor can be used. According to such a measuring apparatus, for example, the position of the eyeball can be recorded with a high frequency of every 20 ms. Thereby, it is possible to know what speed and what trajectory the eyeball has moved.

  The output unit 3 includes a display unit 31 and a speaker 32 in the present embodiment.

  The display unit 31 of the output unit 3 is configured to present the visual target for a time equal to or shorter than the saccade latency in a range that is visible to the subject. The saccade latency is the time from when the visual target appears in the visual field until eye movement occurs, and is usually about 200 ms. Furthermore, the output unit 3 of the present embodiment is configured to present the fixation point before presenting the optotype and to present the optotype immediately after deleting the fixation point. A specific example of the target presentation will be described in the description of the operation described later. The display unit 31 is a display using a CRT or a flat panel, for example.

  The display unit 31 and the speaker 32 of the output unit 3 are configured to present a reinforcer that can be perceived by the subject after the control unit 2 determines that the eyeball position and the target position are substantially equal. A reinforcer is information that can be perceived by a subject and can increase the frequency of occurrence of saccades. A specific example of presenting the reinforcement will be described later.

  After the control unit 2 presented the visual target in the output unit 3, whether the visual target was found from the relationship between the eyeball position change direction, the amount of change, and the position information, and the target display position in the trial. It is configured to determine whether or not. Specifically, the control unit 2 of this embodiment is configured to determine whether or not the eyeball position and the target position are substantially equal. Whether or not the eyeball position and the target position are substantially equal is determined by whether or not the difference between the eyeball position measured by the eye movement measuring unit 1 and the known target position is 2 ° or less, for example. It can be carried out.

  The storage unit 4 stores various kinds of computer software and initial data (for example, data for presenting a target and data for presenting a reinforcement) necessary for the operation of the control unit 2, and further controls the control unit 2 and eye movement measurement. This is a part for storing various data acquired by the unit 1.

(Operation of the first embodiment)
Next, a visual field measurement method using the perimeter according to the present embodiment will be described with reference to the flowchart of FIG.

(Step Sa-1)
First, based on a control command from the control unit 2, as shown in FIG. 3A, the fixation point 5 is presented on the display unit 31 of the output unit 3. In this example, the fixation point 5 is a cross-shaped mark.

(Step Sa-2)
The eye movement measurement unit 1 starts measuring the eyeball position. The eye movement measurement unit 1 constantly monitors the eye movements of the subject and sends the acquired eye movement data to the control unit 2. The control unit 2 stores eye movement data in the storage unit 4.

(Step Sa-3)
Next, the control unit 2 determines whether or not the subject is staring at the fixation point 5. This determination can be made, for example, under the condition that the eyeball position measured by the eyeball movement measurement unit 1 exists in the vicinity of the fixation point 5 for a certain period of time. That the eyeball position is in the vicinity of the fixation point 5 is, for example, that there is little difference between the actual eyeball position and the eyeball position when it is assumed that the fixation point 5 is viewed (for example, 2 as the angle of the eyeball center). Or less). Further, the “a certain amount of time” described above is, for example, 500 ms. After it is determined that the subject is staring at the fixation point 5, the process proceeds to step Sa-4.

(Step Sa-4)
After it is determined that the subject is staring at the fixation point 5, based on the control command from the control unit 2, the target is displayed on the display unit 31 of the output unit 3 as shown in FIG. 6 is presented. That is, the visual target 6 is presented in a range that can be visually recognized by the subject. In addition, the fixation point 5 is erased immediately before the target 6 is displayed. That is, in this embodiment, the target 6 is presented immediately after the fixation point 5 is deleted. Thereby, it is possible to prevent the presence of the fixation point 5 from affecting the visual field measurement and improve the accuracy of the visual field measurement.

  Here, in this specification, “immediately after erasing the fixation point 5” includes a case where the fixation point 5 is erased at the same time. In this embodiment, the target 6 is presented simultaneously with the erasing of the fixation point 5. Even after the fixation point 5 is erased, it is included immediately after a time in a range in which eye movement is unlikely to occur (this time is obtained experimentally or empirically). This is because even after the fixation point 5 is erased, the accuracy of the visual field measurement is not deteriorated so much unless excessive eye movement occurs.

