Orthokeratology contact lens

Abstract

The utility model relates to an orthokeratology contact lens which comprises an inner surface with a rear optical area, the rear optical area is constructed and arranged to correct the vision of the cornea of the eyes of a wearer, the rear optical area is provided with a central circular area (1a) and an annular area (1b), and the annular area (1b) extends outwards in the radial direction from the end of the central circular area (1a). In a cross-section of the orthokeratology contact lens (L), the central circular region (1a) and the annular region (1b) conform to a curvature path of a continuous polynomial shape, in which:-the central circular region (1a) has a spherical radius or a radius of eccentricity (e-value) between 0 and 1, and-the annular region (1b) has a radius of curvature, and-the central circular region (1a) has a spherical radius or a radius of eccentricity (e-value) between 0 and 1, and-the annular region (1b) has a radius of curvature (e-value) between 0 and 1. The radius of curvature gradually increases from the end of the central circular region (1a) to the end of the rear optical region in a non-linear manner, increasing the distance from the reference curve.

Description

TECHNICAL FIELD

[0001] The present utility model relates to an orthokeratology contact lens, which is made to precisely correct the vision of the wearer's eye, accurately correct the refractive state of the eye, and optimize the amount of midperipheral refraction to effectively control myopia. BACKGROUND

[0002] Orthokeratology or Ortho-k uses specially designed and fitted rigid contact lenses of reverse geometry to reshape the corneal epithelium of the cornea to improve vision. Orthokeratology (OK) lenses are also known as reverse geometry lenses, which refer to lenses that are adjacent to or follow an optical zone with a smaller radius of curvature. The two coupled curves form an apical portion at a circular junction, which induces a fluid dynamic force that causes changes in epithelial cells.

[0003] These fluid dynamic suction forces induce a ring of epithelial cells accumulation, which, in combination with the central lens pressure, creates a flat central corneal area and a steep midperipheral area. In fact, a flat or less curved surface means less diopter and thus less myopic defect correction. At the same time, the steep ring of the midperipheral portion means a more curved shape, thus a higher refractive degree. These peripheral visual changes are the reason for the reduction in the axial length growth of myopic children. Numerous scientific experiments have shown that the visual signals produced by the reshaped cornea, including ocular aberrations and defocus, play a crucial role in slowing down the progression of myopia. Today, orthokeratology lenses produce these signals only in relation to the total amount or correction. Therefore, the higher the correction, the more visual signals are used for myopia treatment, and when low myopia is corrected, the signals are weakened in order to achieve good myopia control effect.

[0004] The optical zone is defined as the central area of the lens. The curvature of the front surface of the lens is chosen to achieve the desired lens power after being placed on the wearer's eye. The curvature of the central back surface, inner surface or back surface of the contact lens is called the base curve, i.e. the central back surface (inner surface) curve of the contact lens. The measurement of the base curve is actually the measurement of the radius of curvature of the sphere used to manufacture the lens, and in orthokeratology, the lens is selected to achieve the desired epithelial shaping.

[0005] Even the shape of a normal, untouched cornea is close to aspheric, which is generally flat towards its periphery. Orthokeratology (OK) lenses are usually designed to have a single aspheric or aspherical surface; that is, the inner surface of the lens is formed by connecting a plurality of spherical curves having different radii of curvature extending from the end of the so-called optical zone towards the edge. To correct myopia, the radius of curvature in the optical zone located in the back surface or inner surface in contact with the eye is just greater than the final radius of curvature finally obtained on the shaped cornea. In fact, this radius of curvature is calculated by adding an additional value, called the "Jessen Factor" or "Compression Factor", which is between 0.75 and 1.50 D (0.15 to 0.30 mm) to the final desired corneal radius. Once the lens is applied to a given cornea, the difference in the radii of curvature of the two surfaces (cornea and contact lens) will result in a separation, space, distance or measured height calculated in axial mode at the end of the optical zone. This height at the end of the optical zone is generated only as a result of the intended correction and is given directly, not monitored. That is, orthokeratology lenses for correcting low myopia have a shorter back optic zone radius of curvature (BOZR) than lenses for high myopia. Therefore, orthokeratology lenses using the aspheric optical zone in the prior art, when the myopia correction is high, the shaped cornea can produce a greater peripheral defocus, and unfortunately, in the case of low myopia, the shaped cornea can produce a very small peripheral defocus, poorly controlling and ineffective in the treatment of early low myopia.

