Spectacle lens and method for measuring power

Abstract

Provided is a spectacle lens comprising a center clear region that achieves a wearer's prescription dioptric power and that includes an eye point and a functional region that is provided so as to surround the center clear region, wherein: the functional region has a base region that achieves the prescription dioptric power and a plurality of defocus regions that have a dioptric power differing from the prescription dioptric power; when a prescribed diameter of 4-6 mm is represented as φ, in a plan view, at least one of the defocus regions is inside a virtual circle C that has the diameter φ and that is centered on a point P inside the functional region, and there are no defocus regions on the virtual circle C; and a marking indicating the point P is provided.

Description

Eyeglass lenses and prescription measurement methods

[0001] The present invention relates to a spectacle lens and a method for measuring the power.

[0002] There are two methods for evaluating optical elements such as lenses: surface measurement and transmission measurement. The former is useful for understanding the quality of each front and rear surface, while the latter is useful for managing the quality of the lens as a whole. A typical transmission measurement is wavefront measurement using an interferometer or similar. Wavefront measurement can directly obtain wavefront information including aberrations up to higher orders, but it is only applicable to lenses that are close to aberration-free. One method that can be applied to lenses with large aberrations is power distribution measurement, which examines the wavefront curvature of a small beam of light by passing many small beams of light through the lens. The disadvantage of power distribution measurement is that it can only obtain wavefront information as a distribution of local curvature.

[0003] In the case of eyeglass lenses and contact lenses, power distribution measurement is often used because the lens as a whole has a structure that intentionally adds so-called aberrations such as astigmatism correction and addition, and the aberrations of interest are spherical power error and astigmatism, which are quantities that directly correspond to the wavefront curvature, when viewed in units of a light beam with a diameter of about 4 mm that passes through the pupil. For example, the device described in Patent Document 1 measures local power per minute light beam with a diameter of 0.5 mm.

[0004] Japanese Patent Application Laid-Open No. 2004-205438

[0005] However, spectacle lenses (myopia progression suppressing lenses) that have recently appeared and are effective in suppressing the progression of myopia have functional regions in which areas where prescription power is provided (base regions) and areas where defocus is provided (defocus regions) are discretely scattered, even within a light beam passage range of about 4 mm in diameter that passes through the pupil, and are systems that include ultra-high-order aberrations.

[0006] In evaluating the power of myopia progression suppression lenses, the power (macro power) that indicates where a light beam with a thickness equivalent to the wearer's pupil diameter is focused is important. It is particularly important to evaluate the macro power within the functional area where the base area and the defocus area are mixed. For example, a simple method for evaluating the defocus power of a defocus area is to compare the power of the defocus area with the power of the central clear area (described below). However, considering the influence of the light incident angle, etc., it is more accurate to compare the power of the defocus area with the macro power of the light beam range including the defocus area. Hereinafter, in this specification, unless otherwise specified, the macro power refers to the macro power within the functional area.

[0007] On the other hand, it is difficult to calculate macro power from the local power measured by a power distribution measuring device for an area with a complex structure such as a functional area. The reason for this will be described in detail later.

[0008] An object of one embodiment of the present invention is to provide a spectacle lens that allows easy measurement of macro power.

[0009] A first aspect of the present invention is a spectacle lens having: a central clear area that realizes the prescribed refractive power of a wearer and includes the eye point; and a functional area that is arranged to surround the central clear area, wherein the functional area has a base area that realizes the prescribed refractive power and a plurality of defocus areas having refractive powers different from the prescribed refractive power, and wherein φ is a predetermined diameter that is equal to or greater than 4 mm and equal to or less than 6 mm, and wherein, in a planar view, at least one of the defocus areas exists within an imaginary circle C of diameter φ centered on a point P in the functional area, and no defocus area exists on the imaginary circle C, and wherein the spectacle lens has an inscription indicating the point P.

[0010] A second aspect of the present invention is the eyeglass lens according to the first aspect, wherein, in a planar view, the defocus area does not exist within an annular area from a virtual circle C1 having a diameter of 0.98φ or less and centered on the point P to a virtual circle C2 having a diameter of 1.02φ or more.

[0011] A third aspect of the present invention is the spectacle lens according to the first or second aspect, further comprising an inscription indicating the value of φ.

