WO2012070313A1

WO2012070313A1 - Multifocal eye lens

Info

Publication number: WO2012070313A1
Application number: PCT/JP2011/072763
Authority: WO
Inventors: 金井　守康; 飯塚　隆之
Original assignee: Hoya株式会社
Priority date: 2010-11-24
Filing date: 2011-10-03
Publication date: 2012-05-31
Also published as: JP2014032212A

Abstract

This multifocal eye lens has, on at least one surface thereof: a diffractive surface structure formed at the center section, which includes the light axis; and a refractive surface structure formed at the peripheral section surrounding the center section. The diffractive surface structure is furnished with a diffractive effect that splits an incoming light beam and focuses the beam at each of a distance vision focal point and a near vision focal point. The refractive surface structure is configured from a plurality of refractive surface regions having different curvatures. The plurality of refractive surface regions have an annular shape surrounding the center section. The center-most refractive surface regions are furnished with a distance dioptric power that focuses the incoming light beam to the distance vision focal point.

Description

Multifocal ophthalmic lens

The present invention relates to a bifocal ophthalmic lens that is prescribed for the eyes.

For the purpose of treating cataracts, surgery that removes the turbid lens and inserts an intraocular lens (Intraocular Lens, IOL) has become widespread. In this type of surgery, a multifocal intraocular lens is inserted to compensate for the adjustment power lost by removing the lens. Multifocal intraocular lenses include a refractive type with a distance or near power assigned to each area, and a diffractive structure type that distributes the power to the distance and the near power. Vision, near vision). In other words, the multifocal intraocular lens is designed to ensure visual acuity at both the far and near focusing points so that the lens wearer can send his / her daily life without glasses. Specific configuration examples of this type of multifocal intraocular lens include, for example, Japanese Patent Publication JP3195386B (hereinafter referred to as Patent Document 1), US Patent Application Publication No. US2006 / 0098163A (hereinafter referred to as Patent Document 2), Japanese Patent Application. This is described in Japanese Unexamined Patent Publication JP2008-43752A (hereinafter referred to as Patent Document 3).

Patent Document 1 describes a refractive multifocal lens in which a lens surface is divided into at least five optical zones. This type of refractive multifocal intraocular lens has a problem that the appearance of near vision mainly varies greatly depending on the pupil diameter of the lens wearer. For example, consider a case where a wearer of a refractive multifocal intraocular lens described in Patent Document 1 is outdoors in fine weather. In this case, it is considered that the pupil diameter of the lens wearer is narrowed and the luminous flux incident on the intraocular lens is limited to a part of the second zone at the maximum. Since the lens wearer can mainly use only the optical zone for far vision, it is difficult to perform near vision.

Patent Document 2 describes a diffractive structure type multifocal intraocular lens in which a blaze type diffractive structure is formed on the entire surface of one side of a lens. The diffractive structure type multifocal intraocular lens does not have a problem that the appearance of near vision or far vision changes depending on the pupil diameter. However, the diffractive structure type multifocal intraocular lens has a problem that the contrast is lowered. For example, the diffractive structure type multifocal intraocular lens described in Patent Document 2 uses about 80% of the incident light amount by distributing it to the distant power and the near power. However, the remaining about 20% becomes noise (flare) that spreads over a wide range of the field of view and lowers the contrast. In particular, when there is a bright light source such as a streetlight or car headlight in the dark when viewing at night, etc., the flare of the light source spreads over the entire field of view, and the entire field of view such as whiteout is completely white and invisible There is a risk of becoming.

Patent Document 3 describes a diffractive structure type multifocal intraocular lens in which an apodized diffractive structure is formed at the center of one surface of a lens and no diffractive structure is provided around the diffractive structure. In the diffractive structure type multifocal intraocular lens described in Patent Document 3, it is difficult to view near when the pupil diameter is reduced as in the refractive multifocal lens described in Patent Document 1. Does not occur due to the presence of the diffractive structure at the center of the lens. However, there is a problem that near vision becomes difficult at night when the pupil diameter increases. That is, the periphery of the diffractive structure at the center of one side of the lens has a simple refractive surface shape and has only a far power. For this reason, the occurrence of flare in dark vision is suppressed, and far vision is good at night when the pupil diameter is large. However, near vision has a shortage of light, resulting in a large reduction in visual acuity.

