We just learned about the Rheum.
Another part of the eye is a Myokymia, which is a type of eye spasm where the eyelid twitches.
Sometimes without doing it on purpose the upper or lower eyelid might twitch a little.
It usually goes away after a while, and is usually caused by not getting enough sleep or not drinking enough water.
If it is really bad and doesn't go away for months, then it is called a blepharospasm.
(from: wikipedia - blepharospasm)
Kid Facts - Blast from the past: Vermillion Border