Method for determining spectacle lens

Abstract

Provided is a method for determining a spectacle lens, the method comprising: a step (a) for preparing a plurality of blurred images obtained by applying varying tendencies and degrees of blur to a predetermined original image; a step (b) for conducting trials by presenting a plurality of blurred images to a subject at the same time and asking the subject to compare the appearances of the images to acquire subjective responses from the subject; and a step (c) for determining a spectacle lens suitable for the subject on the basis of the subjective responses acquired in the step (b). In the step (b), trials in which subjects tend to respond that an image with a greater degree of blur applied is preferable out of the plurality of blurred images presented account for more than half of all the trials.

Description

How to choose eyeglass lenses

[0001] The present invention relates to a method for determining spectacle lenses.

[0002] Various design methods have been proposed to realize eyeglass lenses that are suited to the characteristics of individual wearers. For example, Patent Document 1 describes a method for designing eyeglass lenses, which includes presenting a plurality of blurred images created by blurring an original image to different degrees and having the wearer visually recognize the images, acquiring information about the wearer's sensitivity to blur, and designing eyeglass lenses based on the information about the wearer's sensitivity to blur.

[0003] Furthermore, for example, Patent Document 2 describes a method for designing eyeglass lenses, which includes displaying an image on a display device while maintaining the positional relationship between the subject's face and the display device, obtaining information that evaluates the subject's visual sensitivity based on the subject's impression of viewing the image, and designing eyeglass lenses based on the information that evaluates the sensitivity.

[0004] Also, for example, Patent Document 3 describes a progressive lens design that is caused by or related to the lifestyle and / or biometric parameters of the lens wearer.

[0005] Furthermore, for example, Patent Document 4 describes a method for designing eyeglass lenses, which includes a characteristic acquisition step of having a subject visually view different spatial frequencies and acquiring the subject's cognitive characteristics for the spatial frequencies, a characteristic calculation step of calculating the subject's vision characteristics from the subject's cognitive characteristics, and a lens design step of reflecting the subject's vision characteristics in the lens design of the subject's eyeglass lenses.

[0006] International Publication No. 2018 / 101015 International Publication No. 2019 / 009034 Patent No. 6072407 Patent No. 6894621

[0007] An object of one embodiment of the present invention is to provide a technology for grasping a subject's preferred tendency for blur and determining eyeglass lenses suitable for the subject.

[0008] A first aspect of the present invention is a method for determining eyeglass lenses, comprising: a step (a) of preparing a plurality of blurred images obtained by adding blurring of different tendencies and degrees to a predetermined original image; a step (b) of simultaneously presenting the plurality of blurred images to a subject and asking the subject to compare how they appear, thereby obtaining a subjective response from the subject; and a step (c) of determining eyeglass lenses suitable for the subject based on the subjective response obtained in step (b), wherein in step (b), questions presenting a plurality of blurred images that tend to result in subjects answering that blurred images with a greater degree of blurring are preferable account for more than half of all questions.

[0009] A second aspect of the present invention is a method for determining eyeglass lenses, comprising: a step (a) of preparing a plurality of blurred images obtained by adding blurring of different tendencies and degrees to a predetermined original image; a step (b) of simultaneously presenting the plurality of blurred images to a subject and asking the subject to compare how they appear, thereby obtaining a subjective response from the subject; and a step (c) of determining eyeglass lenses suitable for the subject based on the subjective response obtained in step (b), wherein in step (b), problems presenting a plurality of blurred images with blur tails of different lengths account for more than half of all problems.

[0010] A third aspect of the present invention is a method for determining eyeglass lenses, comprising: a step (a) of preparing a plurality of blurred images obtained by adding blurring with different tendencies or degrees to a predetermined original image; a step (b) of simultaneously presenting the plurality of blurred images to a subject and asking the subject to compare how they appear, thereby obtaining a subjective response from the subject; and a step (c) of determining eyeglass lenses suitable for the subject based on the subjective response obtained in the step (b), wherein the step (a) further prepares a plurality of rotationally blurred images by rotating the blurred image by an arbitrary angle, by rotating only the direction of the blur to be added without changing the original image, or by rotating the original image without changing the blur to be added; and the step (b) includes a task of simultaneously presenting the plurality of blurred images to the subject and asking the subject to compare how they appear, and a task of simultaneously presenting the plurality of rotationally blurred images to the subject and asking the subject to compare how they appear.

[0011] A fourth aspect of the present invention is the method for determining a spectacle lens according to any one of the first to third aspects, further comprising a step (d) of obtaining a subjective response from the subject by one or more tests conducted separately from the step (b), and in the step (c), spectacle lenses suitable for the subject are determined based on the subjective responses obtained in the step (b) and the step (d).

[0012] A fifth aspect of the present invention is the method for determining a spectacle lens according to any one of the first to third aspects, wherein the step (b) includes a problem of presenting a blurred image to which multi-peak blur has been added and a blurred image to which uni-peak blur has been added.

[0013] A sixth aspect of the present invention is the method for determining a spectacle lens according to the first or second aspect, wherein in the step (a), a plurality of rotationally blurred images are further prepared by rotating the blurred image by an arbitrary angle, rotating only the direction of the blur to be added without changing the original image, or rotating the original image without changing the blur to be added, and in the step (b), a problem of presenting the plurality of blurred images simultaneously to the subject and having the subject compare how they appear, and a problem of presenting the plurality of rotationally blurred images simultaneously to the subject and having the subject compare how they appear.

[0014] A seventh aspect of the present invention is the method for determining a spectacle lens according to any one of the first to third aspects, wherein in the step (b), a score is assigned based on whether or not the subjective response of the subject coincides with average support in a group, and in the step (c), a spectacle lens suitable for the subject is determined based on the score.

[0015] An eighth aspect of the present invention is the method for determining a suitable eyeglass lens according to the seventh aspect, wherein in step (c), at least one of the score and a statistical amount of support in all or part of the population is presented to the subject.

[0016] A ninth aspect of the present invention is the method for determining a spectacle lens according to the seventh aspect, wherein in the step (c), a spectacle lens suitable for the subject is determined based on the magnitude relationship between the score and a predetermined threshold value.

[0017] A tenth aspect of the present invention is the method for determining a spectacle lens according to the ninth aspect, in which a plurality of threshold values ​​are prepared, and the threshold value is selected depending on the type and number of tests to be performed separately from the step (b).

[0018] An eleventh aspect of the present invention is the method for determining a spectacle lens according to any one of the first to third aspects, wherein in the step (a), the original image is selected according to a characteristic direction of a spot to be convolved with the original image when adding blur.

