OCULAR PENETRATION OF TOPICAL CIPROFLOXACIN AND NORFLOXACIN DROPS ANDTHEIR EFFECT UPON EYELID FLORA

A double blind, prospective study was undertaken to compare aqueous hu mour penetration of topical 0.3% norfloxacin and 0.3% ciprofloxacin an d their effect upon normal eyelid flora in 39 patients undergoing cata ract surgery. Lid swabs were taken before and after six 1 hourly appli cations of single drops of ciprofloxacin or norfloxacin given before s urgery. Aqueous humour was aspirated at surgery and antibiotic concent ration assayed using high performance liquid chromatography. The mean aqueous humour concentrations were: ciprofloxacin 220 ng ml(-1), norfl oxacin 140 ng ml(-1). Although this difference was not statistically s ignificant (p = 0.112) the trend demonstrated may be relevant clinical ly, especially considering the greater activity of ciprolfloxacin. Bot h coagulase negative staphylococcal (p = 0.004) and total bacterial (p = 0.019) lid counts dropped sixfold after ciprofloxacin treatment but the smaller reductions noted after norfloxacin application did not ac hieve statistical significance (p > 0.1). The reduction of external ey e flora experienced with ciprofloxacin suggests that this may be a use ful presurgical prophylactic agent.