Corneal molding lens

Abstract

The present application provides a kind of orthokeratology lens, which includes the inner surface facing the cornea of human eye when wearing, the inner surface includes the base curve area in the center and the reverse curve area on the peripheral side of the base curve area, the base curve area includes: the first base curve area in the center of the base curve area, the sag difference h1>0 of the first base curve area and the base sphere at the same diameter, the second base curve area on the peripheral side of the first base curve area and adjacent to the reverse curve area, the sag difference h2<0 of the second base curve area and the base sphere at the same diameter. With the above structure, the peripheral defocus of the entrance pupil area and the peripheral defocus of the bullseye ring can be improved at the same time, and myopia can be effectively controlled.

Description

Technical Field

[0001] This invention relates to an orthokeratology lens. Background Technology

[0002] Rigid gas permeable contact lenses for orthokeratology (or simply orthokeratology lenses) are a reversible, non-surgical refractive correction product.

[0003] Orthokeratology lenses typically consist of several concentric arc-shaped zones, including a base curve zone, a reverse curve zone, and a positioning zone. They reshape the cornea using inverse geometry principles. Inverse geometry specifically refers to the fact that the base curve and reverse curve zones are not in direct contact with the cornea; there are gaps between these two zones and the cornea. The positioning zone, however, is in direct contact with the cornea. After wearing the orthokeratology lens (sometimes referred to as the lens in this manual), the special shape of its inner surface causes a layer of unevenly distributed tear fluid to be trapped between the lens and the cornea. The hydrodynamic effect of the tear fluid pulls the epithelial cells in the central part of the cornea towards the mid-periphery, located on the periphery of the central cornea. Simultaneously, when the eye is closed, the eyelids exert pressure on the lens. Under this pressure, the central part of the lens applies pressure to the cornea beneath it. These two effects flatten the central curvature of the cornea, reshaping it and altering the eye's refractive state compared to before reshaping. The image point shifts closer to the retina, thus correcting myopia.

[0004] Some orthokeratology lenses have a spherical base curve area. The base curve area consists of a single sphere, and the radius of curvature of the base curve area is determined by the corneal K-value and the myopia degree. The specific relationship is as follows:

[0005]

[0006] Where r is the radius of curvature of the spherical base arc, K is the corneal K-value, D is the myopia degree, and F is the adjustment factor.

[0007] Clinical studies have found that orthokeratology lenses with a spherical base curve can not only correct myopia but also slow down the axial elongation of some adolescents, thus controlling the progression of myopia. Clinical research results show that the mechanism by which orthokeratology lenses work is the formation of myopic peripheral defocus in the eye after wearing them.

[0008] However, orthokeratology lenses with a spherical base curve are not 100% effective at controlling myopia. They cannot achieve effective myopia control for every patient; only a portion of patients can benefit from controlled myopia progression. This is because the base curve is a single sphere, and different patients have different corneal K-values ​​and myopia degrees, resulting in varying degrees of peripheral defocusing after reshaping. Patients with higher corneal K-values ​​and myopia degrees will experience greater peripheral defocusing after reshaping, thus having a higher chance of achieving effective myopia control.

[0009] Besides orthokeratology lenses with a single spherical base curve, there are also orthokeratology lenses in the prior art with a base curve divided into multiple regions, for example, see Patent Documents 1-4.

[0010] Patent document 1 discloses a base curve region comprising multiple regions with different radii of curvature, which can correct refractive errors while simultaneously correcting presbyopia. However, this design is ineffective in improving peripheral defocus.

[0011] In addition, after wearing orthokeratology lenses, the peripheral defocus that causes myopia in the human eye includes two parts: peripheral defocus in the entrance pupil area and peripheral defocus in the bull's eye ring.

[0012] Patent document 2 mentions a base arc region with a gradually steepening design, which improves the defocus around the entrance pupil area compared to a single spherical base arc region, but does not improve the defocus around the bullseye ring. Patent document 3 mentions a base arc region with a gradually flattening design, which improves the defocus around the bullseye ring, but reduces the defocus around the entrance pupil area.

[0013] Therefore, there is still room for improvement in existing technologies regarding how to effectively improve peripheral defocus and effectively control myopia.

[0014] Patent Document 1: CN201711278012.0

[0015] Patent Document 2: CN201510441201.X

[0016] Patent Document 3: CN202020791228.8 Summary of the Invention

[0017] This invention proposes an orthokeratology lens that can provide greater peripheral defocus for myopia correction, thereby improving the effectiveness of myopia control while correcting myopia.

[0018] This invention provides an orthokeratology lens, comprising an inner surface facing the cornea when worn and an outer surface opposite to the inner surface. The inner surface includes a base curve region located at the center and a reverse curve region located on the periphery of the base curve region. The base curve region includes: a first base curve region located at the center of the base curve region, wherein the sag difference h1 between the first base curve region and the base spherical surface at the same diameter is greater than 0; and a second base curve region located on the periphery of the first base curve region and adjacent to the reverse curve region, wherein the sag difference h2 between the second base curve region and the base spherical surface at the same diameter is less than 0; wherein, h1 = h 1A -h S h 1A h is the sag of the first base arc region. S The sag of the base sphere; h2 = h 2A -hS h 2A h is the sag of the second base arc region. S The sag of the base sphere.

