The IC3D Classification of the Corneal Dystrophies

Abstract

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. Purpose 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.

Reis-Bücklers Corneal Dystrophy: A Reappraisal Using in vivo and ex vivo Imaging Techniques

“…The relationship between RBCD, granular dystrophy and lattice type-1 dystrophy has been further explained by molecular genetic studies. These dystrophies could be different phenotypic expressions of the same gene mutation (βIGH3) on chromosome 5q31 [5,18]. Our data showing that genetically proven RBCD patients have both anterior and posterior stromal involvement may also support this finding.…”

“…However, in clinical practice, corneal dystrophies are mostly diagnosed and differentiated using siltlamp biomicroscopy. Because the slitlamp cannot provide details of corneal structures at the cellular level, many corneal dystrophies and most particularly granular dystrophies are difficult to distinguish [5,6]. Recently developed in vivo imaging techniques such as in vivo confocal microscopy (IVCM) and anterior segment (AS) optical coherence tomography (OCT) are providing new insights into the clinical evaluation of corneal dystrophies [7,8].…”

“…A specific clinical and histological phenotype associated with the identification of the gene mutation makes a precise diagnosis of RBCD possible [5]. However, in clinical practice, corneal dystrophies are mostly diagnosed and differentiated using siltlamp biomicroscopy.…”

A review on ocular findings in mouse lemurs: potential links to age and genetic background

“…Thus, it is not possible to assess the effect of genetic background or age on this eye pathology. Since corneal dystrophies are under close investigation in humans, the genetic background in several forms is already well defined (Weiss et al, 2008;Klintworth, 2009). This makes the genetic background for corneal dystrophies in mouse lemurs likely and the investigation of concerned lineages interesting for future studies.…”

“…Cornea dystrophy is multifactorial and includes a high variety of clinical manifestations, while impairments can vary from minimal impact to complete blindness. Cornea dystrophy is defined as an inherited disorder of the cornea itself, which forms spontaneous bilateral opacities and usually has no systemic manifestation (Weiss et al, 2008;Klintworth, 2009;Weiss et al, 2015).…”