JP7585654B2 - Vision Testing Equipment - Google Patents

Description

This disclosure relates to a vision testing device for presenting a test target to a subject's eye to perform a vision test.

For example, there is known a visual acuity testing device that measures the visual function (e.g., visual acuity, etc.) of a subject's eye by having the subject check a test target presented in a target window (see, for example, Patent Document 1). In recent years, there has been a demand for early detection and treatment of abnormalities (diseases) of the subject's eye other than refractive errors during visual function tests.

JP 2000-287926 A

However, when a visual acuity test is performed using a visual acuity testing device such as that described above, if the visual acuity value result is poor (low visual acuity value), it is not possible to determine whether the cause of the poor visual acuity is refractive error, making it difficult to detect abnormalities in the subject's eye other than refractive error at an early stage.

In view of the above-mentioned conventional techniques, the technical objective of the present disclosure is to provide a visual acuity testing device that is capable of early detection of abnormalities in the subject's eye that are different from refractive errors.

To solve the above problems, the present disclosure is characterized by having the following configuration.

The visual acuity testing device according to the present disclosure is a visual acuity testing device for testing the visual acuity of a subject, and comprises an optotype presenting unit that emits an optotype light beam and presents a test optotype to the subject, a response means for inputting the subject's interpretation result for the presented test optotype, a visual acuity determination means that judges whether the interpretation result input by the response means is correct or incorrect and automatically obtains the visual acuity value of the subject, and a correction means that changes the optical characteristics of the optotype light beam , and obtains a first visual acuity value of the subject by the visual acuity determination means, and obtains a second visual acuity value at the time of refractive correction of the subject, the second visual acuity value being different from the first visual acuity value, and The device comprises a correction determination means for determining whether the examined eye is an eye that can be refractively corrected, and a standard setting means for setting a second standard visual acuity value based on the first visual acuity value for determining whether the examined eye is an eye that cannot be refractively corrected, wherein when the correction determination means determines that the first visual acuity value is a visual acuity value equal to or lower than the first standard visual acuity value, the acquisition means controls the correction means to correct the examinee, and automatically acquires the second visual acuity value by determining whether the interpretation result input by the response means is correct or not, and when the correction determination means determines that the second visual acuity value is a visual acuity value equal to or lower than the second standard visual acuity value, the acquisition means determines that the examined eye is an eye that cannot be refractively corrected .

FIG. 1 is an external configuration diagram of a visual acuity testing device. 1 is a schematic diagram showing an optical system and a control system of a visual acuity testing apparatus. 1 is a schematic diagram of an optical system of a visual acuity testing device as viewed from above. FIG. 13 is a diagram showing an example of an inspection flow when a correction determination mode is performed. 13A and 13B are diagrams illustrating an example of a change in the inspection flow when a correction determination mode is performed.

＜Overview＞
A typical embodiment will be described with reference to the drawings. Figures 1 to 5 are diagrams for explaining a vision testing device according to this embodiment. Note that the items classified in <> below can be used independently or in association with each other. In addition, L and R attached to the symbols below indicate left and right eyes, respectively.

For example, the vision testing device in this embodiment (e.g., vision testing device 1) is used to perform a vision test on the subject's eye (test eye).

For example, in this embodiment, the visual acuity testing device includes an optotype presenting unit (e.g., optotype presenting unit 20), a response means (e.g., response button 4, response lever 5), a visual acuity determining means (e.g., control unit 30), an acquisition means (e.g., control unit 30), and a correction determining means (e.g., control unit 30).

For example, the optotype presenting unit emits an optotype light beam and presents a test optotype to the subject. For example, the response means is used to input the subject's interpretation of the presented test optotype. For example, the visual acuity determining means automatically obtains the visual acuity value of the subject by determining whether the interpretation result input by the response means is correct. For example, the visual acuity determining means obtains the first visual acuity value of the subject. For example, the acquisition means obtains at least one of a second visual acuity value at the time of refractive correction of the subject, which is different from the first visual acuity value, and the subject's objective eye refractive power. For example, the correction determining means determines whether the subject's test eye is a test eye that can be refractively corrected based on the first visual acuity value and at least one of the objective eye refractive power and the second visual acuity value acquired by the acquisition means. With this configuration, for example, it is possible to grasp whether the cause of poor visual acuity is refractive error, and therefore it is possible to detect abnormalities (diseases) of the test eye other than refractive error at an early stage.

The visual acuity testing device is not limited to a configuration in which the visual acuity test is performed by looking into it. For example, the technology disclosed herein can be applied to any device that presents a test optotype to the subject's eye. As one example, the technology disclosed herein can also be applied to a device in which a correction means for correcting the optical characteristics of the subject's eye is integrally connected to a housing that houses an optotype presenting unit.

In this embodiment, the second visual acuity value different from the first visual acuity value refers to a visual acuity value obtained when the subject has a different state of refractive correction.
For example, the vision testing device may include an output means (for example, a control unit 30). For example, the output means may be configured to output judgment information based on the result of the judgment by the correction judgment means. In this case, for example, the output means may be configured to display the judgment information on a display. Also, in this case, for example, the output means may be configured to print the judgment information. Also, in this case, for example, the output means may be configured to transmit the judgment information to another device (another control means). At this time, for example, the other device may receive the judgment information and perform various controls based on the received judgment information.

For example, the judgment information may be a judgment result (a result indicating whether or not the subject's test eye is a test eye that can be refractively corrected). In addition, for example, the judgment information may be guide information based on the judgment result (for example, information indicating an abnormality (disease) of the test eye that is different from refractive error, etc.). Of course, the judgment information is not limited to the above configuration.

<Optotype presentation unit>
For example, the optotype presenting unit may be configured to use a display. For example, the display may be at least one of LCD (Liquid Crystal Display), LCOS (Liquid Crystal On Silicon), organic EL (Electro Luminescence), etc. For example, the display displays test optotypes such as a Landolt ring optotype.

For example, the visual target presenting unit may be a DMD (Digital Micromirror Device). DMDs generally have high reflectance and are bright. Therefore, even when polarized light is used, the light intensity of the visual target light beam can be maintained compared to an LCD display.

