Ординатура / Офтальмология / Английские материалы / Shields Textbook of Glaucoma, 6th edition_Allingham, Damji, Freedman_2010

Figure 14.4 Newborn-onset congenital glaucoma with severe bilateral corneal edema and opacification. Despite IOP reduction after surgery, central corneal opacification did not clear completely.

Refractive Error

The enlargement of the globe with elevated IOP in the first 3 years of life creates a myopic shift in the refractive error, which may lead to amblyopia if significant anisometropia is present. The presence of Haab striae often produces significant astigmatism, which also contributes to amblyopia, especially in unilateral or asymmetric cases. Children between 3 and 10 years of age with elevated IOP may develop progressive myopia and astigmatism, despite a stable corneal diameter. These refractive changes have been attributed to continued scleral stretching (7).

Tonometry

Measurement of the IOP in an infant or child suspected of having PCG should ideally be performed in the office, with the child as calm as possible. Useful handheld devices include the Perkins, Tono-Pen, and ICare tonometers, while the cooperative patient older than about 3 years (and without nystagmus) can often sit for Goldmann applanation. It is important to avoid traumatizing a child to obtain the IOP, because tonometry performed in a struggling child will invariably produce falsely elevated readings, which will be useless in diagnosing PCG or assessing control of known PCG. Infants with PCG commonly present with unanesthetized IOPs in the range of 30 to 40 mm Hg, although occasionally values above or below this range occur (42). Target pressures for children with PCG depend entirely on the details of the particular case; while IOPs in the low 20-mm Hg range may be adequate for a child with healthy optic nerves and stable refraction, others with more severe disease may progress at these same IOPs and require lower target IOP (see also Chapters 13 and 40).

Measuring the IOP under anesthesia is sometimes necessary, but should be coupled with an assessment of the overall status of the eye (or eyes), together with subsequent surgical intervention when necessary. When the IOP in infants and

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young children is measured during general anesthesia, the possible influence of the anesthesia on IOP must be considered (see Table 13.4), with the IOP measurement taken as soon as the airway is secure. A pressure of 20 mm Hg or greater should arouse suspicion (43). In cases of unilateral PCG, asymmetry of IOP measured under anesthesia may be very helpful, even if the true IOP has been altered in this setting. Slitlamp Examination

This portion of the examination is best performed with a portable slitlamp, with or without general anesthesia. Tears in the Descemet membrane (i.e., Haab striae) are classic findings of PCG; they may be single or multiple, and are characteristically oriented horizontally or concentric to the limbus (Fig. 14.5). They are typically associated with corneal edema in the early phases of glaucoma. Haab striae are found in about 25% of eyes with a diagnosis of PCG at birth and in more than 60% of those with that diagnosis at 6 months of age (44). These Haab striae remain as a testament to the early onset of the IOP elevation, even in late-diagnosed cases, or those rare cases with spontaneous resolution of the IOP elevation. As

The Bowman layer contains basophilic deposits (band keratopathy) as a degenerative change (stain, hematoxylin-eosin). (From Milman T. Congenital anomalies. In: Tasman W, Jaeger EA, eds. Duane's Foundations of Clinical Ophthalmology. Vol. 3. Philadelphia, PA: Lippincott Williams & Wilkins; 2008:chap 2.)

The anterior chamber is characteristically deep, especially when the globe is distended. The iris is typically normal, although it may have stromal hypoplasia with loss of the crypts.

Gonioscopy

Evaluation of the anterior chamber angle is essential for the accurate diagnosis of PCG. (The instruments and techniques of gonioscopy are discussed in Chapter 3.) In performing gonioscopy on infants and children under anesthesia, an infant Koeppe goniolens is recommended, together with a portable slitlamp for illumination and magnification. (See Chapter 13 for description of normal childhood gonioscopy findings.)

