Posterior Amorphous Corneal Dystrophy

Posterior amorphous corneal dystrophy (PACD) is a very rare form of stromal corneal dystrophy (see this term) characterized by irregular amorphous sheet-like opacities in the posterior corneal stroma and in Descemet membrane and mildly impaired vision.

Epidemiology

Prevalence of this form of corneal dystrophy is not known. To date cases have been reported primarily in the USA.

Clinical description

Patients usually develop corneal abnormalities in infancy or childhood. The condition is non-progressive or slowly progressive. Visual acuity is usually only minimally affected but in some more severe cases, penetrating keratoplasty (PK) may be warranted. Unlike other corneal dystrophies, non-corneal manifestations have been observed and include abnormalities of the iris (iridocorneal adhesions, corectopia, and pseudopolycoria).

Etiology

The etiology of the condition is not known but it is thought to be genetic. The chromosomal locus of the gene responsible for PACD has not been determined.

Diagnostic methods

Opacities are diffuse gray-white and sheet-like and can involve any layer of the stroma but are most prominent posteriorly. The lesions can be centroperipheral, extending to the limbus, or peripheral, the latter with less pronounced findings and symptoms. There are often transparent stromal breaks in the opacification.

Genetic counseling

An autosomal dominant pattern of inheritance has been reported.

Management and treatment

Since the entire stroma is involved, a penetrating kertopasty is indicated if visual impairment is clinically significant.