A type of eyelid malposition, called entropion, can occur due to a number of factors, the most common of which include: age (loss of skin elasticity), scarring (due to previous surgery), mechanical (due to eyelid/facial tumor), or spastic (change in muscle tone causing the eyelid to turn inward).
Regardless of the cause, entropion, or an eyelid that inverted or being pushed inward, can cause deleterious effects on the cornea, which can lead to permanent vision loss. This is usually due to the eyelashes constantly rubbing on the cornea. Treatment of entropion is often necessary to prevent dangerous downstream effects. Treatment can include surgery or even injections with neurotoxins (Botox or Dysport)