Contact lens formulation and contact lens

Abstract

Silicone hydrogel contact lens formulations are described herein. The formulation has a silicone component and a silicone-free component. The silicone component comprises two or three compounds represented by a formula 1, a formula 2 or a formula 3. The silicone-free component includes a methacrylate component and an N-vinyl amide component. The methacrylate component is prepared from hydroxybutyl methacrylate (HOB) and isobornyl methacrylate (IBM). And the N-vinyl amide component is prepared from N-vinyl N-methyl acetamide. When compounds of Formula 1 and compounds of Formula 2 are present in the formulation in specific ratios to each other, specific amounts of HOB and IBM are provided to achieve specific ratio results in desirable silicone hydrogel contact lenses. Silicone hydrogel contact lenses are also described.

Description

TECHNICAL FIELD

[0001] The present invention relates to a novel silicone hydrogel contact lens formulation, and ophthalmic lenses, particularly contact lenses, and more particularly silicone hydrogel contact lenses comprising the reaction product of a polymerizable composition. BACKGROUND

[0002] Silicone hydrogel contact lenses have proven to be an acceptable alternative to hydrogel contact lenses. Contact lens manufacturers are often challenged to introduce novel contact lenses to meet market demands. Thus, there is a continuing need to develop novel silicone hydrogel contact lenses to address this need.

[0003] In developing silicone hydrogel contact lenses, it is difficult to predict whether a novel silicone hydrogel contact lens formulation will result in a clinically acceptable silicone hydrogel contact lens. Achieving a successful fit, acceptable comfort, acceptable handling experience, and acceptable vision improvement are influenced by various changes in lens chemistry, lens design, and manufacturing processes. For example, changing the formulation of a silicone hydrogel contact lens can change oxygen permeability, water content, lens surface wettability, and mechanical properties such as modulus, tensile strength, and elasticity. Thus, it is not predictable what combination of chemicals in a formulation will result in desirable lens properties. SUMMARY

[0004] The present invention addresses this continuing need. The present inventors have discovered that when using certain silicone alkane compounds in specific combinations in a silicone hydrogel contact lens formulation, it is necessary to adjust other monomers in the formulation in ways that were not previously known in order to achieve certain desirable contact lens properties. The disclosure herein describes the present invention in greater detail.

[0005] Applicants have identified that a suitable silicone hydrogel contact lens formulation can be formed using a reaction mixture comprising a silicone component and a non-silicone component. The silicone component comprises, and preferably consists essentially of, two compounds, namely Formula 1:

[0006]

[0007] wherein R1is selected from hydrogen or methyl; R2is selected from hydrogen or C 1-4 hydrocarbyl; m represents an integer from 0 to 10; n represents an integer from 4 to 100; a and b represent integers of 1 or greater; a + b is from 20 to 500; b / (a + b) is from 0.01 to 0.22, and the configuration of the siloxane units comprises a random configuration; and

[0008] Formula 2:

[0009]

[0010] wherein n is an integer from 10 to 25.

[0011] The combination of compounds of Formula 1 and compounds of Formula 2 is critical at a ratio from 50:50 to 77:23. Preferably, the ratio of compounds of Formula 1 to compounds of Formula 2 is from 53:47 to 77:23.

[0012] In certain embodiments, in the compound of Formula 1, R1is selected from hydrogen or methyl; R2is selected from hydrogen or C 1-4 hydrocarbyl; m is 0; n represents an integer from 4 to 15; a represents an integer from 50 to 250, b represents an integer from 5 to 50; and the configuration of the siloxane units comprises a random configuration, wherein the ratio of a:b is from 5:1 to 30:1, preferably 10:1 to 20:1.

[0013] In further embodiments, the silicone component additionally comprises additional silicone compounds of Formula 3:

[0014]

[0015] wherein m represents an integer from 3 to 12, n represents an integer from 1 to 10, R 1 is selected from an alkyl group having from 1 to 4 carbon atoms, R 2 is a hydrogen atom or a methyl group, and R 3 is a hydrogen atom or a methyl group.

[0016] In some embodiments, in the compound of Formula 3, m is 4, and n is 1, R 1 is butyl, R 2 is H, and R 3 is methyl.

[0017] In the presence of a compound of Formula 3, it is used in an amount less than 1% of the total contact lens formulation. In one preferred embodiment of the present formulation, the silicone component consists essentially of Formula 1, Formula 2 and Formula 3.

[0018] The combination of compounds of Formula 1 and Formula 2 advantageously allows the use of lower amounts of silicone component while still producing a contact lens with good oxygen permeability. This also allows for a high water content, which is advantageous for wettability.

[0019] However, when using compounds of Formula 1 and 2 to prepare a contact lens formulation, even at these lower amounts, the tensile strength and Young’s modulus can be high, as seen in Examples 15 to 17 of US8129442.

[0020] The applicants have identified that by focusing on selecting the ratio and / or amounts of specific other monomers, it is possible to prepare a lens having a tensile strength substantially lower than that seen in formulations containing compounds of Formula 1 and Formula 2.

[0021] The silicone-free component of the present contact lens formulation comprises a methacrylate component and an N-vinylamide component.

[0022] The methacrylate component comprises, preferably consists essentially of, and more preferably consists of, hydroxybutyl methacrylate (HOB) and isobornyl methacrylate (IBM). It is critical that HOB and IBM are present in the formulation in a ratio of 70:30 to 90:10. In a particularly preferred embodiment, the weight ratio of HOB to IBM is from 85:15 to 90:10, more preferably the ratio is about 88:12. In another embodiment, the weight ratio of HOB to IBM is preferably from 75:25 to 80:20, more preferably about 77:23.