For example, the optotype presenting unit may have a configuration including a visible light source for presenting optotypes and an optotype plate. In this case, for example, the optotype plate is a rotatable disk plate having multiple optotypes. The multiple optotypes include, for example, optotypes for visual acuity testing used during subjective measurement. For example, the optotypes for visual acuity testing are prepared for each visual acuity value (visual acuity values 0.1, 0.3, ..., 1.5). For example, the optotype plate is rotated by a motor or the like, and the optotypes are switched and positioned on the optical path along which the optotype light beam is guided to the subject's eye. Of course, an optotype presenting unit other than the above configuration may be used as the optotype presenting unit that projects the optotype light beam.

For example, the optotype presenting section may have a pair of optotype presenting sections for the right eye (e.g., optotype presenting section 20R) and the left eye (e.g., optotype presenting section 20L) provided on the left and right sides. For example, the right eye optotype presenting section and the left eye optotype presenting section may be configured with the same member as the member constituting the optotype presenting section for the right eye. Also, for example, the right eye optotype presenting section and the left eye optotype presenting section may be configured with at least some members different from the member constituting the optotype presenting section for the right eye and the member constituting the optotype presenting section for the left eye. For example, the right eye optotype presenting section and the left eye optotype presenting section may be configured with at least some members shared between the member constituting the optotype presenting section for the right eye and the member constituting the optotype presenting section for the left eye. Also, for example, the optotype presenting section for the right eye and the optotype presenting section for the left eye may be configured such that a member constituting the optotype presenting section for the right eye and a member constituting the optotype presenting section for the left eye are provided separately.

<Response means>
For example, the response means may be at least one of a mouse, a joystick, a keyboard, a touch panel, etc. For example, the response means communicates with the visual acuity testing device (for example, visual acuity assessment means) using at least one of a wireless and a wired configuration. For example, the wireless configuration may be a wireless LAN, infrared communication, Wi-Fi (registered trademark), Bluetooth (registered trademark), etc. Also, for example, the wired configuration may be a USB cable, a LAN cable, etc.

<Method of acquisition>
For example, the acquisition means may be configured to acquire the second visual acuity value by receiving the second visual acuity value input to the visual acuity testing device by the examiner operating the operation means when acquiring the second visual acuity value. Also, for example, the acquisition means may be configured to acquire the second visual acuity value by receiving the second visual acuity value measured by a device different from the visual acuity testing device when acquiring the second visual acuity value. Also, for example, the acquisition means may be configured to acquire the second visual acuity value by measuring the second visual acuity value of the subject's eye using the measurement means when acquiring the second visual acuity value. Note that, when the visual acuity testing device is configured to have a measurement means for measuring the second visual acuity value, the visual acuity judgment means for acquiring the first visual acuity value may also be used as the acquisition means. In this case, for example, the visual acuity judgment means may automatically acquire the second visual acuity value by determining whether the interpretation result input by the response means is correct in a state in which the subject is corrected.

For example, the acquisition means may be configured to acquire the objective refractive power (e.g., spherical power, cylindrical power, cylindrical axis angle, etc.) by receiving the objective refractive power input to the visual acuity testing device by the examiner operating the operation means. Also, for example, the acquisition means may be configured to acquire the objective refractive power by receiving the objective refractive power measured by a device (e.g., an objective measuring device) different from the visual acuity testing device. Also, for example, the visual acuity testing device may have an objective measuring means for measuring the objective refractive power, and may acquire the objective refractive power by measuring the objective refractive power of the subject's eye by the objective measuring means.

<Correction Judgment Means>
For example, the correction determination means determines whether or not the subject's test eye is an eye that can be refractively corrected based on the first visual acuity value and at least one of the objective eye refractive power and the second visual acuity value acquired by the acquisition means.

For example, a case will be described in which it is determined whether or not the subject's test eye is a test eye that can be refractively corrected based on the second visual acuity value. In this case, for example, the acquisition means may acquire at least the second visual acuity value when the correction determination means determines that the first visual acuity value is equal to or lower than the first reference visual acuity value (visual acuity value is the same or worse). For example, the correction determination means may determine that the test eye is an eye that cannot be refractively corrected when it determines that the second visual acuity value is equal to or lower than the second reference visual acuity value (visual acuity value is the same or worse). In this way, for example, by using the second visual acuity value acquired when refractive correction is performed on the test eye, it is possible to easily determine whether or not the cause of poor visual acuity is refractive error simply by performing refractive correction on the test eye.

In the above configuration, a configuration is given as an example in which the test eye is determined to be an eye that cannot be refractively corrected based on a comparison process between the second visual acuity value and the second reference visual acuity value, but the present invention is not limited to this. For example, it is sufficient to be able to determine whether the test eye of the test subject is an eye that can be refractively corrected based on a comparison process between the second visual acuity value and the second reference visual acuity value. In this case, for example, the difference between the second visual acuity value and the second reference visual acuity value may be calculated, and a determination may be made based on whether the difference is greater than the reference value. Of course, the comparison process between the second visual acuity value and the second reference visual acuity value is not limited to the above configuration, and may be any process that can compare the difference between the second visual acuity value and the second reference visual acuity value.

For example, the first reference visual acuity value may be determined and set in advance by simulation, experiment, etc. In this case, for example, the first reference visual acuity value may be set as a standard for determining that the visual acuity value of the test eye is good (visual acuity value is normal). Of course, for example, the first reference visual acuity value may be configured to be arbitrarily set by the examiner. For example, the first reference visual acuity value may be stored in a memory (for example, memory 31). In this case, for example, the correction determination means may call up and set the first reference visual acuity value from the memory when performing the determination process.

For example, the second reference visual acuity value may be determined and set in advance by simulation, experiment, or the like. In this case, for example, the second reference visual acuity value may be set as a standard that can determine whether or not the visual acuity value of the test eye after refractive correction of the subject has become higher than the visual acuity value of the test eye before refractive correction (whether or not the effect of refractive correction is manifested in the visual acuity value). Of course, for example, the second reference visual acuity value may be configured to be arbitrarily set by the examiner. For example, the second reference visual acuity value may be stored in a memory (for example, memory 31). In this case, for example, the correction determination means may call up the second reference visual acuity value from the memory and set it when performing the determination process.

Also, for example, the second reference visual acuity value may be set based on the first visual acuity value. In this case, for example, a standard setting means (e.g., control unit 30) may be provided that sets the second reference visual acuity value to a visual acuity value equal to or greater than the first visual acuity value. With such a configuration, for example, it is desirable that the second reference visual acuity value is equal to or greater than the first visual acuity value. By comparing the second visual acuity value with the first visual acuity value obtained from the subject undergoing the test as a standard, it is possible to determine whether or not refractive correction can be performed based on the subject's individual visual acuity value, making it possible to detect abnormalities in the subject's eye at an early stage with greater accuracy.

