Technical field
[0001]
The present invention relates to a toric ophthalmic lens for correcting astigmatism.
BACKGROUND
[0002]
Examples of ophthalmic lenses for correcting astigmatism is glasses or contact lenses, intraocular lenses and the like. These ophthalmic lens has an optical surface called toric surface. The toric surface, as in the rugby ball and donuts aspect, refers to a surface shape of the lens have different radii of curvature of at least two meridians. The lens having the toric surface is referred to as toric lens (toric lens).
[0003]
　The toric surface, a difference in the refractive power of the lens in directions perpendicular to each other, which is set on the surface occurs. It is possible to correct astigmatism by utilizing the difference in the refractive power. The conventional techniques for stabilizing the position in the eye of the technology and intraocular lenses for designing the shape of the lens surface more flexibly have been proposed (Patent Documents 1 and 2). Also, a technique for constituting a connection portion between the optical support part so as to advantageously suppress the onset of cataract has been proposed (Patent Document 3). Also it has been proposed a technique for defining the toric surface in formulas (Patent Document 4).
CITATION
Patent Document
[0004]
Patent Document 1: U.S. Patent No. 5,173,723 Pat
Patent Document 2: WO 2015/136997
Patent Document 3: WO 2006/123427 Patent
Patent Document 4: Japanese Patent No. 4945558
Summary of the Invention
Problems that the Invention is to Solve
[0005]
　However, in the conventional ophthalmic lenses for correcting astigmatism, because it is not assumed to control the thickness of the edge of the lens, the edge thickness is detrimental to the design of the intraocular lens from the viewpoint of preventing cataract there is a possibility. In other words, it the edge thickness from the viewpoint of cataract prevention is predetermined thickness or more is desired, simply because the central thickness of the lens when defining the shape of a lens by an edge thickness in the reference is increased, a small incision insert according becomes difficult, there is a possibility that increasing the burden on insertion.
[0006]
　The disclosure of technology has been made in view of the above circumstances, and it is an object of toric eye capable of designing a lens to contribute to cataract prevented without lowering the degree of freedom in lens design use lens, i.e. has a thickness of edges can be expected cataract prevention effect, and the center thickness is to realize a toric ophthalmic lens does not become unnecessarily thick.
Means for Solving the Problems
[0007]
　Toric ophthalmic lenses of the present disclosure is in a top view of the optical portion, a substantially flat portion edge thickness of the optical portion is substantially constant is provided so as to overlap with the steepest meridian of the toric surface of the optical unit. Thus, conventionally thinner edge thickness of the strong principal meridian direction, providing a support to the part, but the optical unit had stable not obtained concern the force to press the posterior capsule of the eye, the present According to toric ophthalmic lens disclosed, predetermined edge thickness even when the support portion is provided on the portion stably obtained a force for pressing the optical portion in the posterior capsule because it is secured, to prevent secondary cataract viewpoints higher degree of freedom lens design from it is possible. Moreover, the edge thickness of the substantially flat portion, thinner than the edge thickness of the optical portion overlapping with the weak principal meridian of the toric surface in a top view, a toric surface of the strong principal meridian in top view in case of substantially form a flat portion as a toric surface thicker than the edge thickness of the optical portion overlapping with.
[0008]
　Moreover, the substantially flat portion, the area where the thickness is thinner than a predetermined minimum thickness in the toric ophthalmic lenses, the toric surface, the thickness may be formed by replacing the plane as a lowest thickness. It may also be in a substantially flat portion of the gentle slope surface and a curved surface or a combined form thereof.
[0009]
　Further, in a top view of the optical portion of the toric ophthalmic lens, the optical portion of the edge thickness h (r) is the formula position distance is r from the center of the lens (1) and (2) a substantially flat portion provided with the provided
Equation 1

[Equation 2]

