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] This disclosure relates to an intraocular lens that is inserted into the eye. [Background technology]

[0002] Among intraocular lenses (IOLs) inserted into the eye, those that focus incoming light onto the lens portion to a single focal point are known. Compared to IOLs that distribute and focus incoming light onto multiple focal points, objects are more easily perceived with higher resolution when using IOLs that focus incoming light onto the lens portion to multiple focal points.

[0003] Furthermore, techniques have been proposed for intraocular lenses to obtain appropriate resolution even when the focus is shifted to some extent. For example, in the intraocular lens described in Patent Document 1, the reduction in resolution when the focus is shifted is suppressed by making at least one surface of the lens an aspherical surface to expand the depth of focus. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2004-121433 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, after various simulations and studies, it was found that if the method for expanding the depth of focus of the intraocular lens is not appropriate, it is difficult to obtain a good field of vision. For example, one method to expand the depth of focus is to apply different refractive powers to the peripheral and central parts of the lens. However, the human pupil varies in radius between approximately 1 mm and 8 mm. In the method of applying different refractive powers to the peripheral and central parts of the lens, when the wearer's pupil becomes smaller, the proportion of light passing through the peripheral region of the lens and reaching the retina decreases compared to when the pupil is larger. Therefore, when the pupil becomes smaller, it is difficult to obtain a good field of vision corresponding to the refractive power of the peripheral part of the lens.

[0006] A typical object of this disclosure is to provide an intraocular lens that appropriately expands the depth of focus and makes it easier to obtain a good field of view regardless of changes in the wearer's pupil size. [Means for solving the problem]

[0007] An intraocular lens provided by a typical embodiment of this disclosure is an intraocular lens in which a plurality of circular or annular regions are arranged concentrically around the axis of the lens portion, the plurality of regions being the most centrally located, This is a strong refractive power, which is stronger than the standard refractive power used to focus on distant objects. A circular first region to which a first refractive force is applied, an annular second region adjacent to the outside of the first region, and adjacent to the outside of the second region, The aforementioned reference refractive power A third annular region to which a third refractive force is applied, a fourth annular region adjacent to the outside of the third region, and an annular region located outside the fourth region. The aforementioned The region includes an outer region to which a reference refractive power is applied, and in the second region, the refractive power increases as the distance from the axis increases. The strong refractive power of the first region From the above first refractive force , the reference refractive power of the third region The third refractive power Reduce In the fourth region, as the distance from the axis increases, As the refractive power increases from the reference refractive power in the third region,The change is in the opposite direction to the change in the second region, and at least a portion of the first region, the second region, the third region, and the fourth region are located within a region with a radius of 1.5 mm centered on the axis of the lens portion, and 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 portion has one maximum value in the range of defocus amount -0.5D to 0.5D, and the number of minimum values ​​is 0.

[0008] The intraocular lens described herein appropriately expands the depth of focus and makes it easier to obtain a good field of vision regardless of changes in the wearer's pupil size. [Brief explanation of the drawing]

[0009] [Figure 1] This is a plan view of intraocular lens 1. [Figure 2] This is a schematic diagram showing the configuration of the front surface of the lens portion 2 in the intraocular lens of the first embodiment. [Figure 3] This graph shows the relationship between the distance of the lens portion 2 from axis O and the refractive power (diopter) of the lens portion 2 in the first embodiment. [Figure 4] In the first embodiment, this graph compares the MTF curve for light passing through a region with a radius of 1.5 mm centered on the axis O of the lens portion 2 with the MTF curve for light passing through a region with a radius of 1.0 mm centered on the axis O of the lens portion 2. [Figure 5] This graph compares the MTF curve of intraocular lens 1 of the first embodiment with the MTF curve of the intraocular lens of the comparative example. [Figure 6] This graph shows the relationship between the distance of the lens portion 2 from axis O and the refractive power (diopter) of the lens portion in the second embodiment. [Modes for carrying out the invention]

[0010] <Overview> In a first aspect of the intraocular lens exemplified in the present disclosure, a plurality of regions (one circular region and one or more annular regions), which are circular or annular, are arranged in the lens portion concentrically around the axis of the lens portion. The plurality of regions include a first region, a second region, and an outer region. The first region is the circular region located at the most center. A first refractive power is constantly applied to the first region regardless of the distance from the axis. The second region is an annular region adjacent to the outside of the first region. In the second region, the refractive power 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. A reference refractive power for focusing at a distance is applied to the outer region. For light passing through a region with a radius of 1.5 mm centered on the axis of the lens portion, the MTF curve at a spatial frequency of 50 lp / mm has one maximum value in the range of defocus amount of -0.5D to 0.5D with the position where the MTF is the largest as a reference (0D), and the number of minimum values is 0.