[0012] A fourth aspect of the present invention is the spectacle lens according to any one of the first to third aspects, wherein the marking indicating the point P is present within the defocus area.

[0013] A fifth aspect of the present invention is a method for measuring macro power, which is the mean spherical power in a predetermined light flux range within the functional area, in a spectacle lens having a central clear area that realizes the wearer's prescribed refractive power and includes the eye point, and a functional area that is arranged to surround the central clear area, wherein the functional area has a base area that realizes the prescribed refractive power and a plurality of defocus areas having a refractive power different from the prescribed refractive power, the method comprising: (a) checking an engraving that indicates a point P within the functional area; and (b) measuring local power within a range of diameter φ centered on point P, where φ is a predetermined diameter that is equal to or greater than 4 mm and equal to or less than 6 mm, and the macro power is the average of the local powers.

[0014] A sixth aspect of the present invention is the method for measuring dioptric power according to the fifth aspect, wherein in the step (a), an inscription indicating the value of φ is further confirmed.

[0015] According to one embodiment of the present invention, it is possible to provide a spectacle lens that allows easy measurement of macro power.

[0016] Fig. 1 is a cross-sectional schematic diagram of a myopia progression inhibiting lens. Fig. 2 is an example of a histogram of local power distribution of a myopia progression inhibiting lens. Fig. 3 is a schematic diagram of a case where macro power is evaluated in a light beam range of diameter φ in a myopia progression inhibiting lens. Fig. 4 is a planar schematic diagram of the object-side surface of a spectacle lens 10 according to a first embodiment of the present invention. Fig. 5 is an enlarged planar schematic diagram of the vicinity of region Z1 shown in Fig. 4. Fig. 6 is an enlarged planar schematic diagram of the vicinity of region Z1 shown in Fig. 4.

[0017] <Findings Obtained by the Inventor> First, the reason why it is difficult to evaluate macro power in a typical myopia progression inhibiting lens will be explained. FIG. 1 is a cross-sectional schematic diagram of a myopia progression inhibiting lens. For details of the myopia progression inhibiting lens, see, for example, U.S. Patent Application Publication No. 2017 / 0131567. Here, an example is shown in which convex regions (defocus regions) with a defocus power of +4D and a diameter of 0.8 mm are provided at 1.2 mm intervals on a surface with a prescription power (base power) of 0D. In this example, the designed macro power is 0D, the same as the base power.

[0018] There are two main simple methods for calculating macro power from the local power distribution per minute beam of light. The first method is to determine it from a histogram of the local power distribution. Figure 2 shows a histogram of the local power distribution in the above example. Ideally, the peak on the high-power side of the histogram corresponds to the defocus power, and the peak on the low-power side corresponds to the base power. However, as shown in Figure 2, while the peak on the high-power side corresponds to a defocus power of +4D, the peak on the low-power side (-1.8D) is significantly different from the base power of 0D. This is because, when measuring local power, the boundary between the defocus region and the base region is considered to be a concave surface, as shown by the dashed line in Figure 1.

[0019] The second method is to take the average of all local powers within the light beam range corresponding to the pupil diameter. The unknown wavefront at coordinates (x, y) on the lens is defined as w(x, y). Hereinafter, the coordinates (x, y) are assumed to be continuous values, the minute light beam for measuring the local power is assumed to be sufficiently small, and the local power s(x, y) can be expressed as the second derivative of the wavefront as shown in the following equation.

[0020]

[0021] The average local power s (overline) in a light beam (corresponding to the pupil diameter) of diameter φ and radius u can be expressed by the following formula.

[0022]

[0023] According to Green's theorem, the surface integral of the second derivative of x can be replaced with a line integral. The same applies to the second derivative of y. Therefore, the average local frequency s (overline) can be expressed by the following formula:

[0024]

[0025] From the integral range of the above formula, it can be seen that the average s (overline) of the local power is determined only by the wavefront gradient at the outer periphery of the light beam. In other words, only the wavefront gradient at the outer periphery of the light beam is considered, and the wavefront within the light beam is completely ignored. Therefore, if the outer periphery of the light beam has a discontinuous portion or a similar structure, the value of the macro power will fluctuate significantly. Figure 3 is a schematic diagram of the evaluation of the macro power of the light beam range of diameter φ in a myopia progression suppression lens. In Figure 3, the dashed line schematically represents the evaluated macro power (curvature). For example, as shown on the left side of Figure 3, when the outer periphery (end) of the light beam is the base region, the macro power is evaluated as = base power = 0D. However, as shown on the right side of Figure 3, when the outer periphery of the light beam is in the gradient portion of the defocus region (the portion where the wavefront has a gradient), the macro power is considered negative, just like a concave power.

