Posterior polymorphous dystrophy (PPD) is a slowly progressive hereditary disorder of the corneal endothelium, which leads to a variable degree of visual impairment, usually in adulthood. Corneal dystrophy, posterior polymorphous, 1 (PPCD1) is a rare mild subtype of posterior corneal dystrophy, characterized by small aggregates of apparent vesicles bordered by a gray haze at the level of Descemet membrane, an altered corneal endothelial cell structure, and an unusual proliferation of endothelial cells.

The diagnosis of PPCD is based on the clinical evaluation, a detailed patient history, and some tests, such as a slit lamp examination. Most PPCD patients do not require therapy, but some may eventually require a penetrating keratoplasty or a procedure for repairing the posterior surface of the cornea, such as a deep lamellar endothelial keratoplasty (DLEK), Descemet stripping endothelial keratoplasty (DSEK), or Descemet stripping automated endothelial keratoplasty (DSAEK).

PPCD1 is a genetically heterogeneous autosomal dominant disorder. Mutations in the VSX1 gene are the cause of PPCD1 disorder. The VSX1 gene was mapped to chromosome 20p11.21, and the protein encoded by this gene regulates the activity of the LCR and the cone opsin genes at earlier stages of development.