Orthokeratology lens design method and orthokeratology lens

Abstract

The embodiment of the invention provides an orthokeratology lens design method, an orthokeratology lens comprises an adaptive arc area, and the method comprises the following steps: S10, acquiring curvature distribution of a cornea adaptive girdle area of naked eyes of a testee, the cornea adaptive girdle area corresponding to the adaptive arc area; s20, establishing a coordinate system by taking the cornea center as an original point or a pole, and obtaining a mapping relation between the curvature of the cornea adaptive annular zone and different angles according to curvature distribution; s30, obtaining the curvature change rate of the cornea adaptive annular zone according to the mapping relation, and determining a curvature change rate threshold value; s40, determining a plurality of annular sectors according to the curvature change rate of the cornea adaptive annular zone and a curvature change rate threshold value; and S50, determining curvature distribution of an area corresponding to the annular sector in an adaptive arc area of the orthokeratology lens according to the curvature distribution of the annular sector. The fitting degree and the shaping effect of the corneal contact lens and the cornea are improved, the correction effect is improved, and the lens wearing stability can be improved.

Description

Technical Field

[0001] This application relates to the technical field, and in particular to a method for designing orthokeratology lenses and orthokeratology lenses. Background Technology

[0002] Orthokeratology lenses are rigid, high-oxygen-permeable lenses used in corneal reshaping surgery. Through continuous nighttime wear, they apply gentle pressure to the cornea, flattening the central cornea and reducing its curvature. This temporarily alters the eye's refractive power, improving distance vision for clear daytime vision. Simultaneously, the design of orthokeratology lenses steepens the mid-peripheral cornea, creating myopic optical defocus in the peripheral retina and slowing the progression of myopia. These two effects work together to correct myopia and slow its progression.

[0003] Orthokeratology lenses typically consist of a base curve, a reversal curve, an adaptation curve, and a peripheral curve, distributed from the center to the periphery. The adaptation curve, which directly contacts the peripheral corneal region, is responsible for lens positioning and stability, and is crucial for the reshaping effect. A good corneal reshaping effect can only be achieved when the lens is centered on the cornea (central deviation ≤0.5mm) and has good mobility (1-2mm movement during blinking), avoiding excessive tightness, looseness, misalignment, or dislodgement. Therefore, the design of the adaptation curve is of paramount importance.

[0004] Currently, there are two fitting curve designs: conventional and toroidal. In the conventional design, the fitting curve of the lens is rotationally symmetrical relative to the central axis of the lens. This design is generally used for patients with a relatively regular anterior corneal surface morphology (corneal astigmatism less than 1.0D). In the toroidal design, the curvature of the fitting curve of the lens differs in the horizontal and vertical directions. Therefore, this design is generally used for patients with more pronounced peripheral astigmatism (corneal astigmatism greater than 1.0D). Lens fitters can customize the horizontal and vertical curvature of the fitting curve according to the specific amount of astigmatism in the patient's cornea to achieve a good fitting effect.

[0005] The two designs described above provide good fit and shaping effects for corneas with regular, symmetrical astigmatism. However, the anterior surface of the cornea in normal individuals is mostly irregular, such as asymmetrical bowtie shape (32.1%) and irregular shape (7.1%). For these irregular astigmatic corneal shapes, existing lens designs may not fit well in different meridian directions, leading to problems such as lens misalignment and leakage, thus failing to achieve a good shaping effect.

[0006] Patent document CN114740635A discloses a four-quadrant asymmetric orthokeratology lens. While this design improves adaptability to asymmetric corneas, the four quadrants have the same coverage area, and the meridians are fixed as four mutually perpendicular axes. The abrupt geometric transitions in the transition area can easily cause localized detachment of the lens from the anterior corneal surface. Existing technologies, when dealing with asymmetric or irregular corneas, still suffer from problems such as fixed axis divisions, abrupt structural transitions, insufficient adhesion, and unstable positioning, which can easily lead to lens misalignment and affect myopia correction and control effects.

