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, 7-5Fig 7-4 and
Fig 7-5). See also BCSC Section 8, External Disease and Cornea.
, CoxCJ, SeminaEV, AmendtBA. A molecular basis for differential developmental anomalies in Axenfeld-Rieger syndrome.2002;11(7):743–753.