Anterior segment mesenchymal dysgenesis

Anterior segment mesenchymal dysgenesis, also called anterior segment dysgenesis, is a failure of the normal development of the tissues in the front part of the eye. It leaves the mature anterior segment with structural anomalies and raises the risk of glaucoma and corneal opacity. Peters' anomaly is a specific type, with a central corneal leukoma, adhesions between the iris and cornea, and abnormalities of the posterior corneal stroma, Descemet's membrane, corneal endothelium, lens and anterior chamber. Several gene mutations have been identified, mostly in genes that encode transcriptional regulators. PITX2 and FOXC1 are thought to work together to specify mesenchymal progenitor cells, mainly of neural crest origin, that migrate around the embryonic optic cup and then differentiate into the distinct tissues of the anterior segment, and PAX6 has been implicated in Peters' anomaly. Development is sensitive to gene dosage, which helps explain the variability of the condition. No standard treatment is approved. Surgical techniques tried include penetrating keratoplasty, cataract aspiration or lensectomy, optical iridectomy, selective endothelial removal, trabeculectomy and glaucoma drainage implants, but results are poor because of severe amblyopia and complications such as glaucoma and retinal detachment. The German ophthalmologist Albert Peters is credited with first describing this congenital anomaly.