Hard to say. The worry is if the ink is of a kind that reacts (soaks in) to plastic (the screen).
Spray on polish might work... it's pretty good at disolving many chemicals, try a little on a clean duster.
The other thing that comes to mind is WD40, again a little on a cloth and try.
If the ink has soaked in though then nothing is going to work without making a mess of the finish on the screen.