Intraocular lens

Abstract

To provide an intraocular lens capable of appropriately providing a wearer with an excellent multifocal field of vision regardless of the size of the wearer's pupil.SOLUTION: A plurality of segmented areas include: a farsight area with smallest refractive power; a nearsight area with largest refractive power; and an intermediate area having a refractive power between the refractive power in the farsight area and the refractive power in the nearsight area. The plurality of segmented areas radially spread outward from a central part of the lens part. An MTF curve at a spacial frequency 50lp / mm has a farsight maximum value, nearsight maximum value, and intermediate maximum value. The intermediate maximum value is between the farsight maximum value and the nearsight maximum value. Each of the farsight maximum value, the nearsight maximum value, and the intermediate maximum value is 0.10 or more.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to intraocular lenses that are inserted into the eye. [Background technology]

[0002] As an intraocular lens inserted into the eye, a multifocal intraocular lens is known that distributes and focuses incident light to a lens portion at a plurality of focal points. The multifocal intraocular lens can provide the wearer with a pseudo-accommodative power. Multifocal intraocular lenses include refractive lenses in which a plurality of regions with different refractive powers are formed in the optical portion, and diffractive lenses that utilize the diffraction phenomenon of light. The refractive multifocal intraocular lens has the advantage that there is less loss of light reaching the wearer's retina than the diffractive multifocal intraocular lens.

[0003] For example, in the intraocular lens described in Patent Document 1, a plurality of optical zones with different refractive powers are formed concentrically in the lens portion, so that a near refractive power for obtaining near vision, a distance refractive power for obtaining distance vision, and a refractive power between the near refractive power and the distance refractive power are imparted.

[0004] In addition, in the multifocal intraocular lens described in Patent Document 2, the disk-shaped optical part is divided into a plurality of regions by boundaries extending from the periphery toward the geometric center. A group of minute prisms is formed in a different pattern in each divided region, thereby imparting a different refractive power to each region. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2010-82290 A [Patent Document 1] JP 2010-125292 A Summary of the Invention [Problem to be solved by the invention]

[0006] As described in Patent Document 1, in an intraocular lens in which a plurality of regions in the lens portion are arranged concentrically, when the wearer's pupil becomes small, light passes only through the region arranged near the center among the plurality of regions arranged concentrically. As a result, light does not pass through the region arranged in the peripheral portion, making it difficult to obtain the multifocal effect. Therefore, with the intraocular lens described in Patent Document 1, the wearer may not be able to obtain a good multifocal field. In addition, the multifocal intraocular lens described in Patent Document 2 aims to obtain the multifocal effect regardless of the size of the wearer's pupil by forming a plurality of regions with different refractive powers in the lens portion so as to be in contact with the optical axis. However, even in Patent Document 2, it is difficult to say that sufficient consideration has been given to providing the wearer with a good multifocal field. In other words, with conventional intraocular lenses, it has been difficult to appropriately provide the wearer with a good multifocal field regardless of the size of the wearer's pupil.

[0007] An exemplary object of the present disclosure is to provide an intraocular lens that is capable of providing good multifocal vision regardless of the size of the wearer's pupil. [Means for solving the problem]

[0008] A first aspect of an intraocular lens provided by a typical embodiment of the present disclosure is an intraocular lens having a disk-shaped lens portion, wherein three or more segmental regions having different refractive powers are formed on at least one of the front and rear surfaces of the lens portion, the segmental regions including a distance region having the smallest refractive power, a near region having the largest refractive power, and an intermediate region having a refractive power between the refractive power of the distance region and the refractive power of the near region, the segmental regions radially extend outward from a center of the lens portion, and an MTF curve at a spatial frequency of 50 lp / mm has an intermediate maximum value which is a maximum value in a range between a distance maximum value and a near maximum value, and each of the distance maximum value, the near maximum value, and the intermediate maximum value is 0.10 or more.

[0009] A second aspect of the intraocular lens provided by the exemplary embodiments in the present disclosure is an intraocular lens including a disc-shaped lens portion, wherein on at least one of the front surface and the rear surface of the lens portion, three or more segmented regions having different refractive powers from each other are formed, and the plurality of segmented regions include a distance vision region having the smallest refractive power, a near vision region having the largest refractive power, and an intermediate region having a refractive power between the refractive power of the distance vision region and the refractive power of the near vision region. The plurality of segmented regions radially extend outward from the central portion of the lens portion. When the refractive power of the near vision region is S and the refractive power of the intermediate region is M, both the conditions of S≧+2.75D and M<S≦(M + 1.4D) are satisfied.

[0010] According to the intraocular lens according to the present disclosure, regardless of the size of the wearer's pupil, it is easier to obtain a good visual field with multifocality.

Brief Description of the Drawings

[0011] [Figure 1] It is a plan view of the intraocular lens 1. [Diagram 2] It is a plan view showing an example of the intraocular lens 1 in which a plurality of segmented regions 20 are formed. [Diagram 3] It is a diagram schematically comparing cross-sectional views of a cross-section passing through the geometric center O of the lens portion 2 and perpendicular to the lens surface of the lens portion 2 for the distance vision region 20F and the near vision region 20N. [Figure 4] It is a diagram comparing the MTF curves of three intraocular lenses with different refractive powers for each of the distance vision region 20F, the near vision region 20N, and the intermediate region 20I.