For example, when determining whether the subject's test eye is a test eye that can be refractively corrected based on the second visual acuity value, a determination process based on the objective visual acuity may be performed. For example, the acquisition means may acquire the objective visual acuity when the correction determination means determines that the first visual acuity value is equal to or lower than the first reference visual acuity value, and may acquire the second visual acuity value when the correction determination means determines that the acquired objective visual acuity is lower than the reference visual acuity (is less favorable than the reference visual acuity). In this embodiment, the visual acuity close to that of an emmetropic eye includes the visual acuity of an emmetropic eye. For example, the correction determination means may determine that the test eye is an eye that cannot be refractively corrected when the second visual acuity value is equal to or lower than the second reference visual acuity value. With this configuration, for example, it is possible to more accurately determine whether or not the cause of poor vision is refractive error from both the objective results and the second visual acuity value, making it possible to detect abnormalities in the test eye other than refractive error at an early stage.

For example, the reference eye refractive power may be at least one of spherical information (e.g., spherical power) and astigmatism information (e.g., astigmatism power). As an example, when the reference eye refractive power is set as a spherical power, the acquisition means may acquire the second visual acuity value when the correction determination means determines that the spherical power, which is the objective eye refractive power of the subject, is a lower spherical power (a less favorable spherical power) than the reference spherical power, which is the reference eye refractive power.

For example, the reference eye refractive power may be determined and set in advance by simulation, experiment, etc. In this case, for example, the reference eye refractive power may be set as a standard that can determine whether the examined eye is an emmetropic eye or not, or whether it is close to being an emmetropic eye or not. Of course, for example, the reference eye refractive power may be configured to be set arbitrarily by the examiner. For example, the reference eye refractive power may be stored in a memory. In this case, for example, the correction determination means may call up the reference eye refractive power from the memory and set it when performing the determination process.

In the above description, the correction determination means determines whether or not the subject's test eye is an eye that can be refractively corrected based on the second visual acuity value, but is not limited to this. For example, it may be determined whether or not the subject's test eye is an eye that can be refractively corrected based on the objective eye refractive power.

In this case, for example, the acquisition means may acquire at least the objective eye refractive power when the correction determination means determines that the first visual acuity value is equal to or less than the first reference visual acuity value. Also, for example, the correction determination means may determine that the subject's eye is an eye that cannot be corrected for refractive error when the objective eye refractive power is equal to or more than the reference eye refractive power (an eye refractive power closer to an emmetropic eye than the reference eye refractive power). With this configuration, for example, the subject's eye can be determined from the objective result, so that the influence of the subject's response method, such as an examiner who is unfamiliar with the test, on the test result can be suppressed, and it can be more accurately understood whether the cause of poor visual acuity is refractive error.
In the above description, the configuration is exemplified to determine whether the subject's eye is an eye that cannot be corrected for refractive error based on the comparison process between the objective eye refractive power and the reference eye refractive power, but the present invention is not limited to this. For example, it is sufficient to determine whether the subject's eye is an eye that can be corrected for refractive error based on the comparison process between the objective eye refractive power and the reference eye refractive power. In this case, for example, the difference between the objective eye refractive power and the reference eye refractive power may be calculated, and the determination may be made based on whether the difference is greater than the reference value. Of course, the comparison process between the objective eye refractive power and the reference eye refractive power is not limited to the above configuration, and may be any process that can compare the difference between the objective eye refractive power and the reference eye refractive power.

In the above description, a configuration is given in which the acquisition means determines whether or not to acquire at least one of the second visual acuity value and the objective refractive power based on the judgment result of the first visual acuity value, but this is not limiting. For example, at least one of the second visual acuity value and the objective refractive power may be acquired after the first visual acuity value is acquired, without being based on the judgment result of the first visual acuity value.

In the above description, for example, the acquisition means is configured to acquire at least one of the second visual acuity value and the objective refractive power after acquiring the first visual acuity value, but this is not limited to the above. For example, the acquisition means may acquire at least one of the second visual acuity value and the objective refractive power at any timing. In this case, for example, the acquisition means may acquire at least one of the second visual acuity value and the objective refractive power before acquiring the first visual acuity value.

<Correction measures>
For example, in the case of acquiring the second visual acuity value, the visual acuity testing device may be provided with a correction means (e.g., the correction means 60) for correcting the refraction of the subject. In this case, for example, the visual acuity testing device may be provided with a correction means for changing the optical characteristics of the visual target light beam. For example, the acquisition means may be a visual acuity determination means, and in a state in which the subject is corrected by controlling the correction means, the acquisition means may automatically acquire the second visual acuity value by determining whether the interpretation result input by the response means is correct. With such a configuration, for example, a visual acuity test can be easily performed in a state in which the subject's test eye is corrected by the correction means. Therefore, it becomes possible to easily acquire the second visual acuity value by the same visual acuity testing device, and it becomes possible to smoothly and early discover abnormalities in the test eye other than refractive errors. Note that the acquisition means may be provided as a configuration different from the visual acuity determination means.
For example, the optical characteristic of the visual target light beam changed by the correction means may be ocular refractive power, which may be at least one of spherical information (e.g., spherical power (S)), astigmatism information (e.g., at least one of astigmatism power (C) and astigmatism axis angle (A)), etc.

For example, the correction means may be configured to change the optical characteristics of the visual target light beam (for example, at least one of the spherical power, cylindrical power (cylindrical power), and cylindrical axis angle). For example, the correction means may be configured to optically change the presentation position (presentation distance) of the visual target relative to the subject's eye, thereby correcting the spherical power of the subject's eye. In this case, for example, the configuration for optically changing the presentation position (presentation distance) of the visual target may be a configuration for moving the visual target presenting unit in the optical axis (for example, optical axes L1R and L1L). In addition, in this case, for example, a configuration for moving an optical element (for example, a spherical lens) arranged in the optical path in the optical axis direction may be used. In addition, in this case, for example, a configuration for inserting and removing an optical element (for example, optical element 61) in the optical path may be used. Of course, the correction means may be configured to combine at least two or more configurations, namely, a configuration for controlling an optical element, a configuration for moving an optical element arranged in the optical path in the optical axis direction, and a configuration for inserting and removing an optical element in the optical path.

