Hydrophilic and lubricious contact lens

Abstract

To provide a hydrophilic and lubricious contact lens.SOLUTION: The present invention provides a contact lens comprising a core lens body and a shell layer. The shell layer covers the core lens body and contains a first polymer containing polyvinyl alcohol, and a second polymer containing polyvinylpyrrolidone. The contact lenses provide appropriate surface smoothness because of the shell layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a type of contact lens, and more particularly to a contact lens having hydrophilic and lubricating properties. [Background technology]

[0002] Soft contact lens materials were first introduced in the 1960s, and because the soft materials eliminated the discomfort often associated with wearing conventional hard contact lenses (RGP lenses), users who were not originally adapted to hard contact lenses were able to switch to using soft contact lenses. Therefore, soft contact lenses are the primary choice for contact lens wearers today.

[0003] Although soft contact lenses are more flexible and comfortable than hard contact lenses, many users still report feeling a foreign body in their eyes when wearing soft contact lenses. This causes these users to abandon using contact lenses. The main cause of this problem is the frictional force on the surface of the contact lens. Therefore, when blinking, the lens moves on the eyeball and rubs against the eyeball, causing the user to feel like there is something in their eye. To solve this problem, it is necessary to improve the smoothness of the lens surface.

[0004] Much research has been conducted into obtaining a surface lubrication effect by coating the lens surface with polyacrylic acid (PAA). However, PAA is an anionic polymer, which itself tends to carry a negative charge, and its properties are easily affected by the pH of tears. This can cause irritation when worn. Subsequent research has proposed using a cationic polymer to neutralize the charge of PAA to improve the stability of the above-mentioned technology, but it has been found that this method requires significant process management costs and has the problem of the product not being able to maintain a stable lubrication effect even when worn for long periods of time. Contents of the invention

[0005] In view of the above problems and technological developments, the present invention proposes a method that can effectively improve the surface smoothness of contact lenses, and provides a cost-competitive technical solution that can maintain the effect for a long period of time. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic cross-sectional view of a contact lens according to one embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged schematic view of the circle A in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0007] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Generally, the terms and experimental procedures used herein are well known and widely used in the art. These procedures use conventional methods, such as those provided in the art and various general references. Even when a term is provided in the singular, the inventor also contemplates the plural form of the term. The terms used herein and the experimental procedures described below are well known and widely used in the art. As used throughout this disclosure, unless otherwise explained, the following terms are understood to have the following meanings:

[0008] A dry lens refers to a contact lens that has undergone curing and has not yet undergone hydration during the manufacturing process.

[0009] A wet lens refers to a lens that has completed hydration during the contact lens manufacturing process.

[0010] The lens core body refers to the lens component formed by curing from the contact lens formulation. The lens core body may be a dry lens or a wet lens. Some of the samples listed in this invention do not have a shell layer.

[0011] The shell layer refers to the surface of the lens core body that is formed after the lens core body is formed and then cured through another process, but it does not have the same structure as the original lens core body. Furthermore, the shell layer can stably exist on the surface of the lens core body by forming a stable structure similar to an interpenetrating polymer network structure.

[0012] Interpenetrating polymer networks (IPNs) generally refer to a polymer network containing two or more polymers, at least one of which is crosslinked, and in which at least two or more polymers partially cross-link but do not form covalent bonds with each other. For example, if polymer A itself is a crosslinked polymer network, and polymer B partially cross-links with polymer A but does not form a covalent bond between polymer A and polymer B, polymer A and polymer B are said to form an interpenetrating polymer network. Considering the complexities in the fields of polymers and chemistry, the interpenetrating polymer network structure used in the present invention allows for covalent bonding between different polymers in the formation process and results. For example, the disclosed examples of the present invention do not exclude a small amount (less than 0.1 wt%) of the first polymer being covalently bonded to the polymer in the lens core body. For convenience of expression, the inventors will still refer to the partially cross-linked polymer network formed by the first polymer and the polymer in the lens core body on the surface of the lens core body as an interpenetrating polymer network structure. The polymer structure formed by the entanglement of the first polymer and the second polymer in the outer layer can be said to be a stable structure similar to an interpenetrating polymer network structure. In this polymer structure, no clear crosslinks are observed between the polymer chains of the first polymer itself, and no clear crosslinks are observed between the polymer chains of the second polymer itself. Instead, very strong hydrogen bonds are observed only between the polymer chains of the first polymer and between the polymer chains of the first and second polymers, forming a stable structure similar to an interpenetrating polymer network structure. Therefore, in this invention, in order to stay as close as possible to the general theoretical definition, the network structure formed by the first polymer and the second polymer in the outer layer will not be directly referred to as an interpenetrating polymer network structure.

[0013] A semi-interpenetrating polymer network (Semi-IPN) specifically refers to an interpenetrating polymer network in which at least one polymer is a linear polymer, in a general theoretical definition. The interpenetrating polymer network of the present invention includes a semi-interpenetrating polymer network.

[0014] In a general theoretical definition, a simultaneous interpenetrating polymer network (SIPNs, SINs) specifically refers to an interpenetrating polymer network structure formed when two or more polymer component units undergo their respective polymerization reactions. For example, in the case of an interpenetrating polymer network structure consisting of polymer A and polymer B, polymer A is formed by the polymerization reaction of monomer a, and polymer B is formed by the polymerization reaction of monomer b. If monomer a and monomer b are mixed and then polymerized, the interpenetrating polymer network structure of polymer A and polymer B that is finally formed may be a simultaneous interpenetrating polymer network structure. The interpenetrating polymer network structure of the present invention does not include, for example, a simultaneous interpenetrating polymer network structure.

[0015] The present invention provides a contact lens comprising a core lens body and a shell layer, the shell layer covering the core lens body, the shell layer comprising at least two polymers, a first polymer and a second polymer.