[0019] A twelfth aspect of the present invention is the method for determining a spectacle lens according to any one of the first to third aspects, wherein in the step (c), a progressive power lens is determined.

[0020] A thirteenth aspect of the present invention is the method for determining a spectacle lens according to any one of the first to third aspects, wherein in the step (b), the plurality of blurred images are presented at a size such that the spatial frequency of a main part of the plurality of blurred images is 3 CPD or more and 9 CPD or less.

[0021] A fourteenth aspect of the present invention is the method for determining a spectacle lens according to any one of the first to third aspects, wherein in the step (b), the subject's head is not fixed, and the plurality of blurred images are presented at a distance of 0.3 m or more and 2 m or less from the subject's eyes.

[0022] According to one embodiment of the present invention, it is possible to grasp the tendency of blur preferred by a subject and determine spectacle lenses suitable for the subject.

[0023] FIG. 1 shows examples of blurred images with different lengths of blur tails. FIG. 2 shows examples of blurred images to which bimodal and unimodal blurs have been added. FIG. 3 is a flowchart illustrating an example of a method for determining eyeglass lenses according to a first embodiment of the present invention. FIG. 4 shows examples of an original image and a plurality of blurred images according to a first embodiment of the present invention. FIG. 5 shows examples of spots to be convolved into the original image according to a first embodiment of the present invention. FIG. 6 shows an example of a rotationally blurred image according to a first embodiment of the present invention. FIG. 7 is a diagram illustrating characteristic directions of the spatial frequency characteristics of an original image according to a first embodiment of the present invention. FIG. 8A is an image obtained by convolving a spot with a downward tail onto an image of text read to the right of the page (original image). FIG. 8B is an image obtained by convolving a spot with an upward tail onto an image of text read to the right of the page (original image). FIG. 8C is an image obtained by convolving a spot with a rightward tail onto an image of text read to the right of the page (original image). FIG. 8D is an image obtained by convolving a spot with a leftward tail onto an image of text read to the right of the page (original image). 9A is an image obtained by convolving a spot with a downward tail onto an image (original image) of text read downward on the page. FIG. 9B is an image obtained by convolving a spot with an upward tail onto an image (original image) of text read downward on the page. FIG. 9C is an image obtained by convolving a spot with a rightward tail onto an image (original image) of text read downward on the page. FIG. 9D is an image obtained by convolving a spot with a leftward tail onto an image (original image) of text read downward on the page. FIG. 10 is a flowchart showing an example of a method for determining a spectacle lens according to another embodiment of the present invention. FIG. 11A is a diagram showing the power distribution and astigmatism distribution of a spectacle lens of design A according to an embodiment of the present invention. FIG. 11B is a diagram showing the power distribution and astigmatism distribution of a spectacle lens of design B according to an embodiment of the present invention.

[0024] <Findings Obtained by the Inventor> First, the findings obtained by the inventor will be described. As described in Patent Document 1, it was found that when a plurality of blurred images are presented in sequence, the evaluation may vary depending on the subject's memory, fatigue level, adaptation level, etc., and it may be impossible to accurately measure sensitivity to blur. Another problem is that the measurement time becomes long.

[0025] The inventors of the present invention have conducted extensive research into the above-mentioned problems, and as a result have found that by presenting multiple blurred images to a subject at the same time and having the subject compare how they appear, sensitivity to blur can be accurately measured without being affected by the subject's memory, fatigue level, adaptation level, etc.

[0026] In this specification, "adding blur" means blurring an original image by filtering it. The filter used is an optical spot that has been discretized to match the pixels of the image. Since filtering is generally performed by convolving the filter with the original image, adding blur is also referred to as "convolving a spot." The spot may be an optically correct spot that uses aberration information in a spectacle lens, or an artificial spot that intentionally violates the diffraction limit or the law of energy conservation. The latter may be preferable in order to suppress the effects of discretization.

[0027] Further research by the inventors revealed that subjects do not judge image visibility solely based on the magnitude of blur (or the amount of aberration that causes blur) or MTF (Modulation Transfer Function). A specific example is shown in Figure 1. In Figure 1, the length of the tail of the spot convolved in the right blurred image (also referred to as the length of the blur tail) is approximately twice that of the left blurred image. In other words, the spot convolved in the right blurred image has a larger amount of aberration and a smaller MTF. However, when a group of subjects were presented with these two blurred images and asked to compare their appearance, more subjects responded that the right blurred image was clearer and preferable. This is thought to be because many subjects preferred blur with a thin, spread spot tail. Note that "preferred" here means more acceptable to the subjects.

[0028] Another specific example is shown in Figure 2. In Figure 2, the spot convolved with the blurred image on the left has good MTFs at both low and high frequencies, but is bimodal. On the other hand, the spot convolved with the blurred image on the right has a poorer MTF, but is unimodal. Here too, when a group of subjects were presented with these two blurred images and asked to compare how they looked, most of the subjects answered that the blurred image on the right was relatively preferable, because the image on the left has clear lines but doubles. This is thought to be because very few subjects preferred bimodal blur.

[0029] Thus, it can be said that the subject's preference for blur is unrelated to the amount of aberration or MTF. In the field of optics, the amount of aberration generally refers to the sum of squares of Zernike aberration, which corresponds to the root-sum-of-squares (RSS) of the reduction in MTF for all spatial frequencies, including many ultra-high frequencies imperceptible to humans. Furthermore, the root-mean-square (RMS) blur error described in Patent Document 3 corresponds to the reduction in MTF for extremely low frequencies. Furthermore, Patent Document 4 asserts that humans pay attention to high frequencies in addition to low frequencies, and that the MTF should be maintained. Whether considering only low frequencies or low and high frequencies, adding bimodal blur results in better numerical MTF characteristics. In other words, the methods described in these documents do not adequately grasp the subject's preference for blur.

[0030] Therefore, the present inventors have further conducted intensive research and discovered a method for grasping the tendency of blur preferred by subjects. Specifically, for example, the method includes a step (a) of preparing a plurality of blurred images to which blurring of different tendencies and degrees has been added to a predetermined original image, a step (b) of simultaneously presenting the plurality of blurred images to the subject and asking the subject to compare how they look, thereby obtaining a subjective response from the subject, and a step (c) of determining an eyeglass lens suitable for the subject based on the subjective response obtained in the step (b), wherein in the step (b), a plurality of blurred images that tend to be preferred by subjects are presented, and more than half of all the questions are presented. Also, for example, in the step (b), a plurality of blurred images with different lengths of blur tails are presented, and more than half of all the questions are presented. Furthermore, for example, in the step (a), a plurality of rotationally blurred images are further prepared by rotating the blurred image by an arbitrary angle, rotating only the direction of the added blur without changing the original image, or rotating the original image without changing the added blur, and in the step (b), a problem is included in which the plurality of blurred images are simultaneously presented to the subject and the subject is asked to compare how they look, and a problem is included in which the plurality of rotationally blurred images are simultaneously presented to the subject and the subject is asked to compare how they look.By these methods, it is possible to grasp the tendency of blur preferred by the subject and to determine eyeglass lenses suitable for the subject.

