Orthokeratology lens

Abstract

An orthokeratology lens, having a rear surface for shaping a corneal front surface. The rear surface comprises a base curve zone and a reverse curve zone. The radius of curvature of the base curve zone gradually decreases from the center to the periphery; and / or the radius of curvature of the reverse curve zone is smaller than the radius of curvature of the base curve zone and gradually decreases from inside to outside; and / or the zone of a predetermined width at the tail end of the base curve zone is configured as a transition curve zone, and the radius of curvature of the transition curve zone is smaller than the radius of curvature of the base curve zone and greater than the radius of curvature of the reverse curve zone. In this way, an optical area of the rear surface can be raised to increase the thickness of a central tear layer, thereby filling the area with tears.

Description

Orthokeratology lenses

[0001] This disclosure claims priority to Chinese patent application filed on January 15, 2025, with application number 202510061637.X and entitled "Orthokeratology Lens". Technical Field

[0002] This disclosure relates to an orthokeratology lens. Background Technology

[0003] Orthokeratology lenses, worn overnight, use mechanical pressure, lens movement, and the hydraulic pressure of tears to flatten the central curvature of the cornea. This temporarily reduces myopia and improves uncorrected visual acuity, allowing for better vision during the day without glasses. Simultaneously, the lenses create a defocus ring in the pericentric region of the cornea, which slows the progression of myopia, thus controlling its development.

[0004] Numerous studies have confirmed the positive effect of orthokeratology lenses in controlling the progression of myopia. Research indicates that compared to wearing regular eyeglasses, adolescents with myopia who wear orthokeratology lenses experience a significantly slower rate of axial elongation and their myopia progression is controlled to some extent. The overall effectiveness rate is approximately 70%. Some patients, after consistently wearing orthokeratology lenses for a period of time, have seen their myopia stabilize or even decrease to some degree.

[0005] Safety is a critical aspect of orthokeratology lenses. The base curve (optical zone) of an orthokeratology lens provides a template for corneal reshaping. It reshapes the cornea through central positive pressure and peripheral negative pressure. To improve efficiency, the lens sometimes compresses the tear film storage space beneath the lens. However, this increased efficiency is actually detrimental to corneal health. For example, when worn overnight, the lens may adhere to the cornea, making it difficult to move and remove in the morning. This can lead to corneal punctation, corneal epithelial detachment, and even more serious adverse events.

[0006] Therefore, it is necessary to improve the design of orthokeratology lenses to effectively enhance the safety of lens wearing. Summary of the Invention

[0007] One of the technical problems this disclosure aims to solve is how to design an orthokeratology lens that can improve the safety of lens wearing.

[0008] This disclosure provides an orthokeratology lens having a posterior surface for reshaping the anterior surface of the cornea. The posterior surface has a base curve region and a reverse curve region. The radius of curvature of the base curve region gradually decreases from the center to the periphery. And / or the radius of curvature of the reverse curve region is smaller than the radius of curvature of the base curve region and gradually decreases from the inside to the outside. And / or a region of a predetermined width at the end of the base curve region is designated as a transition curve region, the radius of curvature of the transition curve region is smaller than the radius of curvature of the base curve region and larger than the radius of curvature of the reverse curve region.

[0009] Optionally, the posterior surface parameters of the orthokeratology lens are configured such that the thickness of the tear film after the orthokeratology process stabilizes is within a first range. The first range is a range of values ​​determined so that the surface free energy of the tear film is not less than a first value and the cohesive force is not less than a second value. The posterior surface parameters include at least one of the aspherical characteristic parameter values ​​of the base arc region, the aspherical characteristic parameter values ​​of the reversal arc region, the width of the transition arc region, and the radius of curvature.

[0010] Optionally, the aspherical characteristic parameter value of the base arc region is configured to increase the sag of the base arc region by a third value.

[0011] Optionally, the eccentricity of the base arc region ranges from -0.45 to -1.25.

[0012] Optionally, the aspherical characteristic parameter value of the inversion arc region is configured to increase the tear film thickness by a third value.

[0013] Optionally, the eccentricity of the inverted arc region ranges from -0.20 to -0.60.

[0014] Optionally, the width and radius of curvature of the transition arc region are configured to increase the tear film thickness by a third value.

[0015] Optionally, the width of the transition arc region is between 0.1 mm and 0.3 mm, and the difference between the radius of curvature of the base arc region and the radius of curvature of the transition arc region is between 0.35 mm and 3.00 mm.

[0016] Optionally, the third value is 7μm to 10μm.

