Inhibitory Effect of a Novel Ophthalmic Solution on Acanthamoeba castellanii Adhesion and Biofilm Formation on Human Corneal Epithelium

<b>Background/Objectives:</b><i>Acanthamoeba</i> 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 <i>Acanthamoeba</i> 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 <i>Acanthamoeba castellanii</i> adhesion and early adhesion layer on human corneal epithelium (HCE). <b>Methods:</b> Reconstructed HCE models were exposed to <i>A. castellanii</i> under four experimental conditions: negative control (HCE only), positive control (HCE + <i>A. castellanii</i>), co-incubation with CORNEIAL MED and <i>A. castellanii</i> (Study 1), and treatment with CORNEIAL MED after initial <i>A. castellanii</i> 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 <i>p</i> < 0.05 as significant. <b>Results:</b> In Study 1, simultaneous application of CORNEIAL MED with <i>A. castellanii</i> reduced amoeba adhesion by 33.0 ± 11% compared with controls (<i>p</i> = 0.0529). In Study 2, when the product was applied 3 h after amoeba inoculation, adhesion was significantly reduced by 51.9 ± 6.5% (<i>p</i> < 0.05). SEM confirmed a decrease in amoebic colonization and biofilm density in treated samples. <b>Conclusions:</b> CORNEIAL MED demonstrated a measurable inhibitory effect on <i>A. castellanii</i> 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.