Methods of evaluating, designing, and calculating visual perception properties of lenses

Abstract

The present invention provides an evaluation method capable of objectively evaluating the average visual perception of a subject when looking through an eyeglass lens to be evaluated for a relatively long period of time, the time-dependent change in visual perception, and the visual perception when looking with both eyes, and provides a design method, and provides a calculation method for calculating the visual perception characteristics of a subject when looking at an object through a lens. The subject is made to induce brain activity by having the subject look through an eyeglass lens to be evaluated at a visual stimulus that induces a change in periodic brain activity, and the current change caused by the brain activity is recorded in the form of a change in a magnetic field (magnetic flux density) in a time-dependent manner by using a brain magnetic wave recorder; one or more of the amplitude, the dioptric value, and the frequency phase, the frequency being the inverse of the period of the periodic brain activity, is calculated by fast Fourier analysis of the waveform, and the eyeglass lens to be evaluated and the visual perception characteristics of the subject are evaluated based on the magnitude of the amplitude or dioptric value obtained above or based on the slowness / fastness of the phase obtained above.

Description

[0001] This application is a divisional application of the patent application with application number 201480054731.2. TECHNICAL FIELD

[0002] The present application relates to an evaluation method for evaluating eyeglass lenses by induced activity in the homeostasis of the brain, a design method for designing eyeglass lenses using the evaluation method, and a calculation method for calculating the visual perception characteristics of a subject when viewing an object through a lens. BACKGROUND

[0003] In the performance evaluation of the experimental design in designing and developing eyeglass lenses, or in the product comparison when a user considers purchasing eyeglass lenses, it is desirable to employ a technique to objectively evaluate how well the visual scene is actually perceived visually by the lens design. A human being views an object with both eyes, so it is also desirable to objectively evaluate the visual perception when the object is viewed with both eyes. It is also desirable to provide eyeglass lenses suitable for a user by calculating the visual characteristics of the user, or by employing objective numerical values to calculate how the user's visual line is utilized when the user purchases eyeglass lenses. The reason is that if the visual characteristics of the user and how the user's visual line is utilized are known in advance, it is easy to select eyeglasses suitable for the user.

[0004] A visual acuity test using, for example, Landolt rings, "E" marks, or Hiragana, which is an existing method of determining the visual perception of a user, is performed, so it is possible to determine how well the user visually perceives such an object through a lens according to the subjectivity of the user. In addition, the use of, for example, an autorefractor enables objective measurement of the refractive power of the user's eye.

[0005] REFERENCE LIST

[0006] Patent Document

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2012-152568

[0008] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2013-11877

[0009] Patent Document 3: Japanese Unexamined Patent Application Publication No. H11-125799 SUMMARY

[0010] TECHNICAL PROBLEM

[0011] However, in the aforementioned existing visual acuity determination methods, the visual acuity is often determined in the form of the instantaneous maximum visual acuity during the measurement performed in a short period of time, and when the visual acuity is determined by using, for example, Landolt rings, the visual acuity is sometimes considered to be trained if the Landolt rings are recognized (even instantaneously). The same applies to the case where the diopter of the eye is objectively measured with an autorefractor and the measurement is performed based on the tear state on the surface of the eye during the measurement, and the visual acuity sometimes changes only instantaneously.

[0012] Further, it is known that the visual acuity decreases due to reading and driving, continuous use of the eyes in the operation of a personal computer or the like, drying of the surface of the eyes, or muscle fatigue caused by adjustment, and the visual perception changes by blinking or the like. Therefore, it is important to evaluate the degree of good in visually perceiving an object for a slightly longer period of time, or to evaluate how the visual perception changes over time, rather than evaluating the instantaneous visual perception during the measurement.

[0013] Patent Document 1 is an example of a solution for addressing these problems for the first time. Patent Document 1 proposes measuring functional visual acuity by displaying an indication mark (for example, Landolt rings), by receiving the subject's response with an input device, by judging whether the response is correct, and by repeatedly giving indication marks different in size from each other. The technology proposed by this patent document is meaningful in that it is possible to measure the time-dependent change in visual acuity, and it is possible to calculate the time-dependent change in visual perception or to calculate the average visual perception in a time unit by integrating the time-dependent change in the visual acuity value required for the measurement without calculating the instantaneous visual perception. However, the evaluation method of Patent Document 1 depends on the subjective judgment of whether the indication mark (for example, Landolt rings) is recognized, and therefore it is difficult to objectively evaluate the true state of the visual perception of the subject.

[0014] Patent Document 2, which is a prior invention accomplished by the present inventor, is mentioned as a method for objectively evaluating visual perception through eyeglass lenses. Patent Document 2 discloses that when a subject views a visual stimulus object through a lens to be evaluated, the evoked activity of the visual cortex of the brain is measured with an electroencephalograph or a magnetoencephalograph, and so on, and the eyeglass lenses are evaluated based on the amplitude of the activity (amplitude) or based on the period of time (latency) from the reception of the visual stimulus to the appearance of a change in the activity. This eyeglass lens evaluation technique disclosed by Patent Document 2 is meaningful in that, without utilizing spontaneous brain activity, the extremely fine visual perception through the lenses can be objectively evaluated by evoking brain activity. However, the visual evoked potential or the visual evoked magnetic field is used to evoke the brain activity so as to average the electroencephalogram or the magnetoencephalogram that appears after the display of the visual stimulus, and therefore it is disadvantageously required that the subject control blinking (i.e., the subject is required to be trained) according to the display of the stimulus image and the measurement time becomes long because it is generally necessary to perform averaging of more than fifty times, and it is required to creatively evaluate the upper part of the lenses because the reaction of the lower visual field is much more than that of the upper visual field in most cases.

[0015] Furthermore, as disclosed in Patent Document 3, it is desirable to make lenses for both eyes that are easy to use, taking into account the aberration distribution of progressive addition lenses when viewing an object with both eyes. However, it is disadvantageously impossible to objectively evaluate the visual perception when actually viewing an object with both eyes through the progressive addition lenses, although there have been some proposals to simulate the visual perception of both eyes based on optical design techniques.

[0016] The present invention was accomplished in view of these problems in the related art. An object of the present invention is to provide an evaluation method that can objectively evaluate the average visual perception obtained over a relatively long period of time when a subject views an object through eyeglass lenses to be evaluated, can objectively evaluate the time-dependent change in the visual perception, and can objectively evaluate the visual perception when the subject views an object with both eyes; and to provide a design method that utilizes the evaluation method; and to provide a calculation method for calculating the visual perception characteristics of a subject when viewing an object through lenses.

[0017] SOLUTION TO THE PROBLEM

[0018] To solve the aforementioned problems, the gist of the first aspect is that the evaluation method includes: causing the subject to wear the lens to be evaluated, causing the subject to induce brain activity by causing the subject to view, through the lens to be evaluated, a visual stimulus that induces periodic changes in brain activity; obtaining the brain activity in the form of a waveform of an electrical signal; calculating one or more of an amplitude, a dioptric value, and a frequency phase, the frequency being the inverse of the period of the periodic brain activity, by analysis of the waveform; and evaluating the lens to be evaluated based on the magnitude of the amplitude or dioptric value obtained above or on the slowness / quickness of the phase obtained above.

[0019] The gist of the second aspect is that, in addition to the arrangement of the first aspect, a point at which the subject gazes (hereinafter, referred to as a "gaze point") is presented to the subject when the subject views the visual stimulus through the lens to be evaluated.

[0020] The gist of the third aspect is that, in addition to the second aspect, the display is a movable gaze point, and the subject is caused to view the gaze point while the subject moves the line of sight.

[0021] The gist of the fourth aspect is that, in addition to the second aspect or the third aspect, the visual stimulus is set to be movable.

[0022] The gist of the fifth aspect is that, in addition to any one of the first aspect to the fourth aspect, the visual stimulus is viewed with both eyes.

[0023] The gist of the sixth aspect is that, in addition to the fifth aspect, one or more of the amplitude, the dioptric value, and the phase obtained as a result of viewing the visual stimulus with both eyes and analyzed are evaluated by comparison with one or more of the amplitude, the dioptric value, and the phase obtained as a result of viewing the visual stimulus with one eye and analyzed.

[0024] The gist of the seventh aspect is that, in addition to the fifth aspect, one or more of the amplitude, the dioptric value, and the phase obtained as a result of viewing the visual stimulus with both eyes and analyzed are evaluated by comparison with one or more of the amplitude, the dioptric value, and the phase obtained as a result of viewing the visual stimulus through lenses having mutually different states with the left eye and the right eye and analyzed.

[0025] The gist of the eighth aspect is that, in addition to any one of the fifth aspect to the seventh aspect, the balance of visual perception between the two eyes is evaluated using one or more of the amplitude, the dioptric value, and the phase obtained as a result of viewing the visual stimulus with both eyes and analyzed.

[0026] The gist of the ninth aspect is that, in addition to the first aspect to the eighth aspect, one or more of the amplitude, the dioptric value, and the phase obtained as a result of viewing the visual stimulus with the dominant eye and which have been analyzed are evaluated by comparison with one or more of the amplitude, the dioptric value, and the phase obtained as a result of viewing the visual stimulus with the non-dominant eye and which have been analyzed.

[0027] The gist of the tenth aspect is that, in addition to any one of the first aspect to the ninth aspect, in the analysis of the waveform, a time unit for analysis (hereinafter, this time unit will be referred to as an "analysis window") that is smaller than the total measurement time is set, and the analysis is performed using the unit of the analysis window.

[0028] The gist of the eleventh aspect is that, in addition to any one of the first aspect to the tenth aspect, a plurality of lenses to be evaluated that are defined in the foregoing aspects and have mutually different lens characteristics are prepared.

[0029] The gist of the twelfth aspect is that, in addition to any one of the first aspect to the eleventh aspect, the visual stimulus is composed of one line segment or a plurality of line segments, and the visual perception that varies based on the axial direction of astigmatism is evaluated.

[0030] The gist of the thirteenth aspect is that, in addition to any one of the first aspect to the eleventh aspect, the visual stimulus is composed of one circle or a plurality of circles, and the size of the astigmatism component is evaluated without evaluating the visual perception that varies based on the axial direction of astigmatism.

[0031] The gist of the fourteenth aspect is that, in addition to the twelfth aspect, the visual perception that varies based on the axial direction of astigmatism is evaluated by alternately displaying a first figure and a second figure that are components of the visual stimulus, wherein the first figure is composed of one line segment or a plurality of line segments with which directionality of a direction is perceivable, and the second figure is composed of one line segment or a plurality of line segments with which directionality of a direction that is different from the directionality of the first figure is perceivable.

[0032] The gist of the fifteenth aspect is that, in addition to the thirteenth aspect, the size of the astigmatism component is evaluated without evaluating the visual perception that varies based on the axial direction of astigmatism by alternately displaying a first figure and a second figure that are components of the visual stimulus, wherein the first figure is composed of one circle or a plurality of circles with which directionality is not perceivable, and the second figure is composed of one circle or a plurality of circles with which directionality that is different from the directionality of the first figure in arrangement is not perceivable.

[0033] The gist of the sixteenth aspect is, in addition to any one of the first aspect to the fifteenth aspect, presenting the visual stimulus in a second eye position of the subject or in a third eye position of the subject.

[0034] The gist of the seventeenth aspect is, in addition to any one of the first aspect to the sixteenth aspect, continuously displaying the visual stimulus without providing a period in which the visual stimulus is not displayed.

[0035] The gist of the eighteenth aspect is, in addition to any one of the first aspect to the sixteenth aspect, discontinuously displaying the visual stimulus by providing a period in which the visual stimulus is not displayed.

