IC3D second edition: an update

Abstract

AbstractThe International Committee for Classification of Corneal Dystrophies (IC3D) was created by the Cornea Society in Chicago in 2005 to revise the corneal dystrophy nomenclature. The initial group consisted of 15 corneal specialists and 2 ophthalmic pathologists from North America, Europe and Asia, chaired by Dr. Jayne Weiss. The first IC3D edition was published in 2008. Already 6 years later, sufficient new data had become available to begin revision of the IC3D by 13 original and 2 new corneal specialists and 1 original ophthalmic pathologist. The second edition was published in 2015. Like the first one it presents each dystrophy as a template with key characteristics and typical clinical images, but is now supplemented with typical anterior segment OCT and histopathologic images as well. The category of ‘Bowman layer dystrophies’ was replaced by ‘Epithelial–stromal TGFBI dystrophies’ and ‘Descemet Membrane and Endothelial Dystrophies’ was simplified to ‘Endothelial Dystrophies’ because Bowman and Descemet are acellular and secondarily affected. Congenital Hereditary Endothelial Dystrophy 1 (CHED1) was merged with posterior polymorphous dystrophy 1 (PPMD1). Posterior amorphous corneal dystrophy (PACD) was found to be caused by a joint deletion of keratocan (KERA), lumican (LUM), decorin (DCN), and epiphycan (EPYC) genes. After publication of the second IC3D, epithelial recurrent erosion dystrophy (ERED) has been linked with COL17A1 mutations across the world, and the so called ‘variant Thiel‐Behnke dystrophy’, that was dubious, was found to be identical with ERED. The corneal dystrophy field continues to develop, making a third edition likely in the future.