As I've said, my question was about a specific odd lamp. I know how to edge-light a panel from the edge using LEDs and I've done so.
You may quibble about the term "edge lit" regarding this odd bulb, but I used the term to illustrate the principle. And just for the record, a hole does have an edge, and it's the exact same principle of internal reflections that makes it work.
It appears this type of bulb was for a very specialized application, and is no longer commonly available if it ever was. Question answered. Thank you.