Sorry to hear those peepers are playing with you again, did the optician suggest further investigation as to why they're changing so much? My peepers are quite the naughty little blighters and my visual acuity is considered fluid (read medical speak for changes a lot) but I know why, it's the Ehlers Danlos ligament laxity issue, so essentially I have overly mobile eyeballs, it doesn't have much impact on one eye because he's tightly nestled, but the other one is smaller than the socket so he just has his own personal disco. Oh what a picture I paint, I feel I should point out its invisible from the outside and I don't look like cyclops (much). Obviously you don't have EDS so it won't be the same thing, but there are other things (including diabetes my rheumatologist told me) that can cause ligament mobility, have they investigated any of that at all?
If it helps I understand how frustrating it is, I've got similar visual acuity (although my bad eye isn't as bad), and disco eyeball drives me mental with his I can see, oops no I can't see routine. I had a contact lense for disco eyeball as well as glasses for a while which was great but disco eyeball moved too much and that caused abrasions. I had 12 months of accelerated issues after diagnosis, which is when I also learned that stress and anxiety also plays a part in ligament mobility (explains why I always had to change prescriptions when doing exams at school, college, Uni now that I think of it). There's nothing much to be done for my issues, genetic and that's that, but it does help to know what's going on and why, if for no other reason than knowing you're not losing your mind. Hope they manage to shed some light 🙂