[0019] The orthokeratology lens with the above structure can be easily controlled so that the curvature of the central part of the first base curve region is less than that of the peripheral part, and the curvature of the central part of the second base curve region adjacent to the inverted curve region is greater than that of the peripheral part. This also improves the defocus around the entrance pupil and the defocus around the bullseye ring, thus improving the effectiveness of myopia control.

[0020] Optionally, the curvature of the central portion of the first base arc region is less than that of the peripheral portion; the curvature of the central portion of the second base arc region is greater than that of the peripheral portion.

[0021] Optionally, the first base arc region includes one or more arc segments, and any two points i and j on any one of the arc segments satisfy:

[0022] d i <d j , and h 1i <h 1j ,

[0023] Where, d i Let d be the diameter at point i. j Let h be the diameter at point j. 1i Let h be the elevation difference at point i. 1j Let be the difference in elevation at point j.

[0024] Optionally, the first base arc region is composed of at least two arc segments, and the elevation difference h1 of each arc segment increases from the inside to the outside along the radial direction.

[0025] Optionally, the first base arc region includes three or more arc segments, and along the radial direction, the difference in elevation h between the outermost arc segment and the arc segment located in the radial direction is... 1外 The difference in sag h between the arc segments located at the innermost radial end and the arc segments located at the innermost radial end. 1内 The elevation difference h1 of the other arc segments located between the two is greater than 0.

[0026] Optionally, the second base arc region includes one or more arc segments, and any two points p and q on any arc segment satisfy:

[0027] d p <d q , and h 2p >h 2q

[0028] Where, dp Let d be the diameter at point p. q Let h be the diameter at point q. 2p Let h be the elevation difference at point p. 2q Let be the difference in elevation at point q.

[0029] Optionally, the second base arc region includes multiple arc segments, and the sag difference h2 of each arc segment decreases from the inside to the outside along the radial direction.

[0030] Optionally, the second base arc region includes at least three arc segments, and along the radial direction, the difference in elevation h between the outermost arc segment and the arc segment located in the radial direction is... 2外 The difference in sag h is less than that of the arc segment located at the innermost radial end. 2内 The difference in sag h2 between the other arc segments located between the two is less than 0.

[0031] Optionally, the first base arc region consists of one non-spherical arc segment, or it consists of multiple arc segments, including spherical arc segments and / or non-spherical arc segments.

[0032] Optionally, the second base arc region consists of a spherical arc segment or a non-spherical arc segment, or consists of multiple arc segments, including spherical arc segments and / or non-spherical arc segments.

[0033] The sag of an aspherical surface can be derived from the following expression for an aspherical surface:

[0034]

[0035] It is the expression of the curve of the aspherical generatrix on the xy plane, |y| is the sag value, c is the curvature of the basic sphere, Q is the aspherical coefficient, and A2i is the aspherical higher-order coefficient. Each point on the aspherical shape is obtained by rotating the curve around the y-axis. The aspherical surface uses the Q value, or the Q value is used in combination with the higher-order coefficient.

[0036] Optionally, the first base arc region includes a spherical arc segment, and the sag of the sphere is obtained by the following formula:

[0037] (xa) 2 +(yb) 2 =R 2

[0038] It is the expression of the curve of the generatrix of the sphere on the xy plane, where |y| is the sag value, (a,b) are the coordinates of the center of the circle, and R is the radius of curvature of the circle. Each point on the spherical shape is obtained by rotating the curve around the coordinate axis y.

[0039] Optionally, the sagitta h of the base sphere s The following formula is used to derive:

[0040]

[0041] Where, r s Let d be the radius of curvature of the base sphere, and d be the diameter.

[0042] Optionally, the radius of curvature of the first base arc region is 7.0 to 11.0 mm.

[0043] Optionally, the diameter of the first base arc region is 2.0–5.0 mm, or 2.5–4.5 mm, or 3.0–4.0 mm.

[0044] Optionally, the diameter of the second base arc region is 1.0–3.0 mm, or 1.0–2.5 mm, or 1.0–2.0 mm.

[0045] Terminology Definition

[0046] Unless otherwise specified, the following definitions apply to the terminology used in this specification.

[0047] The base curve (BC) is located at the very center of the orthokeratology lens. It is the inner surface of the optical zone and is used to compress and shape the anterior corneal surface. After reshaping, this area of ​​the cornea becomes the optical zone, which plays a role in optical imaging.

[0048] The reversal zone (RC) is the second region closely connected to the base curve zone. It serves to connect the base curve zone and the fitting zone, forming a gap between the orthokeratology lens and the anterior corneal surface, thus storing tears and promoting tear flow.

[0049] The Adaptation Arc (AC), also known as the Positioning Arc or Matching Arc, is located next to the Reversal Arc. This area matches the shape of the cornea and plays a role in positioning.

[0050] The peripheral arc zone (PC) is optional and is located at the outermost edge of the orthokeratology lens. It is closely connected to the fitting arc zone and is generally flatter than the fitting arc zone. It presents a certain upturn angle with the corneal surface to ensure the exchange and flow of tears and oxygen between the cornea and the periphery of the orthokeratology lens.

[0051] The radial width w refers to the width along the radial direction.

