I woke up in the middle of the night and when I opened my eyes it felt like the cornea was being torn or scratched really bad. My eye has done this two to three times over the last couple months. It leaves my eye feeling really scratchy and painful for several hours afterward but eventually goes away. I am a contact lens wearer and think it has something to do with that and / or dry eye syndrome. I have not regularly used artificial tears. Maybe only a couple of times...