Congenital cataract is a highly heterogeneous disorder at both the genetic and clinical-phenotypic levels. Cataracts can be classified clinically into many different types including: posterior polar, anterior polar, lamellar type, and others. The occurrence of posterior polar cataracts is rare. A posterior polar cataract is a round, discoid, opaque mass that is composed of malformed and distorted lens fibers located in the central posterior part of the lens. Posterior polar cataract is a rare form of congenital cataract. It presents at birth and involves a distinctive subtype of lens opacity, which presents as an area of degenerative and malformed lens fibers that form an opacity in the central posterior subcapsular area of the lens. The diagnosis of a posterior polar cataract is based on self-evident on slit-lamp examination and does not require special diagnostic procedures beyond a full ophthalmic examination.

Mutations in the CRYAB gene have been found to be associated with posterior polar cataract 2. A deletion mutation within exon 3, 450delA, which results in a frameshift in codon 150 and produces an aberrant protein, was found to be related to dominant posterior congenital cataract.