JPH11178794A - Sight examining meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a visual acuity meter capable of precisely and quantitative ly measuring night visual acuity by simple constitution. SOLUTION: The eye of an examinee is irradiated for a prescribed time by an illuminating light source 46 to made the eye to be examined light-adopted. After then, illumination is lowered to make the eye to be examined dark-adapted. As the examinee becomes to be able confirm the eye index of an eye index board 17 during it, the confirming is reported by a response switch 6. The period until this confirming is measured as night visual acuity. Satisfactory environment for light adaptation and dark adaptation can be provided for the examinee to quantitatively and precisely measure the night visual acuity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual acuity meter, and more particularly to a visual acuity meter capable of measuring night vision.

[0002]

2. Description of the Related Art Since the cause of traffic accidents increases due to a decrease in visual acuity at night, it is important to quantitatively measure the visual acuity at night. Therefore, a night vision test for measuring vision under low illuminance after light adaptation is performed.

[0003]

When the brightness of the environment changes, the human eye has a function of adapting naturally. Therefore, when measuring night vision, it is important to measure night vision in consideration of the eye adaptation function, particularly light adaptation or dark adaptation. However, the conventional visual acuity meter has a problem that it is not possible to provide a favorable environment for adaptation of the subject's eyes, and it becomes difficult or inaccurate to measure the night vision.

In addition, if the subject closes his or her eyelids during eyesight measurement, sufficient light adaptation cannot be performed and correct measurement cannot be performed. Therefore, it is necessary to constantly monitor the state of the subject's eye during light adaptation. However, when the examiner monitors the eye-opening state of the subject only by visual observation, there is a drawback that the instantaneous blink of the subject is missed and the reliability of the measurement is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an agitometer capable of accurately and quantitatively measuring night vision with a simple configuration.

[0006]

In order to solve the above problems, according to the present invention, an optotype displaying means for displaying an optotype and an optotype displayed at a predetermined optical distance are displayed. An eyepiece for illuminating the subject's eyes for a predetermined period of time; a responding unit for sending a signal when the subject confirms the optotype; After illuminating the eyes of the user, the illumination is reduced to check the visual target, and measuring means for measuring the time until the check is provided, and the night vision is measured based on the measured time.

With such a configuration, a good light adaptation and dark adaptation environment can be provided to the subject, and night vision can be quantitatively and accurately measured.

[0008]

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

1 (A) and 1 (B) schematically show the front and side surfaces of an agitometer according to an embodiment of the present invention. Observes the optotype by placing the left eye on the left eye 1a and the right eye on the right eye 1b of the eyepiece 1. The optotype is provided with a blackout curtain 3 that can expand and contract along the guide 2, so that the index can be observed well.

[0010] An operation panel 5 as shown in detail in FIG. The operation panel 5 is provided with a power switch 5a. When the power switch is turned on, the night vision measuring switch 5b (still)
The eyesight measurement switch 5c is turned on. In addition, the left eye, both eyes,
Right eye selection switches 5d to 5f are provided, and by operating these switches, the left eye, both eyes, and right eye of the subject's eye can be set to the target observation state. The optotype switches 5g to 5j are used to switch the direction of a cut of a known optotype (Landolt ring).
m and 5n change the visual target to change the visual acuity value, and the changed visual acuity value is displayed on the display unit 5q. In addition, the adaptation time display section 5p can display the progress of the dark adaptation time. Further, the display panel 5 is provided with a lighting lamp 5x for displaying the opened or closed state of the eye to be inspected, and a sensitivity adjustment button 5y for changing the detection sensitivity is disposed below the lighting lamp 5x.

In FIG. 1A, reference numeral 6 denotes a response switch which is depressed when the subject recognizes a break in the target and confirms the target.

FIG. 3 shows the optical arrangement of the optometer and the arrangement of the control unit. In FIG. 3, the left eye 1 of the subject is shown.
0 and the right eye 10 ′ are covered with cover glasses 11, 11 ′, shutters 12,
It is located before 12 '. When the left eye selection switch 5d is operated, the shutter 12 is operated, and when the right eye selection switch 5f is operated, the shutter 12 'is operated again.
When e is operated, both shutters 12, 12 'are driven by the actuator 41 operated by the CPU 40, respectively, and separate from the optical path.