For example, the correction means may be configured to switch and arrange optical elements in the optical path. For example, the eye examination unit may be configured to include a lens chamber unit that switches and arranges optical elements in the optical path. For example, the eye examination unit may have a lens disk on which multiple optical elements are arranged on the same circumference, and a driving means for rotating the lens disk, and may be configured to electrically switch optical elements by driving the driving means (e.g., a motor).

For example, the optical element for refractive correction may be at least one of a spherical lens, a cylindrical lens, a cross cylinder lens, a rotary prism, a wavefront modulation element, a variable focus lens, etc. Of course, for example, an optical element other than the optical elements described above may be used. For example, when an optical element is used, at least one or more optical elements may be used.

For example, in this embodiment, the corrective means has a pair of right and left eye corrective means. For example, the right eye corrective means and the left eye corrective means may be configured with the same members as the members constituting the right eye corrective means. Also, for example, the right eye corrective means and the left eye corrective means may be configured with at least some members different from the members constituting the right eye corrective means and the members constituting the left eye corrective means. For example, the right eye corrective means and the left eye corrective means may be configured with at least some members shared between the members constituting the right eye corrective means and the members constituting the left eye corrective means. Also, for example, the right eye corrective means and the left eye corrective means may be configured with the members constituting the right eye corrective means and the members constituting the left eye corrective means being provided separately.

<Objective Measurement Method>
For example, in the case of acquiring objective ocular refractive power, the visual acuity testing device may include an objective measuring means for measuring the objective ocular refractive power of the subject. For example, the objective measuring means may include a light projecting optical system and a light receiving optical system.

For example, the objective measuring means may be configured to irradiate the fundus with spot-shaped measurement light, extract the reflected light in a ring shape, and detect the ring-shaped fundus reflected light. In this case, for example, the light projecting optical system in the objective measuring means may have a measurement light source, emit measurement light, and irradiate the spot-shaped measurement light onto the fundus of the subject eye through the center of the pupil of the subject eye. Also, for example, the light receiving optical system in the objective measuring means may extract the fundus reflected light reflected from the fundus in a ring shape via the peripheral part of the pupil, and detect the ring-shaped fundus reflected light by a detector.

The objective measuring means may be configured to project a ring-shaped measurement light from the peripheral part of the pupil onto the fundus, extract fundus reflected light from the central part of the pupil, and have a detector detect the ring-shaped fundus reflected image. In this case, for example, the light projecting optical system in the objective measuring means may emit measurement light and irradiate the ring-shaped measurement light onto the fundus of the subject's eye via the peripheral part of the pupil of the subject's eye. Also, for example, the light receiving optical system in the objective measuring means may extract the fundus reflected light reflected from the fundus in a ring shape via the central part of the pupil, and have a detector detect the ring-shaped fundus reflected light.

Also, for example, the objective measuring means may be configured to perform measurements using a photorefraction method. In this case, for example, the objective measuring means may be configured to include a light projecting optical system that irradiates measurement light toward the fundus of the test eye, and a light receiving optical system that detects the reflection distribution of the pupil part from the fundus reflected light reflected by the fundus of the test eye through the pupil part.

Note that, for example, the objective measurement means is not limited to the above configuration. For example, the measurement optical system may be configured to include a light projecting optical system that irradiates the test eye with measurement light and a light receiving optical system that detects the reflected light, and may be configured to objectively measure optical characteristics. For example, the objective measurement means may be configured to include a Shack-Hartmann sensor. Also, for example, the objective measurement means may be configured to include a phase difference method that projects a slit onto the test eye.

In this embodiment, at least one of the visual acuity assessment means, acquisition means, correction assessment means, standard setting means, and output means may be combined. Also, for example, the visual acuity assessment means, acquisition means, correction assessment means, standard setting means, and output means may each be provided separately. Of course, each of the above control means may be composed of multiple control means.

<Example>
The visual acuity testing device of this embodiment will be described below. For example, Fig. 1 is an external view of a visual acuity testing device 1 according to this embodiment. In addition, R and L attached to the reference characters hereinafter indicate the right eye and the left eye, respectively.

For example, the visual acuity testing device 1 includes a housing 9. For example, a presentation window 2 is provided on the upper front side of the housing 9. The presentation window 2 presents a test optotype from inside the housing 9 to the outside. For example, the presentation window 2 in this embodiment has a presentation window 2L for the left eye and a presentation window 2R for the right eye. For example, the subject can look into the presentation windows 2 (presentation window 2L for the left eye and presentation window 2R for the right eye) to confirm the test optotype and perform a visual acuity test on the subject's eye.

For example, a speaker 6 is provided in the center of the front of the housing 9. The speakers 6 are a pair, one on the left and one on the right, and output audio guides and the like. Of course, the speakers 6 may be configured to use one speaker each on the left and right. For example, an input button 3, a response button 4, and a response lever (joystick) 5 are provided in the lower front of the housing 9. The input button 3 is used when the subject inputs a signal to start the visual acuity test. The response button 4 is used when the subject cannot read the presented test optotype. The response lever 5 is used when the subject reads the presented test optotype and responds with its direction. For example, the response lever 5 in this embodiment can be tilted in four directions, front, back, left, and right, corresponding to the four directions, up, down, left, and right, of the presented test optotype, and signals in four directions can be input.

For example, a printer 7 is provided on the side of the housing 9. The printer 7 is used to output the test results. For example, a lamp 8 is provided on the top of the housing 9. The lamp 8 notifies the examiner of the test status, test results, etc. The lamp 8 is placed in a position where it cannot be seen when the examinee looks into the presentation window 2. The lamp 8 is equipped with multiple LEDs (light-emitting diodes) and is capable of emitting light in multiple colors (for example, two colors, green and orange). Of course, the lamp 8 may be composed of a single LED and be configured to emit light in a single color.

Also, for example, a control box 40 is connected to the side of the housing 9 via a cable 42. The control box 40 includes a touch panel monitor 41 that serves as both an operation unit for inputting parameters, etc. of the visual acuity testing device 1 and a display unit for confirming the input parameters, etc. Note that the control box 40 is not limited to being provided outside the housing 9, and may be provided integrally with the housing 9.

<Optical system>
For example, Fig. 2 is a schematic diagram of the optical system of the vision testing device 1 as viewed from the right side, and also shows the configuration of the control system. Also, for example, Fig. 3 is a schematic diagram of the optical system of the vision testing device 1 as viewed from above. Note that in this embodiment, the optical system in the side view will be described by taking the optical system for the right eye as viewed from the right side as an example. In this embodiment, the optical system for the right eye as viewed from the right side has the same configuration as the optical system for the left eye as viewed from the left side, so the description of the optical system for the left eye in the side view will be omitted.

