Eyelid malposition: lower lid entropion and ectropion.

Correcting entropion and ectropion successfully requires knowledge of the eyelid problems, because understanding of these abnormalities is a key to planning a successful surgical procedure. Entropion is a condition in which the eyelid margin turns inwards against the globe. It is divided into following categories: congenital and acquired, which may be involutional or cicatricial. Ectropion is a malposition in which the lid falls away or is pulled away from its normal apposition to the globe. The condition is classified as congenital and acquired, which is divided into following categories: involutional, cicatricial, paralytic, and mechanical. Therefore, there are some common anatomic changes for both entropion and ectropion as well as specific changes that are unique to each eyelid malposition. Typically, instability of the eyelid is caused by either horizontal laxity or disinsertion or attenuation of the lower eyelid retractors to the inferior tarsal border, so surgical procedures should be directed at correcting the horizontal and vertical instability of the lid. Classification, etiology, underlying anatomic changes in the lid, principles of surgical treatment of entropion and ectropion are reviewed in this article.