[0007] Another patent document, CN118963000A, discloses a four-axis asymmetric orthokeratology lens. The axial division of its adaptation arc zone is customized based on the average sagittal height of the corneal circumference, which improves its ability to handle irregular corneas to some extent. However, this design still has significant limitations: First, the method for determining the flat (steep) meridian is limited to areas outside the 90° range of the angle between the flattest (steepest) meridians, failing to fully consider the corneal morphological characteristics within the 90° range, resulting in the absence of meridians in key areas. Second, its curvature design relies on a gradual, smooth transition between selected meridians. However, because the selected meridians fail to accurately reflect key characteristic points in corneal curvature changes (such as extreme points, inflection points, etc.), the transition shape cannot truly reproduce the complex curvature change patterns of the corneal circumference (e.g., non-linear curvature fluctuations: initially gentle, then drastic, or exhibiting a wave dynamic of steepness followed by flatness and then steepness again). Therefore, despite the use of a transition design, due to the inherent deviation in meridian positioning, it is still difficult to achieve an ideal fit between the lens and the cornea. Summary of the Invention

[0008] In view of the above, this application provides a method for designing orthokeratology lenses and an orthokeratology lens to solve at least one problem existing in the prior art.

[0009] In a first aspect, one embodiment of this application provides a method for designing an orthokeratology lens, the orthokeratology lens including an adaptation arc area, the method comprising the following steps: S10, Obtain the curvature distribution of the corneal adaptation ring area of ​​the test subject's naked eye, wherein the corneal adaptation ring area corresponds to the adaptation arc area; S20, establish a coordinate system with the corneal center as the origin or pole, and obtain the mapping relationship between the curvature of the corneal fitting ring area and different angles according to the curvature distribution; S30, obtain the curvature change rate of the corneal fitting ring zone according to the mapping relationship, and determine the curvature change rate threshold; S40, determine several annular sectors based on the rate of curvature change of the corneal fitting ring zone and the rate of curvature change threshold; S50, determine the curvature distribution of the region corresponding to the annular sector in the fitting arc area of ​​the orthokeratology lens based on the curvature distribution of the annular sector.

[0010] In conjunction with the first aspect of this application, in an optional embodiment, step S20 further includes: S21, set multiple semi-meridians with a predetermined angle step size, and determine the curvature of each semi-meridian in the corneal fitting ring area; S22, determine the mapping relationship between the curvature of the different semimeridians and the angle of the semimeridian based on the curvature of the multiple semimeridians in the corneal fitting ring area.

[0011] In conjunction with the first aspect of this application, in an optional embodiment, step S22 further includes: performing a function fitting on the mapping relationship between the curvature of the different semimeridians in the corneal fitting ring area and the angle of the semimeridian, to obtain the functional relationship between the curvature of the different semimeridians in the corneal fitting ring area and the angle of the semimeridian.

[0012] In conjunction with the first aspect of this application, in an optional embodiment, step S30 further includes: taking the first derivative of the functional relationship to obtain the rate of change of curvature of the corneal fitting ring region.

[0013] In conjunction with the first aspect of this application, in an optional embodiment, in step S40, the rate of curvature change of the corneal fitting ring area is compared with a curvature change rate threshold, and the corneal fitting ring area is divided into a rapid curvature change area and / or a slow curvature change area according to the comparison result.

[0014] In conjunction with the first aspect of this application, in an optional embodiment, step S40 further includes: S41, determine a sub-regional semimeridian in the region of rapid curvature change and / or the region of slow curvature change, and divide the region of rapid curvature change and / or the region of slow curvature change into sub-ring sectors based on the sub-regional semimeridian.

[0015] In conjunction with the first aspect of this application, in an optional embodiment, the angle of the semimeridian of the rapidly changing curvature sub-region is determined according to the following formula: in, This represents the functional relationship between the curvature of different semi-meridians in the region of rapid curvature change and the angle of that semi-meridian; The angle of the semimeridian in the sub-region of the slowly changing curvature is determined according to the following formula: in, This represents the functional relationship between the curvature of different semi-meridians in the region of slowly changing curvature and the angle of that semi-meridian.

[0016] In conjunction with the first aspect of this application, in an optional embodiment, the functional relationship is a polynomial function.

[0017] In conjunction with the first aspect of this application, in an optional embodiment, step S50 further includes: S51, determine the curvature distribution of the portion of the orthokeratology lens corresponding to the sub-ring sector based on the curvature distribution of the sub-ring sector.

[0018] Secondly, embodiments of this application provide a corneal reshaping lens, including an adaptation arc area, which is obtained using any of the design methods described above.

