Distribution of amyloid and BIG‐H3 in the cornea and limbus of a patient with lattice corneal dystrophy. Unique findings in donated eyes

Abstract

Abstract Purpose The lattice corneal dystrophies (LCDs) are hereditary diseases involving the formation of opaque or refractile, amyloid‐containing filaments in the corneal stroma. We report the distribution of amyloid and big‐h3 protein in cornea and limbus in a patient suffering with LCD. Methods An 84 year‐old patient with lattice corneal dystrophy died and donated her eyes for further study. The corneal and limbal tissue of the patient processed for light and electron microscopy. The primary polyclonal antibody big‐h3 was located by secondary, goat anti‐rabbit antibody conjugated with gold. Results In cornea amyloid deposits were observed below epithelium, and in the anterior and middle stroma. The epithelium was thin and invaginated by the amyloid deposits. In the limbus, large numbers of amyloid deposits were observed in sub‐epithelial region, and in the mid and deep stroma. Subepithelial amyloid was also present in the substantia propria beneath the bulbar conjunctival epithelium. The amyloid deposits contained very thin amyloid fibrils and strongly stained with big‐h3 antibody. There were also numerous long spacing collagen fibrils observed in the mid stroma, which also labelled with the antibody. Conclusion This is the first report of structural changes in the peripheral cornea and limbus in LCD. It is thought that mutated big‐h3 protein diffuse into the stroma from the corneal epithelium to form amyloid deposits. The presence of amyloid and big‐h3 at the limbus and in the adjacent bulbar conjunctiva and perilimbal cornea, suggests that Big‐h3 is overproduced in these regions, which are normally free from clinically detectable disease.