children. A Koeppe lens allows direct visualization of the angle structures. In older children, indirect gonioscopy can be performed with a 4-mirror goniolens at the slit lamp.

The normal anterior chamber angle of an infant differs from the normal adult angle in several ways. The trabecular meshwork is less pigmented, the Schwalbe line less prominent, and the junction between the scleral spur and ciliary body band less distinct in normal infant angles than in normal adult angles. In PCG, the anterior chamber is deep, with a high anterior iris insertion. The angle recess is absent, and the iris root appears as a scalloped line of glistening tissue. This tissue has been referred to as the Barkan membrane, although it is not a true membrane but probably represents thickened and compacted trabecular meshwork (see Fig 6-2).

In JOAG, the angle usually appears normal. In aniridia, gonioscopy reveals a rudimentary iris root with progressive narrowing and synechial closure.

Optic Nerve and Fundus Evaluation

Visualization and documentation of the optic nerve are crucial to the evaluation and management of childhood glaucomas. Indirect ophthalmoscopy is usually inadequate for accurate assessment of the optic nerve. Direct ophthalmoscopy can be performed in the office or operating room. In patients with small pupils, viewing can be enhanced by performing direct ophthalmoscopy through a Koeppe lens without a dimple. In older children, slit-lamp biomicroscopy can be performed. Photographs provide the best documentation and help in the evaluation of changes over time.

The typical newborn without glaucoma has a small physiologic cup (cup–disc ratio [CDR] of <0.3) with a pink rim. In PCG, there is stretching of the optic canal and backward bowing of the lamina cribrosa, causing generalized cup enlargement. Enlarged or increasing CDR or CDR asymmetry greater than 0.2 between the 2 eyes is suggestive of glaucomatous cupping. Cupping may be reversible if the IOP is lowered; however, lowering IOP cannot reverse any existing atrophy of the optic nerve axons.

Axial Length

Serial measurements of axial length using A-scan ultrasonography can document progressive globe enlargement in patients with PCG. Axial length may stabilize or decrease with control of IOP, and this stabilization or decrease is a critical marker of successful surgical control of IOP.

Other Testing

B-scan ultrasonography should be performed whenever media opacities, particularly corneal edema, preclude fundus evaluation. Scanning laser ophthalmoscopy and optical coherence tomography can provide useful longitudinal data in older children with clear media; however, no normative data are available in children.

Treatment Overview

Surgical Management

Medications have limited long-term value in the treatment of most cases of PCG, and surgery is the preferred, definitive therapy. Goniotomy and trabeculotomy ab externo are the procedures of choice for the treatment of PCG. Either procedure is appropriate if the cornea is clear; trabeculotomy should be performed if the cornea is cloudy. In patients with clear corneas, angle surgery with either goniotomy or trabeculotomy yields a 70%–80% success rate. Angle surgery may also be used to treat

other forms of childhood glaucoma, including glaucoma associated with aniridia, Axenfeld-Rieger syndrome, or Sturge-Weber syndrome. Trabeculectomy and glaucoma drainage device implantation should be reserved for those cases of congenital glaucoma in which goniotomy or trabeculotomy has failed or for treatment of other forms of childhood glaucoma. Cyclophotocoagulation is necessary in some intractable cases, but because of the risk of phthisis, it should be avoided if possible.

Glaucoma surgery in children poses unique difficulties. For example, in PCG, the anatomical landmarks are distorted in the buphthalmic eye, and the thin sclera presents additional difficulties during trabeculotomy and trabeculectomy. The surgeon undertaking surgery in pediatric glaucoma patients should have experience with these particular intraoperative issues and should be able to provide the necessary environment for evaluating these patients postoperatively. Since additional surgery is often required, the surgeon should develop a long-term plan in order to keep surgical options available for future use and to minimize the risk of visual compromise.

The decision to proceed with angle surgery is often made during an EUA; ideally, if glaucoma is diagnosed, angle surgery should be performed during the same anesthesia session in order to minimize the number of general anesthesia sessions the child will require. If angle surgery is anticipated, it is best not to dilate the eye during the EUA. This protects the lens during the surgical procedure.

In goniotomy, the angle is visualized with a surgical gonioscopic contact lens, a needle knife is passed across the anterior chamber, and a superficial incision is made in the uveal trabecular meshwork (Fig 6-3). A clear cornea is required in order to visualize the chamber angle.

Figure 6-3 Goniotomy incision as seen through a surgical contact lens.

