Good guess. It depends on how thick your cornea was to begin with and how strong your original prescription was. Some people can only have one treatment. Basically, the goal of LASIK is to make you less dependent on glasses/contacts. There's no way to guarantee your prescription will never change again following LASIK. But it should take you back to zero, and most adults don't change that much, so you should never end up as bad as you were before surgery. I was taught a rule in school called the $6000 rule. It said that the eye can endure only about $6000 worth of surgery before it shrivels up and dies . That may need some correction for inflation since I graduated in 1995, but the point is that your eye can only stand so much surgery. Look at Michael Jackson's face if you want to see what too much surgery can do to you.