[0011] For example, at the central part of the lens portion, it is also conceivable to expand the depth of focus of the intraocular lens by designing so that the refractive power becomes stronger as it approaches the axis. However, in this method, the amount of light passing through the portion where the refractive power is maximum (the portion of the axis) becomes extremely small. Therefore, since the wearer cannot recognize the light passing through the portion of the axis, the wearer cannot recognize the visual field corresponding to the maximum refractive power. The same problem may occur when designing so that the refractive power becomes weaker as it approaches the axis. That is, in these methods, the light passing through the portion of the axis is lost without being recognized by the wearer.

[0012] In contrast, in the intraocular lens exemplified in the present disclosure, the first region, the second region, and the outer region are arranged so that a large amount of incident light on the lens unit is condensed near a predetermined focal point (in the following embodiments, a single focal point), satisfying the requirements as an intraocular lens (the MTF curve at a spatial frequency of 50 lp / mm has one maximum value in the range of defocus amount from -0.5D to 0.5D with respect to the position where the MTF is the largest as the reference (0D), and the number of minimum values is 0), while the depth of focus is expanded. Here, in the first region located at the most central position, the first refractive power is constantly imparted regardless of the distance from the axis. Therefore, unlike the case where the refractive power decreases or increases merely by being slightly away from the axis, the wearer can appropriately recognize the visual field corresponding to the first refractive power. Thus, since the amount of light not recognized by the wearer is suppressed, a good visual field is easily obtained. Also, the wearer can obtain a visual field corresponding to the range of refractive power close to the first refractive power by the light passing through the second region. Therefore, according to the technology of the present disclosure, while suppressing the amount of light not recognized by the wearer among the light passing through the lens unit, the depth of focus is appropriately expanded.

[0013] Note that the range of the defocus amount in which the above-described MTF curve has one maximum value and no minimum value can also be changed. For example, in the range of defocus amount from -1.0D to 0.5D, the MTF curve may have one maximum value and no minimum value. Also, in the range of defocus amount from -1.5D to 0.5D, the MTF curve may have one maximum value and no minimum value. In these cases, it becomes an intraocular lens in which the visual field is less likely to deteriorate even when a larger focus shift occurs.

[0014] It should be noted that the phrase "a region in which the refractive power is applied at a constant rate regardless of the distance from the axis" is used in various parts of this disclosure. This phrase does not stipulate that the refractive power must be strictly constant within the region. In other words, even if the refractive power fluctuates slightly within the region for purposes such as aberration correction, it is still 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%, and more preferably within 10%. Furthermore, the reference refractive power applied to the outer region may also be varied to some extent within the outer region for purposes such as aberration correction.

[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 both 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 the refractive power range close to the first refractive power.

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

[0017] The area of ​​each of the first and second regions is 0.6 mm². 2 The above is also acceptable. In this case, the area of ​​each of the first and second regions is sufficiently secured. As a result, both the field of view corresponding to the first refractive power and the field of view corresponding to the range of refractive powers close to the first refractive power become easier to obtain appropriately.

[0018] The area of ​​the first and second regions is 0.8 mm². 2 More preferably, 1.1 mm 2 The above is also acceptable. In these cases, the areas of the first and second regions are more appropriately allocated.

[0019] The area of ​​the second region may be larger than or equal to the area of ​​the first region. In this case, the size of the second region, where the 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 is obtained more appropriately. In other words, the depth of focus of the intraocular lens becomes more appropriately deeper.

[0020] The first refractive power applied to the first region may be a strong refractive power, which is stronger than the standard 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 intraocular lenses, aberrations are less likely to occur near the axis than in the peripheral parts of the lens. Also, the stronger the refractive power, the greater the impact of aberrations on the wearer's field of vision. Therefore, by applying a strong refractive power, which is stronger than the standard refractive power, to the central first region where aberrations are less likely to occur, the impact of aberrations on the wearer's field of vision is reduced compared to when the standard refractive power is applied to the first region.

[0021] The multiple regions may further include a third, fourth, fifth, and sixth region. The third region is an annular region adjacent to the outside of the second region. The third region is assigned 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 assigned a strong refractive power. The sixth region is an annular region adjacent to the outside of the fifth region and also 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 regions are arranged in order from the inside outwards: a region of high refractive power (region 1), a transition region (region 2), a region of standard refractive power (region 3), a transition region (region 4), a region of high refractive power (region 5), a transition region (region 6), and a region of standard refractive power (outer region). In other words, two regions of high refractive power and a region of standard refractive power between them are located 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 can easily pass through the regions of high refractive power, standard refractive power, and transition regions appropriately. As a result, an appropriate field of view can be obtained more easily, regardless of changes in the wearer's pupil size. In addition, the increase in aberrations caused by increasing the number of regions is suppressed compared to the case where there are seven or more regions inside the outer region. As will be explained in more detail later, the strong refractive power in the first region and the strong refractive power in the fifth region do not need to be exactly the same. Similarly, the reference refractive power in the third region and the reference refractive power in the outer regions do not need to be exactly the same.

[0023] The area ratio between all of the areas 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 standard refractive power to strong refractive power. As mentioned above, it is also possible to change the ±50% value. For example, the ±50% value may be changed to ±30%, etc.

