Contact lenses with softer lens surfaces
The invention is related to a coated contact lens, especially a coated silicone hydrogel contact lens, which comprises an anterior surface, an opposite posterior surface, and a layered structural configuration from the anterior surface to the posterior surface. The layered structural configuration comprises an outer anterior surface hydrogel layer, an inner layer, and an outer posterior surface hydrogel layer. The inner layer is a lens bulk material. The coated contact lens has a superior lens surface softness and a good lens surface hydrophilicity while optionally having a desirably-lower polyquaternium-1 uptake.
1. A method for making coated contact lenses, comprising the steps of:
(1) obtaining a contact lens precursor which has a concave surface and an opposite convex surface and comprises a lens bulk material and first reactive functional groups on and/or near the anterior and posterior surfaces, wherein the first reactive functional groups are selected from the group consisting of carboxyl groups, amino groups, azetidnium groups, and combinations thereof; and
(2) autoclaving the contact lens precursor immersed in a packaging solution in a sealed lens package at a temperature of from about 115° C. to about 125° C. for approximately 20-90 minutes to form a coated contact lens having a hydrogel coating thereon, wherein the packaging solution comprises (a) at least one hydrophilic polymeric material and (b) a pH-buffering system for maintaining pH of the packaging solution, wherein the pH-buffering system comprises at least two buffering agents which are phosphates, wherein the total concentration of all buffering agents present in the packaging solution is from about 10 mM to 70 mM, wherein the packaging solution has a room temperature and a pH of from about 6.9 to about 7.3, wherein the totally concentration of all ions present in the packaging solution is less than 201 mM, provided that the total concentration of all ions each having two or more charges in the packaging solution is less than 50 mM, wherein said at least one hydrophilic polymeric material comprises second reactive functional groups which are selected from the group consisting of carboxyl groups, amino groups, azetidnium groups, and combinations thereof, wherein the hydrogel coating is covalently attached onto the contact lens precursor through covalent linkages each formed between one first functional group and one second functional group, wherein the coated contact lens has a superior lens surface softness as measured by an averaged indentation depth at 5 KPa compression pressure of at least 550 nm with using an indenting probe having a tip radius of 10 μm and a stiffness of 0.5 N/m in a nanoindentation test.
2. The method of claim 1 , wherein the contact lens precursor inherently comprises first reactive functional groups on and/or near the anterior and posterior surfaces, or wherein the contact lens precursor is obtained by subjecting a preformed contact lens to a surface treatment to have the first reactive functional groups.
3. The method of claim 2 , wherein if the first reactive functional groups are carboxyl groups and/or amino groups, then the second reactive functional groups are azetidinium groups; wherein if the first reactive functional groups are azetidinium groups, then the second reactive functional groups are carboxyl groups, amino groups, or combinations thereof.
4. The method of claim 3 , wherein the packaging solution additionally includes one or more non-ionic tonicity-adjusting agents and are used to adjust the osmolality of the packaging solution to a value from about 200 to about 450 mOsm/Kg, wherein said one or more nonionic tonicity-adjusting agents are glycerol, propylene glycol, polyols, mannitol, sorbitol, xylitol, or mixtures thereof.
5. The method of claim 4 , wherein said at least one hydrophilic polymeric material is a branched hydrophilic polymeric material comprising the second reactive functional groups.
6. The method of claim 2 , wherein the first reactive functional groups are carboxyl groups and/or amino groups whereas the second reactive functional groups are azetidinium groups.
7. The method of claim 6 , wherein the packaging solution additionally includes one or more non-ionic tonicity-adjusting agents and are used to adjust the osmolality of the packaging solution to a value from about 200 to about 450 mOsm/Kg, wherein said one or more nonionic tonicity-adjusting agents are glycerol, propylene glycol, polyols, mannitol, sorbitol, xylitol, or mixtures thereof.
8. The method of claim 7 , wherein said at least one hydrophilic polymeric material is a branched hydrophilic polymeric material comprising the second reactive functional groups.
9. The method of claim 8 , wherein the branched hydrophilic polymeric material comprises azetidinium groups and is a partial reaction product of at least one azetidinium-containing polymer with at least one hydrophilicity-enhancing polymer having at least one carboxyl, primary amine, secondary amine, or thiol group.
10. The method of claim 9 , wherein the contact lens precursor inherently comprises comprise first reactive functional groups on and/or near the anterior and posterior surfaces.
11. The method of claim 9 , wherein the contact lens precursor is obtained by subjecting a preformed contact lens to a surface treatment to have the first reactive functional groups.
12. The method of claim 11 , wherein the surface treatment is a plasma treatment; a chemical treatment; a chemical vapor deposition; grafting of compounds having at least one first reactive functional group onto the surface of the preformed contact lens; graft-polymerization of vinylic monomers each having at least one first reactive functional group onto the surface of the preformed contact lens; layer-by-layer (“LbL”) deposition of one or more hydrophilic materials having first reactive functional groups on the surface of the preformed contact lens; covalently attachment of one or more hydrophilic polymeric materials having first reactive functional groups onto the surface of the preformed contact lens; or a combination thereof.