[0026] The inventors have conducted extensive research into the above-mentioned problems and have found that, as shown on the left side of Figure 3, if the power of a spectacle lens can be measured so that the outer periphery of the light beam always becomes the base region, it is possible to correctly evaluate the macro power even if the average of the local powers is used. The present invention is also useful for quality control of spectacle lenses, as it makes it easy to measure and evaluate the macro power even for lenses that have discontinuous portions or similar structures, such as myopia progression control lenses.

[0027] [Details of the embodiment of the present invention] Next, an embodiment of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0028] The spectacle lenses mentioned in this specification have an object-side surface and an eyeball-side surface. The "object-side surface" is the surface that is located on the object side when a wearer wears spectacles equipped with the spectacle lens, and the "eyeball-side surface" is the opposite, i.e., the surface that is located on the eyeball side when a wearer wears spectacles equipped with the spectacle lens. This relationship also applies to the lens substrate that forms the basis of the spectacle lens. In other words, the lens substrate also has an object-side surface and an eyeball-side surface.

[0029] In this specification, the eyepoint is, for example, the position through which the line of sight passes when wearing eyeglasses and looking straight ahead, and this example will be given hereinafter. The eyepoint may also be the position through which the line of sight passes when the wearer views an object close to the wearer (i.e., when viewing close up), i.e., the near eyepoint. In one aspect of the present invention, an example is given in which the geometric center of the eyeglass lens before framing coincides with the eyepoint, coincides with the prism reference point, and coincides with the lens center. The eyepoint can be identified by referring to a remark chart or centration chart issued by the lens manufacturer.

[0030] <First embodiment of the present invention> (1) Spectacle lens Fig. 4 is a plan view schematic diagram of the object-side surface of a spectacle lens 10 of this embodiment. As shown in Fig. 4, the spectacle lens 10 of this embodiment is a myopia progression suppression lens that has the effect of suppressing the progression of myopia, and has a central clear area 11, a functional area 12, and a peripheral clear area 15.

[0031] The central clear area 11 is an area that realizes the prescribed refractive power of the wearer and includes the eye point of the eyeglass lens 10. In this embodiment, an example is shown in which the center of the central clear area 11 coincides with the eye point of the eyeglass lens 10. The central clear area 11 is, for example, a transparent part having a smooth surface shape, and is an area that causes a light beam that has entered from the surface on the object side to exit from the surface on the eyeball side, enter the pupil of the wearer, and converge on the retina.

[0032] The prescribed power (spherical power, astigmatic power, astigmatic axis, etc.) can be achieved by the central clear region 11. This spherical power may be a power (distance power) to be corrected when viewing straight ahead (when the distance to an object is from infinity to about 1 m), or may be a power to be corrected when viewing at intermediate distances (when the distance to an object is from about 1 m to 40 cm) or near distances (when the distance to an object is from about 40 cm to 10 cm).

[0033] Furthermore, the central clear area 11 does not have any configuration (e.g., a convex area or a concave area) intended to have the effect of inhibiting the progression of myopia or the effect of reducing hyperopia (hereinafter also referred to as the effect of inhibiting the progression of myopia, etc.).

[0034] The central clear area 11 of this embodiment (and the base area 13 and peripheral clear area 15 in the functional area 12, which will be described later) functions as a so-called single-focus lens. There are no particular limitations on the surface shape, but this embodiment illustrates a case in which the central clear area 11 has a spherical shape.

