One eye does not tear when crying

I am a 24 year old female with what I'd consider healthy eyes.  I have never had a problem, just prescribed reading glasses.  I have noticed recently that when I cry, my left eye does not tear at all.  My right eye can be gushing with tears while my left remains dry.  The only thing that I can possibly think of, was about 6 months ago.  I was at work and my left eye started tearing up for no reason, it kept going for about 6 hours, then stopped, it didn't feel like anything was in my eye, it wasn't irritated, it didn't hurt, it just kept tearing, I haven't had a problem since.  I am not in any pain, but I want to make sure this can't be anything serious, thanks for your help!

[John C Hagan III, MD, FACS, FAAO]

You need to see an Eye MD> Find one at www.aao.org

JCH III MD