[0031] [Details of the embodiment of the present invention] Next, an embodiment of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0032] First Embodiment of the Present Invention (1) Spectacle Lens Determination Method First, a spectacle lens determination method of this embodiment will be described. Fig. 3 is a flowchart showing an example of the spectacle lens determination method of this embodiment. As shown in Fig. 3, the spectacle lens determination method of this embodiment includes, for example, a blur image preparation step S101, a subjective response acquisition step S102, and a spectacle lens determination step S103. In this embodiment, a case where a progressive power lens suitable for a subject is determined will be described.

[0033] The spectacle lens determination method of this embodiment may include testing, such as counseling, conducted separately from the above steps in order to determine the final design. Alternatively, the design may be determined after narrowing down a number of design candidates from among multiple candidates, prioritizing the multiple candidates, or the like. Furthermore, the method may include a step of returning an output such as "additional testing required" when, for example, the information necessary for the determination is insufficient.

[0034] (Blurred Image Preparation Step S101) The blurred image preparation step S101 is a step of preparing, for example, a plurality of blurred images (two blurred images in this embodiment) by adding blurring with different tendencies and degrees to a predetermined original image (i.e., by changing the spots convolved with the original image). The tendency and degree of blurring to be added may be determined based on aberration. In this embodiment, the convolved spots correspond to spots created by a wavefront including astigmatism, coma, trefoil aberration, etc. The amount of aberration included in the wavefront may be based on the actual amount of aberration of the candidate lens, or may be generated using random numbers. In this embodiment, statistical values ​​of the amount of aberration that may occur in a progressive-power lens are calculated from patent documents, etc., and the image is randomly generated within that range. More specifically, for an object point located 1 m away, this corresponds to the image created 1 m away by a lens with no prescription and a 4 mm aperture diameter that has the above-mentioned aberration. Note that the 4 mm aperture diameter is a diameter that is assumed to be the pupil diameter. The size and distance of the diameter may be changed depending on the application. The image calculation was performed using wave optics, but it may also be performed using geometric optics.

[0035] An example of an original image and a plurality of blurred images is shown in Fig. 4. Fig. 4 shows a blurred image 10A obtained by adding a blur including a predetermined amount of aberration to the original image 10, and a blurred image 10B obtained by adding a larger degree of blur than the blurred image 10A.

[0036] FIG. 5 shows an example of a spot convolved with the original image. FIG. 5 shows a spot with a tail at the bottom left of the page. A blurred image convolved with such a spot appears blurred in the lower left direction. More precisely, among the vectors parallel to the first principal axis when the point spread function is subjected to principal component analysis (in the case of FIG. 5, the axis connects the upper right and lower left of the page), the vector pointing in the opposite direction to the vector pointing from the center of gravity of the point spread function to the peak of the point spread function represents the direction of the tail.

[0037] In the blurred image preparation step S101, it is preferable that the directions of blur added to the multiple blurred images (for example, blurred image 10A and blurred image 10B) are approximately the same. This makes it easier for the subject to compare the appearance of the multiple blurred images. In this specification, "the directions of blur approximately match" includes not only cases where the directions are completely the same, but also cases where there is a slight difference of ±15 degrees or less in the direction of blur. The direction of blur refers to the direction of the vector representing the tail described above.

[0038] In the blurred image preparation step S101, when selecting spots to be convolved with the original image, the selection may be based on, for example, the aberration caused by a standard progressive power lens.

[0039] (Subjective Response Acquisition Step S102) The subjective response acquisition step S102 is a step of, for example, simultaneously presenting a plurality of blurred images to the subject and asking the subject to compare the appearance of the images, thereby obtaining a subjective response from the subject. Specifically, for example, blurred image 10A and blurred image 10B as shown in FIG. 2 are simultaneously presented to the subject to compare the appearance of the images and select which one is preferable (e.g., which one is more clearly visible). Note that in this specification, "presenting a plurality of blurred images simultaneously" means presenting a plurality of blurred images so that the plurality of blurred images are visible within the field of view of the subject, and the timing of the start or end of presentation of each blurred image is not limited (e.g., the start or end timing of presentation of blurred image 10A and blurred image 10B may be different from each other).

[0040] As described above, subjects do not judge the visibility of an image solely based on the magnitude of blur or MTF. Therefore, in the subjective response acquisition step S102 of this embodiment, multiple questions are presented to the subject, and subjective responses are obtained multiple times. Questions presenting multiple blurred images that tend to result in subjects preferring blurred images with a greater degree of blur (hereinafter also referred to as "reverse tendency questions") are included. Preferably, the questions are selected so that the reverse tendency questions account for more than half of all questions. Alternatively, the subjective response acquisition step S102 includes questions presenting multiple blurred images with different blur tail lengths (tail lengths of the convoluted spots) (hereinafter also referred to as "tail length comparison questions"). Preferably, the questions are selected so that the tail length comparison questions account for more than half of all questions. By using either of these methods, the subject's preferred blur tendency can be grasped regardless of the amount of aberration or the magnitude of MTF. Then, the subject's preferred blur tendency can be taken into consideration to determine the appropriate eyeglass lenses for the subject. In this specification, unless otherwise specified, "all questions" means "all questions in the subjective response acquisition step S102."

[0041] In order to select questions with a reversal tendency, for example, a group of people may be given a number of questions in advance that present blurred images with various blurs added, statistics may be collected, and questions for which more test subjects answered that blurred images with a larger degree of added blur (or a smaller MTF) were preferred may be extracted (i.e., questions for which the superiority or inferiority of the amount of aberration or MTF tends to be reversed with the approval rating).

