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.
In people with entropion or ectropion, artificial tears and eye lubricant ointments (for use overnight) can be used to keep the eye moist and soothe the irritation. Entropion and ectropion can be treated surgically—for instance, to preserve sight if damage to the eyes (such as corneal ulcer with entropion) is likely or has occurred, for comfort, or for cosmetic reasons.