[0019] The orthokeratology lens design method and lens provided in this application dynamically identify the curvature change characteristics of the corneal fitting ring zone. Based on the curvature change rate and threshold of the corneal fitting ring zone, an annular sector is determined within the corneal fitting ring zone. Differentiated fitting arc zoning structures are constructed as needed. Based on the curvature change rate of the corneal fitting ring zone, an orthokeratology lens with an asymmetrical axial structure is dynamically constructed. This precise matching design improves the fit and shaping effect between the contact lens and the cornea, enhancing not only the corrective effect but also the stability of lens wear and reducing the risk of corneal damage after lens wear. It is particularly suitable for patients with significant corneal asymmetry, such as irregular corneas, elliptical corneas, and patients with high astigmatism.

[0020] Based on the actual curvature distribution in both rapidly and slowly changing curvature zones, multiple sub-regional semimeridians are flexibly set to divide the cornea into smaller sub-ring sectors. This achieves high-precision fitting of complex curvature change patterns, further improving the fit between the orthokeratology lens fitting arc and the cornea, thereby enhancing the stability of orthokeratology lens wear and improving refractive correction. This design method can meet the personalized needs of different wearers, and is especially suitable for irregularly shaped corneas (such as asymmetrical bowtie corneas, irregular corneas, etc.), thus having a wider range of applications.

[0021] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the structure of an orthokeratology lens provided in one embodiment of this application; Figure 2 This is a cross-sectional schematic diagram of an embodiment of the orthokeratology lens of this application; Figure 3 This is a schematic diagram of a corneal reshaping lens design method provided in an embodiment of this application; Figure 4 This is a schematic diagram showing the overlap of the orthokeratology lens and the cornea in one embodiment of this application; Figure 5 This is a schematic diagram of the orthokeratology lens and corneal partitions in one embodiment of this application; Figure 6 This is a schematic diagram of the orthokeratology lens and local sub-regions of the cornea in one embodiment of this application. Detailed Implementation

[0023] To make the technical solutions and beneficial effects of this application more apparent and understandable, the technical solutions in the embodiments of this application are clearly and completely described below by listing specific examples. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0025] It should be noted that the terms "first," "second," etc., used in this application may be used to describe various elements, but these elements are not limited by these terms. These terms are used only to distinguish one element from another, and not to describe a specific order or sequence. The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, not excluding the presence or addition of one or more other features.

[0026] This application provides a method for designing an orthokeratology lens, which is a circular arc-shaped lens. Please refer to [reference needed]. Figures 1-2 The lens body comprises multiple annular regions extending from the center to the edge: the base curve region 1, the reverse curve region 2, the adaptor curve region 3, and the peripheral curve region 4. The base curve region 1 is an arc-shaped structure located in the central region of the lens body, serving as the central optical and treatment area to flatten the corneal surface. The center 5 of the base curve region 1 corresponds to the center of the cornea. The reverse curve region 2 surrounds the base curve region 1 in a narrower annular structure, used to collect central tear fluid, promoting the flattening of the anterior corneal surface by the base curve region 1. The adaptor curve region 3 surrounds the reverse curve region 2, together forming a slightly wider annular structure. Both adhere closely to the cornea, serving to fix the lens in place.

[0027] The peripheral arc region 4 surrounds the adapting arc region 3 in a narrow ring structure, and its slightly raised edges help facilitate tear exchange. The base arc region 1, the reverse arc region 2, the adapting arc region 3, and the peripheral arc region 4 are integrally molded.

[0028] like Figure 3 As shown, the design method of the orthokeratology lens according to an embodiment of this application includes the following steps: S10, Obtain the curvature distribution of the corneal fitting ring zone in the subject's uncorrected eye. The corneal fitting ring zone corresponds to the aforementioned fitting arc zone. The corneal curvature distribution refers to the measured curvature value of a specific area on the anterior surface of the cornea, such as the central 3mm area. Different locations within the corneal fitting ring zone have different curvature values, thus constituting the curvature distribution of the corneal fitting ring zone. Optionally, a corneal topography instrument is used to measure the corneal tangential curvature map (distribution) of the subject's uncorrected eye, thereby obtaining the curvature distribution of the corneal fitting ring zone. The obtained corneal tangential curvature map is divided into the fitting ring zone, the first ring zone, the second ring zone, and the third ring zone, which correspond to the fitting arc zone 3, the base arc zone 1, the reverse arc zone 2, and the peripheral arc zone 4 of the orthokeratology lens, respectively. The corneal tangential curvature map calculates the curvature of each point on the cornea using the true curvature center of the differential arc segment of that point. It reflects the accurate and true radius of curvature at every point on the corneal surface, making it more sensitive to local curvature changes and precisely reflecting the morphology of the peripheral cornea. The number of fitting ring zones corresponds to the number of fitting arc zones in orthokeratology lenses.

