There are a few things that I did not mention about getting any eyeglasses via online or mail order. If you have a straight forward prescription then you will have no problems with getting good quality glasses from any number of vendors.
Mine was pretty straight forward. I needed bifocals and I have a slight astigmatism in my left eye. I knew my pupillary distance (the distance between the pupils.) For the record I ordered a PD of 60 even though my centered PD was 30 and 30.5. Not quite equal but within the range necessary so not to worry about causing issues with vision.
I also cheated and got an idea of what would fit in terms of frames. This means going to a local business and trying on frames to get an idea of what would fit and what would not. Then taking those numbers and finding a corresponding size on Zenni.
However, if I were to have a prescription that necessitated something outside the ordinary then I would not hesitate to avoid mail order or internet ordered glasses. Spending money on good glasses will prevent problems in the future. I happen to be in the situation where I can get quality at a very good price.
Yes it is not local but local is too expensive right now.