[0017] Optionally, the posterior surface also has a fitting arc region and a peripheral arc region. The fitting arc region includes a first fitting arc region and a second fitting arc region. The first fitting arc region is connected to the reverse arc region, and the second fitting arc region is connected to the peripheral arc region. The first fitting arc region is parallel to the corresponding area of ​​the cornea, and the second fitting arc region gradually moves away from the cornea from the inside to the outside.

[0018] Optionally, the distance between the end of the second fitting arc area and the cornea is between 5 μm and 40 μm.

[0019] Optionally, the radius of curvature of the second fitting arc region is 0.05 mm to 1.15 mm larger than that of the first fitting arc region; and / or the eccentricity of the second fitting arc region ranges from +0.20 to +0.90.

[0020] This disclosure designs the radius of curvature of the base arc region to gradually decrease from the center to the periphery; and / or designs the radius of curvature of the reversal arc region to be smaller than the radius of curvature of the base arc region, and to gradually decrease from the inside to the outside; and / or designates a region of predetermined width at the end of the base arc region as a transition arc region, the radius of curvature of the transition arc region being smaller than the radius of curvature of the base arc region and larger than the radius of curvature of the reversal arc region. In this way, the posterior surface optical region can be raised, increasing the thickness of the central tear film, thereby filling this region with tear fluid. Attached Figure Description

[0021] The above and other objects, features and advantages of this disclosure will become more apparent from the more detailed description of exemplary embodiments thereof taken in conjunction with the accompanying drawings, wherein like reference numerals generally denote like parts.

[0022] Figure 1 shows a simplified cross-sectional view of a conventional orthokeratology lens.

[0023] Figure 2 shows a simplified cross-sectional view of an orthokeratology lens according to an embodiment of the present disclosure.

[0024] Figure 3 shows a simplified cross-sectional view of an orthokeratology lens according to another embodiment of the present disclosure.

[0025] Figure 4 shows a simplified cross-sectional view of an orthokeratology lens according to another embodiment of the present disclosure.

[0026] Figure 5 shows a simplified cross-sectional view of an orthokeratology lens according to another embodiment of the present disclosure.

[0027] Figure 6 shows a simplified cross-sectional view of an orthokeratology lens according to another embodiment of the present disclosure.

[0028] Figure 7 shows a comparison of the matching fluorescence staining of the orthokeratology lens of this disclosure with that of a conventional orthokeratology lens. Detailed Implementation

[0029] Preferred embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0030] Figures 1 through 6 show only the posterior surface of an orthokeratology lens used to reshape the anterior surface of the cornea. Because this disclosure does not concern itself with the design of the anterior surface of the orthokeratology lens, it is omitted in the figures to avoid obstruction. Those skilled in the art will understand that this disclosure is suitable for any appropriate anterior surface design. For example, this disclosure is suitable not only for orthokeratology lenses worn at night but also for orthokeratology lenses worn during the day.

[0031] Furthermore, all the ranges of values ​​described in the text can include two endpoint values.

[0032] Figure 1 shows a simplified cross-sectional view of a conventional orthokeratology lens.

[0033] As shown in Figure 1, the posterior surface of an orthokeratology lens has four zones: the base curve (BC), followed by the reverse curve (RC), alignment curve (AC), and peripheral curve (PC). The base curve is located at the center of the lens. The base curve can also be referred to as the posterior surface optical zone. The reverse curve is adjacent to the base curve. The peripheral curve is adjacent to the alignment curve and is located at the outermost periphery of the lens.

[0034] The posterior surface of an orthokeratology lens can be broadly divided into a central region and a peripheral region. The base curve and reversal curve can be classified as the central region, while the fitting curve and peripheral curve can be classified as the peripheral region.

[0035] This disclosure proposes that by optimizing the design of the central region (base arc region and / or inversion arc region), the optical region (i.e., base arc region) can be slightly raised (i.e. lifted) to increase the thickness of the central tear layer, thereby filling the region with tears.

[0036] This disclosure also proposes that by optimizing the design of the surrounding area (e.g., the fitting arc area), a soft, seamless edge can be formed, allowing the microscopic tear film to be full and the tear exchange to be smooth and gentle.

[0037] In some preferred embodiments, both of the above-mentioned optimization designs can be used simultaneously to effectively improve the safety of lens wearing without compromising shaping efficiency.

[0038] I. Optimized design for the central area

[0039] The purpose of optimizing the design of the central region is to slightly raise the rear surface optical zone in order to increase the thickness of the central tear film.