(Step Sa-5)
Thereafter, the target 6 is turned off within a time shorter than the saccade latency. That is, it is set as the state which cannot be visually recognized from a subject (that is, it returns to the state of FIG. Here, the latency of a saccade is usually about 200 ms. An example of the display timing of the optotype 6 is indicated by the symbol A in FIGS. In this example, the visual target 6 is presented at a position of about 15 ° (an angle in the horizontal plane). In the example of FIG. 4, the display time of the visual target 6 is 200 ms from 0 ms to 200 ms. 4A shows an example in which the visual target 6 is presented at a position 15 ° from the fixation point 5, and FIG. 4B shows an example in which the visual target 6 is presented at a position 9 ° from the fixation point 5. (C) is an example in which the target 6 is presented at a position 3 ° from the fixation point 5.

  The eye movement measurement unit 1 continues to acquire and send the eye movement data of the subject to the control unit 2 even after step Sa-5 described above.

(Step Sa-6)
The control unit 2 presents the target 6 within a predetermined time (for example, 1 second) from the relationship between the eyeball position change direction, the amount of change, and the position information, and the target display position in the trial, It is configured to determine whether the target has been found. Specifically, it is determined whether the eyeball position and the target position are substantially equal. This determination can be made, for example, by a small difference (for example, 2 ° or less) between the actual eyeball position and the eyeball position when it is assumed that the target 6 has been viewed.

  4A to 4C, an example of eye movement after the target 6 is erased is indicated by the symbol B in FIG. Although it may take a certain amount of time, it can be seen that a saccade is generated even after the target 6 is turned off. It can also be seen that when a saccade is generated, the eyeball position and the target position are very close.

  If the determination in step Sa-6 is No after the predetermined time has elapsed, it means that no saccade has occurred, and it can be determined that no target has been found.

(Step Sa-7)
If the determination in step Sa-6 is Yes, the control unit 2 stores the eye movement and the target position in the storage unit 4. Thereby, a target position and eye movement can be memorized.

  Furthermore, the control unit 2 sends the reinforcement to the display unit 31 and the speaker 32 of the output unit 3.

  The reinforcer sent to the display unit 31 is, for example, an image 61 (see FIG. 3C) as if the visual target 6 exploded, and this is presented on the display unit 31. The reinforcer presented on the display unit 31 may be a mark having a conspicuous color such as red.

  The reinforcement transmitted to the speaker 32 is, for example, explosion sound. The enhancer presented by the speaker 32 is preferably a sound that is exciting to the user, but may be a simple sound such as a beep sound.

  These reinforcers make it possible to enjoy visual field measurement like a shooting game and concentrate it.

(Step Sa-8)
After step Sa-7, the measurement is temporarily terminated. When further measurement is performed, the process returns to step Sa-1 and the subsequent operations are repeated. This repetitive operation is performed manually or automatically based on a command from the control unit 2. When the operation stop operation is performed, the operation of the apparatus stops.

  In the present embodiment, the occurrence of a saccade based on the target presentation can be determined based on the eye movement obtained by the eye movement measuring unit 1, and thus the visual field of the subject can be objectively measured. That is, in the present embodiment, the target 6 is presented for a very short time when looking at the fixation point 5, and it is determined that a saccade based on the target 6 has occurred. When a saccade is generated, it can be determined that “the presentation position of the target 6 is within the visual field centered on the fixation point 5”.

  In the perimeter of the present embodiment, as described above, for example, the eye movement can be recorded at a high frequency of every 20 ms from the start point of gaze. If the target 6 is presented for a long time (for example, 1 second) and eye movements are recorded during that time, the target presentation time exceeds the saccade latency, so the position of the eyeball deviates from the position of the fixation point. there is a possibility. Even if a saccade occurs at this time, it occurred when the eyeball was already moving and looking at the vicinity of the target, whether it was a saccade that was caused by finding the target when looking at a fixed fixation point It is difficult to determine whether it is a saccade, and it is difficult to accurately measure the visual field around the fixation point. On the other hand, as in the present embodiment, if the condition that “the eye target 6 has already been erased when the eye movement occurs after staring at the fixation point (that is, after the lapse of latency)” The eye movement can be determined to be due to a saccade based on the target finding. Since the target position when the saccade is generated means a range (that is, a visual field) that can be visually recognized around the gaze position immediately before the saccade is generated, this embodiment enables accurate visual field measurement. There is an advantage.

