JPS6034376B2 - Visual acuity meter for astigmatism, nearsightedness and farsightedness - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a visual acuity meter for astigmatism, myopia and hyperopia.

Astigmatism is mainly determined by corneal astigmatism and crystalline lens astigmatism.The principal meridians of both often overlap in a cross shape, but form a certain angle.

In corneal astigmatism, the curvature of the vertical meridian is usually strong and the curvature of the horizontal meridian is weak. There are also those who are hereditary and those who are acquired. The present invention discovered such a phenomenon, named it accommodative astigmatism, and completed the present invention. Accommodative astigmatism of the crystalline lens, like corneal astigmatism, acts mostly on the vertical meridian and weakly on the horizontal meridian. This phenomenon is thought to be due to the long-standing influence of gravity, which allows the ciliary muscles to adjust and allow the vertical meridian to move easily. Young people have a strong ability to accommodate, so it is natural that they often have direct astigmatism, and the degree and direction of the principal meridian change with age, leading to an increase in oblique astigmatism.

This is also why lens astigmatism appears when people who have developed presbyopia wear contact lenses.

When a non-examiner complains of pain, years of experience have shown that the following has been done: In other words, direct astigmatism has priority over spherical astigmatism and its power is lowered.

For oblique astigmatism, the power is reduced preferentially on the spherical surface (if the spherical surface is negative), and for oblique astigmatism, the power of the astigmatism is CI. 200 to 00D
The reason why it is said that it is okay to straighten the lens vertically or horizontally is due to the accommodative astigmatism of the crystalline lens, and although it looks better, it makes you more tired. The optotype of astigmatism at the far point also changes by changing the posture. When the face is tilted more than 45 degrees toward the right shoulder, the axis of astigmatism usually shifts about 100 degrees clockwise from the examiner's side.

If you tilt it towards your left shoulder, the opposite phenomenon will occur.
In this case as well, the influence of gravity seems to be small when the crystalline lens is in a resting state, which is considered to be due to the influence of gravity. Emmetropia is based on corneal astigmatism, crystalline lens astigmatism, and the balance of the ocular axis and retina. Even in emmetropia, when adjusting the near point, the crystalline lens has accommodative astigmatism, which is usually around C-0.50D before and after the horizontal ball. Most of the time, astigmatism appears, including C-1.00D to C-2.
．． There are also people with 00D or higher.

If you have the following single astigmatism of C-1.00 x 60 and accommodative astigmatism acts on C-0.50 x 180, the axis and power will change as follows: S-0.31: C-0.87
It becomes ×45.

Also, C-1.00×60 and accommodative astigmatism is C-1.00×18.
When it is set to 0, it becomes S-0.50 engineering C-1.00×30. Senile direct astigmatism is strong when you wake up and becomes weaker when you get tired.

In addition, in the case of oblique astigmatism, the spherical surface shifts to the positive direction as the patient gets tired, and the degree of astigmatism increases. Oblique astigmatism shifts from horizontal to vertical direction. Also, in juvenile direct astigmatism, the power is weak when you wake up, and becomes stronger over time (especially when you are near work). In addition, with inverted astigmatism, the spherical surface shifts to a negative direction over time, and the power of astigmatism becomes weak. Oblique astigmatism transforms into a horizontally drawn curvature. It is said that lens astigmatism tends to progress to direct astigmatism rather than oblique astigmatism.

In this case, I think it is the result of a drop in intraocular pressure or the long-term influence of gravity. Experimental example 1 38 year old man Far point power due to fog S + 0.253C - 0.50 x 17
0 visual acuity 1.2 near point astigmatism C-0.50× added to the above power
180 Atropine instillation in the above eyes far point power S + 0.50
3C-0.25×170 Visual acuity 1.2 2nd day after instillation of Atopin Accommodative power recovered to fox far point power due to fog S
+0.25 degrees C-0.50×1701 and near point astigmatism C-1.50×180 3rd day C-1
．． 00×1805th day C-0.75×180 7th day Recovery to original state Example 2 80 year old female RS+3.25 Far point visual acuity 0.8 LS+3.50 Near addition 3.50 Accommodative astigmatism Left and right C- 1.00×180 From the above results, the ciliary muscles work from a point where they can be easily adjusted.

When measuring far-point astigmatism with this situation in mind, extreme vigilance is required for physiological accommodation astigmatism of the crystalline lens, even more so than for nearsightedness and farsightedness.

Therefore, the axis and power of astigmatism should be determined first in a completely cloudy state, and then the measurement of the spherical power should be started. Experimental example 3
A 26-year-old female who has not used glasses until now, has a far point power of S-4.50, visual acuity of 1.2, and has no near-point astigmatism.Based on the above, it seems that accommodative astigmatism will inevitably appear after many years of accommodation.