[0024] The area of ​​each of the 1st, 2nd, 3rd, 4th, 5th, and 6th regions is 0.6 mm². 2 This may also be the case. In this case, the area of ​​each of the 1st to 6th 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 standard refractive power to strong refractive power. Note that, as mentioned above, "0.6mm 2 It is also possible to change the value of "greater than or equal to". For example, 0.6mm 2 The above values ​​are 0.8 mm 2 or more, or 1.1 mm2 You may change it to the above.

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

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

[0027] In a second embodiment of the intraocular lens illustrated in this disclosure, a plurality of circular or annular regions (one circular region and one or more annular regions) are arranged concentrically on the lens portion with respect to 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 lateral region. The first region is the centrally located circular region. The first region is assigned 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 assigned 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 lateral region is an annular region located outside of the fourth region. The lateral region is assigned 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 the change in the second region as the distance from the axis increases. At least a portion of the first, second, third, and fourth regions are located within a region with a radius of 1.5 mm centered on the axis of the lens. The MTF curve for light passing through the region with a radius of 1.5 mm centered on the axis of the lens at a spatial frequency of 50 lp / mm has one maximum value in the range of defocus amount -0.5D to 0.5D, with the position where the MTF is greatest as the reference (0D), and the number of minimum values ​​is 0.

[0028] In the intraocular lens illustrated in this disclosure, the first, second, third, and fourth regions are arranged sequentially from the center, thereby expanding the depth of focus while satisfying the requirements for an intraocular lens (the requirement that the MTF curve at a spatial frequency of 50 lp / mm has one maximum value in the defocus range of -0.5D to 0.5D, and the number of minimum values ​​is 0) by focusing most of the incident light on the lens portion near a predetermined focal point (a single focal point in the embodiments described later). Here, the first refractive power assigned to the first region and the third refractive power assigned to the third region are different. Furthermore, in the second and fourth regions, the refractive power changes in opposite directions as the distance from the axis increases. In addition, at least a portion of the first, second, third, and fourth regions are arranged within a region with a radius of 1.5 mm, corresponding to the radius of a human pupil in a partially constricted state. Therefore, even if the wearer's pupils constrict to some extent, the light reaching the retina passes through the first region where the first refractive power is applied, the third region where the third refractive power is applied, and the transitional regions (second and fourth regions) where the refractive power changes between the first and third refractive powers. Thus, regardless of changes in the wearer's pupil size, it becomes easier to obtain an appropriate field of view corresponding to the range from the first to the third refractive power.

[0029] Furthermore, the range of defocus amounts in which the aforementioned 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 range of defocus amounts from -1.0D to 0.5D. Also, the MTF curve may have one maximum value and no minimum value in the range of defocus amounts from -1.5D to 0.5D. In these cases, the intraocular lens will be less prone to a decrease in field of vision even when a larger focal shift occurs.

[0030] The third refractive power applied to the third region may be a reference refractive power for focusing on distant objects. The first refractive power applied to the first region may be a strong refractive power, which is stronger 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 as the distance from the axis increases. In the fourth region, the refractive power may increase from the reference refractive power of the third region as the distance from the axis increases.

[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 on the wearer's vision. Therefore, by applying a stronger refractive power than the standard refractive power to the central first region where aberrations are less likely to occur, the impact of aberrations on the wearer's vision is reduced compared to applying the standard refractive power 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"), and more preferably within ±20%. Even in this case, an appropriate field of view can be obtained regardless of changes in the wearer's pupil size. However, the closer the reference refractive power values ​​of the outer region and the third region are, the easier it is to obtain a clear field of view at distances when the wearer's pupils become somewhat smaller.

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

[0034] Multiple regions may further include a fifth and a sixth region. The fifth region is an annular region adjacent to the outside of the fourth region. A strong refractive force is applied to the fifth region. The sixth region is an annular region adjacent to the outside of the fifth region and also adjacent to the inside of the outer region. In the sixth region, the refractive force decreases from the strong refractive force of the fifth region to the standard refractive force of the outer region as the distance from the axis increases. In this case, the regions are arranged in order from the inside to the outside: a region of strong refractive force (first region), a transitional region (second region), a region of standard refractive force (third region), a transitional region (fourth region), a region of strong refractive force (fifth region), a transitional region (sixth region), and a region of standard refractive force (outer region). In other words, two regions of strong refractive force and a region of standard refractive force between them are located inside the annular outer region. Therefore, even if the wearer's pupils are not significantly dilated, light reaching the retina can more easily pass through the high refractive power region, the standard refractive power region, and the transitional region appropriately. As a result, an appropriate field of view can be obtained more easily, regardless of changes in the wearer's pupil size. In addition, the increase in aberrations caused by increasing the number of regions is suppressed compared to the case where there are seven or more regions inside the outer region.

[0035] At least a portion of the first, second, third, fourth, fifth, and sixth regions may be positioned within a region with a radius of 1.5 mm centered on the axis of the lens. In this case, even if the wearer's pupil is constricted to some extent, the light reaching the retina passes through each of the two regions of high refractive power, the region of standard refractive power between them, and the three transition regions. Therefore, regardless of changes in the wearer's pupil size, it becomes easier to obtain an appropriate field of view corresponding to the range from standard refractive power to high refractive power.

