How to design toric contact lenses

Abstract

The present invention provides a method for designing a front toric soft contact lens with a substantially circular optical zone. Specifically, the present invention describes a method for designing a front toric soft contact lens that features a substantially circular optical zone with a smooth transition between the optical zone and the peripheral non-optically stabilized carrier zone. The optical zone diameter is designed independently of the cylinder power and shape or curvature of the posterior surface. The present invention describes a method for designing a front toric soft contact lens in which neither the edge profile nor the optical zone diameter is affected by the magnitude of the cylinder power or the orientation of the cylinder axis.

Description

Technical Field

[0001] The present invention relates to a method for designing a front toric soft contact lens having a circular optical zone. The present invention describes a method for designing a front toric soft contact lens characterized by a circular optical zone that smoothly transitions between a circular optical zone and a non-optical peripheral stabilization carrier zone. The diameter of the circular optical zone is designed independently of the cylinder refractive power and shape or curvature of the back surface. The present invention describes a method for designing a front toric soft contact lens in which neither the edge profile nor the optical zone diameter is affected by the magnitude of the spherical refractive power, the magnitude of the cylinder refractive power, and / or the orientation of the cylinder axis.

Background Art

[0002] Astigmatism is one of the refractive abnormalities of the eye caused by deviations from the spherical curvature of the cornea and / or lens of the eye, in which light rays from an object converge to a focal line rather than a common focus, producing a distorted image on the retina.

[0003] Astigmatism can occur in combination with other refractive abnormalities such as myopia, hyperopia, or presbyopia, and a large portion of the population is affected to some extent. To correct astigmatism, cylindrical optical correction, also known as toric optical correction, is used, and individuals who are myopic or hyperopic as well as astigmatic can wear a single soft contact lens that includes both a spherical component and a cylindrical component within the optical zone.

[0004] Toric optical correction or cylindrical optical correction relates to the use of optical features having two different target refractive powers along two orientations that are perpendicular to each other in the optical zone of the contact lens. Basically, a lens for astigmatism has one refractive power known as the spherical refractive power for correcting the myopic or hyperopic component that is the refractive abnormality, and a second refractive power known as the cylindrical refractive power for correcting the astigmatic component, and both refractive powers are incorporated into a single optical region of the optical zone of the contact lens.

[0005] Generally, the toric refractive power of a lens can be generated by the continuously changing radius of curvature of the front, back, or both surfaces of the lens over the meridian angle. Most prior art toric soft contact lenses are posterior toric contact lenses, but some commercially available front toric soft contact lenses exist and are often prescribed primarily for eyes with crystalline astigmatism.

[0006] In posterior toric soft contact lenses, the minimum radius of curvature is called the steep meridian, and the maximum radius of curvature is called the flat meridian. By convention, the orientation of the flat meridian, which has the greatest positive refractive power, is used to identify the axis of astigmatism orientation of the posterior toric soft contact lens.

[0007] Conversely, in frontal toric soft contact lenses, the toric refractive power of the lens is generated by the continuously changing radius of curvature of the frontal surface, which is the opposite of the convention described above; namely, the flat meridian is the meridian with the smallest positive refractive power.

[0008] To achieve the desired toric correction, the orientation of the lens's cylindrical axis must be aligned with the eye's astigmatism axis. Toric optical correction is used in corrective modes for eyeglasses, contact lenses, and intraocular lenses. Toric optical correction used in eyeglass lenses and intraocular lenses is held fixedly to the eye. However, contact lenses without any stabilization function will naturally rotate on the eye. Therefore, toric contact lenses must include a mechanism that rotates the lens in the correct manner to hold the contact lens relatively stably on the eye when the wearer blinks or looks around.

[0009] The mechanical properties of the non-optical peripheral carrier zone of toric soft contact lenses are modified to maintain the orientation of the toric soft contact lens on the eye. For example, the use of truncated prisms, prism ballasts, or intentionally thickening the periphery of the lower region of the toric soft contact lens can contribute to improving the stability of the toric contact lens on the eye. Such methods are described in the prior art documents, U.S. Patents and Patent Applications US10747021B2, US6626534B1, US8814350B2, and US8646908B2.

[0010] Other stabilization methods include double slab-off designs or periballast toric soft contact lenses. A common feature of all these designs is a posterior surface that is rotationally symmetrical at the periphery, with peripheral thickness changes achieved by a front surface that is rotationally symmetrical at the periphery. Traditionally, posterior toric soft contact lenses for astigmatism correction have an elliptical optical zone, with the longest axis corresponding to the meridian with the greatest positive refractive power and the shortest axis corresponding to the meridian with the least positive refractive power. For higher cylindrical refractive powers, e.g., greater than -3.00 DC, the difference between the steep and flat meridians, i.e., the ellipticity of the optical zone, increases, making it difficult to maintain an ellipticity of the optical zone that can provide an appropriate pupillary range, or a peripheral thickness profile that can provide good comfort and supraorbital orientation stability.

[0011] In this technology, a new design method is needed that can maintain a circular optical zone of appropriate diameter for any given magnitude of spherical refractive force and cylindrical refractive force, and for any orientation of the cylindrical axis. [Overview of the project]

[0012] The specific methods and algorithms of the present invention relate to the design of anterior toric soft contact lenses for correcting distance vision, which maintain a circular anterior optical zone of appropriate diameter for any given magnitude of spherical and cylindrical refractive power and any orientation of the cylindrical axis.

[0013] Other methods and algorithms of the present invention relate to the design of front-facing multifocal toric soft contact lenses for correcting far and near vision, maintaining a circular optical zone of appropriate diameter for any given magnitude of spherical refractive power, cylindrical refractive power, and addition refractive power and any orientation of the cylindrical axis.

[0014] In this invention, the term "front toric soft contact lens" means a contact lens that corrects distance visual acuity accompanied by astigmatism, i.e., myopia or hyperopia.

[0015] The term "front multifocal toric soft contact lens" refers to the front toric soft contact lens of the present invention, designed for presbyopia, correcting distance vision, near vision, and astigmatism. In this invention, the methods described relating to the design of front toric soft contact lenses are also applicable to the design of front multifocal toric soft contact lenses. The design methods for front multifocal toric soft contact lenses are considered to fall entirely within the scope of the design of front toric soft contact lenses of the present invention.