In order to solve the above-mentioned problem assumed in Patent Document 3, the present inventor has a refraction having two zones (far power and near power) having different curvatures around the diffractive structure formed at the center of the lens. The idea was to form a mold structure. Hereinafter, for convenience of explanation, an intraocular lens in which a refractive structure is formed around the diffractive structure is referred to as a hybrid multifocal intraocular lens. The hybrid multifocal intraocular lens is considered to maintain a good field of view with a sufficient amount of light in both far vision and near vision at night when the pupil diameter increases.

However, in the hybrid type multifocal intraocular lens, there is a possibility that the advantages of both cannot be fully utilized unless the distribution of the diffractive structure and the refractive structure is appropriately set. For example, if the distribution of the diffractive structures is too large, noise that spreads over a wide range of the visual field cannot be sufficiently suppressed, and there is a risk of hindering walking at night or driving a car. The maximum pupil diameter in scotopic vision generally decreases with age. For example, it is said that the maximum pupil diameter is about φ4 mm in the 60s and only about φ3 mm in the 70s. Therefore, when the distribution of the refractive structure is too large, there is a possibility that multi-focalization is insufficient particularly in elderly people, and near vision becomes difficult.

The present invention has been made in view of the above circumstances, and the object of the present invention is a hybrid type suitable for prescription even for middle-aged people with a relatively large maximum pupil diameter and elderly people with a small maximum pupil diameter. It is to provide a multifocal ophthalmic lens. The present invention can be applied not only to intraocular lenses but also to other types of ophthalmic lenses such as contact lenses. Therefore, in the above, it is described as a multifocal “ophthalmic” lens.

A multifocal ophthalmic lens according to an embodiment of the present invention that solves the above problems includes a diffractive surface structure formed in a central portion including an optical axis, and a refractive surface structure formed in a peripheral portion surrounding the central portion. At least on one side. The diffractive surface structure divides an incident light beam and focuses it on a far vision side condensing point and a near vision side condensing point, respectively. The refractive surface structure has a plurality of refractive surface regions having different curvatures. The plurality of refracting surface regions have an annular shape surrounding the central portion. The farthest refractive surface area is provided with a distance power for condensing the incident light beam at the far vision side condensing point.

According to the multifocal ophthalmic lens according to the present invention, the amount of light is ensured in a well-balanced distance and near vision even at an intermediate or large pupil diameter, which is suitable for prescription for middle to old cataract patients and the like. It is.

In the multifocal ophthalmic lens according to the present invention, the distance between the boundary between the central portion and the peripheral portion and the optical axis is set in order to achieve multifocalization more reliably regardless of the pupil diameter and to suppress the decrease in contrast due to flare. When defined as a and the effective radius defined as b, the following conditional expression (1)
0.29 ≦ a / b ≦ 0.50 (1)
It is good also as composition which satisfies.

The diffractive surface structure has, for example, an annular zone having at least one step centered on the optical axis. The multifocal ophthalmic lens according to the present invention achieves multifocalization more reliably regardless of the pupil diameter, and suppresses the decrease in contrast due to flare, and the step formed on the most peripheral side of the diffractive surface structure and the light When the distance from the axis is defined as a 'and the effective radius is defined as b, the following conditional expression (2)
0.25 ≦ a ′ / b ≦ 0.47 (2)
It is good also as composition which satisfies.

In the multifocal ophthalmic lens according to the present invention, the width of each refracting surface region is set to H in order to suppress both the change in the distribution light quantity of the distance power and the distance power depending on the pupil diameter and the deterioration of the imaging performance due to the influence of diffraction. The following conditional expression (3)
0.040 ≦ H / 2b (3)
It is good also as composition which satisfies.

The multifocal ophthalmic lens according to the present invention may be configured such that the refractive surface region farther from the central portion becomes wider in order to suppress a change in the amount of distributed light between the distance power and the near power depending on the pupil diameter. Good.

