Effects of intracameral injection of chondroitinase ABC in vivo.

A glycosaminoglycan-degrading enzyme, chondroitinase ABC, was introduced into the anterior chamber of three cynomolgus monkeys. Following the injection, the intraocular pressure decreased in the experimental eyes. Depending on the monkey, the intraocular pressure was lowered for 5, 7, or 14 days before it returned to the normal level. Repeated injections produced a similar response. Structurally, the intertrabecular spaces appeared widened, and marked ballooning of the juxtacanalicular tissue was observed. The outer trabecular beams and the inner wall of Schlemm's canal were greatly disorganized. Considerable loss of the juxtacanalicular tissue was noted even 2 months after the enzyme was injected into the anterior chamber. These observations suggest that chondroitinase ABC digested the trabecular glycosaminoglycans, triggering intraocular pressure reduction and causing disorganization of the extracellular matrices of the disorganized trabecular beams, especially in areas near Schlemm's canal.