Several months ago I decided to take a chance and order some glasses from China. I did lots of research about several companies, read lots of reviews and saw video reviews on the YTube.
I had an up to date copy of my prescription from my optometrist which they are required to supply you with if asked. There is one very important measurement that some leave off the prescription called "pupillary distance". This is the distance in millimeters between your pupils, and is important for centering the optics in your glasses. They will give you this number if it is not on the script. You may measure this with a ruler, but the optometrist's electronic measurement is of course more accurate. A few mm's difference is inconsequential.
I chose
www.zennioptical.com, and have been very pleased. There are hundreds of frames in all materials and styles to choose from. They offer many, many frame styles, which if only single vision lenses are necessary, you can get for less than $15 delivered to your door. If you have kids who are hard on glasses I've just saved you a bunch of money. Their website is intuitive and even has a feature where you can upload a picture and "try on" different frame styles. Not perfect by any means, but gives you an idea.
The last pair of glasses I bought locally were lined bifocals in a nice frame. They were $330 out the door. I initially ordered two pair of glasses from Zenni, one clear and one tinted as sunglasses, both with more expensive "no-line" bifocals. They were both metal frame styles. Two pair delivered to my home? $88.00!!! I have since ordered three more pair for myself so I change them depending on what I might be doing that day. I have both metal and plastic framed styles, and all are 1st quality in materials and workmanship. No, they don't give me headaches either. My delivery time has consistently been between 2 and 3 weeks. I know it's not glasses in an hour, but at a sixth the price, who cares? I highly recommend them and will continue to use them for all my vision needs.