[0006] The aspheric base curve in the prior art can work well to adjust the amount of refractive correction, but since the radius of curvature is only determined for central refractive correction, it can only provide appropriate visual signals for children with high myopia to stop axial length growth, making it ineffective for the treatment of early low myopia.

[0007] After Chen C. published his scientific paper in 2022, several patents claimed the benefits of aspheric optical zones for orthokeratology.

[0008] Aspheres can be described by the conic section defined by the aspherical radius of curvature and by a parameter that measures the surface eccentricity (asphere). The conic section obtained by cutting the cone with a plane includes oblate ellipses and prolate ellipses, hyperbolas, and parabolas. Another suitable parameter is the vertex radius of the ellipse and its eccentricity. They are defined as a second order equation where the vertex radius is R0 and the eccentricity is "e". The vertex radius is the radius of the circle that is tangent to the vertex portion of the conic section, and "e" represents the variation of this curve from the vertex portion. An aspherical prolate surface with the same R0 has a smaller sagittal height at the same distance from the axis than a spherical surface. Likewise, a higher height or separation of the end of the ring from the corneal surface and the optical zone will cause the next curve of the ortho-k lens, the so-called reverse curve, to have a shorter radius of curvature to compensate for this height, thus creating a pronounced peripheral molding and better control of the axial growth of the eye of a myopic child.

[0009] As examples, CN106291977A, CN112147796A, CN113671723A, CN113671724A, CN115793279A, and US2022291524A1 feature ortho-k lenses whose optical zone is aspherical.

[0010] In addition to the previous patent literature, CN215986770U includes aspherical designs that fit the peripheral curve or the peripheral curve. It is also possible that all the lens curves will be aspherical, as shown in US40196795A by El Hage.

[0011] The basic principle is to induce greater separation from the edge of the optical zone to the underlying cornea where the lens is applied. This increases the distance to the underlying corneal region, which is filled with tears and is called the tear reservoir. This enhanced tear reservoir increases the molding of the mid-peripheral epithelium, resulting in higher peripheral defocus and better myopia control.

[0012] While the use of aspherical base curves can achieve more significant amounts of defocus, it will overcorrect the central refractive error and not achieve adequate visual comfort for the patient.

[0013] In addition, the aspherical shape of the optical zone changes the central cornea in a pattern that is not desirable, resulting in an overcorrection of the refractive error of the eye. As a result, the visual cues emitted can accelerate the progression of myopia, causing vision problems and discomfort.

[0014] The intention of increasing the thickness of the tear film at the end of the optical zone is disclosed in WO2018234666A1, which proposes to divide the back optical zone into two spherical portions, making the radius of the adjacent circular zones flatter (larger) than the radius of the inner central zone. The result of this structure provides an unstable and irregular correction of the refractive error of the eye, since the angle generated between the two spherical curves in the case of low myopia causes discomfort and non-uniform refractive correction. Furthermore, since this design overcorrects in low myopia, it is necessary to compensate the central spherical zone by making it steeper, thus generating a so-called "central island" or central zone that provides the patient with double vision and halos. Making the design unsuitable for the correction of low myopia.

[0015] Therefore, it is necessary to provide an alternative technical solution to the prior art that covers the blank found in the prior art by providing a orthokeratology contact lens that overcomes the aforementioned drawbacks and therefore provides better and effective control of myopia, accurately correcting the central refractive error, while generating an increase in the corneal curvature of the intermediate peripheral portion, thus generating the amount of defocus in a precisely controlled manner. Utility model content

[0016] To this end, the utility model relates to an orthokeratology contact lens for the eye of a wearer, the orthokeratology contact lens comprising an inner surface having a back optical zone for facing or being in contact with the eye of the wearer, wherein the back optical zone has a central circular zone and at least one annular zone radially extending outwardly from the end of the central circular zone, around a geometric center axis of the lens.

[0017] Contrary to the orthokeratology contact lenses of the prior art, in the orthokeratology contact lens of the utility model, in a cross-section of the orthokeratology contact lens taken along a plane comprising the geometric center axis, the central circular zone and the at least one annular zone conform to a continuous polynomial-shaped curvature path in a characterizing manner:

[0018] - the central circular zone is aspherical, the aspherical having an eccentricity or e-value between 0 and 1 (i.e. low aspherical) and a vertex axial radius, and

[0019] - the at least one annular zone has a curvature radius that gradually increases in a progressive manner, rather than linearly, from the end of the central circular zone to the end of the back optical zone.