[0035] The functional region 12 is an annular region having a portion with a refractive power different from the wearer's prescribed refractive power, and is provided to surround the central clear region 11. In this embodiment, the functional region 12 is provided with a plurality of defocus regions 14 (also referred to as convex regions) in an island shape (i.e., spaced apart and not adjacent to each other) as portions with a refractive power different from the wearer's prescribed refractive power. The plurality of defocus regions 14 are independently and discretely arranged, for example, so that the centers of the defocus regions 14 form vertices of equilateral triangles. The portion of the functional region 12 other than the defocus regions 14 is a base region 13 that performs the same function as the central clear region 11. The functional region 12 is, for example, a region that causes a light beam incident from the object-side surface to exit from the eyeball-side surface, while preventing at least a portion of the light beam incident into the wearer's pupil from converging onto the retina, thereby allowing the eyeglass lens 10 of this embodiment to have an effect of suppressing the progression of myopia. In this specification, unless otherwise specified, the term "planar view" refers to the state when viewed from the normal to the eyepoint of the outer surface (object-side surface or eyeball-side surface) of the spectacle lens 10. The present invention is effective even when the configuration is applied to a planar view viewed from any point on the lens, such as the normal to the point to be evaluated, instead of the planar view viewed from the normal to the eyepoint. The myopia progression suppression effect or hyperopia progression suppression effect is achieved by the light focusing effect outside the retina and / or the contrast reduction effect on the retina of the defocus region 14 in the functional region 12.

[0036] The multiple defocus regions 14 may be formed on at least one of the object-side surface and the eyeball-side surface of the eyeglass lens 10. Alternatively, they may be formed so as to be embedded between the object-side surface and the eyeball-side surface (inside the lens). If the defocus regions 14 are embedded, it is difficult for a third party to identify the position of the defocus regions 14 using reflected light as a clue. While this is aesthetically pleasing, it is less easy to perform fitting and manufacturing processes. Therefore, an engraving (described later) indicating the position and range of the defocus regions 14 is useful. In this case, the engraving is easier to see if it is on the lens surface, but it may be embedded in the same way as the defocus regions 14 to protect the engraving and suppress excessive reflection. This embodiment illustrates a case where multiple defocus regions 14 are provided only on the object-side surface of the eyeglass lens 10. The surface shape of the defocus regions 14 is not particularly limited, but may be, for example, a spherical shape. The number of the multiple defocus regions 14 in the functional region 12 is not particularly limited, but may be, for example, 20 to 500.

[0037] FIG. 5 is an enlarged schematic plan view of the vicinity of region Z1 shown in FIG. 4 . As shown in FIG. 5 , the eyeglass lens 10 of this embodiment has markings 20A and 20B. The markings 20A and 20B are formed, for example, at a position where one of the defocus regions 14 of the functional region 12 is located. The markings 20A and 20B may be formed on the object-side surface or the eyeball-side surface. The markings 20A and 20B may also be formed on the lens substrate or on a coating film formed on the lens substrate. The method for forming the markings 20A and 20B is not particularly limited, and known methods such as laser marking can be used. The shape of the markings 20A and 20B is not particularly limited as long as they are visible. For example, they may be concave markings engraved into the lens surface, or convex markings (convex markings) transferred from markings engraved in a mold.

[0038] The marking 20A is a mark indicating point P, which is the center of the light beam range when measuring macro power. In the example shown in FIG. 5, the center of the cross mark indicates point P. The marking 20B is a mark indicating the light beam diameter φ when measuring macro power. For example, "40" shown in FIG. 5 indicates that φ is 4.0 mm. Note that since the light beam diameter φ corresponds to the pupil diameter of the wearer, in this embodiment, φ is set to at least one value between 4 mm and 6 mm. The value of φ may be, for example, the value of φ written on the lens bag or the like.

[0039] 5, the eyeglass lens 10 of this embodiment is configured such that, in a plan view, at least one defocus region 14 (seven in FIG. 5) exists within an imaginary circle C of diameter φ centered at point P in the functional region 12 (i.e., within the range of imaginary circle C), and no defocus region 14 exists on imaginary circle C (i.e., on an imaginary line representing imaginary circle C). As a result, when measuring macro power, by measuring local power within the range of imaginary circle C, the outer periphery of the light beam all becomes base region 13, making it possible to easily calculate macro power by averaging the local powers.