The multifocal ophthalmic lens according to the present invention may have a configuration having at least three refractive surface regions. The three refracting surface regions are given, for example, the distance power, the distance power for condensing the incident light beam at the near vision side condensing point, and the distance power in order from the center side.

According to the present invention, a hybrid multifocal ophthalmic lens suitable for prescription from middle-aged to elderly is provided.

1 is a lens cross-sectional view illustrating a schematic configuration of a hybrid multifocal intraocular lens according to an embodiment (Example 1) of the present invention. 1 is a cross-sectional structural view and a top view of a first surface of a hybrid multifocal intraocular lens according to a first embodiment of the present invention. FIG. 3 is a cross-sectional structure diagram expressed by subtracting a curvature component of distant power from the cross-sectional structure shown in FIG. It is a figure which shows the light quantity distribution ratio of a distance power and a near power of the hybrid type multifocal intraocular lens of Example 1 of this invention. It is lens sectional drawing which shows schematic structure of the hybrid type multifocal intraocular lens of Example 2 of this invention. It is the cross-section figure of the 1st surface of the hybrid type multifocal intraocular lens of Example 2 of this invention, and a top view. FIG. 7 is a cross-sectional structure diagram expressed by subtracting a curvature component of a distant power from the cross-sectional structure shown in FIG. It is a figure which shows the light quantity distribution ratio of the distance power and the near power of the hybrid type multifocal intraocular lens of Example 2 of this invention. It is lens sectional drawing which shows schematic structure of the hybrid type multifocal intraocular lens of Example 3 of this invention. It is the cross-section figure of the 1st surface of the hybrid type multifocal intraocular lens of Example 3 of this invention, and a top view. FIG. 11 is a cross-sectional structure diagram expressed by subtracting a curvature component of distant power from the cross-sectional structure shown in FIG. It is a figure which shows the light quantity distribution ratio of a distance power and a near power of the hybrid type multifocal intraocular lens of Example 3 of this invention.

Hereinafter, a hybrid multifocal intraocular lens according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a lens cross-sectional view showing a schematic configuration of a hybrid multifocal intraocular lens 1 according to an embodiment of the present invention. The hybrid multifocal intraocular lens 1 has an outer diameter OD and has a rotationally symmetric shape about the optical axis AX. Examples of the material of the hybrid multifocal intraocular lens 1 include silicone, acrylic resin, and Hydroxyethyl Methacrylate (HEMA).

The hybrid multifocal intraocular lens 1 has a first surface R1 and a second surface R2. When the hybrid multifocal intraocular lens 1 is worn, the first surface R1 is located on the object side and the second surface R2 is located on the image side.

A diffractive portion DIF having a diffractive structure is formed in the central portion of the first surface R1 (a circular region centered on the optical axis AX). The diffractive portion DIF divides the incident light beam and focuses it on the far vision side condensing point and the near vision side condensing point, respectively. The diffractive structure of the diffractive portion DIF is, for example, a blazed diffractive structure having a sawtooth shape, and is represented by the following optical path difference function φ (h). The optical path difference function φ (h) is a function expressing the function of the diffractive portion DIF as a diffractive lens in the form of an additional optical path length at a height h from the optical axis, and the installation position of each annular step in the annular structure Is specified. The optical path difference function φ (h) defines second-order, fourth-order, sixth-order,... Optical path difference function coefficients as P ₂ , P ₄ , P ₆ ,. When the diffraction order that maximizes the efficiency is defined as m, it is expressed by the following equation. The hybrid multifocal intraocular lens 1 of the present embodiment uses a first-order diffraction order (m = 1) to add an addition power for near vision, and a first-order diffracted light and a far power zero-next time. It is designed to balance the diffraction efficiency of the folded light within a certain range at the e-line.
φ (h) = (P ₂ h ² + P ₄ h ⁴ + P ₆ h ⁶ + P ₈ h ⁸ + P ₁₀ h ¹⁰ + P ₁₂ h ¹² ) mλ

A refracting part REF is formed in the peripheral part of the diffractive part DIF (a region from the outermost peripheral edge of the diffractive part DIF to the outermost peripheral edge of the effective diameter of the hybrid multifocal intraocular lens 1). The refracting part REF has a plurality of annular refracting surface areas concentric with the diffractive part DIF. Each refracting surface region has a refracting surface having a different curvature, and condenses an incident light beam on one of the condensing points on the far vision side or the near vision side.