[0020] The central circular zone and the at least one annular zone join to form the so-called back optical zone.

[0021] For an embodiment, the diameter of the central circular area is 0.50 mm to 3.00 mm.

[0022] According to an embodiment, in said cross section, the end of the back optical zone has a height or sagittal distance with respect to an imaginary reference sphere on which said back optical zone is disposed, between 30 microns and 250 microns, preferably between 20 microns and 220 microns, wherein said imaginary sphere is an extension / elongation of the vertex radius of curvature of the central circular area.

[0023] The vertex curved surface of the lens has a vertex radius of curvature in the range of 7.00 mm to 10.00 mm.

[0024] For an embodiment of the above, the back optical zone has a diameter in the range of 4.00 mm to 5.5 mm, preferably in the range of 4.00 mm to 4.5 mm, and the above height or sagittal distance is in the range of 30 microns to 100 microns.

[0025] For an alternative embodiment, the back optical zone has a diameter of 7 mm, and the above height or sagittal distance is in the range of 60 microns to 250 microns.

[0026] In an embodiment, the at least one annular area has a conical shape.

[0027] According to an embodiment, the radius r at each given point on the above continuous polynomial-shaped curvature path is given by the following formula: a Following the formula:

[0028]

[0029] where r is the radius with respect to the geometric center axis of the lens, x is a coefficient factor (e value), and y is the distance from the geometric center axis of the lens, wherein x is in the range of 1 to 2 for the central area and in the range of 0 to 8 for the annular area.

[0030] In an embodiment of this, x is in the range of 0 to 8 for the at least one annular area.

[0031] According to an embodiment, the above height or sagittal distance and the additional height or sagittal distance of the end of the central circular area with respect to the above imaginary reference sphere are calculated by the following formula:

[0032]

[0033] where r1 is the axial radius of the central circular area or of the at least one annular area in said cross section, r athe axial radius of the cornea of the eye of the wearer, x is a coefficient factor, and y is the distance from the geometric center axis of the lens.

[0034] For some embodiments, y is in the range of 2 mm to 3.5 mm, and typically 2.50 mm.

[0035] According to embodiments, the ortho-k contact lens comprises a reverse curve portion continuous from the end of the back optical zone as in the prior art, a fitting or alignment curve portion (spherical or aspherical) and an edge curve portion, wherein the fitting or alignment curve portion comprises an inner curve region and an outer curve region radially offset from the reverse curve portion, wherein the inner curve region has a larger radius of curvature than the outer curve region, and wherein the inner curve region and the outer curve region converge to a vertex portion and form a cavity at which tear fluid can accumulate in use.

[0036] For some embodiments, the reverse curve portion can be divided into two or more portions comprising aspherical shapes.

[0037] For implementations of this embodiment, the fitting or alignment curve portion mimics and follows the shape of a reference aspherical surface.

[0038] The lens of the present utility model lies in realizing correct central refractive correction, because current lenses with aspherical or conical back optical zones usually overcorrect or induce irregular correction, causing discomfort to the wearer.

[0039] Secondly, the lens of the present utility model allows the intermediate peripheral portion to be shaped in an independent manner, realizing stronger curvature changes (even without vertex (on-axis) refractive changes). Scientific evidence shows that the strong intermediate peripheral portion increases the positive sign power compared to ordinary lenses, thereby enhancing myopia control.

[0040] Thirdly, the structure associated with the lens of the present utility model avoids any abrupt changes in angle, junction or curvature in the inner surface of the lens, thereby avoiding problems for eye health and discomfort to the wearer.

[0041] By adopting the technical scheme provided by the lens of the present utility model, a better effect of delaying the increase of axial length of the eye can be achieved.

[0042] In summary, the present utility model provides the following beneficial technical effects:

[0043] 1. The ortho-k lens proposed by the present utility model can effectively control the shape of the final corrected cornea, with appropriate central refractive effect.

[0044] 2. The controlled steepening of the intermediate peripheral cornea increases the amount of defocus and the signal for myopia control.

[0045] 3. The delivered lens design has a progressive shape transition and provides comfort. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to better understand the description made, a set of drawings is provided, which schematically and merely by way of non-limiting example represent the practical case of the embodiments.

