JP2000122007A - Multifocus type ocular lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens having a lens face shape with which the visibility at a point existing at the intermediate distance between two points (far point and near point) varying in distances is advantageously assured without the impairment of the viewing clearness of these two points. SOLUTION: An intermediate area 18 set with the lens diopter between the lens diopters of a central vision correction area 14 and outer peripheral vision correction area 16 set with the lens diopters different from each other is disposed between these areas. A first migration part and second migration part having the lens diopters varying from each other are formed in this intermediate area 18. The second migration part having the lens diopter approximate to the lens diopter of the central vision correction area 14 of these first migration part and second migration part is positioned nearer the outer peripheral side (outward in a diametral direction) than the first migration part having the lens diopter approximate to the lens diopter of the outer peripheral vision correction area 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens (hereinafter referred to as an ophthalmic lens) to be worn or buried on or in an eyeball, such as a contact lens or an intraocular lens, having different powers. The present invention relates to a multifocal ophthalmic lens having a plurality of vision correction areas.

[0002]

2. Description of the Related Art Conventionally, different powers have been set in one lens as an ophthalmic lens used for supplementing visual acuity, such as presbyopia, which is applied to an inferior visual acuity adjusting ability. A multifocal ophthalmic lens having a plurality of vision correction regions has been proposed. Specifically, as a multifocal ophthalmic lens, as described in, for example, JP-A-63-95415 and JP-A-1-319729, visual acuity with different powers due to movement of the visual axis is disclosed. A visual axis moving type contact lens which uses different correction areas, and Japanese Patent Application Laid-Open Nos. Sho 59-208524 and Hei 2-217818.
As described in Japanese Patent Application Laid-Open Publication No. H10-209, there is known a simultaneous vision type contact lens or the like in which a visual acuity correction region having different powers is used at the same time to select a necessary image by brain judgment.

[0003] In both types of lenses, the visual axis moving type and the simultaneous visual type, a near vision correction area in which a lens power for near observation is set and a lens power for distant observation are set. A bifocal lens having two different power regions in a distance vision correction region, and three or more different lens power regions forming an intermediate vision correction region between the near vision correction region and the distance vision correction region. A multifocal lens provided with has been proposed.

However, a bifocal lens has only two focal points, making it difficult to obtain a clear image at an intermediate distance.
There is a problem that image jumps and the like are likely to occur, and there is also a problem that a feeling of wearing is poor due to a large step at the boundary. In addition, in the multifocal lens, since the lens power changes in multiple steps with a narrow width in the radial direction, it is difficult to secure a sufficient area in both the near vision correction area and the distance vision correction area, and In addition to the problem that it is difficult to obtain a perfect image, there is also the problem that the clarity of the image at the intermediate distance is poor and the ghost image is likely to appear due to the presence of multi-stage lens power even in the intermediate vision correction area. there were.

Japanese Patent Application Laid-Open No. Hei 5-181096 discloses that a near vision correction area, an intermediate vision correction area, and a distance vision correction area are formed such that the lens power continuously changes in the radial direction. Although a multifocal lens with improved feeling of wearing and visibility at an intermediate distance is disclosed, it is difficult to obtain sufficiently clear visibility both at the time of near observation and at the time of distant observation even with such a lens. There was a case.

[0006] Japanese Patent Application Laid-Open No. 9-26559 discloses that
A bifocal lens in which the near vision correction area and the distance vision correction area are alternately arranged in the radial direction is disclosed, but even with such a lens, the near vision correction area and the distance vision correction area are each from one zone. Like a general bifocal lens,
There is a problem that it is difficult to obtain a clear image at an intermediate distance, and image jumps and the like are likely to occur.

[0007]

Here, the present invention has been made in view of the above-mentioned circumstances, and a problem to be solved is to ensure clear visibility at the time of near and far observation. Another object of the present invention is to provide a multifocal ophthalmic lens capable of obtaining good visibility even at an intermediate distance.

[0008]

In order to solve such a problem, a feature of the present invention is to provide a multifocal ophthalmic lens having a visual acuity correction region in which different lens powers are set, wherein the visual acuity correction region is provided. A central vision correction area, an outer peripheral vision correction area having a lens power different from that of the central vision correction area, and positioned at an outer peripheral side of the central vision correction area, the central vision correction area, and the central vision correction area. The lens power between the outer peripheral vision correction regions is set and includes an intermediate region positioned between the central vision correction region and the outer peripheral vision correction region, and in the intermediate region, different lens powers are used. Forming a first transition portion and a second transition portion having a second transition portion having a lens power close to the lens power of the central vision correction region among the first transition portion and the second transition portion. , The peripheral vision correction In that the allowed positions on the outer peripheral side than the first transition portion having a lens power closer to the lens power of the frequency.

In such a multifocal ophthalmic lens having a structure according to the present invention, a fixed power distribution area is provided in each of the central vision correction area and the peripheral vision correction area, so that the central vision correction area is provided. In the peripheral vision correction area and the peripheral vision correction area, respectively, it is possible to advantageously ensure visibility at a specific distance point particularly required (generally, a near observation point and a distant observation point). A clear image can be observed at a distance point corresponding to each lens power set in the peripheral vision correction area.

Moreover, in the intermediate region, the first transition portion located on the inner peripheral side of the second transition portion is more
Since the second transition portion is formed with a lens power closer to the lens power in the outer visual acuity correction area, the lens power is positive in the radial direction from the inner visual acuity correction area toward the outer visual acuity correction area. Or the first transition portion and the second transition portion with respect to the positional relationship between the lens powers of the inner peripheral vision correction region and the outer peripheral vision correction region without being changed in only one direction on the minus side. The positional relationship of the lens power of
It is reversed in the radial direction. Thus, the clarity of the observation image near the intermediate distance where the first transition portion and the second transition portion are tuned is improved based on the optical characteristics of the intermediate region.

