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

To demonstrate the non-inferiority in antimicrobial effectiveness of thrice-repeated applications of 1% povidone-iodine (PI) compared to a single application of 5% PI on the ocular surface in vivo and to evaluate potential toxicity of PI to the corneal epithelium.Department of Ophthalmology, Shaare Zedek Medical Center, Jerusalem, Israel.Prospective randomized, double-blind study.Patients randomly received either a single application of 5% PI or repeated irrigations of 1% PI on the ocular surface before surgery. 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.The study comprised 102 eyes of 102 patients. Both 1% and 5% PI yielded a marked decrease in bacterial colonies compared to pre-application (P<.001). The repeated application of 1% PI showed a significantly lower bacterial count compared to the single application of 5% PI (P<.05) and resulted in significantly less damage to the corneal epithelium compared to a single 5% PI application (P<.001).Preoperative repeated applications of 1% PI effectively eradicated ocular surface bacteria equal to that of 5% PI with less deleterious impact on the corneal epithelium. Our findings suggest that 1% PI may be a promising alternative to 5% PI.