[0029] By setting the center of the orthokeratology lens concentrically with the center of the cornea, such as Figure 4 As shown, the location and extent of the corneal fitting ring area corresponding to the fitting arc area of ​​the orthokeratology lens can be obtained. In the figure, the area enclosed by circle 21 represents the cornea, and the area enclosed by the dashed line represents the orthokeratology lens. During the design, the two are overlapped. 22 is the base arc area of ​​the lens, 23 is the reverse arc area of ​​the lens, the shaded part 24 represents the part where the corneal fitting ring area overlaps with the fitting arc area of ​​the orthokeratology lens, and 25 is the peripheral arc area of ​​the lens.

[0030] S20: Establish a coordinate system with the corneal center as the origin or pole. Based on the curvature distribution of the corneal fitting ring area obtained in step S10, obtain the mapping relationship between the curvature of the corneal fitting ring area and different angles. For example... Figure 5As shown, a polar coordinate system is established with the corneal center as the pole and the ray extending horizontally to the right from the pole as the polar axis, with the counterclockwise direction as positive. Optionally, a rectangular coordinate system can be used instead of the polar coordinate system. In the coordinate system, different positions of the corneal fitting ring area correspond to one or more curvature values. Based on the curvature values ​​at different positions and the angles at those positions, a mapping relationship between the curvature of the corneal fitting ring area and different angles can be established. This mapping relationship includes the mapping relationship between the curvature value dataset at different positions and the corresponding angle sequence, or the functional relationship between the curvature values ​​at different positions and the corresponding angles.

[0031] Step S20 further includes the following steps: S21, multiple semimeridians are set with predetermined angular steps, and the curvature of each semimeridian in the corneal fitting ring area is determined. For example... Figure 5 As shown, multiple semimeridians are defined with an angular step size of θ. A semimeridian refers to a ray running from the center of the cornea to the corneal limbus. Optionally, 0 < θ ≤ 5°. Taking θ = 1° as an example, 360 corneal semimeridians can be identified. The average curvature of each semimeridian within the corneal annulus region is used as the curvature of that semimeridian within the corneal annulus region. Multiple points are obtained within segments 26 and 27 of each semimeridian within the corneal annulus region at intervals of distance step size d. The average curvature of these multiple points is calculated and used as the curvature k of each semimeridian within the corneal annulus region. Optionally, 0 < d ≤ 0.2 mm.

[0032] Taking d = 0.1mm as an example, on line segment 26, one point is taken at every step of 0.1mm, for a total of m points. The curvature values ​​of each point are denoted as k1, k2, k3, ..., km. The average value is calculated as the curvature of this semimeridian in the corneal fitting ring area.

[0033] If there are 360 ​​semimeridians, and each semimeridian segment corresponds to a curvature value, a total of 360 curvature values ​​can be obtained.

[0034] S22. Determine the mapping relationship between the curvature of each semimeridian and its angle based on the curvature of the semimeridian within the corneal aptome zone. The curvature of each semimeridian within the corneal aptome zone is denoted as the curvature set K, K = {k1, k2, ..., kS}. The angle of the semimeridian corresponding to each curvature value is denoted as the angle set B, B = {θ1, θ2, ..., θS}. S is the number of semimeridians. Establish the mapping relationship between K and B.

[0035] Optionally, this mapping relationship is a functional relationship. A function is fitted to the mapping relationship between the curvature of different hemimeres in the corneal adaptation ring area and the angle of that hemimere, obtaining the functional relationship between the curvature of different hemimeres in the corneal adaptation ring area and the angle of that hemimere. Optionally, this functional relationship is a polynomial function or an aspherical function. Polynomial fitting is performed using the curvature set K and the angle set B.

[0036] Where a0, a1, ..., an are polynomial coefficients, n is the number of terms, θ represents the semimeridian angle, and K(θ) represents the curvature.

[0037] By substituting the curvature set K and the angle set B into the polynomial function above, the coefficients of each polynomial can be obtained.