[0040] When fitting orthokeratology lenses, optometrists or opticians may increase the overcorrection power based on the wearer's expectations for the reshaping effect and efficiency. This means reducing the base curve curvature by 0.25 to 1.00D, or increasing the base curve radius by 0.04 to 0.30mm. Taking the classic spherical four-curve VST design orthokeratology lens as an example, this will result in a reduction of the tear film in the reshaping area by 4μm to 18μm. If the tear film at the center apex of the cornea was originally 10μm, such parameter adjustments will cause contact and overpressure at the center apex of the lens, leading to corneal health problems.

[0041] Textbooks recommend an ideal tear film thickness of 5μm to 20μm for orthokeratology lenses. This recommendation is based on the design of older products and mainly considers the relationship between reshaping efficiency and corneal health. However, as mentioned earlier, in actual use, lenses may tend to sacrifice some corneal health to improve reshaping efficiency.

[0042] Therefore, optimizing the tear film is essential. The main purposes of optimizing the tear film are: firstly, to ensure the shape of the tear film, thereby creating an effective negative pressure and ensuring shaping efficiency; and secondly, to ensure the thickness of the tear film at all locations, so that the tear film under the microscope remains full and lubricated, ensuring the safety and health of the cornea.

[0043] To balance the above two objectives, this disclosure studies the shaping principle of orthokeratology lenses.

[0044] The reshaping force that causes corneal deformation in orthokeratology lenses primarily originates from the surface tension of the tear film beneath the lens. Therefore, quantitative calculation and optimized design of the tear film surface tension are crucial for orthokeratology lens design. Unfortunately, while the industry has long focused on tear pressure under orthokeratology lenses, a universally accepted testing method has yet to be established; assessments are currently limited to non-quantitative methods based on reshaping rate and patient comfort.

[0045] The surface tension of the tear film is determined by the gap between the cornea and the orthokeratology lens, which determines the shape of the tear film. If the tear film is too thin and dispersed, it cannot form concentrated intermolecular attraction within the tear film, resulting in insufficient negative pressure. Conversely, if the tear film is too thick and concentrated, the intermolecular attraction within the tear film has almost reached internal equilibrium, making it difficult to exert an influence on the cornea.

[0046] Specifically, the relationship between tear shape and plasticity can be understood using surface free energy and intermolecular cohesive forces.

[0047] The surface free energy of a liquid refers to the increase in the free energy of a system when its surface area increases by a unit, under constant temperature and pressure conditions. It is a type of potential energy reflecting the high-energy state of molecules at the liquid surface. From a molecular perspective, molecules inside a liquid experience symmetrical forces from surrounding molecules, resulting in lower energy. Surface molecules, however, experience asymmetrical forces and are in a relatively unstable, higher-energy state. Surface free energy measures this additional energy generated by the surface's presence, which affects the balance of intermolecular forces, and is calculated using the following formula: G8 = γA

[0048] Where G8 is the surface free energy, γ is the surface tension coefficient, and A is the liquid surface area.

[0049] For a given liquid composition and environmental conditions, the surface tension coefficient γ of the liquid remains constant, and the surface free energy of the liquid is determined by its surface area; the larger the surface area, the higher the surface free energy.

[0050] According to the second law of thermodynamics, a system tends to move towards its lowest energy state. To reduce surface free energy, a liquid tends to decrease its surface area. This is similar to how liquids always tend to minimize their surface area in surface phenomena. Liquids naturally have a tendency to release energy to reduce potential energy, i.e., to contract inwards, thus reducing their surface area. Without external forces, they will eventually contract into a perfect sphere.

[0051] Cohesion in liquids refers to the forces that attract liquid molecules to each other. It is a manifestation of intermolecular forces in liquids, causing liquid molecules to tend to aggregate and preventing them from separating. The cohesion of liquids mainly originates from van der Waals forces, which are the mutual attraction caused by the polarity or instantaneous polarity of molecules, including dispersion forces, inductive forces, and orientation forces.

[0052] a. Dispersion force formula:

[0053] Where I1 and I2 are the ionization energies of the two interacting molecules, α1 and α2 are their polarizabilities, and r is the distance between the molecular centers of mass.

[0054] b. Formula for induced force:

[0055] Where α is the polarizability, μ1 is the dipole moment of the polar molecule, and r is the distance between the centroids.

[0056] c. Orientation force formula:

[0057] Where μ1 and μ2 are the dipole moments of the two polar molecules, r is the distance between the centers of mass, k is the Boltzmann constant, and T is the thermodynamic temperature.