[0036] The gist of the nineteenth aspect is, in addition to any one of the first aspect to the eighteenth aspect, the visual stimulus is composed of a plurality of and two or more types of visual stimuli, and the plurality of visual stimuli are equal in luminance to each other.

[0037] The gist of the twentieth aspect is, in addition to any one of the first aspect to the nineteenth aspect, the frequency of the inverse of the period of the periodic brain activity is 4 to 60 Hz.

[0038] The gist of the twenty-first aspect is, in addition to the twentieth aspect, the frequency of the inverse of the period of the periodic brain activity is 4 to 7 Hz or 14 to 19 Hz.

[0039] The gist of the twenty-second aspect is, in addition to any one of the first aspect to the twenty-first aspect, the lens to be evaluated is a progressive addition lens.

[0040] The gist of the twenty-third aspect is, in addition to any one of the first aspect to the twenty-second aspect, the brain activity is a visual evoked magnetic field in a steady state.

[0041] The gist of the twenty-fourth aspect is, in addition to any one of the first aspect to the twenty-second aspect, the brain activity is a visual evoked potential in a steady state.

[0042] The gist of the twenty-fifth aspect is, designing an eyeglass lens according to the evaluation method of any one of the first aspect to the twenty-fifth aspect and based on the evaluation result of the calculation.

[0043] The gist of the twenty-sixth aspect is, in addition to the twenty-fifth aspect, the designing method includes:

[0044] a first step of obtaining, as a result of analyzing two or more types of lenses to be evaluated, a difference between an optical performance value of a highest evaluation lens among the lenses to be evaluated and another lens among the lenses to be evaluated;

[0045] The second step: a part of the difference obtained in the first step is given as a correction value of the optical performance value of the highest evaluation lens therein, and a new lens shape is calculated using the corrected optical performance value as a design target value, thereby setting a reference lens to be evaluated;

[0046] The third step: in the following items (A) and (B), a difference in the optical performance value between the highest evaluation lens among the lenses to be evaluated and another lens among the lenses to be evaluated is obtained.

[0047] (A) the reference lens to be evaluated and the highest evaluation lens therein,

[0048] (B) the reference lens to be evaluated, the highest evaluation lens therein, and one or more newly added lenses to be evaluated;

[0049] The fourth step: a part of the difference obtained in the third step is given as a correction value of the optical performance value of the highest evaluation lens therein, and a new lens shape is calculated using the corrected optical performance value as a design target value, thereby setting a reference lens to be evaluated, wherein while the third step and the fourth step are repeatedly performed, an eyeglass lens suitable for the subject is designed by reducing the difference.

[0050] The gist of the twenty-seventh aspect is that the calculation method includes: causing the subject to wear a predetermined lens; causing the subject to induce brain activity by causing the subject to view, through the lens, a visual stimulus that induces a periodic change in brain activity; obtaining the brain activity in the form of a waveform of an electric signal; calculating one or more of an amplitude, a dioptric value, and a frequency phase by analysis of the waveform, the frequency being the inverse of the period of the periodic brain activity, and calculating a visual perception characteristic of the subject when viewing an object through the lens based on a magnitude of the above-obtained amplitude or dioptric value or based on a slowness / fastness of the above-obtained phase.

[0051] The gist of the twenty-eighth aspect is that, in addition to the twenty-seventh aspect, a lens is designed based on the visual perception characteristic of the subject measured in the twenty-seventh aspect.

[0052] In the foregoing arrangement, first, the subject wears the lens to be evaluated, and the subject is induced to brain activity by having the subject view a visual stimulus that induces periodic brain activity changes through the lens to be evaluated, and the brain activity is obtained in the form of a waveform of an electric signal while the subject views the visual stimulus that induces periodic brain activity changes. Although the waveform of the electric signal contains information on many wavelength regions, one or more of an amplitude, a dioptric value, and a frequency phase, which is the inverse of the period of the periodic brain activity, are calculated by analysis. In other words, for example, if the periodic brain activity is performed with a period of 250 ms (milliseconds), the frequency of the change for each unit (here, 1 second) is 1 / 0.25 = 4 Hz, and thus one or more of the amplitude, the dioptric value, and the phase at 4 Hz frequency are calculated as a result of the analysis in this case. Although 4 Hz is required, the amplitude, the dioptric value, and the phase at other frequencies can be calculated in conjunction with this frequency. The lens is evaluated on the basis of the magnitude of the amplitude or the dioptric value or on the basis of the slowness / fastness of the phase obtained in this way. At this time, the lens condition becomes more ideal in proportion to the increase in the strength of the calculated amplitude or dioptric value. The reason is that, when the subject views the visual stimulus that induces periodic brain activity changes as a visual stimulus, the periodicity given as a stimulus is efficiently transmitted to the visual cortex of the brain as one information in the lens having an ideal condition. Furthermore, in comparison with the compared lens, the lens condition becomes more ideal in proportion to the increase in the slowness / fastness of the calculated phase. The reason is that, when the subject views the visual stimulus that induces periodic brain activity changes as a visual stimulus, the periodicity given as a stimulus is rapidly transmitted to the visual cortex of the brain as one information in the lens having an ideal condition. In the embodiments described later, for example, the lens can also be evaluated in a manner other than the magnitude of the amplitude, that is, in a manner using the magnitude of the dioptric value or using the slowness / fastness of the phase. Furthermore, preferably, the evaluation is performed using a combination of two or more evaluation results, for example, a combination of the amplitude and the phase or a combination of the dioptric value and the phase, and is not limited to a case in which the amplitude, the dioptric value, and the phase are used for evaluation individually, because it is possible to reduce the influence of measurement noise.

[0053] Here, the term "dioptric value" represents the magnitude of the energy of one component of the frequency and the dimension is the square of the amplitude. Although the dioptric value relates to a value that is approximately the square of the amplitude in most cases, the dioptric value can also be processed by conversion into, for example, a value per unit time or a value per normalized frequency.

[0054] The slowness / fastness of the phase can be confirmed, for example, in the form of a difference (gap) between two or more phases or in the form of a difference (gap) from the average value of past phases obtained in, for example, data form.

[0055] Further, based on the magnitude of the amplitude or the dioptric value or the phase-based slowness / fastness, the evaluation value can be calculated by simultaneously recording and comparing a plurality of brain areas (even in a single measurement). Therefore, it is preferable to simultaneously measure a plurality of brain areas. For example, in the primary visual cortex and the tertiary visual cortex, the tertiary visual cortex generally shows greater brain activity with respect to complex visual information, and therefore it is preferable to obtain the evaluation value by comparing the amplitude or the dioptric value between the primary visual cortex and the tertiary visual cortex when viewing a complex image. Further, for example, in the primary visual cortex and the sixth visual cortex, visual information is generally transmitted faster in the primary visual cortex than in the sixth visual cortex, and therefore it is preferable to obtain the evaluation value by comparing the phase between the primary visual cortex and the sixth visual cortex. The combination of brain areas for evaluation is one example, and the present application is not limited thereto. Here, preferably, in order to induce periodic brain activity, the subject is caused to view a visual stimulus that induces brain activity of the subject at a frequency of four times or more per second (i.e., a period of 250 milliseconds or less). When the visual stimulus is presented, the neuronal activity in the brain visual cortex ends within approximately 300 milliseconds or less, and therefore if the visual stimulus is presented at a frequency of four times or more per second, the neuronal activity of the next visual stimulus is induced before the neuronal activity of the previous visual stimulus ends, and the reason is that neuronal activity cannot be induced by a single visual stimulus but periodic brain activity is induced. Here, preferably, the frequency (period) of the change in the visual stimulus viewed by the subject is set based on the frequency (period) of the periodic brain activity for analysis. Thereby, the period of the neuronal activity of the brain area of the target brain visual cortex can be established. Further, the frequency (period) of the change in the visual stimulus viewed by the subject can be a frequency that has a multiple relationship with the period of the neuronal activity, and is not limited to synchronization with the period of the target neuronal activity. In this case, the same effect is also similarly achieved.

[0056] For example, in a case where 20 Hz brain activity (i.e., a period of 50 milliseconds) is intended to be induced as periodic brain activity and the brain activity is analyzed, the subject is caused to view one visual stimulus, whereby the neuronal activity of the brain area of the target brain visual cortex at a period of 50 milliseconds becomes substantially the same, and therefore neuronal activity occurs in the brain visual cortex at a period of 50 milliseconds.

[0057] Here, the term "analysis" in the present application represents decomposing the waveform of the electrical signal of each frequency, and obtaining the waveform of the frequency component that is the reciprocal of the variable period. In one analysis technique, the amplitude, the dioptric value, and the phase can be calculated by decomposing the waveform obtained using, for example, Fourier analysis (including discrete Fourier analysis) for each frequency, wavelet analysis, or Hilbert transform.

[0058] The term "changing visual stimulus" generally represents an image that includes a change in a graphic shape or color, alone or in combination, a change in brightness and contrast, and in this context the term is also and only includes the concept of a light spot without a shape such as a graphic. Such a change can be caused by repeatedly performing "display" and "non-display" even if the same image is used. Furthermore, instead of "display" and "non-display", such a change can also be achieved by alternately changing the brightness, color, and shape while continuing to display. Possible examples of the image include a line segment composed of a simple graphic such as a check pattern or a square pattern, a combination of squares pointing outward, and a plurality of circles (which can or can not point outward). Furthermore, instead of a simple image such as a check, a straight line, or a circle, a complex image such as a display of a landscape or a person's face can also be used. For example, it is known that if a distant landscape is displayed, the eye can be brought into a relaxed state, and if a person's face is displayed, a unique brain response can be measured, for example, in the VOR, and thus the complex image can be used as a visual stimulus.

[0059] The change in the visual stimulus can be added to the more specific evaluation of the astigmatism component of the lens. The astigmatism component of the lens represents, for example, astigmatism that occurs at the outer periphery of the spherical lens and that occurs at the lateral portion of the progressive addition lens, and is not limited to astigmatism in the prescribed refractive power of the lens (C power). The astigmatism component, that is, the astigmatism is due to a difference in the image formation on the retina between the maximum meridian having the strongest refractive power and the minimum meridian having the weakest refractive power, and the difference in the refractive power between the maximum meridian and the minimum meridian is the astigmatism difference, and half of the difference in the refractive power between the maximum meridian and the minimum meridian is the astigmatism. The astigmatism component or the astigmatism has a directionality, and the directionality thereof is shown by the axis of the astigmatic vision and the axis of the astigmatism.

[0060] The visual perception that changes based on the axial direction of the astigmatism can be evaluated, for example, by a visual stimulus (image) that forms one or a plurality of line segments that make the perception of the directionality possible. This utilizes the change in the intensity of the early visual cortical neuron activity of the brain caused by the difference in the visual perception because the line segment has a direction that is easy to view based on the axial direction of the astigmatism, that is, the line segment formed on the retina as a clear image, and a direction that is difficult to view based on the axial direction of the astigmatism, that is, the line segment formed on the retina as a defocused image, is obtained by using the line segment as a visual stimulus that makes the perception of the directionality possible.

