Intraocular lens

Abstract

To provide an intraocular lens in which focal depth is appropriately increased and a fine field of view is likely to be obtained regardless of a change in size of a wearer's pupil.SOLUTION: A first area is a circular area positioned closest to a center. In the first area, first refractive power is given. A second area is an annular area adjacent to an outside of the first area. A third area is an annular area adjacent to an outside of the second area. In the third area, third refractive power different from the first refractive power is given. A fourth area is an annular area adjacent to an outside of the third area. An outer area is an annular area positioned outside the fourth area. In the outer area, reference refractive power for focusing on a long distance is given. At least a part of the first area, the second area, the third area, and the fourth area is arranged in the area of 1.5 mm radius around a shaft of a lens part.SELECTED DRAWING: Figure 3

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, an intraocular lens that focuses incident light onto a lens portion at a single focal point is known. With an intraocular lens that focuses incident light onto a single focal point, objects can be more easily viewed with higher resolution than with an intraocular lens that distributes incident light onto a lens portion and focuses it at multiple focal points.

[0003] Furthermore, techniques have been proposed for intraocular lenses that can provide adequate resolution even when the focus is shifted to some extent. For example, the intraocular lens described in Patent Document 1 has at least one lens surface aspherical to increase the depth of focus, thereby preventing a decrease in resolution when the focus is shifted. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-121433 Summary of the Invention [Problem to be solved by the invention]

[0005] However, after various simulations and studies, it was found that unless the method for expanding the depth of focus of an intraocular lens is appropriate, it is difficult to obtain a good field of view. For example, it is possible to expand the depth of focus by imparting different refractive powers to the peripheral and central portions of the lens. However, the radius of a human pupil varies between approximately 1 mm and approximately 8 mm. In the method of imparting different refractive powers to the peripheral and central portions of the lens, when the wearer's pupil becomes small, the proportion of light that passes through the peripheral region of the lens and reaches the retina becomes smaller than when the pupil is large. Therefore, when the pupil becomes small, it is difficult to obtain a good field of view corresponding to the refractive power of the peripheral portion of the lens.

[0006] A typical object of the present disclosure is to provide an intraocular lens that appropriately extends the depth of focus and is likely to provide good vision regardless of changes in the size of the wearer's pupil. [Means for solving the problem]

[0007] An intraocular lens provided by a typical embodiment of the present disclosure is an intraocular lens having a plurality of circular or annular regions concentrically arranged in the lens portion around an axis of the lens portion, the plurality of regions including: a circular first region located at the most center and having a first refractive power; an annular second region adjacent to the outside of the first region; an annular third region adjacent to the outside of the second region and having a third refractive power different from the first refractive power; an annular fourth region adjacent to the outside of the third region; and an outer region that is an annular region located outside the fourth region and having a reference refractive power for focusing on a distant object; In the first region, the refractive power increases or decreases from the first refractive power to the third refractive power as the distance from the axis increases, and in the fourth region, the refractive power changes in the opposite direction to the change in the second region as the distance from the axis increases, and at least a portion of the first region, the second region, the third region, and the fourth region are arranged within an area with a radius of 1.5 mm centered on the axis of the lens unit, and an MTF curve at a spatial frequency of 50 lp / mm for light passing through the area with a radius of 1.5 mm centered on the axis of the lens unit has one maximum value in the range of defocus amounts from -0.5D to 0.5D, and the number of minimum values ​​is 0.

[0008] The intraocular lens of the present disclosure provides an appropriate expansion of the depth of focus and tends to provide a good field of vision regardless of changes in the size of the wearer's pupil. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a plan view of an intraocular lens 1. [Figure 2] 1 is a schematic diagram showing the configuration of the front surface of the lens portion 2 of the intraocular lens of the first embodiment. FIG. [Figure 3] 1 is a graph showing the relationship between the distance from the axis O of the lens portion 2 and the refractive power (diopter) of the lens portion 2 in the first embodiment. [Figure 4]This is a graph comparing the MTF curve for light passing through an area with a radius of 1.5 mm centered on the axis O of the lens part 2 with the MTF curve for light passing through an area with a radius of 1.0 mm centered on the axis O of the lens part 2 in the first embodiment. [Figure 5] 1 is a graph comparing the MTF curve of the intraocular lens 1 of the first embodiment with the MTF curve of an intraocular lens of a comparative example. [Figure 6] 10 is a graph showing the relationship between the distance from the axis O of the lens portion 2 of the second embodiment and the refractive power (diopter) of the lens portion. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Summary> In a first aspect of the intraocular lens exemplified in the present disclosure, multiple circular or annular regions (one circular region and one or more annular regions) are concentrically arranged on the lens portion around the axis of the lens portion. The multiple regions include a first region, a second region, and an outer region. The first region is the circular region located at the most center. The first region is given a constant first refractive power regardless of the distance from the axis. The second region is an annular region adjacent to the outside of the first region. The refractive power of the second region increases or decreases from the first refractive power as the distance from the axis increases. The outer region is an annular region located outside the second region. The outer region is given a reference refractive power for focusing on distant objects. The MTF curve at a spatial frequency of 50 lp / mm for light passing through an area with a radius of 1.5 mm centered on the axis of the lens section has one maximum value in the range of defocus amounts from -0.5D to 0.5D, with the position where the MTF is greatest being the reference (0D), and the number of minimum values ​​is 0.

[0011] For example, it is possible to expand the depth of focus of an intraocular lens by designing the central part of the lens so that the refractive power becomes stronger as it approaches the axis. However, this method results in only a small amount of light passing through the part with the greatest refractive power (the axis). Therefore, the wearer cannot perceive the light passing through the axis, and therefore cannot perceive the field of view corresponding to the maximum refractive power. A similar problem can occur when the refractive power is designed to become weaker as it approaches the axis. In other words, with these methods, the light passing through the axis is lost without being perceived by the wearer.

[0012] In contrast, the intraocular lens exemplified in the present disclosure, by arranging the first region, second region, and outer region, satisfies the requirement for an intraocular lens that focuses most of the light incident on the lens portion near a predetermined focal point (a single focal point in the embodiment described below) (the requirement that the MTF curve at a spatial frequency of 50 lp / mm has one maximum value and zero minimum values ​​in the range of defocus amounts from −0.5D to 0.5D, with the position where the MTF is greatest as the reference (0D)). The depth of focus is expanded. The first region, which is located at the center, is given a constant first refractive power regardless of the distance from the axis. Therefore, unlike a case where the refractive power decreases or increases with a slight distance from the axis, the wearer can appropriately perceive the field of view corresponding to the first refractive power. This reduces the amount of light not perceived by the wearer, making it easier to obtain a good field of view. Furthermore, the wearer can obtain a field of view corresponding to a range of refractive powers close to the first refractive power by using light passing through the second region. Therefore, according to the technology of the present disclosure, the depth of focus is appropriately expanded while suppressing the amount of light that passes through the lens portion and is not recognized by the wearer.

