Processes that modulate the regular architecture and, hence, transparency of the cornea are poorly understood, although proteoglycans are thought to be involved. Scheie's syndrome displays corneal opacification and systemic accumulation of glycosaminoglycans. The manifestations of these two occurrences were examined in relation to the corneal stroma. Collagen architecture was investigated by transmission electron microscopy and synchrotron x-ray diffraction. Cuprolinic blue staining located sulfated glycosaminoglycan deposits that disrupted the extracellular matrix. Unlike normal cornea, which contained collagen fibrils of remarkably uniform diameter (26.0 +/- 2.4 nm), there was a large range of fibril sizes in the Scheie's syndrome stroma (19.9 to 52.0 nm). Moreover, the distribution of fibril diameters appeared bimodal. X-ray diffraction confirmed the discovery of abnormally large stromal collagen. The results suggest a link in Scheie's syndrome between proteoglycan content/distribution and stromal disruption, and between stromal disruption and corneal opacification.