Method for determining eyeglass lenses, and a system for supporting the determination of eyeglass lenses.

Abstract

Provided is an eyeglass lens determination method that includes: a step in which a plurality of blurry images are prepared, the images obtained by changing the amount of aberration applied to a prescribed source image; a step in which the sensitivity of a test subject to aberration is measured by simultaneously presenting a plurality of blurry images to the test subject, causing the test subject to compare ways of viewing, and obtaining the test subject's conscious responses; and a step in which an eyeglass lens appropriate for the test subject is determined, on the basis of the sensitivity of the test subject to aberration.

Description

Technical Field

[0001] The present invention relates to a method for determining spectacle lenses and a system for assisting in the determination of spectacle lenses.

Background Art

[0002] Various design methods have been proposed to realize spectacle lenses suitable for the characteristics of individual wearers. For example, Patent Document 1 discloses presenting a plurality of blurred images created by applying different degrees of blur to an original image to be visually recognized by a wearer, obtaining information regarding the wearer's sensitivity to blur, and designing spectacle lenses based on the information regarding the wearer's sensitivity to blur.

[0003] Also, for example, Patent Document 2 discloses displaying an image on a display device while maintaining the positional relationship between the face of a subject and the display device, obtaining information evaluating the subject's sensitivity regarding vision based on the impression of the subject who has visually recognized the image, and designing spectacle lenses based on the information evaluating the sensitivity.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of one embodiment of the present invention is to provide a technique for determining spectacle lenses suitable for a subject in consideration of the sensitivity regarding the aberration of the subject.

Means for Solving the Problems

[0006] A first aspect of the present invention is: A process of preparing multiple blurred images by varying the amount of aberration added to a given original image, The process involves simultaneously presenting the subject with multiple blurred images and having them compare how they appear, and obtaining the subject's subjective response to measure the subject's sensitivity to aberrations. A method for determining eyeglass lenses, comprising the step of determining eyeglass lenses suitable for the subject based on the subject's sensitivity to aberrations.

[0007] A second aspect of the present invention is: In the step of preparing the aforementioned multiple blurred images, further steps are taken to prepare a plurality of similar blurred images that are similar to the aforementioned multiple blurred images. The method for determining eyeglass lenses according to the first embodiment is as follows: in the step of measuring the subject's sensitivity to aberrations, the subject is simultaneously presented with a plurality of similar blurred images and asked to compare how they appear, and the stability of the subject's subjective response is measured by obtaining the subject's subjective response multiple times.

[0008] A third aspect of the present invention is: In the process of preparing the aforementioned multiple blurred images, further preparations are made of multiple blurred images with varying levels of difficulty, where the difference in appearance is easier or harder to discern than the aforementioned multiple blurred images. The first embodiment of the method for determining eyeglass lenses is described above, in which the step of measuring the subject's sensitivity to aberrations is to simultaneously present the subject with multiple difficulty-changing blur images and have them compare how they appear, and to obtain the subject's subjective response multiple times to measure the subject's sensitivity to aberrations.

[0009] A fourth aspect of the present invention is: The method for determining eyeglass lenses according to the first embodiment is as described above, wherein the step of preparing the multiple blurred images is to select the original image according to the characteristic direction of the spatial frequency characteristic reduction due to the added aberration.

[0010] A fifth aspect of the present invention is: The process for determining the spectacle lens involves determining a progressive power lens, as described in the first embodiment of the method for determining spectacle lenses.

[0011] A sixth aspect of the present invention is: The method for determining eyeglass lenses according to the first embodiment is as follows: In the step of measuring the subject's sensitivity to aberrations, the plurality of blurred images are presented at a size such that the spatial frequency of the essential part of the plurality of blurred images is between 3 CPD and 9 CPD.

[0012] A seventh aspect of the present invention is: The method for determining eyeglass lenses according to the first embodiment is as described above, in which the subject's sensitivity to aberrations is measured, the subject's head is not fixed, and the plurality of blurred images are presented at a distance of 0.3 m to 2 m from the subject's eyes.