[0013] The range of defocus amounts in which the MTF curve has one maximum value and no minimum value can be changed. For example, the MTF curve may have one maximum value and no minimum value in the defocus amount range of -1.0D to 0.5D. Also, the MTF curve may have one maximum value and no minimum value in the defocus amount range of -1.5D to 0.5D. In these cases, the intraocular lens is one in which the visual field is less likely to deteriorate even when a large defocus occurs.

[0014] Note that the phrase "a region to which a constant refractive power is imparted regardless of the distance from the axis" is used in various places in this disclosure. This phrase does not stipulate that the refractive power is strictly constant within the region. In other words, even if the refractive power fluctuates slightly within the region, for example, for the purpose of correcting aberrations, this is within the technical scope of this disclosure. For example, it is sufficient if the rate of fluctuation of the refractive power within the region (e.g., the ratio of the maximum value to the minimum value of the refractive power within the region) is within 15%, more preferably within 10%. Furthermore, the reference refractive power imparted to the outer region may also be varied to some extent within the outer region for the purpose of correcting aberrations, etc.

[0015] The ratio of the area of ​​the second region to the area of ​​the first region may be within ±50%. In other words, the condition "area of ​​the second region / area of ​​the first region ≦ 1 ± 0.5" may be satisfied. In this case, the areas of the first region and the second region are each sufficiently secured. As a result, it becomes easier to more appropriately obtain both the field of view corresponding to the first refractive power and the field of view corresponding to a range of refractive powers close to the first refractive power.

[0016] It is also possible to change the ±50% range. For example, by setting the ratio of the area of ​​the second region to the area of ​​the first region to within ±30%, the areas of the first region and the second region can be more appropriately secured.

[0017] The area of ​​each of the first and second regions is 0.6 mm 2or more. In this case, the areas of the first and second regions are sufficiently secured. As a result, it becomes easier to obtain both the field of view corresponding to the first refractive power and the field of view corresponding to a range of refractive powers close to the first refractive power.

[0018] The area of ​​the first and second regions is 0.8 mm 2 Above 1.1mm, preferably 1.1mm 2 In these cases, the areas of the first and second regions can be more appropriately secured.

[0019] The area of ​​the second region may be equal to or larger than the area of ​​the first region. In this case, the size of the second region, whose refractive power changes depending on the distance from the axis, is more appropriately ensured. Therefore, a field of view corresponding to a refractive power close to the first refractive power can be more appropriately obtained. In other words, the depth of focus of the intraocular lens becomes more appropriately deep.

[0020] The first refractive power imparted to the first region may be a stronger refractive power than the reference refractive power. In the second region, the refractive power may decrease from the strong refractive power of the first region as the distance from the axis increases. In an intraocular lens, aberrations are less likely to occur near the axis than in the peripheral portion of the lens. Furthermore, the stronger the refractive power, the greater the impact of aberrations, etc. on the wearer's visual field. Therefore, by imparting a stronger refractive power than the reference refractive power to the central first region, where aberrations are less likely to occur, the impact of aberrations, etc. on the wearer's visual field is reduced compared to when the reference refractive power is imparted to the first region.

[0021] The multiple regions may further include a third region, a fourth region, a fifth region, and a sixth region. The third region is an annular region adjacent to the outside of the second region. The third region is provided with a reference refractive power. The fourth region is an annular region adjacent to the outside of the third region. The fifth region is an annular region adjacent to the outside of the fourth region. The fifth region is provided with a strong refractive power. The sixth region is an annular region adjacent to the outside of the fifth region and adjacent to the inside of the outer region. In the fourth region, the refractive power increases from the reference refractive power of the third region to the strong refractive power of the fifth region as the distance from the axis increases. In the sixth region, the refractive power decreases from the strong refractive power of the fifth region to the reference refractive power of the outer region as the distance from the axis increases.

[0022] In this case, the following regions are arranged from the inside to the outside: a strong refractive power region (region 1), a transition region (region 2), a reference refractive power region (region 3), a transition region (region 4), a strong refractive power region (region 5), a transition region (region 6), and a reference refractive power region (region 1). In other words, two strong refractive power regions and a reference refractive power region between them are arranged inside the annular outer region. Therefore, even if the wearer's pupil is not significantly dilated (i.e., even if the pupil is smaller than the outer region), light reaching the retina is more likely to pass through the strong refractive power region, the reference refractive power region, and the transition region appropriately. As a result, an appropriate field of view is more easily obtained regardless of changes in the size of the wearer's pupil. Furthermore, the increase in aberrations caused by increasing the number of regions is less than when the number of regions inside the outer region is seven or more. Although details will be described later, the strong refractive power of the first area and the strong refractive power of the fifth area do not need to be strictly the same. Also, the reference refractive power of the third area and the reference refractive power of the outer area do not need to be strictly the same.

[0023] The area ratio between all of the first, second, third, fourth, fifth, and sixth regions may be within ±50%. In this case, the area of ​​each of the first to sixth regions is sufficiently secured. As a result, even when the pupil is smaller than the outer region, it becomes easier to obtain an appropriate field of view corresponding to the range from the reference refractive power to the strong refractive power. As mentioned above, the value of ±50% can also be changed. For example, the value of ±50% may be changed to ±30% or the like.

[0024] The area of ​​each of the first region, the second region, the third region, the fourth region, the fifth region, and the sixth region is 0.6 mm 2 In this case, the area of ​​each of the first to sixth regions is sufficiently secured. As a result, even if the pupil is smaller than the outer region, it becomes easier to obtain an appropriate field of view corresponding to the range from the reference refractive power to the strong refractive power. 2 It is also possible to change the value of "more than" to, for example, 0.6 mm. 2 The above values ​​are 0.8 mm 2 or more, or 1.1 mm 2 It may be changed to the above.

[0025] The area of ​​the fourth region may be equal to or greater than the area of ​​the third region. The area of ​​the sixth region may be equal to or greater than the area of ​​the fifth region. In these cases, a field of view corresponding to a refractive power between the reference refractive power and the strong refractive power can be more appropriately obtained. Therefore, the depth of focus of the intraocular lens becomes more appropriately deep.

[0026] It is also possible to add at least a part of the configuration of the intraocular lens of the second aspect described later to the configuration of the intraocular lens of the first aspect described above. Also, it is also possible to add at least a part of the configuration of the intraocular lens of the first aspect to the configuration of the intraocular lens of the second aspect described later.