[0052] The term "basal sphere" refers to the sphere determined by the corneal K-value and myopia degree, with a radius of curvature of r = 337.5 / (K+D+F).

[0053] The terms “steep” and “flat” describe the magnitude of the equivalent radius of curvature of a lens. For example, in the context of this application, “steep” means that the absolute value of the equivalent radius of curvature of the lens is smaller than the absolute value of the radius of curvature of the base sphere, and “flat” means that the absolute value of the equivalent radius of curvature of the lens is larger than the absolute value of the radius of curvature of the base sphere. Attached Figure Description

[0054] Figure 1 This is a schematic diagram illustrating the method for calculating the equivalent radius of curvature. O is the vertex of the aspherical surface, and r... m Let d be the equivalent radius of curvature, h be the diameter at a point, h be the sag at a point (i.e., the perpendicular distance from that point to the vertex), and w be the radial width. Figure 1 The diagram shows the base arc region, therefore the diameter is equal to the radius;

[0055] Figure 2 This is a schematic diagram of the structure of an orthokeratology lens involved in a specific embodiment;

[0056] Figure 3 This is a schematic diagram illustrating the technical effects of the orthokeratology lens in a specific embodiment of the present invention;

[0057] Figure 4 This is a schematic diagram of a corneal reshaping lens in other embodiments, where the first and second base curve regions are composed of multiple arc segments;

[0058] Figure 5 This is a schematic diagram of a corneal reshaping lens in other embodiments, where the first base curve region consists of three arc segments. The uppermost curve closest to the x-axis represents the base sphere, and the three curves below represent specific embodiments of the invention. All three curves are progressively steeper than the base sphere, but η... mn Same, η ij different;

[0059] Figure 6 This is a schematic diagram of a corneal reshaping lens in other embodiments, where the second base curve region consists of three arc segments, wherein the three curves δ sm Same, δ pq different. Detailed Implementation

[0060] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0061] The orthokeratology lens of this embodiment is used to correct myopia and includes an inner surface facing the cornea of ​​the human eye when worn and an outer surface opposite to the inner surface. The inner surface includes a base curve region, a reversal curve region, a positioning curve region and a side curve region. Figure 2The diagram shown is a structural schematic of an orthokeratology lens according to this embodiment. In this diagram, 10 is the base curve region, 20 is the reversal curve region, 30 is the positioning curve region, and 40 is the edge curve region.

[0062] As mentioned above, after wearing orthokeratology lenses, the peripheral defocus that causes myopia in the human eye consists of two parts: peripheral defocus in the entrance pupil area and peripheral defocus in the bull's eye ring.

[0063] Peripheral defocus of the entrance pupil area refers to defocus within the pupillary area. The average human pupil diameter is 3-4 mm. In this region, the cornea adheres most tightly to the base curve, and the morphology of the reshaped cornea is essentially consistent with the base curve. To improve peripheral defocus of the entrance pupil area, in this embodiment, the central region of the base curve is designed with a smaller radius of curvature at the periphery and a progressively steeper surface. This allows the refractive power to increase with the aperture size, providing a controllable degree of myopia-reducing defocus for the human eye.

[0064] Peripheral defocus of the bull's eye ring refers to the significant peripheral defocus that occurs in the cornea after being reshaped by the inversion arc zone. This area of ​​the cornea is called the "bull's eye ring," and the resulting peripheral defocus is called peripheral bull's eye ring defocus. The magnitude of the peripheral bull's eye ring defocus depends on the traction force of the inversion arc zone on the central corneal epithelial cells, and the magnitude of this traction force depends on the sagittal difference of the inversion arc zone. The sagittal difference of the inversion arc zone refers to the difference between the starting and ending sagittal heights of the inversion arc zone (the sagittal difference of the inversion arc zone can also be understood as the height of the inversion arc zone along the optical axis). The starting point is the ending point of the base arc zone, i.e., the point at the outer edge of the base arc zone, the connection point between the base arc zone and the inversion arc, and the ending point is the starting point of the positioning arc (fitting arc). Sagittal height refers to the distance between the position of the point on the lens and the apex of the orthokeratology lens (…). Figure 3 The height difference between O in the middle.

[0065] The greater the sagittal difference in the base curve region, the greater the fluid force formed by the tear film between the lens and the cornea, the more corneal epithelial cells migrate to the periphery, and the steeper the reshaped corneal surface becomes. This results in an increase in refractive power as the aperture increases, providing the eye with controllable myopic defocus. To increase the sagittal difference in the base curve region, in this embodiment, the outermost portion of the base curve region is designed with a greater radius of curvature at the periphery than at the center.

[0066] like Figure 2As shown, in this embodiment, the base curve region 10 includes two regions: a first base curve region 1 and a second base curve region 2. The first base curve region 1 is the region located at the center of the orthokeratology lens and is circular. Alternatively, the first base curve region 1 may not be circular, for example, it may be elliptical or irregular in shape. The second base curve region 2 is located on the outer side of the first base curve region and adjacent to the reverse curve region 20, and is an annular region. Alternatively, the second base curve region 2 may not be an annular region, for example, it may be elliptical or irregular in shape.

[0067] The diameter of the first base arc region is 2.0–5.0 mm, preferably 2.5–4.5 mm, and more preferably 3.0–4.0 mm.