[0058] According to the formula, on a microscopic level, van der Waals forces are negatively correlated with the distance between molecules, while on a macroscopic level, the higher the degree of dispersion of a liquid, the weaker its inward contraction force.

[0059] For orthokeratology lenses, the cohesive effect of the tear film under the lens is the main source of negative pressure. The surface free energy of the tear film is the energy that the tear film can release onto the cornea, which determines the shaping effect; while the cohesive force of the tear film is the force that the tear film can exert on the corneal epithelium, which determines the shaping efficiency.

[0060] Therefore, when designing the tear film under orthokeratology lenses, it is necessary to comprehensively consider the tear film surface area, volume, and concentration to achieve suitable surface free energy and cohesion, in order to balance the reshaping effect and efficiency. Furthermore, since orthokeratology is a continuous and dynamic process, the central tear film layer gradually decreases until equilibrium is reached as reshaping progresses. Therefore, the morphology of the tear film under the lens during and after reshaping should be carefully considered. For example, when the orthokeratology lens is over-pressurized, the actual central area of ​​approximately 2mm to 4mm in diameter is almost devoid of tear film. After reshaping, this area will further expand, resulting in a smaller surface area, volume, and concentration of the tear film under the lens, meaning poorer surface free energy and cohesion. In this case, the reshaping relies mainly on the mechanical pressure generated by the direct contact between the lens and the cornea, which can easily cause corneal damage.

[0061] When the center of the orthokeratology lens is slightly lifted in an appropriate manner, a suitable tear film layer exists under the lens, regardless of whether the lens is in place or not. This ensures a certain level of surface area, volume, and concentration of the tear film under the lens, providing good surface free energy and cohesion, without compromising the shaping effect or efficiency. Furthermore, because the lens does not directly contact the cornea, mechanical pressure is reduced, effectively protecting corneal health.

[0062] In view of this, this disclosure proposes that the posterior surface parameters of an orthokeratology lens can be configured such that the tear film thickness after the reshaping process stabilizes (i.e., after the central tear film reaches equilibrium) falls within a first range. The first range is a numerical range determined to ensure that the surface free energy of the tear film is not less than a first value and the cohesive force is not less than a second value. That is, the first range is used to ensure that the tear film after the reshaping process stabilizes has good surface free energy and cohesive force. The first and second values ​​can be determined based on actual conditions (such as experimental data). As mentioned above, the surface free energy and cohesive force of the tear film are related to the shape of the tear film (such as surface area, volume, and concentration), while the tear film thickness can be considered a determining factor of the tear film shape when other conditions remain unchanged. Therefore, to ensure that the tear film after the reshaping process stabilizes has good surface free energy and cohesive force, a suitable tear film thickness (i.e., the first range) can be derived through formulas, and then the posterior surface parameters of the orthokeratology lens can be configured so that the tear film thickness after the reshaping process stabilizes falls within the first range.

[0063] The back surface parameters may include at least one of the aspherical characteristic parameter values ​​of the base arc region, the aspherical characteristic parameter values ​​of the reverse arc region, and the width and radius of curvature of the transition arc region. That is, the tear film thickness can be increased by configuring the base arc region, the reverse arc region, and the transition arc region individually or in combination.

[0064] The following examples illustrate three methods for elevating the rear surface optical zone (i.e., increasing the thickness of the central tear film). It should be understood that these three methods can be used individually or in combination. For example, any two or three methods can be used together.

[0065] Method 1: Design the base arc region as an aspherical surface with a negative e-value.

[0066] The base arc region can be designed as an aspherical surface, with aspherical characteristic parameters causing the radius of curvature of the base arc region to gradually decrease from the center to the periphery. The aspherical characteristic parameter value can refer to the e-value, where e represents eccentricity. A positive or negative e-value indicates whether an elongated or elliptical curve is used. A positive e-value indicates an elongated curve with the radius of curvature gradually increasing from the inside out, while a negative e-value indicates an elongated circular curve with the radius of curvature gradually decreasing from the inside out.

[0067] The purpose of designing the base curve region as aspherical with a negative e-value is to gradually decrease the radius of curvature of the base curve region from the center to the periphery. This increases the peripheral defocus area and amount without affecting the patient's visual experience. Simultaneously, compared to a spherical base curve design (or an aspherical design with a positive e-value), the optical zone sag (i.e., the base curve sag) of the lens is higher, effectively slightly raising the optical zone (i.e., arching the center of the lens). This allows for a slight increase in the thickness of the tear film between the lens and the cornea, for example, by approximately 5μm to 15μm. This helps promote tear exchange behind the lens after wearing orthokeratology lenses, maintaining corneal integrity and reducing corneal damage caused by the lenses.