[0027] In a second aspect of the intraocular lens exemplified in the present disclosure, a plurality of circular or annular regions (one circular region and one or more annular regions) are concentrically arranged on the lens portion around the axis of the lens portion. The plurality of regions include a first region, a second region, a third region, a fourth region, and an outer region. The first region is the circular region located at the most center. The first region is imparted with a first refractive power. The second region is an annular region adjacent to the outside of the first region. The third region is an annular region adjacent to the outside of the second region. The third region is imparted with a third refractive power different from the first refractive power. The fourth region is an annular region adjacent to the outside of the third region. The outer region is an annular region located outside the fourth region. The outer region is imparted with a reference refractive power for focusing on distant objects. In the second region, the refractive power increases or decreases from the first refractive power to the third refractive power as the distance from the axis increases. In the fourth region, the refractive power changes in the opposite direction to that in the second region as the distance from the axis increases. The first, second, third, and at least a portion of the fourth region are located within a region with a radius of 1.5 mm centered on the axis of the lens unit. The MTF curve at a spatial frequency of 50 lp / mm for light passing through the region with a radius of 1.5 mm centered on the axis of the lens unit has one maximum value in the range of defocus amounts from -0.5D to 0.5D, with the position where the MTF is greatest being set as the reference (0D), and the number of minimum values ​​is zero.

[0028] In the intraocular lens exemplified in the present disclosure, the first, second, third, and fourth regions are arranged in order from the center, thereby satisfying the requirement for an intraocular lens that focuses most of the light incident on the lens portion near a predetermined focal point (a single focal point in the embodiment described below) (the requirement that the MTF curve at a spatial frequency of 50 lp / mm has one maximum value and zero minimum values ​​in the defocus amount range of −0.5D to 0.5D), while expanding the depth of focus. Here, the first refractive power imparted to the first region and the third refractive power imparted to the third region are different. Furthermore, the refractive powers of the second and fourth regions change in opposite directions as the distance from the axis increases. Furthermore, at least a portion of the first, second, third, and fourth regions are arranged within a 1.5 mm radius, which corresponds to the radius of a human pupil when the pupil is somewhat constricted. Therefore, even if the wearer's pupil is constricted to some extent, light reaching the retina passes through each of the first region to which the first refractive power is imparted, the third region to which the third refractive power is imparted, and the transition region (second region and fourth region) where the refractive power changes between the first and third refractive powers. Therefore, regardless of changes in the size of the wearer's pupil, an appropriate field of view corresponding to the range of the first to third refractive powers can be easily obtained.

[0029] The range of defocus amounts in which the MTF curve has one maximum value and no minimum value can be changed. For example, the MTF curve may have one maximum value and no minimum value in the defocus amount range of -1.0D to 0.5D. Also, the MTF curve may have one maximum value and no minimum value in the defocus amount range of -1.5D to 0.5D. In these cases, the intraocular lens is one in which the visual field is less likely to deteriorate even when a large defocus occurs.

[0030] The third refractive power imparted to the third region may be a reference refractive power for focusing on distant objects. The first refractive power imparted to the first region may be a stronger refractive power than the reference refractive power. In the second region, the refractive power may decrease from the strong refractive power of the first region to the reference refractive power of the third region with increasing distance from the axis. In the fourth region, the refractive power may increase from the reference refractive power of the third region with increasing distance from the axis.

[0031] In intraocular lenses, aberrations are less likely to occur near the axis than at the periphery of the lens. Furthermore, the stronger the refractive power, the greater the impact of aberrations, etc., on the wearer's field of vision. Therefore, by imparting a stronger refractive power than the reference refractive power to the first central region, where aberrations are less likely to occur, the impact of aberrations, etc., on the wearer's field of vision is reduced compared to when the reference refractive power is imparted to the first region.

[0032] The reference refractive power value assigned to the third region and the reference refractive power value assigned to the outer region do not need to be exactly the same. For example, the ratio of the reference refractive power of the third region to the reference refractive power of the outer region may be within ±30% (i.e., "reference refractive power of the third region / reference refractive power of the outer region ≦ 1 ± 0.3"), more preferably within ±20%. Even in this case, an appropriate field of vision can be obtained regardless of changes in the size of the wearer's pupil. However, if the values ​​of the reference refractive power of the outer region and the reference refractive power of the third region are closer, it becomes easier to obtain distant vision when the wearer's pupil becomes somewhat smaller.

[0033] At least a portion of the first region, the second region, and the third region may be located within a region with a radius of 1.0 mm centered on the axis of the lens portion. In bright environments, the radius of the human pupil constricts to approximately 1.0 mm or less. By locating at least a portion of the first region, the second region, and the third region within a region with a radius of 1.0 mm centered on the axis, light reaching the retina passes through each of the first region, the second region, and the third region, even in very bright environments. Therefore, even when the wearer's pupil becomes very small, an appropriate field of view corresponding to a range from standard refractive power to strong refractive power can be easily obtained.

[0034] The multiple regions may further include a fifth region and a sixth region. The fifth region is an annular region adjacent to the outside of the fourth region. The fifth region is provided with a strong refractive power. The sixth region is an annular region adjacent to the outside of the fifth region and adjacent to the inside of the outer region. In the sixth region, the refractive power decreases from the strong refractive power of the fifth region to the reference refractive power of the outer region as the distance from the axis increases. In this case, from the inside to the outside, the strong refractive power region (first region), the transition region (second region), the reference refractive power region (third region), the transition region (fourth region), the strong refractive power region (fifth region), the transition region (sixth region), and the reference refractive power region (outer region) are arranged in that order. In other words, two strong refractive power regions and a reference refractive power region between them are arranged inside the annular outer region. Therefore, even if the wearer's pupil is not significantly dilated, light reaching the retina is more likely to pass through the strong refractive power region, the standard refractive power region, and the transition region appropriately. As a result, it is easier to obtain an appropriate field of view regardless of changes in the size of the wearer's pupil. In addition, the increase in aberrations due to the increase in the number of regions inside the outer region is also suppressed compared to when the number of regions inside is seven or more.

[0035] At least a portion of the first, second, third, fourth, fifth, and sixth regions may be located within a 1.5 mm radius region centered on the lens axis. In this case, even if the wearer's pupil constricts to some extent, light reaching the retina passes through the two strong refractive power regions, the base refractive power region therebetween, and the three transition regions. Therefore, regardless of changes in the size of the wearer's pupil, an appropriate field of view corresponding to the range from base refractive power to strong refractive power can be easily obtained.

[0036] The value of the strong refractive power imparted to the first region and the value of the strong refractive power imparted to the fifth region do not need to be exactly the same. For example, the ratio of the strong refractive power of the fifth region to the strong refractive power of the first region may be within ±30% (more preferably within ±20%). Even in this case, an appropriate field of view can be obtained regardless of changes in the size of the wearer's pupil.

[0037] The refractive power imparted to the fifth region may be closer to the strong refractive power imparted to the first region than to the reference refractive power imparted to the outer region, thereby providing an appropriate field of view regardless of changes in the size of the wearer's pupil.

