Flexible liquid crystal-containing lens

Abstract

An electrically switchable flexible ophthalmic lens for fitting to an eye of a user is provided. The lens comprises a flexible liquid crystal cell for varying an optical property of the ophthalmic lens, and a plurality of support members. The flexible liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface, with liquid crystal therebetween. The flexible liquid crystal cell has a chordal radius w. Each support member is arranged to maintain the cell gap thickness by providing support at one or more support locations within the cell. The plurality of support members are arranged such that the support locations form two rings that are concentric about a center of the liquid crystal cell. A first ring is located at a chordal measurement of 0.26-0.34w from the center of the liquid crystal cell, and a second ring is located at a chordal measurement of 0.52-0.70w from the center of the liquid crystal cell.

Description

[Technical Field]

[0001] This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 63 / 143,157, filed January 29, 2021, which is incorporated by reference in its entirety.

[0002] The present invention relates to electrically switchable flexible liquid crystal lenses and liquid crystal cells for such lenses, for example flexible contact lenses comprising one or more flexible liquid crystal cells. [Background technology]

[0003] Soft contact lenses containing electrically switchable liquid crystals are known. The liquid crystals are typically held in liquid crystal cells within a cavity. When the contact lens is placed on a wearer's cornea, the posterior surface of the contact lens conforms to the shape of the cornea, resulting in distortion of the liquid crystal cell. When the liquid crystal containing soft contact lenses is worn on the eye, gravity and eyelid pressure can exacerbate this distortion. Such distortion is undesirable because it adversely affects the optical properties of the contact lens, such as blurring vision and increasing optical aberrations in the contact lens.

[0004] It would be desirable to provide soft contact lenses having a liquid crystal optical component that inhibits liquid crystal cell distortion and / or reduces the effect of liquid crystal cell distortion on the optical performance of the contact lens. Summary of the Invention

[0005] According to a first aspect, the present invention provides an electrically switchable flexible ophthalmic lens for fitting to an eye of a user, comprising: a liquid crystal cell for varying at least one optical property of the ophthalmic lens; and one or more support members, wherein the flexible liquid crystal cell has a cell gap thickness between first and second inner surfaces and has liquid crystal therebetween, each support member being arranged to maintain the cell gap thickness by providing support at one or more support locations within the cell, and the support members being arranged such that the support locations form one or more rings concentric with a center of the liquid crystal cell.

[0006] Applicant has surprisingly found that providing multiple support locations in the form of rings is particularly effective in maintaining cell spacing even when the liquid crystal cells are subjected to deformation forces such as those that occur when the lens is placed on the wearer's cornea.

[0007] Optionally, substantially all of the plurality of support members are arranged such that the plurality of support locations form one or more rings, in which case there may be substantially no support locations that do not form one of the rings, although peripheral support may be present, as described below.

[0008] Those skilled in the art will understand that the term "ring" does not imply that the ring is perfectly circular. In this regard, each of the support locations forming each ring may be within 30% of the average distance between the center of the liquid crystal cell and the support locations forming that ring. Each of the support locations forming each ring may optionally be within 25%, optionally within 25%, optionally within 20%, optionally within 15%, optionally within 10%, and optionally within 5% of the average distance between the center of the liquid crystal cell and the support locations forming that ring.

[0009] When the plurality of support locations form one (and only one) ring, optionally, the average distance between the center of the liquid crystal cell and the plurality of support locations forming the ring is approximately the same as, or optionally less than, the closest distance between the plurality of support locations forming the ring and the surrounding support feature.

[0010] The liquid crystal cell optionally has a peripheral support feature to maintain a peripheral gap thickness around the perimeter of the liquid crystal cell.

[0011] The liquid crystal cell optionally has a half-width w. The half-width can be defined by a peripheral support configuration. Those skilled in the art will understand that the liquid crystal cell can be curved. In that case, the half-width of the liquid crystal cell can be measured along a chord. The liquid crystal cell can optionally include a disk-shaped spherical cap or a distorted spherical cap of liquid crystal. For example, the peripheral support configuration can optionally be in the form of a ring. For example, the peripheral support configuration can optionally be annular. In this case, the half-width can be the radius of the circle of liquid crystal. The half-width w can be, for example, the chord radius when the liquid crystal cell has a spherical cap or a distorted spherical cap of liquid crystal. Thus, the liquid crystal cell can have a chord radius w.

[0012] The support locations may optionally form one (and only one) ring. Each support location forming the ring may optionally be located 0.30W to 0.60W from the center of the liquid crystal cell, and optionally may be located 0.35W to 0.50W from the center of the liquid crystal cell. The locations of the support locations may be determined using chord measurements.

[0013] The plurality of support locations may optionally form two or more rings concentric with respect to the center of the liquid crystal cell. When the plurality of support locations form two rings, optionally, the average distance between the center of the liquid crystal cell and the plurality of support locations forming a first inner ring may be approximately the same as the average distance between the plurality of support locations forming the first ring and the plurality of support locations forming a second outer ring.

[0014] When the multiple support locations form three or more rings, the distance between adjacent rings may be approximately the same.

[0015] The plurality of support locations may optionally form two (and only two) rings. The plurality of support locations may optionally form three (and only three) rings.

[0016] As described above, the plurality of support locations may form a first inner ring and a second outer ring. The average distance of the plurality of support locations in the first ring from the center of the liquid crystal cell may be denoted d1. The average distance of the plurality of support locations in the second ring from the center of the liquid crystal cell may be denoted d2. Optionally, the ratio d2:d1 may be at least 1.2:1, optionally at least 1.5:1, optionally at least 1.8:1, or optionally at least 2.0:1. The ratio d2:d1 may be 3.0:1 or less, optionally 2.5:1 or less, optionally 2.0:1 or less, optionally 1.8:1 or less, or optionally 1.5:1 or less. The ratio may optionally be between 1.2:1 and 3.0:1, optionally between 1.5:1 and 2.5:1, or optionally between 1.8:1 and 2.5:1. The distances of the support locations of the first and second rings from the center of the liquid crystal cell may be chordal measurements.

[0017] At least one ring, optionally two or more rings, and optionally each ring may be substantially annular. The annular support form may have an annular support member, the annular shape of which may define the annular shape of the support form. The annular support member may have two semi-annular support members, which may be arranged to define an annular ring. The annular ring may be defined by a plurality of arcuate support members. The annular ring may be defined by a plurality of "point" support members (such as cylindrical or spherical).

[0018] The plurality of support locations may optionally form a first ring and a second ring. Each support location forming the first ring may optionally be located 0.16W to 0.50W from the center of the liquid crystal cell, optionally 0.24W to 0.40W from the center of the liquid crystal cell, or optionally 0.26W to 0.34W from the center of the liquid crystal cell. Each support location forming the second ring may optionally be located 0.52W to 0.80W from the center of the liquid crystal cell, optionally 0.52W to 0.75W from the center of the liquid crystal cell, optionally 0.56W to 0.70W from the center of the liquid crystal cell, or optionally 0.60W to 0.68W from the center of the liquid crystal cell.

