The IC3D classification of the corneal dystrophies.
BACKGROUND
The recent availability of genetic analyses has demonstrated the shortcomings of the current phenotypic method of corneal dystrophy classification. Abnormalities in different genes can cause a single phenotype, whereas different defects in a single gene can cause different phenotypes. Some disorders termed corneal dystrophies do not appear to have a genetic basis.


OBJECTIVE
The purpose of this study was to develop a new classification system for corneal dystrophies, integrating up-to-date information on phenotypic description, pathologic examination, and genetic analysis.


METHODS
The International Committee for Classification of Corneal Dystrophies (IC3D) was created to devise a current and accurate nomenclature.


RESULTS
This anatomic classification continues to organize dystrophies according to the level chiefly affected. Each dystrophy has a template summarizing genetic, clinical, and pathologic information. A category number from 1 through 4 is assigned, reflecting the level of evidence supporting the existence of a given dystrophy. The most defined dystrophies belong to category 1 (a well-defined corneal dystrophy in which a gene has been mapped and identified and specific mutations are known) and the least defined belong to category 4 (a suspected dystrophy where the clinical and genetic evidence is not yet convincing). The nomenclature may be updated over time as new information regarding the dystrophies becomes available.


CONCLUSIONS
The IC3D Classification of Corneal Dystrophies is a new classification system that incorporates many aspects of the traditional definitions of corneal dystrophies with new genetic, clinical, and pathologic information. Standardized templates provide key information that includes a level of evidence for there being a corneal dystrophy. The system is user-friendly and upgradeable and can be retrieved on the website www.corneasociety.org/ic3d.
Weiss
Jayne S
JS
Department of Ophthalmology, Kresge Eye Institute, Wayne State University School of Medicine, Detroit, MI 48201, USA. jweiss@med.wayne.edu
Møller
H U
HU
Lisch
Walter
W
Kinoshita
Shigeru
S
Aldave
Anthony J
AJ
Belin
Michael W
MW
Kivelä
Tero
T
Busin
Massimo
M
Munier
Francis L
FL
Seitz
Berthold
B
Sutphin
John
J
Bredrup
Cecilie
C
Mannis
Mark J
MJ
Rapuano
Christopher J
CJ
Van Rij
Gabriel
G
Kim
Eung Kweon
EK
Klintworth
Gordon K
GK