JPS6113814B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for self-testing the eye to determine astigmatic and spherical corrections.

Until now, self-measurement of astigmatism has been performed by patients looking at a radial array map depicting multiple spoke-like lines. First, the best spherical lens correction is determined. A positive spherical correction is added. Negative cylindrical lens correction is then applied in the 90° direction to the spoke-like striations, which gives the sharp-looking striations extremely close to the desired astigmatic axis. This is repeated by changing the negative cylindrical lens until all the striations appear with similar sharpness.

This method can be modified in ways known to those skilled in the art. Finally, when sufficient astigmatism correction is obtained, other optimization measures such as Jackson's cross cylinder lens correction are introduced. These prior art techniques have several disadvantages. First, the patient must be well instructed by the examiner in locating spokes or other striatal target features that are easily visible. This is extremely difficult to do for a population of patients, as it takes time to educate and get the patient up to speed. Therefore, problems such as visual errors, lack of visual coordination, and lack of basic knowledge and experience (for example, in the case of young children) occur. Furthermore, other errors are particularly likely to occur with low diopter cylindrical lens strengths.

A final disadvantage is that patients may not respond to conventional tests of this type due to preconceptions about the size and shape of the image obtained by their own eyes.
Spherical correction changes the magnification of the eye. Patients who are unaccustomed to this can be confused by the changes in magnification and become confused about what is clear in the optical system. This confusion may lead to an incorrect spherical correction prescription. Similarly, cylindrical corrections result in changes in shape. Patients who are not accustomed to this may be confused by the change in shape and become confused as to which image is clearer to the optical system. This confusion in judgment may result in an incorrect cylinder correction prescription.

The present invention discloses an apparatus for allowing patients to make their own decisions to obtain prescriptions for astigmatic and spherical corrections. The spherical correction optical system is adjusted for a target figure consisting of a single straight line to obtain maximum clarity. In this way, the target line will approximately lie on the visual field plane of the eye's retina. Along the direction of at least one axis that intersects this line, astigmatism correction is performed until the target line appears as sharp as possible, without changing the spherical correction, which moves the target image away from the retinal surface of the eye. It is done without moving. Next, a second target figure consisting of a single straight line is introduced. This straight line is arranged at an angle to the first target straight line, preferably at an angle of 45°. This results in a spherical correction that looks extremely sharp. Then, astigmatism correction is performed along at least one axis that intersects this straight line until the sharpest image is visible, but this is done without changing the spherical correction, and the retina of the eye of the image of the target straight line. It is performed without moving from above. By performing vector analysis of the two astigmatism elements, we can plot the astigmatism correction amount on Cartesian coordinates (recently developed), or use the conventional astigmatism description method using polar coordinates using the cylindrical correction amount and rotation amount. It becomes possible to convert to . Astigmatism measurements can be made by placing two target elements at a 45° angle to each other and plotted. By plotting these elements on a 360° drawing, the amount of cylinder correction and rotation (especially for low refractive power) can be easily determined.
See US Pat. No. 3,822,932, owned by William E. Humphrey, entitled "Ophthalmic Examination Method and Apparatus with Independent Astigmatism and Spherical Correction Inputs." Special target shapes consisting of multiple lines are 4 to 6.
It is formed by a diopter cylindrical smear, which consists of point light sources placed at the three vertices of a triangle. By using a cylinder to blur a point light source perpendicular to the baseline of the triangle, and measuring the astigmatism along at least one of the diagonal measurement elements tilted with respect to the blurring cylinder. As a result, an array consisting of three lines is created. Once the measurement is corrected along one astigmatic component, the three blurred striae will be equally spaced from each other, and the patient will be able to keep the central stria at a constant distance from the other blurred striae. An astigmatism test can be performed.

An object of the present invention is to provide a method and apparatus for determining an astigmatism prescription and a spherical correction prescription by measuring each element of astigmatism and spherical correction independently.

The advantage of performing astigmatism measurements using the device of the invention with two astigmatism elements independent of each other is that the adjustment of one astigmatism element does not affect the other astigmatism element.

Another advantage of the device of the invention is that the adjustment of the spherical correction input can be done independently of the two astigmatic components.
Changing the spherical prescription does not require a corresponding change in the already determined astigmatism correction prescription.

Note that the spherical correction prescription is completely determined unexpectedly in this test. A spherical correction prescription is determined prior to determining the second astigmatic element. Thus, prescriptions from this test occur in a previously unanticipated order. That is, first the patient's first astigmatism correction factor is determined, then the required global correction is determined, and finally the remaining astigmatism correction factors are determined.

It is noteworthy that each linear target requires adjustment of only two optical elements, rather than three. Each linear target requires a spherical correction element and an astigmatism correction element that varies diagonally across the direction of the linear target.

