JPS642370B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an automatic visual acuity meter that changes the visual target presentation time depending on the response speed of the subject.

[Prior Art] Conventionally, visual acuity tests have been carried out by presenting a visual acuity chart or the like to a subject, and having the subject respond verbally or manually to determine the visual acuity. However, in recent years, a method of presenting visual targets such as Landolt's ring in an automatic visual acuity meter and determining visual acuity based on whether the test subject inputs the correct or incorrect information has come into widespread use.

In this type of automatic visual acuity meter, in order to shorten the measurement time and homogenize the examination, the visual target presentation time is fixed, and if there is no response input within a predetermined time, the visual target is advanced to the next step. It is being harvested. However, with this method, the subject does not know that the predetermined time has elapsed, and may often miss inputting a response.

In order to improve this shortcoming, a device that sets a different time within the visual target presentation time and prompts the subject to input a response if no response input is received within this time, attempts to carry out the measurement smoothly. The applicant has already proposed this. However, even for subjects with the same visual acuity value, there are individual differences and judgment times vary, so if the visual target presentation time is constant as in this proposal,
For subjects who have a short judgment time, the time from inputting a response until the next optotype is presented is wasted, and for subjects who have a long judgment time, they are prompted to input a response and may feel rushed. You may end up inputting the wrong answer, or you may miss the input in time. Therefore, this visual acuity meter cannot be said to be a visual acuity meter that can fully meet the demand for automatically, quickly and accurately measuring visual acuity.

[Object of the Invention] The object of the present invention is to compare the time required for each test subject to input a response with a set value, and to vary the next optotype presentation time depending on the magnitude of the time. An object of the present invention is to provide an automatic visual acuity meter that gives an optimal optotype presentation time to a subject while taking into consideration individual differences in response input time, and that combines shortening of measurement time and measurement accuracy.

[Summary of the invention] The gist of the present invention for achieving the above object is as follows:
an optotype presentation section that presents the optotype to the subject for a first time; a response input section through which the subject inputs a response to the optotype; a comparison section that compares the response time up to the time of inputting the response to the response input section with a second time that is shorter by a certain percentage with respect to the first time; determining the first time for presenting the mark; if the response time is greater than the second time, the next first time is increased; if the response time is less than the second time; and a control section that decreases the first time.

[Embodiments of the Invention] The present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a block diagram showing the configuration of an automatic visual acuity meter, in which various parts are connected with a microcomputer 1 as the functional center. That is, the microcomputer 1 has an interface 2, an internal bus 3,
Consists of CPU 4, RAM 5, and ROM 6, and interface 2 connects CPU 4 and RAM via internal bus 3.
5 and ROM 6 so that information can be transmitted between them.

This interface 2 is connected to an optotype section 7, a counter 8, a conversion section 9, a first comparison section 10, an optotype presentation time control section 11, a second comparison section 12, and a storage section 13, respectively. The interface 2 and the optotype section 7, counter 8, and conversion section 9 are connected in the direction in which signals from the interface 2 are transmitted, and the interface 2 and the first comparison section 1
0 and the optotype presentation time control unit 11 are connected to each other so that signals are transmitted to each other, and the interface 2 and the second comparison unit 12 are connected to each other so that signals from the second comparison unit 12 are transmitted. connected in the direction of transmission to interface 2, and interface 2 and storage unit 1
3 is connected in the direction in which signals from the storage section 13 are transmitted to the interface 2. Conversion unit 9 and optotype presentation time control unit 11/second comparison unit 12
The counter 8 and the first comparison section 10 and the second comparison section 12 are connected in the direction in which the signals from the counter 8 are transmitted. Further, the signal from this counter 8 is transmitted to the response time storage section 14. The response time storage unit 1 is connected between the response time storage unit 14 and the visual target presentation time control unit 11.
4 is connected in the direction in which signals are transmitted. Further, the first comparison section 10 and the storage section 13 are connected in the direction in which the signal from the first comparison section 10 is transmitted. Further, an input switch 15 is provided, and the input switch 15 and the storage section 13/response time storage section 14 are connected in the direction in which the signal from the input switch 15 is transmitted.