[0019] Thus, the plurality of support locations may form two rings concentric with respect to the center of the liquid crystal cell, with the first ring being located at a chord measurement of 0.26 to 0.34w from the center of the liquid crystal cell and the second ring being located at a chord measurement of 0.52 to 0.70w from the center of the liquid crystal cell.

[0020] Each support member can be positioned to contact the first and second inner surfaces to maintain the cell gap thickness by providing support at a (predetermined) support location within the cell, where multiple support members can be positioned between the first and second inner surfaces.

[0021] In plan view, the center of a liquid crystal cell may be the physical center of the cell or may form the center of a support form. The center may be defined as an axis.

[0022] At least one ring, optionally two or more rings, and optionally each ring may be formed by two or more support members.

[0023] At least one ring, optionally two or more rings, and optionally each ring may be formed by three or more support members, optionally four or more support members, optionally six or more support members, optionally eight or more support members, optionally ten or more support members, optionally twelve or more support members.

[0024] When a ring is formed by two or more support members, the support members may optionally be uniformly spaced within the ring, e.g., the distance between adjacent support members forming each ring may be substantially the same.

[0025] Each support member may have any suitable shape, for example, the support members may be cylindrical, spherical, cylindrical, ellipsoidal, ovoid, or arcuate.

[0026] A ring may include multiple support members of different shapes, optionally multiple support members of the same shape, and optionally multiple support members of the same size.

[0027] When the support member is arcuate, the arc may be a circular arc or a non-circular arc.

[0028] The arcuate angle of the arcuate support members can be between 5 degrees and 360 degrees, typically depending on the number of support members comprising each support configuration. For example, if each ring is formed by six or more arcuate support members, the arcuate angle of each support member can optionally be between 5 degrees and 30 degrees, optionally between 5 degrees and 20 degrees, or optionally between 5 degrees and 10 degrees. If a ring is formed by a single (i.e., only one) arcuate support member, the arcuate angle can optionally be at least 240 degrees, optionally at least 300 degrees, and optionally between 330 degrees and 360 degrees. If a ring is formed by two (and only two) arcuate support members, the arcuate angle of each arcuate support member can optionally be between 120 degrees and 180 degrees. The support members can be provided with one or more recesses or openings for liquid crystal to pass through. For example, if the support member is elongated, such as semi-annular, or if the support member is annular, the absence of such recesses or openings may cause the support member to act as a barrier to the flow of liquid crystal, which may be undesirable in some circumstances. The support member may be provided with a plurality of recesses or openings for the liquid crystal to pass through or through it.

[0029] The one or more support members may comprise a polymer such as polydimethylsiloxane (PDMS). The one or more support members may comprise a material having a Young's modulus of 100 to 5000 kPa, optionally a Young's modulus of 200 to 2000 kPa, optionally a Young's modulus of 200 to 1000 kPa.

[0030] The cell gap thickness may be substantially uniform across the entire liquid crystal cell when the lens is undeformed. Alternatively, the cell gap thickness may not be uniform across the entire liquid crystal cell even when the lens is undeformed. In this case, the cell gap thickness will depend on the position within the liquid crystal cell. For example, if an ophthalmic lens includes a so-called meniscus lens, one of the first and second inner surfaces is typically convex and the other is concave, and the cell gap thickness at any point within the liquid crystal cell is determined by the curvatures of the convex and concave surfaces. For example, if the liquid crystal cell includes a Fresnel lens structure, the cell gap thickness at a particular point within the liquid crystal cell may depend on the height of the Fresnel lens structure at that point within the cell.

[0031] The maximum cell gap thickness (the maximum distance between the first and second inner surfaces of the undeformed cell) can optionally be at least 2 μm, optionally at least 5 μm, optionally at least 10 μm, optionally at least 15 μm, or optionally at least 20 μm. The maximum cell gap thickness can optionally be 200 μm or less, optionally 150 μm or less, optionally 100 μm or less, optionally 75 μm or less, or optionally 50 μm or less. The maximum cell gap thickness can optionally be between 10 μm and 100 μm, or optionally between 20 μm and 75 μm.

[0032] The maximum dimension, such as width or diameter (chord diameter), of the liquid crystal cell can optionally be 20 mm or less, optionally 15 mm or less, optionally 12 mm or less, optionally 10 mm or less, optionally 8 mm or less, optionally 6 mm or less, or optionally 4 mm or less. The maximum dimension of the liquid crystal cell can optionally be at least 3 mm, optionally at least 5 mm, or optionally at least 7 mm.

[0033] The maximum dimension, such as width or diameter (chord diameter), of the ophthalmic lens may optionally be 20 mm or less, optionally 18 mm or less, optionally 16 mm or less, optionally 14 mm or less, optionally 12 mm or less, or optionally 10 mm or less. The maximum dimension of the ophthalmic lens may optionally be at least 6 mm, optionally at least 8 mm, optionally at least 10 mm, or optionally at least 12 mm. In some embodiments, the diameter of the ophthalmic lens is between 10 mm and 16 mm.

[0034] At least one, and optionally each, of the first and second inner surfaces may optionally be provided with one or more surface treatments for aligning liquid crystals. For example, the one or more surface treatments may include one or more alignment layers. At least one, and optionally each, alignment layer may include a polymer, such as an organic polymer, or a vapor-deposited inorganic material, such as silicon oxide. Such polymers may be at least partially aligned by applying a shear force to the surface of the polymer, e.g., by brushing the surface of the polymer. Such polymers typically cause liquid crystals to adopt a particular desired orientation. For example, the director of the liquid crystal adjacent to the polymer may have a preferred in-plane alignment. Furthermore, the liquid crystal may have a low pretilt (e.g., 10° or less, optionally 5° or less, or optionally 3° or less) near the polymer. The one or more surface treatments may align the liquid crystals at a high pretilt orientation (e.g., a pretilt of 60° or more, optionally 70° or more, optionally 80° or more, or optionally 85° or more). The surface treatments may align the liquid crystals in a substantially homeotropic alignment, with the director substantially perpendicular to the first and second inner surfaces.

[0035] The surface treatments of the first and second inner surfaces are typically selected to impart a particular alignment (orientation) to the liquid crystals, for example, the surface treatments of the first and second surfaces can be arranged to cause the liquid crystals to assume a twisted nematic alignment.

[0036] The liquid crystal cell may have a first substrate and a second substrate to provide support for the liquid crystal cell. The first substrate and the second substrate are typically flexible. The liquid crystal cell may be flexible.

[0037] One or both of the first and second substrates may be provided with a conductive layer facing the liquid crystal in the cell. The conductive layer may comprise any suitable conductive material, such as indium tin oxide (ITO). The conductive layer is typically suitably transparent to allow the lens to function as a lens. A non-conductive layer may be provided on each conductive layer. The non-conductive layer may be disposed between the conductive layer and a respective surface treatment (e.g., alignment layer) for aligning the liquid crystal.

