Abnormalities of the Lids

Chapter 616 Abnormalities of the Lids




Ptosis


In blepharoptosis, the upper eyelid droops below its normal level. Congenital ptosis is usually a result of a localized dystrophy of the levator muscle in which the striated muscle fibers are replaced with fibrous tissue. The condition may be unilateral or bilateral and can be transmitted as a dominant trait.


Parents often comment that the eye looks smaller because of the drooping eyelid. The lid crease is decreased or absent where the levator muscle would normally insert below the skin surface. Because the levator is replaced by fibrous tissue, the lid does not move downward fully in downgaze (lid lag). If the ptosis is severe, affected children often attempt to raise the lid by lifting their brow or adapting a chin-up head posture to maintain binocular vision. Marcus Gunn jaw-winking ptosis accounts for 5% of ptosis in children. In this syndrome, an abnormal synkinesis exists between the 5th and 3rd cranial nerves; this causes the eyelid to elevate with movement of the jaw. The wink is produced by chewing or sucking and may be more noticeable than the ptosis itself.


Although ptosis in children is often an isolated finding, it may occur in association with other ocular or systemic disorders. Systemic disorders include myasthenia gravis, muscular dystrophy, and botulism. Ocular disorders include mechanical ptosis secondary to lid tumors, blepharophimosis syndrome, congenital fibrosis syndrome, combined levator/superior rectus maldevelopment, and congenital or acquired 3rd nerve palsy. A small degree of ptosis is seen in Horner syndrome (Chapter 614). A complete ophthalmic and systemic examination is therefore important in the evaluation of a child with ptosis.


Amblyopia may occur in children with ptosis. The amblyopia may be secondary to the lid’s covering the visual axis (deprivation) or induced astigmatism (anisometropia). When amblyopia occurs, it should generally be treated before treating the ptosis.


Treatment of ptosis in a child is indicated for elimination of an abnormal head posture, improvement in the visual field, prevention of amblyopia, and restoration of a normal eyelid appearance. The timing of surgery depends on the degree of ptosis, its cosmetic and functional severity, the presence or absence of compensatory posturing, the wishes of the parents, and the discretion of the surgeon. Surgical treatment is determined by the amount of levator function that is present. A levator resection may be used in children with moderate to good function. In patients with poor or absent function, a frontalis suspension procedure may be necessary. This technique requires that a suspension material be placed between the frontalis muscle and the tarsus of the eyelid. It allows patients to use their brow and frontalis muscle more effectively to raise their eyelid. Amblyopia remains a concern even after surgical correction and should be monitored closely.



Jun 18, 2016 | Posted by in PEDIATRICS | Comments Off on Abnormalities of the Lids
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