Modes for Carrying Out the Invention

[0012] <Overview> A first embodiment of the intraocular lens in the present disclosure will be described. The intraocular lens exemplified in the present disclosure includes a disk-shaped lens portion. At least one of the front surface and the rear surface of the lens portion has three or more segmental regions having different refractive powers. The multiple segmental regions include a distance region having the smallest refractive power, a near region having the largest refractive power, and an intermediate region having a refractive power between the refractive power of the distance region and the refractive power of the near region. The multiple segmental regions spread radially outward from the center of the lens portion. The MTF curve of the intraocular lens of the present disclosure at a spatial frequency of 50 lp / mm has a distance maximum value, a near maximum value, and an intermediate maximum value. The distance maximum value is a maximum value in a range that provides a wearer with a distant field of vision. The near maximum value is a maximum value in a range that provides a wearer with a near field of vision. The intermediate maximum value is a maximum value in a range between the distance maximum value and the near maximum value. The distance maximum, near maximum, and intermediate maximum are each 0.10 or greater.

[0013] In the intraocular lens exemplified in the present disclosure, a plurality of segmental regions with different refractive powers spread radially outward from the center of the lens portion. Therefore, unlike an intraocular lens in which a plurality of regions are arranged concentrically, even if the wearer's pupil becomes small, light can easily pass through all of the plurality of segmental regions. Furthermore, the MTF curve of the intraocular lens of the present disclosure at a spatial frequency of 50 lp / mm has an intermediate maximum value in addition to a distance maximum value and a near maximum value. The MTF values ​​of the distance maximum value, the near maximum value, and the intermediate maximum value are each 0.10 or more. Therefore, according to the intraocular lens of the present disclosure, it is easy to obtain a good field of vision not only for distant objects but also for near objects and intermediate distances between them, regardless of the size of the pupil.

[0014] In the MTF curve at a spatial frequency of 50 lp / mm, the difference between the smaller MTF value of the near maximum value and the intermediate maximum value and the minimum value existing between the near maximum value and the intermediate maximum value may be 0.10 or less. In this case, the distance at which the visual field deteriorates is unlikely to be included between the near distance and the intermediate distance. In other words, it becomes easier to obtain a good visual field overall from the near distance to the intermediate distance. Therefore, regardless of the size of the pupil, it becomes easier to obtain a good visual field not only at far distances but also at near and intermediate distances.

[0015] In addition, in the MTF curve at a spatial frequency of 50 lp / mm, the difference between the smaller MTF value of the near maximum value and the intermediate maximum value and the minimum value existing between the near maximum value and the intermediate maximum value may be 0.08 or less. More preferably, the difference between the smaller MTF value of the near maximum value and the intermediate maximum value and the minimum value existing between the near maximum value and the intermediate maximum value may be 0.05 or less. In this case, the visual field from the near distance to the intermediate distance can be more easily obtained.

[0016] In the MTF curve, the near maximum may be greater than the intermediate maximum, which increases the contrast at the near distance where viewing is most frequently performed, making it easier to obtain a better field of vision.

[0017] However, it is possible to set the near maximum value equal to or lower than the intermediate maximum value, and still obtain good vision at far, near and intermediate distances, regardless of pupil size.

[0018] In the MTF curve at a spatial frequency of 50 lp / mm, the difference between the near maximum value and the intermediate maximum value may be 0.05 or less. In this case, it becomes easier to obtain a good field of view for both near and intermediate distances. Therefore, regardless of the size of the pupil, it becomes easier to obtain a good field of view not only for far distances but also for near and intermediate distances.

[0019] When the refractive power of the near vision area is S and the refractive power of the intermediate area is M, the conditions S ≧ +2.75 D and M < S ≦ (M + 1.4 D) may both be satisfied. That is, the difference between the refractive power S of the near vision area and the refractive power M of the intermediate area may be 1.4 D or less. As a result of repeated trial and error and simulations by the inventor of the present invention, by bringing the difference between the refractive power S of the near vision area and the refractive power M of the intermediate area closer to 1.4 D or less, in addition to the intermediate maximum value in the MTF curve increasing compared to the case where the difference is greater than 1.4 D, it has newly been found that a synergistic effect is obtained in that the MTF value increases overall from the intermediate distance to the near distance. Therefore, by designing the intraocular lens so as to satisfy the conditions S ≧ +2.75 D and M < S ≦ (M + 1.4 D), regardless of the pupil size, the visual fields at not only far distances but also near and intermediate distances can be more easily obtained in better condition.

[0020] Note that the intraocular lens may satisfy both the conditions S ≧ +2.75 D and M < S ≦ (M + 1.35 D). That is, the difference between the refractive power S of the near vision area and the refractive power M of the intermediate area may be 1.35 D or less. In this case, the effect of increasing the intermediate maximum value in the MTF curve and the effect of the MTF value increasing overall from the intermediate distance to the near distance are more easily obtained.

