Antiseptic Efficacy and Ocular Surface Toxicity of Povidone-Iodine and Chlorhexidine for Endophthalmitis Isolates

Purpose: To compare the antimicrobial efficacy and ocular surface toxicity of two antiseptic agents: povidone-iodine (PI) and chlorhexidine gluconate (CHX) against clinical endophthalmitis isolates and to perform preliminary assessments of 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% and 10%) and CHX (0.05% and 0.1%) against 34 microbial isolates, including Gram-positive and Gram-negative bacteria and fungi. Additional testing was conducted using lower concentrations of PI (0.025% and 1%). Corneal epithelial tissue models, both uninfected and infected with Staphylococcus epidermidis, were treated with two antiseptic agents. Cell viability was assessed by MTT assay, and inflammatory response was evaluated by quantifying IL-8 via enzyme-linked immunosorbent assay at multiple time points. Results: PI at 5% and 10% demonstrated statistically significant broader antimicrobial inhibition across most isolates compared to CHX (P < 0.05), although 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 showed higher IL-8 proinflammatory cytokine levels, and CHX elicited minimal inflammatory response. Conclusions: PI and CHX demonstrated broad-spectrum antimicrobial activity in vitro, with PI exhibiting greater antimicrobial activity across most isolates. CHX was associated with higher corneal epithelial viability and a lower inflammatory response of measured cytokines.