[0068] The first base arc region consists of one or more arc segments. When it consists of one arc segment, that arc segment is aspherical. When it consists of multiple arc segments, all of the arc segments can be spherical or aspherical, or they can include both spherical and aspherical arc segments. The curvature of the central portion of the first base arc region 1 is less than that of the peripheral portion.

[0069] The surface shape expression of the above-mentioned aspherical shape can be:

[0070]

[0071] It is the expression for the curve of the aspherical generatrix in the xy plane, where c is the curvature of the basic sphere, Q is the aspherical coefficient, and A... 2i The coefficients are higher-order terms of the aspherical surface. Each point on the aspherical surface is obtained by rotating the curve around the y-axis. The aspherical surface uses the Q value, or the Q value is used in combination with the higher-order terms.

[0072] Furthermore, the surface shape expression of the above spherical shape can be:

[0073] (xa) 2 +(yb) 2 =R 2 (2)

[0074] The above formula is the expression for the curve of the generatrix of the sphere on the xy plane, where (a,b) are the coordinates of the center of the circle and R is the radius of curvature of the circle.

[0075] As an alternative approach, the trend of curvature variation can be measured by the scaling factor η of the equivalent curvature radii of the central and peripheral portions. mn The scaling factor η is limited. mn <1. Where, η mn d is the ratio of the equivalent radii of curvature r at points m and n on the first base arc region, where point m is a point on the outer edge of the first base arc region (in this embodiment, it is the connection point with the second base arc region).m is the diameter of the first base arc region, point n is the point close to the center, d n = 0.01 mm:

[0076]

[0077] where r m is the equivalent curvature radius of point m, r n is the equivalent curvature radius of point n.

[0078] Refer to Figure 1 , the calculation method of the equivalent curvature radius is as follows:

[0079]

[0080] where d is the diameter of a certain point, h is the sagitta of a certain point, and r is the equivalent curvature radius of a certain point.

[0081] Note that the equivalent curvature radius is related to d and h, and actually describes the positional relationship. For example, taking a spherical arc segment as an example, its curvature radius is 7.0, the xy coordinates of the starting point are (2, 1), and the equivalent curvature radius of this point is r = ((2 * 2) 2 + 4 * 1 2 ) / (8 * 1) = 2.5.

[0082] The scale factor η mn can be 0.785 ≤ η mn < 1, preferably 0.887 ≤ η mn ≤ 0.999, more preferably 0.965 ≤ η mn ≤ 0.997.

[0083] Furthermore, if the first base arc region consists of at least two arc segments of spherical or aspherical shapes, the scale factor η ij can be used to further limit each arc segment. i and j are any two points on at least two arc segments, which can be any two points on the same arc segment or any two points on different arc segments, and satisfy di < dj. The scale factor η ij = r j / r i , η mn ≤ η ij < 1. As another method, the η ij of each arc segment can be different. In addition, the η ij of each arc segment can gradually change from the inside to the outside along the radial direction.

[0084] Through the above scale factors η mn and η ijThis allows us to define the curvature of the first base arc region as a gradually steepening trend. The curvature of each arc segment can differ from that of the others.

[0085] The diameter of the second base arc region can be 1.0 to 3.0 mm, preferably 1.0 to 2.5 mm, and more preferably 1.0 to 2.0 mm.

[0086] The second base arc region consists of one or more arc segments. When it consists of one arc segment, the arc segment can be spherical or aspherical. When it consists of multiple arc segments, all of the arc segments can be spherical or aspherical, or they can include both spherical and aspherical arc segments. The curvature of the portion of the second base arc region closer to the center is greater than that of the portion closer to the periphery.

[0087] Here, the surface shape expression of the aspherical surface in the second base arc region is the same as that in equation (1), and the surface shape expression of the spherical surface in the second base arc region is the same as that in equation (2).

[0088] As an alternative approach, the curvature variation trend of the second base arc region is determined by the scaling factor δ of the equivalent radius of curvature between the central and peripheral portions. sm Limited, scaling factor δ sm >1. δ sm The ratio of the radii of curvature r at points s and m is given by d, where s is the connection point between the second base arc region and the reverse arc region, and d is the radius of curvature r between points s and m. s Diameter of the base arc region:

[0089]

[0090] The proportionality factor δ sm It can be 1 < δ sm ≤2.239, preferably 1.001≤δ sm ≤1.960, more preferably 1.002≤δ sm ≤1.605.

[0091] Furthermore, if the second base arc region is composed of multiple spherical or aspherical arc segments, it can be scaled using a scaling factor δ. pq For each arc segment, further constraints are imposed: p and q are any two points on multiple arc segments, which can be any two points on the same arc segment or any two points on different arc segments, and satisfy d p <d q The above scaling factor δ pq =rq / rp, 1<δ pq ≤δ sm δ for each arc segment pq They can be different. Furthermore, the δ of each arc segment... pq It gradually changes radially from the inside out.

[0092] Through the above scaling factor δ sm and δ pq This allows us to define the curvature of the second base arc region as a gradually flattening trend. The degree of curvature between each arc segment can differ.