There is no need to adjust for components of astigmatism that vary in directions parallel and perpendicular to the direction of the linear target.
The advantage of each linear target is that only the corresponding variable astigmatic and variable spherical elements need to be adjusted.
Surprisingly, these adjustments can be made in any order.

Another object of the invention is to greatly simplify patient instructions. It is sufficient to individually tell the patient which spherical adjustment or astigmatism adjustment provides the best vision. There is no risk of creating illusions due to changes in shape or size.

A further advantage of the present invention is that it not only simplifies patient instructions but also allows discrete and independent spherical and astigmatic adjustments. Adjustment of the three optical input variables (one spherical input and two astigmatic inputs) can be done independently of any of the rest.

Yet another object of the invention is to provide a simple linear target for the patient to view, which target always consists of at least one straight line.
The advantage of using this linear target is that changing the spherical power does not significantly affect the patient. The sharpness of the target image for the patient changes without being confused by changes in its dimensions. This dimensional change tends to suppress the patient's response to the test.

A further advantage of the linear targets used in the present invention is that they do not undergo confusing shape changes during astigmatism correction. When looking at a straight line,
This is because there is no change to the target other than visibility.

One purpose of the device of the invention is to provide an imaging instrument suitable only for measuring astigmatism consisting of two independent elements. The advantage of the images produced by this device is that while one component of astigmatism is being measured, deviations due to another component of astigmatism are completely blurred out. An image sensitive to only one astigmatic component allows that astigmatic component to be measured accurately without being confused by the other component.

A further advantage of performing astigmatism measurements on independent elements is that plotting of cylindrical power and rotation to determine the final astigmatism correction prescription is easier and more accurate than in the past.

A further advantage of the device of the present invention is that it can be easily assembled into a hand-held device and can be inserted and used in conjunction with existing inspection procedures.

Another purpose of the special cylindrical blurred linear target of the present invention is to link astigmatism measurements to the patient's objective visual clarity. The advantage of using a patient's objective visual sharpness for subjective measurement of astigmatism is that most people have the ability to know objective visual sharpness, and This provides information as to which direction further adjustment is required.

FIG. 1 is a partial diagram of an apparatus that can be used to carry out the method of the invention. First, a target T consisting of a straight line 14 is drawn from left to right. Typically, straight line 14 will have dimensions of one arc minute (which is the largest dimension that the eye can see sharply) or less, no matter how coarse the target is used. Any number of targets T can be made by conventional eye chart manufacturing methods using a projector or other methods. A patient P, illustrated as an eye 15, views the target T through the corrective optics. The spherical correction optical system 16 consisting of a pair of spherical main lenses is adjusted (first time) according to the visibility of the target T, and then the first astigmatism correction consisting of a first pair of astigmatic lenses is performed. The optical system 18 is adjusted, and then the spherical correction optical system 16 (second time) is adjusted, and finally the second astigmatic lens pair 2 is adjusted.
0 adjustment is made. Note that the spherical correction optical system 16 consisting of a pair of spherical lenses is well known. (1967 2
Lewis patented on the 20th of May. Mr. W. Albertez's "Variable refractive power spherical lens consisting of two elements"
U.S. Patent No. 3,305,294 and April 1970
Lewis patented on the 21st. Mr. W. Alberts and William. See U.S. Pat. No. 3,507,565 to E. Humphrey entitled "Variable Power Lens and Lens System." ) Broadly speaking, one of the spherical lens pairs is moved relative to the other depending on the sharpness with which the target T is viewed by the patient. Spherical correction optical system 16
adjusts the spherical refractive power to any positive or negative value by sequentially and continuously moving one lens element relative to the other 16. First and second astigmatism correction optical systems are also known. (See U.S. Pat. No. 3,751,138 to William E. Humphrey, entitled "Variable Anamorphic Lens and Method for Making Lenses," patented August 7, 1973.) These corrective optics 16, 18, Regarding the 20 lens pairs, these optical elements are schematically shown here as one flat glass, but the reader should be aware that each of these lens pairs has extremely complex optical surfaces. should be recognized. These complex optical elements are described in U.S. Patent No. 3,305,294;
It can be known by referring to No. 3507565 and No. 3751138. Broadly speaking, one of the lens pairs of the first astigmatism correction optical system 18 is moved relative to the other depending on the sharpness with which the target T is viewed by the patient. The lens pair of this astigmatism correction optical system 18 changes its refractive power or focal length from positive to negative along one diagonal direction. At the same time, the lens refractive power is adjusted from negative to positive along the remaining diagonal direction. Horizontal movements in opposite directions produce astigmatism correction adjustments in opposite directions. Similarly, one of the lens pairs of the second astigmatism correction optical system 20 is moved relative to the other depending on the sharpness with which the target 8 is viewed by the patient. The second astigmatism correcting optical system 20 changes its refractive power or focal length from positive to negative along the vertical axis. At the same time, with each relative horizontal movement, an adjustment of the optical power from negative to positive along the horizontal axis also takes place. Horizontal relative movements in opposite directions produce astigmatism correction adjustments in opposite directions. In this case, it should be noted that the mechanical devices that can be used for the operation of this embodiment of the invention are already known elsewhere and are sufficient. For example, a device for generating motions of three lens pairs in the same direction and in opposite directions is an "eye examination device" filed with the applicant on June 20, 1973.
No. 3,874,932.