[0013] An eighth aspect of the present invention is: A storage unit that stores multiple blurred images obtained by varying the amount of aberration added to a predetermined original image, A display unit that simultaneously presents the subject with multiple blurred images and allows them to compare how they appear, An input unit for inputting the subject's subjective responses, A determination unit that determines the subject's sensitivity to aberrations from the subjective response, The eyeglass lens determination support system includes an output unit that outputs information for determining eyeglass lenses suitable for the subject based on the sensitivity to the aforementioned aberrations. [Effects of the Invention]

[0014] According to one embodiment of the present invention, it is possible to determine eyeglass lenses suitable for a subject, taking into account the subject's sensitivity to aberrations. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a flowchart showing an example of a method for determining eyeglass lenses according to the first embodiment of the present invention. [Figure 2]FIG. 2 is a diagram showing an example of an original image and a plurality of blurred images according to the first embodiment of the present invention. [Figure 3] FIG. 3 is a diagram showing an example of a spot image formed by aberration added to the blurred image according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing an example of a similar blurred image according to the first embodiment of the present invention. [Figure 5] FIG. 5 is a diagram for explaining a characteristic direction of the spatial frequency characteristics of the original image according to the first embodiment of the present invention. [Figure 6A] FIG. 6A is an image obtained by adding downward aberration to an image (original image) of text read in the right direction on the paper surface. [Figure 6B] FIG. 6B is an image obtained by adding upward aberration to an image (original image) of text read in the right direction on the paper surface. [Figure 6C] FIG. 6C is an image obtained by adding rightward aberration to an image (original image) of text read in the right direction on the paper surface. [Figure 6D] FIG. 6D is an image obtained by adding leftward aberration to an image (original image) of text read in the right direction on the paper surface. [Figure 7A] FIG. 7A is an image obtained by adding downward aberration to an image (original image) of text read in the downward direction on the paper surface. [Figure 7B] FIG. 7B is an image obtained by adding upward aberration to an image (original image) of text read in the downward direction on the paper surface. [Figure 7C] FIG. 7C is an image obtained by adding rightward aberration to an image (original image) of text read in the downward direction on the paper surface. [Figure 7D] FIG. 7D is an image obtained by adding leftward aberration to an image (original image) of text read in the downward direction on the paper surface. [Figure 8A] FIG. 8A is a diagram showing the refractive power distribution and the aberration distribution of a spectacle lens according to an embodiment of the present invention. [Figure 8B] FIG. 8B is a diagram showing the refractive power distribution and the aberration distribution of a spectacle lens according to an embodiment of the present invention. [Modes for carrying out the invention]

[0016] <Insights gained by the inventor> First, let me explain the findings obtained by the inventor. As described in Patent Document 1, it was found that when multiple blurred images are presented sequentially, the evaluation may differ depending on the subject's memory, fatigue level, adaptability, etc., making it possible that sensitivity to blur (hereinafter also referred to as sensitivity to aberration) cannot be accurately measured. There is also the problem that the measurement time becomes long.

[0017] The inventors have diligently investigated the problems described above. As a result, they have found that by presenting subjects with multiple blurred images simultaneously and having them compare how they perceive them, the influence of the subjects' memory, fatigue level, adaptability, etc., can be minimized, and their sensitivity to blur can be accurately measured. Furthermore, the measurement time can be shortened. In addition, since multiple blurred images are compared, relative evaluation is possible, which has the advantage of making it easier for subjects to evaluate. Therefore, it becomes easier to determine eyeglass lenses that are suitable for the subject, taking into account their sensitivity to blur.

[0018] [Details of the Embodiments of the Invention] Next, one embodiment of the present invention will be described below with reference to the drawings. However, the present invention is not limited to these examples and is intended to include all modifications within the meaning and scope equivalent to the claims, as shown in the claims.

[0019] <First Embodiment of the Invention> (1) How to determine eyeglass lenses First, the method for determining eyeglass lenses in this embodiment will be described. Figure 1 is a flowchart showing an example of the method for determining eyeglass lenses in this embodiment. As shown in Figure 1, the method for determining eyeglass lenses in this embodiment includes, for example, a blur image preparation step S101, a blur sensitivity measurement step S102, and an eyeglass lens determination step S103. In this embodiment, the case of determining a progressive power lens suitable for the subject will be described.

[0020] (Preparation process for blurred image S101) The blur image preparation step S101 is a step of preparing multiple blur images (in this embodiment, two blur images) by changing the amount of aberration added (preferably only that amount) to a predetermined original image. In this embodiment, the aberration added includes astigmatism, coma aberration, trefoil aberration, etc. Figure 2 shows an example of an original image and multiple blur images. In Figure 2, a blur image 10A is shown with a predetermined amount of aberration added to the original image 10, and a blur image 10B has a larger amount of aberration added than blur image 10A.