[0093] Technical effect

[0094] The mechanisms by which the base curve center and periphery of an orthokeratology (OK) lens reshape the cornea differ. Patent Document 1, which describes a base curve divided into multiple zones, aims to correct refractive errors while simultaneously correcting presbyopia; however, this structure has no effect on improving peripheral defocus. Patent Document 2, with its gradually steepening base curve design, improves peripheral defocus in the entrance pupil area, but does not improve peripheral defocus in the bull's eye ring. Patent Document 3, with its gradually flattening base curve design, improves peripheral defocus in the bull's eye ring, but reduces peripheral defocus in the entrance pupil area.

[0095] Figure 3 This is a schematic diagram illustrating the technical effect of the orthokeratology lens described in this invention. The horizontal axis represents the radius of the human pupil, and the vertical axis represents the distribution of refractive power after the human eye wears the orthokeratology lens. Figure 3 As shown, unlike the technologies in the aforementioned patent documents 1-3, the orthokeratology lens of the present invention, with its increasingly steep central region of the base curve, improves peripheral defocus in the entrance pupil area, while its increasingly flat outer region of the base curve area improves peripheral defocus in the bull's eye ring. Thus, using this orthokeratology lens simultaneously improves both peripheral defocus in the entrance pupil area and peripheral defocus in the bull's eye ring. Furthermore, the amount of peripheral defocus increases gradually with the radial increase of the aperture, without abrupt changes.

[0096] The above description uses a structure with two base arc regions as an example. However, the invention is not limited to this. The base arc region can also have a structure with more regions, such as an increasingly steep central region and an increasingly flat outer region. The central region and the outermost region are connected by one or more connecting regions, which act as transition zones between the central and outermost regions. Any base arc region that includes a structure that is initially steep and then becomes flat is within the scope of protection of this invention.

[0097] Figure 4 This is a schematic diagram of a corneal reshaping lens in other embodiments, where the first and second base curve regions are composed of multiple arc segments. In this diagram, 1 indicates that the arc segment belongs to the first base curve region, and 2 indicates that the arc segment belongs to the second base curve region. Figure 4In (a), the first base arc region is composed of a single arc segment, and the second base arc region is composed of a single arc segment. In (b), the first base arc region is composed of two arc segments, and the second base arc region is composed of a single arc segment. In (c), the first base arc region is composed of four arc segments, and the second base arc region is composed of two arc segments. In (d), the first base arc region is composed of two arc segments, and the second base arc region is composed of two arc segments.

[0098] Figure 5 This is a schematic diagram of a corneal reshaping lens with a first base curve region consisting of three arc segments, as described in another embodiment. In the diagram, the uppermost curve closest to the x-axis represents the base sphere, and the three lower curves represent three surface shapes of the first base curve region in this specific embodiment of the invention. All three are progressively steeper than the base sphere, but η... mn Same, η ij different.

[0099] Figure 6 This is a schematic diagram of a corneal reshaping lens in other embodiments, where the second base curve region consists of three arc segments. The three curves represent three surface shapes of the second base curve region. These three curves δ sm Same, δ pq different.

[0100] Some specific embodiments of the present invention are provided below, please refer to Tables 1-3 below.

[0101] Table 1. Example 1: Both the first and second base arc regions consist of one arc segment.

[0102] Table 2 shows that the first base arc region and / or the second base arc region in Example 2 consist of multiple arc segments.

[0103] In this invention, there are multiple possible combinations of specific implementation methods for the orthokeratology lens. Taking Table 2 as an example, the first base curve region can be implemented using any one of the implementation methods 1-3 in Table 2, and the second base curve region can be implemented using any one of the implementation methods 1-3 in Table 2, thus there are 9 possible combinations.

[0104] Table 3 shows that the first base arc region and / or the second base arc region in Example 3 consist of multiple arc segments.

[0105] As can be seen from the above embodiments, the first base arc region and the second base arc region can be composed of one or more arc segments, and can be a combination of spherical and aspherical surfaces, as long as the curvature of the central part of the first base arc region is less than the curvature of the outer part (η). mn <1), the curvature of the second base arc region near the center is greater than the curvature of the outer periphery (δ)sm >1).

[0106] Other embodiments provided in this application are described below. In the following description, parts that are the same as those described above are omitted or briefly described.

[0107] In this embodiment, such as Figure 2 As shown, the base arc region includes two regions, namely the first base arc region and the second base arc region from the center outwards.

[0108] The diameter of the first base arc region is 2.0–5.0 mm, preferably 2.5–4.5 mm, and more preferably 3.0–4.0 mm.

[0109] The first base arc region can consist of one or more arc segments. When it consists of one arc segment, that arc segment is aspherical. When it consists of multiple arc segments, all of the arc segments can be spherical, all of them can be aspherical, or they can be a combination of spherical and aspherical. The curvature of the central part of the first base arc region is less than that of the peripheral part.

[0110] The degree of curvature can be defined by the difference in elevation h1 between the base arc and the base sphere at the same diameter, where the difference in elevation h1 > 0.

[0111] h1 = h 1A -h S

[0112] Among them, h 1A h is the sag of the first base arc region. S The sag of the base sphere.

[0113] When the first base arc region consists of one arc segment, it is only necessary to calculate the sag difference at the diameter of that arc segment.

[0114] When the first base arc region consists of multiple arc segments, it is necessary to calculate the sag difference at the diameter of each arc segment.

