Spectacle lens, spectacle lens group and design method of spectacle lens

Abstract

A spectacle lens (10) having a plurality of segmented regions (11) for causing a light beam incident from an object-side surface to be emitted from an eye-side surface and to be focused at a position different from a position on the retina of an eyeball of a spectacle wearer, the plurality of segmented regions (11) are configured so as to achieve a vision value equal to or less than a predetermined limit vision value, and the area ratio occupied by non-segmented regions other than the segmented regions is 0-25% with respect to a region in which the plurality of segmented regions and the non-segmented regions are combined.

Description

Technical Field

[0001] The present disclosure relates to spectacle lenses, spectacle lens groups, and a method for designing spectacle lenses. Background Art

[0002] In the case of treating monocular amblyopia, when treating amblyopia, the optic nerve of the amblyopic eye can be developed (trained) by covering the healthy non-amblyopic eye or reducing vision. Specifically, known methods include: a complete occlusion method using an eye patch to completely cover the healthy eye, or a method of reducing vision using a substance called a Bangerter filter or Bangerter occlusion foil with fine concavities and convexities (for example, refer to Patent Documents 1 and 2).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-254040

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2022-068287 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] In the treatment of amblyopia, especially for child patients, early detection and treatment are crucial, and it is desirable to minimize the burden on the patient. However, the above methods for treating amblyopia have the following drawbacks. For example, the method of completely covering the healthy eye with an eye patch may cause discomfort to the patient after wearing the eye patch for a long time, affect daily life, and even hinder the development of stereoscopic vision that can only be achieved by using both eyes. In addition, the method of reducing the vision of the healthy eye using a Bangerter filter or the like uses a wearing device similar in appearance to white frosted glass to reduce vision, which results in poor aesthetics when worn and causes the patient to be resistant to using the wearing device.

[0009] Regarding vision reduction, for example, this problem can be solved by using a single-focus lens with a different correction power (prescription power) from that of the wearer, but this method may disrupt the balance of convergence accommodation, thus bringing the risk of strabismus or amblyopia. At the same time, due to the inconsistent size of the left and right eyes in appearance, the aesthetics are also impaired.

[0010] One aspect of the present disclosure provides a technique related to spectacle lenses suitable for treating monocular amblyopia.

[0011] Means for Solving the Problems

[0012] The first aspect of the present disclosure is:

[0013] An eyeglass lens, the eyeglass lens having a plurality of segmented regions that cause light beams incident from an object-side surface to exit from an eye-side surface and be focused at positions different from positions on the retina of the eye of the eyeglass wearer,

[0014] The plurality of segmented regions are configured to achieve a visual acuity value below a predetermined restricted visual acuity value,

[0015] With respect to the region formed by combining the plurality of segmented regions and non-segmented regions other than the segmented regions, the area ratio occupied by the non-segmented regions is 0% or more and 25% or less.

[0016] A second aspect of the present disclosure is:

[0017] The eyeglass lens according to the first aspect, wherein, within a region of a second predetermined diameter D2 assumed at any position within a range of a first predetermined diameter D1 including at least the lens center, the area ratio satisfies 0% or more and 25% or less.

[0018] A third aspect of the present disclosure is:

[0019] The eyeglass lens according to the second aspect, wherein, within the entire lens region, the area ratio satisfies 0% or more and 25% or less.

[0020] A fourth aspect of the present disclosure is:

[0021] The eyeglass lens according to the first aspect, wherein the plurality of segmented regions are configured to have periodicity.

[0022] A fifth aspect of the present disclosure is:

[0023] The eyeglass lens according to the fourth aspect, wherein the plurality of segmented regions are configured such that the center of each segmented region is located at the vertex of a triangle constituting a triangular lattice;

[0024] The planar size d of the lens when the segmented region exists alone is in the range of 0.25 mm or more and 2.0 mm or less,

[0025] The arrangement interval p between adjacent segmented regions among the plurality of segmented regions is in the range of 0.25 mm or more and 2.0 mm or less,

[0026] The planar size d and the arrangement interval p satisfy the relationship 0.866 < p / d < 1.1.

[0027] A sixth aspect of the present disclosure is:

[0028] The eyeglass lens according to the fourth aspect or the fifth aspect, wherein adjacent segmented regions are configured to be in contact with each other.

[0029] The seventh aspect of the present disclosure is:

[0030] The spectacle lens according to the first aspect, wherein the segmented region has a convex portion that focuses the light beam at a position closer to the object side than the retina.

[0031] The eighth aspect of the present disclosure is:

[0032] The spectacle lens according to the first aspect, wherein the segmented region has a concave portion that focuses the light beam at a position farther from the object side than the retina.

[0033] The ninth aspect of the present disclosure is:

[0034] The spectacle lens according to the seventh aspect or the eighth aspect, wherein the non-segmented region is formed into a curved surface shape that focuses the light beam at a position on the opposite side of the segmented region with the retina as the center.

[0035] The tenth aspect of the present disclosure is:

[0036] The spectacle lens according to the first aspect, wherein the spectacle lens has an optical film covering the plurality of segmented regions.

[0037] The eleventh aspect of the present disclosure is:

[0038] A set of spectacle lenses, the set of spectacle lenses being composed of a left-eye lens and a right-eye lens,

[0039] One of the left-eye lens and the right-eye lens is an occlusion function lens composed of the spectacle lens according to the first aspect;

[0040] The other of the left-eye lens and the right-eye lens is a non-occlusion function lens having an optical surface that causes the light beam incident from the object-side surface to exit from the eyeball-side surface and focus on the retina of the eyeball of the spectacle wearer.

[0041] The twelfth aspect of the present disclosure is:

[0042] The set of spectacle lenses according to the eleventh aspect, wherein the plurality of segmented regions in the occlusion function lens are arranged along a virtual curved surface corresponding to the optical surface in the non-occlusion function lens.

[0043] The thirteenth aspect of the present disclosure is:

[0044] A design method for spectacle lenses, the design method comprising the following steps: For an optical surface of one of an object-side surface and an eyeball-side surface, the optical surface is designed to have a plurality of segmented regions, and the plurality of segmented regions cause light beams incident from the object-side surface to exit from the eye-side surface and be focused at positions different from the positions on the retina of the eyeball of the spectacle wearer.

