Hyaluronidase for pharmacologic vitreolysis.

Various pharmacologic vitreolysis agents, including hyaluronidase, urea, plasmin, dispase, tissue plasminogen activator and chondroitinase have been tested. Pharmacologic vitreolysis can avoid the complications of surgery such as cataract, endophthalmitis, retinal hemorrhage, tear or detachment, and anesthesia related complications. Hyaluronan is a major macromolecule of vitreous. It is a long, unbranched polymer of repeating disaccharide (glucuronic acid beta (1,3)-N-acetylglucosamine) moieties linked by beta 1-4 bonds. Hyaluronan is covalently linked to a protein core, to form a proteoglycan. It plays a pivotal role in stabilizing the vitreous gel. Hyaluronidase cleaves glycosidic bonds of hyaluronic acid and, to a variable degree, other acid mucopolysaccharides of the connective tissue. Dissolution of the hyaluronic acid and collagen complex results in decreased viscosity of the extracellular matrix. This in turn increases the diffusion rate of erythrocytes and exudates along with phagocytes through the vitreous and facilitates red blood cell lysis and phagocytosis.