Ocular Microbiology and Immunology Group
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2025 OMIG Abstract

Antimicrobial Efficacy, Ocular Surface Toxicity, and Cytokine Expression with Povidone-Iodine and Chlorhexidine

Anam Ahmed¹, Heather Durkee¹, Alison Rodriguez Leiva¹, Salomon Merikansky^1,3, Suraj Paudyal¹,
James Lai¹, Felipe Echeverri Tribin¹, Alexander Alfonso³, Jorge Maestre-Mesa³, Landon Rohowetz²,
Jean-Marie Parel^1,2, Harry W Flynn, Jr.^1-3, Nicolas A. Yannuzzi², Darlene Miller<sup>2,3

1</sup>Ophthalmic Biophysics Center, Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida; ²Anne Bates Leach Eye Center, Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida; ³Ocular Microbiology Laboratory, Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida

Purpose: To compare the antimicrobial efficacy and ocular surface toxicity of povidone-iodine (PI) and chlorhexidine (CHX) against clinical endophthalmitis isolates, and to evaluate the epithelial viability and inflammatory cytokine response following antiseptic exposure in a corneal tissue model.

Methods: A well diffusion assay was used to assess inhibition zones of PI (5%, 10%) and CHX (0.05%, 0.1%) against 20 microbial isolates, including gram-positive and gram-negative bacteria and Candida albicans. Corneal epithelial tissue models, both uninfected and infected with Staphylococcus epidermidis, were treated with antiseptics. Cell viability was measured via MTT assay. Inflammatory cytokines (IL-6, IL-8, IL-1β, TNF-α) were quantified from supernatant at 30 min, 1 hour, and 24 hours using ELISA.

Results: PI at 5% and 10% demonstrated broader antimicrobial inhibition across most isolates compared to CHX, though CHX had greater efficacy against P. aeruginosa. PI at 0.025% showed no inhibition. CHX-treated corneal tissue retained higher viability (greater percent of living cells) in both healthy and infected models (71–100%) compared to PI (9–17%). PI-treated tissue exhibited elevated inflammatory cytokines, particularly IL-8 and IL-6, with a concentration- and time-dependent increase. CHX induced minimal cytokine release; IL-1β and TNF-α were mostly undetectable in CHX-treated samples.

Conclusions: While PI demonstrated broader antimicrobial efficacy in vitro, it was associated with greater epithelial cytotoxicity and a more pronounced proinflammatory cytokine response. In contrast, CHX-treated tissue retained higher cell viability and induced minimal inflammatory signaling. These findings highlight distinct effects of the two agents on the ocular surface, suggesting that considerations for antiseptic choice could include not only microbial inhibition but also epithelial integrity and inflammatory activation.