[0040] Furthermore, taking into consideration measurement errors of the power distribution measuring instrument, even if the virtual circle C (the range of light beams when measuring macro power) is slightly shifted or deformed, it is preferable that the entire outer periphery of the light beams becomes the base region 13. For example, if we consider a case where the defocus region 14 does not exist within the annular region from a virtual circle C1 whose diameter is slightly smaller than that of the virtual circle C to a virtual circle C2 whose diameter is slightly larger than that of the virtual circle C, the diameter φ of the virtual circle C1 is １ is 0.98φ or less, the diameter φ of the imaginary circle C2 ２ In addition, if the defocus area 14 exists just outside the measurement range, it becomes difficult for the measurer to determine the boundary of the defocus area 14, and there is a risk that the defocus area 14 will be included in the virtual circle C. Therefore, the diameter φ of the virtual circle C2 is preferably 1.02φ or more. ２ It is more preferable that the diameter is larger than 1.05φ. １ = 0.98φ), the virtual circle C2 (diameter φ ２1.05φ), an example will be shown in which the defocus area 14 does not exist within the annular area up to the diameter (φ=1.05φ). This makes it easier to measure macro power.

[0041] It is preferable that the area ratio of the defocus region 14 is, for example, 30% or more and 60% or less (more preferably 40% or more and 60% or less) within the virtual circle C. This makes it easier to compare, for example, the macro power and the defocus power.

[0042] The diameter of the defocus region 14 in a planar view is preferably, for example, 0.5 mm or more and 2.5 mm or less, and more preferably 0.8 mm or more and 1.4 mm or less. Under these conditions, it is easier to obtain the myopia progression suppression effect and to arrange the defocus region 14 in a manner that makes it easy to measure macro power. On the other hand, if the diameter of the defocus region 14 is less than 0.5 mm, it may be difficult to obtain the myopia progression suppression effect. Furthermore, if the diameter of the defocus region 14 exceeds 2.5 mm, an object may be viewed through the defocus region 14, and the myopia progression suppression effect may not be properly obtained. Note that, in this embodiment, a case is described in which the diameter of the defocus region 14 within the functional region 12 is uniform, but the diameter of the defocus region 14 may vary depending on the location in the functional region 12.

[0043] The radius r of the central clear area 11 is preferably 5.5 mm or more and 10 mm or less. Under these conditions, the central clear area 11 has an appropriate size, which makes it easier to obtain the effect of inhibiting the progression of myopia.

[0044] The pitch p of the defocus regions 14 is preferably 1.0 mm or more and 2.5 mm or less, and more preferably 1.2 mm or more and 2.0 mm or less. Under these conditions, it becomes easier to obtain the effect of inhibiting the progression of myopia, and it becomes easier to arrange the defocus regions 14 in a manner that makes it easier to measure macro power.

[0045] The difference (defocus power) between the refractive power of the defocus region 14 and the refractive power of the portion other than the defocus region 14 (for example, the base region 13) is preferably, for example, 0.5D or more and 10D or less in absolute value.

[0046] The defocus regions 14 may be arranged in areas other than the functional region 12, but from the viewpoint of improving the wearing comfort of the eyeglass lens 10, it is preferable that, for example, 80% or more (more preferably 90% or more) of all the defocus regions 14 provided on the eyeglass lens 10 be arranged in the functional region 12.

[0047] In the functional region 12, the area ratio of the defocus region 14 is preferably, for example, 30% or more and 60% or less (more preferably 40% or more and 60% or less). Under these conditions, it is easier to obtain the myopia progression suppression effect and to arrange the defocus region 14 in a manner that makes it easy to measure macro power. If the area ratio of the defocus region 14 is less than 30%, the myopia progression suppression effect may not be sufficiently obtained. In contrast, by setting the area ratio of the defocus region 14 to 30% or more, the myopia progression suppression effect may be sufficiently obtained. On the other hand, if the area ratio of the defocus region 14 exceeds 60%, there is a possibility that the wearing comfort and appearance of the eyeglass lens 10 may be adversely affected. In contrast, by setting the area ratio of the defocus region 14 to 60% or less, the wearing comfort and appearance of the eyeglass lens 10 can be maintained.

[0048] The peripheral clear area 15 is an annular area that realizes 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, because the peripheral clear area 15 is provided along the outer periphery of the spectacle lens 10 so as to surround the functional area 12, peripheral vision can be easily ensured.

