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.