A protocol associating chemoprophylaxis and two-agent flash antibioprophylaxis was performed for more than two years in order to prevent postoperative endophthalmitis in elective open-globe surgery. The aim of this study is to appreciate whether antibiotic therapy is really useful as a complement to chemoprophylaxis. Three successive conjunctival scrapings were performed in the operating room: two before surgery (one before and one after conjunctival disinfection by povidone iodine), and the third one at the end of the operation. The total number of positive scrapings significantly decreased after disinfection but, some changes appeared on the final scrapings positive and negative. The risks of a positive scraping after the disinfection are greater if the scraping was initially positive. The persistence of a positive scraping after disinfection is noted in about 20% of cases. Therefore, there is a risk for microorganisms to penetrate into the eye, still present on the conjunctiva after povidone iodine. This risk is an argument to carry on the flash antibiotic therapy before surgery, in order to obtain a high intravitreal concentration of antibiotics at the precise time when the bacteria may penetrate into the eye, and to stop their multiplication.