I need to change my glasses, and I saw some online store has really cheap ones, can save a lot compare with real store. How to know if the quality is ok since I can not try them on? Any suggestion?

I am entangled between  http://www.framesdirect.com/ and http://www.firmoo.com/promo-free-glasses-samples.html, 

I have Firmoo code firmooff0313 (I can share) , so I can get one for only 11.9$, but framesdirect seems good too (see from the reviews), so did anyone have bought from them?