[0061] Further, in the case where the visual perception that varies depending on the axial direction of astigmatism is not evaluated, the magnitude of the astigmatism component can be evaluated, for example, by a visual stimulus (image) that forms one or a plurality of circles. If the visual stimulus is a line segment, the line segment has directionality, and thus the image formation state on the retina varies depending on the axial direction of astigmatism, and if the visual stimulus is a circle, the circle does not have directionality, and thus if the magnitude of astigmatism is equal and there is a difference in the axial direction, substantially the same image formation state is reached, although a slight effect is caused in rotating the image formation state on the retina, such as Listing's law, and thus the neuron activity intensity of the early visual cortex of the brain does not depend on the axial direction of astigmatism and is affected by the magnitude of astigmatism and other aberrations (for example, refractive error). Thus, in the case where the visual perception that varies depending on the axial direction of astigmatism is not evaluated, the magnitude of the astigmatism component can be evaluated by a visual stimulus that forms one or a plurality of circles.

[0062] Further, in the evaluation thus performed, it is preferable to make the evaluation by alternately displaying a first pattern that is equal in luminance throughout the visual stimulus and a second pattern that is different from the first pattern, because the effect of luminance can be removed from the brain reaction.

[0063] The process of obtaining brain activity in the form of a waveform of an electric signal specifically represents a process of time-dependently recording, with an electroencephalograph, a change in a minute electric current caused by brain activity having an electroencephalic wave as a change in electric potential (voltage), or a process of time-dependently recording, with a magnetoencephalograph, a brain magnetic field as a change in a magnetic field (a change in magnetic flux density).

[0064] Here, the visual stimulus that induces a change in periodic brain activity must be output with accurate time timing, and the period of the periodic brain activity must have such a period that is perceived by the brain of the subject. If the period is too short, a change in state cannot be transmitted to the brain of the subject, and thus the periodic induced brain activity required here cannot be obtained. Therefore, the frequency is preferably 4 to 60 Hz, more preferably 4 to 7 Hz or 14 to 19 Hz. The range of 8 to 13 Hz is a range in which a response appears in spontaneous brain activity (so-called α wave range), and it becomes difficult to draw a difference between spontaneous brain activity and induced periodic brain activity here, and thus there is a case in which brain activity other than induced periodic brain activity is measured in 20 Hz and 30 Hz, and thus 4 to 7 Hz or 14 to 19 Hz is adopted so as to avoid such a case. Among 4 to 7 Hz and 14 to 19 Hz, it is preferable to adopt the range of 14 to 19 Hz, which is a frequency domain in which the number of occurrences of spontaneous brain waves is smaller than that of the range of 4 to 7 Hz. Furthermore, when a visual stimulus is presented at a frequency of 30 to 60 Hz, the switching (flickering) between images that is the visual stimulus does not bother the subject or does not let the subject perceive visually, and thus it is desirable to perceive only through brain response, when intending to reduce fatigue caused by the visual stimulus or when intending to reduce deviation in the line of sight.

[0065] As for the lens to be evaluated, the periodic brain activity measured for a single lens to be evaluated can be evaluated, or the periodic brain activity measured for a plurality of prepared lenses to be evaluated that are different from each other in lens properties can be evaluated. This evaluation does not necessarily lead to the selection of a lens with the best result. Here, the point lies in the fact that the evaluation can obtain objective information about visual perception through the lens.

[0066] Further, it is recommended to present a fixation point when the subject views the visual stimulus through the lens to be evaluated. Preferably, the visual stimulus that induces a change in periodic brain activity is included in the peripheral field of view of 8 degrees or more, not in the central field of view (4 degrees or less) in the subject's field of view, and in this case occupies a relatively large range, so it is recommended to set the fixation point so as to ensure that the subject views the inside of the visual stimulus. If the fixation point is not provided, the line of sight will move unconsciously at the same time as the switching between the visual stimulus, and it will become difficult to measure the target brain response, and the movement of the line of sight during the measurement will cause noise. Specifically, in order to perform the measurement while reducing the noise, it is preferable to display the fixation point in front of the visual stimulus that induces a change in periodic brain activity, and it is preferable to command the subject to not view the visual stimulus that induces a change in periodic brain activity in the background but to view the fixation point. However, in a case where the subject is a child or in a case where the line of sight is not easily fixed, the measurement can be performed with less noise when the fixation point is not displayed, so it is important to appropriately adjust the display of the fixation point based on the subject.

[0067] Further, it is recommended to adopt a display method in which the visual stimulus is movably displayed and the subject is caused to view the moving visual stimulus while moving the line of sight of the subject. The reason is that the visual perception through the lens to be evaluated when the line of sight is moved can be objectively evaluated. At this time, it is preferable to move the fixation point displayed in front along with the visual stimulus. The visual stimulus that induces periodic brain activity and functions as a background moves together with the fixation point, and the subject is caused to follow the visual stimulus with the line of sight, so if the visual perception through the lens is the same, the image formation state on the retina will become substantially constant based on the direction of the line of sight. Therefore, it is possible to evaluate the visual perception at one position on the lens through which the line of sight has passed by moving the stimulus functioning as a background. Further, it is preferable to cause the subject to view the visual stimulus with both eyes, because it becomes the same condition as in actual viewing. When the object is viewed with both eyes at the same time as seen from the side, as FIG. 15The coordinate of the line of sight passing through the lens is different between the right eye and the left eye, as shown in the middle, and thus a difference in the visual perception is generated between the right eye and the left eye, and thus it is important to objectively measure the visual perception with both eyes. Furthermore, it is preferable to evaluate one or more of the amplitude, the dioptric value, and the phase obtained by viewing the visual stimulus with both eyes and which have been analyzed by comparison with one or more of the amplitude, the dioptric value, and the phase, because the difference in the visual perception between viewing with both eyes and viewing with one eye is evaluated, or the difference in the visual perception between the non-dominant eye and the dominant eye is evaluated. It is preferable to have the dominant eye and the non-dominant eye alternately wear lenses having mutually different conditions at this time in order to make a comparison, because it is possible to evaluate the difference in the visual perception between the dominant eye and the non-dominant eye. Furthermore, it is possible to evaluate the balance of the visual perception of both eyes using one or more of the amplitude, the dioptric value, and the phase obtained by viewing the visual stimulus with both eyes and which have been analyzed. Although an unclear visual perception is often provided when viewing the stimulus with both eyes, even if an excellent visual perception is obtained when viewing with each single eye, the application of the present application can make an evaluation in order to adjust the balance of the visual perception of both eyes in such a case. In other words, it is possible to make an evaluation as to whether both eyes are in a truly excellent visually perceptible state.

[0068] Here, the term "dominant eye" is a feature known to assume that a human is part in the same way as the "dominant hand", and is an eye that is more unconsciously used among both eyes when looking with both eyes. The dominant eye can be determined, for example, by judging which eye among both eyes is used for viewing a point while pointing at a point at about several meters away. In many cases, the dominant eye is the same as the dominant eye that is preferentially processed between the right eye and the left eye, and there are also cases in which the dominant eye is sometimes different from the dominant eye. In such a case, for example, it is preferable to have the dominant eye and the non-dominant eye alternately wear mutually different lenses, respectively, for comparison of the dominant eye and the non-dominant eye.

[0069] Furthermore, it is preferable to present the visual stimulus at a second eye position or a third eye position of the subject. The first eye position represents a state in which the subject views the front, the second eye position represents any one of the cases in which the subject views the upper, lower, right, and left axes, and the third eye position represents a case in which the subject views in a diagonal direction. In each lens, of course, the front is better viewed, the reason being that it becomes important to have the subject firmly view such a range in the lens through other dioptric power, as in a progressive addition lens. In a single vision lens, the reason is that the visual perception becomes important not at the center of the lens (first eye position) but at the peripheral portion of the lens, and thus can be objectively evaluated.

[0070] Further, when the subject is caused to view the visual stimulus, it is preferable to continuously display the visual stimulus without providing a period during which the visual stimulus is not displayed. The reason for this is that the brain reaction caused by the display and non-display of the stimulus is removed from the measurement results by continuing to display the stimulus, and stable measurement results are obtained. In this case, the brain reaction caused by the change in luminance is also removed from the measurement results and only the brain reaction in visual perception is measured, specifically by displaying a visual stimulus of the same luminance.

[0071] Further, it is preferable to non-continuously display the visual stimulus by providing a period during which the visual stimulus is not displayed. The reason for this is that a stronger brain reaction can be measured because the change in luminance when the visual stimulus is displayed and not displayed is applied to the visual stimulus.

[0072] Further, in the waveform analysis, it is preferable to set the analysis window used in the analysis to be smaller than the total measurement time and perform the analysis using the analysis window unit. The numerical conversion of the average visual perception can be objectively performed by widely setting the analysis window in a slightly longer time. On the other hand, by more narrowly setting the analysis window and by analyzing the measurement results with a plurality of windows, the time-dependent change in visual perception can be objectively measured based on the brain reaction. At this time, by performing the analysis while continuously moving the analysis window, the time-dependent change in visual perception can be more finely evaluated.

[0073] Further, in the aforementioned arrangement, the subject is caused to wear a predetermined lens, the subject is caused to induce brain activity by causing the subject to view a visual stimulus that evokes a change in periodic brain activity, the brain activity at the time when the subject views the visual stimulus that evokes a change in periodic brain activity is obtained in the form of a waveform of an electrical signal, and one or more of the amplitude, the dioptric value, and the frequency phase, the frequency being the inverse of the period of the periodic brain activity, are calculated by analysis. Thereafter, the visual perception of the subject when viewing an object through the lens is calculated based on the magnitude of the amplitude or dioptric value thus obtained, or based on the slowness / rapidity of the phase thus obtained. In other words, the basic point of the present application is to cause the subject to view a visual stimulus through a lens and induce periodic brain activity. Thus, one basic point is to evaluate the lens itself and thus select a better lens for the subject, and another basic point is to analyze the characteristics regarding how the subject visually perceives the object through the lens and select a better lens for the subject in accordance with the tendency of the visual perception of each individual subject.

[0074] Further, it is preferable that the eyeglass lens be designed by use of the eyeglass lens evaluation method. When the lens to be designed is a progressive addition lens or an aspheric lens, the eyeglass lens design is determined by controlling the diopter or the like in each lens point obtained by controlling the lens shape or the like of the eyeglass lens, and the lens design information is determined. Further, when the lens to be designed is a color lens, the eyeglass lens design is determined by controlling, for example, the light transmittance of each wavelength of light that transmits through the lens, and the lens design information is determined. The color lens is not limited to a tinted lens, and can change the reflection characteristics on the lens surface, or can change the absorption performance of wavelengths in the ultraviolet region or near infrared region, or can change the properties of the lens material, such as the Abbe number related to chromatic dispersion. The common feature is that the lens design with respect to the object to be designed is performed, and the optical performance value (for example, diopter, image formation state on the retina, spectral transmittance, or Abbe number) of the object with respect to the light beam that transmits through the lens can be calculated, and thus is not limited to these.

[0075] For example, in the case of two or more types of lenses to be evaluated, the objective evaluation value of the visual perception that transmits through each lens is calculated by using the eyeglass lens evaluation method, and thus the difference in the optical performance value between the lens to be evaluated that is highest in the evaluation and the remaining lenses to be evaluated is obtained, and a new reference lens to be evaluated is designed as a new design target value obtained by adding a part of the difference to the optical performance value of the lens to be evaluated that is highest in the evaluation. In the case of a plurality of lenses to be evaluated including the new reference lens to be evaluated and the lens to be evaluated that is highest in the evaluation, the objective evaluation of the visual perception is performed by repeatedly using the aforementioned eyeglass lens evaluation method, and it is possible to narrow the design.

