I had strabismus surgery 3 weeks ago on my right eye, which had drifted up and out. They operated on 2 of the muscles, to bring it down and in again.
At this point it looks like the surgery was a good success, even though now if I'm using my right eye my left one drifts up. However if I'm using my left eye it looks completely straight, which was better than before where whichever eye I was using the other one would drift. At least I have the option of looking straight now hehe.
I've had strabismus all my life, being born with both eyes turning inwards and having 4 surgeries when i was younger. Going by my own experience, it would be likely that your eye will drift out over time. That's pretty much what happened to me, after having inward turning eyes fixed, in years they ended up being outward turning eyes! Even now after the latest surgery I have been told it probably won't last. But by lasting my doc said she's hoping for a few decades and I would be very happy with that!! My surgeries from when I was little pretty much lasted for 15+ years before it got really bad (I'm 25 now).
The latest surgery I had was done under general anesthetic, with the outer muscle done as an adjustable suture, which the doc "tweaked" when I had woken up from the surgery. I went into surgery at 9:45am and was ready to go home not long after midday. I am located in Melbourne, Australia.
I was feeling pretty wonky in the head for at least a week, as my brain had to get used to the new position. I was getting a bit of double vision but that has pretty much gone now. I was advised to take a week off work, which was needed as I definitely wasn't up to driving or concentrating on work in that time. I didn't find the recovery very painful, more just annoying as the eye was quite gunky and blurry for a while. Not to mention having to put in eye drops 4 times a day for a week. I still have a bit of redness even 3 weeks later, but apart from that it's all pretty much back to normal.
Anyway that's just my experience. The recovery isn't too bad, only really for the first 4-5 days I found it particularly bad. I found it definitely worth it though, even though I have been told it won't be permanent I am expecting it will now be like this for quite a few years to come.