[0038] The liquid crystal may be any suitable liquid crystal, such as liquid crystals known to those skilled in the art, such as E7 from Merck.

[0039] The liquid crystal may optionally be in a nematic liquid crystal phase at typical operating temperatures, for example, 25° C. The liquid crystal may optionally be in a nematic phase between 10° C. and 40° C., optionally between −5° C. and 50° C.

[0040] Those skilled in the art will appreciate that liquid crystal phases other than nematic phases may be used, for example the liquid crystal may be in a smectic phase at typical operating temperatures.

[0041] The peripheral gap thickness may optionally be approximately the same as the maximum cell gap thickness, although this will depend on the properties of the ophthalmic lens.

[0042] Alternatively, the maximum cell gap thickness may be smaller than the peripheral gap thickness. This may be true, for example, when the cell includes a second liquid crystal layer in addition to the liquid crystal layer between the first and second inner surfaces. In this regard, the liquid crystal cell may have a cell gap between the third and fourth inner surfaces and include liquid crystal therein. The liquid crystal between the third and fourth inner surfaces is in substantially the same optical path as the liquid crystal between the first and second inner surfaces. The liquid crystal cell may include one or more spacers to maintain the cell gap between the third and fourth inner surfaces. Optionally, each spacer is arranged to maintain the cell gap by providing support at a support position within the cell. The one or more spacers may be arranged in a manner similar to the support members between the first and second inner surfaces. In this regard, substantially all of the spacers may be arranged so that the support positions form one or more rings concentric with the center of the liquid crystal cell. For the avoidance of doubt, the cell gap may be substantially uniform throughout the liquid crystal cell. Alternatively, the cell gap need not be uniform throughout the liquid crystal cell. In this case, the cell spacing will depend on the position within the liquid crystal cell. For example, if the ophthalmic lens includes a so-called meniscus lens, one of the third and fourth inner surfaces is typically convex and the other is concave, and the cell spacing at any point within the liquid crystal cell is determined by the curvatures of the convex and concave surfaces. For example, if the liquid crystal cell includes a Fresnel lens structure, the cell spacing at a particular point within the liquid crystal cell may depend on the height of the Fresnel lens structure at that point within the cell.

[0043] Each spacer may contact the third and fourth inner surfaces to maintain the cell spacing.

[0044] The one or more rings may have the features described above in connection with the one or more rings used to maintain a cell gap thickness between the first and second inner surfaces.

[0045] The one or more spacers may have the characteristics described above with respect to the one or more support members used to maintain the cell gap thickness between the first and second inner surfaces.

[0046] The ophthalmic lens may have any suitable configuration to provide a desired optical effect. For example, the ophthalmic lens may have a Fresnel lens structure. Such a Fresnel lens structure may define the shape of one of the first and second surfaces. A liquid crystal disposed between the first and second surfaces may be switchable between a first liquid crystal configuration and a second liquid crystal configuration. The difference in refractive index between the liquid crystal and the material forming the Fresnel lens structure is smaller in one of the first and second liquid crystal configurations than in the other of the first and second liquid crystal configurations. In one of the first and second liquid crystal configurations, the difference in refractive index between the liquid crystal and the material forming the Fresnel lens may be small, or the refractive index of the liquid crystal may be "matched" to the refractive index of the material forming the Fresnel lens. Thus, in one of the liquid crystal configurations (where the refractive index of the Fresnel lens material and the liquid crystal are mismatched), the Fresnel lens refracts light as a lens, while in the other of the liquid crystal configurations (where the refractive index of the Fresnel lens material and the liquid crystal are matched), the Fresnel lens does not refract light as a lens, or refracts light significantly less.

[0047] The height of the support members depends on the geometry of the Fresnel lens structure and the position of the support members relative to the Fresnel lens. For example, if the support members are located on the peaks or apexes of the Fresnel lens, the height of the support members will typically be less than if the support members are located on the valleys of the Fresnel lens structure.

[0048] The ophthalmic lens may include, for example, a meniscus lens. One of the first and second surfaces is convex, and the other of the first and second surfaces is concave. The curvatures of the first and second surfaces may be the same or different. For example, the curvature of the convex surface may be greater or less than the curvature of the concave surface. The cell gap thickness in such a meniscus lens optionally varies depending on the position within the liquid crystal cell. For example, the cell gap thickness at the center of the meniscus lens may be greater than that at the periphery of the lens. Alternatively, the cell gap thickness at the periphery of the lens may be greater than that at the center of the lens. The height of the support members may be selected to maintain these cell gap thicknesses. The ophthalmic lens may include multiple meniscus lenses. For example, the ophthalmic lens may include a first meniscus lens and a second meniscus lens located in the same optical path as the first meniscus lens.

[0049] The ophthalmic lens may comprise, for example, a gradient index (GRIN) lens. A GRIN lens is comprised of a lens in which the refractive index of the liquid crystal depends on the lateral position of the liquid crystal cell. A change in refractive index across the liquid crystal cell is typically achieved by liquid crystal molecules having different orientations at different positions across the liquid crystal cell. This is optionally achieved using different surface treatments on the first and / or second surfaces in different regions of the liquid crystal cell to achieve different pretilts of the liquid crystal molecules at the first or second surface and their adjacent liquid crystal molecules. In a GRIN lens, the cell spacing between the first and second surfaces may be substantially uniform across the liquid crystal cell. Alternatively, the cell spacing may not be substantially uniform across the liquid crystal cell. When a switching voltage is applied, the orientation of at least some of the liquid crystal molecules in the GRIN cell changes, thereby changing the refractive index of the liquid crystal associated with the change in orientation. The ophthalmic lens may comprise multiple GRIN lenses. For example, an ophthalmic lens may comprise a first GRIN lens and a second GRIN lens positioned in the same optical path as the first GRIN lens.

[0050] The ophthalmic lens may be a contact lens.

[0051] The liquid crystal cell is provided to modify at least one optical property of the ophthalmic lens, such as the focal length of the ophthalmic lens.

[0052] As described above, one or more support members are used to maintain the cell gap thickness. To achieve this, the one or more support members are typically attached to another portion of the liquid crystal cell. For example, an adhesive may be used to attach the one or more support members to another portion of the liquid crystal cell. For example, an adhesive may be used to attach the one or more support members to one or both of the first inner surface and the second inner surface.

[0053] As mentioned above, each support member is positioned to maintain a cell gap thickness, which is important for maintaining the optical properties of the ophthalmic lens. In this regard, the average change in cell gap thickness across the liquid crystal cell may optionally be 15% or less, optionally 12% or less, optionally 10% or less, optionally 8% or less, or optionally 5% or less when the ophthalmic lens is deformed by being worn on a user's eye.

[0054] According to a second aspect of the present invention, there is provided a flexible liquid crystal cell suitable for a lens according to the first aspect of the present invention.