[0076] EFFECT OF THE INVENTION

[0077] According to the present application, it is possible to objectively evaluate the average visual perception when a subject views an object through an eyeglass lens to be evaluated over a relatively long period of time, the time-dependent change in the visual perception, the visual perception when the subject views one object with both eyes, and the balance of the visual perception; and it is possible to design a suitable lens based on the evaluation. Further, when the visual perception characteristics of the subject that transmits through the lens are calculated in numerical form, it is possible to design a lens suitable for the subject based on the information about the value. BRIEF DESCRIPTION OF DRAWINGS

[0078] Fig. 1 is a front view of one example of a fixation point and a visual stimulus in Example 1.

[0079] FIG. 2 is an explanatory diagram that describes a case in which the waveform of an electrical signal of brain activity that has not yet been analyzed is recorded.

[0080] FIG. 3is a view showing one example of measurement results, in which the respective measurement positions (gradient meter) of the brain in Example 1 and the arithmetic mean waveform of the obtained change in magnetic flux density are arranged in association with each other. In FIG. 3 The gradient meter pair consisting of M1922 and M1923 is plotted in a circle in

[0081] Fig. 4 (a) is a graph showing the relationship between the sum square root value (RSS value) of the diopter values of the clinometer pair and the frequency when the diopter of S+0D is applied; (b) is a graph showing the same relationship between the sum square root value (RSS value) of the diopter values of the clinometer pair and the frequency when the diopter of S+2D is applied; and (c) is a graph showing the relationship between the sum square root value (RSS value) of the amplitude of the clinometer pair and the frequency component when the diopter of S+0D is applied.

[0082] FIG. 5 is a scalp topography in which the amplitude of brain activity (fT / cm) at the diopter of application and 15 Hz in Example 1 is highlighted to the back side of the head.

[0083] FIG. 6 is a graph showing the relationship between the diopter values and the time period measured when the subject wore the progressive addition lens 1 and when the subject wore the progressive addition lens 2 in Example 2.

[0084] FIG. 7 is a graph showing the ratio between the dominant eye and the non-dominant eye when the sum square root value (RSS value) of the diopter values measured with respect to both eyes of the subject in Example 3 is assumed to be 100%.

[0085] FIG. 8 is a graph showing the relationship between the sum square root (RSS) of the diopter values measured with respect to both eyes of the subject and the applied diopter when the diopter is applied to the dominant eye and the non-dominant eye in Example 4.

[0086] Fig. 9 is a front view of one example of a visual stimulus consisting of a plurality of line segments, in which the fixation point is not displayed at the line segments in Example 5.

[0087] Fig. 10 (a) is a graph of the arithmetic mean waveform when the subject wears a spherical lens with a larger astigmatism in Example 5, and (b) is a graph of the arithmetic mean waveform when the subject wears an aspherical lens with a smaller astigmatism in Example 5.

[0088] Fig. 11 is a front view of one example of a visual stimulus consisting of one fixation point and a non-directional figure (circle) in Example 6.

[0089] FIG. 12is an explanatory diagram describing the movement locus of the line of sight superimposed on the varifocal lens in the astigmatic view from the back surface side of the varifocal lens in Example 8.

[0090] Figs. 13(a) to (c) are explanatory diagrams describing the movement condition of the fixation point and the visual stimulus corresponding to the movement locus of the line of sight in the varifocal lens of Example 8.

[0091] In Fig. 14, in Example 9, (a) is a graph showing the relationship between the root sum square value (RSS value) of the diopter value and the frequency when there is no blank display time interval under the application of the diopter of S+0D; (b) is the same graph when there is a blank display time interval; (c) is the same graph when there is no blank display time interval under the application of the diopter of S+4D; and (d) is the same graph when there is a blank display time interval under the application of the diopter of S+4D.

[0092] FIG. 15 is an explanatory diagram describing the transmitted position on the lens when the fixation point and the visual stimulus are viewed with both eyes in the second eye position or the third eye position.

[0093] FIG. 16 is an average wave form of the plotters channel having a peak in the occipital visual cortex when the visual stimulus is viewed with both eyes in the first eye position or the third eye position in Example 10.

[0094] Fig. 17 is a view comparing the brain responses between (a) the visual perception when the defocus is applied to the dominant eye and the non-dominant eye of the subject E and (b) the visual perception when the distortion is applied to the dominant eye and the non-dominant eye of the subject E in Example 11.

[0095] Fig. 18 is a view comparing the brain responses between (a) the visual perception when the defocus is applied to the dominant eye and the non-dominant eye of the subject F and (b) the visual perception when the distortion is applied to the dominant eye and the non-dominant eye of the subject F in Example 11.

[0096] Fig. 19(a) is an astigmatic view of a conventional design for the right eye, and (b) is an astigmatic view of a conventional design for the left eye.

[0097] Fig. 20(a) is an astigmatic view of the present application designed to be suitable for the right eye of the user E, and (b) is an astigmatic view of the present application designed to be suitable for the left eye of the user E.

[0098] FIG. 21 is a view showing the change in the brain response in the subject G when the color of the grid is changed.

[0099] FIG. 22 is a view of the average wave form of each grid color in Example 13. DETAILED DESCRIPTION

[0100] A specific embodiment of the present application will be described hereinafter with reference to the accompanying drawings.

[0101] <Example 1>

[0102] 1. Experimental conditions and recording of brain activity

[0103] The fixation point was displayed at a visual distance of two meters in front, and the lattice images were displayed alternately at a period of 66.67 ms (milliseconds) without a blank display time interval at (a) and (b) of Fig. 1. Although (a) of Fig. 1 and (b) of Fig. 1 are mutually different patterns, these patterns are very close to each other in the arrangement shape of the lattice pattern, and the brightness and color of the entire image are the same, thus being images of visual stimuli that give the same stimulus to the low-level visual cortex of the brain. These visual stimuli in (a) and (b) have the same brightness, thus being visual stimuli that induce neuronal activity in the low-level visual cortex of the brain when switching between the images. The period thereof is 66.67 ms, thus inducing periodic brain activity in a steady state of 15 Hz. For each lens condition, each image was displayed at this period without a blank display time interval for 90 seconds while switching between the images was alternately performed. The size of the image had a visual angle of 8.6 degrees x 8.6 degrees. The fixation point was actually displayed in red. The subject "A" was made to wear glasses with normal diopter and which were used daily, and the subject was made to wear glasses with S+4D, S+2D, S+1D, and S+0.5D imposed on the normal diopter (S+0D), and the subject was commanded to fixate the fixation point, thus recording brain activity at this time by using a 306-channel magnetoencephalograph (Vector- view, ELECTA Neuromag). The 306-channel magnetoencephalograph includes 102 channels of magnetometers (each magnetometer functions as a magnetic sensor) disposed in a helmet-shaped body in a scattered manner, and 102 pairs of (204 channels) inclinometers. The 306-channel magnetoencephalograph is capable of measuring changes in the magnetic field caused by the brain activity of the subject by having the subject place the body on the head of the subject. The recording of the brain activity was displayed in, for example, FIG. 2 .

[0104] 2. Analysis of brain activity

[0105] Based on, for example, FIG. 2The waveform of the brain activity shown in FIG. 1 is set with an analysis window for analysis. Embodiment 1 is an example in which a period of 64 seconds (in the range from 10 seconds to 74 seconds after the start of measurement out of 90 seconds in which the measurement is performed) is set as the analysis window. Out of the 306 channels of the magnetometers of the magnetoencephalography sensor, 102 channels are set not to be analyzed, and a fast Fourier transform (FFT) is performed on the waveforms included in the 64-second analysis window of each channel based on the recording results of the 204 channels (102 pairs) of the gradiometers to be converted into a relationship between the frequency and the diopter value.

[0106] 3. Results

[0107] FIG. 3 The results in which the time at which the image of Embodiment 1 is presented is defined as 0 seconds and in which the results of the arithmetic average calculation from -100 milliseconds to +300 milliseconds are performed are shown in FIG. 2. It should be understood that, in the case of the results of the arithmetic average calculation from -100 milliseconds to +300 milliseconds, the results of the arithmetic average calculation from -100 milliseconds to +300 milliseconds are performed on the waveforms included in the 64-second analysis window of each channel based on the recording results of the 204 channels (102 pairs) of the gradiometers. FIG. 3 The positions of the circular markers (M1922 and M1923) of FIG. 1 observe large brain activity near the primary visual cortex and observe periodic brain activity. M1922 and M1923 represent the name codes of the gradiometers, respectively, showing the measurement positions of the positions of the circular markers. Although this arithmetic average waveform is not necessarily indispensable in the measurement and the analysis of this embodiment, it is possible to judge whether or not periodic brain activity is evoked.

[0108] As an example, FIG. 4 shows a graph of the sum square root (RSS) of the diopter values of the inclinometer pair of M1922 and M1923 showing the maximum brain activity in the visual cortex and the frequency when two lenses of S+0D (no application) and S+2D are loaded into the normal diopter of the subject "A". This result is an evaluation result of the average visual perception of the analysis window of 64 seconds for analysis. As described in (a) of FIG. 4, when the applied diopter is S+0D, brain activity with high intensity is observed at 15 Hz, and as shown in (b) of FIG. 4, when the applied diopter is S+2D, its activity becomes significantly small, the magnitude of the diopter value when the applied diopter is S+2D is 7% relative to the magnitude of the displayed diopter value when the applied diopter is S+0D. In other words, it should be understood that, in the subject "A", the lens with the applied diopter of S+0D is more appropriate. Further, as the visual perception characteristics of the subject "A", it should be understood that, when S+2D is applied, that is, when the image formation state on the retina is defocused by S+2D, the brain response is reduced by 93% compared to the state without application (S+0D). Here, for example, in one subject B, if the brain response is reduced by 50% when S+2D is applied to the normal diopter compared to when it is not applied, it should be understood that the characteristics of the subject "A" are sensitive to the defocusing of the image caused by the spherical diopter error (S+2D), while the characteristics of the subject B are sensitive to the defocusing of the image caused by the spherical diopter error (S+2D). Further, at this time, the alpha wave occurs in 8 to 13 Hz, so it should be understood that it is preferable to use the range of 4 to 7 Hz, which does not coincide with the alpha wave or the range of 14 to 60 Hz, when evaluating the brain response using frequency analysis, as in the current case. Further, specifically, the range of 14 to 19 Hz is advantageous because it enables measurement of a strong response as shown in (a) of FIG. 4. Further, although the relationship between the amplitude and the frequency when the diopter is S+0D is shown in (c) of FIG. 4, the activity of 15 Hz is observed in this way even if the amplitude is used instead of the diopter value. Here, in the relationship between the brain activity, the amplitude, and the diopter value of the background brain wave, the center is in the range of 8 to 13 Hz, it should be understood that the use of the diopter value makes the difference therein greater than the use of the amplitude, and it is easier to measure the target periodic brain activity.

[0109] FIG. 5 A distribution view of the amplitude of the 15 Hz brain activity on the scalp based on the applied diopter of the subject "A" is shown in FIG. 5. As shown here, the brain response increases in proportion to the decrease in the applied diopter. Further, the amplitude of the brain activity rapidly decreases even when the applied diopter is 0.5D, so the method of the present application is characterized by having a very high sensitivity to the diopter error.

[0110] <Example 2>

[0111] Example 2 is an example in which the analysis window is set to 8 seconds, and comparison is made between two progressive lenses in terms of time-dependent changes in visual perception by continuously moving the analysis windows while being overlapped.

[0112] 1. Experimental Conditions and Brain Activity Recording

[0113] At a viewing distance of 80 cm, a fixation point was presented at a secondary eye position 20 degrees below the front. Subject B wore progressive lenses A and B and was instructed to fixate on the fixation point. Visual stimuli that induced periodic brain activity were displayed for 60 seconds in the same manner as in Figure 1 , with switching between images performed alternately with a 66.67 millisecond cycle (at a frequency of 15 Hz) without blanking intervals. During this time, brain activity was measured using a magnetoencephalogram.

