JPS5899945A - Apparatus for measuring astigmia - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for measuring the astigmatic state of an eye to be examined, particularly the astigmatic axis direction (astigmatism angle), and furthermore, the degree of astigmatism.

Generally, the eye to be examined has a toric surface that is symmetrical about the astigmatic axis.
In other words, it can be regarded as a surface with different curvatures in the astigmatic axis direction and in the direction orthogonal thereto.

It is important for ophthalmologists and opticians to measure the astigmatic state of the subject's eye. Conventionally, to measure the astigmatism of the subject's eye, a so-called astigmatism marker, which has a number of radial lines as an indicator, was used.The patient was made aware of which line would look best, and a cylindrical lens was inserted so that all the lines could be seen equally. The following methods have been adopted.

However, this measurement has the disadvantage that it is time consuming and has poor accuracy. The object of the present invention is to provide an astigmatism measuring device rfIt that solves this drawback.

The characteristics of the present invention are as follows: First, in astigmatism axis direction measurement, the pupil of the eye to be examined is illuminated with two separate light beams from the same light source, a slit index is projected onto the fundus through the illuminated pupil, and the slit is This is to determine whether the slit index matches the astigmatism axis direction based on the presence or absence of image separation.

In other words, if the slit index does not have the same pressure in the astigmatic axis direction, the slit image will be split due to the refractive power in the circumferential direction perpendicular to the meridian, and if it matches the astigmatic axis direction, the slit image will not be split, and the astigmatic axis direction can be detected. It is characterized by

Here, as an example, a pair of cylindrical lenses having the same positive and negative refractive powers is provided in the optical path, which is not essential for the measurement in the astigmatic axis direction but has an important effect on the next astigmatism measurement. It is practical to use this pair of cylindrical lenses during the measurement of the astigmatic axis direction, so that the generatrix direction of both lenses is perpendicular to the longitudinal direction of the slit or aligned with the longitudinal direction of the slit. A matched cylindrical lens with the same positive and negative refractive powers has no refractive power in each meridian direction and is equivalent to a parallel plate. However, when this pair of cylindrical lenses are rotated relative to each other, optically the two The apparent composite direction of the generatrix direction (
The maximum refractive power is generated in the direction rotated by sagittal degrees from the bisector direction.

The slit index and the above-mentioned pair of cylindrical lenses are rotated together around the optical axis so that the longitudinal direction of the slit matches the astigmatism axis direction, and the astigmatism axis direction is detected by detecting that the slit image is no longer split. .

In other words, this is based on the fact that if the slit index is in the axial direction (astigmatism axis direction) for the eye to be examined with a toric lens, the slit image will not be split due to the symmetry of the lens. When measuring the degree of astigmatism, the slit index and a pair of cylindrical lenses are initially integrated and measured from the astigmatic axis direction.
After rotating, the pair of cylindrical lenses are rotated at equal angles, keeping the apparent synthetic generatrix direction constant.
By rotating the cylindrical lens symmetrically and applying pressure so that it has the same curvature in the astigmatic axis direction and the direction orthogonal to this, that is, by detecting that the slit image is no longer split again, the rotation angle of the cylindrical lens can be adjusted. The purpose of this method is to detect the degree of astigmatism.

In other words, the cylindrical refractive power in the astigmatic axis direction changes due to the relative rotation of the pair of cylindrical lenses, and the refractive power in the astigmatic axis direction becomes equal to the refractive power in the direction perpendicular to this, that is. This method uses the fact that the slit image does not split even if the slit index is not in the astigmatic axis direction in an equivalent spherical lens system.

Hereinafter, the present invention will be described in detail using the accompanying drawings.

FIG. 1 shows a first embodiment of the present invention. A light source 1 irradiates a diffuser plate 2, and the diffused light from the diffuser plate 2 irradiates a slit plate 6. In FIG. Slit opening 6 of slit plate 6
The light beam from a is directed by the lens 14 between two circular circles A3a+ that are symmetrical about the optical axis X as shown in FIG. 2 (4).
The light reaches the diaphragm 9 plate 3 having the aperture 3b and is once imaged behind the cylindrical lenses 4 and 5 via the cylindrical lenses 4 and 5, which will be described later, and is then recondensed onto the fundus through the rear lens 7 and the eye EK to be examined.

That is, the image of the slit opening 6a is projected onto the fundus of the eye to be examined.

Further, the aperture plate 3 is maintained in a conjugate relationship with the pupil El) of the eye E to be examined by the lens 7.

