A color-changing silicone hydrogel contact lens and a method of making the same

Abstract

The present application belongs to the technical field of contact lenses, and provides a color-changing silicon hydrogel contact lens and a preparation method thereof. The color-changing silicon hydrogel contact lens comprises the following components in mass fractions: 30-70 parts of an organic silicon monomer, 20-60 parts of a hydrophilic monomer, 0.1-5 parts of a color-changing dye, 0.1-2 parts of a crosslinking agent, 0.1-2 parts of an initiator, and 5-20 parts of an auxiliary agent. The color-changing silicon hydrogel contact lens realizes stable combination of the photochromic function and the silicon hydrogel base material, can maintain colorless transparency indoors, quickly changes color under outdoor light and the color change is reversible and stable; does not precipitate or decolorize during long-term use, ensures long-term stability of the color-changing function, and has excellent biocompatibility and safety, meets the medical contact lens standard, and has a very broad application prospect.

Description

Technical Field

[0001] This invention relates to the field of contact lens technology, and more particularly to a photochromic silicone hydrogel contact lens and its preparation method. Background Technology

[0002] Contact lenses, as an important optical product for correcting vision, are widely used in daily life. Currently, commercially available products are mainly divided into two categories: hydrogel and silicone hydrogel. Among them, silicone hydrogel lenses, due to the introduction of silicon groups, significantly improve the oxygen permeability of the lens and effectively reduce the risk of corneal hypoxia, and have become the mainstream in the current market.

[0003] However, existing silicone hydrogel contact lenses still generally suffer from the following technical drawbacks: They lack automatic light adjustment capabilities, easily causing visual discomfort in strong outdoor light. During daily outdoor activities, strong ultraviolet rays and glare can lead to eye strain, photophobia, and other problems; long-term exposure may even damage the retina. Ordinary contact lenses cannot dynamically adjust their light transmittance according to ambient light intensity, often requiring users to wear sunglasses, resulting in significant shortcomings in convenience and eye protection.

[0004] To address these issues, the industry has attempted to incorporate photochromic materials into contact lenses, but directly adding these materials still faces the following technical challenges: 1. Poor compatibility and durability of photochromic materials with lens substrates: Existing photochromic lenses mostly introduce photochromic dyes through surface coatings or physical doping, which generally suffer from problems such as easy wear of the photochromic layer, easy dye leaching, and poor resistance to sterilization and boiling. During long-term wear, the lenses are prone to discoloration, decline or even failure of photochromic function, and the leached dye may also cause eye irritation or inflammation, posing safety hazards.

[0005] 2. Integration challenges of color-changing function in high-silicon formulation systems: Although high-silicon-content silicone hydrogels have excellent oxygen permeability, the introduction of color-changing dyes can easily interfere with the inherent cross-linking network of the substrate, leading to a decrease in the mechanical strength and toughness of the lens, and making it difficult to guarantee biocompatibility; at the same time, the uniformity of dye dispersion and the reversible stability of color change also face significant challenges.

[0006] Therefore, it is of great significance to develop a photochromic silicone hydrogel contact lens that achieves a stable combination of photochromic function and silicone hydrogel substrate while maintaining high oxygen permeability and wearing comfort, and also has reversible and sensitive color change, no exudation or discoloration after long-term use, and excellent biocompatibility. Summary of the Invention

[0007] In view of this, the present invention provides a photochromic silicone hydrogel contact lens and its preparation method, in order to solve the problems of existing contact lenses lacking automatic light adjustment function, poor compatibility between photochromic materials and silicone hydrogel substrates, insufficient durability, and difficulty in synergistically optimizing high oxygen permeability and stable color change.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a photochromic silicone hydrogel contact lens, comprising the following components in parts by weight: 30-70 parts of organosilicon monomer, 20-60 parts of hydrophilic monomer, 0.1-5 parts of color-changing dye, 0.1-2 parts of crosslinking agent, 0.1-2 parts of initiator, and 5-20 parts of auxiliaries.

[0009] Preferably, the organosilicon monomer includes one or more of (3-methacryloyloxy-2-hydroxypropoxy)propylbis(trimethylsiloxy)methylsilane, 2-(trimethylsiloxy)ethyl methacrylate, methacryloyloxypropyl mono-terminated polydimethylsiloxane, vinyltriethoxysilane, triisopropylsilyl methacrylate, and methacryloyloxypropyltri(trimethylsiloxane)silane.