[0068] Figure 2 shows a simplified cross-sectional view of an orthokeratology lens according to an embodiment of the present disclosure.

[0069] Referring to Figure 2, the dashed line corresponding to the BC area in the lens indicates that the BC area uses a spherical design, while the solid line corresponding to the BC area indicates that the BC area uses an aspherical design with a negative e-value. Compared to using a spherical design for the base curve area, designing the base curve area as aspherical with a negative e-value can increase the sag of the BC area and improve the thickness of the central tear film.

[0070] The aspherical feature parameter value (e-value) and the aspherical surface elevation have a certain functional relationship, which can be represented by the aspherical-elevation function. Therefore, for the desired elevation of region BC, the aspherical feature parameter value required to make region BC have that elevation can be calculated using the aspherical-elevation function.

[0071] In other words, the aspherical characteristic parameter value of the BC region can be determined based on the desired BC region sag. For example, the aspherical characteristic parameter value of the base arc region can be configured to increase the base arc region sag (i.e., the aspherical sag) by a third value. Increasing the base arc region sag by a third value is equivalent to increasing the tear film thickness by a third value. For example, the aspherical characteristic parameter value of the base arc region can be determined with the goal of increasing the base arc region sag by 5μm to 15μm. Increasing the base arc region sag by a third value can refer to increasing it by a third value compared to the base arc region sag corresponding to the original design.

[0072] The aspherical-sagittal function can be denoted as:

[0073] Where Sag(r) represents the sag of the aspherical surface, c is the curvature of the vertex of the aspherical surface (1 / radius of curvature of the vertex), and r is the half-chord length of the aspherical surface. When using this formula to calculate the sag of region BC, z is the sag of region BC, c is the curvature at the center of region BC, and r is the diameter of region BC / 2. The Q value and the e value have a square relationship with opposite signs.

[0074] The relationship between the Q value and the e value can be expressed by the following formula.

[0075] The BC region sag is positively correlated with the thickness of the central tear film. Based on the required BC region sag, the expected range of e-values ​​can be calculated using the above formula. For example, the range of e-values ​​for the BC region calculated to raise the posterior surface optical zone by 5μm to 15μm is -0.45 to -1.25, such as -0.45, -0.50, -0.55, -0.60, -0.65, -0.70, -0.75, -0.80, -0.85, -0.90, -0.95, -1.00, -1.05, -1.10, -1.15, -1.25, or any value within this range, or any value within any sub-range of the range -0.45 to -1.25. A sub-range can be, for example, a range formed by any two values ​​listed here as endpoints.

[0076] For example, when the e-value is selected as -0.45, the posterior surface optical zone is raised by 5 μm, which is slightly higher than the old generation of orthokeratology lens design, and the change in the central tear film thickness is not obvious for some prescriptions.

[0077] For example, when the e-value is selected as -1.25, the posterior surface optical zone is raised by 15 μm, which is more than the previous generation of orthokeratology lens designs, and the central tear film thickness reaches 35 μm for some prescriptions.

[0078] Furthermore, research has found that when the posterior surface optical zone is raised by approximately 7μm to 10μm, the elevation is more suitable compared to older orthokeratology lens designs, exhibiting reasonable elevation values ​​across all power levels. Therefore, the third value can be 7μm to 10μm. In other words, the e-value of the base curve region can be determined with the goal of raising the base curve region sagittal height by 7μm to 10μm. Specifically, a preferred range of e-values ​​for the base curve region corresponds to the range of e-values ​​that raise the base curve region sagittal height by 7μm to 10μm.

[0079] Method 2: Design the reversal arc region as an aspherical surface with a negative e-value.

[0080] Figure 3 shows a simplified cross-sectional view of an orthokeratology lens according to another embodiment of the present disclosure.

[0081] Referring to Figure 3, the dashed line corresponding to the RC zone in the lens indicates that the RC zone uses a spherical design, while the solid line indicates that the RC zone uses an aspherical design with a negative e-value. The BC zone can still use a spherical design. Compared to using a spherical design for the RC zone, designing the RC zone as aspherical with a negative e-value can slightly elevate the BC zone, thereby increasing the thickness of the central tear film. Therefore, the reversal arc zone can be designed aspherical, and the aspherical characteristic parameter value (i.e., the e-value) makes the radius of curvature of the reversal arc zone smaller than that of the base arc zone, gradually decreasing from the inside to the outside. This also achieves the purpose of elevating the BC zone and increasing the thickness of the central tear film.

