Design method and manufacturing method for ophthalmic lens

Abstract

Provided is a design method for an ophthalmic lens provided with a functional region having a base region that achieves prescribed refractive power of a wearer and a plurality of defocus regions that have refractive power different from the prescribed refractive power, the design method for the ophthalmic lens comprising: a step (A) for measuring feature amounts of the defocus regions under a predetermined manufacturing condition to obtain a histogram of the feature amounts; a step (B) for obtaining a maximum value and a minimum value of the feature amounts, the maximum value and the minimum value being actually observed in the histogram or being observable with a predetermined probability; and a step (D) for determining a manufacturing condition for achieving a target state in which at least one of an upper limit margin that is a difference between the maximum value of the feature amounts and an allowable upper limit value of the feature amounts and a lower limit margin that is a difference between an allowable lower limit value of the feature amounts and the minimum value of the feature amounts is set as a variable.

Description

Method for designing and manufacturing ophthalmic lens

[0001] The present invention relates to a method for designing and a method for manufacturing an ophthalmic lens.

[0002] In recent years, studies have been progressing on ophthalmic lenses that exhibit myopia progression inhibitory effects and hyperopia reduction effects (also referred to as myopia progression inhibitory lenses, etc.). For example, Patent Document 1 discloses that when a lens base material is immersed in a hard coat solution, the degree to which unevenness is smoothed varies depending on the position of a convex region (defocus region) on the lens, and thus the defocus power (defocus dioptric power) changes.

[0003] Japanese Unexamined Patent Application Publication No. 2024-151744

[0004] An object of an embodiment of the present invention is to provide a technique that minimizes the risk that a feature amount of a defocus region falls outside an allowable range.

[0005] A first aspect of the present invention is a method for designing an ophthalmic lens comprising a functional region having a base region that achieves a prescription refractive power for a wearer and a plurality of defocus regions each having a refractive power different from the prescription refractive power, the method comprising: a step (A) of measuring a feature amount of the defocus region under predetermined manufacturing conditions to obtain a histogram of the feature amount; a step (B) of obtaining a maximum value and a minimum value of the feature amount that are actually observed in the histogram or can be observed with a predetermined probability; and a step (D) of determining manufacturing conditions that achieve a target state in which at least one of an upper margin, which is a difference between the maximum value of the feature amount and an allowable upper limit value of the feature amount, and a lower margin, which is a difference between an allowable lower limit value of the feature amount and the minimum value of the feature amount, is set as a variable.

[0006] A second aspect of the present invention is the method for designing an ophthalmic lens according to the first aspect, wherein the feature amount includes a defocus dioptric power of the defocus region.

[0007] A third aspect of the present invention is a method for designing an ophthalmic lens according to the first aspect, further comprising a step (C) before performing step (D) the above, which involves calculating a sensitivity that indicates how much the characteristic quantity changes when the manufacturing conditions are changed, and in step (D) the manufacturing conditions are determined using the sensitivity.

[0008] A fourth aspect of the present invention is the method for designing an ophthalmic lens according to the first aspect, wherein the target state is a state in which the smaller of the upper limit margin and the lower limit margin exceeds a specified threshold or reaches its maximum value.

[0009] A fifth aspect of the present invention is a method for designing an ophthalmic lens according to the first aspect, wherein the target state is a state in which the absolute value of the difference between the upper limit margin and the lower limit margin is less than or equal to a specified threshold, or is the minimum value.

[0010] A sixth aspect of the present invention is a method for designing an ophthalmic lens according to the first aspect, wherein in step (B), the histogram is decomposed into a plurality of distribution functions, and the maximum and minimum values ​​of the feature are calculated from the statistics of each distribution function.

[0011] A seventh aspect of the present invention is a method for designing an ophthalmic lens according to the sixth aspect, wherein in step (D), the upper limit margin and the lower limit margin are normalized using the standard deviation of each distribution function, and the manufacturing conditions are determined.

[0012] An eighth aspect of the present invention is a method for designing an ophthalmic lens according to the sixth aspect, wherein the ophthalmic lens further has a central clear region that realizes the wearer's prescribed refractive power and is positioned between the functional regions, and in step (B), the defocus regions are grouped according to the arrangement direction or arrangement distance of the defocus regions as viewed from the central clear region, and the histogram is decomposed into a plurality of distribution functions for each group.

[0013] A ninth aspect of the present invention is a method for designing an ophthalmic lens according to the sixth aspect, wherein in step (B), a plurality of ophthalmic lenses are grouped according to their prescribed refractive power, and the histogram is decomposed into a plurality of distribution functions for each group.

[0014] A tenth aspect of the present invention is a method for designing an ophthalmic lens according to the sixth aspect, wherein the ophthalmic lens is a lens coated by a dipping method, and in step (B), during dipping, the defocused region is grouped into a defocused region arranged in the upper direction and a defocused region arranged in the lower direction, and the histogram is decomposed into a plurality of distribution functions for each group.

[0015] An eleventh aspect of the present invention is a method for designing an ophthalmic lens according to the first aspect, wherein in step (A), the characteristic quantities of a plurality of defocus regions arranged at different positions are measured, and the same measurement is performed on a plurality of ophthalmic lenses.

[0016] A twelfth aspect of the present invention is the method for designing an ophthalmic lens according to the first aspect, wherein the manufacturing conditions determined in step (D) include mold conditions or coating conditions during the manufacture of the ophthalmic lens.

[0017] A thirteenth aspect of the present invention is a method for designing an ophthalmic lens according to the first aspect, wherein in step (D), manufacturing conditions are determined such that the average value of the feature quantity moves away from the midpoint between the allowable upper limit and the allowable lower limit of the feature quantity.