H (High) is an edge thickness of the portion overlapping the strong principal meridian of the toric ophthalmic lens, H (Low) includes a weak principal meridian of the toric ophthalmic lens it may be the edge thickness of the overlapping portions. Also, H is equivalent to the predetermined minimum thickness.
[0010]
　The cross-sectional shape at an arbitrary meridian direction on the lens surface of the toric ophthalmic lens
Equation 3

is expressed by the formula containing, c is the paraxial curvature at the toric ophthalmic lens, r is the toric ophthalmic lens the distance from the lens center, k is the conic constant of the rotationally symmetric surface to the lens optical axis in a toric ophthalmic lens, c, r, k is common to meridian direction on the lens surface, a (θ) and B (theta) is the formula (4) and (5) given by
equation 4]

[formula

5] H (High) is a toric ophthalmic lens was designed using the equation (4) and (5) If an edge thickness of the portion overlapping the strong principal meridian, H (Low) is a toric ophthalmic lens equation (4) and (5) at the edge thickness of the portion overlapping the weak principal meridian when designed using the it may be configured a certain way.
[0011]
　Further, in a top view of a toric ophthalmic lens, to the width of the substantially flat portion in the direction toward the lens center from the edge of the toric ophthalmic lens may be 0.05mm or 0.5mm or less, viewed from the toric ophthalmic lens in the angle range substantially flat portion when viewed from the lens center of the toric ophthalmic lens is formed, 35 ° or less on one side 10 ° or more with respect to 20 ° to 70 ° or less (steepest meridian across the steepest meridian ) may be used. Since the optical unit diameter of the intraocular lens is generally 5 mm in diameter ~ 7 mm, in a top view of a toric ophthalmic lens, the width L of the substantially flat portion in the direction toward the lens center from the edge of the toric ophthalmic lens, ( it may satisfy the condition of 1/100) ≦ L ≦ optical portion diameter (1/10 of the optic diameter).
[0012]
　Furthermore, the toric ophthalmic lenses of the present disclosure, in a top view of the optical portion, and continuous surface is provided on a toric surface of the edge and the optical portion of the optical portion, the edge thickness of the optical portion of the continuous surface is substantially constant, the surface of the continuous may be provided so as to overlap with the steepest meridian of the toric surface of the optical unit.
Effect of the invention
[0013]
　According to the present disclosed technology, it is possible to realize a toric ophthalmic lens having a possible edge to design lenses that contribute to cataract prevented without lowering the degree of freedom in lens design.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014]
[1] Figure 1 (a) ~ (c) is a schematic diagram showing an example of a conventional toric IOL.
FIG. 2 is a graph showing an example of a change in the edge thickness of a conventional toric IOL.
[3] FIG. 3 (a) ~ (c) is a schematic diagram showing an example of a toric intraocular lens according to one embodiment.
[4] FIG. 4 is a graph showing an example of a change in the edge thickness of the toric intraocular lens according to one embodiment.
FIG. 5 is a schematic diagram showing an example of a toric intraocular lens according to a modification.
FIG. 6 is a schematic diagram showing an example of a toric intraocular lens according to another variant.
DESCRIPTION OF THE INVENTION
[0015]
　The following describes embodiments of the present invention. In the following description, it will be described toric intraocular lens, the present invention is not limited to toric intraocular lenses, can be applied to various toric ophthalmic lenses such as spectacle lenses.
[0016]
　The toric intraocular lens, the toric surface, a difference in the refractive power of the lens in directions perpendicular to each other, which is set on the surface (first meridian direction and the second meridian direction) occurs. It is possible to correct astigmatism by utilizing the difference in the refractive power. In general, the difference in the refractive power is called the cylinder power. In toric surface, direction of larger meridian refractive power is called the strong principal meridian direction small meridian refractive power is called the weak principal meridian.
[0017]
　First, a description will be given technology underlying the present invention. In this embodiment, it defines the lens surface by the following equation (6) to produce an intraocular lens. The first term of Equation (6) defines a lens surface of a rotationally symmetric about the optical axis of the lens, the second and subsequent terms defining the toric surface.
[6]

