Unfortunately, as far as I could tell, there aren't very good studies on the topic - they're very limited in number of people and in length of time studied, or they don't measure a control group/baseline - which is a big problem because there is a surprisingly high prevalence of symptoms in the population even before lasik. This makes the data very hard to interpret.
E.g. [1] reports that 6 months after surgery, "41 percent of patients reported visual aberrations, with nearly 2 percent saying the symptoms presented 'a lot of difficulty' or 'so much difficulty that I can no longer do some of my usual activities.' But looking at the data from the PROWL-1 and PROWL-2 studies [2], table 3, 67% of patients had some visual symptom _before_ lasik surgery, with 3.3% / 7.5% having difficulty performing activities and 10.8% / 13.3% reporting "very" or "extremely" bothersome symptoms (again, before lasik). The prevalence of severe visual symptoms decreases 6 months after lasik. However, while some people go from severe symptoms to no symptoms, some of that is just due to regression to the mean (see note on test-retest in [2]), and there is also a substantial percentage of the population that goes from no symptoms to having some symptoms (which is the main thing I am trying to estimate).
Surveying some of the other literature [2][3][4], the overall pattern I saw was that pre-lasik the prevalence of dry eye and visual symptoms is about 60% of any severity, 5% severe, 5-10% moderate. Post-lasik they are about 50% any severity, 3% severe, 5% moderate. Overall they are less postop - but the question is how many people who were normal preop develop symptoms postop (minus how many people who were normal develop symptoms 6 months later without any lasik surgery). I haven't found good enough data to answer this with any degree of accuracy, other than an upper bound of <1% developing severe symptoms and <5% developing moderate symptoms. That isn't a very helpful upper bound to me - a 1% chance of permanent severe complications is a lot, and I think it's obvious that if the rate were that high we'd know about it. But from the data it appears plausible that the rate of developing long-lasting moderate complications is 0.1% - 1%, and the high end of that range is still a pretty substantial rate of complications. I think the actual rates are a lot lower, we just don't seem to have enough data to measure it better. I would love to see pointers to better studies, better analyses of the data, etc.
[1] https://www.nytimes.com/2018/06/11/well/lasik-complications-...
[2] https://jamanetwork.com/journals/jamaophthalmology/fullartic...