Contact lens formulation and contact lens

Abstract

Silicone hydrogel contact lens formulations are described. The formulations have a silicone component, a silicone-free component, and a UV blocker. The silicone component includes compounds represente

Description

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

[002] Silicone hydrogel contact lenses have proven to be acceptable alternatives to hydrogel contact lenses. Contact lens manufacturers are often presented with introducing new contact lenses to satisfy market demand. Thus, there is an ongoing need to develop new silicone hydrogel contact lenses to address this demand.

[003] In the development of silicone hydrogel contact lenses, it is difficult to predict whether a new silicone hydrogel contact lens formulation will result in clinically acceptable silicone hydrogel contact lenses. Achieving a successful fit, an acceptable level of comfort, and an acceptable handling experience is impacted by various changes in lens chemistry, lens design, and manufacturing processes. For example, changing the formulation of a silicone hydrogel contact lens can alter the oxygen permeability, the water content, the lens surface wettability, and mechanical properties such as modulus, tensile strength, and elasticity. Thus, it is unpredictable as to what combination of chemicals in the formulation will result in desired lens properties.

[004] In addition, it is important that lenses are capable of preventing damage to the eye due to exposure to light in the ultraviolet (UV), visible and infrared (IR) bands of the electromagnetic spectrum. UV light has the highest energy and greatest potential to cause damage followed by the violet-blue component of the visible spectrum, i.e. high energy visible light (HEVL) at wavelengths of from 380 to 455 nm. The choice of radiation absorbers is important as they can lead to a yellow colouration being imparted to the lens. They can also have a negative impact on the properties of the final lens. It is important to provide silicone hydrogel contact lenses which can provide desired lens properties whilst also blocking UV light, whilst also being non-yellowing. SUMMARY

[005] The present invention addresses this ongoing need. The inventors have discovered that when particular combinations of certain polysiloxane compounds of silicone hydrogel contact lens formulations are used, it is necessary to adjust other monomers in the formulations in previously unknown ways, in order to achieve certain desirable contact lens properties, such as a consistent lens diameter within a specified range. This combination can be used with a particularly suitable radiation absorber package without impacting on lens properties. The disclosure herein describes this invention in more detail.

[006] The applicant has identified that a suitable silicone hydrogel contact lens formulation can be formed using a reaction mixture comprising a silicone component and a silicone-free component. The silicone component comprises two compounds, Formula 1: ■ ’n wherein Ri is selected from either hydrogen or a methyl group; R2 is selected from either hydrogen or a C1-4 hydrocarbon group; m represents an integer of from 0 to 10; n represents an integer of from 4 to 100; a and b represent integers of 1 or more; a+b is from 20 to 500; b / (a+b) is from 0.01 to 0.22, and the configuration of siloxane units includes a random configuration; and

[007] Formula 2: where n is an integer from 10 to 25.

[008] It is critical that the compound of Formula 1 and the compound of Formula 2 are at a ratio of from 50:50 to 77:23 and in a combined amount of from 45 to 55 weight percent. Preferably, the ratio of the compound of Formula 1 to the compound of Formula 2 is 53:47 to 77:23.

[009] In certain embodiments, in the compound of Formula 1, Ri is selected from either hydrogen or a methyl group; R2 is selected from either hydrogen or a C1-4 hydrocarbon group; m is 0; n represents an integer of from 4 to 15; a represents an integer from 50 to 250, b represents an integer from 5 to 50; and the configuration of siloxane units includes a random configuration, wherein the ratio of a:b is from 5:1 to 30:1, preferably 10:1 to 20:1.

[010] In an additional embodiment, the silicone component additionally comprises an additional silicone compound of Formula 3: R3 CHj CH3 R2 1 R 1—g ।---(OS j ) —c H2 C HC H2O (CHRJ H2 O )KCOC=CHj CH3   ch3 wherein m represents an integer of from 3 to 12, n represents an integer from 1 to 10, R1 is selected from an alkyl group having from 1 to 4 carbon atoms, R2 is either a hydrogen atom or a methyl group, and R3 is either a hydrogen atom or a methyl group.

[011] In some embodiments, in the compound of Formula 3, m is 4, and n is 1, R1 is a butyl group, R2 is H, and R3 is a methyl group.

[012] Where the compound of Formula 3 is present, it is used in an amount of less than 1 weight percent of the total contact lens formulation. In one preferred embodiment of the present formulations, the silicone component consists essentially of Formula 1, Formula 2 and Formula 3.

[013] The combination of compounds of Formula 1 and Formula 2 advantageously allows a lower amount of silicone component to be used whilst still producing a contact lens which has good oxygen permeability. This also allows for a high water content, which is advantageous for wettability.

[014] However, when contact lens formulations are produced using the compounds of Formulae 1 and 2, even at these lower amounts, the tensile strength and Young’s modulus can be high, as seen in Examples 15 to 17 of US8129442.

[015] The applicant has identified that it is possible to produce lenses having a tensile strength substantially lower than that seen in formulations containing the compounds of Formula 1 and Formula 2 by focussed selection of the ratios and / or amounts of specific other monomers.

[016] The formulation typically includes a silicone-free component. The silicone- free component comprises an N-vinyl amide component and a methacrylate component.

[017] The methacrylate component may comprise, or consist of, hydrophobic methacrylate monomers. The methacrylate component may comprise, and in some embodiments consists essentially of or consists of, hydroxybutyl methacrylate (HOB) and isobornyl methacrylate (IBM). It is critical that the HOB and IBM are present in an amount of from 8 to 12 weight percent and that the total amount of IBM is less than 5 weight percent. The HOB and IBM are preferably present in the formulation at a ratio from 70:30 to 90:10. Preferably, the weight ratio of HOB to IBM is from 75:25 to 80:20.

[018] The N-vinyl amide component comprises hydrophilic N-vinyl amide monomers. The N- vinyl amide component may comprise, and in some embodiments consists essentially of or consists of, N-vinyl N-methyl acetamide (VMA). Preferably, the N-vinyl amide component is present in an amount of from 30 to 45 weight percent, preferably 35 to 40 weight percent. Preferably, the N-vinyl amide component consists essentially of or consists of VMA in an amount from 38.0 to 39.0 weight percent.

[019] It has been found, surprisingly, that the particular ratio of HOB to IBM, along with the inclusion of VMA, results in lenses with desirable properties, particularly a low tensile strength and low Young’s modulus compared with previous lenses formed using the combination of the poly siloxane compounds of Formula 1 and Formula 2.

[020] In some embodiments, the total amount of the compound of Formula 2, VMA and HOB is greater than 50 weight percent.

[021] The formulation advantageously includes a chain transfer agent in an amount of from 0.2 to 1.0 weight percent, such as from 0.3, to 0.9 weight percent. A preferred chain transfer agent is allyloxy ethanol (AE).

[022] The formulation additionally contains a UV blocker. The UV blocker comprises: a first high energy visible light (HEVL) absorber comprising a benzotriazole moiety, a second different high energy visible light (HEVL) absorber comprising a benzotriazole moiety, wherein the HEVL absorbers are present in an amount of from 0.8 to 2.7 weight percent. It has been found that by including a combination of two different benzotriazole HEVL absorbers in a contact lens formulation each with different absorption properties, it is possible to obtain a contact lens with improved properties to that which can be produced using a single type of benzotri azole HEVL light absorber. In particular, a contact lens produced from the formulations containing a combination of two different benzotriazole HEVL absorbers has been found to provide a desirable reduction in the levels of light in the 380-455 nm range transmitted by the contact lens when lower overall amounts of benzotriazole high energy, short wavelength visible light absorbers are included in the formulation. Benzophenone UV absorbers have been found to be particularly suited to inclusion in combination with benzotriazole HEVL absorber due to their having a significantly different absorption profile.

[023] In addition, a contact lens produced from the formulations of the invention containing a combination of two different benzotriazole high energy, short wavelength visible light absorbers has been found to provide a desirable reduction in the levels of light in the 380-455 nm range transmitted by the contact lens without substantial yellowing of the contact lens body. It has been further been found that this package of UV blockers can be included in this formulation without impacting negatively on the other lens properties.