[0023] The N-vinylamide component comprises N-vinyl N-methyl acetamide (VMA). In some embodiments, the N-vinylamide component also comprises N-vinyl pyrrolidone (NVP). In the case where the N-vinylamide component comprises NVP and VMA, the ratio of NVP to VMA is preferably from 70:30 to 30:70. In preferred embodiments, the N-vinylamide component consists essentially of and more preferably consists of NVP and VMA.

[0024] It has been surprisingly found that the particular ratio of HOB to IBM, together with the inclusion of VMA and optionally NVP, results in a lens having desirable properties, particularly low tensile strength and low Young's modulus, compared to existing lenses formed using a combination of silicone alkane compounds of Formula 1 and Formula 2.

[0025] In a first particularly preferred embodiment, the contact lens formulation comprises a silicone component consisting essentially of Formula 1 and Formula 2, wherein the ratio of Formula 1 to Formula 2 is from 53:47 to 57:43. The N-vinylamide component consists essentially of NVP and VMA, wherein the ratio of NVP:VMA is from 68:32 to 72:28. The methacrylate component consists essentially of HOB and IBM, wherein the ratio of HOB to IBM is from 85:15 to 90:10. Preferably, the silicone component comprises from 45 to 55 weight percent of the formulation. Also preferably, the methacrylate component comprises from 10 to 20 weight percent of the formulation. Yet further preferably, the N-vinylamide component comprises from 30 to 40 weight percent of the formulation.

[0026] In a second particularly preferred embodiment, the contact lens formulation comprises a silicone component consisting essentially of Formula 1 and Formula 2, wherein the ratio of Formula 1 to Formula 2 is from 73:27 to 77:23. The N-vinylamide component consists essentially of NVP and VMA, wherein the ratio of NVP:VMA is from 32:68 to 28:72. The methacrylate component consists essentially of HOB and IBM, wherein the ratio of HOB to IBM is from 85:15 to 90:10. Preferably, the silicone component comprises from 45 to 55 weight percent of the formulation. Also preferably, the methacrylate component comprises from 10 to 20 weight percent of the formulation. Yet further preferably, the N-vinylamide component comprises from 30 to 40 weight percent of the formulation.

[0027] In a third particularly preferred embodiment, the contact lens formulation comprises a silicone component consisting essentially of Formula 1, Formula 2, and Formula 3, wherein Formula 3 is present in an amount of less than 0.6 weight percent of the formulation, wherein the ratio of Formula 1 to Formula 2 is from 60:40 to 65:35. The N-vinylamide component consists essentially of VMA. The methacrylate component consists essentially of HOB and IBM, wherein the ratio of HOB to IBM is from 75:25 to 80:20. Preferably, the silicone component comprises from 45 to 55 weight percent of the formulation. Also preferably, the methacrylate component comprises from 5 to 15 weight percent of the formulation. Yet further preferably, the N-vinylamide component comprises from 30 to 40 weight percent of the formulation.

[0028] Preferably, the formulation further comprises at least one of the following: a photoinitiator, a thermal initiator, a crosslinking monomer, a UV blocker, and a colorant.

[0029] In another embodiment of the present application, a silicone hydrogel contact lens is disclosed comprising the polymerization reaction product of any of the foregoing embodiments of the formulation.

[0030] The silicone hydrogel contact lens can have a tensile strength of from 0.4 MPa to 1.0 MPa. The silicone hydrogel contact lens typically has a tensile strength of less than or equal to 1.0 MPa, and preferably less than or equal to 0.9 MPa. The silicone hydrogel contact lens typically has a tensile strength of at least 0.4 MPa, and more preferably at least 0.5 MPa. In at least some preferred embodiments, the silicone hydrogel contact lens has a tensile strength of from 0.5 MPa to 0.9 MPa.

[0031] The silicone hydrogel contact lens can have a set drop contact angle of less than 30°, more preferably less than 25°.

[0032] The silicone hydrogel contact lens can have an equilibrium water content of from 45 to 55 weight percent.

[0033] The silicone hydrogel contact lenses can have an oxygen permeability greater than 100 barrer, preferably greater than 110 barrer, more preferably greater than 120 barrer, and especially from 110 to 140 barrer.

[0034] The silicone hydrogel contact lenses can have a Young's modulus of less than or equal to 1.1 MPa, preferably less than or equal to 1.0 MPa. The Young's modulus is preferably at least 0.3 Mpa, more preferably at least 0.5 Mpa. A preferred range is from 0.5 Mpa to 0.95 Mpa.

[0035] The silicone hydrogel contact lenses can have a chord diameter from 13.5 to 15.5 mm and a base curve from 7.5 to 9.5 mm. Other suitable chord diameters and base curves are known to the skilled artisan. DETAILED DESCRIPTION

[0036] Described herein are silicone hydrogel contact lenses that have good dimensional stability, are ophthalmically acceptable, and can be manufactured without the use of volatile organic solvents or diluents in the formulation. The silicone hydrogel contact lenses include a polymeric lens body that is the reaction product of a polymerizable composition or a silicone hydrogel contact lens formulation that includes a silicone component and a non-silicone component. The silicone component includes, or consists essentially of, two compounds, namely Formula 1 and Formula 2. The Formula 1 compound and the Formula 2 compound are critical at a ratio from 50:50 to 77:23.

[0037] Reference herein to "at least one" of a component means both a) a single component, and b) a combination of two or more components of the same type.