[0049] Various commonly used lens substrates can be used as the lens substrate constituting the spectacle 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 the lens substrate, a plastic lens substrate is preferred from the viewpoint of being lightweight and shatter-resistant. Examples of plastic lens substrates include styrene resins such as (meth)acrylic resins, polycarbonate resins, allyl resins, allyl carbonate resins such as diethylene glycol bisallyl carbonate resin (CR-39), vinyl resins, polyester resins, polyether resins, urethane resins obtained by reacting an isocyanate compound with a hydroxy compound such as diethylene glycol, thiourethane resins obtained by reacting an isocyanate compound with a polythiol compound, and cured products (commonly referred to as 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 referred to as a polymerizable composition. The lens substrate may be undyed (colorless lenses) or dyed (dyed lenses). The thickness of the lens substrate is not particularly limited, but may be, for example, approximately 1 to 30 mm (center thickness). The refractive index of the lens substrate may be, for example, approximately 1.60 to 1.75. However, the refractive index of the lens substrate is not limited to this range, and may be within this range or may deviate above or below this range. In this specification, the refractive index refers to the refractive index for light with a wavelength of 500 nm.

[0050] (2) Method for Measuring Macro Power Next, a method for measuring the macro power, which is the mean spherical power in a predetermined light beam range (light beam diameter φ) within the functional area 12, for the eyeglass lens 10 of this embodiment will be described. The method for measuring the macro power of this embodiment includes, for example, a point P confirmation step S100 for confirming an inscription indicating a certain point P within the functional area 12, and a local power measurement step S200 for measuring local power within a range of diameter φ centered on point P. Then, the average of the local powers measured in the local power measurement step S200 is calculated as the macro power.

[0051] In the point P confirmation step S100, for example, the mark 20A indicating the point P is confirmed. Furthermore, in the point P confirmation step S100, it is preferable to further confirm the mark 20B indicating the beam diameter φ. This determines the beam range when measuring the macro power.

[0052] In the local power measurement step S200, for example, a known power distribution measuring device is used to measure the local power within a range of diameter φ centered on point P. At this time, as described above, in the eyeglass lens 10 of this embodiment, since the defocus region 14 does not exist in the outer periphery of the light beam when measuring the macro power, it is possible to use the average of the local powers as the macro power.

[0053] <Other embodiments of the present invention> Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit of the present invention.

[0054] For example, in the above embodiment, a case has been described in which the marking 20A is present at a position indicating the point P, but the form of the marking 20A is not limited to this. For example, the marking 20A indicating the coordinates of the point P may be formed at an arbitrary position on the spectacle lens 10, thereby identifying the point P.

[0055] Furthermore, for example, in the above-described embodiment, the case where the marking 20B indicating the beam diameter φ is provided has been described, but in cases where a standard has been established and the value of the beam diameter φ has been predetermined, the marking 20B may be omitted. Also, the value of the beam diameter φ may be displayed on the lens bag or the like of the eyeglass lens 10. In this case, in the point P confirmation step S100, checking the marking 20B may be omitted, and the beam diameter φ displayed on the lens bag or the like may be checked.

[0056] For example, in the above embodiment, the case where the defocus region 14 of the spectacle lens 10 is convex and has the effect of suppressing the progression of myopia has been described, but the present invention can also be applied to spectacle lenses that have the effect of suppressing the progression of myopia and have a concave defocus region 14. The present invention can also be applied to spectacle lenses that have the effect of reducing hyperopia, which provide a stimulus to the retina different from that of the naked eye or a single-focus lens by changing the defocus and contrast characteristics.

[0057] Furthermore, for example, the present invention can be applied to all similar eyeglass lenses that provide a stimulus to the retina different from that of the naked eye or single-vision lenses by changing defocus and contrast characteristics. For example, the present invention can be applied to eyeglass lenses that provide a stronger defocus stimulus to improve retinal blood flow and are expected to improve glaucoma.

[0058] In the above embodiment, the central clear area 11 and the base area 13 function as a single-focus lens, but the spectacle lens 10 may be a progressive power lens having a progressive surface. According to the present invention, even in this case, the macro power can be easily measured regardless of the arrangement of the defocus area 14.

[0059] Furthermore, for example, in the above-described embodiment, the case where the defocus region 14 has a spherical shape has been described, but the surface shape of the defocus region 14 is not limited to this. For example, the defocus region 14 may have an aspherical shape or a rough surface.

