Entropion and ectropion

[Rihanna]

Entropion is a condition in which the eyelid is turned inward (inverted), causing the eyelashes to rub against the eyeball. Ectropion is a condition in which the eyelid is turned outward (everted) so that its edge does not touch the eyeball.
Normally, the upper and lower eyelids close tightly, protecting the eye from damage and preventing tear evaporation. If the edge of one eyelid turns inward (entropion), the eyelashes rub against the eye, which can lead to ulcer formation and scarring of the cornea. If the edge of one eyelid turns outward (ectropion), the two eyelids cannot meet properly, and tears are not spread over the eyeball.
These conditions are more common among older people (generally the result of increased tissue relaxation with age); among people with eye changes caused by infection, surgery, or injury; and among people who have blepharospasm. Ectropion can also occur in people with Bell palsy.