[0036] Furthermore, the values ​​of the strong refractive power applied to the first region and the strong refractive power applied 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 wearer's pupil size.

[0037] Furthermore, the refractive power value applied to the fifth region may be closer to the strong refractive power applied to the first region than to the standard refractive power value applied to the outer region. Even in this case, an appropriate field of view can be obtained regardless of changes in the wearer's pupil size.

[0038] However, it is also possible to change the configuration of the other regions when applying a strong refractive power to the first region and a standard refractive power to the third region. For example, it is possible to omit the fifth region, which is located between the fourth and sixth regions as described above. Even in this case, a field of view corresponding to the range from the standard refractive power to the strong refractive power can be obtained.

[0039] The first refractive power applied to the first region may be the reference refractive power for focusing on distant objects. The third refractive power applied 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 stronger 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 stronger 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 kept to a minimum of four. The fewer the number of regions, the easier it is to suppress the occurrence of aberrations. Therefore, by setting the number of regions formed inside the outer region to four, it becomes easier to obtain an appropriate field of view regardless of the size of the wearer's pupil while suppressing the occurrence of aberrations.

[0040] Furthermore, the value of the reference refractive power applied to the first region and the value of the reference refractive power applied 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 within ±20%).

[0041] At least a portion of the first, second, and third regions may be positioned within a region with a radius of 1.0 mm centered on the axis of the lens. As mentioned above, in bright environments, the radius of the human pupil constricts to approximately 1.0 mm or less. By positioning 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, even in very bright environments, light reaching the retina will pass through each of the first, second, and third regions. Therefore, even when the wearer's pupil becomes very small, it becomes easier to obtain an appropriate field of view corresponding to the range from standard refractive power to high refractive power.

[0042] <First Embodiment> (Schematic configuration) The intraocular lens 1 of the first embodiment will be described with reference to Figures 1 to 5. First, the schematic configuration of the intraocular lens 1 will be described with reference to Figure 1. Note that the schematic configuration of the intraocular lens 1 described below is also common to the intraocular lens of the second embodiment, which will be described later. In addition, the first and second embodiments will be described using an intraocular lens (a so-called monofocal intraocular lens) that focuses most of the incident light on the lens portion 2 near a single focal point as an example. However, the intraocular lens to which the technology in this disclosure can be applied is any intraocular lens that satisfies the requirement that the MTF curve at a spatial frequency of 50 lp / mm has one maximum value in the range of defocus amount -0.5D to 0.5D and the number of minimum values ​​is 0.Therefore, the technology in this disclosure can also be applied to various intraocular lenses other than monofocal intraocular lenses (for example, multifocal intraocular lenses, etc.).

[0043] The intraocular lens 1 comprises a lens portion (optical portion) 2 and a support portion 3. In this embodiment, the intraocular lens 1 is a so-called one-piece type intraocular lens in which the lens portion 2 and the support portion 3 are integrally molded. However, the technology illustrated in this disclosure can also be applied to intraocular lenses other than the one-piece type (for example, a three-piece type intraocular lens). Various flexible materials can be used as the material for the intraocular lens 1, such as individual materials like BA (butyl acrylate) and HEMA (hydroxyethyl methacrylate), or composite materials of acrylic acid esters and methacrylic acid esters.

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

[0045] In the intraocular lens 1 of this embodiment, the refractive power at each part of the lens portion 2 is adjusted by forming at least one of a pair of lens surfaces in the lens portion 2 into an aspherical shape. For example, in this embodiment, the refractive power at each part of the lens portion 2 is adjusted by forming the front surface (convex surface) of the lens portion 2 into an aspherical shape. However, the rear surface or both surfaces of the lens portion 2 may also be formed into an aspherical shape. For example, of the front and rear surfaces of the lens portion 2, the surface opposite to the side that is formed into an aspherical shape to achieve the refractive power arrangement described later may be formed into a toric shape to correct astigmatism. In this case, in addition to the effects of the intraocular lens 1 described in this embodiment, the effect of correcting astigmatism is also provided.

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

[0047] (Lens area) Referring to Figure 2, the details of the lens portion 2 in the intraocular lens 1 of the first embodiment will be described. As shown in Figure 2, when the lens portion 2 is viewed from a direction along the axis O (front in Figure 2), multiple circular or annular regions R1 to R6, RO are arranged concentrically on the lens portion 2 with the axis O as the center. As mentioned above, in this embodiment, the front surface (convex surface) of the lens portion 2 is formed in an aspherical shape, thereby providing multiple regions R1 to R6, RO.