[0042] In the tail length comparison problem, it is preferable to present multiple blurred images in which the overall spread and the direction of the spot tail are approximately the same but the lengths of the spot tails are different. More specifically, it is preferable to present, for example, a blurred image in which the overall spread of the spot is somewhat large but the spot tail is short, and a blurred image in which the overall spread of the spot is somewhat small but the spot tail is long. This makes it possible to understand whether the subject places importance on the slight difference in the overall spread of the spot or on the length of the spot tail. Note that, in this specification, the length and direction of the spot tail mathematically correspond to the variance and vector of the first principal axis obtained by principal component analysis of the point spread function, and the overall spread of the spot corresponds to the sum of the variances of the first and second principal axes of the entire point spread function. Furthermore, "the overall extent of the spread of the spots is approximately the same" means that the extent of the spread of the smaller spots is 60% to 100% (preferably 80% to 100%) of the extent of the spread of the larger spots, and "the directions of the tails of the spots are approximately the same" means that the difference in the directions of the tails is within 45 degrees (preferably within 22.5 degrees).

[0043] Of course, there are also questions that are both reversal tendency questions and tail length comparison questions. It is more preferable that, in the subjective response acquisition step S102, more than half of all questions selected be reversal tendency questions and more than half be tail length comparison questions. This makes it easier to grasp the subject's preferred blur tendencies.

[0044] In the subjective response acquisition step S102, it is preferable to include a problem in which a blurred image with multimodal blur and a blurred image with unimodal blur are presented (hereinafter also referred to as a multimodal problem). More specifically, for example, it is preferable to present a blurred image with multimodal blur and a blurred image with a greater degree of unimodal blur. This makes it possible to determine whether the subject prefers multimodal or unimodal blur. In this specification, multimodal blur corresponds to a spot having one to three subpeaks with an intensity of 50% or more of the maximum intensity of the spot peak. In other words, multimodality includes bimodal blur, which corresponds to astigmatism plus spherical aberration of the eye, trimodal blur, which corresponds to trefoil plus spherical aberration of the eye, and tetramodal blur, which corresponds to higher-order aberrations of the eye, but does not include pentamodal or higher aberrations.

[0045] According to the inventor's findings to date, few subjects prefer the blurring caused by multimodal problems, and multimodal problems are unlikely to be a major factor determining individual differences. Therefore, it is preferable to avoid having too many multimodal problems (e.g., more than half) in the subjective response acquisition step S102. Specifically, for example, it is preferable that multimodal problems account for 1% to 40% of all problems in the subjective response acquisition step S102.

[0046] In the tail length comparison problem or the multi-peak problem, even if the relative value difference of the aberration amount of the spots convolved in the multiple blurred images to be compared is the same, if the absolute aberration amount changes, the preference tendency may change. Therefore, it is preferable that the subjective response acquisition step S102 includes multiple problems in which the absolute aberration amount of the convolved spots is changed.

[0047] In the blurred image preparation step S101 of this embodiment, a plurality of rotationally blurred images are further prepared by rotating the blurred image by an arbitrary angle, rotating only the direction of the blur to be added without changing the original image, or rotating the original image without changing the blur to be added, and the subjective response acquisition step S102 preferably includes a question in which a plurality of blurred images are simultaneously presented to a subject and the subject is asked to compare how they appear, and a question in which a plurality of rotationally blurred images are simultaneously presented to a subject and the subject is asked to compare how they appear. Rotational blurred images will be described in detail below.

[0048] FIG. 6 shows an example of a rotational blurred image obtained by rotating blurred image 10A and blurred image 10B by an arbitrary angle. In this specification, a rotational blurred image refers to, for example, an image obtained by rotating a blurred image by an arbitrary angle, an image obtained by rotating only the direction of the added blur (the direction of the tail of the convoluted spot) without changing the original image, or an image obtained by rotating the original image without changing the added blur. For example, a rotational blurred image and a blurred image share the same original image, and the convoluted spots are similar. However, discretization may be used to adjust for any strict similarity. Furthermore, when using an original image with a clear direction (the direction in which the text is read or the orientation of the symbol), such as text or symbols, the direction of the text may be changed instead of rotating the original image. In this case, the content of the text may be changed depending on the question. If the font size or line width of the text or symbol is the same, it is considered equivalent to a question using a common image, regardless of the content. Images, text, or symbols in which changes in direction are difficult to perceive are not suitable as original images. Specifically, this applies to shapes with strong rotational symmetry, such as circles and simple polygons. Landolt rings are also unsuitable. For example, an image of an upward-facing Landolt ring rotated 90 degrees could be perceived as an image of a right-facing Landolt ring displayed without rotation, making it difficult to achieve the intended perception. When using these shapes, it is preferable to arrange multiple shapes in a straight line, or take other measures to make the directionality clear.

[0049] 6 shows rotational blurred images 20A and 20B, which are obtained by rotating blurred images 10A and 10B by 90 degrees, rotational blurred images 21A and 21B, which are obtained by rotating blurred images 10A and 10B by 180 degrees, and rotational blurred images 22A and 22B, which are obtained by rotating blurred images 10A and 10B by 270 degrees. In this case, for example, in the subjective response acquisition step S102, two (rotational) blurred images (e.g., rotational blurred image 20A and rotational blurred image 20B) with the same rotation angle are simultaneously presented, and four questions (hereinafter also referred to as similar questions) are posed to compare the appearance, and subjective responses can be obtained four times from the subject. By using such similar questions, the subject's preferred blur tendency can be understood and the eyeglass lens suitable for the subject can be determined. In particular, by checking whether the answer changes depending on the image and the direction of blur, it is possible to understand the degree of dependence on the direction of blur.

[0050] In the subjective response acquisition step S102, in addition to the similar questions, questions presenting overlapping blurred images (hereinafter also referred to as overlapping questions) in which the blurred image and the convoluted spots are congruent and oriented in the same direction may be included. It is preferable that the overlapping blurred images have the same original image, or, when using images with a clear orientation such as text, have the same orientation even if the content is different. By presenting similar questions in overlapping fashion, the effects of adaptation due to order and the effects of display position can be reduced. To achieve this, it is preferable to equalize the conditions by presenting questions presenting a certain blurred image in the first half of the total questions and overlapping questions in the second half, or by displaying blurred images A and B on the left and right sides of the display device, respectively, and then displaying overlapping blurred images A' and B' on the right and left sides, respectively.

[0051] In order to measure the subject's preferred blur tendency in more detail, in the blur image preparation step S101 of this embodiment, a plurality of blur images with varying degrees of difficulty, in which the difference in appearance is easier or harder to see than the plurality of blur images, is further prepared, and in the subjective response acquisition step S102, a plurality of blur images with varying degrees of difficulty are simultaneously presented to the subject, and questions are asked for the subject to compare the appearance, and subjective responses are obtained from the subject multiple times. Details of the blur images with varying degrees of difficulty will be described below.