Similarly, it will be explained below that the relative movement of each of the three independent lens pairs allows for respective optical corrections. A mechanism for remotely controlling adjusted spherical correction outputs and astigmatic prescription outputs is disclosed in U.S. Pat. Previously disclosed in No. 3822932.

Before proceeding further with the description of the invention, it is necessary to clarify the main points in the first embodiment depicted in FIGS. 1-5. The astigmatism correction optics 18, 20, which consist of a pair of variable astigmatism lens elements, are of the type that produce orthogonally oriented positive and negative astigmatism lens powers along mutually orthogonal axes. Although the lens elements depicted here are preferred, it is clear that other lenses and optical devices may be used to achieve the same effect. For example, US Pat.
See invention No. 3822932.

Having shown the simple mechanism of the invention, the apparatus for performing an eye self-test of the invention can be understood by first understanding the optical limitations associated with astigmatism. First of all, it should be emphasized why a straight line target, preferably consisting of a single straight line or at least a plurality of parallel straight lines, is used. Referring to FIG. 1, a single straight line 14 is shown with an exaggerated vertical width. Also shown is an imaginary line 24 drawn as a dashed line extending horizontally. The focus of these straight lines on the hypothetically and diagrammatically shown retinal plane of patient P's eye 15 will help to understand the function of the astigmatism correcting optical system 18 and 20 consisting of the variable astigmatism lens pair in the present invention. Dew. It is assumed that the eye 15 of the patient P has a certain amount of astigmatic aberration. Due to the nature of astigmatism, straight lines in a certain direction form images on planes at different distances from the retinal plane 26 of the eye 15. Here, due to the aberration of the patient P, the horizontal virtual line 24 is imaged behind the virtual retinal surface 26. The vertical straight line 14 is then imaged forward. With an astigmatic eye viewing the linear targets 14 and 24 on the same plane, it is required to apply a spherical correction to one of the targets 14 and 24 that is clearly different from the other one. From this, it is clear that the spoke-like multi-striated target in the prior art cannot be used in the present invention. Adjacent straight lines with slightly different directions have the best imaging planes adjacent to the retinal surface 26 of patient P with astigmatic eyes, so the criteria for determining visual appearance will be completely different for each patient. . Therefore, only straight targets with parallel striations can be satisfactorily used.

Second, once a linear target, such as target 14, is imaged onto the retinal plane by the astigmatic eye 15, adjustments to the astigmatic correction should be made without changing the focal length of the eye. . In other words, the adjustment of the amount of astigmatism correction should be performed by providing positive and negative refractive powers of equal absolute value along mutually orthogonal axes, respectively. These orthogonal axes are substantially inclined at 45° to the target. In this way, astigmatism correction for each element can be performed without affecting the overall imaging distance of the straight target.

Based on the above description and understanding, the basic operating process of the present invention can be explained with successive reference to FIGS. 1 through 5.

In FIG. 1, patient P is asked to look at straight line 14. Then, the lens pair of the spherical correction optical system 16 is moved relative to each other, and the line 14 is adjusted so that it can be clearly seen. A linear movement coincident with the retinal plane 26 of patient P produces the result shown in FIG.

As shown on the far right of Figure 2, straight line 1
Image 4 does not appear with sufficient clarity. This is because the edges are blurred by astigmatism in the direction along the straight line 14 and the inclined axis. These remaining blurs due to astigmatism are to be corrected without removing the straight line 14 from the retinal plane 26.

In FIG. 3, by relatively moving the first astigmatic lens pair 18, the best sharpness can be adjusted for the patient P.
It has been adjusted to look like. The first astigmatic lens pair each obliquely intersects the vertical straight line 14 and generates negative and positive or positive and negative refractive powers along mutually orthogonal axes, so that the target 14 can be imaged. It is possible to improve only the clarity without changing the distance. This adjustment provides the final prescription for one astigmatic element. (The only allowance is
It is only a matter of repeating the entire procedure to obtain the optimal optical conditions. ) In FIG. 4, a new linear target 34 has been placed for viewing. This straight line target 34 is the straight line target 14
Preferably, it is tilted at an angle of 45°. However, it is not necessary that the angle of inclination be exactly 45°. If the angle is 30° or more, usable results can be obtained.