[0016] One preferred design method for an embodiment of the front toric soft contact lens of the present invention is to (a) define a specific magnitude of cylindrical refractive power and a specific orientation of the cylindrical axis for the front toric soft contact lens, (b) define a specific optical zone diameter for the front toric soft contact lens, (c) define a rear shape for the front toric soft contact lens across the lens diameter, the rear shape may be defined by a number or combination of spherical curves, aspherical curves, or a mixture thereof, (d) define the center thickness of the front toric soft contact lens, and (e) calculate the refractive power profile required for each semi-meridian in the optical zone of the front toric soft contact lens based on the specified magnitude of cylindrical refractive power and orientation of the cylindrical axis, the refractive power profile along each semi-meridian in the optical zone of the front toric soft contact lens may be defined by the presence or absence of spherical aberration, the sign of the spherical aberration in the optical zone may be positive or negative, and the magnitude of the spherical aberration in the optical zone The algorithm may be based on a set of steps including: (f) calculating a thickness profile for each semi-meridian of the optical zone of the front toric soft contact lens using a defined semi-meridian refractive power profile, center thickness, and refractive index of the front toric soft contact lens; (g) generating a front optical surface shape within a specified front optical zone diameter by adding the thickness profiles defined along each semi-meridian to the rear profile; (h) defining a thickness profile for the peripheral non-optical stabilization zone along the corresponding semi-meridian; (i) defining a blending zone along each semi-meridian to substantially smoothly couple the front optical zone of the front toric soft contact lens with the peripheral non-optical stabilization zone; (j) defining an edge profile; and (k) using an existing turning technology platform, such as state-of-the-art computer numerical control (CNC) turning technology, to generate a front surface with the precision required to obtain a good optical quality surface and smooth transition without the need for polishing.According to the present invention, the multiple specified semi-meridians of the optical zone of the front toric soft contact lens may be selected to be in the range of about 12 to about 400 semi-meridians. According to the present invention, by calculating the front shape based on the thickness profile of the optical zone of the front toric soft contact lens, the rear surface design of the front toric soft contact lens is not constrained by the requirement of accommodating the major and minor axes within the peripheral non-optical stabilization zone. For example, one distinct advantage of the present invention is that an asphericity value (p value) of less than 1 can be used for an aspherical or polycurved rear surface, i.e., it can be flattened toward the periphery. In some other embodiments, the asphericity may be expressed as Q or k. The method described herein is applicable to both the lathe-cut mode and the casting mode for manufacturing front toric soft contact lenses.

[0017] The particular methods and algorithms of the present invention relate to the design of front toric soft contact lenses, which provide two obvious advantages over conventional rear toric soft contact lens design methods: (a) enabling the maintenance of a circular optical zone of appropriate diameter that can be maintained across all spherical, cylindrical, and axial formulations of the front toric soft contact lens, and / or (b) enabling the optimization of the blend between the optical zone and the non-optical peripheral stabilization zone for each semi-meridian and each individual formulation of the front toric soft contact lens.

[0018] Another preferred design method for an embodiment of the front toric soft contact lens of the present invention is to (a) define a specific magnitude of cylindrical refractive power and a specific orientation of the cylindrical axis for the front toric soft contact lens, (b) define a specific optical zone diameter for the front toric soft contact lens, (c) define a rotationally symmetric rear surface shape of the front toric soft contact lens, the rotationally symmetric rear surface shape may be defined by a single aspherical curve or a polycurve defined by a set of spheres and / or asphericals, (d) define a rear optical zone diameter which is preferably similar to or larger than the front optical zone diameter of the front toric soft contact lens, if the rear surface is defined as a polycurve aspherical, (e) define the total lens diameter of the front toric soft contact lens, and (f) select a plurality of semi-meridians within the optical zone of the front toric soft contact lens to define the front, the plurality of suitable semi-meridians within the optical zone of the front toric soft contact lens may be about 12 to 400 semi-meridians, ( g )Calculate the required refractive power profile based on the spherical refractive power, cylindrical refractive power, lens prescription of a specific size of the cylindrical axis, and the required size and sign of the spherical aberration to be included within the optical zone for each semi-meridian within the optical zone of the front toric soft contact lens, and ( h ) Select a lens material having known refractive index and expansion characteristics, and ( i ) Selecting the appropriate center thickness for the front toric soft contact lens, and ( j ) Defining the circular diameter of the front optical zone of the front toric soft contact lens, and ( k ) Based on the refractive index and center thickness of the material, the radius of curvature or axial thickness profile along each semi-meridian that achieves the desired refractive power within the front optical zone diameter of the front toric soft contact lens, wherein the radius of curvature or axial thickness profile may be defined by discrete data points along semi-meridians of appropriate density, and this step ( lIn ) for front toric soft contact lenses designed with prism ballast stabilization, it is beneficial to add the difference in matching prism thickness to each semi-meridian of the front toric soft contact lens, and ( m ) Defining the desired thickness profile for the peripheral non-optical stabilization zone along each semi-meridian of the front toric soft contact lens, and ( n ) Defining the blend width between the front optical zone and the peripheral non-optical stabilization zone of the front toric soft contact lens along each semimeridian of the front toric soft contact lens, and ( о )Apply an appropriate blending algorithm to smoothly combine these two zones along each semi-meridian of the front toric soft contact lens, and ( p )In order to obtain front data points, a thickness profile along each semi-meridian is added to the posterior surface of the front toric soft contact lens, and ( q ) Adding an appropriate edge profile to the front and rear profiles of the front toric soft contact lens, wherein the edge profile is defined independently of the magnitude of the cylindrical refractive power and independently of the orientation of the cylindrical axis, ( r ) This may be based on another algorithm that at least partially includes a series of steps of converting the front and rear data points into a format suitable for manufacturing each face of a front toric soft contact lens.

[0019] In some embodiments of the present invention, the contact lens is a front-facing multifocal soft contact lens, and one or more steps of a preferred exemplary method of the present invention also include defining a specific magnitude of the addition power of the front-facing multifocal soft contact lens and calculating a required refractive power profile based on a lens formulation of a specific magnitude of spherical power, cylindrical power, addition power, and cylindrical axis, and the required magnitude and sign of spherical aberration to be included within the optical zone.

[0020] In some embodiments, one or more steps of the preferred exemplary methods of the present invention may be combined with one or more steps of other preferred exemplary methods of the present invention, and the steps obtained in such combinations are considered another preferred exemplary method of the present invention within the scope of the present invention.

Brief Description of the Drawings

[0021] [Figure 1] Front view of a prior art back toric soft contact lens having a non-circular optical zone.

[0022] [Figure 2] Front view of a front toric soft contact lens of the present invention having a substantially circular optical zone surrounded by a variable-width hybrid zone.

[0023] [Figure 3] Cross-sectional view of the back surface of a front toric soft contact lens embodiment of the present invention defined using two exemplary steps: (a) a single-curve aspheric surface, and (b) defining the back surface using the lens diameter or radius.

