Purpose: Povidone-iodine 5% solution decreases the incidence of postoperative endophthalmitis when used on the eye for preoperative preparation. We sought to determine whether it also minimized conjunctival bacterial flora immediately after surgery by preventing bacteria present on the surface of the eye from entering surgical wounds.
Methods: In 42 eyes of 40 patients, at the conclusion of surgery, on an alternating basis, each patient received either a drop of a broad-spectrum antibiotic solution (polymyxin B sulfate-neomycin sulfate-gramicidin) or a 5% povidone-iodine solution in the operated-on eye. Bacterial cultures were taken before and after surgery and 24 hours later. The 38 unoperated-on eyes in the unilateral cases served as control eyes.
Results: Relative to the control group, povidone-iodine was effective in preventing an increase in the number of colony-forming units (P = .035), while the antibiotic was not. At 24 hours after surgery, the species count was lower in the eyes receiving povidone-iodine than in the antibiotic-treated eyes (P = .034) and was increased in the antibiotic group since the completion of surgery (P = .013), but was lower in the povidone-iodine and antibiotic groups than in the control eyes for both groups (P < .01).
Conclusions: Povidone-iodine 5% solution applied to the eye at the conclusion of surgery was more effective at minimizing the number of colony-forming units and species for the first postoperative day than was a broad-spectrum antibiotic. While not true for the antibiotic, the antimicrobial effect of povidone-iodine lasted for at least 24 hours after the completion of surgery.