[0045] In the step of designing the optical surface, the spectacle lenses are designed to:

[0046] The plurality of segmented regions are arranged along a virtual curved surface corresponding to the optical surface that causes light beams incident from the object-side surface to exit from the eyeball-side surface and be focused on the retina of the eyeball of the spectacle wearer;

[0047] The plurality of segmented regions are configured to achieve a visual acuity value below a predetermined limit visual acuity value.

[0048] With respect to the region formed by combining the plurality of segmented regions and the non-segmented regions other than the segmented regions, the area ratio occupied by the non-segmented regions is 0% or more and 25% or less.

[0049] Advantages of the Invention

[0050] One aspect of the present disclosure is applicable to the treatment of monocular amblyopia. Description of the Drawings

[0051] Figure 1 is a perspective view showing a schematic configuration example of a spectacle lens group according to an embodiment of the present invention.

[0052] Figure 2 is an explanatory diagram showing a planar configuration example of a spectacle lens in an embodiment of the present disclosure.

[0053] Figure 3 is an explanatory diagram showing a cross-sectional configuration example of a spectacle lens in an embodiment of the present disclosure.

[0054] Figure 4 is an explanatory diagram showing a configuration example of the segmented regions of a spectacle lens in an embodiment of the present invention.

[0055] Figure 5 is an explanatory diagram showing another configuration example of the segmented regions of a spectacle lens in an embodiment of the present disclosure.

[0056] Figure 6 is an explanatory diagram showing a cross-sectional configuration example of the non-segmented regions of a spectacle lens in an embodiment of the present disclosure.

[0057] Figure 7It is an explanatory diagram (the first one) showing a specific example of the optical characteristics of a spectacle lens in an embodiment of the present disclosure.

[0058] Figure 8 It is an explanatory diagram (the second one) showing a specific example of the optical characteristics of a spectacle lens in an embodiment of the present disclosure.

[0059] Figure 9 It is an explanatory diagram (the third one) showing a specific example of the optical characteristics of a spectacle lens in an embodiment of the present disclosure.

[0060] Figure 10 It is an explanatory diagram (the fourth one) showing a specific example of the optical characteristics of a spectacle lens in an embodiment of the present disclosure.

[0061] Figure 11 An explanatory diagram showing a specific example of the design process of the segmented area of a spectacle lens in an embodiment of the present disclosure. Detailed implementation mode

[0062] Hereinafter, an embodiment of the present disclosure will be described with reference to the accompanying drawings. It should be noted that the following description is only an example, and the present invention is not limited to the illustrated embodiment.

[0063] (1) Constitution of spectacle lens

[0064] First, a spectacle lens group according to an embodiment of the present disclosure will be described.

[0065] Figure 1 It is a perspective view showing a schematic configuration example of the spectacle lens group.

[0066] The spectacle lens group in the illustrated example is composed of a left-eye lens 10L and a right-eye lens 10R. The pair of lenses 10L and 10R are mounted on a spectacle frame 2 for a patient who needs to treat monocular amblyopia. That is, the left-eye lens 10L and the right-eye lens 10R are mounted on the spectacle frame 2 to form a monocular amblyopia treatment lens 1 (hereinafter also simply referred to as "treatment glasses"). The wearer of the treatment lens 1 is a patient who needs to treat monocular amblyopia.

[0067] One of the left-eye lens 10L and the right-eye lens 10R is an occlusion function lens disposed in front of the healthy eye of the patient. Since the configuration of the occlusion function lens corresponds to the healthy eye, it is also referred to as the "healthy-eye lens" hereinafter. The other of the left-eye lens 10L and the right-eye lens 10R is a non-occlusion function lens disposed in front of the amblyopic eye of the patient. Since the configuration of the non-occlusion function lens corresponds to the amblyopic eye, it is also referred to as the "amblyopic-eye lens" hereinafter. Thus, the configurations of the occlusion function lens and the non-occlusion function lens are determined according to which eye of the patient's left and right eyes has amblyopia.

[0068] Both the left-eye lens 10L and the right-eye lens 10R have an object-side surface and an eyeball-side surface. The "object-side surface" is the surface located on the object side when the patient, as the wearer, wears the therapeutic glasses 1. The "eyeball-side surface" is the opposite surface, that is, the surface located on the eyeball side when the patient, as the wearer, wears the therapeutic lens 1. Moreover, both the left-eye lens 10L and the right-eye lens 10R are configured such that when the patient wears the therapeutic lens 1, the light beam incident from the object-side surface is emitted from the eyeball-side surface toward the eyeball of the patient as the wearer.

[0069] However, the non-occlusion function lens (amblyopic glasses lens) is designed to focus the light beam incident on the eyeball onto the retina of that eyeball. That is, the non-occlusion function lens is configured to have an optical surface that focuses the light beam onto the retina of the eyeball. Therefore, the non-occlusion function lens is configured to achieve the prescribed prescription power for the wearer, thereby focusing the light beam on the retina of the wearer's eyeball.

[0070] In contrast, the occlusion function lens (healthy-eye lens) is designed to focus the light beam incident on the eyeball at a position other than the retina of the eyeball. Therefore, the occlusion function lens is configured to have a power different from the prescribed prescription power for the wearer, so as to focus the light beam at a position other than the retina of the wearer's eyeball. It should be noted that the specific configuration for focusing the light beam at a position other than the retina will be described in detail later.

[0071] Due to the structural differences between each of the lenses 10L, 10R, the patient, as the wearer of the therapeutic lens 1, will experience a decrease in the visual acuity of the healthy eye through the occlusion function lens. This makes it possible to stimulate and develop (train) the optic nerve of the amblyopic eye, and it is expected to obtain a therapeutic effect for monocular amblyopia.

[0072] (2) Configuration of the spectacle lens

[0073] Next, the spectacle lens according to an embodiment of the present disclosure will be described. The spectacle lens described here corresponds to the occlusion function lens (healthy-eye lens) in the above spectacle lens group.

[0074] Figure 2 It is an explanatory diagram showing an example of a planar configuration of spectacle lenses. Figure 3 It is an explanatory diagram showing an example of a cross-sectional configuration of spectacle lenses.

[0075] It should be noted that in these figures, since the occlusion functional lens can be used as the left-eye lens 10L or the right-eye lens 10R, the reference numeral is simply abbreviated as the spectacle lens 10.