  Furthermore, in this embodiment, since the eyeball position is recorded at a high frequency of every 20 ms by the eye movement measuring unit 1, the position of the eyeball can be acquired with high accuracy, and the visual field is measured with high accuracy. There is also an advantage that it becomes possible.

  Moreover, in this embodiment, since the reinforcement | strengthening is shown, there exist the following advantages. The saccade is a characteristic that is generally provided in humans. However, there are cases where saccades are less likely to occur due to individual differences among subjects and conditions at that time. Therefore, the frequency of saccades can be increased by presenting a reinforcement when a saccade is generated. Thereby, the time required for visual field measurement can be shortened. In addition, many cases that cause saccades can be collected within a unit time, and the accuracy of visual field measurement can be improved.

(Second Embodiment)
Next, a perimeter according to a second embodiment of the present invention will be described with reference mainly to FIG. In the description of the second embodiment, the same reference numerals are used to simplify the description of the components common to the first embodiment described above.

  In the first embodiment, the fixation point 5 is presented before the target 6 is presented. The second embodiment is different from the first embodiment in that the fixation point 5 is not required. Hereinafter, the operation of the perimeter according to the second embodiment will be described in detail.

(Steps Sb-1 and Sb-2)
Also in the second embodiment, the eye movement measurement unit 1 constantly measures the eye movement of the subject, sends the measurement result to the control unit 2, and stores it in the storage unit 4.

  In the second embodiment, the region displayed on the display unit 31 of the output unit 3 is virtually divided into a plurality. In the example shown in FIG. 6A, the area is divided into 16 areas 7a to 7q.

  When the control unit 2 receives a measurement start command from the operator, the control unit 2 determines which region of the display unit 31 the target 6 is to be presented at random or according to a predetermined rule.

(Step Sb-3)
Next, the control unit 2 determines whether or not the region where the visual target 6 is presented is the same as the region where the subject is viewing (the region of the eyeball position). This determination can be made based on the eye movement of the subject measured by the eye movement measurement unit 1. In the example of FIG. 6A, an eyeball position (indicated by a symbol Δ) exists in the region 7f. However, the eyeball position [Delta] is not displayed on the display unit 31, but is shown for ease of explanation.

(Step Sb-4)
When the determination in step Sb-3 is Yes (that is, the target presentation area = the eyeball position area), after a predetermined waiting time (for example, 1 second) has elapsed, the operations after step Sb-1 are performed again.

(Step Sb-5)
If the determination in step Sb-3 is No (that is, the target presentation area ≠ the eyeball position area), the target is presented as in the case of the first embodiment. In the example of FIG. 6B, the visual target 6 is presented in the region 7p.

(Steps Sb-6 to Sb-9)
Subsequent operations are basically the same as steps Sa-5 to Sa-8 in the first embodiment, and thus detailed description thereof is omitted. FIG. 6C shows a state in which the image 61 as a reinforcer is presented in step Sb-8.

  According to the perimeter of the second embodiment, the viewpoint immediately before presentation of the target 6 is grasped, and the target 6 is presented in a region away from the target 6 (that is, other than the region of the target 6). For this reason, even if the subject does not stare at the fixation point 5, the visual field of the subject can be measured using the saccade based on the presentation of the visual target 6. The perimeter of the present embodiment has an advantage that the visual field can be measured even for a subject who is difficult to stare at the fixation point 5 (such as a relatively severely disabled person).

  Since other configurations and advantages in the second embodiment are the same as those in the first embodiment, detailed description thereof is omitted.

(Experimental example 1)
The visual field was evaluated by the perimeter of the first embodiment. The result is shown in FIG. Moreover, the result of the subjective visual field evaluation by the conventional key press is shown in FIG.

In each figure of FIG. 7, three contour lines are drawn. A line close to the origin is a range that can be seen even with a dark target, and indicates that the target cannot be seen unless the target becomes brighter away from the origin. In order from the target near the origin,
III-2b: 15.9cd / m ² (candela / square meter),
III-2c: 20.1cd / m ² (candela / square meter),
III-2d: 25.6cd / m ² (candela / square meter)
The brightness is Here, III indicates that the size of the target is 4 mm ² , and 2b, 2c, and 2d indicate the target luminance.

  From this result, it can be seen that the visual field can be measured by the perimeter of the first embodiment.

(Experimental example 2)
The visual field was evaluated by the perimeter of the second embodiment. The result is shown in FIG. Moreover, the result of the subjective visual field evaluation by the conventional key press is shown in FIG.

  The meanings of the three contour lines in each figure of FIG. 8 are the same as those in FIG.

  From this result, it is understood that the field of view can be measured even by a method that does not present the fixation point as in the second embodiment.

(Experimental example 3)
In the experimental examples 1 and 2, the occurrence of a saccade based on the presentation of a target is determined by determining whether or not the gaze (measured eyeball position) of the subject (subject) is substantially equal to the presentation position of the target. Yes. However, according to the results of data analysis by the inventors,
・ The direction in which the eyeball position moved after the target was presented, or
-It was found that the occurrence of a saccade based on the target presentation can be determined by any or a combination of increases in the movement amount of the eyeball position after the target is presented.

  The experimental procedure of Experimental Example 3 and the results obtained thereby are shown below.

(Experimental procedure of Experimental Example 3)
In Experimental Example 3, the fixation point was displayed at the center of the CRT monitor as the display unit 31. In addition, the visual target 6 can be displayed at a viewing angle of 5 degrees in the horizontal and vertical directions around the fixation point. Subsequently, the target was presented in a random order four times at each target display position.

  The subject was instructed to see the fixation point displayed on the CRT monitor and to press the button when the white circle (ie, the target) was visible on the screen after the fixation point disappeared.

  The eye-gaze position of the subject under observation (that is, the eyeball position) was always recorded by the eye movement measurement unit.

(Result of Experimental Example 3)
In the following, the methods of Experimental Examples 1 and 2 described above are referred to as “line-of-sight arrival”, and the method using the direction in which the eyeball position has moved after the target is presented is referred to as “direction matching” and the target is presented. Hereinafter, a method using an increase in the movement amount of the eyeball position is referred to as “line-of-sight movement” below. In this experimental example, these methods were specifically processed as follows.

(1) Line of sight arrival After the target was presented, the ratio (line of sight arrival rate) that the subject's line of sight moved to a range of plus or minus 2 degrees from the target presentation position was determined.

(2) Gaze movement Whether or not there is a difference between the change in the gaze position when the target is not presented (see FIG. 9) and the change in the gaze position after the presentation of the target (FIG. 10) is determined by t-test. Statistically examined, the ratio (gaze movement rate) when a significant difference was found in the amount of gaze movement was obtained. Thereby, the control part 2 can perform generation | occurrence | production determination of saccade based on the increase in the movement amount of the eyeball position measured by the eyeball movement measurement part 1.

(3) Direction matching Four directions (up / down / left / right directions centering on the fixation point) were set in advance corresponding to the target presentation position. Furthermore, it was recorded in which direction the movement of the line of sight occurred after the target was presented and how long the line of sight was directed in that direction. Among the four directions, the direction in which the line of sight was directed for the longest time during the measurement period of the eyeball position (for example, within 1 second) was defined as the line of sight movement direction. The ratio (direction coincidence rate) in which the direction of movement of the line of sight matched the direction of presentation of the target (direction from the fixation point to the target) was obtained. As a result, the control unit 2 can determine whether the saccade has occurred when the moving direction of the eyeball position measured by the eyeball movement measuring unit 1 is the direction toward the position of the visual target 6.

  As shown in FIG. 9, when the target was not presented, the line of sight hardly moved. Also, as shown in FIG. 10, when the target is presented, it can be seen that the movement of the line of sight in that direction increases. Therefore, it can be said that it is possible to determine the occurrence of a saccade by a visual target based on a visual line movement rate that is a comparison of movement amounts, or a direction matching rate that compares the direction of visual target presentation and the direction of visual line movement.

  Furthermore, in order to examine whether the judgment by each index reflects the fact that the saccade occurred due to the target, the button press at the time of target discovery (subject's subjective reaction) and the target discovery by each index The coincidence with the judgment (objective response) was confirmed by the correlation coefficient. The results are shown in Table 1. In Table 1, “line-of-sight movement rate + direction coincidence rate” indicates a correlation coefficient when two indexes are combined and both indexes are determined to be a target finding.

  According to the results in Table 1, although there are variations depending on the subjects A to F, a positive correlation is observed in many subjects between the subjective response and the objective response. Therefore, it is shown that the saccade determination using each index is effective. That is, it can be seen that the field of view can be measured using an index of line-of-sight movement and direction matching.

  In particular, subjects A and C had a high correlation between button presses and line-of-sight arrival rates (Table 1). That is, when the target can be detected, it can be said that a subjective reaction of pressing a button occurs and an objective response of moving the line of sight to the target. In other words, it can be said that, in the case of a subject in whom the line of sight moves properly, the index of line of sight movement and direction matching is effective for objective visual field measurement.

  Note that the perimeter according to the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the scope of the present invention.

  For example, each component described above may exist as a functional block, and may not exist as independent hardware. As a mounting method, hardware or computer software may be used. Furthermore, one functional element in the present invention may be realized by a set of a plurality of functional elements, and a plurality of functional elements in the present invention may be realized by one functional element.

  Moreover, the functional element may be arrange | positioned in the position physically separated. In this case, the functional elements may be connected by a network.

  Furthermore, in the above-described embodiment, the reinforcement is presented by the display unit 31 and the speaker 32. However, the reinforcement may be presented by only one of them, or by other output means (for example, a light emitting device). Also good.

It is a block diagram which shows schematic structure of the perimeter based on 1st Embodiment of this invention. It is a flowchart for demonstrating the visual field measuring method using the perimeter based on 1st Embodiment. It is explanatory drawing which shows the transition of the information shown by the display part of the perimeter based on 1st Embodiment, Comprising: A figure (a) is a fixation point, A figure (b) is a target, A figure (c) is a reinforcement. The presented state is shown. It is a graph explaining the eyeball movement which arises after showing a visual target, Comprising: The horizontal axis shows time (ms) and the vertical axis | shaft has shown the presentation position (degree). It is a flowchart for demonstrating the visual field measuring method using the perimeter based on 2nd Embodiment of this invention. It is explanatory drawing which shows transition of the information shown by the display part of the perimeter based on 2nd Embodiment, Comprising: A figure (a) is an eyeball position, A figure (b) is a target, A figure (c) is a reinforcement. The presented state is shown. FIG. 7A is a graph showing the result of subjective visual field evaluation by conventional key pressing. FIG. 7B is a graph showing the results of Experimental Example 1. In these drawings, the horizontal axis is the position (°) in the horizontal direction, and the vertical axis is the position (°) in the vertical direction. FIG. 8A is a graph showing the result of subjective visual field evaluation by the conventional key press. FIG. 8B is a graph showing the results of Experimental Example 2. In these drawings, the horizontal axis is the position (°) in the horizontal direction, and the vertical axis is the position (°) in the vertical direction. It is a three-dimensional graph which shows a gaze change when the target is not displayed. The dotted line in the figure indicates the target presentation position. It is a three-dimensional graph which shows a gaze change when a target is displayed, the solid line in a figure shows the position of a gaze, and the dotted line in a figure shows the presentation position of a target.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Eye movement measurement part 2 Control part 3 Output part 31 Display part 32 Speaker 4 Memory | storage part 5 Staring point 6 Target 61 Image as a reinforcement 7a-7q area

Claims (7)

An eye movement measurement unit, a control unit, and an output unit;
The eye movement measurement unit is configured to objectively measure eye movement,
The output unit is configured to present the optotype for a time equal to or less than the saccade latency in a range visible to the subject.
The control unit is configured to determine the occurrence of a saccade based on the presentation of the target based on the eye movement measured by the eye movement measurement unit after the target is presented in the output unit. Yes,
This is a perimeter.   The said control part performs determination of generation | occurrence | production of the said saccade, when the eyeball position measured by the said eye movement measurement part becomes substantially equal to the presentation position of the said target. Perimeter. The output unit is configured to present a gaze point before presenting the target and to present the target immediately after erasing the gaze point. 2. The perimeter according to 2. The perimeter according to claim 1 or 2, wherein the output unit presents the visual target in a region other than a region where the subject is viewing. The output unit is configured to present a reinforcer that can be perceived by a target person after the control unit determines that the eyeball position and the target position are substantially equal. Item 5. The perimeter according to any one of Items 1 to 4. The said control part performs generation | occurrence | production determination of the said saccade, when the movement direction of the eyeball position measured by the said eye movement measurement part is a direction to the presentation position of the said target, The said control part is characterized by the above-mentioned. The perimeter described in 1. 2. The perimeter according to claim 1, wherein the controller determines whether the saccade is generated by an increase in an amount of movement of an eyeball position measured by the eye movement measurement unit.

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