Tinted silicone hydrogel contact lens formulations and contact lenses

Abstract

Silicone hydrogel contact lens formulations comprise a silicone component and a silicone-free component. The silicone component includes compounds represented by Formula 1 and Formula 2 (see claim 1),

Description

FIELD

[001] The present invention relates to a silicone hydrogel contact lens formulation that contains copper phthalocyanine pigment particles and silicone hydrogel contact lenses comprising the reaction product of the contact lens formulation. 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] Silicone hydrogel contact lenses may include a visibility handling tint or tinting agent that allows a lens wearer to visibly see the contact lens while it is immersed in a liquid solution, such as a contact lens packaging solution or a lens care solution for cleaning the contact lenses. The visibility tinting agent provides enough colour to visualize the lens in the solution without negatively impacting light transmission through the lens (e.g., the visible light transmission through the tinted lens is typically greater than 90%). Silicone hydrogel contact lenses may include a visibility tinting agent that is a reactive dye that reacts with the chemical monomers in the silicone hydrogel formulation, or that includes pigment particles that are immobilized within the contact lens.

[004] Although pigment particles may be used to provide a visible tint to a silicone hydrogel contact lens, pigment particles are usually less preferred than reactive dyes as they are more difficult to work with from a manufacturing perspective. For example, particle size is important, and if the particles are too large, the particles can appear as specks in the final contact lens making the contact lens less desirable compared to a lens that is uniformly tinted. In addition, pigment particles are prone to settling when present in liquid silicone hydrogel contact lens formulations, especially the longer the formulations are stored for use prior to use in a manufacturing line.

[005] In view of the above noted problems with pigment particles, there remains a need for a silicone hydrogel contact lens formulation containing pigment particles as a visibility tinting agent that can be practically used in a commercial setting, and silicone hydrogel contact lenses obtained from the formulation that are ophthalmically acceptable and cosmetically acceptable. SUMMARY

[006] The present invention addresses this ongoing need. It has been discovered that in a particular silicone hydrogel contact lens formulation, as described herein, certain pigment particles can be included, and the formulation can be used on automated manufacturing lines to produce millions of lenses per year to make ophthalmically and cosmetically acceptable silicone hydrogel contact lenses. The disclosure herein describes this invention in more detail.

[007] The applicant has identified that a suitable silicone hydrogel contact lens formulation containing pigment particles can be formed using a reaction mixture comprising a silicone component and a silicone-free component when the viscosity of the contact lens formulation is within a range of values, as described herein. With the present silicone hydrogel contact lens formulation, not only is it possible to manufacture ophthalmically acceptable silicone hydrogel contact lenses in large volumes without substantial adverse technical problems like problems with phase separation of the formulation, problems with bubble formation in the dispensing system, and the like, but it is also possible to produce large volumes of lenses in which the pigment particles remain suspended in the formulation and do not significantly agglomerate and / or settle in the formulation.

[008] The present silicone hydrogel contact lens formulation comprises a silicone component and a silicone-free component. The silicone component comprises two compounds, a bifunctional siloxane compound of Formula 1: cf3 ,.o / ....-.. y j r v ap j Q ; >j [ f i 9 J .X ..0..., X .---. -Si.....O-4sio4-4-SiO-i- / -Sio4--six ■ - o ...--. A .-. 0, A - r ' NO-':   ' I h' ; V I i         0 N' ' F ' O H o

[009] that has a molecular weight from 12,000 daltons (Da) to 20,000 Da, wherein h represents an integer from 4 to 8; m represents an integer of from 7 to 13; n represents an integer of from 110 to 190; p represents an integer from 6 to 8, and the configuration of siloxane units includes a random configuration; and

[010] a compound of Formula 2: [Oil] where n is an integer from 10 to 25.

[012] In addition, the present silicone hydrogel formulation comprises a tint dispersion. The tint dispersion comprises copper phthalocyanine pigment particles dispersed within a composition of the bifunctional siloxane compound of Formula 1. Therefore, it can be understood that the tint dispersion is a portion of the silicone component of the present formulation. The presence of the copper phthalocyanine pigment particles provides an acceptable blue visibility tint to the silicone hydrogel contact lens formulation and the silicone hydrogel contact lenses produced therefrom. In addition, the presence of the tint dispersion in the formulation, as described herein, provides reduced agglomeration and settling of the pigment particles compared to formulations in which the pigment particles are added directly to the formulation or lens-forming composition.