[0115] The sag of an aspherical surface can be derived from the expression for an aspherical surface:

[0116]

[0117] It is the expression of the curve of the aspherical generatrix on the xy plane, |y| is the sag value, c is the curvature of the basic sphere, Q is the aspherical coefficient, and A2i is the aspherical higher-order coefficient. Each point on the aspherical shape is obtained by rotating the curve around the y-axis. The aspherical surface uses the Q value, or the Q value is used in combination with the higher-order coefficient.

[0118] The sag of a sphere can be derived from the expression for a sphere:

[0119] (xa) 2 +(yb)2 =R 2 (2)

[0120] It is the expression of the curve of the generatrix of the sphere on the xy plane, where |y| is the sag value, (a,b) are the coordinates of the center of the circle, and R is the radius of curvature of the circle. Each point on the spherical shape is obtained by rotating the curve around the coordinate axis y.

[0121] The sagitta h of the basic sphere s It can be derived from the following formula:

[0122]

[0123] Where, r s Where is the radius of curvature of the base sphere, and d is the diameter. When calculating the sag difference, it represents the difference in sag between the base arc region and the base sphere at the same diameter.

[0124] The diameter of the second base arc region can be 1.0 to 3.0 mm, preferably 1.0 to 2.5 mm, and more preferably 1.0 to 2.0 mm.

[0125] The second base arc region consists of one or more spherical or aspherical arc segments. The curvature of the central part of the second base arc region is greater than that of the outer part.

[0126] As an alternative, the degree of curvature is defined by the difference in elevation h2 between the base arc and the base sphere at the same diameter, wherein the difference in elevation h2 < 0.

[0127] h2=h 2A -h S

[0128] Among them, h 2A h is the sag of the second base arc region. S The sag of the base sphere.

[0129] When the second base arc region consists of one arc segment, it is only necessary to calculate the sag difference at the diameter of that arc segment.

[0130] When the second base arc region consists of multiple arc segments, it is necessary to calculate the sag difference at the diameter of each arc segment.

[0131] The method for calculating the sag is shown in equations (1) and (2).

[0132] Several specific embodiments derived from the ideas of this implementation method are given below.

[0133] Table 4. Parameter Examples for the First Base Arc Region

[0134]

[0135] Table 5. Parameter examples for the second base arc region.

[0136]

[0137] In this embodiment, there are multiple possible combinations of specific methods for using orthokeratology lenses. Taking Tables 4 and 5 above as examples, the first base curve region can be selected from any of the methods in Tables 4-4 above, and the second base curve region can be selected from any of the implementation methods in Tables 5-4 above, thus there are 16 possible combinations.

[0138] It should be noted that, in this embodiment, the specific implementation of each arc segment of the first base arc region and the second base arc region is not limited to those listed in Tables 4 and 5 above. In this embodiment, the first base arc region and the second base arc region can be composed of one or more arc segments, and can be a combination of spherical and non-spherical surfaces, as long as the sag difference h1 of the first base arc region is greater than 0 and the sag difference h2 of the second base arc region is less than 0. This helps to achieve the curvature of the central part of the first base arc region being less than the curvature of the peripheral part (h>0), and the curvature of the second base arc region near the center being greater than the curvature of the peripheral part (h<0).

[0139] Based on the concept of this embodiment, the following solution can be derived.

[0140] An orthokeratology lens includes an inner surface facing the cornea when worn and an outer surface opposite to the inner surface. The inner surface includes a base curve region located at the center and a reverse curve region located on the periphery of the base curve region. The base curve region includes: a first base curve region located at the center of the base curve region, wherein the sag difference h1 between the first base curve region and the base spherical surface at the same diameter is greater than 0; and a second base curve region located on the periphery of the first base curve region and adjacent to the reverse curve region, wherein the sag difference h2 between the second base curve region and the base spherical surface at the same diameter is less than 0.

[0141] Where h1=h 1A -h S h 1A h is the sag of any point in the first base arc region. S The sag of the base sphere; h2 = h 2A -h S h 2A h is the sag of the second base arc region. S The sag of the base sphere.

[0142] This technical solution allows for easy control to ensure that the curvature of the central portion of the first base arc region is less than that of the surrounding portions, while the curvature of the second base arc region near its center is greater than that of the surrounding portions. Thus, as... Figure 3 As shown and as mentioned above, it can improve the effectiveness of myopia control.

[0143] In this embodiment, preferably, the curvature of the central portion of the first base arc region is less than that of the peripheral portion; and the curvature of the central portion of the second base arc region is greater than that of the peripheral portion.

[0144] Optionally, the elevation difference of any arc segment increases from the inside to the outside along the radial direction. Specifically, any two points ij on any arc segment included in the first base arc region satisfy: d i <d j , and h 1i <h 1j .

[0145] Optionally, the first base arc region is composed of at least two arc segments, and the sag difference h1 at the diameter of each arc segment increases from the inside to the outside along the radial direction.

[0146] Optionally, the first base arc region includes at least three arc segments, with h at the diameter of the outermost arc segment along the radial direction. 1外 h is greater than the diameter of the arc segment located at the innermost radial end. 1内 For the diameter of the other arc segment located between the two, h1 > 0.

