Early-onset vs. Late-onset Fuchs Dystrophy
Both types of Fuchs' dystrophy share the same general features of pathological progression. Endothelial guttae are formed, which eventually leads to the formation of corneal edema (swelling). There are, however, subtle differences in physical appearance that can be observed through examination of the two types of disease.
Early-onset guttae are usually more coarse and distinct while those in late-onset appear more fine and patchy. The excrescences (dewdrop-like protrusions) in early-onset Fuchs possess sharper margins. Areas of coalescence (where the guttae merge together into one big patch) are clearly evident with definite intervening areas that had not been affected. Those in late-onset, however, are uniformly elevated and spread out. Furthermore, confocal microscopy indicated that late-onset guttae are generally associated with individual endothelial cells while this correlation is not present for early-onset Fuchs. The association of guttae with individual endothelial cells may be related to the subtle yet numerous guttae viewed through the slit lamp.
One gene that has been discovered to be responsible for Early Onset Fuchs Dystrophy is COL8A (on chromosome 1). It is shown below:
Mutations in Chromosomes 13 and 18 have also been discovered. These are linked to late-onset Fuchs dystrophy. These mutations are illustrated below: