Visual field testing device, visual field testing method, and program

Abstract

To provide a visual field inspection apparatus capable of measuring retinal sensitivity without increase in burden on a subject.SOLUTION: The visual field inspection apparatus comprises: a light irradiation unit which irradiates a retina of a subject with stimulating light; a projection control unit which causes the light irradiation unit to perform irradiation with the stimulating light with an inspection pattern which raises the intensity of the stimulating light to a predetermined luminance with the lapse of time; a switch operated by the subject having viewed the stimulating light; and a calculation unit which calculates the intensity of the stimulating light visible by the subject based on timing when the switch is operated with the inspection pattern.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a visual field testing device, a visual field testing method, and a program. [Background technology]

[0002] Conventionally, there has been known a visual field testing device that presents a fixation point in a housing that covers the visual field of a subject, randomly displays bright points (targets) in the visual field of the subject while the subject is looking at the fixation point, and tests whether the subject can see them. Note that a technology for determining the intensity of a stimulating light to be used during the test based on a threshold value measured in advance from the subject's response is disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-117186 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional visual field testing devices, the intensity of the stimulating light applied to each part of the retina is fixed, so it is not possible to measure the retinal sensitivity of each subject. It is also possible to switch the intensity of the stimulating light and test whether the subject can see at each intensity. However, in this case, the test time will be longer and the burden on the subject will be greater.

[0005] Therefore, in one aspect, the present invention has an object to provide a visual field testing device capable of measuring retinal sensitivity without increasing the burden on the subject. [Means for solving the problem]

[0006] In one embodiment, A light irradiation unit that irradiates a stimulating light to a retina of a subject; a projection control unit that causes the light irradiation unit to irradiate the stimulus light in a test pattern that increases the intensity of the stimulus light over time to a predetermined luminance; a switch operated by the subject who visually recognizes the stimulus light; a calculation unit that calculates an intensity of the stimulus light that is visible to the subject based on a timing at which the switch is operated in the test pattern; A visual field testing device is provided, comprising: Effect of the Invention

[0007] According to one aspect of the present invention, the absolute value of retinal sensitivity can be measured without increasing the burden on the subject. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing the configuration of a visual field examination device according to the present embodiment. [Figure 1A] 1 is a diagram illustrating an example of the appearance of an inspection instrument to which the visual field inspection device of the present embodiment is applied. [Diagram 2] FIG. 2 is a diagram showing a configuration of a light irradiation unit. [Diagram 3] FIG. 1 shows the site on the retina where stimulating light (laser light) is presented. [Figure 4] 4 is a flowchart showing a visual field examination process in the visual field examination device of the present embodiment. [Diagram 5] 13 is a flowchart showing a reaction time measurement process for measuring a reaction time of a subject. [Figure 6] 13 is a flowchart showing a calculation process in a calculation unit. [Figure 7] 1A and 1B are diagrams showing examples of the arrangement of a test pattern of stimulus light and a pattern for measuring reaction time when performing a visual field test; [Figure 8] 6 is a diagram showing a count value of irradiation duration acquired in the reaction time measurement process of FIG. 5. FIG. [Figure 9] FIG. 1 is a diagram showing a method for calculating the retinal sensitivity of a predetermined site on a subject's retina. [Figure 10]FIG. 13 is a diagram showing an example in which the timing of shifting the test target to the next site on the retina is advanced in response to a switch operation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] FIG. 1 is a diagram showing the configuration of a visual field examination device according to this embodiment.

[0010] As shown in Figure 1, the visual field testing device of this embodiment includes a light irradiation unit 11 that irradiates stimulus light onto the retina of a subject, a projection control unit 12 that causes the light irradiation unit 11 to irradiate the stimulus light in a test pattern in which the intensity of the stimulus light is increased to a predetermined luminance over time, a switch 13 that is operated by the subject who views the stimulus light, and a calculation unit 14 that calculates the intensity of the stimulus light visible to the subject based on the timing at which the switch 13 is operated in the test pattern.

[0011] In addition, the visual field examination device of this embodiment is equipped with a memory unit 15 that stores data related to the examination and data such as the examination results calculated by the calculation unit 14, and an output unit 16 that outputs the examination results, etc. stored in the memory unit 15.

[0012] The visual field examination apparatus of this embodiment can be configured using a computer on which a predetermined program is implemented.

[0013] FIG. 1A is a diagram illustrating an example of the appearance of an examination instrument to which the visual field examination device of this embodiment is applied. In the example of FIG. 1A, the light irradiation unit 11 is housed inside the examination instrument. Note that, although FIG. 1A shows an examination instrument corresponding to both the left and right eyes, an examination instrument corresponding to testing each eye separately can also be used. The configuration of the examination instrument is arbitrary, and for example, an examination instrument in which the light irradiation unit 11 is built in a device shaped like goggles or glasses that can be worn by the subject can also be used.

[0014] 1A includes a frame 102, adjustment members 103 and 104, a base 105, support units 106a and 106b, image projection units 107a and 107b, a pedestal 108, and imaging units 109a and 109b. In addition, the pedestal 108 is provided on the base 105, and both ends of the frame 102 are fixed to the upper surface of the base 105.

[0015] The image projection units 107a and 107b are supported by the support units 106a and 106b. The image projection units 107a and 107b irradiate the left and right eyes of a subject to be tested for visual field, visual acuity, visibility, etc. with stimulating light by the light irradiation unit 11, and project a projection image including a test image onto the retina of the subject.

[0016] The adjustment member 103 moves the support portions 106a and 106b, on which the image projection portions 107a and 107b are supported, in the Y-axis direction shown in Fig. 1A. The adjustment member 104 moves the image projection portion 107 along the support portions 106 in the Z-axis direction shown in Fig. 1A.

[0017] The visual inspection device 100 is configured so that the subject's chin and forehead come into contact with the base 108 and frame 102, respectively, and the image projection unit 107 is brought close to the subject's eyes by the adjustment members 103 and 104 so that the subject is looking into the image projection units 107a and 107b, and the inspection is performed with this state in mind.

[0018] 2 is a diagram showing the configuration of the light irradiating unit 11. The light irradiating unit 11 irradiates stimulating light (laser light) onto a retina 22 of an eyeball 20 of a subject by utilizing Maxwellian vision.

[0019] 2, the light irradiation unit 11 has a light source 111, an adjustment unit 112, and an optical system 113. The optical system 113 has a scanning unit 114, a plane mirror 115, and lenses 116 and 117. The scanning unit 114 is, for example, a two-axis MEMS (Micro Electro Mechanical Systems) mirror.

[0020] In the light irradiation unit 11, the numerical aperture (NA) and / or beam diameter of the laser light L emitted by the light source 111 is adjusted in the adjustment unit 112. The laser light L is a visible laser light such as a red laser light, a green laser light, or a blue laser light.

[0021] The laser light L is reflected by a plane mirror 115 and scanned two-dimensionally by the scanning unit 114. The scanned laser light L is irradiated onto the subject's eyeball 20 via lenses 116 and 117. The laser light L converges near the crystalline lens 21, passes through the vitreous body 23, and is irradiated onto the retina 22. As a result, an image is projected onto the retina 22. The scanning unit 114 vibrates at a relatively high frequency, such as 28 kHz, at which 60 frames of images are projected per second.

[0022] The position of the eyeball 20 relative to the light irradiation unit 11 is adjusted, for example, by adjustment members 103 and 104 so that the laser light L is not eclipsed (blocked) at the position of the pupil of the eyeball 20. For example, by obtaining a positional relationship in which the laser light L diffused by scanning converges near the crystalline lens 21 of the eyeball 20 in the optical axis direction, it becomes possible to form an image over the entire field of view without missing the periphery of the image.

[0023] 3 is a diagram showing the sites on the retina to which stimulating light (laser light) is presented, in which each site is represented by a drawn dot 51.

[0024] As shown in FIG. 3, the stimulating light is presented to a total of 28 sites on the retina 22. The interval between adjacent sites in both the vertical and horizontal directions corresponds to an angle of 6 degrees of the stimulating light projected from a convergence point near the center of the crystalline lens 21 onto the retina 22. A background 52 of a predetermined luminance (gray color) is projected onto an area (rectangular area) including the area where the 28 sites are distributed. Any value can be selected as the luminance of the background 52, but in the following description, an example is shown in which the luminance of the background 52 is set to a brightness equivalent to, for example, a value of 100 out of a total of 256 gradations. In addition, a mark 53 indicating the site where the subject will fixate centrally is presented at the center of the area where the 28 sites are distributed. The subject fixates on the mark 53 and operates the switch 13 when he recognizes the stimulating light at the 28 sites, thereby performing a visual field test on the subject.

[0025] Next, the operation of the visual field examination device of this embodiment will be described.

[0026] FIG. 4 is a flow chart showing the visual field examination process in the visual field examination device of this embodiment.

[0027] In step S102 in FIG. 4, the projection control unit 12 selects one site from among candidates corresponding to sites on the retina 22 that have not yet been examined.

[0028] In step S104, the projection control unit 12 starts an operation of irradiating the selected site on the retina 22 with the stimulus light from the light irradiation unit 11 using a test pattern in which the intensity of the stimulus light is increased over time to a predetermined luminance. For example, in the test pattern, the amount of light at the site is continuously increased by continuously increasing 256 8-bit gradation values ​​from 100 to 256, which corresponds to the luminance of the background 52. The time required to increase the amount of light can be set, for example, in the range of 2 to 4 seconds.

[0029] In step S106, the projection control unit 12 starts counting the time that has elapsed since the operation was started in step S104.

[0030] In step S108, the projection control unit 12 acquires the count value of the elapsed time from which counting was started in step S106.

[0031] In step S110, the projection control unit 12 determines whether or not the intensity of the stimulus light has increased to the above-mentioned predetermined luminance based on the count value of the elapsed time acquired in step S108, and if the determination is affirmative, proceeds to step S114, and if the determination is negative, proceeds to step S112.

[0032] In step S112, the projection control unit 12 judges whether or not the switch 13 has been operated, and if the judgment is affirmative, the process proceeds to step S114, whereas if the judgment is negative, the process proceeds to step S110.

[0033] In step S114, the storage unit 15 stores the count value of the elapsed period acquired in step S108 in association with a site on the retina 22.

[0034] In step S118, the projection control unit 12 deletes the area on the retina 22 that is the current examination target from the candidates (areas that can be selected in step S102).

[0035] In step S120, the projection control unit 12 determines whether or not any candidate areas on the retina 22 (areas that can be selected in step S102) remain, and if the determination is positive, the processing proceeds to step S122, and if the determination is negative, the processing ends.

[0036] In step S122, the projection control unit 12 determines whether or not the irradiation of the stimulus light with the test pattern has ended based on the count value of the elapsed time acquired in step S108, and if the determination is positive, the process proceeds to step S102, and if the determination is negative, the process of step S122 is repeated.

[0037] 4, in this embodiment, the count values ​​of the elapsed time are obtained and stored for all 28 sites on the retina 22. If the count value of the elapsed time indicates an abnormality (error), the test (steps S104 to S114) may be performed again for that site on the retina 22 to obtain a valid count value of the elapsed time.

[0038] 4 is executed multiple times (e.g., three times) to improve the accuracy of the examination results. In this case, the average value of the count values ​​of the elapsed time acquired for each site on the retina 22 may be used as the final result (count value of the elapsed time) corresponding to that site.

[0039] In this embodiment, at a predetermined timing during the execution of the process shown in FIG. 4, stimulus light is emitted from the light emitting unit 11 in a reaction time measurement pattern, and the reaction time of the subject is measured.

[0040] 5 is a flow chart showing a reaction time measurement process for measuring a reaction time of a subject. The reaction time measurement process is executed at random timing, for example, during execution of the process shown in FIG.

[0041] In step S202 in FIG. 5, the projection control unit 12 causes the light irradiation unit 11 to irradiate a predetermined portion on the retina 22 with a reaction time measurement pattern in which the intensity of the stimulation light increases more steeply than the test pattern. The reaction time measurement pattern is, for example, a pattern in which the luminance of the stimulation light rises instantaneously from the luminance of the background 52 to a predetermined luminance (for example, a luminance of 256 as a gradation value) and continues for a predetermined duration. In addition, as the portion on the retina 22 to which the reaction time measurement pattern is applied, for example, a portion in the central region 51A shown in FIG. 3 (one of the four portions in the example of FIG. 3) is selected. This makes it possible to measure the reaction time of the subject more accurately.

[0042] In step S204, the projection control unit 12 starts counting the duration of irradiation of the stimulus light, the irradiation of which has started in step S202.

[0043] In step S206, the projection control unit 12 acquires a count value of the duration of the irradiation started in step S204.

[0044] In step S208, the projection control unit 12 determines whether the above-mentioned specified duration has elapsed based on the duration count value acquired in step S108, and if the determination is positive, the process proceeds to step S212, and if the determination is negative, the process proceeds to step S210.

[0045] In step S210, the calculation unit 14 determines whether or not the switch 13 has been operated, and if the determination is affirmative, the process proceeds to step S212, whereas if the determination is negative, the process proceeds to step S206.

[0046] In step S212, the storage unit 15 stores the count value of the duration of irradiation acquired in step S206, and ends the process.

[0047] In this embodiment, the reaction time measurement process shown in Fig. 5 is performed multiple times while the process shown in Fig. 4 is being performed, and multiple count values ​​of the irradiation duration are obtained. This allows the reaction time of the subject to be accurately grasped. The reaction time measurement process may be performed any number of times, but may be performed, for example, about 3 to 5 times. If the count value of the irradiation duration obtained in step S206 indicates an abnormality (error), the number of times the reaction time measurement process is performed may be increased to ensure the number of valid count values ​​of the irradiation duration.

[0048] FIG. 6 is a flowchart showing the calculation process in the calculation unit.

[0049] In step S302 in Fig. 6, the calculation unit 14 acquires the data of the corresponding subject stored in the process of Fig. 4 from the storage unit 15. The data of the subject includes a count value of the irradiation duration (step S212) and a count value of the elapsed period (step S114).

[0050] In step S304, the calculation unit 14 calculates the reaction time of the subject based on the count value of the irradiation duration acquired in step S302. The reaction time can be calculated, for example, as the average value of the count values ​​of a plurality of irradiation durations. In addition, if the count value of the irradiation duration includes a value that is considered to be an error (a value that is too small or too large), the count value may be excluded and the average value of the remaining count values ​​may be calculated as the reaction time.

[0051] In step S306, the calculation unit 14 calculates the retinal sensitivity (the intensity of the stimulus light visible to the subject) for each site on the retina 22 of the subject based on the count value of the elapsed period acquired in step S302, and ends the process.

[0052] FIG. 7 is a diagram showing an example of the arrangement of a test pattern of stimulus light and a reaction time measurement pattern when a visual field test is performed.

[0053] In the example of FIG. 7, basically, the irradiation of the stimulating light by the test pattern is repeated sequentially to different sites on the retina 22 in a certain cycle (for example, 2 to 4 seconds) (see step S122). However, within that cycle, the reaction time measurement process shown in FIG. 5 is inserted as an interrupt process (the interrupt process is not shown in FIG. 4). In FIG. 7, the irradiation of the stimulating light by the test pattern is started at times t0, t1, and t3, and the irradiation of the stimulating light by the reaction time measurement pattern is performed between times t2 and t3. In the test pattern, the intensity is continuously increased from a gradation value of 100, which corresponds to the luminance of the background 52 (FIG. 3), to a gradation value of 256. The intensity of the stimulating light by the reaction time measurement pattern corresponds to a gradation value of 256.

[0054] FIG. 8 is a diagram showing count values ​​of irradiation duration acquired in the reaction time measurement process of FIG.

[0055] 8, at time t11, the intensity of the stimulus light from the reaction time measurement pattern rises from a gradation value of 100 to 256, and at time t3, the intensity returns from a gradation value of 256 to 100. When the switch 13 is operated at time t12 (when the determination in step S210 is positive), the count value of the duration of irradiation is acquired (stored) as a count value Δt.

[0056] FIG. 9 is a diagram showing a method for calculating the retinal sensitivity at a predetermined site on the retina of a subject.

[0057] As described above, in the calculation process shown in FIG. 6, the reaction time of the subject is calculated based on the count value of the duration of irradiation.

[0058] In the example of FIG. 9, the reaction time of the subject corresponding to the count value of the irradiation duration is shown as reaction time ΔT.

[0059] 9, the intensity of the stimulus light by the test pattern gradually increases from a grayscale value of 100 at time t1, and reaches a grayscale value of 256 at time t2. Here, when the switch 13 is operated at time t21, the calculation unit 14 considers that the subject recognized the stimulus light at time t22, which is a reaction time ΔT before time t21. Therefore, the calculation unit 14 calculates the grayscale value X of the stimulus light corresponding to the time t22 as the retinal sensitivity of the corresponding site on the retina 22 (the intensity of the stimulus light visible to the subject).

[0060] In addition, there are cases where the switch 13 is operated after the intensity of the stimulus light by the test pattern reaches the gradation value 256, that is, after the point in time (time t2) when the irradiation of the stimulus light by the test pattern ends. In Fig. 9, when the switch 13 is operated at time t23, the calculation unit 14 considers that the subject recognized the stimulus light at time t24, which is the time point before time t23 by the reaction time ΔT. Therefore, in this case, the gradation value X0 of the stimulus light corresponding to the time t24 is calculated as the retinal sensitivity of the corresponding site on the retina 22 (the intensity of the stimulus light visible to the subject).

[0061] The retinal sensitivity of each site on the retina 22 calculated by the calculation unit 14 is stored in the storage unit 15, and the stored data is output by the output unit 16. For example, each site on the retina 22 can be shown as a two-dimensional chart as shown in Fig. 3, and the retinal sensitivity of each site in the chart, that is, the intensity (tone value) of the stimulus light visible to the subject, can be displayed in a display mode corresponding to the intensity (tone value) of the stimulus light visible to the subject. For example, each area in the chart may be displayed in a display color (for example, a display color with a different tone) according to the retinal sensitivity of the corresponding site.

[0062] FIG. 10 is a diagram showing an example in which the timing of shifting the test target to the next site on the retina is accelerated in response to the operation of a switch.

[0063] When the switch 13 corresponding to the selected area is operated, the projection control unit 12 may shift the test subject to the next area on the retina 22 before increasing the luminance of the stimulation light from the test pattern to the end.

[0064] In the example of FIG. 10, the stimulus light by the test pattern is initially set so that its gradation value gradually increases from 100 at time t0 and reaches a gradation value of 256 at time t1. However, if the subject operates the switch 13 at time t31, it is considered that the subject recognized the stimulus light at time t32, which is a time point that is a reaction time ΔT before time t31, and the gradation value X1 of the stimulus light corresponding to the time t32 is calculated as the retinal sensitivity (the intensity of the stimulus light that the subject can see) of the corresponding part on the retina 22. In this case, after the time t31 when the switch 13 is operated, there is no need to continue irradiating the stimulus light by the test pattern. For this reason, in the example of FIG. 10, the irradiation of the stimulus light by the test pattern is stopped at time t33, and the test subject is moved to the next part on the retina 22.

[0065] By adopting such an operation, if the examinee operates the switch 13 early, the test object can be quickly shifted to the next part on the retina 22. This makes it possible to shorten the test time and reduce the burden on the examinee.

[0066] As described above, the visual field testing device of this embodiment uses a test pattern that increases the intensity of the stimulus light to a predetermined luminance over time, and calculates the intensity of the stimulus light that is visible to the subject based on the timing at which the subject operates the switch. Therefore, the retinal sensitivity at each site on the retina 22 of each subject can be calculated without increasing the burden on the subject. Therefore, for example, it becomes easy to distinguish between diseases caused by opacity such as cataracts and diseases caused by visual field defects such as glaucoma.

[0067] Furthermore, even in the case of subjects with low sensitivity, it is possible to prevent cases in which the subject is unable to see anything from start to finish during the examination, thereby avoiding frustration and burden on the subject.

[0068] Although each embodiment has been described above in detail, the present invention is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the claims. In addition, it is also possible to combine all or a plurality of the components of the above-described embodiments. [Explanation of symbols]

[0069] 11 Light irradiation unit 12 Projection control unit 13. Switch 14 Calculation section 15 Storage section 16 Output section

Claims

1. A light irradiation unit that irradiates a stimulating light to a retina of a subject; a projection control unit that causes the light irradiation unit to irradiate the stimulus light in a test pattern that increases the intensity of the stimulus light over time to a predetermined luminance; a switch operated by the subject who visually recognizes the stimulus light; a calculation unit that calculates an intensity of the stimulus light that is visible to the subject based on a timing at which the switch is operated in the test pattern; A visual field examination device comprising:

2. the projection control unit causes the light irradiation unit to irradiate the stimulus light with a reaction time measurement pattern that increases the intensity of the stimulus light more steeply than the intensity of the test pattern; 2. The visual field testing device according to claim 1, wherein the calculation unit calculates the intensity of the stimulus light visible to the subject based on the timing at which the switch is operated in the reaction time measurement pattern and the timing at which the switch is operated in the test pattern.

3. 3. The visual field testing device according to claim 2, wherein the projection control unit randomly and sequentially selects one of a plurality of locations on the retina, and causes the light irradiation unit to irradiate the selected location with the stimulus light in the test pattern.

4. 4. The visual field inspection device according to claim 3, wherein the projection control unit inserts the reaction time measurement pattern at random timing during the inspection using the test pattern.

5. The visual field testing device of claim 3, wherein when the switch corresponding to the selected area is operated, the projection control unit shifts the test subject to a next area selected from among multiple areas on the retina before increasing the intensity of the stimulus light to the specified brightness.

6. a projection control step of irradiating the stimulus light with a test pattern that increases the intensity of the stimulus light to a predetermined luminance over time; a calculation step of calculating an intensity of the stimulus light visible to the subject based on a timing at which a switch operated by the subject who visually recognizes the stimulus light in the test pattern is operated by the subject; A visual field examination method comprising:

7. a projection control step of irradiating the stimulus light with a test pattern that increases the intensity of the stimulus light to a predetermined luminance over time; a calculation step of calculating an intensity of the stimulus light visible to the subject based on a timing at which a switch operated by the subject who visually recognizes the stimulus light in the test pattern is operated by the subject; A program that causes a computer to execute the following.

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