The Antibacterial Effect of a Preservative-free Multi-dose Eye Dropper Using Air Pressure Differentials

This study aimed to evaluate the antibacterial effects of a newly designed preservative-free multi-dose eye dropper that addresses various shortcomings found in conventional models.To thoroughly assess its performance, we compared bacterial contamination and filtration effects over time among three types of droppers: commercially available multi-dose droppers, conventional preservative-free droppers, and the newly designed preservative-free dropper utilizing air pressure differentials.The bacterial strains used to evaluate contamination included Staphylococcus aureus, Bacillus subtilis, and Aspergillus brasiliensis, with turbidity levels measured according to the McFarland Standards to ensure accuracy.In typical multi-dose eye droppers, bacterial contamination tended to increase significantly with extended usage periods, leading to potential health risks.However, in the preservative-free eye dropper using air pressure differentials, no bacterial growth was observed throughout the entire experimental period.In both forward and reverse filtration tests, the new preservative-free eye dropper successfully prevented bacteria from entering the vial and from being released to the outside through the dropper tip.Overall, this preservative-free reusable eye dropper, which relies on air pressure differentials, offers a safe, effective, and hygienic option for administering eye drops, while minimizing the side effects associated with preservatives and maintaining the sterility of the solution over time.