[0052] When multiple blurred images, each with different blur tendencies and degrees of blur added to a given original image, are simultaneously presented, some blurred images are easy to see the difference in appearance, while others are difficult to see. In this specification, the ease (difficulty) of seeing the difference in appearance between such blurred images is referred to as the difficulty level. For example, a large number of subjects may be asked to compare the appearances in advance, and the difficulty level may be determined based on their correct answer rate. On the other hand, if statistics on the correct answer rates from a sufficient number of subjects cannot be obtained, the difficulty level may be determined based on optical quantities. The difficulty level of a blurred image is affected by the amount of aberration, the direction of blur, and the spatial frequency characteristics of the original image. Therefore, for example, simply because the difference in the amount of aberration of the spots convolved into two blurred images is large, the difficulty level does not necessarily decrease. To determine the difficulty level of a blurred image based on optical quantities, for example, the VSOTF may be calculated for each of the multiple blurred images, and the difficulty level may be determined based on the difference between the VSOTFs. The VSOTF 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." Therefore, a description thereof will be omitted here.

[0053] By using multiple types of difficulty-varying blur images with different levels of difficulty to examine the level of difficulty at which the subject can distinguish differences in appearance, it is possible to gradually grasp the subject's preferred level of blur. This makes it easier to determine the appropriate eyeglass lenses for the subject. It is preferable that the multiple types of difficulty-varying blur images each have a different original image to reduce the influence of the subject's adaptation. Furthermore, for multiple types of difficulty-varying blur images, it is preferable to prepare rotational blur images as described above and obtain the subject's subjective responses multiple times. Furthermore, questions with higher or lower difficulty levels may be prioritized depending on the subjective response trends. Specifically, for example, questions with higher difficulty levels may be prioritized for subjects with higher scores, as described below. Furthermore, from the perspective of smoothly obtaining the subject's subjective responses, it is preferable that the (difficulty-varying) blur images presented first in the subjective response acquisition step S102 be of a sufficiently low level of difficulty. By presenting questions with a sufficiently low level of difficulty other than the first question, it is possible to confirm whether the subjective responses are being obtained correctly. For the purpose of practicing and confirming button operation and the like when answering, extremely easy questions that almost everyone in the group will agree on may be repeatedly asked. It is preferable not to refer to the answers to these questions in the eyeglass lens determination step S103. When considering the proportion of each question among all questions in the subjective response acquisition step S102, it is also preferable to exclude questions intended for practice and confirmation from the number of questions. On the other hand, if the expected answer is not given during practice and confirmation, a warning may be output indicating a possible insufficient understanding of the measurement or a problem with the device.

[0054] FIG. 7 is a diagram illustrating the characteristic direction of the spatial frequency characteristics of an original image. The original image 11 shown in FIG. 7 has a large change in contrast in the left-right direction of the page, so the characteristic direction of the spatial frequency characteristics can be said to be the left-right direction. Adding blur, for example, in the up-down direction, to such an original image 11 is expected to result in a blurred image that looks very similar to the original image 11. In other words, if the direction of the blur to be added differs from the characteristic direction of the spatial frequency characteristics of the original image, the blurred image is likely to be difficult to create. On the other hand, adding blur, for example, in the left-right direction, to the original image 11 is expected to result in a blurred image that looks very different from the original image 11. In other words, if the direction of the blur to be added matches the characteristic direction of the spatial frequency characteristics of the original image, the blurred image is likely to be easy to create. Therefore, in the blurred image preparation step S101 of this embodiment, it is preferable to select an original image based on the characteristic direction of the spot to be convolved with the original image when adding blur. This allows the difficulty of creating a blurred image to be appropriately controlled. Specifically, for example, by selecting an original image such that the direction of the blur to be added substantially coincides with the characteristic direction of the spatial frequency characteristics of the original image, it is possible to avoid extremely difficult blurred images in which the difference in appearance is indistinguishable to anyone. In this specification, "substantially coincident" between the direction of the blur to be added 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 images is 0.7 or greater. The blur direction (0° to 180°) refers to the direction in which the blur increases, and is obtained from, for example, the direction in which the variance of the point spread function is greatest. When an original image without line symmetry is used, a sign may be further assigned based on the direction from the peak point of the point spread function to the center of gravity (i.e., the blur direction is set to -180° to 180°).

[0055] In the subjective response acquisition step S102, it is preferable to present multiple blurred images at a size such that the spatial frequency of the main parts of the multiple blurred images is 3 CPD or more and 9 CPD or less (corresponding to visual acuity of 0.1 to 0.3). For example, if a myopic subject is presented with blurred images that are too large to be seen without eyeglasses, it may be difficult to accurately grasp the subject's preferred blur due to factors such as eyeglass accommodation error. In contrast, by presenting blurred images large enough that most subjects can see them without eyeglasses, individual differences in perception are significantly reflected, allowing the subject's preferred blur to be more accurately grasped. Note that, in this specification, the "main parts of a blurred image" refers to characteristic parts of the blurred image that clearly show differences in appearance. Specifically, for example, the text portions and mark edges of the blurred images 10A and 10B shown in FIG. 4 correspond to the main parts. Furthermore, it is preferable to present multiple blurred images at the same size. However, even if there is a slight difference in the magnification of the multiple blurred images (e.g., a magnification of less than 5%), it is sufficient if the subject can distinguish the difference in appearance. Furthermore, a size such that the spatial frequency of the main part of the blurred image is 3 CPD or more and 9 CPD or less (corresponding to visual acuity of 0.1 to 0.3) means, for example, in the case where the original image is composed of line drawings and text, that the width of the main lines that make up the image is 1 / 6 to 1 / 18 degrees of visual angle.

[0056] In the subjective response acquisition step S102, it is preferable to present multiple blurred images at a distance of 0.3 m to 2 m from the subject's eyes without fixing the subject's head. Performing measurements with the subject's head fixed causes tension and increases the subject's burden. Furthermore, because tension in the head muscles and tension in the eye muscles are linked, it may be difficult for the subject to use their eyes in a normal way, making it difficult to accurately grasp the subject's preferred blur. In contrast, performing measurements without fixing the subject's head can reduce the subject's burden. Furthermore, presenting multiple blurred images at a distance where the effect of slight changes in head position (e.g., approximately 3 cm) is negligible can more accurately grasp the subject's preferred blur.

[0057] The answer options for the subjective response in the subjective response acquisition step S102 may include an option of "I don't know the difference" in addition to which image the subject finds preferable. By taking into consideration the response rate of "I don't know the difference," it becomes easier to determine spectacle lenses that are more suitable for the subject in the spectacle lens determination step S103.