The anterior chamber angle has a characteristic, although slightly variable, appearance in PCG (Fig. 14.6). Usually, the iris has an insertion more anterior than that of the healthy infant, with altered translucency of the angle face rendering rather indistinct ciliary body band, trabecular mesh, and scleral spur. This translucent tissue has historically been referred to as Barkan membrane (45, 46). The scalloped border of the iris pigment epithelium and the trabecular meshwork itself, often prominent in PCG, may appear through the translucent peripheral iris stroma as if viewed through a morning mist. Although the angle is usually avascular, loops of vessels from the major arterial circle may be seen above the iris root, which has been called the Loch Ness monster phenomenon (45). The clinical features of PCG seem to merge with other forms of developmental glaucoma. A gonioscopic assessment of more than 100 eyes with developmental glaucoma revealed a spectrum ranging from the common form described earlier, through a more cicatrized, vascularized condition, to the gross anomalies of the Axenfeld-Rieger syndrome (47).

Funduscopy

Evaluation of the optic nerve head is one of the most important methods for diagnosing PCG and for assessing the response to therapy. This is usually done with the child anesthetized or sedated, often with an undilated pupil, in which case visualization of the disc may be facilitated by using a direct ophthalmoscope with a Koeppe gonioscopy lens on the cornea or a lens designed for vitrectomy surgery (48).

Cupping of the optic nerve head proceeds more rapidly in infants than in adults and is more likely to be reversible if the pressure is lowered early enough (49, 50, 51, 52, 53, 54, 55 and 56).

Significant optic nerve cup size and asymmetry of cupping between fellow eyes suggest, but do not confirm, glaucoma in an infant. The cup-to-disc ratio exceeded 0.3 in 68% of 126 eyes with PCG examined by Shaffer and Hetherington (53), but did so in only 2.6% of 936 healthy newborn eyes examined by Richardson (57). Marked optic cup asymmetry was observed

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in only 0.6% of healthy eyes in the latter study, in contrast to 89% for infants with monocular glaucoma.

Figure 14.6 A: Gonioscopic appearance of infantile glaucoma. Note the relatively high iris insertion, with indistinct angle landmarks and fine iris processes. The angle appears wider on the right side of the photograph, at the site of prior goniotomy surgery. B: Fetal angle manifests anterior insertion of the iris root and anterior displacement of the ciliary processes. The scleral spur is poorly developed. Trabecular meshwork and Schlemm canal are poorly defined; mesenchymal tissue is present in the anterior chamber angle. (From Milman T. Congenital anomalies. In: Tasman W, Jaeger EA, eds. Duane's Foundations of Clinical Ophthalmology. Vol. 3. Philadelphia, PA: Lippincott Williams & Wilkins; 2008:chap 2.) Visual Fields

When tested after the child becomes old enough for a reliable study (typically about 8 to 9 years of age for a child without cognitive impairment and nystagmus), the visual fields are similar to those in adultonset glaucoma, with an initial predilection for loss in the arcuate areas (56).

Visual Acuity

Good vision may be achieved if the IOP is controlled before optic atrophy occurs. Occasionally, however, the acuity is poor despite adequate pressure control. In some cases, this is caused by optic nerve damage, corneal opacity from breaks in the Descemet membrane or persistent stromal haze, or irregular astigmatism (44, 58). Other children may have normal-appearing optic nerve heads and clear media but develop amblyopia from anisometropia or strabismus (59). Retinal detachment is also an occasional cause of poor visual results (60).

Ultrasonography

Ultrasonography may be helpful in documenting progression of infantile glaucoma by recording changes in the axial length of the globe (40, 61, 62). It has also been reported that the axial length may decrease by as much as 0.8 mm after surgical reduction of the IOP (62). This change in axial length may be evident within days after a significant IOP reduction, especially in aphakic eyes of infants after filtration surgery or implantation of a glaucoma drainage device (Freedman SF, personal experience). Ultrasonography may also be helpful when glaucoma drainage-device surgery is being contemplated, because the size of the proposed implant reservoir may be limited by the globe size (see Chapter 40). After such surgery, ultrasonography can be helpful in confirming the presence of fluid around the device's reservoir, especially in patients in whom the bleb cannot easily be visualized in the office setting (Fig. 14.7).

