Unusual Presentation of Presumed Posterior Polymorphous Dystrophy Associated With Iris Heterochromia, Band Keratopathy, and Keratoconus

Abstract

To report an unusual presentation of posterior polymorphous corneal dystrophy (PPCD) associated with band keratopathy, iridocorneal adhesions, heterochromia, keratoconus, and confocal microscopic findings suggestive of iridocorneal endothelial syndrome. Confocal microscopy, corneal topography, electroretinography, and genetic analysis were performed in the proband and his siblings. A 23-year-old man presented with decreased vision in both eyes over 9 months. Examination revealed bilateral alterations in corneal endothelial mosaic with corneal edema and beaten metal appearance in the right eye and cystoid endothelial opacities in the left eye. Marked heterochromia, band keratopathy, and broad peripheral anterior synechiae were present in both eyes. Topographic features of keratoconus were noted. Electroretinography did not detect abnormal retinal function, as has been described with PPCD associated with VSX1 mutations. Diagnosis of PPCD was postulated on the basis of the examination of 3 of proband's brothers by confocal microscopy. Genetic analysis of 3 known PPCD genes, VSX1, COL8A2, and TCF8, did not detect any mutations. In severe cases, PPCD can resemble iridocorneal endothelial syndromes in both clinical appearance and imaging studies (confocal microscopy). There was a strong genetic phenotypic penetrance in the family, which was essential in the diagnostic decision making. A yet undetermined genotype is contributing to this unusual PPCD phenotype.