JP3299782B2 - Optotype presenting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optotype presenting apparatus.

[0002]

2. Description of the Related Art As an optotype presenting apparatus used to inspect a visual acuity value, an apparatus for presenting an optotype such as a Landolt ring is known. For example, in the Landolt ring optotype, the direction of the cut line of the ring is made to respond to the subject, but in the case of the optotype having such a direction, the direction of the optotype is randomly arranged in order that the subject does not memorize the configuration of the optotype arrangement. Is done. The arrangement of optotypes in the conventional optotype presenting apparatus focuses solely on the randomness of the direction, and does not take any other consideration into account.

[0003]

However, in the case of a target having directionality, such as a Landolt's ring, whether or not a certain target can be visually recognized may be affected by the astigmatic axis angle of the subject's eye. . Therefore, a different result may be obtained depending on the presented target or the astigmatic axis direction in the conventional device. This is specifically shown as follows. FIG. 1 shows a configuration example of a conventional visual acuity table. The visual target is a Landolt ring having a cut in one of four directions (up, down, left, and right), and 3 to 5 visual targets are arranged in each visual acuity value sequence. . In this example, in the range of visual acuity of 1.2 to 2.0, the number of visual targets having a cut in the horizontal direction is 3, and the number of visual targets in the vertical direction is 2. By the way, a general criterion for determining that a visual acuity value at a certain stage is two or more when the number of targets at the same stage is three.
In the case of 5, the correct answer number of 3 or more is obtained. However, in the case of using this visual acuity table, there is a possibility that even the eye to be examined having the same astigmatic power has a higher visual acuity than that of the direct astigmatism. large.

In general, when measuring visual acuity, it is not only time-consuming to inspect all targets in order from one having a small visual acuity value, but also the test subject becomes tired and cannot perform the test accurately. Therefore, only the rightmost or leftmost optotype target row (often the right eye in one row and the left eye in the other row) is read in order from the top, and the visual acuity value that could not be read for the first time is used. The target is read in order to check whether there is a correct answer number to recognize as a visual acuity value, and if there is a visual acuity value of one step larger, if not, the visual target of a visual level of one step smaller is read in order, and this is repeated. And the highest visual acuity is used as the visual acuity value of the subject. In the case of such an inspection method, if the breaks in the rightmost (or leftmost) optotype continue horizontally or vertically,
There is a disadvantage that an error of two or more steps may occur depending on the astigmatic axis angle. The present invention has been devised in view of the above-described drawbacks, and does not store the target array in the subject, has a small measurement error due to astigmatism, and provides an accurate visual acuity measurement in a short time. It is an object of the present invention to provide a presentation device.

[0005]

To achieve the above object, the present invention is characterized by having the following configuration. (1) In the horizontal direction , have a left or right cut,
In an optotype presenting apparatus which has a Landolt ring optotype having an upper or lower cut in the vertical direction and selectively presents the Landolt ring optotype to the subject, the optotype having a different visual acuity value or a cut is applied to the subject. A program for sequentially presenting a test subject's response in accordance with the correctness of the tester, wherein a test subject correctly answers a majority of three or more predetermined odd-numbered visual targets presented at a certain visual acuity level. has a program that determines whether there is the visual acuity value by whether the whether the cut in the horizontal direction
The number of optotypes to have (N) and the number of optotypes with vertical cuts
The difference between the numbers (M) is 1 for each visual acuity value, and
When NM = 1 at the stage of the visual acuity value,
At the force value stage, the number of targets with vertical cuts is
The number of optotypes having a break in the direction is increased by one, and M-
When N = 1, the horizontal direction at the level of the visual acuity value above and below
The number of optotypes with a break in the direction
And a target selection program for selecting a presented target so as to increase the number of targets by one .

[0006]

[0007]

Embodiment 1 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a perspective view showing an optotype presenting unit.
FIG. 3 is a perspective view showing an optotype operating section for operating an optotype presenting section, in which the entire visual acuity value optotype is arranged in the same plane. An optotype selecting switch 2 is disposed on the optotype operating section 1, and a mini pattern of optotypes is attached to each of the selection switches so as to correspond to the optotype array of the optotype presenting section. Reference numerals 3 and 4 denote switches for inputting the correctness of the response of the subject, and press the correct answer switch 3 if correct, and press the wrong answer switch 4 if incorrect. Reference numeral 5 denotes a program execution switch for presenting optotypes according to the programmed optotype presentation order, and 6 denotes a measurement end switch. The optotype operating unit 1 has a light emitting window 7 for transmission.