The present invention can be applied to various types of ophthalmic lenses including contact lenses and intraocular lenses, but is particularly advantageously applied to contact lenses.
Thereby, a presbyopic contact lens or the like can be advantageously realized. Further, as a contact lens, both a hard type and a soft type can be applied.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

A multifocal ophthalmic lens having a structure according to the present invention is formed, for example, as a contact lens 10 having a structure as shown in FIG. The contact lens 10 has a vision correction area 12 for giving a corrective vision required by a wearer at a substantially central portion of the lens. Further, in the embodiment shown in FIG. 1, the optical center axis P of the vision correction area 12 is made to coincide with the geometric center axis O relative to the lens outer shape. Accordingly, the optical center axis P can be appropriately deviated from the geometric center axis O of the lens.

For example, considering the general shape of the corneal curvature and the position of the pupil, the optical center axis of the vision correction area 12 is as follows:
It is desirable that P be deviated toward the wearer's nose in the wearing state with respect to the geometric center axis O of the lens, and it is desirable that the deviation be set to 2.0 mm or less. By setting such an amount of deviation, the optical center axis P of the vision correction area 12 can be advantageously matched with the center of the pupil of the wearer in the wearing state, and the visibility is further improved. Can be achieved. Further, as shown in FIG. 2, the optical center axis: P of the vision correction area 12 is
When deviating from the geometric center axis 0 of O, the optical center axis P is shifted downward with respect to the geometric center axis O of the lens in consideration of the living environment of the wearer. Or, by deviating upward, the optical center axis P of the vision correction area 12 can be made to coincide with the center of the pupil of the wearer with high accuracy. It should be noted that the optical center axis: P of the vision correction area 12 is not deviated horizontally from the geometric center axis: O of the contact lens 10 in the wearing state,
It is also possible to deviate only in the vertical direction, for example vertically downward.

The outer peripheral side of the vision correction area 12 does not provide optical characteristics because it is not positioned on the pupil when worn, but is formed as an outer peripheral area necessary for wearing, and is formed as necessary. Slab-off processing and the like are performed. In particular, as described above, when the optical center axis P is deviated from the geometric center axis O of the lens according to the position of the pupil of the wearer or the like, the circumferential direction of the lens under the wearing state may be changed. For the purpose of positioning, an appropriate rotation preventing mechanism is employed, but a prism ballast mechanism is particularly preferably employed. In addition, the prism ballast mechanism is to hold the contact lens in the worn state at a specific position in the circumferential direction by making the lens thickness different in the diameter direction and setting the center of gravity eccentrically with respect to the lens geometric center. Since the prism ballast mechanism itself is a known technique, a detailed description thereof will be omitted here.

As shown in the figure, the visual acuity correction area 12 is composed of a central acuity correction area 14, an outer acuity correction area 16 and an intermediate area 18 in which different lens powers are set. The central vision correction area 14, the peripheral vision correction area 16, and the intermediate area 18 are all formed with the optical center axis: P as the optical center in order to advantageously obtain a simultaneous vision type multifocal contact lens. It is desirable to form them concentrically optically. In particular, in the present embodiment, the central vision correction area 14 has a circular shape centered on the optical central axis: P, and the outer peripheral vision correction area 16
Has a concentric annular shape that is spaced outside the central vision correction area 14. Further, the intermediate region 18 has an annular shape concentrically positioned so as to fill the space between the central vision correction region 14 and the outer peripheral vision correction region 16. The central vision correction area 14, the peripheral vision correction area 16, and the intermediate area 18 do not need to have a perfect circular or annular shape, and for example, an elliptical shape, an elliptical ring shape, or the like may be appropriately adopted.

Furthermore, since the central vision correction area 14 and the peripheral vision correction area 16 are set to different lens powers, one of the vision correction areas is generally
A near vision correction area having a constant lens power sufficient to supplement the user's visual acuity for near observation throughout the radial direction is provided, and the other vision correction area is used for distant observation. Therefore, the distance vision correction area has a constant lens power sufficient to supplement the user's visual acuity adjustment power over the entire radial direction. The central vision correction area 14 and the peripheral vision correction area 16
Which of the above is to be the near vision correction area is appropriately determined in consideration of the user's requirements, living conditions, environment, and the like.

In the contact lens 10, the lens surface on the inner surface (spherical concave surface) is desirably a base curve surface corresponding to the shape of the cornea of the wearer. Generally, the lens surface on the outer surface (spherical convex surface) is preferable. By adjusting the lens surface shape, a desired lens power is provided in each of the regions 14, 16, and 18. In addition, by adjusting the lens surface shapes of both the inner surface and the outer surface, or by adjusting the inner surface lens It is also possible to tune the lens power by adjusting only the surface shape. Also,
The central vision correction area 14 and the peripheral vision correction area 16 are generally
By being formed in each spherical shape, a constant lens power is advantageously given as a whole, but in addition, for example, when astigmatism correction is required,
By combining a cylindrical lens (toric surface) on at least one of the inner and outer lens surfaces in the vision correction area 12, it is also possible to set different lens powers in different radial directions.

The intermediate area 18 includes a central vision correction area 1.
The lens power between the lens power set to 4 and the lens power set to the outer peripheral vision correction area 16 is set, but the lens power in the intermediate area 18 is not constant throughout. , In the radial direction. Moreover, as shown in various power distribution forms illustrated in FIGS. 3 to 13, the intermediate area 18 includes a first transition portion 20 and a second transition portion 22 having mutually different lens powers. Is formed, and the second transition portion 22 having a lens power close to the lens power of the central vision correction region 14 among the first transition portion 20 and the second transition portion 22 is formed in the outer peripheral vision correction region 16. It is located radially outward from the first transition portion 20 having a lens power close to the lens power. 3 to 13, the horizontal axis represents the radial distance from the optical axis, and the vertical axis represents the lens power, and the outer peripheral edge (outer periphery) of the visual acuity correction area 12 from the optical center axis of the visual acuity correction area 12. The lens power distribution up to the outer peripheral edge of the vision correction area 16 is shown. In these figures, a predetermined additional power (ADD) is added to the lens power of the distance vision correction area in the near vision correction area based on the lens power of the distance vision correction area. Are represented as

