JP2005052677A - Visual acuity testing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a visual acuity testing apparatus for accurately testing visual acuity, by making a far-sighted state without a sense of incompatibility. <P>SOLUTION: This visual acuity testing apparatus has a testing window for a subject eye to peep into a testing target presented inside a casing. The apparatus has cylindrical left-right inner wall members laterally individually arranged for separating optical paths of left-right eyes, that is, the laterally symmetrical left-right inner wall members having respectively the testing window and a target presenting window for the left-right eyes, lenses respectively arranged in the optical paths of the left-right inner wall members for setting a part between the testing window and the presenting target to a prescribed optical distance, and an inner wall illuminating light source for illuminating the respective insides for setting an inside space of the left-right inner wall members to prescribed brightness. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a visual acuity inspection apparatus that presents an inspection target and inspects visual acuity and the like.

There is known a visual acuity inspection apparatus configured to inspect visual functions such as visual acuity by providing a binocular inspection window to be examined by a subject and observing an inspection target arranged inside the housing through the inspection window. ing. As this type of device, an ordinary visual acuity inspection device that optically disposes an inspection target placed in a housing at a distant position (5 m) and inspects its appearance, and what is called a night vision meter is also known. It has been.
This night vision meter provides a visual target in a darkened space inside the housing after light adaptation to the eye to be examined by looking through the examination window the space in the housing equivalent to the daytime brightness Then, the visual acuity recovery time until the visual target can be visually recognized is measured (see Patent Document 1).
Microfilm of Japanese Utility Model No.54-1198 (Japanese Utility Model Application No.50-69095)

However, since this type of conventional apparatus is configured to look into one housing with the left and right eyes, the distance between the left and right walls is different when looking through the examination window with each of the left and right eyes, and the target observation is uncomfortable. Such observation has a drawback that it is difficult to create a state of looking at a distance of 5 m, and the accuracy is inferior to that of an eyesight test at an actual distance of 5 m.
In view of the above-described problems of the prior art, an object of the present invention is to provide a visual acuity inspection apparatus that can create a far vision state without a sense of incongruity and can perform inspection with high accuracy.

In order to solve the above problems, the present invention is characterized by having the following configuration.
(1) Cylindrical left and right inner wall members separately provided on the left and right sides to separate the optical paths of the left and right eyes in a visual acuity inspection apparatus having an inspection window for an eye to look through an inspection target presented inside the housing The left and right inner wall members are provided so as to have a predetermined optical distance between the left and right symmetrical inner wall members each having a right and left eye inspection window and a target presentation window. A lens provided in each of the optical paths of the member; and an inner wall illumination light source that illuminates each interior to make the inner space of the left and right inner wall members have a predetermined brightness.
(2) In the visual acuity test apparatus according to (1), a target eye designating unit that designates the right and left of the eye to be examined and a target illumination that illuminates the target placed in each target presentation window for the left and right eyes from behind. A light source; and a control unit that controls turning on / off of the inner wall illumination light source and the target illumination light source based on left and right designations by the eye designation unit.
(3) The visual acuity test apparatus according to any one of (1) and (2) causes the eye to be examined to look into the examination window by turning on the inner wall illumination light source, and then turns off the inner wall illumination light source and performs visual inspection. It is a night vision meter having a measuring means for presenting the target with a predetermined luminance and measuring the visual acuity recovery time until the subject's eye can visually recognize the presented target.

  According to the present invention, it is possible to create a far vision state without a sense of incongruity and to perform inspection with high accuracy.

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a view showing an appearance of a night vision test apparatus according to the present invention.
Reference numeral 1 denotes an apparatus main body, and a binocular inspection window 2 (2R, 2L) is provided on the upper part of the apparatus main body 1 so that a subject can look into a visual target presented inside the housing of the apparatus. An operation panel 3 having various switches and a printer 8 are disposed on the side surface of the apparatus main body 1. The front side of the lower part of the apparatus main body 1 responds that the subject has read the joystick (lever) 5 for responding the direction of the visual target presented inside the main body, and the visual target. A button 4 is provided for use at times. Reference numeral 6 denotes a start switch in the automatic inspection mode, and reference numeral 9 denotes a speaker to which a voice guidance instruction is output.

