Background/Objectives: In the context of increasing bacterial resistance and the need for effective ophthalmic antiseptics, this study evaluates the antimicrobial efficacy of Corneial MED^®, a novel ophthalmic solution containing polyhexamethylene biguanide (PHMB) and cross-linked hyaluronic acid. The study investigates the in vitro fungicidal and bactericidal properties of this solution against clinically relevant fungal and bacterial strains and its impact on conjunctival flora in vivo. Methods: The in vitro assessment included time-kill assays to determine the fungicidal or fungistatic activity against Candida albicans, Aspergillus flavus, and Aspergillus fumigatus. The bactericidal activity was evaluated against Staphylococcus aureus (methicillin-sensitive and -resistant), Staphylococcus epidermidis, Pseudomonas aeruginosa, and Escherichia coli. In vivo, 43 patients undergoing cataract surgery were treated with the solution for three days preoperatively. Results: Corneial MED^® demonstrated a fungistatic effect against C. albicans and A. fumigatus, while it exhibited limited activity against A. flavus. The tested solution effectively reduced bacterial load within minutes, outperforming competitor ophthalmic solutions in activity against P. aeruginosa and E. coli. Conjunctival swabs indicated a significant reduction in bacterial load post-treatment, confirming the solution’s efficacy in reducing potential ocular pathogens. Conclusions: These findings highlight the potential of PHMB-based antiseptic solutions as a viable alternative to traditional disinfectants, particularly for preoperative prophylaxis and infection control. Further clinical trials are needed to confirm long-term safety and efficacy. The combination with cross-linked hyaluronic acid not only enhances tolerability but also extends antimicrobial action, making it a promising candidate for ophthalmic disinfection.

Background/Objectives: Acanthamoeba keratitis (AK) is a rare but sight-threatening corneal infection, often associated with contact lens wear and resistant to conventional therapies. Preventive strategies capable of reducing Acanthamoeba adhesion to corneal epithelium may represent an important tool for infection control. This study aimed to evaluate the amebicidal and preventive activity of CORNEIAL MED eye drops against Acanthamoeba castellanii adhesion and early adhesion layer on human corneal epithelium (HCE). Methods: Reconstructed HCE models were exposed to A. castellanii under four experimental conditions: negative control (HCE only), positive control (HCE + A. castellanii), co-incubation with CORNEIAL MED and A. castellanii (Study 1), and treatment with CORNEIAL MED after initial A. castellanii adhesion (Study 2). Adherent amoebae were quantified using EDTA detachment and Neubauer chamber counting. The early adhesion layer was characterized by scanning electron microscopy (SEM). Statistical analysis considered p < 0.05 as significant. Results: In Study 1, simultaneous application of CORNEIAL MED with A. castellanii reduced amoeba adhesion by 33.0 ± 11% compared with controls (p = 0.0529). In Study 2, when the product was applied 3 h after amoeba inoculation, adhesion was significantly reduced by 51.9 ± 6.5% (p < 0.05). SEM confirmed a decrease in amoebic colonization and biofilm density in treated samples. Conclusions: CORNEIAL MED demonstrated a measurable inhibitory effect on A. castellanii adhesion to HCE, particularly when applied after initial pathogen contact. These findings suggest a potential preventive role of CORNEIAL MED in reducing AK risk, although further in vivo studies are warranted.