Referring to FIG. 4, and recalling the steps shown in FIGS. 1 to 3, due to the astigmatism-induced blurring of the eye 15 of the patient P, the straight line target 34 is different with respect to the virtual retinal plane 26 of the eye 15. It has an imaging distance.
Therefore, the second spherical correction is performed using the spherical lens pair 16.
It will be held in This adjustment is made so that the straight target 34 can be seen clearly, and the straight target 34 forms an image on the retinal surface 26.

In this case, the results are surprising. That is, the final correction value of the spherical refractive power can be known by the spherical adjustment for aligning the straight line target 34 with the retinal surface 26. This result can be obtained even if the elements of the final astigmatism correction value are not known. Furthermore, the elements of the final astigmatism correction value do not affect the settings of the illustrated spherical optical conditions. In contrast, in the prior art, spherical adjustment is affected by changes in the cylindrical optical system. With reference to FIG. 4, even if the spherical conditions are adjusted so that the straight line target 34 can be seen better, the sharpness that should be obtained by astigmatism correction still remains. In other words, the patient P who has the eye 15 is unable to obtain maximum sharpness because the horizontal and vertical astigmatism elements have not yet been corrected. Referring to Figure 5,
The lens pairs of the second astigmatism correction optical system 20 are mutually displaced and adjusted to obtain maximum sharpness. This provides the final astigmatism correction element. And again, the relative negative and positive or positive and negative axes of the astigmatism correcting power are tilted at a substantially 45° angle to the target 34, so that no separation of the image from the retinal plane 26 occurs. Furthermore,
This adjustment provides the final adjustment by the device of the present invention to provide the desired astigmatism correction prescription.

From the above description of the device of the invention, it is clear that the procedure described above can be repeated. This repetition may be performed to make the prescription more appropriate, or may be performed to check the correctness of the prescription.

Even if the physical arrangement order of the correction optical systems 16, 18, and 20 is changed, there is no difference in the effect.

The linear target 14 of FIGS. 1-3 and the target 34 of FIGS. 4-5 each require adjustments for only two correction optics and three correction optics. not, i.e. for the target 14 only the spherical optical system 16 and the first astigmatic optical system 18 are adjusted, and the second astigmatic optical system 20
is not adjusted.

Similarly, regarding the target 34, the spherical correction optical system 1
6 and the second astigmatism correction optical system 20 are adjusted, and the first astigmatism correction optical system 18 is not adjusted. It should also be noted that it makes no difference in what order the adjustments are made for each target. The spherical correction optical system can also be adjusted prior to the adjustment of the astigmatism correction optical system. Moreover, conversely, the astigmatism correction optical system can be adjusted first. It is surprising that whether the spherical correction optics 16 or the astigmatism correction optics 20 are manipulated for the target 34, the same final prescription is obtained. The truth is that the result is the same whether the spherical correction optical system 16 or the astigmatism correction optical system is operated first.

Having described the first preferred embodiment, we will now discuss other embodiments.

Referring to FIG. 6, a patient P on the observation station passes through an adjustable spherical optical system S, a cylindrical optical system (astigmatism correction optical system) A with variable refractive power, and a cylindrical fixed optical system C with constant refractive power. Look at the target T along one optical path. In a typical example, the adjustable cylindrical optics are varied so that the patient P sees a target image as shown in FIG. A measurement of one component of astigmatism is performed by controlling the astigmatism correction power such that a target image as shown in FIG. 7 is visible to the patient. Measurements for the remaining elements are made with the same equipment as shown in FIG. In a typical example, the patient P has an adjustable spherical optical system S and an astigmatism correction optical system with adjustable refractive power.
The repositioned target T is viewed through A' and the repositioned fixed cylindrical optical system C'. The visual target T with astigmatic correction along the remaining astigmatic elements is shown in FIG.

With respect to FIG. 12, a plot of the two measured astigmatism correction inputs can be made to represent the cylindrical power and its rotation. While describing this embodiment of the invention, some minor notes will be noted.

Patient P is schematically indicated by eye 44. Typically, a patient's astigmatism measurements are related to ocular inhomogeneities. Therefore, it must be understood that the alignment of the patient's angular components must remain unchanged. The unchanged cylindrical optics and target are re-aligned only to determine the second astigmatic component. The adjustable spherical optical system S may be a conventional variable focus optical system as described above. Typically, a Galileo-type optical system is used.

