Definition:

Posterior polymorphous corneal dystrophy (PPCD) is a very rare, bilateral autosomal dominant disorder affecting primarily the innermost corneal layers, Descemet membrane (DM), and the endothelium, biomicroscopically presenting as geographical lesions, bands, and vesicles. It primarily affects the corneal endothelium to produce epithelial-like transformation and irregular thickening of DM due to the deposition of an abnormal collagenous layer. Most cases are static, but occasionally rapid progression can result in severe visual disability from secondary glaucoma or corneal edema. Several genes have been reported as causing PPCD.