[0016] The first polymer used in the present invention is a polymer containing a polyvinyl alcohol structure. The first polymer may be polyvinyl alcohol, a copolymer of polyvinyl alcohol and polyvinyl acetate (PVA-PVAc copolymer), or a mixture thereof. The first polymer may be crosslinkable or non-crosslinkable. The copolymer of polyvinyl alcohol and polyvinyl acetate may be a block copolymer, an alternative copolymer, a random copolymer, or a graft copolymer. The polyvinyl alcohol may be crosslinkable or non-crosslinkable. The polyvinyl alcohol may be fully hydrolyzed (i.e., fully hydrolyzed polyvinyl alcohol (PVA)) or partially hydrolyzed (i.e., partially hydrolyzed polyvinyl alcohol (PVA)). Partially hydrolyzed polyvinyl alcohol is preferred. In terms of classification, partially hydrolyzed polyvinyl alcohol can also be understood as a type of polyvinyl alcohol-polyvinyl acetate copolymer (PVA-PVAc copolymer). This is because its polymer segment contains both vinyl alcohol and vinyl acetate units. Furthermore, fully hydrolyzed polyvinyl alcohol is polyvinyl alcohol that is 100% vinyl alcohol units. Furthermore, partially hydrolyzed polyvinyl alcohol, for example, a partially hydrolyzed polyvinyl alcohol with a degree of hydrolysis of 80%, contains 80% vinyl alcohol units and 20% unhydrolyzed vinyl acetate units. In the terminology of the present invention, the two terms, partially hydrolyzed polyvinyl alcohol and polyvinyl alcohol-polyvinyl acetate copolymer, can refer to the same object, and the two terms can be used interchangeably.

[0017] In the present invention, partially hydrolyzed polyvinyl alcohol is preferred as the first polymer. The degree of hydrolysis of partially hydrolyzed polyvinyl alcohol is preferably in the range of 70% to 99%, more preferably 80% to 98%, and even more preferably 88% to 95%. In the present invention, an appropriate degree of hydrolysis of polyvinyl alcohol improves the stability of the first polymer in forming an interpenetrating polymer network with the polymer on the surface of the lens core body, while also improving the stability of the first polymer in forming an interpenetrating polymer network with the second polymer in the outer shell layer. The reason why partially hydrolyzed polyvinyl alcohol is more effective than fully hydrolyzed polyvinyl alcohol is that the fully hydrolyzed polyvinyl alcohol has strong intramolecular hydrogen bonds, which makes it difficult for the fully hydrolyzed polyvinyl alcohol to penetrate into the surface structure of the lens core body (polymer) and form an interpenetrating polymer network with the lens core body (polymer). Similarly, the strong intramolecular hydrogen bonds of fully hydrolyzed polyvinyl alcohol make it difficult for the fully hydrolyzed polyvinyl alcohol to form intermolecular hydrogen bonds with the second polymer containing polyvinylpyrrolidone. Therefore, compared to partially hydrolyzed polyvinyl alcohol, fully hydrolyzed polyvinyl alcohol is less likely to form a similar interpenetrating polymer network structure with a second polymer.

[0018] The molecular weight (Mw) of the first polymer is preferably in the range of 5,000 to 300,000 Da, more preferably in the range of 10,000 to 200,000 Da, even more preferably in the range of 15,000 to 150,000 Da, and most preferably in the range of 25,000 to 100,000 Da.

[0019] The second polymer used in the present invention is a polymer containing a polyvinylpyrrolidone structure. The second polymer may be polyvinylpyrrolidone, a copolymer containing polyvinylpyrrolidone, or a mixture thereof. The second polymer may be crosslinkable or non-crosslinkable. The copolymer containing polyvinylpyrrolidone may be a copolymer of vinylpyrrolidone and dimethylaminoethyl methacrylate ((vinylpyrrolidone)-co-(dimethylaminoethylmethacrylate)), and specific examples include Copolymer 845, Copolymer 937, and Copolymer 958 sold by Ashland Inc. The molecular weight of the copolymer of vinylpyrrolidone and dimethylaminoethyl methacrylate is, for example, 100,000 Da or more.

[0020] The molecular weight (Mw) of the second polymer is preferably 8,000 Da or more, more preferably 100,000 Da or more, even more preferably 160,000 Da or more, and most preferably 360,000 Da or more. This molecular weight range of the second polymer allows for the formation of an effective outer shell layer. If the molecular weight of the second polymer is insufficient, it is difficult to form an effective outer shell layer with the first polymer. This is thought to be because, even if a second polymer with a low molecular weight can form a similar interpenetrating polymer network structure with the first polymer, the low molecular weight of the second polymer makes it more likely to move within the structure, resulting in a lack of stability of the outer shell layer.

[0021] At the interface between the lens core body and the outer shell layer, the first polymer and the polymer structure of the lens core body form an interpenetrating polymer network structure. In most regions of the outer shell layer, a stable structure similar to the interpenetrating polymer network structure is formed between the first polymer and the second polymer.

[0022] At the interface between the lens core body and the outer shell layer, the first polymer and the polymer structure of the lens core body form an interpenetrating polymer network structure. In this interpenetrating polymer network structure, some of the first polymers are freely mobile, and stable bonds are formed between other parts of the first polymer, stabilizing the interpenetrating polymer network structure. The formation of these bonds is primarily due to the contact lens sterilization (autoclave) process, where stable hydrogen bonds are formed between polyvinyl alcohols due to high temperature and pressure. Therefore, the part of the outer shell layer in contact with the lens core body is primarily composed of the first polymer, and the part of the outer shell layer away from the lens core body is primarily composed of the second polymer. In most regions of the outer shell layer, a stable structure similar to an interpenetrating polymer network structure is formed between the first polymer and the second polymer. In this structure, some of the first polymers are freely mobile, and some of the second polymers are also freely mobile, and stable bonds are formed between some of the first polymers, stabilizing the similar interpenetrating polymer network structure. The formation of this bond is mainly due to the sterilization process of contact lenses, which generates stable hydrogen bonds between polyvinyl alcohols. At the same time, stable hydrogen bonds can also be formed between polyvinyl alcohols and polyvinylpyrrolidone, which are mainly due to the hydroxyl groups of polyvinyl alcohols and the oxygen atoms of polyvinylpyrrolidone. This makes the overall structure of the outer shell relatively stable, maintaining comfort for the wearer.