[0047] Figure 1 An embodiment of the orthokeratology contact lens of the present application is schematically illustrated, for which embodiment it is illustrated by a lens side elevational cross-sectional view.

[0048] Figure 2 is schematically illustrated the height or sagittal distance or Figure 1 Graph of the points 1 and 2 marked in the middle.

[0049] Figure 3 is schematically illustrated Figure 1 and Figure 2 the tangent union between the central circular region and the annular region of the embodiment. DETAILED DESCRIPTION

[0050] In this part, different embodiments of the lenses of the present application are described with reference to the attached drawings, in particular the embodiments of the orthokeratology contact lenses in Figures 1 to 3 .

[0051] As disclosed in the previous part and as illustrated in Figure 1 , for an embodiment, the present application relates to an orthokeratology contact lens L for an eye of a wearer, the orthokeratology contact lens L comprising an inner surface having a back optical region (lower surface according to the position illustrated in Figure 1 ), the back optical region being for facing or being in contact with the eye of the wearer and being structured and arranged to correct the vision of the cornea of the eye of the wearer in use, wherein said back optical region has a central circular region la and an annular region lb radially extending outwardly from the end of the central circular region la around a geometric center axis El of the lens L.

[0052] In a cross-section of the orthokeratology contact lens L taken along a plane comprising the geometric center axis El, i.e. as illustrated in Figure 1 , the central circular region la and the annular region lb comply with a curvature path of a continuous polynomial shape, wherein:

[0053] - the central circular zone 1a has a spherical radius or a radius with an eccentricity (e value) comprised between 0 and 1, and

[0054] - the annular zone 1b has a radius of curvature which gradually increases in a progressive manner and not linearly from the end of the central circular zone 1a to the end of the back optical zone.

[0055] The diameter of the back optical zone is denoted in the Figure 1 by the abbreviation BOZD.

[0056] As seen in Figure 1 , for the illustrated embodiment, the lens L comprises: a central circular zone 1a, an annular zone 1b (the annular zone 1b can comprise two or more annular sub-zones), which successively extend radially from the geometric center axis E1, the central circular zone 1a and the annular zone 1b conforming the back optical zone; and a reverse curvature portion 2, a fitting or aligning curvature portion 3 and an edge curvature portion 4 which successively extend from the end of the back optical zone, wherein the fitting or aligning curvature portion 3 comprises an inner curvature zone 3a and an outer curvature zone 3b radially offset from the reverse curvature portion 2, wherein said inner curvature zone 3a has a radius of curvature greater than the radius of curvature of the outer curvature zone 3b, and wherein the inner curvature zone 3a and the outer curvature zone 3b converge to a vertex portion and form a cavity at which, in use, tears can accumulate.

[0057] The radius r at each given point on the continuous polynomial-shaped curvature path a and the sagittal distances of the central circular zone 1a and the annular zone 1b are calculated by the above disclosed equations (1) and (2), respectively.

[0058] The remaining parameters will follow the state of the art and the reverse curvature portion 2 will be calculated to return in alignment with the cornea of the wearer’s eye and will be used to store tears and increase the corneal epithelial cell layer; the reverse curvature portion 2 can be composed of one or more curves, composed of a spherical or aspherical surface, the number of fitting or aligning curvature portions 3 can be determined from 1 to 7; the edge curvature portion 4 will be used to provide a flow channel for the tear fluid between the cornea and the lens L.

[0059] Figure 2 The sagittal distances of the points 1 and 2 marked in Figure 1 are plotted by the solid lines, i.e. the sagittal distances for the end of the central circular zone 1a and the end of the annular zone 1b, respectively. In this case, the inner spherical surface is defined up to point 1 (i.e. for the central circular zone 1a) and then a conical surface up to point 2 (i.e. for the annular zone 1b). The provision of a predetermined height of the hypothetical aspherical surface represents the vertex curvature surface of the eye of the wearer. The dashed lines represent the conventional state of the art.

[0060] Figure 3 It shows Figure 1 and Figure 2 The union of the tangents between the central circular region 1a and the annular region 1b in the implementation method identifies that the local axial radius R0 at point 1 is the same as the radius of the annular curve. The radius of the annular curve is then modified to achieve the radius R0+X at point 2.