[0076] As Figure 2 shown, the spectacle lens 10 used as the occlusion functional lens is configured to have a plurality of segmented regions 11. The segmented regions 11 are provided to cause the light beam incident on the object-side surface of the spectacle lens 10 to exit from the eyeball-side surface and focus the light beam at a position other than the retina of the eyeball of the spectacle wearer (i.e., a patient with monocular amblyopia). In other words, the segmented region 11 is a region that realizes a diopter different from the prescription diopter of the spectacle wearer in order to focus the light beam at a position different from the retina.

[0077] Specifically, as Figure 3 shown, each segmented region 11 has a convex portion 12 formed on the object-side surface of the spectacle lens 10. The convex portion 12 has a curved surface that protrudes convexly toward the object side and is configured to focus the light beam passing through the spectacle lens 10 at a position closer to the object side than the focus on the retina. Thus, by causing the segmented region 11 having the convex portion 12 to focus the light beam at a position closer to the object side than the retina, it is expected to obtain a therapeutic effect on monocular amblyopia by reducing the visual acuity when viewing through the spectacle lens 10.

[0078] However, each segmented region 11 is not limited to having the convex portion 12. Each segmented region 11 may have, for example, a concave portion having a curved surface that bends in the opposite direction to the convex portion 12 (i.e., a concave portion that focuses the light beam at a position farther from the object side than the retina), as long as the segmented region 11 focuses the light beam passing through the spectacle lens 10 at a position other than the retina. Even in this case, it is expected to reduce the visual acuity through the spectacle lens 10 and obtain a therapeutic effect on monocular amblyopia.

[0079] It is known that by focusing the light beam at a position closer to the object side than the retina using the segmented region 11 having the convex portion 12, an effect of suppressing the progression of myopia, i.e., the myopia progression suppression effect, can be obtained. In addition, it is also known that by using the segmented region 11 having a concave shape to focus the light beam at a position farther from the object side than the retina, in the case where the glasses wearer is hyperopic, a hyperopia improvement effect of improving the hyperopia degree can be obtained. Referring to these findings, depending on the refractive error degree of the wearer's amblyopic eye, it is possible to determine whether to use the convex portion 12 or the concave portion in the segmented region 11, or whether to use a mixture of both. For example, the convex portion 12 can be used for myopic people, and the concave portion can be used for hyperopic people.

[0080] It should be noted that in the following description, an example is given in which each segmented region 11 is configured to have the convex portion 12. However, even in the case of being configured to have a concave portion, as for the shielding effect of the shielding functional lens (lens for healthy eye), in addition to the optical action caused by the light beam focusing position, the optical actions obtained in either case are basically the same.

[0081] As Figure 3 shown, the convex portions 12 constituting each segmented region 11 are arranged along a prescribed virtual surface 13. The virtual surface 13 corresponds to the optical surface of the non-shielding functional lens (lens for amblyopic eye) paired with the spectacle lens 10 used as the shielding functional lens. More specifically, the virtual surface 13 is the optical surface on the object side of the non-shielding functional lens, which can be a virtual surface having the same curvature as the optical surface for focusing light on the retina of the eyeball or a curvature difference small enough to be considered the same. Therefore, for example, if the non-shielding functional lens (amblyopia spectacle lens) is a single-focus lens, the virtual surface 13 can correspond to a spherical surface according to the prescription degree of the single-focus lens. If the convex portions 12 are arranged along such a virtual surface 13, when the shielding functional lens and the non-shielding functional lens are used in pair (set), their respective magnifications, etc. will be the same, thereby avoiding the risk of binocular visual acuity decline due to inconsistent visual acuity between the left and right eyes. At the same time, when others observe the wearer externally, there will also be no situation where there are differences in appearance such as the size of the left and right eyes.

[0082] Due to the arrangement of the convex portions 12 constituting each segmented region 11, the spectacle lens 10 used as the shielding functional lens does not focus the light beam on the retina of the eyeball like the non-shielding functional lens used in pair (set), which results in a decline in visual acuity compared to the case of the non-shielding functional lens. In other words, due to the existence of each segmented region 11, the visual acuity value achieved by the spectacle lens 10 is lower than that of the non-shielding functional lens used in pair (set).

[0083] The visual acuity value achieved by the spectacle lens 10 is intended to reduce the visual acuity to an extent where a therapeutic effect for monocular amblyopia can be obtained. Specifically, it is intended to achieve a visual acuity value below a predetermined restricted visual acuity value that is preset to be sufficient to obtain a masking effect for the treatment of monocular amblyopia, and it is intended to achieve a visual acuity value below a predetermined restricted visual acuity value that is preset to be sufficient to achieve the occlusion efficacy for the treatment of monocular amblyopia. The predetermined restricted visual acuity value can be, for example, 0.3 or less, or can be 0.1 or less, in order to obtain a more reliable masking effect. Therefore, in the spectacle lens 10, each segmented region 11 is configured to be able to achieve a visual acuity value of, for example, 0.3 or less, preferably 0.1 or less.

[0084] Each segmented region 11 is set with its own planar dimension d, arrangement interval p, and refractive power to achieve a visual acuity value below the predetermined restricted visual acuity value.

[0085] The planar dimension d of the segmented region 11 is a representative value of the size (dimension) of the region surrounded by the boundary line of the intersection line between the curved surface constituting the segmented region 11 (hereinafter referred to as the "segmented curved surface") and the lens curved surface serving as the base when the segmented region 11 is arranged (for example, the virtual curved surface 13, hereinafter also referred to as the "base lens curved surface") as viewed from the plane when the segmented region 11 exists alone. For example, if the boundary line is circular, any one of the maximum value, average value, median value, etc. of the diameter of the circle corresponds to the planar dimension d. When the interval between adjacent segmented regions 11 is large enough, that is, when the segmented regions 11 are arranged at a certain distance from each other, the actual segmented region 11 is the region surrounded by the boundary line of the intersection line between the segmented curved surface and the base lens curved surface, but when the interval between two adjacent segmented regions 11 is small and the two adjacent segmented regions 11 partially overlap, the intersection line of the two segmented curved surfaces becomes the boundary line. That is, the segmented region 11 is the region surrounded by the intersection line of the segmented curved surface of the segmented region 11 and the segmented curved surfaces of all adjacent segmented regions 11 or the intersection line with the base lens curved surface. When two adjacent segmented regions 11 have even one common boundary line, these two segmented regions 11 are said to be "in contact" with each other.

