Contact lenses with PVA film

Abstract

A film is disclosed having a hydrophobic, water-insoluble dye embedded in polyvinyl alcohol (PVA). The dye is uniformly dispersed throughout the film, and the film is substantially free of organic solvents. The film can be attached to the center of a contact lens. Such a contact lens can be used to correct or improve color vision in people with color blindness.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 458,028, filed on April 7, 2023, which is hereby incorporated by reference in its entirety. The present invention generally relates to colored contact lenses.

Background Art

[0002] Colored contact lenses using dyes play an important role in the contact lens industry for various reasons, including coloring (so - called identification coloring) to easily identify contact lenses in physiological saline, cosmetic use, dealing with frequent migraines, and creating photochromic contact lenses. There are various coloring methods for dispersing dyes in contact lens materials. However, dispersing dyes in contact lens materials causes substantial problems such as the possibility of leaching into the eye in high - water - content soft contact lenses. Another problem is that effective dyes are not distributed where they are particularly needed but are dispersed throughout the contact lens.

Summary of the Invention

[0003] This specification discloses a contact lens having a lens body and a film coating the central portion of the lens body. The film can be attached to the convex surface of the contact lens body. In some examples, the film has a diameter between 4 mm and 7 mm, and the lens body has a diameter greater than 9 mm. The film coating the central portion of the contact lens body is made of polyvinyl alcohol (PVA) having a water - insoluble dye (or hydrophobic dye) embedded therein. The film substantially has no organic solvent. The water - insoluble dye (or hydrophobic dye) is uniformly dispersed throughout the film. The lens body itself contains no water - insoluble dye. The water-insoluble dye (or hydrophobic dye) is immersed in physiological saline for 30 days and then embedded in PVA to prevent the dye from migrating outside the film. Two or more dyes may be embedded in the PVA of the film. The dye may be a narrow-band dye. The dye may be a metal complex dye. The dye (or multiple dyes) within the film makes the film an optical filter having an absorption spectrum. One or more dyes within the film may be narrowband dyes having peak absorption in the range of 560 nm to 620 nm. The film may have an absorption spectrum with an absorption peak in the range of 560 to 620 nm and an optical density of peak absorption greater than 1. Films having these optical qualities may be used with contact lenses to correct or improve the color vision of wearers with color blindness.

[0004] This specification discloses a PVA film having an embedded water-insoluble dye (or hydrophobic dye) and a method for producing such a film. The method begins with preparing an organic solvent that does not form an azeotrope with water. For example, this organic solvent may be methanol or acetone. Next, the water-insoluble dye (or hydrophobic dye) is dissolved in the organic solvent to form a dye solution. Next, this dye solution is mixed with an aqueous solution of polyvinyl alcohol (PVA) to form a PVA-dye solution. Next, substantially all of the organic solvent is removed from the PVA-dye solution to form an aqueous PVA-dye solution. In certain examples, substantially removing all of the organic solvent involves heating the PVA-dye solution until the PVA-dye becomes a solid. Then, a dry nitrogen or argon gas is passed through to substantially remove all remaining free water. This solid form of PVA-dye can be stored and rehydrated when needed to form an aqueous PVA-dye solution. In some examples, the aqueous PVA-dye solution has a viscosity greater than 30 mPa / s.

[0005] The PVA-dye aqueous solution can be coated onto a substrate and cured to form a film. Alternatively, the PVA-dye aqueous solution may be printed or coated onto the central portion of the surface of a contact lens. After printing or coating, the PVA-dye aqueous solution on the contact lens is cured to form a PVA-dye film on the surface of the contact lens body. This contact lens body contains no water-insoluble dyes (or hydrophobic dyes) at all. The following figures illustrate various aspects of the systems and methods disclosed herein. Each figure represents an embodiment of a particular aspect of the disclosed systems and methods, and each of these figures is intended to correspond to a conceivable embodiment. Furthermore, wherever possible, the following descriptions refer to reference numerals included in the following figures, and features depicted in multiple figures are assigned consistent reference numerals. [Brief explanation of the drawing]

