The turning in of the edges of the eyelid (usually the lower eyelid) so that the lashes rub against the eye surface.

Also known as entropion, it can be a congenital condition. In babies, it rarely causes problems because the lashes are very soft and do not easily damage the cornea. In older people, the condition is usually caused by a spasm and weakening of the muscles surrounding the lower part of the eye, causing the lid to turn inward.

Although rare in North America and Europe, trachoma infection (eye infection caused by bacteria) can cause scarring of the inner side of the lid, which may cause entropion.

Trachoma scarring is one of the three leading causes of blindness in the world. Risk factors for entropion are aging, chemical burn, or prior infection with trachoma.