　Here, c is the curvature of the reference surface of the rotational symmetry of the lenses before adding toric surface defined by the second and subsequent terms of equation (6). X and Y are the distance from the lens center in the first the distance from the lens center in the direction and the second direction, for example, strong principal meridian direction and a weak principal meridian direction. Further, r is the radial distance (r 2 = X 2 + Y 2 is). Also, k is the conic constant of the reference surface in front of the rotational symmetry of adding toric surface defined by the second and subsequent terms of equation (6), common c, r, and k is the X and Y directions It has become. Also, a is a parameter for adding the toric surface. The second and subsequent terms of the terms in equation (6) is, (X 2 + Y 2 ) n represents each term of when expanding the (n = 1, 2 · · ·). The coefficient of each term of the second and subsequent terms represent the parameters for adding a toric surface. The first term of Equation (6) is an example of a predetermined defining equation for defining the lens surface of rotational symmetry with respect to the optical axis of the lens. Further, if the expression for defining the first term equal to the lens surface of the Formula (6), the first term may be another expression.
[0018]
　It is possible to define the lens surface throughout the lens when using the above equation. This makes it possible to have a higher than the conventional degrees of freedom defining the lens surface. In particular, the shape of the X-direction and the other Y directions which can not be defined by the conventional formula as described above (e.g., a direction to be X = Y) also may be defined freely.
[0019]
　The first term of Equation (6), has the same form as equation of the aspherical lens by only formula or conic constant of the spherical lens. Therefore, when designing a toric intraocular lens using equation (6), the base shape of the toric intraocular lens can be made similarly to the conventional rotationally symmetric lens. Accordingly, toric intraocular lenses fabricated performed lens design using equation (6) can be loaded without hindrance to conventional inserter.
[0020]
　In the prior art a method of unifying the edge thickness of the 45 ° direction of the lens rotationally symmetrical lens are proposed, the calculation of the edge thickness can not be calculated only after the parameters of the toric surface was determined. Meanwhile, in the design method using the equation (6) of this embodiment, X 2j Y 2 (n-j) (provided that, j is a natural number other than n) is the coefficient of the 0, or a 2Qx = -a 2Qy , a 2Qx a 2py = 0 (p, q is a natural number) Tosureba calculation of the edge thickness is not required, it is possible to an edge thickness of the 45 ° direction to design equivalent shape and rotationally symmetrical lens.
[0021]
　In the case of manufacturing a lens with a so-called molding method, it is necessary to consider the change in the lens shape due to shrinkage of the lens material. By designing the lens using Equation (6) of the present embodiment, the base shape of the lens is given the same rotational symmetry lens, it can be regarded as a shrinkage equal to the rotational symmetry lens. Therefore, according to the lens design method of the present embodiment, it is possible than the conventional method in toric intraocular lens is a non-rotationally symmetrical lens to evaluate shrinkage evaluating efficiently shrinkage.
[0022]
　Further, since it is also easily calculated paraxial curvature in the X and Y directions as described below, it becomes easy calculation of the paraxial refractive power. Therefore, it is possible to easily perform the calculation of the paraxial power from the function of formula (6). Further, by using the equation (6), it is possible to control the spherical aberration in the X and Y directions of the toric intraocular lens. Thus, by the lens designed using the equation (6), the degree of freedom of the parameters defining the toric surface of the toric intraocular lens, the lens surface shape that favorably corrected than conventional various aberrations it can be designed.
[0023]
　Next, the equation (6), derives the expression of the cross-sectional shape in any direction of the optical surface of the lens (angle theta). Here, consider the case of maximum order 4th order as an example. X = rcosθ in equation (6), when y = r sin, equation (7) is obtained by converting as follows.
[Equation 7]

where
[number 8]

is.
Further,
Equation 9]