[0048] The first region R1 is the circular region located at the very center of the multiple regions. The second region R2, third region R3, fourth region R4, fifth region R5, 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 in each region) Referring to Figure 3, the refractive power in each region R1 to R6, RO of the lens portion 2 of the first embodiment will be explained. In the graph shown in Figure 3, the horizontal axis represents the distance of the lens portion 2 from axis O, and the vertical axis represents the refractive power (diopter) of the lens portion 2. In this embodiment, the refractive power applied to the lens portion 2 so that the wearer can focus on distant objects is defined as the reference refractive power. In the graph, the reference refractive power is set to "0D". The stronger the applied refractive power, the closer the wearer's focus becomes to near objects.

[0050] The refractive power (first refractive power) applied to the first region R1 is set to be stronger than the reference refractive power for focusing on distant objects (hereinafter referred to as "strong refractive power"). Specifically, in this embodiment, a constant strong refractive power is applied to the first region R1 regardless of the distance from axis O.

[0051] In the second region R2, the refractive force decreases from the first refractive force as the distance from axis O increases. More specifically, the refractive force in the second region R2 decreases from the strong refractive force in the first region R1 to the third refractive force (reference refractive force) applied to the third region R3 as the distance from axis O increases. In this embodiment, the refractive force within the second region R2 decreases in proportion to the distance from axis O.

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

[0053] In the fourth region R4, the refractive force increases from the third refractive force as the distance from axis O increases. Specifically, the refractive force in the fourth region R4 increases from the reference refractive force in the third region R3 to the fifth refractive force (strong refractive force) applied to the fifth region R5 as the distance from axis O increases. In this embodiment, the refractive force within the fourth region R4 increases in proportion to the distance from axis O.

[0054] The refractive power (fifth refractive power) applied to the fifth region R5 is a strong refractive power. Specifically, in this embodiment, a constant strong refractive power is applied to the fifth region R5 regardless of its distance from axis O. Furthermore, in this embodiment, the value of the strong refractive power applied to the first region R1 and the value of the strong refractive power applied to the fifth region R5 are the same. However, the values ​​of the strong refractive power applied to the first region R1 and the fifth region R5 do not need to be exactly 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 wearer's pupil size.

[0055] In the sixth region R6, the refractive force decreases from the fifth refractive force as the distance from axis O increases. More specifically, the refractive force in the sixth region R6 decreases from the strong refractive force in the fifth region R5 to the reference refractive force applied to the outer region RO as the distance from axis O increases. In this embodiment, the refractive force in the sixth region R6 decreases in proportion to the distance from axis O.

[0056] The refractive power applied to the outer region RO is the reference refractive power. Specifically, in the outer region RO of the present embodiment, the reference refractive power is constantly applied regardless of the distance from the axis O. However, the reference refractive power applied to the outer region RO may vary within the region for the purpose of aberration correction or the like. Also, in the present embodiment, the value of the reference refractive power applied to the third region R3 and the value of the reference refractive power applied to the outer region RO are the same value. However, the values of the reference refractive power applied to each of the third region R3 and the outer region RO do not necessarily have to be exactly 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 the change in the size of the wearer's pupil.

[0057] In the present embodiment, among the plurality of regions R1 to R6 and RO, a region in which the refractive power increases or decreases as the distance from the axis O increases (that is, the second region R2, the fourth region R4, and the sixth region R6) may also be referred to as a transition region.

[0058] (Area of each region) In the present embodiment, among 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, the ratio of the areas between all the regions is within ±50%. Specifically, in the present embodiment, the lens unit 2 is designed such that the areas of the first region R1 to the sixth region R6 are the same.

[0059] Also, in the present 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 or more. Specifically, in the present embodiment, the area of each of the first region R1 to the sixth region R6 is 1.1 mm 2 or more.

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

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

[0062] As shown in Figure 4, the intraocular lens 1 of the first embodiment satisfies the requirements 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 an area with a radius of 1.5 mm (diameter of 3.0 mm) (i.e., when the wearer's pupil is constricted to some extent). These requirements include having one maximum value in the range of defocus amount -0.5D to 0.5D (specifically, -1.5D to 0.5D) and zero minimum values, with the position where the MTF is greatest at a spatial frequency of 50 lp / mm being the reference point (0D). Furthermore, the MTF value is not only high near the maximum value, but is maintained at a high value even when the amount of defocus increases or decreases to some extent. In other words, the depth of focus is appropriately expanded in the intraocular lens 1 of the first embodiment.

[0063] Furthermore, as shown in Figure 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 intraocular lens satisfies the requirement of focusing most of the incident light on the lens portion 2 near a predetermined focal point (a single focal point in this embodiment), and the depth of focus is also appropriately expanded. Moreover, the best focus position at a radius of 1.0 mm changes by only about -0.15 D compared to the best focus position at a radius of 1.5 mm. Therefore, even when the wearer's pupil becomes very small, distance vision is less likely to worsen.