[0038] However, when the first region is given a strong refractive power and the third region is given a standard refractive power, the configuration of the other regions can be changed. For example, the fifth region between the fourth and sixth regions can be omitted. Even in this case, a visual field corresponding to the range from the standard refractive power to the strong refractive power can be obtained.

[0039] The first refractive power imparted to the first region may be a reference refractive power for focusing on a distant object. The third refractive power imparted to the third region may be a stronger refractive power than the reference refractive power. In the second region, the refractive power may increase from the reference refractive power of the first region to the strong refractive power of the third region as the distance from the axis increases. The outer region may be provided adjacent to the outside of the fourth region. In the fourth region, the refractive power may decrease from the strong refractive power of the third region to the reference refractive power of the outer region as the distance from the axis increases. In this case, the number of regions formed inside the outer region is minimized to four. The fewer the number of regions, the more easily aberrations are suppressed. Therefore, by forming four regions inside the outer region, it is easier to obtain an appropriate field of view regardless of the size of the wearer's pupil, while suppressing aberrations.

[0040] The reference refractive power value imparted to the first region and the reference refractive power value imparted to the outer region do not need to be exactly the same. For example, the ratio of the reference refractive power of the first region to the reference refractive power of the outer region may be within ±30% (more preferably ±20%).

[0041] At least a portion of the first, second, and third regions may be located within a region with a radius of 1.0 mm centered on the axis of the lens portion. As described above, in bright environments, the radius of the human pupil constricts to approximately 1.0 mm or less. By locating at least a portion of the first, second, and third regions within a region with a radius of 1.0 mm centered on the axis, light reaching the retina passes through each of the first, second, and third regions, even in very bright environments. Therefore, even when the wearer's pupil becomes very small, an appropriate field of view corresponding to a range from standard refractive power to strong refractive power can be easily obtained.

[0042] First Embodiment (Schematic configuration) An intraocular lens 1 according to a first embodiment will be described with reference to FIGS. 1 to 5. First, the schematic configuration of the intraocular lens 1 will be described with reference to FIG. 1. The schematic configuration of the intraocular lens 1 described below is also common to the intraocular lens according to a second embodiment, which will be described later. Furthermore, in the first and second embodiments, an intraocular lens that focuses most of the light incident on the lens portion 2 near a single focal point (a so-called monofocal intraocular lens) will be described as an example. However, the intraocular lens to which the technology of the present disclosure can be applied is only required to satisfy the requirement that the MTF curve at a spatial frequency of 50 lp / mm has one maximum value within the range of defocus amounts from −0.5D to 0.5D and the number of minimum values ​​is zero. Therefore, the technology of the present disclosure can also be applied to various intraocular lenses other than monofocal intraocular lenses (e.g., multifocal intraocular lenses).

[0043] The intraocular lens 1 includes a lens portion (optical portion) 2 and haptics 3. The intraocular lens 1 of this embodiment is a so-called one-piece intraocular lens in which the lens portion 2 and haptics 3 are integrally molded. However, the technology exemplified in this disclosure can also be applied to intraocular lenses other than one-piece types (e.g., three-piece intraocular lenses, etc.). The material of the intraocular lens 1 can be various soft materials, such as simple substances such as BA (butyl acrylate) and HEMA (hydroxyethyl methacrylate), or composite materials of acrylic esters and methacrylic esters.

[0044] The lens unit 2 provides a predetermined refractive power to the patient's eye. A pair of lens surfaces (front and rear surfaces) of the lens unit 2 are formed as convex surfaces. The lens unit 2 has an axis O that passes through the center of the lens unit perpendicular to the lens surfaces. In this embodiment, the axis O of the lens unit 2 coincides with the optical axis of the lens unit 2.

[0045] In the intraocular lens 1 of this embodiment, at least one of the pair of lens surfaces of the lens portion 2 is formed aspherically, thereby adjusting the refractive power of each portion of the lens portion 2. As an example, in this embodiment, the front surface (convex surface) of the lens portion 2 is formed aspherically, thereby adjusting the refractive power of each portion of the lens portion 2. However, the rear surface or both surfaces of the lens portion 2 may be formed aspherically. For example, of the front and rear surfaces of the lens portion 2, the surface opposite to the side that is formed aspherically to achieve the refractive power arrangement described below may be formed in a toric shape to correct astigmatism. In this case, in addition to the effect of the intraocular lens 1 described in this embodiment, the effect of correcting astigmatism is also imparted.

[0046] The haptics 3 support the lens portion 2 inside the wearer's eye (inside the capsule in this embodiment). As an example, the intraocular lens 1 of this embodiment is provided with a pair of haptics 3. However, the number of haptics 3 is not limited to two. In this embodiment, the shape of the haptics 3 is a loop curved in the circumferential direction. The tip of the haptics 3 is a free end.

[0047] (Lens area) The lens portion 2 of the intraocular lens 1 of the first embodiment will be described in detail with reference to Fig. 2. As shown in Fig. 2, when the lens portion 2 is viewed from the direction along the axis O (from the front in Fig. 2), a plurality of circular or annular regions R1 to R6, RO are arranged in the lens portion 2 concentrically around the axis O. As described above, in this embodiment, the front surface (convex surface) of the lens portion 2 is formed into an aspherical shape, thereby providing a plurality of regions R1 to R6, RO.

[0048] The first region R1 is a circular region located at the center of the multiple regions. The second region R2, the third region R3, the fourth region R4, the fifth region R5, the sixth region R6, and the outer region RO are all annular regions. The second region R2 is adjacent to the outside of the first region R1. The third region R3 is adjacent to the outside of the second region R2. The fourth region R4 is adjacent to the outside of the third region R3. The fifth region R5 is adjacent to the outside of the fourth region R4. The sixth region R6 is adjacent to the outside of the fifth region R5. The outer region RO is adjacent to the outside of the sixth region R6.

[0049] (Refractive power of each area) The refractive power in each of the regions R1 to R6, RO of the lens unit 2 of the first embodiment will be described with reference to Fig. 3. In the graph shown in Fig. 3, the horizontal axis represents the distance from the axis O of the lens unit 2, and the vertical axis represents the refractive power (diopter) of the lens unit 2. In this embodiment, the refractive power imparted to the lens unit 2 so that the wearer can focus on a distant object is defined as the reference refractive power. In the graph, the reference refractive power is set to "0D." The stronger the imparted refractive power, the closer the wearer will focus on a near object.

[0050] The refractive power (first refractive power) imparted to the first region R1 is stronger than the reference refractive power for focusing on a distant object (hereinafter referred to as "strong refractive power"). In detail, the first region R1 of this embodiment is imparted with a constant strong refractive power regardless of the distance from the axis O.