The cylindrical lenses 4 and 5 have the same positive and negative refractive powers and are initially provided in the vicinity of the pupil conjugate point of the eye to be examined, with their generatrix direction T parallel to or perpendicular to the slit longitudinal direction S of the slit plate 6. That is, the generatrix directions T of the cylindrical lenses 4 and 5 coincide, and the combined refractive power is zero. The cylindrical lenses 4.5 are rotated integrally around the optical axis 2 without KFi refractive power in the case of astigmatism angle measurement, and rotated relative to each other in the case of astigmatism measurement.

That is, as shown in FIG. 2, the diaphragm plate 3, the cylindrical lenses 4 and 5, and the slit plate 6 can rotate integrally around the optical axis 2. Slit longitudinal direction S viewed from the optical axis X direction and cylindrical lenses 4 and 5
The relationship between the common generatrix direction T is shown in FIG. 2).

If the eye to be examined has astigmatism, the slit image will not shift in the meridian direction of the astigmatism axis in a direction perpendicular to the meridian 11Kfl, that is, in the circumferential direction, but in the meridian direction other than the astigmatism axis direction, the slit image will not shift in the meridian direction. This results in shifting the slit image in the circumferential direction.

In other words, the direction of the astigmatism axis of the subject's eye is, for example, the vertical direction (
! If it is tilted θ from
), if the slit index is initially set in a meridian direction other than the astigmatic axis direction, for example, in the vertical direction, the slit image appears to be split.

Here, when the diaphragm plate 3, the iris/trical lenses 4 and 5, and the slit plate 6 are integrally rotated by θ around the optical axis 2,
By matching the astigmatic axis direction U, the slit images match without being split, as shown in FIG. 3 [F])K. From this, the initial state, for example, the aperture plate 3 from the top and bottom directions. Cylindrical raise 4,5. It is understood that the astigmatic axis direction U is detected from the integral rotation angle of the slit plate 6.

In addition, in the case of the above-mentioned measurement of the astigmatic axis direction U, the cylindrical lens 4.5 does not have any refractive power even when rotated by Ifi, and is equivalent to not providing the cylindrical lens 4.5 in the optical path. For example, it may be installed outside the optical path, considering the measurement in the axial direction U, so that it is not installed in the optical path.

Next, when measuring the degree of astigmatism, the entire optical system, that is, the aperture plate 3. Cylindrical lens 4.5. The slit plate 6 is integrally rotated by 45° clockwise or counterclockwise around the optical axis X.

As described below, in a system of a pair of cylindrical lenses 4, 5 that are rotated relatively, the apparent synthetic direction T of the generatrix direction (cylindrical lenses 4, 5
It is related to having the maximum refractive power in a direction rotated by 1° from the 2-gon line direction).

In other words, the optical system is initially rotated from the astigmatic axis,
After that, the aperture plate 3. When the slit plate 6 is held still and the cylindrical lenses 4 and 5 are rotated equiangularly and symmetrically by a certain angle so as to keep the composite axis in a predetermined direction, the refractive power in the astigmatism axis direction U changes, and the astigmatism axis direction U and astigmatism change. The different curvatures in the direction perpendicular to the axis appear to be the same.

That is, the system changes from a cylindrical system to a spherical system according to the degree of astigmatism of the eye to be examined.

FIG. 4 is an overall diagram of the astigmatism measurement system. When the entire optical system is initially rotated by 4 degrees from the astigmatic axis direction, the generatrix directions of the cylindrical lenses 4 and 5 coincide, and there is no optical effect. However, the slit index is rotated by a wide angle from the astigmatic axis direction, and the composite system of the eye to be examined and the cylindrical force relais/lens 4 and 5 is still a toric system, so the slit image is split as shown in Figure 6 (a). do.

Here, the cylindrical lenses 4 and 5 are symmetrically rotated at equal angles as shown in FIG. Cylindrical lenses 4, 5tjAs shown in the fifth garden (4), they are a pair of cylindrical/trical lenses, one concave and one convex, with refractive powers of −F and F, respectively, and are arranged equally around the optical axis X. By rotating the angle symmetrically, Figure 5 (B)
As shown in , when the included angle in each generatrix direction is 5,
The system is optically equivalent to a spherical lens with a refractive power of -F sin γ and a cylindrical lens with a refractive power of 2F sin r~.

Here, the axis of the composite cylindrical lens is from the direction T0 of the cylindrical lens 4,502 equisector.

It is in the rotated direction, that is, in the astigmatic axis direction U.

In addition, for the two cylindrical lens system, F”
Technical 0ptics Volume 1 No. 312
For more information on buttons 314 to 314.