FIG. 2 is a schematic view of the optical system arranged inside the apparatus as viewed from the side, and also shows the configuration of the control system. FIG. 3 is a schematic view of the optical system inside the apparatus as viewed from above.
Lenses 10R and 10L are arranged on the left and right examination windows 2R and 2L, respectively, and the examination target to be switched to the rear target windows 15R and 15L is set to an apparent examination distance of 5 m from the subject's eyes ER and EL. The The left and right optical paths are divided by cylindrical inner covers 11R and 11L having a partition plate in the center, and a visual field space in which the left and right eyes see the target is individually secured. The inner covers 11R and 11L have the same shape, and left and right inner wall surfaces are symmetrically formed around the central axes 01R and 01L of the inspection windows 2R and 2L (respective optical axes of the lenses 10R and 10L). The rear target windows 15R and 15L are also provided at the same position. Therefore, when the inside is observed through the inspection windows 2R and 2L with both the left and right eyes, the two visual target windows 15R and 15L are fused and appear as one, as in the case where the inside is observed with the left and right eyes alone. At the same time, the inner covers 11R and 11L are also observed as one space with the same left and right walls. For this reason, the subject can see the inspection target placed optically at a distant distance (5 m) without a sense of incongruity.

The inner surfaces of the inner covers 11R and 11L are painted with a matte white paint. During normal visual examination or during light adaptation for measuring the visual recovery time, the illumination lamps 12R and 12L are both turned on to have a predetermined brightness. To be. The illumination lamps 12R and 12L are placed at positions where the illumination light does not directly enter the eye to be examined. Further, lamps 14 (having luminance equivalent to vehicle headlamps) that are turned on at the time of dimming visual acuity measurement or the like are arranged on the left and right of the target windows 15R and 15L, respectively. The dazzling visual acuity measurement turns on the lamp 14 to inspect the influence of visual acuity when receiving glare due to a headlight of an oncoming vehicle during driving at night.
The optotype presenting unit 20 that switches and arranges the inspection optotypes in the optotype windows 15R and 15L includes one optotype disc plate 21, a pulse motor 22 for rotationally driving the optotype disc plate 21, and the optotype disc. It consists of two illumination lamps 24R and 24L that illuminate the target on the plate 21.

  The optotype disc plate 21 is made of a light-transmitting glass substrate, and on the substrate, Landolt in four directions (left, right, up and down) in 12 stages with visual acuity values of 0.1 to 1.0, 1.2, and 1.5. The ring target is formed of a chrome coat having a light shielding property. This inspection optotype is formed so as to correspond to the positional relationship between the two optotype windows 15R and 15L so that the same target for right eye presentation and left eye presentation can be simultaneously presented to the left and right eyes. . In addition to the inspection target, a shielding plate is provided on the target disk plate 21 to shield the target windows 15R and 15L during bright adaptation in the night vision test.

The same target on the target disc plate 21 is arranged in the target windows 15R and 15L by the rotation of the motor 22, and each target is illuminated by the illumination lamps 24R and 24L. During normal visual acuity measurement, the examination target is presented with a luminance of about 250 cd / m ² when the illumination lamps 24R and 24L are turned on, and during the visual acuity recovery time measurement, the light intensity of the illumination lamps 24R and 24L is usually reduced to 0.15 cd / m. A test target is presented with a dim brightness of about m ² .

  In the case of an inspection in which the target illumination brightness is reduced in this way, if the reflected light on the target surface due to the light incident from the inspection window 2 reaches the subject's eye, the subject will see the target. Therefore, it becomes difficult to perform highly accurate inspection. Therefore, as shown in FIG. 4, the target surface of the target disc plate 21 is inclined at an angle θ with respect to a plane M perpendicular to the central axis 01 connecting the center of the examination window 2 and the target presentation position P. It is arranged so that the reflected light on the target surface does not reach the eye to be examined. This inclination angle θ is determined as follows.

  In FIG. 4, a position where a virtual window 2 ′ having the same diameter as the inspection window 2 does not overlap the inspection window 2 is assumed. Considering the central axis 02 connecting the center of the virtual window 2 ′ and the visual target presentation position P, the central axial line 03 is set at an intermediate angle between the central axial line 02 and the central axis 01 at the visual target presentation position P. The visual target surface is arranged so as to be orthogonal to the central axis 03 at the visual target presentation position P. As a result, the light incident from the inspection window 2 and reflected by the target surface does not pass through the inspection window 2 again. Become invisible.