Here, the first transition portion 20 and the second transition portion 22 in the intermediate region 18 are shown in FIGS.
At least one set (one each) may be provided as illustrated in FIGS. 9, 11 to 13, but as illustrated in FIG. 10, the first transition portion 20 and the second transition portion are provided. 2
2, a plurality of sets (two sets in the lens illustrated in FIG. 10)
It is also possible to provide and arrange each set of the first transition portion 20 and the second transition portion 22 sequentially in the radial direction.
By adjusting the set number of the first transition portion 20 and the second transition portion 22 in this way, the visibility at the intermediate distance is adjusted according to the luminous intensity or the like, or each of the plurality of first transition portions is adjusted. By adjusting the lens power in the section 20 and the second transition section 22 so as to be different from each other, a point having good visibility at an intermediate distance can be narrowed down to a specific distance or scattered at a plurality of distances. It is possible to adjust the visibility of the intermediate distance point.

Also, as illustrated in FIGS. 3 to 5, 7, 10 to 13, the first transition portion 20 in the intermediate region 18 is provided.
For example, it is effective that at least one of the lens powers of the second transition section 22 is given as an extreme value.
The extreme value refers to a local maximum value or a local minimum value, and is a value that is located at the center of a minute region in the lens radial direction and becomes a local maximum or a local minimum. For example, when the lens power that changes continuously in the radial direction is expressed as a function of the radial position, the point at which the differential coefficient becomes 0 is an extreme value in the differentiable range, and the differential coefficient does not exist. In the portion, the point where the function decreases or increases in the region before and after the region becomes the extreme value. FIG.
The maximum and minimum values when the lens power continuously and gradually changed in one direction of increasing or decreasing takes the maximum value or the minimum value at the discontinuous end, as shown in FIG. The value is also included in the extreme value according to the present invention.

Alternatively, as illustrated in FIGS. 8 and 9, the first transition portion 20 and the second transition portion 22 in the intermediate region 18 may be configured such that, for example, at least one of them has a constant lens power. It is effective to give it with a structure that spreads in the radial direction. In order to sufficiently ensure the visibility at the near observation point and the far observation point, the radial dimensions of the transition portions 20 and 22 having a fixed lens power are adjusted by the central vision correction region 14 and the peripheral vision correction region 16. It is desirable to set smaller than any of the above.

As described above, in each of the transition portions 20 and 22, a lens power is given as an extreme value, a constant lens power is provided over a predetermined width in the radial direction, or a structure in which these are appropriately combined is adopted. Thereby, the visibility at the intermediate distance can be advantageously secured, and the points with good visibility at the intermediate distance can be narrowed down to a specific distance or scattered at a plurality of distances. The visibility of points can be adjusted. That is, by giving the lens power as an extreme value at the specific transition portions 20 and 22, the lens power which advantageously gives the visibility of the specific intermediate distance point at both radial portions of the transition portions 20 and 22 is effectively obtained. Transition portion 2 which can be provided and has a fixed lens power over a predetermined radial width.
By adopting 0,22, the visibility of a specific intermediate distance point is advantageously realized at the transition.
Further, as described above, in each of the transition portions 20 and 22, the lens power is given as an extreme value, a constant lens power is provided over a predetermined width in the radial direction, or a structure in which these are appropriately combined is adopted. Even when the optical center axis P of the vision correction area 12 does not exactly coincide with the center of the pupil of the wearer, it is possible to ensure a certain degree of clear visibility, and the lens is not worn when worn. It is also possible to increase the allowable amount of radial deviation.

The lens power in the intermediate area 18 is
As shown in FIGS. 3 to 5, 7, 8, 10 to 13, etc., it may be set so as to change continuously over the entire radial direction. , There may be a point where the lens power changes discontinuously at least in a part of the radial direction. In particular, it is preferable that a point where the lens power changes discontinuously is provided between the first transition portion 20 and the second transition portion 22, and more preferably, as shown in FIGS. First transition 2
The zero and the second transition 22 are radially articulated with such a discontinuously changing boundary. In addition, by continuously changing the lens power over the entire area in the radial direction, the feeling of wearing is improved, the ghost image is more advantageously reduced, and good visibility over the entire intermediate distance is obtained. There is an advantage that it is easy to obtain. In addition, if a discontinuous change point of the lens power is set, particularly excellent visibility is obtained at a specific intermediate distance corresponding to the lens power of the transition portions 20 and 22 located on both sides of the discontinuous change point. It is possible to obtain. That is, the visibility at the intermediate distance can be adjusted by appropriately adopting the continuous change and the discontinuous change of the lens power in the intermediate region 18.

Further, in the intermediate area 18 including the boundary with the central vision correction area 14 and the peripheral vision correction area 16, even when the lens power is continuously changed, the rate of change of the lens power is continuously changed. On the contrary, in the intermediate region 18, the rate of change of the lens power may be changed discontinuously at a specific position. If the rate of change of the lens power is continuously changed in the intermediate region 18, tuning or the like that ensures the visibility at all intermediate distances as a whole can be advantageously realized. On the other hand, if the rate of change of the lens power is changed discontinuously at a specific position in the intermediate region 18, tuning or the like can be made so as to particularly advantageously secure visibility at a specific distance. For example, when the lens power continuously changes in the vicinity of the first transition part 20 or the second transition part 22, the rate of change of the lens power is determined by the transition parts 20, 22.
, The transition sections 20, 22
It is also possible to obtain particularly excellent visibility at a specific intermediate distance corresponding to the lens power. Alternatively, the rate of change of the lens power is continuously reduced by gradually decreasing the rate of change of the lens power in the intermediate area 18 toward 0 at the boundary between the central vision correction area 14 and the outer peripheral vision correction area 16. Although it is possible to change the lens power, the change rate of the lens power may be suddenly set to 0 at such a boundary to make the lens power discontinuous. By making the rate of change of the lens power discontinuous at the boundary between the intermediate area 18 and the central vision correction area 14 or the peripheral vision correction area 16, the near vision by the central vision correction area 14 and the peripheral vision correction area 16 is performed. Alternatively, the clarity of distant observation can be more advantageously secured.