[0061] The technical solution provided by the lens of this invention achieves the desired and appropriate final height at the edge of the rear optical region. With a minimum optical region diameter of 4.00 mm, this height is set between 30 and 50 micrometers; with a maximum diameter of 7.00 mm, the height is set between 90 and 220 micrometers.

[0062] In this case, in order to achieve these values ​​in low myopia, the eccentricity of the outer portion of the optical zone needs to be between 0 and 8.

[0063] The benefit of this structure is that it enables proper central refractive correction, because current lenses with aspherical or conical rear optical regions often overcorrect or cause irregular correction, which can cause discomfort to the wearer.

[0064] Secondly, this structure allows for independent shaping of the intermediate peripheral portion, achieving greater curvature variation (even without vertex (on-axis) refractive changes). Scientific evidence shows that the strong intermediate peripheral portion increases positive sign power compared to ordinary lenses, thereby enhancing myopia control.

[0065] Third, this structure avoids any sudden changes in angle, joint, or curvature on the inner surface of the lens, thus avoiding eye health problems and wearer discomfort.

[0066] By adopting the above technical solution, a good effect can be achieved in delaying the growth of axial length.

[0067] Those skilled in the art can make changes and modifications to the described embodiments without departing from the scope of the present invention as defined in the appended claims.

Claims

1. A orthokeratology contact lens for an eye of a wearer, the orthokeratology contact lens (L) comprising an inner surface having a back optical zone for facing or being in contact with the eye of the wearer, wherein, The back optical zone has a central circular zone (1a) surrounding a geometric center axis (E1) of the orthokeratology contact lens (L) and the back optical zone has at least one annular zone (1b) extending radially outward from an end of the central circular zone (1a), characterized in that, in a cross section of the orthokeratology contact lens (L) taken along a plane comprising the geometric center axis (E1), the central circular zone (1a) and at least one annular zone (1b) conform to a curvature path of a continuous polynomial shape: - the central circular zone (1a) is aspherical, the asphere having an eccentricity or e-value between 0 and 1 and a vertex axial radius, and - at least one annular zone (1b) has a curvature radius that gradually increases in a progressive manner and not linearly from an end of the central circular zone (1a) to an end of the back optical zone.

2. The orthokeratology contact lens of claim 1, wherein, The central circular zone (1a) has a diameter of 0.50 mm to 3.00 mm.

3. The orthokeratology contact lens of claim 1, wherein, In the cross section, the end of the back optical zone has a height or sagittal distance relative to an imaginary reference sphere on which the back optical zone is disposed of between 20 microns and 220 microns, wherein the imaginary reference sphere is an extension of the vertex curvature radius of the central circular zone (1a).

4. The orthokeratology contact lens of claim 2, wherein, In the cross section, the end of the back optical zone has a height or sagittal distance relative to an imaginary reference sphere on which the back optical zone is disposed of between 20 microns and 220 microns, wherein the imaginary reference sphere is an extension of the vertex curvature radius of the central circular zone (1a).

5. The orthokeratology contact lens of claim 3, wherein, The vertex curved surface of the wearer's eye has a vertex curvature radius in the range of 7 mm to 10 mm.

6. The orthokeratology contact lens of claim 4, wherein, The vertex curved surface of the wearer's eye has a vertex curvature radius in the range of 7 mm to 10 mm.

7. The orthokeratology contact lens of claim 3, wherein, The back optical zone has a diameter in the range of 4.00 mm to 4.5 mm and the height or sagittal distance is in the range of 30 microns to 100 microns.

8. The orthokeratology contact lens of claim 4, wherein, The back optical zone has a diameter in the range of 4.00 mm to 4.5 mm and the height or sagittal distance is in the range of 30 microns to 100 microns.

9. The orthokeratology contact lens of claim 5, wherein, The back optical zone has a diameter in the range of 4.00 mm to 4.5 mm and the height or sagittal distance is in the range of 30 microns to 100 microns.

10. The orthokeratology contact lens of claim 6, wherein, The back optical zone has a diameter in the range of 4.00 mm to 4.5 mm and the height or sagittal distance is in the range of 30 microns to 100 microns.

11. The orthokeratology contact lens of claim 3, wherein, The back optical zone has a diameter of 7 mm and the height or sagittal distance is in the range of 60 microns to 250 microns.

12. The orthokeratology contact lens of claim 4, wherein, The back optical zone has a diameter of 7 mm and the height or sagittal distance is in the range of 60 microns to 250 microns.

