Experimental intracameral injection of vancomycin microparticles in rabbits.

PURPOSE To evaluate the in vivo toxicity and efficacy of previously developed poly-(lactide-co-glycolide)-vancomycin-based microparticles (V-MPLs) for eventual use for endophthalmitis prophylaxis during cataract surgery. METHODS The intraocular vancomycin concentration profile was evaluated after V-MPL injection into the anterior chamber of rabbit eyes. The toxicology of V-MPLs versus MPLs alone was tested by corneal cellular counting and retinal histology. The prophylactic efficacy of the V-MPLs was evaluated by bacterial counts after introducing contaminated intraocular lenses (IOLs) together with the V-MPLs into one anterior chamber of phakic rabbit eyes or without V-MPLs in control rabbit eyes. RESULTS Intraocular V-MPLs produced effective vancomycin concentrations over at least 6 hours. Corneal counts revealed no significant increase in dead cells. Retinal toxicity manifested as inflammation 3 hours after injection, reaching its maximum between 12 hours and 24 hours, decreasing by 48 hours, and completely disappearing at 72 hours. Inflammation was similar between V-MPLs and MPLs. Untreated eyes implanted with highly infected IOLs showed severe, reproducible endophthalmitis. No sign of infection was observed with infected IOLs and concomitant V-MPL treatment, supported by bacterial counts showing a significant decrease in colony-forming Staphylococcus epidermidis units in the anterior chamber and on the implant surfaces within 6 hours. CONCLUSIONS The present study demonstrated the release and toxicologic properties of the authors' newly developed V-MPLs in vivo. In addition, the rabbit model shows that V-MPLs are effective in reducing the risk of experimental endophthalmitis.