Ординатура / Офтальмология / Английские материалы / Pediatric Ophthalmology Current Thought and A Practical Guide_Wilson, Saunders, Trivedi_2008

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Contents

19.1.1Anatomic Considerations  . . . . . . .   256

19.1.2 Developmental Considerations  . . . . .   256

19.1.3Evaluation  . . . . . . . . . . . . . . . . . . . . . . . . . .   257

19.1.4Timing of Surgical Intervention  . . . . .   258

19.2Other Eyelid Disorders  . . . . . . . .   261

19.2.1Blepharophimosis Syndrome  . . . . . .   261

19.2.4Congenital Eyelid Coloboma  . . . . . .   262

19.3.1Benign Lesions  . . . . . . . . . . .   266

19.4.3Herpes Simplex  . . . . . . . . . . .   270

19.4.4Herpes Zoster  . . . . . . . . . . . .   270

19.4.5Molluscum Contagiosum  . . . . . . .   270

Core Messages

•Congenital ptosis typically involves reduced function of the levator palpebrae superioris muscle.

•In children with congenital ptosis, amblyopia is common.

•When present, amblyopia is usually refractive and caused by “induced- with-the-rule” astigmatism. Occlusion amblyopia is much less common.

•Surgical repair of congenital ptosis and other pediatric eyelid abnormalities involves procedures that require special considerations and techniques that may differ from oculoplastic surgical procedures performed on adults.

19.1 Congenital Ptosis

19.1.1 Anatomic Considerations

The normal upper eyelid margin forms a curved arch and overlies the superior 1−2 mm of the cornea. The peak of this curve is approximately 1 mm nasal to the center of the cornea. Strands from the external levator aponeurosis attach to the skin and form the upper eyelid crease [1]. In conditions with abnormal levator development, such as congenital ptosis, the upper eyelid crease is reduced or absent. The orbital septum defines the anterior boundary of the orbit and overlies orbital fat. The orbital septum is important in eyelid anatomy. In Caucasians’ upper eyelids the orbital septum and levator aponeurosis fuse at approximately the superior tarsal border 10 mm above the lid margin; however, in Asian eyelids the septum inserts much lower into the levator aponeurosis resulting in inferior displacement of orbital fat and a lower eyelid crease [2]. Posterior to the levator aponeurosis is the underlying Muller’s muscle.

The upper eyelid tarsus is approximately 10 mm in its vertical height in the adult and proportionately shorter in children. The medial canthal tendon attaches to the anterior and posterior lacrimal crest and the fascia of the lacrimal sac. The lateral canthal tendon attaches to the lateral border of the tarsus and to Whitnall’s tubercle inside the lateral orbital rim. The normal lateral canthus is slightly above the medial canthal tendon in the horizontal plane.

The levator muscle originates from the lesser wing of the sphenoid. It runs posterior to anterior along the superior orbit. Just inside the superior orbital rim the levator muscle crosses and fuses with Whitnall’s ligament, which provides support to the levator muscle and its aponeurosis. Turning inferiorly at Whitnall’s ligament, the levator aponeurosis spreads out horizontally to form a fan-shaped structure. This structure attaches to the periosteum medially and laterally forming the medial and lateral horns. The levator aponeurosis also inserts broadly across the anterior surface of the upper eyelid tarsus with fine strands of the levator aponeurosis inserting into the eyelid skin and forming the eyelid crease.

Muller’s muscle complex arises from the posterior aspect of the levator muscle, lies along the posterior surface of the levator aponeurosis, and inserts into the

superior border of the tarsus. The superior division of cranial nerve III innervates the levator palpebrae superioris muscle, while Muller’s muscle is innervated by the sympathetic nervous system.

19.1.2 Developmental Considerations

Congenital ptosis of the upper eyelid is typically seen in association with an abnormal development of the levator muscle complex.Although typically sporadic, familial ptosis is linked to chromosome 1p [3]. It is now believed that the primary defect in congenital ptosis is an abnormality in the development of a part of cranial nerve III responsible for innervation of the levator palpebrae superioris. Because the extraocular muscles require innervation to develop properly, a developmental abnormality of innervation results in a muscle with reduced muscle fibers and a variable degree of reduced levator muscle function. This is a more limited presentation of what occurs in congenital fibrosis syndrome [4, 5], where ptosis of the upper eyelid is a common component. Congenital ptosis occurs either unilaterally or bilaterally. Superior rectus muscle weakness can occur in association with congenital ptosis.