[0021] Figure 3 shows an example of a spot image created by an aberration added to a blurred image. In Figure 3, a spot image with a tail-like projection is shown in the lower left corner of the page. A blurred image with an aberration that creates such a spot image appears blurred in the lower left direction. In other words, the added aberration significantly (characteristically) reduces the spatial frequency characteristics in the lower left direction. In this specification, this characteristic direction of spatial frequency characteristic reduction due to the added aberration will be referred to as the aberration direction.

[0022] In the blur image preparation step S101, it is preferable that the directions of the aberrations added to multiple blur images (for example, blur image 10A and blur image 10B) are approximately the same. This makes it easier for the subject to compare how the multiple blur images appear. In this specification, "approximately the same direction of aberration" includes not only cases where the directions are perfectly the same, but also cases where there is a slight difference of ±15 degrees or less in the direction of the aberrations. The direction of the aberration refers to the direction of the component with the largest absolute value among all the coefficients of all the blur images when the aberrations added to each of the simultaneously displayed blur images are each expanded using the Zernike polynomial.

[0023] In addition, when selecting the aberration to be added to the original image in the blurred image preparation step S101, one may arbitrarily select from, for example, aberrations produced by a standard progressive lens.

[0024] (Blur sensitivity measurement process S102) The blur sensitivity measurement step S102 is a step in which the subject's sensitivity to aberrations is measured by, for example, presenting multiple blurred images to the subject simultaneously, having them compare how they appear, and obtaining the subject's subjective response. Specifically, for example, blurred image 10A and blurred image 10B, as shown in Figure 2, are presented simultaneously and the subject is asked to compare how they appear and select which one appears clearer. If the subject selects blurred image 10A, which has a smaller amount of added aberration (hereinafter also referred to as selecting the correct answer), it may be determined that the subject has high sensitivity to blur, and if the subject selects blurred image 10B, which has a larger amount of added aberration (hereinafter also referred to as selecting the incorrect answer), it may be determined that the subject has low sensitivity to blur. In this specification, presenting multiple blurred images simultaneously means presenting multiple blurred images so that they are visible to the subject while multiple blurred images are present within the subject's field of view, and the timing of the start or end of presentation of each blurred image is not limited (for example, the start or end of presentation timings for blurred image 10A and blurred image 10B may be staggered).

[0025] However, if sensitivity to blur is determined by a single subjective response, it may include cases where, for example, a blurred image with a small amount of aberration was selected by chance, even if the subject did not actually perceive any difference in appearance. Therefore, in the blurred image preparation step S101 of this embodiment, it is preferable to further prepare a plurality of similar blurred images that are similar to the plurality of blurred images, and in the blur sensitivity measurement step S102, the subject is simultaneously presented with a plurality of similar blurred images in which the amount of added aberration (preferably only this amount) is changed, and is asked to compare how they appear, and the stability of the subjective response is measured by obtaining the subject's subjective response multiple times. The similar blurred images will be described in detail below.

[0026] Figure 4 shows an example of a similar blurred image, similar to blurred image 10A and blurred image 10B. In this specification, a similar blurred image means, for example, an image obtained by rotating a blurred image by an arbitrary angle, or an image obtained by enlarging or reducing a blurred image by an arbitrary magnification. Figure 4 shows similar blurred images 20A and 20B, obtained by rotating blurred image 10A and blurred image 10B by 90 degrees, similar blurred images 21A and 21B, obtained by rotating blurred image 10A and blurred image 10B by 180 degrees, and similar blurred images 22A and 22B, obtained by rotating blurred image 10A and blurred image 10B by 270 degrees. In this case, for example, in the blur sensitivity measurement step S102, two (similar) blurred images with the same rotation angle (e.g., similar blurred image 20A and similar blurred image 20B) are presented simultaneously, and the subject is asked to compare how they appear. The subject makes four choices about which image appears clearer, and their subjective response can be obtained four times. For example, if the subject selects an image with a small amount of added aberration each time (blurred image 10A, similar blurred images 20A, 21A, 22B), it is determined that the stability of the subjective response is high. If the subject selects images with small and large added aberrations in roughly equal proportions, it is determined that the stability of the subjective response is low. High stability of the subjective response indicates high sensitivity to the added aberration, and by measuring the stability of the subjective response, it becomes possible to measure sensitivity to blur more accurately. This makes it easier to determine eyeglass lenses suitable for the subject.