[0021] When the refractive power of the near vision area is S and the refractive power of the intermediate area is M, the conditions S ≧ +2.75 D and (M + 1.1 D) ≦ S ≦ (M + 1.4 D) may both be satisfied. As described above, a useful synergistic effect is obtained by bringing the difference between the refractive power S of the near vision area and the refractive power M of the intermediate area closer to 1.4 D or less. On the other hand, if the difference between the refractive power S of the near vision area and the refractive power M of the intermediate area is made too close, the effect of the multifocal intraocular lens for obtaining good visual fields at far, near, and intermediate distances decreases. Therefore, by designing the intraocular lens so as to satisfy both the conditions S ≧ +2.75 D and (M + 1.1 D) ≦ S ≦ (M + 1.4 D), regardless of the pupil size, the visual fields at not only far distances but also near and intermediate distances can be more easily obtained in better condition by the multifocal effect.

[0022] Incidentally, the difference between the refractive power S in the near vision region and the refractive power M in the intermediate region may be 1.15 D or more. In this case, not only distant vision but also near and intermediate distance visual fields are more likely to be obtained better due to the multifocal effect.

[0023] Incidentally, regardless of whether the above-described MTF value conditions are satisfied or not, it is also possible to design the intraocular lens so as to satisfy the conditions of S ≧ +2.75 D and M < S ≦ (M + 1.4 D). Even in this case, by designing the intraocular lens so as to satisfy the conditions of S ≧ +2.75 D and M < S ≦ (M + 1.4 D), regardless of the pupil size, not only distant vision but also near and intermediate distance visual fields are more likely to be obtained better.

[0024] The plurality of segmented regions may have different refractive powers due to different radii of curvature. In this case, compared with the case where a micro prism group or the like is formed in the segmented region, the amount of light scattered in an unintended direction is reduced. As a result, light loss reaching the retina is less likely to occur, and a better visual field is more likely to be obtained. Also, it is easy to process with high precision, and the possibility of breakage during insertion into the eye is low.

[0025] Incidentally, the lens surface of each segmented region may be spherical or aspherical. Also, the refractive power is substantially constant within each segmented region. That is, when a transition portion described later is provided on the lens surface, the refractive power changes within the region at the transition portion, whereas the refractive power is substantially constant within the segmented region.

[0026] The plurality of segmented regions may spread radially outward from one reference point at the center of the lens portion. That is, among each of the segmented regions, the linear end portions extending outward from the center of the lens portion may all pass through the same reference point. In this case, even when the wearer's pupil becomes small, the amount of light passing through each of the plurality of segmented regions is more likely to be ensured compared to the case where a certain region (for example, a circular region etc.) is separately formed at the center of the lens portion. As a result, regardless of the size of the wearer's pupil, the multifocal effect is more likely to be obtained, so the wearer's visual field is more likely to be good.

[0027] A transitional section may be formed between the plurality of segmented regions in the lens section. The transitional section may smoothly connect the ends of the pair of segmented regions by continuously changing the radius of curvature from the end of one segmented region of a pair of adjacent segmented regions to the end of the other segmented region. If no transitional section is formed in the lens section, a step or the like may be formed at the boundary between the pair of adjacent segmented regions, and the step or the like may cause a phenomenon in which light is diffusely reflected by the step or the like and the field of view is deteriorated (e.g., a halo or glare). In contrast, by forming a transitional section between a pair of adjacent segmented regions, the effect of diffuse reflection of light due to the step or the like is less likely to occur. Furthermore, when a transitional section is formed in the lens section, the refractive power of each region in the transitional section smoothly transitions from the refractive power of one adjacent segmented region to the refractive power of the other segmented region. As a result, in addition to the refractive power of each segmented region, the lens section is also given a refractive power between the refractive powers of the segmented regions. Therefore, by forming a transition portion in the lens portion, the effect of the expanded depth of focus (EDOF) of the multifocal intraocular lens can be appropriately obtained.

[0028] Both the segmental region and the transitional portion may refract light that enters the lens portion parallel to the optical axis of the lens portion in a direction approaching the optical axis. In this case, the amount of light that passes through the lens portion and is lost without reaching the retina is reduced. Therefore, a better field of vision is more easily obtained. It is also possible to manufacture an intraocular lens without forming a transitional portion in the lens portion. Even in this case, a better field of vision is more easily obtained than when a group of microprisms or the like is formed in the segmental region.

[0029] The central angle of the transition portion that spreads outward from the center of the lens portion may be 5 degrees or more and 30 degrees or less. In this case, it becomes easier to appropriately obtain both the multifocal effect due to the multiple segmented regions and the focal depth extension effect.

[0030] The central angle of the transition portion may be 15 degrees or more and 20 degrees or less. In this case, the multifocal effect by the multiple segmented regions and the focal depth extension effect can be more appropriately obtained.

[0031] The central angles of the distance region, near region, and intermediate region, which extend outward from the center of the lens portion, may be the largest in the distance region and the smallest in the intermediate region. In this case, it becomes easier to appropriately obtain both distance vision by the distance region and near vision by the near region with an expanded depth of focus.