[0086] In this embodiment, the planar dimension d of the segmented region 11 is set in the range of, for example, 0.25 mm or more and 2.0 mm or less, preferably in the range of 0.25 mm or more and 1.3 mm or less. If the planar dimension d is 0.25 mm or more, the difficulty of forming fine irregularities is reduced compared to the case where the planar dimension d is less than 0.25 mm, so it is preferable. In addition, if the planar dimension d is 2.0 mm or less, preferably 1.3 mm or less, irregularities of such a size are difficult to detect, and it is possible to prevent damage to the aesthetics of the spectacle lens 10, so it is preferable.

[0087] The arrangement interval p of the segmented area 11 is the distance value between the reference points in adjacent segmented areas 11 when observing each segmented area 11 on the plan view (for example, if the segmented area 11 exists alone, it is the center point of the planar shape or the vertex of the convex shape, etc.).

[0088] In this embodiment, the lower limit value of the arrangement interval p of the segmented area 11 is set to be, for example, 0.25 mm or more, preferably 1.0 mm or more. If the arrangement interval p is 0.25 mm or more, the scattered reflection caused by external illumination can be suppressed, and the spectacle lens 10 will not show white flickering in the eyes of others. In addition, by making the arrangement interval p as large as 1.0 mm or more, the risk that the spectacle wearer experiences flickering (appearing like a screen door) due to the false resolution caused by the diffraction effect of the arrangement periodicity is reduced. The upper limit value of the arrangement interval p of the segmented area 11 is set according to, for example, the pupil diameter of the human eye, and is set to be 2.0 mm or less, approximately half of the average pupil diameter. By making the arrangement interval p as small as 2.0 mm or less, local prisms can be suppressed and the eye convergence is not affected.

[0089] In addition, the planar dimension d and the arrangement interval p of the segmented area 11 can be determined according to the ratio of the area of the segmented area 11 to the area of the non-segmented area (which will be described in detail later) that is the area other than the segmented area 11. When achieving the visual acuity reduction effect, it is necessary to reduce the area of the non-segmented area. For example, if the center of the segmented area 11 having a circular planar shape is arranged at the vertex of the triangle forming a triangular lattice, it is desirable to set the planar dimension d and the arrangement interval p to satisfy the relationship 0.866 < p / d < 1.1. When p < 0.866d, the non-segmented area existing between the segmented areas 11 completely disappears, so there is no need to make p / d < 0.866. On the other hand, when p / d > 1.1, the non-segmented area becomes large, and there is a risk that the visual acuity reduction, which is the objective of this technology, cannot be achieved. In this way, when the segmented area 11 is arranged at the vertex of the triangle forming a triangular lattice, while satisfying the above constraints (conditions) regarding the planar dimension d and the arrangement interval p, the maximum visual acuity reduction effect can be obtained. In addition, the segmented area 11 may not be arranged at the vertex of the triangle forming a triangular lattice, but may be arranged in other patterns. In this case, different constraint conditions can be set for p / d to maximize the required visual acuity reduction effect.

[0090] The refractive power of the segmented area 11 refers to the defocus degree caused by the convex portion 12 of the segmented area 11. The defocus degree is not simply the "degree", but the deviation in units of D (diopter) between the case where the segmented area 11 exists and the case where it does not exist (that is, the case where only the virtual surface 13 exists). In other words, the defocus degree is equivalent to the degree difference of the segmented area 11 relative to the virtual surface 13.

[0091] In this embodiment, the refractive power (defocus degree) of the segmented region 11 is appropriately set so that the spectacle lens 10 attains a visual acuity value below the limit visual acuity value. If the planar dimension d and the arrangement interval p satisfy the above-mentioned limit (condition), the visual acuity value can be adjusted by adjusting the defocus degree without excessively increasing or decreasing the risk. Specifically, if the visual acuity value is equal to or less than the limit visual acuity value of 0.3, it can be achieved by setting the defocus degree to, for example, 3.51 D. Further, if the visual acuity value is equal to or less than the limit visual acuity value of 0.1, it can be achieved by setting the defocus degree to, for example, 5.80 D. More generally, if the absolute value of the difference between the maximum value and the minimum value of the sagittal height within the same segmented region 11 is multiplied by the value obtained by subtracting 1 from the e-line refractive index of the material constituting the segmented region 11 and is 265 nm or more (more preferably 530 nm or more), the element will function as an element that blocks high spatial frequency components in a wide range.

[0092] The curved surface shape of the convex portion 12 of each segmented region 11 having such a refractive power is not particularly limited, but may be configured, for example, as a spherical shape (spherical lens). In this case, when light beams pass through the spectacle lens 10, excessive scattering is less likely to occur, which is preferable. Further, for example, the convex portion 12 may also be constituted by an aspherical shape (aspherical lens) in which the power near the periphery is higher than that near the vertex (center) of the convex portion 12. At this time, since the peripheral portion causes a decrease in visual acuity, it is preferable in achieving a visual acuity value lower than the restricted visual acuity value.

[0093] In addition, each segmented region 11 has the planar dimension d, the arrangement interval p, and the refractive power set as described above, and the area ratio of the segmented region 11 is set as follows. When the spectacle lens 10 is viewed from a plan view, a plurality of segmented regions 11 and a non-segmented region as a region other than the segmented region 11 may exist over the entire range of the lens. The area ratio of the segmented region 11 here refers to the area ratio of the non-segmented region with respect to the area of the region composed of the combination of each segmented region 11 and the non-segmented region.

[0094] In this embodiment, the area ratio of the non-segmented region is set to 0% or more and 25% or less, preferably 12% or less. When the area ratio of the non-segmented region is 0%, it means that there is no non-segmented region and the region is only covered by the segmented regions 11.

[0095] Preferably, such an area ratio of the non-segmented region is satisfied over the entire lens region of the spectacle lens 10. However, this is not restrictive. For example, as Figure 1As shown, even if the vicinity of the periphery of the spectacle lens 10 does not meet the requirements, it is sufficient to meet at least a part of the following regions. The "part of the region" mentioned here refers to the region where the line of sight of the spectacle wearer may frequently pass through. More specifically, the part of the region is a region within the range of the second predetermined diameter D2, and the second predetermined diameter D2 is assumed to be at an arbitrary position within the range of the first predetermined diameter D1 including the lens center (geometric center or optical center). The first predetermined diameter D1 is, for example, φ30 mm or more and φ50 mm or less, preferably φ40 mm ± 5 mm. The second predetermined diameter D2 is, for example, φ2.5 mm or more and φ5.0 mm or less, preferably about 4.0 mm of the average pupil diameter. In other words, it is at least necessary to meet the above area ratio in the region of the second predetermined diameter D2, and in the region of the second predetermined diameter D2, the second predetermined diameter D2 approximates the average pupil diameter assumed at an arbitrary position within the range of the first predetermined diameter D1 where the line of sight frequently passes through.