For example, lenses 10R and 10L are placed in the left and right presentation windows 2R and 2L, respectively, and the test targets that are switched and placed in the rear target window 12 (right target window 12R, left target window 12L) are placed at an apparent test distance of 5 m from the test eyes (left test eye EL, right test eye ER). For example, the left and right optical paths are divided by cylindrical internal covers 11R and 11L with a partition plate in the center, and separate visual fields are secured for the left and right eyes to see the targets. Both of these internal covers 11R and 11L have the same shape, and the left and right inner wall surfaces are formed symmetrically around the central axis of each of the presentation windows 2R and 2L (the optical axis of each of the lenses 10R and 10L), and the rear target windows 12R and 12L are also provided in the same position. Therefore, when the inside is observed through the presentation windows 2R and 2L with both the left and right eyes, the two target windows 12R and 12L are fused and seen as one, just as when the inside is observed with the left and right eyes alone, and the inner covers 11R and 11L are also observed as one space with the left and right walls in the same state. Therefore, the subject can see the test target placed at an optically distant distance (5 m) without feeling uncomfortable. In this embodiment, the optical axes L1R and L1L in the optical path along which the target light beam from the target presentation unit 20 is guided to the subject are coaxial with the central axes of the test windows 2R and 2L. In this embodiment, the coaxial includes approximately coaxial.

The inner surfaces of the inner covers 11R and 11L are painted matte white, and the illumination lamps 12R and 12L are turned on to a predetermined brightness during normal visual acuity tests and during light adaptation for measuring visual acuity recovery time. The illumination lamps 17R and 17L are placed in a position where the illumination light does not directly enter the subject's eye.

For example, the optotype presenting unit 20 is used to switch and place test optotypes in the optotype window 12. For example, the optotype presenting unit 20 includes an optotype plate 21, a motor 22, and optotype illumination lamps 24L and 24R. The optotype plate 21 is made of a translucent glass plate. On this glass plate, a test optotype with a directional property (for example, a Landolt ring optotype with a directional property in the up, down, left and right directions) is formed by a chrome coating with a light blocking property. For example, such a test optotype may be formed in 12 stages of visual acuity values of 0.1 to 1.0, 1.2, and 1.5. Also, for example, such a test optotype may be formed corresponding to the positions of the optotype windows 12L and 12R so that the same test optotype for the left eye and the test optotype for the right eye can be simultaneously presented to the left eye EL (hereinafter referred to as the test eye EL) and the right eye ER (hereinafter referred to as the test eye ER).

For example, the motor 22 rotates the optotype plate 21. As a result, the test optotypes for the left eye and the right eye are placed in the optotype windows 12L and 12R, respectively. The optotype illumination lamps 24L and 24R illuminate the optotype plate 21 from behind. As a result, the test optotypes placed in the optotype windows 12L and 12R are presented toward the presentation windows 2L and 2R.

For example, the vision testing device 1 includes a correction means 60. For example, the correction means 60 includes an optical member 61 and a motor 62. For example, the optical member 61 is used to perform refractive correction of the test eye. For example, the motor 62 inserts and removes the optical member 61 into and from the optical path along which the visual target light beam from the visual target presenting unit 20 is guided to the test subject. For example, the control unit 30 drives the motor 62, and the optical member 61 is inserted into the optical path along which the visual target light beam from the visual target presenting unit 20 is guided to the test subject, thereby performing refractive correction of the test eye. For example, the optical member 61 may be, for example, a lens, a prism, or the like. Of course, the optical member 61 is not limited to the above optical members as long as it is an optical member capable of performing refractive correction of the test eye. Of course, optical members having different amounts of correction may be used.

<Control system>
For example, the control unit 30 (see FIG. 2) supervises and controls each part of the vision testing device 1. For example, the control unit 70 may be configured to include a CPU (processor), RAM, ROM, etc. For example, the CPU controls the driving of each component in the vision testing device 1. For example, the RAM temporarily stores various information. For example, the ROM stores programs executed by the CPU, etc. Note that the control unit 30 may be configured by multiple control units (i.e., multiple processors).

For example, the control unit 30 is electrically connected to the input button 3, the response button 4, the response lever 5, the speaker 6, the printer 7, the lamp 8, the internal illumination lamps 17L and 17R, the motor 22, the target illumination lamps 24L and 24R, the storage unit (memory) 31, the control box 40, the motor 62, and the like. For example, the memory 31 may be a non-transient storage medium that can retain the stored contents even if the power supply is cut off. For example, the memory 31 may be a hard disk drive, a flash ROM, or a USB memory that is detachably attached to the visual acuity testing device 1. For example, the memory 31 may store a test program (for example, an automatic test program used in the automatic test mode described later, a manual test program used in the manual test mode described later, a test program used when performing a visual acuity test, a correction judgment program that judges whether or not the subject's eye is a subject's eye that can be corrected for refractive error, etc.).

<Control operation>
The control operation of the visual acuity testing device 1 having the above configuration will be described using an example of testing distance visual acuity. Also, for example, a case where distance binocular vision function is tested after testing distance visual acuity will be described. Note that in the visual acuity testing device 1 of this embodiment, the distance visual acuity test proceeds successively in the order of the right eye, the left eye, and both eyes. Also, the visual acuity testing device 1 of this embodiment has an automatic testing mode in which the control unit 30 automatically selects a test optotype to be presented to the subject's eye E, and a manual testing mode in which the examiner manually selects a test optotype to be presented to the subject's eye E.

For example, when the examiner turns on the power (not shown) of the visual acuity testing device 1, the device is set to an automatic testing mode. Of course, the test mode may be selected by operating the monitor 41. The examiner also operates the monitor 41 to select at least one of a normal test mode for testing distance visual acuity and a correction judgment mode for testing distance visual acuity and judging whether the subject's eye is capable of refractive correction. Note that, although the present embodiment will be described taking the case of testing distance visual acuity as an example, the present technology can also be applied to the case of testing near visual acuity.