[0032] The central angle of the distance region may be 140 degrees or more, the central angle of the near region may be 90 degrees or more, and the central angle of the intermediate region may be 30 degrees or more. In this case, it becomes easier to appropriately obtain far vision by the distance region and near vision by the near region with both of the focal depths expanded.

[0033] <Embodiment> A typical embodiment of the present disclosure will be described below with reference to the drawings. An intraocular lens 1 of this embodiment is inserted into a patient's eye by an intraocular lens insertion instrument (not shown). In the following description, the side of the intraocular lens 1 that is inserted first into the eye by the intraocular lens insertion instrument (the left side in FIG. 1) is referred to as the front of the intraocular lens 1.

[0034] (Schematic configuration of intraocular lens) With reference to FIG. 1, a schematic configuration of an intraocular lens 1 in this embodiment will be described. The intraocular lens 1 includes a lens portion 2 and a support portion 3. The intraocular lens 1 in this embodiment is a so-called one-piece type intraocular lens in which the lens portion 2 and the support portion 3 are integrally molded. However, at least a part of the technology exemplified in this disclosure can also be applied to a so-called three-piece type intraocular lens in which the lens portion 2 and the support portion 3 are formed of separate members. The intraocular lens 1 can be deformed. As the material of the intraocular lens 1, various soft materials can be used, such as simple substances such as BA (butyl acrylate) and HEMA (hydroxyethyl methacrylate), and composite materials of acrylic acid ester and methacrylic acid ester.

[0035] The lens portion 2 provides a predetermined refractive power to the eye of a wearer wearing the intraocular lens 1 (i.e., the patient's eye). The refractive power provided to the lens portion 2 will be described in detail later. The lens portion 2 is disc-shaped. The optical axis of the lens portion 2 illustrated in this embodiment passes through the geometric center O of the lens portion 2 and extends in a direction perpendicular to the lens surface of the lens portion 2 (up and down direction). However, the optical axis of the lens portion 2 does not have to coincide with the geometric center O of the lens portion.

[0036] The intraocular lens 1 of this embodiment includes a pair of support parts 3 (a front support part 3A and a rear support part 3B). The base ends 4 of the pair of support parts 3 (i.e., the base end part 4A of the front support part 3A and the base end part 4B of the rear support part 3B) are connected to different parts of the side surface of the outer periphery of the lens part 2 (in this embodiment, each of the diametrically opposite parts of the outer periphery of the disk-shaped lens part 2). When the intraocular lens 1 is worn in the patient's eye, the pair of support parts 3 support the lens part 2 in the patient's eye.

[0037] (Lens segment area) 2 and 3, the segment regions 20 formed in the lens portion 2 of the intraocular lens 1 of this embodiment will be described. As shown in Fig. 2, in the intraocular lens 1 of this embodiment, three or more segment regions 20 (20F, 20N, 20I) are formed on at least one of the front surface and the rear surface of the disk-shaped lens portion 2.

[0038] The multiple segmental regions 20 have different refractive powers. In detail, the lens unit 2 of this embodiment is formed with a distance region 20F, a near region 20N, and an intermediate region 20I. The distance region 20F has the smallest refractive power among the multiple segmental regions 20. The near region 20N has the largest refractive power among the multiple segmental regions 20. The intermediate region 20I has a refractive power between the refractive power of the distance region 20F and the refractive power of the near region 20N. Therefore, the light passing through the distance region 20F, the near region 20N, and the intermediate region 20I in the lens unit 2 is focused on the wearer's retina, thereby obtaining a multifocal effect. In addition, in the present disclosure, each segmental region 20 is an area having approximately the same refractive power regardless of the part within the area.

[0039] When the lens portion 2 is viewed from a direction perpendicular to the lens surface, the multiple segmented regions 20 spread radially outward from the center of the lens portion 2. That is, each segmented region 20 is segmented by a boundary line that extends linearly from one point in the center of the lens portion 2 outward. Therefore, unlike an intraocular lens in which multiple regions are arranged concentrically, even if the wearer's pupil becomes small, light can easily pass through all of the multiple segmented regions 20. As a result, the multifocal effect can be easily obtained regardless of the size of the wearer's pupil. The boundary line of the segmented region 20 is not limited to a straight line, and may be a curve, or may be bent.

[0040] In detail, in the intraocular lens 1 of this embodiment, the lens portion 2 radially spreads outward from one reference point (in this embodiment, the geometric center O of the lens portion 2). That is, in each of the segmented regions 20, the linear boundary lines (ends) extending outward from the center of the lens portion 2 all pass through the same reference point. Therefore, even if the pupil of the wearer becomes small, the amount of light passing through each of the segmented regions 20 is more easily ensured than when a certain region (e.g., a circular region, etc.) is separately formed in the center of the lens portion 2. As a result, the multifocal effect is more easily obtained regardless of the size of the wearer's pupil, and the field of vision of the wearer is more easily improved. However, it is also possible to provide a certain region in the center of the lens portion 2. Even in this case, the multifocal effect is more easily obtained regardless of the size of the wearer's pupil than when a plurality of regions are arranged concentrically.