[0024] [Figure 4] Another cross-sectional view of the back surface of a front toric soft contact lens embodiment of the present invention defined using three exemplary steps: (a) a set of multi-curve aspheric surfaces, (b) the back optical zone radius, and (c) defining the back surface using the lens diameter or radius.

[0025] [Figure 5] Front view of the optical zone diameter of a front toric soft contact lens embodiment of the present invention, illustrating the step of selecting a plurality of semi-meridians with respect to the front optical zone radius of the front toric soft contact lens disclosed herein.

[0026] [Figure 6]This is a cross-sectional view of the optical zone radius of an embodiment of the front toric soft contact lens of the present invention, illustrating the step of defining refractive power profiles for a selection of semi-meridians with respect to the optical zone radius of the front toric soft contact lens disclosed herein.

[0027] [Figure 7] This is a cross-sectional view of the radius of an embodiment of the front toric soft contact lens of the present invention, illustrating the steps of defining a blending zone width and selecting a blending curve to provide a substantially seamless or smooth contour between a selected set of semi-meridians and a selected set of peripheral non-optical stabilization zone thickness profiles with respect to the front optical zone radius of the front toric soft contact lens disclosed herein.

[0028] [Figure 8] This is a cross-sectional view of the radius of an embodiment of the front toric soft contact lens of the present invention, illustrating the step of generating a front sag profile of a selection of semi-meridians with respect to the front radius of the front toric soft contact lens disclosed herein.

[0029] [Figure 9] This represents the front sag profile data for three selected semi-meridians of the front toric soft contact lens of the present invention.

[0030] [Figure 10] This represents the 3D curvature radius thickness profile of a front toric soft contact lens with a (-3D / -2.5DC×60°) formulation designed using prior art methods.

[0031] [Figure 11] This represents the 3D curvature radius thickness profile of a front toric soft contact lens with a (-3D / -2.5DC×60°) formulation designed using the method of the present invention.

[0032] [Figure 12](a) The cross-sectional radius of curvature and thickness profile along the vertical meridian of a front toric soft contact lens designed using the prior art method (dashed line) and (b) the method of the present invention (solid line).

[0033] [Figure 13] This is a front view of the central near-vision multifocal front toric soft contact lens of the present invention, which has substantially circular distance and near optical zones.

[0034] [Figure 14] This is a cross-sectional view of the optical zone radius of an embodiment of the front toric soft contact lens of the present invention, illustrating the step of defining refractive power profiles for a selection of semi-meridians with respect to the optical zone radius of the central near-vision multifocal front toric soft contact lens disclosed herein. [Modes for carrying out the invention]

[0035] In this section, the present invention will be described in detail with reference to one or more methods, some of which are illustrated and supported in the accompanying drawings. Examples and embodiments are provided for illustrative purposes and should not be construed as limiting the scope of the present invention. The following description provides for methods that may share common characteristics and features of the present invention. It should be understood that one or more features of one method may be combined with one or more methods of other embodiments to constitute additional method embodiments of the front toric soft contact lenses of the present invention.

[0036] The functional and structural information disclosed herein should not be construed as limiting in any way, but rather as a representative basis for teaching the disclosed methods and variations thereof in various ways to those skilled in the art for designing, developing, and manufacturing toric soft contact lenses, more specifically anterior toric soft contact lenses.

[0037] Figure 1 is a front view of a prior art posterior toric soft contact lens (100), comprising a lens diameter (101), a non-circular optical zone (102), and a peripheral non-optical stabilization zone (103). The transition (104) between the non-circular optical zone (102) and the peripheral non-optical stabilization zone (103) of the posterior toric soft contact lens (100) is not defined, and the lens may not be stabilized as needed, which may result in reduced comfort and / or visual performance.

[0038] The elliptical shape and size of the non-circular optical zone (102) of the posterior toric soft contact lens (100) are in accordance with its toric formulation, i.e., spherical refractive power, cylindrical refractive power, and cylindrical axis. The major axis of the ellipse (106) represents the meridian with the largest radius of curvature and the greatest positive refractive power. Its orientation defines the cylindrical axis (105), which in this example is approximately 60°. The minor axis of the ellipse represents the meridian with the smallest radius of curvature, or the meridian with the greatest negative refractive power, or the steepest meridian (107). The cylindrical refractive power of the lens is the refractive power difference between the flat meridian (106) and the steepest meridian (107). The eccentricity of the posterior toric soft contact lens (100), or the ratio between the length of the minor axis and the length of the major axis of the elliptical or non-circular optical zone (102), increases with increasing cylindrical refractive power, which can lead to further deterioration of performance, especially for inclined cylindrical axes.

[0039] Figure 1 shows an example of a prior art posterior toric soft contact lens (100), but the same design limitations exist for the prior art anterior toric soft contact lens.

[0040] To overcome the design limitations of prior art front or rear toric soft contact lenses having a non-circular optical zone, a novel design method for front toric soft contact lenses is provided that provides a circular optical zone regardless of the toric formulation, that is, independently of the magnitude of the cylindrical refractive power and independent of the orientation of the cylindrical axis.

[0041] Figure 2 is a front view of the front toric soft contact lens (200) of the present invention, comprising a lens diameter (201), a substantially circular optical zone (202), a peripheral non-optical stabilization zone (203), and a mixing zone (204) between the substantially circular optical zone (202) and the peripheral non-optical stabilization zone (203). The mixing zone (204) provides smooth mixing and improves comfort and / or visual performance compared to current prior art front toric soft contact lenses.

[0042] The substantially circular optical zone (202) of the front toric soft contact lens (200) includes a meridian with the smallest radius of curvature, which is also the meridian with the largest positive refractive power or steepest meridian (206), and a meridian with the largest radius of curvature, or the meridian with the smallest positive refractive power, or a flat meridian (207). In this embodiment, the orientation of the steepest meridian (206) defines the cylindrical axis (205), which in this example is approximately 60°. The cylindrical refractive power of the lens is the refractive power difference between the steepest meridian (206) and the flat meridian (207). Even with increasing cylindrical refractive power, the size and shape of the substantially circular optical zone (202) remain substantially the same, and visual performance independent of toric formulations can be provided.

[0043] The first few steps of the exemplary method of the present invention are illustrated in Figure 3, a cross-sectional view of the rear surface of an embodiment of the front toric soft contact lens of the present invention. In this embodiment, the first step is to define the rear surface of the front toric soft contact lens using a single curved aspherical surface (301) above a defined lens diameter or radius (step 2, 302), as disclosed herein.

[0044] In one alternative embodiment, the first few steps of the exemplary method of the present invention are illustrated in Figure 4, a cross-sectional view of the rear surface of a front toric soft contact lens embodiment. In this embodiment, the first step is to define the central rear surface using a spherical or aspherical curve (401) including the specification of the central rear optical zone radius (402). Step 3 includes defining the lens radius (403) and at least one rear peripheral curve (404). Between these zones (401 and 404), an appropriate blend is applied to flatten any steep junctions.

