Looking for rubber flexible adult prescription eye glasses. Any advice?

Try asking your optometrist about sports frames, I had an Adidas pair that were similar to the ones Alva described. If I recall they weren't any more expensive than many of the other frames offered.

I don't know what metal my new prescription glasses are, but they can be twisted into a pretzel and survive. So strong and light are they that they didn't even offer me the usual insurance on them at Kaiser, saying "Nothing will happen to these". I absolutely love them. So visit any good place that sells glasses, and yes, they were more expensive. They were, however, covered in my Kaiser plan.
PS just looked down at Lealonnie's response, and yes, right, they are titanium. They are so light I am afraid I will bend over to flush the toilet and have them disappear off my face without my knowing it!

Flexon frames are titanium and you can purchase them, then have prescription lenses inserted at the ophthalmologists office.

https://www.flexon.com/

On the bottom of that website, you can punch in your zip code for a location in your area.

All I see in rubber is kids frames.

Good luck