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.

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 be idiopathic, familial, or associated with other syndromes (e.g., Turner syndrome). Congenital ptosis is commonly an isolated finding in otherwise normal children. Acquired ptosis may develop secondary to third cranial nerve palsy or eyelid or orbital lesions. Myasthenia gravis and chronic progressive external ophthalmolplegia may also cause ptosis, as can many other disorders (Table 25–1).

Evaluation

Ptosis can be generally categorized as mild, moderate, or severe. Mild ptosis is more easily noticed if unilateral, in which case one eyelid is slightly lower than the other. This does not produce visual problems and no treatment is necessary. In patients with severe ptosis, the eyelid partially or completely blocks the pupil, and therefore interferes with vision (Figure 25–2). Infants with severe ptosis require early surgical correction to prevent amblyopia. In children with moderate ptosis the eyelid partially blocks the pupil. Ptosis may cause amblyopia either directly by blocking vision or indirectly by inducing astigmatism by the weight of the eyelid on the cornea.1 Children with moderate-to-severe ptosis often have a prominent brow lift with arched eyelids, which they adopt to help elevate the eyelid by using the frontalis muscles (Figure 25–3). They also frequently develop a chin-up head posture to see below the drooping eyelid (Figure 25–4).

Evaluation of ptosis requires assessment of the degree of the levator muscle function. This is done by noting the amount of elevation of the eyelid between downgaze and upgaze. In normal patients the eyelid excursion measures approximately 15 mm. In moderate ptosis (with some residual function of the levator muscle), patients usually have 5 to 10 mm of movement. In severe ptosis, movement is 4 mm or less (Figure 25–5A and B). In many cases of childhood ptosis, the levator muscle is stiff in addition to being weak. This may cause the eyelid to not fully close, and the distance between the upper and lower eyelids may actually increase in downgaze (Figure 25–5C). The normal eyelid crease forms by fibers of the levator muscle extending to the eyelid skin. Because the levator muscle is weak in patients with ptosis, they often have decreased eyelid skin creases (Figure 25–2).

If ptosis is not an isolated abnormality, most patients will have other findings that suggest a diagnosis. Third cranial nerve palsies typically also involve the pupil (which is dilated, except in some congenital cases in which the affected pupil is smaller than the other) and extraocular muscles (with the eye out and down) (Figures 25–6A and B). Orbital or eyelid lesions may produce proptosis with visible thickening or masses within the eyelid. Contiguous sinus infections may cause ptosis due to inflammation and edema (Figure 25–7A and B). Patients with ocular myasthenia gravis usually have variable strabismus and ptosis (Figure 25–8). These are usually most noticeable when the patient is fatigued. Examination may reveal a Cogan lid twitch, in which the eyelid briefly elevates more than normal when the patient’s gaze is quickly directed from down to up.

Patients with chronic progressive external ophthalmoplegia (CPEO) typically have progressive ptosis and restrictive strabismus, most commonly involving the inferior rectus muscles. A form of this disorder associated with mitochondrial abnormalities is Kearns-Sayre syndrome, which includes CPEO, pigmentary retinopathy (Figure 25–9A and B), and cardiac conduction defects.

Treatment

The treatment of ptosis depends on the patient’s age and the severity of the eyelid droop. Mild ptosis usually does not require any treatment. Children with severe ptosis that occludes the eyes are at high risk for amblyopia, particularly if the ptosis is unilateral (similar to the risk of amblyopia in unilateral congenital cataracts). If the ptosis is moderate and the vision is developing normally, treatment is often delayed until approximately 4 to 5 years of age.

Surgery is required to correct ptosis. The type of surgery depends on the degree of function of the patient’s levator muscle. In severe cases of congenital ptosis the levator usually has almost no function. These patients typically lift their brow to recruit the frontalis muscle to assist in elevating the lid (Figure 25–3). Surgical correction of severe ptosis takes advantage of this by attaching the eyelid directly to the frontalis muscle with strips of donor or autologous fascia or synthetic material (Figure 25–10). After surgery, when the patient elevates the brow, the force is transmitted directly to the eyelid (Figure 25–11). Even with a good surgical outcome, the eyelid height will vary depending on how alert the patient is. The most common complication of frontalis suspension surgery is corneal exposure due to incomplete eyelid closure. Exposure of the implant material or recurrent granuloma formation may also occur, sometimes requiring removal of the material (Figure 25–12). Over time the drooping of the eyelid may recur, necessitating repeat surgery.

Patients with moderate ptosis have some residual function of the levator muscle. Surgery in these patients consists of tightening the muscle (levator muscle resection) (Figure 25–10), normally performed through an incision in the eyelid crease to minimize scarring. This surgery generally results in a more normal appearance of the eyelid than does frontalis suspension surgery, and there are fewer complications.

Pseudoptosis. Patients may sometimes appear to have mild ptosis due to overhanging of the brow skin. This can be distinguished by elevating the brow tissue and examining the eyelid and levator muscle function, which are found to be normal (Figure 25–13A and B).

Patients may also appear to have ptosis due to other ocular conditions:

• Patients with increased light sensitivity (due to a corneal problem, for example) may voluntary keep their eyelid closed to decrease their symptoms.
  
• Patients with vertical strabismus may appear to have ptosis on the side with the lower eye because the eyelid normally moves in conjunction with the eye.
  
• Patients with intermittent exotropia may close the eye when exotropia is manifest.

Blepharophimosis syndrome is an autosomal dominant disorder characterized by ptosis, epicanthus inversus (an epicanthal fold that is most prominent on the lower eyelid), and short vertical and horizontal eyelid fissures (blepharophimosis) (Figure 25–14). The ptosis frequently requires a sling procedure in infancy to prevent amblyopia. Surgery to reduce the prominent epicanthal folds is often performed.