The target T is shown at the end remote from the optics. Three point light sources 48, 49, 50 are shown. Preferably these are point light sources produced by background illumination through the target T. (Background illumination is not shown.) Fixed cylindrical optical system C is shown slightly exaggerated. The cylindrical optical system shown here is arranged horizontally with respect to the patient P and has a strong diopter in the vertical direction. In the example depicted here, the fixed cylindrical optical system C is approximately
It has a strength of 12 diopters. In practice, the refractive power of the cylinder C can be varied over a wide range. For example, it can be 4 to 20 diopters. For this purpose, William. A variable astigmatic lens group of the type shown in E. Humphrey's "Variable Anamorphic Lens and Method for Making Same" (U.S. Pat. No. 3,751,138, issued Aug. 7, 1973) is used. As detailed in the above invention, a variable astigmatism correcting optical system is obtained by moving lens elements having a special configuration relative to each other in the horizontal and vertical directions. When the arrangement and movement are as shown in FIGS. 5 and 6 of the above specification of the invention, astigmatism can be corrected in a direction of 45 degrees with respect to the horizontal axis of the fixed cylindrical optical system C.

Note that the variable astigmatism lens group A is again schematically depicted by a flat circular glass. See the above-cited US Pat. No. 3,751,138 for an example of the extremely complex surface shapes of these lens groups. Of course, any device that can generate variable astigmatism correction power may be used in the present invention. For example, William. Oppositely rotating positive and negative cylindrical lenses can be used as described in E. Humphrey's patent "Apparatus and Method with Independent Astigmatism Correction and Spherical Inputs," US Pat. No. 3,822,932. What you need is a cylinder C
The only thing that can be done is that a variable astigmatism correction force can be created in a diagonal direction with respect to the axis of .

Preferably, the variable astigmatism correcting lens element (astigmatism correcting optical system) A is inclined at 45° with respect to the fixed cylindrical optical system C. Now that we have given a brief explanation of the structure of this device, let's move on to an explanation of its operation.

With the instrument oriented in the direction shown in FIG. 6, the patient P sees the target T through the strong fixed cylindrical optics C. Due to the fixed cylindrical optical system C, each point light source 48-50 on the target T blurs indistinctly in a series of straight lines 58-60.

(See Figure 2) The first spherical correction was performed using a straight line 58 with patient P's eye.
The boundaries between 59 and 60 should be clearly visible. Due to this spherical correction, the straight line group is placed on the retinal surface, as described in connection with FIG. If we remember that the point light sources are placed at the positions where the vertices of the isosceles triangles are located, and if we assume that no astigmatism correction is required, then each point will appear to have the size shown in FIG. 7. In particular, point 48 is relative to straight line 58, and point 4
9 appears blurred with respect to the straight line 59, and point 50 appears blurred with respect to the straight line 60. The operation of the apparatus for obtaining an astigmatism correction prescription can be explained by changing the assumptions about the eye 44. That is, assume that the patient P's eyes have astigmatic aberration. Furthermore, it is assumed that this astigmatic aberration has an intensity of +1 diopter in a direction inclined at 45 degrees with respect to the fixed cylindrical optical system C, and -1 diopter in a direction perpendicular to the fixed cylindrical optical system C. If no astigmatism correction power is input to the variable astigmatism correction optical system A, the target T will be 8th for the patient P.
Looks like the picture. Straight line 59' appears to approach straight line 60' and appears to move away from straight line 58'.

Next, the variable astigmatism correction optical system A performs visual vernier discrimination with respect to the target T.
acuity). In particular, the pair of variable correction elements (astigmatism correction optical system) A are moved relative to each other and are tilted at 45 degrees with respect to the axis of the fixed cylindrical optical system C.
Generates astigmatism correction power in diopters. Straight lines 58'-60' shown in FIG. 8 move to positions 58-60 shown in FIG. 7 when the astigmatism correction prescription is achieved.
At this time, straight line 59 is equidistant from straight lines 58 and 60.