[0023] Further, controlling the proportion of vinyl acetate in the first polymer (i.e., the degree of hydrolysis of the partially hydrolyzed polyvinyl alcohol) can significantly affect the formation of the outer shell layer. Because the polyvinyl alcohol structure itself has strong crystallinity, if the first polymer is too crystalline, it will be unable to effectively penetrate the surface structure of the lens core body before forming the outer shell layer, preventing the first polymer from forming a semi-interpenetrating polymer network structure with the surface structure of the lens core body. As a result, a stable interpenetrating polymer network structure cannot be formed during the subsequent sterilization process. Similarly, if the first polymer is too crystalline, the oxygen atoms of the polyvinylpyrrolidone in the second polymer will be less likely to form hydrogen bonds with the hydroxyl groups of the polyvinyl alcohol in the first polymer, resulting in insufficient entanglement between the first and second polymers. This will affect the formation of a similar interpenetrating polymer network structure between the first and second polymers, ultimately affecting the stability of the outer shell layer. In addition, some of the vinyl acetate in the first polymer can react with some of the vinyl alcohol during sterilization, forming an action similar to a cross-linking reaction, which can further stabilize the structure of the outer shell layer and at the same time help the outer shell layer fix and cover the lens core body.

[0024] One important factor in the formation of a stable outer shell layer referred to in the present invention is the ability of the first polymer to form an interpenetrating polymer network structure with the lens core body, and simultaneously the ability of the first polymer to form an interpenetrating polymer network structure with the second polymer. An important factor in forming a stable interpenetrating polymer network structure is the sterilization process. The high temperature and pressure during sterilization create stable hydrogen bonds between the polyvinyl alcohol in the first polymer. At the same time, some of the vinyl acetate in the first polymer can react with some of the vinyl alcohol during sterilization, forming an effect similar to a crosslinking reaction. This converts the semi-interpenetrating polymer network structure originally formed by the surface structure of the first polymer and the lens core body into a more stable interpenetrating polymer network structure. Similarly, the first polymer and the second polymer in the outer shell layer were originally only physically adsorbed or slightly entangled, but the high temperature and pressure during sterilization cause hydrogen bonds and crosslinking reactions to form between the first polymers, and also strengthen the hydrogen bonds between the first polymer and the second polymer, further strengthening the strength of the entanglements. Therefore, the sterilization process not only helps the outer shell layer to stably coat the lens core body, but also helps strengthen the stability of the outer shell layer itself.

[0025] The first polymer used in the present invention may not contain any positively charged polymeric segments (cationic polymeric segments) and may not contain any negatively charged polymeric segments (anionic polymeric segments).

[0026] The first polymer used in the present invention may contain positively charged polymer segments, but the positively charged polymer segments must not inhibit the formation of an interpenetrating polymer network between the first polymer and the lens core body polymer, nor must they inhibit the formation of a stable entanglement between the first polymer and the second polymer. Similarly, the first polymer used in the present invention may contain negatively charged polymer segments, but the negatively charged polymer segments must not inhibit the formation of an interpenetrating polymer network between the first polymer and the lens core body polymer, nor must they inhibit the formation of a stable entanglement between the first polymer and the second polymer.

[0027] The second polymer used in the present invention may not contain any cationic polymeric segments and may not contain any anionic polymeric segments.

[0028] The second polymer used in the present invention may contain positively charged polymer segments, but the positively charged polymer segments must not inhibit the formation of an interpenetrating polymer network between the first polymer and the lens core body polymer, nor must they inhibit the formation of stable entanglements between the second polymer and the first polymer. Similarly, the second polymer used in the present invention may contain negatively charged polymer segments, but the negatively charged polymer segments must not inhibit the formation of an interpenetrating polymer network between the first polymer and the lens core body polymer, nor must they inhibit the formation of stable entanglements between the second polymer and the first polymer.

[0029] For the convenience of the reader, detailed theoretical explanations are provided herein regarding the structural relationship and principle between the first polymer and the lens core body, and the structural relationship and principle between the first polymer and the second polymer, however, the theoretical explanations should not be construed as limiting the scope of the patent right of the present invention.

[0030] As shown in the examples, the lens core body of the contact lens provided by the present invention is primarily composed of HEMA (2-hydroxyethyl methacrylate), i.e., the contact lens may contain 85% or more, 90% or more, or even 95% or more of HEMA. The calculations of composition and percentages described herein do not include diluents. This type of contact lens is commonly called a hydrogel contact lens.

[0031] As shown in the examples, the lens core body of the contact lens provided by the present invention may be a contact lens containing a silicone-containing component. The silicone-containing component may be a silicone monomer or a silicone macromer, and may also contain a silicone crosslinker. This type of contact lens is generally called a silicone hydrogel contact lens.

[0032] Reference will now be made in detail to the embodiments of the present invention, one or more examples of which will be described. Each embodiment is provided for the purpose of illustrating the invention, not for the purpose of limiting the invention. Indeed, it will be apparent to those of ordinary skill in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. For example, features disclosed or described as part of one embodiment may be used with another embodiment to yield a new embodiment. Thus, it is intended that the present invention cover all such modifications and variations, provided they come within the scope of the appended claims and their equivalents. Other objects, features, and directions of the present invention will be disclosed in or become apparent from the following detailed description. Those of ordinary skill in the art will understand that the present discussion is merely a description of exemplary embodiments, and is not intended to limit the broader aspects of the present invention.

[0033] Figure 1 is a cross-sectional schematic diagram of a contact lens in one embodiment of the present invention. Figure 2 is an enlarged schematic diagram of circle A in Figure 1. Referring to Figures 1 and 2, a contact lens 100 in one embodiment of the present invention includes a lens core body 110 and an outer shell layer 120, with the outer shell layer 120 covering the lens core body 110. The outer shell layer 120 includes a first polymer 121 and a second polymer 122, with the first polymer 121 including polyvinyl alcohol and the second polymer 122 including polyvinylpyrrolidone. The first polymer 121 covers the lens core body 110, for example, and the second polymer 122 covers the first polymer 121, for example.

