Answer:
Entropion is an inward turning of the eyelid margin and contact of the lashes against the cornea. The friction of the lashes and epidermized lid margin causes ocular irritation and corneal epithelial abrasions. Entropion can be either congenital or acquired, the latter can be further categorized into involutional (aging) or cicatricial. The type of repair depends on the type of entropion. Surgical correction of congenital entropion is performed by excising the infratarsal skin and hypertrophied pretarsal orbicularis muscle, with or without a lateral canthoplasty. Cicatricial entropion is caused by scarring of the conjunctiva or subconjunctiva, which shortens the posterior lamella of the lid and pulls on the lid margin, causing the bowing of the tarsus toward the globe. This is corrected by releasing the conjunctival adhesions and resurfacing the bare surfaces with mobilized conjunctival flaps and buccal mucosal grafts. If there is no conjunctival scarring, the management of entropion depends on the degree of ocular irritation and horizontal lid laxity. If entropion occurs with little or no horizontal lid laxity, then the method of correction should create a fibrous tissue (scar) barrier to the upward migration of the preseptal orbicularis muscle. A strip of infraciliary skin and underlying pretarsal muscle is excised to expose the inferior border of the tarsus and insertion of the lower eyelid retractors. Correction is achieved by suturing the infraciliary skin-muscle edge to the inferior border of the tarsus, incorporating the lower lid retractors as well as the lower skin-muscle edge. If there is considerable horizontal lid laxity, the correction must incorporate a horizontal lid-shortening procedure, achieved by excising a triangular segment of full thickness tarsus.