For example, if the diameter of the inspection window 2 is 24 mm and the actual distance from the inspection window 2 to the target presentation position P is 240 mm, θ = 2.9 degrees is calculated from the calculation of θ = tan ⁻¹ (12/240). Therefore, the target surface may be inclined with respect to the surface M by 3 degrees or more.
In the present embodiment, the left and right eyes are configured to separate the optical paths for observing the visual target. However, the above-mentioned visual observation is also applied to an apparatus of a type in which the left and right eyes look into the inspection visual target placed in the center in one housing. The same applies to the slope of the surface.

  In FIG. 2, reference numeral 30 denotes a control unit for controlling the entire apparatus. Each lamp, pulse motor 22, voice guide generation unit 31 connected to the speaker 9, response button 4, joystick 5, operation panel 3, etc. A memory 33 storing a program is connected.

  Next, the operation of the apparatus having the above configuration will be described. In addition, this device has a manual mode, an automatic mode (a mode in which a test program is advanced by the subject operating the joystick 5 according to a voice guide), a semi-automatic mode (a verbal response of the subject to the automatic mode). 3), and the mode selection switch 40 on the operation panel 3 can be used to select one of the three inspection modes. Hereinafter, the inspection in the automatic mode will be described. The automatic mode is programmed so that normal eyesight measurement (5m eyesight measurement), eyesight recovery time measurement (night vision test), and glare-sighted eyesight measurement are sequentially advanced. Keep it. The measurement eye can be designated as right, left, or both eyes. Here, it is assumed that both eyes are designated.

When the subject presses the start switch 6, first, normal visual acuity measurement is started. The control unit 30 turns on the illumination lamps 12R and 12L to make the space of the inner covers 11R and 11L have a luminance of 30 cd / m ² and controls the driving of the pulse motor 22 and the lighting of the illumination lamps 24R and 24L. A visual target having a visual acuity value of 0.5 is presented in the standard windows 15R and 15L. Further, when the direction of the target can be determined by the voice guide, the subject is instructed to tilt the joystick 5 in that direction. When the subject responds with the joystick 5 with the target discrimination result, the controller 30 determines the correctness. If the response is correct, the visual target with the visual acuity value raised by one level is presented, and if the response is incorrect, the visual target with the visual acuity value lowered by one step is presented. If the answer is incorrect or cannot be discriminated by one step (when the response button 4 is pressed if it cannot be read), the visual acuity value is returned to the level at which it was visible, and the test is continued by changing the direction of the target. If the correctness / incorrectness is determined by the control unit 30 and there is a correct answer twice or more with the same visual acuity target, the visual acuity value is determined as having the visual acuity.

  Subsequently, a program for measuring the visual acuity recovery time is executed (see the flowcharts of FIGS. 5 and 6). After the voice guide announces that the lamp is turned on and brightens for 30 seconds, the illumination lamps 12R and 12L are turned on to illuminate the visual field space seen by the subject's eye, and time measurement for light adaptation to the subject's eye is started. The During this time, the shielding plates provided on the target disk plate 21 are placed on the target windows 15R and 15L.

When it approaches the end of the light adaptation time, the voice guide announces that after darkening, if you can see the target, immediately push down the lever in the direction of the broken ring. After completion of the light adaptation time, the illumination lamps 12R and 12L are turned off and a target with a visual acuity value of 0.2 is placed in the target windows 15R and 15L. The target is 0.15 cd by the illumination lamps 24R and 24L. Presented with a dim brightness of about / m ² . The control unit 30 measures the time from the start of the target presentation and checks the response input of the interpretation result by the joystick 5. Here, when there is no response input even after 60 seconds have elapsed (the same applies when the response is incorrect), the target luminance is increased to twice the initial brightness (approximately 0.30 cd / m ² ). . If there is no response input even after 70 seconds, the target brightness is increased to the first three times the brightness (about 0.45 cd / m ² ), and after the 80 seconds, the first four times the target. Increased brightness. In this way, after 60 seconds have passed, not only the time to complete the measurement, but also the target brightness cannot be responded at the first target brightness by sequentially increasing the target brightness every 10 seconds. Even if it is a test subject, possibility that a visual target will be visually recognized becomes high. When 90 seconds have elapsed, the measurement result is “90 seconds have elapsed”, and the measurement is terminated.

  When there is a response input by the joystick 5, the control unit 30 determines whether it is correct or incorrect. If the response is incorrect and it is the first time (if it is not twice in error), after the direction of the test target to be presented has been changed, further “please tilt the lever in the direction of the broken ring Is announced and measurement is continued. When the response is incorrect, the target is not visually recognized, so it is not treated as a measurement result. When there is a response input again and the response is erroneous twice consecutively, remeasurement from the light adaptation is automatically performed. Note that the remeasurement is limited to once, and even if the remeasurement is performed, if the response is erroneous twice consecutively, the measurement is stopped, and the measurement of the visual acuity recovery time itself is ended.

