I don't have any of the symptoms of blepharitis. What else could be causing the thinning or loss of eyelashes on one eye and not the other?
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.
I have read that this is actually normal. Who knew?
Anyhow, get it checked out, and talk with the doc you see about what to do about eyelash loss.
This could be due to blepharitis. Although it is usually in both eyes. Please see an ophthalmologist for a check.
Dr. O.