[013] The silicone-free component of the present silicone hydrogel contact lens formulation comprises N-vinyl pyrrolidone (NVP), N-vinyl N-methyl acetamide (VMA); hydroxybutyl methacrylate (HOB) and isobornyl methacrylate (IBM).

[014] With the combination of ingredients of the silicone component and the silicone-free component, it has been realized that silicone hydrogel contact lenses with desirable properties, such as oxygen permeability, equilibrium water content, lens surface wettability, dimensional stability, and handling can be achieved.

[015] The tint dispersion of the present silicone hydrogel contact lens formulation preferably has an ultraviolet-visible (UV-Vis) absorbance profile characterized by two peaks, one at 638 nm and one at 722 nm. The UV-Vis absorbance value of the peak at 722 nm is greater than the peak at 638 nm. The UV-Vis absorbance profile of the tint dispersion used in the present contact lens formulation is characterized as having a UV-Vis absorbance ratio from 1.05 to 1.45. Preferably, the UV-Vis absorbance ratio is from 1.1 to 1.3.

[016] It has been observed that when such tint dispersions are included in the present silicone hydrogel contact lens formulation, the colour consistency of the visibility tinting agent in the silicone hydrogel contact lenses is maintained across batches of contact lenses, and it is possible to avoid producing silicone hydrogel contact lenses that have to be rejected and destroyed because they do not pass quality control metrics.

[017] In the present silicone hydrogel contact lens formulation, it has been discovered that when the tint dispersion contains the copper phthalocyanine pigment particles at a concentration from 2.0% to 5.0% (wt / wt), that a desirable amount of tinting can be provided to the silicone hydrogel contact lenses obtained therefrom. In preferred embodiments, the concentration of the copper phthalocyanine pigment particles in the tint dispersion is from 3.0% to 3.5% (wt / wt).

[018] Unlike some other silicone hydrogel contact lenses that utilize pigment particles, the present silicone hydrogel contact lens formulation is free of an alcohol diluent. In addition, the present silicone hydrogel contact lens formulation preferably has a viscosity of from 35.0 to 45.0 mPa s measured at a shear rate of 10 reciprocal seconds (1 / s) at a temperature of 25 degrees Celsius. As indicated above, not only can this silicone hydrogel contact lens formulation with the stated range of viscosity be used in a high volume manufacturing environment, it can also be used to produce tinted silicone hydrogel contact lenses that are free of pigment particle agglomerations that would render the contact lenses to be cosmetically unacceptable.

[019] Preferably the formulation further comprises a photoinitiator, and a cross-linking monomer.

[020] In certain embodiments of the present silicone hydrogel contact lens formulation, the copper phthalocyanine pigment particles in the tint dispersion have a maximum dimension no greater than 1 micrometer. The maximum dimension could be understood to be a diameter of the particle if it was perfectly round; however, it will be understood that such pigment particles can be milled to a desired size and so the shape of the particles may not be perfectly spherical, and so the actual diameter of the particle may vary depending on where it is measured. Thus, it can be understood that the copper phthalocyanine pigment particles may have maximum dimension (e.g., a diameter), and the maximum dimension is greater than 0 micrometers and less than or equal to 1 micrometer. For example, the copper phthalocyanine pigment particles may have an average maximum dimension from about 500 nanometers to 1 micrometer. In some embodiments, the copper phthalocyanine pigment particles of the tint dispersion may have a particle size greater than 0 micrometers and less than 1 micrometer. To obtain copper phthalocyanine pigment particles with the desired maximum dimensions, it is possible to pass the tint dispersion containing the pigment particles of varying sizes through a filter having a maximum pore size. For example, the tint dispersion can be directed through a filter having a pore size, or an average pore size, of 1 micrometer or less. Typically, the pore size is determined by the manufacturer of the filters.

