Purpose: To investigate the effect of cataract surgery on the concentration of moxifloxacin in aqueous and vitreous humor after topical application.
Design: Prospective laboratory intervention using a rabbit model.
Methods: Following topical administration of 0.5% moxifloxacin, 60 minutes before surgery and immediately post cataract surgery, aqueous and vitreous humor were sampled at 30, 60, and 120 minutes postsurgery. Moxifloxacin concentrations were determined by high-pressure liquid chromatography (HPLC). Mean tissue concentrations obtained in surgical eyes were compared with concentrations obtained in nonsurgical eyes. The potential effectiveness of moxifloxacin in providing prophylaxis against intracameral bacterial inoculation was investigated by comparing antibiotic concentrations to minimum inhibitory concentration (median MIC90) values for Staphylococcus aureus and Staphylococcus epidermidis.
Results: In surgical eyes, mean moxifloxacin concentrations in aqueous were 13.9, 16.2, and 12.2 microg/ml versus 25.3, 32.6, and 15.7 microg/ml in nonoperated eyes at 30, 60, and 120 minutes, respectively. No statistically significant differences were found between surgical and nonsurgical eyes. In surgical eyes, mean moxifloxacin concentrations in vitreous were 66.8, 66.6, and 400.2 ng/ml versus 43.1, 199.8, and 54.4 ng/ml in nonoperated eyes at 30, 60, and 120 minutes, respectively. These differences were not statistically significant.
Conclusions: There were no statistically significant differences in the penetration of topical moxifloxacin in eyes undergoing cataract surgery compared with unoperated eyes. A multiple-drop schedule of moxifloxacin produced aqueous concentrations that were well above the MICs of even resistant strains of the most common organisms implicated in postcataract surgery endophthalmitis.