Comparative efficacy of single and double povidone–iodine soaking protocols combined with draping sequence in donor cornea disinfection

Purpose: To evaluate the effectiveness of three povidone–iodine disinfection protocols on donor corneoscleral rim contamination and to identify factors influencing microbial contamination during corneal procurement. Design: Prospective interventional study. Methods: This single-center study at the National Eye Bank of Taiwan included 830 corneas from 440 donors. Three povidone–iodine protocols were compared: soaking after draping (single-soaking method 1 [SSM1]), soaking before draping (SSM2), and soaking both before and after draping (double-soaking method [DSM]). Corneoscleral rim cultures were obtained post-procurement, with conjunctival cultures performed before and after each disinfection step in DSM. Grafts with gentamicin-resistant isolates were re-cultured after hypothermic storage. Donor and procurement variables were analyzed for association with contamination. The primary outcome was rim contamination; secondary outcomes included conjunctival culture positivity, persistence of resistant isolates, and associated risk factors. Results: Of 830 corneas, 350 underwent SSM1, 364 SSM2, and 116 DSM. Rim contamination rates were similar (SSM1: 3.1%, SSM2: 3.0%, DSM: 2.6%; P > 0.05). In DSM, conjunctival positivity significantly decreased from 36.1% to 19.8% after double-soaking ( P < 0.001). Staphylococcus epidermidis was the most frequent isolate. One gentamicin-resistant strain was identified but did not persist after storage. No donor or procedural factors correlated with rim contamination, and no post-transplant infections occurred. Conclusion: Double-soaking significantly reduced conjunctival microbial load and showed a favorable trend toward reducing rim contamination. These findings support its use as a simple, low-risk strategy to lower ocular surface bioburden and enhance graft safety, while confirming the effectiveness of current disinfection and storage practices.