For a while now, my vision in one eye has never been quite right even with glasses - maybe 6/9 or so. I know there are many possibilities when this happens, and there was no obvious explanation why it couldn't seem to be corrected as fully as my other eye. It didn't really seem to be much of a problem as my other eye was fine, although possibly starting to have similar issues now. New optician suggested possible issues with binocular vision and that maybe prisms could make vision more comfortable/better in that case.
When I look up prisms, there is a lot of information about using them to treat symptomatic double vision, and needing to report them to the DVLA to be approved before you can continue to drive. But it's not clear whether you'd have to report prisms and wait for an outcome if they are just prescribed for potential subtle binocular vision/vergence issues if you don't actually have any double vision. Anyone know? (and I know it's different if it's something you've had all along, before you started driving). He didn't prescribe them this time in the end but it's still a possibility.
As a side question, do opticians see complex patients as 'heartsink' patients when they come in or join the practice? There are various other issues with my eyes too, and I know it means more time for the original sight test, more re-tests, more time checking glasses, more re-makes trying to get them right, more return visits for checking other eye symptoms, conditions etc. Maybe it is interesting to see patients like this in the mix and they enjoy trying to solve the puzzle of what's wrong, or maybe it's just really irritating for them to have people that keep coming back saying things aren't quite right, especially as it must end up eating into the profit they make on the glasses/contacts. I feel guilty for not paying for all the extra time they spend and repeat visits, and I'd feel less bad about trying to fix the issues if I were charged each time. On the other hand, my glasses already cost a fortune and I can't really afford to pay each time so I might not go back then either.