Other Testing Techniques

Corneal pachymetry to measure central corneal thickness may prove useful after corneal edema has cleared, to help set a target IOP for a particular eye. Children with PCG generally have a

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relatively low central corneal thickness, presumably because of the enlargement of their corneas in early infancy (63) (see Chapter 13). Care should be taken not to “adjust” the measured IOP based on central corneal thickness readings, but rather to guide the determination of the eye's target IOP.

Figure 14.7 In an eye with a functional Ahmed glaucoma drainage device, B-scan ultrasonography reveals fluid-filled space surrounding the implant reservoir in the superotemporal quadrant (indicated by an x), indenting the sclera. In the office setting, the bleb was difficult to visualize but its presence was confirmed easily by using ultrasonography.

Other technologies, such as optical coherence tomography (OCT) (64) (Chapter 4), may prove useful in assessing nerve fiber layer loss in children too young to perform reliable visual field testing.

Etiology

Normal Development of the Anterior Ocular Segment

A basic understanding of the normal development of the anterior ocular segment is necessary before considering the theories of mechanism for congenital glaucoma or for any of the developmental glaucomas with associated anomalies.

General Development

The lens vesicle begins to develop as an invagination of surface ectoderm during the third week of gestation and separates from the latter structure by the sixth week (65). A study of 53 human embryos showed that the adhesion between the lens vesicle and presumptive corneal epithelium at the 8-mm stage is replaced by a “clear zone” at the 12.5-mm stage (66). The same study suggested that the formation of the eye is influenced by signals from neural and pigmented layers and that the lens, with its relatively large size and high mitosis, participates in the early embryogenesis of the rudimentary anterior chamber.

At the same time that the lens vesicle is separating from surface ectoderm, the optic cup, which arises from neural ectoderm, has reached the periphery of the lens, and a triangular mass of undifferentiated cells overrides the rim of the cup and surrounds the anterior periphery of the lens. From this tissue mass will arise portions of the cornea, iris, and the anterior chamber angle structures.

Neural Crest Cell Contribution

The undifferentiated cell mass destined to become the cornea, iris, and anterior chamber angle was originally thought to be derived from mesoderm. Subsequent studies, however, indicated that the tissue is of cranial neural crest cell origin. Johnston and colleagues (67) studied orofacial development in chick embryos. By using these models, it was determined that corneal endothelium and the stroma, iris, ciliary body, and sclera are of neural crest origin, except for the associated vascular endothelium, which is derived from mesodermal mesenchyme. Immunohistochemical studies have provided support for the concept that cells of human trabecular meshwork are also of neural crest origin by showing evidence of neuronal cell-specific enolase (68, 69). These cells were found in the anterior region of the meshwork and in the inner uveal beams (68, 69), whereas the cells lining the Schlemm canal were found to share many immunophenotypical features with vascular endothelial cells (69).

Development of Cornea and Iris

From the mass of undifferentiated cells, three waves of tissue come forward between the surface ectoderm and lens. The first of these layers differentiates into the primordial corneal endothelium by the eighth week and subsequently produces Descemet membrane, and the second wave grows between the corneal endothelium and epithelium to produce the stroma of the cornea (70, 71). The third wave insinuates between the primordia of the cornea and the lens and gives rise to the pupillary membrane and the stroma of the iris. In later months, the pigment epithelial layer of the iris develops from neural ectoderm.