[0027] It is important to note that while blurred images and similar blurred images share a common source image, they are not exactly the same. When obtaining subjective responses multiple times using the exact same blurred image, the influence of the subject's adaptability becomes strong, potentially making it impossible to accurately measure sensitivity to blur. In contrast, using similar blurred images reduces the influence of the subject's adaptability, allowing for a more accurate measurement of sensitivity to blur. Furthermore, in the blur sensitivity measurement step S102, to further reduce the influence of the subject's adaptability, the display positions of the image with small and large aberrations may be swapped.

[0028] To more precisely measure the subject's sensitivity to blurring, in the blurring image preparation step S101 of this embodiment, it is preferable to further prepare multiple blurring images with varying difficulty levels, where the difference in appearance is easier or harder to discern than that of the multiple blurring images. In the blurring sensitivity measurement step S102, it is preferable to simultaneously present the subject with multiple blurring images with varying difficulty levels and have them compare how they appear, thereby measuring the subject's sensitivity to aberrations by obtaining the subject's subjective response multiple times. Details of the blurring images with varying difficulty levels will be described below.

[0029] When multiple blurred images are presented simultaneously to a given original image, each with varying amounts of added aberration, some blurred images will have easily discernible differences in appearance, while others will have difficulty to distinguish between them. In this specification, the ease (or difficulty) of distinguishing between such differences in blurred images is expressed as difficulty level. The difficulty level of a blurred image is influenced by the amount and direction of added aberration, as well as the spatial frequency characteristics of the original image. For example, simply having a large difference in the amount of aberration added to two blurred images does not necessarily mean that the difficulty level will be low. To determine the difficulty level of a blurred image, for example, the VSOTF may be calculated for each of the multiple blurred images, and the difficulty level may be determined by the difference in VSOTF, or a large number of subjects may be asked to compare how they appear, and the difficulty level may be determined by their accuracy rate. Regarding VSOTF, it is described in the following document: "Thibos LN, Hong X, Bradley A, Applegate RA. Accuracy and precision of objective refraction from wavefront aberrations. J Vis. 2004 Apr 23;4(4):329-51.", and therefore, an explanation will be omitted here.

[0030] By using multiple types of difficulty-changing blur images with varying difficulty levels, and investigating how much difference in visual perception a subject can distinguish, it becomes possible to measure the subject's sensitivity to blur in stages. This makes it easier to determine eyeglass lenses suitable for the subject. To reduce the influence of the subject's adaptability, it is preferable that the multiple types of difficulty-changing blur images are based on different original images. Also, from the viewpoint of smooth measurement, it is preferable that the (difficulty-changing) blur image presented first in the blur sensitivity measurement step S102 is one with a low difficulty level. Furthermore, as mentioned above, it is preferable to prepare similar blur images for each of the multiple types of difficulty-changing blur images and measure the stability of the subject's subjective response by obtaining the subject's subjective response multiple times.

[0031] Figure 5 illustrates the characteristic direction of the spatial frequency characteristics of the original image. In the original image 11 shown in Figure 5, the contrast changes significantly in the left-right direction of the paper, so it can be said that the characteristic direction of the spatial frequency characteristics is the left-right direction. If, for example, an aberration in the vertical direction is added to such an original image 11, it is expected that the resulting blurred image will not look much different from the original image 11. In other words, if the direction of the added aberration differs from the characteristic direction of the spatial frequency characteristics of the original image, it is likely to result in a blurred image that is difficult to create. On the other hand, if, for example, an aberration in the left-right direction is added to the original image 11, it is expected that the resulting blurred image will look significantly different from the original image 11. In other words, if the direction of the added aberration matches the characteristic direction of the spatial frequency characteristics of the original image, it is likely to result in a blurred image that is easy to create. Therefore, in the blurred image preparation step S101 of this embodiment, it is preferable to select the original image according to the characteristic direction of the spatial frequency characteristic reduction due to the added aberration (direction of the aberration). This makes it possible to appropriately control the difficulty of creating the blurred image. Specifically, for example, by selecting a source image such that the direction of the added aberration approximately coincides with the characteristic direction of the spatial frequency characteristics of the original image, it is possible to avoid extremely difficult-to-distinguish blurred images where the difference in appearance is indistinguishable to anyone. In this specification, "approximately coincides" between the direction of the added aberration and the characteristic direction of the spatial frequency characteristics of the original image may mean, for example, that the absolute value of the dot product of the unit direction vectors of the two is 0.7 or greater. The direction of the aberration (0° to 180°) is the direction in which the blur is greatest, and is obtained from the direction in which the variance of the point image intensity distribution is greatest. When using a source image without line symmetry, a further sign may be added based on the direction from the peak point to the centroid point of the point image distribution function (i.e., the direction of the aberration is -180° to 180°).