a.
[0024]
　As it is seen from equation (7), using the equation (6) can be expressed the cross-sectional shape of any direction (any theta) of the lens surface in the general optical surfaces defining equation. Further, it is possible to easily perform an optical simulation of the arbitrary cross section of the comparative and actually manufactured lens of the design value.
[0025]
　Then, equation (6), (7) using the base technology of the present invention using any of, will be described below an example of a case of designing a toric intraocular lens. Incidentally, in this description, it is assumed that forming the toric surface as the optical surface of the mountain-(convex upward).
[0026]
　Figure 1 is a schematic view showing an example of the optical portion 100 of a conventional toric IOL. In FIG. 1, it is not shown the supporting portion of the toric intraocular lens. In the optical unit 100 shown in FIG. 1, sets the XY plane perpendicular to the optical axis of the optical unit, described as the X-axis and Y-axis are perpendicular to each other. Further, to set the Z-axis orthogonal to the XY plane. The thickness of the Z-axis direction corresponds to the edge thickness at the edge of the optical portion.
[0027]
　Further, FIG. 1 (a), (b) is a side view of the optical unit 100, FIG. 1 (c), the positive side of the Z axis of the optical portion 100 negative side of the Z-axis, i.e. the optical surface 104 side , that is a view looking toward the optical surface 103 side.
[0028]
　Figure 1 (c), the both sides of the optical portion 100 of a conventional toric intraocular lens, all over the XY plane, i.e. the lens center 101 (XY plane of the origin O) optical surface 103 in the region spanning the edge 102 from , 104 are formed. In the present embodiment, the optical surface 103 has no toric surface is spherical or aspherical shape. On the other hand, the optical surface 104 has a toric surface. Further, as shown in FIG. 1 (a), the edge 102 of the optical unit 100, the edge thickness is thin walled section 105 as compared to the edge thickness of the other portions is formed. Direction thin portion 105 as viewed from the center of the lens 101 is formed corresponds to the extending direction of the so-called steepest meridian. Incidentally, strong principal meridian in FIG. 1 (c) overlaps the X-axis.
[0029]
　Figure 2 shows an example of a change in the angular direction of the edge thickness when viewed from the lens center 101 of the optic 100. Here the vertical axis Z (mm) is a sag amount in the optical surface 104. In the graph of FIG. 2, the angle of the horizontal axis (phi; Unit: °) the direction of 0 ° and 180 °, a weak principal meridian direction of the optical portion 100. The direction of the angle of 90 ° is a strong principal meridian direction of the optical portion 100. The angle change of the edge thickness in the range of 180 ° ~ 360 °, the angle is the same as the change of the edge thickness in the range of 0 ° ~ 180 °. As shown in FIG. 2, the edge thickness of the optical unit 100, the most thinner in strong principal meridian direction.
[0030]
　Therefore, when the lens design to provide a support to the thin portion 105, to become connecting the support part to a thin portion of the edge thickness, the force for pressing the optical portion in the posterior capsule is there is concern that not stably obtained and it may not be desirable lens design from the viewpoint of preventing secondary cataract.
[0031]
　In contrast, in FIG. 3, an example of an optical unit 200 of the toric intraocular lens according to the present embodiment is shown schematically. Similar to FIG. 1, FIG. 3, is not shown of the supporting portion of the toric intraocular lens. Further, similarly to the optical unit 100, the optical unit 200, sets the XY plane perpendicular to the optical axis of the optical unit, described as the X-axis and Y-axis are perpendicular to each other. Further, to set the Z-axis orthogonal to the XY plane. The thickness of the Z-axis direction corresponds to the edge thickness at the edge of the optical portion. Figure 3 (a), (b) is a side view of the optical unit 200, FIG. 3 (c), the positive side of the Z axis of the optical portion 200 negative side of the Z-axis, i.e. the optical surface 204 side, that it is a view looking toward the optical surface 203 side. Also in FIG. 3, the optical surface 203 has no toric surface is spherical or aspherical shape. On the other hand, the optical surface 204 has a toric surface.
[0032]
