How far can my contact lens wander around my eye?

I know I’m not supposed to, but I just rubbed my eyes, and one of my contact lenses migrated off of its proper perch in my eye. I did some exploratory eye-rolling in front of the mirror, and the lens eventually extruded itself from where it had been wadded up near my tear duct.

So, how far around my eye could it possibly go? If it gets under one of the lids, can it migrate all the way to the top or the bottom of my eyeball? If so, how would I ever get it back out? Or are there eye muscles that would block its path all the way around?

Ehow advice.
http://www.ehow.com/tips_116194.html