Entropion describes a situation where the tarsus and lid margin rotate inward. As a result, the lashes are directed onto the ocular surface causing irritation, reflex lacrimation and recurrent conjunctivitis. The cornea is at risk of ulceration. Entropion generally affects the lower lid and is classified as congenital, involutional or cicatricial.
Congenital entropion is due to hypertrophy of the anterior lamella. Mild forms are common and usually resolve with time. If the child is photophobic, or the eyes appear irritated then surgical correction can be acheived by excising an ellipse of skin and orbicularis.
Age-related entropion is caused by laxity of the tarsus and its medial and lateral canthal tendons, laxity of the lower lid retractors and over-riding of the orbicularis. Taping the lower lid provides temporary relief while awaiting surgical correction.
The simplest form of surgery consists of passing absorbable sutures from the lower fornix through the lid to emerge on the skin just below the lashes (everting sutures). The everting effect can be augmented by splitting the lid horizontally. The lid can be shortened if horizontal laxity is a factor.
Cicatricial entropion is caused by scarring disorders which shorten the posterior lamella. The main causes are chemical burns, chronic conjunctivitis, trachoma, mucous membrane pemphigoid and Stevens-Johnston syndrome. The surgical treatment is complex and may involve grafting the posterior lamella in order to lenthen it, allowing the lid to rotate outward again. Even then, the condition often recurs as the scarring progresses. Cicatricial entropion is the only type to affect the upper lid.
In trichiasis, the lid position is normal, but the lashes turn inwards instead of outwards, and rub on the cornea. It may be possible to ablate a single lash root with electrolysis. If more than a few lashes are involved, cryotherapy (freezing treatment) is necessary to destroy the lash roots. In black skin, cryotherapy may cause depigmentation. In the outer part of the upper eyelid, it may stimulate a progressive entropion, negating the effect. In these circumstances, surgery may be necessary to evert that part of the eyelid which bears the lash roots. Distichiasis describes a situation where extra lashes grow out of the little Meibomian glands along the lid margin, spearing the corneal surface. This can be treated by splitting the eyelid margin into two layers and applying cryotherapy to the posterir layer.
In ectropion the tarsus and lid margin rotate outwards. The exposed conjuntiva becomes chronically inflamed and hypertrophic, the lower part of the cornea is exposed and the punctum is carried out of the tear lake, causing epiphora (watering of the eyes). Ectropion generally affects the lower lid and is classified as congenital, mechanical, involutional, cicatricial or paralytic.
Mechanical ectropion is due to the weight of a lid lump. The treatment is to excise the tumour.
Involutional ectropion is due to horizontal laxity of the eyelid tissues. The treatment is to shorten the lid in the site of maximum laxity. In medial ectropion with punctal eversion, this can be combined with excision of a diamond of tarsoconjunctiva to invert the punctum.
Cicatricial ectropion is due to scarring of the anterior lamella due to trauma, burns or facial dermatoses. If the contracture is localised, it may be corrected by a Z-plasty, but when it is generalised a skin graft is required.
Paralytic ectropion is due to a VIIth nerve palsy. If recovery is anticipated then treatment is aimed at protecting the globe. A temporary tarsorrhaphy may be required, depending on the degree of corneal exposure. A newer alternative is to drop the upper lid by paralysing the levator using botulinum toxin. If the palsy is permanent then a variety of lid-shortening procedures can be employed with or without lateral tarsorrhaphy.
John Pitts is an oculoplastic surgeon in full-time privatepractice in London and Barbados following a substantive NHS consultantposition. He graduated MB ChB from Glasgow University in 1983 and,in 1987, after working in pathology and neurology, he trained in ophthalmologyin Glasgow, Nottingham and London. He has travelled extensively, workingin centres of excellence in Los Angeles, New Orleans, Melbourne, Barbados,Brunei and Vancouver. He has undertaken Fellowship training inoculoplastics at Moorfields Eye Hospital.