[0038] Throughout this disclosure, reference to the "total amount" of a particular component (i.e., a combination of two or more components of the same type) in a polymerizable composition means the sum of the amounts of all components of the same type.

[0039] The following definitions of the terms set forth below are provided for convenience and are not intended to limit the meaning of the terms as set forth in the written description and the claims.

[0040] "Monomer" means any molecule that is capable of reacting with the same or different other molecules to form a polymer or copolymer. Thus, the term includes polymerizable prepolymers and macromonomers, unless otherwise specified, there is no size limitation on the monomers.

[0041] "Siloxane monomer" contains at least one Si—O group, and is typically "monofunctional" or "polyfunctional," meaning it has one polymerizable group or two or more polymerizable groups, respectively. "Non-siloxane monomer" is a monomer that does not contain any Si—O groups.

[0042] "Silicone component" is the component or portion of a silicone hydrogel contact lens formulation that consists of all siloxane monomers.

[0043] "Non-silicone component" is the component or portion of a silicone hydrogel contact lens formulation that consists of all non-siloxane monomers.

[0044] "N-vinylamide component" is the component or portion of the non-silicone component of a silicone hydrogel contact lens formulation that consists of at least one non-siloxane monomer having a vinyl group directly bonded to a nitrogen atom.

[0045] "Methacrylate component" is the component or portion of the non-silicone component of a silicone hydrogel contact lens formulation that consists of at least one non-siloxane monomer having a single polymerizable methacrylate group.

[0046] "(Meth)acrylate-containing monomer" is any non-siloxane monomer having a single polymerizable (meth)acrylate group (e.g., methyl methacrylate, etc.). Siloxane monomers having at least one polymerizable (meth)acrylate group are referred to herein as "siloxane monomers containing (meth)acrylate." "(Meth)acrylate" encompasses both methacrylate and acrylate groups. Where only methacrylate or acrylate is intended, it will be explicitly mentioned.

[0047] "Consisting of means that the formulation or component contains only the listed compounds or monomers.

[0048] "Consisting essentially of means that the formulation or component contains not only the listed compounds or monomers, but can also contain other monomers or compounds falling within the definition of the formulation or component, such as dimer or polymer impurities. These additional monomers or compounds can be present in amounts that have no effect on the final lens formulation. Additional monomers or reactive entities can be present in amounts less than 5%, 2%, 1%, 0.5%, or 0.1% based on the total amount of the particular formulation or component.

[0049] "Polymerizable composition" is a composition comprising polymerizable ingredients, wherein the composition has not yet been subjected to conditions that result in polymerization of the polymerizable ingredients. Thus, the silicone hydrogel contact lens formulations of the present application are considered to be polymerizable compositions.

[0050] In the case of polyorganosiloxane prepolymers and other polydisperse monomers, the term "molecular weight" as used herein refers to the absolute number average molecular weight M n(Daltons / Da) or g / mol). Number average molecular weight is typically determined using GPC using polystyrene standards. Additionally, number average molecular weight can be determined by identifying the number average molecular weight on a technical data sheet or specification sheet provided by a chemical supplier to a contact lens manufacturer.

[0051] In the present disclosure, where a value is given for a repeating group in a structural formula (such as Formula 1, Formula 2, or Formula 3), it is an average value. The skilled artisan will appreciate that this type of complex molecule contains a mixture of components.

[0052] As used herein, the term "total formulation" or "total contact lens formulation" refers to all of the formulation ingredients, excluding diluents and / or solvents that are not incorporated into the final polymeric contact lens material. It can be appreciated that when a weight % of an ingredient of the total formulation is provided, it refers to the weight % of that ingredient based on the total weight of the formulation.

[0053] Throughout this disclosure, reference to "an" or "a" or similar referents is intended to introduce "one or more" of the referenced features, unless the context clearly dictates otherwise, or if the context indicates otherwise, it can be combined with any combination of previously described or subsequently described examples (i.e., features).

[0054] Throughout this disclosure, when a range of lower limit values and a range of upper limit values are provided, all combinations of the provided ranges are contemplated, as if each combination were explicitly listed. Likewise, throughout this disclosure, when a series of values is presented with a modifier preceding the first value, the modifier is intended to be implicitly preceded by each value in the series, unless the context otherwise dictates. For example, with the values listed above, the modifier "from about" is intended to be implicitly preceded by the ratio 50:50, and the modifier "to about" is intended to be implicitly preceded by the ratio 80:20.

[0055] As used herein, unless otherwise specified, a ratio refers to a weight ratio. As used herein, a weight ratio refers to a ratio between the weight of a first component and the weight of a second component in a formulation.

[0056] Disclosed herein are silicone hydrogel contact lens formulations comprising a silicone component; and a non-silicone component.

[0057] The silicone component comprises, or consists essentially of, or in some embodiments, consists of, a difunctional (meth)acrylate-containing siloxane monomer and a monofunctional methacrylate-containing siloxane monomer.

[0058] The difunctional (meth)acrylate-containing siloxane monomer is represented by Formula 1:

[0059]

[0060] wherein R1is selected from hydrogen or methyl; R2is selected from hydrogen or C 1-4 hydrocarbyl; m represents an integer from 0 to 10; n represents an integer from 4 to 100; a and b represent integers of 1 or greater; a+b is from 20 to 500; b / (a+b) is from 0.01 to 0.22, and the configuration of the siloxane units comprises a random configuration.