　The optical unit 200 of the toric intraocular lens in this embodiment, the center thickness of the lens center 201 (the origin O of the XY plane ') is equivalent to the center thickness of the lens center 101 of the optic 100 of the conventional toric intraocular lens some, but substantially flat portions where the edge thickness is substantially constant in the edge 202 (hereinafter referred to as "flat portion") 205 is formed. Flat portion 205 is formed to include an edge overlapping the strong principal meridian when viewed from the lens center 201. Incidentally, similarly to FIG. 1 (c), the strong principal meridian in FIG. 3 (c) it overlaps the X-axis. Therefore, in the present embodiment, as shown in FIG. 3 (c), the edge 202, two flat portions 205 are formed around the one of the lens surfaces 204 of the optical unit 200. Also, the flat portion 205, in a top view of the optical portion 200 are formed so as to sandwich the lens center 201 overlaps the X-axis. Incidentally, the flat portion 205, in a top view of the optical unit, which is an example of a continuous surface on the toric surface of the edge and the optical portion of the optical unit.
[0033]
　Here, the edge thickness at the position of the radius r from the center of the lens 201 and h (r) in the flat portion 205 as shown in FIG. 3 (a). The h (r) by appropriately determining, in a top view of the optical unit 200 shown in FIG. 3 (c), the range of the angle φ of the flat portion 205 is formed as viewed from the lens center 201, flat portions 205 It determined the width L in the X-axis direction (the radial direction of the optical portion) of. (Since a toric surface of the optical surface 204 is defined, the edge thickness h (r) is determined line of intersection between the plane of the toric surface and the flat portion 205 of the optical surface 204 is determined.) In the present embodiment, as an example , minimum edge thickness H is in the flat portion 205 is set so as to satisfy the 0.01mm ≦ H-H (high) ≦ 0.05mm, the region where the edge thickness h (r) is thinner than H is, h (r ) = it may be configured such that the H. Toric lens flat portion 205 in this embodiment is provided so that its shape becomes a X-axis, i.e. line symmetry with respect to the strong principal meridian.
[0034]
　In the present embodiment, as described above, if Sadamare edge thickness h (r) in the flat portion 205, the planar shape of the flat portion 205 is determined. However, in the present embodiment, may define planar shape of the flat portion 205 first (preferentially). For example, the angle phi at the end E of the flat portion 205 may be a set to satisfy 55 ° ≦ φ ≦ 80 °. Then, the angular range in which the flat portion when viewed from the lens center of the toric intraocular lens is formed (angular width) is, on one side 10 ° with respect to 20 ° ~ 70 ° (strong principal meridian across the steepest meridian to 35 °) to become. The width L in the X-axis direction of the flat portion 205 may be set so as to satisfy the 0.05 mm ≦ L ≦ 0.5 mm. Since the optical unit diameter of the intraocular lens is generally 5 mm in diameter ~ 7 mm, in a top view of a toric ophthalmic lens, the width L of the flat portion in the direction toward the lens center from the edge of the toric ophthalmic lens, (optical may satisfy the condition that the part 1/100 of the diameter) ≦ L ≦ (1/10 of the optic diameter). In these cases, the angle range of the flat portion 205 (angular width) or by determining the width L of the flat portion 205, the edge thickness h (r) is determined.
[0035]
　The edge thickness h in the flat portion 205 (r) is thinner than the edge thickness of the weak principal meridian side of the optical unit 200, and thicker than the edge thickness in the case of forming a flat portion 205 as a toric surface of the optical portion 100 It is set to be. The edge thickness h (r) By setting in this manner, the edge thickness of the weak principal meridian side of the optical unit 200, i.e., the edge thickness of the portion overlapping the Y-axis can be similarly as the conventional optical unit 100. Therefore, according to this embodiment, by controlling only the edge thickness of the flat portion 205, since it is not necessary to consider the control of the edge thickness of the other portion, the control of the edge thickness of the flat portion 205 of the optical unit 200 it becomes easy.
[0036]
　Figure 4 shows an example of a change in the angular direction of the edge thickness when viewed from the lens center 201 of the optic 200. In the graph of FIG. 4, the angle of the horizontal axis (phi; Unit: °) and sag vertical axis (Z; unit: mm) is the same as FIG. In the example shown in FIG. 4, the edge thickness of the optical portion 200 is constant in the range of 70 ° ~ 110 ° across the strong principal meridian direction (φ = 90 °). That is, in this range, and is formed flat portion 205. In the example shown in FIG. 4, the angle φ in FIG. 3 is a 70 °.
[0037]
　Therefore, even when the lens design to provide the support portion to the flat portion 205, unlike the case of providing the support portion the thin portion 105 of the optical unit 100, since the edge thickness is ensured by the predetermined thickness, the supporting portion force optic is pressed against the posterior capsule becomes possible to stably obtained, the lens design to contribute to the prevention of secondary cataract by.
[0038]
　Further, in the present embodiment, the above equation (6), (7) using one of the formulas when designing an optical unit 200 of the toric intraocular lens, the following equation (8), by (9) to add a condition.
[Expression 10]

