posterior surface of the cornea. (Courtesy of Nasreen A. Syed, MD.)

Figure 7-2 Normal anterior chamber angle. Gonioscopic landmarks of the anterior chamber angle with histologic correlation.

TM = trabecular meshwork. (Courtesy of Tatyana Milman, MD.)

Congenital Anomalies

BCSC Section 10, Glaucoma, also discusses the conditions described in the following sections.

Primary Congenital Glaucoma

Primary congenital glaucoma, also referred to as congenital or infantile glaucoma, becomes evident at birth or within the first few years of life. The pathogenesis of primary congenital glaucoma may be related to the arrested development of the anterior chamber angle structures. Histologically, the anterior chamber angle retains an “embryonic” or “fetal” conformation, characterized by anterior insertion of the iris root, a poorly developed scleral spur with insertion of the ciliary body muscle directly into the trabecular meshwork, and mesenchymal tissue in the anterior chamber angle (Fig 7- 3). See BCSC Section 6, Pediatric Ophthalmology and Strabismus, for detailed discussion.

Figure 7-3 Congenital glaucoma. Fetal anterior chamber angle demonstrates anterior insertion of the iris root (red arrow), anteriorly displaced ciliary processes, and a poorly developed scleral spur (black arrow) and trabecular meshwork

(arrowhead). (Courtesy of Tatyana Milman, MD.)

Anterior Segment Dysgenesis

Anterior segment dysgenesis is the term used for a spectrum of developmental anomalies resulting from abnormalities of neural crest migration and differentiation during embryologic development (Axenfeld-Rieger syndrome, Peters anomaly, posterior keratoconus, and iridoschisis). Maldevelopment of the anterior chamber angle is most prominent in Axenfeld-Rieger syndrome, an autosomal dominant disorder, which itself encompasses a spectrum of anomalies, ranging from isolated bilateral ocular defects to a fully manifested systemic disorder. The single most important clinical feature of Axenfeld-Rieger syndrome phenotypes is that they confer at least a 50% risk of developing glaucoma.

Ocular manifestations of Axenfeld-Rieger syndrome include posterior embryotoxon (a thickened and anteriorly displaced Schwalbe line [termination of Descemet membrane]), iris strands adherent to the Schwalbe line, iris hypoplasia, corectopia and polycoria, and a maldeveloped or “fetal” anterior chamber angle (discussed earlier) (Figs 7-4, 7-5). See also BCSC Section 8, External Disease and Cornea.

Espinoza HM, Cox CJ, Semina EV, Amendt BA. A molecular basis for differential developmental anomalies in Axenfeld-Rieger syndrome. Hum Mol Genet. 2002;11(7):743–753.

Figure 7-4 Posterior embryotoxon. Light micrograph shows a nodular prominence at the termination of the Descemet

membrane (arrow). TM = trabecular meshwork. (Courtesy of Hans E. Grossniklaus, MD.)