Method of manufacturing silicone hydrogel contact lenses having reduced rates of evaporation

1. A method of manufacturing a silicone hydrogel contact lens comprising:

a) providing a contact lens mold comprising a first lens-forming surface to mold one side of said hydrogel contact lens and a second lens-forming surface to mold opposite side of said hydrogel contact lens, wherein the first lens-forming surface has a higher polarity than the second lens-forming surface;

b) curing a polymerizable composition comprising at least one siloxane monomer and at least one hydrophilic monomer in the contact lens mold to form a polymeric lens body;

c) hydrating the polymeric lens body to provide a silicone hydrogel contact lens having a first surface formed by the first lens-forming surface of the contact lens mold and a second surface formed by the second lens-forming surface of the contact lens mold; and

d) sealing the silicone hydrogel contact lens in a package,

wherein the silicone hydrogel contact lens has a lower ionoflux and/or a lower evaporation rate than a control contact lens manufactured by an identical method except that the second lens-forming surface has the same polarity as the first lens-forming surface, and wherein after the curing step the polymeric lens body is subjected to a surface modification treatment to increase wettability of the second surface of the silicone hydrogel contact lens, and the surface modification treatment is selected from air plasma, or UV-ozone, or corona discharge.

2. The method of claim 1 , wherein the first lens-forming surface has a contact angle that is at least 20° lower than the contact angle of the second lens forming surface.

3. The method of claim 1 , wherein the first lens-forming surface is polar and the second lens-forming surface is non-polar.

4. The method of claim 1 , wherein the first lens-forming surface comprises a non-polar thermoplastic material coated with a hydrophilic coating, and wherein the second lens-forming surface comprises the non-polar thermoplastic material in the absence of any polarity-enhancing surface coating or treatment.

5. The method of claim 1 , wherein the at least one hydrophilic monomer is a hydrophilic vinyl-containing monomer.

6. The method of claim 1 , wherein the polymerizable composition comprises a total amount of hydrophilic vinyl-containing monomer of about 20 wt) % to about 60 wt) % based on the total weight of all polymerizable ingredients in the polymerizable composition.

7. The method of claim 5 , where the at least one hydrophilic vinyl-containing monomer is selected from N-vinylacetamide, N-vinyl-N-methylacetamide (VMA), N-vinyl-N-ethylacetamide, N-vinyl-2-pyrrolidone (NVP), N-vinylformamide, N-vinyl-N-ethylformamide, N-vinyl isopropylamide, N-vinylcaprolactam, N-vinyloxycarbonyl-L-alanine, 1,4-butanediol vinyl ether, ethylene glycol vinyl ether, diethylene glycol vinyl ether, a poly(ethylene glycol) vinyl ether, or any combination thereof.

8. The method of claim 7 , wherein the hydrophilic vinyl-containing monomer is VMA, or NVP, or a combination of both VMA and NVP.

9. The method of claim 1 , wherein the polymerizable composition comprises a total amount of siloxane monomer of about 30 wt) % to about 60 wt) % based on the total weight of all polymerizable ingredients in the polymerizable composition.

10. The method of claim 1 , wherein the contact lens has an equilibrium water content (EWC) of at least 40%.

11. The method of claim 1 , wherein the contact lens has an ionoflux of less than 0.5×10 −3 mm 2 /min, and the control contact lens has an ionoflux of at least 1×10 −3 mm 2 /min.

12. The method of claim 1 , wherein the contact lens has a lower evaporation rate from 2 to 4 hours than the control lens, wherein the evaporation rate measured at 48-50% RH and 21° C.) to 23° C.

13. The method of claim 12 , wherein the evaporation rate is less than 15 mg/h.

14. The method of claim 1 , wherein the first surface of the contact lens has a sessile drop contact angle that is less than that of the second surface of the contact lens.

15. The method of claim 1 , wherein the contact lens has a back surface having a contact angle of less than 45°.

16. The method of claim 1 , wherein the first surface of the contact lens is a back surface.

17. The method of claim 1 , wherein the first surface of the contact lens is a front surface.