In vivo assessment of antimicrobial activity and toxicity of repeated 1% povidone-iodine applications vs a single 5% povidone-iodine application

Purpose:To demonstrate the noninferiority in antimicrobial effectiveness of thrice-repeated applications of 1% povidone-iodine (PI) compared with a single application of 5% PI on the ocular surface in vivo and to evaluate potential toxicity of PI to the corneal epithelium.Setting:Department of Ophthalmology, Shaare Zedek Medical Center, Jerusalem, Israel.Design:Prospective, randomized, double-blind study.Methods:Patients randomly received either a single application of 5% PI or repeated irrigations of 1% PI on the ocular surface preoperatively. Bacterial colony counts were quantitatively analyzed by taking standardized conjunctival swabs before and after irrigation, and differences in bacterial colony counts were compared between the 2 groups. The presence of superficial punctate keratopathy was evaluated in all patients by the National Eye Institute grading system.Results:The study comprised 102 eyes of 102 patients. Both 1% and 5% PI yielded a marked decrease in bacterial colonies compared with before application (P <.001). The repeated application of 1% PI showed a significantly lower bacterial count compared with the single application of 5% PI (P <.05) and resulted in significantly less damage to the corneal epithelium compared with a single 5% PI application (P <.001).Conclusions:Preoperative repeated applications of 1% PI effectively eradicated ocular surface bacteria equal to that of 5% PI with a less deleterious effect on the corneal epithelium. Our findings suggest that 1% PI may be a promising alternative to 5% PI.