Crystalline corneal dystrophy in the dog. Histochemical and ultrastructural study.

Crystalline stromal dystrophy a condition resembling human Schnyder's crystalline stromal dystrophy, is described in both the Cavalier King Charles Spaniel and Rough Collie breeds of dog. Both clinical cases and controls were normolipoproteinaemic; neither showed evidence of arcus lipoides corneae. Lipid histochemistry indicated the presence of cholesterol, cholesterol ester, and phospholipid in the superficial stroma. Free fatty acids were also detected in some samples, but triglycerides were not detected in any samples. Electron microscopy showed lamellated and nonlamellated vacuoles both within and outside abnormal fibroblasts. Acicular and rhomboidal clefts, some with a characteristic notch, were observed mainly in extracellular locations, although they were also associated with dying fibroblasts. The epithelium, basal lamina, Descemet's membrane, and endothelium were unaffected, apart from an irregularity of the basal lamina in some specimens.