[0038] Taking n=3 as an example, the polynomial coefficients can be obtained. , , , Therefore, the functional relationship between the curvature of the corneal fitting ring zone and different angles can be obtained. : like Figure 5 As shown, curve 31 represents the curvature function. By inputting any angle, you can obtain the curvature value corresponding to the corneal fitting ring area.

[0039] S30: Obtain the curvature change rate of the corneal fitting ring zone according to the mapping relationship in step S20, and determine the curvature change rate threshold. Optionally, perform approximate differentiation on the curvature set K and the angle set B to obtain the curvature change rate of the corneal fitting ring zone. Approximate differentiation operations include forward difference, backward difference, or central difference, etc.

[0040] Optional, for functional relations By performing first-order derivative calculations and taking the absolute value, the rate of change of curvature in the corneal fitting ring zone is obtained. This represents the rate of change of curvature: like Figure 5 As shown, curve 32 represents the absolute value of the rate of curvature change. To distinguish the speed of curvature change, a curvature change rate threshold T is determined, where T is the average rate of curvature change of the S semimeridians in the corneal fitting ring region. like Figure 5 As shown, curve 33 represents the threshold T.

[0041] S40, several annular sectors are determined based on the rate of curvature change of the corneal adaptation ring area and the curvature change rate threshold. The rate of curvature change of the corneal adaptation ring area is compared. Based on the comparison results with the curvature change rate threshold T, the corneal fitting ring area is determined as a region of rapid curvature change and / or a region of slow curvature change. The area was designated as a region of rapid curvature change, indicating that the corneal curvature in this area changes drastically. The area is designated as a region of slow curvature change, indicating that the corneal curvature in this region changes relatively gently.

[0042] like Figure 5 As shown, based on the intersection of curves 32 and 33, the corneal adaptation arc area C3 is divided into several annular sectors. The intersection point here is... The solution has several solutions, and the semimeridian at each intersection point divides the corneal fitting ring area into several sectors. Figure 5 Central region C1 is The annular sector represents the area of ​​rapid curvature change in the corneal fitting ring zone; Figure 5 Central region C2 is The annular sector represents the area with a gradual change in curvature within the corneal aptor ring zone.

[0043] S50, determine the curvature distribution of the region corresponding to the annular sector in the fitting arc area of ​​the orthokeratology lens based on the curvature distribution of the annular sector. Set the inner surface curvature of several semimeridians in the fitting arc area of ​​the orthokeratology lens to be consistent with the average curvature of the semimeridian corresponding to the corneal fitting annular zone. Preferably, the curvature distribution at the boundary between each annular sector and other regions in the lens fitting arc area is smoothly transitioned.

[0044] The orthokeratology lens design method of this application dynamically identifies the curvature change characteristics of the corneal fitting ring zone. Based on the curvature change rate and threshold of the corneal fitting ring zone, it determines the ring sector within the corneal fitting ring zone and constructs a differentiated fitting arc zone structure as needed. Based on the curvature change rate of the corneal fitting ring zone, it dynamically constructs an orthokeratology lens with an asymmetrical axial structure. This precise matching design improves the fit and shaping effect between the contact lens and the cornea, enhancing not only the corrective effect but also the stability of lens wear and reducing the risk of corneal damage after lens wear. It is particularly suitable for patients with significant corneal asymmetry, such as irregular corneas, elliptical corneas, and patients with high astigmatism.

[0045] In one embodiment of this application, step S40 further includes: S41, determine the sub-regional semimeridian in the region of rapid curvature change and / or slow curvature change, and divide the sub-ring sector according to the sub-regional semimeridian in the region of rapid curvature change and / or slow curvature change. 43, determine the sub-regional semimeridian in the region of rapid curvature change based on the mapping relationship between the curvature distribution and different angles, and divide the sub-ring sector accordingly. For example... Figure 6 As shown, the rapidly changing curvature zone C1 is defined by semimeridians 41 and 42 and the corneal fitting ring zone. The curvature of each semimeridian in the rapidly changing curvature zone is denoted as the curvature set ka, ka = {k1, k2, ..., kSa}, and the angle of the semimeridian corresponding to each curvature value is denoted as the angle set Ba, Ba = {θ1, θ2, ..., θSa}, where Sa is the number of semimeridians defined in the rapidly changing curvature zone with an angle step of θ. By establishing the mapping relationship between ka and Ba, the mapping relationship between the curvature distribution of the rapidly changing curvature zone of the corneal fitting ring zone and different angles can be obtained.