[024] The present invention further provides the use of a chain transfer agent to control the diameter of a cast molded silicone hydrogel contact lens in a method of forming a silicone hydrogel contact lens, the method comprising including a chain transfer agent in a polymerizable composition further comprising: at least 35 weight percent of a polymerizable siloxane component, especially at least 40 weight percent of a polymerizable siloxane component, and at least 30 weight percent of an N-vinyl amide component; and cast molding the composition in a contact lens mold.

[025] In a particularly preferred embodiment, the contact lens formulation comprises a silicone component which consists 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-vinyl amide 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. The first HEVL absorber is 2-[2'-hydroxy-3'-te / 7-butyl-5’-(3”-methacryloyloxypropoxy)phenyl]-5-chloro-2JT-benzotriazole (UV28) and the second HEVL absorber is 2-[2'-hydroxy-3'-terLbutyl-5’-(3”-methacryloyloxypropoxy)phenyl]-5-methoxy-2J / -benzotriazole (UV13), wherein the first HEVL absorber is present in an amount of from 0.3 to 0.9 weight percent and the second HEVL absorber is present in an amount of from 0.5 to 2.2 weight percent. It is preferred that the silicone component is from 45 to 55 weight percent of the formulation. It is further preferred that the methacrylate component is from 5 to 15 weight percent of the formulation. It is yet further preferred that the N-vinyl amide component is from 30 to 45weight percent of the formulation.

[026] Preferably the formulation further comprises at least one of: a photoinitiator, a thermal initiator; a crosslinking monomer; and a tinting agent.

[027] In another embodiment of the invention, a silicone hydrogel contact lens comprising the polymerized reaction product of the formulation of any preceding embodiment is disclosed.

[028] The silicone hydrogel contact lens may have a tensile strength from 0.4 MPa to 1.0 MPa. The silicone hydrogel contact lens typically has a tensile strength 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 from 0.5 MPa to 0.9 MPa.

[029] The silicone hydrogel contact lens can have a sessile drop contact angle less than 30 degrees, more preferably less than 25 degrees.

[030] The silicone hydrogel contact lens can have an equilibrium water content from 45 to 55 wt%.

[031] The silicone hydrogel contact lens can have an oxygen permeability of greater than 100 barrers, preferably greater than 110 barrers, more preferably greater than 120 barrers, and especially from 110 to 140 barrers.

[032] The silicone hydrogel contact lens can have a Young’s modulus 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. Young’s modulus is measured by an ANSI Z80.20 standard using an Instron Model 3342 or Model 3343 mechanical testing system, or equivalent method.

[033] The silicone hydrogel contact lens can have a chord diameter from 13.5 to 15.5 mm. The skilled person is aware of other suitable chord diameters.

[034] By using the above amounts of these components, it is possible to produce a lens which has a good balance of properties and in particular a suitably low modulus and tensile strength, whilst offering suitable radiation absorption.

[035] When using the particular selected silicone components, the applicant has identified that the balance of the silicone-free methacrylate component is important to provide good properties for the resultant lens.

[036] One way of establishing whether a lens has good properties is to see whether it meets a relative methacrylate-flexibility product. The applicant has identified that good lenses have a value for this product of greater than 1.25. They preferably have a value greater than 2.5 and more preferably greater than 5. Lenses having a product meeting this value show a good balance of physical properties, and in particular have a good level of flexibility.

[037] The relative methacrylate-flexibility product is measured as: (weight percent HOB / weight percent IBM)*(tensile strength / modulus). This unitless parameter can allow the skilled person to assess quickly whether a lens made of the above identified main monomers will have good properties.

[038] Advantageously, the silicone hydrogel contact lens formulation, comprises: (i) a silicone component; (ii) a silicone-free component; (iii) a UV blocker; and (iv) a chain transfer agent, wherein: (i) the silicone component comprises: (a) a compound of Formula 1: wherein Ri is selected from either hydrogen or a methyl group; R2 is selected from either hydrogen or a C1-4 hydrocarbon group; m represents an integer of from 0 to 10; n represents an integer of from 4 to 100; a and b represent integers of 1 or more; a+b from 20 to 500; b / (a+b) is from 0.01 to 0.22, and the configuration of siloxane units includes a random configuration; and (b) a compound of Formula 2: wherein n is 10 to 25, and the compound of Formula 1 and the compound of Formula 2 are present in the formulation at a ratio from 50:50 to 77:23 and in a combined amount of from 45 to 55 weight percent; (ii) the silicone-free component comprises an N-vinyl amide component (c); and a methacrylate component (d), wherein the N-vinyl amide component (c) comprises N-vinyl N-methyl acetamide (VMA); and the methacrylate component (d) comprises hydroxybutyl methacrylate (HOB) and isobomyl methacrylate (IBM), wherein the hydroxybutyl methacrylate and isobornyl methacrylate are present in the formulation in an amount of from 8 to 12 weight percent and the total amount of IBM is less than 5 weight percent; (iii) the UV blocker comprises: a first high energy visible light (HEVL) absorber comprising a benzotriazole moiety, a second different high energy visible light (HEVL) absorber comprising a benzotriazole moiety, wherein the HEVL absorbers are present in an amount of from 0.8 to 2.7 weight percent, and optionally a polymerizable UV absorbing agent comprising a benzophenone moiety; and (iv) the chain transfer agent includes a C3-C20 unsaturated alcohol, optionally allyloxy ethanol (AE), wherein chain transfer agent(s) are present in an amount from 0.3 to 0.9 weight percent. DESCRIPTION OF THE DRAWINGS

[039] Figure 1 shows the diameter of contact lenses cast molded from the identical formulations in which the amount of chain transfer agent was varied. DETAILED DESCRIPTION

[040] Silicone hydrogel contact lenses are described herein that have good dimensional stability, are ophthalmically-acceptable, and can be manufactured without the use of volatile organic solvents or diluents in the formulations. The silicone hydrogel contact lenses comprise a polymeric lens body that is the reaction product of a polymerizable composition or silicone hydrogel contact lens formulation comprising a silicone component and a silicone-free component. The silicone component comprises, or consists essentially of two compounds, Formula 1 and Formula 2. It is critical that the compound of Formula 1 and the compound of Formula 2 are at a ratio from 50:50 to 77:23 and in a combined amount of from 45 to 55 weight percent.

[041] References herein to ‘at least one’ of a type of ingredient refer to both a) a single ingredient, and b) a combination of two or more ingredients of the same type.

[042] Throughout this disclosure, references to ‘a total amount’ of a particular component (i.e., a combination of two or more ingredients of the same type) in a polymerizable composition refer to the sum of the amounts of all ingredients of the same type.

[043] The following definitions for the quoted terms provided below are applicable herein unless context dictates otherwise:

[044] A “monomer” refers to any molecule capable of reacting with other molecules that are the same or different, to form a polymer or copolymer. Thus, the term encompasses polymerizable pre-polymers and macromers, there being no size constraint of the monomer unless indicated otherwise.

[045] A “siloxane monomer” contains at least one Si—O group, and is typically either “mono-functional” or “multi-functional”, meaning that it has either one polymerizable group or two or more polymerizable groups, respectively. A “non-siloxane monomer” is a monomer that does not contain any Si—O groups.

[046] A “silicone component” is a component or portion of the silicone hydrogel contact lens formulation which is composed of all of the siloxane monomers.

[047] A “silicone-free component” is a component or portion of the silicone hydrogel contact lens formulation which is composed of all of the non-siloxane monomers .

[048] An “N-vinyl amide component” is a component or portion of the silicone-free component of the silicone hydrogel contact lens formulation which is composed of at least one non-siloxane monomer that has a vinyl group bound directly to a nitrogen atom.

[049] A “methacrylate component” is a component or portion of the silicone-free component of the silicone hydrogel contact lens formulation which is composed of at least one non-siloxane monomer that has a single polymerizable methacrylate group.

[050] A “(meth)acrylate-containing monomer” is any non-siloxane monomer that has a single polymerizable (meth)acrylate group (e.g., methyl methacrylate, etc.). A siloxane monomer having at least one polymerizable (meth)acrylate group is referred to herein as a “(meth)acrylate-containing siloxane monomer”. “(Meth)acrylate” covers both methacrylate groups and acrylate groups. Where only methacrylate or acrylate is covered, it will be referred to explicitly.

[051] A “high energy visible light (HEVL) absorber” as used herein may be defined as a compound which, as a 0.003 wt% solution in ethyl acetate (>99.8%, HPLC grade), has an absorbance of at least 0.5 within the range of 375 nm to 450 nm (solutions are measured in a 10 mm path length quartz cell and the absorbance of the solution from 250-800 mm measured using a Perkin Elmer Lambda 365).

