As Dr. O says, do have yourself checked out by an opthalmologist. If he does not find blepharitis, there are other factors to consider. Since you have always had plenty of eyelashes, you might not be aware of any asymmetry in that department, but I'm very fair, with fine, light hair and I have noticed with the passage of time that one side of my head has slightly more hair than the other (weird, huh?), and interestingly the side with more hair has thicker eyelashes.