Development of Anterior Chamber Angle

The aqueous outflow structures in the anterior chamber angle appear to arise from the mesenchymal mass of neural crest cell origin. The precise details of this development are not fully understood. Theories have included atrophy or resorption (i.e., progressive disappearance of portions of fetal tissue), cleavage (i.e., separation of two pre-existing tissue layers due to differential growth rates), and rarefaction (i.e., mechanical distention due to growth of the anterior ocular segment) (46, 65, 72, 73). Subsequent work suggests that none of these concepts is completely correct.

Anderson (74) studied 40 healthy fetal and infant eyes by light and electron microscopy and found that the anterior surface of the iris at 5 months' gestation inserts at the edge of the corneal endothelium, covering the cells that are destined to become trabecular meshwork. This appears to be what Worst (45) called the fetal pectinate ligament, separating the corneoscleral meshwork primordium from the anterior chamber angle. Anderson observed a posterior repositioning of the anterior uveal structures in relation to the cornea and sclera in progressively older tissue specimens, presumably because of the differential growth rates. At birth, the insertion of the iris and ciliary body is near the level of the scleral spur, and the posterior migration of these structures continues for about the first year of life.

There is some difference of interpretation regarding the innermost layer of the trabecular meshwork primordium, as it is uncovered by the posteriorly receding iris. Anderson (74) thought that the smooth surface represents multilayered mesenchymal tissue, which begins to cavitate by the seventh fetal month. Others have suggested that a true endothelial layer covers the meshwork during gestation (45, 75). Hansson and Jerndal (75) observed that the anterior chamber angle portion of the endothelial layer begins to flatten, with loss of clear-cut cell borders, by the seventh fetal month. During the final weeks of gestation and the first weeks after birth, the endothelial layer undergoes fenestration with migration of cells into the underlying uveal meshwork. Van Buskirk (76) observed a similar endothelial layer and its progressive fenestration in macaque monkey eyes. He noticed that fenestration and gradual retraction of this tissue occurred in the third trimester and progressed in a posterior-to-anterior direction. McMenamin (77), however, in a scanning electron microscopic study of 32 human fetal eyes, found that the endothelial layer in the iridocorneal angle was perforated by discrete intercellular gaps by 12 to 14 weeks and that the gaps between the inner uveal trabecular

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endothelial cells were sufficiently developed by 18 to 20 weeks to allow a route of communication between the fetal anterior chamber and primitive trabecular tissue.

Figure 14.8 A concept of anterior chamber angle development (insets show cross-sectional views of the chamber angle). A: At 5 months' gestation, a continuous layer of endothelium (e) creates a closed cavity of the anterior chamber (according to most studies), and the anterior surface of the iris (i) inserts in front of the primordial trabecular meshwork (tm). B: In the third trimester, the endothelial layer progressively disappears from the pupillary membrane (pm) and iris and cavitates over the anterior chamber angle (aca), possibly becoming incorporated in the trabecular meshwork. At the same time, the peripheral uveal tissue begins to slide posteriorly in relation to the chamber angle structures (arrow). C: Development of the trabecular lamellae and intertrabecular spaces begins in the inner, posterior aspect of the primordial tissue and progresses toward the Schlemm canal (Sc) and Schwalbe line (Sl). D: The normal anterior chamber angle is not fully developed until 1 year of age. (From Shields MB. AxenfeldRieger syndrome: a theory of mechanism and distinctions from the iridocorneal endothelial syndrome. Trans Am Ophthalmol Soc. 1983;81:736, Republished with permission of the American Ophthalmological Society.)

McMenamin (78) also showed, in light and electron microscopic studies of human fetal eyes between 12 and 22 weeks' gestation, that the trabecular anlage doubles in cross-sectional area, cell density decreases but the absolute number of cells increases twofold to threefold, extracellular matrix increases in a predictable fashion by 360%, and the intertrabecular spaces increase in a more variable manner by 200%. It appears that the trabecular meshwork develops by a simple process of growth and differentiation. These observations have been combined in a concept of anterior chamber angle development (79), which is depicted in Figure 14.8.