When the silicate/trical lenses 4 and 5 are mutually rotated,
At a certain rotational position, the slits g1 match without splitting as shown in FIG. 6(6). This is because the degree of astigmatism due to the synthetic cylindrical lens cancels out the degree of astigmatism of the eye to be examined. That is, in this state, the toric lens is converted into a spherical lens.The degree of astigmatism of the eye to be examined is determined from the rotation angle of this mutual rotation.

FIG. 7 shows a second embodiment of the invention. Here, lens 14. Cylindrical lens 4.5 Vi is arranged similarly to the first embodiment. In this embodiment, as shown in FIG. 8, the beam is separated into two beams by wedge prisms 9m and 9b.

Here the sleeve) 6m longitudinal Fi Hou prism 9a,
It matches the tangential direction of 9b.

The aperture plate 8 has a unique circular aperture centered on the optical axis 2, unlike that of the first embodiment. The aperture of the diaphragm plate 8, which forms an image on the pupil formation of the subject's eye through the lens 15, 14, 7, is separated by wedge prisms 9a and 9b, as shown in FIG.

That is, the light beam passing through the wedge prism 9a passes through the upper half of the sleeve 6a and reaches the fundus of the eye via the aperture 8a above the pupil. On the other hand, the bundle passing through the wedge prism 9b is S! Jt6m
It passes through the lower half of the eye and reaches the fundus of the eye via the aperture 41II8b above the pupil.

In the meridian direction where the longitudinal direction of the slit does not coincide with the astigmatic axis direction, the slit image is split as shown in FIG. 10 (3). In other words, each half of the image is one half of the sleeve in the first embodiment. This embodiment has better discrimination accuracy than the first embodiment.

- This is because, considering a system in which the slit width is split by half in this embodiment, in the first embodiment, the slit image only becomes thicker and is not split.

Here, the entire optical system, that is, the aperture plate 8. Cylindrical lenses 4, 5.41 Prisms 9A, 9B.

When the slit plate 6 is rotated integrally by one rotation of the optical axis 2 and the slit direction coincides with the astigmatic axis direction, the slit image no longer undergoes tin lift as shown in FIG. 10 CB). The astigmatic axis direction U is detected by the rotation angle of the entire optical system.Next, in order to measure the degree of astigmatism, the entire optical system is rotated clockwise or counterclockwise around the optical axis 2.

Rotation 0 Figure 11 shows a system for measuring the degree of astigmatism 0 When the entire optical system is rotated, it deviates from the astigmatism axis direction U, so it is toss blit as shown in Figure F1a112. In this state, the generatrix directions of the cylindrical lenses 4 and 5 match. After that, the aperture plate 8. Wedge prisms 9a, 9b,
By keeping the slit plate 6 stationary and rotating the cylindrical lenses 4 and 5 symmetrically by equal angles without changing the synthetic axis direction, as described in the first embodiment, the degree of astigmatism of the eye to be examined is compensated. The slit image is at the position shown in Figure 12)
As shown in K, there will be no splitting. The degree of astigmatism can be determined from the 4°50 rotation angle of the cylindrical lens up to this state.

In the present invention, it has been explained that the generatrix direction T of the cylindrical lens is initially perpendicular to the slit longitudinal direction S or coincident with the slit longitudinal direction d, but this is to maximize the split amount when measuring the degree of astigmatism. Basically, any direction may be used as long as the generatrix directions match.

That is, even if the angle of the generatrix direction T of the cylindrical lenses 4 and 5 is arbitrarily set with respect to the slit longitudinal direction S, for the measurement of the astigmatic axis direction U, the slit longitudinal direction S is simply made to match the astigmatic axis direction U. For astigmatism measurement, the cylindrical lenses 4 and 5 may initially be rotated by 45 degrees from the astigmatism axis direction U.

Furthermore, although the present invention has been described above assuming that the entire optical system is rotated, the cylindrical lenses 4 and 5 may be stationary when measuring the degree of astigmatism.

J The cylindrical lenses 4 and 5 may be moved as one unit, or each may be moved separately.

Furthermore, as shown in FIG. 13, by setting a well-known image rotator 10 in the optical path and rotating it around the optical axis 2, the slit plate, aperture plate, etc. can be fixed.

In other words, when measuring the astigmatic axis, simply use the image rotator 1.
0' and detect the position where the slit image no longer splits.0 Also, when measuring the degree of astigmatism, rotate the image rotator 10 by 22.5''', and then combine the cylindrical lenses 4 and 5. What is necessary is to rotate the axis symmetrically by equal angles without moving the shaft, and then detect the rotation angle until the position where the slit image no longer splits.