The optotype presenting section 8 is provided with a light receiving window 9 for receiving a signal from the transmitting light emitting window 7. In the optotype presenting section 8, a large number of optotypes are arranged based on the arrangement principle as described later, and individual illumination light sources are arranged at the rear of each optotype, and the target is selected by turning on the illumination light source selectively. Presents the target to be read to the person. The principle of arrangement of the optotypes in the optotype presenting section is shown below. The following table shows the relationship between the direction of the astigmatic axis of the myopic eye and the target that is easy to determine (and difficult to determine).

[Table 1] Therefore, different types of optotypes are always arranged in the up, down, left, and right directions of a certain optotype, and all four types of optotypes are included in the optotype group at each visual acuity value (excluding the visual acuity value stage consisting of three optotypes). Marks are included.

The four types of optotypes arranged are arranged almost equally with respect to the total number of optotypes and the number of optotypes in each row. Therefore, it is not easy to read or difficult to read only by a certain type of astigmatism.
The same applies to the case of dividing into two types of horizontal and vertical in the direction of the cut. Of the five optotypes at each visual acuity value, the total number of optotypes with horizontal (or vertical) cuts is 2, 3,
, 2, 3..., The case where the astigmatism or the astigmatism is easier to read is not continuous, and the error due to the astigmatism can be suppressed within one stage.
When the cuts are divided into two types, horizontal and vertical, the optotypes at both ends are alternated from the top and in opposite directions at both ends, so that certain types of astigmatic eyes are easy to read. Nothing.

FIG. 4 is a functional block diagram for explaining a control system of the present apparatus. The switch signal of the optotype operating unit 1 is processed by the signal processing circuit 10 inside the optotype operating unit and is input to the optotype operation control unit 11. The optotype operation control section 11 converts a signal relating to the optotype selection and the correctness of the response to be described later into an infrared pulse signal via the transmission light emitting section 12 and converts the signal into an infrared pulse signal.
Send to 3. The signal received by the light receiving unit 13 is processed by the signal processing circuit 14 and then input to the optotype presenting control unit 15. The optotype presenting control unit 15 has an optotype presenting program described later, and stores a correct / incorrect signal of a response to the presented optotype. The optotype presenting control unit 15 turns on or off the lamp 17 via the lamp driving circuit 16.

The operation of the visual acuity testing apparatus having the above configuration will be described. When an arbitrary optotype selecting switch 1 is pressed by the examiner, the switch signal is transmitted to the light receiving section 13 of the optotype presenting section via the transmitting light emitting section 12 or the like. The signal received by the light receiving unit 13 turns on the corresponding lamp 17 via the optotype presenting control unit 15, the lamp driving circuit 16, and the like, and presents the optotype to the subject. FIG. 5 shows this state.
The correct / incorrect signal of the subject's response is similarly transmitted to the optotype presenting control unit 15. When selecting an optotype based on the examiner's own judgment, the correctness / incorrectness of the response of the examinee is input to the correct answer switch 3 or the incorrect answer switch 4 based on the verbal response of the examinee, and the optotype is selected. Presented sequentially. When the examiner determines that the highest visual acuity has been obtained, he presses the measurement end switch 6. All the optotypes for which the correct answer switch has been pressed are presented (simultaneous presses for which the incorrect answer switch has been pressed may blink). Based on the signal of the measurement end switch 6, the optotype presenting control unit 15 which stores the signal of the correct / incorrect switch presents all the optotypes for which the correct answer switch 3 is pressed.