[0064] Figure 5 is a graph showing the simulation results comparing the MTF curve of the intraocular lens 1 of the first embodiment with the MTF curve of the intraocular lens of the comparative example. In the intraocular lens of the comparative example, only the magnitude of the strong refractive power applied 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 differ from the intraocular lens 1 of the first embodiment. Specifically, in the intraocular lens of the comparative example, a strong refractive power of approximately 2.4D is applied to the first region R1, and a strong refractive power of approximately 2.8D is applied to the fifth region R5. In contrast, in the intraocular lens 1 of the first embodiment, a strong refractive power of 1.3D is applied to each of the first region R1 and the fifth region R5 (see Figure 3). The region through which light passes was standardized to a region with a radius of 1.5 mm (diameter 3.0 mm) centered on axis O.

[0065] As shown in Figure 5, in the comparative intraocular lens, the magnitude of the strong refractive power applied to the first region R1 and the fifth region R5 is significantly increased compared to the strong refractive power in the intraocular lens 1 of the first embodiment, resulting in the formation of distance and near focal points. In other words, the comparative intraocular lens has the properties of a multifocal intraocular lens and cannot focus most of the incident light on the lens portion 2 near a single focal point. In contrast, in the intraocular lens 1 of the first embodiment, the depth of focus is appropriately expanded while maintaining the function of focusing most of the incident light on the lens portion 2 near a single focal point by appropriately adjusting the values ​​of the strong refractive power applied to the first region R1 and the fifth region R5. Note that the peak appearing between the distance and near focal points in the comparative graph is not an intermediate focal point, but a peak that appears due to a phenomenon called false resolution.

[0066] (Suppression of light loss) As shown in Figure 3, the first region R1 is given a constant first refractive power (strong refractive power in this embodiment) regardless of its distance from axis O. Therefore, unlike cases where the refractive power decreases or increases with even a slight distance from axis O, the wearer can appropriately perceive the field of view corresponding to the first refractive power. Thus, since the amount of light that is not perceived by the wearer is suppressed, a good field of view is more easily obtained. Furthermore, the wearer can also obtain a field of view corresponding to a refractive power range close to the first refractive power by the light that has passed through the second region R2. Therefore, according to the technology of this disclosure, the depth of field is appropriately expanded while suppressing the amount of light that is not perceived by the wearer from the light that has passed through the lens portion 2.

[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. Furthermore, in the first embodiment, the areas of the first region R1 and the second region R2 are 0.6 mm². 2 As a result, the areas of the first region R1 and the second region R2 are sufficiently secured. Therefore, it becomes easier to obtain both the field of view corresponding to the first refractive power and the field of view corresponding to the refractive power range close to the first refractive power.

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

[0069] As shown in Figure 3, in the intraocular lens 1 of the first embodiment, a strong refractive power is applied to the first region R1. 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 an intraocular lens, aberrations are less likely to occur near the axis O than in the peripheral part of the lens portion 2. Also, the stronger the refractive power, the greater the impact of aberrations on the wearer's field of vision. Therefore, by applying 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 on the wearer's field of vision is reduced compared to when the reference refractive power is applied to the first region R1.

[0070] As shown in Figures 2 and 3, in the first embodiment, the regions are arranged in order from the inside outwards: a region of high refractive power (first region R1), a transition region (second region R2), a region of standard refractive power (third region R3), a transition region (fourth region R4), a region of high refractive power (fifth region R5), a transition region (sixth region R6), and a region of standard refractive power (outer region RO). In other words, two regions of high refractive power and a region of standard refractive power between them are located inside the annular outer region RO. Therefore, even when the pupil is smaller than the outer region RO, light reaching the retina can easily pass through the regions of high refractive power, standard refractive power, and transition regions appropriately. As a result, an appropriate field of view is more easily obtained. In addition, the increase in aberration due to increasing the number of regions is suppressed compared to the case where there are seven or more regions inside the outer region RO. Furthermore, in the fifth region R5, just like in the first region R1, a constant strong refractive power is applied regardless of the distance from axis O. Therefore, a field of view corresponding to the strong refractive power is appropriately obtained. In other words, the amount of light that is not perceived by the wearer is appropriately suppressed.

[0071] The area ratios between all regions R1, R2, R3, R4, R5, and R6 are within ±50%. As a result, the area of ​​each of the regions R1 to R6 is sufficiently secured. Furthermore, in the first embodiment, the area of ​​each of the regions R3, R4, R5, and R6 is 0.6 mm². 2 As a result, sufficient area is secured in each region. 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 standard refractive power to high refractive power.

[0072] As shown in Figure 3, in the transition region (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 axis O. Therefore, compared to cases where the refractive power is not proportional to the distance from axis O, the possibility of some values ​​deviating significantly from the desired value appearing is reduced. Thus, the design of the lens portion 2 is also simplified. In addition to the second region R2, the sizes of the fourth region R4 and the sixth region R6 are also 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 field of view corresponding to the refractive power is obtained more appropriately between the standard refractive power and the strong refractive power.