[0041] 3 is a schematic comparison of cross-sectional views of a cross section passing through the geometric center O of the lens portion 2 and perpendicular to the lens surface of the lens portion 2 for the distance region 20F and the near region 20N. As shown in FIG. 3, the multiple segment regions 20 formed in the intraocular lens 1 of this embodiment have different radii of curvature, and thus have different refractive powers. The lens surface of each segment region 20 may be spherical or aspheric. When the lens surface is aspheric, the term "radius of curvature" in the present disclosure may be interpreted as the radius of curvature of a sphere approximating the aspheric lens surface.

[0042] In the example shown in FIG. 3, the radius of curvature of the distance region 20F, which has a small refractive power, is larger than the radius of curvature of the near region 20N, which has a large refractive power. In other words, the curve of the lens surface of the distance region 20F, which has a small refractive power, is gentler than the curve of the lens surface of the near region 20N, which has a large refractive power. By changing the radius of curvature of each of the multiple segmented regions 20 to change the refractive power of each segmented region 20, the amount of light scattered in unintended directions is reduced compared to the case where the refractive power is changed by forming different microprism groups or the like in each segmented region 20. As a result, the loss of light reaching the retina is less likely to occur, making it easier to obtain a better field of view. In addition, the intraocular lens 1 of this embodiment is easy to process with high precision, and is less likely to be damaged when inserted into the eye.

[0043] 3, no step or the like is provided at the geometric center O of the lens portion 2. Therefore, the thickness of the side surface (edge ​​portion) of the lens portion 2 at the portion with the greater refractive power (portion with a steeper curve of the lens surface) is smaller than the thickness of the side surface of the lens portion 2 at the portion with the smaller refractive power (portion with a gentler curve of the lens surface).

[0044] 2, when the lens portion 2 is viewed in a direction perpendicular to the lens surface, transition portions 21 (21A, 21B, 21C) are formed between a plurality of segment regions 20 in the lens portion 2. Each transition portion 21 smoothly connects the ends of the pair of segment regions 20 by continuously changing the radius of curvature from the end of one segment region 20 of a pair of adjacent segment regions 20 through the transition portion 21 to the end of the other segment region 20.

[0045] In the example shown in FIG. 2, the refractive power of the far region 20F is 0D, the refractive power of the near region 20N is +3.25D, and the refractive power of the intermediate region 20I is +2.0D. Therefore, in the transitional portion 21A formed between the far region 20F and the near region 20N, the refractive power changes smoothly from 0D to +3.25D as it approaches the end of the near region 20N side from the end of the far region 20F side. In the transitional portion 21B formed between the near region 20N and the intermediate region 20I, the refractive power changes smoothly from +3.25D to +2.0D as it approaches the end of the intermediate region 20I side from the end of the near region 20N side. In the transitional portion 21C formed between the intermediate region 20I and the far region 20F, the refractive power changes smoothly from +2.0D to 0D as it approaches the end of the far region 20F side from the end of the intermediate region 20I side.

[0046] If the transition portion 21 is not formed in the lens portion 2, a step or the like may occur at the boundary between a pair of adjacent segment regions 20, and the step or the like may cause a phenomenon in which light is diffusely reflected and the field of view is deteriorated (for example, a halo or glare). In contrast, by forming the transition portion 21 between a pair of adjacent segment regions 20, the effect of diffuse reflection of light due to the step or the like is less likely to occur. Furthermore, if the transition portion 21 is formed in the lens portion 2, the refractive power of each region in the transition portion 21 smoothly transitions from the refractive power of one adjacent segment region 20 to the refractive power of the other segment region 20. As a result, in addition to the refractive power of each segment region 20, the lens portion 2 is also given a refractive power between the refractive powers of the segment regions 20. Therefore, by forming the transition portion 21 in the lens portion 2, the effect of the expanded depth of focus (EDOF) of the multifocal intraocular lens can be appropriately obtained.

[0047] In the intraocular lens 1 of this embodiment, both the segmental region 20 and the transitional region 21 refract the light that enters the lens portion 2 parallel to the optical axis of the lens portion 2 in a direction approaching the optical axis. As a result, the amount of light that passes through the lens portion 2 and is lost without reaching the retina is reduced. Therefore, a better field of vision is easily obtained.

[0048] The central angle of each transition portion 21 that spreads outward from the center of the lens portion 2 (in this embodiment, the geometric center O, which is the reference point) is designed to be 5 degrees or more and 30 degrees or less. In this case, it is easier to appropriately obtain both the multifocal effect of the multiple segment regions 20 and the focal depth extension effect. It is more preferable that the central angle of each transition portion 21 is designed to be 15 degrees or more and 20 degrees or less. As an example, the central angles of the three transition portions 21 formed in the intraocular lens 1 illustrated in FIG. 2 are all designed to be 20 degrees. However, it goes without saying that when multiple transition portions 21 are formed in the lens portion 2, the central angles of each transition portion 21 do not have to be the same.

[0049] The central angles of the distance region 20F, the near region 20N, and the intermediate region 20I, which spread outward from the center of the lens portion 2, are designed so that the central angle CF of the distance region 20F is the largest and the central angle CI of the intermediate region 20I is the smallest. In this case, it becomes easier to appropriately obtain both distance vision by the distance region 20F and near vision by the near region 20N with an expanded depth of focus.