[0034] Lens ingredient abbreviations and compound descriptions: TIFF2025128996000002.tif83160

[0035] Sample 1-1 (EX1-1): A dry lens of Hydrogel-1 was manufactured. The lens ingredients are listed in Table 1. The process from lens formulation to dry lens manufacturing is well known in the art, and mold-based manufacturing methods are available. Contact lens curing can be performed using either light or heat. Light curing was selected for this sample. The dry lens was hydrated in hot water (70±5°C, reverse osmosis water used) for 60 minutes. The remaining monomers, crosslinkers, initiators, and fillers from the curing reaction were then washed away from the dry lens to obtain a wet lens. The resulting wet lens was then immersed in an aqueous solution containing 0.2 g / L of PVA-PVAc copolymer for 120 minutes. The purpose of this immersion process is to allow the PVA-PVAc copolymer to penetrate the surface of the lens core body by mass transfer. The PVA-PVAc copolymer used here is designated PVA-PVAc-1. It has a molecular weight of 31,000 Da and PVA accounts for 88% of the total, i.e., it is a partially hydrolyzed polyvinyl alcohol (PVA) with a degree of hydrolysis of 88%. After completing these steps, the wet lens was removed from the PVA-PVAc copolymer solution and placed in a polypropylene (PP) cup. Buffer-1 was then added dropwise into the PP cup. The buffer level should be higher than the wet lens, ensuring that all of the buffer covers the wet lens. After completion, the aluminum foil and PP cup were sealed using a heat seal and placed in an autoclave for sterilization. The sterilization conditions were to heat the lens to 122°C and maintain the pressure at 122°C and 2 atmospheres for 30 minutes. As a result, a contact lens was obtained in which the lens core had a water content of approximately 38% and was mainly composed of HEMA, and the outer shell was mainly composed of PVA-PVAc copolymer and PVP, with the lens core and PVP bonded together by the PVA-PVAc copolymer.Approximately 12 hours after the wet lenses had been in contact with the buffer solution (including the sterilization process), the aluminum foil was opened, the contact lenses were removed, and the lenses were placed in a standard buffer solution to equilibrate. The buffer solution was changed every hour using 10 ml of standard buffer solution per contact lens, and this process was repeated three times. The surface smoothness of the contact lenses was then evaluated. The blending ratio of Buffer-1 to Standard Buffer is shown in Table 2.

[0036] [Table 1]

[0037] Note: The diluents in Table 1 (including glycerin, 1-hexanol, and DEGBE) are not included in the calculation of the lens's total composition (SUM). They are added to the SUM to make it 100%. For example, the composition of Hydrogel-1 is 98.5g of HEMA, 0.1g of MAA, 1.0g of EGDMA, and 0.4g of Irgracure 819, for a total weight of 100g. In this case, 15.0g of glycerin is added separately as a diluent.

[0038] [Table 2]

[0039] Note: Values ​​in Table 2 are in grams (g). PVP360K is PVP with a molecular weight of 360,000 Da, PVP8K is PVP with a molecular weight of 8,000 Da, PVA-PVAc-1 is a PVA-PVAc copolymer with a molecular weight of 31,000 Da and 88% PVA, PVA-PVAc-2 is a PVA-PVAc copolymer with a molecular weight of 205,000 Da and 88% PVA, and PVA-PVAc-3 is a PVA-PVAc copolymer with a molecular weight of 27,000 Da and 98% PVA.

[0040] Sample 1-2 (EX1-2): This sample was prepared using the same method as Sample 1-1, except that the aluminum foil and PP cup were heat-sealed and then sterilized in an autoclave. Instead, the wet lens was simply immersed in Buffer-1 within the heat-sealed aluminum foil PP cup. Approximately 12 hours after the wet lens began to come into contact with the buffer solution (including the sterilization process), the aluminum foil was opened, the contact lens was removed, and the contact lens was placed in a standard buffer solution to equilibrate. The buffer solution was changed every hour using 10 ml of standard buffer solution per contact lens, and this was repeated three times. The surface smoothness of the contact lens was then measured.

[0041] Sample 2-1 (EX2-1): A dry lens of Hydrogel-2 was manufactured. The lens ingredients are listed in Table 1. The process from lens formulation to dry lens production is well known in the art, and mold-based manufacturing methods are available. Contact lens curing can be performed using either photocuring or heat curing; photocuring was selected for this sample. The dry lens was immersed in a 0.5 wt% aqueous sodium carbonate solution for 20 minutes to rapidly ionize the MAA in the dry lens, expanding the dry lens and improving cleaning efficiency. The dry lens was then hydrated in RO water at room temperature (20-30°C) for 40 minutes to wash away residual monomers, crosslinkers, initiators, and fillers from the curing reaction, yielding a wet lens. The resulting wet lens was then immersed in an aqueous solution containing 0.2 g / L PVA-PVAc copolymer for 120 minutes. The purpose of this immersion process was to penetrate the PVA-PVAc copolymer into the lens core surface by mass transfer. The PVA-PVAc copolymer used here is designated PVA-PVAc-1, and has a molecular weight of 31,000 Da, with PVA accounting for 88% of the total, i.e., a partially hydrolyzed polyvinyl alcohol (PVA) with a degree of hydrolysis of 88%. After completing these steps, the wet lens was removed from the PVA-PVAc copolymer solution and placed in a PP cup. Buffer-1 was then added dropwise into the PP cup. The buffer level should be higher than the wet lens, ensuring that all of the buffer covers the wet lens. After completion, the aluminum foil and PP cup were sealed using a heat seal and placed in an autoclave for sterilization. The sterilization conditions were to heat the lens to 122°C, maintain the pressure at 122°C and 2 atmospheres, and continue for 30 minutes. As a result, a contact lens was obtained in which the lens core body had a water content of approximately 55% and was mainly composed of HEMA, and the outer shell layer was mainly composed of PVA-PVAc copolymer and PVP, and the lens core body and PVP were bonded by the PVA-PVAc copolymer.Approximately 12 hours after the wet lenses had been in contact with the buffer solution (including the sterilization process), the aluminum foil was opened, the contact lenses were removed, and placed in a standard buffer solution to equilibrate. The buffer solution was changed every hour using 10 ml of standard buffer solution per contact lens, and this was repeated three times, after which the smoothness of the contact lens surface was evaluated.