[0114] 2. Brain Activity Analysis

[0115] When analyzing the waveforms of recorded brain activity, the analysis window was set to 8 seconds. First, measurement data centered at ±4 seconds around 8 seconds was selected, that is, data from 4 to 12 seconds after the start of stimulus presentation. Fast Fourier transform (FFT) was performed on the waveforms measured by each inclinometer in the same manner as in Example 1. The channel where the diopter value of each inclinometer reached its maximum was selected, and the diopter value at this time was recorded. The analysis window was then shifted by 4 seconds. In other words, data centered at ±4 seconds around 12 seconds was selected, and FFT was performed on this data, recording the diopter value of the channel that reached its maximum value in the aforementioned analysis. Next, data centered at ±4 seconds around 16 seconds was selected, and the analysis window was shifted in this manner, capturing changes in diopter values ​​from 8 to 48 seconds (from 4 to 52 seconds in the data used for analysis). In other words, the data was overlapped every 4 seconds.

[0116] 3. Results

[0117] The change in frequency of the measurement time of 15 Hz with respect to the diopter value of the progressive focus lens 1 and the diopter value of the progressive focus lens 2 obtained in this manner is shown in FIG. FIG. 6 Each point is the average value of ±4 seconds. FIG. 6 In the solid line (progressive lens 1), when the measurement starts, the display shows 1200fT. 2 / cm 2 As the measurement time passed, the diopter value gradually decreased and became 200fT. 2 / cm 2 On the other hand, in the progressive lens 2 indicated by the dotted line, the diopter value is 600fT when the measurement starts.2 / cm 2 Therefore, the intensity of the brain response is less than the progressive addition lens 1, and the decrease in the diopter value hardly occurs as time elapses, and the diopter value is maintained approximately equal even after 48 seconds. Based on this fact, it can be judged that in the progressive addition lens 1, the visual perception gradually decreases, although it is visually clear at the beginning, on the other hand, in the progressive addition lens 2, the superior visual perception compared to the progressive addition lens 1 is maintained during approximately 1 minute in the concentrated state, although the initial visual perception is slightly inferior to the progressive addition lens 1, therefore the progressive addition lens 2 is a lens which continues to have better visual perception than the progressive addition lens 1 for a long time. Here, although the present embodiment 2 is one example in which the analysis window is overlapped every 4 seconds, the same analysis method can be employed even when the analysis window is overlapped, for example, every one second.

[0118] <Embodiment 3>

[0119] The periodic brain response induced in the present application shown in Embodiment 3 is varied based on how well an object is viewed with both eyes and objectively evaluated with the brain response.

[0120] 1. Experimental conditions and brain activity recording

[0121] In the same manner as shown in Fig. 1 in Embodiment 1, a visual stimulus which induces periodic brain activity was presented in front of the subject with a 66.67 msec period (a frequency of 15 Hz), ten subjects were made to wear glasses with normal diopter which are used daily, and the brain response was measured with a brain magnetic wave recorder when viewed with both eyes, when viewed with only the dominant eye while masking the non-dominant eye, and when viewed with only the non-dominant eye while masking the dominant eye. The stimulus period was set to 64 seconds.

[0122] <Analysis>

[0123] The analysis window was set to 32 seconds, after which a fast Fourier transform was performed on the recorded first half and the recorded second half of 64 seconds, after which a goniometer pair in the vicinity of the visual cortex was selected in which the RSS value of the diopter at a frequency of 15 Hz became the maximum for each subject, after which the diopter value of the RSS was recorded, and the average of the diopter value of the first half and the diopter value of the second half was calculated.

[0124] <Results>

[0125] The diopter value of the dominant eye and the diopter value of the non-dominant eye were converted so as to become 100% when each subject viewed with both eyes, and the average of all subjects was calculated. The result thereof is shown in FIG. 7In the case of viewing the object with both eyes as shown here, the brain response was observed to be twice as much as when the object was viewed with a single eye. As described above, the application of the present application enables the degree of good viewing of the object with both eyes to be objectively measured.

[0126] <EMBODIMENT 4>

[0127] Embodiment 4 relates to a method for measuring the balance of stereoscopic vision of both eyes.

[0128] 1. Experimental conditions and recording of brain activity

[0129] The viewing distance was set at 1.5 meters, the fixation point was presented in front (first eye position) for 5 seconds, then the fixation point was moved to the third eye position 18 degrees to the right and 18 degrees downward, and the same visual stimulus as in Fig. 1 of Embodiment 1 to induce periodic brain activity was presented behind the fixation point with a 66.67 msec period (frequency of 15 Hz) for 40 seconds. Subsequently, the fixation point was presented in front (first eye position) for 5 seconds, then moved 18 degrees to the left and 18 degrees downward, and the visual stimulus was presented, and the brain activity was measured with the brain magnetic wave recorder in the same manner as described above. The subject was instructed to continue to fixate the fixation point with the line of sight only. In addition to the normal refractive power of the subject, the subject C was given a refractive power of S+4D, S+2D, S+1D, S+0D, S-1D, S-2D, and S-4D to the dominant eye or the non-dominant eye of the subject, and the subject was made to wear an eyeglass lens with normal refractive power for the remaining eye.

[0130] 2. Analysis

[0131] The analysis window was set to 32 seconds, a fast Fourier transform was performed on the data from 4 to 36 seconds after the presentation of the stimulus among the 40 seconds used for measurement, and the average value of the RSS of the refractive power values at a frequency of 15 Hz (at the two measurement positions of the lower right and lower left) was taken as the evaluation result of the lens.

[0132] 3. Results

[0133] The results of the subject C are shown in FIG. 8 . The solid line indicates the case where the refractive power was applied to the dominant eye only, and the broken line indicates the case where the refractive power was applied to the non-dominant eye only. As FIG. 8As shown in , a change in brain response (the magnitude of the refractive power value) occurs between a case in which refractive power is applied to the dominant eye and a case in which refractive power is applied to the non-dominant eye, even if the applied refractive power is the same in both cases, and therefore in subject C, the visual perceptions of the dominant eye and the non-dominant eye are different from each other, and thus quantification in brain response can be achieved. As described above, according to the measurement technology of the present invention, it is possible to objectively evaluate the balance of visual perception using brain response even in subtle cases, such as a case in which a difference in visual perception occurs between the right eye and the left eye. The visual perception of the right eye and the visual perception of the left eye become different from each other, for example, when viewing an object with both eyes through the lateral portion of a progressive focus lens, as FIG. 15 As shown in , it can be said that the technology of the present invention is effective for lens evaluation and lens design in this case. In addition, as a visual perception characteristic, it should be understood that in subject C, the importance of the dominant eye is higher than that of the non-dominant eye, and the decrease in brain reaction (refractive power value) is relatively small. Even if the visual perception of the non-dominant eye becomes worse, if the visual perception of the dominant eye becomes worse, then the brain reaction decreases rapidly, and the visual perception becomes worse when viewing with both eyes. In addition, it should be understood that a more ideal refractive power is obtained by slightly adjusting the refraction of the non-dominant eye on the negative side. As described above, the application of the present invention makes it possible to evaluate whether the balance of visual perception using the subject's two eyes is appropriate through objective measurement.

[0134] <Example 5>

[0135] Example 5 is a method for objectively evaluating visual perception that changes based on the axial direction of astigmatism. In addition, this example discloses an example in which the gaze point is not displayed during measurement.

[0136] 1. Experimental Conditions and Brain Activity Recording

[0137] The apparent distance was set to 80 cm, the fixation point was presented for 5 seconds in front of the first eye position, then moved to a position 25 degrees to the right (second eye position) and the fixation point was cleared, then the two images shown in Fig. 9, which are visual stimuli to induce periodic brain activity, were alternately displayed for 40 seconds so that one image had a display time of 66.67 milliseconds (a frequency of 15 Hz). In other words, although the position of the fixation point was indicated to the subject, only the stimulus image was displayed without the fixation point during the measurement. In the case where the subject was made to wear the spherical lens 1 having S-5.00 D for the right eye and S-4.00 D C-1.00 D AX180 for the left eye for normal diopter, and in the period during which the subject was made to wear the aspherical lens 2 having the same diopter, the subject was instructed to fixate the position where the fixation point was located at the last moment, at which time the brain activity was measured with a magnetoencephalograph. The reason why the fixation point was displayed during the measurement is that it is presumed that there are cases of fixation difficulty, for example, it is presumed that children are subjects or there are people with fixation difficulty who cannot fixate the visual line. Furthermore, in this context, the diopter at the center of the spherical lens 1 and the aspherical lens 2 is the same, and the lens design around the lens is still different. The lens curvature is 0.5 curvature in both lenses, and in the spherical lens, a relatively large astigmatism occurs in the outer peripheral portion thereof, while in the aspherical lens, the occurrence of astigmatism is limited. In other words, as one condition, an astigmatism component occurs in the spherical diopter, while the occurrence of the astigmatism component is limited in the aspherical lens. At this time, in the position of the second eye position where the visual stimulus is presented, the axial degree of the astigmatism component that has occurred is 90 degrees, and the maximum meridian is in the horizontal direction and the minimum meridian is in the vertical direction.

[0138] 2. Analysis

[0139] The analysis window was set to 32 seconds, a fast Fourier transform was performed on the data from 4 to 36 seconds after the presentation of the stimulus in the 40 seconds used for the measurement, and the goniometer in which the diopter value became the largest in the frequency of 15 Hz near the visual cortex when the aspherical lens was worn was selected, and the diopter value thereof was analyzed.

[0140] 3. Results

[0141] To describe the composition of the brain response of the present embodiment, first, the waveforms of the arithmetic mean of the maximum wave channel (M2122 wave channel) in the visual cortex in the measurement (Figs. 10(a) and (b)) will be described. Here, in Fig. 10, the results obtained by performing an arithmetic mean calculation from -100 msec to 300 msec are shown assuming that the time at which the stimulus image of Fig. 9(a) is displayed is 0 seconds. In this context, the letter X of Fig. 10(a) represents the time at which one line segment image is more clear than the other line segment image when the two line segment images of Fig. 9 with two directionality are respectively viewed, and a strong response occurs in this image. The letter Y represents the time at which an image in which the visual perception is inferior to the aforementioned image is viewed and a small response occurs. In other words, the fact that the visual perception varies based on the relationship between the axial direction of the astigmatism component (astigmatism) and the directionality of the line segments of Figs. 10(a) and (b) is reflected in the brain response. On the other hand, in Fig. 10(b), a reaction with approximately the same level occurs in X and Y, although there is a slight difference between the two, and thus it is understood that the visual perception of the two images is approximately equally excellent. In other words, it is understood that the astigmatism component is small, and it is understood that the aspheric lens 2 is more ideal in the visual perception.

[0142] Here, the analysis of the present embodiment employing frequency analysis is performed on the measurement data that has not undergone the arithmetic mean calculation as shown in Fig. 10. Thus, in the case of the spherical lens 1 (Fig. 10(a)), a reaction of 15 Hz is hardly observed, and, on the contrary, a reaction of 7.5 Hz is observed. In the case of the aspheric lens 2 (Fig. 10(b)), a reaction of 15 Hz is mainly observed, and a reaction of 7.5 Hz is hardly observed. As described above, in the evaluation of the visual perception with the astigmatism component, the present embodiment 5 is characterized in that the reaction as the brain response can be measured not only in the case of clear visual perception but also in the case of blurred visual perception.