[0018] A fourteenth aspect of the present invention is a method for designing an ophthalmic lens as described in the first aspect, wherein in step (A), a plurality of different types of feature quantities are measured, and the target state is a state in which the smallest of the normalized upper and lower margins of each type of feature quantity exceeds a specified threshold or reaches its maximum value.

[0019] A fifteenth aspect of the present invention is a method for designing an ophthalmic lens according to the first aspect, wherein step (D) includes a step of calculating or displaying how the upper limit margin and the lower limit margin change when the manufacturing conditions are changed.

[0020] A sixteenth aspect of the present invention is a method for manufacturing an ophthalmic lens having a functional region having a base region that realizes the wearer's prescribed refractive power and a plurality of defocus regions having refractive powers different from the prescribed refractive power, comprising: a step (A) of measuring the feature quantities of the defocus regions under predetermined manufacturing conditions and obtaining a histogram of the feature quantities; a step (B) of determining the maximum and minimum values ​​of the feature quantities that are actually observed in the histogram or that can be observed with a predetermined probability; a step (D) of determining manufacturing conditions that achieve a target state set with at least one of an upper limit margin, which is the difference between the maximum value of the feature quantities and the allowable upper limit of the feature quantities, and a lower limit margin, which is the difference between the allowable lower limit of the feature quantities and the minimum value of the feature quantities, as variables; and a step (E) of manufacturing an ophthalmic lens according to the manufacturing conditions determined in step (D).

[0021] According to one embodiment of the present invention, the risk of features in the defocused region falling outside the acceptable range can be minimized.

[0022] Figure 1 is an example of a histogram when the distribution of defocus power within a lens is represented by a single normal distribution. Figure 2 is an example of a histogram when the manufacturing conditions are corrected to bring the representative value closer to the target value, compared to the example shown in Figure 1. Figure 3 is an example of a histogram showing the distribution of defocus power within a lens in an actual myopia progression suppression lens. Figure 4 is an example of a histogram when the manufacturing conditions are corrected to bring the representative value closer to the target value, compared to the example shown in Figure 3. Figure 5 is an example of a histogram when the manufacturing conditions are corrected using the method of the present invention, compared to the example shown in Figure 3. Figure 6 is a schematic plan view of the object-side surface of the spectacle lens to be designed in the first embodiment of the present invention. Figure 7 is a flowchart of the design method for spectacle lenses in the first embodiment of the present invention. Figure 8 is a histogram of defocus power in the feature quantity histogram acquisition process of the first embodiment of the present invention. Figure 9 is a decomposition of the histogram of defocus power into multiple distribution functions in the maximum / minimum value acquisition process of the first embodiment of the present invention. Figure 10 is a histogram of the defocus frequency when the manufacturing conditions are changed in the sensitivity study step of the first embodiment of the present invention. Figure 11 is a plot showing the changes in the upper and lower margins in the manufacturing condition determination step of the first embodiment of the present invention. Figure 12 is a histogram of the defocus frequency when the manufacturing conditions are optimized in the manufacturing condition determination step of the first embodiment of the present invention. Figure 13 is a diagram showing the shape of the defocus region at the top of the lens according to an embodiment of the present invention. Figure 14 is a diagram showing the shape of the defocus region at the bottom of the lens according to an embodiment of the present invention. Figure 15 is a plot showing the margins to the tolerance values ​​of each feature quantity according to an embodiment of the present invention.

[0023] <Inventor's Findings> Most myopia progression suppression lenses have functional regions on the lens surface in which a region with a prescribed power (base region) and a region that provides high contrast at a point different from the image formation position according to the prescribed power (defocus region) are discretely scattered. The defocus region has many optical or morphological characteristics such as diameter, height, curvature, defocus power, asphericity, and, if a coating film is present, film thickness. In this specification, the defocus power may be any of the following (1) to (4), or equivalent: (1) The difference in transmitted refractive power between the base region and the defocus region under lens wear or measurement system conditions. (2) The value obtained by multiplying the difference in curvature between the base region and the defocus region by the influence of refractive power and the influence of the angle of incidence. (3) An alternative value using the height of the defocus region relative to the base region (especially the boundary between the defocus region and the base region). (4) The difference between the point where the optical indicators (MTF, spot intensity, etc.) are best for the luminous beam passing through the base region and the luminous beam passing through the defocus region, respectively. Furthermore, the defocus degree may be treated not only as the mean spherical degree, but also as the degree in a specific direction or the degree in the direction of maximum or minimum.

[0024] The effectiveness of myopia progression-inhibiting lenses in inhibiting myopia progression is confirmed, for example, through clinical trials. However, what is confirmed in such trials is merely that a predetermined effect exists within a certain range of product characteristics (features in the defocus region), and it is not shown that the effect increases as the product approaches a specific set of product characteristics (features in the defocus region).

[0025] Considering the above situation, there is little point in performing basic manufacturing condition optimization by representing the characteristic quantities of the defocus region of the entire lens with a single value (e.g., the average value) and bringing it closer to a single target value. In myopia progression suppression lenses, the characteristic quantity (target value) that provides the best effect is often not fixed at a specific value, and as described in Patent Document 1, the characteristic quantities of the defocus region exhibit different statistical quantities depending on various factors such as their position on the lens.

[0026] The following describes the case where the defocused power is used as a feature of the defocused region. For example, as shown in Figure 1, if the distribution of defocused powers within the lens is represented by a single normal distribution, it is acceptable to use the simple mean of the defocused powers as the representative value. Then, as shown in Figure 2, the midpoint between the upper limit (tolerable upper limit) and lower limit (tolerable lower limit) of the defocused power that is considered to have a myopia progression suppression effect can be set as the target value, and the manufacturing conditions (e.g., the shape of the mold) can be corrected so that the representative value approaches the target value. This minimizes the risk that the myopia progression suppression effect will not be guaranteed (the defocused power will be outside the acceptable range).

