Get yourself some Maas metal cleaner and with a PRISTINE CLEAN microfibre cloth apply a 5cm worm of the stuff to the screen and GENTLY wipe it smoothly side to side and top to bottom. Then GENTLY wipe off and polish.
The lavender version smells great.
Oh, and the screen becomes silky smooth and very sensitive.
re-apply as needed.
Do this with screen off. If it becomes unresponsive immediately afterwards don't panic, it all comes back, keep polishing.