[052] A “benzotriazole” moiety is any moiety that contains a benzotriazole group:

[053] “Consists of’ means that a formulation or component contains only the listed components, compounds, or monomers.

[054] “Consists essentially of’ means that a formulation or component contains the listed compounds or monomers but can also contain other monomers or compounds which fall within the definition of that formulation or component such as dimeric or polymeric impurities. These additional monomer or compounds can be present in an amount which does not have an impact on the final lens formulation. Additional monomers or reactive entities can be present in an amount of less than 5%, 2%, 1%, 0.5% or 0.1% based on the total amount of the specific formulation or component.

[055] A “polymerizable composition” is a composition comprising polymerizable ingredients, where the composition has not yet been subjected to conditions that result in polymerization of the polymerizable ingredients. Thus, the present silicone hydrogel contact lens formulations are considered polymerizable compositions.

[056] 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 Mn (in units of Daltons (Da) or g / mol) of the monomer. The number average molecular weight is typically determined using GPC, using polystyrene standards. In addition, the number average molecular weight may be determined by identification of the number average molecular weight on a technical data sheet or specification sheet provided by a chemical supplier to a contact lens manufacturer.

[057] A “chain transfer agent” is a molecule that can transfer a radical from a growing polymer chain to another molecule in a free-radical polymerization reaction thereby reducing the molecular weight of the polymer chain.

[058] In the present disclosure, where a value is given for repeat groups in a structural formula, such as Formula 1, Formula 2 or Formula 3, it is an average value. The skilled person would understand that a complex molecule of this kind contains a mixture of components.

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

[060] Throughout this disclosure, a reference to “an example” or “a specific example” or similar phrase, is intended to introduce a feature or features of the contact lens, polymerizable composition, or method of manufacture (depending on context) that can be combined with any combination of previously-described or subsequently-described examples (i.e. features), unless a particular combination of features is mutually exclusive, or if context indicates otherwise.

[061] Throughout this disclosure, when a series of lower limit ranges and a series of upper limit ranges are provided, all combinations of the provided ranges are contemplated as if each combination were specifically listed. Also, throughout this disclosure, when a series of values is presented with a qualifier preceding the first value, the qualifier is intended to implicitly precede each value in the series unless context dictates otherwise.

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

[063] Further, as used in this specification, the singular forms “a,” “an,” and “the” include plural referents (e.g. at least one or more) unless the context clearly dictates otherwise.

[064] A silicone hydrogel contact lens formulation, comprising a silicone component; and a silicone-free component is disclosed herein.

[065] The silicone component comprises, or consists essentially of, or in some embodiments consists of, a bi-functional (meth)acrylate-containing siloxane monomer and a mono-functional methacrylate-containing siloxane monomer.

[066] The bi-functional (meth)acrylate-containing siloxane monomer is represented by Formula 1: R, CH3 CH3 CH3 R; . « 0¼CgHg8 sQ SiO C3HJs, **■ I '• CH, K* I “ CH, '• T C3^o(cH?QH3gV^3 wherein Ri is selected from either hydrogen or a methyl group; R2 is selected from either hydrogen or a C1-4 hydrocarbon group; m represents an integer of from 0 to 10; n represents an integer of from 4 to 100; a and b represent integers of 1 or more; a+b is from 20-500; b / (a+b) is from 0.01-0.22, and the configuration of siloxane units includes a random configuration.

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

[068] In certain embodiments, in the compound of Formula 1, Ri is selected from either hydrogen or a methyl group; R2 is selected from either hydrogen or a C1-4 hydrocarbon group; m is 0; n represents an integer of from 4 to 15; a represents an integer from 50 to 250, b represents an integer from 5 to 50; and the configuration of siloxane units includes a random configuration, wherein the ratio of a:b is from 5:1 to 30:1, preferably 10:1 to 20:1.

[069] It is preferred that Ri is a methyl group. It is preferred that R2 is H or a methyl group, and more preferably a methyl group. It is additionally preferred that m is 0. It is preferred that n is from 6 to 9.

[070] In one 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. It is further preferred that Ri is methyl, R2 is methyl, m is 0 and n is from 7 to 8.

[071] A particularly preferred bi-functional (meth)acrylate-containing siloxane monomer has a CAS Registry Number of: 1216820-69-7.

[072] 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. It is further preferred that Ri is methyl, R2 is methyl, m is 0 and n is from 7 to 8.

[073] Methods of making compounds of Formula 1 are described in US. Patent no. 8,129,442 (incorporated herein by reference).

[074] The mono-functional methacrylate-containing siloxane monomer is represented by Formula 2: where n is an integer from about 10 to 25, preferably from 13 to 18.

[075] The mono-functional methacrylate-containing siloxane monomer of Formula 2 has an average molecular weight of less than 2,000, preferably less than 1,800 Da, and greater than 800, preferably greater than 1,000 Da. In a further specific example, the monofunctional methacrylate-containing siloxane monomer may have an average molecular weight of from 1,000 to 1,800 Da.

[076] Preferably, the mono-functional methacrylate-containing siloxane monomer has a CAS registry number of 697234-76-7.

[077] Siloxane monomers of Formula 2 are described in US. Pat. No. 6,310,169 (incorporated herein by reference).

[078] The compound of Formula 1 and the compound of Formula 2 are at a weight ratio of from 50:50 to 77:23. In one preferred embodiment, the weight ratio of the compound of Formula 1 to the compound 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.

[079] The compound of formula 1 and the compound of formula 2 are in a combined amount of from 45 to 55 weight percent.

[080] In an additional embodiment, the silicone component comprises an additional silicone compound, which is a mono-functional (meth)acrylate-containing siloxane monomer of Formula 3: CH3 CH3 R2 |R3 R?— Si---CH2CIICH2O^^^ CH.   CHj wherein m represents an integer of from 3 to 12, n represents an integer from 1 to 10, R1 is selected from an alkyl group having from 1 to 4 carbon atoms, and each of R2 and R3 of Formula 3 is independently selected from a hydrogen atom or a methyl group.

[081] In some embodiments, in the compound of Formula 3, m is 4, and n is 1. It is further preferred that R1 is a butyl group, R2 is H, and R3 is a methyl group.

[082] Where the compound of Formula 3 is present, it is used in an amount of less than 1 weight percent, preferably less than 0.8 weight percent, more preferably less than 0.6 weight percent of the total contact lens formulation. In one preferred embodiment of the present formulations, the silicone component consists essentially, preferably consists of Formula 1, Formula 2 and Formula 3.

[083] In some embodiments, the weight percent of the silicone component is greater than 48% or 48.5%. In some embodiments the weight percent of the silicone component is less than 53%, 52.5%, 52%, 51.5%, 51%, or 50.5%. In some embodiments any one of the lower limits of the weight percent of the silicone component is combined with any one of the upper limits of the weight percent of the silicone component. For example, the silicone component can be present in the formulation from 48 weight percent to 53 weight percent, preferably from 48 weight percent to 51 weight percent.

[084] In another preferred embodiment, it is preferred that the amount of the compound of Formula 2 is greater than 12 weight percent of the total composition. It is further preferred that the amount of the compound of Formula 2 is less than 25 weight percent. For example, the compound of Formula 2 can be present in the formulation from 12 to 25 weight percent.

[085] In another preferred embodiment, the amount of the compound of Formula 1 is less than 38 weight percent. It is further preferred that the amount of the compound of Formula 1 is greater than 26 weight percent. For example, the compound of Formula 1 can be present in the formulation from 26 to 38 weight percent.

[086] It is particularly preferred that the amount of the compound of Formula 2 is greater than 12 weight percent and the amount of the compound of Formula 1 is less than 38 weight percent.

[087] In addition, it can be understood that the silicone component of the present formulations is free of a hydroxy-functionalized siloxane compound, is free of TRIS, or is free of both.

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

[089] The N-vinyl amide component comprises N-vinyl N-methyl acetamide (VMA). It is further preferred that the N-vinyl amide component consists essentially of, and preferably consists of VMA.