When the shutter 12 leaves the optical path, the mirrors 13 and 14, the half mirror 14 ', the focusing lens 15
Through the window glass 16a of the reflective dome 16, the optotype plate 17 located behind the reflective dome can be observed, while when the shutter 12 'separates from the optical path, the mirror 13', half mirror 14 ', and The optotype plate 17 disposed behind the reflection dome can be observed through the window glass 16a of the reflection dome 16 through the focusing lens 15. The reflection dome 16 is formed of a diffusive member, and is illuminated with a dome illumination light source 42 for stationary vision, which is driven under the control of the CPU 40, and is diffusely illuminated. When the night vision is measured, the reflective dome 16 is illuminated using a dome illumination light source (halogen lamp) 46 adapted for light adaptation in order to adapt the eye to be examined.

The optotype plate 17 has its axis 17a connected to the CPU 40.
Are connected to the axis of a stepping motor 43 driven by the motor, and a plurality of targets 17b are arranged around the shaft. Each of the optotypes is a set of four optotypes whose cuts are different by 90 degrees, and the size of each set is different according to the visual acuity value.
One of the reflection dome windows 16b
Moved to In order to measure night vision, a target corresponding to, for example, a visual acuity value of 0.2 is covered with a diffusion plate 17c. Further, when measuring the normal static visual acuity, each of the visual targets is illuminated from behind by the visual target illumination light source 44 for the static visual acuity driven under the control of the CPU 40 via the half mirror 18, and When the night vision is measured, it is illuminated via the half mirror 18 by a night vision visual target illumination light source 45 driven under the control of the CPU 40.

Each of the displayed targets is a focusing lens 1
By adjusting 5, the optical distance to the eyepiece can be set to an optimal optical distance for visual acuity measurement, and an apparent optotype of 5 m can be formed. Further, in order to prevent the measurement from being disturbed by blinking during the measurement, a light receiving element 47 for receiving the reflected light from the eye to be examined which is illuminated by the dome illumination light source 46 of the light order application is provided. Is input to the CPU 40. Eyelid closed, light receiving element 4
When the amount of light incident on 7 decreases, the lamp 5x is turned on. The sensitivity at which the eyelid is closed and the lamp 5x is turned on can be adjusted with the sensitivity adjustment button 5y.

The CPU 40 is driven by a clock 50, and a memory 51 stores programs, data, and the like necessary for an eyesight test. The CPU 40 can take in signals from various switches or buttons disposed on the operation panel 5 or signals from the response switch 6 via the interface 52, and display various data on the display units 5p and 5q.
Or it can be displayed on the lamp 5x. Further, a voice guidance 53 for guiding the program progress can be output.

Next, the flow of measuring night vision and still vision will be described with reference to the flowchart of FIG. This program is stored in the memory 51,
This is executed under the control of 0.

First, in step S1, the power switch 5a is turned on. With this, the night vision measurement switch 5
b, the static visual acuity measurement switch 5c is turned on, and each visual acuity measurement state is set.

In step S2, when the night vision measurement switch 5b is pressed, the night vision measurement is started, and at this time, first, in step S3, the shutters 12, 12 'are separated from the optical path by the actuator 41. Normally, night vision is measured with both eyes, but when measuring with either eye, the shutter corresponding to the eye is removed from the optical path. In step S4, by driving the stepping motor 43, the target having a cut in a predetermined direction corresponding to, for example, a visual acuity value of 0.2 is moved to the window 16b of the diffusion dome 16 together with the diffusion plate 17c thereon. . At this time, the optotype illumination light source 45 for night vision is turned on in step S5, and the optotype is illuminated from behind (e.g., illuminated with a dark luminance of 0.1 to 0.15 cd / sq. M).

In the case of night vision measurement, the eye to be inspected needs to be sufficiently adapted to light. Therefore, in step S6, the dome illumination light source 46 for light order application is turned on to illuminate the dome and the eye to be inspected (for example, 5700 cd). / Square m of illumination). Since the light adaptation is performed in about 30 seconds, the light source 46 is turned off, and a response from the subject is awaited in step S7. The subject is almost in a dark state by turning off the illumination light source 46, and it is possible to confirm the discontinuity of the displayed target during dark adaptation. Then, when the subject can confirm the break of the optotype, the subject responds with the response switch 6. Light source 46
The time from turning off to the response is measured by a timer (not shown) in the CPU and displayed on the display 5p. This time quantitatively indicates the subject's dark adaptation ability, that is, night vision, and is measured as night vision.