[0051] In the second region R2, the refractive power decreases from the first refractive power as the distance from the axis O increases. In detail, the refractive power in the second region R2 decreases from the strong refractive power of the first region R1 to the third refractive power (reference refractive power) imparted to the third region R3 as the distance from the axis O increases. Note that the refractive power in the second region R2 in this embodiment decreases in proportion to the distance from the axis O.

[0052] The refractive power (third refractive power) imparted to the third region R3 is a reference refractive power. Specifically, in this embodiment, the third region R3 is imparted with a constant reference refractive power regardless of the distance from the axis O.

[0053] In the fourth region R4, the refractive power increases from the third refractive power as the distance from the axis O increases. Specifically, the refractive power in the fourth region R4 increases from the reference refractive power of the third region R3 to the fifth refractive power (strong refractive power) imparted to the fifth region R5 as the distance from the axis O increases. Note that the refractive power in the fourth region R4 of this embodiment increases in proportion to the distance from the axis O.

[0054] The refractive power (fifth refractive power) imparted to the fifth region R5 is strong refractive power. Specifically, in this embodiment, a constant strong refractive power is imparted to the fifth region R5 regardless of the distance from the axis O. Furthermore, in this embodiment, the value of the strong refractive power imparted to the first region R1 and the value of the strong refractive power imparted to the fifth region R5 are the same. However, the values ​​of the strong refractive power imparted to the first region R1 and the fifth region R5 do not need to be strictly the same. For example, the ratio of the strong refractive power of the fifth region R5 to the strong refractive power of the first region R1 may be within ±30% (more preferably, within ±20%). Even in this case, an appropriate field of view can be obtained regardless of changes in the size of the wearer's pupil.

[0055] In the sixth region R6, the refractive power decreases from the fifth refractive power as the distance from the axis O increases. In detail, the refractive power in the sixth region R6 decreases from the strong refractive power of the fifth region R5 to the reference refractive power imparted to the outer region RO as the distance from the axis O increases. Note that the refractive power in the sixth region R6 of this embodiment decreases in proportion to the distance from the axis O.

[0056] The refractive power imparted to the outer region RO is a reference refractive power. Specifically, in this embodiment, the reference refractive power is constant in the outer region RO regardless of the distance from the axis O. However, the reference refractive power imparted to the outer region RO may vary within the region for purposes such as aberration correction. In this embodiment, the reference refractive power imparted to the third region R3 and the reference refractive power imparted to the outer region RO are the same. However, the reference refractive powers imparted to the third region R3 and the outer region RO do not need to be strictly the same. For example, the ratio of the reference refractive power of the third region R3 to the reference refractive power of the outer region RO may be within ±30% (more preferably, within ±20%). Even in this case, an appropriate visual field can be obtained regardless of changes in the size of the wearer's pupil.

[0057] In this embodiment, among the multiple regions R1 to R6, RO, the regions whose refractive power increases or decreases as the distance from the axis O increases (i.e., the second region R2, the fourth region R4, and the sixth region R6) are sometimes referred to as transition regions.

[0058] (area of ​​each area) In this embodiment, the area ratios among all of the first region R1, second region R2, third region R3, fourth region R4, fifth region R5, and sixth region R6 are within ±50%. Specifically, in this embodiment, the lens portion 2 is designed so that the areas of the first region R1 to sixth region R6 are the same.

[0059] In this embodiment, the area of ​​each of the first region R1, the second region R2, the third region R3, the fourth region R4, the fifth region R5, and the sixth region R6 is 0.6 mm 2 In detail, in this embodiment, the area of ​​each of the first region R1 to the sixth region R6 is 1.1 mm 2 That's all.

[0060] (MTF characteristics) The MTF characteristics of the intraocular lens 1 of this embodiment will be described with reference to Figures 4 and 5. MTF (Modulation Transfer Function) is an index that indicates contrast. The graphs in Figures 4 and 5 show MTF curves at a spatial frequency of 50 lp / mm, with the horizontal axis representing the amount of defocus (amount of deviation from focus or power) and the vertical axis representing MTF.

[0061] 4 is a graph comparing the MTF curves for light passing through a region of radius 1.5 mm (diameter 3.0 mm) centered on the axis O of the lens unit 2 and the MTF curves for light passing through a region of radius 1.0 mm (diameter 2.0 mm) centered on the axis O of the lens unit 2 in an optical system simulating the eye of a wearer wearing the intraocular lens 1 of the first embodiment. In FIG. 4, the MTF curve for the region of radius 1.5 mm (diameter 3.0 mm) is shown by a dotted line, and the MTF curve for the region of radius 1.0 mm (diameter 2.0 mm) is shown by a solid line. Note that the region of radius 1.5 mm (diameter 3.0 mm) centered on the axis O of the lens unit 2 approximates the region through which light passes when the wearer's pupil is constricted to a certain extent. Furthermore, the region of radius 1.0 mm (diameter 2.0 mm) centered on the axis O of the lens unit 2 approximates the region through which light passes when the wearer's pupil is very small.

[0062] As shown in FIG. 4, the intraocular lens 1 of the first embodiment satisfies the requirement for an intraocular lens that focuses most of the light incident on the lens portion 2 near a predetermined focal point (a single focal point in this embodiment) even when light passes through a region with a radius of 1.5 mm (i.e., when the wearer's pupil is constricted to a certain extent). This requirement means that the MTF curve at a spatial frequency of 50 lp / mm has one maximum value in the range of defocus amounts from −0.5D to 0.5D (more specifically, from −1.5D to 0.5D), with the position where the MTF is greatest as the reference (0D), and the number of minimum values ​​is zero. Furthermore, the MTF value does not only take high values ​​near the maximum value, but remains high even when the defocus amount increases or decreases to a certain extent. In other words, the intraocular lens 1 of the first embodiment has an appropriately extended depth of focus.

[0063] 4, even when light passes through an area with a radius of 1.0 mm (diameter of 2.0 mm) (i.e., when the wearer's pupil becomes very small), the requirement for an intraocular lens that focuses most of the light incident on the lens portion 2 near a predetermined focal point (a single focal point in this embodiment) is met, and the depth of focus is also appropriately expanded. Furthermore, the best focus position when the radius is 1.0 mm changes by only about -0.15 D from the best focus position when the radius is 1.5 mm. Therefore, even when the wearer's pupil becomes very small, distance vision is unlikely to deteriorate.

[0064] FIG. 5 is a graph showing simulation results comparing the MTF curves of the intraocular lens 1 of the first embodiment and the intraocular lens of a comparative example. The intraocular lens of the comparative example differs from the intraocular lens 1 of the first embodiment only in the magnitude of the strong refractive power imparted to the first region R1 and the fifth region R5 and the amount of change in refractive power in the second region R2, the fourth region R4, and the sixth region R6. Specifically, in the intraocular lens of the comparative example, a strong refractive power of approximately 2.4D is imparted to the first region R1, and a strong refractive power of approximately 2.8D is imparted to the fifth region R5. In contrast, in the intraocular lens 1 of the first embodiment, a strong refractive power of 1.3D is imparted to each of the first region R1 and the fifth region R5 (see FIG. 3). Note that the light-passing region was unified to a region with a radius of 1.5 mm (diameter 3.0 mm) centered on the axis O.