[021] The present disclosure also describes silicone hydrogel contact lenses comprising the polymerized reaction product of the formulation of any preceding embodiment.

[022] In addition, unlike other silicone hydrogel contact lens formulations that utilize pigment particles, the present silicone hydrogel contact lens formulation is free of the small molecular weight siloxane, TRIS. By avoiding the use of alcohol diluents and by using the siloxane compound of Formula 1, it is possible to achieve the desired viscosity range of the present contact lens formulation and the benefits provided therefrom.

[023] The silicone hydrogel contact lenses 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.

[024] The silicone hydrogel contact lenses can have a static sessile drop contact angle less than 40 degrees, more preferably less than 30 degrees.

[025] The silicone hydrogel contact lenses can have an equilibrium water content from 45 to 55 wt%, preferably from 45% to 50%.

[026] The silicone hydrogel contact lenses can have an oxygen permeability of greater than 100 barrers, preferably 100 to 160 barrers.

[027] The silicone hydrogel contact lenses 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 1.1 MPa.

[028] 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. BRIEF DESCRIPTION OF DRAWINGS

[029] FIG. 1 illustrates a UV-Vis absorbance profile of a first lot of a tint dispersion of the present silicone hydrogel contact lens formulation; and

[030] FIG. 2 illustrates a UV-VIS absorbance profile of a second lot of a tint dispersion of the present silicone hydrogel contact lens formulation. DETAILED DESCRIPTION

[031] The present invention relates to a silicone hydrogel contact lens formulation and to silicone hydrogel contact lenses produced from the formulation.

[032] 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.

[033] 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.

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

[035] 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.

[036] 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.

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

[038] 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

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

[040] “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.

[041] 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.

[042] In the case of polyorganosiloxane prepolymers, and other polydisperse monomers, the term “molecular weight”, as used herein, refers to the 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.

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

[044] 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.

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

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

[047] The bi-functional methacrylate-containing siloxane monomer is represented by Formula I: cf3 ,.o / j r v / p i U , vi , , f -     §                       ° Si.....O + SiO+                                       ..---< ..-. ..O^. .. 1 "I h ' ' ’nr I h I ° N ' f H O

[048] The compound of Formula 1 has a molecular weight from 12,000 daltons (Da) to 20,000 Da, wherein h represents an integer from 4 to 8; m represents an integer of from 7 to 13; n represents an integer of from 110 to 190; p represents an integer from 6 to 8, and the configuration of siloxane units includes a random configuration.

[049] Preferably, the bi-functional methacrylate-containing siloxane monomer has a CAS registry number of 697234-74-5.

[050] The mono-functional methacrylate-containing siloxane monomer is represented by Formula 2:

[051] where n is an integer from about 10 to 25, preferably from 13 to 18.

[052] The mono-functional methacrylate-containing siloxane monomer of Formula 2 has 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 a further specific example, the mono-functional methacrylate-containing siloxane monomer may have an average molecular weight Mn of from 1,000 to 1,800 Da.

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

[054] In some embodiments, the weight percent of the silicone component is greater than 45%. In some embodiments, the weight percent of the silicone component can be from 45% to 55%. For example, the silicone component can be present in the formulation from 47% (wt / wt) to 53% (wt / wt). In order to achieve the stated viscosity range, it is preferred that the majority of the silicone component is composed of the compound of Formula 1. For example, the compound of Formula 1 can be present in the silicone component at a weight ratio of approximately 4:1 compared to the compound of Formula 2. For example, the compound of Formula 1 could be present in the formulation at an amount of about 40% (wt / wt) and the compound of Formula 2 could be present in the formulation at an amount of about 10% (wt / wt). In this example, the silicone component in the formulation would make up 50% of the formulation and the weight ratio of the amount of the compound of Formula 1 to the amount of the compound of Formula 2 would be 4:1.

[055] 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.

