Take the screen and put it on the tip of your pinkie and apply some pressure to form somewhat of a bowl shape (you can use the end of a rounded pen as well), from there slowly wedge the screen into the Gong until it catches the ridge of where the glass holds the screen in place, good luck
I have been using eye drops daily for the past ~8 years and have yet to notice any side effects (knock on wood). As people have already mentioned, Rohto's are great