Effects of chronic intracameral injections of chondroitin sulfate on cat eyes.

The effect of chondroitin sulfate on the metabolism of trabecular meshwork was studied by repeatedly injecting a chondroitin sulfate solution into the anterior chamber of cat (experimental) eyes for 28-29 weeks. The aqueous humor of the opposite (control) eyes were similarly replaced with a phosphate-buffered saline-glucose solution. The intraocular pressure of the experimental eyes was increased 4-7 mm Hg above that of the control eyes for a prolonged period of time. In addition, collagen fibers, elastic fibers, and basement membrane-like material were moderately increased in the trabecular meshwork of experimental eyes. Three forms of thickened basement membranes of endothelial cells were observed. The compact multilaminated basement membrane was formed concentrically around some of the trabecular beams. The discontinuous, thin basement membrane was seen among bundles of coarse collagen in association with long spacing collagen fibers. Also, fine filaments were noted streaming from the plasma membrane and basement membrane of endothelial cells of angular aqueous veins. Chondroitinase ABC was able to remove ground substance in the elastic fiber of the trabecular meshwork. Biochemically, the chamber angle tissues from these eyes showed a higher synthetic activity of glycosaminoglycans and proteins. Chondroitin sulfate appears to have a direct effect on trabecular meshwork and can influence the physiologic function of these cells.