[0010] Preferably, the hydrophilic monomer comprises one or more of hydroxyethyl methacrylate, N-vinylpyrrolidone, N,N-dimethylacrylamide, methacrylic acid, and 2-methacryloyloxyethylphosphorylcholine.

[0011] Preferably, the color-changing dye includes one or more of spiroxazine-based photochromic materials, naphthopyran-based photochromic materials, and diarylethylene-based photochromic materials.

[0012] Preferably, the crosslinking agent includes one or more of ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, N,N'-methylenebisacrylamide, and trimethylolpropane trimethacrylate.

[0013] Preferably, the initiator includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, and azobisisobutyramidine hydrochloride.

[0014] Preferably, the adjuvant includes one or more of isopropanol, n-butanol, tert-amyl alcohol, and N-methylpyrrolidone.

[0015] The present invention also provides a method for preparing the above-mentioned photochromic silicone hydrogel contact lens, comprising the following steps: 1) Mix the color-changing dye with some auxiliaries to obtain a pre-dispersion of the color-changing dye; 2) Mix the color-changing dye pre-dispersion solution with organosilicon monomers, hydrophilic monomers, crosslinking agents, initiators and remaining auxiliaries to obtain a monomer mixture solution; 3) The monomer mixture is thermosetting in stages to obtain a dry lens blank. Then, the dry lens blank is immersed in water and hydrated and sterilized in sequence to obtain a photochromic silicone hydrogel contact lens.

[0016] Preferably, the mass ratio of the auxiliary agent mentioned in step 1) to the remaining auxiliary agent mentioned in step 2) is 1.5~2.5:4.5~5.5; the mixing condition mentioned in step 2) is to avoid light.

[0017] Preferably, the segmented thermosetting molding in step 3) includes a first stage thermosetting and a second stage thermosetting performed sequentially; the temperature of the first stage thermosetting is 40~80℃ and the time is 0.5~2 h; the temperature of the second stage thermosetting is 80~120℃ and the time is 2~4 h.

[0018] Preferably, the hydration time in step 3) is 0.5~2 h; the sterilization temperature in step 3) is 80~100℃ and the time is 0.5~2 h.

[0019] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows: 1. The photochromic silicone hydrogel contact lens of the present invention comprises an organosilicon monomer, a hydrophilic monomer, a photochromic dye, a crosslinking agent, an initiator, and an auxiliary agent. The photochromic dye can sensitively respond to environmental ultraviolet rays and light intensity. Under low indoor light, the lens remains transparent and colorless, ensuring light transmission comfort during daily wear. Under strong outdoor light, when excited by ultraviolet rays, the molecular structure undergoes reversible isomerization and quickly and naturally changes color, effectively preventing glare and protecting the eyes. After returning indoors, it can slowly return to a colorless state. The color-changing response is fast, the color difference transition is natural, and the reversible cycle is stable, taking into account both light transmission comfort and outdoor anti-glare and eye protection effects. 2. This invention uses a copolymerization method to combine photochromic dyes with silicone hydrogel substrates, and employs a three-component synergistic compound of vinylsiloxane-modified photochromic dyes, silicon-containing macromolecular crosslinking monomers, and hydrophilic copolymer monomers. This allows the contact lenses to change color upon exposure to light and fade automatically in the absence of light. They are resistant to sterilization and boiling treatment, and do not leach or fade even after long-term wear. This effectively solves the problems of easy leakage and failure of dyes in traditional photochromic lenses, and ensures the compatibility, durability, and long-term stability of the color-changing function between the photochromic dye and the lens substrate. 3. The formulation system of the photochromic silicone hydrogel contact lenses described in this invention does not contain irritating ingredients, has no cytotoxicity, poses no risk of eye irritation, and has a controllable risk of dye precipitation. It fully complies with the safety standards for medical contact lenses, is safe and reliable to wear, and has excellent biocompatibility and high safety. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0021] Figure 1 Images of the dry and wet lenses of the photochromic silicone hydrogel contact lenses prepared in Example 1 after they have changed color outdoors; Figure 2 The images show the dry and wet lenses of the photochromic silicone hydrogel contact lenses prepared in Example 2 after they changed color outdoors. Detailed Implementation