[0032] In the blur sensitivity measurement step S102, it is preferable to present multiple blur images such that the spatial frequency of the key parts of the multiple blur images is between 3 CPD and 9 CPD (corresponding to a visual acuity of 0.1 to 0.3). For example, if a blur image that is too large to see without glasses is presented to a myopic subject, it may not be possible to accurately measure the sensitivity to blur due to the influence of adjustment errors in the glasses. In contrast, by presenting a blur image that is large enough for many subjects to see without glasses, individual differences in perception are reflected to a greater extent, allowing for a more accurate measurement of the subject's sensitivity to blur. In this specification, the key parts of a blur image refer to characteristic parts of the blur image where differences in appearance are easily discernible. Furthermore, it is preferable to present multiple blur images of the same size, but even if there are slight differences in the magnification of the multiple blur images (for example, a magnification of less than 5%), it is acceptable as long as the subject can distinguish the differences in appearance. Furthermore, the size of the blurred image such that the spatial frequency of the essential parts is between 3 CPD and 9 CPD (corresponding to visual acuity of 0.1 to 0.3) means, for example, that if the original image is composed of line drawings or text, the width of the main lines that make it up is between 1 / 6 and 1 / 18 of a degree of visual angle.

[0033] In the blur sensitivity measurement step S102, it is preferable, for example, not to fix the subject's head and to present multiple blurred images at a distance of 0.3m to 2m from the subject's eyes. When the subject's head is fixed during measurement, tension occurs, increasing the subject's burden. Furthermore, since the tension of the head muscles and the tension of the eye muscles are linked, it becomes difficult for the subject to use their eyes in a normal, everyday way, and it may be impossible to accurately measure the sensitivity to blur. In contrast, by performing the measurement without fixing the subject's head, the burden on the subject can be reduced. In addition, by presenting multiple blurred images at a distance where the effect of slight changes in head position (for example, about 3cm) is negligible, the sensitivity to blur can be measured more accurately.

[0034] In the blur sensitivity measurement step S102, the answer choices for subjective responses may include not only "Which image is clearly visible?" but also "I can't see the difference." Subjects who frequently select "I can't see the difference" tend to be more aware of their low sensitivity to blur. Furthermore, if there are multiple subjects with a similar proportion of correct answers, subjects who frequently select "I can't see the difference" are often more tolerant of eyeglass aberrations than subjects who rarely select "I can't see the difference." Thus, considering the response rate of "I can't see the difference" makes it easier to determine eyeglass lenses that are more suitable for the subject in the eyeglass lens determination step S103.

[0035] Furthermore, sensitivity to blur (or aberration) can be divided into, for example, sensitivity to the size of the blur and the strength of the bias depending on the direction of the blur. The sensitivity to blur described so far is mainly sensitivity to the size of the blur, but in the blur sensitivity measurement step S102, it is preferable to measure not only the sensitivity to the size of the blur but also the strength of the bias depending on the direction of the blur. Hereafter, the direction of the blur will refer to the direction in the range of -180° to 180°, which corresponds to the direction in which the tail is drawn, as shown in the spot image in Figure 3. In other words, for example, the left and right directions will be distinguished as the right direction and the left direction.

[0036] Figures 6A to 6D and 7A to 7D are examples of blurred images used to illustrate biases due to the direction of blurring. For an image of text read from right to left (original image), Figure 6A has aberration added in the downward direction, Figure 6B in the upward direction, Figure 6C in the rightward direction, and Figure 6D in the leftward direction. Similarly, for an image of text read from bottom to top (original image), Figure 7A has aberration added in the downward direction, Figure 7B in the upward direction, Figure 7C in the rightward direction, and Figure 7D in the leftward direction.