[090] In one preferred embodiment, the N-vinyl amide component consists essentially of, and preferably consists of VMA. In a further specific example, the polymerizable composition has a weight ratio of total amount of N-vinyl amide component to total amount of (meth)acrylate-containing siloxane monomer (i.e., the mono- and bifunctional (meth)acrylate-containing siloxane monomers) of from about 40:60 to 45:55. It is further preferred that the ratio is from 44:56 to 45:55.

[091] Where the N-vinyl amide component consists essentially of, or consists of VMA, the weight percent of the N-vinyl amide component is greater than 36.0%, or 37.0% or 38.0%. The weight percent of the N-vinyl amide component is less than 41,0%or 40.0% or 39.0%. In some embodiments any one of the lower limits of the weight percent of the N-vinyl amide component is combined with any one of the upper limits of the weight percent of the N-vinyl amide component. In some embodiments the weight percent of the N-vinyl amide component is between 38% and 39%.

[092] 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.

[093] The methacrylate component comprises hydroxybutyl methacrylate (HOB) and isobomyl methacrylate (IBM). It is critical that the HOB and IBM are present in the formulation in an amount of from 8 to 12 weight percent and that the total amount of IBM is less than 5 weight percent. Preferably, the HOB and IBM are present in the formulation at a ratio from 70:30 to 90:10.

[094] The methacrylate component (d) comprises, and in some embodiments consists essentially of, and in some embodiments consists of, hydroxybutyl methacrylate (HOB) and isobornyl methacrylate (IBM). In some embodiments, the ratio of HOB to IBM is greater than 60:40, 65:35, 70:30, or 75:25. In some embodiments, the ratio of HOB to IBM is less than 90:10, 85:15, or 80:20. In some embodiments any one of the lower limits of 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 hydroxybutyl methacrylate and isobomyl methacrylate are present in the formulation at a weight percent greater than 8weight percent. In some embodiments, hydroxybutyl methacrylate and isobornyl methacrylate are present in the formulation at a weight percent less than 10. In some embodiments any one of the lower limits of HOB and IBM is combined with any one of the upper limits of HOB and IBM. Preferably the total amount of HOB and IBM is from 8 to 10 weight percent.

[095] Other silicone-free methacrylate-containing monomers are known in the field and can be present in the contact lens formulation. Exemplary silicone-free methacrylatecontaining monomers include methyl methacrylate (MMA), tert butyl methacrylate (tBMA), 2-hydroxyethyl methacrylate (HEMA), ethylene glycol methyl ether methacrylate (EGMA), and combinations thereof. A preferred additional silicone-free methacrylate-containing monomer is methyl methacrylate (MMA).

[096] It is preferred that these additional methacrylate-containing monomers are present in a total amount of less than 5%, more preferably less than 3% by weight, yet more preferably less than 1 % by weight of the contact lens formulation and even more preferably in the minor amounts as defined above where the methacrylate component consists essentially of HOB and IBM. It is particularly preferred that there are no other methacrylatecontaining monomers.

[097] In a specific example, the polymerizable composition may have a weight ratio of the compound of Formula 2 to total amount of non-siloxane methacrylate-containing monomer of greater than 0.9:1, preferably greater than 1:1.

[098] In another specific example, the total amount of mono-functional (methacrylate-containing non-silicone and siloxane monomers, collectively is greater than 26 weight percent, and preferably greater than 30 weight percent.

[099] The UV blocker comprises: a first high energy visible light (HEVL) absorber comprising a benzotriazole moiety, a second different high energy visible light (HEVL) absorber comprising a benzotriazole moiety, wherein the HEVL absorbers are present in an amount of from 0.8 to 2.7 weight percent, and optionally a polymerizable UV absorbing agent comprising a benzophenone moiety.

[0100] High energy visible light (HEVL) absorbers are compounds that includes a chromophore that absorbs visible light in the violet-blue range of 350-455 nm. Typically, a HEVL absorber has an absorption maximum (kmax) in the range of 350-455 nm, especially in the range of 350-400 nm. The first and second HEVL absorbers in the formulations of the invention are each optionally of formula 4: HO R6 R7 Formula 4 wherein: R1 is a halogen, OH, C1-12 alkyloxy, -A-R9-Y, optionally substituted C1-12 alkyl, optionally substituted phenoxy, or optionally substituted napthyloxy, where the optional substituents are halogen, C1-6 alkyl, C1-6 alkoxy, OH, -(CH2CH2O)nH, -(CH2CH2O)nCH2CH3, -(CH2CH(CH3)O)nH or -(CH2CH(CH3)O)nCH2CH2(CH3); one of R6 and R7 is H or C1-12 alkyl optionally substituted with halogen; and the other of R6 and R7 is: in which: R2 is a bond, C1-12 alkylene optionally substituted with -OH and / or optionally interrupted by an ester group, (CH2CH2O)n or (CH2CH(CH3)O)n; X is a bond, O, NR4, S or (Si(CH3)2O)mSi(CH3)2; R3 is a bond, C(0), C(0)CjH2j, C1-6 alkylene, phenyl, or C1-6 alkylphenyl; each R4 is independently H or methyl; R5 is H, C1-6 alkyl, or phenyl; m is 0-9; n is 2-10; j is 1-6; A is -S- or -SO2-; R8 is H, C1-12 alkyl, Ce-is arylalkyl or -R9-Z; each R9 is independently C1-12 alkylene optionally substituted with -OH and / or interrupted by an ester group; each of Y and Z respectively is -OH, -OC(O)R10, -NH2, -NC(O)R10, -NCO, -CO2H, -CO2R10, each R10 is independently Ci-io alkyl or C3-10 alkenyl; R11 is C3-10 cycloalkenylene; and R12 is Ci-10 alkylene or 1,2-phenylene.

[0101] Examples of benzotri azole HEVL absorbers include:

[0102] 2-(1, l-dimethylethyl)-4-[3-[(4-ethenyl phenyl) methoxy]propoxy]-6-(5- methoxy-2H-benzotriazol-2-yl)-phenol (UV1, CAS # 159732-06-6): UV1

[0103] 2-(5-chloro-2H-benzotriazol -2 -yl)-6-(l,l-dimethylethyl)-4-ethenyl -phenol (UV5 / UVAM, CAS # 124883-10-9): UV5,

[0104] 2-(2-hydroxy-5-methacrylamidophenyl)-5-methoxy-2JH-benzotriazole (UV6, CAS # 110927-08-7):

[0105] 39-0):

[0106] 98809-58-6): HO X. UV6, 2-(3-allyl-2-hydroxy-5-methylphenyl)-2H-benzotriazole (UV9, CAS # 2170- UV9, l-methallyl-2-(2-hydroxy-5-methyl phenyl) benzotriazole (UV12, CAS # UV12,

[0107] 2-[2'-hydroxy-3'-te / 7-butyl-5’-(3”-methacryloyloxypropoxy)phenyl]-5- methoxy-27 / -benzotriazole (UV13, CAS # 114166-71-1): UV13,

[0108] 2-3'-t-butyl-2'-hydroxy-5'-(3"-dimethylvinylsilylpropoxy)-2'-hydroxy-phenyl)- 5-methoxybenzotriazole (UV15, CAS # 122430-79-9): UV15,

[0109] 2-(2 ’ -hydroxy-5 ’ -methacryloylpropyl-3 ’ -tert-butyl-phenyl)-5 -m ethoxy -2H- benzotriazole (UV16, CAS # 1245624-41-2): UV16,

[0110] 3-[3 -(1, l-dimethylethyl)-4-hydroxy-5-[5-(trifluoromethyl)-2H-benzotriazol-2- yl]phenoxy]propyl ester 2-methyl-2-Propenoic acid, (UV23, CAS # 2050905-16-1): UV23,

[0111] 2-[2'-hydroxy-3'-te / 7-butyl-5’-(3”-methacryloyloxypropoxy)phenyl]-5-chloro- 27 / -benzotri azole (UV28, CAS # 275371-71-6): UV28, and

[0112] and 3-[3-(2H-benzotriazol-2-yl)-5-(l,l-dimethylethyl)-4- hydroxyphenoxy]propyl ester 2-methyl-,2-propenoic acid, (UV29, CAS # 2254219-66-2):

[0113] All the above HEVL absorbers are available from LYNN Laboratories, Inc. of 2797 Irving Blvd STE 110, Dallas, TX 75207.