[0046] Optionally, this mapping relationship can be a functional relationship, such as a polynomial function. A function fit is performed on the mapping relationship between the curvature of different semimeridians in the rapidly changing curvature region and the angle of that semimeridian to obtain the functional relationship between the curvature of different semimeridians in the rapidly changing curvature region and the angle of that semimeridian. The function relationship was obtained using the function fitting method described above, which will not be repeated here.

[0047] The angle of the semimeridian in the sub-region of the rapidly changing curvature zone is determined by the following formula: in, This represents the functional relationship between the curvature of different semimeridians in a region of rapid curvature change and the angle of that semimeridian. In other words, the semimeridians in sub-regions of the rapidly changing curvature region are functions of... A solution where the second derivative is zero.

[0048] Optionally, an approximate differentiation operation is performed on the mapping relationship between the curvature set ka and the angle set Ba, and the sub-regional semimeridian is determined based on the solution where the second derivative is zero. The finite difference method is used for the approximate differentiation operation.

[0049] Based on the mapping relationship between the curvature distribution in the region of slowly changing curvature and different angles, a semi-meridian 45° is determined within the region of slowly changing curvature. For example... Figure 6As shown, the slowly changing curvature region C2 is defined by semimeridians 42 and 44 and the corneal fitting ring region. The curvature of each semimeridian in the slowly changing curvature region is denoted as the curvature set kb, kb = {k1, k2, ..., kSb}, and the angle of the semimeridian corresponding to each curvature value is denoted as the angle set Bb, Bb = {θ1, θ2, ..., θSb}, where Sb is the number of semimeridians defined in the rapidly changing curvature region with an angle step of θ. By establishing the mapping relationship between Kb and Bb, the mapping relationship between the curvature distribution of the slowly changing curvature region of the corneal fitting ring region and different angles can be obtained.

[0050] Optionally, an approximate derivative operation is performed on the mapping relationship between the curvature set kb and the angle set Bb, and the sub-regional semimeridian is determined based on the solution with a first derivative of zero.

[0051] Optionally, this mapping relationship can be a functional relationship, such as a polynomial function. By performing function fitting on the mapping relationship between the curvature of different semimeridians in the slowly changing curvature region and the angle of that semimeridian, the functional relationship between the curvature of different semimeridians in the rapidly changing curvature region and the angle of that semimeridian can be obtained. The function relationship was obtained using the function fitting method described above, which will not be repeated here.

[0052] The angle of the semimeridian in a sub-region with slowly changing curvature is determined by the following formula: in, This represents the functional relationship between the curvature of different semimeridians in a region of slowly changing curvature and the angle of that semimeridian. In other words, the semimeridians within a sub-region of the slowly changing curvature are functions of... A solution with a first derivative of zero.

[0053] For regions where curvature changes slowly, there exists... This refers to a situation where the corneal curvature reaches an extreme value. This indicates that the corneal curvature in this area either increases first and then decreases, or decreases first and then increases, showing fluctuations in the direction of curvature change. By setting more semimeridians and zones, the fit of the lens to the adaptation arc area can be improved when the corneal curvature fluctuates.

[0054] Optionally, the mapping relationship between the curvature of the corneal fitting ring area and different angles can be used as the mapping relationship between the curvature of the rapidly changing curvature area and different angles. The mapping relationship between the curvature of the corneal fitting ring area and different angles can be used as the mapping relationship between the curvature of the slowly changing curvature area and different angles.

[0055] Step S50 further includes: S51, determine the curvature distribution of the portion of the orthokeratology lens corresponding to the sub-ring sector based on the curvature distribution of the sub-ring sector. On the inner surface of the fitting arc area of ​​the orthokeratology lens corresponding to the sub-ring sector, set the curvature at the semi-meridian of the defined sub-section of the inner surface to be consistent with the average curvature of the same semi-meridian of the sub-ring sector of the corneal fitting ring area.

[0056] The rapidly changing curvature zone within the corneal fitting ring represents a steeper area of ​​the test subject's cornea. By supplementing the extreme points corresponding to semimeridians in the rapidly changing curvature zone and identifying the semimeridians corresponding to the inflection points of curvature changes in the slowly changing curvature zone, a more accurate description of the nonlinear curvature transition pattern is achieved. Compared to existing technologies that only determine meridians outside 90° and simply smooth the transition between meridians, this application fully considers the local fluctuation characteristics of corneal curvature changes (such as the "fluctuation" pattern of steepening then flattening and then steepening again), making the sagittal difference between the posterior surface of the lens and the anterior surface of the cornea smaller. This design results in a more uniform tear film distribution, effectively avoiding local leakage or pressure.