Next, a case where a target is presented according to a programmed procedure will be described. The examiner sequentially presses the program execution switch 5 and the optional target selection switch 2. 6 and 7 show the procedure when the response to the target presented first is correct and the correct answer switch 3 is pressed. On the diagram,
〇 indicates that the response was correct, X indicates that the response was incorrect, and arrows indicate the lighting order. If the first response is correct, the next target immediately below (the target at the stage with a high visual acuity value) is presented, and thereafter the target is immediately lowered until the wrong answer switch 4 is pressed or the target disappears. Is turned on. When the wrong answer switch 4 is pressed, the rightmost optotype of the optotypes having the same visual acuity value and not yet presented is presented until the presence or absence of the visual acuity at that stage is determined. The optotype on the left side is sequentially turned on regardless of the correctness of the response. If three out of five (or two out of three) correct targets of the same stage are obtained, the optotype operation control unit 11 determines that there is visual acuity at that stage. When it is determined that there is a certain level of visual acuity, the rightmost target that has not yet been presented among the one level higher visual acuity values is presented, and when it is determined that there is no certain level of visual acuity, a one level lower visual acuity value The rightmost optotype not yet presented is presented, and the left optotype is sequentially presented until the presence or absence of visual acuity at that stage is determined. The measurement ends when the above operation is repeated and the maximum visual acuity is obtained.

When the optotype operation controller 11 determines that the highest visual acuity is obtained, all optotypes for which the correct answer switch has been pressed are presented. Next, FIG. 8 shows a procedure in a case where the response to the initially presented target is incorrect and the wrong answer switch 4 is pressed. In the case of an incorrect answer, the optotype immediately above the presented optotype is presented, and the optotype immediately above is presented until the correct answer switch 3 is first pressed. When the correct answer switch 3 is pressed for the first time, the procedure is almost the same as described above.

[0014]

The present invention can be applied not only to an apparatus having a configuration in which all visual acuity value indices are arranged on the same plane, but also to an apparatus having a configuration in which an optotype is divided into a plurality of optotype groups and switched and presented. In addition, the present invention can be applied to a control mechanism for presenting an optotype in an optotype presenting apparatus that displays an optotype on a monitor.

[0016]

According to the present invention, most of astigmatism is straight astigmatism or
Is astigmatism, so even if the subject's eye has astigmatism,
The eye to be measured is measured in spite of the difference in the target order shown.
The fluctuation of the visual acuity value is clearly smaller than the conventional one.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a conventional visual acuity table.

FIG. 2 is a perspective view showing an optotype presenting section.

FIG. 3 is a perspective view showing a target operation unit.

FIG. 4 is a functional block diagram illustrating a control system of the apparatus.

FIG. 5 is a perspective view of an optotype presenting section showing a case where a first optotype is presented.

FIG. 6 is an explanatory diagram showing an example of a procedure when a first response is correct.

FIG. 7 is an explanatory diagram showing another example of the procedure when the first response is correct.

FIG. 8 is an explanatory diagram showing an example of a procedure when an initial response is incorrect.

FIG. 9 is a layout diagram of optotypes showing an example when another optotype is used.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 optotype operating section 2 optotype selection switch 3 correct answer switch 4 wrong answer switch 5 program execution switch 6 measurement end switch 7 transmission light emitting window 8 optotype presenting section 9 light receiving window

Claims (1)

(57) [Claims] (1) having a left or right horizontal cut
Or, in an optotype presenting apparatus that has a Landolt ring optotype having an upper or lower vertical cut, and selectively presents the Landolt ring optotype to the subject, the optotypes having different visual acuity values or cuts are examined. Is a program for sequentially presenting according to the correctness of the response of the examinee, and the examinee correctly answers a majority of three or more predetermined odd-numbered targets presented at a certain visual acuity value stage. A program for determining whether or not the visual acuity value exists based on whether or not there is a difference between the number of optotypes having a horizontal cut (N) and the number of optotypes having a vertical cut (M) Is 1 for each visual acuity value, and when NM = 1 at a certain visual acuity value stage, the number of optotypes having vertical cuts at the upper and lower visual acuity values stages is determined by dividing the horizontal Increase the number of optotypes by 1
When N = 1, the presented optotypes are set so that the number of optotypes having a horizontal cut direction is increased by one with respect to the number of vertical optotype targets at the upper and lower visual acuity values. An optotype presenting apparatus, comprising: an optotype selecting program to select.