[0065] As shown in FIG. 5 , in the intraocular lens of the comparative example, the magnitude of the strong refractive power imparted to the first region R1 and the fifth region R5 is significantly greater than that of the intraocular lens 1 of the first embodiment, resulting in the formation of a distance focus and a near focus. In other words, the intraocular lens of the comparative example has the properties of a multifocal intraocular lens and is unable to focus most of the light incident on the lens portion 2 near a single focus. In contrast, in the intraocular lens 1 of the first embodiment, the values ​​of the strong refractive power imparted to the first region R1 and the fifth region R5 are appropriately adjusted, thereby appropriately expanding the depth of focus while maintaining the function of focusing most of the light incident on the lens portion 2 near a single focus. Note that the peak appearing between the distance focus and the near focus in the graph of the comparative example is not an intermediate focus, but a peak appearing due to a phenomenon called spurious resolution.

[0066] (Reduction of light loss) As shown in FIG. 3 , the first region R1 is given a constant first refractive power (strong refractive power in this embodiment) regardless of the distance from the axis O. Therefore, unlike when the refractive power decreases or increases with a slight distance from the axis O, the wearer can appropriately recognize the field of view corresponding to the first refractive power. This reduces the amount of light not recognized by the wearer, making it easier to obtain a good field of view. Furthermore, the wearer can obtain a field of view corresponding to a range of refractive power close to the first refractive power by using light that passes through the second region R2. Therefore, according to the technology of the present disclosure, the depth of focus is appropriately expanded while reducing the amount of light that passes through the lens unit 2 that is not recognized by the wearer.

[0067] The ratio of the area of ​​the second region R2 to the area of ​​the first region R1 is within ±50%. As a result, the areas of the first region R1 and the second region R2 are sufficiently secured. In the first embodiment, the areas of the first region R1 and the second region R2 are each set to 0.6 mm 2 By doing so, the first region R1 and the second region R2 each have a sufficient area, making it easier to more appropriately obtain both the field of view corresponding to the first refractive power and the field of view corresponding to a range of refractive powers close to the first refractive power.

[0068] The area of ​​the second region R2 is equal to or larger than the area of ​​the first region R1 (in this embodiment, the area of ​​the first region R1 is the same as the area of ​​the second region R2). As a result, the size of the second region R2, whose refractive power changes depending on the distance from the axis O, is appropriately ensured. Therefore, a field of view corresponding to a refractive power close to the first refractive power can be more appropriately obtained. In other words, the depth of focus of the intraocular lens 1 is more appropriately expanded.

[0069] As shown in FIG. 3 , in the intraocular lens 1 of the first embodiment, a strong refractive power is imparted to the first region R1. Furthermore, in the second region R2, the refractive power decreases from the strong refractive power of the first region R1 as the distance from the axis O increases. In the intraocular lens, aberrations are less likely to occur near the axis O than in the peripheral portion of the lens portion 2. Furthermore, the stronger the refractive power, the greater the impact of aberrations, etc. on the wearer's visual field. Therefore, by imparting a strong refractive power stronger than the reference refractive power to the central first region R1, where aberrations are less likely to occur, the impact of aberrations, etc. on the wearer's visual field is reduced compared to when the reference refractive power is imparted to the first region R1.

[0070] As shown in FIGS. 2 and 3 , in the first embodiment, the strong refractive power region (first region R1), the transition region (second region R2), the reference refractive power region (third region R3), the transition region (fourth region R4), the strong refractive power region (fifth region R5), the transition region (sixth region R6), and the reference refractive power region (outer region RO) are arranged in order from the inside to the outside. In other words, two strong refractive power regions and a reference refractive power region between them are arranged inside the annular outer region RO. Therefore, even when the pupil is smaller than the outer region RO, light reaching the retina is more likely to pass through the strong refractive power region, the reference refractive power region, and the transition region appropriately. As a result, an appropriate field of view is more easily obtained. Furthermore, the increase in aberrations due to the increased number of regions is suppressed compared to when the number of regions inside the outer region RO is seven or more. Furthermore, in the fifth region R5, similar to the first region R1, a constant strong refractive power is imparted regardless of the distance from the axis O. Therefore, a visual field corresponding to the strong refractive power is appropriately obtained. In other words, the amount of light not recognized by the wearer is appropriately reduced.

[0071] The area ratio between all of the first region R1, second region R2, third region R3, fourth region R4, fifth region R5, and sixth region R6 is within ±50%. As a result, the area of ​​each of the first region R1 to sixth region R6 is sufficiently secured. In the first embodiment, the area of ​​each of the third region R3, fourth region R4, fifth region R5, and sixth region R6 is set to 0.6 mm 2 By setting the above, each area is sufficiently secured, and therefore, even when the pupil is smaller than the outer region RO, it becomes easier to obtain an appropriate field of view corresponding to the range from the reference refractive power to the strong refractive power.

[0072] As shown in FIG. 3, in the transition regions (the second region R2, the fourth region R4, and the sixth region R6 in the first embodiment), the refractive power increases or decreases in proportion to the distance from the axis O. Therefore, compared to when the distance from the axis O and the refractive power are not proportional, the possibility of a numerical value significantly deviating from the desired numerical value appearing in some areas is reduced. This also simplifies the design of the lens portion 2. Furthermore, in addition to the second region R2, the fourth region R4 and the sixth region R6 also have an area equal to or larger than the area of ​​the first region R1 (in this embodiment, the areas of the first region R1 to the sixth region R6 are all the same). As a result, a more appropriate field of view corresponding to a refractive power between the reference refractive power and the strong refractive power can be obtained.

[0073] (Measures for changes in pupil size) As shown in FIG. 3 , the refractive powers of the second region R2 and the fourth region R4 change in opposite directions as the distance from the axis O increases. Furthermore, the first region R1, the second region R2, the third region R3, and at least a portion of the fourth region R4 (in this embodiment, the entire fourth region R4) are located within a region with a radius of 1.5 mm, which corresponds to the radius of a human pupil when the pupil is constricted to a certain extent. Therefore, even when the wearer's pupil is constricted to a certain extent, light reaching the retina passes through the first region R1, which is provided with the first refractive power, the third region R3, which is provided with the third refractive power, and the transition region (the second region R2 and the fourth region R4) where the refractive power changes between the first and third refractive powers. Therefore, regardless of changes in the size of the wearer's pupil, an appropriate field of view corresponding to the range from the first refractive power to the third refractive power can be easily obtained.