Since this embodiment has the above-described configuration, it operates according to the control program written in the ROM 6 in the microcomputer 1, stores new data in the RAM 5, calculates and controls it by the CPU 4,
Measurement operations are performed sequentially by transmitting and receiving signals to and from external circuits via the internal bus 3 and interface 2.

First, a control signal S1 is sent from the interface 2 to the optotype section 7, and the optotype is presented to the subject at the optotype section 7. At the same time, a reset signal S2 is sent from the interface 2 to the counter 8, and the counter 8 is reset and starts counting time every time the optotype is presented in the optotype section 7. Then, the count output S3 of the counter 8 is sequentially outputted to the first comparator 10 and the second comparator 10.
It is input to the comparison section 12 and response time storage section 14. Furthermore, the interface 2 outputs a first set value t1 corresponding to the optotype presentation time to the conversion section 9, first comparison section 10, and optotype presentation time control section 11. Then, the converter 9 converts this first setting value t1 to 70, for example.
% time is converted, and a second set value t2 is output to the optotype presentation time control section 11 and second comparison section 12.

Here, when the subject responds to the presented optotype using the input switch 15, the signal S4 from the input switch 15 is input to the storage section 13 and the response time storage section 13, and the storage section 13 receives the signal S4 from the input switch 15. In other words, the content of the test subject's response is memorized. The response time storage unit 14 stores the value of the output S3 of the counter 8 at the time when the input from the input switch 15 is made, and sends this value to the visual target presentation time control unit 11 as a signal T, that is, the response time of the subject. Output. The optotype presentation time control unit 11 sets the response time T, which is the output of the response time storage unit 14, to a first set value t1 and a second set value t2.
Compare with. And interface 2 has the first
The output signal S5 from the comparison section 10, the output signals S6 and S7 from the optotype presentation time control section 11, the output S8 from the second comparison section 12, and the output signal S9 from the storage section 13 are input.

Here, the timing of each signal output mentioned above is changed to the second
This is shown in the timing chart shown in the figure. Note that in this chart, the horizontal axis is the time axis, and points at time a,
The passage of time is expressed in the order of b, c, b', and d,
Time a is when the optotype is presented, time b is when the response is input from the response input switch 15, and from time a to time T
This is when the period of time has elapsed. Also, time c is the second point from time a.
When the set value t2 has elapsed, time b' is when a response due to correction is input, and time d is when the first set value t1 has elapsed from time a.

At time point a, a signal S1 from the interface 2 is sent to the optotype section 7, the optotype is presented, and a response input from the subject is awaited. Simultaneously with the presentation of this optotype, the counter 8 starts counting in response to a reset signal S2 from the interface 2, and a count output S3 is output to the first comparison section 10, second comparison section 12, and response time storage section 14, and the counter 8 starts counting by the reset signal S2 from the interface 2. At point a, the signals S1 and S3 become high level.

Further, the contents input by the input switch 15 at time b are stored in the storage section 13, and the response input signal S4 is further sent to the response time storage section 14, from which the contents of the counter 8 at time b are stored. A signal T is sent to the visual target presentation time control section 11.

Thereafter, when the count output S3 in the second comparison section 12 matches the inputted second set value t2 at time c, a coincidence signal S8 is outputted from the second comparison section 12 to the interface 2, and the optotype section For example, the Randall ring shown in step 7 is blinked to confirm with the subject whether or not the response input has been corrected.

If there is no correction, the first comparator 10 at time d
When the first set value t1 and the count output S3 of the counter 8 match, the first comparison section 10 outputs a match signal S5 to the interface 2, sets the output S1 for displaying the optotype to a low level, and stores the memory at that time. The contents of the section 13 are taken into the interface 2 as a response input value S9. In addition, if there is a correction, when the correction response S4 is input from the input switch 15 at time b', the output T of the response time storage section 14 will be the count output S of the counter 8 at that time.
It is exchanged with the contents of 3.

Here, when the response time T, which is the output from the response time storage unit 14, is T≦t2, the signal S6 is output from the visual target presentation time control unit 11 and input to the interface 2, and the response input time T is T> At t2, signal S
7 is output from the optotype presentation time control unit 11 and taken into the interface 2.

If the signal S6 is input to the microcomputer 1 after the first visual target presentation, the first set value t1, which is the next visual target presentation time, is shortened by, for example, 10%. Further, if the signal S7 is input, the first set value t1 is extended by, for example, 10%. Note that the upper and lower limits of the first set value t1 are set in advance, and are not to be exceeded.

