What is required for a preservative to be effective in contact lens solutions?

For a preservative to be effective in contact lens solutions, it must meet efficacy standards for killing microorganisms. This is critical because contact lens solutions are used to disinfect lenses and ensure that they are safe for use on the eyes. The main purpose of a preservative in such solutions is to prevent microbial contamination and ensure that the solution remains free of harmful bacteria, fungi, and other pathogens that could cause infections or irritations when the lenses are placed in the eye.

While other factors like odor, color, and the chemical base of a preservative may influence user experience or formulation stability, they do not directly relate to the preservative's primary function, which is antimicrobial efficacy. Therefore, the ability to effectively kill microorganisms is the most crucial requirement for a preservative in contact lens solutions.