[0074] In detail, in the first embodiment, the first refractive power imparted to the first region R1 is a strong refractive power, and the third refractive power imparted to the third region R3 is a reference refractive power. As described above, by imparting a strong refractive power stronger than the reference refractive power to the first region R1 at the center where aberrations are unlikely to occur, the influence of aberrations and the like on the wearer's field of vision is reduced compared to when the reference refractive power is imparted to the first region R1.

[0075] As shown in FIGS. 2 and 3 , in the first embodiment, the first region R1, the second region R2, and portions of the third region R3 are arranged within a region with a radius of 1.0 mm centered on the axis O of the lens unit 2. In bright environments, the radius of the human pupil constricts to approximately 1.0 mm or less. By arranging at least portions of the first region R1, the second region R2, and the third region R3 within a region with a radius of 1.0 mm centered on the axis O, light reaching the retina passes through each of the first region R1, the second region R2, and the third region R3, even in very bright environments. Therefore, even when the wearer's pupil becomes very small, an appropriate field of view corresponding to a range from standard refractive power to strong refractive power can be easily obtained.

[0076] As described above, in the first embodiment, two strong-power regions and a reference-power region between them are located inside the annular outer region RO. That is, at least a portion of the first region R1, the second region R2, the third region R3, the fourth region R4, the fifth region R5, and the sixth region R6 may be located within a region with a radius of 1.5 mm centered on the axis O of the lens unit 2. Therefore, even if the wearer's pupil constricts to some extent, light reaching the retina is likely to pass appropriately through each of the two strong-power regions, the reference-power region, and the transition region. Therefore, an appropriate field of view corresponding to the range from the reference power to the strong power can be easily obtained regardless of changes in the size of the wearer's pupil.

[0077] The configuration of the third region R3 to the sixth region R6 can also be changed. For example, the third region R3 to the sixth region R6 may also be given the standard refractive power, similar to the outer region RO. Even in this case, the first region R1 and the second region R2 can provide a good field of view while suppressing light loss. It is also possible to omit the fifth region R5 between the fourth region R4 and the sixth region R6. Even in this case, a field of view corresponding to a range from standard refractive power to strong refractive power can be obtained.

[0078] Second Embodiment An intraocular lens of a second embodiment will be described with reference to Fig. 6. The intraocular lens of the second embodiment and the intraocular lens 1 of the first embodiment differ only in the arrangement of the multiple regions in the lens portion 2 and the refractive power of each region, and the other configurations are common. Therefore, the description of the configuration of the intraocular lens of the second embodiment that is common to the intraocular lens 1 of the first embodiment will be omitted or simplified. Note that, like the first embodiment, the intraocular lens of the second embodiment also satisfies the requirement for an intraocular lens that focuses most of the light incident on the lens portion 2 near a predetermined focal point (a single focal point in the embodiments described below) (the requirement that the MTF curve at a spatial frequency of 50 lp / mm has one maximum value and the number of minimum values ​​is zero in the range of defocus amounts from -0.5D to 0.5D).

[0079] (Lens area) The regions of the lens portion 2 in the intraocular lens of the second embodiment will be described below. As shown in Fig. 6, the lens portion 2 has a plurality of regions R1 to R4, RO concentrically arranged around an axis O.

[0080] The first region R1 is a circular region located at the center of the multiple regions. The second region R2, the third region R3, the fourth region R4, and the outer region RO are all annular regions. The second region R2 is adjacent to the outside of the first region R1. The third region R3 is adjacent to the outside of the second region R2. The fourth region R4 is adjacent to the outside of the third region R3. The outer region RO is adjacent to the outside of the fourth region R4.

[0081] (Refractive power of each area) The refractive power in each of the regions R1 to R4 and RO of the lens unit 2 of the second embodiment will be described. In the graph shown in Fig. 6, similar to the graph shown in Fig. 3, the horizontal axis represents the distance from the axis O of the lens unit 2, and the vertical axis represents the refractive power (diopter) of the lens unit 2.

[0082] The refractive power (first refractive power) imparted to the first region R1 is set to a reference refractive power. Specifically, in this embodiment, the first region R1 is given a constant reference refractive power regardless of the distance from the axis O.

[0083] In the second region R2, the refractive power increases from the first refractive power as the distance from the axis O increases. Specifically, the refractive power in the second region R2 increases from the reference refractive power of the first region R1 to the third refractive power (strong refractive power) imparted to the third region R3 as the distance from the axis O increases. Note that the refractive power in the second region R2 in this embodiment increases in proportion to the distance from the axis O.

[0084] The refractive power (third refractive power) imparted to the third region R3 is a strong refractive power stronger than the reference refractive power. In detail, the third region R3 of this embodiment is imparted with a constant strong refractive power regardless of the distance from the axis O.

[0085] In the fourth region R4, the refractive power decreases from the third refractive power as the distance from the axis O increases. Specifically, the refractive power in the fourth region R4 decreases from the strong refractive power of the third region R3 to the reference refractive power imparted to the outer region RO as the distance from the axis O increases. Note that a portion of the fourth region R4 in this embodiment also includes a region where the refractive power is constant regardless of the distance from the axis O (hereinafter referred to as a "constant region"). However, the constant region does not necessarily have to be provided in the fourth region R4. In the fourth region R4 in the second embodiment, the refractive power decreases in proportion to the distance from the axis O in regions other than the constant region.

[0086] The refractive power imparted to the outer region RO is a reference refractive power. Specifically, in this embodiment, the reference refractive power is constant in the outer region RO regardless of the distance from the axis O. However, the reference refractive power imparted to the outer region RO may vary within the region for purposes such as aberration correction. In this embodiment, the reference refractive power imparted to the first region R1 and the reference refractive power imparted to the outer region RO are the same. However, the values ​​of the reference refractive power imparted to the first region R1 and the outer region RO do not need to be strictly the same. For example, the ratio of the reference refractive power of the first region R1 to the reference refractive power of the outer region RO may be within ±30% (more preferably, within ±20%). Even in this case, an appropriate visual field can be obtained regardless of changes in the size of the wearer's pupil.

[0087] (area of ​​each area) In this embodiment, the area ratios of all of the first region R1, second region R2, and third region R3 are within ±50%. Specifically, in this embodiment, the lens portion 2 is designed so that the areas of the first region R1 to third region R3 are the same.

[0088] In this embodiment, the areas of the first region R1, the second region R2, the third region R3, and the fourth region R4 are 0.6 mm 2 In detail, in this embodiment, the area of ​​each of the first region R1 to the fourth region R4 is 1.1 mm 2 That's all.