[0057] By flexibly setting multiple sub-regional semimeridians through the actual distribution of regions with rapid and slow curvature changes, and dividing them into smaller sub-ring sectors, high-precision fitting of complex curvature change patterns is achieved. This further improves the fit between the orthokeratology lens fitting arc area and the cornea, thereby enhancing the stability of orthokeratology lens wear and improving refractive correction. This design method can meet the personalized needs of different wearers, and is especially suitable for irregular corneal shapes (such as asymmetrical bowtie corneas, irregular corneas, etc.), thus having a wider range of applications.

[0058] Embodiments of this application also provide an orthokeratology lens, such as... Figures 1-2 As shown, it includes an adaptation arc region 3, which is obtained using the design method described in any of the above embodiments. The orthokeratology lens body includes multiple annular regions from the center to the edge: a base arc region 1, a reverse arc region 2, an adaptation arc region 3, and a peripheral arc region 4.

[0059] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0060] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for designing an orthokeratology lens, the orthokeratology lens including an adaptation arc area, the method comprising the following steps: S10, Obtain the curvature distribution of the corneal adaptation ring area of ​​the test subject's naked eye, wherein the corneal adaptation ring area corresponds to the adaptation arc area; S20, establish a coordinate system with the corneal center as the origin or pole, and obtain the mapping relationship between the curvature of the corneal fitting ring area and different angles according to the curvature distribution; S30, obtain the curvature change rate of the corneal fitting ring zone according to the mapping relationship, and determine the curvature change rate threshold; S40, determine several annular sectors based on the rate of curvature change of the corneal fitting ring zone and the rate of curvature change threshold; S50, determine the curvature distribution of the region corresponding to the annular sector in the fitting arc area of ​​the orthokeratology lens based on the curvature distribution of the annular sector.

2. The orthokeratology lens design method according to claim 1, wherein step S20 further comprises: S21, set multiple semi-meridians with a predetermined angle step size, and determine the curvature of each semi-meridian in the corneal fitting ring area; S22, determine the mapping relationship between the curvature of the different semimeridians and the angle of the semimeridian based on the curvature of the multiple semimeridians in the corneal fitting ring area.

3. The orthokeratology lens design method according to claim 2, wherein step S22 further comprises: The mapping relationship between the curvature of the different semimeridians in the corneal adaptation ring area and the angle of the semimeridian is obtained by function fitting.

4. The orthokeratology lens design method according to claim 3, wherein step S30 further comprises: The curvature change rate of the corneal fitting ring zone is obtained by taking the first derivative of the functional relationship.

5. The corneal reshaping lens design method according to claim 1, in step S40, the curvature change rate of the corneal fitting ring area is compared with the curvature change rate threshold, and the corneal fitting ring area is divided into a curvature rapid change area and / or a curvature slow change area according to the comparison result.

6. The orthokeratology lens design method according to claim 5, wherein step S40 further comprises: S41, determine a sub-regional semimeridian in the region of rapid curvature change and / or the region of slow curvature change, and divide the region of rapid curvature change and / or the region of slow curvature change into sub-ring sectors based on the sub-regional semimeridian.

7. The orthokeratology lens design method according to claim 6, wherein the angle of the semimeridian of the rapidly changing curvature sub-region is determined according to the following formula: in, The curvature of different semimeridians in the rapidly changing curvature region is a functional relationship with the angle of that semimeridian; the angle of the semimeridians in the slowly changing curvature region is determined according to the following formula: in, This represents the functional relationship between the curvature of different semi-meridians in the region of slowly changing curvature and the angle of that semi-meridian.

8. The orthokeratology lens design method according to claim 3, characterized in that, The functional relationship is a polynomial function.

9. The method for designing orthokeratology lenses according to claim 6, characterized in that, Step S50 further includes: S51, determine the curvature distribution of the portion of the orthokeratology lens corresponding to the sub-ring sector based on the curvature distribution of the sub-ring sector.

10. An orthokeratology lens, comprising an adaptation arc area, characterized in that, The adaptive arc region is obtained using the design method described in any one of claims 1-9.

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