[0022] This invention provides a photochromic silicone hydrogel contact lens, preferably comprising the following components in parts by weight: 30-70 parts of organosilicon monomer, 20-60 parts of hydrophilic monomer, 0.1-5 parts of photochromic dye, 0.1-2 parts of crosslinking agent, 0.1-2 parts of initiator, and 5-20 parts of additives; more preferably comprising the following components in parts by weight: 35-60 parts of organosilicon monomer, 30-55 parts of hydrophilic monomer, 0.5-3 parts of photochromic dye, 0.5-1.5 parts of crosslinking agent, 0.5-1.5 parts of initiator, and 8-15 parts of additives; more preferably comprising the following components in parts by weight: 40-45 parts of organosilicon monomer, 40-50 parts of hydrophilic monomer, 0.8-2 parts of photochromic dye, 0.8-1 part of crosslinking agent, 0.8-1 part of initiator, and 10-12 parts of additives.

[0023] In this invention, the organosilicon monomer preferably includes one or more of (3-methacryloyloxy-2-hydroxypropoxy)propylbis(trimethylsiloxy)methylsilane, 2-(trimethylsiloxy)ethyl methacrylate, methacryloyloxypropyl mono-terminated polydimethylsiloxane, vinyltriethoxysilane (VTES), triisopropylsilyl methacrylate, and methacryloyloxypropyltri(trimethylsiloxane)silane.

[0024] In this invention, the (3-methacryloyloxy-2-hydroxypropoxy)propylbis(trimethylsiloxy)methylsilane contains hydroxyl-modified groups, which can enhance the hydrogen bonding force with hydrophilic monomers, improve the compatibility of silicon-hydrophilic components, and inhibit phase separation. Simultaneously, the hydroxyl groups can improve the surface wettability of the lens, balance the hydrophobic drawbacks of high-silica formulations, and improve oxygen permeability and comfort. The 2-(trimethylsiloxy)ethyl methacrylate can balance the oxygen permeability and hydrophilicity of the lens, improve the surface lubricity of the lens, reduce the hydrophobic drawbacks of silicon materials, and simultaneously improve the mechanical strength and molding stability of the lens. The methacryloyloxypropyl mono-terminated polydimethylsiloxane is a monofunctional polysiloxane monomer with a customizable molecular weight. This technology can precisely control the elastic modulus and flexibility of the lens, improve the fit of the lens, and synergistically enhance oxygen permeability. It also has good compatibility with hydrophilic monomers. The vinyltriethoxysilane can enhance the compatibility between silicon-containing components and hydrophilic components, inhibit phase separation during polymerization, improve lens transparency and uniformity, and optimize the mechanical stability of the lens. The triisopropylsilyl methacrylate, as a hydrophobic silicon-based comonomer, can improve the material's oxygen permeability, hydrophobicity, and anti-deposition properties. The methacryloyloxypropyltris(trimethylsiloxane)silane is a highly oxygen-permeable silicon monomer with a high silicon content structure, which can significantly improve lens oxygen permeability, effectively alleviate corneal hypoxia, and enhance the lens's breathability and anti-aging properties.

[0025] In this invention, the hydrophilic monomer preferably includes one or more of hydroxyethyl methacrylate (HEMA), N-vinylpyrrolidone (NVP), N,N-dimethylacrylamide (DMAA), methacrylic acid (MAA), and 2-methacryloyloxyethylphosphorylcholine (MPC).

[0026] In this invention, the 2-hydroxyethyl methacrylate contains hydrophilic hydroxyl groups, which can improve the surface wettability of the lens, help the tear film adhere stably, reduce friction between the lens and the cornea, and reduce foreign body sensation. It can also improve the dryness caused by the hydrophobicity of pure silicone materials, allowing the silicone hydrogel lens to possess both high oxygen permeability and moisturizing properties. The N-vinylpyrrolidone has extremely strong hydrophilicity, which can significantly improve the lens's water absorption rate and oxygen permeability, further optimizing tear film adhesion and enhancing wearing comfort. It is especially suitable for use with high-silicone formulations to balance hydrophobic and hydrophilic properties and reduce lens dehydration and shrinkage. The N,N-dimethylacrylamide has a flexible molecular structure and can reduce the glass transition temperature of the lens. The lens improves flexibility and fit, reducing the feeling of a foreign object during wear, while also possessing good biocompatibility, reducing the risk of eye irritation. The methacrylic acid is a weakly acidic hydrophilic component that can precisely control the swelling and mechanical strength of the lens, optimizing lens forming precision, and enhancing the slight adhesion between the lens and the cornea, thus improving wearing stability. The molecular structure of 2-methacryloyloxyethyl phosphorylcholine mimics the phospholipid groups of cell membranes, exhibiting excellent biocompatibility. It can form a hydration layer on the lens surface, significantly inhibiting the non-specific adhesion of proteins, lipids, and cells, greatly reducing the risk of lens deposition, while also improving lens surface lubrication and wearing comfort, and reducing the probability of eye inflammation.