[056] The silicone-free component of the present silicone hydrogel contact lens formulation comprises N-vinyl pyrrolidone (NVP) [CAS# 88-12-0], N-vinyl N-methyl acetamide (VMA) [CAS# 3195-78-6]; hydroxybutyl methacrylate (HOB) [CAS# 29008-35-3] and isobornyl methacrylate (IBM) [CAS# 7534-94-3],

[057] The total amount of NVP and VMA in the formulation can be from 35% to 40% (wt / wt). The total amount of HOB and IBM can be from 10% to 20% (wt / wt). For example, the ratio of NVP to VMA may be 2:1 to 4:1 and the ratio of HOB to IBM may be from 1.5:1 to 2.5:1. In certain embodiments, the amount of NVP to the amount of VMA can be at a weight ratio of about 3:1. For example, the formulation may have NVP in an amount of 30% and may have VMA in an amount of 10%. Similarly, in certain embodiments, the amount of HOB to the amount of IBM can be at a weight ratio of approximately 2:1. For example, the formulation may have HOB in an amount of 10% and may have IBM in an amount of 5.9%. In a preferred embodiment, the formulation comprises NVP and VMA at a weight ratio of about 3:1 and HOB and IBM at a weight ratio of about 2:1.

[058] The present silicone hydrogel contact lens formulation also comprises a tint dispersion. The tint dispersion is a liquid composition comprising copper phthalocyanine pigment particles [CAS # 147-14-8] dispersed within the bifunctional siloxane compound of Formula 1.

[059] It has been found that cosmetically acceptable contact lenses can be made from such contact lens formulations when the tint dispersion has a UV-Vis absorbance profile as described herein. The UV-Vis absorbance of the tint dispersion is determined by diluting a stock volume of the tint dispersion in an organic solvent, such as 2-propanol to form a dilute tint dispersion. For example, the tint dispersion can be diluted at a ratio from 1:2 to 1:100 to form a dilute tint dispersion having a peak absorbance value no greater than 1. A volume of the dilute tint dispersion is placed in a quartz cell for testing in a spectrophotometer. The absorbance of the sample can be measured over a range from 350 nm to 850 nm, and then the absorbance values are determined specifically at 638 nm and at 722 nm. An example of a spectrophotometer that can be used to determine these absorbance values is the Cary 60 UV-Vis Spectrophotometer (Agilent Technologies, Santa Clara, CA, USA). Additional details of using a spectrophotometer to determine UV-Vis absorbance of samples are routine for persons skilled in the art.

[060] In more detail, the UV-Vis absorbance profile of the dilute tint dispersion is characterized by two Visible (Vis) absorbance peaks. One peak (Pl) is at the wavelength of 638 nm, and the second peak (P2) is at the wavelength of 722 nm. For example, FIG. 1 and FIG. 2 illustrate two different UV-Vis absorbance profiles of the dilute tint dispersion described herein (each profile is for a different lot of the tint dispersion). The UV-Vis absorbance of the dilute tint dispersion is greater at the second peak relative to the first peak such that P2>P1, as shown in FIG. 1 and FIG. 2. The relationship of P2 to Pl can be characterized as a ratio of the P2 UV-Vis absorbance value (P2AV) to the Pl UV-Vis absorbance value (Pl AV), such as shown in the following equation: R=P2AV / P1 AV. The present silicone hydrogel contact lens formulation comprises a tint dispersion that has a UV-Vis absorbance ratio from 1.05 to 1.45. As one example, if the P2AV is 0.816 and the P1AV is 0.667, the UV-Vis absorbance ratio is 1.22. Similarly, if the P2AV is 0.69 and the Pl AV is 0.57, the UV-Vis absorbance ratio is 1.21. As another example, if the P2AV is 0.69 and the Pl AV is 0.51, the UV-Vis absorbance ratio is 1.35. As another example, if the P2AV is 0.62 and the Pl AV is 0.57, the UV-Vis absorbance ratio is 1.09.

[061] The tint dispersion can be characterized as having a concentration of copper phthalocyanine pigment particles from 2.0% to 5.0% (wt / wt), prior to dilution. In preferred embodiments, the copper phthalocyanine pigment particles in the tint dispersion are present at a concentration from 3.0% to 3.5% (wt / wt). Compared to formulations in which pigment particles are added directly to the lens formulation composition, it is observed that with the presently disclosed silicone hydrogel contact lens formulation containing the tint dispersion that the tinting agent is more uniformly distributed in the liquid formulation. In contrast, formulations which have pigment particles added directly to the lens formulation composition exhibit pigment particles that agglomerate and settle to the bottom of the formulation composition and are not uniformly distributed. Thus, it can be understood that the present contact lens formulation differs from formulations with pigment particles added directly to the formulation composition at least because the distribution of the pigment particles is different.