[0055] Thus, there is provided a liquid crystal cell for altering at least one optical property of an ophthalmic lens, the liquid crystal cell having a cell gap thickness between first and second inner surfaces and comprising one or more support members, each support member arranged to maintain the cell gap thickness by providing support at one or more support locations within the cell, the plurality of support members (optionally all of the plurality of support members) being arranged so that the support locations form one or more rings concentric with the center of the liquid crystal cell.

[0056] The liquid crystal cell may therefore have the features described above in relation to the lens of the first aspect of the invention.

[0057] According to a third aspect of the present invention, there is provided an electrically switchable flexible ophthalmic lens comprising a liquid crystal cell for varying at least one optical property of the ophthalmic lens, the flexible ophthalmic lens having a cell gap thickness between first and second inner surfaces, and a plurality of support members, each support member arranged to maintain the cell gap thickness by providing support at one or more support locations within the cell, the plurality of support members (optionally all of the plurality of support members) being arranged such that the support locations form two annular rings concentric with a center of the liquid crystal cell.

[0058] Applicant has surprisingly found that the provision of a plurality of support members in the form of two annular rings is particularly effective in mitigating degradation of lens performance when the lens is placed on the wearer's cornea. For the avoidance of doubt, there are substantially no support members providing support positions outside the annular rings.

[0059] The liquid crystal cell optionally has peripheral support features to maintain a cell gap thickness around the periphery of the liquid crystal cell.

[0060] The lens may be a contact lens.

[0061] The lens of the third aspect of the invention may comprise features of the lens of the first aspect of the invention and / or the liquid crystal cell of the second aspect of the invention.

[0062] According to a fourth aspect of the present invention there is provided a liquid crystal cell suitable for a lens according to the third aspect of the present invention. According to the fourth aspect of the present invention there is therefore provided a liquid crystal cell for altering at least one optical property, such as refractive index, of an ophthalmic lens, the liquid crystal cell having a cell gap thickness between first and second inner surfaces and comprising a plurality of support members, each support member arranged to maintain the cell gap thickness by providing support at one or more support locations within the cell, the plurality of support members (optionally all of the plurality of support members) being arranged so that the support locations form two annular rings concentric about a centre of the liquid crystal cell.

[0063] The liquid crystal cell of the fourth aspect of the invention may comprise the features described above in relation to the first, second and third aspects of the invention.

[0064] According to a fifth aspect of the present invention, there is provided an electrically switchable flexible ophthalmic lens comprising a liquid crystal cell for varying at least one optical property of the ophthalmic lens, the flexible ophthalmic lens having a cell gap thickness between a first inner surface and a second inner surface, and one or more arcuate support members that help maintain the cell gap thickness.

[0065] Applicant has discovered that the cell gap thickness of a liquid crystal cell in a flexible lens can be maintained using arcuate support members. Furthermore, such arcuate support members can be used to define a ring of support locations within the liquid crystal cell, which has proven useful in mitigating the adverse effects associated with cell deformation when the lens is placed on a wearer's eye. The arcuate shape of the arcuate support members can be arcuate or non-arcuate.

[0066] The arcuate angle of an arcuate support member can be between 5 degrees and 360 degrees. For example, when multiple support members are used in combination to define a ring of support locations within a liquid crystal cell, the arcuate angle can optionally depend on the number of support members forming the ring. For example, when each ring is formed by six or more arcuate support members, the arcuate angle of each support member can optionally be between 5 degrees and 30 degrees, optionally between 5 degrees and 20 degrees, or optionally between 5 degrees and 10 degrees. When a ring is formed by a single (i.e., only one) arcuate support member, the arcuate angle can optionally be at least 240 degrees, optionally at least 300 degrees, and optionally between 330 degrees and 360 degrees. When a ring is formed by two (and only two) arcuate support members, the arcuate angle of each arcuate support member can be between 120 degrees and 180 degrees.

[0067] The one or more arcuate support members may be provided with one or more recesses or openings for the liquid crystal to pass through. For example, if the support member is elongated, such as semi-annular, or if the support member is annular, the absence of such recesses or openings may cause the support member to act as a barrier to the flow of the liquid crystal, which may be undesirable in some circumstances. The support member may be provided with multiple recesses or openings for the liquid crystal to pass through or through.

[0068] The lens may be a contact lens.

[0069] The lens of the fifth aspect of the invention may comprise one or more features of the first to fourth aspects of the invention.

[0070] The present invention further provides a liquid crystal cell for use in the lens of the fifth aspect of the present invention. According to a sixth aspect of the present invention, there is provided a liquid crystal cell having a cell gap thickness between a first inner surface and a second inner surface, and comprising one or more arcuate support members that assist in maintaining the cell gap thickness.

[0071] The liquid crystal cell of the sixth aspect of the invention may comprise one or more features of the first to fifth aspects of the invention.

[0072] The following lenses are also provided according to the following clause (clauses): Section A - An electrically switchable flexible ophthalmic lens for fitting to a user's eye, comprising: a flexible liquid crystal cell for changing at least one optical property of said ophthalmic lens; A plurality of support members; Equipped with the flexible liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface, and has liquid crystal therebetween; the flexible liquid crystal cell has a chord radius w; each support member is positioned to maintain the cell gap thickness by providing support at one or more support locations within the cell; the plurality of support members are arranged so that the support positions form two rings that are concentric with the center of the liquid crystal cell; the first ring is located at a chord measurement distance of 0.26 to 0.34w from the center of the liquid crystal cell; The second ring is located at a chord measurement distance of 0.52 to 0.70 w from the center of the liquid crystal cell. A lens characterized by:

[0073] Section B - The lens of section A, wherein the first ring is located at a chord measurement of 0.30 to 0.34w from the center of the liquid crystal cell.

[0074] Section C - The lens of paragraph A or B, wherein the second ring is located at a chord measurement of 0.56 to 0.70w from the center of the liquid crystal cell.

[0075] Section D - A lens according to any one of sections A to C, wherein the support locations form two (and only two) rings.

[0076] Section E - The lens of any one of sections A to D, wherein the first ring and the second ring are each formed by two or more support members.

[0077] Section F - The distance between adjacent support members forming each ring is approximately the same 10. The lens of claim E, wherein:

[0078] Section G - The lens of any of Sections A to F, wherein one or more of the support members are cylindrical, spherical, cylindrical, ellipsoidal, ovoid, elongated, annular, semi-annular, or arcuate.

[0079] Section H - The lens of any of sections A to G, characterized in that the cell gap thickness is substantially uniform across the liquid crystal cell.

[0080] Section I - The lens of any of sections A to G, wherein the cell gap thickness is not uniform across the liquid crystal cell.

[0081] Section J - The lens of any of Sections A-I, wherein the liquid crystal cell has a peripheral support feature for maintaining a peripheral gap thickness around the liquid crystal cell.

[0082] Section K - The lens of any of Sections A-J, wherein substantially all of the support members are arranged such that the support positions form two rings, and substantially no support members are present outside of the rings.