[0027] However, as shown in Figure 3, in actual myopia progression-inhibiting lenses, the distribution of defocus power within the lens forms a complex histogram. Figure 3 shows, as an example, a case where, when dipping the lens substrate in a hard coat solution, defocus regions positioned in the upper direction have a higher defocus power with less variation, while defocus regions positioned in the lower direction have a lower defocus power with greater variation. In this case, as shown in Figure 4, if a simple average of the defocus powers is used as a representative value and a correction is made to bring the representative value closer to the target value, it may exceed the acceptable range of defocus powers (the lower limit of the acceptable range in Figure 4), potentially resulting in a counterproductive effect.

[0028] The inventor diligently researched the problems described above. As a result, as shown in Figure 5, a method was found to optimize manufacturing conditions to achieve a target state (for example, a state where the smaller of the upper and lower margins exceeds a specified threshold or reaches its maximum value) by setting at least one of the following as variables: the upper margin, which is the difference between the maximum value of the defocus power and the upper limit of the allowable defocus power; and the lower margin, which is the difference between the lower limit of the allowable defocus power and the minimum value. The method of the present invention (hereinafter also referred to as "this method") minimizes the risk of the defocus power falling outside the allowable range. Furthermore, as can be seen from Figures 3 and 5, this method may also make corrections so that the average value of the defocus power moves away from the midpoint between the lower and upper limits of the allowable defocus power. As mentioned above, in myopia progression suppression lenses, there is no specific value for the defocus power (target value) that provides the best effect, and this method does not aim for an intermediate value.

[0029] Of course, this method can also be applied to features other than defocus power (for example, diameter, height, curvature, asphericity, coating film thickness, etc., of the defocus region). The error factors for such defocus region features are diverse. For example, these include changes in manufacturing trends over time due to deterioration of molds and coating agents due to repeated molding and film deposition, differences in trends due to the position of the lens in the rack during coating by the dipping method, differences due to differences in base curves, differences in trends dependent on the base curve when coating lenses with different base curves simultaneously, differences in coating trends due to processing different prescription powers from the same type of lens blank, and prescription power dependence during feature measurement (for example, the larger the prescription power, the more the measured value is likely to vary due to the refractive power and prism effect of the lens). According to this method, even when manufacturing lenses with different prescription powers using the same process, the manufacturing conditions can be optimized and the risk of features falling outside the acceptable range can be minimized.

[0030] In this specification, feature quantities may include measurement errors, and manufacturing conditions may include measurement conditions. For example, when centering during measurement according to markings provided on a lens, the centering may shift depending on the marking's engraving accuracy and reading accuracy, potentially causing variations in measured values ​​such as the degree of defocus as a measurement error. In this case, the variation in the degree of defocus due to measurement error may be used as a feature quantity, and the marking's engraving conditions may be used as manufacturing conditions to improve the variation due to measurement error so that it falls within an acceptable range. Alternatively, the variation in the degree of defocus due to measurement error may be used as a feature quantity, and the camera sensitivity for reading the markings may be used as a manufacturing condition (measurement condition) to improve the variation due to measurement error so that it falls within an acceptable range.

[0031] [Details of Embodiments of the Invention] Next, one embodiment of the present invention will be described below with reference to the drawings. However, the present invention is not limited to these examples and is intended to include all modifications within the meaning and scope equivalent to the claims as shown in the claims.

[0032] The spectacle lenses described herein have an object-facing surface and an eye-facing surface. The "object-facing surface" is the surface that faces the object when the spectacle lenses are worn by the wearer, and the "eye-facing surface" is the opposite surface, that is, the surface that faces the eye when the spectacle lenses are worn by the wearer. This relationship also applies to the lens substrate that forms the basis of the spectacle lenses. In other words, the lens substrate also has an object-facing surface and an eye-facing surface.

[0033] In this specification, the eye point is, for example, the position through which the line of sight passes when the wearer is looking straight ahead while wearing eyeglasses, and this example will be given hereafter. The eye point may also be the position through which the line of sight passes when the wearer views an object close to the wearer (so to speak, when viewing at close range), i.e., the near-seeing eye point. In one embodiment of the present invention, an example is given in which the geometric center of the eyeglass lens before it is fitted into the frame coincides with the eye point, coincides with the prism reference point, and coincides with the lens center. The position of the eye point can be determined by referring to a remark chart or centration chart issued by the lens manufacturer.

[0034] <First Embodiment of the Invention> (1) Eyeglass Lens (Eye Lens) First, the eyeglass lens (eye lens) to be designed in this embodiment will be briefly described. Figure 6 is a schematic plan view of the object-side surface of the eyeglass lens 10 to be designed in this embodiment. As shown in Figure 6, the eyeglass lens 10 is a myopia progression suppression lens that has a myopia progression suppression effect, and comprises a central clear region 11, a functional region 12, and a peripheral clear region 15.

[0035] The central clear region 11 is, for example, a region that realizes the wearer's prescribed refractive power, includes the eye point of the spectacle lens 10, and is positioned to be sandwiched between the functional regions 12. In this specification, "sandwiched between the functional regions 12" refers to a state in which the central clear region 11 exists between the two functional regions 12 when viewed in a cross-section passing through a certain point within the central clear region 11. In this embodiment, the case in which the center of the central clear region 11 coincides with the eye point of the spectacle lens 10 is illustrated. The central clear region 11 is, for example, a transparent portion with a smooth surface shape, and is a region that causes a light beam incident from the object-side surface to exit from the eye-side surface, enter the wearer's pupil, and converge on the retina.

