Turbsy
Any surgeon worth his salt would not even consider operating on a person until they reach about 23 - 25 years of age. This is because your vision does not 'settle' normally until your mid twenties; any if you had refractive surgery carried out before then, your eyes may change, and you would find yourself having to go through it again.
How long have you been at your current prescription? If you are worried, try preventitive methods, such as the Bates method, not using stronger lenses, etc.. etc.. Do a search - there have been plenty of threads on this topic
FD