there is a building just around shanghai railwaystation which sells a lot of glasses, lenses, etc.

but better bring a good spoken chinese with u

There is a specialized contact lens web store for foreigners in China, you can check it out at www.lensproxy.com

Pretty much any optician will have some, I've even been able to find decent Acuvue lenses in my small city. Just bring in the boxes and show them the side, they can find the same ones for you (though possibly a diffrent brand).

I haven't tried lensproxy yet but they have a better variety, I think I'll be buying my next box from them because they have the good silicon hydrogels I like.