Further, even when the lens power in the intermediate range is continuously changed, the changing form is not limited at all, and various changing forms can be appropriately adopted according to the required optical characteristics and the like. . Specifically, for example,
As shown in FIGS. 3, 4, 7, 8, 11 to 13,
Central vision correction area 14 and its closest first transition 20
Area (the first area in the figure) and the outer peripheral vision correction area 1
6 and a region (third region in the figure) closest to the second transition portion 22 each have a radial frequency distribution represented by a second-order or higher polynomial, and A region in the intermediate region 18 in which a region between the first transition portion 20 and the second transition portion 22 (the second region in the figure) has a radial frequency distribution represented by a third-order or higher polynomial. In the case where a plurality of sets of the first and second transition portions 20 and 22 are set as shown in FIG. 10, the central vision correction area may be adopted. The area between 14 and the nearest first transition section 20 (first area in the figure)
And a region (the fifth region in the figure) between the outer peripheral vision correction region 16 and the second transition portion 22 closest thereto has a radial frequency distribution represented by a quadratic or higher polynomial. At the same time, the region between the transition portions 20 and 22 located adjacent to each other in the radial direction (the second, third, and fourth regions in the drawing) has a radial frequency distribution represented by a third-order or higher polynomial. The distribution of the lens power in the radial direction in the intermediate zone 18 can advantageously be employed. Alternatively, in FIGS. 3, 4, 7, and 11 to 13, it is possible that the power distribution in the radial direction in the intermediate region 18 adopts a lens power as represented by one fifth-order or higher polynomial. This makes it possible to continuously set the rate of change of the lens power.

The specific values of the lens powers Pb and Pc of the first and second transition portions 20 and 22 are not particularly limited, but the present invention is shown in FIGS. As described above, one of the first and second transition portions 20 and 22 includes a multifocal ophthalmic lens having the same lens power as the outer peripheral vision correction area 16 or the central vision correction area 14. At this time, in the first transition portion 20 or the second transition portion 22 in which the same lens power is set as the outer peripheral vision correction region 16 or the central vision correction region 14, the lens power is given as an extreme value. May be given as a constant value, but preferably, at both inner and outer peripheral portions of the first transition portion 20 or the second transition portion 22, the center located adjacent to the radial direction from the set lens power. The lens power change region (first, second, and third in FIGS. 11 and 12) that continuously changes to the eyesight correction area 14, the outer peripheral eyesight correction area 16, or the set lens power of the first or second transition portion 20, 22.
The second region and the second and third regions in FIG. 13) are formed. By forming such a lens power change region, ghost is more advantageously reduced, and visibility at an intermediate distance point is more advantageously secured.

Further, the first and second transition sections 20, 22
When setting the same lens power as the outer peripheral vision correction area 16 or the central vision correction area 14 for any one of
Particularly preferably, as shown in FIGS.
The same value as the lens power for near vision among the set lens powers of the central vision correction area 14 and the peripheral vision correction area 16 is given as the lens power of the first transition portion 20 or the second transition portion 22. Thereby, the visibility at the time of near observation, which tends to be insufficient by giving priority to the visibility at the time of distant observation,
It is possible to improve the visibility at the time of distant observation while sufficiently securing the visibility. In addition, for one of the first transition portion 20 and the second transition portion 22, the near diopter lens power set in the central vision correction region 14 or the peripheral vision correction region 16 is set, and On the other hand, by setting a lens power in a range between the central vision correction area 14 and the peripheral vision correction area 16 and not reaching the same as the central vision correction area 14 and the outer vision correction area 16,
The visibility at the intermediate distance point can also be advantageously secured. FIG. 11 shows a specific example of such a configuration.
, The lens power for distant observation: Pa in the central vision correction area 14 and the lens power for near observation: Pd (Pd = Pa + ADD) diopter (hereinafter, referred to as “Dptr.”) In the peripheral vision correction area 16. Are set respectively, and the central vision correction area 14 and the peripheral vision correction area 1
A set of a first transition portion 20 and a second transition portion 22 are formed in the intermediate region 18 formed between the two. And
The lens power: Pb (Dptr.) Of the first transition portion 20 positioned on the inner peripheral side is set as an extreme value having the same value as the lens power: Pd (Dptr.) Of the outer peripheral vision correction area 16. On the other hand, the lens power: Pc (Dptr.) Of the second transition portion 22 positioned on the outer peripheral side satisfies the expression: Pa <Pc <Pa + ADD / 2, and more preferably, the expression: Pa + 0. It is set so as to satisfy 25 ≦ Pc <Pa + ADD / 2.

Further, in the multifocal ophthalmic lens having the structure according to the present invention, the intermediate area 18 is set at 0.5 to 3.5 mm.
It is desirable to form with the radial dimension of. Middle area 18
If the radial width of the intermediate region 18 is smaller than 0.5 mm, it may be difficult to ensure sufficient visibility at intermediate distances.
If it is larger than 5 mm, it may be difficult to ensure sufficient visibility in the near and far regions.