If you pay attention to the placement of targets in Figures 7 and 8,
I can explain the identification clarity of the vernier. Vernier's concept of discriminant sharpness includes the human ability to align and center groups of straight lines. Referring to FIG. 8, due to the astigmatism of patient P's eye 44 tilted at 45 degrees with respect to the axis of fixed cylindrical optical system C and the refractive power of fixed cylindrical optical system C, point 4
It may be imagined that the blurred straight lines 58', 59', and 60 of 8-50 are curved. This inclination causes straight line 59' to approach straight line 60'. At the same time, straight line 58' separates from straight line 59'. One might imagine that the stronger the astigmatism, the more frequent adjustment of the spherical correction force would be necessary to obtain clear straight lines, but this is not the case here. That is,
Even if the astigmatism in the slanted direction and the line groups that are ``blurred and blurred'' increases, it is only necessary to change the direction of the cylindrical blurring, and there is no need to change the focal length or spherical element. This is true as long as the changes in angular direction are made with good approximation. The patient adjusts the variable astigmatism correction optical system A so that the group of straight lines formed by the unsharp points 48, 49, and 59 are equally spaced. If adjustment is made to compensate for astigmatism in a direction inclined at 45 degrees with respect to the axis of the fixed cylindrical optical system C, the point light sources 48, 49, and 50 will be arranged at equal intervals. If you are a person with normal discernment,
He has the ability to adjust the three lines to be evenly spaced with high precision. It is cited here as Bernier's discernment. While measuring the cylindrical refractive power in a direction inclined at 45 degrees with respect to the axis of the fixed cylindrical optical system C, the fixed cylindrical optical system C, which has a relatively strong refractive power, suppresses astigmatism in parallel and perpendicular directions. The patient's astigmatism in this direction is blurred line 58-6
The length of 0 is slightly lengthened or shortened, but this is not noticeable to the patient. Young patients with strong visual adaptations are more likely to have potentially large spherical corrections. Therefore, in order to maintain a clear straight line, the variable spherical optical system S should be moved gradually in a stronger direction. This makes it possible to suppress imaging due to potential adaptation as much as possible and perform correct examinations. Having explained the astigmatism measurement of the unidirectional element, next we will explain the astigmatism measurement of the remaining important parts using the arrangement shown in FIG.

Assuming the arrangement shown in FIG. 9, the image seen by the patient P remains the same as that shown in FIG. Similarly,
The spherical optical system S shown in FIG. 9 is also of a downward variation. The fixed cylindrical optical system C is repositioned. Usually, it is tilted by 45 degrees compared to the case shown in Figure 6 (satisfactory results can be obtained even up to 30 degrees). In this position, the strong refractive power of the fixed cylindrical optical system C' causes the horizontal and vertical astigmatic components to be canceled out or exceeded. Therefore, in the second test, the astigmatism factor measured at the beginning has been completely erased. Target T′ is similarly rotated. Points 48, 49, and 50 are arranged at an angle of 45° to the target shown in FIG. The target T' has the same arrangement as the fixed cylindrical optical system C. Point 48,4
9 and 50 are all located at the vertices of a virtual isosceles triangle whose base is parallel to the rotation axis of the fixed cylindrical optical system C'.

The variable astigmatism lens (astigmatism correction optical system) A is the aforementioned William. E. Humphrey's "Variable Anamorphic Lens and Method for Making the Same" (U.S. Patent No.
3751138). By performing the lens arrangement and movement shown in FIGS. 3 and 4 of this patent specification, the fixed cylindrical optical system C
Astigmatism correction in a direction tilted by 45 degrees is realized.

Of course, any device that produces variable astigmatism correction power as already depicted in FIG. 6 can be used in the present invention.
The only requirement is to be able to generate variable astigmatism correction power in a direction tilted to the fixed cylindrical optical system C.
It goes without saying that the variable astigmatism lens element (astigmatism correction optical system) A' is preferably tilted at 45 degrees with respect to the fixed cylindrical optical system C'.

When the device is repositioned from the direction shown in FIG. 6 to the direction shown in FIG. 9, the remaining astigmatic component can be measured.

In the case described above, the patient P views the target T' through a strong fixed cylindrical optical system C'. The fixed cylindrical optical system C' blurs each point 48-50 on each straight line 58-60 and makes it unclear. First, the straight line 58,5
Spherical correction is performed so that the boundaries of 9 and 60 appear sharp. It will be recalled that each point is located at a vertex of an isosceles triangle. To describe the basic case, consider the case where the fixed cylindrical optical system C' is inclined at 45 degrees and the spherical correction perpendicular to it is not required. Each point appears to have the size shown in Figure 10. . Especially point 48
is on the straight line 58, point 49 is on the straight line 59, and point 50 is on the straight line 58.
are blurred and blurred on the straight line 60. Let us now explain the operation for correcting the remaining astigmatic elements by changing the assumption regarding the patient P's eye 44. Assume that patient P's eyes have astigmatic aberration. Further, it is assumed that this aberration has a cylindrical refractive power of -2 diopters in a direction inclined at 45 degrees with respect to the axis C, and a cylindrical refractive power of +2 diopters in a direction perpendicular to this. When no astigmatism correction power is input to the variable astigmatism correction optical system A, the image seen by the patient P is as shown in FIG. 11. Straight line 58' appears to approach straight line 60', and straight line 58' appears to move away from it. The variable astigmatism correction optic A' is then operated in response to the patient's vernier discrimination relative to the target T'. In particular, the variable astigmatism elements (astigmatism correction optical system) A' are moved relative to each other to produce a refractive power of ±2 diopters, a total of 4 diopters, along the axis tilted at 45 degrees with respect to the direction of the fixed cylindrical optical system C'. do.

