[JohnFen]

A couple of years ago, I had a mishap with a moderately powerful laser, meant for engraving, grazing quickly across my left eye (I was wearing appropriate eye protection).

It wasn't until the next day that it started feeling like someone poured sand in it. It took a few days to return to normal.

[NotYourLawyer]

If you were wearing appropriate eye protection, this would not have been possible.

[JohnFen]

Appropriate eye protection does not provide 100% protection. Outside of a welder's helmet, maybe, even the best eye protection won't stop a reasonably powerful laser beam directed straight into your eye. It will reduce its intensity, though. The main benefit of wearing it is that even the diffuse, scattered light bouncing off of the walls is hazardous, and the eye protection stops that. Without it, you couldn't safely be in the same room as an operating laser even if the beam never comes near you.

If I had not been wearing it, there is an excellent chance that I would have suffered permanent vision damage. The eye protection I wore did exactly what it was supposed to do.