[0006] [Figure 1A-1B] This is a schematic diagram of a contact lens. Figure 1A is a cross-sectional view, and Figure 1B is a plan view. [Modes for carrying out the invention]

[0007] The following detailed description should be read with reference to the drawings, in which the same reference numerals refer to similar elements throughout the various figures. The drawings are not necessarily to scale and represent selective embodiments and are not intended to limit the scope of the invention. The detailed description illustrates the principles of the invention using examples, not for limiting purposes. Figures 1A and 1B show a contact lens 10 for correcting color blindness. Figure 1A is a cross-sectional view of the contact lens 10, and Figure 1B is a plan view of the contact lens 10. The lens body 20 of the contact lens 10 may be a hard lens, a soft lens, a continuous wear lens, or any other type of contact lens. The lens body 20 is typically bounded by a concave inner surface or base surface 21 and a convex outer surface 22. Generally, the lens body 20 has a diameter between 13 mm and 15 mm. Preferably, the diameter of the lens body is greater than about 9 mm. Generally, the central region of the contact lens covers the pupil region of the wearer's eye. The lens body is preferably formed from a substantially transparent biocompatible lens material. For example, the lens body may be formed from a polymerized hydroxyethyl methacrylate (HEMA) based lens material, such as Methafilcon A, or other biocompatible transparent material. The lens body may be colored or uncolored. The lens body may or may not be designed to provide some degree of vision correction; that is, the lens body may or may not enable prescription power.

[0008] The contact lens 10 also comprises a polyvinyl alcohol (PVA) film 30 embedded with a narrow-band dye. The film 30 coats the central region of the contact lens, i.e., the region that will cover the pupil region of the wearer's eye, but preferably not extend beyond the iris. In some embodiments, the film has a diameter of about 6 mm and covers the central portion of the contact lens body, which is 13 mm to 15 mm in diameter. The diameter of the film 30 may be in the range of 4 to 7 mm. Figure 1A shows the film 30 coating the convex outer surface 22 of the contact lens. The film 30 may coat the convex surface 22 of the contact lens. The film 30 has a thickness in the range of 5 to 25 μm, preferably about 15 μm. The molecular weight (MW) of the PVA in the film 30 may be in the range of 22,000 to 220,000 and has a degree of hydrolysis (DH) of 85% to 89%.

[0009] The film 30 contains one or more types of dyes. These dyes are hydrophobic organic dyes that are insoluble in water. The dyes may also be metal complex dyes. The dyes may also be narrowband dyes. Narrowband dyes are dyes that have an absorption peak with a full width at half maximum of at most 40 nm. The one or more types of dyes in the film 30 create an optical filter that can correct the wearer's color vision. The film 30 contains one or more types of hydrophobic, water-insoluble dyes, but the contact lens body 20 does not contain any hydrophobic, water-insoluble dyes. The concentration of the dyes in the film 30 is in the range of 100 to 5000 ppm. The one or more types of hydrophobic, water-insoluble dyes are uniformly dispersed throughout the film. That is, the concentration of the dyes is the same throughout the film. Uniform dispersion of the dye throughout the film is preferable to concentration of the dye on the film's surface. When the dye is introduced into the film by diffusion, diffusion depends on the concentration gradient, so high concentrations of dye remain near the film's surface, while relatively less dye is present in the center of the film. This type of concentration profile is undesirable compared to a film with uniform dye dispersion, as the dye on the film's surface is more likely to diffuse from the film. Furthermore, the diffusion of dye from the film alters the film's optical properties, which is undesirable.

