Comparison of the efficacy of povidone-iodine 1.0%, 5.0%, and 10.0% irrigation combined with topical levofloxacin 0.3% as preoperative prophylaxis in cataract surgery

PURPOSE: To compare the efficacy of povidone-iodine 1.0%, 5.0%, and 10.0% in combination with topical levofloxacin 0.3% in reducing the preoperative conjunctival bacterial load before cataract surgery. SETTING: Department of Ophthalmology, Ludwig-Maximilians-University, Munich, Germany. DESIGN: Randomized clinical trial. METHODS: This study enrolled patients scheduled for cataract surgery between July 2010 and January 2011. All patients received topical levofloxacin 0.3% 4 times on the preoperative day and were randomly assigned to these study groups: Group 1 (povidone-iodine 1.0%), Group 2 (povidone iodine 5.0%), and Group 3 (povidone-iodine 10.0%). In all groups, the conjunctiva was flush irrigated with 10 mL of povidone-iodine of the respective concentration. Conjunctival specimens were obtained at 4 timepoints: baseline (no-surgery eye), before povidone-iodine irrigation, after povidone-iodine irrigation, and at the end of surgery. All specimens were inoculated onto blood and chocolate agars and into thioglycolate broth. RESULTS: The study was completed by 271 patients. In the control smear (no-surgery eye), no significant difference in positive cultures was found. After 10 mL povidone-iodine irrigation, a considerable reduction in the conjunctival bacterial load occurred in all groups. The difference in positive cultures was statistically significant between Group 1 and Group 3 (P=.024) and between Group 2 and Group 3 (P=.029). Coagulase-negative Staphylococcus was the most commonly isolated bacteria in all groups. CONCLUSION: Povidone-iodine 10.0% was more effective than povidone iodine 1.0% and 5.0% in decreasing the conjunctival bacterial load before surgery.