Contact lenses with surfaces having different softness

A method for producing contact lenses, comprising the step 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, epoxide groups, aziridine groups, vinylsulfone groups, thiol groups, and combinations thereof;
• (2) placing the contact lens precursor in a container in a position to ensure that the concave surface of the contact lens precursor faces up whereas the convex surface faces down;
• (3) dosing an aqueous solution into the concave surface of the contact lens precursor in an amount for immersing completely the contact lens precursor in the aqueous solution in the container while maintaining the concave surface facing up, wherein the aqueous solution has a room temperature and comprises at least one hydrophilic polymeric material, wherein said at least one hydrophilic polymeric material comprises second reactive functional groups each of which is capable of reacting with one first reactive functional group at a temperature above the room temperature to form a covalent linkage, wherein the second reactive functional groups are selected from the group consisting of carboxyl groups, amino groups, azetidnium groups, epoxide groups, aziridine groups, vinylsulfone groups, thiol groups, and combinations thereof;
• and
• (4) increasing the temperature of the aqueous solution with the contact lens precursor therein to a temperature of from about 35° C. to about 140° C. to form the contact lens.