In this embodiment, for example, the case where the examiner operates the monitor 41 and selects the correction judgment mode will be described as an example. FIG. 4 is a diagram showing an example of the examination flow when the correction judgment mode is performed. For example, when a distance visual acuity test is performed on the right eye to be examined, a similar distance visual acuity test is performed on the left eye to be examined. This allows the examination results to be obtained for the right and left eyes of the examinee. That is, the correction judgment mode is performed on the other eye as well as on the other eye to be examined. In this embodiment, when the examination of one eye to be examined is completed, the examination of the other eye to be examined is performed, and when the examination of both eyes to be examined is completed, the examination results are output. In the following description, an examination of only one eye to be examined (right eye to be examined or left eye to be examined) will be described as an example.

For example, when the examiner operates the monitor 41 and selects to execute the correction assessment mode, the control unit 30 sets the correction assessment program for executing the correction assessment mode to be executed.

For example, the examiner has the subject look into the presentation window 2 and press the input button 3. The examiner may instruct the subject to press the input button 3. The control unit 30 starts the visual acuity test in response to a signal from the input button 3. At this time, the speaker 6 issues an initial voice prompt, for example, saying, "Your visual acuity will be measured automatically. Please lightly push the lever." When the subject pushes the response lever 5 in any direction in accordance with the voice prompt, the control unit 30 receives the signal and puts the visual acuity testing device 1 into an operational state.

First, the first visual acuity value of the subject's eye is obtained (S1). For example, the control unit 30 turns on the optotype presenting unit 20. For example, the control unit 30 turns on the internal illumination lamp 17 (internal illumination lamps 17L and 17R) and the optotype illumination lamp 24 (optotype illumination lamps 24L and 24R). Also, for example, the control unit 30 rotates the optotype plate 21 by driving the motor 22, and places the initial test optotype (for example, a test optotype with a visual acuity value of 0.5) in the optotype window 12 (optotype windows 12L and 12R). The speaker 6 generates a voice guide saying, "Gently hold the lever with your right hand, place your left hand on the button in front, and look into the window." Next, a voice guide is generated saying, "We will measure your visual acuity. Gently push the lever in the direction where the ring is broken (if the test optotype is a Landolt ring). If you do not know the direction where the ring is broken, press the button in front." When the subject responds using the response lever 5 or response button 4, a correction assessment program is executed to determine the visual acuity of the subject's eye and whether or not the subject's eye is one that can be corrected for refractive error.

For example, in the test program, the control unit 30 controls the speaker 6 to generate a voice guide saying "direction." The subject reads the direction of the test optotype presented in the optotype window 12 and tilts the response lever 5 in that direction. The control unit 30 determines whether the direction of the test optotype matches the direction of the response lever 5 tilted by the subject. For example, if the subject's response is correct (i.e., if the direction of the test optotype matches the direction of the response lever 5), the control unit 30 rotates the optotype plate 21 to present a test optotype with a one-level higher visual acuity value. Also, for example, if the subject's response is incorrect (i.e., if the direction of the test optotype matches the direction of the response lever 5), the control unit 30 rotates the optotype plate 21 to present a test optotype with a one-level lower visual acuity value.

For example, the visual acuity value and direction of the test optotype presented to the subject's eye E are stored sequentially in the memory 31. For example, when a test optotype with a visual acuity value one level higher is presented, if the subject's response is incorrect or illegible (when the response button 4 is operated), the control unit 30 returns the visual acuity value of the test optotype to the stage at which the subject's eye could see, changes the direction of the test optotype, and continues the visual acuity test. For example, the control unit 30 sequentially changes the test optotype presented in the optotype window 12 in this way, and determines whether the subject's response is correct. For example, if there are two or more correct responses to test optotypes with the same visual acuity value, the control unit 30 determines that the subject's eye has that visual acuity value, and sets it as the first visual acuity value.

Here, for example, the control unit 30 judges whether the acquired first visual acuity value is equal to or lower than a first reference visual acuity value (a judgment standard for judging whether the first visual acuity value is good or bad) (S2). In this embodiment, the first reference visual acuity value is set to a visual acuity value of 0.7. Of course, the first reference visual acuity value can be set to any visual acuity value.

In this embodiment, for example, the control unit 30 judges whether the first visual acuity value is equal to or lower than the first standard visual acuity value of 0.7. For example, when the first visual acuity value is higher than the first standard visual acuity value (high visual acuity value), the control unit 30 ends the test with the first visual acuity value as the visual acuity value of the subject eye, and outputs the first visual acuity value as the test result (S3). For example, when the distance visual acuity test is ended, the control unit 30 controls the speaker 6 to emit a voice guide saying "Finished. The test results will be printed from the right side of the device." At this time, the test results are output from the printer 7. At this time, the test results are displayed on the monitor 41 and stored in the memory 31.
Also, for example, if the first visual acuity value is equal to or lower than the first standard visual acuity value (the visual acuity value is the same as or lower than the first standard visual acuity value), the control unit 30 performs refractive correction of the test eye and obtains a second visual acuity value (S11).

In the following description, the case where the subject is myopic will be described. Of course, the present technology can also be applied to cases where the subject is hyperopic. For example, when the test of the first visual acuity value is completed, the control unit 30 turns off the optotype presenting unit 20. Next, for example, the control unit 30 drives the motor 62 to insert the optical element 61 into the optical path along which the optotype light beam from the optotype presenting unit 20 is guided to the subject. This corrects the refraction of the subject's eye. In this embodiment, for example, a -1.0D concave lens is used as the optical element 61. Note that, although the embodiment uses a configuration using a -1.0D concave lens as an example, an optical element having any refractive power can be used. Note that, for example, for hyperopic eyes, a convex lens having any refractive power is used.

For example, when the optical member 61 is inserted into the optical path, the optotype presenting unit 20 is turned on. After that, the second visual acuity value is acquired by the same method as when the first visual acuity value was acquired. Next, for example, the control unit 30 judges whether the acquired second visual acuity value is equal to or lower than a second reference visual acuity value (a judgment criterion for judging whether the second visual acuity value is good or bad) (S12). For example, in this embodiment, the control unit 30 sets the visual acuity value of the acquired first visual acuity value as the second reference visual acuity value. As an example, when the first visual acuity value is 0.5, the control unit 30 sets a visual acuity value of 0.5 as the second reference visual acuity value. Of course, the second reference visual acuity value can be set to any visual acuity value.