[0083] Section L - The lens of any of Sections A to K, wherein the liquid crystal cell has a cell gap between a third inner surface and a fourth inner surface, and has liquid crystal therebetween, and the liquid crystal between the third inner surface and the fourth inner surface is in substantially the same optical path as the liquid crystal between the first inner surface and the second inner surface.

[0084] Section M - The lens described in Section L, characterized in that the liquid crystal cell has one or more spacers to maintain the cell spacing between the third inner surface and the fourth inner surface.

[0085] Section N - A lens described in Section M, characterized in that substantially all of the spacers are arranged so that the support positions form one or more rings, optionally two rings, or optionally only two rings, concentric with the center of the liquid crystal cell.

[0086] 10. The lens of any of paragraphs A-N, comprising: a section O - Fresnel lens structure, the Fresnel lens structure optionally defining the shape of one of the first surface and the second surface, the liquid crystal disposed between the first surface and the second surface optionally switchable between a first liquid crystal configuration and a second liquid crystal configuration, wherein in one of the first liquid crystal configuration and the second liquid crystal configuration, there is a smaller difference in refractive index between the liquid crystal and a material forming the Fresnel lens structure than in the other of the first liquid crystal configuration and the second liquid crystal configuration.

[0087] Section P - The lens of any of Sections A to N, comprising a meniscus lens, wherein one of the first surface and the second surface is convex and the other of the first surface and the second surface is convex, and the curvatures of the first surface and the second surface are the same or different.

[0088] Section Q - A lens according to any one of Sections A to N, comprising a gradient index (GRIN) lens.

[0089] It will of course be understood that features described in relation to one aspect of the invention may be incorporated in other aspects of the invention, for example a lens of the first aspect of the invention may incorporate any of the features described with reference to a lens of the fifth aspect of the invention, and vice versa.

[0090] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which: [Brief explanation of the drawings]

[0091] [Figure 1A] FIG. 1A shows a schematic plan view of an example of an electrically switchable flexible ophthalmic lens according to a first embodiment of the present invention.

[0092] [Figure 1B] FIG. 1B shows a schematic cross-sectional view of the lens of FIG. 1A as it would appear on a wearer's eye.

[0093] [Figure 2A] FIG. 2A shows a cross-sectional view of another example of an electrically switchable flexible ophthalmic lens according to a second embodiment of the present invention.

[0094] [Figure 2B] FIG. 2B shows a schematic cross-sectional view of the lens of FIG. 2A.

[0095] [Figure 3A] FIG. 3A shows a plan view of an example of a plurality of arcuate support members arranged to provide ring-shaped support locations for use within a lens, according to another embodiment of the present invention.

[0096] [Figure 3B] FIG. 3B shows a plan view of an example of multiple cylindrical support members arranged to provide ring-shaped support locations for use within a lens, according to another embodiment of the present invention.

[0097] [Figure 3C] FIG. 3C shows a plan view of two generally semi-annular support members arranged to provide a ring-shaped support location for use within a lens, according to another embodiment of the present invention.

[0098] [Figure 3D]FIG. 3D shows a plan view of an annular support member that provides a ring-shaped support location for use within a lens, according to another embodiment of the present invention.

[0099] [Figure 4] FIG. 4 shows a schematic cross-sectional view of an example of a liquid crystal cell according to one embodiment of the present invention.

[0100] [Figure 5] FIG. 5 is a schematic cross-sectional view of another example of a liquid crystal cell according to another embodiment of the present invention.

[0101] [Figure 6A] Figures 6A-6D show how the simulated range of optical power deviation due to lens deformation varies as a function of the position of the two annular support members within the lens for four cases representing all four combinations of the two conditions (radial polarization / circumferential polarization x powered / unpowered liquid crystal). [Figure 6B] Figures 6A-6D show how the simulated range of optical power deviation due to lens deformation varies as a function of the position of the two annular support members within the lens for four cases representing all four combinations of the two conditions (radial polarization / circumferential polarization x powered / unpowered liquid crystal). [Figure 6C] Figures 6A-6D show how the simulated range of optical power deviation due to lens deformation varies as a function of the position of the two annular support members within the lens for four cases representing all four combinations of the two conditions (radial polarization / circumferential polarization x powered / unpowered liquid crystal). [Figure 6D]Figures 6A-6D show how the simulated range of optical power deviation due to lens deformation varies as a function of the position of the two annular support members within the lens for four cases representing all four combinations of the two conditions (radial polarization / circumferential polarization x powered / unpowered liquid crystal).

[0102] [Figure 7A] 7A and 7B show simulated histograms of the refractive power of the lens for random polarization when the positions of the two ring-shaped supports are selected from the minimum deviation region (d1=0.31 and d2=0.66) of FIG. 6. [Figure 7B] 7A and 7B show simulated histograms of the refractive power of the lens for random polarization when the positions of the two ring-shaped supports are selected from the minimum deviation region (d1=0.31 and d2=0.66) of FIG. 6.

[0103] [Figure 8] 8 shows a schematic cross-sectional view of an example of a lens according to an embodiment of the present invention, the lens comprising a Fresnel optical element. DETAILED DESCRIPTION OF THE INVENTION

[0104] An example of a flexible lens according to the present invention is shown schematically in FIGS. 1A and 1B. FIG. 1A shows a schematic plan view of the lens, and FIG. 1B shows a schematic cross-sectional view of the lens when placed on a wearer's cornea. The electrically switchable flexible ophthalmic lens 1 comprises a flexible liquid crystal cell 3 embedded in a lens body 2. The lens body 2 has a shape typical of a soft contact lens. In this case, the ophthalmic lens is a soft contact lens. The liquid crystal cell 3 has a cell gap thickness between a first inner surface 4 and a second inner surface 5, and contains liquid crystals 9 therebetween. As shown in FIG. 1A and other figures, the liquid crystal cell 3 has a generally circular shape in plan view. The lens body 2 comprises silicone. The lens body may comprise hydrogel, silicone hydrogel, or silicone elastomer. The liquid crystal cell 3 has a peripheral support structure 6 for maintaining the peripheral gap thickness around the liquid crystal cell. The peripheral support structure 6 comprises an annular strip 6a of a 50-micron-thick spacer sheet (e.g., Mylar®). The liquid crystal cell 3 has two support members in the form of two annular support members 7, 8. The two annular support members 7, 8 are arranged to maintain the cell gap thickness by providing support at multiple support locations within the cell. The multiple support locations provided by the two annular support members 7, 8 form two rings that are concentric about the center of the liquid crystal cell 3. The annular support members 7, 8 can be fabricated by any suitable method, such as using a source of appropriate radiation (typically UV radiation) and a mask to control the exposure of a radiation-sensitive material (such as a photopolymer).

[0105] A cross-sectional view of the lens can be seen in Figure 1B. The lower surface L of the lens 1 conforms to the shape of the underlying eye (including the cornea). This causes the lens 1 to deform and a deformation force is applied to the liquid crystal cell 3. The use of two spaced apart annular support members 7, 8 has proven particularly effective in reducing unwanted distortion of the liquid crystal cell 3 and unwanted thickness variations in the liquid crystal layer when the lens is placed on the wearer's cornea.