[0027] In this invention, the color-changing dye preferably includes one or more of spiroxazine-based photochromic materials, naphthopyran-based photochromic materials, and diarylethylene-based photochromic materials.

[0028] In this invention, the crosslinking agent preferably includes one or more of ethylene glycol dimethacrylate (EGDMA), triethylene glycol dimethacrylate (TEGDMA), N,N'-methylenebisacrylamide (MBA), and trimethylolpropane trimethacrylate (TMPTMA).

[0029] In this invention, the ethylene glycol dimethacrylate can undergo a cross-linking reaction with monomers to form a rigid cross-linked network, effectively improving the mechanical strength and anti-swelling properties of the lens, reducing swelling and deformation of the lens in tears, and ensuring the shape stability and optical performance accuracy of the lens. The triethylene glycol dimethacrylate, as a flexible cross-linking component, can construct a flexible cross-linked network, improving the flexibility and elasticity of the lens, reducing the risk of brittle breakage, and lowering the glass transition temperature of the lens, thus improving wearing comfort. The N,N'-methylenebisacrylamide has high cross-linking efficiency and can quickly form a dense cross-linked network, significantly improving the lens's resistance to deformation and mechanical stability, reducing the lens swelling rate, ensuring that the lens does not change shape during long-term use, and adapting to lenses worn for extended periods. The trimethylolpropane trimethacrylate has high polymerization activity and can quickly construct a dense cross-linked network with hydrophilic and silicon monomers, effectively improving the dimensional stability and tear resistance of the lens, and reducing the risk of deformation during wear.

[0030] In this invention, the initiator preferably includes one or more of azobisisobutyronitrile (AIBN), azobisisoheptanenitrile (ADVN), benzoyl peroxide (BPO), and azobisisobutyramidine hydrochloride (AAPH).

[0031] In this invention, the azobisisobutyronitrile decomposes smoothly upon heating to generate free radicals, initiating a polymerization reaction between hydrophilic and silicon monomers. The reaction process is mild and easily controlled, improving the uniformity of the polymerization reaction, reducing internal stress in the lens, and ensuring stable lens molding quality. The azobisisobutyronitrile decomposes slowly upon heating to generate free radicals, resulting in a milder exothermic reaction during polymerization. This reduces issues such as lens bubbles and yellowing caused by localized overheating in the polymerization system, improving the optical uniformity of the lens. The benzoyl peroxide has a moderate decomposition temperature, making it suitable for high-temperature polymerization processes. It significantly improves the polymerization conversion rate, ensuring sufficient monomer reaction, while also enhancing the crosslinking density of the lens, increasing its mechanical strength, and reducing the risk of lens deformation. The azobisisobutyramidine hydrochloride is a water-soluble thermal initiator with good biocompatibility, suitable for aqueous polymerization systems of hydrophilic monomers. It avoids organic solvent residues, improving lens wearing safety, and also ensures a stable initiation reaction, guaranteeing uniform lens performance.

[0032] In this invention, the adjuvant preferably includes one or more of isopropanol, n-butanol, tert-amyl alcohol, and N-methylpyrrolidone.

[0033] In this invention, isopropanol can efficiently dissolve most hydrophilic and silicon-containing monomers, has a moderate evaporation rate, reduces residual stress during lens molding, and improves lens dimensional accuracy; it also has low toxicity, reducing the risk of eye irritation from solvent residue in the finished product; n-Butanol is a medium-boiling-point polar solvent that can adjust the viscosity and flowability of the polymerization system, improving lens molding uniformity; it has good compatibility with high-silicon monomers, enhancing the dispersibility of silicon-containing components, and is suitable for the polymerization process of high oxygen-permeable silicone hydrogel lenses; tert-amyl alcohol has a high boiling point, which can slow down the evaporation rate of solvents in the polymerization system, reducing defects such as bubbles and shrinkage during lens molding, and improving lens surface smoothness; it also has good solubility, adapting to the dissolution requirements of most hydrophilic and silicon-containing monomers, and has low toxicity, reducing the risk of eye irritation from solvent residue in the finished product; N-methylpyrrolidone can dissolve or disperse silicon monomers, hydrophilic monomers, and polymer additives, helping the system to mix uniformly, avoiding phase separation, and improving material uniformity.