[0061] The bifunctional (meth)acrylate-containing siloxane monomer of Formula 1 can have an average molecular weight Mn of at least 8,000, 10,000, 12,000, or 15,000 Da. The bifunctional (meth)acrylate-containing siloxane monomer of Formula 1 can have an average molecular weight Mn of less than 25,000, 20,000, 12,000, 11,000, 10,000, or 9,000 Da. Preferably, the bifunctional (meth)acrylate-containing siloxane monomer has an average molecular weight Mn of from 8,000 to 20,000 Da. In a preferred embodiment, the bifunctional (meth)acrylate-containing siloxane monomer of Formula 1 has an average molecular weight Mn of from 8,000 to 11,000 Da. In another preferred embodiment, the bifunctional (meth)acrylate-containing siloxane monomer of Formula 1 has an average molecular weight Mn of from 15,000 to 20,000 Da.

[0062] In certain embodiments, in the compound of Formula 1, R1is selected from hydrogen or methyl; R2is selected from hydrogen or C 1-4 hydrocarbyl; m is 0; n represents an integer from 4 to 15; a represents an integer from 50 to 250, b represents an integer from 5 to 50; and the configuration of the siloxane units comprises a random configuration, wherein the ratio of a:b is from 5:1 to 30:1, preferably 10:1 to 20:1.

[0063] Preferably, R1is methyl. Preferably, R2is H or methyl, and more preferably methyl. Further preferably, m is 0. Preferably, n is from 6 to 9.

[0064] In a preferred embodiment, a is from 60 to 100, more preferably from 70 to 80, and b is from 4 to 8, more preferably from 5 to 8. Also preferably, R1is methyl, R2is methyl, m is 0, and n is from 7 to 8.

[0065] Particularly preferred bifunctional (meth)acrylate-containing siloxane monomers have a CAS Registry Number of 1216820-69-7.

[0066] In another preferred embodiment, a is from 140 to 220, more preferably from 150 to 200, and b is from 8 to 15, more preferably from 9 to 13. Also preferably, R1is methyl, R2is methyl, m is 0, and n is from 7 to 8.

[0067] Methods of preparing compounds of Formula 1 are described in U.S. Patent No. 8,129,442, incorporated herein by reference.

[0068] Silicone monomers containing monofunctional methacrylate ester are represented by Formula 2:

[0069]

[0070] wherein n is an integer from 10 to 25, preferably from 13 to 18.

[0071] The silicone monomers containing monofunctional methacrylate ester of Formula 2 have an average molecular weight Mn of less than 2,000, preferably less than 1,800 Da, and greater than 800, preferably greater than 1,000 Da. In another particular example, the silicone monomers containing monofunctional methacrylate ester can have an average molecular weight Mn from 1,000 to 1,800 Da.

[0072] Preferably, the silicone monomers containing monofunctional methacrylate ester have a CAS Registry Number of 697234-76-7.

[0073] Silicone monomers of Formula 2 are described in U.S. Patent No. 6,310,169, incorporated herein by reference.

[0074] The compounds of Formula 1 and the compounds of Formula 2 are in a weight ratio from 50:50 to 77:23. In one preferred embodiment, the weight ratio of the compounds of Formula 1 to the compounds of Formula 2 is from 53:47 to 77:23. In some particular embodiments, the weight ratio is from 52:48 to 58:42. In some particular embodiments, the weight ratio is from 60:40 to 65:35. In some particular embodiments, the weight ratio is from 70:30 to 77:23. In some particular embodiments, the weight ratio is about 55:45, about 63:37, or about 75:25.

[0075] In additional embodiments, the silicone component includes an additional silicone compound which is a silicone monomer containing monofunctional (meth)acrylate ester of Formula 3:

[0076]

[0077] wherein m of Formula 3 represents an integer from 3 to 12, n represents an integer from 1 to 10, R 1 selected from alkyl groups having from 1 to 4 carbon atoms, and R2 and R 3 each is independently selected from a hydrogen atom or a methyl group.

[0078] In some embodiments, in the compound of Formula 3, m is 4, and n is 1. Also preferably, R 1 is butyl, R 2 is H, and R 3 is methyl.

[0079] In the presence of a compound of Formula 3, it is used in an amount less than 1 wt%, preferably less than 0.8 wt%, more preferably less than 0.6 wt% of the total contact lens formulation. In one preferred embodiment of the present formulation, the silicone component consists essentially of, preferably consists of, Formula 1, Formula 2, and Formula 3.

[0080] In some embodiments, the silicone component is greater than 48%, 48.5%, or 49% by weight. In some embodiments, the silicone component is less than 53%, 52.5%, 52%, 51.5%, 51%, or 50.5% by weight. In some embodiments, any of the lower limits of the silicone component by weight are combined with any of the upper limits of the silicone component by weight. For example, the silicone component can be present in the formulation from 48% (wt / wt) to 53% (wt / wt), preferably 48% to 51%.

[0081] In another preferred embodiment, preferably the amount of the compound of Formula 2 is greater than 12 wt% of the total composition. Also preferably, the amount of the compound of Formula 2 is less than 25 wt%. For example, the compound of Formula 2 can be present in the formulation from 12 to 25 % (wt / wt).

[0082] In another preferred embodiment, preferably the amount of the compound of Formula 1 is less than 38 wt%. Also preferably, the amount of the compound of Formula 1 is greater than 26 wt%. For example, the compound of Formula 1 can be present in the formulation from 26 to 38 % (wt / wt).

[0083] Particularly preferably, the amount of the compound of Formula 2 is greater than 12 wt% and the amount of the compound of Formula 1 is less than 38 wt%.