[0106] It is noteworthy that the first inner surface 4 and the second inner surface 5 are spaced apart by a peripheral support member 6 and two annular support members 7, 8. There are substantially no other spacers or other support members separating the first inner surface 4 and the second inner surface 5. With the exception of the peripheral support of the liquid crystal cell 3, all of the support locations are arranged in the shape of two rings formed by the two annular support members 7, 8.

[0107] The first and second inner surfaces 4, 5 of the liquid crystal cell are provided with an alignment polymer (not shown in FIG. 1 but described below in connection with FIG. 4) that aligns the liquid crystal 9, so that the liquid crystal cell 3 has the desired optical properties for the lens 1. A conductive layer is also provided to enable switching of the liquid crystal 9 (also not shown in FIG. 1 but described below in connection with FIG. 4).

[0108] Next, a further example of a flexible lens according to the present invention will be described with reference to FIGS. 2A and 2B. FIG. 2A is a schematic cross-sectional view of a portion of lens 1001, showing the location of multiple support members that act to constrain deformation of the liquid crystal cell. FIG. 2B is a schematic cross-sectional view of lens 1001, showing the arrangement of liquid crystals within the lens. Lens 1001 is similar to lens 1 of FIG. 1A in that lens 1001 includes a liquid crystal cell 1003 embedded within lens body 1002. Lens body 1002 has a shape typical of a soft contact lens. Like the liquid crystal cell of FIG. 1A, liquid crystal cell 1003 has a generally circular shape. Furthermore, like the lens of FIG. 1A, liquid crystal cell 1003 is provided with two annular support members 1007 and 1008. The two annular support members 1007 and 1008 are arranged to maintain a cell gap thickness between first inner surface 1004 and second inner surface 1005 by providing support at multiple support locations within the cell. The multiple support locations provided by the two annular support members 1007 and 1008 form two rings concentric with the center of the liquid crystal cell 1003, which is indicated by axis C. The ring formed by support member 1007 has a chord radius r1, and the ring formed by support member 1008 has a chord radius r2. As shown in FIG. 2A, r1 is approximately 0.3w, where w is the distance from the center C of the liquid crystal cell to the edge of the liquid crystal cell, and r2 is approximately 0.85w. As with the lens of FIGS. 1A and 1B, the lens 1001 of FIGS. 2A and 2B is provided with a peripheral support structure 1006. In this case, the peripheral support structure 1006 comprises an annular peripheral member of a polymer having a Young's modulus of 500 kPa. The annular support members 1007 and 1008 are also provided by a polymer having a Young's modulus of 500 kPa.

[0109] The lenses of FIGS. 2A and 2B differ from the lenses of FIGS. 1A and 1B in several important respects. While the liquid crystal cells of FIGS. 1A and 1B have a single liquid crystal cell, the liquid crystal cell 1003 of FIGS. 2A and 2B has two liquid crystal layers 1009, 1009′, each of which is in the same optical path. The liquid crystal 1009 is located between a first inner surface 1004 and a second inner surface 1005, each of which has an alignment surface (not shown) that aligns the liquid crystal molecules substantially parallel to the inner surfaces 1004, 1005 radially outward from the center C (although the molecules may have a small pretilt near the inner surfaces 1004, 1005). The arrows indicate the approximate orientation of the liquid crystal molecules. The liquid crystal 1009′ is located between a third inner surface 1024 and a fourth inner surface 1025. The third inner surface 1024 and the fourth inner surface 1025 are provided with alignment polymers (not shown), which are brushed to align the liquid crystal molecules out of the plane of the figure. The alignment polymers in the left portion 1030 and the right portion 1031 are brushed in different directions, providing the left portion 1030 and the right portion 1031 with different directions of pretilt.

[0110] A conductive layer (not shown) is also provided to allow switching of the liquid crystals 1009, 1009'.

[0111] Applicant has investigated how the number and location of annular haptics affect the performance of a lens when placed on a wearer's cornea, and in this regard, Applicant's findings have demonstrated that the use of two annular haptics is preferable to the use of one (only one) haptic.

[0112] Applicant modeled the behavior of the liquid crystal cell as shown in Figures 2A and 2B to determine the optimal positions of the two annular support members, taking into account the optical performance of the liquid crystal cell in its unswitched and switched states using radially and circumferentially polarized light when the lens is placed on the wearer's cornea and deformed. In this regard, the various parameters of the lens are as follows: 14 mm diameter lens, radius of curvature of top lens surface - 8.4 mm, radius of curvature of bottom lens surface - 8.6 mm, 0.2 mm thick lens made of PDMS with an elastic modulus of 500 kPa, half width of the liquid crystal cell w - 3 mm, thickness of liquid crystal 1009 - 15 microns, thickness of liquid crystal 1009' - 15 microns, radius of curvature of the liquid crystal cell - 8.4 mm, n e (Abnormal refractive index) -1.9, n O (ordinary refractive index) -1.5.

[0113] The unswitched state corresponds to no applied switching voltage, and the switched state corresponds to a fully switched state, where the director of the liquid crystal is substantially parallel to the applied electric field.

[0114] Under these conditions, the refractive power of the aforementioned liquid crystal cell was investigated. The shape of the corneal surface was defined as the best sixth-order fit, as defined by Lee et al. in BMC Ophthalmology, 2016, 16:176. The bottom or posterior surface of the contact lens conformed to the corneal surface, causing deformation of the liquid crystal cell. The position r1 of the inner annular support was fixed at a value between 0w and 0.45w, where w is the chord radius of the liquid crystal cell, measured as shown in Figure 2A. For each such fixed position r1 of the inner annular support, the position r2 of the outer annular support was varied between 0.50w and 0.90w. For the avoidance of doubt, r1 and r2 are chord measurements. For each position of the inner and outer annular support, the refractive power of the liquid crystal cell was simulated for radially and circumferentially polarized light, in both the switched and unswitched states. The change in refractive power across the liquid crystal cell was simulated with the desire to minimize the change in refractive power across the liquid crystal cell for both radially and circumferentially polarized light, and to minimize the difference in refractive power between radially and circumferentially polarized light.

[0115] 6A-6D show the simulated power range (i.e., the variation in power across the lens) as a function of the position of the inner and outer annular supports for four combinations of the two conditions (radial polarization / circumferential polarization x powered / unpowered liquid crystal). FIG. 6A shows the simulated power range variation using circumferential polarization for unpowered liquid crystal. FIG. 6B shows the simulated power range variation using circumferential polarization for powered liquid crystal. FIG. 6C shows the simulated power range variation using radial polarization for unpowered liquid crystal. FIG. 6D shows the simulated power range variation using radial polarization for powered liquid crystal. In each of FIGS. 6A-6D, the position of the inner annular support is plotted on the x-axis as a function of the chord radius w of the liquid crystal cell. The position of the outer annular support is plotted on the y-axis as a function of the chord radius w of the liquid crystal cell. Figures 6A-6D show that for all four cases, the optimal combination of inner and outer annular support positions was surprisingly determined to be approximately 0.3W for the inner support and approximately 0.6W-0.7W for the outer support. When the annular supports were optimally positioned, the refractive power variation across the liquid crystal cell was found to be on the order of approximately 1-2D (see Figure 7). When the annular supports were absent or in different positions, the refractive power range was found to be higher, at least 4D in some cases. When the annular supports were absent, the center of the liquid crystal cell collapsed and the periphery of the liquid crystal cell bulged.