Theories of Abnormal Development in Congenital Glaucoma

Although it is generally agreed that the IOP elevation in congenital glaucoma is caused by an abnormal development of the anterior chamber angle that leads to obstruction of aqueous outflow, there is no universal agreement on the nature of the developmental alteration. Theories of pathogenesis parallel the basic concepts regarding the normal development of the anterior chamber angle, most of which are no longer accepted as being entirely correct. We first review the major theories that have been proposed in the past and then consider how they fit with our current understanding of the developmental abnormality of congenital glaucoma.

In 1928, Mann (80) postulated that incomplete atrophy of anterior chamber mesoderm resulted in

retention of abnormal tissue that blocked aqueous outflow. In 1955, Barkan (46) suggested that incomplete resorption of the mesodermal cells by adjacent tissue led to the formation of a membrane across the anterior chamber angle. This structure became known as the Barkan membrane, although its existence has not been proved histologically. Electron microscopic studies by Anderson (46, 81) revealed no membrane, despite the appearance of such a structure by gonioscopy and the dissecting microscope. In 1955, Allen and colleagues (72) postulated that incomplete cleavage of mesoderm in the anterior chamber angle resulted in the congenital defect. In 1966, Worst (45) proposed a combined theory that included elements of the atrophy and resorption concepts but rejected the cleavage theory. However, all of the theories for normal development of the anterior chamber angle, on which

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each of the previous theories of pathogenesis was based, are no longer thought to be correct.

In 1959, Maumenee (82, 83) observed an abnormal anterior insertion of the ciliary musculature into the trabecular meshwork and reasoned that this might compress the scleral spur forward and externally, narrowing the Schlemm canal. Anderson (74) and others (84) provided further histopathologic support for the high insertion of the anterior uvea into the trabecular meshwork, suggesting that it is caused by a developmental arrest in the normal migration of the uvea across the meshwork in the third trimester of gestation. Maumenee (83) also noticed the absence of Schlemm canal in some histopathologic specimens and suggested that this might be a cause of aqueous outflow obstruction in congenital glaucoma, although Anderson (81) thought it might be a secondary change.

In 1971, Smelser and Ozanics (73) explained congenital glaucoma as a failure of anterior chamber angle anlage to become properly rearranged into the normal trabecular meshwork. Subsequent light and electron microscopic studies favored this theory by showing structural changes of the uveal meshwork and, in some cases of infantile and juvenile glaucoma, a thick layer of amorphous material beneath the internal endothelium of the Schlemm canal (81, 85, 86, 87, 88 and 89). Kupfer and colleagues (90, 91) emphasized the contribution of the cranial neural crest cells in the development of the anterior chamber angle and suggested that abnormal development of structures derived from these cells may result in the defects of the various forms of congenital glaucoma.

In summary, most forms of congenital glaucoma appear to result from a developmental arrest of anterior chamber angle tissue derived from neural crest cells, leading to aqueous outflow obstruction by one or more of several mechanisms. The high insertion of ciliary body and iris into the posterior portion of the trabecular meshwork may compress the trabecular beams. There may be primary developmental defects at various levels of the meshwork and, in some cases, the Schlemm canal. However, a true membrane over the meshwork does not appear to be a feature of this disorder.

Differential Diagnosis

Some of the clinical features of PCG are also found in other conditions, and these must be considered in the differential diagnosis (Table 13.2).

Excessive Tearing

In the infant, excessive tearing is most commonly caused by obstruction of the lacrimal drainage system. The epiphora of nasolacrimal duct obstruction is distinguished from that of PCG (or any infantile-onset glaucoma) in that the former condition may be associated with fullness of the lacrimal sac and often has a purulent discharge. The epiphora of PCG (and any infantile glaucoma) is frequently associated with photophobia and blepharospasm, although these three findings can also result from various external ocular disorders. Any of the several types of conjunctivitis in the infant may manifest with epiphora and a “red eye,” but photophobia is usually absent. Whe n epiphora, photophobia, or blepharospasm accompanies a red eye, ocular inflammation (i.e., uveitis) and corneal injury or keratitis (e.g., abrasion, herpetic dendrite) should be considered.