[0084] Furthermore, it can be appreciated that the silicone component of the present formulation does not contain a hydroxyl functional group-containing siloxane compound, does not contain TRIS, or does not contain both.

[0085] The silicone-free component comprises an N-vinyl amide component (c); and a methacrylate component (d).

[0086] The N-vinylamide component comprises N-vinyl N-methyl acetamide (VMA). The N-vinylamide component optionally further comprises N-vinyl pyrrolidone (NVP). Also preferably, the N-vinylamide component consists essentially of, and preferably consists of, NVP and VMA.

[0087] In a preferred embodiment, where the N-vinylamide component comprises both NVP and VMA, the ratio of NVP to VMA is from 70:30 to 30:70. In some embodiments, the ratio is about 70:30. In some embodiments, the ratio is about 30:70. In another particular example, the polymerizable composition has a weight ratio of the total amount of N-vinylamide component to the total amount of (meth)acrylate-containing siloxane monomers (i.e., siloxane monomers containing monofunctional and difunctional (meth)acrylate esters) is from about 40:60 to 45:55. Also preferably, the ratio is from 41:59 to 42:58.

[0088] In some embodiments, the N-vinylamide component is greater than 34% or 34.5% by weight. In some embodiments, the N-vinylamide component is less than 40%, 39%, 37%, 36%, or 35.5% by weight. In some embodiments, any one of the lower limits of the N-vinylamide component by weight is combined with any one of the upper limits of the N-vinylamide component by weight. In some embodiments, the N-vinylamide component is between 34.5% and 35.5% by weight.

[0089] In a preferred embodiment, the N-vinylamide component consists essentially of, and preferably consists of, VMA. In another particular example, the polymerizable composition has a weight ratio of the total amount of N-vinylamide component to the total amount of (meth)acrylate-containing siloxane monomers (i.e., siloxane monomers containing monofunctional and difunctional (meth)acrylate esters) is from about 40:60 to 45:55. Also preferably, the ratio is from 44:56 to 45:55.

[0090] Where the N-vinylamide component consists essentially of or consists of VMA, the N-vinylamide component is greater than 35% or 38% by weight. The N-vinylamide component is less than 40% or 39% by weight. In some embodiments, any one of the lower limits of the N-vinylamide component by weight is combined with any one of the upper limits of the N-vinylamide component by weight. In some embodiments, the N-vinylamide component is between 38% and 39% by weight.

[0091] In another specific example, the total amount of the compound of Formula 2 and the N-vinyl amide component is at least 47 weight percent, preferably at least 50 weight percent. The total amount of the compound of Formula 2 and the N-vinyl amide component is less than 70 weight percent, preferably less than 60 weight percent.

[0092] The methacrylate component includes hydroxybutyl methacrylate (HOB) and isobornyl methacrylate (IBM). It is critical that the HOB and IBM be present in the formulation in a ratio from 70:30 to 90:10.

[0093] The methacrylate component (d) includes, and in some embodiments consists essentially of, and in some embodiments consists of, hydroxybutyl methacrylate (HOB) and isobornyl methacrylate (IBM), wherein the hydroxybutyl methacrylate and isobornyl methacrylate are present in the formulation in a weight ratio from 70:30 to 90:10. In some embodiments, the ratio of HOB to IBM is greater than 75:25, 80:20, 85:15, or 87:13. In some embodiments, the ratio of HOB to IBM is less than 90:10, 89.5:10.5, 89:11, or 88.5:11.5. In some embodiments, any one of the lower limits of the ratio of HOB to IBM is combined with any one of the upper limits of the ratio of HOB to IBM. In some embodiments, the ratio of HOB to IBM is between 85:15 and 90:10 or is about 88:12.

[0094] In alternative embodiments, the weight ratio of HOB to IBM is preferably from 75:25 to 80:20, more preferably about 77:23.

[0095] It is also preferred that the methacrylate component comprises from 5 to 20 weight percent of the formulation.

[0096] Other non-silicone-containing methacrylate monomers are known in the art and can be present in the contact lens formulation. Exemplary non-silicone-containing methacrylate monomers include methyl methacrylate (MMA), t-butyl methacrylate (tBMA), 2-hydroxyethyl methacrylate (HEMA), ethylene glycol methyl ether methacrylate (EGMA), and combinations thereof. Preferably, the additional non-silicone-containing methacrylate monomer is methyl methacrylate (MMA).

[0097] Preferably, these additional methacrylate-containing monomers are present in the contact lens formulation in a total amount of less than 5 weight percent, more preferably less than 3 weight percent, still more preferably less than 1 weight percent, and even more preferably, in the case where the methacrylate component consists essentially of HOB and IBM, in the minimum amounts as defined above. It is particularly preferred that no other methacrylate-containing monomers are present.

[0098] In a particular example, the polymerizable composition can have a weight ratio of the compound of Formula 2 to the total amount of non-siloxane monomers containing methyl methacrylate ester greater than 0.9: 1, preferably greater than 1: 1.

[0099] In another particular example, the total amount of monofunctional group containing methyl methacrylate ester non-silicone monomers and siloxane monomers is collectively greater than 26 wt%, and preferably greater than 30 wt%.

[0100] Typically, the formulation also includes one or more additional components that are common in contact lens formulations. Suitable additional components include photoinitiators, thermal initiators, crosslinking agents, UV blockers, and colorants.