[0116] Further data demonstrating the performance of the lens are shown in Figures 7A and 7B. Figures 7A and 7B show power histograms for randomly polarized light in the powered (Figure 7A) and unpowered (Figure 7B) states. The x-axis shows power in D, and the y-axis shows the number of uniformly distributed test rays experiencing a range of powers. A narrower histogram is desirable, i.e., a larger percentage of the lens area is of the same power. The data shows that the range of power differences across the liquid crystal cell is small, with a 10-90% range of approximately 0.6D.

[0117] In the liquid crystal cells of Figures 1A, 1B, 2A, and 2B, each ring is formed by an annular support member. An annular support member 407 is also shown schematically in Figure 3D. However, such annular support member 407 does not allow liquid crystal flow therethrough unless a recess or opening is present. However, it may be desirable to allow liquid crystal flow within the liquid crystal cell. In this regard, the support configurations shown in plan view in Figures 3A-3C allow liquid crystal flow while providing a ring arrangement of support.

[0118] 3A shows a ring 107 formed from a plurality of arcuate posts, two of which are labeled 107a and 107b. Each arcuate post is a circular arc having an arc angle of approximately 10°, and the arcuate posts are uniformly distributed around the circumference of ring 107. There is a gap of approximately 10° between each arcuate post. The arcuate posts are disposed between the first and second inner surfaces of the liquid crystal cell.

[0119] 3B shows a ring 207 formed from a number of posts, two of which are labeled 207a and 207b. The posts are cylindrical. The posts are located between the first and second inner surfaces of the liquid crystal cell.

[0120] Figure 3C shows a ring 307 formed from two arcuate posts 307a, 307b. Each arcuate post is an arc, with an arc angle of approximately 175°. There are two small gaps between the arcuate posts.

[0121] The support member may be formed, for example, from a photosensitive material such as a photopolymer. The photosensitive material may be exposed to appropriate radiation using a radiation source and a mask. Such exposure may cause the exposed areas to "harden" (or, in some cases, "soften"). The "softened" or "unhardened" material may then be removed using an appropriate solvent, leaving behind the desired support member. Formation of a support member using a mask is described in WO2019 / 030491.

[0122] A ring may also be formed, for example, by selective placement of a plurality of support members. For example, 50 micron spacer beads may be deposited on a substrate, for example, using an automated deposition system, to provide a ring of such spacer beads. For the avoidance of doubt, there are gaps between the spacer beads.

[0123] FIG. 4 shows a schematic cross-sectional view of a portion of an example liquid crystal cell according to the present invention. The liquid crystal cell 3 has a cell gap thickness G between a first inner surface 4 and a second inner surface 5, and contains liquid crystal 9 therebetween. The liquid crystal cell 3 has a peripheral support structure (not shown) for maintaining the peripheral gap thickness around the liquid crystal cell. The peripheral support structure includes four strips of 50-micron-thick spacer sheet, each strip forming one side of a square, providing a peripheral gap thickness of approximately 50 microns. In this case, the cell gap thickness G is also approximately 50 microns. The liquid crystal cell 3 also has a plurality of support members (not shown) in the form of 50-micron spacer beads. Each support member is arranged to maintain the cell gap thickness G by providing support at a support location within the cell. Substantially all of the support members are arranged such that the plurality of support locations form a first inner ring and a second outer ring concentric with the center of the liquid crystal cell. The first inner ring and second outer ring are substantially similar to those shown in connection with FIG. 1, except that the first inner ring and second outer ring in FIG. 4 are formed from a plurality of spacer beads with spaces therebetween, as opposed to polymer rings.

[0124] The liquid crystal cell 3 includes a first flexible polymer substrate 10 and a second flexible polymer substrate 11. Each substrate 10, 11 includes a conductive layer 12, 13 formed from indium tin oxide. The conductive layers 12, 13 are used to apply an electrical signal to the liquid crystal 9, thereby changing the orientation of the liquid crystal 9, thereby altering the optical properties of the liquid crystal cell. Barrier layers 14, 15 are provided on each conductive layer 12, 13 to reduce surface roughness and prevent leaching of contaminants from the indium tin oxide into the liquid crystal. Layers 16, 17 of alignment polymer are provided on top of the barrier layers 14, 15. Each layer of alignment polymer 16, 17 is brushed to align the alignment polymer. The liquid crystal 9 adjacent to the alignment polymer 16, 17 is aligned in a specific direction, as shown in Figure 4. The liquid crystal director 20 adjacent to the first inner surface 4 is parallel to the plane of FIG. 4, while the liquid crystal director 20' adjacent to the second inner surface 5 is perpendicular to the plane of FIG. 4. Furthermore, the liquid crystal molecules adjacent to the first and second inner surfaces are generally parallel to the first and second inner surfaces (there is a small pretilt of about 3-5°). The orientation of the liquid crystal molecules adjacent to the alignment polymers 16, 17 is effectively fixed, and the viscoelastic properties of the liquid crystal mean that the liquid crystal adopts a twisted configuration as shown in FIG. 4. As is well known to those skilled in the art, application of an appropriate electric field will change the orientation of the liquid crystal molecules, thereby changing the optical properties of the liquid crystal.

[0125] Those skilled in the art will appreciate that the materials and thicknesses of the substrate, conductive layer, barrier layer, and alignment layer are selected to obtain satisfactory optical performance.

[0126] FIG. 5 shows a schematic cross-sectional view of a further example of an embodiment of a liquid crystal cell according to the present invention. A flexible liquid crystal cell 503 has a cell gap thickness G" between a first inner surface 504 and a second inner surface 505, and contains liquid crystal 509 therebetween. The liquid crystal cell 503 has a peripheral support feature 506 for maintaining a peripheral gap thickness PG around the periphery of the liquid crystal cell. The peripheral support feature 506 includes four strips of a 100 micron thick spacer sheet, each strip forming one side of a square, providing a peripheral gap thickness PG of approximately 100 microns. The liquid crystal cell 503 has a first inner annular support member 507 and a second outer annular support member 508. Each support member 507, 508 is arranged to maintain the cell gap thickness G by providing support at support locations within the cell. The support locations form one or more rings concentric with the center of the liquid crystal cell 503. Liquid crystal 509 is disposed between the first inner surface 504 and the second inner surface 505.