[0036] The central clear area 11 allows for the realization of the prescribed power (spherical power, astigmatism power, astigmatism axis, etc.). This spherical power may be the power to be corrected when looking straight ahead (distance from infinity to about 1 m) (distance vision power), or it may be the power to be corrected when looking at intermediate objects (distance from about 1 m to 40 cm) or near objects (distance from about 40 cm to 10 cm).

[0037] Furthermore, the central clear area 11 does not have any configurations intended to produce a myopia progression suppression effect or a hyperopia reduction effect (hereinafter also referred to as myopia progression suppression effect, etc.) (for example, defocus areas having convex or concave regions).

[0038] The central clear region 11 of this embodiment (and the base region 13 and peripheral clear region 15 within the functional region 12, which will be described later) functions as a so-called single-focus lens. Its surface shape is not particularly limited, but in this embodiment, the case in which the central clear region 11 is spherical is given as an example.

[0039] The functional region 12 is an annular region that has a refractive power different from the wearer's prescribed refractive power and is arranged to sandwich (or surround) the central clear region 11. In this embodiment, the functional region 12 has multiple defocus regions 14 (also called convex regions) arranged in an island-like manner (i.e., spaced apart from each other) as parts with a refractive power different from the wearer's prescribed refractive power. The multiple defocus regions 14 are, for example, arranged independently and discretely such that the center of each defocus region 14 is the vertex of an equilateral triangle. The arrangement of the defocus regions 14 is not particularly limited. In the functional region 12, the parts other than the defocus regions 14 are base regions 13 that perform the same function as the central clear region 11. The functional region 12 is, for example, a region in which a light beam incident from the object-side surface is emitted from the eye-side surface, while at least a portion of the light beam incident in the wearer's pupil is not focused onto the retina. As a result, the spectacle lens 10 of this embodiment exhibits a myopia progression suppression effect. In this specification, "planar view" refers to the view from the normal of the eye point on the outer surface (object-side surface or eye-side surface) of the spectacle lens 10, unless otherwise specified. The present invention is also effective when the configuration is applied to a planar view from an arbitrary point on the lens, such as the normal of the point to be evaluated, instead of a planar view from the normal of the eye point. Furthermore, the myopia progression suppression effect or hyperopia progression suppression effect is achieved by the light-gathering effect of the defocus region 14 in the functional region 12 toward the outside of the retina and / or the contrast-reducing effect on the retina.

[0040] Multiple defocus regions 14 may be formed on at least one of the object-side surface or the eye-side surface of the spectacle lens 10. Alternatively, the defocus regions 14 may be embedded between the object-side surface and the eye-side surface (inside the lens). In this embodiment, an example is given where multiple defocus regions 14 are provided only on the object-side surface of the spectacle lens 10. The surface shape of the defocus regions 14 is not particularly limited, but for example, it may be spherical. Of course, it may also be aspherical. It is preferable that the multiple defocus regions 14 within the functional region 12 satisfy either or both of the following conditions: (1) They collectively occupy 20% or more of the area of ​​the functional region 12 in order to exert a sufficient myopia progression suppression effect as a whole lens. (2) The centers (or vertices) of each defocus region 14 are separated by 0.2 mm or more in order to exert a sufficient light-gathering effect of each defocus region 14. In particular, if the defocus area 14 has a spherical shape, it is preferable that either or both of the following conditions (i) and (ii) are met: (i) The number of defocus areas 14 is 18 or more (ii) The number of defocus areas 14 is 5000 or less Also, if the defocus areas 14 are arranged in a concentric circle pattern with respect to a point on the lens, it is preferable that either or both of the following conditions (iii) and (iv) are met: (iii) The number of defocus areas 14 is 2 or more rings (iv) The number of defocus areas 14 is 50 or less

[0041] The peripheral clear area 15 is an annular region that provides the wearer's prescribed refractive power and surrounds the functional area 12. In this embodiment, the peripheral clear area 15 performs the same function as the central clear area 11. Furthermore, since the peripheral clear area 15 is provided along the outer circumference of the spectacle lens 10 so as to surround the functional area 12, peripheral vision is easily ensured.

[0042] Various commonly used lens substrates can be used as the lens substrate constituting the eyeglass lens 10. The lens substrate may be, for example, a plastic lens substrate or a glass lens substrate. The glass lens substrate may be, for example, a lens substrate made of inorganic glass. As a lens substrate, a plastic lens substrate is preferred from the viewpoint of being lightweight and less prone to breakage. Examples of plastic lens substrates include styrene resins such as (meth)acrylic resin, polycarbonate resin, allyl resin, allyl carbonate resin such as diethylene glycol bisallyl carbonate resin (CR-39), vinyl resin, polyester resin, polyether resin, urethane resin obtained by the reaction of an isocyanate compound with a hydroxyl compound such as diethylene glycol, thiourethane resin obtained by the reaction of an isocyanate compound with a polythiol compound, and cured products (generally called transparent resins) obtained by curing a curable composition containing a (thio)epoxy compound having one or more disulfide bonds in the molecule. The curable composition may also be called a polymerizable composition. As the lens substrate, an undyed one (colorless lens) or a dyed one (dyed lens) may be used. The thickness of the lens substrate is not particularly limited, but for example, the thickness (center thickness) may be about 0.7 to 30 mm. The refractive index of the lens substrate may be, for example, about 1.48 to 1.78. However, the refractive index of the lens substrate is not limited to this range, and may be within this range or outside of it. In this specification, refractive index refers to the refractive index for light with a wavelength of 546 nm.

