JP4125874B2 - Sight table - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a visual acuity table, and more particularly to a visual acuity table used mainly by ophthalmologists, capable of accurately measuring visual functions in daily life.
[0002]
[Prior art]
Usually, visual acuity measurement is mostly performed using an index having a high contrast, but the measurement result by this measurement does not always accurately reflect the visual function of the person in daily life. For example, early-stage cataract patients often show good vision in high-contrast visual acuity tables, but are often experienced to complain of various subjective symptoms such as glare in daily life. is there.
[0003]
Eye dazzle plays an important role in visual impairment due to cataracts, corneal opacities, vitreous opacities, and other conditions. Incident light that enters the eye is confused or diffracted by the turbidity present in the translucent body of the eye, reducing the contrast of the image of interest. Patients with translucent opacity of the eye often complain of difficulty finding medium to low contrast objects in the everyday external environment.
[0004]
However, when visual acuity is measured with high contrast visual acuity letters used in most ophthalmic medical facilities (including university hospitals), relatively good visual acuity is often obtained despite significant subjective complaints. It is done. Nevertheless, in many clinical studies, it has been reported that contrast sensitivity function (hereinafter referred to as “CSF”) and dazzling sensitivity or dazzling disorder are abnormal in cataract patients.
[0005]
As described above, new inspection methods such as contrast sensitivity (CSF) have come to be used in ophthalmology for the purpose of measuring visual function in daily life. It takes time to decipher and it can never be done simply.
[0006]
[Problems to be solved by the invention]
As described above, in the case of a conventional visual chart, it is difficult to accurately measure the visual function in daily life, and in the case of a new inspection method such as CSF, it takes time to decode the inspection result, In addition, since there is a drawback that accurate measurement is not necessarily performed, the present invention provides a visual acuity table that does not have such a defect, that is, can accurately and quickly measure visual function in daily life. The task is to do.
[0007]
[Means for Solving the Problems]
The present invention is a visual acuity table comprising four charts, wherein three of the four charts have high contrast, medium contrast and low contrast, respectively , and the remaining one chart. The above-mentioned problem has been solved by a visual acuity chart characterized in that it has the same high contrast as that of the high-contrast chart and has a black-and-white reversed phase . Preferably, the intermediate contrast is 15% and the low contrast is 3%.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing a visual acuity table according to the present invention. As shown in FIG. 1, the visual acuity table includes four charts. Charts 1 to 3 are visual acuity tables having different contrasts. The contrasts are 90% (high contrast), 15% (medium contrast), and 3% (low contrast), respectively, and the average luminance is constant. . Chart 4 has the same 90% contrast as Chart 1, but is composed of white indicators on a black background in the opposite phase of Chart 1. This chart 4 has an average luminance of about 25 to 30% of charts 1 to 3, and is mainly used for glare detection.
[0009]
In each chart, 13 sets of indicators having different sizes are configured as one set, and level 1 to level 13 are set from a small indicator to a large indicator. Level 1 to level 13 are visual acuity 0.125, 0.16, 0.20, 0.25, 0.32, 0.40, 0.50, 0.63, 0.80, 1.00, 1 .25, 1.60, 2.00.
[0010]
In contrast to many commonly used visual chart indices that change algebraically, the chart of the visual chart according to the present invention is characterized by geometric changes. That is, E-shaped, Landolt's ring and other indices (the illustrated example is E-shaped), and their orientations are changing. The greatest advantage is that the visual acuity difference between the indicators at each level is constant, so that the analysis of the result of the visual acuity test becomes more accurate.
[0011]
Next, a measurement method using the visual acuity table according to the present invention will be described. When using the visual acuity table, if the naked eye visual acuity is below normal, the visual acuity is corrected at a distance by a normal visual acuity measurement method.
[0012]
In general, the measurement is separated from the chart 1 by a predetermined inspection distance (for example, three types (40 cm, 3.0 m, 5.0 m) are set between 40 cm and 5.0 m), and one eye is separated from the right eye. Do. First, answer from the bottom index in which direction the index is pointing. If the subject correctly viewed from the bottom up to the level 9 index (0.80) and could not see the level 10 (1.0), it was once again different from the first level 9 index (0.80). Ask about the indicators. If this can be accurately recognized, the score is 10.5, otherwise it is 10.0. The normal value of Chart 1 is 10.0.
[0013]
Next, the chart 4 is inspected in the same procedure. The measurement of the chart 4 does not need to be performed from the level 1, and may be started from the first and second levels below the measurement result of the chart 1. For example, if the measurement result of chart 1 is level 10, it starts from about level 8. In addition, the normal value of the chart 4 is 10.0 or more.
[0014]
Next, the charts 2 and 3 are measured. Charts 2 and 3 start from the top E index. The method of assigning the scores of the charts 2 and 3 is the same as that of the charts 1 and 4, and the normal values are 9.0 and 6.0 or more, respectively. Therefore, the normal value of the entire chart is 35.0 or more.
[0015]
When normal contrast is used, even if an eye disease such as cataract is present, it is often experienced in daily clinical practice to record visual acuity 1.0 in the early stage. Therefore, the result of Chart 4 is often obtained as compared with Chart 1. This is thought to be because the glare due to cataracts is reduced because both charts have the same 90% contrast but are in an opposite phase state.
[0016]
It is possible to detect the presence of an abnormality in the intermediate light transmitting member, for example, a cataract in a short time. For that purpose, first, starting from the chart 1, it is made to answer which direction the bottom E index is facing. If the answer is correct up to the ninth index (0.80) and wrong at the tenth (1.0), the level is lowered by 1 and the other index of the ninth index (0.80) is asked. If it is wrong, the patient's chart 1 score is 9.5 and the visual acuity is between 0.80 and 1.0. If the answer is correct, it goes up to the 10th level and shows an E index that is not the E index that was wrongly answered earlier.
[0017]
The chart 4 is inspected in the same procedure.
[0018]
FIG. 2 shows the measurement results of subjects with no ophthalmological findings other than refractive errors, and it can be seen that the results vary in each of the charts 1 to 4. Thus, the difference in visual acuity due to the difference in contrast can be understood only by using the visual acuity table according to the present invention.
[0019]
If the score of Chart 1 and the score of Chart 4 are exactly the same, it is considered that there is no abnormality in the intermediate translucent body (see the white circle (healthy person) in FIG. 2). If it is good, the presence of a cataract or the like is suspected (see the black circle in FIG. 2 (initial cataract patient)).
[0020]
【The invention's effect】
The present invention is as described above, and the visual function in daily life can be measured accurately, quickly and easily.
[Brief description of the drawings]
FIG. 1 is a diagram showing a visual acuity table according to the present invention.
FIG. 2 is a diagram showing a relationship between a chart of a visual acuity table and a visual acuity level according to the present invention.

Claims (3)

A visual acuity table comprising four charts, wherein three of the four charts have a high contrast, a medium contrast, and a low contrast, respectively , and the remaining one chart is the high chart. A visual acuity chart characterized by the same high contrast as that of the contrast chart, with black and white anti-phase . The intermediate contrast is 15%, optotypes of claim 1 wherein the low contrast is 3%.   The visual acuity table according to claim 1 or 2, wherein the index changes geometrically.

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