Silicone hydrogel contact lenses

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

curing a polymerizable composition comprising a siloxane monomer and a hydrophilic monomer to form a cured silicone hydrogel contact lens;

hydrating the cured silicone hydrogel contact lens;

extracting the hydrated silicone hydrogel contact lens with an extraction liquid comprising an aqueous solution of a single organic solvent selected from ethyl lactate, or ethylene carbonate, or propylene carbonate, or propylene glycol, or butanediol, to make an extracted silicone hydrogel contact lens;

removing organic solvent from the extracted silicone hydrogel contact lens to make an ophthalmically-acceptable lens; and

packaging the ophthalmically-acceptable lens,

wherein:

the extraction liquid and any other liquid used for processing the cured or hydrated silicone hydrogel contact lens has a flash point of at least 50° C.; and

the hydrated silicone hydrogel contact lens has surface distortions that are reduced after the extraction and/or removing step.

2. The method of claim 1 , wherein the extraction liquid comprises from about 20 wt. % up to about 80 wt. % of the organic solvent.

3. The method of claim 1 , wherein the hydrating comprises contacting the cured silicone hydrogel contact lens with water at a temperature of at least 50° C.

4. The method of claim 1 , wherein the polymerizable composition is cured in a mold assembly which is demolded after curing to provide a mold assembly half with the cured silicone hydrogel contact lens adhered thereto, and wherein the hydrating step comprises delensing the cured silicone hydrogel contact lens from the mold assembly half by contacting the hydrogel and mold assembly half with an aqueous liquid free of organic solvent.

5. The method of claim 1 , wherein the removing step comprises rinsing the extracted silicone hydrogel contact lens in room temperature water.

6. The method of claim 1 , wherein the polymerizable composition is free of an organic solvent.

7. The method of claim 1 , wherein the organic solvent is ethyl lactate and wherein formation of ethanol in the extraction liquid is monitored by pH and/or refractive index measurement.

8. The method of claim 1 , wherein the hydrophilic monomer is N-vinyl-N-methyl acetamide (VMA), or N-vinyl pyrrolidone (NVP), or 1,4-butanediol vinyl ether (BVE), or ethylene glycol vinyl ether (EGVE), or diethylene glycol vinyl ether (DEGVE), or any combination thereof.

9. The method of claim 7 , wherein formation of ethanol in the extraction liquid is monitored by pH and/or refractive index measurement.

10. The method of claim 1 , wherein the organic solvent is selected from ethyl lactate, or ethylene carbonate, or propylene carbonate, or butanediol.