[0101] The polymerizable composition can additionally include at least one non-siloxane crosslinking agent. As used herein, a "crosslinking agent" is any compound having a molecular weight of less than about 2,000 Da and two or more ethylenically unsaturated groups. Thus, a crosslinking agent can react with functional groups on two or more polymer chains in order to bridge one polymer to another. TAIC is particularly preferred as a crosslinking agent in the formulations of the present invention.

[0102] The crosslinking agent is preferably used in an amount of 0.03 to 0.2 wt% of the contact lens formulation.

[0103] The composition can additionally include one or more colorants. Preferred colorants are reactive colorants and in particular colorants identified as "reactive blue" dyes.

[0104] The composition can additionally include one or more UV blockers.

[0105] Contact lenses can be made from the polymerizable compositions described herein using curing and other processing methods known in the art, such as cast molding, rotational molding, injection molding, forming a polymeric rod that is subsequently turned, etc. In a particular example, the polymerizable composition is cast molded between molds formed from a thermoplastic polymer. The thermoplastic polymer is typically a non-polar material, such as polypropylene, although polar mold materials (such as ethylene vinyl alcohol) are also used in the art. Briefly, a first mold member defining the front face of the contact lens (referred to as the "negative mold member") is filled with an amount of the polymerizable composition sufficient to form a single polymeric lens body. A second mold member defining the back face of the contact lens (i.e., the eye contacting face) (referred to as the "positive mold member") is coupled with the negative mold member to form a mold assembly having a lens-shaped cavity therebetween, with the amount of the polymerizable composition therebetween.

[0106] The polymerizable composition within the contact lens mold assembly is polymerized using any suitable curing method. Typically, the polymerizable composition is exposed to heat or ultraviolet light (UV) in a polymerizing amount. In the case of UV curing (also known as photopolymerization), the polymerizable composition typically includes a photoinitiator such as benzoin methyl ether, 1 -hydroxycyclohexyl phenyl ketone, Darocur or Irgacur (available from Ciba Specialty Chemicals). Photopolymerization methods for contact lenses are described in U.S. Patent No. 5,760,100, which is incorporated herein by reference. In the case of heat-curing (also known as thermal curing), the polymerizable composition typically includes a thermal initiator. Exemplary thermal initiators include 2,2'-azobis(2,4-dimethylpentanenitrile) (VAZO-52), 2,2'-azobis(2-methylpropanenitrile) (VAZO-64), and 1, 1 '-azobis(cyanocyclohexane) (VAZO-88). The contact lens mold assembly containing the contact lens formulation is cured by exposing the contact lens mold assembly to heat or UV light for a period of time ranging from about 1 hour to about 5 hours. Additional thermal polymerization methods for contact lenses are described in U.S. Publication No. 2007 / 0296914 and U.S. Patent No. 7,854,866, which are incorporated herein by reference.

[0107] At the completion of curing, the polymerized material between the mold members of the mold assembly has the shape of a contact lens, and is referred to herein as a "polymeric lens body." The male and female mold members are demolded, i.e., separated, and the polymeric lens body is removed from the mold members to which it is attached, i.e., delensed. These processes are each referred to as demolding and delensing, and various methods for each are known to those of ordinary skill in the art. In some methods, the demolding and delensing processes can comprise a single process step, such as when a liquid separation mold is used, which also removes the polymeric lens body from the mold. In other methods, such as when a dry demolding process is used, the polymeric lens body typically remains on one of the mold members and is delensed in a subsequent process step. Delensing can also be a wet or dry process. In one example, delensing is performed by a "floating" method, in which the mold member to which the polymeric lens body is attached is immersed in water. The water can optionally be heated (e.g., up to about 100°C). Typically, the polymeric lens body floats off the mold member within about 10 minutes. Dry delensing can be performed manually, for example, using tweezers, to remove the polymeric lens body from the mold member, or it can be removed using an automated mechanical process, such as described in U.S. Patent No. 7,811,483, which is incorporated herein by reference. Additional demolding and delensing methods for silicone hydrogel contact lenses are described in U.S. Publication No. 2007 / 0035049, which is incorporated herein by reference.

[0108] After de-mirroring, the polymeric lens body is washed to remove unreacted or partially reacted ingredients from the polymeric lens body and to hydrate the polymeric lens body. For example, the contact lens can be exposed to an organic solvent, such as ethanol, isopropanol, industrial methylated spirits, and the like, or water, or mixtures thereof. Exemplary washing methods are described in U.S. Patent Publication No. 2007 / 0296914, which is incorporated herein by reference, and in Example 1 below.

[0109] After washing, the hydrated polymeric lens body is typically placed in a blister package, glass vial, or other suitable container, all referred to herein as "package." A packaging solution is also added to the container, which is typically a buffered saline solution, such as a phosphate or borate buffered saline. The packaging solution can optionally contain additional ingredients, such as comfort agents, hydrophilic polymers, surfactants, or other additives to prevent lens sticking to the container, etc. The package is sealed, and the sealed polymeric lens body is sterilized by autoclaving. The final product is a sterile, packaged ophthalmically acceptable contact lens.

[0110] In any of the above examples, the contact lens can be characterized by one or more than one of the following properties: contact angle, oxygen permeability, tensile strength, Young's modulus, and equilibrium water content, as described in detail below.