[0147] Optionally, the elevation difference of any arc segment decreases from the inside to the outside along the radial direction. Specifically, any two points pq on any arc segment included in the second base arc region satisfy: d p <d q , and h 2p >h 2q .

[0148] Optionally, the second base arc region includes multiple arc segments, and the sag difference h2 of each arc segment decreases from the inside to the outside along the radial direction.

[0149] Optionally, the second base arc region includes at least three aspherical or spherical arcs, with h at the diameter of the outermost arc segment along the radial direction. 2外 h is smaller than the diameter of the arc segment located at the innermost radial end. 1内 h2 < 0 at the diameter of the other arc segments located between the two.

[0150] Optionally, the first base arc region consists of one non-spherical arc segment, or it consists of multiple arc segments, including spherical arc segments and / or non-spherical arc segments.

[0151] Optionally, the second base arc region consists of a spherical arc segment or a non-spherical arc segment, or consists of multiple arc segments, including spherical arc segments and / or non-spherical arc segments.

[0152] The sag of an aspherical surface can be derived from the expression for an aspherical surface:

[0153]

[0154] It is the expression of the curve of the aspherical generatrix on the xy plane, |y| is the sag value, c is the curvature of the basic sphere, Q is the aspherical coefficient, and A2i is the aspherical higher-order coefficient. Each point on the aspherical shape is obtained by rotating the curve around the y-axis. The aspherical surface uses the Q value, or the Q value is used in combination with the higher-order coefficient.

[0155] The sag of a sphere can be obtained from the following formula:

[0156] (xa) 2 +(yb) 2 =R 2

[0157] It is the expression of the curve of the generatrix of the sphere on the xy plane, where |y| is the sag value, (a,b) are the coordinates of the center of the circle, and R is the radius of curvature of the circle. Each point on the spherical shape is obtained by rotating the curve around the coordinate axis y.

[0158] The sagitta h of the basic sphere s It can be derived from the following formula:

[0159]

[0160] Where, r s Let d be the radius of curvature of the base sphere, and d be the diameter.

[0161] The radius of curvature of the first base arc region can be 7.0 to 11.0 mm.

[0162] The diameter of the first base arc region can be 2.0–5.0 mm, or 2.5–4.5 mm, or 3.0–4.0 mm.

[0163] The diameter of the second base arc region can be 1.0–3.0 mm, or 1.0–2.5 mm, or 1.0–2.0 mm.

[0164] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An orthokeratology lens, the orthokeratology lens comprising an inner surface facing the cornea of ​​the human eye when worn and an outer surface opposite to the inner surface, the inner surface comprising a base curve region located at a center, a reversal curve region located peripherally to the base curve region, and a fitting curve region located peripherally to the reversal curve, characterized in that, The base arc region includes: The first base arc region is located at the center of the base arc region. The sag difference h1 between the first base arc region and the base sphere at the same diameter is greater than 0. The first base arc region is composed of one non-spherical arc segment, or multiple arc segments, including spherical arc segments and / or non-spherical arc segments. The sag difference h1 of the most central region of the first base arc region increases from the inside to the outside along the radial direction. The second base arc region is located on the outer side of the first base arc region and is adjacent to the reverse arc region. The sag difference h2 between the second base arc region and the base sphere at the same diameter is less than 0. The second base arc region includes an arc segment in which the sag difference h2 decreases from the inside to the outside along the radial direction. in, h 1A h is the sag of the first base arc region. S The sag of the base sphere; h 2A h is the sag of the second base arc region. S The sag of the base sphere, The basic spherical surface refers to the spherical surface determined by the corneal K-value and the degree of myopia, with a radius of curvature of r. s =337.5 / (K+D+F), where K is the corneal K-value, D is the myopia degree, and F is the adjustment factor. The sagitta h of the basic sphere s The following formula is used to derive: ； Where, r s Let d be the radius of curvature of the base sphere, and d be the diameter.

2. The orthokeratology lens according to claim 1, characterized in that, The curvature of the central portion of the first base arc region is less than that of the peripheral portion, such that the first scaling factor of the first base arc region satisfies the following relationship: or mn <1; ； Wherein, the first scaling factor η mn The ratio of the equivalent radii of curvature r at points m and n on the first base arc region, where point m is the outer edge of the first base arc region and point n is a point near the center, r m Let r be the equivalent radius of curvature at point m. n Let n be the equivalent radius of curvature at point n; The curvature of the central portion of the second base arc region is greater than that of the peripheral portion, such that the third scaling factor δ of the second base arc region... sm The following relationship must be satisfied: d sm >1; ； Where, δ sm The ratio of the equivalent radii of curvature r at points s and m, where s is the connection point between the second base arc region and the reverse arc region, and r... s Let r be the equivalent radius of curvature at point s. m Let m be the equivalent radius of curvature at point m. The method for calculating the equivalent radius of curvature at the above points is as follows: ； Where d is the diameter of the point, which is twice the vertical distance from the point to the central axis of the base arc region, h is the sag of the point, and r is the equivalent radius of curvature of the point.

3. The orthokeratology lens according to claim 1, characterized in that, Any two points i and j on any arc segment of the first base arc region satisfy: d i <d j , and h 1i <h 1j , Where, d i Let d be the diameter at point i. j Let h be the diameter at point j. 1i Let h be the elevation difference at point i. 1j Let be the difference in elevation at point j.