[0096] By satisfying the above respective constraints (conditions), each segmented region 11 is configured to have periodicity. The periodicity referred to here means that the segmented regions 11 are arranged repeatedly according to a certain rule. Therefore, even if the segmented regions 11 are not necessarily arranged at equal intervals, as long as their arrangement has a certain regularity, it is considered to be configured to have periodicity. In the arrangement of the plurality of segmented regions 11, for example, even if they are sparsely arranged at a specific position, if there is a certain regularity, it is considered to have periodicity.

[0097] In addition, each segmented region 11 is configured such that adjacent segmented regions 11 are in contact with each other. For example, when the area ratio of the non-segmented region is 0%, the segmented regions 11 are configured such that their entire peripheries are in contact with other segmented regions 11. However, it is not necessary for the entire periphery to be in contact with other segmented regions 11, as long as each segmented region 11 is configured such that at least a part of it is in contact with other segmented regions 11.

[0098] Figure 4 It is an explanatory diagram showing an example of the arrangement of the segmented regions 11. In the illustrated example, a case where the entire peripheries of the respective segmented regions 11 are in contact with other segmented regions 11 and the area ratio of the non-segmented region is 0% is shown.

[0099] In this configuration example, the centers of the respective segmented regions 11 are located at the vertices of the triangles that make up the triangular lattice. As a result, the respective segmented regions 11 are in a honeycomb (staggered) positional relationship. Also, the respective segmented regions 11 are arranged such that their respective peripheries overlap each other and are in a superimposed positional relationship. Therefore, according to this configuration example, the respective segmented regions 11 can be configured most efficiently within a limited range, and the planar shape of each segmented region 11 becomes a polygon (specifically, for example, a hexagon) defined by the boundaries of their respective segmented surfaces.

[0100] Figure 5 FIG. is an explanatory diagram showing another example of another configuration of the segmented region 11. In the illustrated example, the planar shape of each segmented region 11 is circular, a part of its outer periphery contacts other segmented regions 11, and the area ratio of the non-segmented region is greater than 0%.

[0101] In this configuration example, the centers of the respective segmented regions 11 are also located at the vertices of the triangles that make up the triangular lattice, and the respective segmented regions 11 are in a honeycomb (staggered) positional relationship. However, in this example arrangement, the respective segmented regions 11 do not overlap, and a part of the outer periphery of the segmented region 11 contacts other segmented regions 11, such that there is a non-segmented region 14 between the respective segmented regions 11. However, the area ratio of the non-segmented region 14 is set to 25% or less.

[0102] It should be noted that Figure 4 and Figure 5 the configuration examples shown are merely exemplary, and the configuration of each segmented region 11 is not limited to these examples.

[0103] When there is a non-segmented region 14 between the respective segmented regions 11, the non-segmented region 14 can be configured as follows.

[0104] Figure 6 FIG. is an explanatory diagram showing an example of the cross-sectional structure of the non-segmented region 14.

[0105] As shown in the illustrated example, when each segmented region 11 has a convex portion 12, the non-segmented region 14 can be formed into a curved surface shape that bends in the opposite direction to the convex portion 12 (i.e., concave) so that the adjacent convex portions 12 are connected to each other. In this case, the segmented region 11 focuses the light beam at a position closer to the object side than the retina, while the non-segmented region 14 focuses the light beam at a position farther from the object side than the retina. In other words, the non-segmented region 14 can be formed into a curved surface shape that focuses the light beam at a position on the opposite side of the segmented region 11 with the retina as the center.

[0106] It should be noted that in the above configuration, the boundary between the segmented area 11 and the non-segmented area 14 or the boundary between the segmented areas 11 can be regarded as the point where the direction of the surface shape (positive or negative sign when represented by defocus) changes. At this time, the defocus degree of the boundary part is "0", but since its area is an extremely narrow linear band, it is not necessary to regard this part as a single area, and this part does not affect the optical properties of the spectacle lens 10.

[0107] When each segmented area 11 has a convex part 12, it can be conceived that the convex part 12 can be formed by the lens substrate constituting the spectacle lens 10. This also applies to the shape of the non-segmented area 14.

[0108] The lens substrate is molded from a thermosetting resin material such as thiocarbamate, allyl, acrylic, and episulfide. It should be noted that as the resin material constituting the lens substrate, other resin materials that can provide the required refractive power can be selected. In addition, the lens substrate can also be formed of inorganic glass instead of the resin material. When using such a lens substrate, the convex part 12 and the like can be formed by a molding process using a mold.

[0109] The surface of the lens substrate can be coated with an optical film. Examples of the optical film include a hard coat film (HC film) and an anti-reflection film (AR film). In addition to these, other films can also be formed. These optical films can be produced by known techniques and will not be elaborated here.

[0110] When the optical film is coated, the optical film covers each segmented area 11. In this case, the optical film can be formed thinner so that its surface conforms to the surface shape of the lens substrate, or it can be formed thicker to fill and smooth the unevenness of the lens substrate surface shape.

[0111] In either case, the refractive index of the spectacle lens 10 composed of the lens substrate and the optical film for the light incident from the object side surface is preferably 1.55 or more, and preferably about 1.59.

[0112] (3) Optical properties of the spectacle lens

[0113] Next, the optical properties of the spectacle lens 10 configured as described above will be described.

[0114] Figure 7 is an explanatory diagram (the first one) showing a specific example of the optical properties of the spectacle lens 10. The illustrated example shows the relationship between the spatial frequency and the contrast of the light transmitted through the lens. The horizontal axis is the spatial frequency (CPD: cycles per degree), and the vertical axis is the contrast sensitivity.