[0045] Step 4 of the exemplary method of the present invention is illustrated in Figure 5, a front view of the optical zone (501) of the diameter (502) of an embodiment of the front toric soft contact lens of the present invention. This step involves selecting a plurality of semi-meridians (503) with respect to the front optical zone diameter (502) of the front toric soft contact lens, preferably a uniform clockwise increment separated by an angle θ (504), as disclosed herein.

[0046] The next step in the exemplary method of the present invention is step 5(605), described in Figure 6, which represents the refractive power profile in a substantially circular optical zone of the front toric soft contact lens embodiment of the present invention, and this step involves defining the refractive power profile for a selection of semi-meridians in the front optical zone, as disclosed herein. In Figure 6, the refractive power profiles for various semi-meridians (621–630, etc.) are drawn for individual angles θ as a function of the front optical zone radius (607) (i.e., distance from the center). In some embodiments, the selection of semi-meridians may be 12–400 semi-meridians, or 10–300 semi-meridians, or 8–240 semi-meridians. In some embodiments of the present invention, the refractive power difference between the smallest positive semi-meridian (630) and the largest positive semi-meridian (621), also known as the cylindrical refractive power, may be 0.25 DC to 5 DC, 0.5 DC to 3 DC, 0.5 DC to 6 DC, or 1 DC to 4 DC. In other embodiments of the present invention, the refractive power difference between the smallest positive semi-meridian (630) and the largest positive semi-meridian (621), also known as the cylindrical refractive power, may be at least 0.25 DC, at least 1 DC, at least 3 DC, or at least 4 DC. In some embodiments of the present invention, the refractive power profile across selected semi-meridians may be spherical, aspherical, or polycurved.

[0047] Another set of steps of the exemplary method of the present invention is illustrated in Figure 7, which shows the thickness profiles (703a, 703b, 703c, 703d, etc.) along the radius (703) of the front toric soft contact lens embodiment of the present invention. The steps disclosed herein are: step 6, selecting the central thickness (706); step 7, converting the semi-meridian refractive power profiles (621-630) to semi-meridian thickness profiles (e.g., 707a and 707b) of the front optical zone radius (707) taking into account the refractive index of the contact lens material, and adding, if necessary, prism thickness differences to match each selected semi-meridian thickness profile (e.g., 707a and 707b) of the front optical zone radius (707); step 9, defining the mixed zone width (711); and each peripheral zone selection semi-meridian The process includes, or involves, step 10 defining peripheral thickness profiles (e.g., 712a and 712b) for a meridian (712), and step 11 selecting the shape of a blended curve (e.g., 711a and 711b) to provide a substantially seamless or smooth profile between a selection of semi-meridians (e.g., 707a and 707b) with respect to the front optical zone radius (707) of the front toric soft contact lens and a selection of peripheral zone thickness profiles (e.g., 712a and 712b). The blended width may vary between semi-meridians by extending zone 711 and shortening peripheral zone 712 or vice versa.

[0048] The final step of the exemplary method of the present invention is illustrated in Figure 8, a cross-sectional view of the radius of an embodiment of the front toric soft contact lens of the present invention. This step includes, or relates to, generating a front sag profile (813) for a selection of n semi-meridians with respect to the radius of the front toric soft contact lens by adding the thickness profiles of the optical zone (707), the mixing zone (711), and the peripheral zone (712) disclosed herein to the rear profile (812).

[0049] A preferred exemplary design method for a front toric soft contact lens according to embodiments of the present invention may be based on another algorithm that includes at least in part the following set of steps: (Step 1) Define a rotationally symmetric rear profile for the front toric soft contact lens, which may be designed as a single curved aspherical or a set of polycurved conic sections. If necessary, i.e., if the rotationally symmetric rear profile for the front toric soft contact lens is defined as polycurved, perform (Step 2) defining the rear optical zone diameter, which is preferably larger than or similar to the front optical zone diameter of the front toric soft contact lens. (Step 3) Define the front toric soft contact lens diameter (or radius) and appropriate rear peripheral curves to achieve the target average basic curve. (Step 4) Select the front optical zone diameter and a plurality of semi-meridians for front definition of the optical zone of the front toric soft contact lens. For example, the plurality of semi-meridians may be 12 to 400. (Step 5) In this embodiment, for each semi-meridian of the optical zone, the required refractive power profile is calculated based on the spherical, cylindrical refractive power, cylindrical axis, and toric lens formulation for spherical aberration. (Step 6) The lens material and appropriate center thickness are selected. (Step 7) Based on the refractive index and center thickness of the selected material, the multiple semi-meridian refractive power profiles are converted into thickness profiles. (Step 8) The blend width between the front optical zone and the front non-optical peripheral stabilization zone is defined. (Step 9) The peripheral thickness profile for each semi-meridian is defined. (Step 10) A blend curve is applied along each semi-meridian to smoothly combine the optical zone thickness profile with the peripheral zone thickness profile. (Step 11) The calculated thickness profiles for each semi-meridian are added to the rear surface to generate a front profile along each semi-meridian. The selection of the peripheral thickness profile for each semi-meridian is defined in part by the selected stabilization method.The combination of peripheral thickness profiles along each semi-meridian may constitute a commonly used stabilization method, or one of the following: prism ballast, peripheral ballast, or dynamic stabilization, or other methods that allow the lens to be oriented over the eye. Appropriate edge profiles may be added to the front and rear profiles to facilitate manufacturing and to provide acceptable over-eye comfort. The front and rear data points are converted to a format suitable for manufacturing each surface.

[0050] For example, Figure 9 shows front sag profile data for three selected semi-meridians of the front toric soft contact lens of the present invention, which can be used on a lathe to manufacture the front surface. However, the actual number of semi-meridians required to manufacture the front toric soft contact lens may be between 12 and 400. The density of data points along the semi-meridians may vary. In this embodiment, the data points become denser towards the edge of the lens. In other embodiments, the density may be uniform across the semi-meridians.

[0051] The front toric soft contact lenses designed using the method of the present invention offer two advantages over conventional toric soft contact lenses: (I) enabling a circular optical zone of appropriate diameter that can be maintained across all spherical, cylindrical, and axial formulations of the front toric soft contact lens, and / or (II) enabling a blend between the optical zone and the non-optical peripheral stabilization zone that can be optimized for each semimeridian of the front toric soft contact lens for each individual formulation of the front toric soft contact lens. The smooth surface and thickness profile can be considered an advantage for comfortable over-ocular wear.