[Expression 11]

That is, in the present embodiment, the above equation (6), using either equation (7), when designing the optical portion 200 of the toric intraocular lens, the edge for regions where the thickness h (r) is thinner than H is as h (r) = H. Here, H (High) is an edge thickness of the portion overlapping the strong principal meridian in the case of designing the optical unit 200 as a conventional optical unit 100 (in the drawing X-axis), H (Low), the optical unit 200 which is the edge thickness of the portion overlapping the weak principal meridian (in the Y-axis) when designed as a conventional optical unit 100. Here, H is equivalent to the predetermined minimum thickness.
[0039]
　In the configuration of an optical unit of a conventional toric intraocular lenses that the edge thickness is thin, but there is a possibility that an obstacle in designing a toric intraocular lens from the viewpoint of cataract prevention, according to this embodiment formula based on the above condition (6), (7) using either, by designing the optical unit 200, is possible to realize an optical portion of the toric intraocular lenses that contribute to cataract prevention than conventional it can.
[0040]
　Toric intraocular lens of the present embodiment may be produced by cutting method be produced in the mold process. However, processing of the toric surface is preferably performed by the lathe can move the processing tool in the optical axis direction while synchronizing with the rotation speed. In the present embodiment, a toric surface optical surface 204, although the optical surface 203 has been described is a spherical or aspherical configuration of the optical surface to which the present invention is applied is not limited thereto. It optical surface 204 may have an aspheric toric surface, both optical surfaces 203 and the optical surface 204 may include a toric surface. Both optical surfaces 203 and the optical surface 204 is toric surface, if the steepest meridian is common, the edge thickness h (r) has a thickness in the steepest meridian of the optical surface 203, a flat portion 205 thickness It becomes the difference of that thing.
[0041]
　Above it is the description about the present embodiment, the configuration of the toric intraocular lens is not limited to the above embodiments, various within a range that does not lose the technical idea and the identity of the present invention it is possible to change. For example, in the design of the toric intraocular lens, as shown in the following modifications, the above equation (6), (7) may be used an expression other than, if the above expression thereof (8) it may be set by adding a condition shown in (9). Further, in the above embodiment, the angle phi, the width L, the range of each value of the edge thickness h (r) is only an example, not intended to limit the scope of the above. Furthermore, in the embodiment described above, in a top view of the optical portion 200, it is formed so as the flat portion 205 is line symmetrical with respect to the X-axis, strong principal meridian of a toric surface of the optical unit 200 (X-axis ) and be formed to overlap, may not become linearly symmetrical with respect to the X axis. It may also be a part of the flat portion 205 on the gentle slope or curved surfaces or form as combinations thereof.
[0042]
　The method of designing such a toric intraocular lens, in a top view of the optical portion and the surface (flat portion 205) is provided continuous to the toric surface of the edge and the optical portion of the optical unit, in the continuous surface edge thickness of the optical portion is substantially constant, the surface of the continuous can be designed toric intraocular lens that is provided so as to overlap with the steepest meridian of the toric surface of the optical unit.
[0043]
　Next, a modified example of the above embodiment will be described below. In the following description, strong principal meridian direction in the X direction toric intraocular lens, a weak principal meridian direction is a Y direction, X and Y may be reversed. The details of the equation derivation described below, because it is described in the patent documents described above, the description thereof is omitted. As an expression that defines the conventional toric surface, an equation (10) representing the shape of a lens cross section by a plane including the X axis and the optical axis, mentioned formula (11) representing the lens section along a plane containing the Y axis and the optical axis It is. Here, Rx and Ry represent X-axis and the lens section along a plane containing the optical axis radius of curvature and the Y axis of the lens section along a plane containing the optical axis radius of curvature, respectively. It should be noted, it is a Rx ≠ Ry. cx and cy represent X-axis and the curvature of the lens section along a plane containing the optical axis and the Y-axis and the curvature of the lens section along a plane containing the optical axis, respectively. Here, cx = 1 / Rx, a cy = 1 / Ry. kx and ky represent respectively a conic constant in conic constant (conic constant) and Y-direction in the X direction. Incidentally, there is a description of the kx ≠ ky Patent Document 4 (Japanese Patent No. 4945558).
[Number 12]