[0043] (2) Method for designing spectacle lenses (ophthalmic lenses) Next, a method for designing a spectacle lens (ophthalmic lens) according to the present embodiment will be described. In the present embodiment, defocus power is treated as the feature value of the defocus region (hereinafter, also simply referred to as feature value), the manufacturing conditions are optimized by correcting the shape of the mold, and the case where the risk that the defocus power falls outside the allowable range (in the example of the present embodiment, 3.8 D or more and 5.2 D or less) is minimized will be described. FIG. 7 is a flowchart illustrating the method for designing a spectacle lens of the present embodiment. As shown in FIG. 7, the method for designing a spectacle lens of the present embodiment includes, for example, a feature value histogram acquisition step S100, a maximum value / minimum value acquisition step S110, a sensitivity study step S120, and a manufacturing condition determination step S130.

[0044] Note that, in the present specification, a feature value histogram is a general term for convenience that includes the frequency distribution, probability distribution, frequency density function, probability density function, frequency mass function, probability mass function of feature values, and graphed representations thereof, etc.

[0045] (Feature value histogram acquisition step S100) The feature value histogram acquisition step S100 is, for example, a step of measuring the feature value of the defocus region under predetermined manufacturing conditions to obtain a histogram of the feature values. In the present embodiment, spectacle lenses were manufactured using a mold with a shape designed to have a defocus power of 6.6 D, the distribution of the defocus power was measured, and a histogram was created. The histogram is shown in FIG. 8. Note that a known method can be used as the method for measuring the feature value.

[0046] In the feature value histogram acquisition step S100, the objects for measuring the feature value may be a plurality of defocus regions arranged at different positions within one spectacle lens, or may be defocus regions of a plurality of spectacle lenses. In the feature value histogram acquisition step S100, it is preferable to measure the feature values of a plurality of defocus regions arranged at different positions, and perform the same measurement on a plurality of spectacle lenses. This makes it possible to obtain a histogram that reflects both the intra-lens error and inter-lens error, allowing both errors to be handled collectively.

[0047] In the feature quantity histogram acquisition step S100, measured values of the feature quantity may be directly used to form a histogram, or adjustment such as shifting the measured values by a predetermined amount may be performed in consideration of deviations caused by other manufacturing conditions. For example, when the lens for which the feature quantity is measured is not a finished product but an uncoated lens, it is expected that feature quantities such as defocus power will change due to the coating process. In such a case, the amount of change in the feature quantity caused by other processes may be estimated, and adjustment such as shifting the measured value by a predetermined amount may be performed to create a histogram.

[0048] (Maximum Value / Minimum Value Acquisition Step S110) The maximum value / minimum value acquisition step S110 is a step of obtaining the maximum value and minimum value of a feature quantity that are actually observed in the histogram obtained in the feature quantity histogram acquisition step S100, or can be observed with a predetermined probability, for example. The most primitive method for obtaining the maximum value and minimum value is to directly adopt the maximum value and minimum value of the feature quantities (so-called raw data) measured in the feature quantity histogram acquisition step S100, respectively. Alternatively, the raw data may be converted into a standard deviation σ, and values of average value ± 2σ or average value ± 3σ may be used as substitutes for the maximum value and minimum value.

[0049] In the maximum value / minimum value acquisition step S110, it is preferable to decompose the histogram into a plurality of distribution functions (for example, simpler functions such as normal distribution), and obtain the maximum value and minimum value of the feature quantity from the statistics of each distribution function. In the present embodiment, as shown in FIG. 9, the histogram is decomposed into two normal distributions (distribution functions F1, F2), and the maximum value and minimum value of defocus power are obtained from the statistics of each distribution function. Specifically, the standard deviation σ of each distribution function is calculated, the largest value among the average values + 4σ of each distribution function is taken as the maximum value of the feature quantity in the histogram, and the smallest value among the average values - 4σ of each distribution function is taken as the minimum value of the feature quantity in the histogram. In a myopia progression suppression lens, there are a wide variety of error factors for the feature quantity of the defocus region, and the histogram of the feature quantity is likely to be multipolar (that is, it is difficult to form a simple single normal distribution). This method is particularly effective when handling such multipolar feature quantities. Note that the 4σ portion for obtaining the maximum value and minimum value may be replaced with other values such as 3σ.

[0050] In the maximum / minimum value acquisition step S110, when decomposing the histogram into multiple distribution functions, it is possible to decompose it mechanically using AI or the like, but it is more preferable to group the data while taking into account the error factors of the features. For example, it is preferable to group the defocused areas according to their arrangement direction or distance from the central clear area, and decompose the histogram into multiple distribution functions for each group. Defocused areas that are close in arrangement direction or distance from the central clear area tend to have similar feature dispersion trends. By considering defocused areas with similar trends as groups and decomposing each group into multiple distribution functions, it is possible to understand the feature dispersion in more detail, making it easier to optimize manufacturing conditions.

[0051] Furthermore, although this embodiment describes an example in which multiple defocus regions are discretely arranged, if multiple defocus regions are connected (in contact with each other), it is preferable to consider those connected defocus regions as a single group, and if there are multiple groups, to perform grouping.

[0052] Furthermore, for example, when manufacturing multiple spectacle lenses with different refractive powers using the same process, it is preferable to group them according to their refractive power and decompose the histogram into multiple distribution functions for each group. In myopia progression suppression lenses, the inclination of the surface where the defocus region is located differs depending on the size of the base curve, which tends to result in a histogram with multipolar features. This method allows for the optimization of manufacturing conditions for multiple spectacle lenses with different base curves all at once.

[0053] Furthermore, for example, when manufacturing spectacle lenses coated by the dipping method, it is preferable to group the defocused regions into those located in the upper direction and those located in the lower direction during the dipping process, and to decompose the histogram for each group into multiple distribution functions.