In the case of this example, at the start of visual acuity measurement, the first
The set value t1 is set to, for example, 3 seconds, which is the average time required for inputting a response. In the case of a subject with a long response time, the response input time T will be T > t2, and if the subject is unable to respond within the first set value t1, or if the subject is prompted to respond and inputs an appropriate value, the true input value may be There may be cases where this is not possible. In such a case, the signal S7 is output from the optotype presentation time control unit 11, so the measurement is continued with the next first set value t1 set to 3.3 seconds, which is 10% higher than the current value. If the response is still slow, the first setting value t1 is sequentially increased until the upper limit time is reached, and the most suitable time for the subject is determined.

Conversely, in the case of a subject who is quick to make decisions, the response input time T becomes T≦t2, and the optotype presentation time control unit 11
emits the signal S6, so the next first set value t1
is decreased by 10% to 2.7 seconds, and thereafter, the first set value t1 is sequentially decreased for each optotype presentation until it reaches the lower limit, thereby obtaining the optotype presentation time suitable for the subject. In this way, by selecting an appropriate presentation time according to the aptitude of the subject, it becomes possible to accurately measure visual acuity and shorten the measurement time.

The optotype section 7 used in this embodiment is, for example, a Landolt ring 16 as shown in FIG.
Displays optotypes corresponding to 12 levels of visual acuity from "1.5" to "1.0", and on the back side, a lamp is provided for each Landolt ring 16, and the interface 2
The light is selectively turned on by a control signal S1 from the control signal S1.

Although the embodiment has been described above, various optotypes can be used without being limited to this embodiment, and the initial value of the first setting value t1, the conversion ratio from t1 to t2, 1 It is of course possible to arbitrarily set the increase/decrease rate of the first set value t1 after the first measurement, the upper and lower limits of the first set value t1, etc. to desired values. In addition, in this embodiment, the initial first set value t1 is constant regardless of the subject, but the interface 2 is configured so that the initial value can be arbitrarily set from the outside depending on, for example, age. You can also attach digital switches, etc. In this way, it is possible to quickly find the first setting value t1 that is most suitable for the subject without proceeding to several steps.

[Effects of the Invention] As explained above, the automatic visual acuity meter according to the present invention calculates the time required for the test subject to input a response, compares that value with a set value, and determines the test subject's performance based on the magnitude of these values. By determining the length of the response time and controlling the presentation time of the next optotype, the next time the optotype presentation time is adjusted to the optimal time according to individual differences, reducing the overall measurement time. This makes it possible to perform accurate visual acuity measurements. Furthermore, if a storage section is provided next to the input switch, it becomes possible to temporarily store input contents and give the subject an opportunity to make corrections.

[Brief explanation of drawings]

The drawings show one embodiment of the automatic visual acuity meter according to the present invention, and FIG. 1 is a block circuit diagram thereof, FIG. 2 is a timing chart of each signal, and FIG. 3 is a front view of an optotype section. It is. Code 1 is the microcomputer, 2 is the interface, 4 is the CPU, 5 is the RAM, 6 is the ROM, 7
1 is an optotype section, 8 is a counter, 9 is a conversion section, 10 is a first comparison section, 11 is an optotype presentation time control section, 12 is a second comparison section, 13 is a storage section, 14 is a response time storage section, 15 is an input switch, and 16 is a Landolt ring.

Claims (1)

[Scope of Claims] 1. An optotype presentation section that presents an optotype to the subject for a first time, a response input section through which the subject inputs a response to the optotype, and the optotype presentation section. a comparison unit that compares a response time from the start of display of the optotype to the time of inputting a response to the response input unit with a second time that is shorter by a certain percentage than the first time, and a comparison in the comparison unit; The first time at which the visual target is presented next is determined according to the result, and the response time is determined at the second time.
and a control unit that increases the next first time if the response time is greater than the second time, and decreases the next first time if the response time is smaller than the second time. automatic vision meter. 2. The automatic visual acuity meter according to claim 1, wherein the response time is determined by counting by a counter. 3. The automatic visual acuity meter according to claim 1, further comprising a storage section for temporarily storing input contents input from the response input section.