Lattice corneal dystrophy type IIIA. Clinical and histopathologic correlations.

All three types of lattice corneal dystrophy are inherited and localized, and they largely involve linear corneal amyloid deposits. We encountered two white families with lattice corneal dystrophy which closely resembled type III. Four generations of one family and three of another family exhibited lattice corneal dystrophy. Because both families are from Caccamo, Sicily, Italy, we believe it is likely that both are from a single mutation. Thick, ropy lattice lines were seen to traverse the corneas almost from limbus to limbus and were easily detected with direct illumination. Histopathologic examination revealed accumulations of varying sized amyloid deposits in the stroma and ribbons of amyloid between the stroma and Bowman's layer typical of lattice corneal dystrophy type III. We have named the disease in this family lattice corneal dystrophy type IIIA, because of three differences from lattice corneal dystrophy type III: the presence of corneal erosions, the occurrence in whites, and the autosomal dominant inheritance pattern.