Abstract: Lower eyelid involutional entropion is a common eyelid malposition in the aging population. The secondary trichiasis results in ocular irritation and corneal injury, and therefore may affect vision. Eyelid mechanical imbalance is the essence in development of entropion and ectropion. Vertical laxity (from retractor disinsertion), horizontal laxiy and orbicularis override of lower eyelid as the three main factors are involved in mechanical imbalance of involutional entropion. So far more than 100 different surgical approaches have been proposed, and in this review, pathogenesis and treatment strategy for lower eyelid involutional entropion are summarized.