[0050] In detail, the central angle CF of the distance region 20F is designed to be 140 degrees or more, the central angle CN of the near region 20N is designed to be 90 degrees or more, and the central angle CI of the intermediate region 20I is designed to be 30 degrees or more. In this case, it becomes easier to appropriately obtain far vision by the distance region 20F and near vision by the near region 20N with both of the focal depths expanded. As an example, in the intraocular lens 1 illustrated in FIG. 5, the central angle CF of the distance region 20F is designed to be 150 degrees, the central angle CN of the near region 20N is designed to be 100 degrees, and the central angle CI of the intermediate region 20I is designed to be 50 degrees.

[0051] It is also possible to form a toric surface that corrects the astigmatism of the wearer on at least one of the front and rear surfaces of the lens part 2. In this case, an intraocular lens 1 that can obtain both far vision and near vision and can also correct the astigmatism of the wearer is provided. The plurality of segmental regions 20 may be formed on the front surface of the lens surface (i.e., the surface that faces the front side (cornea side) of the eye when worn in the eye of the wearer). In this case, the shape of the rear surface of the lens surface is likely to be smooth, so that it is easy to prevent cells and the like from entering between the rear surface of the lens surface and the posterior capsule of the eye and causing secondary cataracts. In addition, the plurality of segmental regions 20 and the toric surface may be formed on the front surface of the lens surface. In this case, even when a toric surface is formed on the lens surface, it is easy to prevent the occurrence of secondary cataracts. However, it is also possible to form at least one of the segmental regions 20 and the toric surface on the rear surface of the lens surface. The surface on which the segmental regions 20 are formed and the surface on which the toric surface is formed may be different.

[0052] The MTF characteristic of the intraocular lens 1 of this embodiment will be described with reference to Fig. 4. MTF (Modulation Transfer Function) is an index indicating contrast. The graph of Fig. 4 shows an MTF curve at a spatial frequency of 50 lp / mm, with the horizontal axis representing the defocus amount (amount of focal deviation, deviation in power) and the vertical axis representing the MTF. Note that in this embodiment, as shown in Fig. 4, the MTF curve is shown when the analysis direction of the intensity of light passed through the lens portion 2 of the intraocular lens 1 to obtain the MTF is set to a direction parallel to a straight line X that divides the central angle of the distance region 20F in half.

[0053] In the three intraocular lenses 1 of A, B, and C whose MTF curves are shown in FIG. 4, the central angles of the distance region 20F, the near region 20N, and the intermediate region 20I are made the same, and only the refractive power of each region is changed. In detail, in the intraocular lens 1 of A, the central angle of the distance region 20F is 170 degrees, the refractive power is 0D, the central angle of the near region 20N is 120 degrees, the refractive power is +3.50D, and the central angle of the intermediate region 20I is 70 degrees, and the refractive power is +2.00D. As will be described later in detail, the intraocular lens 1 of A is shown only as a comparative example. In the intraocular lens 1 of B, the central angle of the distance region 20F is 170 degrees, the refractive power is 0D, the central angle of the near region 20N is 120 degrees, the refractive power is +3.25D, and the central angle of the intermediate region 20I is 70 degrees, and the refractive power is +2.00D. In the intraocular lens 1 of C, the central angle of the distance region 20F is 170 degrees and the refractive power is 0D, the central angle of the near region 20N is 120 degrees and the refractive power is +3.00D, and the central angle of the intermediate region 20I is 70 degrees and the refractive power is +2.0D. In the three intraocular lenses 1 of A, B, and C whose MTF curves are shown in Figure 4, a transitional section with a central angle of 20 degrees is actually provided between each region. Therefore, in the three intraocular lenses 1 of A, B, and C, excluding the angles of the transitional sections, the central angle of the distance region 20F is 150 degrees, the central angle of the near region 20N is 100 degrees, and the central angle of the intermediate region 20I is 50 degrees.

[0054] In the intraocular lenses 1 of B and C, the refractive power of each region is designed so that three maximum values ​​(distance maximum value, near maximum value, and intermediate maximum value) with MTF values ​​of 0.10 or more appear on the MTF curve at a spatial frequency of 50 lp / mm. The distance maximum value is a maximum value in a range of defocus amounts (in this embodiment, a range of defocus amounts from -1.0D to 1.0D) that provides the wearer with a distant visual field. The near maximum value is a maximum value in a range of defocus amounts (in this embodiment, a range in which the defocus amount is more negative than the distance maximum value). The intermediate maximum value is a maximum value in a range of defocus amounts between the distance maximum value and the near maximum value. Note that the MTF curve illustrated in FIG. 4 is an MTF curve based on the cornea, and the more negative the visual field provided to the wearer becomes, the closer it becomes to the near field. However, in the MTF curve based on the surface of the intraocular lens 1, the more positive the value, the closer the distance of the visual field provided to the wearer becomes.

