Glycosaminoglycans in pterygium tissues and normal conjunctiva.

Glycosaminoglycans (GAG) in pterygium tissues were analyzed and the results were compared with those in the normal human conjunctiva. A marked difference in the GAG composition was found: 78% of the total hexosamines of GAG from pterygium was glucosamine, whereas 98% of those of the conjunctiva was galactosamine. Pterygium contained mainly hyaluronic acid (48.8%), followed by chondroitin sulfate A, chondroitin sulfate C, chondroitin and dermatan sulfate in this order. The normal conjunctiva contained mainly chondroitin sulfate C (73.5%), followed by chondroitin sulfate A and chondroitin sulfate E-like GAG. The amino acid composition showed some differences between pterygium and normal conjunctiva. The pterygium tissues contained an extremely large amount of hydroxyproline, but the conjunctiva contained a very small amount of this substance. Considerable changes in amino acid composition of both tissues were found after digestion with elastase.