  When the response input by the joystick 5 is determined to be the correct answer and it is the first time (when it is not two consecutive correct answers), the direction of the test target to be presented is changed in the same manner as above, Please push down the lever in the direction that it was cut off ". And if the next response input is a correct answer again, and it is within 5 seconds from the response of the previous correct answer, it becomes a correct answer twice in succession, and the subject judges that the target is visible. Since it is possible, the measurement time at the first continuous response is taken as the measurement result (sight recovery time). Here, if 5 seconds have passed since the response of the previous correct answer, the previous correct answer is unreliable (that is, if the target is surely visible at the time of the previous response, the next presentation Since the response of the mark should be fast, the previous response is treated as an error instead of two consecutive correct answers, and the time of the current correct answer is set as the first correct answer time.

  As described above, when there are two consecutive correct answers, the reliability of the measurement result can be improved by setting the initial response time as the visual acuity recovery time. Moreover, since the measurement is continued as it is with one wrong answer (when it is not two consecutive wrong answers), there is no need to perform unnecessary remeasurement.

When the measurement of the visual acuity recovery time is completed, the visual acuity measurement under glare is then performed. After being instructed by the voice guide to gaze at the target and respond to the direction of the presented target, the lamps 14 on both sides of the target windows 15R and 15L are turned on. A visual target with a visual acuity value of 0.5 (or a visual target having a visual acuity value finally determined by normal visual acuity measurement) is presented in the visual target windows 15R and 15L. Determined by the control unit 30. Based on the result, the next presentation target is determined, and if there is a correct answer two or more times with the same visual target, the visual acuity value is determined as having visual acuity.
When the inspection is completed, the printer 8 automatically prints out the measurement results, the determination results of the measurements, and the general guidance content.

  The case where binocular measurement is designated has been described above. For example, when the right eye alone measurement is designated by the switch unit 41, the control unit 30 turns on the designated illumination lamp (12R, 15R, 14). The lighting control is performed as described above, and the left-eye illumination lamp remains off. Since the left and right eyes can be switched by controlling the lighting lamps placed inside and off in this way, the left / right switching mechanism using a conventionally used shielding plate (inserting a shielding plate in front of the eyes to There is no need to provide a mechanism for switching, and the apparatus can be configured at low cost.

It is the figure which showed the external appearance of the night vision test apparatus which concerns on this invention. It is the figure which showed the outline when the optical system arrange | positioned inside an apparatus is seen from the side surface, and the outline of the control system. It is the schematic when the optical system inside an apparatus is seen from the upper part. It is a figure explaining the determination method of the inclination angle of a target surface. It is the figure which showed the flowchart explaining the measurement of visual acuity recovery time. It is the figure which showed the flowchart explaining the measurement of visual acuity recovery time.

Explanation of symbols

2R, 2L Inspection window 10R, 10L Lens 11R, 11L Inner cover 15R, 15L Target window 12R, 12L Illumination lamp 21 Target disk plate 24R, 24L Illumination lamp 30 Control unit

Claims (3)

In a visual acuity inspection apparatus having an inspection window for an eye to look into an inspection target presented inside a housing, cylindrical left and right inner wall members provided separately on the left and right to separate the optical paths of the left and right eyes, Right and left inner wall members having left and right eye inspection windows and visual target presentation windows, and optical paths of the left and right inner wall members to provide a predetermined optical distance between the inspection window and the presentation visual target. A visual acuity inspection apparatus comprising: a lens provided in each case; and an inner wall illumination light source that illuminates the interior of each of the inner walls of the left and right inner wall members so as to have a predetermined brightness. In the visual acuity test apparatus according to claim 1, an eye designation means for designating left and right of the eye to be examined, a target illumination light source for illuminating a target placed in each target presentation window for the left and right eyes from behind, An eyesight inspection apparatus comprising: control means for controlling on / off of the inner wall illumination light source and the target illumination light source based on left and right designation by the eye designation means. The visual acuity inspection device according to claim 1 or 2, wherein after the bright adaptation of the eye to be examined looking into the examination window by turning on the inner wall illumination light source, the inner wall illumination light source is turned off and the examination target is set to a predetermined luminance. A visual acuity examination apparatus comprising: a night vision meter having a measuring means for measuring a visual acuity recovery time until the eye to be examined can be visually recognized.