Purpose: To determine the rate of contamination of microsurgical knives during cataract surgery and the benefit of a 3-day versus a 1-hour preoperative application of topical ofloxacin in reducing the contamination rate.
Design: Prospective, randomized controlled trial.
Participants: Seventy-eight eyes of 75 patients were randomly assigned to control (39 eyes) or study groups (39 eyes).
Methods: All patients from both groups received 0.3% topical ofloxacin 1 hour before surgery, 5% povidone-iodine (PVI) scrub of the periorbital area, and 2 drops of PVI onto the ocular surface preoperatively. The patients in the study group also received ofloxacin 4 times a day for 3 days before surgery.
Main outcome measures: Microsurgical knives were placed in blood culture broth media immediately after the incision had been made. The number of positive cultures and types of bacteria isolated were determined.
Results: Ten of 39 knives (26%) in the control group were found to be positive for bacterial growth compared with only 2 of 39 (5%) in the study group (P = 0.028).
Conclusions: The initial paracentesis incision frequently results in contamination of the microsurgical knife and may serve as a mechanism for introducing bacteria from the ocular surface into the anterior chamber. The application of topical ofloxacin for 3 days before surgery significantly reduces the contamination rate of the microsurgical knives, compared with a preoperative application of ofloxacin given 1 hour before surgery.