Further, in the present invention, the central vision correction area 14
Any of the peripheral vision correction area 16 and the peripheral vision correction area can be set as a near vision correction area or a distance vision correction area, for example,
When the central vision correction area 14 is set to the near vision correction area and the outer peripheral vision correction area 16 is set to the distance vision correction area, FIGS. 3 to 6, 8 to 10, 12, and 13 are used. As shown, the lens power of the outer peripheral vision correction area 16 is Pd (Dp
tr.) and the additional power of the central vision correction area 14: ADD (D
ptr.), the lens power of the first transition portion 20: Pb
(Dptr.) And the lens power of the second transition portion 22: Pc (D
ptr.) is preferably designed to satisfy the following (formula I) and (formula II) or (formula I ′) and (formula II ′), respectively. Pd + 0.25 ≦ Pb <Pd + ADD / 2 (Formula I) Pd + ADD / 2 ≦ Pc ≦ Pd + ADD (Formula II) Pd ≦ Pb <Pd + ADD / 2 (Formula I ′) Pd + ADD / 2 ≦ Pc ≦ Pd + ADD−0.25 (Formula II ′)

In the multifocal ophthalmic lens having the structure according to the present invention, the first transition portion 20 and the second transition portion 22 are provided.
Over the entire intermediate area including the central vision correction area 14 and the peripheral vision correction area 16 and between the central vision correction areas 14
It is also possible to set a lens power within a range that does not reach the same as the outer peripheral vision correction area 16, and this is effective, for example, when it is necessary to advantageously ensure visibility at a specific intermediate distance point. Then, when such a setting of the lens power is adopted, as shown in FIGS. 3 to 10, the lens power of the outer peripheral vision correction area 16: Pd
(Dptr.) And additional power of central vision correction area 14: AD
For D (Dptr.), The lens power of the first transition section 20:
Pb (Dptr.) And the lens power of the second transition portion 22: P
It is particularly desirable to design c (Dptr.) such that each satisfies the following equation, whereby visibility at intermediate distances can be more advantageously ensured. Pd + 0.25 ≦ Pb <Pd + ADD / 2 Pd + ADD / 2 ≦ Pc ≦ Pd + ADD−0.25

Regardless of which of the central vision correction area 14 and the peripheral vision correction area 16 is set as the near vision correction area and the distance vision correction area, in the present invention, for example, FIG.
4, 5, 7, 8, 11-13, a first transition 20 and a second transition 22
Is provided, and the intermediate region 18 is positioned adjacent to the outer peripheral side of the central vision correction region 14 so that the central vision correction region 14
A first region in which the lens power gradually and continuously changes in the radial direction from the lens power of the first transition portion 20 to the lens power of the first transition portion 20; and the first region adjacent to the outer peripheral side of the first region. A second region in which the lens power gradually and continuously changes in the radial direction from the lens power of the transition portion 20 to the lens power of the second transition portion 22, and a second region adjacent to the outer peripheral side of the second region. The outer visual acuity region 16 is determined from the lens power of the second transition portion 22.
The distribution form of the lens power, which is constituted by the third region in which the lens power gradually and continuously changes in the radial direction up to the lens power, can be advantageously adopted.

3 to 5, 7, 11 to 13
As shown in FIG. 3, setting the first transition portion 20 and the second transition portion 22 as extreme values can further reduce ghost images and improve visibility in a wide range of intermediate distances. It is effective for further improvement. In addition, FIGS.
As shown in 0, 12 to 13, the central vision correction area 14 is set to the near vision correction area, and the change rate of the lens power is discontinuous at the boundary between the central vision correction area 14 and the intermediate area 18. In this case, since the lens power close to the lens power for distant vision correction is set near the center of the vision correction area 12, the pupil is used for near vision mainly using the central vision correction area 14. The incident light to the light is optically advantageously condensed, and the visibility in near vision can be further improved.

In the present invention, preferably, as shown in FIG. 4, for example, the lens power of the central vision correction area 14 is Pa, and the lens power of the first transition portion 20 in the intermediate area 18 is Pb. The lens power of the second transition portion 22 in the intermediate region 18 is Pc, the lens power of the outer peripheral vision correction region 16 is Pd, and the optical center axis of the central vision correction region 14 (in this embodiment, the visual correction region). 12 optical central axes:
Wa is the radial distance from P) to the boundary between the central vision correction area 14 and the intermediate area 18, Wb is the radial distance from the optical center axis of the central vision correction area 14 to the first transition portion 20, and W is the central vision correction. The radial distance from the optical center axis of the zone 14 to the second transition portion 22 is Wc, and the radial distance from the optical center axis of the central vision correction zone 14 to the boundary between the intermediate zone 18 and the peripheral vision correction zone 16 is Wd. Then, assuming that a radial distance from the optical center axis of the central visual acuity correction area 14 is x, the lens power: y in each of the first, second, and third regions is a function of the radial distance: x, It is set as follows.

That is, first, in the first area,
The optical power of the visual acuity correction area 12 is equal to the lens power of the central visual acuity correction area 14 at a distance Wa from the optical center axis P: Pa, and the lens power is Pa. , The differential equation y ′ of the lens power y in the first area is expressed as the following equation. y ′ = (x−Wa) (x−Wb) Therefore, using the coefficients: E1 and F1, the lens power: y
Is represented by the following equation. to ^{y = E1 (x 3/3} -x 2 (Wa + Wb) / 2 + x · Wa · Wb) + F1 this equation, x = Wa, and y = Pa, x = Wb, y = Pb
Respectively, the following (Equation 1) and (Equation 2) are obtained. Pa = E1 (Wa 3/3 -Wa 2 (Wa + Wb) / 2 + Wa · Wa · Wb) + F1 ··· ( Equation ^{1) Pb = E1 (Wb 3} /3-Wb 2 (Wa + Wb) / 2 + Wb · Wa · Wb) + F1 (Equation 2) Thus, when (Equation 2) is subtracted from (Equation 1) to delete F1 and obtain E1, E1 = (Pa−Pb) / ((Wa ³ −Wb ³ ) / 3-
(Wa ² −Wb ² ) (Wa + Wb) / 2 + (Wa−W
b) Wa · Wb) F1 = Pa−E1 (Wa ³ / 3−Wa ² (Wa + Wb)
/ 2 + Wa · Wa · Wb).