[0010] The dye is stably embedded within the film 30, which is free from any organic solvents such as acetone or methanol. Contact lenses having a PVA film containing a water-insoluble narrow-band dye can be immersed in phosphate-buffered saline (PBS) or other similar contact lens storage solutions ("saline") at room temperature for more than one month (30 days), provided that there is no visible leaching of the dye into the saline solution. Furthermore, contact lenses having a PVA film containing a water-insoluble narrow-band dye can be immersed in saline maintained at 37°C for 14 days, provided that there is no visible leaching of the dye into the saline solution. To demonstrate that the dye is completely embedded within the PVA polymer, the PVA-dye film can be dissolved in water at approximately 50°C, but because the dye is completely embedded within the PVA polymer, the resulting solution will have the color of the dye, and no dye will precipitate in the solution.

[0011] A method for embedding hydrophobic, water-insoluble dyes in hydrophilic polymers such as PVA involves first dissolving the dye in some organic solvent, such as acetone or methanol, to create a dye solution. This dye solution in acetone or methanol is added to a dilute solution of PVA at about 30-35°C to produce an optically clear PVA-dye-water-solvent solution, i.e., a solution from which no precipitation of the dye or PVA occurs. An important requirement for producing this optically clear solution of the PVA solution with the dye is that both the dye solution and the PVA solution must be dilute solutions. Furthermore, acetone or methanol, as organic solvents, are particularly useful for creating dye solutions because neither solvent forms an azeotrope with water. This allows for the removal of substantially all of the organic solvent from the dye solution. For example, substantially all of either acetone or methanol can be removed from the PVA-dye-water-solvent solution by heating at low temperatures, for example, well below the boiling point of water. When the PVA-dye-water-solvent solution is dried on a substrate, the solvent is removed, leaving a thin PVA-dye film. Because this film was made from the dye solution, the hydrophobic, water-insoluble dye within the film is uniformly dispersed throughout the entire PVA film.

[0012] To remove substantially all of the acetone or methanol, an additional purification step is required. Although acetone and methanol form a non-azeotropic mixture with water, they will form hydrogen bonds with water, making removal difficult. To remove substantially all of the acetone or methanol, the water must be removed. In the first purification step, the PVA-dye-water-solvent solution is heated to about 65°C to remove its acetone or methanol. This reduces the solvent / water ratio to a very low value. With the removal of acetone or methanol, the water content will decrease relatively (azeotropically). By reducing the water content to less than 100 ppm, the acetone or methanol content will decrease to less than 1 ppm. This is possible because PVA is not soluble in acetone or methanol, and both of the organic solvents have a boiling point of 65°C or around 65°C and a vapor pressure 4 to 5 times that of water at 65°C. The first additional purification step is to completely dry the solution to form a solid by heating the solution to 70 to 75°C. This solid can be further divided to produce a powder. In a second additional purification step, the solid is heated at 60–85°C while flowing dry nitrogen or argon gas to entrain and remove substantially all of the remaining free water. The powder form of the solid will release free water at a faster rate. The non-hydrated solid can be stored therein or rehydrated. These purification steps enable the production of an aqueous solution of PVA containing a hydrophobic dye in solution, but with no detectable traces of the organic solvent used to prepare the dye solution.

[0013] Preferably, the PVA-dye aqueous solution is printed onto either the concave mold surface of the contact lens body or the convex surface of the contact lens body using pad transfer printing technology. The viscosity of the PVA-dye aqueous solution should be maintained at a viscosity of about 40 mPa-seconds (millipascal seconds), for example, above 30 mPa-seconds, to prevent the solution from flowing or drying unevenly. The target viscosity can be achieved by removing sufficient water from the PVA-dye aqueous solution before pad transfer printing. The PVA is printed onto the contact lens body in its unhydrated (dry) "tip" form. After printing, the PVA-dye aqueous solution is cured either by air drying to partially crosslink the PVA, or by UV irradiation if a photoinitiator is added to the solution to completely crosslink the PVA. The curing of the PVA-dye aqueous solution on the contact lens body forms the film 30 of the contact lens 10.