Corneal Disorders Large Corneas

Large corneas may represent congenital megalocornea without glaucoma or an enlarged globe due to high myopia. However, PCG (and any infantile-onset glaucoma) also typically causes progressive

myopia resulting from enlargement of the globe. Infants with megalocornea often present with symmetrically enlarged, clear corneas with diameters larger than 14 mm, with deep anterior chambers, and with iridodonesis, but without elevated IOP or optic nerve cupping. Megalocornea is a rare, Xlinked recessive disorder; families have been described in which some individuals have megalocornea alone, whereas others present with primary infantile glaucoma (58, 92). A pedigree has been described with autosomal dominant megalocornea and congenital glaucoma in which the inheritance pattern is thought to represent germ-line mosaicism (93).

Eyes with axial myopia often show enlargement of the globe and cornea, but without elevated IOP; posterior segment examination usually demonstrates an oblique optic nerve head insertion and scleral crescent, often with suggestive chorioretinal findings. Any infant with corneal enlargement should be followed up over time for the development of elevated IOP.

Tears in Descemet Membrane

Tears in the Descemet membrane may result from forceps injury during birth (94). These tears are usually vertical or oblique, in contrast to those of congenital glaucoma (i.e., Haab striae) (Fig. 13.7), which tend to be horizontal or concentric with the limbus. Tears in the Descemet membrane may also be confused with band-like structures in posterior polymorphous dystrophy and posterior corneal vesicles (95, 96). Haab striae may be distinguished from these disorders by thin, smooth areas between thickened, curled edges, contrasting with the central thickening in posterior polymorphous dystrophy and posterior corneal vesicles (95).

Corneal Opacification

Corneal opacification in infancy may be associated with various disorders (97): developmental anomalies (i.e., Peters anomaly and sclerocornea), dystrophies (i.e., congenital hereditary corneal dystrophy and posterior polymorphous dystrophy), choristomas (i.e., dermoid and dermis-like choristoma), edema due to birth trauma, intrauterine inflammation or keratitis (i.e., congenital syphilis, rubella, and herpetic infection), and inborn errors of metabolism (i.e., mucopolysaccharidoses [MPS] and cystinosis).

Other Glaucomas of Childhood

The differential diagnosis of PCG should include developmental glaucomas with associated anomalies and the childhood glaucomas associated with other ocular and systemic disorders (many of which are discussed later in this chapter).

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Although other nonglaucomatous eye conditions may share one or more findings with PCG, care must be taken to rule out other types of childhood glaucoma in each of these cases. For example, glaucoma may complicate uveitis and has been reported in the setting of MPS; corneal dystrophy; congenital anomalies, such as Peters anomaly; and megalocornea. Glaucoma has occurred coincidentally with congenital nasolacrimal duct obstruction (98).

Management Medical Therapy

Definitive treatment of PCG is surgical in nature, with medical therapy playing an adjunctive role. Preoperatively, medications may help clear the cornea to facilitate angle surgery (especially goniotomy), and postoperatively, they may help control IOP until the adequacy of the surgical procedure has been verified. Medical therapy is also indicated in managing difficult cases in which surgery poses lifethreatening risks or has incompletely controlled the glaucoma (7). In general, the same basic principles of medical therapy apply to the treatment of PCG as to adult glaucomas. One possible exception is the use of miotics, which paradoxically may increase the IOP by collapse of the trabecular meshwork because of the high insertion of uveal tissue into the posterior meshwork. (Dosages for children and special precautions are discussed in Chapter 40.) Many obstacles conspire against the success of chronic medical therapy for PCG, including inadequate IOP control, difficulties with long-term adherence, and the potential adverse systemic effects of protracted therapy.