[0042] Sample 2-2 (EX2-2): This sample was prepared using the same method as Sample 2-1, except that the aluminum foil and PP cup were heat-sealed and then sterilized in an autoclave. Instead, the wet lens was simply immersed in Buffer-1 within the heat-sealed aluminum foil PP cup. Approximately 12 hours after the wet lens began to come into contact with the buffer solution (including the sterilization process), the aluminum foil was opened, the contact lens was removed, and the contact lens was placed in a standard buffer solution to equilibrate. The buffer solution was changed every hour using 10 ml of standard buffer solution per contact lens, and this was repeated three times. The surface smoothness of the contact lens was then evaluated.

[0043] Sample 3-1 (EX3-1): Silicone hydrogel dry lenses were manufactured. The lens ingredients are listed in Table 1. The process from lens formulation to dry lens manufacturing is well-known in the art, and mold-based manufacturing methods are available. Contact lens curing can be performed using either light or heat curing; light curing was selected for this sample. First, the dry lenses were immersed in an aqueous solution containing 50 wt% isopropyl alcohol (IPA) for 60 minutes. This allows the dry lenses to expand rapidly and improve cleaning efficiency. Furthermore, IPA's high affinity with the silicone-containing components TRIS and MPDMS ensures thorough cleaning of any remaining TRIS and MPDMS that did not complete the curing reaction, as well as any remaining monomers, crosslinkers, initiators, and fillers. The lenses were then immersed in RO water at room temperature (20-30°C) four times for 30 minutes each, with the water replaced with fresh RO water each time to thoroughly rinse off the IPA. This resulted in wet lenses. The resulting wet lens was immersed in an aqueous solution containing 0.2 g / L of PVA-PVAc copolymer for 120 minutes. The purpose of this immersion process was to allow the PVA-PVAc copolymer to penetrate the lens core surface by mass transfer. The PVA-PVAc copolymer used here was designated PVA-PVAc-1, a partially hydrolyzed polyvinyl alcohol (PVA) with a molecular weight of 31,000 Da and 88% PVA content. After these steps were completed, the wet lens was removed from the PVA-PVAc copolymer solution and placed in a polypropylene (PP) cup. Buffer-1 was then added dropwise to the cup. The buffer level should be higher than the wet lens to ensure that all of the buffer covered the wet lens. After completion, the aluminum foil and the polypropylene (PP) cup were heat-sealed and sterilized in an autoclave. The sterilization conditions are to heat the temperature to 122 degrees Celsius, maintain the temperature at 122 degrees Celsius and 2 atmospheres, and continue this for 30 minutes.This resulted in contact lenses with a silicone hydrogel lens core and a shell composed primarily of PVA-PVAc copolymer and PVP, with the PVA-PVAc copolymer binding the lens core and PVP. Approximately 12 hours after the wet lenses had been in contact with the buffer solution (including the sterilization process), the aluminum foil was removed, the contact lenses were removed, and placed in a standard buffer solution to equilibrate. The buffer solution was changed every hour using 10 ml of standard buffer solution per contact lens, and this process was repeated three times. The surface smoothness of the contact lenses was then evaluated.

[0044] Sample 3-2 (EX3-2): This sample was prepared using the same method as Sample 3-1, except that the aluminum foil and PP cup were heat-sealed and then sterilized in an autoclave. Instead, the wet lens was simply immersed in Buffer-1 within the heat-sealed aluminum foil PP cup. Approximately 12 hours after the wet lens began to come into contact with the buffer solution (including the sterilization process), the aluminum foil was opened, the contact lens was removed, and the contact lens was placed in a standard buffer solution to equilibrate. The buffer solution was changed every hour using 10 ml of standard buffer solution per contact lens, and this was repeated three times. The surface smoothness of the contact lens was then evaluated.

[0045] Sample 4-1 (EX4-1): A dry lens of Hydrogel-2 was manufactured. The lens ingredients are listed in Table 1. The process from lens formulation to dry lens production is well known in the art, and mold-based manufacturing methods are available. Contact lens curing can be performed using either light or heat curing; light curing was selected for this sample. The dry lens was immersed in a 0.5 wt% aqueous sodium carbonate solution for 20 minutes to rapidly ionize the MAA in the dry lens, expanding the dry lens and improving cleaning efficiency. The dry lens was then hydrated in RO water at room temperature (20-30°C) for 40 minutes to wash away residual monomers, crosslinkers, initiators, and fillers from the curing reaction, yielding a wet lens. The resulting wet lens was placed in a PP cup, and Buffer-3 (Buffer-3) was added dropwise into the cup. The buffer level must be higher than the wet lens to ensure that all of the buffer covers the wet lens. After completion, the aluminum foil and PP cup were sealed using a heat seal method and placed in an autoclave for sterilization. Sterilization conditions included heating to 122°C and maintaining the temperature at 122°C and 2 atmospheres for 30 minutes. This resulted in contact lenses with a water content of approximately 55% and a HEMA-based lens core, a PVA-PVAc copolymer- and PVP-based shell, and PVA-PVAc copolymer-based bonding between the lens core and PVP. Approximately 12 hours after the wet lenses were exposed to the buffer solution (including the sterilization process), the aluminum foil was opened, and the contact lenses were removed and placed in a standard buffer solution to equilibrate. The buffer solution was replaced every hour using 10 ml of standard buffer solution per contact lens, and this process was repeated three times. The surface smoothness of the contact lenses was then evaluated. The composition of Buffer-3 is listed in Table 2.