Dysfunction or interruption of the ocular sympathetic nerve causes ptosis, miosis, and anhydrosis.

This triad of signs is known as Horner syndrome [6].

Ptosis of the child’s upper eyelid is most often present from birth. Ptosis in the child is occasionally due to congenital myasthenia, muscular dystrophy, syndromic associations, or to acquired abnormalities such as trauma or loss of innervation to Muller’s muscle. It is usually due to an isolated abnormality in the neuromuscular development of the levator palpebrae superioris; however, mechanical factors can contribute to ptosis such as relative enophthalmos following an orbital fracture. Congenital ptosis that occurs in the Marcus Gunn jaw-winking phenomenon is a result of aberrant innervation of the levator muscle with nerves normally directed to the muscles of mastication. Typically, with contralateral jaw movement the ptotic eyelid elevates. This is often noticed in infancy when the child seems to “wink” while nursing or taking a bottle (Fig. 19.1).

19.1.3 Evaluation

Careful history should be taken as to the variability of the ptosis. While most patients with congenital ptosis report slight worsening with fatigue, this variability is typically minor and the ptosis is always present. A history of a normal eyelid position after sleep followed by significant ptosis when the patient is fatigued should raise a concern for myasthenia gravis.

In the young child, sufficient cooperation to assess fatigability may not be possible. Tests, which can be performed to establish the diagnosis of myasthenia gravis, include the ice test, rest test, and the tensilon test and neostigmine tests. Tests for acetylcholine receptor antibodies are rarely positive in isolated ocular myasthenia gravis, especially in childhood. If present, acetylcholine receptor antibodies are strongly indicative of the presence of myasthenia gravis [7].A positive tensilon test, abnormal single-fiber EMG recordings, and therapeutic responses to anticholinesterase medicines or corticosteroids establish this diagnosis. If myasthenia is strongly suspected, then a trial of mestinon or corticosteroids is indicated. All cases of acquired Horner syndrome and selected cases of congenital Horner syndrome should be evaluated for an underlying neurologic etiology, such as a neuroblastoma involving the ocular sympathetic pathway. Other causes of congenital and acquired ptosis should be considered, including third cranial nerve paresis, Kearns-Sayre syndrome (Fig. 19.2), orbital tumors and trauma.

Fig. 19.2  Kearns-Sayre syndrome. Patient with severe ptosis and nearly complete external ophthalmoplegia

All patients with congenital ptosis require repeated visual acuity testing and determinations of refractive error. Frequently, amblyopia occurs due to induced astigmatism, and less commonly due to occlusion of the line of sight [8]. The presence of a chin elevation may allow for peripheral fusion but does not exclude the presence of amblyopia [9].

Treatment of uncomplicated congenital ptosis is dependent on the amount of ptosis present in the pri-

mary position, as well as the amount of levator muscle function. Patients with unilateral or bilateral ptosis often use their frontalis muscle to elevate the eyelids; therefore, it is important to position the brow in the normal position prior to measuring the amount of ptosis. The lid margin-reflex distance (MRD) should be measured. The MRD is the distance from a corneal light reflex to the upper eyelid margin with the patient’s eyes in primary gaze. The amount of levator function also should be measured. This can be difficult in younger children and infants. In congenital ptosis the amount of ptosis inversely correlates with the amount of levator function. Repeated examinations help the surgeon obtain reliable measurements of the amount of ptosis and levator function. Levator function is measured by firmly fixing the brow to immobilize the frontalis muscle. The millimeters of eyelid margin movement from full downgaze to full upgaze is then determined. A full examination of the extraocular muscles should be performed. In addition to a determination of the superior rectus muscle function, one should check the Bell phenomenon (upward deviation of the eye during forced lid closure). A normal (present) Bell phenomenon is important because lagophthalmos is common following repair of congenital ptosis [10]. When superior rectus muscle function is reduced, a surgeon should be more conservative in the amount of surgery performed to correct the ptosis. Because reliable Schirmer testing is difficult in the child, examination of the tear film and careful evaluation of the cornea for any signs of exposure both preand postoperatively is necessary. In addition, one should determine the corneal sensitivity. Patients with diminished corneal sensitivity due to innervation abnormalities are at increased risk of exposure keratopathy following surgical correction of congenital ptosis. The surgeon should be cautious and avoid surgery or reduce the amount of ptosis correction if abnormal corneal sensitivity exists.