The second surface R2 is a spherical surface. The second surface R2 may be an aspherical surface for aberration correction.

When the hybrid multifocal intraocular lens 1 whose dimensions are determined and designed on the basis of the common general technical knowledge in the field at the time of filing of the present patent application is worn, the intermediate pupil diameter of about φ3 to 4 mm has the largest refractive part REF. It is considered that the object light is incident up to the inner refractive surface region (hereinafter referred to as “innermost refractive surface region” for convenience). Therefore, the hybrid multifocal intraocular lens 1 of the present embodiment gives a distant power to the innermost refractive surface area. With an intermediate pupil diameter, in addition to the light beam transmitted through the diffractive portion DIF, the light beam transmitted through the innermost refractive surface region is also condensed at the far vision side condensing point. The far-sightedness and nearsightedness are maintained well even when prescribed for elderly cataract patients with a maximum pupil diameter of about 3 to 4 mm, because the light intensity is balanced slightly more in the distance vision than in the nearsightedness. It is.

In the hybrid type multifocal intraocular lens 1, when the radius of the diffraction part DIF (the distance between the boundary between the diffraction part DIF and the refractive part REF and the optical axis AX) is defined as a and the effective radius is defined as b, Conditional expression (1)
0.29 ≦ a / b ≦ 0.50 (1)
It is good also as composition which satisfies. Alternatively, when the radius of the annular step formed on the outermost side of the diffraction part DIF (the distance between the annular step and the optical axis AX) is defined as a ′, the following conditional expression (2)
0.25 ≦ a ′ / b ≦ 0.47 (2)
It is good also as composition which satisfies. Twice the effective radius b is approximately equal to the outer diameter OD or the outermost peripheral diameter of the refracting portion REF, and is generally about 6 mm in the case of an intraocular lens.

Elderly people in their 60s are said to have a pupil diameter of only about 2 to 4 mm, and in the 70s only about 2 to 3 mm. In order to deal with such prescriptions for elderly people with small changes in pupil diameter, multifocalization is required to balance the amount of light on the far vision side and near vision side in this range and keep the change due to pupil diameter small. . When the effective radius b is 3.5 mm when the maximum pupil diameter of a general young person is 7 mm, and half of the pupil diameter φ2 to 4 mm (corresponding to a radius) is a,
1 / 3.5 <a / b <1.5 / 3.5 = 0.29 <a / b <0.43 (70s)
1 / 3.5 <a / b <2 / 3.5 = 0.29 <a / b <0.57 (60s)
Holds.

In order to achieve multifocalization more reliably with the pupil diameter of elderly people and the like, the most reliable and simple solution is to increase the diameter of the diffraction part DIF. Therefore, in recent years, when prescribing a multifocal intraocular lens in cataract surgery for elderly people, a diffractive structure type multifocal intraocular lens is often selected rather than a refractive type. However, the greater the diameter of the diffractive portion DIF, the more conspicuous the decrease in contrast due to flare. Especially in the 50-60s age group with a maximum pupil diameter of φ4-5mm, the influence of flare is not small. Therefore, the conditional expression (1) is set as described above in order to more surely achieve multifocalization with the pupil diameter of an elderly person or the like and to suppress a decrease in contrast due to flare. Conditional expression (2) merely replaces the radius a of the diffractive portion DIF in conditional expression (1) with the radius a ′ of the annular step, and the technical idea is substantially the same as conditional expression (1). .

If the upper limit of conditional expression (1) or (2) is exceeded, the decrease in contrast due to flare increases, leading to poor visibility. If the lower limit of conditional expression (1) or (2) is not reached, the area of the diffractive portion DIF is small even for a small pupil diameter, and a sufficient multifocal effect cannot be obtained.