[number 13]

[0044]
　Further, as the expression used in the design of conventional toric intraocular lens, equation (10), Equation (12) instead of (11), and (13). It should be noted, it is a Rx ≠ Ry. Moreover, the patent 4945558 there is described the kx ≠ ky.
[Number 14]

[number 15]

[0045]
　When using the equation (10) and (11), or formula (12) and (13), only be defined the shape of the lens section in the X and Y directions, the whole of the cross-sectional shape lens can not be specified.
[0046]
　Alternatively there is a method of designing a toric intraocular lens using equation (14).
[Number 16]

[0047]
　When designing a toric intraocular lens using the above equation (10) to (14), equation (8), to design by adding a condition of (9), optically as in the above embodiment the edge thickness at the strong principal meridian direction parts by securing a predetermined thickness, it is possible to perform lens design to contribute to the prevention of secondary cataract.
[0048]
　In FIGS shows a partially enlarged view showing a schematic configuration of a toric intraocular lens 300, 400 according to a modification of the above embodiment. Incidentally, configurations that are not shown in FIGS. 5 and 6 are the same as the configuration of the toric intraocular lens 200, the illustration and detailed description thereof is omitted. Toric intraocular lens 300, 400 of the present modification, instead of the flat portion 205 of the toric intraocular lens 200, a curved portion 305, respectively, the inclined portion 405 is formed. Similarly to the flat portion 205, a curved portion 305 and the inclined portion 405 is different from the optical surface 204 is not a part formed for the purpose of exerting the aberration correction function of a toric intraocular lens. In this regard, as a portion having a surface that is continuous with the toric surface of the edge and the optical portion of the optical portion, not only the flat portion 205 of the above, it can be said that the inclined portion 405 is also included. Furthermore, it can be said that the optical surface 204 curved portion 305 having a different plane in terms of optical function are also included in the portion having a surface that is continuous with the toric surface of the edge and the optical portion of the optical unit.
[0049]
　Thus, even when employing a toric intraocular lens 400 toric intraocular lens 300 or inclined portion 405 of the curved portion 305 is formed is formed, similarly to the above-described toric intraocular lens 200, the edge thickness is given because of being secured in thickness, the force is pressed against the posterior capsule optical portion by the support portion becomes possible to obtain stable, the lens design to contribute to the prevention of secondary cataract.
[0050]
　Furthermore, according to the method of designing a toric intraocular lenses 200, 300, 400, when determining the edge thickness, thinner than the center thickness in the center thickness of a conventional toric intraocular lens 100 design of the optical unit effect that can also be expected. That is, according to the design method according to the above embodiment, the center thickness of the optic portion be set thinner than the center thickness in the design of a conventional toric intraocular lens, when it is possible to secure the edge thickness of the it can be said.
DESCRIPTION OF SYMBOLS
[0051]
200 optical unit
202 edge
205 flat part