[0073] (Measures to address changes in pupil size) As shown in Figure 3, in the second region R2 and the fourth region R4, the refractive power changes in opposite directions as the distance from 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 (in this embodiment, all of the fourth region R4) are located within a region with a radius of 1.5 mm, corresponding to the radius of a human pupil in a partially constricted state. Therefore, even when the wearer's pupil is partially constricted, the light reaching the retina passes through the first region R1, where the first refractive power is applied, the third region R3, where the third refractive power is applied, and the transitional regions (second region R2 and fourth region R4) that change between the first and third refractive powers. Thus, regardless of changes in the size of the wearer's pupil, it becomes easier to obtain an appropriate field of view corresponding to the range from the first to the third refractive power.

[0074] In detail, in the first embodiment, the first refractive power applied to the first region R1 is a strong refractive power, and the third refractive power applied to the third region R3 is a standard refractive power. As mentioned above, by applying a strong refractive power, which is stronger than the standard refractive power, to the central first region R1 where aberrations are less likely to occur, the impact of aberrations on the wearer's field of vision is reduced compared to the case where the standard refractive power is applied to the first region R1.

[0075] As shown in Figures 2 and 3, in the first embodiment, the first region R1, the second region R2, and a portion 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 portion 2. In bright environments, the radius of the human pupil constricts to approximately 1.0 mm or less. By arranging at least a portion 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, even in very bright environments, light reaching the retina passes through each of the first region R1, the second region R2, and the third region R3. Therefore, even when the wearer's pupil becomes very small, it becomes easier to obtain an appropriate field of view corresponding to the range from standard refractive power to high refractive power.

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

[0077] It is also possible to change the configuration of the third region R3 to the sixth region R6. For example, the third region R3 to the sixth region R6 may also be given a reference refractive power, similar to the outer region RO. Even in this case, a good field of view can be obtained with light loss suppressed by the first region R1 and the second region R2. Furthermore, it is 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 the range from the reference refractive power to the strong refractive power can be obtained.

[0078] <Second Embodiment> Referring to Figure 6, the intraocular lens of the second embodiment will be described. The intraocular lens of the second embodiment and the intraocular lens 1 of the first embodiment differ only in the arrangement of multiple regions in the lens portion 2 and the refractive power in each region; other configurations are common. Therefore, the configuration of the intraocular lens of the second embodiment that is common with the intraocular lens 1 of the first embodiment will be omitted or simplified in the description. The intraocular lens of the second embodiment, like the first embodiment, also satisfies the requirements of an intraocular lens that focuses most of the incident light on the lens portion 2 near a predetermined focal point (a single focal point in the embodiment described later) (the requirement that the MTF curve at a spatial frequency of 50 lp / mm has one maximum value in the range of defocus amount -0.5D to 0.5D, and the number of minimum values ​​is 0).

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

[0080] The first region R1 is the circular region located at the very 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 in each region) The refractive power in each region R1 to R4 and RO of the lens portion 2 of the second embodiment will be explained. In the graph shown in Figure 6, similar to the graph shown in Figure 3, the horizontal axis represents the distance of the lens portion 2 from axis O, and the vertical axis represents the refractive power (diopter) of the lens portion 2.

[0082] The refractive force (first refractive force) applied to the first region R1 is defined as the reference refractive force. Specifically, in this embodiment, the first region R1 is given a constant reference refractive force regardless of its distance from axis O.

[0083] In the second region R2, the refractive force increases from the first refractive force as the distance from axis O increases. Specifically, the refractive force in the second region R2 increases from the reference refractive force in the first region R1 to the third refractive force (strong refractive force) applied to the third region R3 as the distance from axis O increases. In this embodiment, the refractive force within the second region R2 increases in proportion to the distance from axis O.

[0084] The refractive force (third refractive force) applied to the third region R3 is a strong refractive force that is stronger than the reference refractive force. Specifically, in this embodiment, a constant strong refractive force is applied to the third region R3 regardless of the distance from axis O.

[0085] In the fourth region R4, the refractive force decreases from the third refractive force as the distance from axis O increases. More specifically, the refractive force in the fourth region R4 decreases from the strong refractive force of the third region R3 to the reference refractive force applied to the outer region RO as the distance from axis O increases. In this embodiment, a portion of the fourth region R4 includes a region where the refractive force is constant regardless of the distance from axis O (hereinafter referred to as the "constant region"). However, the fourth region R4 does not necessarily have to include a constant region. In the fourth region R4 of the second embodiment, in regions other than the constant region, the refractive force decreases in proportion to the distance from axis O.

[0086] The refractive power applied to the outer region RO is the reference refractive power. Specifically, in this embodiment, the reference refractive power is applied to the outer region RO at a constant rate, regardless of the distance from axis O. However, the reference refractive power applied to the outer region RO may vary within the region for purposes such as aberration correction. Also, in this embodiment, the value of the reference refractive power applied to the first region R1 and the value of the reference refractive power applied to the outer region RO are the same. However, the values ​​of the reference refractive power applied to the first region R1 and the outer region RO do not need to be exactly 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 field of view can be obtained regardless of changes in the size of the wearer's pupil.

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

[0088] Furthermore, 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 mm². 2 The above is the case. In detail, in this embodiment, the area of ​​each of the first region R1 to the fourth region R4 is 1.1 mm². 2 That's all.