Similarly, in the second area and the third area, the lens power: y is expressed by the following equation. (Second ^{region) y = E2 (x 3/} 3-x 2 (Wb + Wc) / 2 + x · W
b · Wc) + F2 where E2 = (Pb−Pc) / ((Wb ³ −Wc ³ ) / 3−
(Wb ² −Wc ² ) (Wb + Wc) / 2 + (Wb−W
c) Wb · Wc) F2 = Pb−E2 (Wb ³ / 3−Wb ² (Wb + Wc)
/ 2 + Wb · Wb · Wc) (third area) y = E3 (x ³ −3−x ² (Wc + Wd) / 2 + x · W
c · Wd) + F3 where E3 = (Pc−Pd) / ((Wc ³ −Wd ³ ) / 3−
(Wc ² −Wd ² ) (Wc + Wd) / 2 + (Wc−W
d) Wc · Wd) F3 = Pc−E3 (Wc ³ / 3−Wc ² (Wc + Wd)
/ 2 + Wc ・ Wc ・ Wd)

When the lens power: y represented by the above equations is set for each of the first to third regions, the lens power of the first region is particularly set to the value of 3 above. Instead of the following equation, a setting can be made as represented by the following quartic equation. That is, when the rate of change of lens power A in the first region is expressed by a quartic equation, for example, the following equation is obtained. A = (Pa−Pb) / (Wa−Wb) ⁴ Therefore, in the first area, the lens power at the point of x: the distance from the optical center axis: P of the vision correction area 12: y
Can be expressed as the following equation. y = (Pa−Pb) (x−Wb) ⁴ / (Wa−Wb) ⁴
+ Pb Then, the central vision correction area 14 is set as the near vision correction area, the outer peripheral vision correction area 16 is set as the distance vision correction area, and such a lens power is set for the first area. This makes it possible to improve the light-collecting effect on the central vision correction area 14 and improve the clarity at the time of near-field observation.

For example, as shown in FIG. 7, when the central vision correction area 14 is set to the distance vision correction area and the outer peripheral vision correction area 16 is set to the near vision correction area. As described above, the setting of the lens power y in the first, second, and third transition regions can be advantageously employed.
Further, in this case, similarly to the case where the central vision correction area 14 is set to the near vision correction area, the first transition section 20 and the second transition section 22 are set as extreme values, or the central vision correction area is set. Any setting that changes the rate of change of the lens power discontinuously at the boundary between the intermediate region 14 and the intermediate region 18 and the boundary between the intermediate region 18 and the outer peripheral vision correction region 16 can be appropriately adopted as needed.

In addition, as described above, only one set of the first and second transition sections is set, and the first, second, and third transition areas are set in the first and second transition sections. The present invention can also be advantageously employed when any one of the lens powers is set to the same value as the lens power of the outer peripheral vision correction area 16 or the central vision correction area 14. Thereby, the effect of suppressing the ghost is improved, and the visibility at the intermediate distance point can be more effectively secured.

Although the embodiments of the present invention have been described in detail above, these are merely examples, and the present invention
The specific description in such an embodiment should not be construed as limiting in any way.

For example, it should be understood that the present invention is applicable to various ophthalmic lenses, regardless of the use or material of the lens. More specifically, the present invention can be applied to both a hard type and a soft type in a contact lens.
Non-gas permeable materials such as MA and gas permeable materials (RG
P), and can be applied to both hydrous and non-hydrous types as a soft type. Further, it is needless to say that the present invention can be applied to an intraocular lens and the like.

The method of manufacturing the ophthalmic lens having the structure according to the present invention is not limited at all. Specifically, for example, by cutting from the lens blank,
A method of shaving a target lens, and cutting and forming any of the inner and outer surfaces of the lens, and a method of molding a lens of a target shape using a mold having a forming surface that provides the target lens inner and outer surfaces, Alternatively, only one lens surface is molded, and the other lens surface is cut and formed.Moreover, after a rough lens surface shape is given by molding, the surface layer is cut to form the final lens surface. Any method of obtaining a lens surface shape can be advantageously employed. In particular, according to the cutting process, a highly accurate lens surface shape can be stably obtained, and according to the mold forming,
It is possible to obtain good lens production efficiency,
By combining such cutting and molding, it is also possible to achieve both accuracy and production efficiency.

Further, in the above description, the simultaneous vision type contact lens has been described. However, the multifocal ophthalmic lens having the structure according to the present invention has a geometric center with respect to the optical center axis of each vision correction area and the lens outer shape. By appropriately setting the size of the amount of deviation from the axis, the size of each visual acuity correction area, and the like, the present invention can be advantageously applied to an ophthalmic lens of a visual axis moving type.

FIG. 14 shows a contact lens 30 as a specific example in which the present invention is applied to a visual axis moving type ophthalmic lens. In such a contact lens 30, the central vision correction area 14 is a near vision correction area, the outer peripheral vision correction area 16 is a far vision correction area, and the central vision correction area 14 and the outer vision correction area are used. The optical center axis P of the vision correction area 12 including the area 16 is set to be deviated downward with respect to the geometric center axis O of the lens outer shape. In FIG. 14, L is a horizontal line at the time of wearing that passes through the geometric center axis O of the lens outer shape, and M is
It is a vertical line.

In the contact lens 30 having such a structure, when the wearer shifts his / her gaze downward during reading or the like, a wide portion on the pupil is covered with the central vision correction area 14, and the central vision correction area is provided. With the lens power of 14, near vision correction is effectively performed, and the visibility of the near point can be ensured. On the other hand, when the wearer moves his / her gaze upward from the center when driving a car or the like, a wide part on the pupil is covered with the outer peripheral vision correction area 16 and the outer peripheral vision correction area 16
The distance vision correction is effectively performed by the lens power, and the visual clarity of the far point is ensured.