The image rotator can be similarly applied to the embodiment using the wedge prism shown in FIG.

By the way, in the above description, two cylindrical lenses with equal positive and negative refractive powers have been mentioned, but combinations of other cylindrical lenses are also possible. For example, as shown in Fig. 14, a new cylindrical lens with twice the refractive power can be added to form a total of three lenses. In this case, the refractive power of the entire system in the astigmatic axis direction changes with the rotation angle. On the other hand, it is possible to convert from a sin change to an ωS change, and it is possible to prevent a sudden change in refractive power in the initial state of rotation.

In Fig. 14, cylindrical lens 13 Fill, 12
It has twice the refractive power compared to 11.12Fi, and has the same refractive power for both positive and negative directions. Cylindrical lens 13 can be either positive or negative.For example, cylindrical lens 1.1.1s1
3#i have refractive powers of F, -F, and 2F, respectively. Cylindrical Re/Z 11. lλ11 out of 13 and B.

Or 12,! = 13 are set so that the generatrix directions match each other and are orthogonal to the generatrix directions of the remaining cylindrical lenses.

In this state, the cylindrical lens 11. ig13
The system consisting of light has no cylindrical refractive power.

The slit longitudinal direction S and the diaphragm aperture direction or the wedge direction of the wedge prism are inclined at 45 degrees with respect to the generatrix direction of the cylindrical lens 11, for example.

FIG. 15 (■) is a diagram of a measurement system in the astigmatic axis direction.

7. Rindrical Lens 11.12.13. Aperture plate 3. Does the slit plate 6 rotate around the optical axis X as a unit?
The image is rotated by an image rotator IO.

If the slit longitudinal direction S is not in the astigmatic axis direction U, the slit image will be split, but if it is aligned with the astigmatic axis direction U, the slit image will not be split. From this, the astigmatic axis direction U is detected.

@Figure 15) (This is a diagram of the QFi astigmatism measurement system. First, from the state where the astigmatism axis direction U is detected, as shown in Figure 15 CB), the cylindrical lenses 11°, 12, 13.
Aperture plate 3. The slit plate 6 is rotated integrally by 4 degrees, or the image is rotated by 45 degrees by an image rotator. At this time, the slit longitudinal direction S deviates from the astigmatism axis direction U, and the entire system of cylindrical lenses 11, 12, and 13 does not have cylindrical refractive power and does not compensate for the astigmatism of the eye E to be examined. In the step, the slit image is split.

After that, as shown in Fig. 15 (O), the cylindrical lens 13, aperture plate 3, and slit plate 6 are fixed, and the cylindrical lenses 11 and 12 are rotated symmetrically by an equal angle α so as not to change the composite axis. to change the refractive power in the astigmatic axis direction U.

When the refractive power in the astigmatic axis direction U matches the refractive power in the direction perpendicular to the astigmatic axis direction U, the entire system including the eye to be examined becomes equivalent to a spherical optical system, and in this state, the slit image will no longer be split again. .

Incidentally, the refractive power given to the astigmatic axis direction H of the cylindrical lenses 11 and 12 is 2Fsiaγ, but γ+2α
=90°, it becomes 2FCt)52α, which is a cosine change with respect to the relative rotation angle a. If r is small, 2Fsi
The change in nγ is large, but if a is small, the refractive power 2FCO
Since the change in 32α can be made small, the initial change is small, which is convenient for measurement. Note that the present invention is not limited to this embodiment, and other combinations of cylindrical lenses are also possible.

The above explanation is based on the subject's own response, and is about subjective measurement, but the slit a reflected on the fundus of the subject's eye is measured with a photodetector via a light splitting member inserted into the optical path. Therefore, it can also be applied to objective astigmatism measurement.

As described above, according to the present invention, it is possible to provide an astigmatism measurement device that is extremely useful as an ophthalmological instrument because the astigmatism axis direction and degree of astigmatism can be measured with a simple configuration by capturing the changes from the split of the slit image to the "coincidence" with high precision. .