[0082] The aspherical characteristic parameter value of the inversion arc region can be configured to increase the tear film thickness by a third value. This third value could be, for example, the 7μm to 10μm range mentioned above. Increasing the tear film thickness by a third value can mean increasing the tear film thickness by a third value compared to the original design.

[0083] For example, the aspherical characteristic parameter value of the inversion arc region can be configured to make the tear film thickness greater than or equal to the fourth value. The fourth value can be flexibly set according to the actual situation. For example, the central tear film thickness of a conventional orthokeratology lens and the cornea is about 10 μm. To increase the tear film thickness by about 5 μm to 15 μm compared to the conventional thickness, the fourth value can be set to about 15 μm to 25 μm.

[0084] Based on the desired increase in tear film thickness caused by the RC region through elevation of the BC region, the eccentricity of the RC region can be calculated to meet the requirements. For example, the eccentricity of the RC region can range from -0.20 to -0.60, such as -0.20, -0.25, -0.30, -0.35, -0.40, -0.45, -0.50, -0.55, -0.60, or any value within this range.

[0085] For example, when the e-value is selected as -0.20, the posterior surface optical zone is raised by 5 μm, which is slightly higher than the old generation of orthokeratology lens design, and the change in the central tear film thickness is not obvious for some prescriptions.

[0086] For example, when the e-value is selected as -0.60, the posterior surface optical zone is raised by 15 μm, which is more than the previous generation of orthokeratology lens designs, and the central tear film thickness reaches 35 μm for some prescriptions.

[0087] For example, when the preferred e value is -0.30 to -0.40, the posterior surface optical zone is raised by about 7μm to 10μm, which is more suitable than the previous generation of orthokeratology lens designs, and all diopters show a reasonable elevation value.

[0088] Method 3: Set the end of the base arc region as the transition arc region.

[0089] Figure 4 shows a simplified cross-sectional view of an orthokeratology lens according to another embodiment of the present disclosure.

[0090] Referring to Figure 4, a region of predetermined width at the end of the BC region can be designated as a transition curve (TC) region. For example, a width of approximately 0.1 mm to 0.3 mm at the end of the BC region can be designated as a transition curve region. That is, the width of the transition curve region can be between 0.1 mm and 0.3 mm, such as 0.10 mm, 0.15 mm, 0.20 mm, 0.25 mm, 0.30 mm, or any value within this range. The transition curve region can be divided into multiple transition curves, where the radius of curvature of some or all of the multiple transition curves is smaller than the radius of curvature of the base curve region and larger than the radius of curvature of the inversion curve region. By transforming a region of predetermined width at the end of the BC region into a TC region, the BC region can also be elevated to a certain extent, thereby increasing the thickness of the central tear film.

[0091] The width and radius of curvature of the transition arc region are configured to increase the tear film thickness by a third value. This third value could be, for example, the 7–10 μm mentioned above.

[0092] For example, the width and radius of curvature of the transition arc region can be configured such that the tear film thickness is greater than or equal to the fourth value. See the related description above for details on the fourth value.

[0093] When fabricating orthokeratology lenses, the width and radius of curvature of the TC zone can be calculated based on the desired increase in tear film thickness caused by lifting the BC zone. For example, the width of the transition arc zone is between 0.1 mm and 0.3 mm, and the difference between the radius of curvature of the base arc zone and the radius of curvature of the transition arc zone is between 0.35 mm and 3.00 mm.

[0094] For example, when the width of the TC region is set to 0.1 mm, the difference between the radius of curvature of the base arc region (i.e., the base arc region at the position connected to the transition region) and the radius of curvature of the transition arc region can be selected from 0.70 mm to 3.00 mm; when the width of the TC region is set to 0.2 mm, the difference between the radius of curvature of the base arc region and the radius of curvature of the transition arc region can be selected from 0.40 mm to 1.80 mm; when the width of the TC region is set to 0.3 mm, the difference between the radius of curvature of the base arc region and the radius of curvature of the transition arc region can be selected from 0.35 mm to 1.40 mm.

[0095] According to clinical data, when the corneal reshaping lens was improved by the above three methods, and the thickness of the central tear film under the lens was increased by 5-15 μm, a full tear film under the lens could be observed by fluorescence staining. During the 12-month observation period, the patient's wearing comfort was good, and the reshaping efficiency was not impaired due to the increase in the thickness of the central tear film under the lens.

