Ta and co-workers have demonstrated that a three-day application of topical ofloxacin resulted in less conjunctival cultures obtained before and after surgery compared to an application of antibiotic given one hour prior to surgery.[3] Furthermore, the same research group showed that the contamination rate of the microsurgical knives used during surgery decreased from 26% to 5% (P = 0.028) with a three day application of ofloxacin compared to a one-hour application.[4] The goal of the current proposal is to determine if we can improve on the current standard of endophthalmitis prophylaxis at Ludwig-Maximilians-University by using topical 5% levofloxacin prior to surgery. Given that the rate of endophthalmitis is quite low, we will use conjunctival bacterial flora and anterior chamber aqueous contamination rate as surrogate markers to determine the effectiveness of topical levofloxacin in reducing or eliminating bacteria from the ocular surface at the time of the surgery. The results of this prospective-randomized control trial may radically change the current practice of endophthalmitis prophylaxis, and levofloxacin may play a critical role in preventing postoperative endophthalmitis.