Eyelids

While blinking, the eyelids move up and down: 1) During their upward motion, they deposit the thin tear film in charge of the protectyion of the cornea. We first study the thikness of this film, modeling the eyelid as an elastic sheet and the tear as a newtonian liquid. 2) During the downward motion, the eyelid moves upon the tear film and in some case gets stuck and reverses, leading to the so called Entropion desease. We come back on this irregular motion and show how it can be physically understood.