[0096] Furthermore, when the central tear film thickness under the microscope exceeds 35 μm, the reshaping efficiency of the orthokeratology lens is significantly reduced. Improvements using the three methods mentioned above, or combinations thereof, cannot compensate for the reduced reshaping efficiency caused by the excessive increase in the central tear film thickness. Therefore, when increasing the tear film thickness using the three methods mentioned above, or combinations thereof, the limitation should be ensuring that the central tear film thickness under the microscope does not exceed 35 μm.

[0097] In small-scale trials, the above three methods can be used individually or in combination. Verification has shown that the following examples with different parameter combinations exhibit similar, improved fit characteristics, shaping efficiency, and comfort:

[0098] a. The base arc region has an e value of -0.45, -0.55, or -0.70;

[0099] b. The value of e in the inversion region is -0.20, or -0.30, or -0.40;

[0100] c. The width of the transition zone is 0.20 mm, and the radius of curvature is the base arc radius minus 0.40 mm or 0.60 mm.

[0101] It should be understood that, based on the optimized design described above, even with additional overcorrection, there will be no overpressure or corneal health problems. Therefore, the orthokeratology lens of this disclosure can refer to an orthokeratology lens with additional overcorrection.

[0102] II. Optimization Design for Surrounding Areas

[0103] The matching arc area can adopt a dual matching arc design to form a soft, seamless edge curve with the surrounding arc areas.

[0104] The fitting arc area includes a first fitting arc area and a second fitting arc area. The first fitting arc area is the fitting arc area near the center of the lens, and it connects with the reverse arc area. The first fitting arc area is designed to be parallel to the corresponding area of ​​the cornea. The second fitting arc area is the fitting arc area near the edge of the lens, and it connects with the peripheral arc area. The second fitting arc area is designed to gradually move away from the cornea from the inside out, so as to form a soft, seamless edge lift with the peripheral arc area.

[0105] The peripheral arc area of ​​an orthokeratology lens typically has a fixed width, such as 0.3–0.5 mm. Its radius of curvature determines the edge upturn of the lens, thus affecting tear exchange under the lens, lens mobility, and even comfort. This disclosure designs the second fitting arc area to gradually move away from the cornea from the inside out, allowing the second fitting arc area to merge with the peripheral arc area into an ultra-wide edge upturn. This ultra-wide edge upturn is softer and has no obvious transition, thereby ensuring adequate tear production and smooth tear exchange under the lens.

[0106] For example, the distance between the end of the second fitting arc region (the location where it connects with the peripheral arc region) and the cornea can be between 5 μm and 40 μm. This can be achieved by changing the radius of curvature of the second fitting arc region to create an edge curl at a predetermined distance (e.g., 5 μm to 40 μm) from the cornea, or by designing the second fitting arc region as an aspherical surface. Optionally, both methods can be used simultaneously to create this edge curl at the predetermined distance from the cornea.

[0107] When the radius of curvature of AC2 is changed and / or AC2 is set to aspherical so that the end of the second fitting arc region forms an edge curvature at a predetermined distance from the cornea, the radius of curvature and / or eccentricity of AC2 can be calculated according to the value of the predetermined distance.

[0108] According to clinical data, when the orthokeratology lens was modified in the above way to increase the tear film thickness at the end of the second fitting arc by 5μm to 40μm, a thinner microscopic tear film could be observed in the second fitting arc by fluorescence staining. During the 12-month observation period, the patients had good wearing comfort and the lens fit was not changed due to the design modification.

[0109] Based on the above design principles, this disclosure also conducted clinical trials to verify the effectiveness of the design. The results showed that by improving the central and peripheral tear film layers, the safety of orthokeratology lenses can be effectively enhanced, reducing the occurrence of device-related adverse events by 34%, which overturns the previous understanding of tear film layers in orthokeratology lenses.

[0110] In summary, increasing the tear film thickness in the central and peripheral regions using the methods described above can effectively improve the safety of orthokeratology lenses without compromising their reshaping efficiency.

[0111] Figure 5 shows a simplified cross-sectional view of an orthokeratology lens according to another embodiment of the present disclosure.

[0112] Referring to Figure 5, AC1 represents the first fitting arc region, and AC2 represents the second fitting arc region. The radius of curvature of AC2 can be set to be greater than that of AC1, and the radius of curvature of AC2 is 0.05mm to 1.15mm larger than that of AC1. In this way, the end of the second fitting arc region can form an edge warp between 5μm and 40μm.

[0113] Figure 6 shows a simplified cross-sectional view of an orthokeratology lens according to another embodiment of the present disclosure.

[0114] Referring to Figure 6, AC2 can be set to an aspherical surface, and the eccentricity can range from +0.2 to +0.9. In this way, the end of the second fitting arc region can also form an edge warp between 5μm and 40μm.