[0037] In Figures 6A to 6D, many subjects selected Figure 6C, which has rightward aberration added, as clearly visible. In Figures 7A to 7D, many subjects selected Figure 7A, which has downward aberration added, as clearly visible. In other words, in blurred images containing text, there is a tendency to perceive blur less when the direction in which the text is read matches the direction in which the aberration is added. Since the strength of such bias varies from person to person, it is preferable to measure the degree to which subjects have a bias based on the direction of blur. It is also preferable to take into account the differences based on the language that subjects normally use when conducting the measurement.

[0038] As mentioned above, sensitivity to the magnitude of blur can be measured, for example, by presenting subjects with multiple blurred images in which the amount of added aberration differs, and observing whether or not they can recognize the difference. Here, from the viewpoint of reducing the influence of bias due to the direction of blur and more accurately measuring sensitivity to the magnitude of blur, it is preferable, for example, to present subjects with blurred images in which the direction of the added aberration has been changed by 180°, and to obtain subjective responses multiple times. Furthermore, the degree of bias due to the direction of blur can be estimated, for example, from the degree of agreement or disagreement in responses when the direction of the added aberration has been changed by 180°.

[0039] Furthermore, from the viewpoint of reducing the influence of bias due to the direction of blur and more accurately measuring sensitivity to the magnitude of blur, it is preferable to present subjects with blurred images in which the dot product of the unit direction vector of the direction of the added aberration and the characteristic direction of the spatial frequency characteristics of the original image is 0.7 or greater, and blurred images in which it is -0.7 or less, and to obtain subjective responses multiple times. Specifically, for example, for an original image of text that is read from right to left, it is preferable to prepare approximately equal numbers of blurred images with rightward aberration added and blurred images with leftward aberration added, and present them to the subjects.

[0040] (Eyeglass lens selection process S103) The eyeglass lens determination step S103 is a step in which eyeglass lenses suitable for a subject are determined based on the subject's sensitivity to aberrations, for example, as measured in the blur sensitivity measurement step S102. In the eyeglass lens determination step S103, it is preferable to determine progressive power lenses. This is because the effect of aberrations is significant in progressive power lenses, so it is particularly important to consider the subject's sensitivity to blur.

[0041] Specifically, for example, in the blur sensitivity measurement step S102, for subjects who consistently select the correct answer, it may be determined that they have high sensitivity to blur, and a progressive power lens that minimizes aberrations along the principal meridian may be determined. Alternatively, for example, for subjects who consistently select the incorrect answer, it may be determined that they have high sensitivity to blur but prefer a state with large aberrations, and a progressive power lens with the aberrations preferred by the subject may be determined. Furthermore, for example, for subjects whose selection of correct and incorrect answers is inconsistent and who have answered "I cannot see the difference" infrequently, it may be determined that they have low sensitivity to blur but do not consciously perceive themselves as having low sensitivity, and a progressive power lens with a balanced design of low aberrations and improvements in other areas (e.g., power-focused design) may be determined. Finally, for example, for subjects who have answered "I cannot see the difference" many times, it may be determined that they have low sensitivity to blur, and a progressive power lens with a design that improves other areas while retaining aberrations along the principal meridian may be determined.

[0042] In the vicinity of the principal meridian of a progressive power lens with a positive add power, a downward aberration occurs. Therefore, in the spectacle lens determination process S103, the progressive power lens may be determined as follows, taking into account the bias due to the direction of blur. For example, for a subject who is highly sensitive to the magnitude of blur and has a small bias due to the direction of blur, it may be determined that the subject is more sensitive to blur on the principal meridian (or has high sensitivity to blur), and a progressive power lens that minimizes the aberration on the principal meridian may be determined. Alternatively, for a subject who is highly sensitive to the magnitude of blur and has a large bias due to the direction of blur, it may be determined that the subject is less sensitive to blur on the principal meridian (but perceives peripheral blur), and a progressive power lens designed to improve peripheral aberrations while retaining aberrations on the principal meridian may be determined. For example, for a subject with low sensitivity to the magnitude of blur and small bias depending on the direction of blur, it may be determined that they do not perceive blur on the principal meridian (or have low sensitivity to blur), and a progressive power lens designed to improve peripheral aberrations while retaining aberrations on the principal meridian may be selected. For example, for a subject with low sensitivity to the magnitude of blur and large bias depending on the direction of blur, it may be determined that they hardly perceive blur, and a progressive power lens designed to improve other aspects (such as depth of field) while retaining aberrations on the principal meridian may be selected.