[0054] (Sensitivity Examination Step S120) The sensitivity examination step S120 is a step in which the sensitivity is calculated, for example, to show how much the feature quantity changes when the manufacturing conditions are changed. In this embodiment, eyeglass lenses were manufactured using a mold with a defocus power of 6.0D, and the distribution of the defocus power was measured to create a histogram. The histogram is shown in Figure 10. In the sensitivity examination step S120, the maximum and minimum values ​​may be compared by performing the same process as the feature quantity histogram acquisition step S100 and the maximum / minimum value acquisition step S110 after changing the manufacturing conditions, or if the variance of the histogram is expected to remain almost unchanged, only the extent to which the mean value of the feature quantity shifts may be examined. Performing the sensitivity examination step S120 makes it easier to optimize the manufacturing conditions in the manufacturing condition determination step S130 described later.

[0055] When there are multiple candidate manufacturing conditions to change, it is preferable to narrow down the number of manufacturing conditions to change to one (or about two) because changing many manufacturing conditions at once makes it difficult to grasp the trend of feature changes. In such cases, it is preferable to perform the sensitivity examination step S120 and select a manufacturing condition with good sensitivity (for example, one in which the feature changes linearly).

[0056] (Manufacturing Condition Determination Process S130) The manufacturing condition determination process S130 is a process in which a target state is set using at least one of the following as variables: the upper margin, which is the difference between the maximum value of the feature and the allowable upper limit of the feature, and the lower margin, which is the difference between the allowable lower limit of the feature and the minimum value of the feature, and the manufacturing conditions are determined in order to achieve the target state. If the sensitivity examination process S120 has been performed, it is preferable to use the calculated sensitivity to calculate the changes in the upper and lower margins and determine the manufacturing conditions. The manufacturing condition determination process S130 may also include a process to calculate or display how the upper and lower margins change when the manufacturing conditions are changed. In this embodiment, the plot shown in Figure 11 was obtained from the histograms shown in Figures 9 and 10.

[0057] When setting a target state, it is preferable to use the smaller of the upper and lower margin values ​​(hereinafter referred to as the Min value) as the variable. Ideally, the target state can be said to have been achieved when the Min value is sufficiently large. In that case, the other margins will automatically also become sufficiently large. Whether or not the margins are sufficiently large can be judged, for example, by the process capability index. Generally, a margin / σ exceeding 1.33 is considered to indicate sufficient process capability. If the above cannot be met under feasible manufacturing conditions, the risk of the feature quantity falling outside the acceptable range can be minimized by aiming to maximize the Min value under feasible manufacturing conditions. In other words, the target state can be rephrased as the state in which the Min value exceeds a specified threshold (for example, Min value / σ is 1.33) or reaches its maximum value. When the upper and lower margins change in a trade-off manner with changes in manufacturing conditions, maximizing the Min value is equivalent to minimizing the absolute value of the difference between the upper and lower margins. Furthermore, considering that in manufacturing, conditions are often set using discrete values ​​under feasible manufacturing conditions, and perfect equivalence is rare, the state in which the absolute value of the difference between the upper and lower margins is less than or equal to a specified threshold, or the minimum value thereof, is also treated as a target state. The threshold may be set based on the resolution achievable in manufacturing and measurement. For example, if the defocus frequency is used as a feature, the measurement resolution of the defocus frequency is 0.05D, so the threshold may be set to 0.05D.

[0058] In the example shown in Figure 11, a mold condition of 6.3D was adopted, where the upper and lower margins are equal. The histogram of the defocus frequency under this condition is shown in Figure 12. By optimizing the manufacturing conditions in this way, the risk of feature quantities falling outside the acceptable range can be minimized. Furthermore, feasible manufacturing conditions include not only keeping temperature and pressure conditions within a realistic range, but also rounding the conditions to a number of significant figures that is easy to understand during operation. For example, correcting the mold curve in units of 0.1D or adjusting the temperature in units of 1 degree corresponds to rounding the conditions to a number of significant figures that is easy to understand during operation.

[0059] In the manufacturing condition determination step S130, the upper and lower margins may be normalized using the standard deviation σ of each distribution function decomposed in the maximum and minimum value acquisition step S110, and the manufacturing conditions may be determined to achieve the target state set with the normalized margins as variables. Specifically, the target state is defined as the state in which the smaller of (upper margin / 2σ of the distribution function from which the maximum value was obtained) and (lower margin / 2σ of the distribution function from which the minimum value was obtained) exceeds a specified threshold or reaches its maximum value, and the manufacturing conditions are determined accordingly. For example, if the difference in the standard deviations σ of each distribution function is large, more specifically, if the ratio of the maximum standard deviation σMax to the minimum standard deviation σMin (σMax / σMin) of each distribution function is 1.5 or more, it is preferable to perform such normalization. Note that the 2σ part when normalizing the margins may be replaced with other values ​​such as 3σ.

[0060] In the manufacturing condition determination process S130, manufacturing conditions may be adopted (determined) such that the average value of the feature quantities moves away from the midpoint between the acceptable upper and lower limits of the feature quantities. This is because, in the case of myopia progression suppression lenses, there is no specific target value for which the best effect is achieved, and this method does not aim for the midpoint.

[0061] Furthermore, the present invention can also be applied as a method for manufacturing eyeglass lenses (eye lenses). In this case, a process for manufacturing eyeglass lenses (eye lenses) (eye lens manufacturing process) can be further carried out according to the manufacturing conditions determined in the manufacturing condition determination process S130.

[0062] <Other Embodiments of the Invention> Although embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit of the invention.

