Of course you can still ride a roller coaster but for safe reason,you should wait until the corneal is completely recovered.Significant trauma to the eye can cause the Lasik flap to dislodge but it rarely happens if you pay much attention to your eyes.
If you are involved in activities and sports where trauma to the face and eyes is very likely, such as a professional fighter, then Lasik may not be appropriate because of the high probability that you will suffer blows to the eye. Even if a problem is unlikely, it seems prudent to consider Lasik alternatives such as PRK, LASEK, and Epi-Lasik. These techniques, commonly known as surface ablation, do not require the Lasik flap. The patient will have a much longer vision recovery and more discomfort, but laser vision correction
without a flap is available.