Cool, that's a great hacker approach! Fine-tuning like this isn't economical for eye doctors, and 99.5% of the population isn't interested but it will give you the best results.

Just checking because it looks like you're from '79 and talk about drifting vision: you know about presbyopia and accommodation? You might need multi-focals.

It’s cranial pressure and sixth nerve palsy. As my cranial pressure goes up my horizontal eye nerves weaken causes vision to go double.

Prism glasses fixes this. But it’s a completely different power. +3 goes to -1 or anything in between.

As pressure goes down it reverts. Medication or activity can drop or raise it in an hour or less.

Wow, that's more serious than what I was expecting and beyond my limited ophthalmology knowledge. Glad that you managed to find a solution.

I need a different prescription depending on how wide my pupils are. I have separate glasses for night driving. Discovered this after a consultation with a real ophthalmologist, not an optometrist. They can dilate your pupils with eyedrops to take what’s called a wet refraction.

OMG. You may end up having changed my life - it had never occurred to me that a) this was a thing I could just up and buy, and b) it really isn’t that expensive.

No more worrying that I’m about to stick myself with the wrong prescription because the optician (yes, that’s who measures you for glasses in Germany) or I lost patience trying to find the boundary between spherical and cylindrical correction, or doing this at the wrong time of day, all for less than a pair of glasses costs.

Any brand recommendations?

I got a 200 dollar set that I’m happy with. It comes with “glasses” to attach the lenses to. But suggest ordering one that is more adjustable. The one it came with doesn’t adjust for distance between eyes.