Crystalline stromal dystrophy: histochemistry and ultrastructure of the cornea

A report of a woman in her fifties with Schnyder's crystalline stromal dystrophy is presented. There is no personal or family history of hypercholesterolaemia. A full thickness corneal disc was removed before grafting and examined by polarised light, histochemistry, and electron microscopy. Specific lipid histochemical methods showed deposits of cholesterol and cholesterol ester in the superficial stroma and in Bowman's membrane, but no triglyceride or free fatty acids were detected. Electron microscopy showed disruption of the superficial corneal stroma and Bowman's zone by cholesterol crystals and the presence of extracellular lamellated lipid droplets with a 4-4.5 nm periodicity. The epithelium, endothelium, and Descemet's membrane were virtually unaffected. The role of corneal grafting in crystalline stromal dystrophy is evaluated and the possible mechanisms of lipid accumulation in this disease are discussed.