Cornea plana is an extremely rare, congenital hereditary malformation of the corneoscleral shape, characterized by a flattened corneal surface associated with hyperopia and various anterior segment abnormalities.  Autosomal cornea plana 2 is distinguished from dominant cornea plana 2 by a round and opaque thickening, -5 mm in width located centrally.  This thickening occurs in most cases of the CAN2 recessive form, but never in the dominant form.  Additional anomalies, such as malformations of the iris, a slit-like pupil, and adhesions between the iris and cornea, are more prevalent in the recessive CAN2 form.  Also the phenotype of recessive cornea plana 2 is generally non-progressive.

Autosomal recessive cornea plana 2 is associated with mutations in KERA gene. KERA encodes keratan sulfate proteoglycan, which is involved in the maintenance of corneal transparency.