This one actually surprised me. I have previously asked my optometrist if I could reuse my favourite (discontinued) frames when upgrading my lenses. They told me that it was impossible because frames suffer wear during years of use and that they would not last another couple of years. Maybe that was a sales ploy because…
…this optical chain now has an outlet where they sell secondhand frames. The frames are left in by clients (presumably for payment). The frames in good enough shape are cleaned and adjusted for new clients. This outlet also sells previous season collections and frames made from recycled plastic.
I donate all my old glasses frames to Optometrists without Borders for use in developing countries.