Method for making coated silicone hydrogel contact lenses

A method for producing coated silicone hydrogel contact lenses each having a hydrogel coating thereon, comprising the steps of:

• (1) obtaining a preformed silicone hydrogel contact lens comprising a silicone hydrogel material as lens bulk material;
• (2) forming a base coating on the preformed silicone hydrogel contact lens according to a coating process to form a treated silicone hydrogel contact lens having the base coating thereon, wherein the solution-coating process comprises dipping the preformed silicone hydrogel contact lens in a bath of a coating solution for a coating period of time, wherein the coating solution has a pH of from 0 to about 4.5 and comprises from about 0.01% to about 2.5% by weight of a polyanionic polymer, wherein the polyanionic polymer is a homo- or copolymer of acrylic acid or C1-C3 alkylacrylic acid, wherein the coating solution is prepared by dissolving the polyanionic polymer is a mixture of water and one or more organic solvents, an organic solvent, or a mixture of one or more organic solvent;
• (3) rinsing the treated silicone hydrogel contact lens obtained in step (2) with a mixture of water and one or more organic solvent miscible with water for a first rinsing period of time;
• (4) rinsing the treated silicone hydrogel contact lens obtained in step (3) with a buffered saline for a second rinsing period of time, wherein the buffered saline has a pH of from about 7.6 to about 8.5 and a salt concentration of at least 20 mM;
• and
• (5) heating the treated silicone hydrogel contact lens having the base coating thereon in an aqueous solution having a pH of from about 6.5 to about 9.5 and including a water-soluble, thermally-crosslinkable hydrophilic polymeric material at a temperature from about 60° C. to about 140° C. to form a coated silicone hydrogel contact lens that has a hydrogel coating thereon, polyquaternium-1 uptake of less than 0.4 micrograms/lens, and a friction rating of about 2 or lower after 30 cycles of digital rubbing test, wherein the hydrogel coating is covalently attached onto the base coating.