[0114] Optionally the first HEVL absorber is UV28 and the second HEVL light absorber is one of UV1, UV5, UV13 or UV15 or a combination of any of UV1, UV5, UV13 and UV15. One of UV1, UV5, UV13 or UV15 or a combination of any of UV1, UV5, UV13 and UV15 may be present in an amount of from 0.5 to 2.2 weight percent, and preferably from 0.7 to 1.6 weight percent; and UV28 may be present in an amount of from 0.3 to 0.9 weight percent, and preferably from 0.4 to 0.7 weight percent. Optionally the first HEVL absorber is UV28 and the second HEVL light absorber is UV13. UV13 may be present in an amount of from 0.5 to 2.2 weight percent, and preferably from 0.7 to 1.6 weight percent; and UV28 may be present in an amount of from 0.3 to 0.9 weight percent, and preferably from 0.4 to 0.7 weight percent.

[0115] Typically, the formulation further comprises one or more additional components which are common in contact lens formulations. Suitable additional components include a photoinitiator, a thermal initiator, a cross-linking agent and a tinting agent.

[0116] The polymerizable composition may additionally comprise at least one nonsiloxane cross-linking agent. As used herein, a “cross-linking agent” is any compound having a molecular weight of less than about 2,000 Da. with two or more ethylenically unsaturated groups. Thus, a cross-linking agent can react with functional groups on two or more polymer chains so as to bridge one polymer to another. Triallyl isocyanurate (TAIC) is particularly preferred as the cross-linker in the formulations of the present invention.

[0117] The cross-linker is preferably used in an amount of from 0.03 to 0.2 weight percent of the contact lens formulation.

[0118] The composition additionally can comprise one or more tinting agents. Preferred tinting agents are reactive tinting agents and particularly tinting agents identified as “Reactive Blue” dyes.

[0119] Contact lenses can be made from the polymerizable compositions described herein using curing and other processing methods known in the field, such as cast molding, spin casting, injection molding, forming a polymerized rod that is subsequently lathed, etc. In a specific example, the polymerizable composition is cast molded between molds formed of a thermoplastic polymer. The thermoplastic polymer is typically a non-polar material, such as polypropylene, but polar mold materials, such as ethylene vinyl alcohol, are also used in the field. Briefly, a first mold member defining the front surface of the contact lens, referred to as a “female 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 (i.e. eye-contacting) surface of the contact lens, referred to as the “male mold member”, is coupled to the female mold member to form a mold assembly having a lens-shaped cavity with the amount of polymerizable composition therebetween.

[0120] The polymerizable composition within the contact lens mold assembly is polymerized using any suitable curing method. Typically, the polymerizable composition is exposed to polymerizing amounts of heat or ultraviolet light (UV). In the case of UV-curing, also referred to as photopolymerization, the polymerizable composition typically comprises a photoinitiator such as benzoin methyl ether, 1-hydroxycyclohexylphenyl ketone, Darocur or Irgacur (available from Ciba Specialty Chemicals). Photopolymerization methods for contact lenses are described in U.S. Pat. No. 5,760,100 incorporated herein by reference. In the case of heat-curing, also referred to as thermal curing, the polymerizable composition typically comprises a thermal initiator. Exemplary thermal initiators include 2,2'-azobis(2,4-dimethylpentanenitrile) (VAZO-52), 2,2'-Azobis(2-methylpropanenitrile) (VAZO-64), and l,l'-azo bis(cyanocyclohexane) (VAZO-88). The contact lens mold assemblies containing the contact lens formulations are cured by exposing the contact lens mold assemblies to heat or UV light for a time ranging from about 1 hour to about 5 hours. Additional thermal polymerization methods for contact lenses are described in US Publ. No. 2007 / 0296914 and U.S. Pat. No. 7,854,866, incorporated herein by reference.

[0121] 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, i.e. delensed, from the mold member to which it is adhered. These processes are referred to as demolding and delensing, respectively, and a variety of such methods are known to those of ordinary skill in the field. In some methods, the demolding and delensing processes can comprise a single process step, such as when the molds are separated using a liquid 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 carried out by a “float off’ method in which the mold member to which a polymeric lens body is adhered is immersed in water. The water may optionally be heated (e.g. up to about 100° C). Typically, the polymeric lens bodies float off the mold members in about ten minutes. Dry delensing can be carried out manually, for example using tweezers to remove the polymeric lens bodies from the mold member, or they can be removed using an automated mechanical process, such as described in U.S. Pat. No. 7,811,483 (incorporated herein by reference). Additional demolding and delensing methods for silicone hydrogel contact lenses are described in US Publ. No. 2007 / 0035049 (incorporated herein by reference).

[0122] After delensing, 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 lenses can be exposed to organic solvents, such as ethanol, isopropyl alcohol, industrial methylated spirts, and the like, or water, or mixtures thereof. Exemplary washing methods are described in US Pat. Publ. No. 2007 / 0296914 (incorporated herein by reference) and in Example 1 below.

[0123] After washing, the hydrated polymeric lens body is typically placed into a blister package, glass vial, or other appropriate container, all referred to herein as “packages.” A packaging solution is also added to the container, which is typically a buffered saline solution such as phosphate- or borate-buffered saline. The packaging solution may optionally contain additional ingredients such as a comfort agent, a hydrophilic polymer, a surfactant or other additive that prevents the lens from 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.

[0124] In any of the above-described examples, the contact lens may be characterized by one or more of the following properties: contact angle, oxygen permeability, tensile strength, Young’s modulus, and equilibrium water content, as detailed below.

[0125] In any of the below-described examples, the contact lens may have a contact angle of less than about 30°, or 25°, where the contact angle is the static advancing contact angle as determined using a sessile drop method. To determine the contact angle of a contact lens surface, contact lenses to be tested are soaked in phosphate buffered solution (PBS) for at least 12 hours. Using rubber tipped tweezers, the lenses are removed from the PBS and shaken to remove excess water. A 4 mm diameter section of each lens is cut with a lens cutter. The surface of the contact lens section to be tested is blotted dried by placing it face down on a microscope lens wipe and gently dragging the lens section across the wipe using rubber tipped tweezers until no liquid is observed absorbing into the wipe. The lens section is placed on a microscope slide, ensuring that it lies flat with the blotted surface facing upwards. Measurements are taken promptly to ensure that the lens section does not become dry (as evidenced by deformation of the lens section). In the Kriiss DSA-100, the Drop Shape Analysis program is turned on and the “Sessile drop (VCA eq)” method is selected with the following settings: camera tilt=+2; 100 pl syringe with straight needle; dispense solution=purified water; dispense volume=0.75 pl; dispense speed=7.5 pl / min; and dispense 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 in the viewing screen and the image is adjusted until a maximum is reached in the median window. The water is dispensed onto the lens. Between 10 to 15 seconds after dispensing the water, the image of the drop is captured. A calculation method is selected according to the contact angle as follows: <30°=Circle Fitting Method, 30°-130°=Tangent Method-1; >130°=Tangent Method-2. The average contact angle measurement of 5 lens sections is taken to be the contact angle for the particular surface (i.e. posterior or anterior) of the contact lens.

[0126] For oxygen permeability, the Dk values provided in the Examples below were determined using a Rehder 20IT Oxygen Permometer / polarographic cell following the polarographic method described in ISO18369-4:2017 section 4.4.3.

[0127] In any of the below-described examples, the contact lens may have a Young’s modulus (i.e. tensile modulus) of at least 0.3 MPa or 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.

[0128] 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 lens typically has 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.

[0129] The 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-built rectangular contact lens cutting die with 4 mm spacing to prepare the rectangular sample strip. The modulus was determined inside a chamber having a relative humidity of least 70%. A lens was soaked in phosphate buffered solution (PBS) for at least 10 minutes prior to testing. While holding the lens concave side up, a central strip of the lens was cut using the cutting die. 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 fitting over at least 75% of the grip surface of each grip. A test method designed to determine the maximum load (N), the tensile strength (MPa), the strain at maximum load (% elongation) and the mean and standard deviation of the tensile modulus (MPa) was run, and the results were recorded.

