A viscous bioerodible poly(ortho ester) as a new biomaterial for intraocular application

The biocompatibility of a viscous, hydrophobic, bioerodible poly(ortho este r) (POE) intended for intraocular application was investigated. POE was eva luated as a blank carrier and as containing modulators of degradation. Each formulation was injected intracamerally and intravitreally in rabbit eyes, and clinical and histological examinations were performed postoperatively for 2 weeks. In the case of intracameral injections, polymer biocompatibili ty appeared to depend on the amount injected in the anterior chamber. When 50 mu L was administered, the polymer degraded within 2 weeks, and clinical observations showed good biocompatibility of POE with no toxicity to the o cular tissues or increase in intraocular pressure. The injection of a large r volume, 100 mu L, of POE, appeared inappropriate because of direct contac t of polymeric material with the corneal endothelium, and triggered reversi ble edema and inflammation in the anterior chamber of the eye that regresse d after a few days. After intravitreal administration, POE was well tolerat ed and no inflammatory reaction developed during the observation period. Th e polymer degraded slowly, appearing as a round whitish bubble in the vitre ous cavity. The presence of modulators of degradation both improved POE bio compatibility and prolonged polymer lifetime in the eye. POE appears to be a promising biomaterial for clinical intraocular application. (C) 2000 John Wiley & Sons, Inc.