dry eyes are very common for PALS because as the disease progresses, they tend to blink less and less. My PALS sometimes has difficulty closing his eyes all the way, and sometimes they wont stay closed! Also, with the less blinking, if the PALS is sitting very close to a computer screen or even a tv, it can cause dry patches on the eyeballs, which i believe is permanant.
So for all you PALS out there, when youre at your computers, remember to blink often and take breaks. Artificial tears work well, as Iris said. Lots of times Ray with sit with a wet rag strapped over his eyes for a couple of hours. We also tape his eyes shut at night because they tend to pop open when he is trying to sleep.