For example, the control unit 30 determines whether the second visual acuity value is equal to or lower than the second standard visual acuity value of 0.5 (whether it is the same as or lower). For example, if the second visual acuity value is higher than the second standard visual acuity value (high visual acuity value), the control unit 30 determines that the subject's eye is capable of refractive correction (S13). For example, if it is determined that the subject's eye is capable of refractive correction, the control unit 30 ends the test with the first visual acuity value as the visual acuity value of the subject's eye and outputs the first visual acuity value as the test result. Of course, it is also possible to output a statement that refractive correction is possible together with the first visual acuity value as the test result. Also, for example, if the second visual acuity value is equal to or lower than the second standard visual acuity value (the same as or lower visual acuity value), the control unit 30 determines that the subject's eye is not capable of refractive correction (S14). For example, the control unit 30 outputs a statement that there is a suspicion of disease together with the first visual acuity value as the test result.

For example, when the distance visual acuity test is to be completed, the control unit 30 controls the speaker 6 to emit a voice guide stating, "Completed. The test results will be printed from the right side of the device." At this time, the test results are output from the printer 7. At this time, the test results are also displayed on the monitor 41 and stored in the memory 31. In this embodiment, when the test results of the distance visual acuity test are obtained for each of the subject's right and left eyes, the test results are output from the printer 7. At this time, the test results are also displayed on the monitor 41 and stored in the memory 31.

As described above, for example, the visual acuity testing device in this embodiment is a visual acuity testing device that performs a visual acuity test on a subject, and includes a visual acuity presenting unit that emits a visual acuity beam and presents a test visual acuity to the subject, a response means for inputting the subject's interpretation result for the presented test visual acuity, and a visual acuity judging means that judges whether the interpretation result input by the response means is correct or not and automatically acquires the visual acuity value of the subject. Also, for example, the visual acuity testing device in this embodiment acquires the first visual acuity value of the subject by the visual acuity judging means. Also, for example, the visual acuity testing device in this embodiment includes an acquisition means that acquires a second visual acuity value at the time of refractive correction of the subject, which is different from the first visual acuity value, and a correction judging means that judges whether the subject's test eye is a test eye that can be refractively corrected based on the first visual acuity value and the second visual acuity value acquired by the acquisition means. With such a configuration, for example, it is possible to grasp whether the cause of poor visual acuity is refractive error, and therefore it is possible to detect abnormalities in the test eye other than refractive error at an early stage.

For example, the acquisition means may acquire at least the second visual acuity value when the correction determination means determines that the first visual acuity value is equal to or lower than the first reference visual acuity value, and the correction determination means may determine that the test eye is an eye that cannot be refractively corrected when the correction determination means determines that the second visual acuity value is equal to or lower than the second reference visual acuity value. With this configuration, for example, by using the second visual acuity value acquired when refractive correction is performed on the test eye, it is possible to easily determine whether or not the cause of poor visual acuity is refractive error simply by performing refractive correction on the test eye.

For example, the visual acuity testing device may be equipped with a correction means for changing the optical characteristics of the visual target light beam, and the acquisition means may be a visual acuity determination means that, in a state in which the subject has been corrected by controlling the correction means, determines whether the interpretation result input by the response means is correct and automatically acquires the second visual acuity value. With such a configuration, for example, visual acuity testing can be easily performed in a state in which the subject's test eye has been corrected by the correction means. This makes it possible to easily acquire the second visual acuity value using the same visual acuity testing device, and makes it possible to smoothly and early detect abnormalities (diseases) in the test eye other than refractive errors.

For example, the visual acuity testing device may also be provided with a standard setting means for setting the second reference visual acuity value to a visual acuity value equal to or greater than the first visual acuity value. With such a configuration, for example, it is desirable that the second reference visual acuity value is equal to or greater than the first visual acuity value. By comparing the second visual acuity value with the first visual acuity value obtained from the subject undergoing the test as a standard, it is possible to determine whether or not refractive correction can be performed based on the subject's individual visual acuity value as a standard, making it possible to detect abnormalities (diseases) in the subject's eye at an early stage with greater accuracy.

<Example of transformation>
In this embodiment, the subject's eye is myopic, and the refractive correction is performed by a concave lens. However, the present invention is not limited to this. For example, when the condition of the subject's eye (for example, myopia or hyperopia) is not specified, a configuration having a concave lens and a convex lens may be used as the optical member 61. In this case, for example, the control unit 30 may insert the concave lens and the convex lens in order in S11 in FIG. 4 to obtain the second visual acuity value. For example, the control unit 30 may obtain the second visual acuity value obtained when the concave lens is inserted and the second visual acuity value obtained when the convex lens is inserted, and may determine that the subject's eye is not capable of refractive correction when both second visual acuity values are equal to or less than the second reference visual acuity value in S12. On the other hand, for example, the control unit 30 may determine that the test eye is one that can be corrected for refractive error if one of the second visual acuity values obtained when a concave lens is inserted and the second visual acuity value obtained when a convex lens is inserted exceeds the second standard visual acuity value.

Of course, it is not necessary to configure the device to obtain the second visual acuity value with both a concave lens and a convex lens. For example, the second visual acuity value may be obtained with one lens inserted, and only if the obtained second visual acuity value is equal to or less than the second reference visual acuity value, the other lens may be inserted, the second visual acuity value may be obtained, and it may be determined again whether the obtained second visual acuity value is equal to or less than the second reference visual acuity value. In this case, for example, the second visual acuity value may be obtained with one lens inserted, and if the obtained second visual acuity value exceeds the second reference visual acuity value, it may be determined that the subject's eye is capable of refractive correction without obtaining the second visual acuity value by inserting the other lens.

Note that, although the configuration in which refractive correction is performed by inserting a concave lens has been described as an example, the present invention is not limited to this. For example, a configuration in which refractive correction is performed with multiple correction amounts may be used. In this case, for example, the correction amount may be changed continuously. As an example, when acquiring the second visual acuity value, the second visual acuity value may be acquired while performing refractive correction of the test eye with multiple correction amounts, and a correction amount that can obtain a second visual acuity value that exceeds the second reference visual acuity value may be found. In this case, for example, if there is a correction amount that can obtain a second visual acuity value that exceeds the second reference visual acuity value, it may be determined that the test eye is capable of refractive correction. Note that examples of a configuration for changing the correction amount include a configuration in which a variable focus lens is used to change the correction amount, a configuration in which the optotype presenting unit is moved in the optical axis direction, and a configuration in which multiple lenses are inserted and removed to change the correction amount.

In this embodiment, the configuration is not limited to the example in which it is determined whether or not the test eye is an eye that can be refractively corrected based on the first visual acuity value and the second visual acuity value. For example, it may be a configuration in which it is determined whether or not the test eye is an eye that can be refractively corrected based on the first visual acuity value, the second visual acuity value, and the objective eye refractive power.