[0115] In the figure, symbol A represents a specific example of the optical characteristics of the spectacle lens 10 having the above structure, where p = 1.0 mm and p / d = 1.0. Symbols B to E are comparative examples of the specific example of symbol A. Symbol B represents a specific example of the optical characteristics of a non-blocking function lens used in combination with the spectacle lens 10 having the above structure. Reference C represents a specific example of the optical characteristics of a material used as a Bangerter filter. Symbols D and E represent specific examples of the optical characteristics of spectacle lenses having a segmented region defined by convex portions but not satisfying the above limitations (conditions) (for example, the area ratio of the non-segmented region is approximately 30% to 70% or 40% to 60%).

[0116] As Figure 7 shown, for the spectacle lens 10 constructed as described above, in the range of CPD > 3, the contrast sensitivity is reduced (see symbol A). CPD = 3 corresponds to a visual acuity value of approximately 0.1. Therefore, it can be seen that in the spectacle lens 10, the visual acuity value is suppressed to a low level, thereby achieving a limiting visual acuity value of less than 0.1 that provides a reliable shielding effect. On the contrary, for spectacle lenses that do not satisfy the above limitations (conditions) (see symbols D and E), since the light beam passes through the non-segmented region, the contrast sensitivity in the range of CPD > 3 is not sufficiently reduced, and it cannot be considered that a limited visual acuity value of less than 0.1 is achieved. In other words, by satisfying the above limitations (conditions), as in the case of the spectacle lens 10 described in this embodiment, a visual acuity value of less than 0.1 as the limiting visual acuity value is achieved. In addition, if a Bangerter filter is used (see symbol C), a visual acuity value of less than 0.1 can be achieved, but a contrast sensitivity peak appears at a high spatial frequency (for example, CPD = 17), which is not preferable in terms of the risk of generating false resolution.

[0117] Figure 8 This is an explanatory diagram (the second one) showing a specific example of the optical characteristics of the spectacle lens 10. The illustrated example shows the relationship between the spatial frequency and the contrast of the light transmitted through the lens when the interval p of the segmented region 11 is 1.3 mm and the height at which the convex portion 12 protrudes from the virtual curved surface 13 is 1.2 μm, at p / d = 0.87, p / d = 1.0, p / d = 1.05, p / d = 1.2, and p / d = 1.4. The horizontal axis and the vertical axis are the same as those in Figure 7 the case of

[0118] In addition, Figure 9 This is an explanatory diagram (the third one) showing a specific example of the optical characteristics of the spectacle lens 10.

[0119] The illustrated example shows the relationship between the spatial frequency and the contrast of the light transmitted through the lens when the configuration interval p of the segmented region 11 is 1.3 mm and the height at which the convex portion 12 protrudes from the virtual curved surface 13 is 2.4 μm. The rest is the same as that inFigure 8 The same applies.

[0120] As Figure 8 and Figure 9 shown, when p / d = 0.87, p / d = 1.0, and p / d = 1.05, in all cases, the contrast sensitivity is reduced in the range of CPD > 3. In other words, it can be seen that the visual acuity value remains at a low level to achieve a limiting visual acuity value of 0.1 or less, thereby achieving a reliable shielding effect. Therefore, it can be considered that if the relationship between the planar dimension d of the spectacle lens 10 and the spacing p is set to satisfy 0.866 < p / d < 1.1, a visual acuity value of 0.1 or less as the limiting visual acuity value can be achieved.

[0121] It should be noted that in order to achieve a visual acuity value of 0.1 or less, it is preferable that the peak height of the contrast sensitivity that appears in the range of CPD > 3 is as low as possible, and the peak appears at a low CPD position. From this point of view, it can be considered that even if 0.866 < p / d < 1.1 is satisfied, it is most preferable that p / d = 1.0.

[0122] Figure 10 It is an explanatory diagram (the fourth one) showing a specific example of the optical characteristics of the spectacle lens 10. The illustrated example is the simulation result when observing the appearance of a person wearing the spectacle lens from a position 1 meter away in an indoor environment with a fluorescent lamp installed on the ceiling. (a) shows the case where the planar dimension d of the segmented area 11 is φ1.3 mm, (b) shows the case where the planar dimension d of the segmented area 11 is φ1.0 mm, (c) shows the case where the planar dimension d of the segmented area 11 is φ0.63 mm, (d) shows the case where the planar dimension d of the segmented area 11 is φ0.32 mm, (e) shows the case where the planar dimension d of the segmented area 11 is φ0.25 mm, and (f) shows the case where the planar dimension d of the segmented area 11 is φ0.15 mm. In any case, the height by which the convex portion 12 protrudes from the virtual surface 13 is 1.2 μm.

[0123] When observing a spectacle wearer from the outside in an indoor environment with a fluorescent lamp, on the surface of this spectacle lens, a composite image of the transmitted image of the wearer's eyes and the fluorescent reflection image can be seen. At this time, if the segmented size (segment diameter) on the spectacle lens is large, the transmitted image will show a mosaic effect, but if the segmented size is small, the mosaic effect will no longer be obvious and the overall image will look blurred. As the segmented size becomes smaller, the reflection image picks up a larger range of illumination light, and the reflected light becomes visible over the entire lens. Due to the combined effect of these factors, the smaller the segmented size, the cloudier and whiter the spectacle lens looks. For example, this is similar to the case of a Bangerter filter or frosted glass.

[0124] As Figure 10As shown in (f), when the planar dimension d of the segmented area 11 is φ0.15 mm, the spectacle lens 10 appears cloudy and white, and the eye contour of the wearer appears blurred. On the contrary, as Figure 10 (a) to Figure 10 (e) show, if the planar dimension d of the segmented area 11 is φ0.25 mm or more, the spectacle lens 10 will not become cloudy and white, and the eye contour of the wearer will be clearly visible. For these reasons, it can be considered that in order not to impair the aesthetics of the spectacle lens 10, the planar dimension d of the segmented area 11 is very preferably 0.25 mm or more.

[0125] On the other hand, as Figure 10 (a) shows, when the planar dimension d of the segmented area 11 is φ1.3 mm, an area presenting a mosaic effect starts to appear on a part of it. Therefore, the planar dimension d of the segmented area 11 can be in the range of 0.25 mm or more and 2.0 mm or less, but from the viewpoint of not impairing the aesthetics of the spectacle lens 10, it is more preferably 1.3 mm or less.

[0126] As described above, the spectacle lens 10 according to this embodiment not only obtains a vision reduction effect (blocking effect) of achieving a vision value below the limit vision value, but also does not impair the aesthetics when observed from the appearance in the state of wearing the spectacle lens 10. From this point of view, it is significantly different from a Bangert filter, frosted glass, etc. Therefore, the spectacle lens 10 according to this embodiment can eliminate the risk that amblyopia treatment patients are reluctant to wear glasses.