[0115] This disclosure relates to detailed optimizations of the lens and even the tear film under the lens, which can improve the tear film status of the central shaping area and the peripheral fitting area, making the tear film layer distribution under the lens full and the exchange sufficient and gentle, thereby improving the safety of lens wearing.

[0116] Figure 7 shows a comparison of the matching fluorescence staining of the orthokeratology lens of this disclosure with that of a conventional orthokeratology lens.

[0117] Figure 7 shows a tear fluorescein staining image of the orthokeratology lens of this disclosure on the left, and a tear fluorescein staining image of a conventional orthokeratology lens on the right. As shown in the left view of Figure 7, in the fitting arc area (area C), the first fitting arc area (the part within the darker dashed circle) shows a darker color, indicating that there is less tear film in this area; the second fitting arc area (the part outside the darker dashed circle) shows a slightly brighter color, indicating that there is slightly more tear film in this area.

[0118] Comparing the left and right views in Figure 7, it can be seen that the optimized tear film under the lens exhibits a smooth transition with no clear boundaries between areas. Furthermore, clinical trial results show that the orthokeratology lens of this disclosure optimizes tear film distribution and exchange, significantly reducing the incidence of common adverse reactions, such as corneal pilaris, conjunctivitis, keratitis, corneal abrasion, and corneal injury, by 26% to 63%, indicating that this disclosure has a significant effect on improving the safety of orthokeratology lenses.

[0119] The orthokeratology lens according to this disclosure has been described in detail above with reference to the accompanying drawings.

[0120] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A corneal reshaping lens having a posterior surface for reshaping the anterior surface of the cornea, said posterior surface having a base curve region and a reverse curve region, characterized in that, The radius of curvature of the base arc region gradually decreases from the center to the periphery; and / or The radius of curvature of the inverted arc region is smaller than that of the base arc region, and gradually decreases from the inside to the outside; and / or The region with a predetermined width at the end of the base arc region is designated as the transition arc region. The radius of curvature of the transition arc region is smaller than that of the base arc region and larger than that of the reverse arc region.

2. The orthokeratology lens according to claim 1, characterized in that, The posterior surface parameters of the orthokeratology lens are configured such that the thickness of the tear film after the orthokeratology process stabilizes is within a first range. The first range is a range of values ​​determined so that the surface free energy of the tear film is not less than a first value and the cohesive force is not less than a second value. The posterior surface parameters include at least one of the aspherical characteristic parameter values ​​of the base arc region, the aspherical characteristic parameter values ​​of the reversal arc region, the width of the transition arc region, and the radius of curvature.

3. The orthokeratology lens according to claim 1, characterized in that, The aspherical characteristic parameter value of the base arc region is configured to increase the sag of the base arc region by a third value.

4. The orthokeratology lens according to claim 3, characterized in that, The eccentricity of the base arc region ranges from -0.45 to -1.

25.

5. The orthokeratology lens according to claim 1, characterized in that, The aspherical characteristic parameter value of the inverted arc region is configured to increase the tear film thickness by a third value.

6. The orthokeratology lens according to claim 4, characterized in that, The eccentricity of the inverted arc region ranges from -0.20 to -0.

60.

7. The orthokeratology lens according to claim 1, characterized in that, The width and radius of curvature of the transition arc region are configured to increase the tear film thickness by a third value.

8. The orthokeratology lens according to claim 7, characterized in that, The width of the transition arc region is between 0.1 mm and 0.3 mm. The difference between the radius of curvature of the base arc region and the radius of curvature of the transition arc region is between 0.35 mm and 3.00 mm.

9. The orthokeratology lens of any one of claims 3 to 8, wherein, The third value is 7μm to 10μm.

10. The orthokeratology lens of claim 1, wherein , The rear surface also has an adaptation arc area and a peripheral arc area. The matching arc region includes a first matching arc region and a second matching arc region. The first fitting arc region is connected to the reverse arc region, and the second fitting arc region is connected to the peripheral arc region. The first fitting arc area is parallel to the corresponding area of ​​the cornea, and the second fitting arc area gradually moves away from the cornea from the inside to the outside.

11. The orthokeratology lens of claim 10, wherein , The distance between the end of the second fitting arc area and the cornea is between 5 μm and 40 μm.

12. The orthokeratology lens of claim 11, wherein , The radius of curvature of the second fitting arc region is 0.05 mm to 1.15 mm larger than the radius of curvature of the first fitting arc region; and / or The eccentricity of the second fitting arc region ranges from +0.20 to +0.90.

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