The hybrid multifocal intraocular lens 1 has the following conditional expression (3) when the width of each refractive surface area of the refractive part REF is defined as Hn (n is a natural number of 2 or more).
0.040 ≦ Hn / 2b (3)
It is good also as composition which satisfies. In the following, for convenience of explanation, the diffractive portion DIF is defined as “first zone”, the innermost refractive surface region is defined as “second zone”, and the refractive surface region outside the innermost refractive surface region is defined from the inner refractive surface region. Also referred to as “third zone”, “fourth zone”,. In the conditional expression (3), symbols H2, H3, H4 are attached to the widths of the second zone, the third zone, the fourth zone,.

The narrower each zone width of the refracting part REF is, the more advantageous is that the change in the amount of light distributed between the far power and the near power depending on the pupil diameter becomes smaller. However, the narrower the zone width, the more the transmission frequency characteristic is converged by a specific frequency determined by the diameter of the zone, and the deterioration of the imaging performance due to the influence of diffraction increases even in the refracting surface region. Therefore, the conditional expression (3) is set as described above in order to suppress both the change in the distribution light quantity depending on the pupil diameter and the deterioration of the imaging performance due to the influence of diffraction.

If the upper limit of conditional expression (3) is exceeded, the change in the distribution light quantity depending on the pupil diameter is large. If the lower limit of conditional expression (3) is not reached, the influence of diffraction increases rapidly, and the imaging performance is significantly degraded.

By the way, the distribution light quantity ratio depending on the pupil diameter is approximately obtained by a value in which the total area of the incident light beam diameter is the denominator and the area of the distance power or near power zone inside is a numerator. (However, in the first zone, the area is multiplied by the diffraction efficiency.) In this calculation, the denominator value increases as the pupil diameter increases. Therefore, the change in the distribution light quantity ratio cannot be suppressed within a certain range unless the numerator value is increased in the outer zone. Therefore, the hybrid multifocal intraocular lens 1 may be configured such that the zone width increases toward the outer zone of the refractive part REF.

The refracting part REF may be configured to have at least three zones. For example, the near power may be given to the third zone outside the second zone to which the far power is given, and the far power may be given to the fourth zone outside the third zone.

Next, three specific numerical examples of the hybrid multifocal intraocular lens 1 described so far will be described. Each of the hybrid multifocal intraocular lenses 1 according to Examples 1 to 3 of the present invention has first to fourth zones. The second, third, and fourth zones are assigned a far power, a near power, and a far power, respectively. The second surface R2 is a spherical surface. The distant power in water is set to 20 Dptr.

A schematic lens cross-sectional view of the hybrid multifocal intraocular lens 1 of Example 1 is as shown in FIG. The specific numerical configuration of the first surface R1 of the hybrid multifocal intraocular lens 1 according to the first embodiment is as shown in Table 1.

Specific numerical configurations other than the first surface R1 of the hybrid multifocal intraocular lens 1 according to the first embodiment are as follows.
Curvature of second surface R2 = −13.24
Center thickness (optical member thickness on the optical axis AX) D = 0.70
Refractive index ne for the e-line = 1.49379
Abbe number for e-line νe = 57.69
Effective radius b = 3.0
Near power in water = 23.5 Dptr

FIGS. 2A and 2B are a cross-sectional structural view and a top view of the first surface R1 of the hybrid multifocal intraocular lens 1 of the first embodiment, respectively. In FIG. 2A, the vertical axis represents the sag amount (unit: mm), and the horizontal axis represents the lens radius (unit: mm). In FIG. 2B, the vertical axis and the horizontal axis indicate lens radii (unit: mm) orthogonal to each other. In FIG. 2B, a solid line on the first surface R1 indicates an annular step formed in the first zone, and a two-dot line on the first surface R1 indicates a boundary between the first to fourth zones.

FIG. 3 shows a cross-sectional structure diagram expressed by subtracting the curvature component of the distant power (= 20 Dptr) from the cross-sectional structure shown in FIG. The vertical axis of FIG. 3 indicates the sag amount (unit: mm), and the horizontal axis indicates the lens radius (unit: mm). In FIG. 3, a typical sawtooth shape that contributes to the near power remains in the first zone from which the curvature component of the far power is subtracted. A curve indicated by a broken line in the first zone shows a shape obtained by subtracting the curvature component of the distant power from the curvature radius R that is the base of the fine shape of the first zone. The second and fourth zones to which the far power is given are flattened because the power is subtracted. The third zone is an inclined surface indicating the addition power obtained by subtracting the far power from the near power.