[0034] The present invention also provides a method for preparing the above-mentioned photochromic silicone hydrogel contact lens, comprising the following steps: 1) Mix the color-changing dye with some auxiliaries to obtain a pre-dispersion of the color-changing dye; 2) Mix the color-changing dye pre-dispersion solution with organosilicon monomers, hydrophilic monomers, crosslinking agents, initiators and remaining auxiliaries to obtain a monomer mixture solution; 3) The monomer mixture is thermosetting in stages to obtain a dry lens blank. Then, the dry lens blank is immersed in water and hydrated and sterilized in sequence to obtain a photochromic silicone hydrogel contact lens.

[0035] In this invention, the preferred storage conditions for the color-changing dye pre-dispersion liquid in step 1) are light-proof and sealed storage.

[0036] In this invention, the mass ratio of the auxiliary agent mentioned in step 1) to the remaining auxiliary agent mentioned in step 2) is 1.5~2.5:4.5~5.5, preferably 1.8~2.2:4.8~5.2, and more preferably 2:5; the mixing condition mentioned in step 2) is to avoid light; the mixing time is preferably 0.5~2 h, more preferably 0.8~1.8 h, and more preferably 1~1.5 h.

[0037] In this invention, the segmented thermosetting molding in step 3) includes sequentially performing a first-stage thermosetting and a second-stage thermosetting; the temperature of the first-stage thermosetting is 40~80℃, preferably 45~75℃, more preferably 50~70℃, and even more preferably 55~60℃; the time of the first-stage thermosetting is 0.5~2 h, preferably 0.8~1.8 h, more preferably 1~1.6 h, and even more preferably 1.2~1.5 h; the first-stage thermosetting causes the monomers to undergo preliminary crosslinking; the temperature of the second-stage thermosetting is 80~120℃, preferably 85~110℃, more preferably 90~105℃, and even more preferably 95~100℃; the time of the second-stage thermosetting is 2~4 h, preferably 2.5~3.5 h, and even more preferably 2 h; the second-stage thermosetting completes deep polymerization.

[0038] In this invention, step 3) after the second stage of thermosetting preferably includes a natural cooling to room temperature operation.

[0039] In this invention, the hydration time in step 3) is 0.5~2 h, preferably 0.8~1.8 h, more preferably 1~1.6 h, and more preferably 1.2~1.5 h; the sterilization temperature in step 3) is 80~100℃, preferably 85~95℃, and more preferably 90℃; the sterilization time is 0.5~2 h, preferably 0.8~1.8 h, more preferably 1~1.6 h, and more preferably 1.2~1.5 h; the sterilization is used to further remove residual solvent and allow the lens to fully swell to an equilibrium state.

[0040] In this invention, after sterilization in step 3), it is preferable to further include sequential packaging and high-pressure steam sterilization operations; the packaging container is preferably a PP cup; the temperature of the high-pressure steam sterilization is preferably 115~125℃, more preferably 118~123℃, and even more preferably 121℃; the time of the high-pressure steam sterilization is preferably 15~35 min, more preferably 20~33 min, and even more preferably 30 min.

[0041] In this invention, the preparation method of the photochromic silicone hydrogel contact lenses adopts a mature molding and thermosetting process, which is controllable, has a high yield, can achieve large-scale production, and has good market application prospects.

[0042] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0043] Example 1

[0044] In this embodiment, the photochromic silicone hydrogel contact lens comprises the following components in parts by weight: 45 parts of organosilicon monomer (TRIS), 45 parts of hydrophilic monomer (obtained by mixing 2-hydroxyethyl methacrylate and N-vinylpyrrolidone in a mass ratio of 2:1), 1 part of photochromic dye (spiroxazine photochromic material), 0.5 parts of crosslinking agent (ethylene glycol dimethacrylate), 0.8 parts of initiator (azobisisobutyronitrile), and 7.7 parts of auxiliary agent (n-butanol); Among them, the spiroxazine photochromic material was purchased from Tianjin Seterui SP-01 high-purity indoline spiroxazine (CAS: 114747-45-4, purity ≥98%).