Figure 5 is a diagram showing an example of a change in the test flow when the correction judgment mode is implemented. For example, the control unit 30 implements S1 and S2 in the same manner as the test flow of Figure 4 in the above embodiment. For example, the control unit 30 determines whether the first visual acuity value is equal to or lower than the first reference visual acuity value. For example, if the first visual acuity value is higher than the first reference visual acuity value (high visual acuity value), the control unit 30 ends the test with the first visual acuity value as the visual acuity value of the test eye and outputs the first visual acuity value as the test result (S3).

On the other hand, for example, when the first visual acuity value is equal to or lower than the first reference visual acuity value (the same or lower visual acuity value), the control unit 30 acquires the objective refractive power of the subject's eye (S21). In this embodiment, an example will be described in which spherical power is used as the objective refractive power. The spherical power may be an equivalent spherical power. In this embodiment, the objective refractive power is acquired by inputting the objective refractive power of the subject's eye previously measured by another eye examination device equipped with an objective measuring means. For example, when the first visual acuity value is equal to or lower than the first reference visual acuity value, the control unit 30 displays a screen for inputting the spherical power, which is one of the objective refractive powers, on the monitor 41. In addition, the control unit 30 generates a voice guide from the speaker 6 saying, "Please input the objective refractive power." For example, the subject operates the monitor 41 to input the spherical power measured in advance. In this manner, the spherical power is acquired.

For example, the control unit 30 determines whether the objective eye refractive power is equal to or greater than the reference eye refractive power (S22). In this embodiment, since spherical power is used as the eye refractive power, it is determined whether the spherical power is equal to or greater than the reference spherical power. For example, an example of the reference spherical power will be described as ±0.50D. Of course, the reference spherical power (reference eye refractive power) can be set to any refractive power.

For example, if the spherical power is equal to or greater than the reference spherical power (±0.50D) (for example, 0D, ±0.25D, ±0.50D, etc.), the control unit 30 determines that the subject's eye is one for which refractive correction is not possible (S14). For example, such a determination is made because, even if the first visual acuity value has been determined to be low, it has been determined that no refractive error is present based on the objective eye refractive power (the eye is determined to be emmetropic), and it is possible to grasp that the cause of poor visual acuity is not refractive error but may be due to another cause. For example, when it is determined that the subject's eye is one for which refractive correction is not possible, the control unit 30 outputs the first visual acuity value and a statement of suspected disease as the test results.

For example, when the spherical power falls below the reference spherical power (±0.50D) (for example, ±0.75D, ±1.00D, etc.) (when it is lower than the reference spherical power), the control unit 30 performs refractive correction of the test eye and obtains a second visual acuity value (S11). Note that the flow after obtaining the second visual acuity value (S11) is performed in the same manner as in the above embodiment (see S3, S12, S13, S14, S15).

As described above, for example, the acquisition means may acquire the objective eye refractive power when the correction determination means determines that the first visual acuity value is equal to or lower than the first reference visual acuity value, and may acquire the second visual acuity value when the correction determination means determines that the acquired objective eye refractive power is lower than the reference visual acuity value. Also, for example, the correction determination means may determine that the subject's eye is one that cannot be refractively corrected when it determines that the second visual acuity value is equal to or lower than the second reference visual acuity value. With this configuration, for example, it is possible to more accurately determine whether or not the cause of poor visual acuity is refractive error from both the objective result and the second visual acuity value, making it possible to detect abnormalities in the subject's eye other than refractive error at an early stage.

In this modified example, a configuration for determining whether or not the test eye is a test eye that can be refractively corrected based on the first visual acuity value, the second visual acuity value, and the objective refractive power has been described as an example, but a configuration for determining whether or not the test eye is a test eye that can be refractively corrected based on the first visual acuity value and the objective refractive power may also be used. In this case, for example, the acquisition means may acquire at least the objective refractive power when the correction determination means determines that the first visual acuity value is a visual acuity value equal to or lower than the first reference visual acuity value, and the correction determination means may determine that the test eye is a test eye that cannot be refractively corrected when the objective refractive power is determined to be equal to or higher than the reference refractive power. With such a configuration, for example, the test eye can be determined based on the objective results, so that the influence of the test result due to the tester's response method, such as incorrect answers by an examiner who is unfamiliar with the test, can be suppressed, and it is possible to more accurately grasp whether or not the cause of poor visual acuity is refractive error.

REFERENCE SIGNS LIST 1 Vision testing device 2 Presentation window 3 Input button 4 Response button 5 Response lever 6 Speaker 7 Printer 8 Lamp 9 Housing 20 Optotype presentation unit 30 Control unit 31 Memory 40 Control box 60 Correction means

Claims (2)

A visual acuity testing device for testing the visual acuity of a subject, comprising:
an optotype presenting unit that emits an optotype light beam and presents a test optotype to a subject;
A response means for inputting the subject's interpretation result for the presented test optotype;
a visual acuity assessment means for determining whether the interpretation result input by the response means is correct or incorrect, and automatically acquiring the visual acuity value of the subject;
A correction means for changing the optical characteristics of the target light beam;
Equipped with
acquiring a first visual acuity value of the subject by the visual acuity assessment means;
An acquisition means for acquiring a second visual acuity value of the subject at the time of refractive correction, the second visual acuity value being different from the first visual acuity value;
a correction determination means for determining whether or not the subject's eye is an eye that can be corrected for refractive error based on the first visual acuity value and the second visual acuity value acquired by the acquisition means;
a standard setting means for setting a second standard visual acuity value for determining whether or not the subject's eye is an eye that cannot be refractively corrected, based on the first visual acuity value;
Equipped with
When the correction determination means determines that the first visual acuity value is equal to or lower than the first reference visual acuity value, the acquisition means controls the correction means to correct the visual acuity of the subject, and determines whether the interpretation result input by the response means is correct or not to automatically acquire the second visual acuity value;
A vision testing device characterized in that the correction determination means determines that the test eye is an eye that cannot be refractively corrected when it determines that the second visual acuity value is equal to or lower than a second standard visual acuity value. 2. The vision testing device of claim 1,
The visual acuity testing apparatus according to claim 1, wherein the standard setting means sets the second reference visual acuity value to a visual acuity value equal to or greater than the first visual acuity value based on the first visual acuity value.