Contributor: Gordon K. Klintworth
Rieger anomaly is part of the spectrum of anterior segment dysgenesis [dysgenesis - anterior segment]. Reiger anomaly may be associatied with Axenfeld anomaly or the Axenfeld-Rieger syndrome. Abnormalities of the teeth and bone may be associated [Rieger syndrome]. Persistence of mesenchyme in the anterior chamber angle probably forms the prominent Schwalbe ring and attached iris strands. High insertion of the iris and dysgenesis of the aqueous drainage channel is causally related to the developmental glaucoma [glaucoma - developmental], which may have a delayed onset. Juvenile glaucoma [glaucoma - juvenile] develops in 50-70% of such eyes due to faulty development of the filtration angle. Associated anomalies of the cornea are usually central and a focal absence of the corneal endothelium and Descemet membrane results in a gray to white leukoma. Ultrastructural examination of some cases show irregular basal epithelial cells, absence of Bowman layer, stromal edema and scarring with derangement of the lamellar architecture, collagen fibrils with a larger than normal diameter in the posterior stroma, absence of Descemet membrane, and endothelium in the central cornea. Fibrous tissue fills the defect. The main central corneal abnormalities are posterior keratoconus, Peters anomaly and von Hippel internal corneal corneal ulcer ulcer. Abnormal neural crest migration of the cells destined to become posterior corneal stroma, Descemet membrane and endothelium can result in this rare anomaly. Dysgenetic endothelial cells and Descemet membrane with changes similar to those found in the corneas of congenital hereditary endothelial dystrophy have been reported in a patient with Rieger anomaly adding to the spectrum of this condition. Inflammation is not a feature. A cause of Rieger anomaly is mutations in the FOXC1 and PITX2 genes.