[0052] Figure 10 shows the three-dimensional thickness profile of a prior art frontal toric soft contact lens with a -3.00DS / -2.50DC × 60-degree axis formulation. The prior art method has been found to produce a non-circular or elliptical optical zone (1001), which may not provide robust visual performance across the range of pupil diameters the wearer may experience. Furthermore, the greater the cylindrical refractive power to be contained within the toric soft contact lens, the greater the deviation from the circular optical zone. At cylindrical refractive powers greater than 3DC, the elliptical optical zone can result in significant visual performance problems.

[0053] Unlike the teachings of the prior art, the novel design method for front toric soft contact lenses offers two distinct advantages: namely, maintaining a circular optical zone (1101) regardless of the magnitude of the cylindrical refractive power of the front toric soft contact lens, and smoothly blending the optical zone with the peripheral non-optically stabilized zone to improve inocular comfort. The three-dimensional thickness profile of a front toric soft contact lens designed at least partially using the method of the present invention is shown in Figure 11. The front toric soft contact lens in Figure 11 has a formulation of -3.00DS / -2.50DC × 60-degree axis.

[0054] Generally, the minimum optical zone diameter of soft contact lenses is approximately 8 mm, which corresponds to the clinically reasonable maximum pupil diameter under dit-to-twilight lighting conditions. The table below shows the expected changes in the optical zone diameter, i.e., the short and long axes, of prior art frontal toric soft contact lenses as cylindrical refractive power increases. At low cylindrical refractive powers up to approximately -2.0 DC, the minimum optical zone diameter of 8 mm is maintained. However, at higher cylindrical refractive powers, the diameter of soft contact lenses, which is typically 14 mm, increases. Zhou Since the diameter of the long-axis optical zone extends above the edge, it is necessary to shorten the diameter of the short-axis optical zone.

[0055] Therefore, a prior art front-facing toric soft contact lens with a cylindrical refractive power of -4.00 DC, for example, produces a minor-axis optical zone diameter of 6.2 mm while maintaining a major-axis optical zone diameter of up to 13.6 mm. This minor-axis optical zone diameter of 6.2 mm is too small to meet the visual performance requirements under all lighting conditions. [Table 1]

[0056] In contrast, the novel design method for the front toric soft contact lens of the present invention makes it possible to maintain the optical zone diameter at substantially 8 mm regardless of the magnitude of the cylindrical refractive power.

[0057] Figure 12 shows an example of the vertical thickness profile of a prism ballast toric soft contact lens. The dashed line (1201) represents the radius of curvature thickness profile when the lens is designed using a conventional front or rear toric design method. The solid line (1202) represents the radius of curvature thickness profile of the same lens formulation designed by the method of the present invention. The solid line shows a smoother contour and maintains an optical zone diameter of approximately 8 mm across both semi-meridians. In contrast, the dashed line shows more irregularity (i.e., undesirable surface undulation) and the optical zone diameter is reduced to approximately 7 mm across this vertical meridian.

[0058] Although the exemplary embodiment of the present invention described in Figure 12 includes the implementation of a front toric design using a prism ballast, the design method of the front toric design of the present invention can also consist of various other stabilization techniques that have been considered in the prior art.

[0059] Figure 13 is a front view of a central near-vision multifocal anterior toric soft contact lens (1300), comprising a lens diameter (1301), a substantially circular optical zone (1302), a peripheral non-optical stabilization zone (1303), and a blending zone (1304) between the substantially circular optical zone (1302) and the peripheral non-optical stabilization zone (1303). The blending zone (1304) provides smooth blending, leading to improved comfort and / or visual performance compared to prior art anterior toric soft contact lenses.

[0060] The substantially circular optical zone (1302) of the central near-vision multifocal anterior toric soft contact lens (1300) includes a concentric far-vision zone (1308), a concentric intermediate-vision zone (1309), a central near-vision zone (1310), a meridian with the smallest radius of curvature, or the meridian with the largest positive refractive power, or a steep meridian (1306), and a meridian with the longest radius of curvature, or the meridian with the smallest positive refractive power, or a flat meridian (1307). In this embodiment, the orientation of the steep meridian (1306) defines a cylindrical axis (1305), which in this example is approximately 60°. The cylindrical refractive power of the lens is the refractive power difference between the steep meridian (1306) and the flat meridian (1307). Even with an increase in cylindrical refractive power, the size and shape of the substantially circular optical zone (1302) remain substantially the same, providing visual performance independent of toric prescriptions.

[0061] Figure 14 is a cross-sectional view of the optical zone radius of an embodiment of the central near-vision multifocal anterior toric soft contact lens of the present invention, illustrating the step of defining refractive power profiles for a selection of semi-meridians with respect to the optical zone radius of the central near-vision multifocal anterior toric soft contact lens disclosed herein.

[0062] In Figure 14, the refractive power profiles of the exemplified near-central multifocal anterior toric soft contact lenses for various semi-meridians (1421–1430, etc.) are plotted for individual angles θ as a function of the anterior optical zone radius (1407) (i.e., distance from the center). Far-central and other refractive power profiles providing multifocality are also envisioned and are considered to be within the scope and spirit of the present invention. In some embodiments, the selected number of semi-meridians may be 12–400 semi-meridians, or 10–300 semi-meridians, or 8–240 semi-meridians. In some embodiments of the present invention, the refractive power difference between the smallest positive semi-meridian (1430) and the largest positive semi-meridian (1421), also known as cylindrical refractive power, may be 0.25DC–5DC, 0.5DC–3DC, 0.5DC–6DC, or 1DC–4DC. In another embodiment of the present invention, the refractive power difference between the smallest positive semi-meridian (1430) and the largest positive semi-meridian (1421), also known as the cylindrical refractive power, may be at least 0.25 DC, at least 1 DC, at least 3 DC, or at least 4 DC.