However, humans cannot live with only the far point; they naturally need clear vision up to the near point. Improving far point visual acuity will worsen near point visual acuity, and improving near point visual acuity will worsen far point visual acuity, resulting in contradictory results. Normal near point astigmatism is C-0.
If it's 50 or less, there seems to be no problem, but people who work in close fields may need different glasses for close vision. Incidentally, when prescribing bifocal lenses, near-point visual acuity can be improved to some extent by increasing the addition power. Based on the above, the present invention is constructed as follows.

That is, the present invention makes adjustments such that the tension in the vertical meridian increases,
Focusing on accommodative astigmatism, where the horizontal meridian acts small, it has a determination line for the astigmatism power and an axis determination line that can determine the axis of astigmatism in a completely cloudy state, and then the spherical surface, that is, the power of nearsightedness and farsightedness. , a visual acuity measuring device for astigmatism, nearsightedness, and farsightedness, consisting of a rotatably supported far-field power measuring plate and a near-point distance measuring plate provided with a red vertical line and a green horizontal line.

An example of the present invention is shown.

In Fig. 1, 1 is a far power measuring board, 2 is a near point distance measuring board, and the far power measuring board 1 is symmetrical between the vertical and horizontal astigmatic power determining lines 3 and 4, and the vertical astigmatic power determining line 3. The one shown in Fig. 2 has diagonal lines 5, 5 and 6, 6 for determining the axis.
is formed and displayed on the measuring plate, and is mounted on the rotary body 9, which may be attached to the body 10 and rotated as shown in FIG. The near point distance measuring plate 2 is constructed by combining several red side lines 11 and edge side lines 12. Next, the measurement method will be explained.

{1} Measurement of pupil distance S+3 even in myopic eyes that are kept in a foggy state for more than 15 minutes
．． 00 is worn to remove tension from the crystalline lens and ciliary body and enter a resting state.

Next, place a measuring device 3 m in front of your eyes, shield your left eye, and gradually release your coriander eye from the fog until you can see the 10x mark below the auxiliary optotype. (However, if the astigmatism is severe, only the 10x line in one direction can be confirmed.) Next, gradually open the auxiliary optotype until the 10x line above the target can be confirmed, and from that power the SI. Minus 00D. By subtracting it, 10x becomes more visible.

In this state, the patient will be shown radiation therapy to check for astigmatism. If you can't see the line in one direction on the upper side even if you open the lens until you can see the line in one direction on the 10x on the lower side and then the line in one direction on the upper 10x can be seen (SI.00D), consider that you have amblyopia. Measure.

'21 Measuring the astigmatic axis using a rotating optotype. Align the decision line 3 in Figure 1 with the black line that was previously examined using radiation. In the case of Figure 2, the red side line 10 and the edge line 11
Open your eyes and compare them while blinking so that they look the same.

The same visible area is shown on the window as the axis of astigmatism. (3
'Measuring the power of astigmatism Compare with lines 3 and 4 in Figure 1 and add negative cylindrical lenses until they look the same.

[4} Measurement of spherical power Furthermore, the spherical power at 3 m in front of the eye is determined by the red-green test after gradually releasing from the cloud.

SO to focus to infinity due to the distance in front of the eye &h
．． 3 I have to make the fox minus.

SO at 4m in front of me. All you have to do is subtract the 2 mark. Do the same thing for the left eye as for the right eye.

The oblique test is performed with a miniature lamp. Using the measuring instrument of the present invention, visual acuity measurements for astigmatism, myopia, and hyperopia can be performed extremely accurately and easily.

[Brief explanation of the drawing]

Fig. 1 is a front view showing the visual acuity measuring device for astigmatism, myopia, and hyperopia according to the present invention, Fig. 2 is a perspective view of the device installed on a rotating body, and Fig. 3
The figure is a side view of the device attached to the fuselage. 1... Distance power measurement board, 2... Near point distance measurement board, 3, 4... Astigmatism power determination line, 5,
6... Axis determination diagonal line, 11... Red side line, 1
2...Line lateral line. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 Focusing on accommodative astigmatism, in which the tension in the vertical meridian increases and the horizontal meridian acts less when the adjustment is made, the axis of astigmatism is determined in a completely cloudy state, and then the spherical surface, that is, the power of nearsightedness and farsightedness, is determined by law. Astigmatism, nearsightedness and farsightedness consisting of a rotatably supported distance power measuring plate with a line for determining the astigmatic power and a line for determining the axis, and a near point distance measuring plate with a vertical line in the red and a horizontal line in the green. visual acuity measurement device.