[0055] As described above, in the intraocular lens 1 of this embodiment, a plurality of segmental regions (distance region 20F, near region 20N, and intermediate region 20I) with different refractive powers spread radially from the center of the lens portion toward the outside. Therefore, unlike an intraocular lens in which a plurality of regions are arranged concentrically, even if the wearer's pupil becomes small, light can easily pass through all of the plurality of segmental regions. Furthermore, as in the intraocular lenses 1 exemplified by B and C, which are designed to have three maximum values ​​(distance maximum value, near maximum value, and intermediate maximum value) with an MTF value of 0.10 or more, a good visual field can be easily obtained not only for far distances and near distances, but also for intermediate distances between the far distance and near distance, unlike the intraocular lens A of the comparative example. In other words, according to the intraocular lenses 1 exemplified by B and C, a good visual field can be easily obtained not only for far distances but also for near distances and intermediate distances between them, regardless of the size of the pupil.

[0056] As shown in Fig. 4, the intraocular lenses 1 of B and C are designed so that the difference between the smaller MTF value of the near maximum value and the intermediate maximum value and the minimum value between the near maximum value and the intermediate maximum value is 0.10 or less in the MTF curve at a spatial frequency of 50 lp / mm. In detail, in the intraocular lens of B, the difference between the MTF value (about 0.21) of the smaller of the near maximum value and the intermediate maximum value (the intermediate maximum value in the intraocular lens 1 of B) and the minimum value (about 0.18) between the near maximum value and the intermediate maximum value is about 0.03 (≦0.10). In the case of intraocular lens C, the difference between the MTF value (about 0.21) of the smaller of the near maximum value and the intermediate maximum value (near maximum value in intraocular lens C 1) and the minimum value (about 0.15) between the near maximum value and the intermediate maximum value is about 0.06 (≦0.10). In these cases, it is difficult for a distance at which the visual field deteriorates to be included between the near distance and the intermediate distance. In other words, it becomes easier to obtain a good visual field overall from the near distance to the intermediate distance. Therefore, regardless of the size of the pupil, it becomes easier to obtain a good visual field not only for distant objects but also for near and intermediate distances.

[0057] In detail, the intraocular lenses 1 of B and C are designed so that the difference between the smaller MTF value of the near maximum value and the intermediate maximum value and the minimum value between the near maximum value and the intermediate maximum value in the MTF curve at a spatial frequency of 50 lp / mm is 0.08 or less. In this case, it becomes easier to obtain a better field of vision from near to intermediate distances.

[0058] More specifically, the intraocular lens 1 of B is designed so that the difference between the smaller MTF value of the near maximum value and the intermediate maximum value and the minimum value between the near maximum value and the intermediate maximum value in the MTF curve at a spatial frequency of 50 lp / mm is 0.05 or less. In this case, it becomes easier to obtain a better field of vision from near to intermediate distances.

[0059] As shown in Figure 4, in the intraocular lens 1 of B, the refractive power of each region is designed so that the near maximum value is greater than the intermediate maximum value in the MTF curve at a spatial frequency of 50 lp / mm. By satisfying the condition that the near maximum value is greater than the intermediate maximum value, the contrast at the near distance where viewing is frequently performed is increased. As a result, a better visual field is easily obtained.

[0060] As shown in FIG. 4, in the intraocular lenses 1 of B and C, the refractive power of each region is designed so that the difference between the near maximum value and the intermediate maximum value is 0.05 or less in the MTF curve at a spatial frequency of 50 lp / mm. In detail, in the intraocular lens 1 of B, the difference between the near maximum value and the intermediate maximum value is about 0.02 (≦0.05). In the intraocular lens 1 of C, the difference between the near maximum value and the intermediate maximum value is about 0.03 (≦0.05). In these cases, a good field of vision is easily obtained for both near and intermediate distances. Therefore, regardless of the size of the pupil, a good field of vision is easily obtained not only for distant objects but also for near and intermediate distances.

[0061] As a result of repeated trial and error and simulations, the inventors of the present invention have newly discovered that by bringing the difference between the refractive power S of the near region 20N and the refractive power M of the intermediate region 20I closer to 1.4D or less, compared to when the difference is made larger than 1.4D, not only does it increase the intermediate maximum value in the MTF curve, but it also has a synergistic effect of increasing the MTF value overall from intermediate to near distances.

[0062] Actually, as shown in FIG. 4, in the intraocular lens of Comparative Example A, the difference between the refractive power S in the near vision region 20N and the refractive power M in the intermediate region 20I is 1.4D (>1.5D). In the intraocular lens of A, the MTF value at the intermediate distance is insufficient, and the MTF value from the intermediate distance to the near distance is also insufficient as a whole. On the other hand, in the intraocular lenses 1 of B and C, the difference between the refractive power S in the near vision region 20N and the refractive power M in the intermediate region 20I is smaller than 1.4D. Specifically, in the intraocular lens 1 of B, the difference between the refractive power S in the near vision region 20N and the refractive power M in the intermediate region 20I is 1.25D (≦1.4D). In the intraocular lens 1 of C, the difference between the refractive power S in the near vision region 20N and the refractive power M in the intermediate region 20I is 1.00D (≦1.4D). It can be seen that in the intraocular lenses 1 of B and C, in addition to the increase in the intermediate maximum value in the MTF curve compared to the intraocular lens of A, a synergistic effect that the MTF value increases as a whole from the intermediate distance to the near distance occurs. In other words, in the intraocular lenses 1 of B and C, when the refractive power in the near vision region is S and the refractive power in the intermediate region is M, by satisfying both the conditions of S≧+2.75D and M<S≦(M + 1.4D), regardless of the pupil size, it is easier to obtain good vision not only at a far distance but also at near and intermediate distances.