[0143] <Embodiment 6>

[0144] Embodiment 6 is an embodiment for evaluating the degree to which an image is defocused by the astigmatism component and the spherical power error, although the spherical power error is not used as an index in the direction of the astigmatism axis, in the case in which the visual perception depending on the axial direction of the astigmatism component is not evaluated. This evaluation is important, especially for the evaluation of the visual perception of the lateral portion of the progressive addition lens or the lens peripheral portion of the aspheric lens. Furthermore, this is important for evaluating the visual perception characteristics of the user with the astigmatism component and the spherical power error.

[0145] When a combination of line segments is used as shown in FIG. 1 and FIG. 9, the line segment in the clearer visual perception direction and the line segment in the blurred visual perception direction are present in the axial direction of the intermediate astigmatism, and the visual perception is affected by the axial direction of the astigmatism. Therefore, the visual perception is sensitive to the axial direction of the residual astigmatism of the difference between the astigmatism component of the subject's eye and the astigmatism component when the visual line passes through the lens, and there is a case where the influence on the axial direction of the subject's residual astigmatism is measured instead of the performance of the lens to be evaluated. To solve this problem, in Embodiment 6, as shown in FIG. 11 (a) and (b), the fixation point (a square in the figure) is displayed at the third eye position, each of the two images composed of a circle behind it and the brightness of the entire image is equal, is presented with a period of 66.67 msec (a frequency of 15 Hz), the subject fixates the fixation point, and at this time, the activity of the brain is measured.

[0146] The measurement operation was performed twice with a measurement period of 20 seconds (the fixation point was displayed in the lower right and lower left), and the analysis window was set to 16 seconds. The lenses to be evaluated were the progressive addition lenses 1, 2, and 3, the fast Fourier transform was performed, the RSS of the 15 Hz diopter value of the maximum channel pair in the visual cortex was calculated, and the evaluation values obtained by performing the calculation twice (lower right and lower left) were averaged. Therefore, in the subject D, the astigmatism of the progressive addition lens 1 was 210 fT / cm, the astigmatism of the progressive addition lens 2 was 150 fT / cm, and the astigmatism of the progressive addition lens 3 was 360 fT / cm, and it was judged that the aberration distribution of the progressive addition lens 3 was excellent. 2 2 2 2 2 2

[0147] <Embodiment 7>

[0148] Embodiment 7 is an example of a design method for performing lens design according to the evaluation method of the present application. Herein, the lens designed and to be evaluated is an inner surface progressive addition lens having a progressive surface on the back surface.

[0149] ​​​​​​In Embodiment 6, more excellent results were obtained for the progressive addition lens 3 than for the progressive addition lenses 1 and 2. At this time, the brain reaction was affected by the case where the line of sight of the fixation point of viewing Fig. 11 passes through the lens. Therefore, the coordinates of the line of sight of the fixation point of viewing passing through the back surface coordinates of the lens were obtained, and the optical performance values (mean refractive power, astigmatism, etc.) of the center of the progressive addition lenses 1 to 3 in the coordinates (for example, 8 mm x 8 mm and 1 mm step lattice data) and predetermined ranges were obtained. With respect to the optical performance value data (1 mm step lattice data) of the progressive addition lenses 1 to 3 thus obtained, the difference between the highest evaluation progressive addition lens 3 and the optical performance value of the progressive addition lens 1, and the difference between the progressive addition lens 3 and the optical performance value of the progressive addition lens 2 were calculated, and the data trend was analyzed based on the two difference data obtained above, and tolerance data was calculated. Half of the tolerance data was added to the progressive addition lens 3, and a new progressive addition lens 4 was designed by adding the obtained result as a design target value. Thereafter, for the progressive addition lens 3, the progressive addition lens 4, and the progressive addition lens 5 for comparison (not necessarily because it is newly designed), the visual perception was again objectively evaluated repeatedly with the magnetoencephalograph, and thus the evaluation result by using the present application can improve the design. By repeatedly performing the evaluation, the design can be narrowed.

[0150] <Embodiment 8>

[0151] Embodiment 8 is an evaluation made by moving the fixation point and the image behind the fixation point. The line of sight is moved when the spectacle lens is used in daily life, and thus it is necessary to objectively evaluate the ease of viewing in the movement of the line of sight. In Embodiment 8, the movement trajectory of the line of sight is represented to coincide with the lens. As an example as shown in this graph, a case is described in which the line of sight is moved from the viewing point slightly below the front (I) toward the nasal side (II), then moved toward the ear side while reversing the line of sight (III), and finally moved from the ear side toward the point slightly below the front (IV). FIG. 12 FIG. 12 FIG. 12 FIG. 12

[0152] 1. Experimental conditions and brain activity recording

[0153] ​​​​At a visual distance of 2 meters, a fixation point was presented slightly below the front and the image of Fig. 13(a) was displayed, and the fixation point was moved gradually toward the right hand side of the viewer (Fig. 13(b)) in 10 seconds. At this time, the image behind the fixation point was also moved together with the fixation point so that the positional relationship between the fixation point and the image was kept unchanged. Thereafter, the fixation point was moved smoothly from Fig. 13(b) to Fig. 13(c) in 20 seconds, and finally the fixation point and the image were moved from Fig. 13(c) to Fig. 13(a) in 10 seconds. For the convenience of description, the two lattice patterns displayed alternately with solid and broken lines in Figs. 13(a) to (c) were displayed so as to pass over each other on one pattern. The patterns of Figs. 13(a) to (c) drawn with solid and broken lines were displayed while being alternately switched with a period of 66.67 msec (a frequency of 15 Hz).

[0154] This arrangement causes the line of sight to pass through the lens of the left eye in the order of I→ II→ III, and the visual perception starts to gradually move from the clear-seeable area (front) to the defocus, the line of sight reaches the nasal side (line of sight movement of I), and then from the defocus state to the clear-seeable state, again to the defocus state, the line of sight reaches the ear side (line of sight movement of II). Finally, from the defocus state (nasal side) (line of sight movement of III) to the clear-seeable state (front). As described above, the subject was made to wear the progressive addition lens, the fixation point was moved, and the subject was commanded to fixate the fixation point, and therefore the position of the line of sight passing through the lens could be controlled. FIG. 12

[0155] The subject was made to wear the progressive addition lens 1 and the progressive addition lens 2, and the image shown in Fig. 13 was moved continuously (40 seconds in total), and at this time, the brain activity was recorded with the magnetoencephalograph.

[0156] 2. Analysis

[0157] The analysis was performed in the same manner as in the foregoing example. If evaluation of the average visual perception was expected, the analysis window was set to 32 seconds, and if evaluation of the time-dependent change of the visual perception was expected, the analysis window was set to 8 seconds and the analysis window was moved every 4 seconds. After the analysis window was set, the fast Fourier transform was performed, the channel reaching the maximum diopter value in the visual cortex was selected, and the RSS of the 15 Hz diopter value of the goniometer pair containing the channel was recorded.

[0158] 3. Results

[0159] Although this arrangement causes the line of sight to pass through the lens of the left eye in the order of I→ II→ III, and the visual perception starts to gradually move from the clear-seeable area (front) to the defocus, the line of sight reaches the nasal side (line of sight movement of I), and then from the defocus state to the clear-seeable state, again to the defocus state, the line of sight reaches the ear side (line of sight movement of II). Finally, from the defocus state (nasal side) (line of sight movement of III) to the clear-seeable state (front). As described above, the subject was made to wear the progressive addition lens, the fixation point was moved, and the subject was commanded to fixate the fixation point, and therefore the position of the line of sight passing through the lens could be controlled. FIG. 12 ​The visual perception changes in the line of sight of I→II→III, that is, clearly visible (front)→defocused (nose side)→clearly visible (front)→defocused (ear side)→(clearly visible), but by comparing the refractive power values ​​in which the measurement results have been subjected to frequency analysis, a comparative evaluation of the visual perception related to the line of sight movement of progressive focus lens 1 and progressive focus lens 2 can be made.

[0160] In this article, for the convenience of description, reference has been made to Example 8. FIG. 12 The sight line for the left eye is carried out by the position on the lens of the lens for the left eye, but in fact, it is important as FIG. 15 As shown in , the subject was instructed to view a moving fixation point with both eyes. Although the coordinates of the lines of sight through the lenses of the left and right eyes differed due to the subject viewing the moving fixation point with both eyes, this example evaluated visual perception, including the balance of right and left eye perception. The relationship between the right and left eye visual perception balance and the RSS of the diopter values ​​was described in the same manner as in Examples 3 and 4.

[0161] <Example 9>

[0162] While the case where a blank display interval is provided is shown in Example 9, the case where no blank display interval is provided is disclosed in Examples 1 to 8. There are cases where it is difficult to obtain the strength of brain responses based on individual differences between subjects. In such cases, it is possible to obtain brain responses for most subjects, for example, by first having the subject view a visual stimulus that induces periodic brain activity without a blank display interval and then measuring the brain activity, while also using a visual stimulus with a blank display interval if the target brain response is weak.

[0163] 1. Experimental Conditions

[0164] This is an example in which the images of (a) and (b) of FIG. 1 are displayed alternately every 166.66 milliseconds. When the viewing distance is 2 meters, if no blank display time interval is given, the two images are displayed alternately every 166.66 milliseconds. If a blank display time interval is given, FIG. 1 (a) is displayed for 83.33 milliseconds, then a blank image is displayed for 83.33 milliseconds (at this time, only the fixation point is displayed on the background without the image), then FIG. 1 (b) is displayed for 83.33 milliseconds, and then a blank image is displayed. Therefore, in this cycle, the repetition frequency is 6 Hz.

[0165] When an applied diopter of S+0D and an applied diopter of S+4D were applied to glasses with normal diopter worn by subject E, brain activity was measured with a magnetoencephalogram. The measurement was performed for 40 seconds.

[0166] 2. Analysis

[0167] The analysis window was set to 32 seconds, a fast Fourier transform was performed, the channel reaching the maximum power value in the visual cortex was selected, the RSS of the power values of the clinometer pair including the channel was calculated, and the power value was recorded.

[0168] 3. Results

[0169] In the applied power of S+0D, a stronger brain response of 6 Hz was observed in the case where the blank display time interval was given than in the case where no blank display time interval was given (Figs. 14(a) and (b)). In other words, in the applied power of S+4D, when no blank display time interval was given, the target brain activity was masked in the background brain activity, while when the blank display time interval was given, the activity of 6 Hz was obtained even though the applied power was S+4D (Figs. 14(c) and (d)). As described above, when it is difficult to obtain the intensity of the brain response, the present embodiment is effective because the luminance change stimulus can be periodically generated by periodically giving the blank display time interval of the stimulus image.

[0170] <Embodiment 10>

[0171] Embodiment 10 is an example of a method for evaluating visual perception through a lens using phase.

[0172] 1. Experimental conditions

[0173] The subject D was made to wear the progressive addition lens of the astigmatic view shown in Fig. 1, and the subject D was instructed to continue to look at the fixation point. The fixation point was displayed in front (first eye position) at a viewing distance of 2 meters, and the grid images shown in Figs. 1(a) and (b) were alternately displayed with a period of 66.67 msec without a blank display time interval. Thereafter, the fixation point was displayed at the lower right of the diagonal (third eye position), and the grid images of Figs. 1(a) and (b) behind the fixation point were displayed for 40 seconds. The brain response at that time was measured with a 306-channel magnetoencephalograph. FIG. 12 The subject D was made to wear the progressive addition lens of the astigmatic view shown in Fig. 1, and the subject D was instructed to continue to look at the fixation point. The fixation point was displayed in front (first eye position) at a viewing distance of 2 meters, and the grid images shown in Figs. 1(a) and (b) were alternately displayed with a period of 66.67 msec without a blank display time interval. Thereafter, the fixation point was displayed at the lower right of the diagonal (third eye position), and the grid images of Figs. 1(a) and (b) behind the fixation point were displayed for 40 seconds. The brain response at that time was measured with a 306-channel magnetoencephalograph.