[0046] Sample 4-2 (EX4-2): Dry lenses were manufactured using Hydrogel-2. The lens ingredients are listed in Table 1. The process from lens formulation to dry lens manufacturing is well known in the art, and mold-based manufacturing methods are available. Contact lenses can be cured using either light or heat. Light curing was selected for this sample. The dry lenses were immersed in a 0.5 wt% sodium carbonate solution for 20 minutes to rapidly ionize the MAA in the dry lenses, expanding them and improving cleaning efficiency. The lenses were then hydrated in RO water at room temperature (20-30°C) for 40 minutes to wash away residual monomers, crosslinkers, initiators, and fillers from the curing reaction, yielding wet lenses. The resulting wet lenses were then immersed in a 0.6 g / L PVP solution for 120 minutes. The purpose of this immersion process was to allow the PVP to penetrate the surface of the lens core by mass transfer. The PVP used here is designated PVP360, which has a molecular weight of 360,000 Da. After completing these steps, the wetted lenses were removed from the PVP aqueous solution and placed in a PP cup. Buffer 2 was then added dropwise into the PP cup. The buffer level must be higher than the wetted lens to ensure that all of the buffer covers the wetted lens. After completion, the aluminum foil and PP cup were heat-sealed and placed in an autoclave for sterilization. The sterilization conditions were to heat the contact lens to 122°C and maintain the temperature at 122°C and 2 atmospheres for 30 minutes. Approximately 12 hours after the wetted lens came into contact with the buffer solution (including the sterilization process), the aluminum foil was opened, the contact lenses were removed, and the lenses were placed in a standard buffer solution to equilibrate. The buffer solution was replaced every hour using 10 ml of standard buffer solution per contact lens, and this process was repeated three times. The surface smoothness of the contact lenses was then evaluated. The composition of Buffer-2 is shown in Table 2.

[0047] Sample 5-1 (EX5-1): Prepared using the same method as Sample 4-1, but replacing the PVP in the buffer solution with Copolymer 845. After approximately 12 hours (including the sterilization process) from when the wetted lenses began to contact the buffer solution, the aluminum foil was opened, the contact lenses were removed, and placed in a standard buffer solution to equilibrate. The buffer solution was changed every hour using 10 ml of the standard buffer solution per contact lens, and this was repeated three times, after which the surface smoothness of the contact lenses was evaluated.

[0048] Sample 5-2 (EX5-2): Dry lenses were manufactured using Hydrogel-2. The lens ingredients are listed in Table 1. The process from lens formulation to dry lens production is well known in the art, and mold-based manufacturing methods are available. Contact lenses can be cured using either light or heat. Light curing was selected for this sample. The dry lenses were immersed in a 0.5 wt% aqueous sodium carbonate solution for 20 minutes to rapidly ionize the MAA in the dry lenses, expanding them and improving cleaning efficiency. The lenses were then hydrated in RO water at room temperature (20-30°C) for 40 minutes to wash away residual monomers, crosslinkers, initiators, and fillers from the curing reaction, yielding wet lenses. The resulting wet lenses were placed in a PP cup, and Buffer-2 (Buffer-2) was added dropwise into the cup. The buffer level must be higher than the wet lens to ensure that all of the buffer covers the wet lens. After completion, the aluminum foil and PP cup were sealed using a heat seal and placed in an autoclave for sterilization. The sterilization conditions were to heat the temperature to 122°C, maintain the pressure at 122°C and 2 atmospheres, and continue for 30 minutes. After the sterilization was completed, the aluminum foil was opened, the contact lens was removed, and placed in a new PP cup. Buffer-1 was then dripped into the PP cup. The buffer liquid level should be higher than the wet lens, ensuring that all of the buffer covers the wet lens. After completion, the aluminum foil and PP cup were sealed using a heat seal and placed in an autoclave for a second sterilization. The sterilization conditions were to heat the temperature to 122°C, maintain the pressure at 122°C and 2 atmospheres, and continue for 30 minutes. After completion, the aluminum foil was opened, the contact lenses were removed, and placed in a standard buffer solution to equilibrate. The buffer solution was changed every hour using 10 ml of standard buffer solution per contact lens, and this was repeated three times, after which the smoothness of the contact lens surface was evaluated.

[0049] Sample 6-1 (EX6-1): This sample was prepared using the same method as Sample 4-1, except that Buffer 3 was replaced with Buffer 4. The blending ratio of Buffer 4 is shown in Table 2. After sterilization was completed, approximately 12 hours (including the sterilization process) had passed since the wet lenses began to come into contact with the buffer solution. The aluminum foil was opened, and the contact lenses were removed and placed in a standard buffer solution to equilibrate. The buffer solution was replaced every hour using 10 ml of standard buffer solution per contact lens, and this was repeated three times. The smoothness of the contact lens surfaces was then evaluated.

[0050] Sample 7-1 (EX7-1): This sample was prepared using the same method as Sample 4-1, except that Buffer 3 was replaced with Buffer 5. The blending ratio of Buffer 5 is shown in Table 2. After sterilization was completed, approximately 12 hours (including the sterilization process) had passed since the wet lenses began to come into contact with the buffer solution. The aluminum foil was opened, the contact lenses were removed, and the lenses were placed in a standard buffer solution to equilibrate. The buffer solution was replaced every hour using 10 ml of standard buffer solution per contact lens, and this was repeated three times. The smoothness of the contact lens surfaces was then evaluated.

[0051] Sample 8-1 (EX8-1): This sample was prepared using the same method as Sample 4-1, except that Buffer 3 was replaced with Buffer 6. The blending ratio of Buffer 6 is shown in Table 2. After sterilization was completed, approximately 12 hours (including the sterilization process) had passed since the wet lenses began to come into contact with the buffer solution. The aluminum foil was opened, the contact lenses were removed, and the lenses were placed in a standard buffer solution to equilibrate. The buffer solution was replaced every hour using 10 ml of standard buffer solution per contact lens, and this was repeated three times. The smoothness of the contact lens surfaces was then evaluated.