[0060] In the above embodiment, the macro power and local power are the mean spherical power in the corresponding area, but the astigmatic power or cylinder power in the corresponding area can also be used. Furthermore, if the evaluation light beam range is an ellipse, the present invention may be applied after performing an affine transformation so that it becomes a perfect circle with the same area.

[0061] Next, examples of the present invention will be described. These examples are merely examples of the present invention, and the present invention is not limited to these examples.

[0062] In this example, a myopia progression inhibiting lens (Sample 1) was designed as shown in Figure 4. The design conditions for Sample 1 were as follows: Lens substrate: PC (polycarbonate) Refractive index of lens substrate: 1.589 Prescription refractive power (spherical refractive power): 0.0D Prescription refractive power (astigmatic refractive power): 0.0D Shape of defocus area: spherical (circular in plan view) Surface on which defocus area is formed: object-side surface Height of defocus area: 1 µm Defocus power: +4D Diameter of defocus area: 0.9 mm Pitch of defocus area: 1.5 mm

[0063] In addition, a cross mark (stamp 20A) indicating point P was formed at the coordinates (x, y) = (0, 10) (unit: mm) in a plan view, with the lens center (eye point) of Sample 1 as the origin. Furthermore, a numerical value (stamp 20B) indicating a beam diameter φ = 4.0 mm when measuring macro dioptric power was formed near the stamp 20A.

[0064] 5 , it was confirmed that seven defocus regions exist within a virtual circle C having a diameter of φ and centered at point P, and that no defocus regions exist on virtual circle C. It was also confirmed that no defocus regions exist on the circumference of a circle having a diameter of 3.90 mm and centered at point P, and on the circumference of a circle having a diameter of 4.28 mm and centered at point P. In other words, it was confirmed that no defocus regions exist within the annular region from virtual circle C1 having a diameter of 0.98φ and centered at point P to virtual circle C2 having a diameter of 1.05φ.

[0065] Then, the local power was measured within a range of diameter φ centered on point P, and the average of the local power was calculated to be 0.00D, which was confirmed to be consistent with the designed macro power of 0.0D.

[0066] From the above, it was confirmed that the eyeglass lens of this embodiment is capable of correctly evaluating macro power even when the average of local powers is used, and is an eyeglass lens in which macro power can be easily measured.

[0067] 10: eyeglass lens; 11: central clear area; 12: functional area; 13: base area; 14: defocus area; 15: peripheral clear area; 20A, 20B: marking; S100: point P confirmation step; S200: local power measurement step

Claims

1. A spectacle lens comprising: a central clear area that realizes the wearer's prescribed refractive power and includes the eye point; and a functional area that is arranged to surround the central clear area, wherein the functional area has a base area that realizes the prescribed refractive power and a plurality of defocus areas having refractive powers different from the prescribed refractive power, wherein φ is a predetermined diameter of 4 mm or more and 6 mm or less, wherein, in a planar view, at least one of the defocus areas exists within an imaginary circle C of diameter φ centered on a certain point P within the functional area, and wherein no defocus area exists on the imaginary circle C, and wherein the spectacle lens has an inscription indicating the point P.

2. The eyeglass lens according to claim 1, wherein, in a plan view, the defocus area does not exist within an annular area extending from an imaginary circle C1 having a diameter of 0.98φ or less and centered on the point P to an imaginary circle C2 having a diameter of 1.02φ or more.

3. The eyeglass lens according to claim 1, further having an engraving indicating the value of φ.

4. The eyeglass lens according to claim 1, wherein the marking indicating the point P is located within the defocus area.

5. A method for measuring macro power, which is the mean spherical power in a predetermined light flux range within the functional area, in a spectacle lens having a central clear area that realizes the wearer's prescribed refractive power and includes the eye point, and a functional area that is arranged to surround the central clear area, wherein the functional area has a base area that realizes the prescribed refractive power and a plurality of defocus areas that have a refractive power different from the prescribed refractive power, the method comprising the steps of: (a) checking an engraving that indicates a point P within the functional area; and (b) measuring local power within a range of diameter φ centered on point P, where φ is a predetermined diameter that is between 4 mm and 6 mm, and the average of the local powers is taken as the macro power.

6. The method for measuring refractive power according to claim 5, wherein step (a) further comprises checking an inscription indicating the value of φ.

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