FIG. 4 shows the light quantity distribution ratio between the distant power and the near power according to the lens radius of the hybrid multifocal intraocular lens 1 of the first embodiment. The vertical axis in FIG. 4 indicates the ratio of the distance power or the near power to the total light quantity (unit:%), and the horizontal axis indicates the lens diameter (unit: mm). In FIG. 4, a region where the light intensity distribution ratio of the far power and the near power is constant corresponds to the first zone. A region where the light intensity distribution ratio of the far power increases (according to another aspect, the light intensity distribution ratio of the near power decreases) corresponds to the second and fourth zones. A region where the light quantity distribution ratio of the near power increases (according to another aspect, the light quantity distribution ratio of the far power decreases) corresponds to the third zone. As shown in FIG. 4, the sum of the light intensity distribution ratios of the far power and the near power in the first zone is about 80%. The remaining 20% is mainly flare. The present applicant has found that when the light intensity distribution ratio falls below 30%, the visual acuity rapidly decreases. For this reason, the widths of the second to fourth zones are set so that the light quantity distribution ratio between the far power and the near power is almost within the range of 30 to 60%.

In addition, the description about each figure and table | surface of Example 1 is applied also to each figure and table | surface presented in the following Examples.

FIG. 5 is a lens cross-sectional view illustrating a schematic configuration of the hybrid multifocal intraocular lens 1 according to the second embodiment. The specific numerical configuration of the first surface R1 of the hybrid multifocal intraocular lens 1 of Example 2 is as shown in Table 2.

Specific numerical configurations other than the first surface R1 of the hybrid multifocal intraocular lens 1 according to the second embodiment are as follows. In the hybrid multifocal intraocular lens 1 of the second embodiment, the annular step in the first zone is provided at a narrow pitch as compared with the first embodiment and the curvature of the third zone is large, so the near power is the present. Stronger than Example 1.
Curvature of second surface R2 = −13.24
Center thickness (optical member thickness on the optical axis AX) D = 0.70
Refractive index ne for the e-line = 1.49379
Abbe number for e-line νe = 57.69
Effective radius b = 3.0
Near power in water = 24.5 Dptr

6 (a) and 6 (b) are a cross-sectional structural view and a top view of the first surface R1 of the hybrid multifocal intraocular lens 1 of the second embodiment, respectively. FIG. 7 shows a cross-sectional structure diagram expressed by subtracting the curvature component of the distant power (= 20 Dptr) from the cross-sectional structure shown in FIG. FIG. 8 shows the light quantity distribution ratio between the distant power and the near power according to the lens radius of the hybrid multifocal intraocular lens 1 of the second embodiment.

FIG. 9 is a lens cross-sectional view illustrating a schematic configuration of the hybrid multifocal intraocular lens 1 according to the third embodiment. Specific numerical configurations of the first surface R1 of the hybrid multifocal intraocular lens 1 of Example 3 are as shown in Table 3.

Specific numerical configurations other than the first surface R1 of the hybrid multifocal intraocular lens 1 according to the third embodiment are as follows. The hybrid multifocal intraocular lens 1 of Example 3 has a design that emphasizes both the suppression of flare generated in the first zone and the securing of far vision in situations where the pupil diameter is large, such as dark place vision. Yes. Specifically, the hybrid multifocal intraocular lens 1 of the third embodiment has a smaller first zone and a wider fourth zone than the first and second embodiments.
Curvature of second surface R2 = −13.24
Center thickness (optical member thickness on the optical axis AX) D = 0.70
Refractive index ne for the e-line = 1.49379
Abbe number for e-line νe = 57.69
Effective radius b = 3.0
Near power in water = 24.5 Dptr

FIGS. 10A and 10B are a cross-sectional structural view and a top view of the first surface R1 of the hybrid multifocal intraocular lens 1 of the third embodiment, respectively. FIG. 11 shows a cross-sectional structure diagram expressed by subtracting the curvature component of the distant power (= 20 Dptr) from the cross-sectional structure shown in FIG. FIG. 12 shows the light intensity distribution ratio between the distant power and the near power according to the lens radius of the hybrid multifocal intraocular lens 1 of the third embodiment.