[0058] The preference for blur is influenced by the strength of the bias due to the direction of blur. In the subjective response acquisition step S102, it is preferable to grasp the strength of the bias due to the direction of blur. The direction of blur refers to a direction in the range of -180° to 180°, which corresponds to the direction in which the spot tails as shown in FIG. 5. In other words, for example, the left-right direction is distinguished into the right direction and the left direction.

[0059] 8A to 8D and 9A to 9D are diagrams showing examples of blurred images to explain bias due to the direction of blur. An image of text read toward the right on the page (original image) is convolved with a spot trailing downward in FIG. 8A, upward in FIG. 8B, rightward in FIG. 8C, and leftward in FIG. 8D. Also, an image of text read toward the bottom on the page (original image) is convolved with a spot trailing downward in FIG. 9A, upward in FIG. 9B, rightward in FIG. 9C, and leftward in FIG. 9D.

[0060] When a group of subjects were presented with these blurred images, many responded that the degree to which each character was clearly visible was the same for all of Figures 8A to 8D. However, many subjects responded that Figure 8C, in which the spot with a trailing tail to the right is folded over when viewed as a whole, felt more natural and preferable for reading sentences and words. Furthermore, many subjects responded that the degree to which each character was clearly visible was the same for all of Figures 9A to 9D. However, many subjects responded that Figure 9A, in which the spot with a trailing tail to the bottom is folded over when viewed as a whole, felt more natural and preferable for reading sentences and words. In other words, in blurred images containing text, subjects tend to feel less uncomfortable due to the blur if the direction of the blur is consistent with the direction of reading the text. Because the strength of this bias varies from person to person, it is preferable to understand the extent to which subjects have a bias due to the direction of the blur. It is also preferable to consider differences due to the language the subjects normally use.

[0061] As described above, preference for blur is influenced by the strength of the bias due to the direction of blur. From the viewpoint of effectively grasping the influence of the bias due to the direction of blur, it is preferable to ask a question in which the subject is presented with blurred images in which the direction of blur is changed by 180°. Furthermore, the degree of bias due to the direction of blur can be estimated, for example, from the degree of agreement or disagreement of answers when the direction of blur is changed by 180°.

[0062] Furthermore, from the viewpoint of effectively grasping the influence of bias due to the blur direction, it is preferable to pose a question in which the subject is presented with blurred images in which the inner product of the unit direction vector of the blur direction and the characteristic direction of the spatial frequency characteristics of the original image is 0.7 or more and blurred images in which the inner product is -0.7 or less. Specifically, for example, for an original image of text to be read from the right, it is preferable to prepare approximately equal numbers of blurred images with rightward blur added and blurred images with leftward blur added, and present them to the subject.

[0063] (Spectacle Lens Determination Step S103) The spectacle lens determination step S103 is a step of determining spectacle lenses suitable for the subject based on, for example, the subject's subjective response obtained in the subjective response acquisition step S102. In the spectacle lens determination step S103, it is preferable to determine progressive power lenses. This is because progressive power lenses are significantly affected by aberrations, and it is particularly important to consider the subject's preferred tendency for blur.

[0064] In the subjective response acquisition step S102, the subject's subjective response is scored based on whether it matches the average support in the group, and in the spectacle lens determination step S103, spectacle lenses suitable for the subject are preferably determined based on the score. The average support may be a statistical value obtained when a question is previously posed to a group, or may be estimated using machine learning, etc. Specifically, for example, in a question that asks subjects to compare left and right blurred images, if many subjects prefer the left blurred image (high support rate), subjects who answered that the left image is preferred may be given +1 point, etc., as the response matches the average support in the group, and subjects who answered that the right image is preferred may be given -1 point, etc., as the response does not match the average support in the group. Then, the total score and subtotals for each question tendency may be tallied, and, for example, if the score is equal to or greater than a predetermined score (threshold), spectacle lenses of design A may be determined, and if the score is less than the predetermined score (threshold), spectacle lenses of design B may be determined. In other words, spectacle lenses suitable for the subject may be determined based on the magnitude relationship between the score and a predetermined threshold. By assigning scores in this way, preferences for blur can be classified. In addition, the characteristics of the subject can be easily identified, making it easier to provide counseling when deciding on eyeglass lenses.

[0065] It is preferable to assign the same score to questions with the same amount of aberration and difference between the convoluted spots. This makes it easier to understand the dependency on the direction of blur. For example, if a questioner answers that image A appears in one direction and image B appears in another direction, points will be added for one and subtracted for the other, resulting in a total score of 0. In other words, the closer the total score is to 0, the more susceptible the questioner is to compatibility due to direction. Furthermore, the scoring can be finely determined by varying the point allocation for each question. Responses that "I don't know the difference" can be assigned 0 points, or if there are many responses that "I don't know the difference," additional investigations, such as counseling, can be conducted to determine the appropriate eyeglass lenses.

[0066] When determining the appropriate eyeglass lenses for a subject based on the subtotal score and total score, a score threshold is required for recommending a certain design if the score is equal to or greater than a predetermined value, and this threshold may be determined from prior information about the population. For example, the distribution of total scores in a population that prefers eyeglass lenses of design A and eyeglass lenses of design B may be represented by a Gaussian mixture distribution, and the total score and the probability that design A and design B will be preferred may be estimated based on this, and the total score at which the probability of preference for design A and design B is reversed may be set as the threshold.

[0067] Multiple thresholds may be prepared and used according to the measurement environment, etc. For example, multiple thresholds may be prepared and selected according to the type and number of tests performed separately from the subjective response acquisition step S102. In cases such as unmanned measurements using the Internet, the threshold may be the boundary at which the probability of preference for design A and design B changes, as described above. When multiple measurements or counseling are possible, the threshold may be set to a value at which design A or design B is preferred with a sufficiently high probability, and if neither threshold is met, the decision on design selection may be left to another measurement or counseling. Furthermore, the threshold may be updated in accordance with updates to population information.

[0068] In the eyeglass lens selection step S103, it is preferable to present to the subject at least one (preferably both) of the subject's score and the statistical amount of support in all or part of the group in which the preliminary survey was conducted. This allows the subject to know his or her own score and characteristics, making it easier to provide counseling when selecting eyeglass lenses. It is also expected that the subject will be able to use eyeglasses more effectively.

[0069] Furthermore, for subjects who prefer multimodal blur based on the subtotal of scores in the multimodal problem, the design of the eyeglass lens may be optimized using an evaluation function that simply maximizes the (weighted) sum of MTFs, while for subjects who prefer unimodal blur, the design of the eyeglass lens may be optimized using an evaluation function that adds a penalty to the inflection or positive gradient of the MTF curve.