[062] As stated herein, the present silicone hydrogel contact lens formulations are free of an alcohol diluent, such as ethanol, isopropanol, propanol, and the like. With the combination of the various compounds described herein, the silicone hydrogel contact lens formulation has a viscosity from 35.0 to 45.0 mPa s measured at a shear rate of 10 reciprocal seconds (1 / s) at a temperature of 25 degrees Celsius. The viscosity is measured using a rheometer, such as a MCR301 rheometer (Anton Paar GmbH, Austria) using a CP-50-1 cone plate and Rheoplus software and the accompanying operating instructions. Not only is it possible to produce silicone hydrogel contact lenses containing the copper phthalocyanine tint particles without the tint particles substantially agglomerating, but it has been demonstrated that the formulation with the claimed viscosity values can be used in a high volume manufacturing environment. Other silicone hydrogel contact lens formulations that do not include the compound of Formula 1 or the compound of Formula 2, or both, have viscosities that are much less viscous, for example, they may have viscosities that are about 10% of the viscosity of the present contact lens formulation. As understood by one skilled in the art, formulations with lower viscosities are expected to be more manufacturing friendly since the formulations can pass through and be dispensed from tubing into contact lens molds with less effort and associated problems.

[063] Typically, the formulation further comprises one or more additional components which are common in contact lens formulations. For example, in preferred embodiments, the formulation further comprises a photoinitiator, and a cross-linking monomer or cross-linking agent.

[064] 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 crosslinking agent can react with functional groups on two or more polymer chains so as to bridge one polymer to another. TAIC is particularly preferred as the cross-linker in the formulations of the present invention. The cross-linking monomer or agent is preferably used in an amount of from 0.03 to 0.2 weight percent of the contact lens formulation.

[065] As discussed herein, the copper phthalocyanine pigment particles are desirably small so as to impart a blue colour to the contact lens. The particles are milled down to a desirable size, and the particles can then be passed through one or more filters to further isolate pigment particles of different sizes. It can be understood that the copper phthalocyanine pigment particles of the tint dispersion have a maximum dimension that is no greater than 1 micrometer. As explained herein, this maximum dimension is analogous to a diameter of a spherical object, and it refers to the largest cross-sectional distance from one surface of the particle to an opposing surface of the particle. It can be understood that there will be many pigment particles in the tint dispersion, so it can be understood that the maximum dimension represents an average of the variously sized pigment particles. As stated herein, to achieve a tint dispersion of pigment particles with a maximum dimension no greater than 1 micrometer, the tint dispersion can be directed through a filter having a labeled pore size of 1 micrometer.

[066] The present silicone hydrogel contact lens formulation can be made by weighing each of the compounds of the silicone component (i.e., the compound of Formula 1 and the compound of Formula 2) and the silicone-free component and placing the compounds in a container. The tint dispersion containing the copper phthalocyanine pigment particles and the compound of Formula 1 can then be added to the container containing the other ingredients of the formulation. In some embodiments, a volume of the tint dispersion is added to the formulation in an amount of from 0.20% to 0.30% of the amount of the compound of Formula 1 present in the formulation. In other embodiments, a volume of the tint dispersion is added to the formulation in an amount of from 0.15% to 0.30% of the amount of the silicone component in the formulation. By employing the present tint dispersions in the silicone hydrogel contact lens formulations, it is possible to achieve a desired tinted contact lens using low amounts of the copper phthalocyanine pigment particles. For example, in some embodiments, the amount of the pigment particles in the formulation may range from 0.005% to 0.013% (wt / wt) of the amount of the compound of Formula 1. In some other embodiments, the amount of the pigment particles in the formulation may range from 0.005% to 0.01% (wt / wt) of the amount of the silicone component. In further embodiments, an amount of the tint dispersion is added to the formulation to achieve a concentration of copper phthalocyanine pigment particles in the formulation from 0.002% to 0.005% (wt / wt). The ingredients of the formulation can be mixed until it appears that solid materials are dissolved, such as with using a magnetic stir bar. The stirred formulation can then be passed through a filter into another container for use on a manufacturing line or for storage.