[0043] In the eyeglass lens selection step S103, the eyeglass lenses may be selected taking into account the subject's residual refractive error. Specifically, for example, for subjects with strong refractive errors such as astigmatism, the eyeglass lenses may be selected by assuming that they actually have a slightly higher sensitivity than the sensitivity measured in the blur sensitivity measurement step S102, taking into account the possibility that they may have difficulty distinguishing the difference in how blurred images appear.

[0044] (2) Eyeglass lens selection support system The present invention can also be applied as a system to assist in determining eyeglass lenses. The eyeglass lens determination assistance system of this embodiment includes, for example, a storage unit that stores multiple blurred images obtained by varying the amount of aberration added to a predetermined original image; a display unit that simultaneously presents multiple blurred images to a subject and allows them to compare how they appear; an input unit that inputs the subject's subjective response; a determination unit that determines the subject's sensitivity to aberration from the subject's subjective response; and an output unit that outputs information for determining eyeglass lenses suitable for the subject based on the subject's sensitivity to aberration. The eyeglass lens determination assistance system of this embodiment can be implemented, for example, by a tablet terminal equipped with a predetermined program, and has the advantage of low implementation costs. Furthermore, the eyeglass lens determination assistance system of this embodiment may further include, for example, a creation unit that adds a predetermined aberration to an original image and creates a blurred image.

[0045] <Other embodiments of the present invention> Although embodiments of the present invention have been specifically described above, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.

[0046] For example, in the embodiment described above, two blurred images were prepared by varying the amount of aberration added to a predetermined original image, and the two blurred images were presented simultaneously for comparison. However, three or more blurred images may be prepared, and the three or more blurred images may be presented simultaneously for comparison. However, when three or more blurred images are presented simultaneously for comparison, differences due to position within the field of view may become dominant. Furthermore, it may become difficult for the subject to make a judgment. Therefore, from the viewpoint of reducing differences due to position within the field of view and presenting blurred images that are easy for the subject to judge, it is preferable to present two blurred images simultaneously for comparison, as in the embodiment described above.

[0047] Furthermore, in the above-described embodiment, for example, the case in which the direction of aberrations added to multiple blurred images presented simultaneously is approximately the same, but it is not necessary for the direction of aberrations added to multiple blurred images presented simultaneously to be approximately the same. Specifically, for example, one blurred image may have no astigmatism added at all (no direction of aberration), while the other blurred image may have astigmatism added (there is a direction of aberration). In this case as well, as in the above-described embodiment, it is easy for the subject to compare how the multiple blurred images appear. [Examples]

[0048] Next, embodiments of the present invention will be described. These embodiments are examples of the present invention, and the present invention is not limited to these embodiments.

[0049] (Preparation process for blurred image S101) In this embodiment, two blurred images were presented simultaneously. First, six different source images were prepared, and six pairs of blurred images with varying difficulty levels (difficulty-varying blurred images) were prepared. Furthermore, for each of the six pairs of blurred images, the rotation angle was changed to prepare three similar blurred images (four in total, including the original blurred image), resulting in a total of 24 pairs of blurred images.

[0050] (Blur sensitivity measurement process S102) In this embodiment, pairs of blurred images were displayed on a tablet device 24 times in a random order, and the subjects were asked to compare how they appeared to each other, and their subjective responses indicating which image was clearer were obtained 24 times. The blurred images were enlarged to a size such that the spatial frequency of their key parts was approximately 6 CPD (corresponding to a visual acuity of 0.2), and were presented at a distance of 1 meter in front of the subjects.

[0051] In this embodiment, subjects who frequently selected blurred images with small added optical aberrations (or blurred images with a good evaluation index) (for example, 18 or more out of 24 times) were classified as Group A, which has high sensitivity to aberrations; subjects who moderately selected blurred images with small added optical aberrations (or blurred images with a good evaluation index) (for example, 7 to 17 out of 24 times) were classified as Group B, which has low sensitivity to aberrations; and subjects who did not select blurred images with small added optical aberrations (or blurred images with a good evaluation index) very often (for example, 6 or fewer out of 24 times) were classified as Group C, which evaluates images from a different perspective than the designer. In this specification, the evaluation index is the VSOTF of the blurred image, or an index indicating the visibility of the blurred image calculated from the selection results of past subjects.