[0063] The present invention describes a multifocal front toric soft contact lens (e.g., Figure 13) comprising a front surface, a rear surface, a central thickness, front and rear optical zones having a plurality of semi-meridians and a plurality of refractive power profiles, a peripheral stabilization zone circumscribing the optical zones, a mixed zone between the front optical zone and the peripheral stabilization zone, and an edge. A multifocal front-facing toric soft contact lens involves (1) defining the diameter of the multifocal front-facing toric soft contact lens, (2) defining the diameter of the optical zone, (3) defining the width of the blending zone for each semi-meridian, (4) defining the width of the peripheral stabilization zone for each semi-meridian, (5) defining the rotationally symmetric rear surface of the multifocal front-facing toric soft contact lens, (6) selecting multiple semi-meridians to define the multifocal front surface of the contact lens, (7) calculating the refractive power profile along each of the multiple semi-meridians of the multifocal front-facing toric soft contact lens based on a prescription including spherical refractive power, cylindrical refractive power, addition refractive power, cylindrical axis, and spherical aberration, (8) selecting the lens material and the appropriate center thickness of the front-facing toric soft contact lens, and (9) determining the curvature along each of the multiple semi-meridians within the optical zone to achieve the refractive power profile based on the refractive index and center thickness of the lens material. The design method is comprised of an algorithm that at least partially includes a series of design steps: (10) calculating a radius or axial thickness profile, wherein the radius of curvature thickness profile is defined by a set of discrete points selected along each set of semi-meridians in the optical zone; (11) optimizing the blend width between the optical zone and the peripheral stabilization zone for each set of semi-meridians; (12) applying an appropriate blending algorithm to join the optical zone and the peripheral stabilization zone so that the optical zone and the peripheral stabilization zone are substantially smooth along each set of semi-meridians; (13) adding the thickness profile along each set of semi-meridians to the rear surface to obtain front data points; (14) adding edges to the front and rear profiles; and (15) converting the front and rear data points into a format suitable for manufacturing the front and rear surfaces.

[0064] The use of the present invention enables contact lens manufacturers to design front toric soft contact lenses by adding calculated thickness profiles, as illustrated in the various embodiments disclosed herein, to arbitrary basic curves, providing a degree of freedom to maintain a circular optical zone, and the shape is independent of the magnitude of the cylindrical refractive power contained within the front toric soft contact lens of the present invention. More specifically, one method of the present invention provides a front toric soft contact lens that essentially features a circular optical zone.

[0065] In some embodiments, the front toric soft contact lens includes a front surface, a back surface, a central thickness, an optical zone having a refractive power profile, a peripheral stabilization zone circumscribing the optical zone, a mixed zone between the optical zone and the peripheral stabilization zone, and an edge. The contact lens is defined by (1) defining the diameter of the contact lens, (2) defining the diameter of the optical zone, (3) defining the width of the blending zone, (4) defining the width of the peripheral stabilization zone, (5) defining the rotationally symmetric rear surface of the contact lens, (6) selecting multiple semi-meridians to define the front surface of the contact lens, (7) calculating the refractive power profile along each of the multiple semi-meridians of the contact lens based on a prescription including spherical refractive power, cylindrical refractive power, cylindrical axis, and spherical aberration, (8) selecting the lens material and the appropriate center thickness of the contact lens, and (9) calculating the radius of curvature or axial thickness profile along each of the multiple semi-meridians in the optical zone to realize the refractive power profile based on the refractive index and center thickness of the lens material, wherein the radius of curvature or thickness profile is selected along each of the multiple semi-meridians in the optical zone. The design method is constructed using an algorithm that at least partially includes a set of design steps: (10) defining a set of discrete points selected, (11) adding a desired thickness profile to each of the semi-meridians within the peripheral stabilization zone to provide a prism ballast, (12) optimizing the mixed zone between the optical zone and the peripheral stabilization zone for each of the semi-meridians, (13) applying an appropriate mixing algorithm to combine the optical zone and the peripheral stabilization zone so that the optical zone and the peripheral stabilization zone are substantially smooth along each of the semi-meridians, (14) adding a thickness profile along each of the semi-meridians to the rear surface to obtain front data points, (15) adding edges to the front and rear profiles, and (16) converting the front and rear data points into a format suitable for manufacturing the front and rear profiles.

[0066] In some embodiments, the front toric soft contact lens may be configured such that the shape of the optical zone is substantially circular, and this shape may be independent of the spherical refractive power, cylindrical refractive power, cylindrical axis, or magnitude of spherical aberration of the formulation.

[0067] In some embodiments, the front toric soft contact lens may be configured such that the toric optical correction of the optical zone of the contact lens has two different target refractive powers along two orientations that are not perpendicular to each other.

[0068] In other embodiments, the front toric soft contact lens may be defined using a rotationally symmetric rear surface that may be designed as a single-curve aspheric surface or a set of multi-curve aspheric surfaces.

[0069] In another exemplary embodiment, the front toric soft contact lens of the present invention may be defined using a plurality of semi-meridians, the number of which may be 12 to 400 or 8 to 240.

[0070] In one embodiment, the front toric soft contact lens may have a spherical refractive power of -10D to +10D, a cylindrical refractive power of -0.5DC to -3.5DC, a cylindrical axis of 0 to 180 degrees, and a spherical aberration of -2D to +2D, as defined on the optical zone.

[0071] In another embodiment, the front toric soft contact lens of the present invention is manufactured using a lens material having a refractive index of 1.38 to 1.5. In another embodiment, the front toric soft contact lens of the present invention has a diameter of 13.5 mm to 15 mm. In another embodiment, the front toric soft contact lens of the present invention has an optical zone diameter of 6 to 9 mm.

[0072] In another embodiment, the front toric soft contact lens of the present invention is designed using a number of discrete points of selected densities along each of several semi-meridians, wherein the number of discrete points is at least 100 or at least 1000, or 32 to 256, or 256 to 10000.

[0073] In another embodiment, the front toric soft contact lens of the present invention is defined as having a round edge, a chisel edge, or a knife edge.

[0074] Several other embodiments are described in the following set of examples. Example Set A: Front toric soft contact lenses for distance vision correction

[0075] The front toric soft contact lens includes a front surface, a back surface, a central thickness, an optical zone having multiple semi-meridians and multiple refractive power profiles, a peripheral stabilization zone circumscribing the optical zone, a mixed zone between the optical zone and the peripheral stabilization zone, and an edge. A multifocal front toric soft contact lens involves (1) defining the diameter of the front toric soft contact lens, (2) defining the diameter of the optical zone, (3) defining the width for the blending zone of each semi-meridian, (4) defining the width for the peripheral stabilization zone of each semi-meridian, (5) defining the rotationally symmetric rear surface of the multifocal front toric soft contact lens, (6) selecting multiple semi-meridians to define the multifocal front surface of the contact lens, (7) calculating the refractive power profile along each of the multiple semi-meridians of the multifocal front toric soft contact lens based on a prescription including spherical refractive power, cylindrical refractive power, cylindrical axis, and spherical aberration, (8) selecting the lens material and appropriate center thickness for the front toric soft contact lens, and (9) determining the refractive power profile for each of the multiple semi-meridians within the optical zone based on the refractive index and center thickness of the lens material. The design method is comprised of an algorithm that at least partially includes a series of design steps: (10) adding a desired thickness profile to each of the semi-meridians in the peripheral stabilization zone; (11) optimizing the blend width between the optical zone and the peripheral stabilization zone for each of the semi-meridians; (12) applying an appropriate blending algorithm to join the optical zone and the peripheral stabilization zone so that they are substantially smooth along each of the semi-meridians; (13) adding the thickness profile along each of the semi-meridians to the rear surface to obtain front data points; (14) adding edges to the front and rear profiles; and (15) converting the front and rear data points into a format suitable for manufacturing the front and rear surfaces.