[0063] For example, in the embodiment described above, the case where the defocus frequency is used as the feature quantity of the defocus region was explained, but this method can also be applied to features other than the defocus frequency (e.g., diameter, height, curvature, asphericity, coating film thickness of the defocus region, etc.). Furthermore, this method can also handle multiple different types of features at once. In this case, in the feature histogram acquisition step S100, multiple different types of features can be measured and multiple histograms can be created. In the maximum / minimum value acquisition step S110, it is preferable to decompose the histogram into multiple distribution functions. Also, in the manufacturing condition determination step S130, the target state is determined when the smallest of the upper and lower margins of each type of feature, normalized by the standard deviation σ of each distribution function, exceeds a specified threshold or reaches the maximum value, and the manufacturing conditions can be determined. By normalizing (non-dimensioning) the upper margin (lower margin) by, for example, 2σ, multiple features with different units can be considered at once.

[0064] Furthermore, although the above embodiment described a case in which manufacturing conditions are optimized by correcting the shape of the mold, the manufacturing conditions to be optimized may be other conditions. Since the error factors of the feature quantities in the defocused region are often related to the mold conditions or coating conditions, it is preferable that the manufacturing conditions to be optimized (manufacturing conditions determined in the manufacturing condition determination step S130) include the mold conditions or coating conditions used in the manufacture of eyeglass lenses.

[0065] Furthermore, in cases where changes in manufacturing conditions directly affect the feature quantities, such as mold shape, the sensitivity examination step S120 may be omitted because it is easy to predict the fluctuations in the feature quantities.

[0066] Furthermore, while the above-described embodiment described the case where the target of the design is an eyeglass lens having a myopia suppression effect or a hyperopia reduction effect, it is also applicable to eyeglass lenses for other purposes (e.g., progressive power lenses, multifocal lenses, AR glasses, etc.). For example, it may be applied to eyeglass lenses with a functional area to stimulate the retina in order to suppress the progression of glaucoma, in which case it is reasonable to set the eye point at a point far from the geometric center of the eyeglass lens depending on the wearer's field of vision. It is also applicable to ophthalmic lenses such as optometric lenses, contact lenses, and IOLs (intraocular lenses).

[0067] Next, embodiments of the present invention will be described. These embodiments are examples of the present invention, and the present invention is not limited to these embodiments.

[0068] The inventors' research revealed that the shape of the defocused area changes depending on the ambient humidity during the coating process. Generally, the lower the humidity, the greater the height of the defocused area tends to be, but this behavior differs between the upper part of the lens (at the 12 o'clock position when viewed from the central clear area, towards the sky during dipping) and the lower part of the lens (at the 6 o'clock position when viewed from the central clear area, towards the ground during dipping).

[0069] In this embodiment as well, a lens with the configuration shown in Figure 6 was used. Defocus areas with a diameter of 1.0 mm are arranged in a staggered pattern at 1.5 mm intervals. There are no defocus areas in the area with a diameter of 11 mm from the center of the lens, and this area corresponds to the central clear area. The area outside of this and up to a diameter of 31 mm corresponds to the functional area.

[0070] Figure 13 shows the defocused area at the top of the lens (the fourth area from the 12 o'clock position from the lens center) and its surrounding area after the coating process, and Figure 14 shows the defocused area at the bottom of the lens (the fourth area from the 6 o'clock position from the lens center) and its surrounding area after the coating process. In both cases, the shape relative to the base shape is shown in μm on the vertical axis and mm on the horizontal axis.

[0071] As shown in Figure 13, the defocus region at the top of the lens increases in height while maintaining the same diameter when humidity is low (especially the area near the center bulges), thus increasing the degree of defocus. On the other hand, as shown in Figure 14, the defocus region at the bottom of the lens increases in both diameter and height simultaneously when humidity is low, so the degree of defocus remains almost unchanged.

[0072] If the diameter or height of the defocused area increases, the contrast of light focused onto the retina decreases. Therefore, these values ​​must also be kept within an acceptable range to achieve the myopia progression suppression effect. Furthermore, if the contrast on the retina is too high, it is undesirable because it results in insufficient light concentration outside the retina.

[0073] The above-mentioned case is one in which optimization is difficult with quality control based solely on the degree of defocus. Therefore, in this embodiment, we will describe a case in which three features of the defocus region—the degree of defocus, the height of the defocus region, and the diameter of the defocus region—are treated simultaneously to optimize the environmental humidity of the coating process.

[0074] First, we prepared several eyeglass lenses manufactured under environmental humidity conditions of 5% and several eyeglass lenses manufactured under environmental humidity conditions of 15%. We then grouped their characteristic features (defocus power, height, and diameter) into the defocus region at the top of the lens and the defocus region at the bottom of the lens and compiled the results. Table 1 shows the statistics for each characteristic feature.

[0075]

[0076] Next, Table 2 shows the maximum and minimum values ​​of each feature calculated from the statistics. Table 3 shows the acceptable upper and lower limits for each feature.

[0077]

[0078]

[0079] Based on these results, we plotted the margins (upper and lower limits) of each feature relative to its tolerance when the ambient humidity was varied. Each margin was normalized (dimensionless) by dividing it by 2σ of each feature. The results are shown in Figure 15.

[0080] As shown in Figure 15, the manufacturing condition in which the smallest of the normalized upper and lower margins for each feature was maximized was an ambient humidity of 19.5%. By adopting this condition, the risk of each feature falling outside the acceptable range can be minimized.

[0081] Based on the above, we have confirmed that the method of the present invention can minimize the risk of features in the defocused region falling outside the acceptable range, even when dealing with multiple different types of features.

[0082] Up to this point, we have described a method for optimizing the margin for acceptable ranges, assuming that there are no explicit targets for one or more features. On the other hand, there are features for which the target is clear. For example, the number of scratches and dirt on the lens surface, and surface roughness (excluding intentionally roughened areas), which are preferable to be zero, and spherical power and astigmatism power, which are standard functions of eyeglasses, which should be as prescribed. For simplicity, we will refer to the former as features without targets and the latter as features with targets below.

