CROSS-LINKED POLY(1-VINYL-2-PYRROLIDINONE) AS A VITREOUS SUBSTITUTE

A hydrogel with a high water content was produced and tested as a poss ible vitreous substitute. The polymer (poly[1-vinyl-2-pyrrolidinone]) (PVP) was synthesized by free radical bulk polymerization of 1-vinyl-2 -pyrrolidinone (VP) in the presence of 0.25% divinyl glycol (DVG) as a crosslinking agent. The fully hydrated polymer, containing about 98% water, was clear, transparent, autoclavable, and easily injected throu gh a small-gauge needle with minimum fragmentation, and without change s in its optical properties. Dynamic mechanical analysis of the hydrog el indicated a covalently crosslinked elastic network both before and after injection. The resilience of hydrogel decreased after being subj ected to shear stress during the injection process. A cytotoxicity bio assay of the hydrogel in vitro, using cultured mouse (Balb/c-3T3) fibr oblasts, showed cytostatic but not cytocidal effects. The hydrogel was injected into the vitreous cavity of rabbits and followed up to 4 wee ks. The gel was clinically well tolerated, however opacities in the vi treous body were observed following the insertion of the gel. Histopat hological examination revealed no adverse reactions to the retina, but the presence of loose polymer particles indicated the possibility of the biodegradation of the polymer. These results suggest the potential use of crosslinked PVP hydrogels as vitreous substitutes, provided th at their biodegradation is not significant, a matter that should be fu rther investigated. (C) 1996 John Wiley & Sons, Inc.