(Summary)
As shown in FIGS. 4, 8, and 12, the hybrid multifocal intraocular lens 1 according to the first to third embodiments has a light quantity for far vision and near vision even at an intermediate pupil diameter of about φ3 to 4 mm. Appropriately secured. Therefore, the hybrid multifocal intraocular lens 1 of Examples 1 to 3 can sufficiently cope with prescription for elderly cataract patients and the like. In addition, by arranging the third zone for near vision in the vicinity of φ3 to 4 mm, the amount of light is ensured appropriately for distance vision and near vision even in dark places for middle-aged people with a relatively large maximum pupil diameter. The Furthermore, in the third embodiment, as shown in FIGS. 10 and 11, the flare caused by diffraction is suppressed to be extremely small by minimizing the first zone which is the central diffraction portion. For this reason, the contrast is particularly high when viewed in the dark.

Table 4 is a list of values calculated when the conditional expressions (1) to (3) are applied in the first to third embodiments. As shown in Table 4, the hybrid multifocal intraocular lens 1 of Examples 1 to 3 satisfies all the conditional expressions (1) to (3). Therefore, the hybrid multifocal intraocular lens 1 according to the first to third embodiments can achieve multifocalization even in an elderly person with a small intermediate pupil diameter or maximum pupil diameter, and can reduce contrast due to flare. (Effect by satisfying conditional expression (1) or (2)). In the hybrid multifocal intraocular lens 1 according to the first to third embodiments, the change in the distribution light quantity depending on the pupil diameter and the deterioration of the imaging performance due to the influence of diffraction in the refractive surface area are simultaneously suppressed (conditions) Effect by satisfying the expression (3)).

The above is the description of the embodiment of the present invention. The present invention is not limited to the above-described configuration, and various modifications can be made within the scope of the technical idea of the present invention. For example, the hybrid multifocal intraocular lens 1 of the present embodiment can also be applied to a contact lens. The contact lens has a meniscus shape, for example, and has a region corresponding to the first to fourth zones on at least one of the object side surface and the image side surface. Since the contact lens has a large outer diameter so as to be stable near the center of the cornea (for example, φ14.5 mm), the effective radius b is set to 1/4 of the outer diameter (diameter). (1) to (3) may be applied.

Claims

A diffractive surface structure formed in the center including the optical axis;
A refracting surface structure formed in a peripheral portion surrounding the central portion;
On at least one side,
The diffractive surface structure divides an incident light beam and collects it on a far vision side condensing point and a near vision side condensing point, respectively.
The refractive surface structure has a plurality of refractive surface regions having different curvatures,
The plurality of refractive surface regions have an annular shape surrounding the central portion,
The multifocal ophthalmic lens according to claim 1, wherein a distance power for condensing the incident light beam on the far vision side condensing point is given to the refractive surface region closest to the center.
When the distance between the boundary between the central portion and the peripheral portion and the optical axis is defined as a and the effective radius is defined as b, the following conditional expression (1)
0.29 ≦ a / b ≦ 0.50 (1)
The multifocal ophthalmic lens according to claim 1, wherein:
The diffractive surface structure has an annular zone having at least one step around the optical axis,
When the distance between the step formed on the most peripheral side of the diffractive surface structure and the optical axis is defined as a ′ and the effective radius is defined as b, the following conditional expression (2)
0.25 ≦ a ′ / b ≦ 0.47 (2)
The multifocal ophthalmic lens according to claim 1, wherein:
When the width of each refractive surface region is defined as H, the following conditional expression (3)
0.040 ≦ H / 2b (3)
The multifocal ophthalmic lens according to any one of claims 1 to 3, wherein:
The multifocal ophthalmic lens according to any one of claims 1 to 4, wherein a width of the refractive surface region farther from the central portion is wider.
Having at least three refractive surface regions;
The three refracting surface regions are provided with the far power, the near power for condensing the incident light flux on the near vision side condensing point, and the far power in order from the central portion side. The multifocal ophthalmic lens according to any one of claims 1 to 5.