[0052] (Eyeglass lens selection process S103) In this embodiment, a progressive power lens suitable for a subject was determined based on the subject's sensitivity to aberrations measured in the blur sensitivity measurement step S102 described above. Specifically, for example, for group A, a progressive power lens having a power distribution and astigmatism distribution (AS) as shown in Figure 8A was determined, and for group B, a progressive power lens having a power distribution and astigmatism distribution (AS) as shown in Figure 8B was determined. As shown in Figure 8A, for subjects with high sensitivity to aberrations, a lens without astigmatism on or near the principal meridian is suitable, and as shown in Figure 8B, for subjects with low sensitivity to aberrations, a lens with astigmatism on the principal meridian but with a wide range of sufficient near-vision add power on both sides is suitable. In the measurements conducted by the inventors to date, no subjects belonging to group C have appeared. However, since objective optical indicators are difficult to apply to group C, it is advisable to conduct additional investigations, such as counseling, to determine the appropriate eyeglass lens.

[0053] Based on the above, we confirmed that it is possible to determine suitable eyeglass lenses for each subject by considering their sensitivity to aberrations. [Explanation of Symbols]

[0054] 10, 11 Original images 10A, 10B blurred images Similar blurred images: 20A, 20B, 21A, 21B, 22A, 22B S101 Preparation process for blurred images S102 Blur Sensitivity Measurement Process S103 Eyeglass Lens Selection Process

Claims

1. A process of preparing multiple blurred images by varying the amount of aberration added to a given original image, The process involves simultaneously presenting the subject with multiple blurred images and having them compare how they appear, and obtaining the subject's subjective response to measure the subject's sensitivity to aberrations. The process includes determining suitable spectacle lenses for the subject based on the subject's sensitivity to aberrations, In the step of preparing the aforementioned multiple blurred images, a further set of similar blurred images is prepared, which are images obtained by rotating the aforementioned multiple blurred images by an arbitrary angle, or images obtained by enlarging or reducing the aforementioned multiple blurred images by an arbitrary magnification. A method for determining eyeglass lenses, comprising the step of measuring the subject's sensitivity to aberrations, in which the subject is simultaneously presented with a plurality of similar blurred images and asked to compare how they appear, and the stability of the subject's subjective response is measured by obtaining the subject's subjective response multiple times.

2. In the step of preparing the aforementioned multiple blurred images, further multiple blurred images with varying difficulty levels are prepared, which are blurred images with different VSOTF differences from the aforementioned multiple blurred images, or blurred images with different correct answer rates when the appearance is compared by a large number of subjects. The method for determining eyeglass lenses according to claim 1, wherein the step of measuring the subject's sensitivity to aberrations is to simultaneously present the subject with a plurality of difficulty-changing blur images and have him compare how they appear, and to obtain the subject's subjective response multiple times to measure the subject's sensitivity to aberrations.

3. The method for determining eyeglass lenses according to claim 1, wherein in the step of preparing the plurality of blurred images, the original image is selected according to the characteristic direction of the spatial frequency characteristic reduction due to the added aberration.

4. The method for determining eyeglass lenses according to claim 1, wherein the step of determining the eyeglass lens is to determine a progressive power lens.

5. The method for determining eyeglass lenses according to claim 1, wherein in the step of measuring the subject's sensitivity to aberrations, the plurality of blurred images are presented such that the spatial frequency of the essential parts of the plurality of blurred images is 3 CPD or more and 9 CPD or less.

6. The method for determining eyeglass lenses according to claim 1, wherein in the step of measuring the subject's sensitivity to aberrations, the subject's head is not fixed, and the plurality of blurred images are presented at a distance of 0.3 m to 2 m from the subject's eyes.

7. A storage unit that stores multiple blurred images obtained by varying the amount of aberration added to a predetermined original image, A display unit that simultaneously presents the subject with multiple blurred images and allows them to compare how they appear, An input unit for inputting the subject's subjective responses, A determination unit that determines the subject's sensitivity to aberrations from the subjective response, It has an output unit that outputs information for determining eyeglass lenses suitable for the subject based on the sensitivity to the aberrations, The storage unit further stores a plurality of similar blurred images, which are images obtained by rotating the plurality of blurred images by an arbitrary angle, or images obtained by enlarging or reducing the plurality of blurred images by an arbitrary magnification. The display unit simultaneously presents the subject with the multiple similar blurred images and allows them to compare how they appear. The determination unit is a spectacle lens selection support system that determines the stability of the subjective response by obtaining the subject's subjective response multiple times.

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