[0014] The peak absorption wavelength of the dye needs to be measured experimentally. The spectral characteristics of the dye are affected by its embedding in the PVA film, and in particular, the MW and DH of the PVA polymer film affect the peak absorption maximum and spectral linewidth of the dye. Knowing these spectral characteristics is essential to optimizing the design of the filter. The spectral characteristics of the dye were measured in PVA with various MWs and a high DH of 98%. It was observed that the peak wavelength, intensity, and full width at half maximum were stable in PVA with MWs exceeding 60,000 and DHs exceeding 98%.

[0015] A method for correcting or enhancing color vision in individuals with color blindness is to provide an optical filter that enhances the green-red color contrast. Such a filter can be made by using a narrowband dye having a peak absorption in the range of 560 nm to 620 nm. Preferably, the optical density spectrum of the filter containing the narrowband dye has an optical density greater than 1 at the peak absorption wavelength of the narrowband dye. For example, a PVA-dye film may provide such an optical filter if its optical density spectrum has a peak absorption in the range of 560 nm to 620 nm and that peak absorption has an optical density greater than 1. [Examples]

[0016] (Example 1) The narrow-band exciton dye ABS-574L was dissolved in methanol at a concentration of 0.12 g / L. 11.4 mL of the dye solution was added to 13 g of a 4% PVA solution maintained at 30°C, with a degree of hydrolysis of 89% and a molecular weight distributed between 20,000 and 200,000. This solution was stirred at 65°C for 1 hour. Thin films of the PVA-dye solution were prepared on glass slides and dried. These films exhibit exceptional optical quality, showing maximum absorption at 576 nm in optical spectra recorded in the range of 400–700 nm, and can be used as optical filters.

[0017] (Example 2) The narrow-band exciton dye ABS-594 was dissolved in methanol at a concentration of 0.49 g / L. 10.5 mL of the dye solution was added to 8.0 g of a 4% PVA solution, maintained at 30°C, with a degree of hydrolysis of 89% and a molecular weight distributed between 20,000 and 200,000. This solution was stirred at 65°C for 1 hour. Thin films of the PVA-dye solution were prepared on glass slides and dried. These films exhibit exceptional optical quality, showing maximum absorption at 599 nm in optical spectra recorded in the range of 400–700 nm, and can be used as optical filters.

[0018] (Example 3) The narrow-band exciton dye ABS-594 was dissolved in acetone at a concentration of 0.49 g / L. 10.5 mL of the dye solution was added to 8.0 g of a 4% PVA solution, maintained at 30°C, with a degree of hydrolysis of 89% and a molecular weight distributed between 20,000 and 200,000. This solution was stirred at 65°C for 1 hour. Thin films of the PVA-dye solution were prepared on glass slides and dried. These films exhibit exceptional optical quality, showing maximum absorption at 599 nm in optical spectra recorded in the range of 400–700 nm, and can be used as optical filters. (Example 4) An aqueous solution of ABS-594 PVA dye (from Example 2) was coated onto the center of the lens of a contact lens body in the form of a dry tip. Next, the lens was dried in an oven at room temperature. After drying, the contact lens was immersed in physiological saline solution for more than one month. After one month in physiological saline solution, no visible leaching of the dye into the physiological saline solution occurred, and the thin layer of PVA dye remained attached to the contact lens.

[0019] (Example 5) An aqueous solution of ABS-594 PVA dye (from Example 2) was coated onto the center of the lens of a contact lens body (Methafilcon A). Next, the lens was dried in an oven at room temperature. After drying, the contact lens was immersed in physiological saline solution maintained at 37°C for 14 days, in a state where there was no visible leaching of the dye. The thin layer of PVA dye remained stable and adhered to the center of the contact lens. (Example 6) A thin film of the PVA-dye aqueous solution of ABS-594 (from Example 2) was coated on a slide glass and dried at room temperature in an oven. When this PVA-dye film was immersed in water at 50 °C, the PVA-dye film dissolved in water. This solution was transparent and had the color of the dye. If the dye had not been embedded in the polymer, the water-insoluble dye would have precipitated from the solution and the solution would have been colorless, suggesting that the dye was still embedded in the PVA polymer.