[0045] The preparation method of the above-mentioned photochromic silicone hydrogel contact lenses is as follows: 1) Mix the color-changing dye with some of the auxiliary agents according to the above mass proportions, and stir ultrasonically for 30 min to completely dissolve the color-changing dye to obtain a color-changing dye pre-dispersion solution. Store it in a sealed container away from light for later use. 2) Mix the color-changing dye pre-dispersion solution with organosilicon monomers, hydrophilic monomers, crosslinking agents, initiators and remaining auxiliaries (the mass ratio of some auxiliaries to the remaining auxiliaries is 2:5) under light-protected conditions and stir for 1 h to obtain a monomer mixture. 3) Inject the monomer mixture into the contact lens base plate, seal it with the mold, and place it in a tunnel oven. First, heat cure it at 50℃ for 1 hour, then heat cure it at 90℃ for 3 hours. Finally, let it cool naturally to room temperature, demold it to obtain a dry lens blank, then immerse the dry lens blank in purified water and soak it at room temperature for 1 hour for hydration. Then take it out and immerse it in deionized water at 100℃ for 1 hour for sterilization. Finally, put it into a PP cup containing preservation solution (phosphate buffer), seal it, and autoclave it at 121℃ for 30 minutes to obtain a photochromic silicone hydrogel contact lens (denoted as lens S1).

[0046] Example 2

[0047] In this embodiment, the photochromic silicone hydrogel contact lens comprises the following components in parts by weight: 50 parts of organosilicon monomer (2-(trimethylsiloxy)ethyl methacrylate), 30 parts of hydrophilic monomer (obtained by mixing 2-hydroxyethyl methacrylate and N,N-dimethylacrylamide in a mass ratio of 5:1), 2 parts of photochromic dye (naphthopyran-based photochromic material), 1 part of crosslinking agent (trimethylolpropane trimethacrylate), 0.5 parts of initiator (azobisisobutyronitrile), and 6.5 parts of auxiliary agent (tert-amyl alcohol); Among them, the naphthopyran photochromic material was purchased from Wuhan Haishan NP-01 diphenylnaphthopyran (CAS: 4222-20-2, purity ≥98%).

[0048] The preparation method of the above-mentioned photochromic silicone hydrogel contact lenses is as follows: 1) Mix the color-changing dye with some of the auxiliary agents according to the above mass proportions, and stir ultrasonically for 30 min to completely dissolve the color-changing dye to obtain a color-changing dye pre-dispersion solution. Store it in a sealed container away from light for later use. 2) Mix the color-changing dye pre-dispersion solution with organosilicon monomers, hydrophilic monomers, crosslinking agents, initiators and remaining auxiliaries (the mass ratio of some auxiliaries to the remaining auxiliaries is 2:5) under light-protected conditions and stir for 1 h to obtain a monomer mixture. 3) Inject the monomer mixture into the contact lens base plate, seal it with the mold, and place it in a tunnel oven. First, heat cure it at 70°C for 1 hour, then heat cure it at 100°C for 3 hours. Finally, let it cool naturally to room temperature, demold it to obtain a dry lens blank, then immerse the dry lens blank in purified water and hydrate it at room temperature for 1 hour. Then, take it out and immerse it in deionized water at 100°C for 1 hour of sterilization. Finally, put it into a PP cup containing preservation solution (same as in Example 1), seal it, and sterilize it by high-pressure steam at 121°C for 30 minutes to obtain a photochromic silicone hydrogel contact lens (denoted as lens S2).

[0049] Example 3

[0050] In this embodiment, the photochromic silicone hydrogel contact lens comprises the following components in parts by weight: 55 parts of organosilicon monomer (TRIS), 33 parts of hydrophilic monomer (obtained by mixing 2-hydroxyethyl methacrylate, N-vinylpyrrolidone and methacrylic acid in a mass ratio of 20:10:3), 2 parts of photochromic dye (diarylethylene photochromic material), 0.8 parts of crosslinking agent (ethylene glycol dimethacrylate), 0.7 parts of initiator (azobisisobutyronitrile), and 8.5 parts of auxiliary agent (N-methylpyrrolidone); Among them, the diarylethene-based photochromic material was purchased from Xi'an Qiyue Biotechnology Co., Ltd. hydroxyl-type fluorinated diarylethene (CAS: 94142-97-9, purity ≥98%).