In the contact lens 30, the optical center axis of the visual acuity correction area 12: the geometric center axis of the lens outer shape of P: the amount of deviation vertically downward with respect to O: e
Is desirably set to e ≦ 7.0 mm. Thereby, under general living conditions, near vision and far vision can both be advantageously secured. In addition, in the contact lens 30, in consideration of a lens position shift at the time of wearing and the like, preferably, as shown in FIG. 12, the optical center axis P of the vision correction area 12 is the geometric shape of the lens outer shape. Target center axis: set so as to deviate obliquely downward from the nose side (right side in the figure) with respect to O And such a contact lens 30
Also, by setting the lens power in the intermediate region 18 in the same manner as in the contact lens 10 described in the above embodiment, the various effects described above can be effectively exhibited.

In addition, although not enumerated one by one, the present invention
Based on the knowledge of those skilled in the art, various changes, modifications, improvements, and the like can be made, and unless such embodiments depart from the spirit of the present invention.
Both are included in the scope of the present invention,
Needless to say.

[0048]

As is apparent from the above description, in the multifocal ophthalmic lens having the structure according to the present invention, two distance points particularly required by the central vision correction area and the peripheral vision correction area. The visibility at the (near point and far point) is very advantageously secured, and in the intermediate region, a specific lens between the lens powers set in the central vision correction region and the peripheral vision correction region, respectively. By providing the first transition portion and the second transition portion where the frequency is set, it is possible to advantageously obtain the visibility at the intermediate distance while sufficiently securing the visibility at the near point and the far point. Can be done.

[Brief description of the drawings]

FIG. 1 is an explanatory front view showing an example of a contact lens as an embodiment of the present invention.

FIG. 2 is an explanatory front view showing an example of a contact lens as another embodiment of the present invention.

FIG. 3 is a graph illustrating a specific setting example of a lens power distribution in a contact lens as an embodiment of the present invention.

FIG. 4 is a graph for explaining another specific setting example of the lens power distribution in the contact lens as the embodiment of the present invention.

FIG. 5 is a graph for explaining still another specific setting example of the lens power distribution in the contact lens as the embodiment of the present invention.

FIG. 6 is a graph for explaining still another specific setting example of the lens power distribution in the contact lens according to the embodiment of the present invention.

FIG. 7 is a graph for explaining still another specific setting example of the lens power distribution in the contact lens as the embodiment of the present invention.

FIG. 8 is a graph for explaining still another specific setting example of the lens power distribution in the contact lens as the embodiment of the present invention.

FIG. 9 is a graph for explaining still another specific setting example of the lens power distribution in the contact lens as the embodiment of the present invention.

FIG. 10 is a graph for explaining still another specific setting example of the lens power distribution in the contact lens as the embodiment of the present invention.

FIG. 11 is a graph for explaining still another specific setting example of the lens power distribution in the contact lens as the embodiment of the present invention.

FIG. 12 is a graph illustrating still another specific setting example of the lens power distribution in the contact lens according to the embodiment of the present invention.

FIG. 13 is a graph illustrating still another specific setting example of the lens power distribution in the contact lens according to the embodiment of the present invention.

FIG. 14 is an explanatory front view showing an example of a contact lens as still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Contact lens 12 Vision correction area 14 Central vision correction area 16 Peripheral vision correction area 18 Intermediate area 20 First transition section 22 Second transition section

Continued on the front page (72) Inventor Kazuya Miyamura 5-1-1 Takamoridai, Kasugai-shi, Aichi F-term in Menicon Research Institute, Ltd. 2H006 BD03

Claims (21)