[067] Contact lenses can be made from the silicone hydrogel contact lens formulation are preferably made using a cast molding process, as understood by persons skilled in the art. Cast molding is desirable since it can be effectively used to produce many contact lenses in a high volume automated manufacturing environment.

[068] In a specific example, contact lens formulation is cast molded between molds formed of a thermoplastic polymer. The thermoplastic polymer can be a non-polar material, such as polypropylene, or the thermoplastic polymer can be a polar mold material, such as ethylene vinyl alcohol. 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 contact lens formulation sufficient to form a single polymeric lens body. A second mold member defining the back (i.e. eyecontacting) 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 contact lens formulation therebetween.

[069] The contact lens formulation 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. In the case of UV-curing, also referred to as photopolymerization, the contact lens formulation typically comprises a photoinitiator such as benzoin methyl ether, 1-hydroxycyclohexylphenyl ketone, Darocur or Irgacur (available from Ciba Specialty Chemicals). As stated herein, the present silicone hydrogel contact lens formulation is preferably UV cured, and thus it includes a photoinitiator. Exemplary thermal initiators include 2,2Z -azobis(2,4-dimethylpentanenitrile) (VAZO-52), 2,2Z -Azobis(2-methylpropanenitrile) (VAZO-64), and l,lz -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.

[070] At the completion of curing, the polymerized formulation 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. The two mold members can be split apart using a wedge device. In some methods, the mold assembly is immersed in water prior to being split by the wedge device. Preferably, the polymeric lens body remains on the female mold half. The polymeric lens body can be delensed by soaking the female mold half with the polymeric lens body in a liquid, such as water. The water may optionally be heated (e g. up to about 100° C).

[071] After delensmg, 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.

[072] After washing, the hydrated polymeric lens body is typically placed into a blister package. 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.

[073] The present invention also includes a silicone hydrogel contact lens that comprises the polymerized reaction product of the presently disclosed silicone hydrogel contact lens formulation. The present silicone hydrogel 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.

[074] In any of the below-described examples, the contact lens may have a contact angle of less than about 40°, or 35°, 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 wide 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.

[075] The present silicone hydrogel contact lenses have an oxygen permeability from 100 barrers to 160 barrers. Preferably, the oxygen permeability is from 120 barrers to 140 barrers. For oxygen permeability, the Dk values can be determined using a Rehder 201T Oxygen Permometer / polarographic cell following the polarographic method described in ISO 18369-4:2017 section 4.4.3.

[076] The present silicone hydrogel contact lens may have a Young’s modulus (i.e. tensile modulus) of from 0.3 MPa to 1.2 MPa. In preferred embodiments, the contact lens has a Young's modulus from 0.5 MPa to 1.1 MPa.

[077] The contact lenses have a tensile strength of at least 0.4 MPa. In preferred embodiments, the present silicone hydrogel 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.

[078] The modulus and tensile strength values of the present contact lenses can be 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 can be determined inside a chamber having a relative humidity of least 70%. A lens is 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 is cut using the cutting die. The thickness of the strip is determined using a calibrated gauge (Rehder electronic thickness gauge, Rehder Development Company, Castro Valley, Calif., USA). Using tweezers, the strip is loaded into the grips with 1200 grit sandpaper adhered to each grip surface 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) is run, and the results are recorded.

[079] The present silicone hydrogel contact lens may have an equilibrium water content (EWC) of at least about 40-60 wt%. Preferably, the silicone hydrogel contact lens has an EWC from 45 to 55 wt%. To measure EWC, excess surface water is wiped off the lens and the lens is weighed to obtain the hydrated weight. The lens is dried in an oven at 105° C, and weighed. The weight difference is determined by subtracting the weight of the dry lens from the weight of the hydrated lens. The wt. % EWC of the lens is = (weight difference / hydrated weight) X 100. 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%.