[0051] The preparation method of the above-mentioned photochromic silicone hydrogel contact lenses is as follows: 1) Mix the color-changing dye with some of the auxiliary agents according to the above mass proportions, and stir ultrasonically for 30 min to completely dissolve the color-changing dye to obtain a color-changing dye pre-dispersion solution. Store it in a sealed container away from light for later use. 2) Mix the color-changing dye pre-dispersion solution with organosilicon monomers, hydrophilic monomers, crosslinking agents, initiators and remaining auxiliaries (the mass ratio of some auxiliaries to the remaining auxiliaries is 2:5) under light-protected conditions and stir for 1 h to obtain a monomer mixture. 3) The monomer mixture is injected into the contact lens base plate, sealed with the mold, and placed in a tunnel oven. It is first heat-cured at 45°C for 1.5 h, then heat-cured at 115°C for 3 h, and finally cooled naturally to room temperature. The dry lens blank is then demolded to obtain a dry lens blank. The dry lens blank is then immersed in purified water and hydrated at room temperature for 1.5 h. After that, it is taken out and immersed in deionized water at 100°C for 1 h of sterilization by boiling. Finally, it is placed in a PP cup containing preservation solution (same as in Example 1), sealed, and sterilized by high-pressure steam at 121°C for 30 min to obtain a photochromic silicone hydrogel contact lens (denoted as lens S3).

[0052] The photochromic silicone hydrogel contact lenses prepared in Examples 1-3 above were subjected to the following basic performance tests. All test methods complied with the requirements of GB 11417.3-2012 "Ophthalmic Optical Contact Lenses Part 3: Soft Contact Lenses": 1. Optical and photochromic performance testing: The transmittance of lenses S1, S2, and S3 under indoor and outdoor photochromic states was tested using a transmittance meter. All tests were conducted in the visible light band of 280~780 nm. The indoor transmittance of lens S1 was 91.38%, and the outdoor transmittance after photochromic change was 91.28%. The indoor transmittance of lens S2 was 91.85%, and the outdoor transmittance after photochromic change was 91.86%. The indoor transmittance of lens S3 was 91.68%, and the outdoor transmittance after photochromic change was 91.65%. Both sets of results are greater than the 89% requirement specified in the national standard GB 11417.3-2012.

[0053] As can be seen from the above transmittance test, the lens prepared by the present invention maintains high transmittance indoors and also maintains high transmittance after color change, with stable performance, and can achieve dynamic adjustment of outdoor anti-glare and indoor transparency.

[0054] In addition, actual photos of the S1 lens after photochromic changes outdoors, both dry and wet, are shown below. Figure 1 As shown; actual images of dry and wet lenses of lens S2 after photochromic changes outdoors are shown below. Figure 2 As shown.

[0055] from Figures 1-2 As can be seen, the color-changing dye and the silicone hydrogel substrate are combined through copolymerization or uniform dispersion, resulting in fast color-changing response, reversible cycle stability, no precipitation or discoloration after long-term wear; in addition, the different colors are due to the use of different color-changing dyes.

[0056] 2. Moisture content test: The moisture content of lenses S1, S2 and S3 was tested by the drying loss method. The measured moisture contents were 55.25%, 55.65% and 55.48% respectively, all of which meet the design requirement of 56±2%. This shows that the lenses prepared by the present invention have moderate moisture content, are comfortable to wear, have good hydrophilicity, and can effectively reduce the dryness when wearing them.

[0057] 3. Safety and biocompatibility testing: The cytotoxicity test was conducted according to the ISO 10993-5 standard and the L929 cell culture method was used. It was found that the lenses S1, S2 and S3 prepared in Examples 1 to 3 had no obvious toxic reactions and the cytotoxicity level was ≤1.

[0058] The eye irritation test was conducted on rabbit conjunctiva according to the standard of ISO 10993-10. The results showed that the lenses S1, S2 and S3 prepared in Examples 1 to 3 did not show any irritation reactions such as congestion, edema, or secretions, and there was no obvious irritation.