[Claims] 1. A multifocal ophthalmic lens having a vision correction area in which different lens powers are set, wherein the vision correction area is a central vision correction area, and a lens power different from the central vision correction area is set. And an outer peripheral vision correction area positioned to be spaced apart on the outer peripheral side of the central vision correction area,
A lens power between the central vision correction area and the outer peripheral vision correction area is set and includes an intermediate area located between the central vision correction area and the outer peripheral vision correction area,
In the intermediate region, a first transition portion and a second transition portion having mutually different lens powers are formed, and among the first transition portion and the second transition portion, a lens power of the central vision correction region is formed. A multifocal ophthalmic lens, wherein the second transition portion having a close lens power is located on the outer peripheral side of the first transition portion having a lens power close to the lens power in the outer peripheral vision correction area. . 2. The multifocal ophthalmic lens according to claim 1, wherein the central vision correction area, the outer peripheral vision correction area, and the intermediate area are optically concentric with each other. 3. The multifocal ophthalmic eye according to claim 1, wherein the lens power in each of the central vision correction area and the peripheral vision correction area is substantially constant over the entire radial direction. lens. 4. The multifocal ophthalmic device according to claim 1, wherein the lens power in at least one of the first transition portion and the second transition portion is given as an extreme value. lens. 5. The lens power change rate is changed discontinuously at at least one of a boundary between the central vision correction area and the intermediate area and a boundary between the intermediate area and the outer peripheral vision correction area. Item 5. The multifocal ophthalmic lens according to any one of Items 1 to 4. 6. The multifocal lens according to claim 1, wherein at least one of the first transition portion and the second transition portion is formed so as to expand in a radial direction at a constant lens power. Type ophthalmic lens. 7. The same lens power as the peripheral vision correction area or the central vision correction area is set for one of the first transition part and the second transition part. The multifocal ophthalmic lens according to any one of the above. 8. A point where the lens power changes discontinuously in a radial direction between at least one of the first transition portion and the second transition portion in the intermediate region. A multifocal ophthalmic lens according to any one of claims 1 to 7. 9. A region between the central vision correction region and the first transition portion closest to the central vision correction region, and a region between the outer peripheral vision correction region and the second transition portion closest to the central vision correction region,
A region between the first transition portion and the second transition portion which are radially adjacent to each other and have a radial frequency distribution represented by a second-order or higher polynomial is represented by a third-order or higher polynomial. The multifocal ophthalmic lens according to any one of claims 1 to 8, having a power distribution in a radial direction as shown. 10. The power distribution in the radial direction in the intermediate region is represented by a single fifth-order or higher polynomial.
The multifocal ophthalmic lens according to any one of the above. 11. The central vision correction region and the first transition portion closest to the central vision correction region, the first transition portion and the second transition portion located radially adjacent to each other, and the The multifocal ophthalmic lens according to any one of claims 1 to 8, wherein a distribution of a lens power in a radial direction is expressed by a linear expression in at least one region between a second transition portion and the outer peripheral vision correction region. . 12. The multifocal ophthalmic lens according to claim 1, wherein the intermediate region has a radial dimension of 0.5 to 3.5 mm. 13. In the intermediate region, the second transition portion is located on the central vision correction region side of the second transition portion, and the outer peripheral vision correction is performed more than the second transition portion. A plurality of first transition portions having a lens power set close to the lens power of the area are provided, and a plurality of sets each including the first transition portion and the second transition portion are sequentially arranged in the radial direction. 13. The multifocal ophthalmic lens according to any one of 1 to 12. 14. A distant observation lens power: Pd (Dptr.) Is set for the outer peripheral vision correction area, and an additional power: ADD (Dptr.) Is given to the central vision correction area. The lens power for near observation is set,
Further, the lens power of the first transition portion: Pb (Dptr.) And the lens power of the second transition portion: Pc (Dptr.) Are respectively represented by the following formulas: Pd + 0.25 ≦ Pb <Pd + ADD / 2 Pd + ADD / 2 14. The multifocal ophthalmic lens according to claim 1, wherein the following condition is satisfied: ≦ Pc ≦ Pd + ADD. 15. A lens power for distant observation: Pd (Dptr.) Is set for the peripheral vision correction area, and an additional power: ADD (Dptr.) Is given to the central vision correction area. The lens power for near observation is set,
Further, the lens power of the first transition portion: Pb (Dptr.) And the lens power of the second transition portion: Pc (Dptr.) Are represented by the following expressions: Pd ≦ Pb <Pd + ADD / 2 Pd + ADD / 2 ≦ Pc 14. The multifocal ophthalmic lens according to claim 1, wherein the following condition is satisfied: ≦ Pd + ADD−0.25. 16. A pair of the first transition portion and the second transition portion are provided for the intermediate region, and the intermediate region is located adjacent to the outer peripheral side of the central vision correction region. And a first area in which the lens power gradually and continuously changes in the radial direction from the lens power of the central vision correction area to the lens power of the first transition portion, and a position adjacent to the outer peripheral side of the first area. Then, a second region where the lens power gradually and continuously changes in the radial direction from the lens power of the first transition portion to the lens power of the second transition portion, and on the outer peripheral side of the second region. 16. A third region, which is located adjacent to the third region and has a gradually and continuously changing lens power in the radial direction from the lens power of the second transition portion to the lens power of the outer peripheral vision correction area. The multifocal ophthalmic lens according to any one of the above. 17. The multifocal ophthalmic lens according to claim 16, wherein a lens power of the central vision correction area is Pa, a lens power of the first transition portion in the intermediate area is Pb, and the intermediate area is Pb. The lens power of the second transition portion is Pc, the lens power of the outer peripheral vision correction area is Pd, and from the optical center axis of the central vision correction area to the boundary between the central vision correction area and the intermediate area. Is the radial distance of Wa, and the radial distance from the optical center axis of the central vision correction area to the first transition portion is W.
b, the radial distance from the optical center axis of the central vision correction area to the second transition portion is Wc, from the optical center axis of the central vision correction area to the boundary between the intermediate area and the outer peripheral vision correction area. if the radial distance between Wd, lens in the first region power: y is the radial distance from the optical center axis of the central vision correction region as x, the following ^{equation: y = E1 (x 3/} 3 −x ² (Wa + Wb) / 2 + x · W
a · Wb) + F1, where E1 = (Pa−Pb) / ((Wa ³ −Wb ³ ) / 3−
(Wa ² −Wb ² ) (Wa + Wb) / 2 + (Wa−W
b) Wa · Wb) F1 = Pa−E1 (Wa ³ / 3−Wa ² (Wa + Wb)
/ 2 + Wa · Wa · Wb), and the lens power in the second region: y is represented by the following formula: y = E2 (x) where x is a radial distance from the optical center axis of the central vision correction region. ^{x 3/3-x 2 (} Wb + Wc) / 2 + x · W
b · Wc) + F2 where E2 = (Pb−Pc) / ((Wb ³ −Wc ³ ) / 3−
(Wb ² −Wc ² ) (Wb + Wc) / 2 + (Wb−W
c) Wb · Wc) F2 = Pb−E2 (Wb ³ / 3−Wb ² (Wb + Wc)
/ 2 + Wb · Wb · Wc), and the lens power in the third area:
y is the radial distance from the optical center axis of the central vision correction region as x, the following ^{equation: y = E3 (x 3/} 3-x 2 (Wc + Wd) / 2 + x · W
c · Wd) + F3 where E3 = (Pc−Pd) / ((Wc ³ −Wd ³ ) / 3−
(Wc ² −Wd ² ) (Wc + Wd) / 2 + (Wc−W
d) Wc · Wd) F3 = Pc−E3 (Wc ³ / 3−Wc ² (Wc + Wd)
/ 2 + Wc · Wc · Wd) The multifocal ophthalmic lens according to claim 16, represented by: 18. The multifocal ophthalmic lens according to claim 17, wherein the relation between the lens power: y and the radial distance: x in the first area is expressed by the following formula instead of the relational expression. Formula: y = (Pa−Pb) (x−Wb) ⁴ / (Wa−Wb) ⁴
The multifocal ophthalmic lens according to claim 17, represented by + Pb. 19. The multiple optical system according to claim 1, wherein the optical center of the central vision correction area is deviated with respect to a lens geometric center axis, and the amount of deviation is 2.0 mm or less. Focused ophthalmic lens. 20. The multifocal ophthalmic lens according to claim 1, wherein in the central vision correction area and the peripheral vision correction area, the surface shapes for determining power are each spherical. . 21. In the vision correction area, one of the lens surfaces is a toric surface.
0. The multifocal ophthalmic lens according to any one of 0.