I've know a few who had it done and a couple of years later required glasses again to correct their near-sightedness.

In other instances they can't always achieve 20/20 or better. Some folks end up with vision slightly worse than 20/20.

By the way, not sure if others know this but here's what 20/20 indicates.

Let's say your vision is 20/300.

What a person with normal eye sight (20/20) sees clearly at 300 feet, you see clearly at 20 feet. In other words, the clarity you have at 20 feet will be the same clarity a person with 20/20 vision has at 300 feet.