4. The orthokeratology lens according to claim 1, characterized in that, The first base arc region is composed of at least two arc segments, and the elevation difference h1 of each arc segment increases from the inside to the outside along the radial direction.

5. The orthokeratology lens according to claim 1, characterized in that, The first base arc region includes three or more arc segments, and along the radial direction, the difference in elevation h between the outermost arc segments is... 1外 The difference in sag h between the arc segments located at the innermost radial end and the arc segments located at the innermost radial end. 1内 The elevation difference h1 of the other arc segments located between the two is greater than 0.

6. The orthokeratology lens according to any one of claims 1-5, characterized in that, The second base arc region includes one or more arc segments, and any two points p and q on any arc segment satisfy: d p <d q , and h 2p >h 2q , Where, d p Let d be the diameter at point p. q Let h be the diameter at point q. 2p Let h be the elevation difference at point p. 2q Let be the difference in elevation at point q.

7. The orthokeratology lens according to any one of claims 1-5, characterized in that, The second base arc region includes multiple arc segments, and the sag difference h2 of each arc segment decreases from the inside to the outside along the radial direction.

8. The orthokeratology lens according to any one of claims 1-5, characterized in that, The second base arc region includes at least three arc segments, and along the radial direction, the difference in elevation h between the outermost arc segment and the arc segment located radially is... 2外 The difference in sag h is less than that of the arc segment located at the innermost radial end. 2内 The difference in sag h2 between the other arc segments located between the two is less than 0.

9. The orthokeratology lens according to claim 1, characterized in that, The second base arc region consists of a spherical arc segment or a non-spherical arc segment, or consists of multiple arc segments, including spherical arc segments and / or non-spherical arc segments.

10. The orthokeratology lens according to claim 9, characterized in that, The sag of an aspherical surface is derived from the following expression for an aspherical surface: ； It is the expression for the curve of the aspherical generatrix on the xy plane, |y| is the sag value, c is the curvature of the base sphere, Q is the aspherical coefficient, and A is the aspherical coefficient. 2i The coefficients are higher-order terms of the aspherical surface. Each point on the aspherical surface is obtained by rotating the curve around the y-axis. The aspherical surface uses the Q value, or the Q value is used in combination with the higher-order terms.

11. The orthokeratology lens according to any one of claims 1-5 and 9, characterized in that, The first base arc region and / or the second base arc region include spherical arc segments, and the sag of the sphere is obtained by the following formula: ； It is the expression of the curve of the generatrix of the sphere on the xy plane, where |y| is the sag value, (a, b) are the coordinates of the center of the circle, and R is the radius of curvature of the circle. Each point on the spherical shape is obtained by rotating the curve around the coordinate axis y.

12. The orthokeratology lens according to any one of claims 1-5, characterized in that, The radius of curvature of the first base arc region is 7.0~11.0 mm.

13. The orthokeratology lens according to any one of claims 1-5, characterized in that, The diameter of the first base arc region is greater than or equal to 2.0 mm and less than or equal to 5.0 mm.

14. The orthokeratology lens according to any one of claims 1-5, characterized in that, The diameter of the first base arc region is 2.5~4.5mm.

15. The orthokeratology lens according to any one of claims 1-5, characterized in that, The diameter of the first base arc region is 3.0~4.0mm.

16. The orthokeratology lens according to any one of claims 1-5, characterized in that, The diameter of the second base arc region is 1.0~3.0mm.

17. The orthokeratology lens according to any one of claims 1-5, characterized in that, The diameter of the second base arc region is 1.0~2.5mm.

18. The orthokeratology lens according to any one of claims 1-5, characterized in that, The diameter of the second base arc region is 1.0~2.0mm.

19. The orthokeratology lens according to claim 2, characterized in that, The curvature of the central portion of the first base arc region is less than that of the peripheral portion, making the curvature of the first base arc region gradually steeper. The curvature of the central portion of the second base arc region is greater than that of the peripheral portion, causing the curvature of the second base arc region to gradually flatten. The term "steep" refers to the fact that the absolute value of the lens's equivalent radius of curvature is smaller than the absolute value of the radius of curvature of the base sphere, while "flat" refers to the fact that the absolute value of the lens's equivalent radius of curvature is larger than the absolute value of the radius of curvature of the base sphere.

20. The orthokeratology lens according to claim 1, characterized in that, The base curve region is located at the very center of the orthokeratology lens. It is the inner surface of the optical zone and is used to compress the anterior corneal surface and shape it.

21. The orthokeratology lens according to claim 1, characterized in that, The inverted arc region is a second region closely connected to the base arc region, forming a gap between the orthokeratology lens and the anterior corneal surface, which serves to store tears and promote tear flow.

22. The orthokeratology lens according to claim 21, characterized in that, The matching arc area, which is adjacent to the reversal arc area, matches the shape of the cornea and plays a positioning role.

23. The orthokeratology lens according to claim 22, characterized in that, It also includes an edge arc area, located at the outermost edge of the orthokeratology lens, connected to the fitting arc area, which is flatter than the fitting arc area and is upturned relative to the corneal surface to ensure the exchange and flow of tears and oxygen between the cornea and the periphery of the orthokeratology lens.

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