Ocular histopathology and ultrastructure of Sanfilippo's syndrome, type III-B.

The ocular histopathology of systemic mucopolysaccharidosis, type III-B (Sanfilippo's syndrome) was studied using histochemical and ultrastructural techniques. Cytoplasmic, single-membrane-bound vacuoles containing the major storage product, acid mucopolysaccharide, were found in virtually every ocular tissue. Lamellar cytoplasmic membranous bodies of complex lipid were found mainly in the retinal ganglion cells and the lens epithelium. Many tissues had inclusions that were of an intermediate type and were composed of combined fibrillogranular and lamellar membranous material. Hypopigmentation of the neuroepithelial pigment layers (ie, iris, ciliary, and retinal) seems to be the result of autophagocytosis with melanolysis. Photoreceptor cell degeneration was similar to that seen in some forms of retinitis pigmentosa. The mechanism of photoreceptor cell degeneration is unknown. It may be the result of metabolic dysfunction due to accumulation of mucopolysaccharide in the retinal pigment epithelium.