I had it done when I was ~21 (I'm now 29). I had pretty bad Myopia (almost 6 diopters in each eye). It has its good and bad sides:
Good news:
- If you want to not wear glasses for Myopia, it's great! I no longer have Myopia.
- The procedure is quick, painless and recovery is very, VERY easy on the patient (itches like hell on first afternoon sleep it off and you'll get bloomy vision for a while but it goes away).
Catches I had to deal with:
- Most important catch: The procedure is not 100% guaranteed that you won't wear glasses for the rest of your life. While I no longer have Myopia, I do have light Astigmatism which I didn't have before. As people grow older their eyes naturally develop other issues (like the need for reading glasses when you're 50 which would happen with or without this surgery). This procedure is not a silver bullet for all eye-diseases. There is no such thing.
- Also, since the post-op is basically your cornea stuck to your eye by its sheer surface tension (they can't glue it back or stitch it back without completely ruining your eyes), you won't be able to do contact sports or go to the beach or swimming pools for at least 6 months. It's a time period in which you should be careful regarding the cleanliness of your eyes so things don't get infected.
- If you have really bad Myopia like I did, the surgery can cause a weird situation: since the surgery is only done on part of your cornea, at night your pupil might grow larger than the area in which the surgery was done. When you have really bad Myopia it will cause your eyes to see at the same time through the area that was fixed and through the area that wasn't fixed. In my case, I end up seeing a focused image with a light blurred image on top of it. Also causes pretty bad light flares at night. I'm told this is a non-issue if you don't have acute Myopia.
The last catch almost made me regret having Lasik done. But in the end, I've been glass-less for the past ~10 years now and I look better because of it. The next glasses I need won't be Hubble telescope lenses because of it.
Please make sure your doctor makes you aware of all the consequences you'll have due to this surgery (you won't have "scars" in the knife-to-the-gut sense, but you will have sight-related scars of various degrees depending on how acute your situation is).
After re-reading my post I see it makes it look like it's a bad thing. It's not. It's a good thing for a lot of cases. If you have any doubts or specific questions, reply to me and I'll get you more info/opinions