[0083] In the method of the present invention, the degree of deviation of the target feature from the target and the size of the margin of the untarget feature may be optimized sequentially (or simultaneously). For example, a condition range in which the target feature is sufficiently close to the target value may be calculated, and the condition in which the margin of the untarget feature is maximized within that condition range may be calculated. Alternatively, for example, a condition range in which the margin of the untarget feature is sufficiently large may be calculated, and the condition in which the target feature is closest to the target value within that condition range may be calculated. Alternatively, for example, the degree of deviation (or size) of the target feature from the target value and the size (or smallness) of the margin of the untarget feature may be used as scores, and these may be optimized simultaneously.

[0084] 10 Eyeglass lens 11 Central clear area 12 Functional area 13 Base area 14 Defocus area 15 Peripheral clear area S100 Feature histogram acquisition process S110 Maximum / minimum value acquisition process S120 Sensitivity examination process S130 Manufacturing condition determination process

Claims

1. A method for designing an ophthalmic lens having a functional region having a base region that realizes the wearer's prescribed refractive power and a plurality of defocus regions having refractive powers different from the prescribed refractive power, comprising: (A) measuring the feature quantities of the defocus regions under predetermined manufacturing conditions and obtaining a histogram of the feature quantities; (B) determining the maximum and minimum values ​​of the feature quantities that are actually observed in the histogram or that can be observed with a predetermined probability; and (D) determining manufacturing conditions that achieve a target state set with at least one of the following as variables: an upper margin which is the difference between the maximum value of the feature quantities and the allowable upper limit of the feature quantities, and a lower margin which is the difference between the allowable lower limit of the feature quantities and the minimum value of the feature quantities.

2. The method for designing an ophthalmic lens according to claim 1, wherein the feature quantity includes the defocusing power of the defocused region.

3. The method for designing an ophthalmic lens according to claim 1, further comprising a step (C) of calculating a sensitivity that indicates how much the feature quantity changes when the manufacturing conditions are changed, before performing step (D), wherein the manufacturing conditions are determined using the sensitivity in step (D).

4. The method for designing an ophthalmic lens according to claim 1, wherein the target state is a state in which the smaller of the upper limit margin and the lower limit margin exceeds a specified threshold or reaches its maximum value.

5. The method for designing an ophthalmic lens according to claim 1, wherein the target state is a state in which the absolute value of the difference between the upper limit margin and the lower limit margin is less than or equal to a specified threshold, or is the minimum value thereof.

6. The method for designing an ophthalmic lens according to claim 1, wherein in step (B), the histogram is decomposed into a plurality of distribution functions, and the maximum and minimum values ​​of the feature are calculated from the statistics of each distribution function.

7. The method for designing an ophthalmic lens according to claim 6, wherein in step (D), the upper and lower margins are normalized using the standard deviations of each distribution function, and the manufacturing conditions are determined.

8. The method for designing an ophthalmic lens according to claim 6, wherein the ophthalmic lens has a central clear region that realizes the wearer's prescribed refractive power and is positioned between the functional regions, and in step (B), the defocus regions are grouped according to the orientation or distance of the defocus regions as viewed from the central clear region, and the histogram is decomposed into a plurality of distribution functions for each group.

9. The method for designing an ophthalmic lens according to claim 6, wherein in step (B), a plurality of ophthalmic lenses are grouped according to their prescribed refractive power, and the histogram is decomposed into a plurality of distribution functions for each group.

10. The method for designing an ophthalmic lens according to claim 6, wherein the ophthalmic lens is a lens coated by a dipping method, and in step (B), during dipping, the defocused region is divided into a group of defocused regions arranged in the upper direction and a group of defocused regions arranged in the lower direction, and the histogram is decomposed into a plurality of distribution functions for each group.

11. The method for designing an ophthalmic lens according to claim 1, wherein in step (A), the characteristic quantities of a plurality of defocus regions arranged at different positions are measured, and the same measurement is performed on a plurality of ophthalmic lenses.

12. The method for designing an ophthalmic lens according to claim 1, wherein the manufacturing conditions determined in step (D) include mold conditions or coating conditions used in the manufacture of ophthalmic lenses.

13. The method for designing an ophthalmic lens according to claim 1, wherein in step (D), manufacturing conditions are determined such that the average value of the feature quantity moves away from the midpoint between the allowable upper limit and the allowable lower limit of the feature quantity.

14. The method for designing an ophthalmic lens according to claim 1, wherein in step (A), a plurality of different types of feature quantities are measured, and the target state is a state in which the smallest of the normalized upper and lower margins of each type of feature quantity exceeds a specified threshold or reaches its maximum value.

15. The method for designing an ophthalmic lens according to claim 1, wherein step (D) includes a step of calculating or displaying how the upper limit margin and the lower limit margin change when the manufacturing conditions are changed.

16. A method for manufacturing an ophthalmic lens having a functional region having a base region that realizes the wearer's prescribed refractive power and a plurality of defocus regions having refractive powers different from the prescribed refractive power, comprising: (A) measuring the feature quantities of the defocus regions under predetermined manufacturing conditions and obtaining a histogram of the feature quantities; (B) determining the maximum and minimum values ​​of the feature quantities that are actually observed in the histogram or that can be observed with a predetermined probability; (D) determining manufacturing conditions that achieve a target state set with at least one of the following as variables: an upper margin which is the difference between the maximum value of the feature quantities and the allowable upper limit of the feature quantities, and a lower margin which is the difference between the allowable lower limit of the feature quantities and the minimum value of the feature quantities; and (E) manufacturing an ophthalmic lens according to the manufacturing conditions determined in step (D).

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