Straight lines 58', 59', 6 shown in FIG.
0' is position 5 if the astigmatism correction prescription is achieved.
Move towards 8, 59, 60. Straight line 59 is straight line 5
It comes equidistant from 8,60. It will be appreciated that many variations are possible in the second embodiment described herein. For example, a two-point target can be used in conjunction with a blurring cylinder to provide a single straight line image to the eye with astigmatism correction achieved. In this case, more than one straight line is visible when viewed with the eye for which astigmatism correction has not been achieved. When astigmatism correction is performed, the convergence of these lines becomes a self-test goal for the patient. Thus, in this embodiment, any number of targets with multiple straight lines can be used, as long as the astigmatism optic is moved to provide an appreciable geometric alignment. be.

Two optical elements are operated for each target instead of three as shown in the previous embodiment.
In this way, for the target T' facing in the direction shown in FIGS. 6 to 8, only the adjustment of the spherical optical system and the relative movement of the variable astigmatism correction optical system A in the horizontal direction are required, and the astigmatism correction optical system There is no need to move A in the vertical direction. Similarly, for the target T' facing in the directions shown in Figures 9 to 11, only the adjustment of the spherical optical system and the relative movement in the vertical direction are required, and the horizontal movement of the astigmatism correction optical system A is not necessary. be. Similarly, it should be noted that the adjustment is the same regardless of the order in which the adjustments are made for the targets T facing each direction. It is also possible to first adjust the spherical optical system S. Alternatively, the astigmatism correction optical system A may be adjusted first. Furthermore, surprisingly, the first operation was performed by changing the spherical optical system S or the astigmatism correction optical system A to the second one.
Even if the target T is in the direction of , the same prescription is ultimately obtained in either case. It is correct that either the spherical optical system S or the astigmatism correction optical system A is operated first. By using the device of the present invention, two astigmatic elements can be obtained, so the necessary prescription can be determined. Referring to FIG. 12, a plot of Cartesian coordinates has been converted to one for the angular direction of a normal cylindrical lens. However, this angle is oversized by a factor of 2.

In this way, in the plot shown in Figure 12, the rotation of the cylindrical lens by 180° is not the case in the actual plot.
Marked at 360°. Referring to Fig. 12, when the examination device is arranged as shown in Fig. 9, the amount of astigmatism offset is plotted as 4 diopters in the 0 direction, and in the case of the arrangement shown in Fig. 6, it is plotted as 4 diopters in the y direction. Two diopters are plotted in the 45° direction. As a result, the required astigmatism correction is determined to be approximately 4.5 diopters of cylindrical power in a direction of 77 degrees. The lens settings used here are extreme. Optical corrections of this strength are rarely needed. This figure was created to explain the case of plotting on polar coordinates in the present invention. Further advantages can be obtained by using a special form of Cartesian coordinates. In particular, in the case of a low diopter refractive power, it becomes difficult to prescribe an astigmatic lens such as that obtained using ordinary polar coordinates. This is due to errors, and the error in orientation increases at low diopters. Those who have errors in these plotted coordinates are saved. Let us assume that the configurations shown in Figures 6 and 9 each provide a positive cylindrical refractive power of 1/2 diopter. Furthermore, let us assume that the uncertainty of this value is ±1/4 diopter.
Referring to Figure 12, the position of 1/2 diopter is 7.
Plotted to 0. Furthermore, the possible range in the 1/2 diopter prescription is plotted at 72. Assume that the error caused by the patient's error in astigmatism correction falls anywhere inside the circle 72. At this time, if plotting is performed in polar coordinates, the error regarding the angular component will increase. For example, if it is assumed that the error caused by the device falls within a circle 72, the angular range will be as wide as 11.20° to 33.7°. On the other hand, if this is plotted in Cartesian coordinates, not only can it be easily converted to conventional polar coordinates, but it can also describe astigmatism correction by itself. This method is William. E. Humphrey's patent "Ophthalmic Apparatus and Method with Independent Astigmatism Correction Input and Spherical Input" (U.S. Patent No.
3822932) and is also claimed. It is clear that modifications can be made to the invention within the scope of the claims. Similar to the spherical lens (spherical lens optical system) S, a fixed central column optical system C, a variable astigmatism correction optical system A, a target T,
Naturally, changes can be made as long as the principles described above are not changed.