[080] The present silicone hydrogel contact lenses may have a chord diameter from 13.5 to 15.5 mm and a base curve from 7.5 to 9.5 mm. In preferred embodiments, the silicone hydrogel contact lenses have a diameter (a chord diameter) from 13.8 mm to 14.2 mm and a base curve from 8.5 mm to 8.7 mm.

[081] In view of the disclosure herein, it can be appreciated that desirable silicone hydrogel contact lenses having a blue visibility handling tint have been created. The contact lenses are transparent, such as by providing a light transmittance greater than 97% measured at 590 nm, but also provide enough colour to visualize in a liquid composition, such as a packaging solution or a lens care solution. The formulation used in the production of the silicone hydrogel contact lens is manufacturing-friendly and enables silicone hydrogel contact lenses to be made at high volumes on automated manufacturing lines.

[082] 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.

Claims

1. A silicone hydrogel contact lens formulation, comprising:(i) a silicone component;(ii) a silicone-free component, whereinthe silicone component comprises:(a) a bifunctional siloxane compound of Formula 1?        9           id,. I . , 4'. i            o         ;A .Si—O-48(O-;-4-8iO-+-4-S(C>4—Su ,- -0, .Ar a °' '        ~ f ■ । * 4 A h ;' ■ ' .....tt "" i vi-O n Hohaving a molecular weight from 12,000 daltons (Da) to 20,000 Da, wherein h represents an integer from 4 to 8; m represents an integer of from 7 to 13; n represents an integer of from 110 to 190; p represents an integer from 6 to 8, and the configuration of siloxane units includes a random configuration;(b) a compound of Formula 2wherein n is 10 to 25; and(c) a tint dispersion comprising copper phthalocyanine pigment particles dispersed within a composition of the bifunctional siloxane compound of Formula 1, wherein the copper phthalocyanine pigment particles are present in the tint dispersion in an amount from 2.0% to 5.0% (wt / wt), andthe silicone-free component comprises N-vinyl pyrrolidone (NVP), N-vinyl N-methyl acetamide (VMA); hydroxybutyl methacrylate (HOB) and isobornyl methacrylate (IBM), and wherein the silicone hydrogel contact lens formulation is free of an alcohol diluent.

2. The formulation of claim 1, wherein the tint dispersion has a UV-Vis absorbance ratio from 1.1 to 1.3.

3. The formulation of claim 1 or claim 2, further comprising a photoinitiator, and a crosslinking monomer.

4. The formulation of any preceding claim, wherein the copper phthalocyanine pigment particles of the tint dispersion have a maximum dimension no greater than 1 micrometer.

5. The formulation of any preceding claim which is free of TRIS.

6. The formulation of any preceding claim, wherein the tint dispersion has an ultraviolet-visible (UV-Vis) absorbance profile having a UV-Vis absorbance ratio from 1.05 to 1.45, wherein the UV-Vis absorbance ratio (R) is calculated by the equation: R=P2AV / P1 AV, wherein P2AV is the peak UV-Vis absorbance measured at 722 nm, and Pl AV is the peak UV-Vis absorbance measured at 638 nm.

7. The formulation of any one of claims 1 to 5, wherein the formulation has a viscosity from 35.0 to 45.0 mPa s measured at a shear rate of 10 reciprocal seconds (1 / s) at a temperature of 25 degrees Celsius.

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

9. The silicone hydrogel contact lens of claim 8, which has a tensile strength less than 1 MPa.

10. The silicone hydrogel contact lens of claim 8 or claim 9, which has a static sessile drop contact angle less than 40 degrees.

11. The silicone hydrogel contact lens of any one of claims 8-10, which has an equilibrium water content from 45% to 55%.

12. The silicone hydrogel contact lens of any one of claims 8-11, which has an oxygen permeability from 100-160 barrers.

13. The silicone hydrogel contact lens of any one of claims 8-12, which has a Young's modulus from 0.5 MPa to 1.1 MPa.

14. The silicone hydrogel contact lens of any one of claims 8-13, which as a chord diameter from 13.5 to 15.5 mm and a base curve from 7.5 to 9.5 mm.