In addition to measuring levator function, the eyelid should be assessed with its response to phenylephrine. One drop of 2.5% phenylephrine is instilled into the lower cul-de-sac in younger children and infants.

Re-measure the MRD after approximately 5 min. If the eyelid elevates to a near-normal position, tightening or resection of Muller’s muscle is considered for ptosis repair.

In patients with Marcus Gunn jaw-winking ptosis, the amount of eyelid retraction with movement

of the jaw should be evaluated. If significant retraction is present, extirpation of the involved levator muscle combined with a frontalis suspension should be performed. Failure to extirpate the involved levator muscle will result in persistent wink. If only mild retraction occurs, ptosis repair should be undertaken using standard amounts of surgery. An external levator resection is the usual procedure.

19.1.4 Timing of Surgical Intervention

In most situations congenital ptosis is repaired between the ages of 4 and 5 years. Occlusion amblyopia from severe ptosis is rare. When recognized, surgical repaired should be performed. Most ptosis-associated amblyopia is caused by induced astigmatism. If a significant astigmatism develops, spectacle correction and amblyopia therapy should be instituted.

19.1.5 Surgical Procedures

There are several options for the surgical management of congenital ptosis. The two main surgical procedures are the external levator resection and the frontalis suspension procedure. The Muller’s muscle procedures (Fasanella Servat and Mullerectomy) may be used for the correction in mild ptosis, and works especially well in neurogenic ptosis associated with Horner syndrome.

19.1.5.1Levator Muscle Procedures

Levator aponeurosis/muscle shortening procedures are performed in cases of mild to moderate ptosis (Fig. 19.3). Although classic levator aponeurosis dehiscence can be encountered in the pediatric population, more commonly decreased levator function and levator muscle dysgenesis is encountered. A more generous resection of the levator muscle aponeurosis is required in children than in the adult. The amount of resection is dependent on the amount of levator function measured (Table 19.1). In cases of severe congenital ptosis, supramaximal levator muscle resection can produce satisfactory eyelid height in pri-

mary position; however, the lagophthalmos created by this procedure is usually much greater than that created with the frontalis suspension procedure.

The surgical approach is through the eyelid crease, dissecting through skin and then through orbital septum. The underlying levator aponeurosis is exposed beneath the preaponeurotic fat. The levator aponeurosis is separated from the tarsal plate and dissection in the plane between Muller’s muscle and levator aponeurosis is carried superiorly to expose and separate the levator tendon (Fig. 19.4). In cases where a large resection is anticipated the lateral and medial horns of the aponeurosis are cut. Three partial thickness sutures are placed in the anterior tarsal surface

3−4mmbelowthesuperiorborderofthetarsus.These sutures are then placed through the levator aponeurosis. Because the patient is usually under general anesthesia, the amount of resection needs to be determined prior to surgery. Sutures are tied with a single

throw knot on the anterior surface of the aponeurosis and are replaced and retied until the surgeon is satisfied with the eyelid height and contour. Square knots are then tied and the levator tendon distal to the sutures is resected. The eyelid crease may be formed with separate sutures between the levator tendon and the eyelid skin, or by incorporating bites of the levator tendon into the skin closure.

19.1.5.2Frontalis Suspension

Frontalis suspension procedures are used in unilateral or bilateral cases of severe ptosis with very poor levator function (Fig. 19.5) [11]. Autogenous fascia lata can be obtained from the leg of the child. Typically, children are 3−4 years of age before an adequate length of fascia lata is obtainable. Banked irradiated fascia lata is available; however, autogenous fascia

Fig. 19.4  a The aponeurosis of the levator muscle has been dissected off of the tarsus and underlying Muller’s muscle and conjunctiva. b Sutures placed in the Tarsus and passed through

the levator aponeurosis; Muller’s muscle is seen at the superior border of the tarsus. c The sutures have been securely tied and distal portion of the levator aponeurosis resected

lata has a lower rate of recurrent ptosis. Newer nonresorbing materials are available such as mersilene mesh, supramid suture, and expanded polytetrafluoroethylene (ePTFE). Synthetic supramid suture can be used for temporary elevation of the eyelid but may result in recurrent ptosis within 18 months [12]. Expanded polytetrafluoroethylene (ePTFE) is now available in strips specifically designed for use in ptosis repair (ptose-up, FCI Ophthalmics, Marshfield

Hills, Mass.).

