Effect of the ozonated oil in liposomes: they act against Staphylococcus aureus and Pseudomonas aeruginosa is among the most frequent eye pathogens and causes acute and chronic infections of the ocular surface. Staphylococcus aureus and Pseudomonas aeruginosa were tested in this study. The bacterial suspension of Staphylococcus aureus was diluted to obtain 150 CFU/ml. The bacterial suspension of Pseudomonas aeruginosa was diluted to obtain 15 CFU/ml. Various volumes of liposome-vehiculated ozonated oil were added (400 μl, 200 μl, 100 μl and 50 μl) to 100 μl of bacterial suspension; both of Staphylococcus aureus and Pseudomonas aeruginosa are incubated at 37˚C for 10 minutes. The cytotoxicity of liposome-vehiculated ozonated oil was analysed at the University of Campania "Luigi Vanvitelli", Department of Precision Medicine. The HaCaT epidermal keratinocyte cell line (ATCC, USA) was grown in Dulbecco's Modified Eagle Medium (Euroclone) with the addition of 10% foetal bovine serum (FBS) (Euroclone), 2 mM of L-glutamine (Euroclone) and antibiotics (100 U/ml penicillin, 100 g/ml streptomycin) (Euroclone). The microbiological results clearly show the antimicrobial efficacy of liposome-vehiculated ozonated oil against bacterial strains such as Staphylococcus aureus and Pseudomonas aeruginosa. Furthermore, the studies carried out in vitro on the keratinocyte line showed how ozonated oil in liposomes does not evidence any cell toxicity, and that after 3 days of treatment, it promotes cell growth compared to the positive control.