[0174] 2. Analysis The analysis window was set to 32 seconds, a fast Fourier transform was performed, the channel reaching the maximum power value in the visual cortex was selected, the RSS of the power values of the clinometer pair including the channel was calculated, and the power value was recorded.

[0175] 3. Results

[0176] The phase in the front of the viewing lens (first eye position) is 50 degrees, the phase in the lower diagonal of the viewing lens (third eye position) is 212 degrees, and it is determined that there is a phase delay of 162 degrees in the line of sight at the third eye position compared to the first eye position. When the lens is a progressive lens, the image is clearly viewed at the first eye position, the image is blurred at the third eye position due to astigmatism or image field curvature or the difference between the left and right images when viewing the image with both eyes, and thus the phase delay represents that there is greater difficulty in the visual perception at the third eye position than at the first eye position for the progressive lens to be evaluated. Therefore, the use of the phase slowness / quickness enables, for example, to evaluate whether the ideal lens for the subject D is the progressive lens 1 or the progressive lens 2, or to perform lens design based on the evaluation result. Furthermore, by making a comparison between the first eye position and the third eye position, it is possible to evaluate the visual perception characteristics of the subject. For example, assuming that the progressive lens 1 is worn, the phase is delayed by 162 degrees in the comparison between the third eye position and the first eye position in the subject D, and the phase is delayed by 100 degrees in the comparison between the third eye position and the first eye position in the subject E. At this time, the amount of phase delay of the subject D is greater at the third eye position of the progressive lens, and thus it is possible to evaluate the visual perception characteristics that are sensitive to the influence of aberration present in the lower diagonal direction of the progressive lens.

[0177] Here, in order to describe the phase, the average waveform of the FIG. 16 pliotometer (M2112) that shows the maximum response in the visual cortex is shown in FIG. 3 This is to obtain the waveform of the channel in which the strongest response is obtained in the visual cortex of the occipital lobe by performing an arithmetic addition calculation of 600 times such that the time when the image is presented is defined as 0 ms, and selecting the waveform based on the waveforms of all the head measurements as shown in FIG. 16 This is the brain response in 15 Hz steady state with a period of 66.67 ms when an object is viewed at the first eye position and when an object is viewed at the third eye position as described in

[0178] Here, it is understood that by focusing on the amplitude of FIG. 16 when an object is viewed at the first eye position, the amplitude is three times larger when the object is viewed at the third eye position, and a more comfortable visual perception is obtained at the first eye position than at the third eye position, and thus it is understood that the lens performance can be evaluated with a combination of amplitude and phase. It is conceivable that the influence of measurement noise or measurement error can be reduced by evaluating with a combination of amplitude and phase or a combination of diopter value and phase as described above, and thus it is preferable to use a plurality of evaluation values in the same measurement. FIG. 16The average waveform is formed by adding 40 seconds (600 times) of cycles, and it is necessary to add as many times, so that several seconds to several tens of seconds of measurement are required to obtain the measurement value. On the other hand, when the phase delay is focused on, the phase can be calculated with each analysis window, so that by setting the analysis window to, for example, 512 milliseconds, the visual perception can be evaluated in real time in a very short time.

[0179] <Embodiment 11>

[0180] Embodiment 11 is an example in which the user characteristics when the subject (user) wears the spectacle lens are evaluated by measuring the brain response when the subject wears the lens for the specific evaluation. In this example, although the user characteristics are measured with the magnetoencephalograph placed in the laboratory, the brain response of the visual cortex measured with the magnetoencephalograph can also be measured even with the electroencephalograph by disposing the electrodes on the occipital lobe. Therefore, the brain response can be measured in the same manner as by using the electroencephalograph in the shop of, for example, an optometrist.

[0181] 1. Experimental conditions and brain activity recording

[0182] The grid patterns of (a) and (b) of Fig. 1 are alternately displayed with a 66.67 millisecond cycle at a viewing distance of 100 cm in front of the presentation of the fixation point. Under the following conditions, the defocus or the distortion is applied to the dominant eye and the non-dominant eye of the subject with the lens, Condition A: none is applied to both eyes; Condition B: there is an application to the dominant eye and none to the non-dominant eye; Condition C: there is an application to the non-dominant eye and none to the dominant eye; and Condition D: there is an application to both eyes and the subject is caused to fixate the fixation point. For example, in order to apply the defocus to the subject with the lens, the spherical diopter or the like is used as the loaded lens. For example, in order to apply the distortion to the subject with the lens, a progressive addition lens, such as S+0.00 ADD 2.00 or a cylindrical diopter is used as the loaded lens. The display period of the visual stimulus is set to 20 seconds, and the brain response is repeatedly measured while changing the conditions.

[0183] 2. Analysis

[0184] The analysis window is set to 16 seconds, and the diopter value of the brain activity at 15 Hz is calculated in each of Conditions A to D in the same manner as in Embodiment 3.

[0185] 3. Results

[0186] Here, the results with respect to the subject E whose right eye is the dominant eye and with respect to the subject F whose left eye is the dominant eye are shown in Figs. 17 and 18.

[0187] First, in the subject E, when defocus was applied to the single eye of the subject E (i.e., when the single eye was brought into a defocus state), the intensity of the brain response was approximately halved, and when defocus was applied to both eyes, the intensity of the brain response became approximately 1 / 6, as shown in (a) of Fig. 17. At this time, there was no difference between the application to the dominant eye and the application to the non-dominant eye. On the other hand, as shown in (b) of Fig. 17, when distortion was applied to the non-dominant eye, the intensity of the brain response was approximately halved, and when distortion was applied to the non-dominant eye, the amount of decrease was half of the case in which distortion was applied to the dominant eye, and when distortion was applied to both eyes, the intensity was substantially the same as when distortion was applied to the dominant eye. Based on these facts, it should be understood that the subject E has the following characteristics:

[0188] Although there was no large difference between the dominant eye and the non-dominant eye in terms of defocus, there was a difference in the brain response between the dominant eye and the non-dominant eye in terms of distortion.

[0189] When distortion was applied to the right eye, which was the dominant eye, the brain response decreased to a large extent.

[0190] Even when distortion was applied to the left eye, which was the non-dominant eye, the brain response did not easily decrease.

[0191] When both eyes were brought into a defocus state, the brain response rapidly decreased, and when both eyes were brought into a distortion state, the brain response became as high as when the dominant eye was brought into a distortion state.

[0192] Next, in the case of the subject F, the results obtained by performing the same measurement are shown in Fig. 18.

[0193] In the subject F, the intensity of the brain response hardly changed even when distortion was applied as shown in (b) of Fig. 18, and the brain response decreased when defocus was applied specifically to the dominant eye, as shown in (a) of Fig. 18. Based on these facts, it should be understood that the subject F has the following characteristics:

[0194] The subject F is more sensitive to defocus than to distortion.

[0195] When the dominant eye was brought into a defocus state, the brain response decreased to a large extent.

[0196] As described above, the application of the present application makes it possible to measure how the dominant eye and the non-dominant eye of a user have visual perception characteristics in terms of defocus and distortion.

[0197] <Example 12>

[0198] Example 12 is one example in which the visual perception characteristics of the user are measured and the lens design is performed based on the information about the visual perception characteristics. Although the description is given herein to the case in which the lens is designed by measuring the visual perception characteristics of the user with respect to the defocus, the lens design technique is not limited thereto.

[0199] 1. Measurement of characteristics of the user

[0200] The user is caused to view the visual stimulus shown in (a) and (b) of Fig. 1, which is the same as in Example 1 (e.g., an optometrist's shop), with an electroencephalograph to measure the brain response. At this time, the user is caused to wear the lens having the refractive power obtained by applying S+1D to the refractive power adjusted for the user (S+1D applied state) to preferably view the distant object, the user is caused to view the visual stimulus for 20 seconds, and then the user is caused to wear the lens having the refractive power adjusted for the user (S+0D applied state) to preferably view the distant object, and the user is caused to view the visual stimulus for 20 seconds. The electrodes of the electroencephalograph are disposed at O1 and O2 in the international 10-20 electrode system, the reference electrode is disposed at the right ear, and the ground electrode is disposed at the vertex of the head. The visual distance from the visual stimulus is set to 5 meters, and the visual angle is set to 4 degrees. The measured brain waves are analyzed with the electrodes attached to the measuring device, and the refractive power values in the S+1D applied state and the S+0D applied state, respectively, are obtained. Further, the defocus characteristics of the visual perception of the user are calculated according to the equation: Defocus index = (refractive power value in the S+1D applied state) / (refractive power value in the S+0D applied state). In this defocus characteristics, if the defocus index is a large value, the decrease in the brain response is small even when S+1D is applied, and therefore it is understood that the user has the visual perception characterized by less deterioration of the visual perception due to the defocus, on the other hand, if the defocus index is a small value, it is understood that the user has the visual perception characterized by the deterioration of the visual perception easily occurring even if the defocus is slight. Here, it is assumed that the defocus index of the user E is calculated to be 0.4.

[0201] 2. Lens design

[0202] When an optometrist's shop orders a lens from a spectacle lens manufacturer, the obtained visual perception characteristics (defocus characteristics) are communicated to the spectacle lens manufacturer via telephone or the Internet. Thereafter, a comparison is made between the defocus characteristics of the user and the average of the defocus characteristics of many people calculated in advance by using the host computer of the spectacle lens manufacturer, and a scaling ratio with respect to the visual perception of the user characterized in comparison with the standard visual perception is determined. For example, if the average of the defocus characteristics of many people calculated in advance is 0.2 and if the defocus characteristics of the user E are 0.4, it is understood that a decrease in visual perception does not easily occur in the user E even when a defocus state is reached. Therefore, in contrast to the conventional lens design shown in FIG. 19, a lens having less distortion is designed and manufactured in the manner of a personalized design as shown in FIG. 20. Generally, this personalized design has some defects in defocus in the lateral portions of the lens, although it has the advantage of having less distortion, on the other hand, the user E has a visual perception characterized by having less defocus concern than other many users, and therefore the personalized design shown in FIG. 20 is preferable to the design shown in FIG. 19.

[0203] <Embodiment 13>

[0204] Embodiment 13 is an example of measuring the visual perception characteristics of a user in color. Although this embodiment is an example in which the measurement is performed in a laboratory by using a magnetoencephalograph, it is possible to measure the visual perception characteristics of a user in color and provide a color lens, etc. that reflects its measurement results in color by using similar visual stimuli and by using an electroencephalograph (e.g., in an optometrist's shop).

[0205] 1. Experimental conditions and brain activity recording

[0206] At a viewing distance of 100 cm, a fixation point of gray color is presented in front, and the lattice patterns of (a) and (b) of FIG. 1 are alternately displayed at a cycle of 66.67 milliseconds. At this time, the color of the lattice is set to any one of white, red, blue, green, and yellow, and the subject wears a colorless lens that has been corrected for vision, and the brain activity when the color of the lattice repeatedly displayed as a visual stimulus in a random order with each color is measured for ten seconds using a magnetoencephalograph. Preferably, at this time, it is displayed two or more times in order to exclude the influence of the order.