[0089] (Suppression of light loss) As shown in Figure 6, the first region R1 is given a constant first refractive power (reference refractive power in the second embodiment) regardless of its distance from axis O. Therefore, unlike cases where the refractive power decreases or increases with even a slight distance from axis O, the wearer can properly perceive 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). Thus, since the amount of light that is not perceived by the wearer is suppressed, a good field of view is more easily obtained. Furthermore, the wearer can also obtain a field of view corresponding to a refractive power range close to the first refractive power by using light that has passed through the second region R2. Therefore, according to the technology of this disclosure, the depth of field is appropriately expanded while suppressing the amount of light that is not perceived by the wearer from the light that has passed 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. Furthermore, in the first embodiment, the areas of the first region R1 and the second region R2 are 0.6 mm². 2 As a result, the areas of the first region R1 and the second region R2 are sufficiently secured. Therefore, it becomes easier to obtain both the field of view corresponding to the first refractive power and the field of view corresponding to the refractive power range close to the first refractive power.

[0091] The areas of the second region R2 and the fourth region R4 are 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 axis O, are appropriately ensured. Therefore, a field of view corresponding to a refractive power close to the first refractive power is obtained more appropriately. In other words, the depth of focus of the intraocular lens 1 is more appropriately expanded.

[0092] In the second embodiment, the areas of the third region R3 and the fourth region R4 are also 0.6 mm². 2 As a result, sufficient area is secured in each region. 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 standard refractive power to high refractive power.

[0093] (Measures to address 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 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 are located within a 1.5 mm radius region, corresponding to the radius of a human pupil in a partially constricted state. Therefore, even when the wearer's pupil is partially constricted, the light reaching the retina passes through the first region R1, where the first refractive power is applied, the third region R3, where the third refractive power is applied, and the transitional regions (second region R2 and fourth region R4) that change between the first and third refractive powers. Thus, regardless of changes in the wearer's pupil size, it becomes easier to obtain an appropriate field of view corresponding to the range from the first to the third refractive power.

[0094] In detail, in the second embodiment, the first refractive power applied to the first region R1 is the reference refractive power, and the third refractive power applied to the third region R3 is the strong refractive power. In this case, the number of regions formed inside the outer region RO is kept to a minimum of four. The fewer the number of regions, the easier it is to suppress the occurrence of aberrations. 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 occurrence of aberrations.

[0095] In the second embodiment, the first region R1, the second region R2, and a portion 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 portion 2. As mentioned above, in bright environments, the radius of the human pupil constricts to approximately 1.0 mm or less. By arranging at least a portion 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, even in very bright environments, the light reaching the retina passes through each of the first region R1, the second region R2, and the third region R3. Therefore, even when the wearer's pupil becomes very small, it becomes easier to obtain an appropriate field of view corresponding to the range from standard refractive power to high refractive power.

[0096] The technologies disclosed in the above embodiments are merely examples. Therefore, it is possible to modify the technologies exemplified in the above embodiments. For example, it is possible to adopt only some of the technologies exemplified in the first and second embodiments in the intraocular lens. [Explanation of Symbols]

[0097] 1. Intraocular lens 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. It is an intraocular lens, Multiple circular or annular regions are arranged concentrically around the axis of the lens portion. The aforementioned multiple regions are, A circular first region is located at the very center and is given a first refractive power, which is a strong refractive power stronger than the reference refractive power for focusing on distant objects, A second annular region adjacent to the outside of the first region, A third annular region adjacent to the outside of the second region, to which the third refractive force, which is the reference refractive force, is applied, A ring-shaped fourth region adjacent to the outside of the third region, An outer region which is an annular region located outside the fourth region and to which the reference refractive power is applied, Includes, In the second region, as the distance from the axis increases, the refractive power decreases from the first refractive power, which is the strong refractive power in the first region, to the third refractive power, which is the reference refractive power in the third region. In the fourth region, as the distance from the axis increases, the refractive power increases from the reference refractive power in the third region, and thus changes in the opposite direction to the change in the second region. At least a portion of the first region, the second region, the third region, and the fourth region is arranged within a region with a radius of 1.5 mm centered on the axis of the lens portion. An intraocular lens characterized in that the MTF curve for light passing through a region with a radius of 1.5 mm centered on the axis of the lens portion, at a spatial frequency of 50 lb / mm, has one maximum value in the range of defocus amount -0.5 D to 0.5 D, and the number of minimum values ​​is 0.

2. An intraocular lens according to claim 1, An intraocular lens characterized in that at least a portion of the first region, the second region, and the third region are arranged within a region with a radius of 1.0 mm centered on the axis of the lens portion.

3. An intraocular lens according to claim 1 or 2, The aforementioned multiple regions are, Adjacent to the outside of the fourth region is an annular fifth region to which the strong refractive force is applied, A sixth annular region adjacent to the outside of the fifth region and adjacent to the inside of the outer region, It further includes, In the sixth region, the refractive power decreases from the strong refractive power in the fifth region to the reference refractive power in the outer region as the distance from the axis increases.

Images