[0076] A front toric soft contact lens according to claim 1 of the embodiment set A, wherein the refractive power profile along each of the multiple semi-meridians results in a front toric soft contact lens for correcting distance vision.

[0077] A front toric soft contact lens according to claim 1 of the embodiment set A, wherein the shape of the optical zone is substantially circular, and the shape is independent of the spherical refractive power, cylindrical refractive power, addition refractive power, cylindrical axis, or magnitude of spherical aberration of the formulation.

[0078] The front toric soft contact lens according to claim 1 of the embodiment set A, wherein the rotationally symmetric rear surface is designed as an aspherical surface with a single curve.

[0079] The front toric soft contact lens according to claim 1 of the embodiment set A, wherein the rotationally symmetric rear surface is designed as a set of multi-curved aspherical surfaces.

[0080] The front toric soft contact lens according to claim 1 of the example set A, wherein the number of semi-meridians is 12 to 400.

[0081] The front toric soft contact lens according to claim 1 of the example set A, wherein the number of semi-meridians is 8 to 240.

[0082] The front toric soft contact lens of claim 1 of the embodiment set A, wherein the spherical refractive power defined on the optical zone is -10D to +10D, the cylindrical refractive power is -0.5DC to -3.5DC, the cylindrical axis is 0 to 180 degrees, and the spherical aberration is -2D to +2D.

[0083] The front toric soft contact lens according to claim 1 of the example set A, wherein the refractive index of the lens material is 1.38 to 1.5.

[0084] The toric soft contact lens according to claim 1 of the example set A, wherein the lens diameter is 13.5 mm to 15 mm.

[0085] The front toric soft contact lens according to claim 1 of the example set A, wherein the diameter of the circular optical zone is 6 to 9 mm.

[0086] A front toric soft contact lens according to claim 1 of the embodiment set A, wherein the number of discrete points of density selected along each of the multiple semi-meridians is at least 100.

[0087] The front toric soft contact lens of claim 1 of the example set A, wherein the number of discrete points of density selected along each of the multiple semi-meridians is 32 to 256.

[0088] The front toric soft contact lens of claim 1 of the example set A, wherein the number of discrete points of density selected along each of the multiple semi-meridians is 256 to 10000.

[0089] The front toric soft contact lens according to claim 1 of the embodiment set A, wherein the edge is defined as a rounded edge.

[0090] A front toric soft contact lens according to claim 1 of embodiment set A, wherein the edge is defined as a chisel edge.

[0091] The front toric soft contact lens according to claim 1 of the embodiment set A, wherein the edge is defined as a knife edge.

[0092] A front toric soft contact lens according to claim 1 of the set of examples A, wherein the axial thickness profile along each of the multiple semi-meridians within the optical zone is used to achieve the refractive index profile. Example Set B: Multifocal frontal toric soft contact lenses

[0093] A multifocal frontal toric soft contact lens includes a front surface, a posterior surface, a central thickness, a front optical zone having multiple semi-meridians and multiple refractive power profiles, a peripheral stabilization zone circumscribing the optical zone, a mixed zone between the front optical zone and the peripheral stabilization zone, and an edge. A multifocal front toric soft contact lens involves (1) defining the diameter of the multifocal front toric soft contact lens, (2) defining the diameter of the optical zone, (3) defining the width for the blending zone of each of the multiple semi-meridians, (4) defining the width for the peripheral stabilization zone of each semi-meridian, (5) defining the rotationally symmetric rear surface of the multifocal front toric soft contact lens, (6) selecting multiple semi-meridians to define the multifocal front surface of the contact lens, (7) calculating the refractive power profile along each of the multiple semi-meridians of the multifocal front toric soft contact lens based on a prescription including spherical refractive power, cylindrical refractive power, addition refractive power, cylindrical axis, and spherical aberration, (8) selecting the lens material and appropriate center thickness for the front toric soft contact lens, and (9) determining the refractive power profile within each of the multiple semi-meridians in the optical zone based on the refractive index and center thickness of the lens material. The design method is comprised of an algorithm that at least partially includes a series of design steps: (10) adding a desired thickness profile to each of the semi-meridians in the peripheral stabilization zone; (11) optimizing the mixed zone between the optical zone and the peripheral stabilization zone for each of the semi-meridians; (12) applying an appropriate mixing algorithm to combine the optical zone and the peripheral stabilization zone so that they are substantially smooth along each of the semi-meridians; (13) adding the thickness profile along each of the semi-meridians to the rear surface to obtain front data points; (14) adding edges to the front and rear profiles; and (15) converting the front and rear data points into a format suitable for manufacturing the front and rear surfaces.

[0094] A multifocal anterior toric soft contact lens according to claim 1 of the embodiment set B, wherein the refractive power profiles along multiple semi-meridians result in a central near-vision multifocal anterior toric soft contact lens.

[0095] A multifocal anterior toric soft contact lens according to claim 1 of the set of examples B, wherein the refractive power profiles along multiple semi-meridians result in a multifocal anterior toric soft contact lens for central distance.

[0096] A multifocal front-facing toric soft contact lens according to one or more claims of the set of examples B, wherein the shape of the optical zone is substantially circular, and the shape is independent of the spherical refractive power, cylindrical refractive power, addition refractive power, cylindrical axis, or magnitude of spherical aberration of the formulation.

[0097] A multifocal front toric soft contact lens according to one or more claims of the set of examples B, wherein the rotationally symmetric rear surface is designed as a single-curve aspheric surface.

[0098] A multifocal front toric soft contact lens according to one or more claims of the set of examples B, wherein the rotationally symmetric rear surface is designed as a set of multicurved aspherical surfaces.

[0099] A multifocal anterior toric soft contact lens according to one or more claims of the set of examples B, wherein the number of semi-meridians is 12 to 400.

[0100] A multifocal anterior toric soft contact lens according to one or more claims of the set of examples B, wherein the number of semi-meridians is 8 to 240.

[0101] A multifocal front-facing toric soft contact lens according to one or more claims of the set of examples B, wherein the spherical refractive power defined on the optical zone is -10D to +10D, the cylindrical refractive power is -0.5DC to -3.5DC, the cylindrical axis is 0 to 180 degrees, the addition refractive power is +0.5 to +3.5D, and the spherical aberration is -2D to +2D.