[0052] Sample 9-1 (EX9-1): Hydrogel-2 dry lenses were manufactured. The lens ingredients are listed in Table 1. The process from lens formulation to dry lens production is well known in the art, and mold-based manufacturing methods are available. Contact lens curing can be performed using either photocuring or heat curing; photocuring was selected for this sample. The dry lenses were immersed in a 0.5 wt% aqueous sodium carbonate solution for 20 minutes to rapidly ionize the MAA in the dry lenses, expanding them and improving cleaning efficiency. The lenses were then hydrated in RO water at room temperature (20-30°C) for 40 minutes to wash away residual monomers, crosslinkers, initiators, and fillers from the curing reaction, yielding wet lenses. The resulting wet lenses were then immersed in a 0.2 g / L aqueous solution of PVA (molecular weight 145,000 Da, hydrolysis degree 99%) and heated at 70±5°C for 120 minutes. The wetted lenses were then immersed in a 0.6 g / L aqueous solution of PVP (molecular weight 360,000 Da) and heated at 70±5°C for 120 minutes. The resulting wetted lenses were placed in a PP cup, and a standard buffered saline solution was added dropwise into the cup. The buffer level should be higher than the wetted lens, ensuring that all of the buffer covered the wetted lens. After completion, the aluminum foil and PP cup were sealed using a heat seal method and then placed in an autoclave for sterilization. The sterilization conditions were to heat the lens to 122°C, maintain the pressure at 122°C and 2 atmospheres, and continue this process for 30 minutes. Approximately 12 hours after the wet lenses had been in contact with the buffer solution (including the sterilization process), the aluminum foil was opened, the contact lenses were removed, and the lenses were placed in a standard buffer solution to equilibrate. The buffer solution was changed every hour using 10 ml of standard buffer solution per contact lens, and this was repeated three times. The formulation of the standard buffer solution is listed in Table 2.

[0053] Sample 6-2 (EX6-2): This sample was prepared using the same method as Sample 9-1, except that the aluminum foil and the PP cup were heat-sealed and then sterilized in an autoclave. Instead, the wet lenses were simply immersed in a standard buffered saline solution within the heat-sealed aluminum foil PP cup. After approximately 12 hours (including the sterilization process) of the wet lenses coming into contact with the buffer solution, the aluminum foil was opened, the contact lenses were removed, and the contact lenses were placed in a standard buffer solution to equilibrate. The buffer solution was changed every hour using 10 ml of standard buffered saline solution per contact lens, and this was repeated three times. The smoothness of the contact lens surfaces was then evaluated.

[0054] Sample 7-2 (EX7-2): This sample was prepared using the same method as Sample 4-1, except that Buffer 3 was replaced with Buffer 1. The blending ratio of Buffer 1 is shown in Table 2. After sterilization was completed, approximately 12 hours (including the sterilization process) had passed since the wet lenses began to come into contact with the buffer solution. The aluminum foil was opened, the contact lenses were removed, and the lenses were placed in a standard buffer solution to equilibrate. The buffer solution was replaced every hour using 10 ml of standard buffer solution per contact lens, and this was repeated three times. The smoothness of the contact lens surfaces was then evaluated.

[0055] Sample 8-2 (EX8-2): Prepared using the same method as Sample 7-2, except that before evaluating the surface smoothness of the contact lens, the aluminum foil was opened, the contact lens was removed, and the lens was placed in a standard buffer solution to be equilibrated. The buffer solution was changed every hour using 10 ml of the standard buffer solution per contact lens, and this was repeated three times, after which the surface smoothness of the contact lens was evaluated.

[0056] Sample 9-2 (EX9-2): This sample was prepared using the same method as Sample 4-1, except that Buffer 3 was replaced with Buffer 2. The blending ratio of Buffer 2 is shown in Table 2. After sterilization was completed, approximately 12 hours (including the sterilization process) had passed since the wet lenses began to come into contact with the buffer solution. The aluminum foil was opened, and the contact lenses were removed and placed in a standard buffer solution to equilibrate. The buffer solution was replaced every hour using 10 ml of standard buffer solution per contact lens, and this was repeated three times. The smoothness of the contact lens surfaces was then evaluated.

[0057] Surface lubricity score of contact lenses. The surface smoothness of contact lenses is rated on a scale of 1 to 4. Higher scores indicate greater smoothness of the contact lenses. A score of 1 indicates that the contact lenses feel completely unsmooth when rubbed with the hand. A score of 2 indicates that the contact lenses feel somewhat smooth when rubbed with the hand, which is comparable to the commercially available contact lens product Acuvue Oasys 1 day. A score of 3 indicates that the contact lenses are moderately smooth. A score of 4 indicates that the contact lenses are very smooth, which is comparable to the commercially available contact lens product Dailies Total 1. It should be noted that some contact lens wearers rate the wearing comfort of Dailies Total 1 as very good, but find the contact lenses too slippery, making them very difficult to remove after use, which affects their willingness to continue wearing that brand of contact lenses. Therefore, the smoothness of a contact lens is not necessarily better. In the present evaluation, the optimal smoothness is 3.

[0058] Surface smoothness evaluation test method: Five subjects were selected, and each subject simultaneously rubbed both Acuvue Oasys 1 day and Dailies Total 1. The smoothness of the feeling when rubbing Acuvue Oasys 1 day was given a score of 2, and the smoothness of the feeling when rubbing Dailies Total 1 was given a score of 4. If four out of the five subjects rated the smoothness of the test sample as significantly lower than Acuvue Oasys 1 day, the test sample's smoothness was given a score of 1. If three subjects rated the smoothness of the test sample as significantly lower than Acuvue Oasys 1 day and two subjects rated the difference from Acuvue Oasys 1 day as unclear, the score was 1-2. If four or more subjects judged the smoothness of the test sample to be equivalent to Acuvue Oasys 1 day, the score was 2. If three or more people rate the test sample as significantly smoother than Acuvue Oasys 1 day and two people rate it as equivalent to Acuvue Oasys 1 day, the score will be 2-3. If four or more people rate the test sample as significantly smoother than Acuvue Oasys 1 day, the score will be 3.

[0059] The surface smoothness evaluation of this sample is shown in Table 3.

