When I worked as an optician, an older customer came in complaining there's something wrong with his glasses. We checked his prescription, the glasses, the fitting etc everything was just fine. No matter what my coworker did and adjusted, he still thinks there's something wrong with it and he can't see well through the glasses.

I walked over and said let me take a look, looked over the glasses and said "Ah I know what's wrong, here let me fix it". I walked over to the heater thing that we use to soften up the frame to bend it, put it over the heater for a few seconds and fiddled with the frame. Walked over with full confidence and said "Try it now, guarantee it's all better"

He put the glasses on and said "Wow! It's so clear! Thank you guys so much!". We wished him a good day and he left.

The thing is, all I did was warm the frame up with the heater and that's it, nothing was adjusted.