While the illumination light source 46 is turned on to light-adapt the eye to be examined, whether or not the eyelids of the eye to be examined are open is measured by using the light receiving element 47, and when the eye is closed by blinking or the like, The lamp 5x is turned on to notify the examiner of the fact.

On the other hand, when the static visual acuity measurement switch 5c is selected in step S2, static visual acuity measurement is started, and in steps S13, the switches 5d to 5f are switched.
Shutter 1 according to which eye is selected by
Either 2 or 12 'or both are out of the light path. In step S14, the target is illuminated by the target illumination light source 44, and the reflection dome 16 is illuminated by the dome illumination light source 42. When an optotype corresponding to a predetermined visual acuity value is set using the visual acuity change switches 5m and 5n and the optotype switches 5g to 5j in step S15, the stepping motor 43 rotates and the selected optotype is displayed in the window 16b. Moving. At this time, the set visual acuity value is displayed on the display 5q. The subject responds with the response switch 6 if the target can be confirmed (step S16), and if not, the process proceeds to step S16.
Returning to 15, the examiner changes the optotype switches 5g to 5j or the eyesight change switches 5m and 5n, and repeats this until the subject can be confirmed. When there is a response, the value displayed on the display 5q is measured as a static visual acuity (step S17).

If there is no response from the response switch 6 during night vision or stationary vision measurement, the measurement can be advanced by changing the measurement program such as automatically changing the vision value. Further, when the eyelid is closed during night vision measurement, the examiner can be informed to that effect by the lamp 5x or can be informed to the examiner and the examinee by voice. Further, when the eyelid is closed, the measurement program can be changed so that the detection level for automatically detecting that the eyelid is closed is changed and the measurement is performed again. In addition, audio guidance 53 indicates the progress of each measurement.
At any time, and the subject can be guided by voice according to a preset program.

[0024]

As described above, according to the present invention, the subject's eyes are illuminated for a predetermined period of time to cause light adaptation, and then the illumination is reduced to confirm the optotype. Since the measurement is used to measure night vision, a good light adaptation and dark adaptation environment can be provided to the subject, and the night vision can be quantitatively and accurately measured. .

In the present invention, the closed state of the subject can be detected during night vision measurement by detecting the reflected light from the anterior segment, so that it is monitored whether or not the light adaptation state is maintained. be able to.

Further, according to the present invention, not only night vision,
Still vision can also be measured, and both tests can be easily performed in a small space. In addition, since the measurement can be performed by guiding the subject by voice according to a preset program, it is not necessary for the examiner to be present at the place, so that the measurement can be performed automatically. Can be achieved.

[Brief description of the drawings]

FIG. 1A is a front view of an eyesight meter according to an embodiment of the present invention, and FIG. 1B is a side view thereof.

FIG. 2 is an arrangement diagram showing an arrangement of various switches on an operation panel.

FIG. 3 is a configuration diagram showing a configuration of an optical system and a configuration of a control system of the eyesight meter.

FIG. 4 is a flowchart showing the flow of eyesight measurement.

[Explanation of symbols]

 6 Response switch 12, 12 'Shutter 16 Diffusion dome 17 Optotype plate 42 Dome illumination light source for static vision 44 Optotype illumination light source for static vision 45 Optotype illumination light source for night vision 46 Dome illumination light source for light order application 47 Light receiving element

Claims (6)

[Claims] 1. An optotype display means for displaying an optotype, an eyepiece for viewing an optotype displayed at a predetermined optical distance, and illuminating the subject's eyes for a predetermined time. Illuminating means for performing, a response means for sending a signal when the subject confirms the target, the predetermined time, after illuminating the subject's eyes, reduce the illumination and confirm the target, A visual acuity meter, comprising: measuring means for measuring time until confirmation, and measuring night vision based on the measured time. 2. The method according to claim 1, further comprising a step of receiving illumination reflected light from an anterior eye of the subject, and detecting a closed state of the subject based on the amount of light received while measuring the eyes of the subject. The optometer according to claim 1, wherein: 3. The optometer according to claim 1, wherein when the closed eye state is detected, the sensitivity for detecting the closed eye state can be adjusted. 4. The optometer according to claim 1, wherein a normal still visual acuity can be measured by changing the size of the visual target. 5. The optometer according to claim 1, wherein the progress of the measurement program is changed according to the measurement result. 6. The optometer according to claim 1, wherein the measurement can be advanced by voice guidance.