[0111] In any of the examples described below, the contact angle of the contact lens can be less than about 30° or 25°, wherein the contact angle is the static advancing contact angle as determined using the sessile drop method. To determine the contact angle of a contact lens surface, the contact lens to be tested is soaked in phosphate buffered solution (PBS) for at least 12 hours. Using rubber tipped forceps, the lens is removed from the PBS and shaken to remove excess water. A 4 mm diameter section of each lens is cut using a lens cutter. The surface of the contact lens section to be tested is blotted dry by placing it face down on a microscope lens wipe and gently dragging the lens section through the wipe using rubber tipped forceps until no liquid is observed being absorbed into the wipe. The lens section is placed on a microscope slide, ensuring it is lying flat with the blotted dry surface facing up. The measurement is taken in a timely manner to ensure the lens section does not dry out (as evidenced by distortion of the lens section). In a Krüss DSA-100, the drop shape analysis program is opened and the "sessile drop (VCA eq)" method is selected with the following settings: camera tilt = +2; 100 μΐ syringe with straight needle; dispensing solution = purified water; dispensing volume = 0.75 μΐ; dispensing speed = 7.5 μΐ / min; and dispensing mode = volume. The microscope slide is placed on the sample stage so that the longer side of the lens section is perpendicular to the camera. The syringe is moved to fit the viewing screen and the image is adjusted until a maximum is reached in the center window. Water is dispensed onto the lens. Between 10 and 15 seconds after the water is dispensed, an image of the drop is captured. The calculation method is selected according to the contact angle as follows: < 30° = circle fit method, 30° to 130° = tangent method -1; > 130° = tangent method -2. The average contact angle measurement of 5 lens sections is taken as the contact angle for the particular surface of the contact lens (i.e., the back or front).

[0112] For oxygen permeability, the Dk values provided in the examples below were determined using a Rehder 201T oxygen permeability / polarographic cell following the polarographic method described in ISO 18369-4:2017 section 4.4.3.

[0113] In any of the examples described below, the contact lens can have a Young's modulus (i.e., tensile modulus) of at least 0.3 MPa or from 0.5 MPa to 0.95 MPa, 1.0 MPa, or 1.1 MPa. In preferred embodiments, the contact lens has a Young's modulus from 0.3 MPa to 1.1 MPa, and preferably from 0.5 to 0.95 MPa.

[0114] The contact lenses have a tensile strength of less than or equal to 1.0 MPa, preferably less than or equal to 0.9 MPa. The contact lenses typically have a tensile strength of at least 0.4 MPa, more preferably at least 0.5 MPa. Preferred embodiments of the present contact lenses have a tensile strength from 0.5 MPa to 0.9 MPa.

[0115] Modulus, elongation, and tensile strength values reported herein were determined using an Instron model 3342, 3343, or 5944 mechanical testing system (Instron Corporation, Norwood, Mass., USA) and Bluehill Materials testing software, using a custom rectangular contact lens cutting die with a 4 mm gap to prepare rectangular sample strips. Modulus was determined in a room with a relative humidity of at least 70%. Lenses were soaked in phosphate buffered solution (PBS) for at least 10 minutes prior to testing. A central strip of the lens was cut using the cutting die with the concave surface held facing upwards. The thickness of the strip was determined using a calibrated gauge (Rehder electronic thickness gauge, Rehder Development Company, Castro Valley, Calif., USA). Using tweezers, the strip was loaded into the grips of the calibrated Instron apparatus, with the strip seated on at least 75% of the grip surface of each grip. The test method was run designed to determine the average and standard deviation of maximum load (N), tensile strength (MPa), strain at maximum load (% elongation), and tensile modulus (MPa), and the results were recorded.

[0116] In any of the above examples, the contact lenses can have an equilibrium water content (EWC) of at least about 30, 40, or 45 weight % and up to about 50, 55, 60, or 70 weight %. For example, the contact lenses can have an EWC of 40 to 60 weight %. To measure the EWC, excess surface water was blotted from the lens and the lens was weighed to obtain the hydrated weight. The lens was dried in an oven at 105 °C, and weighed. The weight difference was determined by subtracting the weight of the dry lens from the weight of the hydrated lens. The weight % EWC of the lens = (weight difference / hydrated weight) x 100. In particular examples, the contact angle is < 30° and the equilibrium water content is most preferably at least 45 weight % and up to 55 weight %.

[0117] As will be apparent from the disclosure of the application as a whole, including the structure of the technical solutions and the specific examples, the exemplary components of the polymerizable compositions disclosed herein are generally combined in embodiments of the application. For example, one of skill in the art will know that the polymerizable compositions of the application advantageously comprise the exemplary monofunctional (meth)acrylate-containing siloxane monomers disclosed herein in combination with the exemplary difunctional (meth)acrylate-containing siloxane monomers disclosed herein and in combination with the exemplary N-vinylamide components disclosed herein and in combination with the exemplary (meth)acrylate components disclosed herein.

[0118] As demonstrated by the specific examples, it has been found that the combination of the preferred monofunctional methacrylate-containing siloxane monomers, difunctional (meth)acrylate-containing siloxane monomers, N-vinylamide components, and methacrylate-containing monomers of the application provide contact lenses of the application having advantageous properties such as reduced tensile strength.

[0119] Examples

[0120] The following examples illustrate certain aspects and advantages of the present application, which should be understood not to be limited thereby. The reactants used in the examples are detailed in Table 1, the specific amounts of each component used are set forth in Table 2 in weight % of the total formulation, the ratios of the components and the combination totals are presented in Table 3, and the properties are presented in Table 4.

[0121] The silicone hydrogel lenses of Examples 1-3 and Comparative Example were produced according to the following method.

[0122] The compounds or monomers were all mixed and stirred to form a polymerizable composition or a silicone hydrogel contact lens formulation.

[0123] The formulation was placed into a mold for a contact lens.