[0063] Note that, like the intraocular lenses 1 of B and C, the conditions of S≧+2.75D and M<S≦(M + 1.35D) may both be satisfied. That is, the difference between the refractive power S in the near vision region and the refractive power M in the intermediate region may be 1.35D or less. In this case, the effect of increasing the intermediate maximum value in the MTF curve and the effect of increasing the MTF value as a whole from the intermediate distance to the near distance are more likely to be obtained.

[0064] In addition, in the intraocular lens 1 of B, when the refractive power of the near vision region is S and the refractive power of the intermediate region is M, the conditions of S ≧ +2.75 D and (M + 1.1 D) ≦ S ≦ (M + 1.4 D) are both satisfied. As described above, a useful synergistic effect can be obtained by making the difference between the refractive power S of the near vision region and the refractive power M of the intermediate region approach 1.4 D or less. On the other hand, if the difference between the refractive power S of the near vision region and the refractive power M of the intermediate region is made too close, the effect of the multifocal intraocular lens for obtaining good visual fields at far, near, and intermediate distances will decrease. Therefore, by designing the intraocular lens 1 so that the conditions of S ≧ +2.75 D and (M + 1.1 D) ≦ S ≦ (M + 1.4 D) are both satisfied, regardless of the pupil size, visual fields at not only far but also near and intermediate distances can be more easily obtained better due to the multifocal effect. As described above, the value of "1.4 D" in the above conditions may be "1.35 D".

[0065] Note that the difference between the refractive power S of the near vision region and the refractive power M of the intermediate region may be 1.15 D or more. In this case, visual fields at not only far but also near and intermediate distances can be more easily obtained better due to the multifocal effect.

[0066] The technology disclosed in the above embodiment is only an example. Therefore, it is also possible to change the technology exemplified in the above embodiment. First, it is also possible to adopt only a part of the plurality of technologies exemplified in the above embodiment in the intraocular lens. For example, regardless of whether the condition of the MTF value exemplified in the above embodiment is satisfied, it is also possible to design the intraocular lens 1 having a plurality of segmented regions so that the conditions of S ≧ +2.75 D and M < S ≦ (M + 1.4 D) are satisfied. Even in this case, by designing the intraocular lens 1 so that the conditions of S ≧ +2.75 D and M < S ≦ (M + 1.4 D) are satisfied, regardless of the pupil size, visual fields at not only far but also near and intermediate distances can be more easily obtained better.

Explanation of Reference Numerals

[0067] 1 Intraocular lens 2 Lens part 20 Segmented region 20F Remote Use Area 20N Near Field 20I Intermediate Area 21(21A,21B,21C) Transition Department

Claims

1. An intraocular lens having a disc-shaped lens portion, Three or more segmented regions having different refractive powers are formed on at least one of the front and rear surfaces of the lens portion, The plurality of segmental regions include: a distance area with the smallest refractive power; The near area has the greatest refractive power, an intermediate area having a refractive power between the refractive power of the distance area and the refractive power of the near area; Including, The plurality of segmented regions extend radially outward from a central portion of the lens portion, The MTF curve at a spatial frequency of 50 lp / mm has an intermediate maximum value which is a maximum value in the range between the distance maximum value and the near maximum value, An intraocular lens characterized in that each of the distance maximum value, the near maximum value, and the intermediate maximum value is 0.10 or more.

2. 10. The intraocular lens of claim 1, In the MTF curve at a spatial frequency of 50 lp / mm, An intraocular lens characterized in that the difference between the smaller MTF value of the near maximum value and the intermediate maximum value and the minimum value existing between the near maximum value and the intermediate maximum value is 0.10 or less.

3. 10. The intraocular lens of claim 1, An intraocular lens characterized in that, in the MTF curve, the near maximum value is greater than the intermediate maximum value.

4. 10. The intraocular lens of claim 1, An intraocular lens characterized in that, in the MTF curve at a spatial frequency of 50 lp / mm, the difference between the near maximum value and the intermediate maximum value is 0.05 or less.

5. An intraocular lens having a disc-shaped lens portion, Three or more segmented regions having different refractive powers are formed on at least one of the front and rear surfaces of the lens portion, The plurality of segmental regions include: a distance area with the smallest refractive power; The near area has the greatest refractive power, an intermediate area having a refractive power between the refractive power of the distance area and the refractive power of the near area; Including, The plurality of segmented regions extend radially outward from a central portion of the lens portion, When the refractive power of the near zone is S and the refractive power of the intermediate zone is M, An intraocular lens characterized by satisfying both the conditions S≧+2.75D and M<S≦(M+1.4D).

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