Surgical Therapy

The primary surgical techniques are designed to eliminate the resistance to aqueous outflow created by the structural abnormalities in the anterior chamber angle. This “angle surgery” may be achieved with incisional surgery, by using an internal (goniotomy) or external (trabeculotomy) approach. Some surgeons prefer to perform a combined angle and filtration surgery (i.e., trabeculotomy and trabeculectomy) as the initial procedure; others use this technique after initial angle surgery has failed; and still others always perform filtration surgery only after angle surgery has failed (99, 100 and 101). This discussion is limited to the concepts of management. (Details of the operative procedures are considered in Chapter 40.)

Goniotomy

Barkan (102) described a technique in which abnormal tissue (originally thought to be Barkan membrane) is incised under direct visualization with the aid of a goniolens. It is now believed that the incision is not through a membrane, but rather through the inner portion of the trabecular meshwork. This presumably relieves the compressive traction of the anterior uvea on the meshwork and eliminates any resistance imposed by incompletely developed inner meshwork.

Trabeculotomy

Harms and Dannheim (103) described a technique in which the Schlemm canal is identified by external dissection, and the trabecular meshwork is incised by passing a probe into the canal and then rotating it into the anterior chamber. One advantage of this procedure is that it can be performed in eyes with cloudy corneas, whereas goniotomy surgery requires visualization of the angle. Although some surgeons use the technique only in cases with corneal opacification, or when multiple goniotomies have failed, others prefer it as the initial procedure in PCG. In a modification of the earlier techniques, the Schlemm canal is cannulated for its entire circumference with a suture or an illuminated endoscopic probe, and then the encircling suture or endoscope is pulled, achieving a 360-degree trabeculotomy (104) (see also Chapter 40).

Goniotomy and trabeculotomy each have their advocates, and reported success rates vary considerably, with neither procedure having clear-cut superiority. Although goniotomy spares conjunctival tissues for possible later surgery, trabeculotomy can proceed even when corneal opacity precludes an angle view.

(A more detailed comparison of the two operations is presented in Chapter 40.) With both procedures, success is related to the severity and duration of the glaucoma. The worst prognosis occurs for infants with elevated pressures and cloudy corneas at birth (primary newborn glaucoma). The most favorable outcomes are seen in infants who undergo surgery between the second and eighth month of life (primary infantile glaucoma), and the surgery then becomes less effective with increasing age (105). One study of long-term surgical outcome after trabeculotomy divided 71 children into groups of congenital glaucoma (i.e., existing before 2 months of age), infantile glaucoma (i.e., occurring between 2 months and 2 years), and juvenile glaucoma (i.e., after 2 years) and reported success rates with one or more trabeculotomies of 60.3% ± 5.9%, 96.3% ± 3.6%, and 76.4% ± 7.5%, respectively (106). Future studies may someday allow genetic identification of the patients with PCG who are more likely than others to benefit from angle surgery (107).

Other Glaucoma Procedures

When incisional angle surgery (e.g., goniotomies, trabeculotomies) has failed, alternatives include filtration surgery, glaucoma drainage-device surgery, and cyclodestruction, usually in that order. (Chapter 40 includes detailed review of published series using trabeculectomy with and without the use of antimetabolites, such as mitomycin C, to treat children with glaucoma.) Although older children with phakic eyes often achieve successful glaucoma control with this surgery (108), trabeculectomy is less likely to successfully control glaucoma in young infants because of their exuberant healing and scarring response. In addition, trabeculectomy in any child carries with it a lifetime risk for endophthalmitis (109, 110, 111 and 112).

Glaucoma drainage-device surgery also has a role in the management of infants and other children refractory to angle surgery and trabeculectomy. (Detailed discussion of implant surgery in children can be found in Chapter 40.) The Molteno, Baerveldt, and Ahmed implants have been used in children, with widely varying rates of success— from about 50% to greater than 90% (113, 114, 115, 116, 117, 118,