[0127] (4) Design method and manufacturing method of spectacle lens

[0128] Next, the design method and manufacturing method of the spectacle lens 10 having the above structure will be described.

[0129] The design of the spectacle lens 10 is based on the unobstructed function lens used in pair with the spectacle lens 10. That is, before designing the spectacle lens 10, first, the surface shape of the optical surface constituting the unobstructed function lens is specified according to, for example, the prescription power, etc.

[0130] Then, when designing the spectacle lens 10, a virtual surface 13 of the spectacle lens 10 is specified to correspond to the surface shape of the optical surface of the non-blocking function lens. Then, a plurality of segmented regions 11 are arranged along the specified virtual surface 13, thereby specifying the surface shape of the optical surface of the spectacle lens 10. For example, if each segmented region 11 is arranged in a honeycomb (staggered) shape on the optical surface, on the surface of the specified virtual surface 13, a virtual triangular mesh composed of equilateral triangles is stretched, the arrangement interval p of each segmented region 11 is the length of one side of the equilateral triangle, and the reference points (for example, the center point of the planar shape or the vertex of the convex shape, etc.) of each segmented region 11 are located at each vertex of the equilateral triangle in the triangular mesh, and the convex portions 12 constituting each segmented region 11 are arranged in this way. At this time, when the peripheries of the segmented regions 11 overlap each other, the position with the highest height from the virtual surface 13 including the surface of the virtual surface 13 is determined as the outermost surface of the optical surface. In this way, the convex portions 12 constituting each segmented region 11 are joined to each other to obtain the surface shape of the optical surface of the spectacle lens 10.

[0131] It should be noted that when arranging each segmented region 11, at least the planar dimension d and the arrangement interval p of each segmented region 11 are preset so that the planar dimension d is in the range of 0.25 mm or more and 2.0 mm or less, the arrangement interval p is in the range of 0.25 mm or more and 2.0 mm or less, and the planar dimension d and the arrangement interval p satisfy the relationship 0.866 < p / d < 1.1. As a result, after arranging each segmented region 11, with respect to the region composed of each segmented region 11 and the non-segmented region, the area ratio occupied by the non-segmented region is 0% or more and 25% or less. In other words, the segmented regions 11 are arranged so that the area ratio of the non-segmented region is 0% or more and 25% or less.

[0132] More specifically, if each segmented region 11 is composed of a convex portion 12, the arrangement of each segmented region 11 can be as follows.

[0133] Figure 11 It is an explanatory diagram showing a specific example of the design process of the segmented region.

[0134] As Figure 11 (a) shows, as a first step, segmented spheres (of course, aspheres are also possible) are discretely arranged on a plane. The plane at this time corresponds to the virtual surface 13. In the illustrated example, the case where curved surfaces with a diameter of 1.2 mm and a height of 0.18 mm are arranged at an interval of 1.3 mm is shown. It should be noted that in Figure 11 (a), the left figure is the case of the arrangement within a 2 mm square region, and the right figure is a cross-sectional view along the arrow direction. The solid line and the dashed line in the right figure correspond to the arrows in the left figure respectively.

[0135] Then, as shown in Figure 11 (b), as the second step, smoothing is performed using a smoothing filter. It should be noted that in Figure 11 (b), the left figure is the diameter of the smoothing filter, and the right figure is the cross-sectional view of the smoothing filter. In this example, a uniform filter is used. If the filter diameter is not set to be greater than the maximum inscribed radius of the non-segmented area, the surface of the virtual surface 13 will remain exposed. When the filter is configured in a honeycomb shape as described above, the relationship filter diameter > configured interval p × √3÷2 - planar dimension d holds. In this example, it is set to 0.3 mm.

[0136] Thereafter, since the segmentation height and the effective shielding effect change due to the smoothing process, as shown in Figure 11 (c), as the third step, while adjusting by scaling in the height direction, the shape and performance are checked, thereby completing the convex portions 12 in each segmented area 11 and the non-segmented area 14 therebetween.

[0137] It should be noted that when machining such a surface shape, it can be converted into spline data and added to the base curve of the virtual surface 13.

[0138] Through the above steps, the optical surface of the spectacle lens 10 of this embodiment can be designed.

[0139] In addition, after designing the optical surface, the spectacle lens 10 of this embodiment can be manufactured according to its design result. Specifically, for example, a mold reflecting the design result is made, and the lens substrate is made by performing molding processing using this mold. Then, an optical film coating process is performed on the lens substrate as needed, thereby obtaining the spectacle lens 10 of this embodiment.

[0140] It should be noted that regarding the design method or manufacturing method of the spectacle lens 10, specific details not described here can be implemented using well-known techniques.

[0141] When designing the spectacle lens 10, a surface similar to a Gaussian function can be arranged without going through the process of forming a discontinuous surface and then smoothing it as in the above example. This is equivalent to the process of smoothing the spherical segmented area 11 with a relatively small diameter (planar dimension d) with respect to the pitch (configured interval p) using a Gaussian filter with a large diameter.

[0142] In addition, when manufacturing the spectacle lens 10, if an optical film such as an HC film is applied thickly, the peripheral portion of the segmented area 11 may sag, thereby increasing the apparent planar size d. Therefore, taking this into account, correction can be made at the design stage of the spectacle lens 10 by subtracting the amount of expansion from the diameter of the smoothing filter. For example, when the thickness of the HC film is 2 μm, the planar size d can be expanded by approximately 0.05 mm. Therefore, if the filter diameter is set to 0.30 - 0.05 = 0.25 mm, an appropriate planar size d can be obtained according to the sag degree of the HC film.

[0143] (5) Effects of this embodiment

[0144] According to this embodiment, one or more of the following effects are achieved.

[0145] The spectacle lens 10 according to this embodiment has an effect of reducing vision (occlusion effect) below the limit vision value. Therefore, it is very suitable for the treatment of monocular amblyopia.

[0146] For the spectacle lens 10 according to this embodiment, even when an effect of reducing vision (occlusion effect) is obtained, different from the method of completely covering the healthy eye with an eye patch, the light passing through the lens is not completely blocked. Therefore, even when the lens is worn for a long time, it will not cause pain to the patient or pose a risk of affecting daily life, nor will it hinder the development of stereoscopic vision obtained by binocular viewing.