[0130] In any of the above-described examples, the contact lens may have an equilibrium water content (EWC) of at least about 30 wt. %, 40 wt. % or 45 wt. % and up to about 50 wt%, 55 wt%, 60 wt. % or 70 wt. %. For example, the contact lens may have an EWC from 40 to 60 wt%. Unless otherwise specified, EWC refers to the water content of a fully hydrated lens which can be measured using the BS EN ISO 18369-4:2017: Section 4.6 gravimetric test method after equilibrating the lens at 20° C in standard saline solution (see ISO 18369-3:2017 4.9.2.1) as follows: excess surface water is wiped off the lens and the lens is weighed to obtain the hydrated wet weight. The lens is dried in an oven at 105° C and weighed until a steady weight is reached to obtain a fully dehydrated, dry weight. The weight difference is determined by subtracting the weight of the dry lens from the weight of the wet lens and the % water content the wet lens when fully hydrated is calculated as follows: Wet weight - Dry weight x 100 = % water content Wet weight

[0131] The water content of lenses at a set relative humidity (RH) level (e.g. 97.5% RH) can be determined by equilibrating the fully hydrated lenses in standard saline solution (see ISO 18369-3:2017 4.9.2.1) then equilibrating the fully hydrated lenses in a humidity and temperature-controlled chamber at 25 °C at the required RH until a steady weight is reached to give a wet weight at the RH level. The dry weight is obtained by drying the same lens in the humidity and temperature-controlled chamber at 25 °C and 0.5%RH until a steady weight is reached. The % water content at that RH can be determined from the difference between the weight of the wet lens at the desired RH and the dry weight of the same lenses when equilibrated to a steady weight at 0.5%RH at 25 °C, according to the above equation. In a specific example, the contact angle is ^30° and the equilibrium water content is most preferably at least 45 wt. % and up to 55 wt%.

[0132] As is evident from the disclosure of the application as a whole, including the claim structure and the specific examples, the exemplary components of the polymerizable composition disclosed herein are typically combined in embodiments of the invention. For example, the person skilled in the art would recognize that the polymerizable composition of the invention advantageously includes the exemplary mono-functional (meth)acrylate-containing siloxane monomers disclosed herein in combination with the exemplary bifunctional (meth)acrylate-containing siloxane monomers disclosed herein and in combination with the exemplary N-vinyl amide components disclosed herein and in combination with the exemplary (meth)acrylate components disclosed herein.

[0133] As demonstrated by the specific examples, it has been found that combinations of the preferred mono-functional methacrylate-containing siloxane monomers, bi-functional (meth)acrylate-containing siloxane monomers, N-vinyl amide component, and methacrylatecontaining monomers of the invention provide contact lenses of the invention with advantageous properties such as reduced tensile strength.

[0134] The polymerizable composition may additionally comprise at least one chain transfer agent, i.e., can comprise one chain transfer agent or can comprise a chain transfer agent component comprising at least two chain transfer agents. Examples of chain transfer agents which can be included as the chain transfer agent or the chain transfer agent component of the present polymerizable compositions include, thiol compounds, or halocarbon compounds, or C3-C5 hydrocarbons, or C3-C20 unsaturated alcohols, or any combination thereof. A particularly suitable chain transfer agent is an unsaturated alcohol having a terminal unsaturated group, such as a compound of the formula: H2C=CH-CH2[O-CH2-CH2]n-OH where n is an integer from 1 to 5, especially allyloxy ethanol. In Examples 1 and IC disclosed herein, the chain transfer agent is allyloxy ethanol. When present in the polymerizable composition, the chain transfer agent or chain transfer agent component may optionally be present in an amount from about 0.1 weight percent to about 1.5 weight percent. The chain transfer agent, e.g. allyloxy ethanol, may advantageously be present in an amount of from 0.2 to 1.0 weight percent, such as from 0.3, to 0.9 weight percent.

[0135] It has been found that the diameter of a cast-molded silicone hydrogel contact lens can be controlled by varying the amount of a chain transfer agent present in the polymerizable composition. In particular, it has been found that the diameter of a cast molded silicone hydrogel contact lens formed from a polymerizable composition comprising: at least 35 weight percent of a polymerizable siloxane component at least 30 weight percent of an N-vinyl amide component can be controlled using a chain transfer agents, such as allyloxy alcohol. A chain transfer agent may, for example, be used to control the diameter of a lens from a polymerizable composition comprise a siloxane component in an amount of at least 35 weight percent based on the total weight of the formulation, such as from 40 to 60 weight percent), wherein at least 40% of the siloxane content is di-functional siloxanes having a molecular weight of at least 8,000 Daltons and wherein at least 25 weight percent of the polymerizable siloxane content is mono-functional siloxanes having a molecular weight of less than 3000 Daltons; and an N-vinyl amide monomer component present in an amount of at least 30 weight percent, especially at least 37 weight percent, based on the total weight of the formulation and optionally a non-siloxane hydrophobic methacrylate monomers in an amount of at least 5 weight percent based on the total weight of the formulation. The amount of chain transfer agent used to control the diameter of a silicone hydrogel contact lens, e.g. a silicone hydrogel contact lens formed from the polymerizable compositions described above, may be from amount of from 0.2 to 1.0 weight percent, such as from 0.3, to 0.9 weight percent. The chain transfer agents used may be a thiol compound, or halocarbon compound, or C3-C5 hydrocarbon, or C3-C20 unsaturated alcohol, or any combination thereof. A particularly suitable chain transfer agent is an unsaturated alcohol having a terminal unsaturated group, such as a compound of the formula: H2C=CH-CH2[O-CH2-CH2]n-OH where n is an integer from 1 to 5, especially allyloxy ethanol. EXAMPLES

[0136] The following Examples illustrate certain aspects and advantages of the present invention, which should be understood not to be limited thereby. The reactants used in the Examples are detailed in Table 1, the particular amounts of each component used are set out in Table 2, ratios and combined totals of components are presented in Table 3 and the properties are presented in Table 4.

[0137] The silicone hydrogel lenses of Example 1, Example 1A, Example IC and Comparative Examples were produced according to the following method: The compounds or monomers of Table 1 were mixed together in the relative amounts by weight shown in Table 2 to form a polymerizable composition (i.e. a silicone hydrogel contact lens formulation). The formulation was put in a mold for a contact lens. The lenses were cured using ultraviolet light for about 1 hour (Examples 1, 1A and IC and Comparative Examples). The skilled person is aware of suitable methods for curing contact lens formulations. The cured polymers were removed from the contact lens molds and washed to remove unreacted materials by contacting them with organic solvent, water, or combinations thereof, and then the washed contact lenses were placed in a package and sterilized in an autoclave to provide a sterilized packaged contact lens. The contact lenses of all Examples and Comparative Examples were transparent and flexible, and also had good water wettability.

[0138] Table 1 Abbreviation Compound Si-1 Formula 1 above wherein Ri is a methyl group, R2 is a methyl group, m is 0, a is 60-100, b is 4-7, n is 6-8. Si-la Formula 1 above wherein Ri is a methyl group, R2 is a methyl group, m is 0, a is 120-230, b is 6-15, and n is 6-8. Si-2 Formula 2 above wherein n is 16. Si-3 Formula 3 above wherein R1 is a butyl group, R2 is hydrogen, and R3 is a methyl group, and n is 1, and m is 5. VMA N-vinyl-N-methylacetamide [CAS# 3195-78-6] NVP N-vinyl pyrrolidone [CAS# 88-12-0] HOB Hydroxybutyl methacrylate [CAS# 29008-35-3] IBM Isobornyl methacrylate [CAS# 7534-94-3] TAIC Triallyl isocyanurate [CAS# 1025-15-6] TPP Triphenylphosphine [CAS# 603-35-0] TPO Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide [CAS# 75980-60-8] AIBN Azobisisobutyronitrile [CAS # 78-67-1] AOT Sodium bis(2-ethylhexyl)sulfosuccinate (sodium dioctyl sulfosuccinate) [CAS# 577-11-7] AE 2-Allyloxyethanol [CAS # 111-45-5] UV13 2-[2'-hydroxy-3'-tert-butyl-5’-(3”-methacryloyloxypropoxy)phenyl]-5-methoxy-2 / / -benzotriazole [CAS # 114166-71-1] UV28 2-[2'-hydroxy-3'-tert-butyl-5’-(3”-methacryloyloxypropoxy)phenyl]-5-chloro-2J / -benzotri azole [CAS # 275371-71-6]

