I had red and very irritated eyes, to the point of beeing sensitive to light, for quite a few months after my initial diagnosis. I didn't know what was going on, since I didn't have eye closure problems or problems with tear production. At the end I figured out that indeed it was due to eye dryness, caused by reduced feeling in the cornea, due to my trigeminal nerve issues. What happens is that your eye becomes dry, and although you still have the capability for tear production your cornea cannot sense the dryness, so it does not send the correct signal. Your eye becomes extremely dry and irritated, then the other eye tries to compensate (remember all these systems are interconnected), and both eyes become irritated.
My optometrist confirmed my "self-diagnosis" and he gave me different eye-drops to try out. He also said that I should apply eye drops at least every 2 hours, to make sure that the eye remains moist. I finally settled with the Refresh Celluvisc twice a day (that many other people have recommended here), and Genteal gel drops in between. You need to experiment and figure out the type of product that works best for you.
(Oh, and eye-liner irritates my eye, so I have decided to avoid it).
Marianna