[Brief explanation of the drawing]

Fig. 1 is a diagram of the astigmatism axis direction measurement system according to the first embodiment of the present invention, the second toss is a perspective view of the optical system rotating section, Fig. 2 (03) is a diagram viewed from the optical axis direction, and Fig. 3 (4) is a slit image in the meridian direction other than the astigmatic axis direction, Figure 3) is a slit image in the astigmatic axis direction, Figure 4 is a diagram of the astigmatism measurement system, and Figure 5 (4) (
8) is a perspective view of the relative rotation of a pair of cylindrical/trical lenses, and an overall view as seen from the optical axis direction; Fig. 6 (4) is a slit image with the astigmatism of the subject's eye not compensated; Fig. (
B) is a slit image with the astigmatism of the subject's eye compensated;
FIG. 7 is a diagram of the astigmatism axis direction measurement system according to the second embodiment of the present invention.
Figure 8 is a perspective view of the Hou prism and slit plate, Figure 9 is an explanatory diagram of the aperture opening in the pupil, Figure 10 (4) is a slit image in the meridian direction other than the direction of the astigmatic ring, and Slit image in the astigmatism axis direction, 1st, 2nd = ''' Diagram of the pharynx diopter measurement system, Fig. 12 (4) is a slit image in a state where the astigmatism of the eye to be examined is not compensated, Fig. 12 [F]) 13 is a diagram of another embodiment of the present invention using an image rotator, FIG. 14 is a diagram of another embodiment of the cylindrical lens, and FIG. Diagram (A
) ω) (0 is the astigmatic axial view in the example of FIG. 14, an explanatory diagram of astigmatism measurement, in the figure, Etj is the eye to be examined, Ep is the pupil, 2 is the optical axis, S is the slit longitudinal direction, T is the serial direction. /The generatrix direction of the trical lens, To is the synthetic generatrix direction of the cylindrical lens, U is the astigmatic axis direction, 1 is the light source, 2 is the diffuser plate, 3-digit aperture plate, 3a, 3b are the aperture aperture, 4° 8b is the pupil Separated aperture aperture, 9m. 9b is a wedge prism, 10 is an image rotator, 11,
Reference numerals 12 and 13 are the AF, -F, and 2F horizontal IJ/)'IJ cal lenses, and 14 and 15U lenses. Applicant Canon Co., Ltd.

Claims (1)

[Claims] 1. In an apparatus that measures astigmatism from the image state in each direction of the slit image projected onto the fundus of the eye to be examined, an aperture f image separated in the longitudinal direction of the slit on the pupil of the eye to be examined is at least two cylindrical lenses that are relatively rotatable in a plane perpendicular to the optical axis; and a rotation means that rotates the slit image around the optical axis. measuring device. 2. The astigmatism measuring device according to claim 1, wherein the rotating means rotates the entire means for forming the separated aperture images. 3. The astigmatism measuring device according to claim 1, wherein the rotation means is an image rotation optical means. 4. A patent claim in which the means for forming the separated aperture image comprises a stone aperture means having two apertures symmetrical with respect to the optical axis, and an imaging means for focusing the apertures on the pupil of the eye to be examined. The astigmatism measuring device according to item 1. 5. The means for forming the separated aperture image comprises an aperture means having an aperture on the optical axis, a wedge prism, and an imaging means for forming an image of the aperture on the pupil of the eye to be examined. The astigmatism measuring device according to item 1. 6. The astigmatism measuring device according to claim 1, wherein the cylindrical lens is two cylindrical lenses having the same positive and negative refractive powers. 7. The synthetic generatrix direction of the cylindrical lens is orthogonal to the longitudinal direction of the slit. The astigmatism measuring device according to claim 6, wherein the astigmatism measuring device is in a direction in which the astigmatism is measured. 8. The astigmatism measuring device according to claim 7, wherein the cylindrical lens is rotatable equiangularly and symmetrically while maintaining the composite axis. 9. The astigmatism measuring device according to claim 8, wherein the equiangularly symmetrical rotation is performed after the longitudinal direction of the slit is rotated by 45 degrees from the astigmatism axis direction of the eye to be examined. 10. The cylindrical lens has the same positive and negative refractive powers. The astigmatism measuring device according to claim 1, which comprises a second cylindrical lens and a third cylindrical lens having twice the refractive power. 11. The longitudinal direction of the slit is the first. The astigmatism measuring device according to claim 10, which is provided by being rotated by 45 rotations with respect to the generatrix direction of any one of the a-th and third cylindrical lenses. 12. Said No. 1. 12. The astigmatism measuring device according to claim 11, wherein the generatrix direction of the third cylindrical lens coincides with the generatrix direction of the second cylindrical lens and is orthogonal to the generatrix direction of the second cylindrical lens. 13. Fix the third cylindrical lens, and
．． 13. The astigmatism measuring device according to claim 12, wherein the second cylindrical lens can be rotated equiangularly and symmetrically while maintaining the composite axis. 14. The astigmatism measuring device according to claim 13, wherein the equiangularly symmetrical rotation is performed after the longitudinal direction of the slit has been rotated from the astigmatism axis direction of the eye to be examined.