[0127] Liquid crystal cell 503 has liquid crystal 509' in the same optical path as liquid crystal 509. The thickness of liquid crystal 509' corresponds to a cell spacing G''' between third inner surface 524 and fourth inner surface 525. Cell spacing G''' is maintained by spacers 527, 528. Spacer 527 is in the form of an inner annulus and spacer 528 is in the form of an outer annulus.

[0128] The first inner surface 504 is supported by the first substrate 510. The fourth inner surface 525 is supported by the second substrate 511. The second inner surface 505 and the third inner surface 524 are supported by the internal substrate 520.

[0129] FIG. 2 illustrates that the present invention can be used with ophthalmic lenses, including so-called meniscus lenses. Those skilled in the art will appreciate that other optical configurations are possible. For example, FIG. 8 shows a schematic cross-sectional view of an ophthalmic lens 601 including a liquid crystal cell. A flexible liquid crystal cell 603 has a cell gap thickness G between a first inner surface 604 and a second inner surface 605, with liquid crystal 609 therebetween. The liquid crystal cell 603 has a peripheral support feature 606 for maintaining a peripheral gap thickness PG around the liquid crystal cell. The peripheral support feature 606 includes a 50-micron-thick ring of spacer sheet, providing a peripheral gap thickness PG of approximately 50 microns. The liquid crystal cell 603 has a first inner annular support member 607 and a second outer annular support member 608. The shape of the first inner surface 604 is defined by a Fresnel structure (a series of annular features providing peaks and valleys). Each support member 607, 608 is positioned to maintain the cell gap thickness G by providing support at support locations within the cell. The cell gap thickness G is not uniform across the liquid crystal cell due to the presence of a Fresnel structure. In this case, the height of support member 607 is less than the height of support member 608. The support locations form one or more rings concentric with the center of liquid crystal cell 603. Liquid crystal 609 is disposed between first inner surface 604 and second inner surface 605. Those skilled in the art will appreciate that other optical configurations, such as a gradient index lens (GRIN lens), can be realized using the present invention.

[0130] While the present invention has been described and illustrated with reference to specific embodiments, it will be understood by those skilled in the art that the present invention is susceptible to many different variations not specifically illustrated herein. By way of example only, certain possible variations are described below.

[0131] While the above examples show that the liquid crystal cell can have two concentric rings of support locations to maintain the cell gap thickness, those skilled in the art will understand that other arrangements are possible, for example, with one (only) ring of support locations or more than two rings of support locations.

[0132] In the above examples, the ring is shown to be substantially annular. Those skilled in the art will appreciate that the ring need not be annular.

[0133] While the above examples show lenses with particular orientations of liquid crystals, those skilled in the art will appreciate that other orientations or arrangements of liquid crystals may be used depending on the optical effect required.

[0134] Although the above examples have been described with reference to contact lenses, those skilled in the art will appreciate that other ophthalmic lenses may also be used.

[0135] Where the foregoing description refers to integers or elements that have known, obvious, or foreseeable equivalents, such equivalents are incorporated herein as if individually set forth. Reference should be made to the claims to determine the true scope of the invention, which should be construed to embrace all such equivalents. The reader will also understand that any integers or features of the invention described as preferred, advantageous, convenient, or the like are optional and do not limit the scope of the independent claims. It should further be understood that such optional integers or features may be beneficial in some embodiments of the invention, but may be undesirable and therefore absent in other embodiments.

Claims

1. 1. An electrically switchable flexible ophthalmic lens for fitting to a user's eye, comprising: a flexible liquid crystal cell for changing at least one optical property of said ophthalmic lens; A plurality of support members; Equipped with the flexible liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface, and has liquid crystal therebetween; the flexible liquid crystal cell has a chord radius w; each support member is positioned to maintain the cell gap thickness by providing support at one or more support locations within the cell; the plurality of support members are arranged so that the support positions form two circumferential rings that are concentric with a center of the liquid crystal cell; a first of the two circumferential rings is located between 0.26 and 0.34w chord measurements from the center of the liquid crystal cell; a second of the two circumferential rings is located between 0.52 and 0.70 wth chord measurements from the center of the liquid crystal cell; the support locations form only two full-circumferential rings; The second ring is positioned within the liquid crystal cell such that a portion of the liquid crystal is located outside the second ring. A lens characterized by:

2. The first ring is located at a chord measurement of 0.30 to 0.34w from the center of the liquid crystal cell.

2. The lens of claim 1.

3. The second ring is located at a chord measurement of 0.60 to 0.68 w from the center of the liquid crystal cell.

3. The lens according to claim 1 or 2.

4. The first ring and the second ring are each formed by two or more support members.

4. The lens according to claim 1, wherein the lens is a reflective surface.

5. The distances between adjacent support members forming each circumferential ring are substantially the same.

5. The lens of claim 4.

6. One or more of the support members are cylindrical, spherical, cylindrical, ellipsoidal, ovoid, elongated, annular, semi-annular, or arcuate.

6. A lens according to claim 1.

7. The cell gap thickness is substantially uniform across the liquid crystal cell.

7. A lens according to claim 1.

8. The cell gap thickness is not uniform across the liquid crystal cell.

7. A lens according to claim 1.

9. The liquid crystal cell has peripheral support spacers for maintaining a peripheral gap thickness around the liquid crystal cell.

9. A lens according to claim 1.

10. All of the plurality of support members are arranged such that the plurality of support positions form two full-circumferential rings, and there is no support position that does not form one of the two full-circumferential rings.

10. A lens according to claim 1.

11. the liquid crystal cell has a cell gap between a third inner surface and a fourth inner surface, and has liquid crystal therebetween; the third inner surface and the fourth inner surface are in addition to the first inner surface and the second inner surface, The liquid crystal between the third inner surface and the fourth inner surface is in the same optical path as the liquid crystal between the first inner surface and the second inner surface.

11. A lens according to any one of claims 1 to 10.

12. The liquid crystal cell has one or more spacers for maintaining the cell gap between the third inner surface and the fourth inner surface.

12. The lens of claim 11.

13. All of the spacers are arranged so that the support positions form one or more rings concentric with the center of the liquid crystal cell.

13. The lens of claim 12.

14. The support locations form only two rings that are concentric about the center of the liquid crystal cell.

14. The lens of claim 13.

15. Fresnel lens structure Equipped with the Fresnel lens structure defines a shape of one of the first inner surface and the second inner surface; the liquid crystal disposed between the first inner surface and the second inner surface is switchable between a first liquid crystal configuration and a second liquid crystal configuration; In one of the first liquid crystal form and the second liquid crystal form, the difference in refractive index between the liquid crystal and the material forming the Fresnel lens structure is smaller than in the other of the first liquid crystal form and the second liquid crystal form.

15. A lens according to any one of claims 1 to 14.

16. Meniscus Lens Equipped with one of the first inner surface and the second inner surface is a convex surface; the other of the first inner surface and the second inner surface is a convex surface, The curvatures of the first and second inner surfaces may be the same or different.

15. A lens according to any one of claims 1 to 14.

17. Gradient Refractive Index (GRIN) Lens 15. The lens according to claim 1, further comprising:

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