I have been looking through the literature on lasik complications since I am considering lasik and there were several articles recently such as [1] which goes into a lot more detail. There are a lot of temporary complications/side effects (e.g. a few months), but what I'm most interested in understanding is the risk of lasik causing serious, long-lasting or permanent complications. The main ones discussed in these articles are visual artifacts (halos, starbursts, etc.) and dry eye (which at the extreme end means constant intense pain).
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.
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...
[3] https://www.ncbi.nlm.nih.gov/pubmed/25896684
[4] https://www.ncbi.nlm.nih.gov/pubmed/27373395