In trabeculotomy, the Schlemm canal is cannulated from an ab externo approach, and the trabecular meshwork is opened by breaking through the Schlemn canal into the anterior chamber. The procedure begins with creation of a conjunctival flap, beneath which a partial-thickness scleral flap is created, similar to trabeculectomy. Beneath the partial-thickness scleral flap, the surgeon identifies the Schlemm canal either by creating a radial incision into the sclera or by dissecting a deep scleral flap and noting the canal at the edges of this flap. Alternatively, the surgeon can identify the canal edges after unroofing the Schlemm canal with a single deep scleral flap. A fine wirelike instrument (trabeculotome) is inserted into the Schlemn canal and then rotated into the anterior chamber, tearing the trabecular meshwork (Fig 6-4). Alternatively, a 6-0 nonabsorbable polypropylene suture (Prolene) can be fed through the Schlemm canal for 360° and pulled tautly into the anterior chamber. When using either the trabeculotome or suture, the surgeon must take care to avoid creating a false passage or entering the subretinal or suprachoroidal spaces.

Schlemm canal until the cannula passes 360°. The ends of the catheter can then be grasped and pulled in opposite directions to perform a 360° trabeculotomy.

Many surgeons fill the anterior chamber with viscoelastic at the start of goniotomy and trabeculotomy in order to prevent collapse of the chamber and to tamponade bleeding intraoperatively. Thorough removal of the viscoelastic at the end of the procedure is necessary to prevent a postoperative spike in IOP.

Although the success rates of the 2 angle surgeries are similar, each procedure has its advantages and disadvantages. When the cornea is clear, goniotomy has the following advantages over trabeculotomy: there is no postoperative conjunctival scarring, the presence of which can limit future filtering surgery; the procedure is much faster, and there is less trauma to the anterior segment tissues. Trabeculotomy offers the following advantages: the approach to trabeculotomy is more familiar to surgeons experienced in adult glaucoma procedures; trabeculotomy can be performed in an opacified cornea; and it can be converted to a trabeculectomy if the Schlemm canal cannot be cannulated.

Complications associated with these procedures include hyphema, infection, lens damage, and uveitis. Descemet membrane may be stripped during trabeculotomy. General anesthesia may cause serious complications in children; to minimize the risks associated with general anesthesia, bilateral procedures are performed in some children.

Angle surgery is successful in 70%–80% of infants with PCG who present between 3 months and 1 year of age, although a second procedure may be required. A second angle procedure should be performed if the first surgery is not successful. Trabeculectomy or implantation of a glaucoma drainage device should be considered when 2 or more angle surgeries are not successful in lowering the IOP; when adjunctive medical therapy is inadequate; or in children who have forms of glaucoma other than PCG, although angle surgery is often successful in aphakic glaucoma and in new onset of glaucoma in aniridia.

If angle surgery is not successful, the next procedure should be trabeculectomy or implantation of a glaucoma drainage device. The surgeon must consider several factors when deciding between these 2 options. Trabeculectomy has a low success rate in children younger than 2 years and in aphakic eyes. Bleb scarring and failure are very prevalent without the use of antifibrotics, but there are serious risks of bleb leaks and bleb infections when these agents are used. Until the child is old enough to understand good hygiene, mitomycin C (MMC)–augmented trabeculectomy should be performed with caution in the pediatric patient to avoid the risk of blebitis and endophthalmitis.

Glaucoma drainage devices are useful for lowering IOP, and they avoid the risk of bleb-related infections. Success rates vary with different drainage devices, diagnoses, and patient age. Complications include anterior migration of the drainage device with resultant corneal damage, tube blockage, cataract, motility disturbances, bleb encapsulation with elevated IOP, and pupil distortion. The IOPs are usually higher after implantation of these devices than after trabeculectomy, and most of these children will need to continue using topical glaucoma medications. The various styles and sizes of glaucoma drainage devices can help individualize the surgery to the patient’s situation.

Cyclodestruction is reserved for cases refractory to other surgical and medical treatments. Cyclodestructive procedures lower IOP by destroying regions of the ciliary body to decrease aqueous production. Cyclodestructive techniques include cyclocryotherapy, transscleral cyclophotocoagulation (CPC) with the Nd:YAG or diode laser, and endoscopic cyclophotocoagulation (ECP). When these techniques are used in pediatric patients, general anesthesia is required. One disadvantage of cyclodestructive techniques is that it can be difficult to titrate the results. Another disadvantage is that the potential complications—which include hypotony, uveitis, phthisis, and blindness—are serious. The rate of complications is lower with cyclodestructive laser