[0060] [Table 3]

[0061] The data in Table 3 show that the technical features proposed by the present invention (Samples EX1-1, 2-1, 3-1, 4-1, 5-1, 6-1, 7-1, 8-1, and 9-1) can effectively improve surface smoothness and control it within a suitable range. The main difference between Sample 1-1 (EX1-1) and Sample 1-2 (EX1-2) is whether or not they are sterilized. Sample 1-1, which was sterilized, has a higher surface smoothness and is scored 3 points. Similarly, the surface smoothness score of Sample 2-1 (EX2-1) is higher than that of Sample 2-2 (EX2-2). The surface smoothness score of Sample 3-1 (EX3-1) is also higher than that of Sample 3-2 (EX3-2). However, this is due to its similarity to Sample 1-1 (EX1-1), and a detailed explanation is omitted here. Samples 4-1 (EX4-1) and 4-2 (EX4-2) are similar, but the main difference between them is the timing of contacting the first and second polymers with the lens core body. In Sample 4-1 (EX4-1), the lens core body is immersed in a buffer solution containing both the first and second polymers, allowing the first polymer to effectively form an interpenetrating polymer network with the surface structure of the lens core body, thereby affecting the surface smoothness of the final contact lens. The main difference between Sample 5-1 (EX5-1) and Sample 5-2 (EX5-2) is that Sample 5-2 was sterilized twice. First, it was immersed in Buffer-2 containing PVA, followed by sterilization for the first time, and then in Buffer-1 containing PVP, followed by sterilization for the second time. Based on the surface smoothness score, Sample 5-1 received a higher score than Sample 5-2. The reason for this is thought to be that during the first sterilization of Sample 5-2, strong hydrogen bonds and cross-linking reactions were formed between some of the polyvinyl alcohol in the first polymer, which may prevent the second polymer from forming an outer shell layer with the first polymer during the second sterilization, resulting in an unstable outer shell layer and a low surface smoothness score.Comparing Sample 9-1 (EX9-1) and Sample 6-2 (EX6-2), Sample 9-1 received a higher surface smoothness score due to its sterilization process. Sample 4-1 (EX4-1) and Sample 7-2 (EX7-2) are similar, but the main difference between them is that the Buffer-3 in which Sample 4-1 is immersed contains not only the second polymer but also the first polymer. This allows the second polymer to stably reside on the surface of the lens core body with the help of the first polymer. Therefore, Sample 4-1 received a higher surface smoothness score. Similarly, the surface smoothness score of Sample 4-1 (EX4-1) was higher than that of Sample 8-2 (EX8-2), but a detailed explanation of this is omitted here. Comparing Sample 4-1 (EX4-1) and Sample 9-2 (EX9-2), Sample 4-1 receives a higher surface smoothness score than Sample 9-2 because Buffer-3, in which Sample 4-1 is immersed, contains not only the first polymer but also the second polymer, which helps form an outer shell layer that improves the surface smoothness of the contact lens.

[0062] The contact lenses of Samples 4-1 and 7-2 were rinsed three times with RO water to remove components (including buffer salts such as NaCl, NaH2PO4, and Na2HPO4) from the contact lens surface. The contact lenses were then dried at 105°C for at least 8 hours to remove water and obtain dry lenses. The surface composition of the dried lenses was then analyzed using energy-dispersive X-ray spectroscopy with scanning electron microscope (SEM-EDX). The elemental analysis data showed that the surface of the treated dry lens of Sample 4-1 contained 4.39% nitrogen, indicating that the second polymer (PVP) remained stable on the surface of the lens core body after rinsing with RO water. However, no nitrogen was detected on the surface of the treated dry lens of Sample 7-2, indicating that the second polymer (PVP) originally present on the surface of the lens core body was washed away after rinsing with RO water. Therefore, using the SEM-EDX analysis method, it can be further demonstrated that the lens core body of the contact lens in one embodiment of the present invention is covered with an outer shell layer comprising a second polymer (PVP).

[0063] From the above data analysis and explanation, it can be proved that the technical features proposed in the present invention can effectively provide contact lenses with adequate surface smoothness and improve the comfort of wearing contact lenses.

[0064] Although the present invention has been disclosed using examples, the present invention is not limited thereto. Those skilled in the art can make some modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention is limited by the appended claims. [Explanation of symbols]

[0065] 100: Contact lenses 110: Lens core body 120: Outer shell 121: First Polymer 122: Second Polymer

Claims

1. A contact lens comprising a lens core body and an outer shell layer covering the lens core body, the outer shell layer comprising a first polymer containing polyvinyl alcohol and a second polymer containing polyvinylpyrrolidone.

2. The contact lens of claim 1 , wherein the first polymer covers the lens core body and the second polymer covers the first polymer.

3. 10. The contact lens of claim 1, wherein the first polymer is a partially hydrolyzed polyvinyl alcohol having a degree of hydrolysis of 70% to 99%.

4. 10. The contact lens of claim 1, wherein the first polymer is a partially hydrolyzed polyvinyl alcohol having a degree of hydrolysis of 80% to 98%.

5. 10. The contact lens of claim 1, wherein the first polymer is a partially hydrolyzed polyvinyl alcohol having a degree of hydrolysis of 88% to 95%.

6. The contact lens of claim 1 , wherein the second polymer has a molecular weight of 8,000 Da or greater.

7. The contact lens of claim 1 , wherein the second polymer has a molecular weight of 160,000 Da or greater.

8. The contact lens of claim 1 , wherein the second polymer has a molecular weight of 360,000 Da or greater.

9. The contact lens of claim 1 , wherein the second polymer further comprises dimethylaminoethyl methacrylate.

10. The contact lens of claim 9 , wherein the second polymer has a molecular weight of 100,000 Da or greater.

11. The contact lens of claim 1 , wherein the contact lens is a hydrogel contact lens.

12. The contact lens of claim 1 , wherein the contact lens is a silicone hydrogel contact lens.

13. 2. The contact lens of claim 1, wherein nitrogen element can be detected in elemental analysis using a scanning electron microscope, and the nitrogen element originates from the outer shell layer.

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