So, there are 3 generations of laser eye surgery. The first generation of laser eye surgery was initially performed in the early 1990s and this type of laser eye surgery was called PRK, or LASEK. In PRK, or LASEK, the laser is applied directly to the surface of the eye. This results in quite an amount of discomfort and watering and a slow visual recovery.
For that reason, a second generation of laser eye surgery, called LASIK, was developed. In LASIK there are 2 steps to the procedure. The first step is to use a femtosecond laser to create a thin flap on the surface of the cornea, which is peeled open. The second step is to use a second laser, called an Excimer laser, to sculpt the glasses prescription into the corner, thereby correcting the vision. The flap is then placed back in place and the vision recovers rapidly, within 24 hours, with minimal discomfort and only mild watering from the eye.
The usual recovery after SMILE is equally rapid as with LASIK
The third generation of laser eye surgery is called ReLEx SMILE. This is effectively the same principle as LASIK, except it is performed through a tiny 3mm keyhole incision. There is no flap and in contrast with LASIK, there is a 24mm incision to create the flap. The usual recovery after SMILE is equally rapid as with LASIK and again, there are minimal symptoms of discomfort and rapid visual recovery.