[0070] In the spectacle lens determination step S103, spectacle lenses may be determined taking into consideration the subject's residual refractive error. Specifically, for example, for a subject with a strong refractive error such as astigmatism, spectacle lenses may be determined taking into consideration the possibility that the subject may have difficulty in distinguishing differences in how blurred images appear.

[0071] (2) Spectacle Lens Decision Support System The present invention can also be applied as a spectacle lens decision support system. The spectacle lens decision support system of this embodiment includes, for example, a storage unit that stores multiple blurred images obtained by adding blurring of different tendencies and degrees to a predetermined original image; a display unit that simultaneously presents the multiple blurred images to a subject to compare how they appear; an input unit that inputs the subject's subjective response; a determination unit that determines the subject's preferred blur tendency from the subject's subjective response; and an output unit that outputs information for determining spectacle lenses suitable for the subject based on the subject's preferred blur tendency. The spectacle lens decision support system of this embodiment can be realized, for example, by a tablet terminal or the like equipped with a predetermined program, and has the advantage of low implementation costs. The spectacle lens decision support system of this embodiment may also include, for example, a creation unit that adds blurring of different tendencies and degrees to an original image to create blurred images.

[0072] <Other embodiments of the present invention> Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit of the present invention.

[0073] For example, in another embodiment of the present invention, the method may further include a step (other test S201) of obtaining subjective responses from the subject through one or more tests conducted separately from the subjective response acquisition step S102, and in the spectacle lens determination step S103, spectacle lenses suitable for the subject may be determined based on the subjective responses obtained in the subjective response acquisition step S102 and the subjective responses obtained in the other test S201. Fig. 10 is a flowchart showing an example of a spectacle lens determination method according to another embodiment of the present invention. In other words, spectacle lenses suitable for the subject may not be determined based solely on the preferred tendency for blur, but may be finally determined taking into account the results of other tests. Specific examples of the other test S201 include a test to determine preferences for the degree of distortion of landscape images, a test to determine preferences for shaking in moving images, etc.

[0074] For example, in the above-described embodiment, two blurred images are prepared by adding blurring with different tendencies or degrees to a predetermined original image, and the two blurred images are simultaneously presented to compare their appearances. However, three or more blurred images may be prepared and presented simultaneously to compare their appearances. However, when three or more blurred images are simultaneously presented to compare their appearances, differences due to position within the visual field may become dominant. Furthermore, this may make it difficult for the subject to judge. Therefore, from the viewpoint of reducing differences due to position within the visual field and presenting blurred images that are easy for the subject to judge, it is preferable to simultaneously present two blurred images and compare their appearances, as in the above-described embodiment.

[0075] Furthermore, for example, in the above-described embodiment, the case where the directions of blur added to the multiple blurred images presented simultaneously are substantially the same has been described, but the directions of aberration added to the multiple blurred images presented simultaneously do not necessarily have to be substantially the same. Specifically, for example, a spot without astigmatism may be convoluted into one blurred image, and a spot with astigmatism may be convoluted into the other blurred image. In this case, as in the above-described embodiment, it is easy for the subject to compare how the multiple blurred images appear.

[0076] Furthermore, for example, in the subjective response acquisition step S102 of the above-described embodiment, a score is assigned based on whether the subjective response of the subject matches the average support in the group, and in the spectacle lens determination step S103, spectacle lenses suitable for the subject are determined based on the score. However, such scoring is not necessarily required. For example, spectacle lenses suitable for the subject may be determined by inputting the obtained data of the subject's subjective response into a classifier that has previously undergone machine learning of data linking the subject's subjective response with spectacle lenses of the subject's preferred design. In this case, while accuracy is easily achieved, there is also the disadvantage that the scores are not visualized and become a black box, making it difficult to provide counseling, etc. when determining spectacle lenses.

[0077] For example, the eyeglass lens decision support system may have a device that displays the subject's score and the probability that the selected eyeglasses will be preferred. In this case, the average value and statistics for the group may also be displayed. This is expected to make it easier for the subject to understand their own characteristics and use eyeglasses effectively. Furthermore, by understanding the preference probability, the risk of purchasing the selected eyeglasses can be understood.

[0078] For example, the scores and subjective responses obtained may be recorded in a database or the like. When the subject repurchases eyeglass lenses, the measurement may be omitted and the eyeglass lenses selected may be based on the previous scores. In this case, the threshold value at the time of measurement may be used (i.e., the same lenses as before may be selected if there are no significant differences in other tests or counseling), or the latest updated threshold value may be used.

[0079] Furthermore, for example, the scores and the acquired subjective responses may be converted into two-dimensional barcodes and output, recorded, and transmitted. The subject may perform the subjective response acquisition step S102 in advance at home or the like, save the results as a two-dimensional barcode, and present it to an eyeglass store, thereby enabling the selection of eyeglass lenses with minimal waiting time.

[0080] Next, examples of the present invention will be described. These examples are merely examples of the present invention, and the present invention is not limited to these examples.

[0081] (Blurred image preparation step S101) In this embodiment, two blurred images were presented simultaneously. First, six different original images were prepared. Furthermore, for each of the six pairs of blurred images, the rotation angle was changed to prepare three types of rotated blurred images (four types when combined with the original blurred image), for a total of 24 types of problems. Of the 24 types of problems, 20 were tail length comparison problems and four were multi-peak problems. In addition, there were 16 types of reversal trend problems.

[0082] (Subjective response acquisition step S102) In this example, pairs of blurred images were displayed on the tablet device in random order 24 times, and the subject was asked to compare the appearance and select which one was clearer and preferable (or whether they could tell the difference) 24 times to obtain a subjective response. The blurred images were enlarged to a size such that the spatial frequency of their main parts was about 6 CPD (equivalent to a visual acuity of 0.2), and were presented at a distance of 1 m in front of the subject.

[0083] In this example, the average support was determined using statistical values ​​obtained when a similar question was previously given to a group. If the subject's answer matched the average support of the group, they were given +1 point, and if it did not match the average support of the group, they were given -1 point. If the subject answered "I don't know the difference," they were given 0 points.

