Method for making embedded hydrogel contact lenses

A method for producing embedded hydrogel contact lenses, comprising the steps of:

• (1) obtaining an insert mold, wherein the insert mold comprises a male insert mold half having a first molding surface and a female insert mold half having a second molding surface are configured to receive each other such that an insert-molding cavity is formed between the first and second molding surfaces when the female insert mold half is closed with the male insert mold half;
• (2) dispensing an insert-forming composition in the female insert mold half, wherein the insert-forming composition comprises (i) at least one polymerizable material comprising one or more vinylic monomers and one or more vinylic crosslinkers, (ii) at least one first free-radical initiator, and (iii) at least one iniferter;
• (3) closing the female insert mold half with the male insert mold half to form a first molding assembly comprising the insert-forming composition within the insert-molding cavity of the insert mold;
• (4) curing thermally or actinically the insert-forming composition in the insert-molding cavity of the first molding assembly to form an insert that is made of a first crosslinked polymeric material comprising iniferter moieties covalently attached thereto and has a diameter of up to 13 mm, a front surface, an opposite back surface, and a central axis, wherein the insert is smaller than an embedded hydrogel contact lens containing the insert therein in any dimension;
• (5) obtaining a lens mold and a lens-forming composition, wherein the lens mold comprises a male lens mold half having a third molding surface and a female lens mold half having a fourth molding surface are configured to receive each other such that a lens-molding cavity is formed between the third and fourth molding surfaces when the female lens mold half is closed with the male lens mold half, wherein the lens-forming composition comprises at least one second polymerizable material and a second free-radical initiator;
• (6) in no particular order, placing the insert obtained in step (4) in the female lens mold half at a desired position in a way to ensure that the central axis of the insert coincides with the central axis of the female lens mold half and dispensing the lens-forming composition in the female lens mold half, wherein the insert is immersed in the lens-forming composition;
• (7) closing the female lens mold half with the male lens mold half to form a second molding assembly comprising the lens-forming composition and the insert immersed therein in the lens-molding cavity of the lens mold;
• (8) curing thermally or actinically the lens-forming composition while simultaneously initiating iniferter-induced graft polymerization of the lens-forming composition at and near the surface of the insert in the lens-molding cavity of the second molding assembly to form an embedded hydrogel lens precursor that comprise a bulk hydrogel material formed from the lens-forming composition and the insert embedded in the bulk material, wherein the bulk hydrogel material is a second crosslinked polymeric material that is covalently linked to the first crosslinked polymeric material at iniferter moieties located at and near the surface of the insert through covalent linkages formed from the iniferter-induced graft polymerization;
• (9) separating the lens mold obtained in step (8) into the male and female lens mold halves, with the embedded hydrogel lens precursor adhered onto a lens-adhered lens mold half which is one of the male and female lens mold halves;
• (10) removing the embedded hydrogel lens precursor from the lens-adhered lens mold half;
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• (11) subjecting the embedded hydrogel lens precursor to post-molding processes including a hydration process and one or more other processes selected from the group consisting of extraction, surface treatment, packaging, sterilization, and combinations thereof to form the embedded hydrogel contact lens that has a minimized susceptibility to delamination due to the presence of covalent linkages between the bulk hydrogel material and the insert embedded therein.