[0089] (Reduction of light loss) As shown in FIG. 6 , the first region R1 is given a constant first refractive power (reference refractive power in the second embodiment) regardless of the distance from the axis O. Therefore, unlike when the refractive power decreases or increases with a slight distance from the axis O, the wearer can properly recognize the field of view corresponding to the first refractive power (i.e., the field of view obtained by light passing through the first region R1). This reduces the amount of light not recognized by the wearer, making it easier to obtain a good field of view. Furthermore, the wearer can obtain a field of view corresponding to a range of refractive powers close to the first refractive power by light passing through the second region R2. Therefore, according to the technology of the present disclosure, the depth of focus is appropriately expanded while reducing the amount of light not recognized by the wearer among the light passing through the lens portion 2.

[0090] The ratio of the area of ​​the second region R2 to the area of ​​the first region R1 is within ±50%. As a result, the areas of the first region R1 and the second region R2 are sufficiently secured. In the first embodiment, the areas of the first region R1 and the second region R2 are each set to 0.6 mm 2 By doing so, the first region R1 and the second region R2 each have a sufficient area, making it easier to more appropriately obtain both the field of view corresponding to the first refractive power and the field of view corresponding to a range of refractive powers close to the first refractive power.

[0091] The areas of the second region R2 and the fourth region R4 are equal to or larger than the area of ​​the first region R1. As a result, the sizes of the second region R2 and the fourth region R4, whose refractive power changes depending on the distance from the axis O, are appropriately secured. Therefore, a field of view corresponding to a refractive power close to the first refractive power can be more appropriately obtained. In other words, the depth of focus of the intraocular lens 1 is more appropriately extended.

[0092] In the second embodiment, the areas of the third region R3 and the fourth region R4 are also 0.6 mm 2 By setting the above, each area is sufficiently secured, and therefore, even when the pupil is smaller than the outer region RO, it becomes easier to obtain an appropriate field of view corresponding to the range from the reference refractive power to the strong refractive power.

[0093] (Measures for changes in pupil size) In the second region R2 and the fourth region R4, the refractive power changes in opposite directions as the distance from the axis O increases. Furthermore, at least a portion of the first region R1, the second region R2, the third region R3, and the fourth region R4 is located within a 1.5 mm radius area, which corresponds to the radius of a human pupil when the pupil is somewhat constricted. Therefore, even when the wearer's pupil is somewhat constricted, light reaching the retina passes through the first region R1, which is provided with the first refractive power, the third region R3, which is provided with the third refractive power, and the transition region (the second region R2 and the fourth region R4) where the refractive power changes between the first and third refractive powers. Therefore, regardless of changes in the size of the wearer's pupil, an appropriate field of view corresponding to the range of the first to third refractive powers can be easily obtained.

[0094] In detail, in the second embodiment, the first refractive power imparted to the first region R1 is a reference refractive power, and the third refractive power imparted to the third region R3 is a strong refractive power. In this case, the number of regions formed inside the outer region RO is as few as possible, that is, four. The fewer the number of regions, the more easily the amount of aberration generated is suppressed. Therefore, by setting the number of regions formed inside the outer region RO to four, it becomes easier to obtain an appropriate field of view regardless of the size of the wearer's pupil, while suppressing the generation of aberration.

[0095] In the second embodiment, the first region R1, the second region R2, and portions of the third region R3 are arranged within a region with a radius of 1.0 mm centered on the axis O of the lens unit 2. As described above, in bright environments, the radius of the human pupil constricts to approximately 1.0 mm or less. By arranging at least portions of the first region R1, the second region R2, and the third region R3 within a region with a radius of 1.0 mm centered on the axis O, light reaching the retina passes through each of the first region R1, the second region R2, and the third region R3, even in very bright environments. Therefore, even when the wearer's pupil becomes very small, an appropriate field of view corresponding to a range from standard refractive power to strong refractive power can be easily obtained.

[0096] The techniques disclosed in the above embodiments are merely examples. Therefore, the techniques exemplified in the above embodiments may be modified. For example, only some of the techniques exemplified in the first and second embodiments may be employed in the intraocular lens. [Explanation of symbols]

[0097] 1. Intraocular lenses 2 Lens section 3 Support part O-axis R1 1st area R2 2nd area R3 3rd area R4 4th area R5 5th area R6 6th area RO outer area

Claims

1. An intraocular lens, A plurality of circular or annular regions are arranged in the lens portion concentrically about an axis of the lens portion, The plurality of regions include: a first region having a circular shape and a first refractive power, the first region being located at the most center of the lens; an annular second region adjacent to the outside of the first region; an annular third region adjacent to the outside of the second region and having a third refractive power different from the first refractive power; an annular fourth region adjacent to the outside of the third region; an outer region which is an annular region located outside the fourth region and has a reference refractive power for focusing on a distant object; Including, In the second region, the refractive power increases or decreases from the first refractive power to the third refractive power as the distance from the axis increases, In the fourth region, the refractive power changes in a direction opposite to that in the second region as the distance from the axis increases, At least a portion of the first region, the second region, the third region, and the fourth region are disposed within a region having a radius of 1.5 mm centered on the axis of the lens portion, An intraocular lens characterized in that an MTF curve at a spatial frequency of 50 lp / mm for light passing through an area with a radius of 1.5 mm centered on the axis of the lens portion has one maximum value in the range of defocus amounts from -0.5D to 0.5D, and the number of minimum values ​​is 0.

2. 2. The intraocular lens of claim 1, the third refractive power imparted to the third region is the reference refractive power; the first refractive power imparted to the first region is a stronger refractive power than the reference refractive power, In the second region, the refractive power decreases with increasing distance from the axis from the strong refractive power of the first region to the reference refractive power of the third region, An intraocular lens, characterized in that in the fourth region, the refractive power increases from the reference refractive power of the third region with increasing distance from the axis.

3. 3. The intraocular lens according to claim 2, An intraocular lens characterized in that at least a portion of the first region, the second region, and the third region are arranged within an area of ​​radius 1.0 mm centered on the axis of the lens portion.

4. The intraocular lens according to claim 2 or 3, The plurality of regions include: a fifth region having an annular shape and adjacent to the outside of the fourth region and having the strong refractive power; an annular sixth region adjacent to the outside of the fifth region and adjacent to the inside of the outer region; Further comprising: An intraocular lens, characterized in that in the sixth region, the refractive power decreases from the strong refractive power of the fifth region to the reference refractive power of the outer region with increasing distance from the axis.

5. An intraocular lens as described in claim 1, the first refractive power imparted to the first region is the reference refractive power; the third refractive power imparted to the third region is a stronger refractive power than the reference refractive power, In the second region, the refractive power increases with increasing distance from the axis from the base refractive power of the first region to the strong refractive power of the third region; The outer region is provided adjacent to the outside of the fourth region, An intraocular lens, characterized in that in the fourth region, the refractive power decreases from the strong refractive power of the third region to the reference refractive power of the outer region with increasing distance from the axis.

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