[0084] (Spectacle Lens Determination Step S103) In this embodiment, a progressive power lens suitable for the subject was determined based on the subject's total score in the subjective response acquisition step S102. Specifically, for subjects with a total score of 12 points or more, a progressive power lens (design A) having a power distribution (power) and astigmatism distribution (AS) as shown in FIG. 11A was determined, and for subjects with a total score of less than 12 points, a progressive power lens (design B) having a power distribution (power) and astigmatism distribution (AS) as shown in FIG. 11B was determined. As shown in FIG. 11A, the spectacle lens of design A is a lens in which astigmatism is reduced on and near the principal meridian. Also, as shown in FIG. 11B, the spectacle lens of design B is a lens that has astigmatism on the principal meridian but has a wide range on both sides with sufficient near-distance addition power. The threshold value of 12 points was determined by expressing the distribution of total scores in a group of people who prefer eyeglass lenses of design A and eyeglass lenses of design B in a preliminary survey using a mixed Gaussian distribution, estimating the total score and the probability that design A and design B would be preferred based on this, and then determining the total score at which the probability of preference for design A and design B was reversed.

[0085] The percentage of subjects who actually preferred the lenses determined by the above classification (classification accuracy) was 65%. From the above, it was confirmed that by understanding the subject's preferred tendency for blur, it is possible to determine the eyeglass lenses that are suitable for the subject.

[0086] As another example of the spectacle lens selection step S103, a case where the threshold value was changed is shown. Specifically, for subjects with a total score of 14 points or more, a progressive power lens (design A) having a power distribution (power) and astigmatism distribution (AS) as shown in FIG. 11A was selected. For subjects with a total score of less than 10 points, a progressive power lens (design B) having a power distribution (power) and astigmatism distribution (AS) as shown in FIG. 11B was selected. For subjects with a total score that did not fall into either category, design A or design B was selected based on the results of other tests and counseling. As another test, 20 subjective response questions were asked to select which of two unblurred images, each with different distortions applied to the original image, the subject preferred. Note that the number of questions from other tests is not included in the calculation of the percentage of each question in the subjective response acquisition step S102.

[0087] The percentage of subjects who actually preferred the lenses determined by the above classification (classification accuracy) was 76%. From the above, it was confirmed that by understanding the subject's preferred blur tendency and changing (selecting) the threshold value according to the results of other measurements and counseling, it is possible to determine the eyeglass lenses that are suitable for the subject with higher accuracy.

[0088] 10, 11 Original image 10A, 10B Blurred image 20A, 20B, 21A, 21B, 22A, 22B Rotation blurred image S101 Blurred image preparation step S102 Subjective response acquisition step S103 Spectacle lens determination step S201 Other test

Claims

1. A method for determining eyeglass lenses, comprising: a step (a) of preparing a plurality of blurred images to which blurring of different tendencies and degrees has been added for a given original image; a step (b) of simultaneously presenting the plurality of blurred images to a subject and asking the subject to compare how they appear, thereby obtaining a subjective response from the subject; and a step (c) of determining eyeglass lenses suitable for the subject based on the subjective response obtained in step (b), wherein in step (b), questions presenting a plurality of blurred images for which subjects tend to answer that blurred images with a greater degree of blurring added are preferable account for more than half of all questions.

2. A method for determining eyeglass lenses, comprising: a step (a) of preparing a plurality of blurred images to which blurring of different tendencies and degrees has been added for a given original image; a step (b) of simultaneously presenting the plurality of blurred images to a subject and asking the subject to compare how they appear, thereby obtaining a subjective response from the subject; and a step (c) of determining eyeglass lenses suitable for the subject based on the subjective response obtained in step (b), wherein in step (b), the questions presenting a plurality of blurred images with blur tails of different lengths account for more than half of all the questions.

3. A method for determining eyeglass lenses, comprising: a step (a) of preparing a plurality of blurred images by adding blur of different tendencies and degrees to a predetermined original image; a step (b) of simultaneously presenting the plurality of blurred images to a subject and asking them to compare how they appear, thereby obtaining a subjective response from the subject; and a step (c) of determining eyeglass lenses suitable for the subject based on the subjective response obtained in step (b), wherein in step (a), a plurality of rotationally blurred images are further prepared by rotating the blurred image by an arbitrary angle, rotating only the direction of the blur to be added without changing the original image, or rotating the original image without changing the blur to be added; and in step (b), a question is asked in which the plurality of blurred images are simultaneously presented to the subject and asked to compare how they appear, and a question is asked in which the plurality of rotationally blurred images are simultaneously presented to the subject and asked to compare how they appear.

4. A method for determining a spectacle lens according to any one of claims 1 to 3, further comprising a step (d) of obtaining a subjective response from the subject through one or more tests conducted separately from step (b), wherein step (c) determines spectacle lenses suitable for the subject based on the subjective responses obtained in step (b) and step (d).

5. A method for determining a spectacle lens according to any one of claims 1 to 3, wherein step (b) includes a problem of presenting a blurred image to which multi-peak blur has been added and a blurred image to which uni-peak blur has been added.

6. The method for determining eyeglass lenses according to claim 1 or claim 2, wherein in step (a), a plurality of rotationally blurred images are further prepared by rotating the blurred image by an arbitrary angle, rotating only the direction of the blur to be added without changing the original image, or rotating the original image without changing the blur to be added, and in step (b), a problem is included in which the plurality of blurred images are simultaneously presented to the subject and the subject is asked to compare how they appear, and a problem is included in which the plurality of rotationally blurred images are simultaneously presented to the subject and the subject is asked to compare how they appear.

7. A method for determining a suitable eyeglass lens according to any one of claims 1 to 3, wherein in step (b), the subject's subjective response is scored based on whether it coincides with average support in a group, and in step (c), suitable eyeglass lenses for the subject are determined based on the score.

8. The method for determining a suitable eyeglass lens according to claim 7, wherein in step (c), at least one of the scores and statistics of support in all or part of the population is presented to the subject.

9. The method for determining eyeglass lenses according to claim 7, wherein in step (c), eyeglass lenses suitable for the subject are determined based on the magnitude relationship between the score and a predetermined threshold value.

10. The method for determining a spectacle lens according to claim 9, wherein a plurality of threshold values are prepared, and the threshold value is selected according to the type and number of tests to be performed separately from step (b).

11. A method for determining a spectacle lens according to any one of claims 1 to 3, wherein in step (a), the original image is selected according to a characteristic direction of a spot to be convolved with the original image when blurring is added.

12. A method for determining a spectacle lens according to any one of claims 1 to 3, wherein step (c) determines a progressive power lens.

13. A method for determining a spectacle lens according to any one of claims 1 to 3, wherein in step (b), the plurality of blurred images are presented at a size such that the spatial frequency of the main parts of the plurality of blurred images is 3 CPD or more and 9 CPD or less.

14. A method for determining a suitable eyeglass lens according to any one of claims 1 to 3, wherein in step (b), the subject's head is not fixed and the plurality of blurred images are presented at a distance of 0.3 m or more and 2 m or less from the subject's eyes.

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