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CONGENITAL GLAUCOMA

Congenital glaucoma (rare) can be subdivided into (1) primary congenital glaucoma, in which the developmental abnormalities are restricted to the anterior chamber angle; (2) the anterior segment developmental anomalies-Axenfeld's syndrome, Peter's anomaly, and Rieger's syndrome-in which iris and corneal development are also abnormal; and (3) a variety of other conditions-including aniridia, Sturge-Weber syndrome, neurofibromatosis-1, Lowe's syndrome, and congenital rubella-in which the developmental anomalies of the angle are associated with other ocular or extraocular abnormalities.

Clinical Findings

Congenital glaucoma is manifest at birth in 50%, diagnosed in the first 6 months in 70%, and diagnosed by the end of the first year in 80%. The earliest and most common symptom is epiphora. Photophobia and decreased corneal luster may be present. Increased intraocular pressure is the cardinal sign. Glaucomatous cupping of the optic disk is a relatively early-and the most important-change. Later findings include increased corneal diameter (above 11.5 mm is considered significant), epithelial edema, tears of Des-cemet's membrane, and increased depth of the anterior chamber (associated with general enlargement of the anterior segment of the eye) as well as edema and opacity of the corneal stroma (Figure 11-9).

Differential Diagnosis

Megalocornea, corneal clouding due to congenital dystrophy or mucopolysaccharidoses, and traumatic rupture of Descemet's membrane should be ruled out. Measurement of intraocular pressure, gonioscopy, and evaluation of the optic disk are important in making the differential diagnosis. Assessment generally requires examination under general anesthesia.

Course & Prognosis

In untreated cases, blindness occurs early. The eye undergoes marked stretching and may even rupture with minor trauma. Typical glaucomatous cupping occurs relatively soon, emphasizing the need for early treatment.

1. ANTERIOR SEGMENT DEVELOPMENTAL ANOMALIES

These rare diseases constitute a spectrum of maldevelopment of the anterior segment, involving the angle, iris, cornea, and occasionally the lens. Usually there is some hypoplasia of the anterior stroma of the iris, with bridging filaments connecting the iris stroma to the cornea. If these bridging filaments occur peripherally and connect to a prominent, axially displaced Schwalbe's line (posterior embryotoxon), the disease is known as Axenfeld's syndrome. This resembles the trabeculodysgenesis of primary congenital glaucoma. If there are broader iridocorneal adhesions associated with the disruption of the iris, with polycoria and, in addition, skeletal and dental anomalies, the disorder is called Rieger's syndrome (an example of iridotrabecular dysgenesis). If adhesions are between the central iris and the central posterior surface of the cornea, the disease is known as Peter's anomaly (an example of iridocorneal trabeculodysgenesis).

These diseases are usually dominantly inherited, though sporadic cases have been reported. Mutations on chromosomes 4 and 13, probably involving homeobox genes, have been identified in pedigrees with Axenfeld-Rieger syndrome. Glaucoma occurs in approximately 50% of such eyes and often does not present until late childhood or early adulthood. Goniotomy has a much lower success rate in these cases, and trabeculotomy or trabeculectomy may be recommended. Many such patients require long-term medical glaucoma therapy, and the prognosis is guarded for long-term retention of good visual function.

2. ANIRIDIA

The distinguishing feature of aniridia, as the name implies, is the vestigial iris. In many cases, little more than the root of the iris or a thin iris margin is present. Other deformities of the eye may be present, such as congenital cataracts, corneal dystrophy, and foveal hypoplasia. Vision is usually poor. Glaucoma frequently develops before adolescence and is usually refractory to medical or surgical management.

This rare syndrome is genetically determined. Both autosomal dominant and autosomal recessive inheritance have been reported.

If medical therapy is ineffective, goniotomy or trabeculotomy may occasionally normalize the intraocular pressure. Filtering operations are often necessary, but the long-term visual prognosis is poor.

10.1036/1535-8860.ch11

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