The branch I visited was inside the Sainsbury's megastore at Sydenham. They had closed the shutters across the shop, with a gap at one end, blocked by a table, where they asked you your business before admission. All the staff wore masks and gloves, the equipment was wiped down before use and there was a box for glasses you'd tried on, so they could be disinfected before they went back on the shelf.
"Do you wear your glasses for driving?" I was asked. Friends, I could barely recognise a car without my glasses on, let alone drive one.
It turned out my prescription hadn't changed as much as I thought it had, but my lenses were pretty scratched (and the earpieces a bit chewed) so the optometrist advised me to get a new pair, which I wanted to do anyway.
I prowled around for ages unable to find anything I liked, then spotted a pair in the box of tried-on frames, so the sales assistant cleaned them for me and they were great. Thanks, person who tried them on and rejected them!
They were one of the most expensive pairs in the shop, inevitably.