[0124] The lens was cured using ultraviolet light for about 1 hour (Examples 1 and 2 and Comparative Example) or using heat for about 5 hours (Example 3). The skilled artisan will know suitable methods for curing the contact lens formulation.

[0125] The cured polymer was removed from the contact lens mold and washed to remove unreacted material by contacting it with an organic solvent, water, or a combination thereof, and then the washed contact lens was placed into packaging and sterilized in an autoclave to yield a sterilized packaged contact lens. The contact lenses of all examples and comparative examples were clear and flexible, and also had good water wettability.

[0126] Table 1

[0127]

[0128] Table 2

[0129]

[0130] Table 3

[0131]

[0132] Table 4

[0133]

[0134] In Table 3, "(Formula 2)" refers to the general structure of the Formula 2 compounds in this description, and Si-2 is a specific example within Formula 2.

[0135] Surprisingly, a particular selection of non-silicone monomers and the ratio of HOB to IBM can result in such a dramatic decrease in the tensile strength of the resulting lens. The inventive lenses retain other advantageous features seen in prior art lenses formed using the same combination of siloxane monomers, such as high Dk and good sessile drop contact angle.

[0136] While the disclosure herein refers to certain examples, it will be understood that these examples are presented by way of example and not by way of limitation. While exemplary examples are discussed, it is to be understood that the above description is intended to cover all modifications, alternatives and equivalents as can befall within the spirit and scope of the present application as defined by the appended disclosure.

[0137] A number of publications and patents have been cited in the foregoing disclosure. Each of the publications and patents cited herein is incorporated herein by reference in its entirety.

Claims

1. A silicone hydrogel contact lens formulation comprising: (i) Silicone components; and (ii) Silicone-free, wherein The silicone component comprises: (a) Compound of Formula 1 Where R1 is selected from hydrogen or methyl; R2 is selected from hydrogen or C 1-4 Hydrocarbon group; m represents an integer from 0 to 10; n represents an integer from 4 to 100; a and b represent integers of 1 or greater; a+b is from 20 to 500; b / (a+b) is from 0.01 to 0.22, and the configuration of the siloxane unit includes random configuration; and (b) Compound 2 Wherein n is 10 to 25, and the compound of formula 1 and the compound of formula 2 are present in the formulation in a ratio from 50:50 to 77:23; and The silicone-free component comprises: (c) N-vinylamide component; and (d) Methacrylate component, wherein The N-vinylamide component (c) comprises N-vinyl-N-methylacetamide (VMA); and The methacrylate component (d) comprises hydroxybutyl methacrylate (HOB) and isobornyl methacrylate (IBM), wherein the hydroxybutyl methacrylate and isobornyl methacrylate are present in the formulation at a ratio of 70:30 to 90:

10.

2. The formulation according to claim 1, wherein the ratio of HOB to IBM is from 85:15 to 90:

10.

3. The formulation according to claim 1 or 2, further comprising at least one of the following: Photoinitiators, thermal initiators, crosslinking monomers, UV blockers, and colorants.

4. The formulation according to any of the preceding claims, wherein the N-vinylamide component (c) comprises VMA and N-vinylpyrrolidone (NVP).

5. The formulation according to claim 4, wherein the ratio of NVP to VMA is about 70:30 or about 30:

70.

6. The formulation according to any of the preceding claims, wherein the ratio of the compound of formula 1 to the compound of formula 2 is from 55:45 to 75:

25.

7. The formulation according to any of the preceding claims, wherein the ratio of HOB to IBM is approximately 88:

12.

8. The formulation according to claim 1, wherein: The ratio of Equation 1 to Equation 2 is from 53:47 to 57:43; The N-vinylamide component is essentially composed of NVP and VMA, wherein the NVP:VMA ratio is from 68:32 to 72:28; and The methacrylate component is essentially composed of HOB and IBM, wherein the ratio of HOB to IBM is from 85:15 to 90:

10.

9. The formulation according to claim 1, wherein: The silicone component is essentially composed of Formula 1, Formula 2 and Formula 3: In equation 3, m represents an integer from 3 to 12, n represents an integer from 1 to 10, and R... 1 Selected from alkyl groups having 1 to 4 carbon atoms, and R 2 and R 3 Each is independently selected from hydrogen atoms or methyl groups, wherein formula 3 is present in an amount of less than 0.6% by weight of the formulation; The ratio of Equation 1 to Equation 2 is from 60:40 to 65:35; The N-vinylamide component is essentially composed of VMA; and The methacrylate component is essentially composed of HOB and IBM, wherein the ratio of HOB to IBM is from 75:25 to 80:

20.

10. A silicone hydrogel contact lens comprising a polymerization product of a formulation according to any of the preceding claims.

11. The silicone hydrogel contact lens according to claim 10, having a tensile strength from 0.4 MPa to 1 MPa.

12. The silicone hydrogel contact lens according to claim 10 or 11, having a droplet contact angle of less than 30°.

13. The silicone hydrogel contact lens according to any one of claims 10 to 12, having a balanced water content of from 45% by weight to 55% by weight.

14. The silicone hydrogel contact lens according to any one of claims 10 to 13, having an oxygen permeability of 110 to 140 barrers.

15. The silicone hydrogel contact lens according to any one of claims 10 to 14, having a Young's modulus from 0.3 MPa to 1.1 MPa.

16. The silicone hydrogel contact lens according to any one of claims 10 to 15, having a chord diameter of 13.5 to 15.5 mm and a base curve of 7.5 to 9.5 mm.

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