In cases of severe unilateral ptosis, bilateral frontalis suspensions have been performed in order to provide a symmetric eyelid appearance, particularly in downgaze where lagophthalmos is most notable; however, if unilateral frontalis suspension is per-

formed and postoperative asymmetry is an issue, the fellow normal eyelid can be operated subsequently. In instances of asymmetric bilateral ptosis, requiring a frontalis suspension procedure on the more severely affected side, bilateral frontalis suspension typically results in the best cosmetic result.

The double rhomboid technique provides excellent results (Fig. 19.6). The brow of the child is the most mobile section of the forehead and allows for both adequate elevation of the eyelid as well as good closure of the eyelid. Some surgeons prefer a central knot higher on the forehead. While this provides excellent contour and suspension to the upper lid, the more fixed superior forehead does not allow as much dynamic eyelid movement.

Fig. 19.6a−c  Frontalis suspension using the double rhomboid technique. a Three brow incisions and three eyelid incisions are made. Two strips of ptose-up (FCI Ophthalmics, Marshfield Hills, Mass.) are passed using the Wright fascia needle.

19.1.5.3 Tarsal Muller’s Muscle Procedures

Tarsal Muller’s muscle procedures are excellent procedures in those patients with excellent levator function and mild ptosis, especially for those patients who have a congenital or acquired Horner syndrome.

b Each strip is used to make a rhomboid. c Each strip of ptoseup is tied to itself, secured with a permanent suture, and then buried in the medial and temporal brow incisions

ptosis, epicanthus inversus, telecanthus, blepharophimosis (a short horizontal palpebral fissure length), and variable lower eyelid ectropion. Each of the individual abnormalities is addressed surgically, either simultaneously or at separate sessions.

19.1.6 Complications of Ptosis Surgery

The primary complications of ptosis surgery are undercorrections, overcorrections, and lagophthalmos with exposure keratopathy. Other complications include abnormal eyelid crease, ectropion, entropion, conjunctival prolapse, infection, and bleeding. Blindness is a rare but devastating complication. Undercorrection is common in congenital ptosis, while overcorrection is unusual. Evaluation for exposure keratopathy should be performed for at all postoperative examinations. Lubrication with ointments and artificial tears is used postoperatively until the corneal examination is stable.

19.2 Other Eyelid Disorders

19.2.1 Blepharophimosis Syndrome

Blepharophimosis syndrome is an autosomal-domi- nant syndrome whose characteristic features include

19.2.2Anophthalmos

and Microphthalmos

True anophthalmos is extremely rare, and most cases of clinical anophthalmos likely represent severe microphthalmos. Microphthalmos represents a range of ocular developmental abnormalities from nearly complete absence of identifiable ocular structures to a small normally formed eye, a condition referred to as nanophthalmos. Microphthalmos often is associated with abnormal or reduced orbital bony size because the eyelid and orbital development are dependent on ocular development. Eyelid deformities also result and include a shortened horizontal palpebral fissure length. Treatment involves serial prosthetic conformers to enlarge the cul-de-sacs. In more severe cases the orbital volume can be expanded using dermis fat grafts, orbital implants, and orbital expanders [13].

Soft tissue growth parallels bone growth. Using these various techniques an acceptable cosmetic appearance is often achieved.

19.2.3 Cryptophthalmos

Cryptophthalmos is an extremely rare condition in which there is complete failure of development of the eyelid folds. A distinct feature of cryptophthalmos is failure of the brow to develop normally, resulting in fusion of the hairline and brow. This is distinct from an abnormal separation of the eyelid folds. Without development of the normal eyelid folds, the underlying cornea and conjunctiva do not normally form usually resulting in a severely malformed anterior segment of the eye. The posterior segment of the eye is sometimes disorganized. If an attempts is made to separate the eyelids, corneal transplantation to close the anterior segment defect and mucous membrane grafting to form conjunctival cul-de-sacs will usually be required. Preoperative evaluation with an electroretinogram, visual evoked potentials, imaging studies, and ultrasound provides insight into the structure and function of the underlying eye. Despite reconstructive surgery useful vision is rarely achieved. Fraser syndrome should be considered when cryptophthalmos is associated with cutaneous syndactyly, malformations of the larynx and genitourinary tract, craniofacial dysmorphism, orofacial clefting, mental retardation, and musculoskeletal anomalies [14].