[0020] (Example 7) The PVA-dye aqueous solution of ABS-594 (from Example 2) was stirred at 65 °C for 1 hour. Next, the solution was heated to 70 - 75 °C until all of its moisture was removed, and the PVA-dye became solid. Next, the solid PVA-dye was powdered and heated to 70 - 75 °C while flowing dried argon to remove all remaining moisture and any trace amounts of remaining methanol. This PVA-dye solid was stored and rehydrated with water. The rehydrated PVA-dye solution had no detectable traces of methanol.

Claims

1. A lens body including the surface and central portion, which does not contain water-insoluble dyes, and A film for coating the central portion of the surface of the lens body, comprising a water-insoluble dye embedded in polyvinyl alcohol (PVA) and uniformly dispersed throughout the film, and substantially free of organic solvents, Contact lenses containing [this ingredient].

2. A lens body including the surface and central portion, which does not contain hydrophobic dyes, and A film for coating the central portion of the surface of the lens body, comprising a hydrophobic dye embedded in polyvinyl alcohol (PVA) and uniformly dispersed throughout the film, and substantially free of organic solvents, Contact lenses containing [this ingredient].

3. The contact lens according to claim 1 or 2, wherein the dye is embedded in PVA so that it does not migrate outside the film after 30 days in physiological saline solution.

4. The contact lens according to claim 1 or 2, wherein the aforementioned surface is convex.

5. The contact lens according to claim 1 or 2, wherein the film contains two or more water-insoluble dyes.

6. The contact lens according to claim 1 or 2, wherein the dye is a narrow-band dye.

7. The contact lens according to claim 6, wherein the narrowband dye has a peak absorption in the range of 560 nm to 620 nm.

8. The contact lens according to claim 7, wherein the film is an optical filter having an absorption spectrum having an optical density greater than 1 at the wavelength of peak absorption.

9. The contact lens according to claim 6, wherein the dye is a metal complex salt dye.

10. The contact lens according to claim 1 or 2, wherein the film has a diameter between 4 mm and 7 mm, and the lens body has a diameter greater than 9 mm.

11. A method for manufacturing contact lenses, A step of preparing an organic solvent that does not form an azeotropic mixture with water, A step of dissolving a water-insoluble dye in the organic solvent to form a dye solution, The process involves mixing the aforementioned dye solution with an aqueous solution of polyvinyl alcohol (PVA) to form a PVA-dye solution. A step of removing substantially all of the aforementioned organic solvent from the PVA-dye solution to form an aqueous PVA-dye solution, The process of printing the PVA-dye aqueous solution onto the central part of the surface of a contact lens, and The process of curing the PVA-dye aqueous solution on the contact lens and forming a PVA-dye film on the surface of the contact lens. A method that includes this.

12. The method according to claim 11, wherein the organic solvent is methanol.

13. The method according to claim 11, wherein the organic solvent is acetone.

14. The method according to claim 11, wherein the surface is convex.

15. The method according to claim 11, wherein the dissolution step includes dissolving the second water-insoluble dye in methanol or acetone.

16. The method according to claim 11, wherein the water-insoluble dye is a narrow-band dye.

17. The method according to claim 16, wherein the water-insoluble dye is a metal complex salt dye.

18. The method according to claim 11, wherein the printing step includes printing the PVA-dye aqueous solution onto the central portion of the contact lens, the central portion of which has a diameter between 5 mm and 7 mm.

19. The method according to claim 11, wherein, before the printing process, water is removed from the PVA-dye aqueous solution until the viscosity of the solution exceeds 30 mPa seconds.

20. The curing step is to crosslink the PVA in the PVA-dye aqueous solution, according to the method of claim 11.

21. A film comprising a hydrophobic, water-insoluble dye embedded in polyvinyl alcohol (PVA), wherein the dye is uniformly dispersed throughout the film and the film is substantially free of organic solvents.

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