Contact lens with a hydrophilic layer
Embodiments of the technology relate to a contact lens having a core that is coated by a hydrogel layer, and to methods of making such a lens. The coated lens can include a rigid gas permeable contact lens. The coated lens can also include a hybrid silicone and rigid gas permeable contact lens. In one aspect, embodiments provide for a coated contact lens comprising a lens core with a water equilibrium constant of less than about 2% comprising an outer surface; and a hydrogel layer covalently attached to at least a portion of the outer surface, the hydrogel layer adapted to contact an ophthalmic surface, wherein the hydrogel layer comprises a hydrophilic polymer population of one or more species.
1. A method of making a hydrogel coated contact lens comprising:
reacting an outer surface of a lens core of a contact lens with a hydrophilic polymer population comprising a first polyacrylamide species and a second polyacrylamide species, wherein the first polyacrylamide species comprises a reactive amine moiety at a first portion that forms a covalent attachment to the outer surface of the contact lens; and
reacting the first polyacrylamide species with the second polyacrylamide species, wherein the second polyacrylamide species comprises a reactive carboxyl moiety that forms a covalent bond to a second portion of the first polyacrylamide species in a second covalent reaction, thereby forming a hydrogel coating on the lens core, wherein the first polyacrylamide species is at least partially cross-linked to the second polyacrylamide species.
2. The method of claim 1 , wherein the covalent attachment between the outer surface of the contact lens and the first portion of the first polyacrylamide species is formed by a first nucleophilic conjugate reaction.
3. The method of claim 1 , wherein the second covalent reaction is a second nucleophilic conjugate reaction.
4. The method of claim 1 , wherein the lens core is a soft contact lens.
5. The method of claim 4 , further comprising modifying the outer surface of the contact lens to form a plurality of reactive nucleophilic sites or a plurality of electrophilic sites on the outer surface.
6. The method of claim 5 , wherein the plurality of reactive nucleophilic sites or the plurality of electrophilic sites are selected from the group consisting of: hydroxyl, carboxyl, N-hydroxysuccinimide (NHS) ester, sulfo-NHS ester, imidoester, isocyanate, isothiocyanate, acylhalide, arylazide, p-nitrophenyl ester, aldehyde, and sulfonyl chloride.
7. The method of claim 5 , wherein the modifying step comprises exposing the outer surface of the contact lens to a gas plasma treatment.
8. The method of claim 1 , further comprising adding a bifunctional monomer or a polymer to a prepolymerization mixture used to form the contact lens.
9. The method of claim 8 , wherein the bifunctional monomer or the polymer provides additional nucleophilic or electrophilic reactive sites on the outer surface of the contact lens.
10. The method of claim 9 , wherein adding the bifunctional monomer or the polymer to the prepolymerization mixture includes one or more of: pH adjustment, plasma activation, light activation, activation of the prepolymerization mixture, wet activation, and adding a monomer that reacts with the contact lens that still leaves reactive sites.
11. The method of claim 1 , wherein the lens core comprises polysiloxane.
12. The method of claim 1 , wherein the lens core is substantially free of polysiloxane.
13. The method of claim 1 , wherein the lens core is a hydrogel core.
14. The method of claim 1 , wherein the hydrogel coated contact lens has an oxygen transmissibility (DK/t) of greater than 200.
15. The method of claim 1 , wherein the hydrogel coating comprises a thickness between about 1 nm to about 50 nm.
16. The method of claim 1 , wherein the lens core comprises an elastic modulus of less than about 1.8 MPa.
17. The method of claim 1 , wherein the lens core comprises an equilibrium water content of less than about 1%.
18. The method of claim 1 , wherein the lens core comprises an equilibrium water content of less than about 0.5%.
19. The method of claim 1 , wherein the lens core comprises an oxygen transmissibility (Dk/t) of greater than about 200.
20. The method of claim 1 , wherein the lens core comprises about 50% to about 100% silicone by weight.