[0102] A multifocal front-facing toric soft contact lens according to one or more claims of Example Set B, wherein the refractive index of the lens material is 1.38 to 1.5.

[0103] A multifocal frontal toric soft contact lens according to one or more claims of Example Set B, wherein the lens diameter is 13.5 mm to 15 mm.

[0104] A multifocal front-facing toric soft contact lens according to one or more claims of Example Set B, wherein the circular optical zone diameter is 6 to 9 mm.

[0105] A multifocal frontal toric soft contact lens according to one or more claims of the set of examples B, wherein the number of discrete points of density selected along each of the multiple semi-meridians is at least 100.

[0106] A multifocal frontal toric soft contact lens according to one or more claims of the set of examples B, wherein the number of discrete points of density selected along each of the multiple semi-meridians is 32 to 256.

[0107] A multifocal frontal toric soft contact lens according to one or more claims of the set of examples B, wherein the number of discrete points of density selected along each of the multiple semi-meridians is between 256 and 10000.

[0108] A multifocal frontal toric soft contact lens according to one or more claims of the set of examples B, wherein the edge is defined as a rounded edge.

[0109] A multifocal front-facing toric soft contact lens according to one or more claims of the set of examples B, wherein the edge is defined as a chisel edge.

[0110] A multifocal front-facing toric soft contact lens according to one or more claims of the set of embodiments B, wherein the edge is defined as a knife edge.

[0111] A multifocal front-facing toric soft contact lens according to one or more claims of the set of examples B, wherein the axial thickness profile along each of the multiple semi-meridians within the optical zone is used to achieve a refractive index profile. [Industrial applicability]

[0112] The front toric soft contact lens of the present invention enables (a) the maintenance of a circular optical zone of appropriate diameter that can be maintained across all spherical, cylindrical, and axial formulations of the front toric soft contact lens, and / or (b) the optimization of the blend between the optical zone and the non-optical peripheral stabilization zone for each semi-meridian and each individual formulation of the front toric soft contact lens. [Explanation of Symbols]

[0113] 200: Front toric soft contact lenses 201: Lens diameter 202: Optical Zone 203: Peripheral non-optical stabilization zone 204: Mixed Zone 205: Cylindrical axis 206: Steep Meridian 207: Flat meridian

Claims

1. A front toric soft contact lens comprising a front surface, a rear surface, a central thickness, an optical zone which is a front optical zone having a plurality of semi-meridians and a plurality of refractive power profiles, a peripheral stabilization zone circumscribing the optical zone, a mixed zone between the optical zone and the peripheral stabilization zone, and an edge, (1) Define the diameter of the front toric soft contact lens, (2) Defining the diameter of the optical zone, (3) Defining the width for the mixed zone of each of the plurality of semi-meridians, (4) Defining the width for the peripheral stabilization zone of each of the plurality of semi-meridians, (5) Defining the rotationally symmetric rear surface of the front toric soft contact lens, (6) Selecting the plurality of semi-meridians in order to define the front surface of the front toric soft contact lens, (7) Based on the formulation including spherical refractive power, cylindrical refractive power, cylindrical axis, and spherical aberration, calculate the refractive power profile of each of the plurality of semi-meridians of the front toric soft contact lens, (8) Selecting the appropriate center thickness of the lens material and the front toric soft contact lens, (9) Based on the refractive index of the lens material and the center thickness, a radius of curvature thickness profile or axial thickness profile along the plurality of semi-meridians in the optical zone is calculated in order to realize the refractive power profile, wherein the radius of curvature thickness profile is defined by a plurality of discrete points selected along each of the plurality of semi-meridians in the optical zone, (10) Adding a desired thickness profile to each of the plurality of semi-meridians within the peripheral stabilization zone, (11) Optimizing the blending width between the optical zone and the peripheral stabilization zone of each of the plurality of semi-meridians, (12) Applying an appropriate mixing algorithm to combine the optical zone and the peripheral stabilization zone so that they are substantially smooth along each of the plurality of semi-meridians, (13) In order to obtain front data points, the thickness profile is added to the rear surface along each of the plurality of semi-meridians, (14) Adding the edges to the front profile and rear profile, (15) Converting the front data points and rear data points into a format suitable for manufacturing the front and rear surfaces. The design method is constructed using an algorithm that includes, at least partially, a series of design steps, Front toric soft contact lenses.

2. The shape of the optical zone is substantially circular. The shape is independent of the magnitude of the spherical refractive power, cylindrical refractive power, cylindrical axis, or spherical aberration of the formulation. The front toric soft contact lens according to claim 1.

3. The aforementioned rotationally symmetric rear surface is designed as an aspherical surface with a single curve. A front toric soft contact lens according to claim 1 or claim 2.

4. The aforementioned rotationally symmetric rear surface is designed as a set of multi-curved aspherical surfaces. A front toric soft contact lens according to claim 1 or claim 2.

5. The number of semi-meridians mentioned above ranges from 12 to 400. A front toric soft contact lens according to claim 1 or claim 2.

6. The number of semi-meridians mentioned above ranges from 8 to 240. A front toric soft contact lens according to claim 1 or claim 2.

7. The spherical refractive power defined on the optical zone is -10D to +10D, the cylindrical refractive power is -0.5DC to -3.5DC, the cylindrical axis is 0 to 180 degrees, and the spherical aberration is -2D to +2D. A front toric soft contact lens according to claim 1 or claim 2.

8. The refractive index of the lens material is 1.38 to 1.

5. A front toric soft contact lens according to claim 1 or claim 2.

9. The diameter of the aforementioned toric soft contact lens is 13.5 mm to 15 mm. A front toric soft contact lens according to claim 1 or claim 2.

10. The diameter of the circular optical zone is 6 to 9 mm. A front toric soft contact lens according to claim 1 or claim 2.

11. The number of discrete points of density selected along each of the aforementioned semi-meridians is at least 100. A front toric soft contact lens according to claim 1 or claim 2.

12. The number of discrete points of density selected along each of the aforementioned semi-meridians is 32 to 256. A front toric soft contact lens according to claim 1 or claim 2.

13. The number of discrete points of density selected along each of the aforementioned semi-meridians is between 256 and 10,000. A front toric soft contact lens according to claim 1 or claim 2.

14. The aforementioned edge is defined as a rounded edge. A front toric soft contact lens according to claim 1 or claim 2.

15. The aforementioned edge is defined as a chisel edge. A front toric soft contact lens according to claim 1 or claim 2.

16. The aforementioned edge is defined as a knife edge. A front toric soft contact lens according to claim 1 or claim 2.

17. The axial thickness profiles along each of the plurality of semi-meridians within the optical zone are used to realize the refractive power profile. A front toric soft contact lens according to claim 1 or claim 2.

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