19.2.4 Congenital Eyelid Coloboma

An eyelid coloboma is a congenital defect involving absence of a portion of the eyelid margin. This may occur in the upper or lower eyelid and may vary in size from a small eyelid marginal defect to a near complete absence of the eyelid. Colobomas are more common in the nasal aspect of the upper eyelid.

Large colobomas can result in corneal exposure and ulceration.

Eyelid colobomas may result from abnormal migration of ectoderm and mesoderm causing an abnormal development of the eyelid margin. Colobomas may also result from a mechanical disruption of eyelid development such as seen with amniotic bands or facial clefts. Eyelid colobomas can be seen in association with other abnormalities including Goldenhar syndrome, dermoids, cleft lip, microphthalmia, and ocular coloboma.

Treatment of upper-eyelid coloboma is initially directed at maintaining lubrication and protection of the ocular surface (Fig. 19.7). Surgical correction is not emergent if adequate protection of the corneal surface is achieved. Larger coloboma may require more aggressive lubrication and perhaps occlusive dressing prior to surgical closure. For smaller colobomas surgical repair during the latter half of the first year of life is preferable to allow for tissue growth. Defects less than 25% of the horizontal width of eyelid may be directly closed after excision of the defect. The edges of the defect are excised to form a pentagonal defect and then the tarsus is closed with three interrupted absorbable sutures. The eyelid margin is closed with sutures anterior to the gray line, through the gray line, and posterior to the gray line. The skin is approximated with interrupted sutures. Larger defects up to 40% of the eyelid margin can be closed by adding a lateral canthotomy and cantholysis with medial rotation of the lid. Even larger eyelid defects require a free tarsal conjunctival graft. Eyelid-shar- ing procedures (Hughes procedure), which temporarily occlude the eye, are contraindicated in children because of the induced amblyopia.

19.2.5 Pseudo-Coloboma

More commonly, pseudo-colobomas of the lower lid are seen in craniofacial synostosis (Treacher–Collins syndrome). With these pseudo-colobomas the eyelid margin is intact, but there is a facial cleft laterally which results in an inferior and lateral displacement of the lower eyelid. Simple soft tissue tightening and elevation of the lateral canthal tendon is often ineffective in correcting the lateral dystopia of the eyelid because there is often an absence of vertical and horizontal eyelid tissue. For this reason transposition flaps from the upper to lower eyelids are useful in addition to re-suspension of the lateral canthal tendon.

19.2.6 Ankyloblepharon

Ankyloblepharon is a condition of failure of eyelid separation or may result from an abnormality

in the migration of the mesodermal elements of the eyelid. Ankyloblepharon filiforme adnatum may be isolated, demonstrating fine bands of tissue between the upper and lower eyelids, or it may be seen with trisomy 18 [15], Hay-Wells syndrome [16], or other chromosomal abnormalities [17]. The treatment of ankyloblepharon is entirely surgical. The bands of the eyelid are separated and the eyelid margins are reformed as necessary.

Trichiasis refers to an acquired eyelash abnormality resulting from normally located but misdirected directed cilia. Chronic eyelid inflammation is the most common cause for trichiasis.

Treatment of eyelash abnormalities is not required in the absence of any abnormality of the corneal surface. Electrolysis or split thickness eyelid resections can be used to remove the lash follicles [18]. In addition, direct excision of the lash follicles is possible.

Distichiasis occurs when a developmental abnormality results in cilia formation in association with metaplastic meibomian glands. Although often asymptomatic, these lashes may cause superficial corneal irritation and abrasion. When acquired, distichiasis can be seen with chronic eyelid inflammations such as blepharitis, trachoma, and Stevens-Johnson syndrome.

Congenital ectropion is rarely found in isolation. When involving the lower eyelid, it is often part of the blepharophimosis syndrome or Treacher–Collins syndrome. Also, congenital eyelid ectropion may be seen in patients with neonatal erythroderma (collodian baby) [19]. When secondary to an insufficiency in the vertical extent of the skin and orbicularis lay-