I had my eyes tested a few weeks ago, long overdue and my first non-medical "indoors" since shielding ended. It was at a Specsavers branch.
Firstly, they keep strict guard on the door. Everything is buy appointment, you have to queue outside, and it is one-in one-out. Masks for everyone, staff and customers.
Once allowed if you have to go to the small waiting area, where there is a plastic screen between each seat. Pretty standard, into the pre-screening, back to the waiting area, then to the eye test. Everything gets cleaned between each customer so it is a bit slower.
So that was fine, and no worse than any medical appointment I have had. Arguably better, because the front of the hospital I regularly use has 'segregated' things in a way that forces people into smaller channels than when it was fully open plan. And masks there seem optional.
The only bit that felt uncomfortable was afterwards when I was looking at the glasses, as mine needed replacing anyway, as an older couple who were together were brought over by another assistant to show them the range. As this was in a corner it was too close for my liking, so I had to stand to the side and wait.
Thankfully the store was not too busy, as I say they are strict on the door, and the couple did not take lon to pick out a pair and leave me to myself again.
If you touch a pair of glasses you cannot put them back, you need to put them on the counter by the door, and someone will take them away to clean before putting them back on display. Once I had made my choice I was taken away to a desk for fitting and paying then the guard released me from the shop on parole until I my appointment to collect them.
So if where you are visiting is anywhere like my local Specsavers branch then you will have nothing to worry about. And the effect on my vision is amazing, to have kept waiting and using an older prescription would probably have been bad for them in the long term, so it is definitely better not to put it off.