Entropion involves the turning in of the edges of the eyelid (usually the lower eyelid) so that the lashes rub against the eye surface.
Entropion can be present at birth (congenital).
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. This causes the lid to turn inward.
Although rare in North America and Europe, trachoma infection 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:
Howard GR. Eyelid retraction. In: Yanoff M, Duker JS, Augsburger JJ, et al, eds. Ophthalmology. 2nd ed. Philadelphia, Pa: Mosby Elsevier; 2004: chap 85.