Is it safe and feasible to buy eyeglasses online?

Not going to write much here. Here are some links I discovered in a search about buying eyeglasses online. I believe my eye doctor is doing right by me; but I can't afford 450.00 for a new prescription. My last new eyeglasses were built into the same old titanium frames, but they are moving on also. Is it safe to do this?

One of the most helpful sources was an article in the New York Times: Do it YOurself Eyeglass Shopping On the Internet. Before I found this, I noticed that many google hits were to online sales sites from the UK. The following are sites that seem at least interesting.

• 39-DollarGlasses.com
• Goggles4U
• FramesDirect.com
• Eyeglasses.com (now dysfunctional, but mentioned in the NYT article)

Essential link: GlassyEyes Blog. (Note later: This blog is amazing, with fine and useful comments. Great service to humanity.)

Now I have some fat to chew on.

Added Later: Here's another link: Eyeglass Liquidators . One post on the blog above mentioned they do trifocals, while others didn't.