[0059] The specific detection method for the dye precipitation test is as follows: the lenses S1, S2 and S3 prepared in Examples 1 to 3 were soaked in physiological saline for 30 days, and then detected by ultraviolet spectrophotometry. It was found that no obvious dye precipitation was observed in lenses S1, S2 and S3.

[0060] The specific method for testing sterilization stability is as follows: After the lenses S1, S2 and S3 prepared in Examples 1 to 3 were sterilized by high-pressure steam at 121°C for 10 times, the transmittance of the lenses was tested using a transmittance tester. It was found that the transmittance of lenses S1, S2 and S3 did not change, there was no discoloration, and there was no obvious performance degradation.

[0061] As can be seen from the above safety and biocompatibility test results, the lenses prepared by this invention are free from cytotoxicity and eye irritation, the dyes are stably bonded to the substrate, and there is no precipitation or discoloration after long-term wear and multiple sterilizations. The safety performance meets the requirements of medical contact lens standards.

[0062] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A photochromic silicone hydrogel contact lens, characterized in that, The components include the following parts by mass: 30-70 parts of organosilicon monomer, 20-60 parts of hydrophilic monomer, 0.1-5 parts of color-changing dye, 0.1-2 parts of crosslinking agent, 0.1-2 parts of initiator, and 5-20 parts of auxiliaries.

2. The photochromic silicone hydrogel contact lens according to claim 1, characterized in that, The organosilicon monomers include one or more of (3-methacryloyloxy-2-hydroxypropoxy)propylbis(trimethylsiloxy)methylsilane, 2-(trimethylsiloxy)ethyl methacrylate, methacryloyloxypropyl mono-terminated polydimethylsiloxane, vinyltriethoxysilane, triisopropylsilyl methacrylate, and methacryloyloxypropyltri(trimethylsiloxane)silane.

3. The photochromic silicone hydrogel contact lens according to claim 2, characterized in that, The hydrophilic monomers include one or more of hydroxyethyl methacrylate, N-vinylpyrrolidone, N,N-dimethylacrylamide, methacrylic acid, and 2-methacryloyloxyethylphosphorylcholine.

4. A photochromic silicone hydrogel contact lens according to any one of claims 1 to 3, characterized in that, The color-changing dyes include one or more of the following: spiroxazine-based photochromic materials, naphthopyran-based photochromic materials, and diarylethylene-based photochromic materials.

5. A photochromic silicone hydrogel contact lens according to claim 4, characterized in that, The crosslinking agent includes one or more of ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, N,N'-methylenebisacrylamide, and trimethylolpropane trimethacrylate.

6. The photochromic silicone hydrogel contact lens according to claim 5, characterized in that, The initiator includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, and azobisisobutyramidine hydrochloride.

7. A photochromic silicone hydrogel contact lens according to claim 6, characterized in that, The adjuvants include one or more of isopropanol, n-butanol, tert-amyl alcohol, and N-methylpyrrolidone.

8. A method for preparing a photochromic silicone hydrogel contact lens according to any one of claims 1 to 7, characterized in that, Includes the following steps: 1) Mix the color-changing dye with some auxiliaries to obtain a pre-dispersion of the color-changing dye; 2) Mix the color-changing dye pre-dispersion solution with organosilicon monomers, hydrophilic monomers, crosslinking agents, initiators and remaining auxiliaries to obtain a monomer mixture solution; 3) The monomer mixture is thermosetting in stages to obtain a dry lens blank. Then, the dry lens blank is immersed in water and hydrated and sterilized in sequence to obtain a photochromic silicone hydrogel contact lens.

9. The method for preparing a photochromic silicone hydrogel contact lens according to claim 8, characterized in that, The mass ratio of the auxiliary agent mentioned in step 1) to the remaining auxiliary agent mentioned in step 2) is 1.5~2.5:4.5~5.5; The mixing condition described in step 2) is to avoid light.

10. The method for preparing a photochromic silicone hydrogel contact lens according to claim 9, characterized in that, The segmented thermosetting molding described in step 3) includes sequential first-stage thermosetting and second-stage thermosetting; The temperature for the first stage of thermosetting is 40~80℃, and the time is 0.5~2 h; The second stage of thermosetting is carried out at a temperature of 80~120℃ for 2~4 hours. The hydration time mentioned in step 3) is 0.5~2 hours; The sterilization temperature in step 3) is 80~100℃ and the time is 0.5~2 h.

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