[Brief explanation of the drawing]

FIG. 1 shows an apparatus for eye examination according to the invention,
A target diagram is drawn. This target image is viewed by the patient, and the correction optical system inserted between the patient's eye and the target image is depicted using a perspective drawing from the retinal surface of the eye. FIG. 2 is a diagram similar to FIG. 1, showing the first spherical correction adjustment according to the present invention. FIG. 3 is a diagram similar to FIG. 1, illustrating the determination of the correction of the first astigmatic component in accordance with the present invention. Figure 4 is a view similar to the first, but with a new target view at an angle (preferably 45°) for making the second and final spherical correction prescription change to determine the spherical correction prescription required for the patient. It is depicted. FIG. 5 is a diagram similar to FIG. 4, and shows the determination of the final astigmatism factor to complete the examination. FIG. 6 shows another embodiment using a cylindrical blur point to measure astigmatism. FIG. 7 shows the preferred target image of the present invention as viewed by the patient's eye when optimal astigmatism correction has been achieved. FIG. 8 shows the same target as viewed by the patient's eye without an optimal astigmatism correction prescription. FIG. 9 is a view corresponding to FIG. 6 in which the cylinder and target image are arranged at an angle of 45° relative to the arrangement of FIG. 6 in order to examine the patient's remaining astigmatic elements. FIG. 10 shows a target view as seen by the patient's eye through the device of the present invention when an astigmatic prescription is determined along the remaining astigmatic elements. FIG. 11 shows a target diagram when a correct astigmatism correction prescription has not been determined. FIG. 12 is a plot diagram showing how astigmatism correction measurements are combined with the plots of the rotational and cylindrical correction prescriptions described above. P...patient, A, A'...astigmatism correction optical system,
C, C'... Cylindrical optical system, T, T'... Target, 1
5, 44...Eye, 16, 18, 20...Lens pair.

Claims (1)

[Claims] 1. An observation station on which the patient's own eye is to be positioned; at least one first linear target aligned with the station at an arbitrarily preselected angle independent of the principal axis of the patient's eye to be examined; positioned between the viewing station and a linear target, when being viewed by the patient;
a variable spherical optical system for changing the spherical correction of the linear target; and a variable spherical optical system for changing the spherical correction of the first linear target, the first linear target being disposed between the observation station and the linear target in alignment with the spherical optical system. a first variable astigmatic optical system for changing the astigmatic lens refractive power along first intersecting axes that intersect in mutually opposite angular directions by substantially equal angles with respect to the preselected alignment angle; and the first variable astigmatism optical system changes the astigmatism refractive power from positive to negative along one axis of the first intersecting axes and from negative to positive along the other axis of the first intersecting axes. and, as a result, the patient himself/herself can determine the first component of the astigmatism prescription. 2. an observation station in which the patient's own eye is to be positioned; at least one first linear target aligned with said station at an arbitrarily preselected angle independent of the principal axis of the patient's eye to be examined; said observation station; placed between a linear target and being observed by the patient;
a variable spherical optical system for changing the spherical correction of the linear target; and a variable spherical optical system for changing the spherical correction of the first linear target, the first linear target being disposed between the observation station and the linear target in alignment with the spherical optical system. a first variable astigmatic optical system for changing the astigmatic lens refractive power along first intersecting axes that intersect in mutually opposite angular directions by substantially equal angles with respect to the preselected alignment angle; and the first variable astigmatism optical system changes the astigmatism refractive power from positive to negative along one axis of the first intersecting axes and from negative to positive along the other axis of the first intersecting axes. a second straight line target aligned to a preselected second angle, so that the patient himself or herself can determine the first component of the astigmatism prescription; the linear target has an inclination of at least 30° with respect to said first linear target; as a result, the difference in this spherical correction to the sharpness of said second linear target determines the spherical prescription for said patient. Optometric prescription determination device. 3. an observation station in which the patient's own eye is to be positioned; at least one first linear target aligned at an arbitrarily preselected angle independent of the principal axis of the patient's eye of the station; placed between a linear target and being observed by the patient;
a variable spherical optics system for changing the spherical correction of the linear target; and a variable spherical optics system arranged between the observation station and the linear target in alignment with the spherical optical system; a first variable astigmatic optical system for varying the astigmatic lens refractive power along first intersecting axes that intersect in mutually opposite angular directions by approximately equal angles with respect to the preselected alignment angle; , the first variable astigmatic optical system has an astigmatic refractive power from positive to negative along one axis of the first intersecting axes and from negative to positive along the other axis of the first intersecting axes. a first component of the astigmatism prescription; further comprising a second linear target aligned to a preselected second angle; The linear target has an inclination of at least 30° with respect to the first linear target; as a result, the difference in this spherical correction to the sharpness of the second linear target can determine the spherical prescription for the patient. furthermore, a second intersecting axis for altering the astigmatic lens refractive power along a second intersecting axis substantially equal to and mutually opposite to the alignment direction of the second linear target;
a variable spherical optical system; the second variable astigmatism optical system has a variable spherical optical system from positive to negative along one of the second intersecting axes and negative along the other axis of the second intersecting axes; It changes the astigmatic refractive power from positive to positive;
An optometric prescription determining device that determines a second component of an astigmatism prescription for the patient by varying the second variable astigmatism optical system.