[0147] For the spectacle lens 10 according to this embodiment, the aesthetic appearance when the spectacle lens 10 is worn is not impaired. Therefore, different from the method of reducing the vision of the healthy eye using a Bangerter filter or the like, even when wearing glasses, an extremely natural appearance can be maintained, thereby eliminating the resistance of patients to wearing glasses during amblyopia treatment.

[0148] For the spectacle lens 10 according to this embodiment, by providing each segmented area 11, an effect of reducing vision (occlusion effect) is obtained, thereby reducing the risk of strabismus or amblyopia caused by the disruption of the convergence accommodation balance.

[0149] For the spectacle lens 10 according to this embodiment, each segmented area 11 is arranged along the virtual curved surface 13 corresponding to the optical surface of the non-occluding function lens. Therefore, even when the non-occluding function lens and the occluding function lens constituted by the spectacle lens 10 are used as a pair (set) of the left-eye lens 10L and the right-eye lens 10R, the magnification and the like of each lens are the same, and there will be no situation where, for example, the left and right eyes look different when observed from the appearance. In this regard, an extremely natural appearance can also be maintained, and the risk of patients undergoing amblyopia treatment being reluctant to wear glasses can be eliminated.

[0150] (6) Modification examples, etc.

[0151] Although embodiments of the present disclosure have been described above, the technical scope of the present invention is not limited to the above-described exemplary disclosure, and various modifications can be made without departing from the gist of the present disclosure.

[0152] In this embodiment, an example is given in which a convex portion is disposed on the object-side surface of the spectacle lens 10 to form a segmented region, but the present invention is not limited thereto. For example, a concave portion may be arranged instead of the convex portion to configure the segmented region. Further, the convex portion or the concave portion may be provided on the side surface of the spectacle lens 10 facing the eyeball instead of the side surface facing the object. Additionally, for example, a convex portion or a concave portion may also be formed inside the spectacle lens 10 (i.e., a portion other than the surface), and a segmented region may be formed by covering an optical surface having a thickness greater than a certain thickness. Further, a convex or concave portion may be formed on a film or a thin film, and the film or the thin film may be attached to the lens surface or sandwiched inside the lens.

[0153] In this embodiment, the case where the spectacle lens 10 is used for treating monocular amblyopia is taken as an example for illustration, but the present invention is not limited thereto and can also be used for other purposes.

[0154] Reference Signs

[0155] 1... Spectacles, 2... Spectacle Frame, 10... Spectacle Lens, 10L... Left-Eye Lens, 10R... Right-Eye Lens, 11... Segmented Region, 12... Convex Portion, 13... Virtual Curved Surface, 14... Non-Segmented Region.

Claims

1. An eyeglass lens, the eyeglass lens having a plurality of segmented regions that cause light beams incident from an object-side surface to exit from an eye-side surface and be focused at positions different from positions on the retina of the eye of the eyeglass wearer, the plurality of segmented regions being configured to achieve a visual acuity value below a predetermined restricted visual acuity value, with respect to a region formed by combining the plurality of segmented regions and a non-segmented region other than the segmented regions, the area ratio occupied by the non-segmented region is 0% or more and 25% or less.

2. The spectacle lens according to claim 1, wherein, Within a region of a second predetermined diameter D2 assumed at an arbitrary position within a range of a first predetermined diameter D1 that at least includes the lens center, the area ratio satisfies 0% or more and 25% or less.

3. The spectacle lens according to claim 2, wherein, Throughout the entire lens region, the area ratio satisfies 0% or more and 25% or less.

4. The spectacle lens according to claim 1, wherein, The plurality of segmented regions are configured to have periodicity.

5. The spectacle lens according to claim 4, wherein, The plurality of segmented regions are configured such that the center of each segmented region is located at the vertex of a triangle that forms a triangular lattice; the planar size d of the lens when the segmented regions exist individually is in the range of 0.25 mm or more and 2.0 mm or less, the arrangement interval p between adjacent segmented regions among the plurality of segmented regions is in the range of 0.25 mm or more and 2.0 mm or less, the planar size d and the arrangement interval p satisfy the relationship 0.866 < p / d < 1.

1.

6. The spectacle lens according to claim 4 or 5, wherein, Adjacent ones of the segmented regions are configured to be in contact with each other.

7. The spectacle lens according to claim 1, wherein The segmented region has a convex portion that focuses the light beam at a position closer to the object side than the retina.

8. The spectacle lens according to claim 1, wherein, The segmented region has a concave portion that focuses the light beam at a position farther from the object side than the retina.

9. The spectacle lens according to claim 7 or 8, wherein, The non-segmented region is formed in a curved surface shape that focuses the light beam at a position on the opposite side of the segmented region with the retina as the center.

10. The spectacle lens according to claim 1, wherein, The eyeglass lens has an optical film covering the plurality of segmented regions.

11. An eyeglass lens group, the eyeglass lens group being composed of a left-eye lens and a right-eye lens, one of the left-eye lens and the right-eye lens is an occlusion function lens constituted by the eyeglass lens according to claim 1; the other of the left-eye lens and the right-eye lens is a non-occlusion function lens having an optical surface that causes light beams incident from an object-side surface to exit from an eyeball-side surface and be focused on the retina of the eye of the eyeglass wearer.

12. The spectacle lens group according to claim 11, wherein, The plurality of segmented regions in the occlusion function lens are arranged along a virtual curved surface corresponding to the optical surface in the non-occlusion function lens.

13. A design method for spectacle lenses, the design method comprising the following steps: For an optical surface of one of the object-side surface and the eyeball-side surface, the optical surface is designed to have a plurality of segmented regions that cause light beams incident from the object-side surface to exit from the eye-side surface and be focused at positions different from positions on the retina of the eye of the eyeglass wearer, in the step of designing the optical surface, the eyeglass lens is designed to: arrange the plurality of segmented regions along a virtual curved surface that corresponds to the optical surface that causes light beams incident from the object-side surface to exit from the eyeball-side surface and be focused on the retina of the eye of the eyeglass wearer; Configure the multiple segmented areas to achieve a visual acuity value below a predetermined limited visual acuity value. With respect to the area composed of the multiple segmented areas and the non-segmented areas other than the segmented areas, the area ratio occupied by the non-segmented areas is 0% or more and 25% or less.

Images