[0139] Table 2 Ingredient Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Comp. Ex. 4 Comp. Ex. 5 Comp. Ex. 6 Ex. 1 Ex. 1A Ex. IC TAIC 0.10 0.10 0.10 0.12 0.12 0.09 0.05 0.05 0.05 IBM 5.40 5.40 5.40 3.40 1.40 1.87 2.08 2.08 2.08 HOB 9.00 9.00 9.00 11.00 9.00 13.73 6.92 6.92 6.92 VMA 9.00 7.00 7.00 9.00 9.00 10.42 38.72 38.72 38.72 NVP 27.10 27.10 27.10 27.10 27.10 24.30 Si-1 26.97 30.15 30.15 30.15 Si-la 39.80 39.80 34.80 37.78 41.78 Si-2 9.00 11.00 16.00 11.00 11.00 22.07 17.99 17.99 17.99 Si-3 0.49 0.49 0.49 AE 0.63 0 1.23 Reactive dye 0.01 0.01 0.01 0.01 TPO 0.10 0.10 0.10 0.10 0.10 0.09 AIBN 0.45 0.45 0.45 TPP 0.40 0.40 0.40 AOT 0.50 0.50 0.50 0.50 0.50 0.05 UV13 1.08 1.08 1.08 UV28 0.50 0.50 0.50 Other UV blockers 0.54 0.54 0.54 Total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 99.4 100.6 US8129442 Ex. 15 Ex. 16 Ex. 17 Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Comp. Ex. 4 Comp. Ex. 5 Ex. 1 Total Silicone (%) 48.82 48.82 48.82 48.80 50.80 50.80 48.78 52.78 48.63 Sum NVP+ VMA (%) 36.17 36.17 36.17 36.10 34.10 34.10 36.10 36.10 38.72 Sum HOB+IBM (%) 14.47 14.47 14.47 14.40 14.40 14.40 14.40 10.40 9.00 Sum Si-2 (Formula 2) + Si-3 + IBM + HOB (%) 23.51 23.51 23.51 23.40 25.40 30.40 25.40 21.40 27.48 Sum Si-2 (Formula 2) + Si-3 + VMA + NVP (%) 45.21 45.21 45.21 45.10 45.10 50.10 47.10 47.10 57.20 Ratio Si-1 (Si-la):Si-2 (Formula 2) 81:19 81:19 81:19 82:18 78:22 69:31 77:23 79:21 63:37 Ratio NVP:VMA 75:25 75:25 75:25 75:25 79:21 79:21 75:25 75:25 0:1 Ratio HOB IBM 63:37 63:37 63:37 63:37 63:37 63:37 76:24 87:13 77:23 Ratio (NVA+VMA):(Si-l (Si-la) + Si-2 + Si-3) 42.6:57.4 42.6:57.4 42.6:57.4 42.5:57.5 40.2:59.8 40.2:59.8 42.5:57.5 41.5:58.5 44.3:55.7 Ratio Si-2 (Formula 2): (HOB+IBM) 38:62 38:62 38:62 38:62 43:57 53:47 43:57 51:49 67:33 US8129442 Ex. 15 Ex. 16 Ex. 17 Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Comp. Ex. 4 Comp. Ex. 5 Ex. 1 Ex. 1A Ex. IC Diameter (mm) 14.4 14.26 14.3 14.47 14.44 14.20 14.44 13.88 EWC (%) 44 55 30 49 48 47 49 49 52 52 50 Young’s Modulus (MPa) 0.71 0.74 0.68 0.74 0.85 0.84 0.86 0.85 Dk (barrers) 115 90 150 127 131 124 139 129 Tensile Strength (MPa) 3 3 2.8 1.02 1.3 0.85 0.85 0.86 0.89 0.93 0.90 Sessile Drop Contact Angle (degrees) 44 40 50 21.1 25.4 27.5 20.0 (weight % HOB / weight % IBM)*(tensile strength / modulus) 1.2 0.95 1.3 2.8 6.4 2.8

[0142] In Table 3, "(Formula 2)" refers to the general structure of the compound of Formula 2 in this description, and Si-2 is a specific embodiment within Formula 2.

[0143] It is surprising that the particular selection of non-silicone monomers and the ratio of HOB to IBM can cause such a significant reduction in the tensile strength of the resulting lens. It is further surprising that these properties are retained even in the presence of the benzotriazole-containing HEVL absorbers. The lenses of the present invention retain the 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.

[0144] Figure 1 shows the diameter of contact lenses cast molded from the formulations of Example 1, 1A and IC. It has been found that the presence of the chain transfer agent, allyloxy ethanol in the polymerizable composition of the present invention an amount of from 0.3, to 0.9 weight percent, such as about 0.6 weight percent (Example 1) provides lenses with a consistent diameter of about 14.3 mm, i.e. within the required specification of 14.0 to 14.4 mm. When no chain transfer agent was included in the formulation (Example 1 A) the diameter was above the desired range, whereas when greater than 1.0 weight percent chain transfer agent was present such as about 1.3 weight percent allyloxy ethanol (Example IC) the diameter was below the desired range. Thus, it has been found that a chain transfer agent may be used to control the diameter of the cast-molded silicone hydrogel contact lens.

[0145] Silicone hydrogel contact lenses contain water and will dehydrate when exposed to atmospheric conditions. Lens dehydration during wear can affect the lens fit, for example due to changes in the lens shape and size; the level of wearer comfort due to a change in the stiffness of the lens material; and surface wetting of the lens.

[0146] When worn on the eye, a contact lens is protected from dehydration by the tear film. If the tear film breaks, then the lens will be exposed to the ambient atmosphere and localised dehydration of the lens surface occurs leading to a reduction in lens hydration during wear. The presence of the contact lens interferes with reflex blinking, as the eye below the lens typically remains wet so will not trigger the response, meaning that blinking may not occur immediately when the tear film on the lens surface breaks. Some activities have been shown to further reduce blinking frequency such as driving and some computer-based activities. It is desirable for a silicone hydrogel contact lens to retain a high proportion of water in the period after the film on the lens surface breaks and before blinking restores a tear film over the lens.

[0147] The equilibrium water content (EWC) of a lens is a well known measure of the water content of a fully hydrated lens, which is believed to reflect the water content of a lens when covered with a tear film. However, a lens would advantageously retain water content when exposed to air following breaking of the tear film to prevent the lens from becoming temporarily dehydrated in the period before the tear film is restored. The lenses of the present invention have been found to have a greater ability to resist dehydration than comparable commercially available lenses.

[0148] The water content of lenses was determined and Table 5 shows the % EWC when measured under the ISO gravimetric method (BS EN ISO18369-4:2017 Section 4.6). The % water content was also determined at 97.5% RH by comparing the wet weight of a lens at 97.5% RH and the dry weight of the lens. The wet weight 97.5% RH is determined by equilibrating the lens at 20° C in standard saline solution consisting of a solution of 0.8300 % (w / v) sodium chloride (NaCI), 0.0528 % (w / v) sodium dihydrogen orthophosphate dihydrate (NaH2PO4.2H2O) and 0.5993 % (w / v) disodium hydrogen orthophosphate dodecahydrate (Na2HPO4.12H2O), then exposing the lens to 97.5% RH at 25 °C in humidity and temperature-controlled chamber until a steady weight was reached. The same lens is then exposed to 0.5% RH at 25 °C in the humidity and temperature-controlled chamber until a steady weight was reached to determine the dry weight. The % hydration of the contact lenses at 97.5% RH was then determined by comparing the maximum EWC as measured by the ISO method to the % water content at 97.5% RH.

[0149] Table 5 Lens Material ISO %EWC (measured) % water content at 97.5%RH %Hydrated at 97.5%RH Example 1 51.9 27.3 ±0.5 53.6 ± 1.0 Comp. Ex 6 48.1 23.9 ±0.2 49.8 ±0.4 Biofinity 47.2 23.6 ±0.2 49.9 ±0.3 MyDay 55.8 24.3 ± 0.3 43.5 ±0.6 clariti 58.4 27.4 ±0.4 46.9 ±0.8 Dailies Total 1 33.2 18.4 ±0.1 55.3 ±0.4 Oasys Max 37.8 17.5 ±0.2 46.2 ±0.6

[0150] The water content of the lens of Example 1 at 97.5% RH was found to be comparable to that of a commercially available clariti™ lens, which has a higher maximum EWC when measured using the ISO method. Furthermore, the lens of Example 1 was found to retain a high proportion of the maximum water content, a proportion similar to that of commercially available Dailies Total 1™ lenses which have a surface coating.