[0207] 2. Analysis

[0208] As for the time when each of the lattices displaying white, red, blue, green, and yellow is displayed, an analysis window of 8 seconds is set out of 10 seconds for measurement, a fast Fourier transform is executed, the refractive power is calculated, and the sum square root (RSS) of the refractive power values of the phoropter pairs for which the strongest response has been measured in the visual cortex is calculated. Thereafter, in each color, the average of the refractive power values of the phoropter pairs is calculated.

[0209] 3. Results

[0210] As for the subject G, the measurement results are shown in FIG. 21 where the brain response becomes smaller in the order of white ≈ yellow > green > red > blue according to the color change of the lattice. At this time, it should be understood that the ratio between white and blue (blue / white) as a result of the calculation is 0.03. Here, in order to evaluate the visual perception characteristics of the subject E, the ratio between white and blue (blue / white) of the average of thirty subjects is calculated in advance, and is compared with the ratio between white and blue (blue / white) of the subject E = 0.03. Therefore, it is assumed that the ratio between white and blue (blue / white) is lower in the subject E in comparison with the entire average. In this case, it should be understood that there is a tendency that the brain response becomes smaller than the average when the subject E watches blue and the subject E has a characteristic of having difficulty in seeing blue visual perception. Based on these facts, it should be understood that it is preferable to let the subject G wear lenses that do not excessively reduce the light transmittance of blue (i.e., the light transmittance of short wavelengths of 500 nm or less) by color lenses or the like, and thus the lens light transmittance in each wavelength can be set and the color lenses can be designed.

[0211] Next, FIG. 22 The average waveform recorded with the phoropter for which the strongest response has been measured in the visual cortex is shown in FIG. 8. When the phase is focused on, the order is white ≈ yellow > green > red > blue, and it should be understood that the same results as the refractive power values can be obtained even when the phase is used for evaluation. As described above, when the visual perception in terms of color is evaluated, the information about the refractive power values and about the phase can be utilized.

[0212] The present application can also be modified and implemented in the following manner.

[0213] Although the two images including the visual stimulus of the periodic brain wave are alternately displayed in the foregoing embodiment as described above, the number of types of images can be two or more. For example, if ten images are prepared in which the brightness of the entire image and the number of line segments (total line segment length) are equal to each other, and if these ten images are presented in a random order, the interval of the display time periods of each image becomes the period of the periodic brain response induced by the visual stimulus.

[0214] Although the display period and the non-display period of the image are set to be equal to each other in Embodiment 9, these do not necessarily have to be equal to each other. Although the stimulus-stimulus interval is 166.66 msec as one example in Embodiment 9, the periodic brain response can be induced even if the display period is set to 100 msec and even if the non-display period is set to 66.66 msec.

[0215] When the visual stimulus that induces the periodic brain response is displayed, its periodicity can be changed. For example, the visual stimulus is presented with a long period at the beginning and its periodicity is gradually made faster, and thus the frequency that the subject can accept can be objectively measured.

[0216] The fixation point is not indispensable in the specific display, and represents a command to the subject to fix the direction of the line of sight. For example, the fixation point of the present application also includes a case where the subject is commanded to watch the center of the moving visual stimulus and a case where the subject is commanded to watch the visual stimulus having an angle of view of 2 degrees or less.

[0217] The length of the analysis window of the foregoing embodiment is one example, and the present application is not limited to this length.

[0218] Although the image is used as the display of the visual stimulus in the foregoing embodiment, the present application includes giving the stimulus by using a visual stimulus other than the image, such as flicker or color change of LED light.

[0219] The measurement method of the user characteristics disclosed in Embodiment 11 is one example, and the present application is not limited to this.

[0220] The defocus characteristics disclosed in Embodiment 12 are one example, and the present application is not limited to this.

[0221] The design example disclosed in Embodiment 12 is one example of aberration improvement, and the present application is not limited to this.

[0222] The evaluation method of the color vision characteristics disclosed in Embodiment 13 is one example, and the present application is not limited to this.

[0223] The color lens design method disclosed in Embodiment 13 is one example, and the present application is not limited to this.

[0224] In some embodiments, the lens evaluation can be freely performed, such as using the magnitude of the refraction value or using the difference between the phases, but is not limited to the lens evaluation using the magnitude of the amplitude.

[0225] Although the right and left lens applications different from each other as in Example 4 or Example 11 are given when the application of the visual perception having a difference between the dominant eye and the non-dominant eye is given, the present application also includes an arrangement in which the subject wears, for example, a polarized lens or a liquid crystal lens, and in which the presentation of the right and left visual stimuli different from each other by the subject is performed without performing the lens replacement by using a stereoscopic display acting as a display that displays a visual stimulus.

[0226] Although the lens application of the defocus can be performed by the lens that the subject wears when the defocus is applied to the subject as shown in Example 1 or Example 12, the subject can wear a lens having a refractive power with which the subject can visually well perceive the distance from a visual stimulus, for example, and the defocused visual stimulus can be presented to the subject. In other words, the present application also includes an arrangement in which the subject wears a lens having a refractive power with which the subject can visually well perceive the distance from a visual stimulus when the visual perception characteristics of the subject due to the defocus are measured, and gazes at several types of visual stimuli in which the degree of defocus of the visual stimulus has been changed.

[0227] Furthermore, the present application can be freely implemented with embodiments that do not depart from the gist of the present application.

Claims

1. A method for calculating visual perception characteristics of a subject when the subject views an object through a lens, the method comprising: having the subject wear predetermined lenses; The periodic brain activity of the subject's brain is induced by allowing the subject to view, through the lens, a visual stimulus that changes at a predetermined period and is designed to induce the periodic brain activity of the subject's brain. The visual stimulus comprises: a first figure consisting of one or more line segments and / or one or more circles; and a second figure consisting of one or more line segments and / or one or more circles, wherein the second figure is different from the first figure, and the subject is caused to alternately view the first figure and the second figure at a frequency of more than 4 times per second. obtaining the brain activity in the form of a waveform of an electrical signal; calculating one or more of an amplitude, a diopter value, and a phase at a frequency that is an inverse of a period of brain activity by analyzing the waveform; and calculating the visual perception characteristics of the subject when viewing an object through the lens based on the magnitude of the amplitude or diopter value obtained above, or based on the slowness / fastness of the phase obtained above, wherein the brain activity is obtained using a time unit for analysis, hereinafter referred to as an analysis window, and the average visual perception is calculated in the analysis window, Here, as the visual perception characteristics of the subject, the visual perception characteristics of the subject with respect to defocus are calculated based on the results of analyzing the periodic brain activity when there is no diopter and the results of analyzing the periodic brain activity when there is diopter.

2. A method for calculating visual perception characteristics of a subject when the subject views an object through a lens, the method comprising: having the subject wear predetermined lenses; The periodic brain activity of the subject's brain is induced by allowing the subject to view, through the lens, a visual stimulus that changes at a predetermined period and is designed to induce the periodic brain activity of the subject's brain. The visual stimulus comprises: a first figure consisting of one or more line segments and / or one or more circles; and a second figure consisting of one or more line segments and / or one or more circles, wherein the second figure is different from the first figure, and the subject is caused to alternately view the first figure and the second figure at a frequency of more than 4 times per second. obtaining the brain activity in the form of a waveform of an electrical signal; calculating one or more of an amplitude, a diopter value, and a phase at a frequency that is an inverse of a period of brain activity by analyzing the waveform; and calculating the visual perception characteristics of the subject when viewing an object through the lens based on the magnitude of the amplitude or diopter value obtained above, or based on the slowness / fastness of the phase obtained above, wherein the brain activity is obtained using a time unit for analysis, hereinafter referred to as an analysis window, and the average visual perception is calculated in the analysis window, Here, as the visual perception characteristics of the subject, the visual perception characteristics of the subject with respect to color are calculated based on the results of analyzing the periodic brain activity when the subject views the visual stimuli of a plurality of different colors.

3. A method for calculating visual perception characteristics of a subject when the subject views an object through a lens, the method comprising: having the subject wear predetermined lenses; The periodic brain activity of the subject's brain is induced by allowing the subject to view, through the lens, a visual stimulus that changes at a predetermined period and is designed to induce the periodic brain activity of the subject's brain. The visual stimulus comprises: a first figure consisting of one or more line segments and / or one or more circles; and a second figure consisting of one or more line segments and / or one or more circles, wherein the second figure is different from the first figure, and the subject is caused to alternately view the first figure and the second figure at a frequency of more than 4 times per second. obtaining the brain activity in the form of a waveform of an electrical signal; calculating one or more of an amplitude, a diopter value, and a phase at a frequency that is an inverse of a period of brain activity by analyzing the waveform; and calculating the visual perception characteristics of the subject when viewing an object through the lens based on the magnitude of the amplitude or diopter value obtained above, or based on the slowness / fastness of the phase obtained above, wherein the brain activity is obtained using a time unit for analysis, hereinafter referred to as an analysis window, and the average visual perception is calculated in the analysis window, In which, as the visual perception characteristics of the subject, the visual perception characteristics of the subject for the dominant eye are calculated based on the results of analyzing the periodic brain activity when the subject views the visual stimulus with the dominant eye and the results of analyzing the periodic brain activity when the subject views the visual stimulus with the non-dominant eye.

4. A method for designing a lens, the method being based on the visual perception characteristics of a subject measured in the method for calculating the visual perception characteristics of a subject when viewing an object through a lens according to any one of claims 1 to 3.

5. A method for designing a spectacle lens, the method being based on an evaluation result calculated by an evaluation method for evaluating a spectacle lens, the evaluation method comprising: Have the subject wear the lenses to be evaluated; The periodicity of neuronal activity in the visual cortex of the subject's brain is established by having the subject view, through the lens to be evaluated, a visual stimulus that changes with a predetermined period and is designed to induce periodic brain activity with a period to be analyzed, thereby inducing the periodic brain activity with the period to be analyzed; The visual stimulus comprises: a first figure consisting of one or more line segments and / or one or more circles; and a second figure consisting of one or more line segments and / or one or more circles, wherein the second figure is different from the first figure, and the subject is caused to alternately view the first figure and the second figure at a frequency of more than 4 times per second. obtaining the brain activity in the form of a waveform of an electrical signal; calculating one or more of amplitude, diopter value, and phase at a frequency that is the inverse of a period of brain activity by analyzing the waveform; and evaluating the visual perception in observation through the lens to be evaluated based on the magnitude of the amplitude or diopter value obtained above or based on the slowness / fastness of the phase obtained above, wherein the brain activity is obtained using a time unit for analysis, hereinafter referred to as an analysis window, and the average visual perception is evaluated in the analysis window, The method for designing spectacle lenses comprises: Step 1: Analyze two or more types of lenses to be evaluated to obtain the difference in optical performance between the highest-rated lens among the lenses to be evaluated and another lens among the lenses to be evaluated; A second step is to assign a portion of the difference obtained in the first step as a correction value for the optical performance value of the highest-evaluated lens, and calculate a new lens shape using the corrected optical performance value as a design target value to set a reference lens to be evaluated; The third step: in the following items (A) and (B), obtaining the difference in optical performance value between the highest-rated lens among the lenses to be evaluated and another lens among the lenses to be evaluated, (A) the reference lens to be evaluated and the highest-rated lens among them, (B) the reference lens to be evaluated, the highest-rated lens therein, and one or more lenses to be evaluated that have been newly added, and Step 4: giving a portion of the difference obtained in the step 3 as a correction value for the optical performance value of the highest-evaluated lens, and calculating a new lens shape using the corrected optical performance value as a design target value to set the reference lens to be evaluated; While repeatedly performing the third step and the fourth step, a spectacle lens suitable for the subject is designed by reducing the difference.

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