Anne Jackson wrote:
The message from "R D S" contains these words:
"Graham." wrote:

What's the best way of locking them in that won't invalidate
your guarantee from the optician?
Why don't they do this for us?
If I don't tighten the screws on my varifocals on a
weekly basis the RH lens drops out!

Summats wrong with them then, is the joint fully closing
when you tighten them?

As someone else said, loctite, or if you have some handy
a dab of touch up paint on the screw head with a bit of
overlap should stop it turning.

Try using _both_ hands, to remove your glasses. You said it's
the RH lens that 'pops out' - chances are you're right-handed!

Seconded. Loctite and a bit of care when putting them on and taking them
off. My bird used to work repairing glasses and most frames end up knackered
because people stretch at the hinges taking them off with one hand.