I had to have a correction because one of my eyes was overcorrected more than the other--I was 20/20 in both eyes but there was a discrepancy in perceived object size between my left and right eyes, so I had to have the right eye redone. No big deal, but it sucked because it was right in the middle of the semester.
I had the custom surgery done, and I seriously think I can see better during low light conditions (dawn/twilight, which is what it's for) than I could with contacts.
Went from 20/600 or thereabouts to at least 20/20.