Chapter 25

The most common eyelid abnormality in children is ptosis (blepharoptosis), which causes drooping of the eyelid. The upper eyelid normally rests just below the junction of the cornea and sclera (the limbus) superiorly. Eyelid retraction is the opposite of ptosis—the upper eyelid rests too high on the globe, such that the sclera above the iris is visible. Lagophthalmos is present if the eyelids do not close completely.

The eyelashes are normally directed away from the eye. Entropion is present if the eyelid and lashes are directed inward. Ectropion is present if the eyelashes are turned outward and the eyelid does not rest directly against the eyeball. Distichiasis is a condition in which patients have an extra row of abnormal eyelashes on the posterior eyelid margin.

Abnormalities of the eyelid structures occur in association with many craniofacial abnormalities. Examples of these include hypotelorism, in which the orbits and eyelids are closer together than normal; hypertelorism, in which these structures are farther apart than normal; and telecanthus, in which the distance between the inner eyelid margins (medial canthi) is abnormally wide. These abnormalities do not usually cause vision problems, but analysis of the different relationships of the eyelid structures may be useful in identifying specific syndromes. Epicanthal folds, extra medial eyelid tissue, are fairly common in infants. They are the most common cause of pseudostrabismus, the appearance of eye crossing despite normal ocular alignment.

The upper eyelid is lifted by the levator palpebrae superiorus muscle, which originates in the posterior orbit. It travels forward and divides into an anterior portion, the levator aponeurosis, and a posterior portion, Müller’s muscle. Both of these insert onto to the tarsal plate (tarsus), the firm connective tissue that gives substance to the eyelid (Figure 25–1). The levator aponeurosis has attachments to the skin, which create the superior eyelid fold. The levator muscle is innervated by the third cranial nerve. Müller’s muscle is sympathetically innervated.

###### FIGURE 25–1

Cross-sectional view of upper eyelid anatomy.

The eyelids close by contraction of the orbicularis oculi muscle, which is arranged in a circular configuration around the upper and lower eyelids. It is innervated by the seventh cranial nerve.

### Embryology

The eyelids initially form from ectoderm at 4 to 5 weeks gestation. The upper and lower eyelids move toward each other and fuse at 10 weeks. Mesodermal tissue enters the lid and forms the musculature of the eyelid. During the fifth month of gestation the eyelids separate.

### Ptosis

Ptosis is caused by dysfunction of the levator muscle. In children it may be congenital or acquired. Most commonly it is congenital, secondary to underdevelopment of the muscle. Ptosis may be bilateral or unilateral, and may ...

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