[0151] Although the disclosure herein refers to certain illustrated examples, it is to be understood that these examples are presented by way of example and not by way of limitation. The intent of the foregoing detailed description, although discussing exemplary examples, is to be construed to cover all modifications, alternatives, and equivalents of the examples as may fall within the spirit and scope of the invention as defined by the additional disclosure.

[0152] A number of publications and patents have been cited hereinabove. Each of the cited publications and patents are hereby incorporated by reference in their entireties.

Claims

1. A silicone hydrogel contact lens formulation, comprising:(i) a silicone component;(ii) a silicone-free component; and(iii) a UV blocker, whereinthe silicone component comprises:(a) a compound of Formula 1CH3 . CMj CH3S iQ ""F SsO 4™™" OC jsA™ 0<kl?CH? ' I 1s 0■ 'nwherein Ri is selected from either hydrogen or a methyl group; R2 is selected from either hydrogen or a C1-4 hydrocarbon group; m represents an integer of from 0 to 10; n represents an integer of from 4 to 100; a and b represent integers of 1 or more; a+b from 20 to 500; b / (a+b) is from 0.01 to 0.22, and the configuration of siloxane units includes a random configuration; and(b) a compound of Formula 2wherein n is 10 to 25, and the compound of Formula 1 and the compound of Formula 2 are present in the formulation at a ratio from 50:50 to 77:23 and in a combined amount of from 45 to 55 weight percent;the silicone-free component comprises an N-vinyl amide component (c); and a methacrylate component (d), whereinthe N-vinyl amide component (c) comprises N-vinyl N-methyl acetamide (VMA); andthe methacrylate component (d) comprises hydroxybutyl methacrylate (HOB) and isobornyl methacrylate (IBM), wherein the hydroxybutyl methacrylate and isobomylmethacrylate are present in the formulation in an amount of from 8 to 12 weight percent and the total amount of IBM is less than 5 weight percent;the UV blocker comprises: a first high energy visible light (HEVL) absorber comprising a benzotriazole moiety, a second different high energy visible light (HEVL) absorber comprising a benzotriazole moiety, wherein the HEVL absorbers are present in an amount of from 0.8 to 2.7 weight percent.

2. The formulation of claim 1, wherein the total amount of the compound of Formula 2, VMA and HOB is greater than 28 weight percent.

3. The formulation of claim 1 or claim 2, further comprising at least one of: a polymerizable UV absorbing agent comprising a benzophenone moiety, a photoinitiator; a thermal initiator; a crosslinking monomer; and a tinting agent.

4. The formulation of any preceding claim wherein N-vinyl amide component is present in an amount of from 33 to 39 weight percent.

5. The formulation of any one of the preceding claims, wherein the ratio of HOB to IBM is 85:15 to 90:10.

6. The formulation of any preceding claim wherein the ratio of the compound of Formula 1 to the compound of Formula 2 is 55:45 to 75:25.

7. The formulation of any preceding claim wherein the first and second HEVL absorbers are each of formula (1):HO R6R7 (1),wherein:R1 is a halogen, OH, C1-12 alkyloxy, -A-R9-Y, optionally substituted C1-12 alkyl, optionally substituted phenoxy, or optionally substituted napthyloxy, where the optional substituents are halogen, C1-6 alkyl, C1-6 alkoxy, OH, -(CH2CH2O)nH, -(CH2CH2O)nCH2CH3, -(CH2CH(CH3)O)nH or -(CH2CH(CH3)O)nCH2CH2(CH3);one of R6 and R7 is H or C1-12 alkyl optionally substituted with halogen; andthe other of R6 and R7 is:R2 is a bond, C1-12 alkylene optionally substituted with -OH and / or interrupted by an ester group, (CH2CH2O)n or (CH2CH(CH3)O)n;R3 is a bond, C(O), C(O)CjH2j, C1-6 alkylene, phenyl or C1-6 alkylphenyl;X is a bond, O, NR4, S or (Si(CH3)2O)mSi(CH3)2;each R4 is independently H or methyl;R5 is H, C1-6 alkyl or phenyl;m is 0-9;n is 2-10;j is 1-6;A is -S- or -SO2-;R8 is H, C1-12 alkyl, Ce-is arylalkyl or -R9-Z;each R9 is independently C1-12 alkylene optionally substituted with -OH and / or interrupted by an ester group,each of Y and Z respectively is -OH, -OC(O)R10, -NH2, -NC(O)R10, -NCO, -CO2H, -CO2R10,0 0A   A---N                    ,O Y  Y0 or 0 ;each R10 is independently C1-10 alkyl or C3-io alkenyl;R11 is C3-io cycloalkenylene; andR12 is Ci-io alkylene or 1,2-phenylene.

8. The formulation of any preceding claim, wherein: the first HEVL absorber is 2-[2'-hydroxy-3'-tert-butyl-5’-(3”-methacryloyloxypropoxy)phenyl]-5-chloro-2J / -benzotri azole (UV28).

9. The formulation of any preceding claim, wherein the second HEVL absorber is selected from: 2-(1, l-dimethylethyl)-4-[3-[(4-ethenyl phenyl) methoxy]propoxy]-6-(5-methoxy-2J / -benzotriazol-2-yl)-phenol (UV1), 2-(5-chloro-27 / -benzotri azol-2-yl )-6-(1,1-dimethylethyl)-4-ethenyl-phenol (UV5 / UVAM), 2-[2'-hydroxy-3'- / c / 7-butyl-5’-(3”-methacryloyloxypropoxy)phenyl]-5-methoxy-2J / -benzotriazole (UV13), 2-3'- / c77-butyl-2'-hydroxy-5'-(3"-dimethylvinylsilylpropoxy)-2'-hydroxy-phenyl)-5-methoxybenzotri azole (UV15), especially 2-[2'-hydroxy-3'-terLbutyl-5’-(3”-methacryloyloxypropoxy)phenyl]-5-methoxy-27 / -benzotri azole (UV13).

10. The formulation of any one of claims 1 to 7, wherein the first HEVL absorber is present in an amount of from 0.3 to 0.9 weight percent, preferably from 0.4 to 0.7 weight percent; and the second HEVL absorber is present in an amount of from 0.5 to 2.2 weight percent, preferably from 0.7 to 1.6 weight percent.

11. The formulation of claim 1, wherein:the silicone component consists essentially of Formula 1, Formula 2 and Formula 3:CH3 CH3 R3 1^R1—Si---(OSi)^—CHjCHCILOfCILCI-MCH3 ch3wherein m represents an integer of from 3 to 12, n represents an integer from 1 to 10, R1 is selected from an alkyl group having from 1 to 4 carbon atoms, and each of R2 and R3 of Formula 3 is independently selected from a hydrogen atom or a methyl group, 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-vinyl amide 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; andthe first HEVL absorber is 2-[2'-hydroxy-3'-te / 7-butyl-5’-(3”-methacryloyloxypropoxy)phenyl]-5-chloro-2Z / -benzotriazole (UV28), the second HEVL absorber is 2-[2'-hydroxy-3'- / c / 7-butyl-5’-(3”-methacryloyloxypropoxy)phenyl]-5-methoxy-27 / -benzotriazole (UV13), wherein the first HEVL absorber is present in an amount of from 0.3 to 0.9 weight percent and the second HEVL absorber is present in an amount of from 0.5 to 2.2 weight percent.

12. The formulation of any preceding claim further comprising chain transfer agent.

13. The formulation of claim 12 comprising from 0.3 to 0.9 weight percent of a C3-C20unsaturated alcohol chain transfer agent, for example, allyloxy ethanol.

14. A silicone hydrogel contact lens comprising the polymerized reaction product of the formulation of any preceding claim.

15. The silicone hydrogel contact lens of claim 14, which has a tensile strength of from 0.4 MPa to 1 MPa.

16. The silicone hydrogel contact lens of claim 14 or claim 15, which has a sessile drop contact angle less than 30 degrees.

17. The silicone hydrogel contact lens of any one of claims 11-16, which has an equilibrium water content from 45 weight percent to 55 weight percent.

18. The silicone hydrogel contact lens of any one of claims 11-19, which has an oxygen permeability from 110-140 barrers.

19. The silicone hydrogel contact lens of any one of claims 11-18, which has a Young’s modulus from 0.3 MPa to 1.1 MPa.

20. The silicone hydrogel contact lens of any one of claims 14-19, which has a diameter of from 14.0 to 14.4 mm.

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