13. The orthokeratology contact lens of claim 5, wherein, The back optical zone has a diameter of 7 mm and the height or sagittal distance is in the range of 60 microns to 250 microns.

14. The orthokeratology contact lens of claim 6, wherein, The back optical zone has a diameter of 7 mm and the height or sagittal distance is in the range of 60 to 250 microns.

15. The orthokeratology contact lens of any of the preceding claims, wherein, At least one of the annular zones (1 b) has a conical shape.

16. The orthokeratology contact lens of any one of claims 1 to 14, wherein, a radius r at each given point on the continuous polynomial-shaped curvature path a follows the equation: wherein r is the radius with respect to the geometric center axis (E1) of the ortho-k contact lens (L), x is a coefficient factor or e-value, and y is the distance from the geometric center axis (E1) of the ortho-k contact lens (L), wherein x is in the range between 0 and 8 for at least one of the annular zones (1 b).

17. The orthokeratology contact lens of claim 15, wherein, a radius r at each given point on the continuous polynomial-shaped curvature path a follows the equation: wherein r is the radius with respect to the geometric center axis (E1) of the ortho-k contact lens (L), x is a coefficient factor or e-value, and y is the distance from the geometric center axis (E1) of the ortho-k contact lens (L), wherein x is in the range between 0 and 8 for at least one of the annular zones (1 b).

18. The orthokeratology contact lens of claim 16, wherein, x is in the range of 0 to 8 for at least one of the annular zones (1 b).

19. The orthokeratology contact lens of claim 17, wherein, x is in the range of 0 to 8 for at least one of the annular zones (1 b).

20. The orthokeratology contact lens of claim 1, wherein, In said cross section, the end of the back optical zone has a height or sagittal distance with respect to an imaginary reference sphere on which the back optical zone is disposed, of between 20 microns and 220 microns, wherein the imaginary reference sphere is an extension of the vertex radius of curvature of the central circular zone (1a), wherein x is in the range 0 to 8 for at least one of the annular zones (1b), wherein the radius r at each given point on the continuous polynomial shaped curvature path a follows the equation: wherein r is the radius with respect to the geometric center axis (E1) of the ortho-k contact lens (L), x is a coefficient factor or e-value, and y is the distance from the geometric center axis (E1) of the ortho-k contact lens (L), wherein x is in the range between 0 and 8 for at least one of the annular zones (1 b), and wherein the height or sagittal distance, and the height or sagittal distance of the end of the central circular zone (1 a) with respect to the imaginary reference sphere, are calculated by the following formula: wherein r1 is the axial radius of the central circular zone (1a) or of at least one of the annular zones (1b) in the cross section, r a is the axial radius of the cornea of the eye of the wearer, x is a coefficient factor, and y is the distance from the geometric center axis (E1) of the corneal shaping contact lens (L).

21. The orthokeratology contact lens of claim 20, wherein, The diameter of the central circular zone (1 a) is in the range of 0.50 to 3.00 mm.

22. The orthokeratology contact lens of claim 17, wherein, y is in the range of 2 to 3.5 mm.

23. The orthokeratology contact lens of claim 19, wherein, y is in the range of 2 to 3.5 mm.

24. The orthokeratology contact lens of claim 20 or 21, wherein, y is in the range of 2 to 3.5 mm.

25. The orthokeratology contact lens of claim 16, wherein, y is in the range of 2 to 3.5 mm.

26. The orthokeratology contact lens of claim 18, wherein, y is in the range of 2 to 3.5 mm.

27. The orthokeratology contact lens of claim 1, wherein, At least one of the annular zones (1 b) further comprises a reverse curvature portion (2), a fitting or alignment curvature portion (3), and an edge curvature portion (4) continuous from the end of the back optical zone, wherein the fitting or alignment curvature portion (3) comprises an outer curvature region (3b) and an inner curvature region (3a) radially offset from the reverse curvature portion (2), wherein the inner curvature region (3a) has a larger radius of curvature than the radius of curvature of the outer curvature region (3b), and wherein the inner curvature region (3a) and the outer curvature region (3b) converge to a vertex and form a cavity at which tear fluid can accumulate in use.

28. The orthokeratology contact lens of claim 27, wherein, The fitting or alignment curvature portion (3) mimics and follows the shape of a reference asphere.

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