The scope of the claims
[Requested item 1]
　In a top view of the optical portion, a substantially flat portion edge thickness of the optical portion is substantially constant, the is provided so as to overlap with the steepest meridian of the toric surface of the optical part, for toric eye, characterized in that lens.
[Requested item 2]
　The edge thickness of the generally flat portion, said top surface thinner than the edge thickness of the optical portion that overlaps the weak principal meridian of the toric surface in view, in the top view when the substantially flat portion is formed as the toric surface thicker than the edge thickness of the optical portion overlapping the strong principal meridian of a toric surface, a toric ophthalmic lens of claim 1, wherein the.
[Requested item 3]
　It said generally flat portion, the claims thickness in the toric ophthalmic lens for the region made thinner than a predetermined minimum thickness, a toric surface, wherein the thickness is formed by replacing the plane to be the minimum thickness toric ophthalmic lens according to 1 or 2.
[Requested item 4]
　In a top view of the optical portion of the toric ophthalmic lenses, provided a substantially flat portion in which the distance from the lens center edge thickness of the optical portion of the position is r h (r) is given by equation (1) and (2)
[Equation 1]

[Equation 2]

H (High) is an edge thickness of the portion overlapping the strong principal meridian of the toric ophthalmic lens, H (Low), the portion overlapping the weak principal meridian of the toric ophthalmic lens in is the edge thickness
toric ophthalmic lens, characterized in that.
[Requested item 5]
　The cross-sectional shape at an arbitrary meridian direction on the lens surface of the toric ophthalmic lens
Equation 3

is expressed by the formula containing, c is the paraxial curvature at the toric ophthalmic lens, r is the toric ophthalmic lens the distance from the lens center, k is the conic constant of the rotationally symmetric surface to the lens optical axis in the toric ophthalmic lens, c, r, k is common to the meridian direction on the lens surface, a (theta) and B (theta) is the formula (4) and (5) given by
equation 4]

[formula 5]

wherein H (High), the formula (4) the toric ophthalmic lens and (5 ) is an edge thickness of the portion overlapping the strong principal meridian when designed using, H (Low), the weak principal meridian in the case of designing the toric ophthalmic lenses using equation (4) and (5) the edge thickness of the portion overlapping the, especially the Toric ophthalmic lens according to claim 4,.
[Requested item 6]
　In a top view of the toric ophthalmic lens, according to claim 1 to 5, the width of the substantially flat portion in the direction toward the lens center from the edge of the toric ophthalmic lens characterized in that it is a 0.5mm or 0.05mm toric ophthalmic lens according to any one of.
[Requested item 7]
　In a top view of the toric ophthalmic lens, the width of the substantially flat portion in the direction toward the lens center from the edge of the toric ophthalmic lens optical zone diameter of 1/100 or more and 1/10 or less of the optic diameter toric ophthalmic lens according to any one of claims 1 to 5, characterized in that there.
[Requested item 8]
　Wherein in a top view of a toric ophthalmic lens, the angular range in which the substantially flat portion when viewed from the lens center is formed of the toric ophthalmic lens, said strong principal meridian interposed therebetween is 20 ° to 70 ° or less toric ophthalmic lens according to any one of claims 1 to 7, wherein the.
[Requested item 9]
　In a top view of the optical portion, the optical portion of the edge and has said toric surface and continuous surface to the optical section is provided,
　the edge thickness of the optical portion of the continuous surface is substantially constant,
　for the continuous surface, the is provided so as to overlap with the steepest meridian of the toric surface of the optical portion, toric ophthalmic lenses, characterized in that.